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Biomedical subjects

R Ross

Publications and source records attributed to R Ross.

At least 433 records · Page 24Linked to original sources
PubMed1974

The effect of complement depletion on wound healing.

The role of the complement system in nonspecific inflammation was investigated by depleting guinea pigs of serum complement with cobra venom factor (CoF). The progress of wound healing was compared in decomplemented and control animals which received buffer and no CoF. When wound tissue sections were assessed at 12 hours after wounding, no morphologic differences were observed between experimental and control wounds. Quantitation of 24-hour wound exudates by a point volumetric method revealed a 50% reduction in infiltrating polymorphonuclear neutrophilic leukocytes (PMN) in the absence of complement. A smaller decrease in mononuclear leukocytes (MNL) was seen. Red cells occupied four times as much space in the experimental wounds at 24 hours. In 48-hour wounds, PMN were still 50% of controls, but were near control levels at 72 hours. Despite the decreased influx of PMN, wound debridement and subsequent fibrogenesis proceeded as in the controls. No differences were seen in fibroblast proliferation, connective tissue formation or capillary regeneration. These results suggest that the complement system is not a primary mediator of inflammation following a nonimmunologic stimulus.

Animals↗
PubMed1973

Smooth muscle regeneration in the ureter. Electron microscopic and autoradiographic observations.

The cellular events taking place during reconstitution of the rabbit ureteral wall following resection of a portion of its circumference were studied utilizing electron microscopy and autoradiography. It was shown that hyperplasia takes place in the smooth muscle of the ureteral remnant during the first 2 postoperative weeks and that spindle-shaped cells possessing the ultrastructural characteristics of myoblasts migrate from the edges of the remnant into the defect, resulting in regeneration of the muscularis within 5 to 6 weeks of the time of injury.

Animals↗
PubMed1972

Experimental arteriosclerosis. I. Fibrous plaque formation in primates, an electron microscope study.

Arteriosclerotic lesions have been produced in monkeys (Macaca nemestrina) by selective removal of the vascular endothelium with an intra-arterial balloon catheter. Immediately after de-endothelialization a platelet layer covers the denuded area. This thrombus is gradually removed and by 7 days the vessel appears to be largely reendothelialized. Beginning at day 4, smooth muscle cells undergo modification and migrate through fenestrae in the internal elastic lamina into the intima where they proliferate. By 28 days, the intimal lesion consists of multiple layers of smooth muscle cells surrounded by collagen and elastic fibers and basement-like material. After 3 months the lesions are markedly hyperplastic and contain new extracellular connective tissue elements. In contrast, with no further injury after 6 months the lesion has decreased markedly in size suggesting that it may be reversible in the absence of continued endothelial injury. The importance of endothelial "injury" exposing medial smooth muscle to plasma constituents may be the principal factors associated with the migration and proliferation of the smooth muscle cells into the intima resulting in the lesion. The smooth muscle cells do not contain lipid. The similarities of this lesion to the fibromusculo-elastic lesion or preatherosclerotic intimal hyperplasia in man makes it a useful model for the further study of atherosclerosis.

Animals↗
PubMed1972

The neutrophilic leukocyte in wound repair a study with antineutrophil serum.

The role of the neutrophilic leukocyte in wound healing was investigated by observing the progress of repair in the absence of these cells. Circulating neutrophils were eliminated in guinea pigs by the administration of antineutrophil serum (ANS) 24 hr before wounding and by daily injections throughout a 10 day period of healing. Control animals received normal rabbit serum at the same dose levels and times. The wounds consisted of six linear incisions in the dorsal skin of the animals.The contents of 24-hr neutropenic and control wounds were compared by quantitating the major cellular and extracellular wound components using a histometric technique. At 24 hr, there were no differences between control and neutropenic wounds in the per cent of total wound volume occupied by mononuclear leukocytes and fibrin. The neutropenic wounds had no neutrophils, had a significantly decreased volume of fluid space, and an increased volume of red cells, as compared with controls. The differences in numbers of erythrocytes and amount of fluid space in these two sets of wounds may be related to substances within neutrophils that promote lysis of erythrocytes or affect vascular permeability. In spite of the lack of neutrophils in the ANS-treated animals during the 10 days of healing, no differences were observed between the control and neutropenic wounds relative to the rate of wound debridement or the extent of repair. The wounds from the two groups of animals were identical in cellularity and degree of connective tissue formation. These observations support the notion that neither wound debridement nor the formation of granulation tissue are dependent upon the presence of neutrophils. A neutrophil response in early wounds is not an essential antecedent to the infiltration of monocytes, as suggested by previous investigations.

Animals↗
PubMed1971

The smooth muscle cell. I. In vivo synthesis of connective tissue proteins.

These studies have examined the ability of smooth muscle cells from developing aorta of the prepubertal rat to utilize amino acids in the synthesis and secretion of connective tissue proteins. Prepubertal rats, previously given either an alcohol carrier or estradiol-17-beta, were each given an intravenous injection of proline-(3)H. The animals were sacrificed after 15 and 30 min, and 4 hr. Light and electron microscope radioautographs of the aortic smooth muscle and of the myometrial cells demonstrated that the aortic cells, in both groups of animals, and the myometrial cells, in the estrogen-stimulated animals, took up the proline and rapidly secreted it in both collagen and elastic fibers within 4 hr. In contrast, the myometrial cells of the nonstimulated animal took up relatively small amounts of proline and retained most of the amino acid within the cells. Electron microscope radioautographs demonstrated that the organelles involved in this activity were the rough endoplasmic reticulum and Golgi complex together with peripheral elements, presumed to be small vesicles. These studies have demonstrated that the smooth muscle cells of the developing aorta and of the estrogen-stimulated myometrium have a capacity to synthesize and secrete proteins associated with the extracellular connective tissue matrix.

Animals↗
PubMed1971

The smooth muscle cell. II. Growth of smooth muscle in culture and formation of elastic fibers.

Smooth muscle derived from the inner media and intima of immature guinea pig aorta were grown for up to 8 wk in cell culture. The cells maintained the morphology of smooth muscle at all phases of their growth in culture. After growing to confluency, they grew in multiple overlapping layers. By 4 wk in culture, microfibrils (110 A) appeared within the spaces between the layers of cells. Basement membrane-like material also appeared adjacent to the cells. Analysis of the microfibrils showed that they have an amino acid composition similar to that of the microfibrillar protein of the intact elastic fiber. These investigations coupled with the radioautographic observations of the ability of aortic smooth muscle to synthesize and secrete extracellular proteins demonstrate that this cell is a connective tissue synthetic cell.

Amino Acids↗