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Term Definition
G Protein Coupled Receptor (GPCR) A large family of related cell surface proteins that associate with internal signaling molecules (G proteins). GPCRs are often pursued as drug targets, for example the beta adrenergic receptor is a GPCR target for beta blockers.
GABA Gamma-aminobutyric acid. It is the most important inhibitory neurotransmitter in the central nervous system (CNS). It and its receptors facilitate chloride entry into the interior of nerve cells thus inhibiting specific neurotransmitter release in the presence of positive voltage polarization pulses. Such inhibition is extremely common as GABA receptors can be found at 60 - 80% of CNS neurons. Subtypes of GABA receptors can be activated by specific mushroom toxins (GABA-A) as well as the antispasmodic amino acid drug baclofen (GABA-B). These drugs directly mimic the action of GABA at the receptor. Drugs that allosterically facilitate GABA receptors at several distinct sites can be used as sedatives and anxiolytics. These drugs bend the receptor open to indirectly facilitate GABA binding. Prime examples are benzodiazapines and alcohol.
Gadolinium The element, Gd , atomic number 64 and atomic weight 157.25 (3) g, that is used as an intravenous contrast agent, or “dye,” that, when imaged with magnetic resonance imaging (MRI), improves the definition of certain, especially pathologic, structures.
Gallium A rare metal whose principal form has an atomic weight of 69. Isotopes such as gallium 68 can be produced by cyclotrons and emits gamma rays. Citrated gallium 68 is used as a radiotracer to identify sites of inflammation and tumor tissue within the body.
Gangrene Death of tissue due to the loss of its blood supply often allowing bacteria to invade it and accelerate its decay. Gas gangrene is an acute emergency involving invasion of a deep penetrating wound by anaerobic bacteria (bacteria that survive with little or no oxygen) that generate gas and pus. Dry gangrene is a chronic consequence of the death of tissue due to vascular (blood vessel) insufficiency. It is unaccompanied by bacterial invasion, and over time tissue simply dries up and shrivels.
Gastrointestinal Related to the stomach, intestines, mouth, and other organs involved in food digestion.
Gaucher disease A single gene disorder in which glucocerebroside accumulates in the lysosomes of various cells. Often leads to enlarged spleen, anemia, bone fractures, and can lead to death from bone marrow failure.
Gene The functional and physical unit of heredity passed from parent to offspring. Genes are segments of DNA and most genes contain the information for making a specific protein.
Gene Chip Affymetrix brand name for its DNA microarrays.
Gene Delivery Transport of therapeutic genes to patients.
Gene Discovery The identification of genes.
Gene Expression A gene is expressed when its sequence is transcribed into RNA. Most frequently, that RNA is an mRNA which is later translated into protein. Although all genes of an organism are present in each cell, not all genes are active in each. Some genes are activated only in certain tissues; others are activated only in response to certain environmental stressors. Studies of gene expression patterns are a source of information about gene function.
Gene Expression Data Data generated by microarrays which measure the amount of RNA being made from thousands of individual genes in a particular sample.
Gene Splicing The technique of manipulating DNA sequences in the laboratory. Scientists can synthesize and manipulate DNA to create new genes, usually from splicing different parts of natural genes together in new ways. Many biotechnology processes involve gene splicing techniques, for example the development of recombinant proteins and humanized monoclonal antibodies.
Gene Therapy Treatment of a disease or condition by adding to or replacing a patient’s DNA.
Genealogical Databases Databases which contain family histories, often including medical histories and pedigree analyses. These databases can be used in combination with patient DNA samples to identify genes whose mutations cause genetic predisposition to disease. "
Generic Drugs Pharmaceuticals which are bioequivalent copies of marketed brand-named drugs. Generic drugs typically are introduced by companies which specialize in generic drugs after the patents protecting brand-name drugs expire. Generic drugs are usually significantly less expensive than their branded equivalents.
Genetic Counseling An educational counseling process for individuals and families who have a genetic disease or who are at risk for such a disease. Genetic counseling provides patients with information about their condition and its risks, helping them make informed decisions.
Genetic Counselor A master’s degree-level (at least) health care provider whose profession it is to provide genetic counseling.
Genetic Database A database containing DNA sequence information derived from any of several sources.
Genetic Engineering Using recombinant DNA technology.
