Evolution of mammalian X-linked and autosomal Pgk and Pdh E1 alpha subunit genes

The phylogeny and substitution rates of the mammalian X chromosome- located and autosomal phosphoglycerate kinase and pyruvate dehydrogenase genes were investigated. Compatibility analysis was used to show reticulate evolution in these genes. Analysis of the marsupial, mouse, and human phosphoglycerate kinase genes suggests that at least two recombination events have taken place, one occurring about the time of the placental-marsupial split involving exons 1-5 and the other before the primate-rodent split involving exons 9-10. Similar analysis of the pyruvate dehydrogenase genes indicates a recombination event involving exons 2-3 at a time before the primate-rodent split and a gene conversion between exons 3-4 in the human somatic and testis- specific pyruvate dehydrogenase genes after the primate-rodent split. This demonstrates that genetic exchange can occur between paralogous genes at widely separated chromosomal locations. Estimation of nucleotide substitution rates in these genes confirmed a higher substitution rate in the pyruvate dehydrogenase genes. In the phosphoglycerate kinase genes, there is no difference between the substitution rates in mice and humans and between the X chromosome- and autosome-located genes. A greater substitution rate was noted in the mouse autosomal pyruvate dehydrogenase gene when compared with the other mouse and human genes. This may be a result of either directional natural selection or a relaxation of functional constraint at this specific gene.      

Lamellar lubrication in vivo and vitro: friction testing of hexagonal boron nitride

Phospholipid molecules (PLs) in vivo and graphite, molybdenum disulfide, tungsten disulfide and hexagonal boron nitride (h-BN) in vitro are good examples of frictionless lubricants. PLs and solid materials have the ability to form multi-bilayer or layered structures similar to lamellate solid. It has been confirmed experimentally that PLs as lamellar lubricants protect the surface of joints against wear while acting as frictionless lubricant. An experimental study has been conducted on the friction properties of h-boron nitride on porous non-full journal bearings. The porous non-full journal bearings were a mixture of 97.5 wt.% Fe and 2.5 wt.% Cu powder, and compressed to a density of 5.9 g/cm(3). The porosity of non-full journal bearings were 15.5 and 27.8 wt.% and were impregnated with vaseline and vaseline+5 wt.% h-BN. Additionally, the two additives SFR NLGI #2 (or SFR 2522) grease and graphite grease were used for comparison to h-BN. The tribological tests were performed on a four-ball machine under load of 49 daN, and a friction tribotester. The above experiment strongly suggested that h-BN has the ability to lubricate under load with very low friction coefficient comparable to phospholipids. Relatively low surface energy and low adhesion between the crystallites are giving the additives low friction coefficient. The results of the experimental studies showed that h-BN as an additive in vaseline possesses friction reducing properties, and excellent anti-wear properties.     

Performance of dye-affinity beads for aluminium removal in magnetically stabilized fluidized bed

BACKGROUND: Aluminum has recently been recognized as a causative agent in dialysis encephalopathy, osteodystrophy, and microcytic anemia occurring in patients with chronic renal failure who undergo long-term hemodialysis. Only a small amount of Al(III) in dialysis solutions may give rise to these disorders. METHODS: Magnetic poly(2-hydroxyethyl methacrylate) (mPHEMA) beads in the size range of 80-120 microm were produced by free radical co-polymerization of HEMA and ethylene dimethacrylate (EDMA) in the presence of magnetite particles (Fe3O4). Then, metal complexing ligand alizarin yellow was covalently attached onto mPHEMA beads. Alizarin yellow loading was 208 micromol/g. These beads were used for the removal of Al(III) ions from tap and dialysis water in a magnetically stabilized fluidized bed. RESULTS: Al(III) adsorption capacity of the beads decreased with an increase in the flow-rate. The maximum Al(III) adsorption was observed at pH 5.0. Comparison of batch and magnetically stabilized fluidized bed (MSFB) maximum capacities determined using Langmuir isotherms showed that dynamic capacity (17.5 mg/g) was somewhat higher than the batch capacity (11.8 mg/g). The dissociation constants for Al(III) were determined using the Langmuir isotherm equation to be 27.3 mM (MSFB) and 6.7 mM (batch system), indicating medium affinity, which was typical for pseudospecific affinity ligands. Al(III) ions could be repeatedly adsorbed and desorbed with these beads without noticeable loss in their Al(III) adsorption capacity. CONCLUSIONS: Adsorption of Al(III) demonstrate the affinity of magnetic dye-affinity beads. The MSFB experiments allowed us to conclude that this inexpensive sorbent system may be an important alternative to the existing adsorbents in the removal of aluminium.     

