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Elek's Test
Elek's test or the Elek plate test is an '' in vitro'' test of virulence performed on specimens of ''Corynebacterium diphtheriae'', the bacteria that causes diphtheria. It is used to test for toxigenicity of ''C. diphtheriae'' strains. The test uses immunodiffusion. A strip of filter paper impregnated with diphtheria antitoxin is buried just beneath the surface of a special agar plate before the agar hardens. Strains to be tested are streaked with known positive and known negative toxigenic strains on the agar's surface in a line across the plate, and at a right angle to the antitoxin paper strip. After incubation for 24 hours at 37 degrees Celsius, plates are examined with transmitted light for the presence of fine precipitin lines at a 45-degree angle to the streaks. The presence of precipitin lines indicates that the strain produced toxin that reacted with the antitoxin. The test was characterized in 1949 by Hungarian-born British microbiologist Stephen Dyonis Elek (191 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In Vitro
''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology and its subdisciplines are traditionally done in labware such as test tubes, flasks, Petri dishes, and microtiter plates. Studies conducted using components of an organism that have been isolated from their usual biological surroundings permit a more detailed or more convenient analysis than can be done with whole organisms; however, results obtained from ''in vitro'' experiments may not fully or accurately predict the effects on a whole organism. In contrast to ''in vitro'' experiments, ''in vivo'' studies are those conducted in living organisms, including humans, and whole plants. Definition ''In vitro'' ( la, in glass; often not italicized in English usage) studies are conducted using components of an organism that have been isolated fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incubator (culture)
An incubator is a device used to grow and maintain microbiological cultures or cell cultures. The incubator maintains optimal temperature, humidity and other conditions such as the CO2 and oxygen content of the atmosphere inside. Incubators are essential for much experimental work in cell biology, microbiology and molecular biology and are used to culture both bacterial and eukaryotic cells. An incubator is made up of a chamber with a regulated temperature. Some incubators also regulate humidity, gas composition, or ventilation within that chamber. The simplest incubators are insulated boxes with an adjustable heater, typically going up to 60 to 65 °C (140 to 150 °F), though some can go slightly higher (generally to no more than 100 °C). The most commonly used temperature both for bacteria such as the frequently used E. coli as well as for mammalian cells is approximately 37 °C (99 °F), as these organisms grow well under such conditions. For other organisms used in biologi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vaccine Hesitancy
Vaccine hesitancy is a delay in acceptance, or refusal, of vaccines despite the availability of vaccine services and supporting evidence. The term covers refusals to vaccinate, delaying vaccines, accepting vaccines but remaining uncertain about their use, or using certain vaccines but not others. The scientific consensus that vaccines are generally safe and effective is overwhelming. Vaccine hesitancy often results in disease outbreaks and deaths from vaccine-preventable diseases. Therefore, the World Health Organization characterizes vaccine hesitancy as one of the top ten global health threats. "Anti-vaccinationism" refers to total opposition to vaccination; in more recent years, anti-vaccinationists have been known as "anti-vaxxers" or "anti-vax". Vaccine hesitancy is complex and context-specific, varying across time, place and vaccines. It can be influenced by factors such as lack of proper scientifically based knowledge and understanding about how vaccines are made or wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphtheria Vaccine
Diphtheria vaccine is a toxoid vaccine against diphtheria, an illness caused by ''Corynebacterium diphtheriae''. Its use has resulted in a more than 90% decrease in number of cases globally between 1980 and 2000. The first dose is recommended at six weeks of age with two additional doses four weeks apart, after which it is about 95% effective during childhood. Three further doses are recommended during childhood. It is unclear if further doses later in life are needed. The diphtheria vaccine is very safe. Significant side effects are rare. Pain may occur at the injection site. A bump may form at the site of injection that lasts a few weeks. The vaccine is safe in both pregnancy and among those who have a poor immune function. The diphtheria vaccine is delivered in several combinations. Some combinations (Td and DT vaccines) include tetanus vaccine, others (known as DPT vaccine or DTaP vaccine depending on the pertussis antigen used) comes with the tetanus and pertussis v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Testing
Animal testing, also known as animal experimentation, animal research, and ''in vivo'' testing, is the use of non-human animals in experiments that seek to control the variables that affect the behavior or biological system under study. This approach can be contrasted with field studies in which animals are observed in their natural environments or habitats. Experimental research with animals is usually conducted in universities, medical schools, pharmaceutical companies, defense establishments, and commercial facilities that provide animal-testing services to the industry. The focus of animal testing varies on a continuum from pure research, focusing on developing fundamental knowledge of an organism, to applied research, which may focus on answering some questions of great practical importance, such as finding a cure for a disease. Examples of applied research include testing disease treatments, breeding, defense research, and toxicology, including cosmetics testing. In edu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microbiologist
