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Biomedical subjects

C Bachmann

Publications and source records attributed to C Bachmann.

At least 55 records · Page 3Linked to original sources
PubMed1995

Interaction of fluorescein derivatives with sulfonylurea binding in insulin-secreting cells.

Recently evidence was presented that fluorescein derivatives (e.g. phloxine B) inhibit glibenclamide binding by occupation of a nucleotide-binding site at the ATP-sensitive potassium channel (KATP channel). However, this conclusion was inconsistent with the results of previous studies testing the effects of nucleotides on glibenclamide binding. To elucidate the interaction mode of fluorescein derivatives with sulfonylurea binding, the effect of phloxine B on binding of [3H]glibenclamide to microsomes obtained from a pancreatic beta-cell line (HIT-T15) was examined. Phloxine B inhibited specific binding of glibenclamide half-maximally at 3.2 mumol/l. The slope parameter for the displacement curve was close to one, suggesting a competitive interaction between both drugs. In accordance with this assumption 4 mumol/l phloxine B did not show an effect on the number of high-affinity binding sites but increased the apparent dissociation constant for glibenclamide by 3.1-fold and 30 mumol/l phloxine B did not alter the rate of dissociation of [3H]glibenclamide. Moreover, MgATP (300 mumol/l) significantly reduced the apparent affinity for binding of phloxine B to the sulfonylurea receptor. This finding resembled the action of MgATP on binding of sulfonylureas to their receptor site. It is concluded that fluorescein derivatives inhibit glibenclamide binding due to competition for the same site at the sulfonylurea receptor.

Benzamides↗
PubMed1994

The treatment of spondylotic cervical myelopathy by ventral discectomy. Long term results on 121 patients.

The pathophysiology of spondylotic cervical myelopathy is still a matter of discussion. This paper presents a series of 126 patients operated on using a ventral approach. In 47% of the patients only a spondylotic narrowing of the spinal canal was present and in 35% an additional disc herniation was found. In 13% of the cases however a soft disc without spondylotic spures was found and in 5% a dislocation of vertebral bodies. We found a marked male preponderance of 77%, mean age was 51.6 years, ranging from 25-50 years. Most patients were operated on at the levels of C4/5 and C5/6. Observation time covered a period of 3-10 years. The outcome was rated relatively to the preoperative degree of disablement using a questionnaire for the patients and their family doctors. We found a marked difference in the answers, especially in rating deterioration, which was stated by patients in 34%, by physicians only in 12%. Another finding was the time-related outcome. We found best results with 75% improvement and 5% deterioration between 3-6 months postoperatively, with increasing time the results decreased to 33% improvement, 33% identical statys and in 33% a deterioration related to the preoperative status must be noted.

Adult↗
PubMed1994

Pitfalls in aminoacid and organic acid analysis: 3-hydroxypropionic aciduria.

Pitfalls in organic acid analysis can originate from inadequate methodology, analytical interferences, in vivo interactions and from pre-analytical conditions which often are unknown to the specialized analytical laboratory. Among the latter, ingested food and additives, metabolites of food processing or medications have to be considered. Bacterial metabolites from the gastrointestinal or urogenital system or formed after sample collection can lead to pitfalls as well. An example of such a patient whose urinary metabolites mimic at first glance inherited propionic aciduria is described.

Amino Acid Metabolism, Inborn Errors↗
PubMed1994

Photoaffinity labeling of the cerebral sulfonylurea receptor using a novel radioiodinated azidoglibenclamide analogue.

