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Biomedical subjects

D Breyer

Publications and source records attributed to D Breyer.

13 recordsLinked to original sources
PubMed1993

A subtractive hybridization method to isolate tissue-specific transcripts: application to the selection of new brain-specific products.

A method based on subtractive hybridization of brain complementary DNAs with peripheral messenger RNAs has enabled us to construct an enriched brain-specific cDNA library. Single-stranded cDNAs (ssc DNAs) were synthesized from brain polyadenylated mRNAs and subsequently hybridized with peripheral mRNAs immobilized on nitrocellulose membrane. Unhybridized sscDNAs were converted into double-stranded cDNAs and cloned into plasmid pUC13. The screening of the resulting library showed that a high percentage of the cloned cDNAs corresponded to mRNAs specifically transcribed in the brain.

Animals↗
PubMed1992

Biochemical, genetic and molecular characterization of new respiratory-deficient mutants in Chlamydomonas reinhardtii.

Eight respiratory-deficient mutants of Chlamydomonas reinhardtii have been isolated after mutagenic treatment with acriflavine or ethidium bromide. They are characterized by their inability to grow or their very reduced growth under heterotrophic conditions. One mutation (Class III) is of nuclear origin whereas the seven remaining mutants (Classes I and II) display a predominantly paternal mt- inheritance, typical of mutations residing in the mitochondrial DNA. Biochemical analysis has shown that all mutants are deficient in the cyanide-sensitive cytochrome pathway of the respiration whereas the alternative pathway is still functional. Measurements of complexes II + III (antimycin-sensitive succinate-cytochrome c oxido-reductase) and complex IV (cytochrome c oxidase) activities allowed to conclude that six mutations have to be localized in the mitochondrial apocytochrome b (COB) gene, one in the mitochondrial cytochrome oxidase subunit I (COI) gene and one in a nuclear gene encoding a component of the cytochrome oxidase complex. By using specific probes, we have moreover demonstrated that five mutants (Class II mutants) contain mitochondrial DNA molecules deleted in the terminal end containing the COB gene and the telomeric region; they also possess dimeric molecules resulting from end-to-end junctions of deleted monomers. The two other mitochondrial mutants (Class I) have no detectable gross alteration. Class I and Class II mutants can also be distinguished by the pattern of transmission of the mutation in crosses. An in vivo staining test has been developed to identify rapidly the mutants impaired in cyanide-sensitive respiration.

Animals↗
PubMed1991

The effect of guanidino substances from uremic plasma on insulin binding to erythrocyte receptors in uremia.

We have studied insulin binding to erythrocyte receptors in a group of 25 nonobese, nondiabetic uremic patients undergoing maintenance hemodialysis for 2-54 months and 14 healthy controls. Erythrocytes of predialyzed uremics bind significantly less insulin than control erythrocytes (p less than 0.01). Dialysis resulted in a rapid increase of insulin binding (p less than 0.001). The concentrations of plasma insulin and glucose remained essentially unchanged during 5-hour hemodialysis and did not significantly differ from the control values. The down regulation of insulin receptors in undialyzed patients in the presence of normal plasma insulin concentration indicates that factors other than insulin itself could be responsible for insulin receptor activity during uremia. The results demonstrated that creatinine, creatine and glycocyamine have a direct suppressive effect on insulin binding of postdialyzed plasma (p less than 0.05) in concentration of 1 mmol/l. This suggested that specific uremic toxins could play an important role in the mechanisms of altered insulin binding during hemodialysis. Despite the high concentration of these compounds in blood of uremics, the only common feature for these compounds is the presence of the guanidino group in the molecule.

Adult↗
PubMed1985

Changes in insulin binding during hemodialysis in uremic patients.

