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Nutrition science studies the relationship between diet and states of health and disease. Dieticians are health professionals who are specialized in this area of expertise, highly trained to provide safe, evidence-based dietary advice and interventions.
There is a spectrum ranging from malnutrition to optimal health, including many common symptoms and diseases which can often be prevented or alleviated with better nutrition.
Deficiencies, excesses and imbalances in diet can produce negative impacts on health, which may lead to diseases such as scurvy, obesity or osteoporosis, as well as psychological and behavioral problems. Moreover, excessive ingestion of elements that have no apparent role in health, (e.g. lead, mercury, PCBs, dioxins), may incur toxic and potentially lethal effects, depending on the dose. The science of nutrition attempts to understand how and why specific dietary aspects influence health. (More...)
Insulin (from Latin insula, "island", as it is produced in the Islets of Langerhans in the pancreas) is a polypeptide hormone that regulates carbohydrate metabolism. Apart from being the primary agent in carbohydrate homeostasis, it has effects on fat metabolism and it changes the liver's activity in storing or releasing glucose and in processing blood lipids, and in other tissues such as fat and muscle. The amount of insulin in circulation has extremely widespread effects throughout the body.
Insulin is used medically to treat some forms of diabetes mellitus. Patients with type 1 diabetes mellitus depend on external insulin (most commonly injected subcutaneously) for their survival because of an absolute deficiency of the hormone. Patients with type 2 diabetes mellitus have insulin resistance, relatively low insulin production or both; some type 2 diabetics eventually require insulin when other medications become insufficient in controlling blood glucose levels. (More...)
Vacutainer was developed in 1947 by Joseph Kleiner. The vein is first punctured with the hypodermic needle, which is connected to a translucent plastic holder. The needle actually has a second, smaller needle, and when a Vacutainer test tube is pushed down into the holder, its rubber cap is pierced. The vacuum in the tube sucks blood though the needle and fills itself. The tube is then removed and another can be inserted and filled the same way. It is important to remove the tube before withdrawing the needle, as there may still be some suction left, causing pain upon withdrawal. (More...)
Helicobacter pylori is a bacterium that infects the mucus lining of the human stomach. Many peptic ulcers and some types of gastritis are caused by H. pylori infection, although most humans who are infected will never develop symptoms. This bacterium lives in the human stomach exclusively and is the only known organism that can thrive in that highly acidic environment. It is helix-shaped (hence the name helicobacter) and can literally screw itself into the stomach lining to colonize.
The bacterium was rediscovered in 1982 by two Australian scientists Robin Warren and Barry Marshall; they isolated the organisms from mucosal specimens from human stomachs and were the first to successfully culture them. In their original paper, Warren and Marshall contended that most stomach ulcers and gastritis were caused by colonization with this bacterium, not by stress or spicy food as had been assumed before.
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Asthma is a disease of the human respiratory system where the airways narrow, often in response to a "trigger" such as exposure to an allergen, cold air, exercise, or emotional stress. This narrowing causes symptoms such as wheezing, shortness of breath, chest tightness, and coughing, which respond to bronchodilators. Between episodes, most patients feel fine.
The disorder is a chronic (reoccurring) inflammatory condition in which the airways develop increased responsiveness to various stimuli, characterized by bronchial hyper-responsiveness, inflammation, increased mucus production, and intermittent airway obstruction. The symptoms of asthma, which can range from mild to life threatening, can usually be controlled with a combination of drugs and lifestyle changes.
The word asthma is derived from the Greek aazein, meaning "sharp breath." The word first appears in Homer's Iliad. Hippocrates was the first to use it in reference to the medical condition. Hippocrates thought that the spasms associated with asthma were more likely to occur in tailors, anglers, and metalworkers. Six centuries later, Galen wrote much about asthma, noting that it was caused by partial or complete bronchial obstruction. Moses Maimonides, an influential medieval rabbi, philosopher, and physician, wrote a treatise on asthma, describing its prevention, diagnosis, and treatment.
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Female hysteria was an incorrectly diagnosed medical condition in western medicine that is not currently acknowledged by the medical community. It was a popular diagnosis in the Victorian era for a wide array of symptoms including faintness, nervousness, insomnia, fluid retention, heaviness in abdomen, muscle spasm, shortness of breath, irritability, loss of appetite for food or sex, and a "tendency to cause trouble".
Patients diagnosed with female hysteria would undergo "pelvic massage" — manual stimulation of the woman's genitals by the doctor to "hysterical paroxysm", which is now recognized as orgasm.
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Influenza A virus subtype H5N1, also known as A(H5N1) or simply H5N1, is a subtype of the Influenza A virus which can cause illness in humans and many other animal species. A bird-adapted strain of H5N1, called HPAI A(H5N1) for "highly pathogenic avian influenza virus of type A of subtype H5N1", is the causative agent of H5N1 flu, commonly known as "avian influenza" or "bird flu". It is endemic in many bird populations, especially in Southeast Asia. One strain of HPAI A(H5N1) is spreading globally after first appearing in Asia. It is epizootic (an epidemic in nonhumans) and panzootic (affecting animals of many species, especially over a wide area), killing tens of millions of birds and spurring the culling of hundreds of millions of others to stem its spread. Most references to "bird flu" and H5N1 in the popular media refer to this strain.
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Forensic facial reconstruction (or forensic facial approximation) is the process of recreating the face of an unidentified individual from their skeletal remains through an amalgamation of artistry, forensic science, anthropology, osteology, and anatomy. It is easily the most subjective - as well as one of the most controversial - techniques in the field of forensic anthropology. Despite this controversy, facial reconstruction has proved successful frequently enough that research and methodological developments continue to be advanced.
In addition to remains involved in criminal investigations, facial reconstructions are created for remains believed to be of historical value and for remains of prehistoric hominids and humans. (More...)
Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down large molecules, for example to harvest energy in cellular respiration. Anabolism, on the other hand, uses energy to construct components of cells such as proteins and nucleic acids.
The chemical reactions of metabolism are organized into metabolic pathways, in which one chemical is transformed into another by a sequence of enzymes. Enzymes are crucial to metabolism because they allow organisms to drive desirable but thermodynamically unfavorable reactions by coupling them to favorable ones. Enzymes also allow the regulation of metabolic pathways in response to changes in the cell's environment or signals from other cells.
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Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses). The name influenza comes from the Italian: influenza , meaning "influence", (Latin: influentia). In humans, common symptoms of the disease are fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort. In more serious cases, influenza causes pneumonia, which can be fatal, particularly in young children and the elderly. Although it is sometimes confused with the common cold, influenza is a much more severe disease and is caused by a different type of virus. Influenza can produce nausea and vomiting, especially in children, but these symptoms are more characteristic of the unrelated gastroenteritis, which is sometimes called "stomach flu" or "24-hour flu."
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A sexually transmitted disease (STD), a.k.a. Venereal disease (VD), is an illness that has a significant probability of transmission between humans or animals by means of sexual contact, including vaginal intercourse, oral sex, and anal sex. Increasingly, the term sexually transmitted infection (STI) is used, as it has a broader range of meaning; a person may be infected, and may potentially infect others, without showing signs of disease. Some STIs can also be transmitted via the needles used in IV drug use, as well as through childbirth or breastfeeding. Sexually transmitted infections have been well known for hundreds of years.
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Hodgkin's lymphoma, also known as Hodgkin's disease, is a type of lymphoma first described by Thomas Hodgkin in 1832. Hodgkin's lymphoma is characterized clinically by the orderly spread of disease from one lymph node group to another and by the development of systemic symptoms with advanced disease. Pathologically, the disease is characterized by the presence of Reed-Sternberg cells. Hodgkin's lymphoma was one of the first cancers to be cured by radiation. Later it was one of the first to be cured by combination chemotherapy. The cure rate is about 93%, making it one of the most curable forms of cancer.
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Fever (also known as pyrexia from the Greek pyretos meaning fire, or a febrile response from the Latin word febris, meaning fever, and archaically known as ague) is a frequent medical symptom that describes an increase in internal body temperature to levels that are above normal (the common oral measurement of normal human body temperature is 36.8±0.7 °C or 98.2±1.3 °F). Fever is most accurately characterized as a temporary elevation in the body's thermoregulatory set-point, usually by about 1–2°C. Fever differs from hyperthermia, which is an increase in body temperature over the body's thermoregulatory set-point (due to excessive heat production or insufficient thermoregulation, or both). Carl Wunderlich discovered that fever is not a disease but a symptom of disease.
