Effect of Terminalia arjuna extract on adriamycin-induced DNA damage.

The effect of a bark extract of Terminalia arjuna (TAE) was studied on the alteration of adriamycin (ADR)-induced micronuclei formation in cultured human peripheral blood lymphocytes. Exposure of lymphocytes to ADR resulted in a dose-dependent increase in the micronuclei formation indicating DNA damage. Pretreatment of lymphocytes with TAE before ADR treatment resulted in a significant decline in micronuclei formation. Increasing doses of ADR caused a dose-dependent increase in the frequency of lymphocytes bearing one, two and multiple micronuclei. Prior exposure of lymphocytes to 15 microg/mL of TAE significantly reduced the frequency of lymphocytes bearing one, two and multiple micronuclei when compared with ADR-treated control. TAE-inhibited the induction of (*)OH (hydroxyl), O2(*-) (superoxide), DPPH (1,1-diphenyl-2-picrylhydrazyl), ABTS(*+) (2,2-azino-bis-3-ethyl benzothiazoline-6-sulphonic acid) radicals in a dose-dependent manner. These results demonstrate that TAE protects DNA against ADR-induced damage.

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.

Antioxidant, anticlastogenic and radioprotective effect of Coleus aromaticus on Chinese hamster fibroblast cells (V79) exposed to gamma radiation.

Coleus aromaticus (Benth, Family: Laminaceae), Indian Oregano native to India and Mediterranean, is well known for its medicinal properties. A preliminary study was undertaken to elucidate in vitro free radical scavenging potential and inhibition of lipid peroxidation by C.aromaticus hydroalcoholic extract (CAE). Anti-clastogenic and radioprotective potential of CAE were studied using micronucleus assay after irradiating Chinese hamster fibroblast (V79) cells. CAE at 10, 20, 40, 60, 80, 100 and 120 mug/ml resulted in a dose-dependent increase in radical scavenging ability against various free radicals viz., 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), superoxide anion (O(2)(*-)), hydroxyl (OH(*)) and nitric oxide (NO(*)) generated in vitro. A maximum scavenging potential was noticed at 100 mug/ml and a saturation point was reached thereafter with the increasing doses of CAE. The free radical scavenging potential of the extract was in the order of DPPH > ABTS > Superoxide > Hydroxyl > Nitric oxide. CAE also exhibited a moderate inhibition of lipid peroxidation in vitro, with a maximum inhibition at 60 mug/ml (33%), attaining saturation at higher doses. The extract also rendered protection against radiation induced DNA damage, as evidenced by the significant (P < 0.05) decrease in the percentage of radiation-induced micronucleated cells (MN) and frequency of micronuclei (total). A maximum anticlastogneic effect/ radioprotection was noticed at a very low concentration i.e., 5 mug/ml of CAE, treated 1 h prior to 2 Gy of gamma radiation. A significant (P < 0.0001) anticlastogenic/radioprotective effect was also observed when the cells were treated with an optimum dose of CAE (5 mug/ml) 1 h prior to 0.5, 1, 2 and 4 Gy of gamma radiation compared with the respective radiation control groups. Overall, our results established an efficient antioxidant, anticlastogenic and radioprotective potential of CAE, which may be of great pharmacological importance.

Radioprotection by mangiferin in DBAxC57BL mice: a preliminary study.

The radioprotective effects of various concentrations (0, 0.25, 0.5, 1, 2, 5, 10, 17.5, 25, 50, 75 and 100 mg/kg b.wt.) of mangiferin (MGN) was studied in the DBAxC57BL mice whole body exposed to 10 Gy of gamma-irradiation. Treatment of mice with different doses of MGN, one hour before irradiation reduced the symptoms of radiation sickness and delayed the onset of mortality when compared with the non-drug treated irradiated controls. The radioprotective action of MGN increased in a dose dependent manner up to 2mg/kg and declined thereafter. The highest radioprotective effect was observed at 2mg/kg MGN, where greatest number of animals survived against the radiation-induced mortality. The administration of 0.5, 1, 2, 5, 10 and 17.5 mg/kg MGN reduced the radiation-induced gastrointestinal death as evident by a greater number of survivors up to 10 days in this group when compared with the DDW + 10 Gy irradiation group. A similar effect of MGN was observed for the radiation-induced bone marrow deaths also. Our study demonstrates that mangiferin, a gluosylxanthone, present in the Mangifera indica protected mice against the radiation-induced sickness and mortality and the optimum protective dose of 2mg/kg was 1/200 of LD50 dose (400 mg/kg) of MGN. The administration of 400 mg/kg MGN induced 50% mortality, therefore LD50 of the drug was considered to be 400 mg/kg.

