A circadian rhythm /sɜːrˈkeɪdiən/ is any biological process that displays an endogenous, entrainable oscillation of about 24 hours. These 24-hour rhythms are driven by a clock, and they have been widely observed in plants, fungi. The term circadian comes from the Latin circa, meaning around, the formal study of biological temporal rhythms, such as daily, weekly and annual rhythms, is called chronobiology. Processes with 24-hour oscillations are generally called diurnal rhythms, strictly speaking. Although circadian rhythms are endogenous, they are adjusted to the environment by external cues called zeitgebers. The earliest recorded account of a circadian process dates from the 4th century B. C. E, when Androsthenes, a ship captain serving under Alexander the Great, described diurnal leaf movements of the tamarind tree. The first recorded observation of an endogenous circadian oscillation was by the French scientist Jean-Jacques dOrtous de Mairan in 1729, in 1896, Patrick and Gilbert observed that during a prolonged period of sleep deprivation, sleepiness increases and decreases with a period of approximately 24 hours.
Szymanski showed that animals are capable of maintaining 24-hour activity patterns in the absence of external cues such as light, in the early 20th century, circadian rhythms were noticed in the rhythmic feeding times of bees. Extensive experiments were done by Auguste Forel, Ingeborg Beling, ron Konopka and Seymour Benzer isolated the first clock mutant in Drosophila in the early 1970s and mapped the period gene, the first discovered genetic determinant of behavioral rhythmicity. Joseph Takahashi discovered the first mammalian circadian clock mutation using mice in 1994, recent studies show that deletion of clock does not lead to a behavioral phenotype, which questions its importance in rhythm generation. The term circadian was coined by Franz Halberg in the 1950s, to be called circadian, a biological rhythm must meet these three general criteria, The rhythm has an endogenous free-running period that lasts approximately 24 hours. The rhythm persists in constant conditions, with a period of about 24 hours, the period of the rhythm in constant conditions is called the free-running period and is denoted by the Greek letter τ.
The rationale for this criterion is to distinguish circadian rhythms from simple responses to external cues. A rhythm cannot be said to be endogenous unless it has been tested, in diurnal animals, in general τ is slightly greater than 24 hours, whereas, in nocturnal animals, in general τ is shorter than 24 hours. The rhythm can be reset by exposure to external stimuli, a process called entrainment, the external stimulus used to entrain a rhythm is called the Zeitgeber, or time giver. In other words, they maintain circadian periodicity over a range of physiological temperatures, many organisms live at a broad range of temperatures, and differences in thermal energy will affect the kinetics of all molecular processes in their cell. In order to track of time, the organisms circadian clock must maintain roughly a 24-hour periodicity despite the changing kinetics. The Q10 Temperature Coefficient is a measure of this compensating effect, if the Q10 coefficient remains approximately 1 as temperature increases, the rhythm is considered to be temperature-compensated
National Institutes of Health
The National Institutes of Health is a biomedical research facility primarily located in Bethesda, Maryland. An agency of the United States Department of Health and Human Services, it is the agency of the United States government responsible for biomedical. The NIH comprises 27 separate institutes and centers that conduct research in different disciplines of biomedical science, NIHs roots extend back to a Marine Hospital Service in the late 1790s that provided medical relief to sick and disabled men in the U. S. Navy. By 1870, a network of hospitals had developed and was placed under the charge of a medical officer within the Bureau of the Treasury Department. In 1887 a laboratory for the study of bacteria, the Hygienic Laboratory, was established at the Marine Hospital in New York, in the early 1900s, Congress began appropriating funds for the Marine Hospital Service. By 1922, this changed its name to Public Health Services. This marked the beginning of a partnership with universities, in 1930, the Hygienic Laboratory was re-designated as the National Institute of Health by the Ransdell Act and was given $750,000 to construct two NIH buildings.
Over the next few decades, Congress would increase its funding tremendously to the NIH, in 1944, the Public Health Service Act was approved, and National Cancer Institute became a division of NIH. In 1948, the changed from National Institute of Health to National Institutes of Health. In the 1960s prominent virologist and cancer researcher Chester M. Southam injected HeLa cancer cells into patients at the Jewish Chronic Disease Hospital, when three doctors resigned after refusing to inject patients without their consent, this experiment gained considerable media attention. The NIH was a source of funding for Southam’s research and had required all research involving human subjects to obtain their consent prior to any experimentation. }Upon investigating all of their grantee institutions. From on, the NIH has required all grantee institutions to approve any research involving human experimentation with review boards. In 1967 the Division of Regional Medical Programs was created to administer grants for research for heart disease and strokes.
