| high altitude chamber | A decompression chamber for simulating a high altitude environment, particularly its low barometric pressure. Synonym: high altitude chamber. (05 Mar 2000) |
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| high altitude pulmonary oedema | <physiology> The abnormal deposition of fluid into the lungs that occurs with exposure to lower barometric pressure and low oxygen. (12 Jan 1998) |
| high altitude sickness | A condition that results from the exposure to lower barometric pressure (lower oxygen concentration). Synonym: acute mountain sickness. (27 Sep 1997) |
| high-bred | Bred in high life; of pure blood. Source: Websters Dictionary (01 Mar 1998) |
| high-calorie diet | A diet containing upward of 4,000 calories per day. (05 Mar 2000) |
| high convex | The segment of a sphere of short radius. (05 Mar 2000) |
| high density lipoprotein | <biochemistry> These lipoproteins acts to carry cholesterol in the bloodstream. Raised high density lipoprotein levels have been correlated with a lower risk for heart disease. Less than 35 mg/dl is considered a positive risk factor for coronary artery disease, over 60 mg/dl is considered a negative risk factor (reduces your risk of heart disease). Recent studies show a low high density lipoprotein level is the strongest predictor of cardiovascular death in women. Acronym: HDL (18 Nov 1997) |
| high dose tolerance | The induction of tolerance by exposure to high doses of antigen. (05 Mar 2000) |
| high-egg-passage vaccine | Living Flury strain rabies virus at the 180th to 190th level egg passage (embryonate eggs), used for vaccination of cattle and cats, low-egg-passage (LEP) vaccine: at the 40th to 50th passage level, containing 103 to 104 mouse LD50; nonpathogenic in dogs but retains some pathogenicity for cattle and cats. (05 Mar 2000) |
| high endothelial postcapillary venules | Venule's in the lymph nodes, tonsils, and Peyer's patches that have a high-walled endothelium through which blood lymphocytes migrate into the lymphatic parenchyma. (05 Mar 2000) |
| high enema | An enema instilled high up into the colon. Synonym: enteroclysis. (05 Mar 2000) |
| high energy bond | <chemistry> Chemical bonds that release more than 25kJ/mol on hydrolysis: their importance is that the energy can be used to transfer the hydrolysed residue to another compound. The risk in using the term is that students may think the bond itself is different in some way, whereas it is the compound that matters. Hydrolysis of creatine phosphate yields 42.7kJ/mol, of phosphoenolpyruvate, 53.2, ATP to ADP, 30.5: the latter is important because it shows that energetically the hydrolysis of creatine phosphate will suffice to reconstitute ATP, hence the use of creatine phosphate in muscle. (18 Nov 1997) |
| high energy compounds | Classically, a group of phosphoric esters whose hydrolysis takes place with a standard free energy change of -5 to -15 kcal/mol (or, -20 to -63 kJ/mol) (in contrast to -1 to -4 kcal/mol or, -4 to -17 kJ/mol) for simple phosphoric esters like glucose-6-phosphate or alpha-glycerophosphates), thus being capable of driving energy-consuming reactions in living cells or reconstituted cell-free systems; adenosine 5'-triphosphate, with respect to the beta-and gamma-phosphates, is the best known and is regarded as the immediate energy source for most metabolic syntheses. The general types are acid anhydrides, phosphoric esters of enols, phosphamic acid (R-NH-PO3H2) derivatives, acyl thioesters (e.g., of coenzyme A), sulfonium compound's (R3-S+), and aminoacyl esters of ribosyl moieties. See: high energy phosphates. (05 Mar 2000) |
| high energy particle generating unit | A machine capable of providing highly energised radiation for the purposes of radiotherapy treatment. (16 Dec 1997) |
| high energy phosphate bond | See: high energy phosphates. (05 Mar 2000) |