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Biomedical subjects

R Marks

Publications and source records attributed to R Marks.

At least 289 records · Page 16Linked to original sources
PubMed1988

Tissue measurements in senile sebaceous gland hyperplasia.

Senile sebaceous gland hyperplasia has been studied in 18 subjects in an attempt to shed some light on its pathogenesis. The sizes of different segments of the pilosebaceous unit were compared in senile sebaceous gland hyperplasia (SGH) and in control skin samples, using stereological techniques. The whole follicle was found to be significantly increased in volume compared with follicular structures in the control specimens. The size of differentiated sebaceous gland cells was found to be reduced compared with controls (490 +/- 72 microns 2 and 554 +/- 98 microns 2, respectively), but not significantly so. The mean tritiated thymidine autoradiographic labelling index determined in vitro was found to be decreased (5.42 +/- 1.79) compared with controls (7.48 +/- 2.44), but again, not significantly so. In addition the degree of solar elastotic degenerative change was found to be similar in SGH bearing skin compared with control samples. It is of interest that SGH and prostatic hypertrophy are exceptions to the usual atrophy of ageing and that both tissues are androgen dependent.

Aged↗
PubMed1988

Assessment of the duration of action of terfenadine on histamine induced weals.

In this study we aimed to quantify the reduction in area, perimeter and thickness of histamine induced weals 12, 18 and 24 h after a single oral dose of 120 mg terfenadine. Ten healthy volunteers were given 120 mg of terfenadine or placebo in a double-blind randomized two-period cross-over study. Twenty micrograms of histamine were then injected intradermally at 12, 18, and 24 h. The thickness of the resulting weal was measured by an A-scan pulsed ultrasound device. The area and perimeter of the resulting weal and flare were measured by tracing onto acetate sheets and using a digitizing tablet linked to a microcomputer. Just before each dose of histamine was injected, blood was taken to measure the level of the major metabolite of terfenadine. There was a significant difference between terfenadine 120 mg and placebo in the area and perimeter of the weal and the area and perimeter of the weal and flare at 12, 18 and 24 h, but no significant difference in weal thickness. Thus, terfenadine suppresses the wealing response caused by intradermally injected histamine over a 24 h period. It may be possible, therefore, to use a once daily dose of terfenadine.

Adult↗
PubMed1988

Relief of experimentally induced pruritus with a novel eutectic mixture of local anaesthetic agents.

The effectiveness of a eutectic mixture of the local anaesthetics lignocaine and prilocaine (EMLA cream) in relieving artificially induced pruritus was examined in 20 volunteers. The study was conducted in two parts. In part one, the effect of EMLA on the threshold concentration of histamine necessary to induce pruritus was assessed by a double-blind placebo controlled method. In part two, the effect of EMLA on the perception of pruritus induced by the artificial pruritogens cowhage and papain was assessed by a single blind method. Some subjects were less sensitive to histamine after placebo cream treatment, but all subjects showed a marked reduction in sensitivity to histamine after EMLA treatment. The difference between EMLA and the placebo treatment was statistically significant. The EMLA preparation was found to be effective in alleviating pruritus induced by cowhage and papain and this effect was also statistically significant. Thus, EMLA cream was found to be effective in reducing experimentally induced pruritus and, therefore, may be useful in some clinical circumstances where persistent itch is a distressing symptom.

Adult↗
PubMed1988

Structural determinants of the response of the skin to chemical irritants.

A study was made of the relationships between structural parameters of the epidermis and stratum corneum and the skin's sensitivities to chemical irritation by dithranol or ammonium hydroxide. Statistically significant positive correlations were found between the minimal blistering time to ammonium hydroxide and the area bounded by the skin surface contour line as determined by a skin surface replica technique. A significant positive correlation was also found between the minimal irritancy dose of dithranol and (a) the mean corneocyte area, and (b) the mean epidermal thickness in cell numbers. Mean corneocyte area was also found to increase with age and to be significantly less in UV-sensitive Types I and II subjects than in the relatively UV-insensitive Types III and IV subjects. These correlations are further evidence that there are inherent structural differences in the skin which influence the way the skin reacts to chemical trauma.

Adult↗
PubMed1988

Treatment of cutaneous neoplasia with etretinate in renal transplant recipients.

Six patients who had developed neoplastic and pre-neoplastic cutaneous lesions following a successful renal transplant were treated with etretinate, 1 mg/kg/day, for six months. In four cases there was almost complete resolution of the lesions; one patient had only a partial response, and one patient developed further lesions whilst on treatment. Patients were observed for six months after treatment was discontinued. Two patients in the group that had responded well to treatment developed further lesions. No deterioration in renal function, as measured by serial serum creatinine concentrations and creatinine clearance, occurred in any of the patients treated. In-vivo measures of the cutaneous cell-mediated immune response were unaltered, but cell kinetic studies demonstrated an increase in proliferative activity in sun-exposed skin during treatment, suggesting that the anti-tumour effect of etretinate is not due to a cytostatic action, and does not require an intact immune system. On the basis of our observations, we feel that further studies are warranted with larger numbers of patients.

Adult↗
PubMed1988

The relationship of basal cell carcinomas and squamous cell carcinomas to solar keratoses.

Six thousand four hundred sixteen people aged 40 years and over from three different locations in Victoria (Australia) were examined on the hands, forearms, head, and neck for the presence of solar keratoses and basal (BCCs) and squamous cell carcinomas (SCCs). Analysis of the relationship between these tumors revealed that the factors which predicted the likelihood of developing a solar keratosis were essentially the same as those that predicted the likelihood of developing a BCC and/or an SCC. These were age, sex, years of residence in Australia, indoor or outdoor occupation, tanning ability, propensity to sunburn, and location of residence. The presence of a coexisting solar keratosis was necessary for the development of an SCC in contrast to the development of a BCC. The findings suggest that unlike BCCs, the majority of SCCs in light-exposed areas may arise from preexisting solar keratoses. Whereas the prevalence of BCCs and SCCs was relatively constant in the three locations, the prevalence of solar keratoses differed markedly in direct relation to the degree of isolation. This suggests that solar keratoses are a more sensitive indicator of sunlight exposure than invasive carcinoma.

Adult↗
PubMed1987

Effects of all-trans retinoic acid on the morphology of human epidermal cells in vitro.

The effects of all-trans retinoic acid on human epidermal cell cultures were studied using ultrastructural techniques. Differentiation and stratification were reduced in retinoic acid treated epidermal cells. Treated cells developed a rounded appearance and seemed to contain more granules and vacuoles than usual. Desmosomes were not found in treated cells.

Cell Differentiation↗