2'-deoxyguanosine oxidation is associated with decrease in the DNA-binding activity of the transcription factor Sp1 in liver and kidney from diabetic and insulin-resistant rats.

Over the years, several lines of evidence have emerged supporting the role of oxidative stress in the development of diabetic complications. This could involve the increase in the production of reactive oxygen species and the decrease in antioxidative defense systems. Modulation of the level of intracellular reactive oxygen species is likely to affect the intracellular redox homeostasis, which is crucial for numerous biological events such as the transcriptional activation of genes. In this work we studied the binding of the redox transcription factors Sp1 and NF-kappaB extracted from kidney and liver of streptozotocin diabetic (STZ) and fructose-fed rats using electrophoretic mobility shift (EMSA) assay. In addition, the level in 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) was assessed within DNA by high performance liquid chromatography with electrochemical detection (HPLC-EC). A decrease in the affinity of Sp1 to DNA was observed in the kidney of STZ rats and fructose-fed rats (15% +/- 8.3 and 54% +/- 6.9, respectively, versus control group set to 100%). This was also found to occur to a lower extent, in the liver. Interestingly, higher levels of 8-oxodGuo, a biomarker of DNA oxidation, were measured in the kidney of diabetic rats. Therefore, the modification in the binding efficiency of Sp1 or NF-kappaB could be related to reactive oxygen species-mediated DNA damage.

Therapeutic response to taxol of six human tumors xenografted into nude mice.

To test the antineoplastic activity of taxol, a natural product isolated from yew (Taxus baccata L.), six human tumors transplanted into athymic mice were used (primary tumors of breast, endometrium, ovary, brain, lung and a recurrence of tongue tumor). While the growth rates varied with the histopathological characteristics of different tumor types, all mice were treated at a mean tumor volume of 200 +/- 8 mm3. Taxol was given SC at a dose level of 12.5 mg/kg per injection per day for 5 consecutive days out of 7 over a period of 3 weeks. With this schedule antitumor responses were obtained in all of the six neoplasms xenografted into nude mice. In the case of the ductal carcinoma of the breast total tumor regressions were observed in four of the five treated animals. In the five other experimental models taxol produced significant growth delays. We believe that the results of these initial tests on the nude mouse--human tumor xenograft system are convincing and justify clinical assessment of this drug.

Modulation of natural killer cell functional activity in athymic mice by beta-carotene, oestrone and their association.

In athymic mice, Natural Killer (NK) cells influence the take rate and growth of human malignant tissue xenografts. To confirm preliminary results, comparative experiments were conducted to study the effects of beta-carotene, oestrone and their association on the cytolysis mediated by spleen NK cells from athymic mice receiving these different treatments. Target cells consisted of YAC-1 malignant cells. With a 65% increase of cytolysis (ratio effector/target 50:1), beta-carotene induced a significant activation of NK cells (p < 0.002). This effect could be attributed to its antioxidant properties and confirmed by a moderate increase in erythrocyte glutathione peroxidase activity. On the contrary, oestrone resulted in a significant decrease of cytolysis (p < 0.001). In this case, the prooxidant properties of oestrone could explain its effect on NK cells and agree with the increase of intracellular reduced glutathione level observed. When mice received the combination beta-carotene-oestrone, their opposite effects on NK cell activity were counterbalanced, leading to a moderate change of cytolysis.

In vitro comparative study of cytolysis mediated by natural killer cells towards malignant cells preincubated with antioxidants.

We have previously reported that antioxidants such as beta-carotene, were able to enhance cytolytic activity of NK cells. The aim of the present study was to investigate whether preincubating YAC-1 tumor cells in culture with different antioxidants, affected their NK cell-mediated cytolysis. The antioxidants studied were enzymes (superoxide dismutase and catalase), hydroxyl radical scavengers (thiourea, mannitol, dimethyl sulfoxide) and a singlet oxygen quencher: beta-carotene. After 24 hours coincubation with the antioxidants, radiolabeled YAC-1 cells were submitted to the cytotoxic activity of NK cells for a 4 hour period. For some antioxidants, a moderate increase of cytotoxic potential occurred for weak NK cell number. By contrast, a clear decrease of cytotoxic potential was induced with high NK cell number. An antioxidant, with a protective effect which appeared stronger was thiourea, which induced 20, 58 and 36% decrease of cytolysis in the effector-target ratios 50:1, 100:1 and 200:1 respectively. These studies suggest that the malignant YAC-1 cells are vulnerable to treatment by different antioxidants.