That same year, the NIH director lobbied the White House for increased funding in order to increase research. An advisory committee was formed to further development of the NIH. The funding of NIH has often been a source of contention in Congress and this contention was seen most dramatically during the 1980s, when President Reagan repeatedly tried to cut funding for research, only to see Congress partly restore funding. But it was not until July 1987, as NIH celebrated its 100th anniversary, by the 1990s, the focus of the NIH committee had shifted to DNA research, and the Human Genome Project was launched. In 2009, President Obama reinstated federally funded research, revoking the ban imposed by President Bush in 2001
United States National Library of Medicine
The United States National Library of Medicine, operated by the United States federal government, is the worlds largest medical library. Located in Bethesda, the NLM is an institute within the National Institutes of Health, the current director of the NLM is Patricia Flatley Brennan. Since 1879, the National Library of Medicine has published the Index Medicus and these resources are accessible without charge on the internet. S. and international consultants. The Extramural Division provides grants to research in medical information science and to support planning and development of computer. Research and exhibitions on the history of medicine, in April 2008 the current exhibition Against the Odds, Making a Difference in Global Health was launched. For details of the history of the Library, see Library of the Surgeon Generals Office. The precursor of the National Library of Medicine, established in 1836, was the Library of the Surgeon Generals Office, the Armed Forces Institute of Pathology and its Medical Museum were founded in 1862 as the Army Medical Museum.
Throughout their history the Library of the Surgeon Generals Office and the Army Medical Museum often shared quarters, from 1866 to 1887, they were housed in Fords Theatre after production there was stopped, following the assassination of President Abraham Lincoln. In 1956, the collection was transferred from the control of the U. S. The library moved to its current quarters in Bethesda, Maryland, on the campus of the National Institutes of Health, journalReview. org National Library of Medicine classification system PubMed Miles, Wyndham D. A History of the National Library of Medicine, The Nations Treasury of Medical Knowledge
The superior duct, the smaller and shorter of the two, at first ascends, bends at an acute angle, and passes medialward and downward to the lacrimal sac. The inferior duct at first descends, runs almost horizontally to the lacrimal sac, at the angles they are dilated into ampullæ. Able to be seen under a microscope, they are lined by nonkeratinizing stratified squamous epithelium surrounded by fibrous tissue, canaliculitis is an inflammation of the canaliculus. Canalicular trauma may require special attention by a specialist trained in the repair of laceration, lacrimal apparatus Canaliculus This article incorporates text in the public domain from the 20th edition of Grays Anatomy
A mast cell is a type of white blood cell. Specifically, it is a type of granulocyte derived from the stem cell that is a part of the immune and neuroimmune systems and contains many granules rich in histamine. The mast cell is similar in both appearance and function to the basophil, another type of white blood cell. Although mast cells were thought to be tissue resident basophils. Mast cells were first described by Paul Ehrlich in his 1878 doctoral thesis on the basis of their unique staining characteristics and these granules led him to the incorrect belief that they existed to nourish the surrounding tissue, so he named them Mastzellen. They are now considered to be part of the immune system, mast cells are very similar to basophil granulocytes in blood. Both are granulated cells that contain histamine and heparin, an anticoagulant, the Fc region of immunoglobulin E becomes bound to mast cells and basophils and when IgEs paratopes bind to an antigen, it causes the cells to release histamine and other inflammatory mediators.
These similarities have led many to speculate that mast cells are basophils that have homed in on tissues, they share a common precursor in bone marrow expressing the CD34 molecule. Basophils leave the bone marrow already mature, whereas the mast cell circulates in an immature form, the site an immature mast cell settles in probably determines its precise characteristics. The first in vitro differentiation and growth of a population of mouse mast cells has been carried out using conditioned medium derived from concanavalin A-stimulated splenocytes. Later, it was discovered that T cell-derived interleukin 3 was the component present in the media that was required for mast cell differentiation. Mast cells in rodents are divided into two subtypes, connective tissue-type mast cells and mucosal mast cells. The activities of the latter are dependent on T-cells, mast cells play a key role in the inflammatory process. When activated, a mast cell can either release or rapidly release mediators, or compounds that induce inflammation.
