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Biomedical subjects

M H Flint

Publications and source records attributed to M H Flint.

13 recordsLinked to original sources
PubMed1988

Chondrons extracted from canine tibial cartilage: preliminary report on their isolation and structure.

We report on the morphology and structure of single and multiple chondrons isolated from homogenized samples of fresh and fixed canine tibial cartilage. Phase contrast, Nomarski, and scanning electron microscopy observations show each chondron to be composed of a chondrocyte and its pericellular matrix enclosed within a "felt-like" pericellular capsule. The extraction of intact chondrons from cartilage homogenates confirms the structural validity of the chondron concept and emphasizes the intrinsic mechanical strength of the capsule. Frayed collagen fibers radiate from multiple chondron columns suggesting a shear-resistant, structural interrelationship between capsular components and type II collagen fibers. Future development of chondron extraction procedures could provide a unique model with which to study the structure, biochemistry, and function of articular cartilage chondrocytes and their pericellular microenvironment.

Animals↗
PubMed1988

The efficacy of subcutaneous goretex implants in monitoring wound healing response in experimental protein deficiency.

This combined biochemical and histological study demonstrated that subcutaneously implanted Goretex tubing can be used to monitor and detect variations in wound healing potential in rats subjected to experimental hypoproteinaemic and normal refeeding conditions. Induced hypoproteinaemia was observed to be associated with a marked diminution in cellular infiltration, collagen synthesis and fibrous deposition within the implant. All these effects were completely reversed by subsequent refeeding of normal diet. Although regional variations in fibroblastic response attributable to biologic variability, were observed within individual control implants, or between paired controls, they were relatively minor as compared to the marked differences observed at the macroscopic, microscopic and biochemical level between implants removed from normally fed and protein deficient animals.

Animals↗
PubMed1987

Chondrons in cartilage: ultrastructural analysis of the pericellular microenvironment in adult human articular cartilages.

A combination of scanning and transmission electron microscopy was used to investigate the morphology and ultrastructure of normal human articular cartilage sampled from adult amputation specimens. This study confirms our previous observations on canine articular cartilage, which showed middle and deep layer chondrocytes surrounded by a pericellular matrix and enclosed within a pericellular capsule composed of filamentous and fine fibrillar materials. Pores in the "felt-like" organization of the capsular weave progressively decreased in size from the inner to the outer border of the capsule. Matrix vesicles were found embedded within the capsular weave and distributed throughout the territorial matrix. It is suggested that the chondrocyte, its pericellular matrix, and capsule together constitute the "chondron," a primary functional and metabolic unit of cartilage that acts hydrodynamically to protect the integrity of the chondrocyte and its pericellular microenvironment during compressive loading.

Adult↗
PubMed1986

The immunoperoxidase localization of type X collagen in chick cartilage and lung.

We have localized type X collagen in chick cartilage and lung by use of affinity-purified antibodies raised against the purified protein. Examination of the centers of primary endochondral development in the embryonic sternum, developing cartilage in the embryonic tubular bones and growth plate cartilages demonstrated the specific association of type X collagen with regions of hypertrophic chondrocytes in these tissues. Furthermore these studies revealed a tendency for type X collagen to accumulate adjacent to regions of active vascular invasion and an apparent lag between the initial intracellular accumulation and the matrix deposition of type X collagen. A lag in the matrix accumulation of type X collagen was also shown biochemically and immunohistochemically in chondrocytes in culture. In chick lung type X collagen was localized to the smooth muscle of the blood vessels and to smooth muscle surrounding alveolar ducts.

Animals↗
PubMed1979

The effect of charged synthetic polymers on proteoglycan synthesis and sequestration in chick embryo fibroblast cultures.

The polycation, poly(L-lysine), repressed the synthesis of glycosaminoglycans in secondary cultures of chick embryo skin fibroblasts and caused sequestration of glycosaminoglycans around the cells. The synthesis of chondroitin sulphate, dermatan sulphate, hyaluronic acid and a fourth component, thought to be heparan sulphate, were all inhibited to the same extent but the sequestration of the sulphated polymers were greater than that of the unsulphated. The sequestered material was retained around and not within the cells. Incubations with the polyanion, poly(L-glutamate), showed a slight stimulation of glycosaminoglycan synthesis and in these and control incubations (no additions to medium), most of the glycosaminoglycan synthesised appeared in the culture medium. The subsequent addition of poly(L-glutamate) to incubations containing poly(L-lysine) reversed the inhibitory and sequestering effect of the polycation. It was concluded that the inhibition of synthesis by poly(L-lysine) was either a direct effect of poly(L-lysine) on the cell membrane or a result of the high local pericellular concentration of sequestered proteoglycan.