Radioprotective effect of abana, a polyherbal drug following total body irradiation.

Effects of 20 mg/kg body weight of abana (ABE) on radiation-induced sickness and mortality in mice exposed to 7 Gy to 12 Gy of gamma irradiation were studied. Treatment of mice with abana 1 h before irradiation delayed the onset of mortality and reduced the symptoms of radiation sickness when compared with the non-drug treated irradiated controls (double distilled water, DDW). Abana provided protection against both the gastrointestinal and haemopoietic deaths. However, animals of both the ABE+irradiation and DDW+irradiation groups did not survive up to 30 days post-irradiation beyond 11 Gy irradiation. The LD(50/30) was found to be 8.5 Gy for the DDW+irradiation group and 10.3 Gy for ABE+irradiation group. The administration of abana resulted in an increase in radiation tolerance by 1.8 Gy, and the dose modification factor (DMF) was found to be 1.2. The irradiation of animals resulted in a dose dependent elevation in lipid peroxidation, and a reduction in glutathione (GSH) concentration on day 31 post-irradiation. Treatment of mice with abana before irradiation caused a significant depletion in lipid peroxidation followed by a significant elevation in GSH concentration in the liver of mice at day 31 post-irradiation. Abana scavenged (*)OH, DPPH, ABTS(*+) and NO(*) in a concentration dependent manner in vitro. Our results indicate that the radioprotective activity of abana may be due to free radical scavenging and increased GSH level in irradiated mice.

Augmentation of wound healing by ascorbic acid treatment in mice exposed to gamma-radiation.

PURPOSE: Because of the crucial practical importance of acute radiation exposure associated with combined injuries, the study was undertaken to investigate the effect of various doses of ascorbic acid on the survival and healing of wounds in mice exposed to whole-body gamma-radiation. MATERIALS AND METHODS: Animals were given double-distilled water or different doses of ascorbic acid by intraperitoneal injection before exposure to 0 or 10 Gy whole-body gamma-radiation to evaluate the effect of ascorbic acid on radiation-induced mortality. The animals were monitored daily for the symptoms of radiation sickness and mortality. In a separate experiment, animals were administered with either double-distilled water or different doses of ascorbic acid before exposure to 0 or 6 Gy whole-body gamma-radiation to investigate the effect of ascorbic acid on the irradiated wound. A full-thickness skin wound was created on the dorsum of the irradiated mice and the progression of wound contraction was monitored by capturing video images of the wound at various post-irradiation periods. RESULT: Treatment of mice with various doses of ascorbic acid elevated survival of mice and a highest number of survivors (67 and 33% for 10 and 30 days post-irradiation) was observed for 250 mg kg(-1) (p<0.002 and<0.02 for 10- and 30-day survival, respectively). Ascorbic acid treatment caused a dose-dependent elevation in the wound contraction and highest contraction was observed for 250 mg kg(-1). The wound contraction was significantly greater at 3 (p<0.005), 6 (<0.05) and 9 (<0.05) days post-irradiation with 250 mg kg(-1) ascorbic acid. The complete healing of the wound was effected by day 22.8 post-irradiation in the ascorbic acid-treated irradiation group. CONCLUSION: Administration of ascorbic acid protected mice against radiation-induced sickness, mortality and improved healing of wounds after exposure to whole-body gamma-radiation. Additional studies will be directed toward analysing the role of successive administration of ascorbic acid to protect non-target tissues during radiotherapy and in initiating and supporting the cascade of tissue repair processes in radiotherapy delayed wounds.

Evaluation of the radioprotective effect of bael leaf (Aegle marmelos) extract in mice.

