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Biomedical subjects

P Bergmann

Publications and source records attributed to P Bergmann.

At least 19 recordsLinked to original sources
PubMed1992

Longitudinal study of bone metabolism after ethanol withdrawal in alcoholic patients.

The pathogenesis of osteopenia in chronic alcoholism remains unclear, and many ethanol-related abnormalities have been advocated to explain bone loss. A direct inhibitory effect of ethanol on osteoblast function was suggested by in vivo and in vitro studies. We measured biochemical markers of bone turnover in 12 alcoholic men before and during a 2 week period of alcohol withdrawal, and we compared the results with those obtained in 15 nonalcoholic men. Our alcoholic patients presented with (1) decreased serum concentrations of bone gla protein (BGP), suggesting decreased bone formation; (2) increased urinary excretion of hydroxyproline, suggesting increased bone resorption; (3) increased renal threshold of phosphate excretion without modification of serum PTH concentration, suggesting a direct effect of ethanol on the renal handling of phosphate. The rapid increase in serum BGP concentrations following ethanol withdrawal suggests that low serum BGP concentrations in alcoholics may result from a direct toxic effect of ethanol on osteoblast function and/or numbers.

Adult↗
PubMed1992

Expression of mRNA of parathyroid hormone-related peptide in fetal bones of the rat.

Previous studies have indicated that 19-day-old fetal long bones of the rat contain an adenylyl cyclase-stimulating activity antigenically related to parathyroid hormone-related peptide. To ascertain its origin, Northern blotting and in situ hybridization histochemistry were performed. Results demonstrate that mRNA of parathyroid hormone-related peptide is present in RNA extracted from fetal long bones of the rat and that cells responsible for its production are localized in the periosteum. These cells are not mature osteoblasts because they do not synthesize mRNA of osteocalcin. Thus the present study shows that parathyroid hormone-related peptide could be produced locally, at least in part, in the skeleton of fetal rats.

Animals↗
PubMed1992

Early adaptation of thyrotropin and thyroglobulin secretion to experimentally decreased iodine supply in man.

Five healthy male volunteers (aged 25 to 28 years) were studied both after 4 weeks of treatment with 200 micrograms iodine/d orally (PO) and following experimental iodine depletion by treatment with 3 x 300 mg perchlorate/d PO over a 4-week period, in an attempt to better define the early adaptive responses to an alteration in iodine supply in thyroid function. Intrathyroidal iodine, serum triiodothyronine (T3), free T3 (FT3), thyroxine (T4), free T4 (FT4), reverse T3 (rT3), thyroxine-binding globulin (TBG), thyroglobulin (Tg), and thyrotropin (TSH) levels (10-minute sampling over 24 hours) were measured at the end of iodine administration and at the end of perchlorate treatment. Thyroid volume was determined by sonography, and iodine content was determined by fluorescence scintigraphy. TSH pulses were analyzed by computer-assisted programs. Comparing both experimental situations, perchlorate treatment significantly reduced intrathyroidal iodine concentration (4.0 +/- 1.3 to 3.0 +/- 1.2 nmol/mL, P less than .05), but thyroid volume and total serum T4, T3, FT3, and TBG levels were not altered. Mean 24-hour serum TSH levels (1.8 +/- 0.3 to 1.0 +/- 0.3 mU/L, P less than .001), amount of TSH secreted/pulse (0.5 +/- 0.1 to 0.3 +/- 0.1 mU/L, P less than .001), and FT4 levels (15.7 +/- 1.7 to 14.3 +/- 1.4 pmol/L, P less than .005) were significantly diminished, whereas Tg levels (18.6 +/- 10.0 to 35.1 +/- 14.0 ng/mL, P less than .01) were significantly increased. Thyroid-specific antibodies were normal and were not altered by treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

Responsiveness to recombinant erythropoietin therapy in end-stage renal disease. An analysis of the predictive value of several biological measurements, including circulating erythroid progenitors.

