Creatine reduces human muscle PCr and pH decrements and P(i) accumulation during low-intensity exercise.
(73/3106)
The purpose of this study was to examine with (31)P-magnetic resonance spectroscopy energy metabolism during repeated plantar flexion isometric exercise (Ex-1-Ex-4) at 32 +/- 1 and 79 +/- 4% of maximal voluntary contraction (MVC) before and during a creatine (Cr) feeding period of 5 g/day for 11 days. Eight trained male subjects participated in the study. ATP was unchanged with Cr supplementation at rest and during exercise at both intensities. Resting muscle phosphocreatine (PCr) increased (P < 0.05) from 18.3 +/- 0.9 (before) to 19.6 +/- 1.0 mmol/kg wet wt after 9 days. At 79% MVC, PCr used, P(i) accumulated, and pH at the end of Ex-1-Ex-4 were similar after 4 and 11 days of Cr supplementation. In contrast, PCr utilization and P(i) accumulation were lower and pH was higher for exercise at 32% MVC with Cr supplementation, suggesting aerobic resynthesis of PCr was more rapid during exercise. These results suggest that elevating muscle Cr enhances oxidative phosphorylation during mild isometric exercise, where it is expected that oxygen delivery matches demands and predominantly slow-twitch motor units are recruited. (+info)
Osseointegration of Ti6Al4V alloy implants coated with titanium nitride by a new method.
(74/3106)
Coating titanium alloy implants with titanium nitride (TiN) by the method of Powder Immersion Reaction Assisted Coating (PIRAC) produces a stable layer on their surface. We have examined the ability of the new TiN coating to undergo osseointegration. We implanted TiN-coated and uncoated Ti6Al4V alloy pins into the femora of six-month-old female Wistar rats. SEM after two months showed a bone collar around both TiN-coated and uncoated implants. Morphometrical analysis revealed no significant differences between the percentage of the implant-bone contact and the area and volume of the bone around TiN-coated compared with uncoated implants. Electron-probe microanalysis indicated the presence of calcium and phosphorus at the implant-bone interface. Mineralisation around the implants was also confirmed by labelling with oxytetracycline. Strong activity of alkaline phosphatase and weak activity of tartrate-resistant acid phosphatase were shown histochemically. Very few macrophages were detected by the non-specific esterase reaction at the site of implantation. Our findings indicate good biocompatibility and bone-bonding properties of the new PIRAC TiN coatings which are comparable to those of uncoated Ti6Al4V alloy implants. (+info)
Effect of intravenous fructose 1,6-diphosphate administration in malnourished chronic obstructive pulmonary disease patients with chronic respiratory failure.
(75/3106)
BACKGROUND: Weight loss and skeletal muscle wasting are common in patients with chronic obstructive pulmonary disease (COPD) and can influence the course and the prognosis of COPD. Hypophosphatemia is a pathologic status often characterized by muscle weakness and is a frequent laboratory finding in these patients. OBJECTIVE: The aim of the present study was to evaluate the effect of an organic phosphate (fructose 1,6-diphosphate, FDP) administration on respiratory performance in 45 malnourished COPD patients in stable clinical conditions. METHODS: Physiologic evaluation including spirometry, maximal voluntary ventilation (MMV), elevated arm test, maximal mouth pressures (PImax and PEmax), respiratory response to CO(2), oxygen (PaO(2)) and carbon dioxide (PaCO(2)) arterial tension, a visual analogic scale (VAS) to measure dyspnea, and complete blood tests were done at the beginning and again at the end of the study. RESULTS: After FDP administration, there was a significant increase in PImax (43.0 +/- 18.3 cm H(2)O before treatment vs. 49.8 +/- 14.9 cm H(2)O after treatment; p < 0.005). This did not occur in the placebo group (40.3 +/- 17.4 cm H(2)O before treatment vs. 42.6 +/- 20.1 cm H(2)O after treatment, nonsignificant). There was also a trend of VAS to decrease and of MVV to increase. CONCLUSIONS: These results show that FDP administration may be useful in the management of malnourished COPD patients, especially in increasing their respiratory muscle strength. (+info)
Oxidized phospholipids, linked to apolipoprotein B of oxidized LDL, are ligands for macrophage scavenger receptors.
(76/3106)
Previous studies have shown that macrophage receptors for oxidized LDL (OxLDL) recognize both the lipid and protein moieties, and that a monoclonal antibody against OxLDL, EO6, also recognizes both species. The present studies show directly that during LDL oxidation phospholipids become covalently attached to apolipoprotein B (apoB). After exhaustive extraction of lipids, apoB of native LDL contained 4 +/- 3 moles of phosphorus/mole protein. In contrast, apoB of OxLDL contained approximately 75 moles of phosphorus/mole protein. Saponification of this apoB released phosphorus, choline, and saturated fatty acids in a molar ratio of 1.0:0.98:0.84. When LDL was reductively methylated prior to oxidation, the amount of phospholipid covalently bound was reduced by about 80%, indicating that the phospholipids attach at lysine epsilon amino groups. Progressive decreases in the phospholipid associated with apoB of OxLDL decreased the ability of the protein to compete for binding to macrophage scavenger receptors and decreased its reactivity with antibody EO6. We postulate that some oxidized phospholipids containing fatty acid aldehydes at the sn-2 position bind to lysine residues of apoB while others remain unreacted within the lipid phase. This would account for the interchangeability of lipid and apolipoprotein of OxLDL with respect to receptor binding and antibody recognition. (+info)
Constitution of the cell envelope of Haemophilus influenzae in relation to competence for genetic transformation.
