Human skeletal muscle creatine transporter mRNA and protein expression in healthy,young males and females

The present study investigated whether there were any differences between males and females in respect to creatine transporter (CreaT) gene expression and/or total creatine (TCr) content in human vastus lateralis muscle. Skeletal muscle obtained from young healthy male (n = 13, age: 23.2 ± 5.0 years) and female subjects (n = 12, age: 21.7 ± 4.3 years) was analyzed for CreaT mRNA, CreaT protein and TCr content. Total CreaT protein content in the muscle was similar (p > 0.05) between the sexes. Two bands (~ 55 and 73 kDa) of the CreaT protein were detected in all muscle samples. Both the 55 and the 73 kDa bands were present in similar (p > 0.05) amounts in males compared with females. The 73 kDa band was in greater abundance (p < 0.05) than the 55 kDa band, irrespective of gender. In addition, CreaT mRNA expression relative to -actin mRNA and the TCr content (males: 117.8 ± 2.2, females: 125.3 ± 4.3 mmol.kg^–1 dry mass) were also unaffected (p > 0.05) by gender. These data demonstrate that gender does not influence skeletal muscle TCr content and CreaT gene expression in young human subjects.     

Muscle metabolites and performance during high-intensity, intermittent exercise

Six men werestudied during four 30-s "all-out" exercise bouts on anair-braked cycle ergometer. The first three exercise bouts wereseparated by 4 min of passive recovery; after the third bout, subjectsrested for 4 min, exercised for 30 min at 30-35% peakO₂ consumption, and rested for afurther 60 min before completing the fourth exercise bout. Peak powerand total work were reduced (P < 0.05) during bout 3 [765 ± 60 (SE) W; 15.8 ± 1.0 kJ] compared withbout 1 (1,168 ± 55 W, 23.8 ± 1.2 kJ), but no difference in exercise performance was observed betweenbouts 1 and4 (1,094 ± 64 W, 23.2 ± 1.4 kJ). Before bout 3, muscle ATP,creatine phosphate (CP), glycogen, pH, and sarcoplasmic reticulum (SR)Ca²⁺ uptake were reduced, whilemuscle lactate and inosine 5'-monophosphate wereincreased. Muscle ATP and glycogen before bout4 remained lower than values beforebout 1 (P < 0.05), but there were no differences in muscle inosine 5'-monophosphate, lactate, pH, and SR Ca²⁺ uptake. Muscle CP levelsbefore bout 4 had increased aboveresting levels. Consistent with the decline in muscle ATP wereincreases in hypoxanthine and inosine before bouts3 and 4. The decline in exercise performance does not appear to be related to a reduction inmuscle glycogen. Instead, it may be caused by reduced CP availability, increased H⁺ concentration,impairment in SR function, or some other fatigue-inducing agent.

     

Healthy Eating and Risks of Total and Cause-Specific Death among Low-Income Populations of African-Americans and Other Adults in the Southeastern United States: A Prospective Cohort Study

Background

A healthy diet, as defined by the US Dietary Guidelines for Americans (DGA), has been associated with lower morbidity and mortality from major chronic diseases in studies conducted in predominantly non-Hispanic white individuals. It is unknown whether this association can be extrapolated to African-Americans and low-income populations.

Methods and Findings

We examined the associations of adherence to the DGA with total and cause-specific mortality in the Southern Community Cohort Study, a prospective study that recruited 84,735 American adults, aged 40–79 y, from 12 southeastern US states during 2002–2009, mostly through community health centers that serve low-income populations. The present analysis included 50,434 African-Americans, 24,054 white individuals, and 3,084 individuals of other racial/ethnic groups, among whom 42,759 participants had an annual household income less than US$15,000. Usual dietary intakes were assessed using a validated food frequency questionnaire at baseline. Adherence to the DGA was measured by the Healthy Eating Index (HEI), 2010 and 2005 editions (HEI-2010 and HEI-2005, respectively). During a mean follow-up of 6.2 y, 6,906 deaths were identified, including 2,244 from cardiovascular disease, 1,794 from cancer, and 2,550 from other diseases. A higher HEI-2010 score was associated with lower risks of disease death, with adjusted hazard ratios (HRs) of 0.80 (95% CI, 0.73–0.86) for all-disease mortality, 0.81 (95% CI, 0.70–0.94) for cardiovascular disease mortality, 0.81 (95% CI, 0.69–0.95) for cancer mortality, and 0.77 (95% CI, 0.67–0.88) for other disease mortality, when comparing the highest quintile with the lowest (all p-values for trend < 0.05). Similar inverse associations between HEI-2010 score and mortality were observed regardless of sex, race, and income (all p-values for interaction > 0.50). Several component scores in the HEI-2010, including whole grains, dairy, seafood and plant proteins, and ratio of unsaturated to saturated fatty acids, showed significant inverse associations with total mortality. HEI-2005 score was also associated with lower disease mortality, with a HR of 0.86 (95% CI, 0.79–0.93) when comparing extreme quintiles. Given the observational study design, however, residual confounding cannot be completely ruled out. In addition, future studies are needed to evaluate the generalizability of these findings to African-Americans of other socioeconomic status.