In end-stage renal disease (ESRD), the human recombinant erythropoietin doses required to keep haemoglobin in the target range may vary considerably between patients. Previous studies have failed to find any predictive factor of the response. We thus performed the present investigation in 30 ESRD patients to discover if the haematological response to human recombinant erythropoietin (rHuEpo) was related to the results of circulating erythroid progenitor cultures. Peripheral erythroid burst forming units (BFU-E) were cultured in a plasma clot system in the absence or in the presence of autologous serum just before starting rHuEpo therapy. The results showed a higher BFU-E number in ESRD patients than in controls and a stimulatory effect of autologous serum in both patients and controls. Comparison between culture results and haematological response yielded positive correlation between the BFU-E number and the haemoglobin increase during the first month of treatment, and negative correlation between the increase of BFU-E numbers during the first week of therapy and the rHuEpo doses required for a long-term response. We thus conclude that in ESRD patients the individual response to rHuEpo is linked to the numbers of circulating BFU-E.

Adult↗
PubMed1992

Performance of an immunoradiometric assay of erythropoietin and results for specimens from anemic and polycythemic patients.

We evaluated a new commercially available two-site immunoradiometric assay (IRMA; BioMérieux 125I-EPO CoatRIA) for erythropoietin (EPO) in human serum. The precision (CV) was 4.1% intra-assay and 8% interassay for a serum pool with an EPO concentration of 17 int. units/L; the detection limit was 0.5 int. unit/L, one order of magnitude lower than by classical radioimmunoassay (RIA), although standardization of IRMA and RIA were similar. Results by both IRMA and RIA are compared for normal subjects, patients with nonrenal noninflammatory anemias, patients with beta-thalassemia major, hemodialysis patients, and patients with primary or secondary polycythemia. Values by IRMA compared well with those by RIA in the upper area of the range; IRMA and RIA values for EPO show parallel expected variations with the degree of anemia. However, because of its greater sensitivity and specificity, we consider the IRMA more appropriate than RIA for investigating patients with sub-normal EPO concentrations.

Adolescent↗
PubMed1991

Calcitonin secretion in idiopathic renal stone formers.

Several studies demonstrated a reduction in bone mineral content (BMC) in idiopathic renal stone formers (RSF). We found this reduction in association with a chronic low-calcium diet. Low calcium intake could theoretically result in calcitonin deficiency, responsible for increased bone resorption. This hypothesis was tested in 22 male RSF eating a low-calcium diet (350 +/- 72 SD mg/day) for 2 years or more, who showed a significant reduction in their BMC. When compared to 15 normal male subjects eating a free diet, RSF showed increases in serum alkaline phosphatase activity and fasting urinary excretion of hydroxyproline and calcium, suggesting increased bone turnover. Plasma calcitonin levels were measured by radioimmunoassay following an extraction-concentration technique (exCT). Basal plasma exCT levels were higher (P less than 0.005) in RSF (4.1 +/- 0.8 SEM pg/ml) than in normal subjects (2.8 +/- 0.4). Following a 5 minute infusion of 2 mg elemental calcium per kg, levels of plasma exCT tended to increase more, although not significantly, in RSF (51.3 +/- 9.4 pg/ml) than in normal subjects (36.6 +/- 9.7). The CT secretory response, taking into account changes in serum calcium concentration (delta exCT/delta Ca), was higher (P less than 0.05) in RSF (50.0 +/- 10.0) than in normal subjects (25.6 +/- 6.6). Our study thus demonstrates that RSF chronically fed a low-calcium diet have increased basal plasma CT levels and increased CT cells responsiveness. CT deficiency cannot therefore be considered a cause for the low BMC associated with a chronic low-calcium diet in RSF.

Adult↗
PubMed1991

Adenylate cyclase stimulating activity immunologically similar to parathyroid hormone-related peptide can be extracted from fetal rat long bones.

We observed that culture medium conditioned with fetal rat long bones contained peptides immunologically related to the parathyroid hormone-related peptide of malignancy (PTHrP) and stimulated cyclic AMP production in canine renal cortical membranes. Because the adenylate cyclase stimulating activity (CSA) of the medium increased when bone resorption was stimulated, it was suspected that these peptides were stored in the matrix and released during the resorption process. In this work, we extracted the noncollagenous proteins of fetal rat long bones and found that the extract contained significant amounts of CSA. The biologic activity of the extract was abolished after trypsin digestion and eluted at 24 and 37 kD on filtration HPLC. The CSA of bone extract and of both HPLC peaks could be inhibited by 3-34 and 7-34 parathyroid hormone analogs. It was not blocked by an antiserum directed against the N-terminal region of parathyroid hormone, but it was significantly inhibited after an overnight preincubation with an antiserum directed against the 1-11 fragment of PTHrP. One band migrating at 18 kD could be visualized after SDS-PAGE electrophoresis of bone extract and immunoblotting with the anti-PTHrP antiserum. We conclude that an adenylate cyclase stimulator immunologically similar to PTHrP is present in the matrix of fetal rat long bones. Adenylate cyclase stimulating peptides of lower molecular weight found in bone-conditioned medium could be active fragments formed by proteolysis during the resorption process.

