Eccentric exercise induces transient insulin resistance in healthy individuals.

Euglycemic-hyperinsulinemic clamps were performed on six healthy untrained individuals to determine whether exercise that induces muscle damage also results in insulin resistance. Clamps were performed 48 h after bouts of predominantly 1) eccentric exercise [30 min, downhill running, -17% grade, 60 +/- 2% maximal O2 consumption (VO2max)], 2) concentric exercise (30 min, cycle ergometry, 60 +/- 2% VO2max), or 3) without prior exercise. During the clamps, euglycemia was maintained at 90 mg/dl while insulin was infused at 30 mU.m-2.min-1 for 120 min. Hepatic glucose output (HGO) was determined using [6,6-2H]glucose. Eccentric exercise caused marked muscle soreness and significantly elevated creatine kinase levels (273 +/- 73, 92 +/- 27, 87 +/- 25 IU/l for the eccentric, concentric, and control conditions, respectively) 48 h after exercise. Insulin-mediated glucose disposal rate was significantly impaired (P less than 0.05) during the clamp performed after eccentric exercise (3.47 +/- 0.51 mg.kg-1.min-1) compared with the clamps performed after concentric exercise (5.55 +/- 0.94 mg.kg-1.min-1) or control conditions (5.48 +/- 1.0 mg.kg-1.min-1). HGO was not significantly different among conditions (0.77 +/- 0.26, 0.65 +/- 0.27, and 0.66 +/- 0.64 mg.kg-1.min-1 for the eccentric, concentric, and control clamps, respectively). The insulin resistance observed after eccentric exercise could not be attributed to altered plasma cortisol, glucagon, or catecholamine concentrations. Likewise, no differences were observed in serum free fatty acids, glycerol, lactate, beta-hydroxybutyrate, or alanine. These results show that exercise that results in muscle damage, as reflected in muscle soreness and enzyme leakage, is followed by a period of insulin resistance.     

中国西北沙漠夜间活动的东鳖甲属昆虫二新种(鞘翅目:拟步甲科:漠甲亚科)

记述中国西北地区东鳖甲属2新种:巴丹东鳖甲A.badainica Ba,Ren&Liu sp.nov.和古尔班东鳖甲A.gurbantunggutica Ba&Ren sp.nov.,提供了主要鉴别特征和形态图,并简要讨论了其昼夜活动规律.     

Effects of increased meal frequency on fat oxidation and perceived hunger

Objective:

Consuming smaller, more frequent meals is often advocated as a means of controlling body weight, but studies demonstrating a mechanistic effect of this practice on factors associated with body weight regulation are lacking. The purpose of this study was to compare the effect of consuming three (3M) vs. six meals (6M) per day on 24‐h fat oxidation and subjective ratings of hunger.

Design and Methods:

Lean (body mass index <25 kg/m²) subjects (7M, 8F) were studied in a whole‐room calorimeter on two occasions in a randomized cross‐over design. Subjects were provided isoenergetic, energy balanced diets with a 1‐ to 2‐week washout between conditions. Hunger, fullness, and “desire to eat” ratings were assessed throughout the day using visual analog scales and quantified as area under the curve (AUC).

Results:

There were no differences (P < 0.05) in 24‐h energy expenditure (8.7 ± 0.3 vs. 8.6 ± 0.3 mj d^?1), 24‐h respiratory quotient (0.85 ± 0.01 vs. 0.85 ± 0.01), or 24‐h fat oxidation (82 ± 6 vs. 80 ± 7 g day^‐1) between 3M and 6M, respectively. There was no difference in fullness 24‐h AUC, but hunger AUC (41850 ± 2255 vs. 36612 ± 2556 mm.24 h, P = 0.03) and “desire to eat” AUC (47061 ± 1791 vs. 41170 ± 2574 mm.24 h, P = 0.03) were greater during 6M than 3M.

Conclusion:

We conclude that increasing meal frequency from three to six per day has no significant effect on 24‐h fat oxidation, but may increase hunger and the desire to eat.

