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Biomedical subjects

P Stehle

Publications and source records attributed to P Stehle.

At least 37 records · Page 2Linked to original sources
PubMed2000

Physiologic fluctuations of serum estradiol levels influence biochemical markers of bone resorption in young women.

We investigated the effect of physiologic variations in sex hormone levels during the menstrual cycle on biomarkers of bone turnover. Blood and 24-h and fasting urine samples were obtained in nine women (age, 25.1+/-3.0 yr) with regular menstrual cycles during the early follicular period (t1), 3 days before ovulation (t2), 3 days after ovulation (t3), at the midluteal period (t4) and again during the early follicular period of the next cycle (t5). All subjects had a calcium intake covering current dietary recommendations (above 1,000 mg/day, standardized food record). Serum calcium, phosphorus, calcitriol, 24-h and 2-h fasting urinary calcium, and phosphorus excretion remained constant during the menstrual cycle. Serum 25-hydroxyvitamin D3 levels decreased slightly from the beginning until the end of the study (P<0.05), indicating low cutaneous vitamin D synthesis during wintertime. The serum levels of sex hormones showed typical monthly variations, with the lowest estradiol (E2) levels at t1 and t5. Fasting 2-h pyridinoline (Pyd) concentrations (a marker of bone resorption) fell from t1 to t3 and rose again at t5 (P<0.01). Similar variations were observed for the resorption marker deoxypyridinoline (Dpd; P<0.05). The amplitude of the two biomarkers was 32% and 33%, respectively. The serum levels of the carboxyterminal propeptide of type I collagen (a marker of bone formation) showed an inverse cyclic pattern, as compared with the pyridinium cross-links. Low concentrations were observed at t1; a rise occurred until t3 and was followed by a decrease until t5 (P<0.05). A similar cyclic pattern was observed for serum PTH levels, with the highest concentrations at t3 (P<0.05). Dpd and Pyd values were significantly correlated with serum E2 levels (r = 0.52; P<0.0001 and r = 0.50; P<0.001, respectively). Neither progesterone nor LH nor FSH was correlated with Pyd or Dpd levels. The data suggest that normal menstrual cycling in young women is associated with monthly fluctuations in bone turnover. This physiological effect of the menstrual cycle is most probably related to variations in serum E2 concentrations.

Adult↗
PubMed1999

Calcium metabolism in microgravity.

Unloading of weight bearing bones as induced by microgravity or immobilization has significant impacts on the calcium and bone metabolism and is the most likely cause for space osteoporosis. During a 4.5 to 6 month stay in space most of the astronauts develop a reduction in bone mineral density in spine, femoral neck, trochanter, and pelvis of 1%-1.6% measured by Dual Energy X-ray Absorption (DEXA). Dependent on the mission length and the individual turnover rates of the astronauts it can even reach individual losses of up to 14% in the femoral neck. Osteoporosis itself is defined as the deterioration of bone tissue leading to enhanced bone fragility and to a consequent increase in fracture risk. Thinking of long-term missions to Mars or interplanetary missions for years, space osteoporosis is one of the major concerns for manned spaceflight. However, decrease in bone density can be initiated differently. It either can be caused by increases in bone formation and bone resorption resulting in a net bone loss, as obtained in fast looser postmenopausal osteoporosis. On the other hand decrease in bone formation and increase in bone resorption also leads to bone losses as obtained in slow looser postmenopausal osteoporosis or in Anorexia Nervosa patients. Biomarkers of bone turnover measured during several missions indicated that the pattern of space osteoporosis is very similar to the pattern of Anorexia Nervosa patients or slow looser postmenopausal osteoporosis. However, beside unloading, other risk factors for space osteoporosis exist such as stress, nutrition, fluid shifts, dehydration and bone perfusion. Especially nutritional factors may contribute considerably to the development of osteoporosis. From earthbound studies it is known that calcium supplementation in women and men can prevent bone loss of 1% bone per year. Based on these results we studied the calcium intake during several European missions and performed an experiment during the German MIR 97 mission where we investigated the effects of high calcium intake (>1000 mg/d) and vitamin D supplementation (650 IU/d) on the calcium and bone metabolism during 21 days in microgravity. In the MIR 97 mission high calcium intake and vitamin D supplementation led to high ionized calcium levels and a marked decrease in calcitriol levels together with decreased bone formation and increased bone resorption markers. Our conclusion from the MIR 97 mission is that an adequate calcium intake and vitamin D supplementation during space missions is mandatory but, in contrast to terrestrial conditions, does not efficiently counteract the development of space osteoporosis.