Animals↗
PubMed1979

The development of the circle technique for determining the optimum line of tumour excision.

The healing of skin wounds is markedly influenced by their relationship to the tensional forces in the skin. Directional variations in skin extensibility which give rise to the cleavage line phenomenon and the skin tension lines are easily visualized by a recently developed skin marking technique. This technique makes it possible to plan accurately the optimum line of excision of skin tumours, including malignant melanomata, so as to allow primary linear wound closure without the necessity of undermining or grafting. The technique is particularly applicable to the excision of tumours of the back and limbs, and in addition, provides a warning if the local skin tensional state makes primary closure hazardous.

Dermatologic Surgical Procedures↗
PubMed1977

The proteoglycan content and the axial periodicity of collagen in tendon.

The glycosaminoglycan content and the axial periodicity of collagen was determined in various regions of the rabbit flexor digitorum profundus tendon. This tendon, which passes from the calf to the toes round the inner side of the ankle, contains a thickened sesamoid-like pad where it is subjected to friction and pressure. Other regions of the tendon are subject only to longitudinal tension. In tensional areas the axial periodicity of collagen was of the order of 62 nm and the tissue contained less than 0.2% proteoglycan on a dry weight basis. In the sesamoid-like region, however, the axial periodicity was a significant 13-15% less, and the proteoglycan constituted about 3.5% of the dry weight. Also, in the tensional areas the predominant glycosaminoglycan was dermatan sulphate, whereas in the sesamoid the predominant glycosaminoglycan was chondroitin sulphate. The possible interrelationships between collagen axial peroidicity and proteoglycan content in this tissue are discussed.

Animals↗
PubMed1977

The effect of centrifugal force on glycosaminoglycan production by aortic smooth muscle cells in culture.

Cultured smooth muscle cells from pig aorta subjected to centrifugation (48 h at 45 g over a 72-h period) increased their production of glycosaminoglycans by approximately 50%. The sulphated components, heparan sulphate, dermatan sulphate and chondroitin sulphate, showed a relatively greater increase than hyaluronic acid (66-34%). The results are consistent with the hypothesis that mechanical stress, such as hypertension, leads to increased accumulation of glycosaminoglycans in the aortic wall and that secondary trapping of lipoproteins by sulphated glycosaminoglycans produces atherosclerotic plaques.

Animals↗
PubMed1977

A comparison of the glycosaminoglycans of weight-bearing and non-weight-bearing human dermis.

Twenty-six samples of human skin from three non-weight-bearing and 27 samples from three weight-bearing sites were obtained at autopsy from 11 subjects varying in age from 4 to 91 years. The dermis was idssected free of other tissues and after proteolytic digestion, the glycosaminoglycans were isolated quantitatively by ion-exchange chromatography. Analysis of the preparations showed that there was significantly more glycosaminoglycan in the dermis from weight-bearing sites (p less than 0.001). The major glycosaminoglycans were hyaluronic acid and dermatan sulfate with chondroitin sulfate as a minor component, but the relative proportions of these components were not significantly different in the two sets of samples (p greater than 0.1). It is suggested that the quantity of glycosaminoglycan in the dermis is influenced by the functional requirements of the dermis at that site.

Adolescent↗
PubMed1976

Diagnostic parameters in experimental renal infection.

Urinary tract infections are commonly encountered in medical practice but their laboratory diagnosis presents many difficulties. In this study we have used experimental models to assess the value of serum antibody, urinary antibody, rheumatoid factor, and the histochemical examination of renal tissue as diagnostic parameters. Under the conditions of the experiment the analyses did provide useful diagnostic information and may prove to be of value in the management of urinary tract infection in man.

Animals↗
PubMed1975

The effect of dried mussel extract on an induced polyarthritis in rats.

A polyarthritis was induced in a number of rats by the intradermal injection of a modified Freund's adjuvant into the right foot pad. Powered extract of New Zealand mussel fed to the rats did not have any beneficial effect on either the development or the severity of the arthritis.

Animals↗