     

Haemosporidian Parasites of Antelopes and Other Vertebrates from Gabon,Central Africa

Re-examination, using molecular tools, of the diversity of haemosporidian parasites (among which the agents of human malaria are the best known) has generally led to rearrangements of traditional classifications. In this study, we explored the diversity of haemosporidian parasites infecting vertebrate species (particularly mammals, birds and reptiles) living in the forests of Gabon (Central Africa), by analyzing a collection of 492 bushmeat samples. We found that samples from five mammalian species (four duiker and one pangolin species), one bird and one turtle species were infected by haemosporidian parasites. In duikers (from which most of the infected specimens were obtained), we demonstrated the existence of at least two distinct parasite lineages related to Polychromophilus species (i.e., bat haemosporidian parasites) and to sauropsid Plasmodium (from birds and lizards). Molecular screening of sylvatic mosquitoes captured during a longitudinal survey revealed the presence of these haemosporidian parasite lineages also in several Anopheles species, suggesting a potential role in their transmission. Our results show that, differently from what was previously thought, several independent clades of haemosporidian parasites (family Plasmodiidae) infect mammals and are transmitted by anopheline mosquitoes.     

Molecular basis of ion permeability in a voltage‐gated sodium channel

Voltage‐gated sodium channels are essential for electrical signalling across cell membranes. They exhibit strong selectivities for sodium ions over other cations, enabling the finely tuned cascade of events associated with action potentials. This paper describes the ion permeability characteristics and the crystal structure of a prokaryotic sodium channel, showing for the first time the detailed locations of sodium ions in the selectivity filter of a sodium channel. Electrostatic calculations based on the structure are consistent with the relative cation permeability ratios (Na⁺ ≈ Li⁺ ≫ K⁺, Ca²⁺, Mg²⁺) measured for these channels. In an E178D selectivity filter mutant constructed to have altered ion selectivities, the sodium ion binding site nearest the extracellular side is missing. Unlike potassium ions in potassium channels, the sodium ions in these channels appear to be hydrated and are associated with side chains of the selectivity filter residues, rather than polypeptide backbones.     

HRT preserves increases in bone mineral density and reductions in body fat after a supervised exercise program

The aims of thisstudy were to confirm our previous finding that hormone-replacementtherapy (HRT) augments exercise-induced increases in bone mineraldensity (BMD) in older women and to determine whether HRT preserves theadaptations when exercise is reduced or discontinued. The studyincluded an 11-mo treatment phase and a 6-mo follow-up phase.Participants, aged 66 ± 3 yr, were assigned to control (Con;n = 10), exercise (Ex;n = 18), HRT(n = 10), and Ex+HRT(n = 16) groups. HRT was continuedduring the follow-up. After the treatment phase, changes in total body BMD were 0.5 ± 1.7, 1.5 ± 1.4, 1.2 ± 0.8, and 2.7 ± 1.2% in Con, Ex, HRT, and Ex+HRT, respectively. Ex+HRT was moreeffective than HRT in increasing BMD of the total body and tended(P = 0.08) to be more effective at thelumbar spine. Ex+HRT was more effective than Ex in increasing BMD ofthe total body, lumbar spine, and trochanter. Exercise-induced gains inBMD were preserved during the follow-up only in those individuals onHRT. HRT also attenuated fat accumulation, particularly in theabdominal region, after the exercise program. These findings suggestthat HRT is an important adjunct to exercise for the prevention notonly of osteoporosis but also of diseases related to abdominal obesity.

     

Efficacy of hyaluronic acid binding assay in selecting motile spermatozoa with normal morphology at high magnification

Background  

The present study aimed to evaluate the efficacy of the hyaluronic acid (HA) binding assay in the selection of motile spermatozoa with normal morphology at high magnification (8400x).     

Pyrazole inhibitors of HMG-CoA reductase: an attempt to dramatically reduce synthetic complexity through minimal analog re-design

An extraordinarily potent and hepatoselective class of HMG-CoA reductase inhibitors containing a pyrazole core was recently reported; however, its development was hampered by a long and difficult synthetic route. We attempted to circumvent this obstacle by preparing closely related analogs wherein the key dihydroxyheptanoic acid sidechain was tethered to the pyrazole core via an oxygen linker ('oxypyrazoles'). This minor change reduced the total number of synthetic steps from 14 to 7. Although the resulting analogs maintained much of the in vitro and cell activity of the pyrazoles, inferior in vivo activity precluded further development. Caco-2 cell permeability data suggest that enhanced cellular efflux of the oxypyrazoles relative to the pyrazoles may be responsible for the poor in vivo activity.