Effects of selenium supplementation on malignant lymphoproliferative pathologies associated with OF1 mouse ageing.

Low plasma selenium (Se) levels have been shown to correlate with increased cancer incidence in humans and in mice. This study was undertaken to investigate the ability of Se to decrease mortality rate and tumor production in ageing mice. Se (2.5 ppm) given as sodium selenite in drinking water to 8 months old OF1 mice, for 4 consecutive months, reduced significantly the mortality of mice with 6% and 50% mortality rate for Se and control groups, respectively. In addition 80% of control deaths resulted from a lymphoid cell neoplasma, while no one of Se supplemented mice produced tumor. Evaluation of parameters of free radical metabolism showed highly significant reduction of the antioxidant defence system in the liver of cancer mice, with a 78% decrease in GSH-Px activity, a 65% decrease in superoxide dismutase (SOD) activity, a 75% decrease in the GSH/GSSG ratio and a 62% decrease of plasma Se level, as compared to healthy old mice. Nevertheless in the conditions of our experiment, Se didn't really improve the endogenous antioxidant status of ageing mice.

Amplification of oncogenes in lung carcinoma grafted in nude mice.

Seven lung carcinomas were grafted on nude mice and continuously propagated as in vivo models on which the amplification of 9 oncogenes (N-myc, v-erb A, v-abl, v-sis, c-myc, c-myb, v-Ha-ras, c-Kiras, and v-scr) was studied by Southern blot hybridization. Only c-myc was amplified (20 copies) in an adenocarcinoma. The presence of 2 bands at 9 kb and 6.6 kb in addition to the normal 12.7 kb in EcoR1 digested DNAs suggested a polymorphism of the c-myc gene in this tumor. The other 8 oncogenes were not amplified in this tumor. The 5 small cell lung carcinomas of this study did not show any amplification of any of the 9 oncogenes tested.

Antineoplastic activity of two taxol derivatives on an ovarian tumor xenografted into nude mice.

In order to compare the antineoplastic activities of taxol A, taxol B, a mixture of the two (taxol A 72%) and vinblastine, a human ovarian tumor serially transplanted into 104 female athymic mice was used. In the first experiment (11th passage), the antineoplastic activities of taxol A, taxol B and the mixture taxol AB were tested. The same dose was used in each case (12.5 mg/kg i.e. 1/20 of the evaluated LD50 value). It was administered subcutaneously for 5 consecutive days. Three courses of treatment were performed, with 2 rest periods of 1 week in between. All the taxol derivatives produced a statistically significant delay in the tumor growth. However, taxol B had the lowest chemotherapeutic response. In the second experiment (18th passage), different dose levels were administered (mixture 12.5 mg/kg/day x 4 - taxol A 8.8. mg/kg/day x 4 - taxol B 3.5 mg/kg/day x 4 - vinblastine 0.5 mg/kg/day x 2). For all the taxol derivatives 4 treatment courses with 3 rest periods of 4 days were used, and for vinblastine 4 treatment courses with 3 rest periods of 1 week. At the end of the second experiment, vinblastine, taxol A and a mixture of the two showed similar significant activity, whereas no objective antitumor response was observed following the taxol B treatment at the dose level chosen. The experimental results obtained clearly demonstrate that, in the taxane system, the greatest degree of antineoplastic activity can be attributed to taxol A.

Effect of oestrone on the natural killer (NK) cell activity, antioxidant status and tumour growth in athymic mice xenografted with human tumours.

