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Biomedical subjects

R Marks

Publications and source records attributed to R Marks.

At least 343 records · Page 19Linked to original sources
PubMed1985

Truncated mu (mu') chains in murine IgM. Evidence that mu' chains lack variable regions.

Secreted IgM was shown to contain truncated mu (mu') chains with an apparent molecular mass of approximately 55 kD. The estimated percentage of IgM heavy (H) chains in the mu' form ranged from less than or equal to 1% in the case of one tumor IgM protein (104E) to greater than or equal to 30% in normal serum IgM. Serum mu' chains lacked antigenic determinants characteristic of immunoglobulin variable regions and showed a restricted isoelectric focusing pattern compared with that of conventional mu chains. Intracellular mu' chains were readily detected in bone marrow cells but not in spleen or lymph node cells; mu' chains were also detected in IgM-producing tumor cells and in a hybridoma cell line that deleted its productive mu allele. These results predict irregularities in IgM structure and recall an old controversy concerning the valence of IgM molecules.

Animals↗
PubMed1985

Solar keratoses. The association with erythemal ultraviolet radiation in Australia.

The prevalence rate of solar keratoses among 2000 residents of Melbourne, Australia, was compared to the rate among 2113 residents of Maryborough, a north central Victorian city. There was a significantly higher prevalence rate among the Australian-born population of Maryborough compared with Melbourne residents of the same age, sex, country of birth, and level of outdoor activity. Calculation of the erythemal ultraviolet radiation level revealed a 14.2% increase in the dose in Maryborough compared with that in Melbourne. These figures demonstrate a significant increase in the rate of solar keratoses, and thus the potential for the development of skin cancer, in all of the age groups studied. The difference was associated with a relatively small increase in ultraviolet radiation between two areas that are separated by a latitude distance of only 110 km.

Adult↗
PubMed1985

Methodologies to produce and assess standardized trauma to the skin.

In order to learn how mechanical trauma affects the skin, it is necessary to establish quantitative relationships between the degree of trauma and the extent of the biological response. This requires the development of novel techniques and instrumentation. In this paper, two new techniques for applying standardized increments of trauma to the skin are presented. Methods for measuring the effects on the skin surface and on skin function are described.

Adult↗
PubMed1985

Non-melanoma skin cancer and solar keratoses in Australia--a review.

Non-melanoma skin cancer and solar keratoses are common in Australia due to a combination of recent fashions in a predominantly fair-skinned population in intense sunlight. Between 2-3% of the population aged 40 years and over have at least one non-melanoma skin cancer, and more than 40% of the same population have at least one solar keratosis (the majority having more than one). Squamous cell carcinoma arising on sun-exposed areas has a significant rate of metastasis. The clinical diagnosis of these tumors is often inaccurate, and biopsy is essential to confirm all diagnoses of not only squamous cell carcinoma, but also basal cell carcinoma. Public education programmes are necessary to reduce the major public health problem that non-melanoma skin cancer currently presents in Australia.

Australia↗
PubMed1985

Effect of zinc pyrithione on mitotic activity in normal human skin.

Two concentrations (0.02% and 0.002%) of zinc pyrithione (ZPT) in water and a water control were applied to normal forearms - both on normal skin (six subjects) and also where the skin had been stripped to the 'glistening layer' (six subjects) with adhesive tape. Measurements of labelling index (LI), mean epidermal thickness (MET), mean stratum-corneum thickness (MSCT), total epidermal thickness (TET) and basal/granular cell ratio (B/G) showed no significant differences between the three treatments on normal skin or the parameters studied in stripped skin. It is concluded that ZPT has no effect on epidermal renewal in normal skin in vivo.

Adult↗
PubMed1985

Glucocorticoid-induced vasoconstriction in canine skin.

Vasoconstriction, manifest as a reduction in blood flow necessary to maintain a constant pressure, was observed over 4 h in the arteries supplying isolated abdominal skin flaps of greyhound dogs treated with intravenously administered betamethasone-17-valerate. Norepinephrine concentration-response curves performed initially and after 4 h showed no significant difference between the treated or control animals.

Animals↗
PubMed1985

Transplantation of human malignant and premalignant skin lesions of epidermis to nude mice.