In previous studies evidence has been presented by photoaffinity labeling that a polypeptide of 145-150 kDa represents the cerebral sulfonylurea receptor. However, covalent incorporation of [3H]glibenclamide or a 125I-labeled glibenclamide analogue into the sulfonylurea receptor required high amounts of photoenergy and took place with low yield of photoinsertion. To provide a probe with increased photoreactivity a 4-azido-5-iodosalicyloyl analogue of glibenclamide was synthesized. Binding experiments revealed specific and reversible high-affinity binding of this novel probe to the particulate (KD = 0.13 nM) and solubilized (KD = 0.56 nM) sulfonylurea receptor from cerebral cortex. The novel probe showed > 100-fold higher sensitivity to irradiation at 356 nm than glibenclamide. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed specific photoincorporation into a cerebral protein of 175 kDa and indicated an efficiency of photoincorporation of 9%. From dissociation binding curves following irradiation photoincorporation was estimated as 28% of specifically bound ligand. Photoincorporation into the 175-kDa protein following saturation binding of the novel probe to particulate sites from cerebral cortex indicated a KD value of 0.38 nM. Inhibition of photoincorporation into this protein by glibenclamide, glipizide, and tolbutamide revealed KD values for these sulfonylureas of 0.06 nM, 1.6 nM, and 1.2 microM, respectively. These results show that the novel photoaffinity ligand can be used as a probe for detection and characterization of the sulfonylurea receptor and suggest that a 175-kDa protein represents the cerebral sulfonylurea receptor.

ATP-Binding Cassette Transporters↗
PubMed1994

Age-related reference values for urinary organic acids in a healthy Turkish pediatric population.

Organic acid concentrations were quantified by gas chromatography and the individual acids identified by mass spectrometry in urine specimens from a healthy Turkish pediatric population of ages 2 days to 16 years, subdivided into five age groups. We quantified 69 organic acids (32 major and 37 minor components) and report here the median values and percentiles for each compound, adjusted for creatinine content, for the five groups. Concentrations of most of the organic acids tend to decrease with age but display substantial differences between age groups. This emphasizes the importance of comparing patients' data with age-matched reference data. Correlations between the excretion of organic acids and protein or caloric intake were significant for several compounds.

Aging↗
PubMed1993

Plasma carnitines: reference values in an ambulatory population.

Carnitine was determined radioenzymatically in the plasma of 415 hospital employees involved in a screening programme for prevention of major cardiovascular risks. A reference population (N = 340) was extracted after excluding subjects with hypertension, diabetes mellitus or treatment for hypercholesterolaemia. This population showed a Gaussian distribution for total and free carnitine concentrations both in females and males but not for acyl carnitine or the acyl/free ratio. Females had lower total and free carnitine concentrations but a higher ratio of acyl/free carnitine than males. These differences were not detectable in older subjects (35 years for the acyl/free ratio, 45 years for total and free carnitine concentrations). Females with a body mass index > 28 had a lower acyl/free ratio than their respective controls. The differences in carnitine concentrations indicate that sex and age should be matched in patients or experimental groups and controls in studies involving carnitine plasma concentrations.

Adult↗
PubMed1992

[Value of simultaneous determination of cyclosporin blood levels using specific and nonspecific methods in liver transplantation].

Cyclosporine's narrow therapeutic window and the large inter- and intra-individual variation of its pharmacokinetics require therapeutic monitoring. Cyclosporine is metabolized in the liver and excreted with its metabolite into the bile. An accumulation of metabolites occurs in liver dysfunction, leading to a high cyclosporine blood concentration when measured by a non-specific method (polyclonal antibodies). Specific methods (HPCL, monoclonal antibody) are therefore recommended by some authors. We evaluated the potential usefulness of simultaneous cyclosporine determination by a non-specific (fluorescent polarisation TDx, polyclonal antibodies) and a specific method (I125-RIA, monoclonal antibody). 10 patients were followed from 51 days to 32 months after hepatic transplantation. 2 patients who showed no graft rejection presented a polyclonal antibodies/monoclonal antibody ratio below or equal to 4 throughout their evolution. Other patients presented a rise of this ratio during periods of liver dysfunction, particularly in acute graft rejection. When bilirubin concentrations are plotted versus this ratio, an hysteresis is present during periods of acute rejection, but not during an episode of histological hepatitis. The same holds true for alkaline phosphatase and gamma-GT. These data suggest that this ratio could be a sensitive test for early detection of rejection. Simultaneous cyclosporine blood determination with specific and nonspecific methods may be useful in the follow-up of liver-transplanted patients.

Adult↗
PubMed1992

Ornithine carbamoyl transferase deficiency: findings, models and problems.