Genetic Marker A polymorphic sequence of DNA with an identifiable physical location on a chromosome and whose inheritance can be followed. A marker can be a gene, or it can be some section of DNA with no known function. Because DNA segments that lie near each other on a chromosome tend to be inherited together, markers are often used as indirect ways of tracking the inheritance pattern of a gene that has not yet been identified, but whose approximate location is known. Markers can also be exploited for mapping.
Genetic Screening Testing a population group to identify a subset of individuals at high risk for having or transmitting a specific genetic disorder.
Genetic Variation Differences in genetic composition at any given level: total genome, sub-genomic, chromosomal, genic/allelic, or nucleotide. Most often, the biotechnology industry uses differences at the level of the DNA sequence, specifically at the level of the allele or single nucleotide. Variation at these levels gives rise to polymorphisms, DNA spellings along analogous stretches (loci) of DNA, the differences of which may be associated with disease, freedom from disease, drug response, lack of drug response, adverse effects, and other human traits. The origins of genetic variation are direct consequences of sexual reproduction: (1) mutations (altering DNA by changing base pairs), (2) segregation (random distribution of one of each chromosome pair into sperm or egg), and (3) recombination (an event in sperm and egg cell development [meiosis] during which specific DNA is “shuffled”). These processes make each sexually-produced individual unique and provide the basis of genetic variation.
Genetics The science of biological inheritance.
Genome All the DNA contained in an organism or a cell, which includes both the chromosomes within the nucleus and the DNA in mitochondria.
Genomics Study of the genome, the complete complement of DNA in an organism.
Germ-Line Mutation A change in the DNA of the sperm or egg that therefore has a chance to be passed on to offspring.
Glaucoma Eye condition in which fluid pressure inside the eyes is increased due to impaired fluid drainage from the eye. Untreated, the optic nerve and other parts of the eye are at risk of impairment and loss of vision or even blindness can ensue. Common varieties include open-angle (the common adult-onset type of glaucoma) and acute angle-closure (less common, but type that can rapidly impair vision). Treatment may include medication, surgery, or laser surgery.
Glial Cell A type of support cell for neurons found in the brain.
Glial Derived Neurotrophic Factor (GDNF) A member of the transforming growth factor-beta protein superfamily, it is a potent neurotrophic factor that enhances survival of midbrain neurons that manufacture dopamine. Since its write-up in Science in 1993, GDNF has been widely explored in preclinical investigation relating to the management of Parkinson disease. In Parkinson disease, dopamine-producing neurons fail to provide dopamine in adequate amounts needed to preserve motor accuracy.
Glial Growth Factor A small hormone-like protein which induces growth of glial cells, a type of support cell for neurons found in the brain.
Glioma A general category of brain cancers that includes astrocytomas, oligodendrogliomas, and ependymomas.
Glucagon-Like Peptide 1 (GLP-1) Secreted from the L-cells of the gastrointestinal tract, GLP-1 has potent effects on glucose-dependent insulin secretion, insulin gene expression, and pancreatic islet cell formation. GLP-1 augments insulin secretion; decelerates gastric emptying; promotes satiety; suppresses glucagon secretion from pancreatic alpha-cells; facilitates insulin sensitivity in peripheral tissues; upregulates expression of pancreatic beta-cell genes GLUT2, glucokinase, insulin, and PDX-1; and promotes pancreatic beta-cell integrity. Recombinant versions of the peptide have pharmacologic properties that may make them suitable for energy-related metabolic disorders as well as disorders affecting a variety of organ systems.
Glucose A simple sugar that is a main energy source for metabolism. Blood glucose levels are tightly regulated by the hormones insulin and glucagon.
Glucose Tolerance The ability of an organism to properly uptake, utilize, and metabolise glucose. At the cellular level, the hormones insulin and glucagon are the principle mediators of these related processes. At the clinical level, impaired glucose tolerance is manifest by and is defined by high blood glucose levels after a standard test. At lower levels, impaired glucose tolerance is a precursor to diabetes mellitus. At higher levels, it is a characteristic of diabetes mellitus.
Glutamate A salt or ester of glutamic acid (the amino acid HOOC-CH2-CH2-CH(NH2)-COOH), it is an excitatory neurotransmitter. Overactivity in Alzheimer disease is the basis for therapies that modify its activity.
