Correlation between cell survival, micronuclei-induction, and LDH activity in V79 cells treated with teniposide (VM-26) before exposure to different doses of gamma radiation.

The influence of teniposide (VM-26) treatment was studied on the radiation-induced alterations in cell survival, micronuclei (MN) formation and lactate dehydrogenase (LDH) release in V79 cells. Treatment of V79 cells with 10 nM teniposide before exposure to different doses of gamma radiation resulted in a significant decline in the cell survival when compared with the PBS + irradiation group. The decline in cell survival was dose related. The cell proliferation indices also declined in a dose-dependent manner in both PBS + irradiation and VM-26 + irradiation groups. The decline was higher in the VM-26 + irradiation group in comparison with the PBS + irradiation group. In contrast, the frequency of micronuclei increased in a dose-related manner in both PBS + irradiation and VM-26 + irradiation groups. However, the frequency of micronuclei was significantly greater in the latter group when compared with the former group at all the post-irradiation time periods studied. The LDH contents increased in a dose-dependent manner in both PBS + irradiation and VM-26 + irradiation groups at all the post-irradiation time periods evaluated. This elevation in LDH contents was significantly greater in the VM-26 + irradiation group in comparison with the PBS + irradiation group.     

Evaluation of teniposide (VM-26)-induced toxicity on mouse spermatogenesis by flow cytometry

Alteration in the testicular weight and various germ cell populations was studied in male mice treated with different doses (0.05, 0.25, 0.5, 1.0 and 2.0 mg/kg b. wt.) of teniposide (VM-26) at various post-treatment time periods. Treatment of mice with different doses of teniposide did not significantly alter the testicular weights, irrespective of the drug dose used. Flow-cytometric analysis of germ cells of the untreated control mice testes revealed four distinct DNA peaks corresponding to elongated spermatids (HC), round spermatids (1C), spermatogonia and non-germ cells (2C) and primary spermatocytes (4C). The region between 2C and 4C peaks represents cells that are actively synthesizing DNA (S-phase cells). Treatment of mice with different doses of teniposide resulted in a significant depletion in the relative percentage of spermatogonia from day 2 to 35 post-treatment depending on the drug dose. DNA-synthesizing, i.e. S-phase, cells declined significantly at day 1 post-treatment and continued to decline up to day 70 post-treatment for all the drug doses studied, except 2 mg/kg drug dose at day 28 post-treatment. A significant decline in the relative percentage of primary spermatocytes (4C) was observed at day 7 that continued up to day 70 post-treatment depending on the drug dose. Round spermatids (1C) declined significantly at day 21 post-treatment after administration of 0.25--2.0 mg/kg VM-26. The relative percentage of elongated spermatids showed a significant decline at day 28 after 1 and 2 mg/kg drug treatment. These alterations in different germ-cell populations are reflected in the various germ-cell ratios. The 4C:2C ratio showed a significant decline at day 7 and 14 post-treatment after 1 and 2 mg/kg VM-26 treatment, while the 1C:2C ratio declined significantly at day 21 post-treatment in the mice treated with 0.5 and 2.0 mg/kg of VM-26. 4C:S-phase and 1C:4C ratios increased significantly from day 1 to 70 post-treatment, depending on the drug dose. Our study demonstrates that the treatment of mice with low doses of VM-26 exerts cytotoxic effects on various germ-cell populations.     

Elevation of micronuclei frequency in mouse bone marrow treated with various doses of teniposide (VM-26)

The effect of various doses (0-10 mg/kg body wt.) of teniposide (VM-26) was studied on the induction of micronuclei at 12, 24 and 36 h post-treatment. The frequency of micronuclei (MPCE and MNCE) increased in a dose-dependent manner up to a dose of 0.3125 mg/kg VM-26, where a peak frequency of micronuclei was observed. A further increase in the drug dose resulted in the reduction in micronuclei frequency in comparison with 0.3125 mg/kg drug dose reaching a nadir at 10 mg/kg. However, it was significantly higher than DDW (double distilled water) treated controls. The pattern of micronuclei induction was similar for all the post-treatment time periods. The frequency of micronuclei also increased with scoring time and the highest frequency of micronuclei was observed at 24 h post-treatment, which declined thereafter without restoration to DDW treated control level. Conversely, the PCE/NCE ratio registered a dose-dependent decline after treatment of mice with various doses of VM-26. A peak decline was observed at a dose of 0.3125 mg/kg, thereafter the decline became consistently less resulting in an elevation in the PCE/NCE ratio in comparison with 0.3125 mg/kg VM-26.     

