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Could you inject external gamma waves into your brain safely?

Could you inject external gamma waves into your brain safely?


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I've recently taken up the study of neurology, and I was wondering if you could create a device that would input gamma waves into your brain. And if it would be safe. Suppose you had a device that you wore sort of like a headband, and it emitted gamma waves and focused them into your brain. Would this be safe, if at low power? And would it increase focus/awareness?


I am fairly certain that the question is not about electromagnetic gamma light radiation, but rather about the gamma frequency brain waves. While we do not "inject gamma waves" we can stimulate brain activity at gamma level frequencies through the use of sensory stimulation that occurs at such a frequency. There has been research done with people who have Alzheimer's and the use of lights that turn off and on at the same frequency as Gamma waves.

Here are the respective wikipedia articles that concern gamma waves vs gamma rays respectively https://en.wikipedia.org/wiki/Gamma_wave vs https://en.wikipedia.org/wiki/Gamma_ray#:~:text=A%20gamma%20ray%2C%20or%20gamma,imparts%20the%20highest%20photon%20energy.

I found the following articles about the use of gamma frequency stimulation in Alzheimer patients.

Here is a link to an article: https://www.nia.nih.gov/news/noninvasive-brain-wave-treatment-reduces-alzheimers-pathology-improves-memory-mice#:~:text=Previously%2C%20researchers%20at%20the%20Massachusetts,also%20boosted%20the%20activity%20of Noninvasive brain wave treatment reduces Alzheimer's pathology, improves memory in mice

Here is an article that mentions the use of sound waves at a gamma frequency too.

https://www.alzforum.org/news/research-news/flash-beep-gamma-waves-stimulate-microglia-memory Flash! Beep! Gamma Waves Stimulate Microglia, Memory


Q: Could you inject external gamma waves into your brain safely?

A: Yes, nowdays we can inject external gamma waves into the brain safely, and the procedure has been done routinely in many advanced neuroradiosurgical clinics for decades now - it's called Gamma Knife or Gamma Knife Radiosurgery.

But the procedure isn't done to increase focus or awareness - there's no theoretical background or experimental evidence for that. Instead, the procedure is done to precisely remove a pathologic lesion, such as tumor, arterovenous malformation, and epileptic focus.

This procedure is the procedure of choice when the conventional neurosurgery cannot be performed due to fact that the lesion is too deep down in the brain or too near a vital structure (such as in the middle of the brainstem) or that the patient's age or medical conditon wouldn't allow a conventional neurosurgical procedure.

References:

  1. Gamma Knife

  2. Gamma Knife Radiosurgery


Safety Concerns with Implantable Infusion Pumps in the Magnetic Resonance (MR) Environment: FDA Safety Communication

Cardiology, Emergency Medicine, General Surgeons, Magnetic Resonance Technologists, Neurosurgeons, Neurologists, Nurses and Nurse Practitioners, Orthopedic Surgeons, Physician Assistants, Primary Care Physicians, Radiologists

Devices:

Implantable infusion pumps are devices that are surgically implanted under the skin, typically in the abdominal region. They are connected to an implanted catheter and are used to deliver medications and fluids within the body. Implantable infusion pumps are periodically refilled with medications or fluids by a health care provider. Implantable infusion pumps may be used to treat chronic pain, muscle spasticity, and many other diseases or conditions.

Magnetic Resonance Imaging (MRI) is a medical diagnostic exam that creates images of the internal structures of the body by using strong magnetic fields and radio waves (radiofrequency energy). These images provide information to physicians and can be useful in diagnosing a wide variety of diseases and conditions. Some medical devices, including some implantable infusion pumps, can be affected by the strong magnetic fields associated with MRI.

Purpose:

The FDA is informing patients, caregivers, MR technologists, and health care providers of important safety precautions to help patients with implantable infusion pumps safely have an MRI exam.

Summary of Problem and Scope:

The FDA has received reports of serious adverse events, including patient injury and death, associated with the use of implantable infusion pumps in the MR environment. These reports describe medication dosing inaccuracies (e.g., over-infusion or under-infusion, unintended bolus) and other mechanical problems with the pump (e.g., motor stall, pump not restarting after an MRI exam).

MRI systems provide images of the internal structures of the body that can be useful in diagnosing a wide variety of diseases and conditions. However, the MR environment presents safety hazards for patients with implantable infusion pumps. Only implantable infusion pumps labeled as MR Conditional may be used safely within an MR environment, and only under the specified conditions of safe use. The specific conditions that health care practitioners and patients should follow before, during, and after the MRI exam vary by the make and model of the implantable infusion pump system. Importantly, each implantable pump model may have unique conditions that must be followed in order for a patient to safely undergo an MRI exam. Failure to adhere to these conditions can result in serious injury or death.

The benefits and risks of an MRI exam must be considered for each patient. The value of the information to be gained from the MRI exam should be weighed against the risks of the exam. All medical devices present in the MR environment during the exam (including implants, external devices and accessory devices) should be considered.

Recommendations:

To help reduce the likelihood of serious adverse events, FDA recommends the following before, during, and after a patient with an implantable infusion pump has an MRI exam:

Patients with implantable infusion pumps and their caregivers:

  • Be aware that specific instructions must be followed by your health care providers and MR technologist before, during, and after an MRI exam. These instructions may differ by manufacturer and model of the pump.
  • If you are scheduled for an MRI, make sure your physicians and the MR technologist know that you have an implantable infusion pump.
  • Be able to identify the make and model of your implantable infusion pump. Most patients are provided with an "implant card" that lists this information.
  • Bring the implant card for your implantable infusion pump with you when you go for your MRI exam. Before you can safely have an MRI exam, your health care team will need to identify your specific pump model to locate the specific MRI safety information for your pump. If there are any questions about the make and model of implantable infusion pump you have, contact the physician who manages your pump and do not have the MRI exam until the specific implantable pump model is identified.
  • Consider obtaining a medical alert bracelet or necklace in case of an emergency situation. Include information to notify medical professionals that you have an implantable pump and that MRI precautions need to be followed.
  • Be aware that MRI exams may affect the function or programming of your infusion pump, even when the specified conditions of MR Conditional use have been followed. For example, your implantable pump may need to be checked and/or reprogrammed by your physician before and after your MRI.
  • Only implantable infusion pumps labeled as MR Conditional may be safely scanned, and only under the specific conditions of safe use. Consult with your physician and the MR technologist to determine whether it is safe for you to have an MRI.

MRI Technologists:

  • Be aware of and follow the policies and procedures at your site for patient screening prior to MRI exposure. Be sure all patients are screened for implantable devices such as implantable infusion pumps.
  • Do NOT scan the patient until the pump model has been positively identified and instructions for safe MRI exposure are understood. Before scanning a patient with an implantable infusion pump, ask the patient for their implant card to confirm the pump model. If there are any questions about the specific pump model a patient has, contact the health care provider managing the pump.
  • Only implantable infusion pumps labeled as MR Conditional may be safely scanned, and only under the specific conditions of safe use. Contact the implantable infusion pump manufacturer if there are any questions about the MRI safety status of the implantable pump system.
  • Be aware that the steps that must be followed before, during, and after an MRI exam may be different for each manufacturer and model of pump. Be sure to verify that the conditions of safe MRI use can be followed prior to scanning the patient.
  • Ensure that the MRI system at your site meets all conditions provided in the MR Conditional labeling of the implantable pump. For example, some implantable pump models can be safely imaged only at 1.5 tesla (T), but not 3T. (Tesla or "T" is a measure of magnetic field strength.)

Radiologists:

  • Consider the benefits and risks of an MRI exam for each patient and weigh the value of the information gained from the magnetic resonance images against the risks of the exam for the patient. All medical devices present in the MR environment during the exam (including implants, external devices and accessory devices) should be included in the risk assessment.
  • Only implantable infusion pumps labeled MR Conditional may be safely scanned, and only under the specified conditions of safe use. Contact the implantable infusion pump manufacturer if there are any questions about the MRI safety status of the implantable pump system.

Health Care Providers who implant infusion pumps:

  • When selecting the appropriate pump for each patient, please be aware that only patients implanted with MR Conditional pumps can safely undergo MRI exams, and only under very specific conditions of safe use. The conditions of safe MRI use may differ by manufacturer and model of the pump. This information should be discussed with the patient before and after the pump is implanted.
  • Ensure that your patients receive and understand information about their implantable infusion pump, including how to use their patient implant card.
  • Document the implantable device identification information in the patient's medical record.

Health Care Providers who manage implantable infusion pumps:

  • Be aware that only patients implanted with MR Conditional pumps can safely undergo MRI exams, and only under the specified conditions of safe use. The conditions of safe use may differ by manufacturer and model of the pump.
  • Before ordering an MRI scan for a patient with an implantable infusion pump, determine the make and model of the implantable infusion pump and ask the patient for their implant card to confirm the pump model.
  • Only implantable infusion pumps labeled as MR Conditional may be safely scanned, and only under the specific conditions of safe use. Contact the implantable infusion pump manufacturer if there are any questions about the MRI safety status of the implantable pump system.
  • Be aware that specific instructions must be followed before, during, and after MRI exams of patients with implanted infusion pumps, and that these instructions may differ by manufacturer and model of the pump.
  • Inform your patients that they should notify you before having an MRI exam that another health care provider orders. MRI exams may affect the function or programming of the implantable infusion pump. For example:
    • Some pump models may automatically stop delivering medication during the MRI exam, and some may need to be reprogrammed before and/or after the exam. Depending on the medication delivered by the implantable pump, alternative drug therapy may need to be considered to prevent drug withdrawal.
    • Some pump models may need to be completely emptied of drug prior to the MRI exam to prevent unintended over delivery of medication and drug overdose.