Bone and Bones↗
PubMed1999

Vitamin status of elderly people in Germany.

In the last decade several attempts (Nationale Verzehrsstudie, NVS; Verbundstudie Ernährungserhebung und Risikofaktoren-Analytik, VERA: Bethanien-Ernährungsstudie, BEST) have been made to assess the nutritional status of the elderly in Germany. A careful evaluation of those data describing the vitamin status clearly indicate that healthy older people are not at higher risk for vitamin deficiency compared to younger adults. The results of the NVS showed that, except for folic acid, mean intake of all vitamins exceeded 80% of the current recommendations. Only 5% of blood vitamin concentrations analyzed in a subpopulation (VERA-Study) were founded to be below the physiological range. Only the incidence of low cobalamin values increased with age, presumably due to gastrointestinal problems (atrophic gastritis). In contrast, geriatric patients showed markedly lower vitamin blood concentrations compared to healthy subjects of the same age (BEST-Study). This might be explained by physical and mental deterioration, handicaps, chronic diseases and multiple chronic drug use. Underrepresentation of very old people, lack of reliable reference values for biomarkers and uncertainties in data collection may have contributed to misinterpretations. Representative studies are needed to objectively assess the nutritional status of the elderly population in Germany.

Aged↗
PubMed1999

Determination of glutamine in muscle protein facilitates accurate assessment of proteolysis and de novo synthesis-derived endogenous glutamine production.

BACKGROUND: Results of tracer studies indicate that skeletal muscle contributes to approximately 70% of overall glutamine production in healthy adults; the contribution of de novo synthesis being estimated at approximately 60%. However, measurement of the de novo synthesis rate in muscle tissue requires knowledge of the appearance rate of glutamine in plasma and the quantity of glutamine derived from intracellular proteolysis. Thus, the content of glutamine in muscle protein is a prerequisite for an accurate calculation. OBJECTIVE: The objective of the study was to measure glutamine in muscle protein. DESIGN: Muscle specimens (open biopsies) were obtained from humans (10 men and 4 women), rats (n = 4), cows (n = 4), and pigs (n = 4). Glutamine was assessed via prehydrolysis derivatization, rapid microwave-enhanced acid hydrolysis, and 5-dimethylaminonaphthalene-1-sulfonyl chloride (dansyl chloride) reversed-phase HPLC, and expressed per mg alkali-soluble protein (ASP) and DNA. RESULTS: Glutamine concentrations in muscle cell protein of various species ranged from 41 to 49 microg/mg ASP; the differences were not species related. The combined means (+/-SDs) for the 4 species were 43.6 +/- 4.9 microg/mg ASP and 11.9 +/- 2.0 mg/mg DNA, respectively. In humans, there was no apparent influence of age, sex, or BMI. CONCLUSIONS: Direct and specific measurements of glutamine in intact muscle protein were 50% lower than assumed previously. We used data compiled from earlier studies to recalculate the contributions of proteolysis and de novo synthesis to the endogenous production of glutamine in selected age groups of healthy humans; these contributions remained remarkably constant at approximately 13% and approximately 87%, respectively.

Adolescent↗
PubMed1999

Wheat bran supplementation does not affect biochemical markers of bone turnover in young adult women with recommended calcium intake.

