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Biomedical subjects

R Ziegler

Publications and source records attributed to R Ziegler.

At least 289 records · Page 16Linked to original sources
PubMed1992

Disturbance of GABA metabolism in pyridoxine-dependent seizures.

In an infant with typical pyridoxine-dependent seizures, CSF GABA level, was determined before treatment with pyridoxine. Before onset of treatment, level of GABA in CSF was highly lowered (16 pmol/ml), pyridoxine level in serum was within normal range. Immediately after application of 80 mg pyridoxine fits stopped and the EEG was without seizure activity. The data substantiate previous findings in brain tissue from a patient with pyridoxine-dependent seizures. They are proof of a disturbed GABA metabolism in pyridoxine dependent seizures.

Brain↗
PubMed1992

Localization of occult persisting medullary thyroid carcinoma before microsurgical reoperation: high sensitivity of selective venous catheterization.

In 14 patients with occult persisting medullary thyroid carcinoma, tumor tissue was removed by microsurgical reoperation in 13 of 14 patients. This resulted in biochemical improvement in all but 1 patient and biochemical cure in 3 patients (21%). The lateral compartment of the neck or the upper mediastinum was involved in all but 1 patient. Before microsurgical reoperation, selective venous catheterization (SVC) for serum sampling along with serum calcitonin (CT) determination was done and compared to other localization methods. Tumor tissue could be localized correctly by SVC in 89% (CT gradient 1.21-2.02), computed tomography in 38%, and ultrasound in 28%. In patients with an elevated CT level after initial surgery and clinically occult disease, SVC is recommended for localization of tumor tissue. The affected side of the neck should be reoperated on with microdissection of the central and lateral compartment of the neck and the upper mediastinum. With this procedure, the cure rate of reoperation in patients with persistent occult MTC can be improved.

Calcitonin↗
PubMed1992

Circulating levels of midregional parathyroid hormone-related protein in hypercalcaemia of malignancy.

OBJECTIVE: We have developed and evaluated a sensitive radioimmunoassay directed against the midregional part of parathyroid hormone-related protein (PTHrP), which is involved in the syndrome of humoral hypercalcaemia of malignancy. PATIENTS: Midregional PTHrP levels were studied in 41 consecutive inpatients with malignancy and hypercalcaemia, 32 normocalcaemic patients with malignancy, 21 patients with primary hyperparathyroidism, 34 patients with renal failure, and 87 normals. MEASUREMENTS: The assay used an antiserum against the midregional amino acid residues 53-84 of PTHrP and PTHrP(1-86) as label and standard. Midregional PTHrP was stable in serum and plasma and could be measured directly without sample extraction. RESULTS: Normal plasma concentrations ranged from undetectable (< 5 pmol/l) to 21 pmol/l. In renal failure, PTHrP was positively correlated with serum creatinine, but PTHrP elevations of up to 30 pmol/l were found only in severe renal dysfunction with creatinine > 850 mumol/l. In hypercalcaemia caused by solid tumours, midregional PTHrP was elevated in 81% (22 of 27) of patients, ranging from undetectable to 203 pmol/l (median: 40 pmol/l). In these patients serum calcium correlated positively with PTHrP (P < 0.01). Mean PTHrP levels were indistinguishable in subgroups with and without metastatic skeletal disease. The mechanism of hypercalcaemia in 14 patients with haematological malignancy was apparently different, since all but one had normal or only marginally elevated PTHrP levels. In 21 patients with primary hyperparathyroidism midregional PTHrP was normal in 20. The assay was therefore especially useful in distinguishing the latter condition from humoral hypercalcaemia of malignancy as the second major cause of hypercalcaemia. PTHrP was normal in all 32 patients with normocalcaemic malignancy. CONCLUSION: This radioimmunoassay of midregional PTHrP provides high diagnostic sensitivity in the identification of humoral hypercalcaemia of malignancy caused by solid tumours. The assay should therefore be useful in the differential diagnosis of hypercalcaemia.

Diagnosis, Differential↗
PubMed1992

Bone mass of spine and forearm in osteoporosis and in German normals: influences of sex, age and anthropometric parameters.

