Ramp and constant power trials produce equivalent critical power estimates

The standard critical power test protocol on the cycle prescribes a series of trials to exhaustion, each at a different but constant power setting. Recently the protocol has been modified and applied to a series of trials to exhaustion each at a different ramp incremental rate. This study was undertaken to compare critical power and anaerobic work capacity estimates in the same group of subjects when derived from the two protocols. Ten male subjects of mixed athletic ability cycled to exhaustion on eight occasions in randomized order over a 3-wk period. Four trials were performed at differing constant power settings and four trials on differing ramp incremental rates. Both critical power and anaerobic work capacity were estimated for each subject by curve fitting of the ramp model and of three versions of the constant power model. After adjusting for inter-subject variability, no significant differences were detected between critical power estimates or between anaerobic work capacity estimates from any model formulation or from the two protocols. It is concluded that both the ramp and constant power protocols produce equivalent estimates for critical power and anaerobic work capacity.

Effect of milling conditions on the synthesis of chromium carbides by mechanical alloying

The synthesis of chromium carbides, Cr7C3 and Cr3C2, by mechanically allowing chromium and carbon powders has been investigated. Milling conditions were found to have a strong influence on the evolution of microstructure, with high collision energies being required to form carbide phases. Milling at intermediate energy levels resulted in the formation of an amorphous phase, and with low energy conditions only grain size refinement of Cr occurred with no evidence of any reaction between Cr and C. The amorphous phase was found to be the precursor to carbide formation. (C) 1997 Elsevier Science S.A.

Synthesis, identification, characterization, stability, solubility, and protein binding of ester derivatives of salicylic acid and diflunisal

O-Acyl esters were prepared from salicylic acid and diflunisal by esterification with the appropriate acyl anhydride (in the presence of sulfuric acid at 80 degrees C) or acyl chloride (in the presence of pyridine at 0 degrees C). Synthesis, identification and characterization of these compounds is described. In vitro hydrolysis, solubility and protein binding studies of these O-acyl esters were performed. For the diflunisal esters, the melting points fell as the side chain was increased from ethyl to pentyl. The melting points showed no significant difference as the length of the side chain was increased from pentyl to heptyl. The aspirin analogues showed a similar trend, The relationship between solubility and carbon chain length agreed closely with that for the melting points with carbon chain length. In vitro non-enzymatic hydrolysis studies concluded that: (1) hydrolysis rate constants generally decreased with carbon chain length; (2) the diflunisal esters have shorter half lives compared with their salicylate counterparts; and (3) the in vitro hydrolysis of these compounds was retarded by the presence of bovine serum albumin. Protein binding experiments showed that the strength of binding of the aspirin and diflunisal analogues to bovine serum albumin increased with carbon chain length. (C) 1997 Elsevier Science B.V.

Chemistry of 5-oxodihydroisoxazoles .18. Synthesis of oxazoles by the photolysis and pyrolysis of 2-acyl-5-oxo-2,5-dihydroisoxazoles

N-Acylisoxazol-5-ones lose carbon dioxide under photochemical and thermal conditions affording iminocarbenes which undergo intramolecular cyclisation through the oxygen of the acyl group to give oxazoles. Under photochemical conditions those acylisoxazolones with electron withdrawing groups at C-4 usually give high yields of oxazoles, while those with electron donating groups at C-4 give only poor yields: the reverse is observed under thermal conditions.

The chemistry of 5-oxodihydroisoxazoles .19. The synthesis and photolysis of N-thioacylisoxazol-5(2H)-ones

5-Oxodihydroisoxazoles react with thiocarbonyl chlorides to afford N-thioacylisoxazol-5(2H)-ones which lose carbon dioxide under photochemical conditions and undergo intramolecular cyclisation of the iminocarbene to afford thiazoles, However, in some cases loss of carbon dioxide is accompanied by loss of sulfur, giving 1,3-oxazin-6-ones.

Potential GABAB receptor antagonists .9. The synthesis of 3-amino-3-(4-chlorophenyl)propanoic acid, 2-amino-2-(4-chlorophenyl)ethylphosphonic acid and 2-amino-2-(4-chlorophenyl)ethanesulfonic acid

This paper describes the synthesis of 3-amino-3-(4-chlorophenyl)propanoic acid and the corresponding phosphonic and sulfonic acids, lower homologues of baclofen, phaclofen and saclofen respectively. The chlorinated acids were all weak specific antagonists of GABA at the GABAB receptor, with the sulfonic acid (pA(2) 4.0) being stronger than the phosphonic acid (pA(2) 3.8) and carboxylic acid (pA(2) 3.5).

