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Biomedical subjects

R Penttinen

Publications and source records attributed to R Penttinen.

At least 73 records · Page 4Linked to original sources
PubMed1980

Collagen synthesis in granulation tissue formed in rats treated with female sex hormones.

In previous studies, we have shown that female sex hormones given in dosages corresponding to plasma levels in the last trimester of pregnancy retard collagen accumulation in early phases of experimental granulation tissue formation. Results of incorporation experiments using radioactive proline reported in this article indicate that this hormone treatment reduces general protein synthesis in granulation tissue and, even more markedly, the synthesis of collagen. Since collagen accumulation into granulomas is normal in the later phases of healing, it is suggested that hormone treatment not only decreases synthesis of collagen but also decreases breakdown of collagen. Hormone treatment did not affect the solubility of labeled collagen. No differences were observed in the synthesis of different collagen types. Under conditions when active collagen and protein synthesis occurs in the uterus and fetus, corresponding synthesis in other tissues is, thus, decreased. This may serve as an energy and protein saving function during pregnancy. The results may have applications for treatment of extensive scar formation.

Animals↗
PubMed1979

The healing of experimental fractures by compression osteosynthesis. II. Morphometric and chemical analysis.

The effects of rigid plate fixation on the structure and chemical composition of bones during healing of experimental fractures were studied by morphometric and chemical analysis at intervals of 3 to 24 weeks after attachment of six-hole AO plates to osteotomized rabbit tibiae. After fracture union gradual porotic transformation could be observed from 9 weeks onwards, with rapid excavation and breakdown of the cortical wall. During the study over 24 weeks the degree of porosity increased from 9.0 +/- 4.8 per cent to 37.5 +/- 10.2 per cent (P less than 0.001). This osteoporosis was accompanied by formation of new subperiosteal bone. The changes in the tubular bone led to a progressive increase in overall diameter and in the area occupied by the medullary cavity throughout the experiment. In the osteotomy area increased values were found for the content of hexosamines and the ratio of hexosamines to hydroxyproline at 3 weeks, indicating formation of connective tissue in the fracture area. Later on, no chemical signs of callus formation could be detected. In spite of the slight increase in the content by hydroxyproline, reflecting the formation of new bone subperiosteally, the chemical composition of the unresorbed cortical bone remained unchanged.

Animals↗
PubMed1978

Partial characterization of amyloid proteins in inherited amyloidosis with lattice corneal dystrophy and in secondary amyloidosis.

Amyloid fibrils isolated from two patients, one with inherited systemic amyloidosis and lattice corneal dystrophy, and the other with secondary amyloidosis due to chronic glomerulonephritis, were studied using immunologic, electrophoretic and chromatographic techniques. Amino acid hydrolysates of both amyloid types showed a high proportion of acidic and aliphatic amino acid residues but were non-identical in the overall amino acid composition. The preparations also contained 12--16% lipids. Guanidine hydrochloride denaturated amyloid fibrils of both types were resolved into four fractions in Sepharose 6B chromatography with molecular weights of ca. 160 000, 45 000, 20 000 and 8 000. The 160 000 mol. wt. fraction predominated in the chromatograms of inherited amyloid protein and was further resolved into two main fractions of 17 000 and 15 000 mol. wt. in sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. None of these fractions from inherited amyloid protein showed immunologic identity with tissue-derived amyloid protein A (AA) whereas all four fractions from secondary amyloid reacted against anti-AA antiserum. The three major Sepharose 6B fractions of secondary amyloid fibrils were resolved into a 25 000 mol. wt. fraction in SDS-polyacrylamide gel electrophoresis without urea but into a 12 000 mol. wt. fraction in gels containing 8M urea after more drastic dissolving conditions of the fibrils.

Adult↗
PubMed1978

Collagen types in early phases of wound healing in children.

Small silicone rubber tubes containing a standard size viscose cellulose sponge (Cellstic) were implanted in wounds of ten children at the end of surgery. The Cellstics were drawn out of the wound 24--120 hours after implantation and the cellulose sponges were sectioned and studied for collagen types. Immunologically detectable Type III collagen and procollagen was detected in the sponges 24--48 hours after implantation whereas Type I collagen was not found at that time. From hour 72 onwards a substantial increase in Type I collagen was noted, while the relatively low levels of Type I procollagen remained unchanged. The levels of Type III collagen and procollagen increased only slightly. Primary cultures from 9-day-old granulation tissue synthesized preferentially Type I collagen, on the basis of chromatographic analysis. We conclude that Type III collagen is produced at the earliest phases of wound healing by primitive mesenchymal cells followed by the production of Type I collagen after the appearance of mature wound fibroblasts.

Adolescent↗
PubMed1975

Patients with Ehlers-Danlos syndrome type IV lack type III collagen.

One of the genetically distinct collagens (type III) normally found in skin, aorta, and intestine is missing from the tissues of patients with the Ehlers-Danlos syndrome type IV. While skin fibroblasts from other individuals synthesize both types I and III collagen. Ehlers-Danlos syndrome IV cells synthesize only type I. These results suggest that the fragile skin, blood vessels, and intestines of Ehlers-Danlos syndrome IV patients result from an absence of type III collagen.

Amino Acid Sequence↗