    Health Care Providers that prescribe MRI Exams:

    • Be aware that only patients implanted with MR Conditional pumps can safely undergo MRI exams, and only under specified conditions of safe use. The conditions may differ by manufacturer and model of the pump.
    • You should ask all of your patients if they have any implantable pumps or other implants when determining whether an MRI exam is safe for them.
    • Before ordering an MRI scan for a patient with an implantable infusion pump, determine the make and model of the implantable infusion pump and ask the patient for their implant card to confirm the pump model. If there are any questions about the specific pump make and model a patient has, contact the health care provider managing the pump.
    • Only implantable infusion pumps labeled as MR Conditional may be safely scanned, and only under the specific conditions of safe use. Contact the implantable infusion pump manufacturer if there are any questions about for the MRI safety status of the implantable pump system.
    • Consider the benefits and risks of an MRI exam and weigh the value of the information to be gained from the MRI exam against the risks of the exam for the patient. All medical devices present in the MR environment during the exam (including implants, external devices and accessory devices) should be included in the risk assessment.
    • If needed, consult with a radiologist to determine if the MRI exam will deliver the expected benefits. For example, under some circumstances, artifacts from the pump may compromise the quality of acquired images.
    • Ensure that care for your patient is coordinated between you, the physician who manages the implantable pump, and the facility that will perform the MRI exam.

    FDA Activities:

    Before an implantable infusion pump is introduced into clinical use, the FDA reviews evidence supporting the safe and effective use of that pump. This review may include evidence supporting the MR Conditional labeling. After an implantable infusion pump is approved for clinical use, the FDA monitors adverse events related to the pump.

    An analysis of adverse event information and manufacturer labeling alerted the FDA to a potential safety problem with the use of implantable infusion pumps in the MR environment. The FDA is working with the applicable manufacturers to update MRI safety information in their labeling to ensure that instructions for the safe use of these devices are clear and up-to-date with current terminology and definitions.

    Reporting Problems to the FDA:

    Prompt reporting of adverse events can help the FDA identify and better understand the risks associated with medical devices. If you suspect an implantable pump of having problems during an MRI exam, we encourage you to file a voluntary report through MedWatch, the FDA Safety Information and Adverse Event Reporting program.

    Device manufacturers and user facilities must comply with the applicable Medical Device Reporting (MDR) regulations.

    Health care personnel employed by facilities that are subject to the FDA's user facility reporting requirements should follow the reporting procedures established by their facilities.


    Background

    Alzheimer’s disease (AD) is the most prevalent form of dementia in the elderly [1, 2]. The hallmarks of AD include senile plaques, composed primarily of amyloid-beta (Aβ) protein, as well as neurofibrillary tangles and memory loss [3,4,5]. Clinical trials of potential therapies for AD have thus far met with very limited success [3, 6, 7]. Therefore, there is still much research interest in establishing methods to diagnose and prevent AD before the onset of the irreversible deterioration phase of the disease. Although the primary sensory centers of the brain are minimally affected [8], patients with early-stage AD exhibit olfactory perceptual deficits, often coinciding with, or preceding, the manifestation of classical cognitive impairments such as memory loss [9,10,11,12,13]. Thus, one potential approach to the early diagnosis of AD would be to detect the olfactory sensory dysfunction in combination with neuropsychological measures involving affective changes [14, 15].

    In the olfactory system, odor is first received by olfactory sensory neurons (OSNs) located in the olfactory epithelium (OE) [16, 17]. After the OSNs convert the chemical signal of the odorant into electrical potential, odor information is transferred to the olfactory bulb (OB) where it is encoded by OB output neurons, mitral/tufted (M/T) cells, and then sent to highly plastic olfactory cortical areas, including the piriform cortex (PC) [18, 19]. AD pathogenic factors, including Aβ aggregation, have been found within the OE, OB and PC in both AD patients and AD rodent models [20,21,22,23]. It is now evident that patients with early-stage AD often have a reduced ability to detect, discriminate, and identify odors, coupled with abnormal odor coding [9, 24, 25]. However, potential olfactory biomarkers and the precise neural mechanisms underlying the olfactory deficits in early AD remain poorly understood. Therefore, the usefulness of olfactory screens as an approach to AD diagnosis is hampered by a lack of knowledge on how and when AD pathogenesis impacts olfaction.

    Gamma oscillations (40–100 Hz), resulting from activation of excitatory and fast-spiking inhibitory local circuits, have been shown to be necessary for higher cognitive functions and sensory procession [26,27,28]. Gamma rhythms recruit both neuronal and glial responses to attenuate AD-associated pathology [26, 29] and improve cognition [30], suggesting they could play an important role in AD pathogenesis and treatment. As the first relay of the olfactory system, proper gamma oscillations in the OB are required for odor discrimination and odor learning [27, 31]. Though aberrant gamma rhythms are known to occur in the OB of a Swedish mutation AD model, Tg2576 mice, and OB slices of APP/PS1 mice at ages before Aβ deposition [23, 32], the mechanism and relationship between altered gamma oscillations and local- or long-range-circuitry pathology remain unclear.

    In the present study, impaired olfactory detection occurred in 3–5 month-old AD mouse models, including APP/PS1 and 3xTg mice, accompanied by increased gamma oscillations, which may be attributed to a disturbance in the excitation/inhibition (E/I) ratio of OB. Moreover, we discovered that abnormal number of OSNs and subsequent OE → OB excitation, altered glutamatergic- and GABAergic-synaptic transmission and levels of GABAARs underlie aberrant gamma oscillations. Furthermore, an increase in levels of GABA in the synaptic cleft by blockade of GABA-uptake transporter 1 (GAT1) with tiagabine (TGB), an anti-convulsive medication, attenuated aberrant gamma oscillations in both APP/PS1 and 3xTg mice. The results highlight the potential for the early diagnosis of AD by identification of altered olfactory perception with aberrant gamma oscillatory activity and levels of GABA receptors, and the use of an anti-convulsant medicine, TGB, in the treatment of certain symptoms of early AD. Evidence reviewed here in the context of the emergence of other typical pathological changes in AD suggests that olfactory impairments could be probed to understand the molecular mechanisms involved in the early phases of the pathology.


    Contents

    Classically, ARS is divided into three main presentations: hematopoietic, gastrointestinal, and neurovascular. These syndromes may be preceded by a prodrome. [3] The speed of symptom onset is related to radiation exposure, with greater doses resulting in a shorter delay in symptom onset. [3] These presentations presume whole-body exposure, and many of them are markers that are invalid if the entire body has not been exposed. Each syndrome requires that the tissue showing the syndrome itself be exposed (e.g., gastrointestinal syndrome is not seen if the stomach and intestines are not exposed to radiation). Some areas affected are:

    1. Hematopoietic. This syndrome is marked by a drop in the number of blood cells, called aplastic anemia. This may result in infections, due to a low number of white blood cells, bleeding, due to a lack of platelets, and anemia, due to too few red blood cells in circulation. [3] These changes can be detected by blood tests after receiving a whole-body acute dose as low as 0.25 grays (25 rad), though they might never be felt by the patient if the dose is below 1 gray (100 rad). Conventional trauma and burns resulting from a bomb blast are complicated by the poor wound healing caused by hematopoietic syndrome, increasing mortality.
    2. Gastrointestinal. This syndrome often follows absorbed doses of 6–30 grays (600–3,000 rad). [3] The signs and symptoms of this form of radiation injury include nausea, vomiting, loss of appetite, and abdominal pain. [10] Vomiting in this time-frame is a marker for whole body exposures that are in the fatal range above 4 grays (400 rad). Without exotic treatment such as bone marrow transplant, death with this dose is common, [3] due generally more to infection than gastrointestinal dysfunction.
    3. Neurovascular. This syndrome typically occurs at absorbed doses greater than 30 grays (3,000 rad), though it may occur at 10 grays (1,000 rad). [3] It presents with neurological symptoms like dizziness, headache, or decreased level of consciousness, occurring within minutes to a few hours, and with an absence of vomiting it is invariably fatal. [3]

    Early symptoms of ARS typically include nausea and vomiting, headaches, fatigue, fever, and a short period of skin reddening. [3] These symptoms may occur at radiation doses as low as 0.35 grays (35 rad). These symptoms are common to many illnesses, and may not, by themselves, indicate acute radiation sickness. [3]

    Dose effects Edit

    Phase Symptom Whole-body absorbed dose (Gy)
    1–2 Gy 2–6 Gy 6–8 Gy 8–30 Gy > 30 Gy
    Immediate Nausea and vomiting 5–50% 50–100% 75–100% 90–100% 100%
    Time of onset 2–6 h 1–2 h 10–60 min < 10 min Minutes
    Duration < 24 h 24–48 h < 48 h < 48 h N/A (patients die in < 48 h)
    Diarrhea None None to mild (< 10%) Heavy (> 10%) Heavy (> 95%) Heavy (100%)
    Time of onset 3–8 h 1–3 h < 1 h < 1 h
    Headache Slight Mild to moderate (50%) Moderate (80%) Severe (80–90%) Severe (100%)
    Time of onset 4–24 h 3–4 h 1–2 h < 1 h
    Fever None Moderate increase (10–100%) Moderate to severe (100%) Severe (100%) Severe (100%)
    Time of onset 1–3 h < 1 h < 1 h < 1 h
    CNS function No impairment Cognitive impairment 6–20 h Cognitive impairment > 24 h Rapid incapacitation Seizures, tremor, ataxia, lethargy
    Latent period 28–31 days 7–28 days < 7 days None None
    Illness Mild to moderate Leukopenia
    Fatigue
    Weakness
    Moderate to severe Leukopenia
    Purpura
    Hemorrhage
    Infections
    Alopecia after 3 Gy
    Severe leukopenia
    High fever
    Diarrhea
    Vomiting
    Dizziness and disorientation
    Hypotension
    Electrolyte disturbance
    Nausea
    Vomiting
    Severe diarrhea
    High fever
    Electrolyte disturbance
    Shock
    N/A (patients die in < 48h)
    Mortality Without care 0–5% 5–95% 95–100% 100% 100%
    With care 0–5% 5–50% 50–100% 99–100% 100%
    Death 6–8 weeks 4–6 weeks 2–4 weeks 2 days – 2 weeks 1–2 days
    Table source [11]

    A person who happened to be less than 1 mile (1.6 km) from the atomic bomb Little Boy's hypocenter at Hiroshima, Japan was found to absorb about 9.46 grays (Gy). [12] [13] [14] [15]

