Protein-containing nutrient supplementation following strength training enhances the effect on muscle mass, strength, and bone formation in postmenopausal women.

We evaluated the response of various muscle and bone adaptation parameters with 24 wk of strength training in healthy, early postmenopausal women when a nutrient supplement (protein, carbohydrate, calcium, and vitamin D) or a placebo supplement (a minimum of energy) was ingested immediately following each training session. At inclusion, each woman was randomly and double-blindedly assigned to a nutrient group or a placebo (control) group. Muscle hypertrophy was evaluated from biopsies, MRI, and dual-energy X-ray absorptiometry (DEXA) scans, and muscle strength was determined in a dynamometer. Bone mineral density (BMD) was measured using DEXA scans, and bone turnover was determined from serum osteocalcin and collagen type I cross-linked carboxyl terminal peptide. The nutrient group improved concentric and isokinetic (60 degrees /s) muscle strength from 6 to 24 wk by 9 +/- 3% (P < 0.01), whereas controls showed no change (1 +/- 2%, P > 0.05). Only the nutrient group improved lean body mass (P < 0.05) over the 24 wk. BMD responded similarly at the lumbar spine but changed differently in the two groups at the femoral neck (P < 0.05) [control: 0.943 +/- 0.028 to 0.930 +/- 0.024 g/mm(3) (-1.0 +/- 1.4%); nutrient group: 0.953 +/- 0.051 to 0.978 +/- 0.043 g/mm(3) (3.8 +/- 3.4%)] when adjusted for age, body mass index, and BMD at inclusion. Bone formation displayed an interaction (P < 0.05), mainly caused by increased osteocalcin at 24 wk in the nutrient group. In conclusion, we report that nutrient supplementation results in superior improvements in muscle mass, muscle strength, femoral neck BMD, and bone formation during 24 wk of strength training. The observed differences following such a short intervention emphasize the significance of postexercise nutrient supply on musculoskeletal maintenance.     

Hormone-sensitive lipase is necessary for normal mobilization of lipids during submaximal exercise

For the working muscle there are a number of fuels available for oxidative metabolism, including glycogen, glucose, and nonesterified fatty acids. Nonesterified fatty acids originate from lipolysis in white adipose tissue, hydrolysis of VLDL triglycerides, or hydrolysis of intramyocellular triglyceride stores. A key enzyme in the mobilization of fatty acids from intracellular lipid stores is hormone-sensitive lipase (HSL). The aim of the present study was to investigate the metabolic response of HSL-null mice challenged with exercise or fasting and to examine whether other lipases are able to fully compensate for the lack of HSL. The results showed that HSL-null mice have reduced capacity to perform aerobic exercise. The liver glycogen stores were more rapidly depleted in HSL-null mice during treadmill exercise, and HSL-null mice had reduced plasma concentrations of both glycerol and nonesterified fatty acids after exercise and fasting, respectively. The data support the hypothesis that in the absence of HSL, mice are not able to respond to an exercise challenge with increased mobilization of the lipid stores. Consequently, the impact of the lipid-sparing effect on liver glycogen is reduced in the HSL-null mice, resulting in faster depletion of this energy source, contributing to the decreased endurance during submaximal exercise.     

alpha Isoforms of soluble and membrane-linked folate-binding protein in human blood

The high-affinity FBP/FR (folate-binding protein/folate receptor) is expressed in three isoforms. FRalpha and FRbeta are attached to cell membranes by hydrophobic GPI (glycosylphosphatidylinositol) anchors, whereas FBPgamma is a secretory protein. Mature neutrophil granulocytes contain a non-functional FRbeta on the surface, and, in addition, nanomolar concentrations of a secretory functional FBP (29 kDa) can be present in the secondary granules. A statistically significant correlation between the concentrations of functional FBP, probably a gamma isoform, in granulocytes and serum supported the hypothesis that serum FBP (29 kDa) mainly originates from neutrophils. The presence of FBP/FRalpha isoforms were established for the first time in human blood using antibodies specifically directed against human milk FBPalpha. The alpha isoforms identified on erythrocyte membranes, and in granulocytes and serum, only constituted an almost undetectable fraction of the functional FBP. The FBPalpha in neutrophil granulocytes was identified as a cytoplasmic component by indirect immunofluorescence. Gel filtration of serum revealed a peak of FBPalpha (>120 kDa), which could represent receptor fragments from decomposed erythrocytes and granulocytes. The soluble FBPs may exert bacteriostatic effects and protect folates in plasma from biological degradation, whereas FRs on the surface of blood cells could be involved in intracellular folate uptake or serve as signal proteins. The latter receptors have also been used for therapeutic targeting in malignancy.     