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Smallpox is an acute infectious disease unique to humans, caused by either of two virus variants named Variola major and Variola minor. Also known by the Latin names Variola or Variola vera; a derivative of the Latin varius, meaning spotted, or varus, meaning "pimple". The term "smallpox" was first used in Europe in the 15th century to distinguish variola from the great pox (syphilis).
Smallpox localizes in small blood vessels of the skin and in the mouth and throat. In the skin, this results in the characteristic maculopapular rash, which evolves into raised vesicles, then into fluid-filled pustules. V. major produces a more serious disease and has an overall mortality rate of 30–35%. V. minor (also known as alastrim, cottonpox, milkpox, whitepox, and Cuban itch) causes a milder form of disease which kills ~1% of its victims.
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Vaccination is the administration of antigenic material to produce immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by a pathogen. The material administrated can either be live, but weakened forms of pathogens such as bacteria or viruses, killed or inactivated forms of these pathogens, or purified material such as proteins. Smallpox was the first disease people tried to prevent by purposely inoculating themselves with other types of infections; smallpox inoculation was started in India or China before 200 BC. In 1718, Lady Mary Wortley Montague reported that the Turks have a habit of deliberately inoculating themselves with fluid taken from mild cases of smallpox and she inoculated her own children.
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Renal cell carcinoma is the most common form of kidney cancer arising from the renal tubule. It is the most common type of kidney cancer in adults. Initial treatment is surgery. It is notoriously resistant to radiation therapy and chemotherapy, although some cases respond to immunotherapy. The advent of targeted cancer therapies such as sunitinib has vastly improved the outlook for treatment of RCC.
The classic triad is hematuria (blood in the urine), flank pain and an abdominal mass. This is now known as the 'too late triad' because by the time patients present with symptoms, their disease is often advanced beyond a curative stage. Today, the majority of renal tumors are asymptomatic and are detected incidentally on imaging, usually for an unrelated cause.
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Cholangiocarcinoma is a cancer of the bile ducts, which drain bile from the liver into the small intestine. It is a relatively rare cancer, with an annual incidence of 1–2 cases per 100,000 in the Western world, but rates of cholangiocarcinoma have been rising worldwide over the past several decades. Risk factors for cholangiocarcinoma include primary sclerosing cholangitis (an inflammatory disease of the bile ducts), congenital liver malformations, infection with the parasitic liver flukes Opisthorchis viverrini or Clonorchis sinensis, and exposure to Thorotrast (thorium dioxide), a chemical previously used in medical imaging. The symptoms of cholangiocarcinoma include jaundice, weight loss, and sometimes generalized itching. The disease is diagnosed through a combination of blood tests, imaging, endoscopy, and sometimes surgical exploration.
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An ambulance is a vehicle for transporting sick or injured people,[1] to, from or between places of treatment for an illness or injury. The term ambulance is used to describe a vehicle used to bring medical care to patients outside of the hospital and when appropriate, to transport the patient to hospital for follow-up care and further testing. In some jurisdictions there is a modified form of the ambulance used, that only carries one member of ambulance crew to the scene to provide care, but is not used to transport the patient. In these cases a patient who requires transportation to hospital will require a patient-carrying ambulance to attend in addition to the fast responder.
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Colorectal cancer, also called colon cancer or bowel cancer, includes cancerous growths in the colon, rectum and appendix. It is the third most common form of cancer and the second leading cause of cancer-related death in the Western world. Colorectal cancer causes 655,000 deaths worldwide per year.[2] Many colorectal cancers are thought to arise from adenomatous polyps in the colon. These mushroom-like growths are usually benign, but some may develop into cancer over time. The majority of the time, the diagnosis of localized colon cancer is through colonoscopy. Therapy is usually through surgery, which in many cases is followed by chemotherapy.
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Cirrhosis is a consequence of chronic liver disease characterized by replacement of liver tissue by fibrotic scar tissue as well as regenerative nodules, leading to progressive loss of liver function. Cirrhosis is most commonly caused by alcoholism and hepatitis C, but has many other possible causes.
Ascites (fluid retention in the abdominal cavity) is the most common complication of cirrhosis and is associated with a poor quality of life, increased risk of infection, and a poor long-term outcome. Other potentially life-threatening complications are hepatic encephalopathy (confusion and coma) and bleeding from esophageal varices. Cirrhosis is generally irreversible once it occurs, and treatment generally focuses on preventing progression and complications. In advanced stages of cirrhosis the only option is a liver transplant.
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A pregnancy test is a test to determine whether or not a woman is pregnant.
The earliest test for pregnancy is a rosette inhibition assay for early pregnancy factor (EPF). EPF can be detected in blood within 48 hours of fertilization. However, testing for EPF is expensive and time consuming.
Most chemical tests for pregnancy look for the presence of the beta subunit of hCG or human chorionic gonadotropin in the blood or urine. hCG can be detected in urine or blood after implantation, which occurs six to twelve days after fertilization.
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The heart sounds are the noises (sound) generated by the beating heart and the resultant flow of blood through it. This is also called a heartbeat. In cardiac auscultation, an examiner uses a stethoscope to listen for these sounds, which provide important information about the condition of the heart.
In healthy adults, there are two normal heart sounds often described as a lub and a dub (or dup), that occur in sequence with each heart beat. These are the first heart sound (S1) and second heart sound (S2), produced by the closure of the AV valves and semilunar valves respectively. In addition to these normal sounds, a variety of other sounds may be present including heart murmurs and adventitious sounds.
Heart murmurs are generated by turbulent flow of blood, which may occur inside or outside the heart. Murmurs may be physiological (benign) or pathological (abnormal). Abnormal murmurs can be caused by stenosis restricting the opening of a heart valve, causing turbulence as blood flows through it. Valve insufficiency (or regurgitation) allows backflow of blood when the incompetent valve is supposed to be closed. Different murmurs are audible in different parts of the cardiac cycle, depending on the cause of the murmur.
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The aortic valve has three cusps. These cusps are half moon shaped hence also called aortic semilunar valve. Each cusp has a small swelling in the center called the nodule. Dilatation of the wall of the aorta behind these cusps is called aortic sinus. When the aortic valve is open, the normal size of the orifice is 3-4 cm² in adults.
During ventricular systole, pressure rises in the left ventricle. When the pressure in the left ventricle rises above the pressure in the aorta, the aortic valve opens, allowing blood to exit the left ventricle into the aorta. When ventricular systole ends, pressure in the left ventricle rapidly drops. When the pressure in the left ventricle decreases, the aortic pressure forces the aortic valve to close. The closure of the aortic valve contributes the A component of the second heart sound.
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Ulcerative colitis (Colitis ulcerosa, UC) is a form of inflammatory bowel disease (IBD). Ulcerative colitis is a form of colitis, a disease of the intestine, specifically the large intestine or colon, that includes characteristic ulcers, or open sores, in the colon. The main symptom of active disease is usually diarrhea mixed with blood, of gradual onset. Ulcerative colitis is, however, a systemic disease that affects many parts of the body outside the intestine. Because of the name, IBD is often confused with irritable bowel syndrome ("IBS"), a troublesome, but much less serious condition. Ulcerative colitis has similarities to Crohn's disease, another form of IBD. Ulcerative colitis is an intermittent disease, with periods of exacerbated symptoms, and periods that are relatively symptom-free. Although the symptoms of ulcerative colitis can sometimes diminish on their own, the disease usually requires treatment to go into remission.
Ulcerative colitis is a rare disease, with an incidence of about one person per 10,000 in North America. The disease tends to be more common in northern areas. Although ulcerative colitis has no known cause, there is a presumed genetic component to susceptibility. The disease may be triggered in a susceptible person by environmental factors. Although dietary modification may reduce the discomfort of a person with the disease, ulcerative colitis is not thought to be caused by dietary factors. Although ulcerative colitis is treated as though it were an autoimmune disease, there is no consensus that it is such. Treatment is with anti-inflammatory drugs, immunosuppression (suppressing the immune system), and biological therapy targeting specific components of the immune response. Colectomy (partial or total removal of the large bowel through surgery) is occasionally necessary, and is considered to be a cure for the disease.
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Henrietta Lacks (August 18, 1920 – October 4, 1951) was the involuntary donor of cells from her cancerous tumor, which were cultured by George Otto Gey to create an immortal cell line for medical research. This is now known as the HeLa cell line.