    The doses at the hypocenters of the Hiroshima and Nagasaki atomic bombings were 240 and 290 Gy, respectively. [16]

    Skin changes Edit

    Cutaneous radiation syndrome (CRS) refers to the skin symptoms of radiation exposure. [1] Within a few hours after irradiation, a transient and inconsistent redness (associated with itching) can occur. Then, a latent phase may occur and last from a few days up to several weeks, when intense reddening, blistering, and ulceration of the irradiated site is visible. In most cases, healing occurs by regenerative means however, very large skin doses can cause permanent hair loss, damaged sebaceous and sweat glands, atrophy, fibrosis (mostly keloids), decreased or increased skin pigmentation, and ulceration or necrosis of the exposed tissue. [1] Notably, as seen at Chernobyl, when skin is irradiated with high energy beta particles, moist desquamation (peeling of skin) and similar early effects can heal, only to be followed by the collapse of the dermal vascular system after two months, resulting in the loss of the full thickness of the exposed skin. [19] This effect had been demonstrated previously with pig skin using high energy beta sources at the Churchill Hospital Research Institute, in Oxford. [20]

    ARS is caused by exposure to a large dose of ionizing radiation (>

    0.1 Gy) over a short period of time (>

    0.1 Gy/h). Alpha and beta radiation have low penetrating power and are unlikely to affect vital internal organs from outside the body. Any type of ionizing radiation can cause burns, but alpha and beta radiation can only do so if radioactive contamination or nuclear fallout is deposited on the individual's skin or clothing. Gamma and neutron radiation can travel much greater distances and penetrate the body easily, so whole-body irradiation generally causes ARS before skin effects are evident. Local gamma irradiation can cause skin effects without any sickness. In the early twentieth century, radiographers would commonly calibrate their machines by irradiating their own hands and measuring the time to onset of erythema. [25]

    Accidental Edit

    Accidental exposure may be the result of a criticality or radiotherapy accident. There have been numerous criticality accidents dating back to atomic testing during World War II, while computer-controlled radiation therapy machines such as Therac-25 played a major part in radiotherapy accidents. The latter of the two is caused by the failure of equipment software used to monitor the radiational dose given. Human error has played a large part in accidental exposure incidents, including some of the criticality accidents, and larger scale events such as the Chernobyl disaster. Other events have to do with orphan sources, in which radioactive material is unknowingly kept, sold, or stolen. The Goiânia accident is an example, where a forgotten radioactive source was taken from a hospital, resulting in the deaths of 4 people from ARS. [26] Theft and attempted theft of radioactive material by clueless thieves has also led to lethal exposure in at least one incident.

    Exposure may also come from routine spaceflight and solar flares that result in radiation effects on earth in the form of solar storms. During spaceflight, astronauts are exposed to both galactic cosmic radiation (GCR) and solar particle event (SPE) radiation. The exposure particularly occurs during flights beyond low Earth orbit (LEO). Evidence indicates past SPE radiation levels that would have been lethal for unprotected astronauts. [27] GCR levels that might lead to acute radiation poisoning are less well understood. [28] The latter cause is rarer, with an event possibly occurring during the solar storm of 1859.

    Intentional Edit

    Intentional exposure is controversial as it involves the use of nuclear weapons, human experiments, or is given to a victim in an act of murder. The intentional atomic bombings of Hiroshima and Nagasaki resulted in tens of thousands of casualties the survivors of these bombings are known today as Hibakusha. Nuclear weapons emit large amounts of thermal radiation as visible, infrared, and ultraviolet light, to which the atmosphere is largely transparent. This event is also known as "Flash", where radiant heat and light are bombarded into any given victim's exposed skin, causing radiation burns. [29] Death is highly likely, and radiation poisoning is almost certain if one is caught in the open with no terrain or building masking-effects within a radius of 0–3 km from a 1 megaton airburst. The 50% chance of death from the blast extends out to

    8 km from a 1 megaton atmospheric explosion. [30]

    Scientific testing on humans done without consent has been prohibited since 1997 in the United States. There is now a requirement for patients to give informed consent, and to be notified if experiments were classified. [31] Across the world, the Soviet nuclear program involved human experiments on a large scale, which is still kept secret by the Russian government and the Rosatom agency. [32] [33] The human experiments that fall under intentional ARS exclude those that involved long term exposure. Criminal activity has involved murder and attempted murder carried out through abrupt victim contact with a radioactive substance such as polonium or plutonium.

    The most commonly used predictor of ARS is the whole-body absorbed dose. Several related quantities, such as the equivalent dose, effective dose, and committed dose, are used to gauge long-term stochastic biological effects such as cancer incidence, but they are not designed to evaluate ARS. [34] To help avoid confusion between these quantities, absorbed dose is measured in units of grays (in SI, unit symbol Gy) or rads (in CGS), while the others are measured in sieverts (in SI, unit symbol Sv) or rems (in CGS). 1 rad = 0.01 Gy and 1 rem = 0.01 Sv. [35]

    In most of the acute exposure scenarios that lead to radiation sickness, the bulk of the radiation is external whole-body gamma, in which case the absorbed, equivalent, and effective doses are all equal. There are exceptions, such as the Therac-25 accidents and the 1958 Cecil Kelley criticality accident, where the absorbed doses in Gy or rad are the only useful quantities, because of the targeted nature of the exposure to the body.

    Radiotherapy treatments are typically prescribed in terms of the local absorbed dose, which might be 60 Gy or higher. The dose is fractionated to about 2 Gy per day for "curative" treatment, which allows normal tissues to undergo repair, allowing them to tolerate a higher dose than would otherwise be expected. The dose to the targeted tissue mass must be averaged over the entire body mass, most of which receives negligible radiation, to arrive at a whole-body absorbed dose that can be compared to the table above. [ citation needed ]

    DNA damage Edit

    Exposure to high doses of radiation cause DNA damage, later creating serious and even lethal chromosomal aberrations if left unrepaired. Ionizing radiation can produce reactive oxygen species, and does directly damage cells by causing localized ionization events. The former is very damaging to DNA, while the latter events create clusters of DNA damage. [36] [37] This damage includes loss of nucleobases and breakage of the sugar-phosphate backbone that binds to the nucleobases. The DNA organization at the level of histones, nucleosomes, and chromatin also affects its susceptibility to radiation damage. [38] Clustered damage, defined as at least two lesions within a helical turn, is especially harmful. [37] While DNA damage happens frequently and naturally in the cell from endogenous sources, clustered damage is a unique effect of radiation exposure. [39] Clustered damage takes longer to repair than isolated breakages, and is less likely to be repaired at all. [40] Larger radiation doses are more prone to cause tighter clustering of damage, and closely localized damage is increasingly less likely to be repaired. [37]

    Somatic mutations cannot be passed down from parent to offspring, but these mutations can propagate in cell lines within an organism. Radiation damage can also cause chromosome and chromatid aberrations, and their effects depend on in which stage of the mitotic cycle the cell is when the irradiation occurs. If the cell is in interphase, while it is still a single strand of chromatin, the damage will be replicated during the S1 phase of cell cycle, and there will be a break on both chromosome arms the damage then will be apparent in both daughter cells. If the irradiation occurs after replication, only one arm will bear the damage this damage will be apparent in only one daughter cell. A damaged chromosome may cyclize, binding to another chromosome, or to itself. [41]

    Diagnosis is typically made based on a history of significant radiation exposure and suitable clinical findings. [3] An absolute lymphocyte count can give a rough estimate of radiation exposure. [3] Time from exposure to vomiting can also give estimates of exposure levels if they are less than 10 Gray (1000 rad). [3]

    A guiding principle of radiation safety is as low as reasonably achievable (ALARA). [42] This means try to avoid exposure as much as possible and includes the three components of time, distance, and shielding. [42]

    Time Edit

    The longer that humans are subjected to radiation the larger the dose will be. The advice in the nuclear war manual entitled Nuclear War Survival Skills published by Cresson Kearny in the U.S. was that if one needed to leave the shelter then this should be done as rapidly as possible to minimize exposure. [43]

    In chapter 12, he states that "[q]uickly putting or dumping wastes outside is not hazardous once fallout is no longer being deposited. For example, assume the shelter is in an area of heavy fallout and the dose rate outside is 400 roentgen (R) per hour, enough to give a potentially fatal dose in about an hour to a person exposed in the open. If a person needs to be exposed for only 10 seconds to dump a bucket, in this 1/360 of an hour he will receive a dose of only about 1 R. Under war conditions, an additional 1-R dose is of little concern." In peacetime, radiation workers are taught to work as quickly as possible when performing a task that exposes them to radiation. For instance, the recovery of a radioactive source should be done as quickly as possible. [ citation needed ]

    Shielding Edit

    Matter attenuates radiation in most cases, so placing any mass (e.g., lead, dirt, sandbags, vehicles, water, even air) between humans and the source will reduce the radiation dose. This is not always the case, however care should be taken when constructing shielding for a specific purpose. For example, although high atomic number materials are very effective in shielding photons, using them to shield beta particles may cause higher radiation exposure due to the production of bremsstrahlung x-rays, and hence low atomic number materials are recommended. Also, using material with a high neutron activation cross section to shield neutrons will result in the shielding material itself becoming radioactive and hence more dangerous than if it were not present. [ citation needed ]

    There are many types of shielding strategies that can be used to reduce the effects of radiation exposure. Internal contamination protective equipment such as respirators are used to prevent internal deposition as a result of inhalation and ingestion of radioactive material. Dermal protective equipment, which protects against external contamination, provides shielding to prevent radioactive material from being deposited on external structures. [44] While these protective measures do provide a barrier from radioactive material deposition, they do not shield from externally penetrating gamma radiation. This leaves anyone exposed to penetrating gamma rays at high risk of ARS.

    Naturally, shielding the entire body from high energy gamma radiation is optimal, but the required mass to provide adequate attenuation makes functional movement nearly impossible. In the event of a radiation catastrophe, medical and security personnel need mobile protection equipment in order to safely assist in containment, evacuation, and many other necessary public safety objectives.