We measured forearm bone mineral density (BMD) using single photon absorptiometry (SPA) and bone mineral content (BMC) and BMD of lumbar spine by dual photon absorptiometry (DPA). The population consisted of 463 bone healthy subjects, 346 females and 117 males aged 20-85 years. Any underlying bone disease or other diseases known to affect bone mass were excluded by physical examination, thoracic and lumbar radiographs and laboratory screening. Patients with osteoarthritis of lumbar spine were excluded as well as patients taking drugs known to affect bone mass. All bone mass values declined with age. Body height also declined with age by 1.2 cm and 1.8 cm per 10 years (-0.7% and -1%) in females and males respectively. Main effects of age, body height, -surface, -weight and -mass index on bone mass were calculated using multiple regression models. In males and females lumbar BMC measured in gHA depended primarily on body height and secondarily on age. Spinal BMD as measured in g cm-2 was primarily dependent on age and then on height. In females forearm BMD depended primarily on age and then on body surface, in males on body surface only. Using receiver operating characteristic (ROC) analysis the ROC area increased from 0.81-0.85 (n.s.) including body height into spinal BMD values leading to a higher sensitivity of measurements of spinal bone mass in recognizing 58 patients with spinal postmenopausal osteoporosis. Including body surface into forearm BMD measurements ROC area increased from 0.66-0.69 (P = 0.055).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Severe type III hyperlipoproteinemia associated with unusual apolipoprotein E1 phenotype and epsilon 1/'null' genotype.

A 60-year-old white male (KH) was diagnosed to suffer from severe type III hyperlipoproteinemia (HLP) and premature cardiovascular disease. Biochemical analysis revealed an unusual apolipoprotein (apo) E phenotype and genotype. All clinical characteristics of type III HLP were present in the patient. His very low density lipoprotein (VLDL) cholesterol to plasma triglyceride (TG) ratio was elevated at 0.97 without therapy which is unusually high (normal ratio about 0.18). By contrast his plasma apo E level was only moderately elevated (6.8 mg dl-1). The patient's apo E migrated in the apo E1 position on isoelectric focusing gels. Chemical modification with cysteamine and treatment with neuraminidase confirmed the presence of two cysteine residues in the patient's apo E and a normal sialylation pattern. Pedigree analysis suggested that the patient was a compound heterozygote with one apo epsilon 1 allele and another allele whose product did not appear in the plasma compartment ('null' allele). Direct sequencing of polymerase chain reaction (PCR) amplified segments of the apo E gene as well as restriction fragment length polymorphism (RFLP) analysis with the endonuclease Taq I identified an adenosine for guanosine (G-->A) exchange in the second base of codon 127 that is predictive for an Asp for Gly substitution in the encoded apo E amino acid sequence. This mutation is the structural basis for the apo E1 isoform identified upon isoelectric focusing. Five other family members are also carriers of the mutant apo epsilon 1 allele. Two of those were hyperlipidemic and exhibited biochemical characteristics of type III HLP. A second mutation, a deletion of a G in codon 31, is predictive for a reading frameshift that encodes for a premature stop in codon 60. Our inability to identify the product of a second apo E allele in the plasma of the patient and two other members of the KH family corresponds with the heterozygous presence of this mutation in the affected individuals. Both relatives (like the index case) had an increased VLDL cholesterol to plasma TG ratio, which indicates the presence of cholesterol-enriched VLDL particles. We propose that the single base deletion in the apo E gene which is the cause of a non-functional 'null' allele in addition to a probably dominant apo E1 (Gly127-->Asp, Arg158-->Cys) variant of late or incomplete penetrance are the primary genetic defects in this kindred leading to severe dysbetalipoproteinemia.

Adolescent↗
PubMed1992

Effects of endogenous and exogenous calcitonin on inflammation-mediated osteopenia in the rat.

Inflammation-mediated osteopenia (IMO) in the rat is characterized by loss of bone mass within 3 weeks after induction of nonspecific inflammation (s.c. talcum injections) in growing rats. Histologically, this shows as marked inhibition of osteoblasts 3 days after the initiation of IMO. The role of calcitonin (CT) was investigated in the present study. A reversible increase of serum CT levels was found after intraperitoneal calcium challenge in rats on day 4 after induction of IMO, which was thought to be a result from calcium efflux from bone. No difference in stimulated serum CT levels between the rats with and without IMO was seen on any other day during 4 weeks after initiation of IMO. Bone loss after IMO was more pronounced in normocalcemic and euthyroid rats with deficiency of endogenous CT (thyroidectomy with parathyroid gland reimplanted) (-12.9%) compared with sham operated controls with IMO (-3.25%). Daily subcutaneous injections of 100 mIU salmon CT in rats with and without IMO did not prevent the development of bone loss. This might have been due to the growing state of rats of this age group. Our results support the hypothesis that endogenous CT physiologically has a bone protective role. They furthermore are consistent with the view that endogenous CT itself is not pathogenetically involved in the development of osteoporosis.