She was born as Henrietta Pleasant on August 18, 1920 in Roanoke, Virginia to Eliza (1886–1924) and John Randall Pleasant I (1881–1969). Eliza died giving birth to her tenth child in 1924. Sometime after his wife's death, John Pleasant took the children back to where their relatives on their mother's side lived, and where they were raised. In 1929, a 48 year old John, still living in Roanoke at 12th Street Southwest, married a 13 year old girl named Lillian. John worked as a brakeman on the railroad.
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Eyes are organs of vision that detect light. Different kinds of light-sensitive organs are found in a variety of organisms. The simplest eyes do nothing but detect whether the surroundings are light or dark, while more complex eyes can distinguish shapes and colors. The visual fields of some such complex eyes largely overlap, to allow better depth perception (binocular vision), as in humans; and others are placed so as to minimize the overlap, such as in rabbits and chameleons.
In most vertebrates and some mollusks, the eye works by allowing light to enter it and project onto a light-sensitive panel of cells known as the retina at the rear of the eye, where the light is detected and converted into electrical signals. These are then transmitted to the brain via the optic nerve. Such eyes are typically roughly spherical, filled with a transparent gel-like substance called the vitreous humour, with a focusing lens and often an iris which regulates the intensity of the light that enters the eye. The eyes of cephalopods, fish, amphibians and snakes usually have fixed lens shapes, and focusing vision is achieved by telescoping the lens—similar to how a camera focuses.
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The heart is a muscular organ responsible for pumping blood through the blood vessels by repeated, rhythmic contractions, or a similar structure in the annelids, mollusks, and arthropods.[3] The term cardiac (as in cardiology) means "related to the heart" and comes from the Greek καρδία, kardia, for "heart." The heart is composed of cardiac muscle, an involuntary muscle tissue which is found only within this organ.[4] The average human heart beating at 72 BPM, will beat approximately 2.5 billion times during a lifetime of 66 years.
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Magnetic resonance imaging (MRI), formerly referred to as magnetic resonance tomography (MRT) and, in scientific circles and as originally marketed by companies such as General Electric, Nuclear Magnetic Resonance Imaging (NMRI) or NMR zeugmatography imaging, is a non-invasive method used to render images of the inside of an object. It is primarily used in medical imaging to demonstrate pathological or other physiological alterations of living tissues. MRI also has uses outside of the medical field, such as detecting rock permeability to hydrocarbons and as a non-destructive testing method to characterize the quality of products such as produce and timber.
MRI should not be confused with the NMR spectroscopy technique used in chemistry, although both are based on the same principles of nuclear magnetic resonance. In fact MRI is NMR applied to the signal from water to acquire spatial information in place of chemical information about molecules. The same equipment can be used for both imaging and spectroscopy.
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Radiology is the medical specialty directing medical imaging technologies to diagnose and sometimes treat diseases. Originally it was the aspect of medical science dealing with the medical use of electromagnetic energy emitted by X-ray machines or other such radiation devices for the purpose of obtaining visual information as part of medical imaging. Radiology that involves use of x-ray is called roentgenology. Today, following extensive training, radiologists direct an array of imaging technologies (such as ultrasound, computed tomography (CT) and magnetic resonance imaging) to diagnose or treat disease. Interventional radiology is the performance of (usually minimally invasive) medical procedures with the guidance of imaging technologies. The acquisition of medical imaging is usually carried out by the radiographer or radiologic technologist. Outside of the medical field, radiology also encompasses the examination of the inner structure of objects using X-rays or other penetrating radiation.
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Morphine (INN) (IPA: [ˈmɔ(ɹ)fin]) is a highly potent opiate analgesic drug and is the principal active agent in opium and the prototypical opioid. Like other opiates, e.g. diacetylmorphine (heroin), morphine acts directly on the central nervous system (CNS) to relieve pain, and at synapses of the nucleus accumbens in particular. Studies done on the efficacy of various opioids have indicated that, in the management of severe pain, no other narcotic analgesic is more effective or superior to morphine. Morphine is highly addictive when compared to other substances, and tolerance, physical and psychological dependences develop very rapidly.
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Osteoarthritis / Osteoarthrosis (OA, also known as degenerative arthritis, degenerative joint disease, arthrosis or in more colloquial terms "wear and tear"), is a condition in which low-grade inflammation results in pain in the joints, caused by wearing of the cartilage that covers and acts as a cushion inside joints. As the bone surfaces become less well protected by cartilage, the patient experiences pain upon weight bearing, including walking and standing. Due to decreased movement because of the pain, regional muscles may atrophy, and ligaments may become more lax. OA is the most common form of arthritis.
OA affects nearly 21 million people in the United States, accounting for 25% of visits to primary care physicians, and half of all NSAID (Non-Steroidal Anti-Inflammatory Drugs) prescriptions. It is estimated that 80% of the population will have radiographic evidence of OA by age 65, although only 60% of those will be symptomatic.
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Inflammation (Latin, inflammatio, to set on fire) is the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. It is a protective attempt by the organism to remove the injurious stimuli as well as initiate the healing process for the tissue. Inflammation is not a synonym for infection. Even in cases where inflammation is caused by infection it is incorrect to use the terms as synonyms: infection is caused by an exogenous pathogen, while inflammation is the response of the organism to the pathogen.
In the absence of inflammation, wounds and infections would never heal and progressive destruction of the tissue would compromise the survival of the organism. However, inflammation which runs unchecked can also lead to a host of diseases, such as hay fever, atherosclerosis, and rheumatoid arthritis. It is for this reason that inflammation is normally tightly regulated by the body.
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Rudolf Ludwig Karl Virchow (born October 13, 1821, in Schivelbein (Pomerania); died September 5, 1902, in Berlin) was a German doctor, anthropologist, public health activist, pathologist, prehistorian, biologist and politician. He is referred to as the "Father of Pathology".
From a farming family of relatively modest means, Virchow studied medicine in Berlin at the military academy of Prussia on a scholarship. When he graduated in 1842 he went to serve as Robert Froriep's assistant at the Berlin Charité rather than the expected military service. One of his major contributions to German medical education was to encourage the use of microscopes by medical students and was known for constantly urging his students to 'think microscopically'. The campus where this Charité hospital is located is named after him, the Campus Virchow Klinikum.
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Gene therapy is the insertion of genes into an individual's cells and tissues to treat a disease, and hereditary diseases in which a defective mutant allele is replaced with a functional one. Although the technology is still in its infancy, it has been used with some success. Antisense therapy is not strictly a form of gene therapy, but is a genetically-mediated therapy and is often considered together with other methods.
In the 1980s, advances in molecular biology had already enabled human genes to be sequenced and cloned. Scientists looking for methods of easily producing proteins — such as insulin, the protein deficient in diabetes mellitus type 1 — investigated introducing human genes to bacterial DNA. The modified bacteria then produce the corresponding protein, which can be harvested and injected in people who cannot produce it naturally.
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An artificial heart is a prosthetic device that is implanted into the body to replace the biological heart. It is distinct from a cardiopulmonary bypass machine (CPB), which is an external device used to provide the functions of both the heart and the lungs. The CPB oxygenates the blood, so does not need to be connected to both blood circuits. Also, a CPB is only suitable for a few hours use, while artificial hearts have so far been used for periods of long over a year (as of 2007).
A synthetic replacement for the heart remains one of the long-sought holy grails of modern medicine. The obvious benefit of a functional artificial heart would be to lower the need for heart transplants, because the demand for donor hearts (as it is for all organs) always greatly exceeds supply.
Although the heart is conceptually simple (basically a muscle that functions as a pump), it embodies subtleties that defy straightforward emulation with synthetic materials and power supplies. Consequences of these issues include severe foreign-body rejection and external batteries that limit patient mobility. These complications limited the lifespan of early human recipients to hours or days.
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A pacemaker (or artificial pacemaker, so as not to be confused with the heart's natural pacemaker) is a medical device which uses electrical impulses, delivered by electrodes contacting the heart muscles, to regulate the beating of the heart. The primary purpose of a pacemaker is to maintain an adequate heart rate, either because the heart's native pacemaker is not fast enough, or there is a block in the heart's electrical conduction system. Modern pacemakers are externally programmable and allow the cardiologist to select the optimum pacing modes for individual patients. Some combine a pacemaker and implantable defibrillator in a single implantable device. Others have multiple electrodes stimulating differing positions within the heart to improve synchronisation of the lower chambers of the heart.