Coelomocyte numbers and expression of HSP70 in wounded sea stars during hypoxia

Hypoxia, mainly caused by eutrophication, is a common and growing problem on marine soft bottoms. Echinoderms are known for their ability to regenerate tissue after wounding but hypoxia has a negative influence on regeneration and also on reproduction in echinoderms. We have investigated the cellular and molecular responses to wounding stress and hypoxia in the sea star Asterias rubens by using the total coelomocyte count (TCC) and the expression of heat shock proteins (HSPs). As early as 1 h after wounding, sea stars under hypoxic conditions show significantly increased TCC and, after 6 h, cell numbers increase approximately two-fold. After a 3-h hypoxia exposure of wounded animals, Western blot analysis reveals highly elevated coelomocyte cytoplasmic HSP70 expression. Non-wounded sea stars exposed to hypoxia and wounded animals kept in normoxia show enhanced HSP70 expression only after 24 h. Immunocytochemical analysis has not demonstrated any translocation of HSP70 from the cytoplasm to the nucleus. We conclude that both wounding and hypoxia elicit a stress response in sea stars and that the combined stress produces synergistic effects that may inhibit the initial processes of wound healing and regeneration.     

Population Dynamics of the Dioecious Amazonian Palm Mauritia flexuosa: Simulation Analysis of Sustainable Harvesting

The dioecious, tropical palm Mauritia flexuosa has high ecological and economic value, but currently some wild populations are harvested excessively, which is likely to increase. In this study, we investigated the population dynamics of this important palm, the effects of harvesting, and suggested sustainable harvesting regimes. Data were collected from populations in the Ecuadorian Amazon that were assumed to be stable. We used a matrix population model to calculate the density-independent asymptotic population growth rate (λ= 1.046) and to evaluate harvesting scenarios. Elasticity analysis showed that survival (particularly in the second and fifth size class) contributes more to the population growth rate, than growth and fecundity. To simulate a stable population at carrying capacity, density dependence was incorporated and applied to the seedling survival and growth parameters in the transition matrix. Harvesting scenarios were simulated with the density-dependent population models to predict sustainable harvesting regimes for the dioecious palm. We simulated the removal of only female palms and showed how both sexes are affected with harvest intensities between 15 and 75 percent and harvest intervals of 1–15 yr. By assuming a minimum female threshold, we demonstrated a continuum of sustainable harvesting schedules for various intensities and frequencies for 100 yr of harvest. Furthermore, by setting the population model's λ= 1.00, we found that a harvest of 22.5 percent on a 20 yr frequency for the M. flexuosa population in Ecuador is consistent with a sustainable, viable population over time.     

Hyperinsulinemic rats are normotensive but sensitized to angiotensin II

The effect of insulin on blood pressure (BP) is debated, and an involvement of an activated renin-angiotensin aldosterone system (RAAS) has been suggested. We studied the effect of chronic insulin infusion on telemetry BP and assessed sympathetic activity and dependence of the RAAS. Female Sprague-Dawley rats received insulin (2 units/day, INS group, n = 12) or insulin combined with losartan (30 mg.kg(-1).day(-1), INS+LOS group, n = 10), the angiotensin II receptor antagonist, for 6 wk. Losartan-treated (LOS group, n = 10) and untreated rats served as controls (n = 11). We used telemetry to measure BP and heart rate (HR), and acute ganglion blockade and air-jet stress to investigate possible control of BP by the sympathetic nervous system. In addition, we used myograph technique to study vascular function ex vivo. The INS and INS+LOS groups developed euglycemic hyperinsulinemia. Insulin did not affect BP but increased HR (27 beats/min on average). Ganglion blockade reduced mean arterial pressure (MAP) similarly in all groups. Air-jet stress did not increase sympathetic reactivity but rather revealed possible blunting of the stress response in hyperinsulinemia. Chronic losartan markedly reduced 24-h-MAP in the INS+LOS group (-38 +/- 1 mmHg P < 0.001) compared with the LOS group (-18 +/- 1 mmHg, P 相似文献   

Evidence for numerous analogs of yessotoxin in Protoceratium reticulatum

A solid-phase extract from Protoceratium reticulatum was partitioned between water and butanol and the two fractions purified on an alumina column. Fractionation was monitored by ELISA and LC–MS. Results indicate that while almost all yessotoxin (1) was extracted into butanol, large amounts of yessotoxin analogs remained in the aqueous extract along with lesser amounts in the butanolic extract. NMR analysis of selected fractions from reverse-phase chromatography of the extracts confirmed the presence of yessotoxin analogs, although structure determinations were not possible due to the complexity of the mixtures. Analysis of fractions with LC–MS³ and neutral-loss LC–MS/MS indicated the presence of more than 90 yessotoxin analogs, although structures for most of these have not yet been determined. These analogs provide a mechanism to rationalise the discrepancy between ELISA and LC–MS analyses of algae and shellfish.