    Research has been done exploring the feasibility of partial body shielding, a radiation protection strategy that provides adequate attenuation to only the most radio-sensitive organs and tissues inside the body. Irreversible stem cell damage in the bone marrow is the first life-threatening effect of intense radiation exposure and therefore one of the most important bodily elements to protect. Due to the regenerative property of hematopoietic stem cells, it is only necessary to protect enough bone marrow to repopulate the exposed areas of the body with the shielded supply. [45] This concept allows for the development of lightweight mobile radiation protection equipment, which provides adequate protection, deferring the onset of ARS to much higher exposure doses. One example of such equipment is the 360 gamma, a radiation protection belt that applies selective shielding to protect the bone marrow stored in the pelvic area as well as other radio sensitive organs in the abdominal region without hindering functional mobility.

    Reduction of incorporation Edit

    Where radioactive contamination is present, an elastomeric respirator, dust mask, or good hygiene practices may offer protection, depending on the nature of the contaminant. Potassium iodide (KI) tablets can reduce the risk of cancer in some situations due to slower uptake of ambient radioiodine. Although this does not protect any organ other than the thyroid gland, their effectiveness is still highly dependent on the time of ingestion, which would protect the gland for the duration of a twenty-four-hour period. They do not prevent ARS as they provide no shielding from other environmental radionuclides. [46]

    Fractionation of dose Edit

    If an intentional dose is broken up into a number of smaller doses, with time allowed for recovery between irradiations, the same total dose causes less cell death. Even without interruptions, a reduction in dose rate below 0.1 Gy/h also tends to reduce cell death. [34] This technique is routinely used in radiotherapy. [ citation needed ]

    The human body contains many types of cells and a human can be killed by the loss of a single type of cells in a vital organ. For many short term radiation deaths (3–30 days), the loss of two important types of cells that are constantly being regenerated causes death. The loss of cells forming blood cells (bone marrow) and the cells in the digestive system (microvilli, which form part of the wall of the intestines) is fatal. [ citation needed ]


    Side effects. There has not been enough research to uncover the side effects of GABA supplements.

    Risks. Overall, there isn't enough information to be sure about the safety of GABA. For this reason, it's best to play it safe and not use GABA if you are pregnant or breastfeeding.

    Interactions. Not enough is known about how GABA may interact with drugs, foods, or other herbs and supplements, but use with caution if taking with blood pressure medications.

    Be sure to tell your doctor about any supplements you're taking, even if they're natural. That way, your doctor can check on any potential side effects or interactions with medications, foods, or other herbs and supplements. They can let you know if the supplement might raise your risks.

    The U.S. Food and Drug Administration (FDA) does regulate dietary supplements however, it treats them like foods rather than medications. Unlike drug manufacturers, the makers of supplements don’t have to show their products are safe or effective before selling them on the market.

    Sources

    Virginia Commonwealth University: "The Role of GABA in the Pathogenesis and Treatment of Anxiety and Other Neuropsychiatric Disorders."

    Linus Pauling Institute: "Neurotransmitter Synthesis."

    Natural Medicines Comprehensive Database: "GABA (Gamma-Aminobutyric Acid)."

    Shimada M. Clinical and Experimental Hypertension. June 2009.

    Krantis A. Acta Neuropathologica, 1984.

    Enna, S. GABA, Volume 54 (Advances in Pharmacology), Academic Press, 2006.

    Amen, D. Change Your Brain, Change Your Life, Three Rivers Press, 1999.


    Is there any risk that internal radiation implants (brachytherapy) will leak or break free from where they are placed and move around my body?

    With brachytherapy, we use a needle or a catheter to insert radioactive material contained within a sealed source such as a seed, pellet, wire, or capsule. As the radioactive material inside the implants decays naturally over time, it emits radiation that deposits energy to treat nearby cancer cells. This radioactivity travels only a certain distance beyond the implant. Within a few weeks or months, the implant no longer gives off any radiation. The implants are specially tested and sealed to ensure that the encapsulated radioactive material doesn&rsquot leak, and we place them in such a way that it&rsquos highly unlikely they will move. We give people specific precautions to minimize exposure to others from the implanted radioactive material.


    How Radiation Sickness Works

    When radiation of high enough energy strikes another atom, it strips away an electron. The resulting positively charged atom is called an ion, which explains why high energy radiation is called ionizing radiation. The release of the electron produces 33 electron volts (eV) of energy, which heats the surrounding tissues and disrupts certain chemical bonds. Extremely high-energy radiation can even destroy the nuclei of atoms, releasing even more energy and causing more damage. Radiation sickness is the cumulative effect of all this damage on a human body that's been bombarded with radiation.

    Ionizing radiation comes in three flavors: alpha particles, beta particles and gamma rays. Alpha particles are the least dangerous in terms of external exposure. Each particle contains a pair of neutrons and a pair of protons. They don't penetrate very deeply into the skin, if at all -- in fact, clothing can stop alpha particles. Unfortunately, alpha particles can be inhaled or ingested, usually in the form of radon gas. Once ingested, alpha particles can be very dangerous. However, even then they don't typically cause radiation sickness -- instead, they lead to lung cancer [source: EPA].

    Beta particles are electrons that move very quickly -- that is, with a lot of energy. Beta particles travel several feet when emitted from a radioactive source, but they're blocked by most solid objects. A beta particle is about 8,000 times smaller than an alpha particle -- and that's what makes them more dangerous. Their small size allows them to penetrate clothing and skin. External exposure can cause burns and tissue damage, along with other symptoms of radiation sickness. If radioactive material enters food or water supplies or is dispersed into the air, people can inhale or ingest beta particle emitters unknowingly. Internal exposure to beta particles causes much more severe symptoms than external exposure.

    Gamma rays are the most dangerous form of ionizing radiation. These extremely high energy photons can travel through most forms of matter because they have no mass. It takes several inches of lead -- or several feet of concrete -- to effectively block gamma rays. If you're exposed to gamma rays, they pass through your entire body, affecting all of your tissues from your skin to the marrow of your bones. This causes widespread, systemic damage.

    How much radiation does it take to cause radiation sickness, and what effect does this damage have on a human body? That's next. For more detailed information on different types of radiation and where they come from, take a look at How Radiation Works.


    Time Frame

    Because building blocks of the human body such as calcium and iodine retain radiation for long periods of time, it's hard to clear the body of radiation poisoning and thus slow the damage. This is why people exposed to gamma radiation over time are more likely to develop thyroid and bone cancer.

    Generally, burns occur almost instantly while nausea, fatigue and vomiting take hours to appear after exposure. Hair loss, incontinence and bleeding may take up to a few weeks to months. Doses of more than 1 million mrem are almost certain to kill a person within a couple of weeks, while 2 million mrem can do so in hours by destroying the central nervous system.

    This article was written by a professional writer, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more, see our about us page: link below.


    Best Uses for Neurofeedback

    Now let’s take a deeper look at the most common, evidence-based uses for neurofeedback.

    1. Neurofeedback for Stress and Anxiety

    If there is one specific area where neurofeedback shines, it’s stress reduction.

    It’s useful for literally any condition that’s related to stress.

    Learning how to manage stress is one of the best things you can do for your overall health, brain function, and mental well-being.

    The typical stress-induced flight-or-fight response initiates a cascade of physiological changes you normally have no control over.

    Your heart rate and blood pressure increase, your breathing becomes fast and shallow, and blood gets directed away from your brain and into your muscles.

    Neurofeedback teaches you how to manage your brainwave activity to slow down the stress response cascade. (4)

    It’s particularly helpful for any health condition with a high correlation to stress like anxiety, high blood pressure, bruxism (teeth grinding), and digestive disorders like IBS and chronic constipation.

    2. Neurofeedback for ADHD

    The most studied use of neurofeedback is for ADHD (attention deficit hyperactivity disorder).

    It shows promise as a safe and effective drug-free treatment for children as well as adults. (5, 6)

    In a meta analysis of studies on ADHD, researchers concluded that neurofeedback effectively reduces the symptoms of inattention, impulsiveness, and hyperactivity. (7)

    One review of large-scale clinical trials found that neurofeedback therapy induces a state of relaxed attention, modulates both over and under-arousal, and works comparably to the typical stimulant medications prescribed for ADHD. (8)

    3. Neurofeedback and Depression

    D. Corydon Hammond, PhD, is a recognized authority in the field of neurotherapy.

    He has nearly 200 scientific publications to his credit and is the primary author of the recommended standards of practice for the clinical use of neurofeedback. (9)

    In a review of the current body of literature on neurofeedback for depression, he states that significant, enduring improvements occur approximately 80% of the time in patients who have a biological predisposition to depression. (10)

    Most patients notice a difference after three to six sessions, feel a very significant improvement after ten to twelve sessions, and usually complete treatment within 20 to 22 sessions.

    One study on depression found that the use of neurofeedback decreased depressive symptoms by 50%. (11)

    4. Neurofeedback for Peak Performance

    Neurofeedback is also an effective technique to enhance overall performance.

    It is used by Olympians, professional athletes, NASA astronauts, entrepreneurs, biohackers, and others who seek peak physical or mental performance. (12, 13)

    The US military uses neurofeedback to treat soldiers with PTSD and brain injuries, and for general performance enhancement. (14, 15)

    You too can use it to improve any area of your life — work, studies, relationships, health, and happiness.

    Get our BRAIN POWERUP GUIDE, free.

    5. Additional Uses for Neurofeedback

    The list of uses for neurofeedback is so long that it reads like the table of contents of a medical textbook.

    The International Society for Neuroregulation & Research has compiled a comprehensive bibliography of hundreds of scientific neurofeedback studies.