In 1889 J A McWilliam reported in the British Medical Journal of his experiments in which application of an electrical impulse to the human heart in asystole caused a ventricular contraction and that a heart rhythm of 60-70 beats per minute could be evoked by impulses applied at spacings equal to 60-70/minute.
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X-rays (or Röntgen rays) are a form of electromagnetic radiation with a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 to 30 000 PHz (1 PHz = 1015 Hertz). X-rays are primarily used for diagnostic radiography and crystallography. X-rays are a form of ionizing radiation and as such can be dangerous. In many languages it is called Röntgen radiation after one of the first investigators of the X-rays, Wilhelm Conrad Röntgen.
The average person living in the United States is exposed to approximately 360 mrem annually from background sources alone.
All human societies have medical beliefs that provide explanations for, and responses to birth, death, and disease. Throughout the world, illness has often been attributed to witchcraft, demons, averse astral influence, or the will of the gods, ideas that retain some power, with faith healing and shrines still common, although the rise of scientific medicine in the past two centuries has altered or replaced many historic health practices.
There is no actual record of when the use of plants for medicinal purposes first started, although the first generally accepted use of plants as healing agents were depicted in the cave paintings discovered in the Lascaux caves in France, which have been Radiocarbon dated to between 13,000 - 25,000 BC.
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Autism is a brain development disorder that shows symptoms before a child is three years old and has a steady course with no remission. Its characteristic signs are impairments in social interaction and communication, as well as restricted and repetitive behavior. These characteristics distinguish autism from milder pervasive developmental disorders (PDD) or autism spectrum disorders (ASD), and reflect Leo Kanner's first descriptions of autism, which emphasized "autistic aloneness" and "insistence on sameness".
Heritability contributes about 90% of the risk of a child developing autism, but the genetics of autism are complex and typically it is unclear which genes are responsible. In rare cases, autism is strongly associated with agents that cause birth defects. Many other causes have been proposed, such as exposure of children to vaccines; these proposals are controversial and the vaccine hypotheses have no convincing scientific evidence.
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Theobromine, also known as xantheose, is a bitter alkaloid of the cacao plant, and is therefore found in chocolate. It is in the methylxanthine class of chemical compounds, which also includes the similar compounds theophylline and caffeine. Despite its name, the compound contains no bromine — theobromine is derived from Theobroma, the name of the genus of the cacao tree, (which itself is made up of the Greek roots theo ("God") and broma ("food"), meaning "food of the gods") with the suffix -ine given to alkaloids and other basic nitrogen-containing compounds.
Theobromine is a water insoluble, crystalline, bitter powder; the colour has been listed as either white or colourless.
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The evolution of sex is a major puzzle in modern evolutionary biology. Many groups of organisms, notably the majority of animals and plants, reproduce sexually. The evolution of sex contains two related, yet distinct, themes: its origin and its maintenance. However, since the hypotheses for the origins of sex are difficult to test experimentally, most current work has been focused on the maintenance of sexual reproduction. Several explanations have been suggested by biologists including W. D. Hamilton, Alexey Kondrashov, and George C. Williams to explain how sexual reproduction is maintained in a vast array of different living organisms.
It seems that a sexual cycle is maintained because it improves the quality of progeny (fitness), despite reducing the overall number of offspring (twofold cost of sex). In order for sex to be evolutionarily advantageous, it must be associated with a significant increase in the fitness of offspring.
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Metformin (INN; trade names Glucophage, Diabex, Diaformin, Fortamet, Riomet, Glumetza and others) is an anti-diabetic drug from the biguanide class of oral antihyperglycemic agents. Other biguanides include the withdrawn agents phenformin and buformin. Metformin is the most popular anti-diabetic drug in the United States and one of the most prescribed drugs overall, with nearly 35 million prescriptions filled in 2006 for generic metformin alone.
The biguanide class of anti-diabetic drugs originates from the French lilac (Galega officinalis), a plant known for several centuries to reduce the symptoms of diabetes mellitus. (More...)
The genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences) by living cells. Specifically, the code defines a mapping between tri-nucleotide sequences called codons and amino acids; every triplet of nucleotides in a nucleic acid sequence specifies a single amino acid. Because the vast majority of genes are encoded with exactly the same code (see #RNA codon table), this particular code is often referred to as the canonical or standard genetic code, or simply the genetic code, though in fact there are many variant codes (thus, the canonical genetic code is not universal). For example, in humans, protein synthesis in mitochondria relies on a genetic code that varies from the canonical code. (More...)
Lung cancer is the malignant transformation and expansion of lung tissue, and is responsible for 1.3 million deaths worldwide annually. It is the most common cause of cancer-related death in men, and the second most common in women.
Current research indicates that the factor with the greatest impact on risk of lung cancer is long-term exposure to inhaled carcinogens, especially tobacco smoke. While some people who have never smoked do still get lung cancer, this appears to be due to a combination of genetic factors and exposure to secondhand smoke. Radon gas and air pollution may also contribute to the development of lung cancer.
Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient's performance status. Treatments include surgery, chemotherapy, and radiotherapy. (More...)
Herpes zoster, colloquially known as shingles, is the reactivation (from the general area of the spinal cord) of varicella zoster virus (VZV, primary infection of which leads to chickenpox), one of the Herpesviridae group, leading to a crop of painful blisters over the area of a dermatome. In Italy and in Malta, it is sometimes referred to as "St. Anthony's fire", although that name usually refers to ergotism.[5][6] Shingles, or herpes zoster, is a neurological disease. affecting the nervous system, with or without the appearance of a rash on the skin. (More...)
Renal tubular acidosis (RTA) is a medical condition that involves an accumulation of acid in the body due to a failure of the kidneys to appropriately acidify the urine. When blood is filtered by the kidney, the filtrate passes through the tubules of the nephron, allowing for exchange of salts, acid equivalents, and other solutes before it drains into the bladder as urine. The metabolic acidosis that results from RTA may be caused either by failure to recover sufficient (alkaline) bicarbonate ions from the filtrate in the early portion of the nephron (proximal tubule) or by insufficient secretion of (acid) hydrogen ions into the latter portions of the nephron (distal tubule). Although a metabolic acidosis also occurs in those with renal insufficiency, the term RTA is reserved for individuals with poor urinary acidification in otherwise well-functioning kidneys. Several different types of RTA exist, which all have different syndromes and different causes. (More...)
Henipavirus is a genus of the family Paramyxoviridae, order Mononegavirales containing two members, Hendravirus and Nipahvirus. The henipaviruses are naturally harboured by Pteropid fruit bats (flying foxes) and are characterised by a large genome, a wide host range and their recent emergence as zoonotic pathogens capable of causing illness and death in domestic animals and humans.
Henipaviruses are pleomorphic (variably shaped), ranging in size from 40 to 600 nm in diameter. They possess a lipid membrane overlying a shell of viral matrix protein. At the core is a single helical strand of genomic RNA tightly bound to N (nucleocapsid) protein and associated with the L (large) and P (phosphoprotein) proteins which provide RNA polymerase activity during replication. (More...)
Doxorubicin (trade name Adriamycin) or hydroxyldaunorubicin is a DNA-interacting drug widely used in chemotherapy. It is an anthracycline antibiotic and structurely closely related to daunomycin, and also intercalates DNA. It is commonly used in the treatment of a wide range of cancers.
The drug is administered by injection, and may be sold under the brand names Adriamycin PFS, Adriamycin RDF, or Rubex. Doxil is a liposome-encapsulated dosage form of doxorubicin made by Ben Venue Laboratories for Johnson & Johnson. The main benefits of this form are a reduction in cardiotoxicity. (More...)
The maxillary central incisor is a human tooth in the front upper jaw, or maxilla, and is usually the most visible of all teeth in the mouth. It is located mesial (closer to the midline of the face) to the maxillary lateral incisor. As with all incisors, their function is for shearing or cutting food during mastication (chewing). There are no cusps on the teeth. Instead, the surface area of the tooth used in eating is called an incisal ridge or incisal edge. Formation of these teeth begin at 14 weeks in utero for the deciduous (baby) set and 3–4 months of age for the permanent set.
There are some minor differences between the deciduous maxillary central incisor and that of the permanent maxillary central incisor. The deciduous tooth appears in the mouth at 10 months of age and is replaced by the permanent tooth around 7–8 years of age. The permanent tooth is larger and is longer than it is wide. The maxillary central incisors contact each other at the midline of the face. (More...)