Lesions of solar keratoses and squamous cell carcinoma maintained their histological appearance and an increased tritiated thymidine autoradiographic labelling index after being grafted on to nude mice. However, the values for their mean epidermal thickness and individual cell size appeared to decrease slightly during the 24-week period of study. As judged by the immunolocalization of involucrin antibodies, the grafts maintained a human epidermal antigenic profile. However, immunolocalization studies with HLA antibodies showed only a patchy positivity in the original premalignant lesions and were negative after grafting. These results indicate the potential value of the nude mouse as a model for studying the progress of premalignant and malignant skin lesions in an immunologically privileged non-human site and further indicate that solar keratoses can be maintained independently of systemic donor influences.

Animals↗
PubMed1985

Acute skin toxicity reactions in man--tests and mechanisms.

There is increasing concern to avoid toxicity reactions from materials that come into contact with the skin. In this paper the mechanisms underlying the commonest type of cutaneous toxicity, i.e. the dermatitis reaction, are discussed. The various tests that may be used to predict human cutaneous toxicity are reviewed, with emphasis on in vivo human toxicity tests. It is concluded that preliminary testing of potentially toxic materials should be conducted in vitro or, until such tests are available, in small mammals, but that definitive tests of finished products should be performed in vivo in man.

Animals↗
PubMed1985

Plantar hyperkeratosis: a study of callosities and normal plantar skin.

Although callosities of the plantar skin are common and often disabling, little is known of their pathology or the reasons for their persistence. In this study plantar epidermal structure and cell renewal were investigated in patients with callosities and normal, age-, sex- and site-matched control subjects. Tritiated thymidine autoradiographic labeling indices were increased in the calluses but the dansyl chloride fluorescence clearance time was prolonged, reflecting the increased thickness of the stratum corneum. The number of corneocytes that could be removed from the surface of callosities by a standardized stimulus was considerably increased compared to controls but after adhesive tape stripping no such increase was observed. The density of corneocytes as measured on Percoll gradients was decreased in corneocytes from callus compared to normal plantar skin, and their volume was increased. These observations suggest that there are differences in epidermal differentiation due to an increased rate of epidermal cell production in plantar skin affected by callosity.

Adult↗
PubMed1985

The effects of a shampoo containing zinc pyrithione on the control of dandruff.

Thirty-two subjects who suffered from dandruff participated in a study in which one-half of the head was washed with a shampoo containing 1% zinc pyrithione (ZPT) and the other half was washed with the same shampoo without ZPT. Four groups, eight subjects per group, were shampooed one, three, six or nine times (shampoo frequency twice per week). Clinical dandruff gradings of each half of the head were made 4 days after the last shampoo in each group, when scalp biopsy samples were also taken from each half of the head. Measurements of labelling index (LI), mean epidermal thickness (MET), and assessment of the numbers of PAS- and Gram-positive micro-organisms were made on the biopsy samples. There was a progressive reduction in dandruff on the sides of the head treated with the ZPT shampoo, the differences relative to the placebo-treated areas being statistically significant after three, six and nine washes. There were no significant differences in LI between treatment groups and the MET was shown to vary according to the treatment and the number of washes. There was a significant reduction in the number of PAS-positive micro-organisms (but not Gram-positive micro-organisms) on the ZPT-treated areas.

Cell Division↗
PubMed1985

Retinoid-induced inhibition of growth and reduction of spreading of human epidermal cells in culture.

The effect of various retinoids (retinol, all-trans-retinoic acid, etretinate, 13-cis-retinoic acid and an arotinoid, Ro-13-6298) on cultured human epidermal cells has been investigated. Cell growth was inhibited in a dose-dependent fashion by retinol, all-trans-retinoic acid and 13-cis-retinoic acid, but to a lesser extent by etretinate. The arotinoid showed an enhancing effect on cell growth. The area of cells on the culture dish was reduced by all the retinoids in a dose-dependent fashion, but the arotinoid was especially active in this respect even at very low concentrations. The measurement of cell volume by cell size frequency analysis, using a Coulter counter channelyzer, showed no differences compared with control cultures, and so the reduction of cell area was considered to be due to reduced 'spreading' of cells on the substrate. These results suggest that the retinoids interfere with cell-to-cell and cell-to-substratum attachment. It is possible that the change in membrane configuration is responsible for the inhibition of cell proliferation in our culture system.

Cell Adhesion↗