Long term effects of muscle-derived stem cells on leak point pressure and closing pressure in rats with transected pudendal nerves

The survival of muscle-derived cells injected into the urethra and bladder wall was described recently. In this study, we tested whether injections of periurethral muscle-derived stem cells (MDSC) and bovine collagen (BC) after denervation of the pudendal nerve could increase leak point pressure (LPP) and closing pressure (CP) in female rats over the long term. S-D rats were anesthetized with halothane and the pudendal nerves transected bilaterally via a dorsal incision in order to denervate the external urethral sphincter. In the collagen and MDSC groups (C & M), injection of collagen or MDSC was made into the proximal urethra after pudendal nerve transection. At 4 and 12 week, visually identified LPP and CP measurements were made using the vertical tilt/intravesical pressure clamp model of stress urinary incontinence. The rats were then sacrificed and urethra harvested for histology. Both LPP and CP were significantly lower in the denervated (D) group at each time compared with the normal (N), C, and M groups, and both LPP and CP in the C and M groups were significantly higher than in the D group at both 4 and 12 weeks. The persistence of MDSC over the period of study was verified by histology. Thus pudendal nerve denervation led to a progressive decline in LPP and CP that was evident at 4 week and persisted to 12 week, and injection of MDSC into the denervated rats led to a long term increase in LPP and CP.     

Poor physical fitness is independently associated with mild cognitive impairment in elderly Koreans

The purpose of this study was to investigate the association between physical fitness and mild cognitive impairment (MCI) in elderly Koreans. This was a cross-sectional study that involved 134 men and 299 women aged 65 to 88 years. Six senior fitness tests were used as independent variables: 30 s chair stand for lower body strength, arm curl for upper body strength, chair-sit-and-reach for lower body flexibility, back scratch for upper body flexibility, 8-ft up-and-go for agility/dynamic balance, and 2-min walk for aerobic endurance. Global cognitive function was assessed using the Korean version of the Mini-Mental State Examination (MMSE). Potential covariates such as age, education levels, blood lipids, and insulin resistance (IR) markers were also assessed. Compared to individuals without MMSE-based MCI, individuals with MMSE-based MCI had poor physical fitness based on the senior fitness test (SFT). There were significant positive trends observed for education level (p=0.001) and MMSE score (p<0.001) across incremental levels of physical fitness in this study population. Individuals with moderate (OR=0.341, p=0.006) and high (OR=0.271, p=0.007) physical fitness based on a composite score of the SFT measures were less likely to have MMSE-based MCI than individuals with low physical fitness (referent, OR=1). The strength of the association between moderate (OR=0.377, p=0.038) or high (OR=0.282, p=0.050) physical fitness and MMSE-based MCI was somewhat attenuated but remained statistically significant even after adjustment for the measured compounding factors. We found that poor physical fitness was independently associated with MMSE-based MCI in elderly Koreans.     

Rex1/Zfp42 is dispensable for pluripotency in mouse ES cells

Background  

Rex1/Zfp42 has been extensively used as a marker for the undifferentiated state of pluripotent stem cells. However, its function in pluripotent stem cells including embryonic stem (ES) cells remained unclear although its involvement in visceral endoderm differentiation in F9 embryonal carcinoma (EC) cells was reported.     

Molecular dynamics study of the KcsA potassium channel

The structural, dynamical, and thermodynamic properties of a model potassium channel are studied using molecular dynamics simulations. We use the recently unveiled protein structure for the KcsA potassium channel from Streptomyces lividans. Total and free energy profiles of potassium and sodium ions reveal a considerable preference for the larger potassium ions. The selectivity of the channel arises from its ability to completely solvate the potassium ions, but not the smaller sodium ions. Self-diffusion of water within the narrow selectivity filter is found to be reduced by an order of magnitude from bulk levels, whereas the wider hydrophobic section of the pore maintains near-bulk self-diffusion. Simulations examining multiple ion configurations suggest a two-ion channel. Ion diffusion is found to be reduced to approximately (1)/(3) of bulk diffusion within the selectivity filter. The reduced ion mobility does not hinder the passage of ions, as permeation appears to be driven by Coulomb repulsion within this multiple ion channel.