    There you’ll find links to research on the following conditions:

    • addictions
    • ADHD
    • anxiety
    • asthma
    • autism and Asperger’s
    • bipolar disorder
    • cerebral palsy
    • chemotherapy side effects
    • chronic fatigue syndrome
    • chronic pain
    • cognitive decline, including dementia
    • cognitive enhancement
    • depression
    • dissociative disorders
    • eating disorders
    • epilepsy
    • fibromyalgia
    • headaches, including migraines
    • high blood pressure
    • insomnia
    • learning disabilities
    • Lyme disease
    • memory loss
    • obsessive-compulsive disorder
    • Parkinson’s disease
    • post-traumatic stress disorder
    • restless leg syndrome
    • schizophrenia
    • stress
    • stroke
    • tinnitus
    • Tourette’s syndrome
    • traumatic brain injury

    Many studies have been conducted on the use of neurofeedback for optimal mental functioning as well.

    It’s been shown to increase creativity, memory, concentration, attention, and general well-being.

    Think more clearly, learn faster, and remember more.

    Dr. Pat | Be Brain Fit


    We're not going to go into details about the exact origins of alpha, beta and gamma radiation in this lesson.

    Animation giving an idea of the relative size and speed of alpha, beta and gamma radiation.

    For the moment we'll say that alpha and beta radiation consist of tiny particles, much smaller than an atom. They move incredibly fast, perhaps thousands of kilometres per second.

    Gamma radiation is a sort of invisible, very high-energy light.

    Alpha, beta and gamma are the first three letters of the Greek alphabet. The types of radiation are named in the order that they were discovered.


    We're not going to go into details about the exact origins of alpha, beta and gamma radiation in this lesson.

    Animation giving an idea of the relative size and speed of alpha, beta and gamma radiation.

    For the moment we'll say that alpha and beta radiation consist of tiny particles, much smaller than an atom. They move incredibly fast, perhaps thousands of kilometres per second.

    Gamma radiation is a sort of invisible, very high-energy light.

    Alpha, beta and gamma are the first three letters of the Greek alphabet. The types of radiation are named in the order that they were discovered.


    Time Frame

    Because building blocks of the human body such as calcium and iodine retain radiation for long periods of time, it's hard to clear the body of radiation poisoning and thus slow the damage. This is why people exposed to gamma radiation over time are more likely to develop thyroid and bone cancer.

    Generally, burns occur almost instantly while nausea, fatigue and vomiting take hours to appear after exposure. Hair loss, incontinence and bleeding may take up to a few weeks to months. Doses of more than 1 million mrem are almost certain to kill a person within a couple of weeks, while 2 million mrem can do so in hours by destroying the central nervous system.

    This article was written by a professional writer, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more, see our about us page: link below.


    Contents

    Classically, ARS is divided into three main presentations: hematopoietic, gastrointestinal, and neurovascular. These syndromes may be preceded by a prodrome. [3] The speed of symptom onset is related to radiation exposure, with greater doses resulting in a shorter delay in symptom onset. [3] These presentations presume whole-body exposure, and many of them are markers that are invalid if the entire body has not been exposed. Each syndrome requires that the tissue showing the syndrome itself be exposed (e.g., gastrointestinal syndrome is not seen if the stomach and intestines are not exposed to radiation). Some areas affected are:

    1. Hematopoietic. This syndrome is marked by a drop in the number of blood cells, called aplastic anemia. This may result in infections, due to a low number of white blood cells, bleeding, due to a lack of platelets, and anemia, due to too few red blood cells in circulation. [3] These changes can be detected by blood tests after receiving a whole-body acute dose as low as 0.25 grays (25 rad), though they might never be felt by the patient if the dose is below 1 gray (100 rad). Conventional trauma and burns resulting from a bomb blast are complicated by the poor wound healing caused by hematopoietic syndrome, increasing mortality.
    2. Gastrointestinal. This syndrome often follows absorbed doses of 6–30 grays (600–3,000 rad). [3] The signs and symptoms of this form of radiation injury include nausea, vomiting, loss of appetite, and abdominal pain. [10] Vomiting in this time-frame is a marker for whole body exposures that are in the fatal range above 4 grays (400 rad). Without exotic treatment such as bone marrow transplant, death with this dose is common, [3] due generally more to infection than gastrointestinal dysfunction.
    3. Neurovascular. This syndrome typically occurs at absorbed doses greater than 30 grays (3,000 rad), though it may occur at 10 grays (1,000 rad). [3] It presents with neurological symptoms like dizziness, headache, or decreased level of consciousness, occurring within minutes to a few hours, and with an absence of vomiting it is invariably fatal. [3]

    Early symptoms of ARS typically include nausea and vomiting, headaches, fatigue, fever, and a short period of skin reddening. [3] These symptoms may occur at radiation doses as low as 0.35 grays (35 rad). These symptoms are common to many illnesses, and may not, by themselves, indicate acute radiation sickness. [3]

    Dose effects Edit

    Phase Symptom Whole-body absorbed dose (Gy)
    1–2 Gy 2–6 Gy 6–8 Gy 8–30 Gy > 30 Gy
    Immediate Nausea and vomiting 5–50% 50–100% 75–100% 90–100% 100%
    Time of onset 2–6 h 1–2 h 10–60 min < 10 min Minutes
    Duration < 24 h 24–48 h < 48 h < 48 h N/A (patients die in < 48 h)
    Diarrhea None None to mild (< 10%) Heavy (> 10%) Heavy (> 95%) Heavy (100%)
    Time of onset 3–8 h 1–3 h < 1 h < 1 h
    Headache Slight Mild to moderate (50%) Moderate (80%) Severe (80–90%) Severe (100%)
    Time of onset 4–24 h 3–4 h 1–2 h < 1 h
    Fever None Moderate increase (10–100%) Moderate to severe (100%) Severe (100%) Severe (100%)
    Time of onset 1–3 h < 1 h < 1 h < 1 h
    CNS function No impairment Cognitive impairment 6–20 h Cognitive impairment > 24 h Rapid incapacitation Seizures, tremor, ataxia, lethargy
    Latent period 28–31 days 7–28 days < 7 days None None
    Illness Mild to moderate Leukopenia
    Fatigue
    Weakness
    Moderate to severe Leukopenia
    Purpura
    Hemorrhage
    Infections
    Alopecia after 3 Gy
    Severe leukopenia
    High fever
    Diarrhea
    Vomiting
    Dizziness and disorientation
    Hypotension
    Electrolyte disturbance
    Nausea
    Vomiting
    Severe diarrhea
    High fever
    Electrolyte disturbance
    Shock
    N/A (patients die in < 48h)
    Mortality Without care 0–5% 5–95% 95–100% 100% 100%
    With care 0–5% 5–50% 50–100% 99–100% 100%
    Death 6–8 weeks 4–6 weeks 2–4 weeks 2 days – 2 weeks 1–2 days
    Table source [11]

    A person who happened to be less than 1 mile (1.6 km) from the atomic bomb Little Boy's hypocenter at Hiroshima, Japan was found to absorb about 9.46 grays (Gy). [12] [13] [14] [15]

    The doses at the hypocenters of the Hiroshima and Nagasaki atomic bombings were 240 and 290 Gy, respectively. [16]

    Skin changes Edit

    Cutaneous radiation syndrome (CRS) refers to the skin symptoms of radiation exposure. [1] Within a few hours after irradiation, a transient and inconsistent redness (associated with itching) can occur. Then, a latent phase may occur and last from a few days up to several weeks, when intense reddening, blistering, and ulceration of the irradiated site is visible. In most cases, healing occurs by regenerative means however, very large skin doses can cause permanent hair loss, damaged sebaceous and sweat glands, atrophy, fibrosis (mostly keloids), decreased or increased skin pigmentation, and ulceration or necrosis of the exposed tissue. [1] Notably, as seen at Chernobyl, when skin is irradiated with high energy beta particles, moist desquamation (peeling of skin) and similar early effects can heal, only to be followed by the collapse of the dermal vascular system after two months, resulting in the loss of the full thickness of the exposed skin. [19] This effect had been demonstrated previously with pig skin using high energy beta sources at the Churchill Hospital Research Institute, in Oxford. [20]

    ARS is caused by exposure to a large dose of ionizing radiation (>

    0.1 Gy) over a short period of time (>

    0.1 Gy/h). Alpha and beta radiation have low penetrating power and are unlikely to affect vital internal organs from outside the body. Any type of ionizing radiation can cause burns, but alpha and beta radiation can only do so if radioactive contamination or nuclear fallout is deposited on the individual's skin or clothing. Gamma and neutron radiation can travel much greater distances and penetrate the body easily, so whole-body irradiation generally causes ARS before skin effects are evident. Local gamma irradiation can cause skin effects without any sickness. In the early twentieth century, radiographers would commonly calibrate their machines by irradiating their own hands and measuring the time to onset of erythema. [25]

    Accidental Edit

    Accidental exposure may be the result of a criticality or radiotherapy accident. There have been numerous criticality accidents dating back to atomic testing during World War II, while computer-controlled radiation therapy machines such as Therac-25 played a major part in radiotherapy accidents. The latter of the two is caused by the failure of equipment software used to monitor the radiational dose given. Human error has played a large part in accidental exposure incidents, including some of the criticality accidents, and larger scale events such as the Chernobyl disaster. Other events have to do with orphan sources, in which radioactive material is unknowingly kept, sold, or stolen. The Goiânia accident is an example, where a forgotten radioactive source was taken from a hospital, resulting in the deaths of 4 people from ARS. [26] Theft and attempted theft of radioactive material by clueless thieves has also led to lethal exposure in at least one incident.

    Exposure may also come from routine spaceflight and solar flares that result in radiation effects on earth in the form of solar storms. During spaceflight, astronauts are exposed to both galactic cosmic radiation (GCR) and solar particle event (SPE) radiation. The exposure particularly occurs during flights beyond low Earth orbit (LEO). Evidence indicates past SPE radiation levels that would have been lethal for unprotected astronauts. [27] GCR levels that might lead to acute radiation poisoning are less well understood. [28] The latter cause is rarer, with an event possibly occurring during the solar storm of 1859.