An ambulance is a vehicle for transporting people to, from or between places of treatment for an illness or injury. In the modern context it is also the vehicle commonly used to bring medical care to patients outside of the hospital and, when appropriate, to transport the patient to hospital for follow-up care and further testing. There is also a modified form of the ambulance used in several jurisdictions that only carries one member of ambulance crew to the scene to provide care but is not used to transport the patient. In these cases a patient who requires transportation to hospital will require a patient carrying ambulance to attend in addition to the fast responder.
The term ambulance comes from the Latin word ambulare, meaning to walk or move about [7] which is a reference to early medical care where patients were moved by lifting or wheeling. The word is most commonly associated with the land-based, motorized emergency vehicles that administer emergency care to those with acute illnesses or injuries, hereafter known as emergency ambulances. These are usually fitted with flashing warning lights and sirens to facilitate their movement through traffic. (More...)
Measles, also known as rubeola, is a disease caused by a virus, specifically a paramyxovirus of the genus Morbillivirus.
Reports of measles go back to at least 600 BCE, however, the first scientific description of the disease and its distinction from smallpox is attributed to the Persian physician Ibn Razi (Rhazes) 860-932 who published a book entitled "Smallpox and Measles" (in Arabic: Kitab fi al-jadari wa-al-hasbah). In 1954, the virus causing the disease was isolated, and licensed vaccines to prevent the disease became available in 1963.
Measles is spread through respiration (contact with fluids from an infected person's nose and mouth, either directly or through aerosol transmission), and is highly contagious—90% of people without immunity sharing a house with an infected person will catch it. Airborne precautions should be taken for all suspected cases of measles. (More...)
A psychoactive drug or psychotropic substance is a chemical substance that acts primarily upon the central nervous system where it alters brain function, resulting in temporary changes in perception, mood, consciousness and behavior. These drugs may be used recreationally to purposefully alter one's consciousness, as entheogens for ritual or spiritual purposes, or as medication.
Many of these substances (especially the stimulants and depressants) can be habit-forming, causing chemical dependency and may lead to substance abuse. Conversely, others (namely the psychedelics) can help to treat and even cure such addictions. (More...)
Coeliac disease or celiac disease is an autoimmune disorder of the small bowel that occurs in genetically predisposed individuals in all age groups after early infancy. Symptoms may include diarrhoea, failure to thrive (in children) and fatigue, but these may be absent and associated symptoms in all other organ systems have been described. It affects approximately 1% of Caucasian populations, though it is significantly underdiagnosed. A growing portion of diagnoses are being made in asymptomatic persons as a result of increasing screening.
Coeliac disease is caused by a reaction to gliadin, a gluten protein found in wheat (and similar proteins of the tribe Triticeae which includes other cultivars such as barley and rye). Upon exposure to gliadin, the enzyme tissue transglutaminase modifies the protein, and the immune system cross-reacts with the bowel tissue, causing an inflammatory reaction. That leads to flattening of the lining of the small intestine, which interferes with the absorption of nutrients. The only effective treatment is a lifelong gluten-free diet. (More...)
Cholangiocarcinoma is a cancer of the bile ducts, which drain bile from the liver into the small intestine. It is a relatively rare cancer, with an annual incidence of 1–2 cases per 100,000 in the Western world, but rates of cholangiocarcinoma have been rising worldwide over the past several decades. Risk factors for cholangiocarcinoma include primary sclerosing cholangitis (an inflammatory disease of the bile ducts), congenital liver malformations, infection with the parasitic liver flukes Opisthorchis viverrini or Clonorchis sinensis, and exposure to Thorotrast (thorium dioxide), a chemical previously used in medical imaging. The symptoms of cholangiocarcinoma include jaundice, weight loss, and sometimes generalized itching. The disease is diagnosed through a combination of blood tests, imaging, endoscopy, and sometimes surgical exploration.
Surgery is the only potentially curative treatment, but most patients have advanced and inoperable disease at the time of diagnosis. After surgery, adjuvant chemotherapy or radiation therapy may be given to increase the chances of cure. Patients with advanced and inoperable cholangiocarcinoma are generally treated with chemotherapy and palliative care measures. Areas of ongoing medical research in cholangiocarcinoma include the use of newer targeted therapies (such as erlotinib) and the use of photodynamic therapy. (More...)
Pathology (from Greek pathos, feeling, pain, suffering; and logos, study of; see also -ology) is the study and diagnosis of disease through examination of molecules, cells, tissues and organs. The term encompasses both the medical specialty which uses tissues and body fluids to obtain clinically useful information, as well as the related scientific study of disease processes.
The histories of both investigative and medical pathology can be traced to the earliest application of the scientific method to the field of medicine, a development which occurred in Western Europe during the Italian Renaissance. Most early pathologists were also practicing physicians or surgeons. Like other medical fields, pathology has become more specialized with time, and most pathologists today do not practice in other areas of medicine. (More...)
The International Red Cross and Red Crescent Movement is an international humanitarian movement whose stated mission is to protect human life and health, to ensure respect for the human being, and to prevent and alleviate human suffering, without any discrimination based on nationality, race, religious beliefs, class or political opinions.
The often-heard term International Red Cross is actually a misnomer, as no official organization as such exists bearing that name. In reality, the movement consists of several distinct organizations that are legally independent from each other, but are united within the Movement through common basic principles, objectives, symbols, statutes, and governing organs.
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The 2007 Bernard Matthews H5N1 outbreak was an occurrence of avian flu in England that began on January 30, 2007. The infection was caused by the H5N1 subtype of the Influenza A virus and occurred at one of Bernard Matthews' farms in Holton in Suffolk. A range of precautions were instituted including a large cull of turkeys, the imposition of segregation zones, and a disinfection programme for the plant.
Though the cause of the outbreak was not determined, Bernard Matthews regularly transports turkeys and turkey products between the UK and its plant in Hungary, and the H5N1 bird flu strains found in Hungary and Britain are effectively genetically identical. (More...)
Crohn's disease (also known as regional enteritis) is a chronic, episodic, inflammatory condition of the gastrointestinal tract characterized by transmural inflammation (affecting the entire wall of the involved bowel) and skip lesions (areas of inflammation with areas of normal lining in between). Crohn's disease is a type of inflammatory bowel disease (IBD) and may sometimes affect any part of the gastrointestinal tract from mouth to anus; as a result, the symptoms of Crohn's disease can vary between affected individuals. The main gastrointestinal symptoms are abdominal pain, diarrhea, which may be bloody, and weight loss. Crohn's disease can also cause complications outside of the gastrointestinal tract such as skin rashes, arthritis, and inflammation of the eye. (More...)
Endoscopic foreign body retrieval refers to the removal of ingested objects from the esophagus, stomach and duodenum by endoscopic techniques. It does not involve surgery, but rather encompasses a variety of techniques employed through the gastroscope for grasping foreign bodies, manipulating them, and removing them while protecting the esophagus and trachea.
It is of particular importance with children, people with mental illness and prison inmates as these groups have a high rate of foreign body ingestion. (More...)
Anabolic androgenic steroids are a class of natural and synthetic steroid hormones that promote cell growth and division, resulting in growth of several types of tissues, especially muscle and bone. Different anabolic androgenic steroids have varying combinations of androgenic and anabolic properties, and are often referred to in medical texts as AAS (anabolic/androgenic steroids). Anabolism is the metabolic process that builds larger molecules from smaller ones.
Anabolic steroids were first discovered in the early 1930s and have since been used for numerous medical purposes including stimulation of bone growth, appetite, puberty, and muscle growth. The most widespread use of anabolic steroids is their use for chronic wasting conditions, such as cancer and AIDS. Anabolic steroids can produce numerous physiological effects including increases in protein synthesis, muscle mass, strength, appetite and bone growth. (More...)
The 1918 flu pandemic was an influenza pandemic between 1918 and 1920 caused by an unusually severe and deadly strain of the subtype H1N1 of the species Influenza A virus. By far the most destructive influenza pandemic in history, it killed some 50 million to 100 million people worldwide (2.5 – 5% of the human population) in just 18 months, dwarfing the simultaneous bloodshed due to World War I. Furthermore, many of its victims were healthy young adults, in contrast to most influenza outbreaks which predominantly affect juvenile, elderly, or otherwise weakened patients.
Despite not having originated in Spain, the Allies of World War I came to call it the Spanish Flu. This was mainly because the pandemic received greater press attention in Spain than in the rest of the world, as Spain was not involved in the war and had not imposed wartime censorship. (More...)
