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Biomedical subjects

N Gutman

Publications and source records attributed to N Gutman.

35 records · Page 2Linked to original sources
PubMed1983

Glucosyl and galactosyl transferase activities of diabetic (db/db) and obese (ob/ob) mice kidneys.

1. Glucosyl and galactosyl activities were determined in kidney cortex tissue prepared from two strains of mice, genetically diabetic and obese mice. 2. These activities were measured as a function of ageing between 6 weeks and 13 months. 3. For both strains glucosyl transferase activity was shown to increase with respect to ageing whereas galactosyl transferase activity decreased at the same time. 4. These changes of enzymatic activities would suggest that a smaller increase of hydroxylysine-linked glycans than expected was observed under these pathological conditions.

Aging↗
PubMed1983

Nonenzymatic glycosylation of collagen in diabetes: incidence on increased normal platelet aggregation.

The effect of normal and nonenzymatically glycosylated rat type I acid-soluble collagen on normal human platelets was investigated. Glycosylated collagen was obtained either after in vitro incubation with glucose or from rats made diabetic by streptozotocin. The amount of nonenzymatically bound glucose was as follows: normal 2.3, diabetic 7.6 and in vitro glycosylated collagen 9.0 nmol/mg. When investigated under conditions leading to identical diameters and molecular packings for all the samples, the aggregation potency was markedly stronger for diabetic and glycosylated collagens than for normal ones. These results show the potential role of this posttranslational modification of collagen which can be considered as a risk factor in the thrombotic pathogeny of diabetes.

Animals↗
PubMed1983

The molecular interaction between platelet and vascular wall.

Two different subendothelial macromolecules have been identified as being thrombogenic: collagen and the microfibrils associated with elastin. The interaction between platelets and collagen involves the binding of platelet membrane receptors by numerous sites repeatedly staggered along a collagen fiber: this explains why the preservation of ordered structures (quaternary and tertiary structures) is so important in the reactivity of collagen towards platelets. In the case of Type III collagen, a nonapeptide has been identified as possibly being part of these repetitive sites. The microfibrils have not yet been characterized, although the biochemical data presently available show that they are acidic glycoproteins resistant to collagenase. Microfibrils extracted from human placenta or bovine aorta induce the aggregation of platelets in a reaction which involves platelet glycoprotein Ib and FVIII/vWF. A general model proposed for explaining platelet adhesion to subendothelium suggests that two different mechanisms should be envisaged depending on the thrombogenic macromolecules (collagen, microfibrils) involved.

Binding Sites↗
PubMed1982

[Thrombogenicity of the vessel: role of microfibrils and of collagen].

Thrombogenicity of the vessel wall: role of the microfibrils and collagen. The study of platelet adhesion to rabbit aortic subendothelium preincubated with highly specific collagenase has revealed that platelets adhere to the microfibrils of the elastic lamina. To certify that an interaction between microfibrils and platelets can occur, microfibrils from two different origins were isolated: placental microfibrils extracted from the villi of human placenta, and aortic microfibrils extracted from adult bovine aorta. Both preparations were histologically homogeneous, and differed in their amino acid composition with an acidic character more pronounced for placental than for aortic microfibrils. Both preparations were able to induce platelet aggregation in plasma, but not after platelet isolation and resuspension in buffer. An interesting feature was the fact that when normal platelets were isolated, washed and resuspended in plasma from severe VWD patients, they were not aggregated by placental or aortic microfibrils. This defect was corrected after perfusion of cryoprecipitate to one patient. Moreover, monoclonal antibody directed against platelet glycoprotein Ib inhibited the aggregation of platelets to microfibrils, not to collagen; this suggested that an axis platelet GPI-FVIII/VWF-microfibrils could represent a pathway for platelet/subendothelium interaction. The adhesion of platelets to collagen seems to involve the staggering of a short amino acid sequence along a collagen fibre. This possibility arises from the requirement for the preservation of the quaternary structure of collagen in the induction of platelet adhesion/aggregation in vitro, and also from the identification and synthesis of a nonapeptide derived from type III collagen, which is also to specifically inhibit the aggregation of platelets by collagen, following its binding to platelet membrane.

