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Biomedical subjects

S B Deak

Publications and source records attributed to S B Deak.

27 records · Page 2Linked to original sources
PubMed1989

The effect of viable omentum on early bile leakage and healing of liver lacerations.

In order to determine if omental tissue accelerates the healing of liver lacerations, simulated bile leakage and collagen biosynthesis were studied in 53 rabbits. After creating a standardized complex liver laceration, hemostasis was obtained by vessel ligation and electrocoagulation. The wound was either left open (OP) or viable omentum sutured to its base (OM). Simulated bile leakage was noted in all of eight animals (four OM, four OP) studied on day of injury. None of 18 OM and two of 17 OP animals demonstrated extravasation of dye from the wound on the second and third postinjury day (N.S.). The ratio of mRNA for alpha 1(I) procollagen/actin, used as an indicator of wound healing, was 56.3 +/- 7.8 for OM and 50.6 +/- 12.1 for OP at the wound edge, and 63.5 +/- 18.6 and 69.2 +/- 7.5, respectively, for RNA isolated from the scar (N.S.). For alpha 1(III) procollagen mRNA, the ratio was 23.9 +/- 3.5 for OM and 22.4 +/- 8.3 for OP at the wound edge, and 32.4 +/- 6.5 and 31.8 +/- 7.9, respectively, for RNA isolated from the scar (N.S.). There was no difference in the scar hydroxyproline content between the two repair methods. In this model of hepatic injury and repair, bile leakage was minimal by the second postinjury day with both repair methods. Placing the omentum in liver lacerations did not contribute to accelerated wound healing as measured by simulated bile leakage and collagen biosynthesis.

Animals↗
PubMed1988

Rat tropoelastin is synthesized from a 3.5-kilobase mRNA.

A lambda gt11 cDNA library was constructed from poly(A+) RNA isolated from aortic tissue of neonatal rats and screened with a human tropoelastin cDNA clone. DNA sequence analysis of several overlapping rat clones confirmed the presence of DNA sequences coding for murine tropoelastin and DNA sequences coding for the 3'-untranslated region of the rat tropoelastin mRNA. Northern blot analysis of total RNA from aortic tissue of neonatal rats using oligonucleotide probes derived from these rat tropoelastin cDNAs demonstrated the presence of a 3.5-kilobase tropoelastin mRNA. The size of this rat tropoelastin mRNA agrees with previous reports for the size of the mRNA coding for tropoelastin in tissue from several vertebrate species but contrasts with several reports suggesting the presence of a higher molecular weight mRNA species responsible for the synthesis of tropoelastin in rodent tissue.

Animals↗
PubMed1988

Increased elastin mRNA levels associated with surgically induced intimal injury.

Quantitative levels of mRNAs coding for elastin, types I and III procollagen and gamma-actin were measured in porcine vascular material following balloon catheterization. A balloon catheter was introduced into the thoracic aorta and jugular vein of 3-6 week old pigs; following distention and six days of postoperative recovery, tissue samples were obtained for histopathology, electron microscopy, RNA extraction and mRNA quantitation. Using a series of mammalian cDNA clones and the procedure of slot blot hybridization, we have shown that elastin and types I and III procollagen mRNA levels rose significantly during the postoperative period following vascular distention. The increase correlated with an increase in the cell mass present in both the venous and arterial intimal layers. Changes in gamma-actin mRNA levels were also associated with this rapid proliferative response but in arterial tissue only.

Actins↗
PubMed1987

Increased procollagen mRNA levels in carbon tetrachloride-induced liver fibrosis in rats.

Carbon tetrachloride-induced liver damage is a well-characterized experimental model for studying liver fibrosis. We used this model to examine alpha 1(I), alpha 1(III), and alpha 1(IV) procollagen mRNA levels during the development of liver fibrosis. Rats were given 0.5 ml of carbon tetrachloride/kg of body weight for 1-6 weeks. The liver tissue was assayed for collagen content by measuring total hydroxyproline content. Specific increases in procollagen mRNAs were assayed by slot blot hybridization. There was a significant increase in hydroxyproline content of liver tissue following 3 weeks of carbon tetrachloride treatment. The increase in tissue collagen content correlated with an increase in alpha 1(I) procollagen mRNA levels. At 5 and 6 weeks of treatment, there was an increase in alpha 1(III) procollagen mRNA levels. alpha 1(IV) procollagen levels increased slightly with five injections of carbon tetrachloride treatment. These results suggest that specific increases in procollagen mRNAs in liver fibrosis parallel, but do not precede, increases in tissue collagen content.

