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Biomedical subjects

A J Perejda

Publications and source records attributed to A J Perejda.

8 recordsLinked to original sources
PubMed1986

Skin, joint, and pulmonary changes in type I diabetes mellitus.

Three hundred seventy-five patients with diabetes mellitus were examined for the presence of sclerodermalike skin changes, limited joint mobility, and vital capacity changes. Nineteen percent of patients had vital capacities 2 SDs below the mean of predicted values. There was no significant relationship between decreased vital capacities and duration of diabetes, sclerodermalike skin changes, limited joint mobility, smoking history, proteinuria, or retinopathy. Cutaneous involvement consisting of thickening, tightening, and/or a waxy quality of the skin was noted in 190 patients (51%). The severity of skin involvement correlated positively with the patients' duration of diabetes, age, severity of joint contractures, and diabetic retinopathy. Thus, sclerodermalike skin changes appear to reflect generalized connective tissue alterations in diabetes and may indicate increased risk for diabetic microvascular complications.

Adolescent↗
PubMed1985

Altered steady-state ratio of type I/III procollagen mRNAs correlates with selectively increased type I procollagen biosynthesis in cultured keloid fibroblasts.

Regulation of collagen gene expression was studied in fibroblast cultures established from patients with keloids, fibrotic lesions of the skin. In selected keloid fibroblast cultures, an overproduction of type I procollagen was observed. This increase was accompanied by a parallel increase in type I procollagen-specific mRNA levels, as detected by dot-blot and RNA transfer hybridizations, without concomitant change in type I procollagen gene copy number. At the same time, type III procollagen mRNA levels were unaltered, resulting in markedly elevated type I/III procollagen mRNA ratios. Thus, keloid fibroblasts offer a unique model to study the independent regulation of the gene expression of two genetically distinct procollagens, type I and type III.

Cells, Cultured↗
PubMed1985

Marfan's syndrome: structural, biochemical, and mechanical studies of the aortic media.

An intrinsic defect in the aortic media in six patients with Marfan's syndrome, who died of cardiovascular complications of the disease at an average age of 32 years, has been delineated by correlated morphologic, biochemical, and mechanical studies. The findings in the Marfan aortas have been compared with those in age- and sex-matched controls, who died of unrelated diseases without significant aortic lesions, and in three patients with dissecting aneurysms of non-Marfan origin. The results showed that there was a significant reduction in the tensile strength of the aorta in Marfan's syndrome. This finding was correlated by scanning electron microscopy with structural alterations of the medial elastic fibers, including enlarged interlaminar spaces and loss of interlaminar elastic fibrils. No structural alterations were identified in collagen fibers. Biochemical analyses of the aortic media revealed a substantial reduction in aortic elastin content. Furthermore, the desmosine content of the isolated elastin was reduced by approximately 50%. No changes were detected in the composition or solubility of the medial collagen. In contrast to Marfan aortas, the elastin and collagen contents of the dissecting aneurysms of non-Marfan origin were similar to those of the controls. These findings suggest that the vascular complications in Marfan's syndrome may be based on a genetic abnormality affecting elastin fibrillogenesis.

Adult↗
PubMed1984

Nonenzymatic glucosylation of lysyl and hydroxylysyl residues in type I and type II collagens.

Nonenzymatic glucosylation of type I and type II collagens was examined by incubating collagen substrates with D-glucose in vitro. In one set of experiments, unlabeled collagen was incubated with [14C]-glucose and the incorporation of [14C]-radioactivity into protein was determined by TCA precipitation. The incorporation was dependent on the concentration of glucose and the time of incubation. The glucosylated product was also examined by SDS-polyacrylamide slab gel electrophoresis. The results indicated that both alpha 1(I)- and alpha 2(I)-chains of type I collagen were glucosylated and the glucosylation occurred both with native and denatured collagen as substrate. In further studies [3H]-lysine-labeled collagens were glucosylated, the products reduced by NaBH4, and the [3H]-lysine-derived residues were separated by amino acid analyzer. After a 144 h incubation in vitro, 18.9% of [3H]-lysyl residues and 36.5% of [3H]-hydroxylysyl residues in type I collagen were substituted with glucose. In contrast, 47.9% of [3H]-lysyl residues and 68.1% of [3H]-hydroxylysyl residues in type II collagen were glucosylated after 144 h incubation. Based on quantitative amino acid analyses of the substrates, these values represent 27.6 lysine plus hydroxylysine residues substituted per triple-helical type I collagen molecule and 65.3 residues per triple-helical type II collagen molecule. Thus, type I and type II collagens display differential susceptibilities to nonenzymatic glucosylation. Finally, [3H]-proline-labeled type I collagen was glucosylated to varying extents, and the glucosylated products were used as substrates for human polymorphonuclear leukocyte collagenase. No difference in susceptibility to this collagenase was noted, irrespective of the extent of glucosylation.