Animals↗
PubMed1979

[Isolation and composition of plasma membranes of bovine glomerulus].

Plasma membranes of Beef kidney glomeruli were prepared by ultracentrifugation on a discontinuous sucrose density gradient. They were characterized by specific marker enzyme activities and electron microscopy morphological studies. Amino acid composition revealed a high amount of hydrophobic residues. Carbohydrate amount was found to be as high as 8.9 p. cent of the dry weight.

Amino Acids↗
PubMed1979

[Assay of "pregnancy alpha 2 glycoprotein" in the serum of prostatic cancer patients and changes during estrogen therapy].

Preliminary results are presented after measuring Pregnancy alpha 2 glycoprotein (P.A.G.) in a series of healthy males and those with cancer of the prostate, some of whom were being treated with oestrogens. Serum P.A.G. levels were measured in 21 patients with cancer of the prostate to observe any changes occurring during treatment with oestrogens. There was no significant difference between the P.A.G levels in healthy males and those with untreated prostatic cancer. Treatment however causes increased P.A.G. levels with wide individual variations. There is no apparent relationship between P.A.G. levels and the tumor stage, or efficacy of treatment. A relationship does exist however between the curves of serum P.A.G. levels in pregnant women and patients with prostatic cancer treated with oestrogens. Until proved otherwise, these measurements are of no practical value in patients with prostatic cancer, and future confirmation of these results by the study of a larger number of cases would be of value only in that they avoid other teams from repeating the same investigations.

Aged↗
PubMed1977

[Isolation of structural glycoproteins from human placenta].

Microfibrils about 100 A wide are isolated by mechanical procedures (sieving and ultrasonic disintegration from villosities of human placenta. Amino acid and carbohydrate compositions seem to be related to structural glycoproteins described before in connective tissues.

Amino Acids↗
PubMed1976

[Intraepiploic pancreatic autograft in dogs. Blood sugar changes as compared with a group of pancreatectomized dogs].

The authors used the omentum to envelop thin pancreatic fragments (10 to 18 g. i.e. 1/3 to 1/2 of the canine pancreas). After control of the blood sugar, a total corporo-caudal pancreatectomy was carried out in 21 dogs within 1 to 5 months. Nine survivors from one week to 3 months, permitted them to control the course of the blood sugar with biopsies of the graft and the absence of residual pancreas in the duodeno-hepatic region at autopsy. Compared with a comparative series of 11 dogs which survived total pancreatectomy and required 8 to 22 units of long-acting insulin, the series with autotransplants within the omentum, showed a moderate increase in blood sugar (1,1 to 1,1 g/l). However, progressive or acute cachexia with digestive disorders, frequently fistula of the sub-cutaneous graft were observed. In spite of the progressive and attenuated character of the diabetes, the preservation of secreting endocrine pancreatic islets is only temporary as shown by the histological controls.

Animals↗
PubMedDate not supplied

[Hepatitis B vaccine: characterization of the polypeptides of hepatitis B surface antigen (author's transl)].

In order to realize a new kind of hepatitis B vaccine, the polypeptide components of the outer-coat of the hepatitis B virus have been studied. The characterization of the polypeptides of purified hepatitis B surface antigen (HBsAg) was performed by SDS-polyacrylamide gel electrophoresis. Seven polypeptides were observed, designated P1 to P7, according to their increasing molecular weight: P1 (MW = 24,000), P2 (MW = 32,500) and P6 (MW = 78,000) represented the major components. When the reducing action was increased and followed by alkylation and citraconylation, a single polypeptide of low MW (5,000 less than MW less than 10,000) was isolated from HBsAg.

Electrophoresis, Polyacrylamide Gel↗