A microbiologist (from Ancient Greek, Greek ) is a scientist who studies microscopic life forms and processes. This includes study of the growth, interactions and characteristics of Microorganism, microscopic organisms such as bacteria, algae, fungi, and some types of parasites and their vectors. Most microbiologists work in offices and/or research facilities, both in private biotechnology companies and in academia. Most microbiologists specialize in a given topic within microbiology such as bacteriology, parasitology, virology, or immunology. Duties Microbiologists generally work in some way to increase scientific knowledge or to utilise that knowledge in a way that improves outcomes in medicine or some industry. For many microbiologists, this work includes planning and conducting experimental research projects in some kind of laboratory setting. Others may have a more administrative role, supervising scientists and evaluating their results. Microbiologists working in the medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precipitin
A precipitin is an antibody which can precipitate out of a solution upon antigen binding. Precipitin reaction The precipitin reaction provided the first quantitative assay for antibody. The precipitin reaction is based upon the interaction of antigen with antibody leading to the production of antigen-antibody complexes. To produce a precipitin reaction, varying amounts of soluble antigen are added to a fixed amount of serum containing antibody. As the amount of antigen added: * In the zone of antibody excess, each molecule of antigen is bound extensively by antibody and crosslinked to other molecules of antigen. The average size of antibody-antigen complex is small; cross-linking between antigen molecules by antibody is rare. * In the zone of equivalence, the formation of precipitin complexes is optimal. Extensive lattices of antigen and antibody are formed by cross-linking. * At high concentrations of antigen, the average size of antibody-antigen complexes is once again small be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Body Temperature
Normal human body-temperature (normothermia, euthermia) is the typical temperature range found in humans. The normal human body temperature range is typically stated as . Human body temperature varies. It depends on sex, age, time of day, exertion level, health status (such as illness and menstruation), what part of the body the measurement is taken at, state of consciousness (waking, sleeping, sedated), and emotions. Body temperature is kept in the normal range by thermoregulation, in which adjustment of temperature is triggered by the central nervous system. Methods of measurement Taking a person's temperature is an initial part of a full clinical examination. There are various types of medical thermometers, as well as sites used for measurement, including: * In the rectum (rectal temperature) * In the mouth (oral temperature) * Under the arm (axillary temperature) * In the ear (tympanic temperature) * On the skin of the forehead over the temporal artery * Using heat flux ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agar
Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from ogonori (''Gracilaria'') and "tengusa" (''Gelidiaceae''). As found in nature, agar is a mixture of two components, the linear polysaccharide agarose and a heterogeneous mixture of smaller molecules called agaropectin. It forms the supporting structure in the cell walls of certain species of algae and is released on boiling. These algae are known as agarophytes, belonging to the Rhodophyta (red algae) phylum. The processing of food-grade agar removes the agaropectin, and the commercial product is essentially pure agarose. Agar has been used as an ingredient in desserts throughout Asia and also as a solid substrate to contain culture media for microbiological work. Agar can be used as a laxative; an appetite suppressant; a vegan substitute for gelatin; a thickener for soups; in fruit preserves, ice cream, and other desser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virulence
Virulence is a pathogen's or microorganism's ability to cause damage to a host. In most, especially in animal systems, virulence refers to the degree of damage caused by a microbe to its host. The pathogenicity of an organism—its ability to cause disease—is determined by its virulence factors. In the specific context of gene for gene systems, often in plants, virulence refers to a pathogen's ability to infect a resistant host. The noun ''virulence'' derives from the adjective ''virulent'', meaning disease severity. The word ''virulent'' derives from the Latin word ''virulentus'', meaning "a poisoned wound" or "full of poison." From an ecological standpoint, virulence is the loss of fitness induced by a parasite upon its host. Virulence can be understood in terms of proximate causes—those specific traits of the pathogen that help make the host ill—and ultimate causes—the evolutionary pressures that lead to virulent traits occurring in a pathogen strain. Virulent ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agar Plate
An agar plate is a Petri dish that contains a growth medium solidified with agar, used to culture microorganisms. Sometimes selective compounds are added to influence growth, such as antibiotics. Individual microorganisms placed on the plate will grow into individual colonies, each a clone genetically identical to the individual ancestor organism (except for the low, unavoidable rate of mutation). Thus, the plate can be used either to estimate the concentration of organisms in a liquid culture or a suitable dilution of that culture using a colony counter, or to generate genetically pure cultures from a mixed culture of genetically different organisms. Several methods are available to plate out cells. One technique is known as "streaking". In this technique, a drop of the culture on the end of a thin, sterile loop of wire, sometimes known as an inoculator, is streaked across the surface of the agar leaving organisms behind, a higher number at the beginning of the streak and a l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphtheria Antitoxin
Diphtheria antitoxin (DAT) is a medication made up of antibodies used in the treatment of diphtheria. It is no longer recommended for prevention of diphtheria. It is given by injection into a vein or muscle. Side effects are common. They include serum sickness and allergic reactions including anaphylaxis. Diphtheria antitoxin is made from the blood plasma of horses that have been immunized against diphtheria toxin. It works by neutralizing the toxins produced by '' Corynebacterium diphtheriae''. Diphtheria antitoxin was developed and came into medical use in the late 1800s. It is on the World Health Organization's List of Essential Medicines. In the United States it can be obtained from the Center for Disease Control. It is not available in many countries including many in Europe as of 2008. Chemistry It is a solution of concentrated proteins, chiefly globulins, containing antibodies obtained from the blood of horses that have been immunized against diphtheria toxin. Refere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