Correlation of micronuclei-induction with the cell survival in HeLa cells treated with a base analogue,azidothymidine (AZT) before exposure to different doses of gamma-radiation

The effect of 0.1 microM azidothymidine (AZT) a pyrimidine analogue has been studied on the growth kinetics, cell survival and micronuclei formation in HeLa cells exposed to 0, 0.25, 0.5, 1, 2 and 3 Gy of 60Co gamma-radiation. The AZT pretreatment resulted in a significant decline in the cell growth kinetics, cell survival and cell proliferation indices when compared with the PBS+irradiation group at 20, 30 and 40 h post-irradiation. Conversely, the frequency of micronucleated binucleate cells (MNBNC) elevated in a dose dependent manner in both PBS+irradiation and AZT+irradiation group. This elevation in MNBNC-induction was significantly higher in the latter when compared with the former group at all post-irradiation scoring time periods studied. The dose-response relationship for micronuclei induction for both the PBS+irrradiation and AZT+irradiation groups was linear. The biological response was studied by correlating the cell survival with MNBNC-induction. The cell survival and MNBNC-induction showed a close but inverse relationship and this relationship gave a best fit on the linear quadratic model.     

Effect of teniposide (VM-26) on the cell survival, micronuclei-induction and lactate dehydrogenase activity on V79 cells

The genotoxic effect of 0, 1, 5, 10, 25, 50 and 100 nM teniposide (VM-26) treatment was studied on cultured V79 cells. Treatment of V79 cells with different concentrations of teniposide resulted in a concentration-dependent decline in the cell survival and growth kinetics. VM-26 treatment also caused alteration in the cell proliferation kinetics as evidenced by the increase in the frequency of mononucleate cells, with a consequent decline in the frequency of binucleate cells in a concentration-dependent manner at all the post-treatment time periods. Exposure of V79 cells to different concentrations of VM-26 resulted in a concentration related elevation in the frequency of micronucleated binucleate (MN) cells. The frequency of MN was significantly higher in VM-26 treated cells than that of non-drug treated cells at all the post-treatment time periods. A peak frequency of MN was observed at 16 h post-treatment that declined thereafter. The release of lactate dehydrogenase increased with the increase in drug concentration and a maximum LDH release was observed at 0.5 h post-treatment after exposure to 10-100 nM VM-26. While a peak value was observed at 1 and 2 h for 5 and 1 nM VM-26, respectively. The biological response was evaluated by determining the relationship between micronuclei and cell survival. The cell survival declined with increasing MN frequency, resulting in a close but an inverse relationship between the cell survival and micronuclei-induction. The dose effect relationships for micronuclei induction, LDH release and biological response was linear quadratic.     

Enhancement of radiation effect by Aphanamixis polystachya in mice transplanted with Ehrlich ascites carcinoma

The effect of radiation on tumor tissue can be optimized by adding radiosensitizing agents, in order to achieve a greater degree of tumor damage than expected from the use of either treatment alone. The ethanolic extract of Aphanamixis polystachya (APE) was tested in Swiss albino mice transplanted with Ehrlich ascites carcinoma (EAC) and exposed to various doses of gamma-radiation. EAC mice received 0, 10, 25, 50, 75, 100, 150 or 200 mg/kg body wt APE before exposure to 6 Gy gamma-radiation followed by once daily administration for another 8 consecutive days post-irradiation. The optimum radiosensitizing dose was found to be 50 mg/kg APE that was further tested in EAC mice exposed to 0, 1, 2, 4, 6 or 8 Gy hemi body gamma-radiation. The best effect of APE and radiation was observed for 6 Gy gamma-radiation. The splitting of 50 mg into two equal fractions of 25 mg and administering the split dose with a gap of 8 h on 1, 3, 5, 7 or 9 d of tumor inoculation resulted in an increased survival even when the drug was administered at late stages (day 5) of tumor development. The APE treatment before irradiation elevated lipid peroxidation followed by a reduction in the glutathione contents. Treatment of tumor bearing mice with APE before irradiation further reduced the activities of various antioxidant enzymes like glutathione peroxidase, glutathione-s-transferase, superoxide dismutase and catalase at different post last drug administration (PLDA) times.     

