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Biomedical subjects

R M Hembry

Publications and source records attributed to R M Hembry.

79 records · Page 5Linked to original sources
PubMed1978

Destructive corneal disease in the connective tissue disorders. Comparison with an experimental animal model.

The corneo-scleral changes described are highly characteristic and may be the first signs of an underlying systemic disorder so that otherwise healthy patients who present with limbal guttering and scleral disease must be continuously monitored with this association in mind. The clinical and histological features of limbal guttering in connective tissue disorders strongly suggest that a local antigen-antibody reaction triggers off a number of biochemical and cellular responses which combine to produce lysis of scleral and corneal collagen, although immune complexes have not so far been demonstrated in these eyes. Modes of therapy aimed at one particular chain of events have varying degrees of success, as indeed does more blunderbuss treatment with steroids, anti-inflammatory drugs, or cytotoxic agents. The early stages of the ocular lesion in the rabbit are now being studied, as is the immunological basis for its production. It is hoped that further work with the animal model will lead to a deeper understanding of the pathogenesis of these conditions, which will turn provide both ophthalmologists and rheumatologists with more scientific guidelines for treatment.

Animals↗
PubMed1974

Comparison of the effects of vitamin A and its analogs upon rabbit ear cartilage in organ culture and upon growth of the vitamin A-deficient rat.

A study was conducted to explore the relationship between the effects of vitamin A upon cartilage and the biological role of vitamin A in maintaining growth and life. Retinol, retinoic acid, alpha-retinoic acid, and ROB-7699 (a cyclopentyl analog of retinoic acid) were highly effective in promoting the lysis of the extracellular matrix of cartilage grown in organ culture in vitro. Retinoic acid and its two analogs were quantitatively more active than was retinol in bringing about lysis of matrix and release of proteoglycan into the culture medium. A bioassay was then conducted to determine the ability of each compound to promote growth of vitamin A-deficient rats. In contrast to their effects upon cartilage, retinoic acid and its two analogs were considerably less active quantitatively than retinol in promoting growth of vitamin A-deficient rats. Moreover, the three acids tested showed graded biological activity in the growth bioassay, with alpha-retinoic acid showing reduced bioactivity (approx. one-fourth that of retinoic acid) and ROB-7699 being virtually inactive. The lysis of cartilage produced by these compounds was presumably caused by release of lysosomal enzymes as a result of the membrane-labilizing effects of the compounds. Thus, these membrane effects of the vitamin A-related compounds are poorly correlated with their biological growth-promoting activity. The alpha-ionone analogs of retinol and retinoic acid were able to maintain good health and growth of vitamin A-deficient rats, although their quantitative activity was low. Rats fed alpha-retinyl acetate showed high liver stores of alpha-retinyl esters and low levels of serum retinol-binding protein (similar to the levels seen in retinoic acid-fed rats). The biological activity of the alpha-ionone analogs was apparently not due to contamination with or conversion to the normal beta-ionone compounds.

Animals↗
PubMedDate not supplied

Secretion and localization of cathepsin D in synovial tissues removed from rheumatoid and traumatized joints. An immunohistochemical study.

The proteinase cathepsin D which degrades proteoglycan was never demonstrated in extracellular sites in tissues from patients with traumatized meniscoid cartilage, either before or after culture with an antiserum to human cathepsin D. In contrast, in synovia (but not usually cartilage) from the knees of 6 of 11 rheumatoid patients, extracellular cathepsin D was commonly detected by culturing tissues with an antiserum to this enzyme.

Animals↗
PubMedDate not supplied

Ultrastructural studies of corneal collagen during the development of experimental scleritis in rabbits.

An active Arthus reaction induced in the rabbit cornea leads to scleral disease resembling that in humans. Collagen damage was located in the corneal stroma at the site of the immune reaction. In the electron microscope, some regions of corneal stroma, without loss of lamellar integrity, demonstrated the apparent swelling of individual, scattered collagen fibrils such that a helical arrangement of component microfibrils was evident. In areas showing more extensive damage, fibril fragmentation and solubilization was associated with the aggregation of fibrous banded material. These observations are discussed with reference to possible mechanisms underlying the development of scleritis in the rabbit and which might also contribute to an understanding of the pathology of the disease in humans.

Animals↗