    Intentional Edit

    Intentional exposure is controversial as it involves the use of nuclear weapons, human experiments, or is given to a victim in an act of murder. The intentional atomic bombings of Hiroshima and Nagasaki resulted in tens of thousands of casualties the survivors of these bombings are known today as Hibakusha. Nuclear weapons emit large amounts of thermal radiation as visible, infrared, and ultraviolet light, to which the atmosphere is largely transparent. This event is also known as "Flash", where radiant heat and light are bombarded into any given victim's exposed skin, causing radiation burns. [29] Death is highly likely, and radiation poisoning is almost certain if one is caught in the open with no terrain or building masking-effects within a radius of 0–3 km from a 1 megaton airburst. The 50% chance of death from the blast extends out to

    8 km from a 1 megaton atmospheric explosion. [30]

    Scientific testing on humans done without consent has been prohibited since 1997 in the United States. There is now a requirement for patients to give informed consent, and to be notified if experiments were classified. [31] Across the world, the Soviet nuclear program involved human experiments on a large scale, which is still kept secret by the Russian government and the Rosatom agency. [32] [33] The human experiments that fall under intentional ARS exclude those that involved long term exposure. Criminal activity has involved murder and attempted murder carried out through abrupt victim contact with a radioactive substance such as polonium or plutonium.

    The most commonly used predictor of ARS is the whole-body absorbed dose. Several related quantities, such as the equivalent dose, effective dose, and committed dose, are used to gauge long-term stochastic biological effects such as cancer incidence, but they are not designed to evaluate ARS. [34] To help avoid confusion between these quantities, absorbed dose is measured in units of grays (in SI, unit symbol Gy) or rads (in CGS), while the others are measured in sieverts (in SI, unit symbol Sv) or rems (in CGS). 1 rad = 0.01 Gy and 1 rem = 0.01 Sv. [35]

    In most of the acute exposure scenarios that lead to radiation sickness, the bulk of the radiation is external whole-body gamma, in which case the absorbed, equivalent, and effective doses are all equal. There are exceptions, such as the Therac-25 accidents and the 1958 Cecil Kelley criticality accident, where the absorbed doses in Gy or rad are the only useful quantities, because of the targeted nature of the exposure to the body.

    Radiotherapy treatments are typically prescribed in terms of the local absorbed dose, which might be 60 Gy or higher. The dose is fractionated to about 2 Gy per day for "curative" treatment, which allows normal tissues to undergo repair, allowing them to tolerate a higher dose than would otherwise be expected. The dose to the targeted tissue mass must be averaged over the entire body mass, most of which receives negligible radiation, to arrive at a whole-body absorbed dose that can be compared to the table above. [ citation needed ]

    DNA damage Edit

    Exposure to high doses of radiation cause DNA damage, later creating serious and even lethal chromosomal aberrations if left unrepaired. Ionizing radiation can produce reactive oxygen species, and does directly damage cells by causing localized ionization events. The former is very damaging to DNA, while the latter events create clusters of DNA damage. [36] [37] This damage includes loss of nucleobases and breakage of the sugar-phosphate backbone that binds to the nucleobases. The DNA organization at the level of histones, nucleosomes, and chromatin also affects its susceptibility to radiation damage. [38] Clustered damage, defined as at least two lesions within a helical turn, is especially harmful. [37] While DNA damage happens frequently and naturally in the cell from endogenous sources, clustered damage is a unique effect of radiation exposure. [39] Clustered damage takes longer to repair than isolated breakages, and is less likely to be repaired at all. [40] Larger radiation doses are more prone to cause tighter clustering of damage, and closely localized damage is increasingly less likely to be repaired. [37]

    Somatic mutations cannot be passed down from parent to offspring, but these mutations can propagate in cell lines within an organism. Radiation damage can also cause chromosome and chromatid aberrations, and their effects depend on in which stage of the mitotic cycle the cell is when the irradiation occurs. If the cell is in interphase, while it is still a single strand of chromatin, the damage will be replicated during the S1 phase of cell cycle, and there will be a break on both chromosome arms the damage then will be apparent in both daughter cells. If the irradiation occurs after replication, only one arm will bear the damage this damage will be apparent in only one daughter cell. A damaged chromosome may cyclize, binding to another chromosome, or to itself. [41]

    Diagnosis is typically made based on a history of significant radiation exposure and suitable clinical findings. [3] An absolute lymphocyte count can give a rough estimate of radiation exposure. [3] Time from exposure to vomiting can also give estimates of exposure levels if they are less than 10 Gray (1000 rad). [3]

    A guiding principle of radiation safety is as low as reasonably achievable (ALARA). [42] This means try to avoid exposure as much as possible and includes the three components of time, distance, and shielding. [42]

    Time Edit

    The longer that humans are subjected to radiation the larger the dose will be. The advice in the nuclear war manual entitled Nuclear War Survival Skills published by Cresson Kearny in the U.S. was that if one needed to leave the shelter then this should be done as rapidly as possible to minimize exposure. [43]

    In chapter 12, he states that "[q]uickly putting or dumping wastes outside is not hazardous once fallout is no longer being deposited. For example, assume the shelter is in an area of heavy fallout and the dose rate outside is 400 roentgen (R) per hour, enough to give a potentially fatal dose in about an hour to a person exposed in the open. If a person needs to be exposed for only 10 seconds to dump a bucket, in this 1/360 of an hour he will receive a dose of only about 1 R. Under war conditions, an additional 1-R dose is of little concern." In peacetime, radiation workers are taught to work as quickly as possible when performing a task that exposes them to radiation. For instance, the recovery of a radioactive source should be done as quickly as possible. [ citation needed ]

    Shielding Edit

    Matter attenuates radiation in most cases, so placing any mass (e.g., lead, dirt, sandbags, vehicles, water, even air) between humans and the source will reduce the radiation dose. This is not always the case, however care should be taken when constructing shielding for a specific purpose. For example, although high atomic number materials are very effective in shielding photons, using them to shield beta particles may cause higher radiation exposure due to the production of bremsstrahlung x-rays, and hence low atomic number materials are recommended. Also, using material with a high neutron activation cross section to shield neutrons will result in the shielding material itself becoming radioactive and hence more dangerous than if it were not present. [ citation needed ]

    There are many types of shielding strategies that can be used to reduce the effects of radiation exposure. Internal contamination protective equipment such as respirators are used to prevent internal deposition as a result of inhalation and ingestion of radioactive material. Dermal protective equipment, which protects against external contamination, provides shielding to prevent radioactive material from being deposited on external structures. [44] While these protective measures do provide a barrier from radioactive material deposition, they do not shield from externally penetrating gamma radiation. This leaves anyone exposed to penetrating gamma rays at high risk of ARS.

    Naturally, shielding the entire body from high energy gamma radiation is optimal, but the required mass to provide adequate attenuation makes functional movement nearly impossible. In the event of a radiation catastrophe, medical and security personnel need mobile protection equipment in order to safely assist in containment, evacuation, and many other necessary public safety objectives.

    Research has been done exploring the feasibility of partial body shielding, a radiation protection strategy that provides adequate attenuation to only the most radio-sensitive organs and tissues inside the body. Irreversible stem cell damage in the bone marrow is the first life-threatening effect of intense radiation exposure and therefore one of the most important bodily elements to protect. Due to the regenerative property of hematopoietic stem cells, it is only necessary to protect enough bone marrow to repopulate the exposed areas of the body with the shielded supply. [45] This concept allows for the development of lightweight mobile radiation protection equipment, which provides adequate protection, deferring the onset of ARS to much higher exposure doses. One example of such equipment is the 360 gamma, a radiation protection belt that applies selective shielding to protect the bone marrow stored in the pelvic area as well as other radio sensitive organs in the abdominal region without hindering functional mobility.

    Reduction of incorporation Edit

    Where radioactive contamination is present, an elastomeric respirator, dust mask, or good hygiene practices may offer protection, depending on the nature of the contaminant. Potassium iodide (KI) tablets can reduce the risk of cancer in some situations due to slower uptake of ambient radioiodine. Although this does not protect any organ other than the thyroid gland, their effectiveness is still highly dependent on the time of ingestion, which would protect the gland for the duration of a twenty-four-hour period. They do not prevent ARS as they provide no shielding from other environmental radionuclides. [46]

    Fractionation of dose Edit

    If an intentional dose is broken up into a number of smaller doses, with time allowed for recovery between irradiations, the same total dose causes less cell death. Even without interruptions, a reduction in dose rate below 0.1 Gy/h also tends to reduce cell death. [34] This technique is routinely used in radiotherapy. [ citation needed ]

    The human body contains many types of cells and a human can be killed by the loss of a single type of cells in a vital organ. For many short term radiation deaths (3–30 days), the loss of two important types of cells that are constantly being regenerated causes death. The loss of cells forming blood cells (bone marrow) and the cells in the digestive system (microvilli, which form part of the wall of the intestines) is fatal. [ citation needed ]


    Side effects. There has not been enough research to uncover the side effects of GABA supplements.

    Risks. Overall, there isn't enough information to be sure about the safety of GABA. For this reason, it's best to play it safe and not use GABA if you are pregnant or breastfeeding.

    Interactions. Not enough is known about how GABA may interact with drugs, foods, or other herbs and supplements, but use with caution if taking with blood pressure medications.

    Be sure to tell your doctor about any supplements you're taking, even if they're natural. That way, your doctor can check on any potential side effects or interactions with medications, foods, or other herbs and supplements. They can let you know if the supplement might raise your risks.

    The U.S. Food and Drug Administration (FDA) does regulate dietary supplements however, it treats them like foods rather than medications. Unlike drug manufacturers, the makers of supplements don’t have to show their products are safe or effective before selling them on the market.

    Sources

    Virginia Commonwealth University: "The Role of GABA in the Pathogenesis and Treatment of Anxiety and Other Neuropsychiatric Disorders."

    Linus Pauling Institute: "Neurotransmitter Synthesis."

    Natural Medicines Comprehensive Database: "GABA (Gamma-Aminobutyric Acid)."

    Shimada M. Clinical and Experimental Hypertension. June 2009.

    Krantis A. Acta Neuropathologica, 1984.

    Enna, S. GABA, Volume 54 (Advances in Pharmacology), Academic Press, 2006.