Complement proteins can activate membrane receptors on mast cells to various functions as well. Mast cells express a high-affinity receptor for the Fc region of IgE and this receptor is of such high affinity that binding of IgE molecules is in essence irreversible. As a result, mast cells are coated with IgE, which is produced by plasma cells, IgE molecules, like all antibodies, are specific to one particular antigen. In allergic reactions, mast cells remain inactive until an allergen binds to IgE already coated upon the cell, other membrane activation events can either prime mast cells for subsequent degranulation or act in synergy with FcεRI signal transduction
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is rich in glycoproteins and water and is produced from cells found in mucous glands. Mucous fluid may originate from mixed glands, which contain both serous and mucous cells and this mucus serves to protect epithelial cells in the respiratory, urogenital and auditory systems, the epidermis in amphibians, and the gills in fish. A major function of mucus is to protect against infectious agents such as fungi, bacteria. The average human nose produces about a liter of mucus per day, most of the mucus produced is in the gastrointestinal tract. Bony fish, snails and some other invertebrates produce external mucus, the rest of this article deals with the production and function of mucus in humans. In the human system, mucus aids in the protection of the lungs by trapping foreign particles that enter them, in particular, through the nose. Phlegm is a term for mucus that is restricted to the respiratory tract.
Nasal mucus is produced by the mucosa, and mucosal tissues lining the airways is produced by specialized airway epithelial cells. Small particles such as dust, particulate pollutants, and allergens, as well as agents and bacteria are caught in the viscous nasal or airway mucus. This event along with the movement of the respiratory mucus layer toward the oropharynx. This explains why coughing often occurs in those who smoke cigarettes, the bodys natural reaction is to increase mucus production. In addition, mucus aids in moisturizing the inhaled air and prevents tissues such as the nasal and airway mucus is produced continuously, with most of it swallowed subconsciously, even when it is dried. Increased mucus production in the tract is a symptom of many common illnesses, such as the common cold. Hypersecretion of mucus can occur in respiratory diseases such as respiratory allergies, asthma. The presence of mucus in the nose and throat is normal, in general, nasal mucus is clear and thin, serving to filter air during inhalation.
During times of infection, mucus can change color to yellow or green either as a result of trapped bacteria or due to the reaction to viral infection. The green color of mucus comes from the group in the iron-containing enzyme myeloperoxidase secreted by white blood cells as a cytotoxic defense during a respiratory burst
Opioids are substances that act on opioid receptors to produce morphine-like effects. Opioids are most often used medically to relieve pain, and by people addicted to opioids, opioids include opiates, an older term that refers to such drugs derived from opium, including morphine itself. Other opioids are semi-synthetic and synthetic drugs such as hydrocodone and fentanyl, antagonist drugs such as naloxone, the terms opiate and narcotic are sometimes encountered as synonyms for opioid. Opiate is properly limited to the alkaloids found in the resin of the opium poppy although some include semi-synthetic derivatives. In some jurisdictions all controlled drugs are classified as narcotics. The term can have pejorative connotations and its use is discouraged where that is the case. Primarily used for relief, including anesthesia they are used to suppress cough, suppress diarrhea, treat addiction, reverse opioid overdose. Extremely strong opioids are approved only for use such as immobilizing large mammals.
Opioids act by binding to receptors, which are found principally in the central and peripheral nervous system. These receptors mediate both the psychoactive and the effects of opioids. The side effects of opioids may include itchiness, nausea, respiratory depression, constipation and dependence will develop with continuous use, requiring increasing doses and leading to a withdrawal syndrome upon abrupt discontinuation. The euphoria attracts recreational use, and frequent, escalating recreational use of opioids typically results in addiction, accidental overdose or concurrent use with other depressant drugs commonly results in death from respiratory depression. Because of opioid drugs reputation for addiction and fatal overdose, most are controlled substances, illicit production and addiction to opioids prompted treaties and policing which have realized limited success. In 2013 between 28 and 38 million people used opioids illicitly, in 2011 an estimated 4 million people in the United States used opioids recreationally or were dependent on them.
