Lung tumour growth delay and normal tissue toxicity induced by three cytotoxic platinum drugs.

Single doses of the drug cisplatin and its analogues carboplatin and iproplatin were administered to tumour-bearing rats. The tumours used were two bronchial squamous cell carcinomas, that are part of a panel of experimental lung tumours developed at this institute. Cisplatin resulted in severe nephrotoxicity. Carboplatin and iproplatin were less nephrotoxic, but resulted in acute gastrointestinal and (probably) hematological toxicity. Carboplatin also caused late occurring liver damage. The responses of the tumours were compared at the level of maximum tolerated drug doses for early toxicity. The level of response was different for the two tumours. One was more sensitive to the drugs than the other. The effects of cisplatin and carboplatin were approximately similar. Iproplatin was less effective. Because cisplatin caused more severe late toxicity, it is concluded that carboplatin has the best therapeutic index for these two lung tumours.     

Hydroxyurea-induced cell death in human T lymphoma cells as related to imbalance in DNA/protein cycle and deoxyribonucleotide pools and DNA strand breaks.

The aim of this study was to elucidate the mechanism(s) behind the cellular toxicity of therapeutic concentrations of hydroxyurea (HU). Treatment of human T lymphoma cells (CCRF-CEM) with 60-100 microM of HU for 24 h decreased the growth rate by 90% due to accumulation of cells in early S phase. It induced a marked imbalance in both the DNA/protein cycle (as measured by two-parameter flow cytometry) and the deoxyribonucleotide (dNTP) pools. HU treatment did not enhance the frequency of DNA single-strand breaks (SSBs), as measured by the alkaline unwinding technique. Cell viability was unaffected. However, removal of HU led to 10-15% cell loss during the following 12 h period in parallel with increasing SSBs, and a rapid progression of cells through S and G2 stages. The unbalanced DNA to protein content per cell and the dNTP pools were normalized 6-12 and 24 h after removal of HU, respectively. These results show that marked changes in the DNA to protein ratio and dNTP pools alone are not directly lethal, but when combined with a high replicative DNA synthesis rate, as found after removal of HU, apparently lead to elevated cell death.     

Cell death in relation to cell cycle in a mouse ascites tumor growing in vivo after combined treatment with cisplatin and 5-fluorouracil

The interaction of 5-fluorouracil (5-FU) and cisplatin (CDDP) was studied in Bp8 ascites sarcoma cells growing in mice. By density gradient centrifugation in Percoll solution, non-viable cells were separated from viable cells. Single drug treatment with doses of 12 and 36 mg/kg body weight of 5-FU and 0.4 and 0.8 mg/kg body weight of CDDP did not yield non-viable cells during the time period studied (96 h). Combination of the drugs increased the non-viable cells to about 10-25% depending on the doses given. This indicates a supra-additive cytotoxic effect. Analysis of the distribution of viable cells in the different cell cycle phases by flow cytometry showed an accumulation of cells in the S-phase after 5-FU and in the S- and G2-phases of the CDDP or combined 5-FU-CDDP treatment. Similar analysis of non-viable cells showed a similar cell cycle distribution, which suggests that supra-additive cytotoxicity is not cell cycle specific. By labeling the DNA of the tumor cells with [125T]-deoxyuridine and using whole body measurement, the cell loss was studied. No changes in cells loss after single drug and combined treatment were found during the observation time. The molecular basis for the interaction between 5-FU and CDDP should be elucidated.     

Residual haemopoietic damage in the mouse after fractionated gamma-irradiation, down to 0.1 Gy per fraction

Residual damage in haemopoietic progenitor cell populations, spleen and granulocyte-macrophage colony-forming cells (CFU-S and GM-CFC) was detected in mice after 15 daily fractions where the dose per fraction was as low as 0.1 Gy. The injury was dose-dependent and after higher total fractionated doses of 7.5-10 Gy the CFU-S population recovered to about 50% of control between 2 and 12 months after irradiation. Residual damage was also detected in the stroma, in the form of reduced numbers of fibroblastoid colony-forming cells and of CFU-S in ossicles under the kidney capsule. The response to a second course of 15 fractions, given 3 weeks after the end of the first course, was similar and additive to the response to the first course in the short term. However, in the long term, recovery levels were similar after either one or two courses.     