The biomimetic synthesis of marine epoxylipids: Bisepoxides to tetrahydrofurans

The biomimetic synthesis of novel lipids 1, 2, 8 and 10 obtained from the southern Australian marine brown alga Notheia anomala has been achieved, and features the acid mediated conversion of methylene interrupted bisepoxides to tetrahydrofurans. (C) 1997 Elsevier Science Ltd.

Equivalent Neurogenic Potential of Wild-Type and GFP-Labeled Fetal-Derived Neural Progenitor Cells Before and After Transplantation Into the Rodent Hippocampus

Introduction. The hippocampal formation is a specific structure in the brain where neurogenesis occurs throughout adulthood and in which the neuronal cell loss causes various demential states. The main goal of this study was to verify whether fetal neural progenitor cells (NPCs) from transgenic rats expressing green fluorescent protein (GFP) retain the ability to differentiate into neuronal cells and to integrate into the hippocampal circuitry after transplantation. Methods. NPCs were isolated from E14 (gestational age: 14 days postconception) transgenic-Lewis and wild-type Sprague-Dawley rat embryos. Wild-type and transgenic cells were expanded and induced to differentiate into a neuronal lineage in vitro. Immunocytochemical and electrophysiological analysis were performed in both groups. GFP-expressing cells were implanted into the hippocampus and recorded electrophysiologically 3 months thereafter. Immunohistochemical analysis confirmed neuronal differentiation, and the yield of neuronal cells was determined stereologically. Results. NPCs derived from wild-type and transgenic animals are similar regarding their ability to generate neuronal cells in vitro. Neuronal maturity was confirmed by immunocytochemistry and electrophysiology, with demonstration of voltage-gated ionic currents, firing activity, and spontaneous synaptic currents. GFP-NPCs were also able to differentiate into mature neurons after implantation into the hippocampus, where they formed functional synaptic contacts. Conclusions. GFP-transgenic cells represent an important tool in transplantation studies. Herein, we demonstrate their ability to generate functional neurons both in vitro and in vivo conditions. Neurons derived from fetal NPCs were able to integrate into the normal hippocampal circuitry. The high yield of mature neurons generated render these cells important candidates for restorative approaches based on cell therapy.

Synthesis of Fructooligosaccharides in Banana `Prata` and Its Relation to Invertase Activity and Sucrose Accumulation

Levels of sucrose and total fructool igosaccha rides (FOS) were quantified in different phases of banana `Prata` ripening during storage at ambient (similar to 19 degrees C) and low (similar to 10 degrees C) temperature. Total FOS levels were detected in the first days after harvest, whereas 1-kestose remained undetectable until the sucrose levels reached approximately 200 mg/g (dry weight) in both groups. Sucrose levels increased slowly but constantly at low temperature, but they elevated rapidly when the temperature was raised to 19 degrees C. Total FOS and sucrose levels were higher in bananas stored at low temperature than in the control group. In both samples, total FOS levels were higher than those of 1-kestose. The carbohydrate profiles obtained by HPLC and TLC suggest the presence of neokestose, 6-kestose, and bifurcose. The enzymes putatively involved in banana fructosyltransferase activity were also evaluated. Results obtained indicate that the banana enzyme responsible for the synthesis of FOS by transfructosylation is an invertase rather than a sucrose-sucrosyl transferase-like enzyme.

Synthesis, spectroscopic characterization, DFT studies and biological assays of a novel gold(I) complex with 2-mercaptothiazoline

A new gold(I) complex with 2-mercaptothiazoline (MTZ) with the coordination formula [AuCN(C(3)H(5)NS(2))] was synthesized and characterized by chemical and spectroscopic measurements, OFT studies and biological assays. Infrared (IR) and (1)H, (13)C and (15)N nuclear magnetic resonance (NMR) spectroscopic measurements indicate coordination of the ligand to gold(I) through the nitrogen atom. Studies based on OFT confirmed nitrogen coordination to gold(I) as a minimum of the potential energy surface with calculations of the hessians showing no imaginary frequencies. Thermal decomposition starts at temperatures near 160 degrees C, leading to the formation of Au as the final residue at 1000 degrees C. The gold(I) complex with 2-mercaptothiazoline (Au-MTZ) is soluble in dimethyl sulfoxide (DMSO), and is insoluble in water, methanol, ethanol, acetonitrile and hexane. The antibacterial activities of the Au-MTZ complex were evaluated by an antibiogram assay using the disc diffusion method. The compound showed an effective antibacterial activity against Staphylococcus aureus (Gram-positive) and Escherichia coli and Pseudomonas aeruginosa (Gram-negative) bacterial cells. Biological analysis for evaluation of the cytotoxic effect of the Au-MTZ complex was performed using HeLa cells derived from human cervical adenocarcinoma. The complex presented a potent cytotoxic activity, inducing 85% of cell death at a concentration of 2.0 mu mol L(-1). (C) 2011 Elsevier Ltd. All rights reserved.

