Influence of a diet regimen on glucose homeostasis and serum lipid levels of male elite athletes.

Physical training affects carbohydrate metabolism and results in an increased insulin-stimulated glucose disposal. To investigate if carbohydrate and lipid metabolism would be affected by nutritional factors in optimally trained elite athletes, during a 1-year period we studies elite ice-hockey players on two Swedish top-performance teams. Players on one team were subjected to extensive dietary monitoring and intervention, whereas players on the second team continued their ordinary diet. Blood levels of insulin, C-peptide, glucose, hemoglobin A1C (HbA1c), lipids, and lipoproteins were measured repeatedly. Basal insulin levels and insulin resistance (IR) were significantly lower among athletes on both teams compared with a sedentary group, and muscle weight and body mass index were significantly higher. During the course of the study in the intervention group, insulin levels decreased (3.6 +/- 0.3 v 6.2 +/- 0.6 [mean +/- SEM], P <.05) in conjunction with a decreased relative fat energy content, but returned toward baseline levels when relative fat energy content increased. IR decreased in parallel (0.59 +/- 0.05 v l.12 +/- 0.12, P <.05) and followed a similar pattern, reverting toward baseline levels. Also, levels of HbA1c changed during dietary manipulation. No changes in these parameters were observed among the elite players from the team not participating in the diet regimen. In contrast to the parameters for glucose homeostasis, no significant changes were found in serum lipid or lipoprotein levels in either team during the course of the study. The results verify the presence of an improved carbohydrate metabolism in elite athletes. The observed changes in glycemic control and glucose homeostasis as a consequence of dietary modification demonstrate further that nutritional factors may affect carbohydrate metabolism also in well-trained athletes.

Comparison of the proportion of unconjugated to total serum cholic acid and the [14C]-xylose breath test in patients with suspected small intestinal bacterial overgrowth.

The proportion of unconjugated to total cholic acid in fasting serum and the 1-gram [14C]-xylose breath test were determined in 36 patients with suspected bacterial overgrowth of the small intestine. Twenty-two patients had an abnormal [14C]-xylose breath test, indicating bacterial overgrowth. The proportion of unconjugated to total cholic acid was significantly higher in the patients with an abnormal breath test compared with those displaying a normal breath test (47 +/- 5% vs 16 +/- 3%). A good correlation was obtained between the proportion of unconjugated to total cholic acid and the breath test (r = 0.63, n = 36). Provided the [14C]-xylose breath test is reliable as a test of bacterial overgrowth, determination of the proportion of unconjugated to total cholic acid in fasting serum had a sensitivity of 73% and a specificity of 94%. It is suggested that determination of the proportion of unconjugated to total cholic acid in peripheral venous blood may be useful as a simple screening test for detection of bacterial contamination of the upper small intestine provided the patients do not have bile acid malabsorption.

Endogenous anabolic and catabolic steroid hormones in male and female athletes during off season.

Peripheral serum hormone levels during the off season were analysed in 10 male and 10 female athletes, all belonging to the Swedish national teams in skiing and orienteering and in age matched sedentary controls (15 males, 13 females). No clinical signs of overuse strain were observed in any of the athletes. No significant differences in hormone variables were found between male athletes and controls. The female athletes had significantly higher levels of cortisol and significantly lower ratios between total testosterone and cortisol, between non-SHBG-bound testosterone and cortisol and between 4-androstene-3, 17-dione and cortisol than the sedentary controls. The increased levels of cortisol found in the female athletes probably reflect an adaptation to several years of hard training. A decrease of the free T/cortisol ratio has earlier been shown to indicate an overuse distress. One may speculate that the low androgen/cortisol ratios found in the female athletes in contrast to the males could indicate that the female athletes might need longer time to recover from hard exercise than male athletes, or could suggest an insufficient dietary intake.

Amino acid concentrations in cerebrospinal fluid and plasma in Alzheimer's disease and healthy control subjects.