Conclusions

Our results showed, to our knowledge for the first time, that adherence to the DGA was associated with lower total and cause-specific mortality in a low-income population, including a large proportion of African-Americans, living in the southeastern US.     

A Mutation in the Mitochondrial Fission Gene Dnm1l Leads to Cardiomyopathy

Mutations in a number of genes have been linked to inherited dilated cardiomyopathy (DCM). However, such mutations account for only a small proportion of the clinical cases emphasising the need for alternative discovery approaches to uncovering novel pathogenic mutations in hitherto unidentified pathways. Accordingly, as part of a large-scale N-ethyl-N-nitrosourea mutagenesis screen, we identified a mouse mutant, Python, which develops DCM. We demonstrate that the Python phenotype is attributable to a dominant fully penetrant mutation in the dynamin-1-like (Dnm1l) gene, which has been shown to be critical for mitochondrial fission. The C452F mutation is in a highly conserved region of the M domain of Dnm1l that alters protein interactions in a yeast two-hybrid system, suggesting that the mutation might alter intramolecular interactions within the Dnm1l monomer. Heterozygous Python fibroblasts exhibit abnormal mitochondria and peroxisomes. Homozygosity for the mutation results in the death of embryos midway though gestation. Heterozygous Python hearts show reduced levels of mitochondria enzyme complexes and suffer from cardiac ATP depletion. The resulting energy deficiency may contribute to cardiomyopathy. This is the first demonstration that a defect in a gene involved in mitochondrial remodelling can result in cardiomyopathy, showing that the function of this gene is needed for the maintenance of normal cellular function in a relatively tissue-specific manner. This disease model attests to the importance of mitochondrial remodelling in the heart; similar defects might underlie human heart muscle disease.     

Islands as refugia of <Emphasis Type="Italic">Trifolium repens</Emphasis> genetic diversity

Island populations are often thought to be more susceptible to the loss of genetic diversity as a consequence of limited population size and genetic drift, greater susceptibility to detrimental stochastic events and low levels of immigration. However the geographic isolation of islands may create refuges for native crop species whose genetic diversity is threatened from the genetic erosion occurring in mainland areas as a result of crop-wild gene flow and genetic swamping. Many UK islands remain uncharacterised in terms of plant genetic diversity. In this study we compared the genetic diversity of mainland populations and landraces of Trifolium repens with wild populations collected from the islands surrounding the UK, including the island of Hirta in the St Kildan archipelago. Individuals from St Kilda represent a unique conservation resource, with populations both highly differentiated from UK mainland populations and genetically distinct from cultivated varieties, whilst able to retain diversity through limited human influence on the islands. In contrast, there is relative genetic similarity of wild UK populations to cultivated forms highlighted in mainland populations, but with geographic barriers preventing complete homogenisation of the mainland UK genepool. We underline the need for conservation priorities to include common species that are threatened by gene flow from cultivation, and draw attention to the potential of islands to preserve natural levels of genetic diversity.     

Predicting Secchi disk depth from average beam attenuation in a deep,ultra-clear lake

We addressed potential sources of error in estimating the water clarity of mountain lakes by investigating the use of beam transmissometer measurements to estimate Secchi disk depth. The optical properties Secchi disk depth (SD) and beam transmissometer attenuation (BA) were measured in Crater Lake (Crater Lake National Park, Oregon, USA) at a designated sampling station near the maximum depth of the lake. A standard 20 cm black and white disk was used to measure SD. The transmissometer light source had a nearly monochromatic wavelength of 660 nm and a path length of 25 cm. We created a SD prediction model by regression of the inverse SD of 13 measurements recorded on days when environmental conditions were acceptable for disk deployment with BA averaged over the same depth range as the measured SD. The relationship between inverse SD and averaged BA was significant and the average 95% confidence interval for predicted SD relative to the measured SD was ±1.6 m (range = −4.6 to 5.5 m) or ±5.0%. Eleven additional sample dates tested the accuracy of the predictive model. The average 95% confidence interval for these sample dates was ±0.7 m (range = −3.5 to 3.8 m) or ±2.2%. The 1996–2000 time-series means for measured and predicted SD varied by 0.1 m, and the medians varied by 0.5 m. The time-series mean annual measured and predicted SD’s also varied little, with intra-annual differences between measured and predicted mean annual SD ranging from −2.1 to 0.1 m. The results demonstrated that this prediction model reliably estimated Secchi disk depths and can be used to significantly expand optical observations in an environment where the conditions for standardized SD deployments are limited.     

The discovery of potent, selective, and orally bioavailable hNK1 antagonists derived from pyrrolidine

SAR studies on amides, ureas, and vinylogous amides derived from pyrrolidine led to the discovery of several potent hNK(1) antagonists. One particular vinylogous amide (45b) had excellent potency, selectivity, pharmacokinetic profile, and functional activity in vivo. An in vivo rhesus macaque brain receptor occupancy PET study for compound 45b revealed an estimated Occ(90) approximately 300 ng/ml.     

Selective non zinc binding inhibitors of MMP13

Directed screening has identified a novel series of MMP13 inhibitors that possess good levels of activity whilst possessing excellent selectivity over related MMPs. The binding mode of the series has been solved by co-crystallisation and demonstrates an interesting mode of inhibition without interaction with the catalytic zinc atom.