Reduced strength after passive stretch of the human plantarflexors.

The purpose of this study was to assess strength performance after an acute bout of maximally tolerable passive stretch (PS(max)) in human subjects. Ten young adults (6 men and 4 women) underwent 30 min of cyclical PS(max) (13 stretches of 135 s each over 33 min) and a similar control period (Con) of no stretch of the ankle plantarflexors. Measures of isometric strength (maximal voluntary contraction), with twitch interpolation and electromyography, and twitch characteristics were assessed before (Pre), immediately after (Post), and at 5, 15, 30, 45, and 60 min after PS(max) or Con. Compared with Pre, maximal voluntary contraction was decreased at Post (28%) and at 5 (21%), 15 (13%), 30 (12%), 45 (10%), and 60 (9%) min after PS(max) (P < 0.05). Motor unit activation and electromyogram were significantly depressed after PS(max) but had recovered by 15 min. An additional testing trial confirmed that the torque-joint angle relation may have been temporarily altered, but at Post only. These data indicate that prolonged stretching of a single muscle decreases voluntary strength for up to 1 h after the stretch as a result of impaired activation and contractile force in the early phase of deficit and by impaired contractile force throughout the entire period of deficit.     

Restriction fragment length polymorphisms distinguish ectomycorrhizal fungi

Basidiomycetous fungi, two saprophytes and three mycorrhizal, were used to assess the specificity of DNA hybridization for distinguishing genera from one another. Interspecific comparisons were done with several isolates of mycorrhizal fungi,Laccaria bicolor andL. laccata, collected from diverse geographical sites. The DNAs were digested with four restriction nucleases and separated by gel electrophoresis into patterns of DNA fragments called restriction fragment length polymorphisms (RFLPs). The RFLPs were hybridized with a radioactively-labeled DNA probe encoding Basidiomycetous ribosomal RNA genes. The five genera were discernable using both unprobed and probed RFLPs. Hybridization of probe DNA with RFLPs was isolate-specific for all nine Laccaria isolates examined. The reclassification of aL. bicolor isolate is supported, demonstrating that hybridization of RFLPs offers an additional tool for taxonomy of ectomycorrhizal fungi. The method may have field application for distinguishing known isolates if their DNA fingerprints are previously ascertained and are distinct from RFLPs of indigenous organisms.     

Relationships to skating performance in competitive hockey players

The purpose of this study was to identify off-ice variables that would correlate to on-ice skating sprint performance and cornering ability. Previous literature has not reported any off-ice testing variables that strongly correlate to on-ice cornering ability in ice hockey players. Thirty-six male hockey players aged 15-22 years (mean +/- SD: 16.3 +/- 1.7 years; weight = 70.8 +/- 10.4 kg; height = 175.6 +/- 4.1 cm) with an average of 10.3 +/- 3.0 years hockey playing experience (most at AA and AAA levels) participated in the study. The on-ice tests included a 35-m sprint and the cornering S test. The off-ice tests included the following: 30-m sprint, vertical jump, broad jump, 3 hop jump, Edgren side shuffle, Hexagon agility, side support, push-ups, and 15-second modified Wingate. The on-ice sprint test and cornering S test were strongly correlated (r = 0.70; p < 0.001). While many off-ice tests correlated with on-ice skating, measures of horizontal leg power (off-ice sprint and 3 hop jump) were the best predictors of on-ice skating performance, once weight and playing level were accounted for. These 4 variables accounted for a total of 78% (p < 0.0001) of the variance in on-ice sprint performance. No off-ice test accounted for unique variance in S-cornering performance beyond weight, playing level, and skating sprint performance. These data indicate that coaches should include horizontal power tests of off-ice sprint and 3 hop jump to adequately assess skating ability. To improve on-ice skating performance and cornering ability, coaches should also focus on the development of horizontal power through specific off-ice training, although future research will determine whether off-ice improvements in horizontal power directly transfer to improvements in on-ice skating.     

Condition-dependent dispersal of a patchily distributed riparian ground beetle in response to disturbance

In common with many habitat elements of riverine landscapes, exposed riverine sediments (ERS) are highly disturbed, naturally patchy and regularly distributed, whose specialists are strongly adapted to flood disturbance and loss of habitat due to succession. Investigations of dispersal in ERS habitats therefore provide an important contrast to the unnaturally fragmented, stable systems usually studied. The present investigation analysed the three interdependent stages of dispersal: (1) emigration, (2) inter-patch movement and (3) immigration of a common ERS specialised beetle, Bembidion atrocaeruleum (Stephens 1828) (Coleoptera, Carabidae), in a relatively unmodified section of river, using mark–resight methods. Dispersal was correlated with estimates of local population size and density, water level and patch quality in order to test for condition-dependent dispersal cues. Flood inundation of habitat was found to increase strongly the overall rate of dispersal, and the rate of emigration was significantly higher from patches that were heavily trampled by cattle. Strongly declining numbers of dispersers with distance suggested low dispersal rates during periods of low water level. Dispersal in response to habitat degradation by cattle trampling would likely lead to a higher overall population fitness than a random dispersal strategy. Dispersal distances were probably adapted to the underlying habitat landscape distribution, high-flow dispersal cues and ready means of long-distance dispersal through hydrochory. Species whose dispersal is adapted to the natural habitat distribution of riverine landscapes are likely to be strongly negatively affected by reduced flood frequency and intensity and habitat fragmentation through flow regulation or channelisation.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