Adenylyl Cyclases↗
PubMed1991

Stimulation of calcitonin secretion by an oral calcium load test in normal subjects and in idiopathic renal stone formers.

Circulating concentrations of calcitonin (CT) have been found high in idiopathic renal calcium stone formers (RSF). It has been postulated that this could result from increased serum calcium concentrations following calcium-containing meals. To verify this hypothesis, 15 male idiopathic RSF and 15 male normal subjects underwent plasma CT measurements, following an extraction-concentration technique (exCT), in basal state and during an oral calcium load test. Most RSF exhibited increased excretion of calcium following oral calcium loading, suggesting overabsorption of calcium, but serum calcium did not increase more in RSF than in normal subjects. Basal plasma exCT concentrations were normal in RSF. ExCT plasma concentrations following calcium loading, and the area under the curve of exCT levels, tended to be higher in RSF than in normal subjects, but not significantly. Our results thus do not support the hypothesis that increased plasma CT levels in RSF result from increased serum calcium concentrations following calcium-containing meals.

Administration, Oral↗
PubMed1991

Serum immunoreactive erythropoietin level: a new parameter for monitoring transfusion management of thalassaemia.

Serum immunoreactive erythropoietin (EPO) was measured sequentially in 8 patients with thalassaemia major. The EPO levels were distinctly increased before transfusion; they did not significantly change just after transfusion, but subsequently decreased. Pretransfusion EPO levels were similar to those observed in patients with non renal non inflammatory anaemias of the same severity. Our results show that production of EPO is appropriately increased in thalassaemia major and confirm that stimulation of endogenous erythropoiesis is not completely suppressed by the hypertransfusion regimen commonly used in this disease. As hyperstimulated ineffective erythropoiesis may lead to invalidating complications, we suggest that serum EPO measurements, which are now easily and reliably performed, should be used in monitoring the therapy of thalassaemia major.

Adolescent↗
PubMed1991

Marginal adaptation with glass-ceramic inlays adhesively luted with glycerine gel.

The purpose of this study was to examine the effectiveness of glycerine gels in preventing the formation of an oxygen-inhibition layer during the polymerization of composite resin materials. Sixteen glass-ceramic inlays were adhesively luted with and without the application of glycerine gels on the inlay margins before the polymerization of the luting composite resin material. To remove the oxygen-inhibition layer, the inlays were brushed with acetone. Replicas were obtained before and after acetone brushing, and a computerized quantitative marginal analysis was carried out under the scanning electron microscope. Statistical analysis revealed significant differences between the polymerization with and the polymerization without the use of a glycerine gel. The inlay margins polymerized after the application of a glycerine gel showed better marginal adaptation than did the inlay margins polymerized without it, suggesting that oxygen inhibition during polymerization can be prevented by the application of glycerine gels to the surface of composite resin materials.

Ceramics↗
PubMed1990

Release of parathyroid hormonelike peptides by fetal rat long bones in culture.

We observed that culture medium conditioned with fetal rat long bones stimulated cyclic AMP production by canine renal cortical membranes. This cyclase-stimulating activity (CSA) was retained by an ultrafiltration membrane with a molecular weight cutoff of 5000; three biologically active peaks with an approximate molecular weight of 18,000-25,000, 9000-12,000, and 4000-6000 were separated by high-performance liquid chromatography. The biologic activity was destroyed by trypsin digestion. The stimulation of adenylate cyclase by the medium and by the three peaks was inhibited by [N-leu8,18,Tyr34]parathyroid hormone-(3-34)-amide and by [Tyr34]parathyroid hormone-(7-34)amide. Preincubation of the bone culture medium and of the three peaks with an antibody raised against human parathyroid hormone-(1-34) did not decrease the biologic activity more than incubation with nonimmune serum. However, the biologic activity of the three active peaks was significantly suppressed after preincubation with an antiserum directed against the N-terminal region of the parathyroid hormone-related peptide of malignancy. The release of CSA into the bone culture medium was enhanced by parathyroid hormone induction and by 1,25-dihydroxycholecalciferol. It was decreased by calcitonin. We conclude that fetal murine bones in culture release peptides that stimulate the adenylate cyclase of renal cortical membranes. These peptides are antigenically similar to the parathyroid hormone-related peptide of malignancy. Their release from bones is modulated by hormones that control bone resorption.