Glutathione S-Transferase Any of several related DNA protective enzymes of particular importance in specific biochemical detoxification pathways including those related to free radical scavenging systems. Without the activity of glutathione S-transferase, toxic products can promote mutagenesis and tumor formation. As variations of the protein can exist for cancerous, precancerous, or unaffected cells, modulating its effects in different systems can have varying results.
Glycosaminoglycan Any of a group of polysaccharides containing amino sugars (e.g. glucosamine), they include hyaluronic acid, keratan sulfate, chondroitin sulfate, dermatan sulfate, and heparin sulfate. Their three-dimensional structures enable them to trap water, which forms a gel giving glycosaminoglycans (GAGs) elastic properties. These elastic properties are most notable in the GAG-containing buffering tissues of the body such as cartilage. GAGs are also known as mucopolysaccharides (MPSs), and their accumulation in the lysosomes of the cells of various tissues is a feature of the single gene disordered inborn errors of metabolism known as mucopolysaccharidoses.
Glycosylation Relating to the state of having attached carbohydrates or the process of attaching them.
gpIIb/IIIa Receptor Short for "glycoprotein IIb/IIIa receptor complex," it is the platelet's cell surface receptor complex that interacts with the blood clotting protein, fibrinogen, in order to facilitate platelet aggregation and blood clotting/coagulation. Its hereditary absence leads to the bleeding disorder "Glanzmann thrombasthenia," and interference with its biological function, by drugs, can be used for therapeutic anticoagulation.
Grade A tumor classification scheme based upon the microscopic (histologic) appearance of tumor cells. The spectrum extends from low grade in which tumor cells resemble normal cells of the same type to the highest grade where tumor cells bear virtually no resemblance at all to their normal counterparts. Grades in between are typically numbered or lettered in ascending order of severity, and pathologists set nomenclature with regard to correlating the degree to which the cells differ from normal. "
Graft vs. Host Disease (GVHD) Condition that occurs after bone marrow or other blood cell related transplants when the donor’s immune cells manufacture antibodies against host tissues. Patients try to receive closely genetically matched bone marrow to reduce the risk of serious GVHD.
Gram Negative Bacteria that lose the crystal violet stain (thus appearing the color of the red counterstain) in J.M.C. Gram's staining method. The organisms that stain this way, gram-negative bacteria, have a cell wall composed of a thin layer of a material called peptidoglycan. Since the early 1900s Gram's staining has aided in distinguishing between different types of bacteria. A specific antibiotic has a tendency to work better for either gram-negative or gram-positive bacteria or subsets of either, rarely for both. Gram-negative bacteria include most of the bacteria normally found in the gastrointestinal tract as well as gonococci (veneral disease) and meningococci (bacterial meningitis). The organisms responsible for cholera and bubonic plague are also gram-negative bacteria.
Gram Positive Bacteria that retain the color of the crystal violet stain in in J.M.C. Gram's staining method. The organisms that stain this way, gram-positive bacteria, have a cell wall composed of a thick layer of a material called peptidoglycan. Since the early 1900s Gram's staining, has aided in distinguishing between different types of bacteria. A specific antibiotic has a tendency to work better for either gram-negative or gram-positive bacteria or subsets of either, rarely for both. Gram-positive bacteria include staphylococci ("staph"), streptococci ("strep"), and pneumococci, as well as the bacteria responsible for anthrax and diptheria.
Granulocyte Colony Stimulating Factor (GCSF) (1) A growth factor (small hormone like signaling protein) secreted by certain white blood cells which stimulates growth of other white blood cells. (2) Generic name of Amgen’s Filgrastim formulation, Neupogen, indicated in many specific circumstances in which a patient has a low white blood cell count.
Granulocyte Macrophage Colony Stimulating Factor (GM-CSF) A growth factor (small hormone like signaling protein) secreted by certain white blood cells which stimulates growth of other white blood cells.
Growth Factor Any of an array of molecules that are known to mediate cell growth, often also associated with cell differentiation, locomotion, and contractility. Many are involved in essential developmental processes, fundamental cell and tissue repair processes, and wound healing. Growth factors are peptides, similar in structure to hormones.
Growth Hormone Made in the pituitary gland, it stimulates release of a liver hormone called somatomedin which, by several mechanisms, stimulates growth. Its many roles include stimulating protein synthesis, stimulating mobilization of free fatty acids, and inhibiting glucose utilization. Also known as somatotropin and somatropin.
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