Application of dried blood spots combined with HPLC-MS/MS for the quantification of acetaminophen in toxicokinetic studies

A reversed phase HPLC-MS/MS method has been developed and validated for the quantitative bioanalysis of acetaminophen in dried blood spots (DBS) prepared from small volumes (15 microL) of dog blood. Samples were extracted for analysis with methanol. Detection was by positive ion TurboIonSpray ionisation combined with selected reaction monitoring MS. The analytical concentration range was 0.1-50 microg/mL. The intra-day precision and bias values were both less than 15%. Acetaminophen was stable in DBS stored at room temperature for at least 10 days. The methodology was applied in a toxicokinetic (TK) study where the data obtained from DBS samples was physiologically comparable with results from duplicate blood samples (diluted 1:1 (v/v) with water) analysed using identical HPLC-MS/MS conditions. This work demonstrates that quantitative analysis of a drug extracted from DBS can provide high quality TK data while minimising the volume of blood withdrawn from experimental animals, to an order of magnitude lower than is current practice in the pharmaceutical industry. This is the first reported application of DBS analysis to a TK study in support of a safety assessment study. The success of this and similar, related studies has led to the intent to apply DBS technology as the recommended analytical approach for the assessment of pharmacokinetics (PK)/TK for all new oral small molecule drug candidates, which have previously demonstrated a successful bioanalytical validation.     

Selective inhibition of ADAMTS-1, -4 and -5 by catechin gallate esters.

Three mammalian ADAMTS enzymes, ADAMTS-1, -4 and -5, are known to cleave aggrecan at certain glutamyl bonds and are considered to be largely responsible for cartilage aggrecan catabolism observed during the development of arthritis. We have previously reported that certain catechins, polyphenolic compounds found in highest concentration in green tea (Camellia sinensis), are capable of inhibiting cartilage aggrecan breakdown in an in vitro model of cartilage degradation. We have now cloned and expressed recombinant human ADAMTS-1, -4 and -5 and report here that the catechin gallate esters found in green tea potently inhibit the aggrecan-degrading activity of these enzymes, with submicromolar IC50 values. Moreover, the concentration needed for total inhibition of these members of the ADAMTS group is approximately two orders of magnitude lower than that which is needed to partially inhibit collagenase or ADAM-10 activity. Catechin gallate esters therefore provide selective inhibition of certain members of the ADAMTS group of enzymes and could constitute an important nutritional aid in the prevention of arthritis as well as being part of an effective therapy in the treatment of joint disease and other pathologies involving the action of these enzymes.     

Human neuromuscular fatigue is associated with altered Na+-K+-ATPase activity following isometric exercise.

The purpose of this study was to investigate the hypothesis that reductions in Na+-K+- ATPase activity are associated with neuromuscular fatigue following isometric exercise. In control (Con) and exercised (Ex) legs, force and electromyogram were measured in 14 volunteers [age, 23.4 +/- 0.7 (SE) yr] before and immediately after (PST0), 1 h after (PST1), and 4 h after (PST4) isometric, single-leg extension exercise at ~60% of maximal voluntary contraction for 30 min using a 0.5 duty cycle (5-s contraction, 5-s rest). Tissue was obtained from vastus lateralis muscle before exercise in Con and after exercise in both the Con (PST0) and Ex legs (PST0, PST1, PST4), for the measurements of Na+-K+-ATPase activity, as determined by the 3-O-methylfluorescein phosphatase (3-O-MFPase) assay. Voluntary (maximal voluntary contraction) and elicited (10, 20, 50, 100 Hz) force was reduced 30-55% (P < 0.05) at PST0 and did not recover by PST4. Muscle action potential (M-wave) amplitude and area (measured in the vastus medialis) and 3-O-MFPase activity at PST0-Ex were less than that at PST0-Con (P < 0.05) by 37, 25, and 38%, respectively. M-wave area at PST1-Ex was also less than that at PST1-Con (P < 0.05). Changes in 3-O-MFPase activity correlated to changes in M-wave area across all time points (r = 0.38, P < 0.05, n = 45). These results demonstrate that Na+-K+- ATPase activity is reduced by sustained isometric exercise in humans from that in a matched Con leg and that this reduction in Na+-K+-ATPase activity is associated with loss of excitability as indicated by M-wave alterations.