Use of bioelectrical impedance to assess body composition changes at high altitude.

This study determined the feasibility of using bioelectrical impedance analysis (BIA) to assess body composition alterations associated with body weight (BW) loss at high altitude. The BIA method was also evaluated relative to anthropometric assessments. Height, BW, BIA, skinfold (SF, 6 sites), and circumference (CIR, 5 sites) measurements were obtained from 16 males (23-35 yr) before, during, and after 16 days of residence at 3,700-4,300 m. Hydrostatic weighings (HW) were performed pre- and postaltitude. Results of 13 previously derived prediction equations using various combinations of height, BW, age, BIA, SF, or CIR measurements as independent variables to predict fat-free mass (FFM), fat mass (FM), and percent body fat (%Fat) were compared with HW. Mean BW decreased from 84.74 to 78.84 kg (P less than 0.01). As determined by HW, FFM decreased by 2.44 kg (P less than 0.01), FM by 3.46 kg (P less than 0.01), and %Fat by 3.02% (P less than 0.01). The BIA and SF methods overestimated the loss in FFM and underestimated the losses in FM and %Fat (P less than 0.01). Only the equations utilizing the CIR measurements did not differ from HW values for changes in FFM, FM, and %Fat. It was concluded that the BIA and SF methods were not acceptable for assessing body composition changes at altitude.     

Precursors in the biosynthesis of vasopressin and oxytocin in the rat. Characteristics of all the components in high-performance liquid chromatography.

A reverse-phase high performance liquid-chromatography (h.p.l.c.) protocol has been developed, whereby all the major known posterior-pituitary components that are derived from the processing of pro-oxytocin and pro-vasopressin can be separated one from another. Thus, in a single chromatographic step, it has been possible to separate vasopressin (VP), oxytocin (OT), oxytocin-neurophysin (rOT-Np), vasopressin-neurophysin (rVP-Np) and vasopressin-glycopeptide (rVP-GP) from acid extracts of the neurointermediate lobes of rat pituitary glands. All these peptides except rVP-GP were labelled in the neural lobe by 24h after a hypothalamic injection of [35S]cysteine, whereas all except VP were labelled by 24h after a similar injection of [3H]leucine. Three major labelled proteins were isolated from 20 min [35S]cysteine-injected rats when extracts of the supraoptic nucleus were subjected to Sephadex G-75 chromatography, h.p.l.c. and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Immunoprecipitation with antisera raised against rat neurophysins, VP and OT revealed 21000- and 19000-mol.wt. common precursors to VP and rVP-Np and a 15000-mol.wt. common precursor to OT and rOT-Np. Some immunoreactive rVP-Np could occasionally be detected in the Vo of Sephadex G-75 chromatograms of Wistar rat supraoptic-nucleus extracts, but no evidence of [35S]neurophysin in this fraction was obtained from h.p.l.c. fingerprinting of its S-carboxymethylated tryptic digests. Radioimmunoassay for rVP-Np and rOT-Np revealed that about 70-80% of the total recovered immunoreactive neurophysin (IR-Np) in the supraoptic nucleus eluted from Sephadex G-75 and h.p.l.c. in the positions of rVP-Np and rOT-Np. Evidence is presented for an approx. 20000-mol.wt. rOT-Np in both Wistar and Brattleboro rats and for an approx. 20000-mol.wt. component in the Brattleboro rat that is recognized by vasopressin-neurophysin antisera.     

A specific method of high sensitivity for the determination of adenosine in the incubation medium of fat tissue

A suitable method for the measurement of adenosine in the incubation medium of fat tissue (200-500 mg) has been developed. The method is based on the specificity of the adenosine deaminase reaction and on the high sensitivity of a fluorescent method for adenine derivatives. The decrease of fluorescence in a sample after treatment with this enzyme is used for measuring adenosine in the range of 50-500 pmoles/tube. This method is highly specific and is not affected by other adenine derivatives present in the sample. Instead of acetic acid, perchloric acid was used in the fluorescent reaction, thus increasing the amount of adenosine dependent fluorescence. With this modification of the original fluorescent method, perchloric acid extracts can be used without further processing after deproteinization of the samples. Using this method, we could measure the adenosine release of fat pads of Wistar rats incubated in Krebs-Ringer-albumin buffer without concentration or purification procedures.     

Three triterpenes and other terpenoids from Catha cassinoides

The investigation of stems and leaves of Catha cassinoides afforded, in addition to sitosterol, β-amyrin, ursolic acid, lup-20(29)-en-3β,30-diol and friedelin, three new pentacyclic triterpenes: 30-hydroxyfriedelan-3-one, 29-hydroxyfriedelan-3-one and 3-oxo-friedelan-29-oic acid. The structures ofthese were determined by spectral studies and correlations, and were confirmed by X-ray analysis of 29-hydroxyfriedelan-3-one acetate.     

Cellulolytic enzymes for the hydrolysis of leached beet cosette

Summary Cellulolytic fungi were isolated from rotting leaves and tested for extra-cellular cellulase activities (CMCase, avicelase, cellobiase and xylanase). The effect of the proportion of the enzyme activities on the rate of degradation of leached beet cosette was observed using a range of supernatant fluids in appropriate combinations. At low cosette concentrations (1.5–3.0 g/l), avicelase and cellobiase were the rate limiting enzymes; avicelase in the initial stages of reaction and cellobiase after 6–8 hours, when cellobiose inhibition becomes important. A ratio of celiobiase to avicelase of approx 2.0 was established as appropriate. At higher substrate concentrations (10 g/l, 40 g/l) the best cellobiase to avicelase ratio was maintained and up to 40% hydrolysis was obtained in the 10 g/l incubation with 10 Uav/l and 20 Ucellob/l. At 100 g/l cosette concentration, substrate inhibition was observed.     

Reactions between diglycolaldehyde dithioacetals and some nucleophiles

The homogeneous, neutral polysaccharide isolated from the crude polysaccharide of the fruit pulp from bael (Aegle marmelos) contains arabinose, galactose, and glucose in the molar ratios of 2:3:14. The linkages among the different monosaccharide residues were established through methylation analysis and Smith-degradation studies of the polysaccharide. The anomeric configurations of the different glycosyl groups were determined by study of the chromium trioxide oxidation of the acetylated polysaccharide. Results of these experiments have been discussed in order to assess the structure of the neutral polysaccharide.     

Effect of experimental diabetes on glycolytic intermediates and regulation of phosphofructokinase in rat lens

The pattern of glycolytic intermediates in the lens of alloxan-diabetic rats was indicative of regulation at phosphofructokinase. The changes in metabolites influencing phosphofructokinase activity in the diabetic, relative to the normal, rat lens were: glucose 6-phosphate, 182%; fructose 6-phosphate, 107%; fructose diphosphate, 57%. There was also a marked decrease in phosphoenolpyruvate, pyruvate, lactate and ATP but no significant change in other triose phosphates or cyclic AMP. The resuts are considered in relation to the early changes in [Ca²⁺] known to occur in lens in diabetes and to the coordinating effect of fructose diphosphate on flux through the glycolytic route.