An abortion is the removal or expulsion of an embryo or fetus from the uterus, resulting in or caused by its death. This can occur spontaneously as a miscarriage, or be artificially induced by chemical, surgical or other means. Commonly, "abortion" refers to an induced procedure at any point during pregnancy; medically, it is defined as miscarriage or induced termination before twenty weeks' gestation, which is considered nonviable.
Throughout history abortion has been induced by various methods. The moral and legal aspects of abortion are subject to intense debate in many parts of the world. (More...)
A Schatzki ring or Schatzki-Gary ring is a ring found in the lower part of the esophagus that can cause difficulty swallowing. The ring is made up of mucosal tissue (which lines the esophagus) or muscular tissue.[8] Patients with Schatzki rings can develop intermittent dysphagia or difficulty swallowing, or more seriously, with a completely blocked esophagus. The ring is named after the American physician, Richard Schatzki. (More...)
Asperger syndrome (AS) is one of five neurobiological pervasive developmental disorders (PDD) that is characterized by deficiencies in social and communication skills. It is considered to be part of the autistic spectrum and is differentiated from other PDDs and from high functioning autism (HFA) in that early development is normal and there is no language delay. The diagnosis of AS is complicated by the lack of adoption of a standardized diagnostic screen, and, instead, the use of several different screening instruments and sets of diagnostic criteria. The exact cause of AS is unknown and the prevalence is not firmly established, due partly to the use of differing sets of diagnostic criteria.
Asperger syndrome is often not identified in early childhood, and many individuals do not receive diagnosis until after puberty or when they are adults. Assistance for core symptoms of AS consists of therapies that apply behavior management strategies and address poor communication skills, obsessive or repetitive routines, and physical clumsiness. Many individuals with AS can adopt strategies for coping and do lead fulfilling lives - being gainfully employed, getting married or having successful relationships, and having families. In most cases, they are aware of their differences and recognize when they need support to maintain an independent life. (More...)
The human genome is the genome of Homo sapiens, which is composed of 24 distinct chromosomes (22 autosomal + X + Y) with a total of approximately 3 billion DNA base pairs containing an estimated 20,000-25,000 genes. The Human Genome Project produced a reference sequence of the euchromatic human genome, which is used worldwide in biomedical sciences. The human genome is much more gene-sparse than was initially predicted at the outset of the Human Genome Project, with only about 1.5% of the total length serving as protein-coding exons. (More...)
A total of 29 human blood group systems are recognized by the International Society of Blood Transfusion (ISBT). The most significant of these are the ABO blood group system and the Rhesus blood group system.
Each blood group is represented by a substance on the surface of red blood cells (RBCs). These substances are important because they contain specific sequences of amino acid and carbohydrate that are antigenic. As well as being on the surface of RBCs, some of these antigens are also present on the cells of other tissues. (More...)
The first AIDS case was identified in Brazil in 1982. Infection rates climbed exponentially throughout the 1980s, and in 1990 the World Bank famously predicted 1,200,000 cases by 2000, approximately double the actual number reported by the Brazilian Ministry of Health and most international organizations.
The Brazilian experience is frequently cited as a model for other developing countries facing the AIDS epidemic, including the internationally controversial policies of the Brazilian government such as the universal provision of antiretroviral drugs (ARVs), progressive social policies toward risk groups, and collaboration with non-governmental organizations. (More...)
The Baby Gender Mentor test is a blood test designed to determine if a pregnant mother is carrying a boy or a girl. The test is made by Acu-Gen Biolab, Inc, a biotech company in Lowell, Massachusetts, in the United States and is marketed to detect the gender of a fetus as early as five weeks after conception. An estimated 50-70% of expectant parents would like to know the gender of their child ahead of delivering the baby. Some parents would like to know this information early in order to get a head start on shopping for baby clothes or decorating the nursery. Others have cited an interest in preparing themselves or the baby's siblings for gender-specific issues.
The test has been the center of several controversies. Some customers and scientists are questioning the accuracy of the test. A class-action lawsuit has been filed against Acu-Gen and a major supplier of the test is under criminal investigation. Concerns have also been raised by bioethicists that use of the test could lead to unethical practices such as gender selection. There have also been anecdotal reports of Acu-Gen making additional claims for use of the test in ways that are not described in the product packaging or on the company's website. (More...)
Rabies (Latin, rabies, "madness, rage, fury") is a viral zoonotic disease that causes acute encephalitis in animals. In non-vaccinated humans, rabies is almost invariably fatal after neurological symptoms have developed, but prompt post-exposure vaccination may prevent the virus from progressing.
Cats, dogs, ferrets, raccoons, skunks, foxes, wolves, coyotes, bears, bats, and horses can become rabid. Squirrels, chipmunks, other rodents (except beavers), and rabbits are very seldom infected. Rabies may also be present in a so-called "paralytic" form, rendering the victim abnormally quiet and withdrawn.
The virus is usually present in the saliva of a symptomatic rabid animal; the route of infection is nearly always by a bite, and causes the victim to be exceptionally aggressive. Transmission has occurred via an aerosol through mucous membranes; transmission in this form may have happened in people exploring caves populated by rabid bats. Transmission between humans is extremely rare, though it can happen through transplant surgery (see below for recent cases), or even more rarely through bites or kisses. (Read more...)
Osteonecrosis of the jaw (ONj) is a severe bone disease that affects the jaws, including the maxilla and the mandible. Jaw bone (osteo-) damage and death (-necrosis) occurs as a result of reduced local blood supply (ischaemia). The condition is thus included in the general category of ischaemic or avascular osteonecrosis (literally "dead bone from poor blood flow.").
Various forms of ONj have been described over the last 160 years, and a number of causes have been suggested in the literature. In recent years, an increased incidence of ONj has been associated with the use of high dosages of bisphosphonates, required by some cancer treatment regimens, especially when the patient undergoes subsequent dental procedures. The possible risk from lower oral doses of bisphosphonates, taken by patients to prevent or treat osteoporosis, remains uncertain. (More...)
The Black Death, also known as the Black Plague, was a devastating pandemic that first struck Europe in the mid-late-14th century (1347–1351), killing between a third and two-thirds of Europe's population. Almost simultaneous epidemics occurred across large portions of Asia and the Middle East during the same period, indicating that the European outbreak was actually part of a multi-regional pandemic. Including Middle Eastern lands, India and China, the Black Death killed at least 75 million people.
The Black Death had a drastic effect on Europe's population, irrevocably changing Europe's social structure. It was a serious blow to the Roman Catholic Church, Europe's predominant religious institution at the time, and resulted in widespread persecution of minorities such as Jews, Muslims, foreigners, beggars and lepers. The uncertainty of daily survival created a general mood of morbidity influencing people to live for the moment, as illustrated by Giovanni Boccaccio in The Decameron (1353). (More...)
Stem cells in humans are primal undifferentiated cells that retain the ability to produce an identical copy of themselves when they divide (clone) and differentiate into other cell types. In higher animals this function is the defining property of the deleted cells. Stem cells have the ability to act as a repair system for the body, because they can divide and differentiate, replenishing other cells as long as the host organism is alive.
Medical researchers believe stem cell research has the potential to change the face of human disease by being used to repair specific tissues or to grow organs. Yet there is general agreement that, "significant technical hurdles remain that will only be overcome through years of intensive research.". Current evidence indicates that some stem cells are involved in assisting cancer's proliferation, or worse yet, some stem cells act as cancer stem cells (CSC). (More...)
Down syndrome or trisomy 21 (British Down's syndrome) is a genetic condition resulting from the presence of all or part of an extra 21st chromosome. Down syndrome is characterized by a combination of major and minor abnormalities of body structure and function. Among features present in nearly all cases are impairment of learning and physical growth, and a recognizable facial appearance usually identified at birth. It is named after John Langdon Down, the British doctor who first described it in 1866.
Individuals with Down syndrome have lower than average cognitive ability, normally ranging from mild to moderate retardation. Some individuals may have average intelligence overall, but will generally have some amount of developmental disability, such as a tendency toward concrete thinking or naïveté. There is also a small number of individuals with Down syndrome with severe to profound mental retardation. The incidence of Down syndrome is estimated at 1 per 800 to 1 per 1000 births.(More...)
Prostate cancer is a disease in which cancer develops in the prostate, a gland in the male reproductive system. Cancer cells may spread (metastasize) from the prostate to other parts of the body, especially the bones and lymph nodes. Prostate cancer may cause pain, difficulty in urinating, erectile dysfunction and other symptoms.
