A comparison of blood gases and acid-base measurements in arterial, arterialized venous, and venous blood during short-term maximal exercise

The purpose of this study was to determine the relationship between blood gases and acid-base measurements in arterial, arterialized venous, and venous blood measured simultaneously during short-term maximal exercise. Ten well-trained male cyclists performed a graded maximal exercise test on a cycle ergometer to determine the power output corresponding to their peak oxygen consumption (test I), and a short-term maximal test on a cycle ergometer at peak power output (test II). During test II arterial, arterialized venous and venous blood were sampled simultaneously for determination of partial pressures of oxygen and carbon dioxide, pH, bicarbonate (HCO3-), base excess (BE), and lactate (La). Samples were taken at rest, the end of 1 min of exercise (1 ME), at the end of exercise (EE), and at 2 min of recovery (REC). During test II, subjects maintained a peak power output of 370.6 (62.1) W [mean (SD)] for 4.5, SD 1.6 min. Except at rest venous and arterialized venous measurements tended to be the same at all sampling intervals, but differed significantly from measurements in arterial blood (P less than 0.05). BE was the only variable that rendered consistently significant correlations between arterial and arterialized venous blood at each sampling interval. The pooled correlation coefficient between arterial and arterialized venous BE was r = 0.83 [regression equation: BEa = (0.84 BEav)-0.51]. Arterial La was significantly higher than venous La at 1 ME (2.8, 0.7 vs 0.8, 0.3 mmol.l-1) and higher than both venous and arterialized venous La at EE.(ABSTRACT TRUNCATED AT 250 WORDS)     

Parameter relation rows: a query system for protein structure function relationships

In the course of molecular modeling or mutant prediction one often wants quick answers to questions such as: 'Are there any residues in a beta-strand that point into an internal cavity, and are highly mutable?' 'Are there large polar residues in a helix that make a contact with a hydrophobic residue in a sheet, and don't make the maximal number of hydrogen bonds?' or 'Which hydrophobic residues are in a helix with a large hydrophobic moment, and make a contact with a co-factor, but at the same time still have a large accessible surface?'. I describe here a method to get answers to these kinds of questions in a very quick and easy manner. The method described is partly based on the principles used in the design of relational databases, and its mode of operation is similar to the query methods used in a relational database environment. Although designed for aiding in molecular modeling, its applicability is much more general. The method has been implemented as part of a large molecular modeling package which copes with the numerous problems in systematic handling of protein structures, e.g. residue numbering. This also implies that many normal tools such as graphical analyses, I/O facilities, etc. are available on-line.     

Preservation of plastic properties of synaptic transmission in long-lasting hippocampal slices under the effects of a peptide analog of piracetam, L-pGlu-D-Ala-NH2

The tetanic stimulation of the Schaffer collaterals (SC) in rat hippocamp slices after 6 hrs in vitro conditions did not produce long-term potentiation (LTP) of the field response amplitude in the CA1 pyramidal cell layer. In contrast, LTP after the late tetanization was well preserved in the slices that were perfused for 20 minutes with 0.5 mkM L-pGlu-D-Ala-NH2 (PGAA) after 4-4.5 hrs in vitro. There were no significant reactivity changes during the perfusion of the slices with this drug concentration. Two other drugs with nootropic activity, piracetam (100 mkM) and gamma-hydroxybutyrate (100 mkM, Na-salt) did not prevent the disappearance of LTP in the late period in vitro, while enhanced the reactivity during perfusion period. The maintenance of the plastic properties of the SC-CA1 synaptic transmission under the influence of PGAA is thought to be the result of some specific interaction of the drug with LTP induction mechanisms. LTP damaged in the late period in vitro might be a new model of memory disturbances and this model can turn out to be useful for the comparative estimation of the effectiveness of the drugs with proposed nootropic activity and for the analysis of the possible mechanisms of their action.     

Role of serotonin receptors in the amygdaloid complex and central gray substance in conditioned passive avoidance reaction in rats

The functional role of 5-HT1 receptors in the memory trace retrieval was investigated in amygdala (AM), central gray substance of midbrain (CGS) and frontal cortex. There is used the passive avoidance response in the rat. The decrease of 5-HT1 binding sites in AM and CGS was revealed for the rats with retention of the passive avoidance response. The binding of 3H-5-HT in AM was found two sets of binding sites. It was concluded, that 5-HT1 receptors of AM and CGS are involved in learning processes either in the moment of the memory trace retrieval or immediately after it.     

Overproduction and purification of the uncI gene product of the ATP synthase of Escherichia coli

The uncI gene, the first gene of the unc operon, has been cloned into an expression vector carrying the lambda PRPL promoters in tandem orientation and the gene cI857 coding for the thermolabile repressor. Linkage of the uncI gene to an efficient ribosome binding site (the translational initiation region of the uncE gene) resulted in 10-20-fold increased gene expression. The i protein has been extracted from overproducing cells using chloroform/methanol and purified to homogeneity by ion exchange chromatography. Analyzing the products of the uncI gene encoded by different plasmids, we provide evidence that, in contrast to the previously reported data (Walker, J. E., Saraste, M., and Gay, N. J. (1984) Biochim. Biophys. Acta 768, 164-200), the chromosome-encoded i protein contains the N-terminal sequence Ser-Val-Ser-Leu-Val-Ser-Arg and has a molecular weight of 13,504.     

The determination of the oxidation phenotype in inbred C57Bl/6 and BALB/c mice

Antipyrine oxidation was studied in C57BL/6 and BALB/c inbred mice. It was found that C57BL/6 are weak oxidant but BALB/c are strong oxidants of antipyrine. Animals F1 hybrids inherited the high capacity of antipyrine oxidation.     

Sex-dependent effect of melatonin on the secretory activity of rat and hamster adrenal gland in vitro

Adrenal quarters from adult male or female hamsters were incubated in the presence of melatonin (10(-7) or 10(-4)M), and cortisol concentration in the incubation medium was assayed by RIA. Melatonin did not change cortisol output by adrenals obtained from the male hamsters, while a slight stimulatory effect was observed in female glands, the lower concentration of melatonin being more effective than the higher one. At both concentrations tested, melatonin notably stimulated corticosterone output by isolated rat adrenocortical cells derived from the males, and lowered corticosterone secretion by the cells obtained from the female glands only at a concentration of 10(-7) M. The lower concentration of melatonin increased ACTH (0.1 mU.ml-1)-stimulated corticosterone output by the cells of male and female rat adrenals. The pineal hormone was ineffective at a concentration of 10(-4) M, as well as in the presence of a higher dose of ACTH (1.0 mU.ml-1). These findings indicate a distinct sex-dependent effect of melatonin on in vitro cortisol and corticosterone production, and demonstrate that the modulatory effect of melatonin of the secretion of steroid hormones is more effective at lower concentrations.     

Response of carbonic anhydrase to polyethylene glycol-mediated water stress in wheat

Carbonic anhydrase (CA) activity in wheat leaves changed upon leaf dehydration: it decreased at mild stress (relative water content, RWC, 81 %), but increased at severe water stress (RWC 74 %). Phosphoenopyruvate carboxylase activity was not significantly affected by these stresses. This revised version was published online in June 2006 with corrections to the Cover Date.