Lactate profiles in blood and sweat during exercise and heat induced sweating

Blood lactate levels and sweat lactate excretion were determined during exercise and subsequently during heat induced sweating, in the same subjects in an attempt to investigate the contribution of blood lactate to the sweat lactate excretion. Eighteen male volunteers of ages 15- 32 participated in the study. Exercise was performed on a cycle ergometer and involved a stepwise increase in workload until exhaustion. A passenger van with shutters up parked in the afternoon sun was used to create a warm environment-for heat-induced sweating. Both exercise (0.017 ± 0.001 L/min/m2) and the warm environment (0.013 ± 0.001 /min/m2) induced comparable rates of sweating. Pretest blood lactate levels were similar before exercise (2.2 ± 0.16 mmol/L) and heat test (1.9 ± 0.12 mmol/L). However, blood lactate levels during exercise (10.4 ± 0.42 mmol/L) were significant higher than levels during heat induced sweating (1.9 ± 0.10 mmol/L) (P < 0.001). Sweat lactate excretion during exercise (1.03 ± 0.11 mmol/min/m2) was significantly greater than sweat lactate excretion during heat induced sweating, (0.54 ± 0.04 mmol/min/m2) in spite of comparable volumes of sweat production.During heat induced sweating, sweat lactate excretion increased with increased sweat rates and the correlation a significant (r • 0.48) (p < 0.001). These results demonstrate that raised blood lactate levels during exercise contribute significantly to sweat lactate excretion. Sweat gland metabolism also contributes to sweat lactate excretion.The results cannot quantify the relative contributions of these two factors. Such quantification will necessitate further studies in the future. Whatever these respective contributions may be, sweat lactate excretion is probably not a sufficiently reliable index of aerobic capacity, to be recommended as a routine measurement because of its variability with varying sweat gland metabolism

Topological modeling of antimycobacterial activity of 3-formyl rifamycin SV derivatives

The paper describes topological modeling of antimycobacterial activity of 3-formyl rifamycin SV derivatives using a large series of molecular vis-à-vis topological descriptors. For the set of 53 derivatives of 3-formyl rifamycin SV no one variable model is possible, however, in multiparametric regression excellent model is obtained for modeling the activity. The results are discussed using variety of statistical parameters

Role of magnesium in essential hypertension

Beneficial role of magnasium supplementation in prevention of complications in coronary artery disease (Iseri,1984) in ischaemic heart disease (Altura,1988) and in the treatment of patients with AMI (Abraham,1990) has been well documented. One study showed that magnesium supplementation reduced arterial blood pressure in patients with hypertension (Dykner& Waster,1983).Renin profiling, nevertheless,has revealed higher,and lower magnesium levels in low renin and high renin hypertensives respectively (Resnick LM et a1 1983).The significance of this seems to be that the influence of magnesium intake on blood pressure may differ according to the underlying state of magnesium metabolism in hypertensive patients. These observations remain largely unconfirmed. Recently it has been reported that a disordered metabolism of magnesium and calcium ions is present in women with pregnancy induced hypertension (Singh, HJ 1993).So the objective of this study was to investigate the magnesium status in serum, erythrocyte and in urine of untreated hypertensive patients. Work was further extended to investigate the relationship between serum and urinary magnesium levels,plasma renin activity (PRA) and plasma renin concentration (PRC) in normotensive and age and sex-matched untreated hypertensives

Effect of Salt Coatings on Low Cycle Fatigue Behavior of Nickel -base Superalloy GTM-SU-718

AbstractNickel-base superalloys are used as components of gas turbines both of jet engines as well as marine engines. Sin e these components are subjected to high temperature and oxidizing environment, their performance is drastically affected by the environmental conditions. Marine environment further aggravates the situation due to presence of salt (NaCl) particles in air. This salt along with sulphur and vanadium present in the fuel oil, leads to formation of compounds like sodium sulfate (Na2SO4) and vanadium pentaoxide (V2O5) during combustion and causes hot corrosion and stress corrosion cracking of engine components. Strain controlled low cycle fatigue tests were conducted on the nickel base superalloy GTM-SU-718 in air, at room temperature on unexposed, exposed at 550°C for 25h, exposed at 650°C for 25h as well as on the specimens coated with layers of NaCl, 25wt.%NaCl+75wt.%Na2SO4 and 90wt.%Na2SO4+5wt.%NaCl+5wt.%V2O5 salt/salt mixtures separately and exposed at elevated temperatures for 25h. While the NaCl coated sample was exposed at 550°C, those coated with other two salt mixtures were exposed at 650°C. It was observed that fatigue life of the NaCl coated sample, exposed at 550°C for 25h was reduced, however, there was little effect on fatigue life of the other specimens referred to above, including even those coated with salt mixtures and exposed at 650°C

Crossing w=-1 in Gauss-Bonnet Brane World with Induced Gravity

Recent type Ia supernovas data seemingly favor a dark energy model whose equation of state $w(z)$ crosses -1 very recently, which is a much more amazing problem than the acceleration of the universe. In this paper we show that it is possible to realize such a crossing without introducing any phantom component in a Gauss-Bonnet brane world with induced gravity, where a four dimensional curvature scalar on the brane and a five dimensional Gauss-Bonnet term in the bulk are present. In this realization, the Gauss-Bonnet term and the mass parameter in the bulk play a crucial role.Comment: Revtex 16 pages including 10 eps files, references added, to appear in Comm. Theor. Phy

Orbit spaces of free involutions on the product of two projective spaces

Let $X$ be a finitistic space having the mod 2 cohomology algebra of the product of two projective spaces. We study free involutions on $X$ and determine the possible mod 2 cohomology algebra of orbit space of any free involution, using the Leray spectral sequence associated to the Borel fibration $X \hookrightarrow X_{\mathbb{Z}_2} \longrightarrow B_{\mathbb{Z}_2}$. We also give an application of our result to show that if $X$ has the mod 2 cohomology algebra of the product of two real projective spaces (respectively complex projective spaces), then there does not exist any $\mathbb{Z}_2$-equivariant map from $\mathbb{S}^k \to X$ for $k \geq 2$ (respectively $k \geq 3$), where $\mathbb{S}^k$ is equipped with the antipodal involution.Comment: 14 pages, to appear in Results in Mathematic

Fermi surfaces and quasi-particle band dispersions of the iron pnictides superconductor KFe2As2 observed by angle-resolved photoemission spectroscopy

We have performed an angle-resolved photoemission study of the iron pnictide superconductor KFe2As2 with Tc 4 K. Most of the observed Fermi surfaces show almost two-dimensional shapes, while one of the quasi-particle bands near the Fermi level has a strong dispersion along the kz direction, consistent with the result of a band-structure calculation. However, hole Fermi surfaces \alpha and \zeta are smaller than those predicted by the calculation while other Fermi surfaces are larger. These observations are consistent with the result of a de Haas-van Alphen study and a theoretical prediction on inter-band scattering, possibly indicating many body effects on the electronic structure.Comment: 4 pages, 5 figures. Proceeding of the 9th International Conference on Spectroscopies in Novel Superconductors (SNS2010

First-principles Calculation of the Formation Energy in MgO-CaO Solid Solutions

The electronic structure and total energy were calculated for ordered and disordered MgO-CaO solid solutions within the multiple scattering theory in real space and the local density approximation. Based on the dependence of the total energy on the unit cell volume the equilibrium lattice parameter and formation energy were determined for different solution compositions. The formation energy of the solid solutions is found to be positive that is in agreement with the experimental phase diagram, which shows a miscibility gap.Comment: 11 pages, 3 figure