Prostate cancer develops most frequently in men over fifty. This cancer can only occur in men; the prostate is exclusively of the male reproductive tract. It is the second most common type of cancer in men in the United States, where it is responsible for more male deaths than any other cancer except lung cancer. However, many men who develop prostate cancer never have symptoms, undergo no therapy, and eventually die of other causes. Many factors, including genetics and diet, have been implicated in the development of prostate cancer. (More...)
Acute myeloid leukemia (AML), also known as acute myelogenous leukemia, is a cancer of the myeloid line of white blood cells, characterized by the rapid proliferation of abnormal cells which accumulate in the bone marrow and interfere with the production of normal blood cells. AML is the most common acute leukemia affecting adults, and its incidence increases with age. While AML is a relatively rare disease overall, accounting for approximately 1.2% of cancer deaths in the United States, its incidence is expected to increase as the population ages.
The symptoms of AML are caused by replacement of normal bone marrow with leukemic cells, resulting in a drop in red blood cells, platelets, and normal white blood cells. While a number of risk factors for AML have been elucidated, the specific cause of AML remains unclear. As an acute leukemia, AML progresses rapidly and is typically fatal in weeks to months if untreated.
Acute myeloid leukemia is a potentially curable disease; however, only a minority of patients are cured with current therapy. AML is treated initially with chemotherapy aimed at inducing a remission; some patients may go on to receive a hematopoietic stem cell transplant. (More...)
Yellow fever (also called yellow jack, black vomit or vomito negro in Spanish, or sometimes American Plague) is an acute viral disease. It is an important cause of hemorrhagic illness in many African and South American countries despite existence of an effective vaccine. The yellow in the disease name refers to the jaundice that affects some patients.
Yellow fever has been a source of several devastating epidemics. During one of Napoleon's campaigns to Haiti in 1802, the troops were attacked by yellow fever. More than half of the army perished due to the disease. Outbreaks followed by thousands of fatalities occurred periodically in other Western Hemisphere locations until research which included human volunteers (some of whom died) led to an understanding of the method of transmission to humans (primarily by mosquitos) and development of a vaccine and other preventative efforts in the early 20th century. (More...)
Tourette syndrome is an inherited neurological disorder with onset in childhood, characterized by the presence of multiple physical (motor) tics and at least one vocal (phonic) tic; these tics usually wax and wane. Tourette's is defined as part of a spectrum of tic disorders, which includes transient and chronic tics.
Tourette's was once considered a rare and bizarre syndrome, most often associated with the exclamation of obscene words or socially inappropriate and derogatory remarks (coprolalia). However, this symptom is present in fewer than 15% of people with Tourette's. It is no longer considered a rare condition, but it may not always be correctly identified because of the wide range of severity, with most cases classified as mild. Genetic and environmental factors each play a role in the etiology of Tourette's, but the exact causes are unknown. (More...)
Barbara McClintock (June 16, 1902 – September 2, 1992) was a pioneering American scientist and one of the world's most distinguished cytogeneticists. McClintock received her PhD in botany from Cornell University in 1927, where she was a leader in the development of maize cytogenetics. The field remained the focus of her research for the rest of her career. From the late 1920s, McClintock studied chromosomes and how they change during reproduction in maize. Her work was groundbreaking: she developed the technique to visualize maize chromosomes and used microscopic analysis to demonstrate many fundamental genetic ideas, including genetic recombination by crossing-over during meiosis—a mechanism by which chromosomes exchange information. She produced the first genetic map for maize, linking regions of the chromosome with physical traits, and she demonstrated the role of the telomere and centromere, regions of the chromosome that are important in the conservation of genetic information. She was recognized amongst the best in the field, awarded prestigious fellowships and elected a member of the National Academy of Sciences in 1944. (More...)
Lesch-Nyhan syndrome (LNS) is a rare, inherited disorder caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT). LNS is an X-linked recessive disease: the gene is carried by the mother and passed on to her son. LNS is present at birth in baby boys. Patients have severe mental and physical problems throughout life. The lack of HPRT causes a build-up of uric acid in all body fluids, and leads to problems such as severe gout, poor muscle control, and moderate mental retardation, which appear in the first year of life. A striking feature of LNS is self-mutilating behaviors, characterized by lip and finger biting, that begin in the second year of life. Abnormally high uric acid levels can cause sodium urate crystals to form in the joints, kidneys, central nervous system and other tissues of the body, leading to gout-like swelling in the joints and severe kidney problems. Neurological symptoms include facial grimacing, involuntary writhing, and repetitive movements of the arms and legs similar to those seen in Huntington's disease. The direct cause of the neurological abnormalities remains unknown. Because a lack of HPRT causes the body to poorly utilize vitamin B12, some boys may develop a rare disorder called megaloblastic anemia. (More...)
DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as UV light can cause DNA damage, resulting in as many as 1 million individual molecular lesions per cell per day. Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene that the affected DNA encodes. Other lesions induce potentially harmful mutations in the cell's genome, which will affect the survival of its daughter cells after it undergoes mitosis. Consequently, the DNA repair process must be constantly active so it can respond rapidly to any damage in the DNA structure.
The DNA repair ability of a cell is vital to the integrity of its genome and thus to its normal functioning and that of the organism. Many genes that were initially shown to influence lifespan have turned out to be involved in DNA damage repair and protection. Failure to correct molecular lesions in cells that form gametes can introduce mutations into the genomes of the offspring and thus influence the rate of evolution. (More...)
Multiple sclerosis (abbreviated MS, also known as disseminated sclerosis) is a chronic, inflammatory disease that affects the central nervous system (CNS). MS can cause a variety of symptoms, including changes in sensation, visual problems, muscle weakness, depression, difficulties with coordination and speech, and pain. Although many patients lead full and rewarding lives, MS can cause impaired mobility and disability in the more severe cases.
Multiple sclerosis affects neurons, the cells of the brain and spinal cord that carry information, create thought and perception and allow the brain to control the body. Surrounding and protecting some of these neurons is a fatty layer known as the myelin sheath, which helps neurons carry electrical signals. MS causes gradual destruction of myelin (demyelination) and transection of neuron axons in patches throughout the brain and spinal cord, causing various symptoms depending upon which signals are interrupted. The name multiple sclerosis refers to the multiple scars (or scleroses) on the myelin sheaths. It is thought that MS results from attacks by an individual's immune system on the nervous system and is therefore categorized as an autoimmune disease.
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Acquired immunodeficiency syndrome or acquired immune deficiency syndrome (AIDS or aids) is a collection of symptoms and infections in humans resulting from the specific damage to the immune system caused by infection with the human immunodeficiency virus (HIV). The late stage of the condition leaves individuals prone to opportunistic infections and tumors. Although treatments for AIDS and HIV exist to slow the virus's progression, there is no known cure. HIV is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk. This transmission can come in the form of anal, vaginal or oral sex, blood transfusion, contaminated needles, exchange between mother and baby during pregnancy, childbirth, or breastfeeding, or other exposure to one of the above bodily fluids.
Most researchers believe that HIV originated in sub-Saharan Africa during the twentieth century; it is now a pandemic, with an estimated 38.6 million people now living with the disease worldwide.
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Paracetamol (INN) (IPA: [pærəˈsitəmɒl, -moʊl, -ˈsɛtə-]) or acetaminophen (USAN) (brand names Tylenol® in US and Panadol® in UK), is a common analgesic and antipyretic drug that is used for the relief of fever, headaches, and other minor aches and pains. Paracetamol is also useful in managing more severe pain, allowing lower dosages of additional NSAID or opioid analgesics to be used, so minimising overall side-effects. It is a major ingredient in numerous cold and flu medications and many prescription analgesics. It is remarkably safe in recommended doses, but because of its wide availability, deliberate or accidental overdoses are fairly common.
The words acetaminophen and paracetamol both come from the chemical names for the compound: N-acetyl-para-aminophenol and para-acetyl-amino-phenol. In some contexts, it is shortened to apap, for N-acetyl-para-amino-phenol. (More...)
Tooth enamel is the hardest and most highly mineralized substance of the body, and with dentin, cementum, and dental pulp is one of the four major parts of the tooth. It is the normally visible dental tissue of a tooth and must be supported by underlying dentin. Ninety-six per cent of enamel consists of minerals, with water and organic material composing the rest. The normal color of enamel varies from light yellow to grayish white. At the edges of teeth where there is no dentin underlying the enamel, the color sometimes has a slightly blue tone. Since enamel is semitranslucent, the color of dentin and any restorative dental material underneath the enamel strongly affects the appearance of a tooth. Enamel varies in thickness over the surface of the tooth and is often thickest at the cusp, up to 2.5 mm, and thinnest at its border, which is seen clinically as the cementoenamel junction (CEJ).
