Norepinephrine, but not epinephrine, enhances platelet reactivity and coagulation after exercise in humans

The effects of exercise and catecholamineson platelet reactivity or coagulation and fibrinolysis appear to beinconsistent. This may be partly due to the methods employed inprevious studies. In the present study, we investigated the effects ofacute aerobic exercise and catecholamines on the thrombotic status by anovel in vitro method, shear-induced hemostatic plug formation(hemostatometry), using nonanticoagulated (native) blood. Aerobicexercise (60% maximal O₂consumption) was performed by healthy male volunteers for 20 min, andthe effect on platelet reactivity and coagulation was assessed byperforming hemostatometry before and immediately after exercise.Exercise significantly increased shear-induced platelet reactivity,coagulation, and catecholamine levels. The effect of catecholamines onplatelet reactivity and coagulation was assessed in vitro by addingcatecholamines to blood collected in the resting state. The mainfindings of the present study are that elevation of circulatingnorepinephrine at levels that are attained during exercise causesplatelet hyperreactivity and a platelet-mediated enhanced coagulation.This may be a mechanism of an association of aerobic exercise withthrombotic risk.

     

The susceptibility of pregnant mice to encephalomyocarditis (EMC) virus infection on different days of gestation.

Pregnant mice of the BALB/c CrSlc strain were experimentally infected with the D variant of encephalomyocarditis virus (EMC-D, 5 x 10(2) PFU/head) on three different gestational days (GD). Mice were intraperitoneally inoculated with EMC-D on 11, 13 and 15 GD and sacrificed 3 days post inoculation. There was no significant difference in the fetal mortality among all inoculation groups. Placenta showed higher virus titer than fetus and dam's serum in all inoculation groups, and the virus titer of the fetus was lowest in the 15GD group. Histopathological changes and signals of viral RNAs detected by in situ hybridization were observed almost restricted to the spongiotrophoblast layer of the placenta in all inoculation groups, and the signals were strongest in the 11GD group. In the fetus of the11GD group, signals of viral RNAs were also seen in myocardium and hepatocytes. Ultrastructurally, intracytoplasmic aggregations of virus-like particles in crystalline array were observed in trophoblast cells and giant cells in the spongiotrophoblast layer in all inoculation groups.     

Changes in activities of enzymes in erythrocytes from ddY mice supplemented with dietary selenium.

Plasma and erythrocyte enzyme activities were measured in ddY mice supplemented with dietary selenium (Se) from baker's yeast (Saccharomyces serevisiae) or selenious acid at 0.3 ppm Se content. Glutathione peroxidase (GSHpx) activities increased significantly in erythrocytes from mice supplemented with dietary Se. It was concluded that addition of dietary Se as food additive is very effective for activation of GSHpx in mice.     

Effects of chronic administration of bilobalide on amino acid levels in mouse brain.

We have previously demonstrated that 4-day-treatment of mice with bilobalide, a sesquiterpene of Ginkgo biloba L., increases GABA levels in mouse brain, but, effects of chronic treatment with it are not clear. To study effects of chronic treatment of mice with bilobalide on amino acid levels in the brain, we determined the levels of aspartate, glutamate, serine, glutamine, glycine, taurine and GABA in the hippocampus, striatum and cortex. Bilobalide (3 mg/kg/day) was administered orally to 4-week-old mice for 40 days. Bilobalide treatment resulted in a significant increase in the levels of glutamate, aspartate, gamma-aminobutyric acid (GABA), and glycine in the hippocampus of mice compared with the control. An increased level of glycine after bilobalide treatment was also detected in the striatum. In the cortex, bilobalide increased the GABA level, whereas it decreased the level of aspartate. These changes in the levels of various amino acids may be involved in the broad spectrum of pharmacological activities of the extract of Ginkgo biloba on the central nervous system.     

Nucleoid Condensation and Cell Division in Escherichia coli MX74T2 ts52 After Inhibition of Protein Synthesis

The reorganization of the bacterial nucleoid of an Escherichia coli mutant, MX74T2 ts52, was studied by electron microscopy after protein synthesis inhibition by using whole mounts of cell ghosts, ultrathin-sectioning, and freeze-etching. The bacterial nucleoid showed two morphological changes after chloramphenicol addition: deoxyribonucleic acid (DNA) localization and DNA condensation. DNA localization was observed 10 min after chloramphenicol addition; the DNA appeared as a compact, solid mass. DNA condensation was observed at 25 min; the nucleoid appeared as a cytoplasm-filled sphere, often opened at one end. Ribosomes were observed in the center. Giant nucleoids present in some mutant filaments showed fused, spherical nucleoids arranged linearly, suggesting that the tertiary structure of the nucleoid reflects the number of replicated genomes. Inhibitors which directly or indirectly blocked protein synthesis and caused DNA condensation were chloramphenicol, puromycin, amino acid starvation, rifampicin, or carbonyl cyanide m-chlorophenyl hydrazone. All inhibitors that caused cell division in the mutant also caused condensation, although some inhibitors caused condensation without cell division. Nucleoid condensation appears to be related to chromosome structure rather than to DNA segregation upon cell division.     