We investigated the effect of wheat bran on biochemical indicators of Ca and bone metabolism in nineteen healthy women, aged 25.5 (SE 0.9) years. Subjects received six wheat bran biscuits or six white flour biscuits per day for a period of 4 weeks (crossover). Wheat bran consumption increased fibre intake from 17.7 (SE 1.3) to 29.6 (SE 1.3) g/d (7 d food record) and enhanced P intake from 1225 (SE 59) mg/d to 1663 (SE 65) mg/d; P < 0.001. Mean daily Ca intake during wheat bran consumption (1110 (SE 82) mg/d) significantly (P = 0.008) exceeded Ca ingestion during the white flour period (955 (SE 67) mg/d). Wheat bran increased the number of defecations per week from 7.9 (SE 0.8) to 12.2 (SE 1.4) (P = 0.0018). Urinary Ca excretion over 24 h significantly (P = 0.021) decreased from 473 (SE 53) mumol/mmol creatinine (control period) to 339 (SE 37) mumol/mmol creatinine (wheat bran period). Serum 25-hydroxyvitamin D, 2 h fasting urinary Ca/creatinine excretions and 24 h urinary P excretion remained constant. No differences in serum levels of carboxy-terminal propeptide of type I procollagen (biomarker of bone formation) or in 2 h fasting urinary hydroxyproline/creatinine excretions (biomarker of bone resorption) were observed at the end of the two cycles of dietary supplementation. We conclude that a high fibre intake of approximately 30 g/d has no significant adverse effects on bone turnover in subjects with Ca intakes above 1000 mg/d and that the reduction in 24 h urinary Ca excretion is most probably the result of an adaptation process, induced by a decrease in net absorbed Ca.

Adult↗
PubMed1998

Relation of fibre intake to HbA1c and the prevalence of severe ketoacidosis and severe hypoglycaemia. EURODIAB IDDM Complications Study Group.

The effect of dietary fibre intake on glycaemic control is still controversial. This study analysed the intake of natural dietary fibre in patients with Type I diabetes mellitus enrolled in the EURODIAB IDDM Complications Study to determine any associations with HbA1c levels and with the prevalence of severe ketoacidosis or severe hypoglycaemia. Dietary intake was assessed by a 3-day dietary record. The relation between intake of fibre (total, soluble and insoluble) and HbA1c was examined in 2065 people with Type I diabetes. Associations with severe ketoacidosis (requiring admission to hospital) and severe hypoglycaemia (requiring the help of another person) were analysed in 2687 people with Type I diabetes. Total fibre intake (g/day) was inversely related to HbA1c (p = 0.02), independently of carbohydrate intake, total energy intake and other factors regarding lifestyle and diabetes management. Severe ketoacidosis risk fell significantly with higher fibre intake (p = 0.002), with an adjusted odds ratio of 0.48 (95 % confidence interval 0.27 to 0.84) in the highest quartile ( > or = 23.0 g fibre/day) compared with the lowest quartile ( < or = 13.7 g fibre/day). The occurrence of severe hypoglycaemia was not related to fibre intake. Beneficial effects of fibre on HbA1c and the risk of severe ketoacidosis were particularly pronounced in patients from southern European centres. This study shows that higher fibre intake is independently related to a reduction in HbA1c levels in European people with Type I diabetes. Furthermore, increased fibre intake may reduce the risk of severe ketoacidosis. These beneficial effects were already observed for fibre intake within the range commonly consumed by people with Type I diabetes.

Adolescent↗
PubMed1998

Seasonal variations in vitamin D status and calcium absorption do not influence bone turnover in young women.

OBJECTIVE: To evaluate the effect of seasonal variations in UV B-exposure on calcium absorption and bone turnover in young women with the overall goal to assess the potential benefit of a vitamin D supplementation during wintertime. DESIGN: Cross-sectional study. SETTING: Area of Bonn, Germany (51 degrees N). SUBJECTS: Thirty-eight women (24.5+/-0.5 y) studied in winter and 38 females of the same age (24.7+/-0.4 y) studied in summer. RESULTS: As estimated by a 4 d food record, both groups had similar dietary calcium and phosphorus intakes (> 1200 mg/d, respectively) covering actual recommendations. Significant reductions in serum concentrations of 25-hydroxyvitamin D (25OHD) and calcitriol, fractional calcium absorption (Fc220, measured by means of a stable strontium test), 24h urinary calcium and 24h urinary phosphorus excretion were observed during wintertime. 25OHD but not calcitriol was correlated with Fc220 values and with 24h urinary phosphorus excretion. Moreover, Fc220 was related to 24 h urinary calcium excretion. Fasting 2 h-urinary deoxypyridinoline concentrations (biomarker of bone resorption) and serum levels of carboxyterminal propeptide of type I procollagen (biomarker of bone formation) showed no differences between summer and winter. CONCLUSIONS: Our data indicate a decrease in intestinal calcium and phosphorus absorption during wintertime, most likely because of a reduction in serum 25OHD levels. Since bone turnover was not affected by the seasonal differences in mineral metabolism, there is no objective for young women with high calcium intake to supplement vitamin D during wintertime.