Current increased rates of use and addiction are attributed to over-prescription of opioid medications. Conversely, fears about over-prescribing, exaggerated side effects and addiction from opioids are similarly blamed for under-treatment of pain, the term opioid originated in the 1950s. It combines opium + -oid meaning opiate-like, by the late 1960s, research found that opiate effects are mediated by activation of specific molecular receptors in the nervous system, which were termed opioid receptors. The definition of opioid was refined to refer to substances that have activities that are mediated by the activation of opioid receptors
An antibody, known as an immunoglobulin, is a large, Y-shaped protein produced mainly by plasma cells that is used by the immune system to neutralize pathogens such as bacteria and viruses. The antibody recognizes a molecule of the harmful agent, called an antigen. Each tip of the Y of an antibody contains a paratope that is specific for one particular epitope on an antigen, allowing these two structures to bind together with precision. Using this binding mechanism, an antibody can tag a microbe or a cell for attack by other parts of the immune system. Depending on the antigen, the binding may impede the process causing the disease or may activate macrophages to destroy the foreign substance. The ability of an antibody to communicate with the components of the immune system is mediated via its Fc region. The production of antibodies is the function of the humoral immune system. Antibodies are secreted by B cells of the immune system. In most cases, interaction of the B cell with a T helper cell is necessary to produce full activation of the B cell and, soluble antibodies are released into the blood and tissue fluids, as well as many secretions to continue to survey for invading microorganisms.
Antibodies are glycoproteins belonging to the immunoglobulin superfamily and they constitute most of the gamma globulin fraction of the blood proteins. They are typically made of basic structural units—each with two heavy chains and two small light chains. There are several different types of heavy chains that define the five different types of crystallisable fragments that may be attached to the antigen-binding fragments. The five different types of Fc regions allow antibodies to be grouped into five isotypes, each Fc region of a particular antibody isotype is able to bind to its specific Fc Receptor, thus allowing the antigen-antibody complex to mediate different roles depending on which FcR it binds. The ability of an antibody to bind to its corresponding FcR is further modulated by the structure of the present at conserved sites within its Fc region. The ability of antibodies to bind to FcRs helps to direct the immune response for each different type of foreign object they encounter. For example, IgE is responsible for an allergic response consisting of mast cell degranulation, igEs Fab paratope binds to allergic antigen, for example house dust mite particles, while its Fc region binds to Fc receptor ε.
The allergen-IgE-FcRε interaction mediates allergic signal transduction to induce conditions such as asthma and this region is known as the hypervariable region. Each of these variants can bind to a different antigen and this enormous diversity of antibody paratopes on the antigen-binding fragments allows the immune system to recognize an equally wide variety of antigens
Crying is the shedding of tears in response to an emotional state. This could be, happiness, the act of crying has been defined as a complex secretomotor phenomenon characterized by the shedding of tears from the lacrimal apparatus, without any irritation of the ocular structures. A related medical term is lacrimation, which refers to non-emotional shedding of tears. Various forms of crying are known as weeping, whimpering, for crying to be described as sobbing, it usually has to be accompanied by a set of other symptoms, such as slow but erratic inhalation, occasional instances of breath holding and muscular tremor. A neuronal connection between the lacrimal gland and the areas of the brain involved with emotion has been established. There is debate among scientists over whether or not humans are the animals that produce tears in response to emotional states. Charles Darwin wrote in The Expression of the Emotions in Man, Tears produced during emotional crying have a chemical composition which differs from other types of tears.
They contain significantly greater quantities of the hormones prolactin, adrenocorticotropic hormone, and Leu-enkephalin, the question of the function or origin of emotional tears remains open. Theories range from the simple, such as response to inflicted pain, to the more complex, some have claimed that crying can serve several biochemical purposes, such as relieving stress. Crying is believed to be an outlet or a result of a burst of intense emotional sensations, such as agony and this theory is more plausible as it explains why people cry during cheerful events, as well as very painful events. Individuals tend to remember the positive aspects of crying, and may create a link between other simultaneous events, such as resolving feelings of grief. Together, these features of memory reinforce the idea that crying helped the individual, in Hippocratic and medieval medicine, tears were associated with the bodily humors, and crying was seen as purgation of excess humors from the brain. However, tears have a ability to eliminate chemicals, reducing the likelihood of this theory.