PURPOSE: To investigate the radioprotective activity of a leaf extract of bael leaf (Aegle marmelos) (AME) in mice exposed to different doses of gamma-radiation. MATERIALS AND METHODS: The acute toxicity of AME was evaluated in Swiss albino male mice administered various intraperitoneal single doses of AME. For radioprotection studies, mice were administered different doses, 0, 5, 10, 15, 20 or 40 mg kg(-1), of AME or sterile physiological saline intraperitoneally once daily consecutively for 5 days before exposure to 10 Gy 60Co gamma-radiation or five doses of 15 mg kg(-1) AME before exposure to 6, 7, 8, 9, 10 or 11 Gy. The animals were monitored for symptoms of radiation sickness and mortality up to 30 days post-irradiation. Glutathione and lipid peroxidation were estimated in the surviving animals of both groups on day 31 post-irradiation. RESULTS: AME was non-toxic up to a single dose of 1750 mg kg(-1). The optimum radioprotective dose was five consecutive doses of 15 mg kg(-1) AME, where the highest survival to 10 Gy radiation was observed. The irradiation caused a dose-dependent decline in survival, while treatment of mice with AME enhanced survival. The dose reduction factor was 1.15. Irradiation caused a dose-dependent decline in the level of glutathione accompanied by an elevation in lipid peroxidation. AME pretreatment arrested glutathione decline and lipid peroxidation significantly. CONCLUSION: AME treatment reduced the symptoms of radiation-induced sickness and increased survival. The radioprotective action might be due to free-radical scavenging and arrest of lipid peroxidation accompanied by an elevation in glutathione.

Effect of curcumin on radiation-impaired healing of excisional wounds in mice.

OBJECTIVE: To study the effect on wound contraction of pretreatment with various doses of curcumin (the most important active ingredient of the spice turmeric) in mice exposed to 6 Gy whole-body gamma radiation. METHOD: A full-thickness skin wound was produced on the dorsum of Swiss albino mice treated with and without 25, 50, 100, 150 or 200 mg/kg body weight of curcumin before exposure to 6 Gy gamma radiation. Progression of wound contraction was monitored using video images of the wound at various days post-irradiation until full healing occurred. Mean wound healing times were also calculated. RESULTS: Irradiation caused significant delay in wound contraction and healing times. However, treatment with curcumin resulted in a dose-dependent increase in contraction when compared with a control. Greatest contraction was observed for 100 mg/kg curcumin, with statistically significant results at days three (p < 0.009), six (p < 0.05) and nine (p < 0.05) post-irradiation for this dose. Complete healing was achieved by day 23 post-irradiation in the curcumin-treated irradiation group. CONCLUSION: Pretreatment with curcumin has a conductive effect on irradiated wounds. It could be a substantial therapeutic agent for ameliorating radiation-induced delay in wound repair in cases of combined injuries.

Evaluation of intraperitoneal vincristine in malignant peritoneal effusion.

The efficacy and safety of intraperitoneal administration of vincristine sulphate was determined in mice bearing Ehrlich ascitic carcinoma. The tumor bearing animals were administered with 0.5 mg/kg body weight (b.wt) of freshly prepared vincristine sulphate intraperitoneally on day 6 after tumor transplantation followed by drug administration once daily 5 days a week consecutively. The observations regarding the survival, alteration in the volume of peritoneal fluid, increase in life span and pathological changes in the liver, kidney, gastrointestinal tract and bone tissues were made. The vincristine sulphate treatment reduced the malignant cell population significantly and there were no significant changes in the histological picture of liver, kidney, bone, except the intestine, where atropy of villi demonstrating nests and cords of uniform small round cells were observed. Our experimental data suggests that intraperitoneal administration of vincristine is beneficial in malignant peritoneal effusion.

The evaluation of the radioprotective effect of Triphala (an ayurvedic rejuvenating drug) in the mice exposed to gamma-radiation.

The effect of 0, 5, 6.25, 10, 12.5, 20, 25, 40, 50 and 80 mg/kg b. wt. of aqueous extract of triphala (an Ayurvedic herbal medicine) administrered intraperitoneally was studied on the radiation-induced mortality in mice exposed to 10 Gy of gamma-radiation. Treatment of mice with different doses of triphala consecutively for five days before irradiation delayed the onset of mortality and reduced the symptoms of radiation sickness when compared with the non-drug treated irradiated controls. The highest protection against GI (gastrointestinal) death was observed for 12.5 mg/kg triphala, where a highest number of survivors were reported up to 10 days post-irradiation. While 10 mg/kg triphala i.p. provided the best protection as evidenced by the highest number of survivors after 30 days post-irradiation in this group when compared with the other doses of triphala. Toxicity study showed that triphala was non-toxic up to a dose of 240 mg/kg, where no drug-induced mortality was observed. The LD50 dose i.p. of triphala was found to be 280 mg/kg b. wt. Our study demonstrates the ability of triphala as a good radioprotective agent and the optimum protective dose of triphala was 1/28 of its LD50 dose.