Animals↗
PubMed1992

Differential effects of platelet-derived growth factor isoforms on plasminogen activator activity in fetal rat osteoblasts due to isoform-specific receptor functions.

We examined receptor binding and metabolic effects of the platelet-derived growth factor (PDGF) isoforms AA, AB, and BB in cultures of osteoblastic cells from fetal rat calvaria. Saturation binding experiments demonstrated the presence of 6,000 binding sites for PDGF-AA, 42,000 for PDGF-AB, and 60,000 for PDGF-BB. Binding competition experiments were compatible with the recently postulated model of three PDGF receptor subtypes with differential affinity for the PDGF isoforms. The effects of the PDGF isoforms on DNA synthesis, collagen synthesis, and alkaline phosphatase activity in osteoblasts strictly correlated with the number of available binding sites. Accordingly, PDGF-BB was the most potent isoform, PDGF-AB was slightly less potent, and PDGF-AA was the least potent. In contrast, we found that PDGF-BB was less potent than PDGF-AB in increasing plasminogen activator activity in the osteoblast-conditioned medium. Our data strongly suggest that the PDGF receptor subtypes in fetal rat osteoblasts not only selectively bind one or more PDGF isoforms, but are also capable of responding differently to these isoforms.

Alkaline Phosphatase↗
PubMed1992

Serum levels of intact parathyroid hormone and alkaline phosphatase correlate with cortical and trabecular bone loss in primary hyperparathyroidism.

We examined the relationship between bone loss and several biochemical indices in 38 patients with primary hyperparathyroidism. Bone mineral density was reduced by 12 +/- 4.0% in the lumbar spine, 18 +/- 4.2% at the distal radius and 21 +/- 2.8% at the proximal radius (mean +/- SEM). There were significant negative correlations between the serum concentrations of intact parathyroid hormone (PTH) and the Z-scores of the bone mineral content at the proximal and distal radius. In the lumbar spine, bone mineral density was greater in patients with mildly elevated PTH and less in patients whose PTH levels exceeded 8.6 pmol/l. We also observed a strong association between increased levels of serum alkaline phosphatase and low bone mineral Z-scores. Our data thus indicate that cortical and, with the exception of mild primary hyperparathyroidism, trabecular bone loss is proportional to the concentration of circulating PTH and the severity of PTH-induced bone turnover. For the individual patient, however, the usefulness of intact PTH and alkaline phosphatase measurements for assessing bone loss associated with primary hyperparathyroidism seems to be only limited.

Aged↗
PubMed1992

Long-term excess of endogenous calcitonin in patients with medullary thyroid carcinoma does not affect bone mineral density.

In a cross-sectional study of 39 patients with medullary thyroid carcinoma (MTC), we have investigated the effects of long-term calcitonin excess on bone mineral density. Bone mineral density was measured by dual X-ray absorptiometry at the lumbar spine between the second and fourth vertebra and by single photon absorptiometry at the distal forearm. The mean observation time of each patient between diagnosis of tumour and measurement of bone mineral density was 62.4 months (range 1-158 months). The mean calcitonin serum level was 14.4 micrograms/l at the time of measurement of bone mineral density. All patients were substituted with 150-200 micrograms L-thyroxine daily. At both sites, the mean bone mineral densities of all patients with MTC were not significantly different from controls. Patients with normal calcitonin levels (below 0.2 micrograms/l) after treatment had a normal bone mineral density of the spine but significantly (P less than 0.05) reduced bone mineral density values of the forearm. This was due to the decreased body surface areas of patients in this subgroup. Patients with multiple endocrine neoplasia type IIa had significantly higher bone mineral densities. Other bone-influencing factors, such as postoperative hypoparathyroidism, calcium intake, diarrhoea, menopause, tumour stage, previous anti-tumour treatment, or thyroxine substitution dose, did not affect bone mineral density. We thus conclude that long-term excess of endogenous calcitonin in patients with MTC has no positive effect on bone mineral density.