Recent psychological theories of crying emphasize the relationship of crying to the experience of perceived helplessness, from this perspective, an underlying experience of helplessness can usually explain why people cry. For example, a person may cry after receiving surprisingly happy news, emotional tears have been put into an evolutionary context. One study proposes that crying, by blurring vision, can handicap aggressive or defensive actions, and may function as a reliable signal of appeasement, need, or attachment. Another theory that follows evolutionary psychology is given by Paul D. MacLean, the tears, he speculates, are a result of a link between the development of the cerebrum and the discovery of fire. MacLean figures that since early humans must have relied heavily on fire, as humans evolved the smoke possibly gained a strong association with the loss of life and, sorrow
Cocaine, known as coke, is a strong stimulant mostly used as a recreational drug. It is commonly snorted, inhaled, or injected into the veins, mental effects may include loss of contact with reality, an intense feeling of happiness, or agitation. Physical symptoms may include a fast heart rate, high doses can result in very high blood pressure or body temperature. Effects begin within seconds to minutes of use and last between five and ninety minutes, Cocaine has a small number of accepted medical uses such as numbing and decreasing bleeding during nasal surgery. Cocaine is addictive due to its effect on the pathway in the brain. After a short period of use, there is a risk that dependence will occur. Its use increases the risk of stroke, myocardial infarction, lung problems in those who smoke it, blood infections, Cocaine sold on the street is commonly mixed with local anesthetics, quinine, or sugar which can result in additional toxicity. Following repeated doses a person may have decreased ability to feel pleasure, Cocaine acts by inhibiting the reuptake of serotonin and dopamine.
This results in concentrations of these three neurotransmitters in the brain. It can easily cross the barrier and may lead to the breakdown of the barrier. Cocaine is made from the leaves of the plant which are mostly grown in South America. In 2013,419 kilograms were produced legally and it is estimated that the illegal market for cocaine is 100 to 500 billion USD each year. With further processing crack cocaine can be produced from cocaine, after cannabis, cocaine is the most frequently used illegal drug globally. Between 14 and 21 million people use the drug each year, use is highest in North America followed by Europe and South America. Between one and three percent of people in the world have used cocaine at some point in their life. In 2013 cocaine use resulted in 4,300 deaths. The leaves of the plant have been used by Peruvians since ancient times. Cocaine was first isolated from the leaves in 1860, since 1961 the international Single Convention on Narcotic Drugs has required countries to make recreational use of cocaine a crime
A basophil is a type of white blood cell. Basophils are the least common of the granulocytes, representing about 0.5 to 1% of circulating blood cells. However, they are the largest type of granulocyte and they can perform phagocytosis, produce histamine and serotonin that induce inflammation, and heparin that prevents blood clotting. Basophils were discovered in 1879 by a German physician Paul Ehrlich, Ehrlich received the 1908 Nobel Prize in Physiology or Medicine for his discoveries. The name comes from the fact that these leukocytes are basophilic, i. e. they are susceptible to staining by basic dyes, basophils contain large cytoplasmic granules which obscure the cell nucleus under the microscope when stained. However, when unstained, the nucleus is visible and it usually has two lobes, the mast cell, another granulocyte, is similar in appearance and function. Both cell types store histamine, a chemical that is secreted by the cells when stimulated, they arise from different branches of hematopoiesis, and mast cells usually do not circulate in the blood stream, but instead are located in connective tissue.
Like all circulating granulocytes, basophils can be recruited out of the blood into a tissue when needed, basophils appear in many specific kinds of inflammatory reactions, particularly those that cause allergic symptoms. Basophils contain anticoagulant heparin, which prevents blood from clotting too quickly and they contain the vasodilator histamine, which promotes blood flow to tissues. They can be found in high numbers at sites of ectoparasite infection. Like eosinophils, basophils play a role in both parasitic infections and allergies and they are found in tissues where allergic reactions are occurring and probably contribute to the severity of these reactions. Basophils have protein receptors on their surface that bind IgE. It is the bound IgE antibody that confers a selective response of cells to environmental substances, for example. Recent studies in mice suggest that basophils may regulate the behavior of T cells, basophil function is inhibited by CD200. Herpesvirus-6, herpesvirus-7, and herpesvirus-8 produce a CD200 homolog which inhibits basophil function and this suggests that basophils may play a role in the immune response to these viruses.
Recently, Heneberg proposed that basophils may be defined as the cellular population positive for CD13, CD44, CD54, CD63, CD69, CD107a, CD123, CD164, CD193/ CCR3, CD203c, TLR-4, and FcεRI. When activated, some additional surface markers are known to be upregulated, basophils arise and mature in bone marrow. When activated, basophils degranulate to release histamine and they secrete lipid mediators like leukotrienes, and several cytokines