Inhibition of radiation-induced clastogenicity by Aegle marmelos (L.) correa in mice bone marrow exposed to different doses of gamma-radiation

The frequency of micronucleated polychromatic (MPCE), normochromatic erythrocytes (MNCE), and polychromatic/normochromatic erythrocyte ratio (PCE/NCE), was studied in the bone marrow of mice orally administered with 0, 200, 225, 250, 275 and 300 mg/kg body weight of hydroalcoholic leaf extract of Aegle marmelos (AME). Treatment of mice with AME, once daily for 5 consecutive days, before exposure to 2 Gy resulted in a significant decline in the frequency of MPCE when compared to the non-drug-treated irradiated control. The greatest reduction in MPCE was observed for 250 mg/kg body weight AME, accompanied by the highest polychromatic erythrocyte to normochromatic erythrocyte ratio, in comparison with the non-drug-treated irradiated control. Therefore, further studies were carried out using this dose of AME, where the animals were administered with 250 mg/kg body weight of AME before exposure to 0, 0.5, 1, 2, 3 and 4 Gy of gamma-radiation and evaluated at 12, 24, 36 and 48 hours post-irradiation. Whole body irradiation of mice to different doses of gamma-radiation resulted in a dose-dependent increase in the frequency of MPCE at all post-irradiation times. Treatment of 250 mg/kg AME orally (p.o.) before irradiation significantly reduced the frequency of MPCE at all post-treatment times. The frequency of MPCE increased with time, reached a peak level at 24 hours, and declined thereafter. The occurrence of MNCE has also shown a pattern similar to MPCE, except that the MNCE frequency reached a peak level by 48 hours. The AME significantly reduced the frequency of MNCE at all post-irradiation times, when compared to the non-drug-treated irradiated group. Treatment of mice with AME before exposure to different doses of gamma-radiation resulted in the inhibition of a radiation-induced decline in the PCE/NCE ratio, when compared with the concurrent irradiated controls. To gain insight into the mechanism of action, AME was tested for its antioxidant effects in cell-free chemical systems using H2O2/FeSO4 to generate hydroxyl (*OH) radicals, which were measured by a fluorescent probe, 2V, 7V-dichlorofluorescin diacetate (DCFH/DA). Xanthine/xanthine oxidase was used to generate superoxide (O2*-) anion radical, which was measured by a fluorescent probe dihydroethidium (DHE). AME significantly reduced fluorescence in a concentration dependent manner, indicating its efficacy to scavenge free radicals. Our results demonstrate that one of the mechanism of reduction in the radiation-induced DNA damage in mice bone marrow by AME may be due to scavenging of free radicals and elevation in the antioxidant status, as previously reported.     

Preparation and characterization of teniposide PLGA nanoparticles and their uptake in human glioblastoma U87MG cells

Many studies have demonstrated the uptake mechanisms of various nanoparticle delivery systems with different physicochemical properties in different cells. In this study, we report for the first time the preparation and characterization of teniposide (VM-26) poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles (NPs) and their cellular uptake pathways in human glioblastoma U87MG cells. The nanoparticles prepared with oil-in-water (O/W) single-emulsion solvent evaporation method had a small particle size and spherical shape and provided effective protection against degradation of teniposide in PBS solution. Differential scanning calorimeter (DSC) thermograms concluded that VM-26 was dispersed as amorphous or disordered crystalline phase in the PLGA matrix. A cytotoxicity study revealed that, in a 24h period, blank PLGA NPs had no cytotoxicity, whereas teniposide-loaded PLGA NPs (VM-26-NPs) had U87MG cytotoxicity levels similar to free teniposide. Confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM) images showed the distribution and degradation processes of nanoparticles in cells. An endocytosis inhibition test indicated that clathrin-mediated endocytosis and macropinocytosis were the primary modes of engulfment involved in the internalization of VM-26-NPs. Our findings suggest that PLGA nanoparticles containing a sustained release formula of teniposide may multiplex the therapeutic effect and ultimately degrade in lysosomal within human glioblastoma U87MG cells.     

