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Biomedical subjects

D Nachtigall

Publications and source records attributed to D Nachtigall.

9 recordsLinked to original sources
PubMed2001

Effects of a short-term vitamin D(3) and calcium supplementation on blood pressure and parathyroid hormone levels in elderly women.

Calcium supplementation is effective in reducing blood pressure in various states of hypertension, including pregnancy-induced hypertension and preeclampsia. In addition, calcitropic hormones are associated with blood pressure. The hypothesis is that short-term therapy with calcium and vitamin D(3) may improve blood pressure as well as secondary hyperparathyroidism more effectively than calcium monotherapy. The effects of 8 weeks of supplementation with vitamin D(3) (cholecalciferol) and calcium on blood pressure and biochemical measures of bone metabolism were studied. The sample consisted of 148 women (mean +/- SD age, 74 +/- 1 yr) with a 25-hydroxycholecalciferol (25OHD(3)) level below 50 nmol/L. They received either 1200 mg calcium plus 800 IU vitamin D(3) or 1200 mg calcium/day. We measured intact PTH, 25OHD(3), 1,25-dihydroxyvitamin D(3), blood pressure, and heart rate before and after treatment. Compared with calcium, supplementation with vitamin D(3) and calcium resulted in an increase in serum 25OHD(3) of 72% (P < 0.01), a decrease in serum PTH of 17% (P = 0.04), a decrease in systolic blood pressure (SBP) of 9.3% (P = 0.02), and a decrease in heart rate of 5.4% (P = 0.02). Sixty subjects (81%) in the vitamin D(3) and calcium group compared with 35 (47%) subjects in the calcium group showed a decrease in SBP of 5 mm Hg or more (P = 0.04). No statistically significant difference was observed in the diastolic blood pressures of the calcium-treated and calcium- plus vitamin D(3)-treated groups (P = 0.10). Pearson coefficients of correlation between the change in PTH and the change in SBP were 0.49 (P < 0.01) for the vitamin D(3) plus calcium group and 0.23 (P < 0.01) for the calcium group. A short-term supplementation with vitamin D(3) and calcium is more effective in reducing SBP than calcium alone. Inadequate vitamin D(3) and calcium intake could play a contributory role in the pathogenesis and progression of hypertension and cardiovascular disease in elderly women.

Aged↗
PubMed2000

Effects of a short-term vitamin D and calcium supplementation on body sway and secondary hyperparathyroidism in elderly women.

Long-term vitamin D and calcium supplementation is effective in reducing nonvertebral fractures in elderly people. Increased bone fragility caused by secondary hyperparathyroidism (sHPT) and impaired balance are known risk factors for hip fractures. The hypothesis is that short-term therapy with calcium and vitamin D may improve body sway as well as sHPT more effectively than calcium monotherapy. The effects of 8 weeks of supplementation with vitamin D (cholecalciferol) and calcium on body sway and biochemical measures of bone metabolism were measured. The sample consisted of 148 women (mean [+/-SD] age, 74 +/- 1 years) with a 25-hydroxycholecalciferol level below 50 nmol/liter. They received either 1200 mg of calcium plus 800 IU of vitamin D or 1200 mg of calcium per day. We measured intact parathyroid hormone (PTH), markers of bone turnover, and body sway before and after treatment. Falls and fractures among the participants were followed over a 1-year period. Compared with calcium mono, supplementation with vitamin D and calcium resulted in an increase in serum 25-hydroxyvitamin D of 72% (p < 0.0001), a decrease in the serum PTH of 18% ( p = 0.0432), and a decrease in body sway of 9% (p = 0.0435). The mean number of falls per subject during a 1-year follow-up period was 0.45 for the calcium mono group and 0.24 for the calcium and vitamin D group (p = 0.0346). Short-term supplementation with vitamin D and calcium improves sHPT and body sway and therefore may prevent falls and subsequent nonvertebral fractures in elderly women.

Aged↗
PubMed1999

Bioavailability of fine dispersed platinum as emitted from automotive catalytic converters: a model study.

Automobile exhaust catalytic converters emit fine dispersed elemental platinum, Pt (0), in the nanometer range coated on larger aluminium oxide carrier particles. A pre-requisite for a potential systemic toxic effect of the emitted platinum is its bioavailability which was investigated using laboratory animals. To this end, a model substance was synthesised which consisted of aluminium oxide particles < or = 5 microns onto which platinum particles > or = 4 nm were deposited by a calcination process. These particles closely resemble those emitted from automobile exhaust converters. This model substance was applied to female Lewis rats in two doses by intratracheal instillation; the animals were killed after 1, 7, 28 and 90 days. In addition, the model substance was also applied during a 90-day inhalation study. After microwave digestion of the tissues, the platinum was determined in all organs and body fluids by inductively coupled plasma/mass spectrometry (ICP/MS). Platinum was found in the blood, urine and faeces and all important organs (liver, spleen, kidneys, adrenals, stomach, femur). Based on the platinum content determined in the body fluids and all organs (except the lung and the faeces) it was calculated that up to 16% of the platinum was retained in the lung 1 day after intratracheal instillation and up to 30% of the fine dispersed platinum deposited on an average during 90 days inhalation in the lung was bioavailable. Using size exclusion chromatography (SEC) in combination with ICP/MS, it was shown that > or = 90% of the bioavailable platinum was bound to high molecular weight compounds (approximately 80-800 kDa), most likely proteins.