The initial clinical symptoms of ornithine carbamoyl transferase deficiency depend on the age of onset. Respiratory distress on the first day of life does not allow exclusion of OCT deficiency in the individual patient. The acid-base status is not useful as a discriminant between urea-cycle disorders and organic acidurias. Beyond the neonatal age, a second period of increased risk for often lethal hyperammonaemic crises is found between 12 and 15 years of age. For definite diagnosis (pre- and postnatal) of heterozygotes the quantity of tissue obtained should be sufficient to obtain a representative sample for a mosaic structure. Experimental work gives some clues for the interpretation of reversible symptoms of hyperammonaemia. The increased transport of tryptophan at the blood-brain barrier in presence of increased glutamine concentration in tissue appears to depend on intact gammaglutamyl transpeptidase in brain microvessels and involves at least in part the L-carrier. Animal research on the mechanisms leading to irreversible damage in hyperammonaemia should be encouraged in order to define reliable predictive criteria for clinical decisions.

Adolescent↗
PubMed1992

Hartnup syndrome, progressive encephalopathy and allo-albuminaemia. A clinico-pathological case study.

Clinical, biochemical, neuropathological and neurochemical findings in a case of Hartnup syndrome are reported. After initially normal development, the affected girl suffered progressive neuropsychiatric decline with statomotor and mental retardation and intractable seizures and died at the age of 2 years. Postmortem neuropathological and neurochemical investigations showed a combination of extensive neuronal degeneration and cerebral dysmyelination. Pathogenetic hypotheses and the relationship between neuropsychiatric disease and Hartnup syndrome are discussed. Additionally, a fast type bisalbuminaemia present in the girl and her mother is described.

Amino Acids↗
PubMed1992

[Screening for cardiovascular disease risk factors among employees of a hospital].

A health promotion and screening program for the detection of the major risk factors for ischemic heart disease was carried out in 1990 among the employees (n = 4,521; 70% female) of the Centre Hospitalier Universitaire Vaudois (CHUV). The prevalence of risk factors among the 1,425 employees (73% female) who took part in the study (participation rate: males 29%, females 33%) was compared with the prevalence of risk factors within three other populations: 1) new CHUV employees, who are systematically screened (n = 424: 71% female); 2) a representative sample of the general population; and 3) a group of employees from 44 companies located in the same region. Smoking was the most common of the three main risk factors; its prevalence was lowest among CHUV employees and highest among employees of the 44 firms. The prevalence of hypercholesterolemia and high blood pressure was variable among the different populations. These variations could partly be due to differences in methodologies and measurement conditions, but could not totally be explained in this way.

Adult↗
PubMed1992

Long-term follow-up of 12 patients with the late-onset variant of argininosuccinic acid lyase deficiency: no impairment of intellectual and psychomotor development during therapy.

To date, two variants of argininosuccinic acid lyase deficiency, the second most common enzymatic defect of the urea cycle, have been described. Most of the previous studies reported on outcomes involving neurological and intellectual impairment in affected children. This study is the first to demonstrate that the physical and mental development of such children can be normal and adequate for their age if they are treated with a low-protein diet and/or arginine supplements. Since 1973, 12 Austrian children suffering from argininosuccinic acid lyase deficiency have been detected in the Austrian Neonates Screening Program and could have been followed up. After confirmation of diagnosis, all the children were administered a daily arginine supplement (3 to 4 mmol/kg per day) in conjunction with either a normal diet or a special diet in which protein intake was restricted to 1.2 to 1.5 g/kg per day. Routine checks, including physical examination, determination of biochemical parameters, and IQ tests, were performed so the further development of these 12 patients with respect to treatment could be observed. It can be concluded that early treatment of partial argininosuccinic acid lyase deficiency results in normal intellectual and psychomotor development.

Amino Acid Metabolism, Inborn Errors↗
PubMed1991

N-acetylglutamate synthetase deficiency: diagnosis, management and follow-up of a rare disorder of ammonia detoxication.

We report the 9-year follow-up of a patient suffering from N-acetylglutamate synthetase deficiency, an urea cycle disorder leading to severe neonatal hyperammonaemia. Hitherto two patients from two families with this inborn error of metabolism had been observed. Our management consisted mainly of a protein-restricted diet and oral treatment with N-carbamylglutamate, an activator of carbamylphosphate synthetase, together with arginine or citrulline. The somatic development was normal whereas a moderate psychomotor retardation was diagnosed. The patient died after an episode of coma and prolonged generalized convulsions at the age of 9.5 years.

Acetyltransferases↗