苯妥英钠对化学治疗耐药胶质瘤细胞内卡莫司汀和替尼泊苷药物浓度的影响

目的 研究苯妥英钠对化学治疗耐药人胶质母细胞瘤细胞(8-MG-BA)内卡莫司汀、替尼泊苷积聚浓度的影响.方法 实验细胞分为5组,H4细胞组、8-MG-BA细胞组、8-MG-BA+苯妥英钠5 mg,/L组、8-MG-BA+苯妥英钠10 mg/L组、8-MG-BA+维拉帕米5 mg/L组.采用高效液相色谱法(HPLC)检测各组细胞内卡莫司汀、替尼泊苷积聚浓度.采用外标标准曲线法,以药物的质量浓度(C)为横坐标、峰面积(A)为纵坐标进行线性回归计算,并测定仪器精密度与方法回收率.结果 吸收1、3h后,H4细胞组细胞内卡莫司汀、替尼泊苷含量均高于8-MG-BA细胞组[吸收1h后卡莫司汀浓度:(1.75±0.05)mg/L比(0.31±0.03)mg/L,吸收3h后卡莫司汀浓度:(1.70±0.03)mg/L比(0.39±0.04)mg/L,吸收1h后替尼泊苷浓度:(1.18±0.03)mg/L比(0.42±0.03)mg/L,吸收3h后替尼泊苷浓度:(1.09±0.04)mg/L比(0.46±0.03)mg/L,均P＜0.01];8-MG-BA+维拉帕米5 mg/L组、8-MG-BA+苯妥英钠5 mg/L组、8-MG-BA+苯妥英钠10 mg/L组细胞内卡莫司汀、替尼泊苷含量均高于8-MG-BA细胞组[吸收1h后卡莫司汀浓度:(0.56±0.04)mg/L、(1.10±0.12)mg/L、(1.37±0.04)mg/L比(0.31±0.03)mg/L,吸收3h后卡莫司汀浓度:(0.68±0.04)mg/L、(1.25±0.03)mg/L,(1.49±0.04)mg/L比(0.39±0.04)mg/L,吸收1h后替尼泊苷浓度:(0.50±0.03)mg/L、(0.59±0.03)mg/L、(0.95±0.04)mg/L比(0.42±0.03)mg/L,吸收3h后替尼泊苷浓度:(0.53±0.04)mg/L、(0.62±0.04)mg/L、(1.01±0.03)mg/L比(0.46±0.03)mg/L,均p＜0.01];8-MG-BA+苯妥英钠5 mg/L组、8-MG-BA+苯妥英钠10 mg/L组细胞内卡莫司汀、替尼泊苷含量均高于8-MG-BA+维拉帕米5 mg/L组(P＜0.01);8-MG-BA+苯妥英钠5 mg/L组细胞内卡莫司汀、替尼泊苷含量均低于8-MG-BA+苯妥英钠10 mg/L组(P＜0.05).当被测VM26及卡莫司汀质量浓度为0.05～5 mg/L时,其浓度与峰面积之间具有良好的线性关系.替尼泊苷回收率分别为(96±5)％、(100±4)％和(99±2)％;卡莫司汀回收率分别为(100±5)％、(99±4)％和(99±4)％,日内(24h)、日间(2d间)误差相对标准偏差分别为4.47％和4.96％(n=5).结论 苯妥英钠可以增加化学治疗耐药8-MG-BA细胞内卡莫司汀、替尼泊苷的积聚浓度,并与剂量有关.     

Effect of azidothymidine on the radiation-induced LDH release in HeLa cells

Treatment of HeLa cells with various concentrations of 0, 0.01, 0.1, 1, 10, and 100 microM AZT resulted in a concentration dependent elevation in the LDH release at 0, 0.5, 1, 2 and 4 h post-treatment. An elevation of 1.7 to 9.2 fold in LDH content was observed at 1 h post-treatment depending on the drug concentration. Similarly, treatment of HeLa cells with 0.1 microM AZT before irradiation caused an irradiation dose dependent increase in the LDH release in AZT + irradiation groups. This increase in LDH release was approximately two fold greater at 0 h post-irradiation in AZT + irradiation group, when compared with the PBS + irradiation group. This trend of elevation in LDH release continued up to 2 h, except 2 and 3 Gy, where it was 1.7 fold in the former group when compared with the latter. However, a peak level of LDH release was observed at 0 h post-irradiation.     