Administration, Inhalation↗
PubMed1998

Bioavailability of platinum emitted from automobile exhaust.

A model substance was used which is similar in respect to platinum content of exhaust particles emitted from a three-way-catalytic converter equipped engine. The bioavailability of platinum from such exhaust particles and the kind of platinum species formed in vivo were assessed. An in vitro solubility test showed a solubility of approximately 10 percent of platinum content of the model substance in physiological sodium chloride solution. Two short-term animal studies (8 days) were performed. In all examined rat tissues and body fluids platinum could be detected. In addition, the contribution of the overall bioavailability caused by swallowing a certain amount of the intratracheally applied platinum was evaluated by oral application. It was very low. An analytical method was developed to determine platinum species. Synthetic samples (matrix with a platinum standard solution) were analysed. In rat bronchoalveolar lavage spiked with a platinum standard solution only low molecular complexed platinum was found whereas in rat blood plasma all platinum was bound to proteins. In ongoing studies, the model substance is being tested in a three month rat inhalation study.

Animals↗
PubMed1998

Iron supplementation in athletes. Current recommendations.

There is still debate in the literature on whether or not endurance athletes tend to have low iron stores. In this article, we propose that endurance athletes really are at risk of becoming iron deficient due to an imbalance between absorption of dietary iron and exercise-induced iron loss. The purpose of this article is to present a critical review of the literature on iron supplementation in sport. The effect of iron deficiency on performance, its diagnosis and suggestions for treatment are also discussed. Studies of the nutritional status of athletes in various disciplines have shown that male, but not female, athletes clearly achieve the recommended dietary intake of iron (10 to 15 mg/day). This reflects the situation in the general population, with menstruating women being the main risk group for mild iron deficiency, even in developed countries. Whereas the benefit of iron supplementation in athletes with iron deficiency anaemia is well established, this is apparently not true for non-anaemic athletes who have exhausted iron stores alone (prelatent iron deficiency); most of the studies in the literature show no significant changes due to supplementation in the physical capacity of athletes with prelatent iron deficiency. However, the treatment protocols used in some of these studies do not meet the general recommendations for the optimal clinical management of iron deficiency, that is, with respect to adequate daily dosage, mode of administration and treatment period. For future studies, we recommend a prolonged treatment period (> or = 3 months) with standardised conditions of administration (use of a pharmaceutical iron preparation with known high bioavailability and a dosage of ferrous (Fe++) iron 100 mg/day, taken on an empty stomach). Currently, decisions regarding iron supplementation are best made on the basis of taking care of individual athletes. We believe that there are sufficient arguments to support controlled iron supplementation in all athletes with low serum ferritin levels. Firstly, the development of iron deficiency is prevented. Secondly, the nonspecific upregulation of intestinal metal ion absorption is reverted to normal, thus limiting the hyperabsorption of potentially toxic lead and cadmium even in individuals with mild iron deficiency.

Adult↗
PubMed1996

Platinum solubility of a substance designed as a model for emissions of automobile catalytic converters.

Automobile catalytic converters emit nanocrystalline platinum attached to alumina particles. For investigations about the bioavailability of Pt from these particles a model substance with approx. 5% Pt on alumina has been prepared and characterized by physical methods (ESCA, XRD, TEM, DTA, TG). Measuring the platinum solubility of these samples in different solvents revealed high amounts that can be explained assuming a corrosion process. The portion of soluble platinum is dependent on the particle size distribution. For a comparative study platinum black has been used. In general the platinum determination has been carried out by electrothermal atomic absorption spectrometry (ET-AAS). The comparison of ET-AAS results with determinations by adsorptive voltammetry (formazone method) allowed to distinguish between elemental and ionic platinum; in solution samples only ionic platinum has been present. UV spectra of extracts have been used for the semi-quantitative platinum speciation in solutions.

Journal Article↗
PubMed1996

Iron deficiency in distance runners. A reinvestigation using Fe-labelling and non-invasive liver iron quantification.

In a group of male distance runners, 23 out of 45 athletes showed decreased serum ferritin values (< 35 micrograms). The high prevalence of a typical iron deficiency in runners was confirmed in a subgroup of eight athletes in which the iron metabolism was studied in detail using radio-iron labelling and liver iron quantification. Most of these athletes showed an up-regulated 59Fe absorption and a decreased liver iron concentration as compared to a control group. 59Fe activity in collected samples of stool, urine or sweat was measured sensitively using a shielded high-pure germanium spectrometer. In periods without running, a faecal excretion of 59Fe equivalent to 1.5 ml blood loss/d was observed, which represents the normal iron excretion. Under intensive training or racing conditions, a significant increase up to 4.9-6.6 ml blood loss/day was observed, whereas excretion of 59Fe in urine or sweat was negligible. Thus, gastrointestinal blood loss was the main reason for the slightly negative iron balance in the runners. This confirms earlier studies in the literature using qualitative blood stool testing. A treatment with 100 mg ferrous iron/day for 3 months significantly increased the values for serum ferritin (from 34 +/- 11 to 54 +/- 18 micrograms/l) and liver iron (from 105 +/- 42 to 227 +/- 67 micrograms/g liver).

Adult↗