Absorptiometry, Photon↗
PubMed1992

Somatostatin acts via a pertussis toxin-sensitive mechanism on calcitonin secretion in C-cells.

The effect of the somatostatin analog octreotide on cAMP-mediated calcitonin (CT) secretion and cAMP accumulation in C-cells was investigated. Glucagon stimulated cAMP accumulation and CT secretion with a maximal effect at a concentration of 10(-6) M. The cAMP antagonist RpcAMPs blocked the glucagon-induced CT secretion down to control levels. Therefore, no other second messengers seem to be involved in glucagon-stimulated CT secretion. Octreotide in increasing doses (10(-9) to 10(-6) M) inhibited cAMP accumulation and CT secretion with a maximal effect at a concentration of 10(-7) (40% and 29% of control values, respectively). Pretreatment of the cells with 100 ng/mL pertussis toxin for 24 hours abolished the inhibitory effect of octreotide on cAMP accumulation and CT secretion (82% and 58% of control values, respectively). Similar results were obtained under the influence of the phosphodiesterase inhibitor IBMX. Therefore, we conclude that somatostatin modulates adenylate cyclase-coupled CT secretion in C-cells via a pertussis toxin-sensitive G-protein possibly in an autocrine/paracrine way.

Adenylate Cyclase Toxin↗
PubMed1992

Diabetes mellitus and bone metabolism.

Whether there is a diabetic osteopathy" or osteopathy in diabetes mellitus", is still unclear. Epidemiological studies show in part discrepant results: bone mass was diminished in some studies, unchanged in others--even more positive trends were reported. Increases in osteoporotic fractures were observed in smaller collectives whereas no general trends for fracturing bones were found in diabetics. There are many in part favouring, in part impairing factors to be taken into consideration: Diabetes mellitus type I is a disease including immune phenomena. As inflammation leads to bone loss (inflammation-mediated osteopenia = IMO), peak bone mass may be influenced by such a process. The lack of insulin-like growth factors may be decisive, too. Complications of diabetes mellitus include hypogonadism--this may be disadvantageous for the skeleton. Diabetic complications like retinopathy, neuropathy, and angiopathy may influence the fracture event independently from bone mass. On the other hand, diabetes mellitus type II may be somehow protected against bone loss: Increased adipose tissue in connection with the frequently seen overweight yields metabolically active steroid hormones, insulin related growth factors may stimulate bone formation (e.g. in Forestier's disease). Older diabetics do not show diminished life expectancy any more due to their regular medical care--whether this includes the risk of bone diseases, is not yet clear. It may be worth to further analyse these "positive" effects seen in bones of type II diabetics because they may be useful in osteoporosis even in non-diabetics.

Animals↗
PubMed1991

[Increased prevalence of osteoporosis and arteriosclerosis in conventionally substituted anterior pituitary insufficiency: need for additional growth hormone substitution?].

In a retrospective study of 632 patients with pituitary disease we diagnosed pituitary insufficiency without hypersecretion of any pituitary hormone in 122 patients. Patients were substituted with sex hormones (76%), hydrocortisone (74%) and/or L-thyroxine (77%). 76% had additional growth hormone deficiency, as shown by an increase of growth hormone of less than 5 ng/ml after i.v. administration of L-arginine. In 17% of all patients the diagnosis of osteoporosis was proven or suspected radiologically. 57% had low bone mass of lumbar spine (dualphotonabsorptiometry) and 73% had low bone mass of the proximal forearm (singlephotonabsorptiometry). BMD values of pituitary insufficient patients were in the same range as those of patients with established osteoporosis. More than half of all patients (53%) complained of tiredness, exhaustion and muscle weakness. 40% suffered from adipositas. 77% had hyperlipidemia (68% hypertriglyceridemia and 42% hypercholesterinemia), 18% had hypertension. 14% of the patients had arteriosclerotic events in their history (myocardial infarction or stroke). These figures are higher than incidences shown in the German PROCAM-study. These data show an increased prevalence of osteoporosis and vascular diseases. This is in contrast to the general opinion, that patients with pituitary insufficiency are adequately treated by substitution with adrenal, thyroid and sex hormones. Whether other factors such as the additional growth hormone deficiency are responsible for these diseases has to be examined in prospective studies.