替尼泊苷联合卡铂与依托泊苷联合卡铂一线治疗小细胞肺癌的长期随访研究

目的 长期随访比较替尼泊苷（Teniposide,VM-26）联合卡铂（Carboplatin,CBP）（TC方案）与依托泊苷（Etoposide,VP-16）联合卡铂（EC方案）一线治疗小细胞肺癌（Small cell lung cancer,SCLC）的疗效及对脑转移的预防作用。方法 102例初治、无脑转移的SCLC患者接受治疗,其中EC方案（VP-16组）64例,TC方案（VM-26组）38例,患者一般临床特征经χ2检验,两组具有可比性（P﹥0.05）。化疗后达PR或CR者给予预防性脑照射（prophylactic cranial irradiation, PCI）。结果 VM-26组CR 4例,PR 26例,SD 7例,PD 1例,ORR为78.9%,DCR为97.4%,中位PFS为10个月,中位OS为18个月;VP-16组CR 7例,PR 42例,SD 12例,PD 3例,ORR为76.6%,DCR 95.3%,中位PFS为9个月,中位OS为16个月。VM-26组1、2、3年OS分别为73.7%、36.8%和18.4%;VP-16组1、2、3年OS分别为71.9%、37.5%和18.8%。两组有效率、疾病控制率及生存期均无统计学差异（P﹥0.05）。VM-26组脑转移发生率为21.1%,VP-16组为43.8%,VP-16组明显高于VM-26组,有统计学差异（P=0.020）。不良反应主要是骨髓抑制,多为I、II度,两组比较无统计学差异（ P﹥0.05）。结论 TC方案治疗SCLC疗效肯定,其近期疗效和长期生存与EC方案相似,且该方案一定程度上可降低脑转移发生率,耐受性较好,可作为初治SCLC的一线治疗方案。     

The effects in mice of combined treatments to X-rays and antineoplastic drugs in the Comet assay

The Comet assay is a rapid, easy and reproducible method to detect genotoxic activity of chemical and physical agents in vitro and in vivo. In the present study the effects of exposure to irradiation or chemicals: cyclophosphamide (CP) and mitomycin C (MMC) or combined exposure to low doses of both agents (0.25 Gy+3.15 mg/kgbw CP and 0.25 Gy+0.25 mg/kgbw MMC) were examined for the induction of DNA damage in the Comet assay measured simultaneously in somatic (bone marrow lymphocytes) and haploid germ cells. The male mice were treated in vivo and sacrificed at 24 h after exposure. The percentage contents of DNA in the "comet tail" increased with increasing doses of X-rays and chemicals. After combined exposure to X-rays and CP and to X-rays and MMC weak increases of DNA damage in bone marrow lymphocytes and in germ cells were observed by comparison with the results obtained for each agent acting alone. There were slightly different responses in bone marrow lymphocytes and in germ cells, but effects were observed over a similar dose range.     

Correlation between cell survival and micronuclei-induction in HeLa cells treated with adriamycin after exposure to various doses of gamma-radiation

The effect of 10 microg/ml of adriamycin (doxorubicin) post-treatment was studied in HeLa cells exposed to 0, 0.5, 1, 2 and 3 Gy of gamma radiation. The survival of HeLa cells declined in a dose dependent manner in both irradiation+PBS and irradiation+ADR groups. Treatment of adriamycin immediately after irradiation resulted in a significant decline in the cell survival. The surviving fraction of HeLa cells reduced to 0.61 after exposure to 0. 5 Gy in the irradiation+ADR group, whereas a similar effect (i.e. surviving fraction of 0.61) was obtained for 3 Gy in the irradiation+PBS group. In contrast, the frequency of micronuclei increased in a dose dependent manner in both irradiation+PBS and irradiation+ADR groups. A significant elevation in the frequency of micronuclei was observed in the latter when compared with the former group. The dose response for both groups was linear quadratic. The cell proliferation indices also showed a dose dependent decline in both the groups. The decline in the cell proliferation was significantly higher in the irradiation+ADR group when compared with the irradiation+PBS group. A close correlation between the cell survival and micronuclei induction was observed in both groups, where the cell survival declined with the elevation in the micronuclei frequency. The relationship between cell survival and micronuclei induction was linear quadratic.     

