Effects of knee extensor muscle strength on the incidence of osteopenia and osteoporosis after 6 years

The association of knee extensor muscle strength with bone mineral density (BMD) has been reported in cross-sectional epidemiological studies, but it remains unclear whether or not this is the case with longitudinal change. Thus, we investigated whether or not the knee extension strength can predict the incidence of osteopenia or osteoporosis after 6 years, then compared the difference between sexes. Subjects were 1255 community-dwelling Japanese men and menopaused women, aged 40–81 years. BMD of lumbar spine and femoral neck was assessed by dual-energy X-ray absorptiometry twice at 6-year intervals. Subjects were divided into three groups, normal, osteopenia, and osteoporosis, depending on their young adult mean BMD % value. In the cross-sectional analysis the correlations between the knee extension strength and BMD of the two regions were examined, using Pearson’s correlation coefficient. Longitudinal analyses were then conducted to determine the odds ratio, controlled for age and BMI, given that those who were normal in the initial stage developed osteopenia or osteoporosis after 6 years, for every 1 SD decrease in knee extension strength, as well as those who first had normal or osteopenia and then developed osteoporosis. Cross-sectional analysis showed a statistically significant relation between knee extensor muscle strength and BMD at both the lumbar spine (p = 0.02) and the femoral neck (p < 0.0001) only in men. The longitudinal analysis showed the significant effect of muscle strength on the loss of femoral neck BMD from normal to osteopenia or osteoporosis both in men (OR 1.84, 95 % CI 1.36–2.48, p < 0.0001) and in women (OR 1.29, 95 % CI 1.002–1.65, p < 0.05), as well as on the loss of spinal BMD from normal or osteopenia to osteoporosis only in men (OR 2.97, 95 % CI 1.07–8.23, p < 0.05). The results suggest the importance of knee extension strength to maintain the bone health of the proximal femur and spine in aging particularly in men.     

The Dose-Response Relationship Between Body Mass Index and the Risk of Incident Stage ≥3 Chronic Kidney Disease in a General Japanese Population: The Ibaraki Prefectural Health Study (IPHS)

Purpose

To examine the relationship between body mass index (BMI) and the risk of stage ≥3 chronic kidney disease (CKD) in a general Japanese population.

Methods

A total of 105 611 participants aged 40–79 years who completed health checkups in Ibaraki Prefecture, Japan, and were free of CKD in 1993 were followed-up through 2006. Stage ≥3 CKD was defined by an estimated glomerular filtration rate <60 mL/min/1.73 m² reported during at least 2 successive annual surveys or as treatment for kidney disease. Hazard ratios (HRs) for the development of stage ≥3 CKD relative to the BMI categories were calculated using the Cox proportional hazards regression model, which was adjusted for possible confounders and mediators.

Results

During a mean follow-up of 5 years, 19 384 participants (18.4%) developed stage ≥3 CKD. Compared to a BMI of 21.0–22.9 kg/m², elevated multivariable-adjusted HRs were observed among men with a BMI ≥23.0 kg/m² and women with a BMI ≥27.0 kg/m². Significant dose-response relationships between BMI and the incidence of stage ≥3 CKD were observed in both sexes (P for trend <0.001).

Conclusions

Obesity was associated with the risk of developing stage ≥3 CKD among men and women.Key words: chronic kidney disease, body mass index, obesity, dose-response relationship, epidemiology     

Stretching versus transitory icing: which is the more effective treatment for attenuating muscle fatigue after repeated manual labor?

Purpose

Effective recovery from muscle fatigue, especially during rest intervals between periods of high-intensity activity, is important to ensure optimal subsequent performance. Stretching and icing are two types of treatment used for muscle recovery in such situations. However, their effectiveness remains unclear because of a lack of adequate evidence and/or discrepant results of previous studies. We performed a study to elucidate the effects of stretching and icing on muscle fatigue in subjects performing alternating muscle contraction and rest.

Methods

Sixteen healthy male subjects aged 21–27 years were evaluated. Each subject performed repeated isometric muscle contraction exercises that involved lifting and holding a dumbbell to induce muscle fatigue. Four treatments were performed during the rest periods between isometric muscle contraction: static stretching, ballistic stretching, no stretching, or icing. Electromyography and relative muscle oxygen saturation measurements were performed during the exercises. Muscle fatigue was indirectly estimated by the decline in the median frequency of the electromyographic signal.

Results

Stretching between alternate isometric muscle contraction exercises resulted in a significantly lower median frequency of the electromyographic signal than did no stretching. There was no significant difference in the change in the median frequency between static and ballistic stretching. Conversely, icing between alternate exercises did not decrease the median frequency.

Conclusions

Stretching, whether static or ballistic, is not beneficial for recovery from muscle fatigue and may actually inhibit recovery. Icing may more effectively induce such recovery and thus may be a better choice between the two treatment techniques.     

Attenuated nuclear shrinkage in neurones with nuclear inclusions of SCA1 brains

BACKGROUND: Spinocerebellar ataxia type 1 (SCA1) is one of the autosomal dominant neurodegenerative disorders commonly linked to pathological expansion of the CAG repeat of the relevant gene. Nuclear inclusions and neurodegeneration are both triggered by this pathological expansion of the CAG/polyglutamine repeat on ataxin-1, but it remains to be determined whether or not nuclear inclusion formation is associated with accelerated neurodegeneration. OBJECTIVE: To examine the influence of nuclear inclusions on nuclear size and deformity in human brains from patients suffering from SCA1. MATERIAL: Pontine sections of brains obtained at necropsy from seven patients with SCA1 and five controls. METHODS: The size and deformity of each neuronal nucleus was quantified. Nuclei with and without inclusions were examined separately to assess the possible influence of nuclear inclusions on neurodegeneration. RESULTS: Nuclear shrinkage and deformity were more marked in SCA1 brains than in controls. This shrinkage was attenuated in neurones containing nuclear inclusions. CONCLUSIONS: The existence of nuclear inclusions in SCA1 is presumably linked to a mechanism that attenuates rather than accelerates nuclear shrinkage. This in vivo finding may provide a clue to constructing a rational therapeutic strategy for combating neurodegeneration associated with nuclear inclusions.     

Delineating developmental and metabolic pathways in vivo by expression profiling using the RIKEN set of 18,816 full-length enriched mouse cDNA arrays

We have systematically characterized gene expression patterns in 49 adult and embryonic mouse tissues by using cDNA microarrays with 18,816 mouse cDNAs. Cluster analysis defined sets of genes that were expressed ubiquitously or in similar groups of tissues such as digestive organs and muscle. Clustering of expression profiles was observed in embryonic brain, postnatal cerebellum, and adult olfactory bulb, reflecting similarities in neurogenesis and remodeling. Finally, clustering genes coding for known enzymes into 78 metabolic pathways revealed a surprising coordination of expression within each pathway among different tissues. On the other hand, a more detailed examination of glycolysis revealed tissue-specific differences in profiles of key regulatory enzymes. Thus, by surveying global gene expression by using microarrays with a large number of elements, we provide insights into the commonality and diversity of pathways responsible for the development and maintenance of the mammalian body plan.