    Amen, D. Change Your Brain, Change Your Life, Three Rivers Press, 1999.


    Is there any risk that internal radiation implants (brachytherapy) will leak or break free from where they are placed and move around my body?

    With brachytherapy, we use a needle or a catheter to insert radioactive material contained within a sealed source such as a seed, pellet, wire, or capsule. As the radioactive material inside the implants decays naturally over time, it emits radiation that deposits energy to treat nearby cancer cells. This radioactivity travels only a certain distance beyond the implant. Within a few weeks or months, the implant no longer gives off any radiation. The implants are specially tested and sealed to ensure that the encapsulated radioactive material doesn&rsquot leak, and we place them in such a way that it&rsquos highly unlikely they will move. We give people specific precautions to minimize exposure to others from the implanted radioactive material.


    Best Uses for Neurofeedback

    Now let’s take a deeper look at the most common, evidence-based uses for neurofeedback.

    1. Neurofeedback for Stress and Anxiety

    If there is one specific area where neurofeedback shines, it’s stress reduction.

    It’s useful for literally any condition that’s related to stress.

    Learning how to manage stress is one of the best things you can do for your overall health, brain function, and mental well-being.

    The typical stress-induced flight-or-fight response initiates a cascade of physiological changes you normally have no control over.

    Your heart rate and blood pressure increase, your breathing becomes fast and shallow, and blood gets directed away from your brain and into your muscles.

    Neurofeedback teaches you how to manage your brainwave activity to slow down the stress response cascade. (4)

    It’s particularly helpful for any health condition with a high correlation to stress like anxiety, high blood pressure, bruxism (teeth grinding), and digestive disorders like IBS and chronic constipation.

    2. Neurofeedback for ADHD

    The most studied use of neurofeedback is for ADHD (attention deficit hyperactivity disorder).

    It shows promise as a safe and effective drug-free treatment for children as well as adults. (5, 6)

    In a meta analysis of studies on ADHD, researchers concluded that neurofeedback effectively reduces the symptoms of inattention, impulsiveness, and hyperactivity. (7)

    One review of large-scale clinical trials found that neurofeedback therapy induces a state of relaxed attention, modulates both over and under-arousal, and works comparably to the typical stimulant medications prescribed for ADHD. (8)

    3. Neurofeedback and Depression

    D. Corydon Hammond, PhD, is a recognized authority in the field of neurotherapy.

    He has nearly 200 scientific publications to his credit and is the primary author of the recommended standards of practice for the clinical use of neurofeedback. (9)

    In a review of the current body of literature on neurofeedback for depression, he states that significant, enduring improvements occur approximately 80% of the time in patients who have a biological predisposition to depression. (10)

    Most patients notice a difference after three to six sessions, feel a very significant improvement after ten to twelve sessions, and usually complete treatment within 20 to 22 sessions.

    One study on depression found that the use of neurofeedback decreased depressive symptoms by 50%. (11)

    4. Neurofeedback for Peak Performance

    Neurofeedback is also an effective technique to enhance overall performance.

    It is used by Olympians, professional athletes, NASA astronauts, entrepreneurs, biohackers, and others who seek peak physical or mental performance. (12, 13)

    The US military uses neurofeedback to treat soldiers with PTSD and brain injuries, and for general performance enhancement. (14, 15)

    You too can use it to improve any area of your life — work, studies, relationships, health, and happiness.

    Get our BRAIN POWERUP GUIDE, free.

    5. Additional Uses for Neurofeedback

    The list of uses for neurofeedback is so long that it reads like the table of contents of a medical textbook.

    The International Society for Neuroregulation & Research has compiled a comprehensive bibliography of hundreds of scientific neurofeedback studies.

    There you’ll find links to research on the following conditions:

    • addictions
    • ADHD
    • anxiety
    • asthma
    • autism and Asperger’s
    • bipolar disorder
    • cerebral palsy
    • chemotherapy side effects
    • chronic fatigue syndrome
    • chronic pain
    • cognitive decline, including dementia
    • cognitive enhancement
    • depression
    • dissociative disorders
    • eating disorders
    • epilepsy
    • fibromyalgia
    • headaches, including migraines
    • high blood pressure
    • insomnia
    • learning disabilities
    • Lyme disease
    • memory loss
    • obsessive-compulsive disorder
    • Parkinson’s disease
    • post-traumatic stress disorder
    • restless leg syndrome
    • schizophrenia
    • stress
    • stroke
    • tinnitus
    • Tourette’s syndrome
    • traumatic brain injury

    Many studies have been conducted on the use of neurofeedback for optimal mental functioning as well.

    It’s been shown to increase creativity, memory, concentration, attention, and general well-being.

    Think more clearly, learn faster, and remember more.

    Dr. Pat | Be Brain Fit


    Safety Concerns with Implantable Infusion Pumps in the Magnetic Resonance (MR) Environment: FDA Safety Communication

    Cardiology, Emergency Medicine, General Surgeons, Magnetic Resonance Technologists, Neurosurgeons, Neurologists, Nurses and Nurse Practitioners, Orthopedic Surgeons, Physician Assistants, Primary Care Physicians, Radiologists

    Devices:

    Implantable infusion pumps are devices that are surgically implanted under the skin, typically in the abdominal region. They are connected to an implanted catheter and are used to deliver medications and fluids within the body. Implantable infusion pumps are periodically refilled with medications or fluids by a health care provider. Implantable infusion pumps may be used to treat chronic pain, muscle spasticity, and many other diseases or conditions.

    Magnetic Resonance Imaging (MRI) is a medical diagnostic exam that creates images of the internal structures of the body by using strong magnetic fields and radio waves (radiofrequency energy). These images provide information to physicians and can be useful in diagnosing a wide variety of diseases and conditions. Some medical devices, including some implantable infusion pumps, can be affected by the strong magnetic fields associated with MRI.

    Purpose:

    The FDA is informing patients, caregivers, MR technologists, and health care providers of important safety precautions to help patients with implantable infusion pumps safely have an MRI exam.

    Summary of Problem and Scope:

    The FDA has received reports of serious adverse events, including patient injury and death, associated with the use of implantable infusion pumps in the MR environment. These reports describe medication dosing inaccuracies (e.g., over-infusion or under-infusion, unintended bolus) and other mechanical problems with the pump (e.g., motor stall, pump not restarting after an MRI exam).

    MRI systems provide images of the internal structures of the body that can be useful in diagnosing a wide variety of diseases and conditions. However, the MR environment presents safety hazards for patients with implantable infusion pumps. Only implantable infusion pumps labeled as MR Conditional may be used safely within an MR environment, and only under the specified conditions of safe use. The specific conditions that health care practitioners and patients should follow before, during, and after the MRI exam vary by the make and model of the implantable infusion pump system. Importantly, each implantable pump model may have unique conditions that must be followed in order for a patient to safely undergo an MRI exam. Failure to adhere to these conditions can result in serious injury or death.

    The benefits and risks of an MRI exam must be considered for each patient. The value of the information to be gained from the MRI exam should be weighed against the risks of the exam. All medical devices present in the MR environment during the exam (including implants, external devices and accessory devices) should be considered.

    Recommendations:

    To help reduce the likelihood of serious adverse events, FDA recommends the following before, during, and after a patient with an implantable infusion pump has an MRI exam:

    Patients with implantable infusion pumps and their caregivers:

    • Be aware that specific instructions must be followed by your health care providers and MR technologist before, during, and after an MRI exam. These instructions may differ by manufacturer and model of the pump.
    • If you are scheduled for an MRI, make sure your physicians and the MR technologist know that you have an implantable infusion pump.
    • Be able to identify the make and model of your implantable infusion pump. Most patients are provided with an "implant card" that lists this information.
    • Bring the implant card for your implantable infusion pump with you when you go for your MRI exam. Before you can safely have an MRI exam, your health care team will need to identify your specific pump model to locate the specific MRI safety information for your pump. If there are any questions about the make and model of implantable infusion pump you have, contact the physician who manages your pump and do not have the MRI exam until the specific implantable pump model is identified.
    • Consider obtaining a medical alert bracelet or necklace in case of an emergency situation. Include information to notify medical professionals that you have an implantable pump and that MRI precautions need to be followed.
    • Be aware that MRI exams may affect the function or programming of your infusion pump, even when the specified conditions of MR Conditional use have been followed. For example, your implantable pump may need to be checked and/or reprogrammed by your physician before and after your MRI.
    • Only implantable infusion pumps labeled as MR Conditional may be safely scanned, and only under the specific conditions of safe use. Consult with your physician and the MR technologist to determine whether it is safe for you to have an MRI.

    MRI Technologists:

    • Be aware of and follow the policies and procedures at your site for patient screening prior to MRI exposure. Be sure all patients are screened for implantable devices such as implantable infusion pumps.
    • Do NOT scan the patient until the pump model has been positively identified and instructions for safe MRI exposure are understood. Before scanning a patient with an implantable infusion pump, ask the patient for their implant card to confirm the pump model. If there are any questions about the specific pump model a patient has, contact the health care provider managing the pump.
    • Only implantable infusion pumps labeled as MR Conditional may be safely scanned, and only under the specific conditions of safe use. Contact the implantable infusion pump manufacturer if there are any questions about the MRI safety status of the implantable pump system.
    • Be aware that the steps that must be followed before, during, and after an MRI exam may be different for each manufacturer and model of pump. Be sure to verify that the conditions of safe MRI use can be followed prior to scanning the patient.
    • Ensure that the MRI system at your site meets all conditions provided in the MR Conditional labeling of the implantable pump. For example, some implantable pump models can be safely imaged only at 1.5 tesla (T), but not 3T. (Tesla or "T" is a measure of magnetic field strength.)

    Radiologists:

    • Consider the benefits and risks of an MRI exam for each patient and weigh the value of the information gained from the magnetic resonance images against the risks of the exam for the patient. All medical devices present in the MR environment during the exam (including implants, external devices and accessory devices) should be included in the risk assessment.
    • Only implantable infusion pumps labeled MR Conditional may be safely scanned, and only under the specified conditions of safe use. Contact the implantable infusion pump manufacturer if there are any questions about the MRI safety status of the implantable pump system.