Natural killer (NK) cells have been described as being very sensitive to oxidative stress. Thus it has been previously shown that chronic administration of oestrone in drinking water of athymic mice xenografted with a wide variety of human tumours, increases their growth and development. In this study an investigation was made to see whether oestrone supplementation could influence the NK cell activity by changes in the antioxidant defences which result in an oxidative stress and influence the proliferation of tumours. Supplementary oestrone was administered in drinking water of athymic mice xenografted with two different human tumours which lack oestrogen receptors: a bladder carcinoma and a small-cell lung carcinoma. The growth of the urothelial carcinoma was poorly affected by oestrone, but oestrone significantly (p<0.01) increased the proliferation of the small-cell lung carcinoma. The average uterus weight was increased by 62% in oestrone treated mice with no modifications in plasma zinc and selenium status, nor in erythrocyte copper zinc superoxide dismutase level. Nevertheless a slight decrease in erythrocyte glutathione peroxidase activity was noted. Trace elements and antioxidant enzymes in liver homogenates remained unchanged. Oestrone treatment also had no effect on plasma and liver lipid peroxides. The immune response was evaluated by measuring NK activity of splenocytes against 51Cr labelled YAC-I target cells. A 35.5% decrease in the NK activity (p<0.001) was observed after oestrone treatment and may be responsible for graft tolerance. However, the results of these experiments seem to exclude the role of oxidative stress in the modulation of NK activity.

Comparative distribution of beta-carotene and lycopene after intraperitoneal administration in mice.

To determine the kinetics of accumulation of beta-carotene and lycopene, and their main storage sites, they were separately administered in OFI mice at a single dose of 10 mg/kg body weight or in combination. Animals were sacrificed at given time intervals after intraperitoneal administration and carotenoids were dosed in serum, liver, spleen, kidneys and lungs. A single injection of beta-carotene led to a serum peak at t = 2 h and high levels were detected in the liver after 0.75 hours and in the spleen after 5 hours, with peak values of 10.46 +/- 0.62 and 134 +/- 6 micrograms/g tissue respectively. In contrast, lungs and kidneys did not appear as main accumulation sites. After administration of the carotenoid association, beta-carotene distribution in the four organs was strongly inhibited by lycopene. Concerning lycopene distribution, the concentration values were lower than beta-carotene, the spleen and liver remaining the main storage sites. After administration of a combined dose carotene/lycopene, the percentage of lycopene distribution inhibition was lower compared to the beta-carotene distribution inhibition induced by lycopene. This unusual and non-physiological way of administration for micronutrients leads to high levels of beta-carotene and lycopene in the liver and spleen, and seems of interest in the experimental study and understanding of the biomolecular mechanisms of their activities when administered alone or together.

Effects of free and liposome-encapsulated taxol on two brain tumors xenografted into nude mice.

Free taxol and liposome-encapsulated taxol were compared for their antitumoral activities on two human brain tumors serially grafted into female athymic mice in the scapular region. In the first experiment, a human glioblastoma (15th and 16th passages) was studied. In the second experiment, a fast growing human gliosarcoma (19th passage) was used. Free taxol and liposomal taxol were administered intraperitoneally, at the same dose; 12.5 mg/kg (i.e. 1/15 of the evaluated LD 50 value). In the first experiment, the treatment was performed for four consecutive days, with four courses separated by three rest periods of three days in between. Both free taxol and encapsulated taxol produced a statistically significant delay in tumor growth, and at the end of the experiment some total tumor regressions were obtained. However, liposomes were observed to be more effective in their action on the two consecutive passages of the glioblastoma, giving a marked increase of the number of total tumor regressions. In the second experiment another schedule of treatment was chosen because of the fast growth pattern of the xenografted human gliosarcoma: free taxol and liposome-encapsulated taxol were administered for five consecutive days and three courses of treatment were performed with two rest periods of two days. The two forms of taxol had a significant inhibitory effect on gliosarcoma tumor growth; as before encapsulation in liposomes was found to increase the anti-tumoral activity of taxol, although, in this case no tumor regression was observed.

Beta-carotene enhances natural killer cell activity in athymic mice.

To study the effects of beta-carotene on Natural Killer (NK) cells, we chose athymic mice whose spleens have a higher percentage of NK cells than conventional mice. Preliminary studies conducted with beta-carotene given intraperitoneally to athymic mice xenografted with a small-cell lung carcinoma resulted in a slight but significant antiproliferative effect (unpublished observations). We speculated that such an activity of beta-carotene was related to its immunostimulating properties. NK cell activity in ungrafted athymic mice as influenced by beta-carotene was studied. Mice received beta-carotene intraperitoneally. Splenic NK cells were labelled with monoclonal antibody and numeration was completed by measurement of their functional activity against YAC-1 malignant cells with a 51Cr release assay. In addition, splenic lymphocytes were evaluated for their reduced glutathione (GSH) content. There was a non-significant increase in the number of NK cells in the spleen, however their killing capacity was significantly (p < 0.01) enhanced after beta-carotene treatment. Also the GSH content of splenic lymphocytes was significantly higher in beta-carotene treated mice. Comparison of the average body weights of treated animals and of their respective controls showed that treatment had no adverse effects.