To investigate factors responsible for altered insulin sensitivity in uremia, we studied 125I-insulin binding to erythrocytes in 20 uremic patients before and after dialysis. In uremic patients, predialysis binding was 50% lower in comparison with healthy controls (4.35 +/- 1.79 vs. 9.37 +/- 1.30%; p less than 0.01). Five-hour dialysis treatment resulted in a rapid increase in binding (on average to 55%; p less than 0.01). During the course of dialysis, binding to erythrocytes from 2 selected patients steadily increased in a time-dependent manner (on average 24%/h). The dialysis-induced increase in binding did not correlate with the changes in plasma insulin levels, but depended on the efficiency of dialysis as assessed by a relative decrease in plasma urea and creatinine. After an intravenous glucose load, the insulin-to-glucose ratio decreased in parallel with the increase in binding after dialysis. The results indicate that uremic plasma contains dialyzable substances which reversibly inhibit insulin binding, leading to altered insulin sensitivity.

Adult↗
PubMed1984

Serum uric acid concentrations in offspring of conjugal diabetic parents.

Serum uric acid concentrations were measured in offspring of conjugal diabetic parents, in diabetic patients, and in matched nondiabetic controls. The mean uric acid level in offspring of conjugal diabetic parents was significantly higher than in the controls and diabetic patients (P less than 0.001 in the nonobese and P less than 0.05 in the obese). Diabetic patients did not show significant differences in the serum uric acid concentration compared to the controls. The elevated level of serum uric acid in offspring of conjugal diabetic parents could possibly be an early biochemical marker of diabetes.

Adult↗
PubMed1983

Inhibitor of insulin binding to erythrocytes in plasma of uremic patients.

Previously, we have shown that insulin binding (IB) to erythrocytes was decreased in uremic patients and that hemodialysis corrected the receptor defect. In the present study cross-incubation experiments were performed using uremic and control erythrocytes and plasma. Incubation of control erythrocytes with uremic plasma resulted in a 60% decrease in specific insulin binding, and progressive dilutions of uremic plasma revealed a parallel decrease in degree of inhibition suggesting the presence of an inhibitor of insulin binding in uremic plasma. Plasma obtained from uremic patients exhibiting lower IB to their erythrocytes was more potent in inhibition of IB to control erythrocytes, i.e. predialysis in comparison with postdialysis plasma. The alteration of IB was reversible since incubation of uremic erythrocytes with normal plasma restored IB towards normal values. Subjects having higher IB to their erythrocytes had more efficient plasma in restoring IB to uremic erythrocytes. The data indicate that alteration of insulin binding in uremia is mediated by dialysable plasma inhibitors. The possibility that humoral factors affecting binding of insulin to its receptors can in this way influence the sensitivity of peripheral tissues to insulin is considered.

Adult↗
PubMed1983

Improvement of insulin binding to erythrocyte insulin receptors in uraemia by haemodialysis.

Insulin binding to erythrocytes obtained from uraemic patients was determined using a radioreceptor assay. The binding was reduced by 50 per cent in 20 non-diabetic uraemic patients in comparison with 20 controls (4.7 +/- 1.79 vs 9.37 +/- 1.30 (mean +/- SD) p less than 0.01). During the course of haemodialysis insulin binding steadily increased in a time dependent manner in proportion to the efficiency of haemodialysis as assessed by relative decrease in plasma urea, uric acid or creatinine. Incubation of healthy donors' erythrocytes with uraemic plasma resulted in a dose dependent inhibition of insulin binding with a maximum of 40 per cent. These data indicate the presence of dialysable inhibitors of insulin binding in uraemic plasma.

Adult↗
PubMed1981

Decreased insulin binding to erythrocytes in subjects with Klinefelter's syndrome.

Insulin binding to specific erythrocyte receptors was investigated in group of 25 subjects with Klinefelter's syndrome (47 XXY genotype) and 14 healthy male volunteers. Insulin binding was significantly decreased in Klinefelter subjects (P less than 0.01 at insulin concentrations of 0.051 and 0.136 mmol/liter); however, their fasting glucose concentration was normal (87 +/- 17), and the glucose disappearance rate was slightly increased (2.3 +/- 0.9; P less than 0.2). These data indicated a compensatory, mechanism involved in the glucose metabolism in Klinefelter's syndrome.

Erythrocyte Membrane↗