Adult↗
PubMed1998

Total parenteral nutrition with glutamine dipeptide after major abdominal surgery: a randomized, double-blind, controlled study.

OBJECTIVE: To assess the efficacy of glutamine (Gln) dipeptide-enriched total parenteral nutrition (TPN) on selected metabolic, immunologic, and clinical variables in surgical patients. SUMMARY BACKGROUND DATA: Depletion of Gln stores might lead to severe clinical complications. Recent studies indicate that the parenteral provision of Gln or Gln-containing dipeptides improves nitrogen balance, maintains the intracellular Gln pool, preserves intestinal permeability and absorption, and shortens hospital stay. METHODS: Twenty-eight patients (age range, 42-86 years, mean 68 years) undergoing elective abdominal surgery were allocated, after randomization, to two groups to receive isonitrogenous (0.24 g nitrogen kg(-1) day(-1)) and isoenergetic (29 kcal/122 kJ kg(-1) day(-1)) TPN over 5 days. Controls received 1.5 g of amino acids kg(-1) day(-1), and the test group received 1.2 g of amino acids and 0.3 g of L-alanyl-L-glutamine (Ala-Gln) kg(-1) day(-1). Venous heparinized blood samples were obtained before surgery and on days 1, 3, and 6 after surgery for routine clinical chemistry and for the measurement of plasma free amino acids. Lymphocytes were counted and the generation of cysteinyl-leukotrienes from polymorphonuclear neutrophil granulocytes was analyzed before surgery and on days 1 and 6 after surgery. Nitrogen balances were calculated postoperatively on days 2, 3, 4, and 5. RESULTS: No side effects or complaints were noted. Patients receiving Gln dipeptide revealed improved nitrogen balances (cumulative balance over 5 days: -7.9 +/- 3.6 vs. -23.0 +/- 2.6 g nitrogen), improved lymphocyte recovery on day 6 (2.41 +/- 0.27 vs. 1.52 +/- 0.17 lymphocytes/nL) and improved generation of cysteinyl-leukotrienes from polymorphonuclear neutrophil granulocytes (25.7 +/- 4.89 vs. 5.03 +/- 3.11 ng/mL). Postoperative hospital stay was 6.2 days shorter in the dipeptide-supplemented group. CONCLUSION: We confirm the beneficial effects of Gln dipeptide-supplemented TPN on nitrogen economy, maintenance of plasma Gln concentration, lymphocyte recovery, cysteinyl-leukotriene generation, and shortened hospital stay in surgical patients.

Adult↗
PubMed1998

Chemoprevention--a novel approach in dietetics.

Chemoprotective potential of naturally occurring phytochemicals in food is a major area of scientific interest. Results acquired from epidemiologic studies suggest a reduced risk of degenerative diseases with high phytochemical consumption. Bioavailability of phytochemicals is a critical issue, though their significant absorption has been demonstrated. Phytochemicals possess an array of biochemical and pharmacological qualities like antioxidative, anticarcinogenic, antimicrobial, cholesterol-lowering and antithrombotic activities.

Anticarcinogenic Agents↗
PubMed1998

Assessment of lead exposure in schoolchildren from Jakarta.