Antioxidant status and lipid peroxidation in athymic mice xenografted with two types of human tumors.

Antioxidants and reactive oxygen species are considered to play an important role in experimental in vivo carcinogenesis studies. We attempted in this study to evaluate the repercussions on the antioxidant and lipid peroxide status of the growth of human malignant tumors xenografted into athymic mice. We selected three tumor models: two urothelial carcinomas (bladder tumors stage 3) and one brain tumor (glioblastoma stage 4). All these tumors exhibited a fast growth pattern when xenografted into athymic mice. Tumoral tissue was implanted subcutaneously. After growth establishment each tumor size was measured at regular intervals: every 2 d for bladder tumor and twice a week for glioblastoma. The period of observation was 3 wk for bladder tumors and 5 wk for glioblastoma. At the end of the observation period, all mice were sacrificed; tumoral tissue was taken and blood collected. Superoxide dismutase activity (SOD), glutathione peroxidase activity (GSH-Px), zinc (Zn), selenium (Se), and thiobarbituric acid reactive substances (TBARS) were measured in blood. TBARS alone were measured into tumoral tissue. A modification of the antioxidant blood status was observed in mice xenografted with bladder tumors with decrease in Se status and GSH-Px activities, and increase in TBARS. Such an effect was absent in mice xenografted with glioblastoma. It would appear that an oxygen-mediated stress exists in the animal bearing an implanted tumor compared with the control group, and that tumoral tissue itself is able to induce an oxidative stress into its host. All this leads to a disturbance of the antioxidant defense system.

[Comparison of the clinical effects of propofol and methohexital in induced abortion]. / Comparaison des effets cliniques du propofol et du méthohexital au cours des interruptions volontaires de grossesse.

The clinical effects of propofol and methohexitone were compared in a group of 59 women undergoing abortion under general anaesthesia. At induction, the premedicated patients were given 2.5 mg . kg-1 propofol or methohexitone, followed by 1 mg . kg-1 fentanyl; if necessary, extra bolus doses of hypnotic were given. Hiccups and other movements were more frequent with methohexitone. There was no difference between the two groups as for injection pain and apnoea. The quicker recovery with propofol, with a mean of 2 min less, even when extra doses were given, could be explained by the pharmacokinetics of the drug. However, the quality of recovery in either group was satisfactory for short-length anaesthesia.

[3 experimental models applied to the study of urothelial tumors of the bladder]. / Trois modèles expérimentaux appliqués à l'étude des tumeurs urothéliales de vessie.

Three important models can be used in experimental carcinogenesis: Clonogenic assays which can be used to study tumor cells in vitro. This method is particularly useful in order to investigate biochemical markers and chromosomal spreads. Chemically-induced bladder tumors in various animals are used to analyse the mechanisms of induction and development of these cancers. The athymic mice have provided, over the last twenty years, an immunological system suitable for the heterotransplantation of human tumor tissues. These three experimental models, which are complementary, are reviewed and discussed.

[Myocardial metabolism after one hour of anoxia and deep generalised hypothermia. Experimental study in the dog (author's transl)]. / Métabolisme du myocarde après une heure d'anoxie et hypothermie profonde généralisée. Etude expérimentale chez le chiot.

Fifteen young dogs weighing less than six kilograms underwent circulatory arrest for one hour and profound hypothermia with extra-corporeal circulation. During reperfusion, myocardial metabolism was studied by comparing the oxygen arterio-venus (02 A-V) difference and lactate consumption at different temperatures. As the myocardial temperature rose, 02 A-V difference increased from 4 vl/100 cc at 25 degrees C to 10 vol/100 cc and K1 lactate balance rose from -19,3% to + 8% which indicates a large increase in lactate consumption. This study shows that profound and generalized hypothermia ensures good myocardial protection during at least one hour of ischemia. This experimental study confirms results obtained with other forms of cardiac hypothermia.