Determination of homocysteine in plasma by liquid chromatography with fluorescence detection.

A liquid chromatographic (LC) method to assay homocysteine in plasma at micro-molar levels is described. The procedure consists of protein precipitation with trichloroacetic acid and a centrifugation step. The supernatant is then derivatized with a thiol-specific fluorochromophore and LC assayed with fluorescence detection at 385 nm excitation and 515 nm detection. LC analysis is performed by isocratic elution using an acetate buffer (0.05 M, pH 4) as a mobile phase and an alphaBond column. Recoveries based on a five-point standard curve calculation ranged from 96 to 112%. The limits of detection and quantification reached were 0.8 and 1.57 micromol/L, respectively.

Effect of endurance training on postexercise parathyroid hormone levels in elderly men.

The present study was designed to evaluate the effects of 6-wk endurance training on serum parathyroid hormone (PTH) levels and on other parameters at rest and after a maximal exercise test (MET) in 24 55- to 73-yr-old men. Before training, MET was found to induce a significant increase in PTH levels as compared with resting values. This MET-induced rise in PTH was accompanied by enhanced total calcium, phosphate, alkaline phosphatase (ALP), osteocalcin, and albumin levels. After the training period (75-80% maximal heart rate, 1 h.d-1, 4 d.wk-1), the changes induced by MET in calcium, phosphate, ALP, and albumin levels followed the same pattern as before training. Conversely, the MET-induced increase in PTH levels was found markedly more pronounced after training than in untrained conditions (+21.9% vs +11.1%, respectively, P < 0.05). Furthermore, lower values of osteocalcin were found after training as compared with pretraining values, both at rest and after maximal exercise. These findings indicate that 6 wk of endurance training enhanced exercise-related release of PTH and reduced osteocalcin levels in elderly men. This might be of importance regarding bone status in the elderly, as exercise is proposed as a preventive measure against osteopenia.

Influence of simulated altitude on the performance of five blood glucose meters.

OBJECTIVE: To determine the reliability of five blood glucose meters (BGMs) at various simulated altitudes using a hypobaric chamber. RESEARCH DESIGN AND METHODS: Blood glucose levels (ranged from 1.5 to 26.3 mmol/l, according to the reference method) were measured in 18 venous blood samples by each BGM at 200, 1,000, and every 500 m up to 4,000 m in a hypobaric chamber, where temperature and humidity were held constant. RESULTS: Four BGMs underestimated and one overestimated blood glucose concentration while barometric pressure decreased. The average percent error varied in relation to simulated altitude from 0.26 +/- 4.8% (SD) at 200 m to -28.9 +/- 4.5% at 4,000 m (Glucometer 3; P < 0.05), from 28.4 +/- 5.7 to 49.3 +/- 5.9% (Accu-Chek Easy; P < 0.05), from -10.5 +/- 2.6 to 19.8 +/- 4.3% (Tracer, P < 0.05), from -5.5 +/- 2.6 to -11.2 +/- 3.0% (Reflolux; NS), and from 17.8 +/- 4.3 to 14.8 +/- 3.6% (One Touch; NS). The most accurate seemed to be the Reflolux, except for high blood glucose levels at simulated high altitudes. The One Touch II showed a good agreement, whatever the barometric pressure and the range of blood glucose concentrations. The highest underestimation was seen with the Glucometer 3. CONCLUSIONS: Except for the Accu-Chek Easy, low barometric pressure underestimated the BGM results in comparison with measurements taken at simulated low altitudes. The lack of accuracy and consistency of performance > 2,000 m should be known by diabetic patients practicing sports activities, such as trekking or skiing at high altitudes.

Branched-chain amino acid supplementation during repeated prolonged skiing exercises at altitude.

This study was conducted to test the hypothesis that a branched-chain amino acid (BCAA) supplementation would minimize changes in body composition and alterations in plasma amino acid profile induced by prolonged exercises at altitude. Twenty-four highly trained subjects participated in six successive sessions of ski mountaineering (6-8 hr duration, altitude 2,500-4,100 m). Twelve subjects took a dietary supplement of BCAA (BCAA group) and 12 took a dietary supplement that was 98% carbohydrate (C group). Body weight decreased in C subjects (-2.1%, p < .01), while the body weight loss recorded in the BCAA group was not statistically significant (-1.2%, NS). Changes in body composition that resulted from repeated skiing exercise at altitude were not significantly minimized by BCAA administration. Peak power output recorded during an incremental bicycle exercise decreased in C subjects but did not change significantly in BCAA subjects. Results of this study demonstrate that neither changes in body composition related to the ski mountaineering program nor muscular performance during isometric contraction was significantly affected by BCAA administration.

Changes in dietary protein intake fail to prevent decrease in muscle growth induced by severe hypoxia in rats.

Muscle growth, fiber size, muscle and liver glycogen, plasma hormones, and muscle glutamine concentration were evaluated in rats chronically exposed (26 days) to a simulated hypobaric altitude (HA; 6,000 m) and fed diets of varying protein concentrations (10, 20, or 40 g protein/100 g of dry matter; LP, MP, and HP, respectively). Values were compared with those measured in animals maintained under normobaric conditions and either fed ad libitum (SL groups) or pair fed equivalent quantities of food consumed by HA animals (PF groups). There was marked anorexia in response to HA exposure for all protein diets (P < 0.001). A specific effect of hypoxia on the decrease in muscle growth has been identified by comparison of the values of the muscle weight-to-body weight ratio between HA and PF groups (P < 0.05 for all dietary protein levels). Plasma insulin concentrations were lower in HA than in SL and PF rats (P < 0.05). Liver glycogen was significantly decreased by exposure to HA (P < 0.001) and high dietary protein content (P < 0.005). Hypoxia per se and decreased food intake had additive effects on soleus muscle glycogen concentrations. An increase in muscle glutamine was observed in rats fed the LP diet in comparison with the MP diet, especially in SL and PF groups (P < 0.05). These results clearly demonstrate that 1) hypobaric hypoxia per se decreases growth rate in rats and 2) increasing the dietary protein intakes in rat had no effect on the depression of muscle growth related to high altitude but had deleterious effects on glycogen deposition in liver and fast muscle.

[Indications and results apropos of 290 endonasal ethmoidectomies]. / Indications et résultats à propos de 290 ethmoïdectomies endonasales.

An intranasal ethmoidectomy prospective study was carried out from 1985 to 1991 on 152 patients and 290 ethmoidectomies. This surgery is intended for patients who have been treated often for nasal polyps, chronic ethmoiditis and recurrent sinus barotrauma. A discrepancy was observed between patients satisfaction (82%) and clinical symptoms, given that results remain good in 75% of the cases three years afterwards but only in 60 cases after five years. There is a recurrence of nasal polyps in 36% of the cases.