A triangular loop of domain D1 of FlgE is essential for hook assembly but not for the mechanical function

The bacterial flagellar hook is a short, curved tubular structure made of FlgE. The hook connects the basal body as a rotary motor and the filament as a helical propeller and functions as a universal joint to smoothly transmit torque produced by the motor to the filament. Salmonella FlgE consists of D0, Dc, D1 and D2 domains. Axial interactions between a triangular loop of domain D1 (D1-loop) and domain D2 are postulated to be responsible for hook supercoiling. In contrast, Bacillus FlgE lacks the D1-loop and domain D2. Here, to clarify the roles of the D1-loop and domain D2 in the mechanical function, we carried out deletion analysis of Salmonella FlgE. A deletion of the D1-loop conferred a loss-of-function phenotype whereas that of domain D2 did not. The D1-loop deletion inhibited hook polymerization. Suppressor mutations of the D1-loop deletion was located within FlgD, which acts as the hook cap to promote hook assembly. This suggests a possible interaction between the D1-loop of FlgE and FlgD. Suppressor mutant cells produced straight hooks, but retained the ability to form a flagellar bundle behind a cell body, suggesting that the loop deletion does not affect the bending flexibility of the Salmonella hook.     

Structural stability of flagellin subunit affects the rate of flagellin export in the absence of FliS chaperone

FliS chaperone binds to flagellin FliC in the cytoplasm and transfers FliC to a sorting platform of the flagellar type III export apparatus through the interaction between FliS and FlhA for rapid and efficient protein export during flagellar filament assembly. FliS also suppresses the secretion of an anti‐σ factor, FlgM. Loss of FliS results in a short filament phenotype although the expression levels of FliC are increased considerably due to an increase in the secretion level of FlgM. Here to clarify the rate limiting step of FliC export in the absence of FliS, we isolated bypass mutants from a Salmonella ΔfliS mutant. All the bypass mutations were identified in FliC. These bypass mutations increased the export rate of FliC by ca. twofold, allowing the bypass mutant cells to produce longer filaments than the parental ΔfliS cells. Both far‐UV CD measurements and limited proteolysis revealed that the bypass mutations significantly destabilize the folded structure of FliC monomer. These results suggest that an unfolding step of FliC limits the export rate of FliC in the ΔfliS mutant, thereby producing short filaments. We propose that FliS promotes FliC docking at the FlhA platform to facilitate subsequent unfolding of FliC.     

Activation of caspase 3 in HepG2 cells by elaidic acid (t18:1)

In order to examine the effects of trans-unsaturated fatty acids (TFAs) on HepG2 cells, cells were grown in serum-free media supplemented with elaidic acid (t18:1); t18:1 is the trans-isomer of oleic acid and is the major component of TFAs in foods. Both t18:1 and palmitic acids (16:0) at concentrations higher than 100 microM inhibited growth and decreased the rate of protein synthesis. The presence of phosphatidylserine in the outer leaflet of the lipid bilayer, indicative of apoptosis, occurred 1 h after the addition of both t18:1 and 16:0 to the media. Caspase 3 was found to be activated by these fatty acids: caspase 8 was activated by 16:0 and only moderately by t18:1. Activation of caspase 3 by these fatty acids was fully inhibited by a caspase 8 inhibitor. However, growth inhibition by t18:1 was partially prevented by the caspase 8 inhibitor. These results suggest that cell death caused by t18:1 may proceed by both caspase-dependent and -independent pathways.     

Identification of a neuron-specific human gene, KIAA1110, that is a guanine nucleotide exchange factor for ARF1

To identify neuron-specific genes, we performed gene expression profiling, cDNA microarray and in silico ESTs (expressed sequence tags) analyses. We identified a human neuron-specific gene, KIAA1110 (homologue of rat synArfGEF (Po)), that is a member of the guanine nucleotide exchange factor (GEF) for the ADP-ribosylation factor (ARF). RT-PCR analysis showed that the KIAA1110 gene was expressed specifically in the brain among adult human tissues, whereas no apparent expression was observed in immature neural tissues/cells, such as fetal brain, glioma tissues/cells, and neural stem/precursor cells (NSPCs). The KIAA1110 protein was shown to be expressed in mature neurons but not in undifferentiated NSPCs. Immunohistochemical analysis also showed that KIAA1110 was expressed in neurons of the human adult cerebral cortex. Furthermore, the pull-down assay revealed that KIAA1110 has a GEF activity toward ARF1 that regulates transport along the secretion pathway. These results suggest that KIAA1110 is expressed specifically in mature neurons and may play an important role in the secretion pathway as a GEF for ARF1.