Adenylyl Cyclases↗
PubMed1990

Calcitonin and bone mass status in congenital hypothyroidism.

Calcitonin (CT) deficiency and its possible repercussions on bone mass were studied in a group of 9 adult patients (7 females, 2 males) with congenital hypothyroidism of dysgenetic origin. Using a new extraction method (exCT) which considerably improves the sensitivity and the specificity of the assay for CT-monomer, we measured CT levels before and after a short calcium (Ca) stimulation test (2 mg Ca/kg over 5 minutes) to evaluate C-cell secretory reserve. Mean basal plasma CT concentrations were lower in the hypothyroid women (mean +/- SEM: 0.6 +/- 0.1 pg/ml) than in 30 normal female controls (1.7 +/- 0.2 pg/ml, P less than 0.001). Serum calcium increased similarly in the two groups, but postinfusion CT levels were lower in the hypothyroid women, (1.7 +/- 0.2 pg/ml) than in normal women (16.8 +/- 2.9 pg/ml), P less than 0.001. Hypothyroid women showed a 10% reduction in bone mineral content at the diaphyseal site in the radius, 0.840 +/- 0.037 g/cm, compared with normal age-matched controls, 0.930 +/- 0.020 g/cm, (P less than 0.05). Our study demonstrates the existence of a profound CT-monomer deficiency in adult patients with thyroid agenesis or dysgenesis. Both calcitonin deficiency and thyroid hormone treatment could play a role in the observed bone loss. Attention should therefore be paid to bone metabolism during treatment of congenital hypothyroidism to avoid further bone loss.

Adolescent↗
PubMed1990

Involvement of low-calcium diet in the reduced bone mineral content of idiopathic renal stone formers.

The possibility that low-calcium intake in renal stone formers could lead to reduced bone mineral content was investigated in 123 male patients with idiopathic urolithiasis. Radius bone mineral content (BMC) was measured by single photon absorptiometry. Two groups of patients were analyzed: group 1 (n = 63) maintained on a free diet; group 2 (n = 60) maintained on a low-calcium diet (350 mg/day +/- 20 SEM) for 3.9 years +/- 0.6 SEM. The two groups of patients were investigated after a standard reduction of calcium intake for at least 1 week. The urinary excretion of calcium and of hydroxyproline, and the serum alkaline phosphatase activity were higher in both groups than in normal subjects submitted to the same low-calcium diet. Both groups of stone formers showed lowered radius BMC values at 3 cm (distal) and 8 cm (proximal) above the styloid process, but distal BMC was significantly lower in group 2 than in group 1. The results suggest that low-calcium intake could worsen the already decreased BMC of idiopathic renal stone formers.

Adult↗
PubMed1990

Effect of acute hypercalcemia on thyrotropin (TSH) and triiodothyronine responses to TSH-releasing hormone in man.

In chronic hypercalcemia, basal TSH has been found to be low, with normal serum circulating concentrations of T3 and T4. This observation suggested a potentiation by hypercalcemia of the thyroid secretory response to TSH. The present study was undertaken to assess the possible influence of hypercalcemia on the T3 secretory response to TSH. Since T3 secretion was studied after stimulation of endogenous TSH by TRH, it was first necessary to find a protocol enabling us to study the effect of calcium on T3 release without affecting TSH secretion. Eighteen subjects underwent two TRH tests, with and without simultaneous calcium infusion, at 2-week interval and in a randomized order. In group A (five subjects) calcium infusion started 1 min after TRH, in group B (five subjects) 10 min after TRH, and in group C (eight subjects) 20 min after TRH. In groups A and B, TSH secretion was markedly blunted by hypercalcemia. In contrast, when calcium infusion was started 20 min after TRH (group C), the TSH secretion profile was no longer different from that in the control study. However, in this situation the increments of T3 and free T3 120 and 180 min after TRH were significantly higher when the subjects were rendered hypercalcemic than in the control study. These findings suggest that calcium might act at two different levels, to enhance the thyroid secretory response to TSH and decrease TSH secretion by acting directly on the pituitary gland. Both effects would produce the association of low serum TSH and normal levels of T3 and T4 observed in chronic hypercalcemia.