Neuroendocrine responses to nicotine and stress: enhancement of peripheral stress responses by the administration of nicotine

Habitual smokers frequently report that when they are stressed smoking helps them to relax. One potential explanation for the reported stress ameliorating effect of smoking is that cigarette consumption (nicotine self-administration) may decrease the sympathetic autonomic nervous system activity which is associated with the stress response. In the present study, rabbits prepared with chronic vascular cannulae were used to study the effects of nicotine administation on plasma corticosterone, catecholamine (epinephrine, norepinephrine and dopamine) and glucose responses to physical restraint stress. Nicotine (0.025, 0.05 or 0.10 mg nicotine base/kg body weight) was administered for 10 days prior to the stress test to allow for the development of habituation/tolerance to its acute toxic effects. Independent administration of nicotine, or the application of the physical restraint stressor, resulted in increases in the plasma concentrations of corticosterone, epinephrine, norepinephrine, and glucose. Nicotine administration during restraint stress enhanced the increase in plasma corticosterone and epinephrine, as compared to the responses induced by either factor alone. The results suggest that the stress ameliorating effect of continued cigarette smoking, as reported by habitual smokers, is not due to a reduction in the activity of the peripheral sympathetic autonomic nervous system.     

20q13.2 Amplification in intraductal hyperplasia adjacent to in situ and invasive ductal carcinoma of the breast

The 20q13 region harboring recently described putative oncogenes is frequently amplified in invasive ductal carcinoma (IDC). The aim of this study was to examine the 20q13 copy number in intraduct hyperplasia (IH), atypical duct hyperplasia (ADH), and ductal carcinoma in situ (DCIS) adjacent to IDC. In 5 patients, comparative genomic hybridization (CGH) after laser microdissection revealed 20q13 amplification in four of five cases of IH, in all of three cases of IH with atypia, all five of DCIS, and all five of IDC. Fluorescence in situ hybridization (FISH) confirmed the amplification at 20q13.2 in IH in the two specimens analyzed. The amplification rate, however, was higher in DCIS and IDC. In phenotypically normal ductal epithelium normal values were found for 20q13 copy number by FISH (n=2) and CGH (n=5). Although the number of cases presented here is small, our results suggest that mutations in the 20q13.2 region in IH may be associated with accelerated proliferation and hyperplasia of the ductal epithelium. Progression to DCIS and ICD is accompanied by a further increase in the 20q13.2 copy number. Received: 17 March 1999 / Accepted: 22 June 1999     

In vitro andin vivo inhibition of virus multiplication by microwave hyperthermia

Summary The effects of microwave hyperthermia (41° and 43° C) on virus multiplication have been exploredin vitro (HSV-1 infected primary rabbit kidney cultures) andin vivo (mice infected with HSV-1 or vaccinia). In vitro the cells were inoculated with HSV-1 and heated to 41° or 43° C either before or after infection. Virus yields were significantly decreased when the cells were exposed to hyperthermia within the first few hours after infection, while hyperthermia was without effect when applied before infection or with several hours delay after infection.In mice inoculated intranasally with HSV-1, mortality due to herpes encephalitis was significantly reduced upon daily exposure to microwave hyperthermia from the day of infection onward.In mice inoculated intravenously with vaccinia, a significant decrease in the number of specific tail lesions was observed if the animals were exposed to microwave hyperthermia within the first three days after infection, while irradiation prior to infection or delayed until several days after infection did not exhibit an appreciable effect.Our data suggest that microwave hyperthermia interferes directly with the virus multiplication cycle bothin vitro andin vivo.With 3 Figures