Fatty acid synthesis and generation of glycerol-3-phosphate in brown adipose tissue from rats fed a cafeteria diet

In vivo fatty acid synthesis and the pathways of glycerol-3-phosphate (G3P) production were investigated in brown adipose tissue (BAT) from rats fed a cafeteria diet for 3 weeks. In spite of BAT activation, the diet promoted an increase in the carcass fatty acid content. Plasma insulin levels were markedly increased in cafeteria diet-fed rats. Two insulin-sensitive processes, in vivo fatty acid synthesis and in vivo glucose uptake (which was used to evaluate G3P generation via glycolysis) were increased in BAT from rats fed the cafeteria diet. Direct glycerol phosphorylation, evaluated by glycerokinase (GyK) activity and incorporation of [U-(14)C]glycerol into triacylglycerol (TAG)-glycerol, was also markedly increased in BAT from these rats. In contrast, the cafeteria diet induced a marked reduction of BAT glyceroneogenesis, evaluated by phosphoenolpyruvate carboxykinase-C activity and incorporation of [1-(14)C]pyruvate into TAG-glycerol. BAT denervation resulted in an approximately 50% reduction of GyK activity, but did not significantly affect BAT in vivo fatty acid synthesis, in vivo glucose uptake, or glyceroneogenesis. The data suggest that the supply of G3P for BAT TAG synthesis can be adjusted independently from the sympathetic nervous system and solely by reciprocal changes in the generation of G3P via glycolysis and via glyceroneogenesis, with no participation of direct phosphorylation of glycerol by GyK.

Glutamine supplementation does not improve protein synthesis rate by the jejunal mucosa of the malnourished rat

It has been demonstrated that glutamine, a conditionally essential amino acid, improves nitrogen balance, acts as a stimulant of protein synthesis, and decreases proteolysis in myopathic children. In contrast, other studies have shown no beneficial effect of glutamine supplementation on burn victims or critically ill patients. Nonetheless, we hypothesized that glutamine supplementation would increase the fractional protein synthesis rate (FSR) in the jejunal mucosa of malnourished male Wistar rats. Thus, the objective of the present study was to test the effect of daily oral glutamine supplementation (0.42 g kg(-1) d(-1) for 14 days) on the FSR of the jejunal mucosa of healthy and malnourished rats. A 4-hour kinetic study with L-[1-(13)C]leucine was subsequently performed, and jejunal biopsies were obtained 1.5 cm from the Treitz angle and analyzed. Malnourished rats showed a 25% weight loss and increased urinary nitrogen excretion. Plasma amino acid concentration did not differ between groups. (13)C enrichment in plasma and jejunal cells was higher in the malnourished groups than in the healthy group. The FSR (percent per hour) was similar for the control and experimental groups (P > .05), with a mean range of 220%/h to 27%/h. Oral glutamine supplementation alone did not induce higher protein incorporation by the jejunal mucosa in malnourished rats, regardless of total food intake or the presence or absence of glutamine supplementation. (C) 2009 Elsevier Inc. All rights reserved.

OXIDATIVE STRESS BIOMARKER RESPONSES TO AN ACUTE SESSION OF HYPERTROPHY-RESISTANCE TRADITIONAL INTERVAL TRAINING AND CIRCUIT TRAINING

