Hypocrellins as photosensitizers for photodynamic therapy: a screening evaluation and pharmacokinetic study.

Hypocrellin compounds were selected as potential photosensitizers for photodynamic therapy (PDT) owing to their high quantum yields of singlet oxygen (1O2), and facility for site-directed chemical modification to enhance phototoxicity, pharmacokinetics, solubility, and light absorption in the red spectral region, among other properties. Parent hypocrellins A and B share an absorption peak at 658 nm. These molecules may therefore be considered useful progenitors of derivatives which absorb more strongly in the red, considering that the ideal sensitizer should absorb in the 650-800 nm range, beyond the absorption range of hemoglobin and melanin, and where light penetration in tissues is maximized through reduced scattering. A series of pure, monomeric hypocrellin derivatives was tested for properties of dark cytotoxicity and photosensitizing potential by clonogenic assay in monolayer cultures of EMT6/Ed murine tumor cells. Their respective toxicities are reported on a molar basis. The in vitro screening assay has, to date, resulted in the selection of four hypocrellin derivatives for further development as photosensitizers for PDT. Cellular uptake for photosensitizing doses of selected compounds was determined by fluorimetry. Dose escalation studies in rodents indicate that potentially photosensitizing doses promote no demonstrable systemic toxicity.

Prostate cancer in Canada.

The early detection and treatment of men with prostate cancer is a complex and urgent challenge faced by most of the worlds' nations. In Canada, its significance is increasing in parallel to that of the United States. With increasing incidence, the implications for intervention in terms of quality of life and the utilization of health care resources must be continually reassessed. In this article, the epidemiology and the screening of prostate cancer as it pertains to Canadian men and the Canadian Health Care system are discussed.

A review of 1486 transurethral resections of the prostate in a teaching hospital.

The authors reviewed retrospectively 1486 consecutive transurethral resections of the prostate (TURP) gland performed in a teaching hospital between 1985 and 1987. The death rate was 0.8% in an institution where senior residents were the primary resectionists in approximately 75% of TURPs. The results of this review are compared with those of a 1974 study of 2223 patients. They indicated that TURP was a reasonably well-tolerated surgical procedure in the training environment and was associated with lower mortality and morbidity and a shorter hospital stay for the patient than in the 1974 study. The authors believe that with proper supervision and instruction, resident urologists can obtain satisfactory results while gaining competence and experience in performing TURPs.