Enamel's primary mineral is hydroxyapatite, which is a crystalline calcium phosphate. The large amount of minerals in enamel accounts not only for its strength but also for its brittleness. Dentin, which is less mineralized and less brittle, compensates for enamel and is necessary as a support. (More...)
The menstrual cycle is a recurring cycle of physiological changes in the females of some animal species that is associated with reproductive fertility. Only human beings and the great apes experience a true menstrual cycle. Most placental mammals experience estrus instead. The menstrual cycle is under the control of the reproductive hormone system and is necessary for reproduction. In women, menstrual cycles occur typically on a monthly basis between puberty and menopause.
During the menstrual cycle, the sexually mature female body builds up the lining of the uterus with gradually increasing amounts of estrogen, and when this hormone reaches a critical level, estradiol is produced, and shortly thereafterward there is the stimulation of the ovaries with Follicle Stimulating Hormone, and luteinizing hormone. Follicles begin developing, and within a few days one "matures" into an ovum or egg. The ovary then releases this egg, (or occasionally two, which might result in dizygotic, or non-identical, twins) at the time of ovulation. The lining of the uterus, the endometrium, peaks shortly there afterward in a synchronised fashion. After ovulation, this lining changes to prepare for potential conception and implantation of the fertilized egg to establish a pregnancy. The hormone progesterone rises after ovulation, and peaks shortly thereafter. (More...)
Tooth development is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth. Although many diverse species have teeth, non-human tooth development is largely the same as in humans. For human teeth to have a healthy oral environment, enamel, dentin, cementum, and the periodontium must all develop during appropriate stages of fetal development. Primary (baby) teeth start to form between the sixth and eighth weeks in utero, and permanent teeth begin to form in the twentieth week in utero. If teeth do not start to develop at or near these times, they will not develop at all.
A significant amount of research has focused on determining the processes that initiate tooth development. It is widely accepted that there is a factor within the tissues of the first branchial arch that is necessary for the development of teeth. (More...)
Pneumonia is an illness of the lungs and respiratory system in which the alveoli (microscopic air-filled sacs of the lung responsible for absorbing oxygen from the atmosphere) become inflamed and flooded with fluid. Pneumonia can result from a variety of causes, including infection with bacteria, viruses, fungi, or parasites. Pneumonia may also occur from chemical or physical injury to the lungs, or indirectly due to another medical illness, such as lung cancer or alcohol abuse.
Typical symptoms associated with pneumonia include cough, chest pain, fever, and difficulty breathing. Diagnostic tools include x-rays and examination of the sputum. Treatment depends on the cause of pneumonia; bacterial pneumonia is treated with antibiotics.
Pneumonia is a common illness, occurs in all age groups, and is a leading cause of death among the elderly and people who are chronically ill. Vaccines to prevent certain types of pneumonia are available. The prognosis for an individual depends on the type of pneumonia, the appropriate treatment, any complications, and the person's underlying health. (More...)
Médecins Sans Frontières (<phonos file="Fr-Médecins Sans Frontières.oga">pronunciation</phonos>) is a secular humanitarian-aid non-governmental organisation best known for its projects in war-torn regions and developing countries facing endemic disease.
Médecins Sans Frontières was created in 1971 by a small group of French doctors, as an aftermath of the Biaffra secession. The organisation is known to much of the world by its French name or simply as MSF. In many countries (such as the United States), the English-translated name Doctors Without Borders is used instead. (More...)
Tuberculosis (commonly abbreviated as TB) is an infection caused by the bacterium Mycobacterium tuberculosis, which most commonly affects the lungs (pulmonary TB) but can also affect the central nervous system (meningitis), lymphatic system, circulatory system (Miliary tuberculosis), genitourinary system, bones and joints.
Tuberculosis is one of the most deadly and common major infectious diseases today. As of 2004, 14.6 million people have active TB disease with nine million new cases of the disease and nearly two million deaths, mostly in developing countries. However, developing countries are not the only places with tuberculosis. There is a rising number of people in the developed world who contract tuberculosis because they have compromised immune systems, typically as a result of immunosupressive drugs or HIV/AIDS. These people are at particular risk of tuberculosis infection and active tuberculosis disease. (More...)
Keratoconus (from Greek: kerato- horn, cornea; and konos cone), is a degenerative non-inflammatory disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal, gradual curve. Keratoconus can cause substantial distortion of vision, with multiple images, streaking and sensitivity to light all often reported by the patient. Though frequently thought of as a rare condition, keratoconus is the most common dystrophy of the cornea, affecting around one person in a thousand, and it seems to occur equally in all ethnic groups worldwide. It is typically diagnosed in the patient's adolescent years and attains its most severe state in the twenties and thirties. (More...)
Chagas disease (also called American trypanosomiasis) is a human tropical parasitic disease which occurs in the Americas, particularly in South America. Its pathogenic agent is a flagellate protozoan named Trypanosoma cruzi, which is transmitted to humans and other mammals mostly by hematophagous assassin bugs of the subfamily Triatominae (Family Reduviidae). Those insects are known by numerous common names varying by country, including benchuca, vinchuca, kissing bug, chipo, barbeiro, etcetera. The most common insect species belong to the genera Triatoma, Rhodnius, and Panstrongylus. Other forms of transmission are possible, though, such as ingestion of food contaminated with parasites, blood transfusion and fetal transmission.
Trypanosoma cruzi is a member of the same genus as the infectious agent of African sleeping sickness, but its clinical manifestations, geographical distribution, life cycle and insect vectors are quite different. (More...)
Because of this 'updating' function of the cerebellum, lesions within it are not so debilitating as to cause paralysis, but rather present as feedback deficits resulting in disorders in fine movement, equilibrium, posture, and motor learning. Initial observations by physiologists during the 18th century indicated that patients with cerebellar damage show problems with motor coordination and movement. Research into cerebellar function during the early to mid 19th century was done via lesion and ablation studies in animals. Research physiologists noted that such lesions led to animals with strange movements, awkward gait, and muscular weakness. These observations and studies led to the conclusion that the cerebellum was a motor control structure. However, modern research shows that the cerebellum has a broader role in a number of key cognitive functions, including attention and the processing of language, music, and other sensory temporal stimuli. (More...)
Schizophrenia is a psychiatric diagnosis that describes a mental disorder characterized by abnormalities in the perception or expression of reality. It most commonly manifests as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking with significant social or occupational dysfunction. Onset of symptoms typically occurs in young adulthood, with approximately 0.4–0.6% of the population affected. Diagnosis is based on the patient's self-reported experiences and observed behavior. No laboratory test for schizophrenia currently exists.
Studies suggest that genetics, early environment, neurobiology, psychological and social processes are important contributory factors; some recreational and prescription drugs appear to cause or worsen symptoms. Despite its etymology, schizophrenia is not the same as dissociative identity disorder, previously known as multiple personality disorder or split personality; in popular culture the two are often confused. Read more...
Al-Risalah al-Dhahabiah (Arabic: الرسالة الذهبیة , Arabic pronunciation: ['rɪsælætæ 'ðæhæ'biæ]; "The Golden Treatise") is a medical dissertation on health and remedies attributed to Ali ibn Musa al-Ridha (765–818), the eighth Imam of Shia. He wrote this dissertation in accordance with the demand of Ma'mun, the caliph of the time. It is revered as the most precious Islamic literature in the science of medicine, and was entitled "the golden treatise" as Ma'mun had ordered it written in gold ink. Chain of narrators is said to reach Muhammad ibn Jumhoor or al-Hassan ibn Muhammad al-Nawfali who is described as "highly esteemed and trustworthy" by al-Najjashi.
The treatise of Ali al-Ridha includes scientific branches such as Anatomy, Physiology, Chemistry and Pathology when medical science was still primitive. According to the treatise, one's health is determined by four humors of blood, yellow bile, black bile and phlegm, the suitable proportion of which maintains the health. The liver plays an important role in producing and maintaining the required proportions in the body. Ali al-Ridha describes the body as a kingdom whose king is the heart while the (blood) vessels, the limbs, and the brain are the laborers. (More...)
- ↑ Skinner, Henry Alan. 1949, "The Origin of Medical Terms". Baltimore: Williams & Wilkins
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