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Biomedical subjects

N S Crowcroft

Publications and source records attributed to N S Crowcroft.

40 records · Page 3Linked to original sources

The spectrum of ocular toxocariasis.

Ocular toxocariasis is rare and therefore the spectrum of clinical disease is difficult to establish. We present a review of the clinical features and laboratory findings in a group of patients with positive Toxocara serology and ocular toxocariasis. The clinical spectrum was diverse and milder disease was commoner than might be supposed from reviews of the literature. Eosinophilia was unusual, but featured in two cases of unilateral pars planitis.

Adolescent↗

Responses of human cervical keratinocytes in vitro to tumour promoters and diethylstilboestrol.

We have compared the responses of normal human cervical keratinocytes (HCE) to diethylstilboestrol (DES), and the promoting agents, phorbol-12-myristate-13-acetate (PMA) and mezerein using the loss of cloning efficiency as a measure of terminal differentiation in vitro. Dose-response studies showed that normal HCE are growth inhibited by chronic exposure to DES at concentrations greater than or equal to 2.5 X 10(-5) M, to PMA at concentrations greater than 10(-8) M and mezerein at concentrations greater than 10(-9) M. Compared to acetone controls, promoter or DES-treated cells exhibited a 10- to 12-fold increase in cornified-envelope formation. Normal HCE exhibit a heterogeneous response to PMA in that 85-90% of colony-forming cells lose their colony-forming ability after a 24-h exposure to 10(-6) M PMA. The PMA-resistant subpopulation, PMAR, remains constant and is not reduced even after 96 h chronic exposure to PMA. In contrast, the colony-forming ability of normal HCE is almost totally suppressed after 24 h exposure to 10(-6) M mezerein. After 24 h incubation with 5 X 10(-5) M DES, 20% of normal HCE are capable of colony formation but this resistant fraction is eliminated after 96 h chronic exposure. Cornified-envelope formation was negligible in malignant cervical keratinocytes grown in the presence of DES or promotors and these cells were characterised by a very large PMAR fraction - 85 - 90% of cells retained colony-forming ability after exposure to 10(-6) M PMA for 24 h. Furthermore, 90-100% of malignant cervical keratinocytes retained their colony-forming capacity after exposure to 10(-6) M mezerein. However, colony-forming ability declined steadily in the presence of 5 X 10(-5) M DES and after 96 h only a tiny fraction, 1% of malignant cervical keratinocytes could form colonies on replating. The mechanisms by which DES inhibits growth and induces cornified-envelope formation in HCE would appear to be distinct from those activated by PMA and mezerein.

Carcinogens↗