Animals↗
PubMed1986

The single copy gene coding for human alpha 1 (IV) procollagen is located at the terminal end of the long arm of chromosome 13.

Using dual-laser sorted chromosomes and spot-blot analysis, we have previously assigned genomic DNA sequences coding for human alpha 1 (IV) procollagen to chromosome 13 (Pihlajaniemi et al. 1985). By in situ hybridization to normal chromosomes and chromosomes with 13q deletions, we now report the localization of this gene to the terminal end of the long arm of chromosome 13. In addition, Southern and slot blot hybridization analysis clearly show that these genomic sequences are present only once per haploid genome.

Base Sequence↗
PubMed1985

Altered helical structure of a homotrimer of alpha 1(I)chains synthesized by fibroblasts from a variant of osteogenesis imperfecta.

Cultured skin fibroblasts from a variant of osteogenesis imperfecta were previously shown to synthesize a type I procollagen which was a homotrimer of pro alpha 1(I) chains. Trimers of alpha 1(I) collagen were isolated by pepsin digestion of culture medium from these fibroblasts. The amino acid composition of the isolated protein indicated that it contained an increased amount of hydroxylysine, apparently because of post-translational over-modification. The thermal stability of the alpha 1(I) trimers was examined by circular dichroism. We found no consistent difference in the melting curve of the alpha 1(I) trimers compared to control type I collagen. We next examined the thermal stability of the alpha 1(I) trimers using digestion with a combination of trypsin and alpha-chymotrypsin as an alternative probe of helical stability. When enzymatic digestions were carried out at 36 degrees to 40 degrees C, the alpha 1(I) chains in the trimers were cleaved to polypeptides which were shortened by approximately 100 amino acids. Vertebrate collagenase digestion of the shortened molecules indicated that the 100 amino acid segment removed from each alpha 1(I) chain was located at the carboxyl-terminus. The decreased thermal stability of the alpha 1(I) trimers was probably explained by the absence of alpha 2(I) chains in the molecules. The results, however, did not exclude the possibility that the post-translational over-modification of the alpha 1(I) chains contributed to the altered helical structure.

Cells, Cultured↗
PubMed1983

The molecular defect in a nonlethal variant of osteogenesis imperfecta. Synthesis of pro-alpha 2(I) chains which are not incorporated into trimers of type I procollagen.

Cultured fibroblasts were examined from a patient with a nonlethal form of osteogenesis imperfecta. As reported previously (Nicholls, A. C., Pope, F. M., and Schloon, H. (1979) Lancet 1, 1193), the cells synthesized and secreted a type I procollagen which lacked pro-alpha 2(I) chains and consisted of a trimer of pro-alpha 1(I) chains. No pro-alpha 2(I) chains were recovered from the medium under conditions in which nonhelical pro-alpha 1(I) and pro-alpha 2(I) chains were readily detected in the medium of normal fibroblasts incubated with the hydroxylase inhibitor, alpha, alpha'-dipyridyl. Examination of cellular proteins demonstrated that the fibroblasts synthesized both pro-alpha 1(I) and pro-alpha 2(I) chains. The cellular pro-alpha 2(I) chains did not, however, become disulfide-linked into dimers or trimers of pro-alpha chains. Since the association of pro-alpha chains during the biosynthesis of type I procollagen is directed by the conformation of the COOH-terminal propeptides, the data suggest that the pro-alpha 2(I) chains synthesized by the fibroblasts have a mutated structure in the COOH-terminal propeptides which markedly reduces their affinity for pro-alpha 1(I) chains. A further observation was that the ratio of newly synthesized pro-alpha (I):pro-alpha 2(I) chains in the patient's fibroblasts was 7.18 +/- 0.58 S.E. instead of the value of 2.25 +/- 0.16 S.E. seen in control fibroblasts. One possible explanation for the high ratio is that the proband is homozygous for a mutation altering the structure of the pro-alpha 2(I) chain and that a secondary effect of the structural mutation is a decreased rate of synthesis of pro-alpha 2(I) chains.

2,2'-Dipyridyl↗