Effect of prior ingestion of glucose or fructose on the performance of exercise of intermediate duration

The metabolic responses induced by the ingestion of a beverage containing glucose (G), fructose (F) or placebo (W) 30 min before exercise of high intensity and intermediate duration have been investigated; in these conditions the energy processes are mostly dependent on aerobic reactions. A group of 11 male recreational sportsmen ran on a treadmill, at an intensity corresponding to 82% of peak oxygen consumption, until exhaustion on three different occasions (after ingestion of a beverage containing 75 g of G, 75 g of F or W). Plasma glucose, insulin, and lactic acid concentrations were determined just prior to the ingestion of the beverages, 30 min afterwards and 10 and 30 min after completion of the exercise. The mean endurance time was 644 (SD 261) s after the ingestion of G, 611 (SD 227) s after the ingestion of F and 584 (SD 189) s after the ingestion of the W (P < 0.05 between G and W). No differences in the oxygen uptake, respiratory quotient or lactate concentrations between the three trials were observed. Both plasma glucose and insulin concentrations determined in samples obtained immediately before the onset of exercise were higher when G was ingested than when F (P < 0.05 andP < 0.05, respectively) or W (P < 0.001 and P < 0.005, respectively) were ingested. These findings would suggest that the ingestion of G prior to an effort of intermediate duration may improve physical performance.     

IR and Raman spectroscopic studies of the interaction of trehalose with hen egg white lysozyme

Infrared and Fourier transform Raman spectra are reported for dried mixtures of trehalose and lysozyme. The Raman spectra show effects on the protein amide I band and some sugar bands that are not present when the components are dried separately. Comparison of ir spectra with those published previously show significant differences. It is concluded that these arise because of differences in the extent of drying of the moisture, and that, contrary to some claims, vibrational spectroscopy does not so far show any clear evidence of specific trehalose/protein interactions and that results may be interpreted in terms of entrapment of water within the mixture. © 1994 John Wiley & Sons, Inc.     

Improvement of somatic embryogenesis inFeijoa sellowiana berg (Myrtaceae) by manipulation of culture media composition

Summary Somatic embryos could be induced from the cotyledons of zygotic embryos from immature fruits ofFeijoa sellowiana Berg (Feijoa) in the presence of a wide range of concentrations of fructose, glucose, maltose, and sucrose. Mannitol or sorbitol alone were ineffective. The highest frequencies of induction (99%) and the greatest number of somatic embryos per explant (134) were obtained with 0.4M fructose and 0.3M sucrose, respectively. This sucrose concentration also showed greater induction capacity than equimolar combinations of its monosaccharide constituents combined. Somatic embryo development was arrested at the globular stage at concentrations higher than 0.5M of all the sugars tested. When transferred to solid germination medium containing 2.0 mg/liter (5.77μM) gibberellic acid, 0.5 mg/liter (2.32μM) kinetin, and 0.029M sucrose, somatic embryos formed under 0.3 or 0.4M sucrose had better germination capacity than those induced under lower (0.1 and 0.2M) concentrations, as assessed by the frequency of explants presenting germinated embryos and by the number of plants obtained from those explants. On liquid media of similar composition somatic embryos did not germinate. Our data suggest that high (0.3 to 0.4M) carbohydrate levels improve somatic embryogenesis by acting both as carbon source and as osmotic regulator.     

Circannual Variations in Blood Cholesterol Levels

The seasonality of blood cholesterol is still not well established. Some have described a seasonal pattern with highest levels during autumn and lowest in summer, whereas others have reported no change. A number of studies showed circannual variations with maximum levels in winter and minimum in summer. The aim of this study was to examine the circannual variation of cholesterol in a large cohort in Israel. In the Israeli CORDIS study, employees of 21 factories were screened for cardiovascular disease risk factors during 1985-7. As part of the information gathered, serum cholesterol and blood counts were available for 3,726 men and 1,514 women. Serum cholesterol levels fit a circannual rhythm assessed by the cosinor analysis. Highest levels of serum cholesterol were found in spring and lowest in summer. We conclude that there is a circannual change of serum cholesterol, which could be partially associated with changes in environmental temperature. The circannual variation in serum cholesterol was considerable and should be taken into account when carrying out clinical evaluation of patients.     

The larval development of lateral musculature in gilthead sea bream Sparus aurata and sea bass Dicentrarchus labrax

Fibre-type differentiation of the lateral musculature has been studied in Sparus aurata (L.) and Dicentrarchus labrax (L.) during larval development. Histochemical and ultrastructural techniques show two presumptive muscle layers and two germinative zones of presumptive myoblasts. At hatching, myotomal muscle consists of a monolayer of thin undifferentiated cells near the skin (first germinative zone) overlying another mono-layer of small diameter fibres extending hypaxially and epaxially away from the transverse septum. Below this, there is a much thicker, deep layer of fibres, generally large in diameter and polygonal in shape. The presumptive myoblasts are located between these two layers of fibres in the second germinative zone. Initially, the superficial and deep muscle fibres show high and low myosin ATPase activity, respectively. Both layers grow by generating new fibres from the two mentioned germinative zones. At the end of larval life, the superficial layer changes its histochemical profile from high to low myosin ATPase activity and, at the same time, intermediate or pink muscle fibres can be observed by oxidative activity (the NADH-TR reaction). Morphometric analysis shows a significant increase in mean fibre diameter during successive ages, as shown by the Student's t-test (hypertrophic growth). Skewness and kurtosis values of fibre diameters point to the generation of a new fibre population from the germinative zones (hyperplastic growth).     

Sensitivity of European microtines to injected CdCl2.

Basic histologic and metabolic indices of damage to the testes by CdCl2 were observed in six species of rodents: Lagurus lagurus, Pitymys subterraneus, Microtus oeconomus, M. agrestis, Clethrionomys glareolus (and Mus musculus for comparison). All species showed discoloration of the subcapsular tissues and damage to the testicular parenchyma. Testes of all species receiving CdCl2 utilized from 43% to 76% less oxygen than did those from untreated individuals. Cadmium treatment preceded few significant temperature shifts. The voles observed experienced differential sensitivity to CdCl2 and should be quite suitable for further studies of the mechanism of action of CdCl2 as a testicular poison.