Children attending schools in urban areas with high traffic density are a high risk group for lead poisoning. We assessed the magnitude of lead exposure in schoolchildren from Jakarta by analyzing blood lead concentrations and biomarkers of heme biosynthesis. A total of 131 children from four public elementary schools in Jakarta (two in the southern district and two in the central district) were enrolled in the study. To evaluate lead pollution in each area, soil samples and tap water were collected. The mean blood lead concentration was higher in the central district than in the southern district (8.3 +/- 2.8 vs. 6.9 +/- 3.5 microg/100 ml; p<0.05); 26.7% of the children had lead levels greater than 10 microg/100 ml. In 24% of the children, zinc protoporphyrin concentrations were over 70 micromol/mol hemoglobin; in 17% of the samples, hemoglobin was less than 11 g/100 ml. All other values were within the physiological range. Blood lead concentration and hematological biomarkers were not correlated. Analyses of tap water revealed lead values under 0. 01 mg/l; lead contamination of soil ranged from 77 to 223 ppm. Our data indicate that Indonesian children living in urban areas are at increased risk for blood lead levels above the actual acceptable limit. Activities to reduce pollution (e.g., reduction of lead in gasoline) and continuous monitoring of lead exposure are strongly recommended.

Child↗
PubMed1997

Simultaneous measurements of free amino acid patterns of plasma, muscle and erythrocytes in healthy human subjects.

Muscle biopsy and blood samples were simultaneously collected from 27 healthy subjects for determination of free amino acid (AA) in plasma, muscle and erythrocytes (RBC) by reverse-phase high performance liquid chromatography and related their concentrations to deoxyribonucleic acid (DNA), muscle alkali-soluble protein, s-albumin and s-total protein. Extra- and intracellular water distribution in muscle was estimated with a modified chloride method. The majority of the AA showed higher concentration in intracellular water (ICW) than in plasma; exceptions were the concentrations of branched-chain amino acids (BCAA), phenylalanine and tyrosine exhibiting muscle/plasma and RBC/plasma ratios of 1.0-1.4. Muscle arginine and lysine as well as RBC citrulline showed higher concentrations in younger female subjects when compared to males whereas in the three compartments all other AA were present in higher concentrations in the males than in the female subjects. The levels of valine and asparagine in muscle as well as serine, ornithine, methionine and BCAA in RBC were higher in the younger than in the elderly subjects. On the other hand, muscle arginine and plasma histidine levels were higher in the elderly than in the younger subjects. There were significant positive correlations between plasma, muscle and RBC AA concentrations for a large number of AA, specially BCAA. The RBC BCAA concentrations correlated most strongly with the ratio of alkali-soluble protein to DNA in skeletal muscle (P < 0.002) and were also significantly correlated to serum albumin and total proteins. The results presented here are proposed to be used as reference data for simultaneously comparing the AA profile in muscle, plasma and RBC in various disease conditions.

Journal Article↗
PubMed1997

Free amino-acid levels simultaneously collected in plasma, muscle, and erythrocytes of uraemic patients.

BACKGROUND: Disturbances in amino acid (AA) metabolism in uraemia have mainly been reported to occur in plasma and muscle. The erythrocytes (RBC) constitute a large proportion of the free AA in blood and may play an important role in the interogan transport of AA. This report presents the first data on AA levels obtained simultaneously from three different compartments in uraemic patients. METHODS: Muscle biopsy and blood samples were obtained from 38 haemodialysis (HD), 22 continuous peritoneal dialysis (CPD) and 10 end-stage renal failure patients for determination of free amino acids by reversed-phase HPLC. The results are compared to data obtained from 27 healthy subjects under the same conditions. RESULTS: For a number of non-essential AA (alanine, glycine, asparagine, arginine) and for lysine, elevated concentrations were present simultaneously in RBC and in muscle but not in plasma. On the other hand, low concentration of some essential AA (leucine, valine, phenylalanine, tyrosine) were observed in RBC and in plasma, while the concentrations in muscle were normal. Most of the non-essential AA (NEAA), especially taurine and glutamine, had much higher muscle/plasma gradients than RBC/plasma gradients, although an accumulation in RBC of glycine, serine, arginine, asparagine, ornithine, glutamate and taurine was observed. Most of the essential AA (EAA) showed higher muscle/plasma gradients, whereas the RBC/ plasma gradients were approximately 1.0. CONCLUSION: Our findings are in agreement with studies that have shown that RBC and plasma play independent and opposing roles in AA interorgan transport. The results indicate that there are several AA abnormalities in all three compartments in uraemic patients. They also suggest that there may be some specific common changes of selected transport systems for both RBC and muscle in uraemia. Determination of AA in RBC should be considered when undertaking metabolic and clinical studies of AA disturbances.

Adult↗