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R L Trelstad

Publications and source records attributed to R L Trelstad.

At least 109 records · Page 6Linked to original sources
PubMed1973

Collagen synthesis in vitro by embryonic spinal cord epithelium.

Isolated spinal cords from chick embryos (stages 12 to 15) were incubated in vitro with radioactive proline. The proteins synthesized were fractionated by coprecipitation with added carrier collagen, followed by molecularsieve and ion-exchange chromatography. A portion of the isotopically labeled proteins were found to be collagen molecules consisting only of alpha1 chains.

Amino Acids↗
PubMed1973

A collagen defect in homocystinuria.

The biochemical mechanism accounting for the connective tissue abnormalities in homocystinuria was explored by examining the effects of various amino acids known to accumulate in the plasma of patients with this disease on cross-link formation in collagen. Neutral salt solutions of purified, rat skin collagen, rich in cross-link precursor aldehydes, were polymerized to native type fibrils by incubating at 37 degrees C in the presence of homocysteine, homocystine, or methionine. After the polymerization was completed, each sample was examined for the formation of covalent intermolecular cross-links, assessed indirectly by solubility tests and directly by measuring the cross-link compounds after reduction with tritiated sodium borohydride and hydrolysis. Collagen solutions containing homocysteine (0.01 M-0.1 M) failed to form insoluble fibrils. Furthermore, much less of the reducible cross-links, Delta(6,7) dehydrohydroxylysinonorleucine, Delta(6,7) dehydrohydroxylysinohydroxynorleucine, and histidino-dehydrohydroxymerodesmosine were formed in the preparations containing homocysteine as compared with the control and the samples containing methionine or homocystine. The content of the precursor aldehydes, alpha-aminoadipic-delta-semialdehyde (allysine) and the aldol condensation product, was also markedly diminished in tropocollagen incubated with homocysteine. It is concluded that homocysteine interferes with the formation of intermolecular cross-links that help stabilize the collagen macromolecular network via its reversible binding to the aldehydic functional groups. Analysis of the collagen cross-links in skin biopsy samples obtained from three patients with documented homocystinuria showed that the cross-links were significantly decreased as compared with the age-matched controls, supporting the tentative conclusions reached from the in vitro model studies. In addition, the solubility of dermal collagen in non-denaturing solvents was significantly increased in the two patients examined, reflecting a functional defect in collagen cross-linking. Although the concentration of homocysteine used in this study to demonstrate these effects in vitro is clearly higher than that which is observed in homocystinuric's plasma, the data do suggest a possible pathogenetic mechanism of connective tissue defect in homocystinuria.

Adult↗
PubMed1972

Collagen heterogeneity within different growth regions of long bones of rachitic and non-rachitic chicks.

The different anatomical regions involved in osteogenesis in the chick long bone have been examined for heterogeneities in collagen structure that might relate to the mechanism of ossification. Experimentally induced lathyrism was employed to enhance collagen solubility, and vitamin D deficiency to allow accumulation of osteoid, the precursor of bone matrix. The extractable lathyritic collagens of the cartilaginous and osseous regions of growing long bones from rachitic and non-rachitic chicks were examined for alpha-chain type and amino acid composition. In both groups of animals the growth plate and cartilaginous regions of the epiphysis gave collagen molecules of the constitution [alpha1(II)](3), whereas the ossifying regions contained [alpha1(I)](2) alpha2. The degree of hydroxylation of the lysine moieties was increased by approximately 50% in the alpha1(I)-chain and alpha2-chain of rachitic bone collagen. Since uncalcified osteoid is greatly enriched in rachitic bone, it is concluded that the collagen of osteoid has the configuration [alpha1(I)](2) alpha2, similar to that of bone matrix, but has an elevated hydroxylysine content. The possible relationship of this difference to the mechanism of calcification is discussed.

Amino Acids↗
PubMed1971

Morphogenesis of the collagenous stroma in the chick cornea.

The embryonic chick corneal epithelium produces a highly structured acellular matrix beneath its basal surface during early development. This matrix, which contains collagen, serves as a morphogenetic template for subsequent stromal development in that the three-dimensional architecture of the adult corneal stroma is initially established, in miniature, in this epithelially derived connective tissue. Examination of the early corneal epithelium and matrix in both the light and electron microscope suggests that self assembly of the matrix may be one of several important factors in the morphogenesis of this early connective tissue.

Animals↗
PubMed1970

The Golgi apparatus in chick corneal epithelium: changes in intracellular position during development.

The intracellular position of the Golgi apparatuses in the basal cell layer of the corneal epithelium in embryonic and hatched chicks has been studied in the light microscope by impregnating the Golgi apparatus with silver. During two distinct periods in development the Golgi apparatuses in the basal cells shift from an apical to basal position. Each of these periods correlates in time with the appearance of an acellular collagenous matrix beneath the epithelium. Examination of the basal epithelial cells in the electron microscope confirms the intracellular shifts in position of the Golgi apparatus. The results suggest that the Golgi apparatus shifts to the basal cell pole of the corneal epithelium in order to excrete connective tissue materials into the developing corneal stroma.

Animals↗
PubMed1970

Subcellular Localization of Salmonella enteritidis Endotoxin in Liver and Spleen of Mice and Rats.

Salmonella enteritidis(14)C-endotoxin was recovered predominantly from the nuclear and mitochondrial subcellular fractions of livers and spleens of mice and rats, 3.5 hr and 3 days after intravenous administration. Of the recovered radioactivity, 10 to 20% was present in the liver mitochondrial fraction as high-molecular-weight, biologically active material, suggesting the presence of intact endotoxin. Autoradiographic studies demonstrated nuclear and cytoplasmic labeling in the liver and at least nuclear label in spleen cells. The resistance of rats, as compared to mice, to the induction of amyloidosis does not appear to be based on a difference in subcellular localization of endotoxin within the reticuloendothelial system.

Journal Article↗