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.

Azidothymidine induces dose dependent increase in micronuclei formation in cultured HeLa cells.

Exposure of HeLa cells to azidothymidine (AZT) resulted in a concentration dependent decline in growth kinetics. 100 microM of AZT completely inhibited the cell growth. The frequency of binucleate and multinucleate cells declined with increasing concentration of AZT and the formation of multinucleate cells was completely inhibited at 20 and 30 h at higher concentrations indicating inhibition of cell division. Similarly, the clonogenicity of cells declined in a concentration dependent manner and 10 microM AZT killed 50% of the cells. Conversely, the frequency of MNBNC (micronucleated binucleate cell) increased in a concentration dependent manner and was significantly higher in the AZT treated group than the non-drug treated control group. The relationship between concentrations of AZT and micronuclei-induction was linear for all the post-treatment time periods studied. The biological response was also determined by plotting the surviving fraction of cells on the X-axis and the number of micronuclei on the Y-axis. A close and inverse correlation between the surviving fraction and micronuclei formation was observed and the data could be fitted on to a linear quadratic model.

Genotoxic effect of hydroquinone on the cultured mouse spleenocytes.

The daily administration of 0, 0.5, 1, 2, 4 and 8 mg/kg b. wt. of hydroquinone (HQ) to Swiss albino mice, consecutively for 6 days resulted in a dose dependent elevation in the frequency of micronucleated binucleate spleenocytes (MNBNS). This increase in the frequency of MNBNS was significantly higher than that of non-drug treated controls (0 mg/kg). The daily administration of various doses of HQ for 6 days not only increased the frequency of binucleated spleenocytes bearing one micronuclei (MN), but also the BNS bearing two, three, and four MN. The study demonstrates that the daily administration of various doses of HQ for 6 days increases the genotoxic and mutagenic potential in mice.

Evaluation of micronuclei frequency in the cultured peripheral blood lymphocytes of cancer patients before and after radiation treatment.

The frequency of micronucleated binucleate lymphocyte (MNBNC) was determined in the peripheral blood lymphocytes of patients suffering from various types of cancer before the onset of radiation treatment, middle (mid-) of the treatment and after completion of the treatment (post-treatment). The frequency of micronuclei increased significantly in the pretreatment sample of cancer patients when compared with the normal untreated healthy volunteers. During the middle of the radiotherapy an approximate two or > two-fold increase was observed in the micronuclei frequency in most of the patients when compared with the concurrent pretreatment samples. Immediately after the completion of treatment, the frequency of micronuclei further increased, and this increase was significantly higher than that of pretreatment and mid-treatment samples. Out of 27 patients analyzed, only nine patients did not have any history of smoking, tobacco chewing or alcohol consumption, while the remaining 18 patients had a history of either smoking, tobacco chewing or alcohol consumption or combination of two or all habits at the time of blood collection.

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.

Effect of doxorubicin on cell survival and micronuclei formation in HeLa cells exposed to different doses of gamma-radiation.

PURPOSE: The present study was undertaken to obtain an insight into the combined effects of doxorubicin with radiation on the cell survival and micronuclei induction in HeLa cells. MATERIAL AND METHODS: HeLa S3 cells were allowed to grow till they reached plateau phase, inoculated with 10 micrograms/ml doxorubicin hydrochloride and then exposed to 0, 0.5, 1, 2 and 3 Gy gamma-radiation. Clonogenicity of cells was measured using the colony forming assay, micronuclei formation using the micronucleus assay. RESULTS: The treatment of HeLa cells with doxorubicin (adriamycin) for 2 hours before exposure to different doses of gamma-radiation resulted in a significant and dose-dependent decline in the cell survival and cell proliferation when compared to the PBS + irradiation group. Conversely, the frequency of micronuclei increased in a dose-related manner in both the PBS + irradiation and doxorubicin + irradiation groups. The pretreatment of HeLa cells with doxorubicin before irradiation to various doses of gamma-rays resulted in a significant elevation in the frequency of micronuclei when compared with the concurrent PBS + irradiation group. The dose-response relationship for both PBS + irradiation and doxorubicin + irradiation groups was linear. The correlation between cell survival and micronuclei induction was also determined for PBS or doxorubicin + irradiation group, where the clonogenicity of cells declined with the increase in micronuclei formation. The correlation between cell survival and micronuclei induction was linear quadratic for both PBS + irradiation and doxorubicin + irradiation groups. CONCLUSION: From our study it can be concluded that combination treatment with doxorubicin and radiation increased the genotoxic effect of the either treatment given alone.

