Radiosensitivity: Gender and Order of Administration of G-CSF, An Experimental Study in Mice.

To elucidate the potential influence of stimulating bone marrow before cell-cycle-dependent irradiation, we sought to determine overall survival in mice receiving total-body irradiation (TBI) when administered granulocyte stimulating factor (G-CSF) at different time points. Gender differences were also studied. C57/BL/6J mice, aged 9-14 weeks, received 8 Gy TBI in a perspex cage using a linear accelerator. In each of five different experiments, three groups were studied: 1. one control group receiving TBI only; 2. one group treated with filgrastim [500 lg/kg subcutaneously/intraperitoneally (s.c./i.p.)] the day before TBI, followed by daily filgrastim injections postirradiation (1-5 days); and 3. one group treated with daily filgrastim injections only post-TBI (1-5 days). Each experimental group included male and female mice. Survival of the mice was monitored daily, and mice were euthanized when their condition deteriorated. A total of 293 mice were monitored for at least 37 days post-TBI. Control mice that received 8 Gy TBI showed a significant gender difference, with a median survival of 22 days in females and 17 days in males. Addition of G-CSF, irrespective of pre- or postirradiation, significantly improved survival, but in males the improvement was significantly better when G-CSF was not given before TBI. Improved survival in females was independent of the order of administration of GCSF. Multiple filgrastim injections were more effective than a single injection, and s.c. administration was not better than i.p. In conclusion, these findings indicate that male mice are more sensitive to TBI than females. Filgrastim improved survival in both genders irrespective of whether given pre- or postirradiation, but in males the improvement was significantly less if an injection was given before irradiation. These results suggest that, to prevent toxicity most effectively, GCSF should not be given before cytotoxic therapy. While a completely different experimental model was used here, these results may also be extrapolated to indicate that endocrine cell-cycle suppression therapy should not be given before or during cytotoxic therapy of hormone-dependent tumors (e.g., breast and prostate cancer), thus a reduction in the efficacy of cell-cycle-dependent therapy can be prevented.

Early disturbance of microvascular function precedes chemotherapy-induced intestinal injury.

Intestinal injury 4-48 hr after cytotoxic therapy (etoposide phosphate, 100 mg/kg body weight [bw], intravenously [i.v.]) was studied in rats using ligated intestinal loops. Chromium-51 ethylenediaminetetraacetic acid ((51)Cr-EDTA) and rubidium-86 chloride ((86)RbCl) were deposited intraluminally to determine the extent of the increase in intestinal permeability and ion channel disruption. Evans Blue (EB) was used for detection of endothelial leakage. Intestinal morphology was documented. Endothelial dysfunction, as observed by an increased extravasation of EB, was evident already 4 hr after cytotoxic therapy. Intestinal epithelial injury, as observed by an increase in (51)Cr-EDTA permeation and a decrease in (86)Rb absorption, occurred after 48 hr. Finally, histology disclosed a reduced crypt cell proliferation, displayed as a decrease in Ki67-positive cells. The findings suggest that, in the development of intestinal injury after cytotoxic therapy, endothelial disruption is an early event, whereafter epithelial dysfunction and crypt stem cell arrest occur. This knowledge could be of importance in the design of future intervention trials.

Radio-and chemotoxicity in mice during hypothermia.

BACKGROUND: The influence of hypothermia induced by chlorpromazine (10-15 mg/kg given intra-peritoneally) on the survival from radiation and chemotherapy exposure in C57B1-mice, with or without tumour inoculation, was studied. MATERIALS AND METHODS: The mice were exposed to either whole body irradiation (8 Gy), or doxorubicin (15 or 17.5 mg/kg i.p.), or cisplatin (20 mg/kg i. p.) and followed to ensuing death. The control mice maintained a rectal temperature of 38 degres C while those receiving chlorpromazine developed moderate hypothermia of 28 degrees C or 36 degrees C, dependent on the ambient temperature. RESULTS: Hypothermia of 28 degrees C protected the mice from radiation-induced death and acute doxorubicin toxicity, with males gaining more protection than females. The effects appeared dependent on temperature, not on chlorpromazine. Hypothermia protected the mice from acute cisplatin toxicity and increased the anti-tumour effects in both genders. Chlorpromazine itself did not cause toxicity, neither did it change the natural course of tumour progression. CONCLUSION: Hypothermia of 28 degrees C induced by chlorpromazine profoundly reduces radiation, doxorubicin-and cisplatin-induced toxicity in mice with males benefiting more than females. The hypothermia itself, not the chlorpromazine, was responsible for these effects. The anti-neoplastic activity was not compromised; rather, it was enhanced, particularly for cisplatin.

Prevalence of Klinefelter's syndrome in male breast cancer patients.

Klinefelter's syndrome (KS, XXY) as a risk factor for developing breast cancer was evaluated in a retrospective study of 93 unselected male breast cancer patients from the Healthcare region of Western Sweden. Archival normal material from lymph nodes or skin and subcutaneous tissue was examined using the FISH (fluorescence in situ hybridisation)-technique. The best yield of intact nuclei was obtained from lymph node tissue. The prevalence rate of KS in males with breast cancer was found to be 7.5 per cent, a much higher rate than previously reported (approximately 3 per cent). Methodological differences are suggested to cause the increased prevalence rate. Based on our finding and on the prevalence of KS in the normal population as well as on the incidence of MBC, a 50-fold increased risk of developing breast cancer in males with KS relative to normal males was found. The same median age at diagnosis, 72 years, was established for both groups of patients. No differences in survival were seen.