| cross-sectional method | <epidemiology> The study of the life span involving comparison of groups of individuals at different age levels. Compare: longitudinal method. (05 Mar 2000) |
|---|---|
| Hamilton-Stewart method | Formula to calculate cardiac output after intravenous indicator dye injection; blood flow in liters per minute is given by dividing the amount of injectant in milligrams by the product of the average dye concentration in the initial curve of the dye concentration sampled at a given point in the circulation and multiplied by the dose of dye (in milligrams) to write the curve from appearance to disappearance (in the absence of any recirculation). Synonym: Hamilton-Stewart formula, Stewart-Hamilton method. (05 Mar 2000) |
| Hammerschlag's method | A hydrometric method of determining the specific gravity of the blood by allowing a drop of blood to fall into each of a series of tubes containing mixtures of chloroform and benzene of known graded specific gravities; the specific gravity of that mixture in which the drop remains exactly suspended, neither rising nor falling, corresponds to the specific gravity of the blood sample. (05 Mar 2000) |
| Sanger Coulson method | The most popular method of DNA sequence determination (c.f. Maxam Gilbert sequencing). Starting with single stranded template DNA, a short complementary primer is annealed and extended by a DNA polymerase. The reaction is split into 4 tubes (called A, C, G or T) each containing a low concentration of the indicated dideoxy nucleotide, in addition to the normal deoxynucleotides. Dideoxynucleotides, once incorporated, block further chain extension and so each tube accumulates a mixture of chains of lengths determined by the template sequence. The 4 reactions are denatured and run out on an acrylamide sequencing gel in neighbouring lanes and the sequence read up the gel according to the order of the bands. (18 Nov 1997) |
| Sanger method | The method for the sequencing of DNA employing an enzyme that can polymerase DNA and labelled nucleotides. (05 Mar 2000) |
| Scarpa's method | Cure of aneurysm by ligation of the artery at some distance above the sac. (05 Mar 2000) |
| Schafer's method | An obsolete method of resuscitation in cases of drowning or asphyxia; the patient is laid face downward and natural breathing is imitated by gentle intermittent pressure over the lower part of the thorax at the rate of about 15 times a minute. (05 Mar 2000) |
| Schede's method | Filling of the defect in bone, after removal of a sequestrum or scraping away carious material, by allowing the cavity to fill with blood which may become organised (Schede's clot). (05 Mar 2000) |
| Schick method | A test for susceptibility to Corynebacterium diphtheriae toxin: 0.1 ml of Schick test toxin is injected into the skin of one forearm (test site) and the same quantity of the same, but heat-inactivated, material into the skin of the other forearm (control site); individuals with toxin-neutralizing antibodies either will have no reaction at either injection site (negative test) or may have a pseudoreaction due to antibodies for substances (antigens) in the test materials other than diphtheria toxin; individuals lacking toxin-neutralizing antibodies may have a positive reaction, which consists of an area of redness appearing 24 to 36 hours at the test site only and persisting for 4 to 5 days. Synonym: Schick method. (05 Mar 2000) |
| schlieren method | <radiobiology> An optical technique that detects density gradients occuring in a fluid flow. In its simplest form, light from a slit is collimated by a lens and focused onto a knife edge by a second lens, the flow pattern is placed between the two lenses, and the resulting diffraction pattern is observed on a screen or photographic film placed behind the knife edge. (09 Oct 1997) |
| Schmidt-Thannhauser method | A method for fractionation of nucleic acid, based upon the fact that RNA but not DNA is hydrolyzed to nucleotides by alkali; RNA can be hydrolyzed in about 2 hours in 0.75 n NaOH, but 18 hours and 0.3 n NaOH usually are used. (05 Mar 2000) |
| Schweninger's method | A method suggested to reduce obesity by restricting intake of fluid. (05 Mar 2000) |
| scientific method | The universally-accepted, organised approach to the study of science, which consists of the following steps: 1. Observation - collecting data. 2. Hypothesis - forming a preliminary possible explanation of the data. 3. Testing - test the hypothesis by collecting more data. 4. Results - interpreting the results of the test and deciding if the hypothesis should be rejected. The hypothesis is rejected if the results contradict it, showing that it is wrong. 5. Conclusion - stating a conclusion that can be evaluated independently by others. (09 Oct 1997) |
| hexokinase method | The most specific method for measuring glucose in serum or plasma, wherein hexokinase plus ATP transforms glucose to glucose-6-phosphate plus ADP; glucose-6-phosphate is then reacted with NADP and glucose-6-phosphate dehydrogenase to form NADP which is measured spectrophotometrically. (05 Mar 2000) |
| Hilton's method | Division of the nerves supplying a part, for the relief of pain in ulcers. (05 Mar 2000) |