Amino Acids↗
PubMed1982

Elastin in diseases.

Previous morphologic observations have suggested abnormalities in the elastic fibers in a number of both inherited and acquired diseases. Recent progress made in understanding of the normal biology of elastin has allowed us to examine these diseases by biochemical means. In this review we are discussing the current status of the research on the elastin diseases with particular emphasis on clinical conditions affecting skin, as for example, cutis laxa, pseudoxanthoma elasticum, and the Buschke-Ollendorff syndrome. In addition, we present new data which appears to be the first demonstration of an elastin abnormality in the Marfan syndrome.

Connective Tissue Diseases↗
PubMed1982

Marfan syndrome. Demonstration of abnormal elastin in aorta.

Aortae from three patients with classic presentation of Marfan syndrome, who died of vascular complications, were subjected to biochemical analyses of the connective tissue; for comparison, aortae from eight age-matched controls, without evidence of connective tissue abnormalities, were examined. Elastin was prepared from the aortae by two techniques. First, the tissues were extracted with 5 M guanidine-HCl, bacterial collagenase digestion and reduction with dithiothreitol (elastin I preparation). Secondly, this material was further purified by extraction with 0.1 M NaOH at 99 degrees C (elastin II preparation). Amino acid analyses of both elastin preparations indicated that the values for desmosine and isodesmosine were reduced in Marfan cases to approximately one-half of the control values. A corresponding increase in lysyl residues was noted in elastin II preparations. Also, the concentration of elastin per milligram dry weight of tissue was reduced in Marfan cases. The hydroxyproline content of elastin was increased in two cases with the Marfan syndrome. Recoveries indicated that the alkali treatment solubilized 46.2% of the elastin I preparations in Marfan aortae compared with 23.7% in controls. In contrast to elastin, the concentration and solubility of collagen were unchanged; the amino acid composition and the genetic types of insoluble collagen isolated by limited pepsin proteolysis were the same in both Marfan and control aortae. The results of our study demonstrate that the cross-linking of aortic elastin is reduced in the three patients with Marfan syndrome. Thus, a defect in elastin could explain the vascular fragility observed clinically in these patients.

Adult↗
PubMed1982

Glycosylation of human glomerular basement membrane collagen: increased content of hexose in ketoamine linkage and unaltered hydroxylysine-O-glycosides in patients with diabetes.

To study the glycosylation of glomerular basement membrane collagen (GBMC) in diabetes, kidneys were obtained at autopsy from 5 patients with insulin-requiring diabetes of long duration and diabetic complications, and from 5 control subjects. Glomeruli were prepared by sieving and collagen was isolated by limited pepsin proteolysis followed by salt precipitations. Amino acid analyses of the collagen preparations, after acid hydrolysis, indicated a composition consistent with that of type IV collagen. No differences in the relative contents of various amino acids, and in particular, 3-hydroxyproline, 4-hydroxyproline and hydroxylysine, were noted between diabetic and control samples. Non-enzymatic glucosylation was assessed by measuring hexose in ketoamine linkage with thiobarbituric acid after conversion to 5-hydroxymethylfurfural. In 4 of the 5 patients studied, glucosylation values exceeded the mean +2 S.D. of the controls; in the fifth subject glucosylation was in the high normal range. No correlation between the severity of diabetes and hexose content of GBMC was noted, however. In further studies, enzymatic glycosylation of GBMC was assayed after alkaline hydrolysis by separation of glucosylgalactosyl-O-hydroxylysine, galactosyl-O-hydroxylysine, and unsubstituted hydroxylysine in an amino acid analyzer. No differences in the relative contents of hydroxylysine-O-glycosides were evident between diabetic and control GBMC. The results suggest that non-enzymatic glucosylation, but not glycosylation catalyzed by collagen glucosyl and galactosyl transferases, is increased in diabetes. The increased carbohydrate content of collagen may lead to decreased turnover and/or excessive accumulations of basement membrane collagen thus contributing to the vascular complications of diabetes.

Adult↗