Deminice, R, Sicchieri, T, Mialich, MS, Milani, F, Ovidio, PP, and Jordao, AA. Oxidative stress biomarker responses to an acute session of hypertrophy-resistance traditional interval training and circuit training. J Strength Cond Res 25(3): 798-804, 2011-We have studied circuit resistance schemes with high loads as a time-effective alternative to hypertrophy-traditional resistance training. However, the oxidative stress biomarker responses to high-load circuit training are unknown. The aim of the present study was to compare oxidative stress biomarker response with an acute session of hypertrophy-resistance circuit training and traditional interval training. A week after the 1 repetition maximum (1RM) test, 11 healthy and well-trained male participants completed hypertrophy-resistance acute sessions of traditional interval training (3 x 10 repetitions at 75% of the 1RM, with 90-second passive rest) and circuit training (3 x 10 repetitions at 75% of the 1RM, in alternating performance of 2 exercises with different muscle groups) in a randomized and cross-over design. Venous blood samples were collected before (pre) and 10 minutes after (post) the resistance training sessions for oxidative stress biomarker assays. As expected, the time used to complete the circuit training (20.2 +/- 1.6) was half of that needed to complete the traditional interval training (40.3 +/- 1.8). Significant increases (p < 0.05) in thiobarbituric acid reactive substances (40%), creatine kinase (CK) (67%), glutathione (14%), and uric acid (25%) were detected posttraditional interval training session in relation to pre. In relation to circuit training, a significant increase in CK (33%) activity postsession in relation to pre was observed. Statistical analysis did not reveal any other change in the oxidative stress biomarker after circuit training. In conclusion, circuit resistance-hypertrophy training scheme proposed in the current study promoted lower oxidative stress biomarkers and antioxidant modulations compared with resistance traditional interval training.

Ethinylestradiol and estradiol have different effects on oxidative stress and nitric oxide synthesis in human endothelial cell cultures

Study objective: To compare the effects of ethinylestradiol (EE) and 17 beta-estradiol (E(2)) on nitric oxide (NO) production and protection against oxidative stress in human endothelial cell cultures. Design: Experimental study. Settings: Research laboratory. Material: Human ECV304 endothelial cell cultures. Intervention(s): The NO synthesis was determined by flow cytometry, and oxidative stress was determined by a cell viability assay, after exposure to hydrogen peroxide (H(2)O(2)) and stimulation of endothelial cells with EE at concentrations similar to those of a contraceptive containing 30 mu g EE. Main Outcome Measure(s): The effects of EE were compared with those of E(2) at concentrations similar to those occurring during the follicular phase. Result(s): Ethinylestradiol did not increase NO synthesis and did not protect cells against oxidative stress. The viability of the cells incubated with E(2) in combination with H(2)O(2) was greater than the viability obtained with H(2)O(2) only or with H(2)O(2) in combination with EE. The cells stimulated with E(2) presented a significant increase in NO production compared with control. Conclusion(s): In contrast to the effects of E(2), EE did not protect human ECV304 endothelial cells against oxidative stress and did not increase their production of NO. (Fertil Steril (R) 2010; 94: 1578-82. (C) 2010 by American Society for Reproductive Medicine.)

Nitric oxide synthesis blockade reduced the baroreflex sensitivity in trained rats

Objective: The present study has investigated the effect of blockade of nitric oxide synthesis on cardiovascular autonomic adaptations induced by aerobic physical training using different approaches: 1) double blockade with methylatropine and propranolol; 2) systolic arterial pressure (SAP) and heart rate variability (HRV) by means of spectral analysis; and 3) baroreflex sensitivity. Methods: Male Wistar rats were divided into four groups: sedentary rats (SR); sedentary rats treated with N(omega)-nitro-L-arginine methyl ester (L-NAME) for one week (SRL); rats trained for eight weeks (TR); and rats trained for eight weeks and treated with L-NAME in the last week (TRL). Results: Hypertension and tachycardia were observed in SRL group. Previous physical training attenuated the hypertension in L-NAME-treated rats. Bradycardia was seen in TR and TRL groups, although such a condition was more prominent in the latter. All trained rats had lower intrinsic heart rates. Pharmacological evaluation of cardiac autonomic tonus showed sympathetic predominance in SRL group, differently than other groups. Spectral analysis of HRV showed smaller low frequency oscillations (LF: 0.2-0.75 Hz) in SRL group compared to other groups. Rats treated with L-NAME presented greater LF oscillations in the SAP compared to non-treated rats, but oscillations were found to be smaller in TRL group. Nitric oxide synthesis inhibition with L-NAME reduced the baroreflex sensitivity in sedentary and trained animals. Conclusion: Our results showed that nitric oxide synthesis blockade impaired the cardiovascular autonomic adaptations induced by previous aerobic physical training in rats that might be, at least in part, ascribed to a decreased baroreflex sensitivity. (C) 2009 Elsevier B.V. All rights reserved.