Effects of Artichoke Extract Supplementation on Gonads of Cadmium-Treated Rats

The present study was designed to determine whether artichoke (Cynara scolymus) exerts a protective effect on gonads of cadmium-treated rats and if there is a relationship between artichoke supplementation and nitric oxide (NO) formation in cells. Forty Wistar albino male rats, weighing an average of 90 g each, were equally divided into four groups receiving 1 mg/100 g cadmium chloride by injection (group 1), the same dose CdCl₂ plus 3 mg/100 g artichoke extract (group 2), the same dose of artichoke extract (group 3), and male controls (group 4). Four additional groups, labeled 5–8, consisted of identically treated and control female rats. After 4 weeks of treatment, the animals were killed and their gonads were removed for histological examination. As expected, the seminiferous tubules and Leydig cells were damaged by cadmium. Ovarian tissue was not damaged to the same extent as testicular cells. Artichoke extract exerted a clear protective effect against Cd-induced testicular damage and lowered NO production to the same level of that in the control groups.     

Assessment of the P Wave Dispersion and Duration in Elite Women Basketball Players

Background

P wave dispersion is an independent predictor of atrial fibrillation. P wave dispersion is associated with inhomogeneous and discontinuous propagation of sinus impulses. The purpose of this study was to investigate P wave dispersion and transthoracic echocardiographic findings in elite women basketball players.

Methods

We recruited 27 well-trained woman athletes with a training history of many years (11.9 ± 3.6 years). All of the athletes were elite women basketball players and they were regularly maintaining sportive activities and training programs. Twenty-six age and sex matched healthy sedentary subjects consisted of control group. The difference between P maximum and P minimum durations was defined as P wave dispersion. The echocardiographic parameters were assessed in detail in the standard left lateral decubitus position.

Results

The body height, body weight, body surface area, metabolic equivalent, maximum P wave duration and P wave dispersion were increased in the elite basketball athletes as compared with healthy sedentary subjects. On the contrary; the heart rate, ejection fraction and interventricular septum thickness in diastole were decreased in athletes. The body height (p=0.006, r=0.37), body weight (p=0.04, r=0.28), body surface area (p=0.01, r=0.33) and heart rate (p=0.01, r=-0.32) were correlated with P wave dispersion.

Conclusions

P wave dispersion was increased in elite woman basketball players as compared with healthy sedentary subjects. P wave dispersion was correlated with heart rate, body height, body weight and body surface area.     

Gain-of-function p53 protein transferred via small extracellular vesicles promotes conversion of fibroblasts to a cancer-associated phenotype

1. Download : Download high-res image (201KB)
2. Download : Download full-size image

     

Heme oxygenase-1 plays a pro-life role in experimental brain stem death via nitric oxide synthase I/protein kinase G signaling at rostral ventrolateral medulla

Background  

Despite its clinical importance, a dearth of information exists on the cellular and molecular mechanisms that underpin brain stem death. A suitable neural substrate for mechanistic delineation on brain stem death resides in the rostral ventrolateral medulla (RVLM) because it is the origin of a life-and-death signal that sequentially increases (pro-life) and decreases (pro-death) to reflect the advancing central cardiovascular regulatory dysfunction during the progression towards brain stem death in critically ill patients. The present study evaluated the hypothesis that heme oxygnase-1 (HO-1) may play a pro-life role as an interposing signal between hypoxia-inducible factor-1 (HIF-1) and nitric oxide synthase I (NOS I)/protein kinase G (PKG) cascade in RVLM, which sustains central cardiovascular regulatory functions during brain stem death.