Adolescent↗
PubMed1991

[The antibaby pill as a risk factor for thrombosis: are the molecular mechanisms known?].

Oral contraceptives are being associated with an increased risk of thrombosis. Measurements of clotting factor abnormalities in plasma can not predict the individual risk of thrombosis, nor can they explain the pathophysiology of the clinically known association of thrombosis and oral contraceptives. Research conducted over the last 10 years points to the important role of endothelial cells, fibroblasts and monocytes in the regulation of the initiation of coagulation. Hence we propose, that the molecular mechanism of oral contraceptive associated thrombosis can only be elucidated by studies looking at the effect of these drugs on cellular elements involved in coagulation. Measurements of plasmatic coagulation factors can not indicate safety or risk for a patient taking any of the multiple drugs available.

Blood Coagulation Factors↗
PubMed1991

[PTH-related protein (PTHrP) in serum of patients with tumor hypercalcemia].

Parathyroid hormone-related protein (PTHrP) is a recently described hormone, that was isolated from malignant tumors. It shows many properties of parathyroid hormone (PTH) and is related to the pathogenesis of humoral hypercalcemia of malignancy. Therefore, we analyzed PTHrP in the sera of 30 patients with hypercalcemia of malignancy and compared the values with those obtained in patients with primary hyperparathyroidism, Paget's disease of bone, and normal subjects. PTHrP was quantitated with radioimmunoassay (RIA) using aminoterminal antibodies without and with chromatographical sample purification applying SEP-PAK C18 cartridges. Measurements of PTHrP without sample purification yielded high values in all patient groups. There was no differentiation between patient groups. However, quantitation of PTHrP after SEP-PAK C18 purification of the samples resulted in values above the normal range only in tumour patients. In 30 normal subjects PTHrP levels were 110 +/- 75 pg-eq/ml. Eight out of 30 patients with malignant tumours displayed PTHrP-concentrations above 335 pg-eq/ml. PTHrP levels in patients with primary hyperparathyroidism or Paget's disease of bone were within the normal range. PTHrP concentrations were not affected from renal function. We conclude, that determination of PTHrP after sample purification may contribute to the differential diagnosis of malignant disease.

Aged↗
PubMed1991

Different isoforms of an apoprotein (apolipophorin III) associate with lipoproteins in Locusta migratoria.

Insects transport lipid for flight in the form of diacylglycerol-rich low-density lipoproteins (low-density lipophorin, LDLp), which in the hemolymph are produced from high-density lipophorin (HDLp) by reversible association with several molecules of an apolipoprotein, apolipophorin III (apoLp-III, Mr approximately 18,000-20,000) during lipid loading. Two isoforms of apoLp-III (a and b) were purified both from adult Locusta migratoria migratorioides hemolymph and LDLp, which have identical apparent Mr but differ in amino acid composition, NH2-terminal amino acid sequence, and isoelectric points (5.35 +/- 0.01 for apoLp-IIIa, 5.10 +/- 0.01 for apoLp-IIIb). The NH2-terminal sequence of apoLp-IIIb is identical to the primary structure of apoLp-III deduced from cloned cDNA [Kanost et al. (1988) J. Biol. Chem. 263, 10,568-10,573], whereas the NH2-terminal sequence of apoLp-IIIa is identical to that of apoLp-IIIb but preceded by Arg-Pro-, which is the C-terminal of the putative signal peptide coded by cDNA upstream from that coding for apoLp-IIIb. The ratio apoLp-IIIa apoLp-IIIb free in hemolymph is identical to that in LDLp (5:9); since 14 molecules of apoLp-III appear to be bound in one molecule of LDLp, an average of 5 molecules of apoLp-IIIa and 9 of apoLp-IIIb are involved in formation of each LDLp particle. In vivo studies using 35S-labeled apoLp-IIIa and b demonstrate that each of the isoforms can associate with HDLp to produce LDLp reversibly; in an in vitro system, production of LDLp containing exclusively apoLp-IIIa or apoLp-IIIb demonstrates independent participation of each isoform in LDLp formation.

Amino Acid Sequence↗