Adult↗
PubMed1990

Comparative study of the changes in insulin-like growth factor-I, procollagen-III N-terminal extension peptide, bone Gla-protein, and bone mineral content in children with Turner's syndrome treated with recombinant growth hormone.

Six girls (7-13 yr old) with Turner's syndrome and short stature were treated for 1 yr with recombinant human GH (0.15 U/kg.day, sc) and had sequential determinations of serum insulin-like growth factor-I (IGF-I), osteocalcin, and procollagen-III. Bone mineral content and density of the spine and radius were measured before treatment and at 90 and 360 days. Two girls received small doses of ethinyl estradiol (0.025 micrograms/kg) in addition to GH. Height velocity increased by 144% after 3 months of treatment. IGF-I was normal (0.75 +/- 0.20 kU/L) before treatment and increased by 90% on day 1 and by 290% on day 360. Procollagen-III was low before treatment; it peaked at 53.0 +/- 14.7 micrograms/L (260% above baseline) on day 30, then decreased to the normal range. Serum osteocalcin increased more slowly to reach a plateau on day 90 of 23.7 +/- 1.2 micrograms/L (46% above baseline). Before treatment, bone mineral content of the spine was 25% lower than that of children matched for bone age. Bone mineral contents of the peripheral and axial skeleton were increased by 10% and 17%, respectively, after 1 yr of treatment, an increase commensurate with that of bone age in the four patients who did not receive estrogen. On day 90, however, although radius mineral density was already increased by 3%, the mineral density of the lumbar spine was significantly decreased by 4%. We conclude that treatment with GH increases IGF-I, collagen turnover, osteoblastic function, and height velocity in Turner's syndrome. However, there is no catch-up of bone mineral content after 1 yr of treatment, and an early effect of GH is to decrease spine mineral density.

Adolescent↗
PubMed1990

Circadian and pulsatile TSH secretion under physiological and pathophysiological conditions.

In addition to the well known circadian rhythm of TSH secretion a pulsatile pattern of release has been shown. Analysis of the pulsatile release by different computer-assisted methods revealed systematic differences in the number and distribution of TSH pulses. Using the same approximation of false positive pulses (less than 1%) in any of the 21 healthy male volunteers tested a lower number of pulses was found by the Pulsar method (mean 5.1 +/- 2.0/24 h) than by the Cluster (10.6 +/- 1.8) or the DESADE program (13.6 +/- 4.6). The results of the Cluster and Desade analysis fit well to that of Fourier transformation which revealed a dominant frequency at 160 min. In addition dominant frequencies in comparison to a noise series were found at 24 h and at 33 min. Analysis of the data in 8 h segments between 2000 and 0400 h, 0400 and 1200 h and 1200 and 2000 h by Desade and cluster revealed that app. 50% of pulses occurred between 2000 and 0400 h, suggesting an important role of pulsatile TSH release in the generation of the circadian TSH rhythm. In 3 patients with TSH-induced hyperthyroidism the circadian and pulsatile pattern of TSH secretion was similar to that in healthy controls. In contrast, in a patient with a TSH producing pituitary tumor the circadian variation of TSH secretion was abolished. Patients with a non-toxic goitre revealed a significantly lower mean TSH serum level as the control group of healthy subjects. The number of TSH pulses was slightly but significantly lower when analyzed by the DESADE program but not when analyzed with any other method.

Adult↗
PubMed1990

[Effect of cavity design on the marginal fit of Class I composite fillings].

16 butt joint (Group A) and 16 beveled (Group B) class I cavities were prepared in extracted molars and filled with two hybrid composite resin materials using the enamel etching technique. Replicas were obtained before and after thermocycling (TC) and a computerized quantitative margin analysis was carried out in the SEM. Statistical analysis revealed significant differences (p less than 0.01) between the two groups only after TC. Group B showed significantly less marginal openings than Group A (A: 50.7%, B: 8.4%) after TC. Class I cavities for hybrid composite resin materials should be beveled.

Acid Etching, Dental↗