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Biomedical subjects

A D Pearse

Publications and source records attributed to A D Pearse.

31 records · Page 2Linked to original sources
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

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↗
PubMed1984

The effect of povidone-iodine paint on fungal infection.

Povidone-Iodine (Betadine) Paint was used in thirteen patients with a proven fungal infection. Ten patients had pityriasis versicolor, two had trichophyton rubrum and one M. canis. In the pityriasis versicolor group, seven out of the ten patients were either improved or cleared up completely within 7 days. There were no adverse reactions in this group of patients and the material proved quite acceptable to them. Scanning electron micrographs were carried out on three of the patients and demonstrated the decrease in fungal elements after treatment and clinical improvement.

Humans↗
PubMed1983

Response of human skin to ultraviolet radiation: dissociation of erythema and metabolic changes following sunscreen protection.

After UV irradiation of human skin there is an increase in epidermal and stratum corneum thickness and an increase in the thymidine autoradiographic labeling index. Previously we have demonstrated that persistent exposure to ultraviolet radiation (UVR) alters the distribution and activities of glucose-6-phosphate dehydrogenase (G-6-PDH) and succinic dehydrogenase (SDH) within the epidermis; G-6-PDH activity is increased over the whole epidermis and SDH activity is diminished in the granular cell area but increased in the basal layer. When skin is protected by an efficient sunscreen and irradiated with UVB, there is almost complete inhibition of the erythema normally seen following UVR exposure. In this study we have investigated the cytochemical, cell kinetic, and histometric changes that take place in the epidermis after UVB irradiation, with and without two different types of sunscreen. Some of the histometric and metabolic changes associated with UVB exposure were still evident despite sunscreen protection and the successful blocking of the erythema response. The implications of these findings are discussed together with the use of sunscreens to prevent development of solar damage.

Adult↗
PubMed1978

A quantitative histochemical study of three oxidative enzymes in solar keratoses and Bowen's disease.

Succinate dehydrogenase (SDH), glucose-6-phosphate dehydrogenase (G6PDH) and lactate dehydrogenase (LDH) activities have been studied using quantitative enzyme histochemical techniques in the epidermis of five patients with solar keratoses and Bowen's disease. 'Non sun-exposed' buttock skin was compared with the skin from the actual lesion and adjacent, clinically normal paralesional skin. SDH activity was significantly increased in the basal layer and decreased in the granular layer in the epidermis of both lesion and paralesional skin, although the total epidermal activities were unchanged when compared to 'non-exposed' buttock skin. G6PDH activity was increased in the granular layer of paralesional epidermis and of lesions. No change in LDH activity was detected. Inclusion of phenazine methosulphate in the reaction mixtures resulted in a three-fold increase in formazan deposition without altering the localization. It is concluded that the quantitative changes and alteration in localization of SDH and G6PDH reported in solar keratoses are accompanied by similar changes in adjacent, clinically normal 'sun-exposed' skin and differ from normal 'non-exposed' skin. It is suggested that these changes may precede the development of the solar keratoses and that these findings may indicate a significant metabolic alteration in the events that lead to neoplasia.

Aged↗
PubMed1978

Quantitative changes in respiratory enzyme activity in premalignant lesions and experimentally irradiated skin.

Chronic exposure of human skin to solar irradiation results in a variety of preneoplastic and frankly neoplastic skin lesions. We have shown that in solar keratoses (SK) and in paralesional skin there is instead of an even distribution of succinic dehydrogenase (SDH) activity a relative decreased activity in the granular cell layer. Furthermore, there is enhancement of the usual concentration of glucose-6-phosphate dehydrogenase (G6PDH) activity in the granular zone as well as an increase in total G6PDH epidermal activity. In the experimental part of this study, six normal volunteer subjects had areas of normally non exposed skin (buttocks) irradiated with a 2 Mean erythema dose of ultra violet light (290--400 nm) on between 3 and 5 occasions per week for 2--6 week periods. The results obtained indicated that the same changes in enzyme activity localization take place in artificially irradiated normally non exposed epidermis as seen in normally exposed skin nearby actinic keratoses. It is suggested that these quantitative changes may be the basis of a model for the study of chronic ultra violet light damage to the epidermis.

Aged↗
PubMed1977

Actinic keratoses and the epidermis on which they arise.

The appearance of the epidermis and epidermal autoradiographic labelling indices were compared in actinic keratoses and paralesional skin in seventeen patients after injection of tritiated thymidine. The skin on the buttock area was also studied as a "non-sun exposed" control. Labelling indices obtained from skin removed after 1 hwere as follows: actinic keratoses 17-4%; paralesional skin 11-2%; buttock skin 5-4%. Many of the epidermal cells in the keratoses that incorporated tritiated thymidine were bizarre and not restricted to the basal or suprabasal regions but were scattered through the thickness of the epidermis. Paralesional skin also showed epidermal thickening and cytological abnormalities including the formation of multinucleate epidermal cells. These findings suggest that the development of actinic keratoses takes place in epidermis that is itself abnormal. The changes suggest that there is a gradual stepwise progression of sun damage epidermis via the clinically obvious keratosis to squamous cell epithelioma.

Autoradiography↗
PubMed1976

Further studies on section thickness measurement.

A rapid, simple, accurate and reproducible technique for measuring section thickness using an instrument known as a surfometer is described. It has shown that microtome settings cannot be relied upon as a means of monitoring the thickness of sections of quenched or wax-embedded tissue. However, there appeared to be a linear relationship between microtome setting and the thickness of dewaxed sections. Microtome settings seem to provide an accurate indication of the thickness of araldite sections.

Animals↗
PubMed1975

Surfometry. A method of evaluating the internal structure of the stratum corneum.

A method is described which enables measurement to be made of the roughness of the surfact of skin surface biopsies. The instrument used in this investigation has previously been employed to measure the degree of unevenness of metal and ceramic surfaces and is called a 'surfometer'. Using this technique the tracings that resulted from examination of normal skin, psoriasis and certain ichthyotic states could easily be distinguished. It was also demonstrated that there was a consistent pattern of change with increasing hydration of the stratum corneum in the absence of easily identifiable morphological alterations.

Adult↗
PubMed1974

Measurement of section thickness in quantitative microscopy with special reference to enzyme histochemistry.

Quantitative histochemical techniques demand constancy in sectioning tissue and preferably knowledge of the true thickness of a section. In this investigation a simple, rapid, accurate, and reproducible technique is described for measuring section thickness using an instrument known as a Surfometer. It has been shown that: (a) cryostat microtome settings bear little relationship to the true section thickness of the sections produced; (b) that different instruments differ in their inaccuracies; (c) that this inaccuracy varies slightly with different tissues.If densitometric methods are used and either the absolute amount of a tissue component is to be measured or the amount of a tissue component is to be compared in two tissues then it is mandatory to determine the actual thickness of the section. The method described here seems the most appropriate one for these investigations.

Animals↗
PubMed1972

Preparation of unfixed undemineralized bone sections: the Bright bone cryostat.

A bone cryostat is described with which cold sections of unfixed, undemineralized calcified tissue can be prepared. The bone cryostat is suitable for the preparation of the sections required for the histochemical and immunofluorescent study of bone, for electron microprobe analysis, and for bone and joint autoradiography with soluble compounds.

Alkaline Phosphatase↗