Cerebrospinal fluid (CSF) and plasma levels of 18 amino acids were studied in 22 subjects with dementia of the Alzheimer type (DAT) and in 11 healthy volunteers with no clinical or family history of dementia. Significant decreases of plasma taurine and glutamate were seen in the DAT cases compared with the controls. The CSF concentrations of glycine, leucine and valine were also significantly reduced in the DAT cases. Furthermore, in the DAT cases significant decreases were observed in the ratio between CSF and plasma (CSF/P) levels for alanine, glutamine, glycine, phenylalanine and valine, when compared with controls. In the DAT group there were significant correlations between behaviour and CSF glutamine; memory and cognitive functions and CSF valine; copying ability and CSF glutamate. CSF/P ratios of glutamine and glutamate correlated with behaviour and copying performances, respectively. The results of this study provide further evidence for a disruption of amino acid metabolism in DAT.

Determination of 4-methylpyrazole in plasma using solid phase extraction and HPLC.

A rapid method for the determination of 4-methylpyrazole in plasma is described. Internal standard (3-methylpyrazole) is added to the plasma which is subsequently applied to a BondElut SCX column. After washing the column the 3- and 4-methylpyrazoles are eluted with a phosphate buffer and analyzed by isocratic reversed-phase high performance liquid chromatography with UV detection. The concentration of 4-methylpyrazole is calculated from the 4-methylpyrazole/3-methylpyrazole peak height ratio. The method is linear between 2.5 and 100 mumol/L with a within-day precision (CV) of 2.2% (n = 10) and a day-to-day precision of 2.8% (n = 30). The sensitivity is sufficient for analysis of plasma levels in the low micromolar range.

Effect of ursodeoxycholic acid treatment on intestinal absorption of triglycerides in man.

The aim of the present study was to evaluate whether treatment with ursodeoxycholic acid (UDCA) may affect the absorption of dietary fat in man. Fifteen healthy subjects volunteered for the study. They were treated with UDCA in a daily dose of 15 mg/kg body weight for 4 weeks. Before and during treatment fat absorption was measured with a 14C-triolein breath test. In addition, fasting serum bile acids were measured in 11 of the subjects. The maximum specific activity of 14CO2 was not significantly changed during the treatment period. However, the cumulative output of 14CO2 during a 6-h period was decreased by about 25% (p less than 0.03). Several subjects with decreased outputs also lost 1-2 kg of body weight during the study period. UDCA treatment raised the serum level of this bile acid from 0.18 +/- 0.11 mumol/l to 5.98 +/- 1.08 mumol/l. The concentrations of the other bile acids were not significantly changed. It is suggested that UDCA treatment may in some patients be associated with an impaired fat absorption. Whether this effect is of any clinical importance remains to be elucidated.

Effect of cephapirin on tubular reabsorption of amino acids, uric acid and beta 2-microglobulin in man.

Cephapirin, a beta-lactam antibiotic, was administered intravenously to five healthy subjects in a dose of 1 g. Renal clearances of cephapirin, beta 2-microglobulin, uric acid and amino acids were measured during the experiment and compared to timed control data, i.e. when no cephapirin was given. Renal clearance of cephapirin decreased when plasma concentrations declined. As protein binding of cephapirin is constant over a wide plasma concentration range, this finding may indicate that cephapirin is reabsorbed in the kidney by a saturable process. Renal clearance of endogenous amino acids, particularly those belonging to the basic group increased after cephapirin. There was no change in renal clearance of beta 2-microglobulin which excludes a general toxic effect on tubular reabsorption of endogenous substances caused by cephapirin. A flow dependent increase of uric acid clearance was observed. Our results are suggestive of a competition between cephapirin and amino acids for some common step in the tubular reabsorption process.

14C-triolein breath test as a rapid and convenient screening test for fat malabsorption.

The 14C-triolein breath test was evaluated as a screening test for fat malabsorption in 50 consecutive patients. After the ingestion of a 30-g fat meal containing 5 microCi 14C-triolein, the breath excretion of 14CO2 was measured at hourly intervals for 6 h and compared with a 3-day faecal excretion of fat. Nineteen patients had steatorrhoea and 31 patients normal fat excretion. The maximum specific activity of CO2 in the breath provided the best means of distinguishing between the two groups, with no false-negative values and nine false-positive values (29%). Our findings confirm that the 14C-triolein breath test is sensitive and has sufficient specificity for screening fat malabsorption, especially among outpatients. If a normal 14C-triolein breath test is obtained, it seems unnecessary to perform measurements of excretion of faecal fat.