VM-26 in gastric cancer

Summary The Southwest Oncology Group conducted a trial of VM-26 (teniposide) in patients with advanced gastric cancer. VM-26 60 mg/m² IV infusion over 30–45 minutes was given daily for 5 days every 21 days. Twentyone eligible patients with measurable disease and a SWOG performance status of 0–2 were analyzed for response and toxicity. Partial responses were seen in 2 of the 21 eligible patients (9.5%). Median survival was 3.8 months. Severe or life-threatening toxicity was observed in 13/21 (62%) patients. This included two drug related deaths related to neutropenic sepsis and seven other patients with grade 4 granulocytopenia (< 500/mm³). Liver dysfunction and hypotension were seen less often and were not dose limiting. Although the modest activity seen was comparable to that of VP-16 (etoposide) as a single agent, the hematologic toxicity observed in this trial would likely preclude further trials of VM-26 (teniposide) in advanced gastric cancer.     

Long-term effects of radioprotector WR-2721 on locomotor activity and body weight of mice following exposure to ionizing radiation

The effects of 13 Gy gamma-radiation alone and in combination with 200 mg/kg of the radioprotector S-2-(3-aminopropylamino)ethylphosphorothioic acid (WR-2721) on locomotor activity and body weight were examined in CD2F1 mice over a 10-month period. The results confirmed that WR-2721 is an excellent radioprotector against lethality. All mice receiving 13 Gy without WR-2721 died in 5-7 days. For mice that received WR-2721 alone or WR-2721 + radiation, survival at 30 days was 100% and 70%, respectively. Body weights of mice receiving WR-2721 without radiation were comparable to control animals. Body weights of animals given WR-2721 + radiation fell on days 1-5 and then increased until day 11, but remained below control values throughout the experiment. Animals in the radiation-only group did not exhibit any significant reductions in behavior until day 2 post-irradiation. Mice administered WR-2721 alone showed significantly reduced locomotor activity levels on day 0 then completely recovered within 24 h and exhibited normal body weights. Animals given WR-2721 before irradiation showed greater reductions in locomotor activity on day 0 than either the WR-2721 or radiation-only groups and recovered to control level by day 3. Beginning on day 5, they showed significant reductions in activity. Mice pretreated with WR-2721 that survived a normally lethal dose of radiation showed a 20-40% reduction in locomotor performance that recovered in 2-5 months.     

Synthesis and biological activity of galactopyranoside derivatives of 4'-demethylepipodophyllotoxin showing VP-16 (etoposide)-like activity.

To investigate the role of the glucoside moiety in the biological activity of VP-16 (etoposide; 4'-demethylepipodophyllotoxin-ethylidene-beta-D-glucoside) and VM-26 (teniposide; 4'-demethyl-epipodophyllotoxin-thenylidene-beta-D-glucoside), a number of acetal and ketal derivatives of 4'-demethylepipodophyllotoxin (DMEP)-beta-D-galactoside were synthesized. The compounds synthesized included acetaldehyde, propionaldehyde, 2-thiophenecarboxaldehyde, phenylacetaldehyde and acetone derivatives. In contrast to the glucose derivatives, where the acetal ring is trans to the pyranose ring, in galactose derivatives it is located in the cis position. The activities of the above compounds have been measured in two different biological assays, based on cross resistance towards mutants exhibiting specific resistance to VP-16/VM-26-like drugs and DNA-strand breaks as measured by the alkaline elution technique. All of the above compounds showed specific cross resistance to VpmR mutants (mutants resistant to VP-16 and VM-26) and caused a dose-dependent enhancement in DNA-strand breakage, providing evidence that they possessed the same kind of biological activity as VP-16 and VM-26. The relative activities of the DMEP-galactose derivatives have been compared with the corresponding DMEP-glucoside compounds. These studies reveal that, for the acetal and ketal derivatives with small R groups (acetaldehyde and acetone derivatives), the activities in the two series are comparable. However, for derivatives with larger, more hydrophobic R groups (2-thiophene or phenylacetaldehyde), the glucoside derivatives showed about 8-10-fold higher activity in comparison with the corresponding galactoside compounds.     

