Errors in the use of isokinetic dynamometers.

The use of constant velocity dynamometers in functional testing and in exercise and therapy programs has been increasing in the past few years. For movements in the horizontal plane there are no gravitational errors. However, in vertical movements the limbs are not only working against the dynamometer but also are either aided or opposed by gravity.

Alternatives to total parenteral nutrition in the critically ill patient.

Alternatives to total parenteral nutrition (TPN) can play an invaluable role in the support of the critically ill patient. However, the efficacy of this depends on: (1) early nutritional assessment; (2) sequential nutritional assessment as dictated by the clinical condition of the patient; (3) careful estimation of requirements based on calculated energy expenditure and use of the "stress-index"; (4) early use of enteral feedings in combination with peripheral and central intravenous routes, especially with the use of "feeding modules" to provide patient's specific concentrated diet; (5) use of intravenous fat as an isotonic supplement to dextrose in the presence of carbohydrate intolerance; (6) avoid overfeeding as rigorously as underfeeding; (7) continued clinical trials to determine optimal nutritional/metabolic support of the critically ill.

Threshold effects on the concanavalin A-mediated agglutination of modified erythrocytes.

Bovine erythrocytes, which are not concanavalin A (ConA)-agglutinable, can be rendered so by attaching alpha-D-mannose residues to their outer membrane. The sugars are incorporated by mildly oxidizing the cells with periodate followed by coupling the liberated aldehyde groups with an alpha-thiomannosyl containing hydrazide (I). The rate and extent of ConA-mediated aggregation of the modified cells are not linearly dependent on the amount of sugar incorporated.

Synthetic glycolipids and the lectin-mediated aggregation of liposomes.

Synthetic mannose-containing glycolipids utilizing the cholesterol nucleus as a lipid anchor, and either the 6-aminohexyl- or the 6-(6-aminohexanamido)hexyl-1-thio-alpha-D-mannopyranosides as the carbohydrate ligands, have been synthesized and incorporated into small unilamellar liposomes. Incorporation of these cholesterol-mannoside derivatives at concentrations up to 14 mol% apparently does not affect the physical characteristics of the liposomes. Addition of concanavalin A to a suspension of liposomes containing the long chain cholesterol-mannose derivative causes an increase in light-scattering at 360 nm.

Adenosine 5'-O-([gamma-18O]gamma-thio)triphosphate chiral at the gamma-phosphorus: stereochemical consequences of reactions catalyzed by pyruvate kinase, glycerol kinase, and hexokinase.

The 2-[18O]phosphorothioate of D-glycerate, chiral at phosphorus, was prepared. The chiral phosphoryl group was transferred enzymically to ADP [by using enolase and pyruvate kinase (ATP:pyruvate 2-O-phosphotransferase; EC 2.7.

Transglutaminase activity in normal and transformed cells.

Transglutaminase activity was determined in normal and transformed paired cell systems. Reduced enzyme activity was found in virus-transformed human and hamster cells and in chemically transformed mouse cells relative to normal counterparts. Most of the enzyme activity was localized in the particulate fraction sedimenting at 105,000 X g.

Differential transglutaminase distribution in normal rat liver and rat hepatoma.

Distribution of transglutaminase activity was determined in normal rat liver, a 3'-methyl-4-dimethylaminoazobenzene-induced primary hepatoma, and the Novikoff hepatoma. Over 90% of the total enzyme activity was found in the 105,000 X g supernatant of normal liver, whereas only 30% was found in this fraction of the hepatomas, the remainder being found in the particulate fraction. The is distribution pattern did not correlate with protein distribution nor did it change during cellular proliferation, since regenerating liver and embryonic tissue had the same pattern as normal liver.

Amino acid and hexose transport of normal and simian virus 40-transformed human cells.

Studies on amino acid and hexose transport were performed on human WI-38 cells and WI-38 SV40-transformed cells (VA13A and VA13-2RA). Depending upon cell line or conditions, either no difference or a relative decrease in initial uptake by transformed cells was found. Under similar growth conditions, transformed hamster cells (PyBHK-21/C13) had increased uptake, compared with the normal hamster cells (BHK-21/C13).

The interaction of the phosphonate analogue of 3-phospho-D-glycerate with phosphoglycerate kinase.

The methylene analogue of 3-phospho-d-glycerate, 2-hydroxy-4-phosphono-dl-butyric acid, is a substrate for phosphoglycerate kinase. The pK(a) values for the final dissociation of the natural substrate and its methylene isostere are 6.20 and 7.