    Health Care Providers who implant infusion pumps:

    • When selecting the appropriate pump for each patient, please be aware that only patients implanted with MR Conditional pumps can safely undergo MRI exams, and only under very specific conditions of safe use. The conditions of safe MRI use may differ by manufacturer and model of the pump. This information should be discussed with the patient before and after the pump is implanted.
    • Ensure that your patients receive and understand information about their implantable infusion pump, including how to use their patient implant card.
    • Document the implantable device identification information in the patient's medical record.

    Health Care Providers who manage implantable infusion pumps:

    • Be aware that only patients implanted with MR Conditional pumps can safely undergo MRI exams, and only under the specified conditions of safe use. The conditions of safe use may differ by manufacturer and model of the pump.
    • Before ordering an MRI scan for a patient with an implantable infusion pump, determine the make and model of the implantable infusion pump and ask the patient for their implant card to confirm the pump model.
    • Only implantable infusion pumps labeled as MR Conditional may be safely scanned, and only under the specific conditions of safe use. Contact the implantable infusion pump manufacturer if there are any questions about the MRI safety status of the implantable pump system.
    • Be aware that specific instructions must be followed before, during, and after MRI exams of patients with implanted infusion pumps, and that these instructions may differ by manufacturer and model of the pump.
    • Inform your patients that they should notify you before having an MRI exam that another health care provider orders. MRI exams may affect the function or programming of the implantable infusion pump. For example:
      • Some pump models may automatically stop delivering medication during the MRI exam, and some may need to be reprogrammed before and/or after the exam. Depending on the medication delivered by the implantable pump, alternative drug therapy may need to be considered to prevent drug withdrawal.
      • Some pump models may need to be completely emptied of drug prior to the MRI exam to prevent unintended over delivery of medication and drug overdose.

      Health Care Providers that prescribe MRI Exams:

      • Be aware that only patients implanted with MR Conditional pumps can safely undergo MRI exams, and only under specified conditions of safe use. The conditions may differ by manufacturer and model of the pump.
      • You should ask all of your patients if they have any implantable pumps or other implants when determining whether an MRI exam is safe for them.
      • Before ordering an MRI scan for a patient with an implantable infusion pump, determine the make and model of the implantable infusion pump and ask the patient for their implant card to confirm the pump model. If there are any questions about the specific pump make and model a patient has, contact the health care provider managing the pump.
      • Only implantable infusion pumps labeled as MR Conditional may be safely scanned, and only under the specific conditions of safe use. Contact the implantable infusion pump manufacturer if there are any questions about for the MRI safety status of the implantable pump system.
      • Consider the benefits and risks of an MRI exam and weigh the value of the information to be gained from the MRI exam against the risks of the exam for the patient. All medical devices present in the MR environment during the exam (including implants, external devices and accessory devices) should be included in the risk assessment.
      • If needed, consult with a radiologist to determine if the MRI exam will deliver the expected benefits. For example, under some circumstances, artifacts from the pump may compromise the quality of acquired images.
      • Ensure that care for your patient is coordinated between you, the physician who manages the implantable pump, and the facility that will perform the MRI exam.

      FDA Activities:

      Before an implantable infusion pump is introduced into clinical use, the FDA reviews evidence supporting the safe and effective use of that pump. This review may include evidence supporting the MR Conditional labeling. After an implantable infusion pump is approved for clinical use, the FDA monitors adverse events related to the pump.

      An analysis of adverse event information and manufacturer labeling alerted the FDA to a potential safety problem with the use of implantable infusion pumps in the MR environment. The FDA is working with the applicable manufacturers to update MRI safety information in their labeling to ensure that instructions for the safe use of these devices are clear and up-to-date with current terminology and definitions.

      Reporting Problems to the FDA:

      Prompt reporting of adverse events can help the FDA identify and better understand the risks associated with medical devices. If you suspect an implantable pump of having problems during an MRI exam, we encourage you to file a voluntary report through MedWatch, the FDA Safety Information and Adverse Event Reporting program.

      Device manufacturers and user facilities must comply with the applicable Medical Device Reporting (MDR) regulations.

      Health care personnel employed by facilities that are subject to the FDA's user facility reporting requirements should follow the reporting procedures established by their facilities.


      Background

      Alzheimer’s disease (AD) is the most prevalent form of dementia in the elderly [1, 2]. The hallmarks of AD include senile plaques, composed primarily of amyloid-beta (Aβ) protein, as well as neurofibrillary tangles and memory loss [3,4,5]. Clinical trials of potential therapies for AD have thus far met with very limited success [3, 6, 7]. Therefore, there is still much research interest in establishing methods to diagnose and prevent AD before the onset of the irreversible deterioration phase of the disease. Although the primary sensory centers of the brain are minimally affected [8], patients with early-stage AD exhibit olfactory perceptual deficits, often coinciding with, or preceding, the manifestation of classical cognitive impairments such as memory loss [9,10,11,12,13]. Thus, one potential approach to the early diagnosis of AD would be to detect the olfactory sensory dysfunction in combination with neuropsychological measures involving affective changes [14, 15].

      In the olfactory system, odor is first received by olfactory sensory neurons (OSNs) located in the olfactory epithelium (OE) [16, 17]. After the OSNs convert the chemical signal of the odorant into electrical potential, odor information is transferred to the olfactory bulb (OB) where it is encoded by OB output neurons, mitral/tufted (M/T) cells, and then sent to highly plastic olfactory cortical areas, including the piriform cortex (PC) [18, 19]. AD pathogenic factors, including Aβ aggregation, have been found within the OE, OB and PC in both AD patients and AD rodent models [20,21,22,23]. It is now evident that patients with early-stage AD often have a reduced ability to detect, discriminate, and identify odors, coupled with abnormal odor coding [9, 24, 25]. However, potential olfactory biomarkers and the precise neural mechanisms underlying the olfactory deficits in early AD remain poorly understood. Therefore, the usefulness of olfactory screens as an approach to AD diagnosis is hampered by a lack of knowledge on how and when AD pathogenesis impacts olfaction.

      Gamma oscillations (40–100 Hz), resulting from activation of excitatory and fast-spiking inhibitory local circuits, have been shown to be necessary for higher cognitive functions and sensory procession [26,27,28]. Gamma rhythms recruit both neuronal and glial responses to attenuate AD-associated pathology [26, 29] and improve cognition [30], suggesting they could play an important role in AD pathogenesis and treatment. As the first relay of the olfactory system, proper gamma oscillations in the OB are required for odor discrimination and odor learning [27, 31]. Though aberrant gamma rhythms are known to occur in the OB of a Swedish mutation AD model, Tg2576 mice, and OB slices of APP/PS1 mice at ages before Aβ deposition [23, 32], the mechanism and relationship between altered gamma oscillations and local- or long-range-circuitry pathology remain unclear.

      In the present study, impaired olfactory detection occurred in 3–5 month-old AD mouse models, including APP/PS1 and 3xTg mice, accompanied by increased gamma oscillations, which may be attributed to a disturbance in the excitation/inhibition (E/I) ratio of OB. Moreover, we discovered that abnormal number of OSNs and subsequent OE → OB excitation, altered glutamatergic- and GABAergic-synaptic transmission and levels of GABAARs underlie aberrant gamma oscillations. Furthermore, an increase in levels of GABA in the synaptic cleft by blockade of GABA-uptake transporter 1 (GAT1) with tiagabine (TGB), an anti-convulsive medication, attenuated aberrant gamma oscillations in both APP/PS1 and 3xTg mice. The results highlight the potential for the early diagnosis of AD by identification of altered olfactory perception with aberrant gamma oscillatory activity and levels of GABA receptors, and the use of an anti-convulsant medicine, TGB, in the treatment of certain symptoms of early AD. Evidence reviewed here in the context of the emergence of other typical pathological changes in AD suggests that olfactory impairments could be probed to understand the molecular mechanisms involved in the early phases of the pathology.


      How Radiation Sickness Works

      When radiation of high enough energy strikes another atom, it strips away an electron. The resulting positively charged atom is called an ion, which explains why high energy radiation is called ionizing radiation. The release of the electron produces 33 electron volts (eV) of energy, which heats the surrounding tissues and disrupts certain chemical bonds. Extremely high-energy radiation can even destroy the nuclei of atoms, releasing even more energy and causing more damage. Radiation sickness is the cumulative effect of all this damage on a human body that's been bombarded with radiation.

      Ionizing radiation comes in three flavors: alpha particles, beta particles and gamma rays. Alpha particles are the least dangerous in terms of external exposure. Each particle contains a pair of neutrons and a pair of protons. They don't penetrate very deeply into the skin, if at all -- in fact, clothing can stop alpha particles. Unfortunately, alpha particles can be inhaled or ingested, usually in the form of radon gas. Once ingested, alpha particles can be very dangerous. However, even then they don't typically cause radiation sickness -- instead, they lead to lung cancer [source: EPA].

      Beta particles are electrons that move very quickly -- that is, with a lot of energy. Beta particles travel several feet when emitted from a radioactive source, but they're blocked by most solid objects. A beta particle is about 8,000 times smaller than an alpha particle -- and that's what makes them more dangerous. Their small size allows them to penetrate clothing and skin. External exposure can cause burns and tissue damage, along with other symptoms of radiation sickness. If radioactive material enters food or water supplies or is dispersed into the air, people can inhale or ingest beta particle emitters unknowingly. Internal exposure to beta particles causes much more severe symptoms than external exposure.

      Gamma rays are the most dangerous form of ionizing radiation. These extremely high energy photons can travel through most forms of matter because they have no mass. It takes several inches of lead -- or several feet of concrete -- to effectively block gamma rays. If you're exposed to gamma rays, they pass through your entire body, affecting all of your tissues from your skin to the marrow of your bones. This causes widespread, systemic damage.

      How much radiation does it take to cause radiation sickness, and what effect does this damage have on a human body? That's next. For more detailed information on different types of radiation and where they come from, take a look at How Radiation Works.



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