Effect of acyclovir on the radiation-induced micronuclei and cell death.

Treatment of HeLa cells with 0.1 microM Acyclovir [9-(2-hydroxyethoxymethyl)guanine] (ACV) before exposure to 0, 0.25, 0.5, 1, 2 and 3 Gy of gamma-radiation resulted in a dose-dependent decline in the growth kinetics and cell proliferation indices at 20, 30 and 40 h post-irradiation when compared with the PBS+irradiation group. These results were reflected in the cell survival, which declined in a dose-dependent manner and the surviving fraction of cells was significantly lower in ACV+irradiation group than that of PBS+irradiation group. The effect of ACV+1 Gy irradiation was almost similar to PBS+3 Gy irradiation suggesting an enhancement of the radiation effect by ACV pretreatment. The frequency of micronuclei increased in a dose-dependent manner at all the post-irradiation time periods in both PBS+irradiation and ACV+irradiation group and it was significantly elevated in the latter when compared with the former group. The dose-response for both groups was linear. The surviving fraction of HeLa cells declined with the increasing MN frequency and a close linear quadratic correlation between cell survival and micronuclei-induction was observed.

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.

Alteration in the radiation-induced LD release in HeLa cells by acyclovir.

The aim of the present investigation was to study the effect of various concentrations of acyclovir (ACV) alone or the effect of 0.1 micromol/l acycloir pretreatment on the radion-induced lactate dehydrogenase (LD) release by HeLa cells exposed to 0-3 Gy of gamma-radiation. The plateau-phase cells were treated with 0-100 micromol/l ACV for 8 h or 0.1 micromol/l ACV before exposure to 0-3 Gy of gamma-radiation. The whole media was removed from the culture and the LD release was measured at 0, 0.5, 1, 2, and 4 h post-drug treatment or post-irradiation. The ACV treatment resulted in a concentration-dependent elevation in the LD release at all the post-treatment time periods. A peak level for LD release was observed at 0 h up to 1 micromol/l ACV and declined thereafter. However, at higher doses a highest elevation in LD release was observed at 1 h post-treatment. Pretreatment of HeLa cells with 0.1 micromol/l ACV before irradiation to different doses of gamma-radiation resulted in significant elevation in the release of LD in the medium. The LD release was twofold greater in the ACV+irradiation group at 0 h post-irridiation when compared with the concurrent PBS+gamma-radiation group. The highest increase in LD activity was observed at 0 h post-irradiation and a gradual decline thereafter, without restoration to non-drug treated control level up to 4 h post-irradiation. The LD measurements can serve as a short-term assay to evaluate the cytotoxicity of ACV or radiation in vitro.

Correlation between cell survival and micronuclei formation in V79 cells treated with vindesine before exposure to different doses of gamma-radiation.

Effect of 20 nM vindesine sulphate (VDS) treatment was studied on cell survival, growth kinetics and micronuclei induction in V79 cells exposed to 0-300 cGy of gamma-radiation at 16, 22 and 28 h post-irradiation. Treatment of V79 cells with VDS before exposure to different doses of gamma radiation resulted in a significant decline in cell survival and growth kinetic when compared with the concurrent PBS+irradiation group. The decline in cell survival and growth kinetics was dose related. Similarly, the cell proliferation indices also declined in a dose dependent manner in both PBS+irradiation and VDS+irradiation groups and this decline was higher in VDS+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 VDS+irradiation groups. However, the frequency of micronuclei was significantly greater in the VDS+irradiation group when compared to the PBS+irradiation group at all the post-irradiation time periods studied and the dose response for both groups was linear for all the scoring time periods. The biological response was determined by plotting surviving fraction and micronuclei frequencies on X- and Y-axes, respectively. The plot between surviving fraction and micronuclei induction showed a close correlation. The surviving fraction of V79 cells reduced with the increasing frequency of micronuclei in both groups and the relationship between micronuclei induction and cell survival could be fitted on a linear quadratic model.