(77/3106)
Cell envelopes of Haemophilus influenzae have been prepared by breakage in a French pressure cell followed by differential centrifugation. The envelope fraction may be resolved into an inner-membrane (light) and an outer-membrane (heavy) fraction on density gradients. Envelopes from competent cells possess elevated levels of lipopolysaccharide with a composition different from that of log-phase cell envelopes. Three apparently new polypeptides have been observed in envelopes from competent cells by gel electrophoresis in sodium dodecyl sulfate; additional quantitative alterations in the profiles of membrane polypeptides also company the development of the capacity to transport deoxyribonucleic acid. Most of the polypeptide changes are confined to the outer membrane; one new polypeptide is associated with the inner cytoplasmic membrane of competent cells. Protein synthesis during competence developement is rquired for the change in lipopolysaccharides and in the envelope polypeptides to occur. (+info)
Coronary-artery calcification in young adults with end-stage renal disease who are undergoing dialysis.
(78/3106)
BACKGROUND: Cardiovascular disease is common in older adults with end-stage renal disease who are undergoing regular dialysis, but little is known about the prevalence and extent of cardiovascular disease in children and young adults with end-stage renal disease. METHODS: We used electron-beam computed tomography (CT) to screen for coronary-artery calcification in 39 young patients with end-stage renal disease who were undergoing dialysis (mean [+/-SD] age, 19+/-7 years; range, 7 to 30) and 60 normal subjects 20 to 30 years of age. In those with evidence of calcification on CT scanning, we determined its extent. The results were correlated with the patients' clinical characteristics, serum calcium and phosphorus concentrations, and other biochemical variables. RESULTS: None of the 23 patients who were younger than 20 years of age had evidence of coronary-artery calcification, but it was present in 14 of the 16 patients who were 20 to 30 years old. Among those with calcification, the mean calcification score was 1157+/-1996, and the median score was 297. By contrast, only 3 of the 60 normal subjects had calcification. As compared with the patients without coronary-artery calcification, those with calcification were older (26+/-3 vs. 15+/-5 years, P<0.001) and had been undergoing dialysis for a longer period (14+/-5 vs. 4+/-4 years, P< 0.001). The mean serum phosphorus concentration, the mean calcium-phosphorus ion product in serum, and the daily intake of calcium were higher among the patients with coronary-artery calcification. Among 10 patients with calcification who underwent follow-up CT scanning, the calcification score nearly doubled (from 125+/-104 to 249+/-216, P=0.02) over a mean period of 20+/-3 months. CONCLUSIONS: Coronary-artery calcification is common and progressive in young adults with end-stage renal disease who are undergoing dialysis. (+info)
Microbial community changes in biological phosphate-removal systems on altering sludge phosphorus content.
(79/3106)
Biomarkers (respiratory quinones and cellular fatty acids) and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA genes were used to characterize the microbial community structure of lab-scale enhanced biological phosphate-removal (EBPR) systems in response to altering sludge phosphorus (P) content. All the data suggest that the microbial community structures of sludge samples with a P content between 8 and 12.3% (sludge dry weight) (i.e. good EBPR activity) were very similar, but differed from those with 2% P content (i.e. no EBPR activity). For all samples analysed, ubiquinones Q-8 and Q-10, menaquinone MK-8(H4), and fatty acids C16:0, C16:1 omega9c and C18:1, omega11c were the major components. The dominance of Q-8, Q-10 and MK-8(H4) suggested that large numbers of organisms belonging to the beta and alpha subclasses of the Proteobacteria and the Actinobacteria from the high G+C Gram-positive bacteria, respectively, were present. DGGE analysis revealed at least 7-9 predominant DNA bands and numerous other fragments in each sample. Five major DGGE fragments from each of the 2% and 12% P-containing sludge samples, respectively, were successfully isolated and sequenced. Phylogenetic analysis of the sequences indicated that both 2% and 12% P-containing sludge samples shared three common phylotypes that were separately affiliated with a novel bacterial group from the gamma subclass of the Proteobacteria, two MK-8(H4)-containing actinobacteria previously isolated from the 2% P-containing sludge, and a Caulobacter spp. in the alpha subclass of the Proteobacteria. The phylogenetic analysis also revealed phylotypes unique to both sludge samples. Changes in sludge P content therefore had an effect on the composition and abundance of the predominant microbial populations, though specific phylotypes could not be unequivocally associated with EBPR. (+info)
Quantification in situ of crystalline cholesterol and calcium phosphate hydroxyapatite in human atherosclerotic plaques by solid-state magic angle spinning NMR.
(80/3106)
Because of renewed interest in the progression, stabilization, and regression of atherosclerotic plaques, it has become important to develop methods for characterizing structural features of plaques in situ and noninvasively. We present a nondestructive method for ex vivo quantification of 2 solid-phase components of plaques: crystalline cholesterol and calcium phosphate salts. Magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of human carotid endarterectomy plaques revealed (13)C resonances of crystalline cholesterol monohydrate and a (31)P resonance of calcium phosphate hydroxyapatite (CPH). The spectra were obtained under conditions in which there was little or no interference from other chemical components and were suitable for quantification in situ of the crystalline cholesterol and CPH. Carotid atherosclerotic plaques showed a wide variation in their crystalline cholesterol content. The calculated molar ratio of liquid-crystalline cholesterol to phospholipid ranged from 1.1 to 1.7, demonstrating different capabilities of the phospholipids to reduce crystallization of cholesterol. The spectral properties of the phosphate groups in CPH in carotid plaques were identical to those of CPH in bone. (31)P MAS NMR is a simple, rapid method for quantification of calcium phosphate salts in tissue without extraction and time-consuming chemical analysis. Crystalline phases in intact atherosclerotic plaques (ex vivo) can be quantified accurately by solid-state (13)C and (31)P MAS NMR spectroscopy. (+info)