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J P Keene

Publications and source records attributed to J P Keene.

11 recordsLinked to original sources
PubMed1986

Dose-response relationships for photodynamic injury to murine skin.

Oedema and necrosis of murine tail skin have been measured after intravenous injection of haematoporphyrin derivative ("Photofrin", or PhI) followed 24 h later by graded exposures of the tail to full-spectrum visible light from a quartz-halogen lamp. End-points were degree of oedema and the proportion of mice in a dose-group that developed skin necrosis and tail atrophy. Oedema developed within 24 h of illumination and was a function of PhI dose and duration of light exposure. Onset of necrosis occurred after a minimum of 5 days and onset time was an inverse function of exposure time. Probit plots of proportion of necroses versus light exposure yielded values for ND50 (exposure corresponding to 50% incidence of necrosis) and l/slope. At the high but non-toxic dose of 2 mg PhI/mouse, ND50 was 18 min, l/slope 4 min, for pigmented BDF1 mice. Halving the PhI dose increased ND50 by a factor of 1.9. Albino BALB/c mice were markedly more sensitive to 2 mg PhI plus light than BDF1 mice: the ND50 was 7 min. Temporary occlusion of the blood supply to the tail (10 min before and during illumination) abrogated totally the oedematous and necrotic reactions to photodynamic therapy.

Animals↗
PubMed1984

A comparison of low and high dose-rate radiation for recipient mice in spleen-colony studies.

Over the last 15 years, endogenous spleen-colony formation in our mice, following lethal irradiation, has increased to an unacceptable level. It has been found necessary, therefore, to introduce a new method of preparing recipient mice for spleen-colony studies. Irradiation with low dose-rate 60Cobalt gamma rays has been compared with high dose-rate linear accelerator electrons, and their effects on endogenous spleen colony formation compared with earlier X and gamma ray dose-response data. It was found that a large dose (13.5 Gy) of gamma rays results in fewer endogenous colonies than 8.5 Gy of electrons, yet because of its low dose rate (14.1 X 10(-3) Gy/min) it has a marked sparing of the intestinal tissue as measured by the intestinal microcolony technique. This in turn permits better survival and, therefore, a 'healthier' animal for spleen-colony work. Exogenous colony formation is also lower in the low dose-rate, gamma-irradiated recipients and this is shown to be due to a reduced spleen-seeding efficiency. It is concluded that very low dose-rate radiation is preferable for haemopoietic ablation, that a mouse colony requires constant monitoring for changes of endogenous spleen-colony formation and that the spleen-seeding efficiency of CFU-s depends on the irradiation technique used--there is no absolute value for a given strain of mouse.

Animals↗
PubMed1980

A fluorescence polarization flow cytometer.

The effect of mitogens on the degree of polarization of the fluorescence from viable human lymphocytes, labeled with fluorescein, have been reported to be different in cells from subjects with malignant disease as compared with those from healthy donors. This has potential applications in the field of clinical diagnosis and a flow cytometer could be the instrument of choice for this purpose. We believe that such an instrument should be simple and easy to use and a flow cytometer was assembled with this in mind and with the object of gaining experience which would provide the basis for a future finalized design. The instrument is suitable for use in other biologic applications where polarization is of interest and also as a general purpose flow cytometer. Its main features, its characteristics and preliminary performance report are presented here.

Flow Cytometry↗