Flow cytometric evaluation of the effect of various doses of vindesine sulphate on mouse spermatogenesis

Spermatogenesis, a rapidly proliferating cell system, is highly susceptible to damage by radiotherapy and/or chemotherapy. Vindesine, a semisynthetic vinca alkaloid, was given as a single injection to adult male Swiss albino mice to study its effects on testicular weight and male germ cell turnover pattern using flow cytometry. Testicular weight declined significantly at Day 7 to 14 and from Day 14 to 35 after administration of 1 and 2 mg/kg b wt vindesine, respectively. Flow cytometric evaluation of various testicular cell types after the administration of 2 mg/kg b wt vindesine revealed a significant increase in the relative percentage of spermatogonial cells at Day 21 and 35 posttreatment. In contrast, the relative percentage of primary spermatocytes declined significantly at Day 7 and 14 posttreatment. Similarly, a significant reduction in the relative percentage of round spermatids was observed from Day 7 to 35 posttreatment. The relative percentage of elongated spermatids declined significantly at day 35 post-treatment. These changes are reflected in the transformation ratios. While the 4C:2C ratio did not exhibit any significant change below 1 mg/kg vindesine, it declined significantly after 1 mg/kg (Day 14) and 2 mg/kg (Day 7 to 35, except Day 28 posttreatment) vindesine treatment. Treatment of male mice with 2 mg/kg vindesine resulted in a significant decline in 1C:2C ratio from 7 to 35 d post-treatment. The 4C:S-phase ratio decreased significantly at Day 7 and 14 posttreatment for all the drug doses above 0.05 mg/kg. A significant reduction in the 1C:4C ratio was observed at day 21 to 35 posttreatment as a result of 2 mg/kg vindesine administration.     

Protective effects of quercetin on ultraviolet A light-induced oxidative stress in the blood of rat

The oxidative effects of ultraviolet A (UVA) light (320-400 nm) and the antioxidant effects of quercetin were examined in rat blood. For this purpose, rats were divided into three groups: control, ultraviolet (UV) and ultraviolet + quercetin (UV + Q). The UV and UV + Q groups were irradiated for 4 h a day with UVA light (1.25 mW cm(2)) during periods of 3, 6 and 9 days. Quercetin (50 mg kg(-1) body wt.) was administered intraperitoneally in the UV + Q group rats before irradiation periods. Blood was taken 3, 6 and 9 days post-treatment. Plasma malondialdehyde (MDA) levels significantly increased after 9 days of daily exposure to UVA. Whole blood glutathione (GSH) levels significantly declined after 3-9 days of irradiation. Glutathione peroxidase activity on days 6 and 9 and glutathione reductase activities on days 3, 6 and 9 post-irradiation were diminished significantly. Superoxide dismutase and catalase activities decreased significantly 3-9 days post-irradiation. The administration of quercetin before the 9-day period of irradiation significantly reduced the increase in plasma MDA value. Whole blood GSH levels significantly decreased with the administration of quercetin on all days. Quercetin significantly increased antioxidant enzymes diminished by UVA irradiation. Exposure of rats to UVA light leads to oxidative stress, reflected by increased MDA and reduced antioxidant enzyme levels. The administration of quercetin appears to be a useful approach to reduce the damage produced by UVA radiation.     

Activity of etoposide (VP-16) and teniposide (VM-26) in exponential and plateau phase human tumor cell cultures.

The effects of etoposide (VP-16) and teniposide (VM-26) have been evaluated in human epidermoid carcinoma cells (A431, ME180 and HEp3) grown as exponential and plateau phase cultures. A significant increase in resistance to both these chemotherapeutic agents was observed in unfed plateau compared with exponential phase cells. The large differences in cell killing could not be explained by cell cycle specific toxicities resulting from variations in the cell cycle distributions. Rather the differences in the treatment efficacies probably reflect the 5- to 15-fold increase in the proportion of quiescent cells measured in the plateau phase cultures. These findings suggest that non-proliferating cells in tumors may be preferentially spared in treatments utilizing VP-16 and VM-26.