In vivo growth inhibitory and radiosensitizing effects of withaferin A on mouse Ehrlich ascites carcinoma.

Adult Swiss albino mice were inoculated intraperitoneally (i.p.) with 10 (6) Ehrlich ascites carcinoma cells. Twenty-four hours later they were given an i.p. injection of 10-60 mg/kg of withaferin A (WA), isolated from the roots of Withania somnifera. The tumor growth and tumor free animal survival were studied for up to 120 days. In another experiment 30 mg/kg WA was injected i.p. to mice at 1, 3 or 5 days after tumor cell injection with or without acute abdominal exposure to 7.5 Gy gamma radiation and the tumor growth and 120-day survival were studied. WA inhibited tumor growth and increased tumor free survival in a dose-dependent manner. The drug ED50 for 120-day survival was approximately 30 mg/kg body wt. Drug treatment before irradiation synergistically increased 120-day even in advanced tumors. A dose of 30 mg/kg seems to be optimum for combination with radiation.

Effect of prenatal exposure to diagnostic ultrasound on the development of mice.

Pregnant Swiss albino mice were exposed to diagnostic ultrasound (3.5 MHz, approximately 65 mW) for 10 min on Day 3.5 (preimplantation period), 6.5 (early organogenesis period), or 11.5 (late organogenesis period) of gestation. Sham-exposed controls were maintained for comparison. Exposed as well as control fetuses were dissected out on the 18th day of gestation, and changes in total mortality, body weight, body length, head length, brain weight, sex ratio, and microphthalmia were recorded. Exposure on Day 3.5 of gestation resulted in a small increase in the resorption rate and a significant reduction in fetal body weight. A low fetal weight and an increase in the number of growth-retarded fetuses were produced by exposure on Day 6.5 postcoitus. A statistically nonsignificant increase in the incidence of microphthalmia was induced in fetuses exposed on Day 6.5 or Day 11.5 of gestation. These results indicate that ultrasound may have some adverse effects on the mouse embryos depending on the developmental stage at which the exposure occurred.

Effect of fetal exposure to ultrasound on the behavior of the adult mouse.

Pregnant Swiss albino mice were exposed to diagnostic ultrasound (3.5 MHz, 65 mW, ISPTP = 1 W/cm2,ISATA = 240 W/cm2) for 10, 20 or 30 min on day 14.5 (fetal period) of gestation. Sham-exposed controls were studied for comparison. Any changes in physiological reflexes (such as pinna detachment, opening of the eyes and development of fur), postnatal mortality and changes in adult behavior (open-field test, dark/bright arena test, hole board test and conditioned-avoidance test) were recorded. No change was observed in the physiological reflexes. The postnatal survival was also not affected significantly by the exposure. However, there were significant alterations in behavior in all three exposed groups as revealed by the decreased locomotor and exploratory activity and the increase in the number of trials needed for learning. These results indicate that ultrasound exposure during the early fetal period can impair brain function in the adult mouse.

Effect of exposure to low-dose gamma radiation during late organogenesis in the mouse fetus.

The abdominal region of pregnant Swiss mice was exposed to 0.05 to 0.50 Gy of gamma radiation on day 11.5 postcoitus. The animals were sacrificed on day 18 of gestation and the fetuses were examined for mortality, growth retardation, changes in head size and brain weight, and incidence of microphthalmia. No marked increase in fetal mortality or growth retardation was observed below 0.25 Gy; the increase in these parameters was significant only at 0.50 Gy. A significant reduction in head size and brain weight and a significant increase in the incidence of microphthalmia were observed at doses above 0.15 Gy. Detectable levels of microcephaly and microphthalmia were evident even at 0.10 Gy. A linear dose response was seen for these effects in the dose range of 0.05 to 0.15 Gy. It is concluded that the late period of organogenesis in the mouse, especially between days 10 and 12 postcoitus, is a particularly sensitive phase in the development of the skull, brain and eye.

Determination of potential doubling times in human melanoma cell cultures subjected to irradiation and/or hyperthermia by flow cytometry.

The proliferation of human melanoma cells in vitro after irradiation and/or hyperthermia was studied by means of two-parameter flow cytometry. Cultures were incubated with BrdU for 30 min and fixed either immediately or after a delay of several hours. Cells having synthesized DNA were identified with the help of an antibody against BrdU. DNA was stained quantitatively with propidium iodide. In this way the distribution of cells in the phases of cell cycle could be determined and the movement of labeled cells through the phases of the cycle could be analyzed. Experiments in which the cell cycle distribution was studied at 4-h intervals after treatment showed the following: (1) Irradiation (4 Gy X rays) causes the expected G2 block with a maximum after 12-16 h. The proportion of S-phase cells decreases continually during the first 48 h after treatment. (2) Hyperthermia (1 h, 43 degrees C) alone or in combination with irradiation causes a delay in S phase. The cells begin to move into G2 phase only after 12-16 h and accumulate there to some extent. From the progression of labeled cells through the cycle, the duration of S phase could be determined. Experiments and calculations of this kind were done 0, 24 and 48 h after treatment. The duration of S phase was increased only moderately (by 4 h) after irradiation, but a delay of about 30 h occurred after hyperthermia (alone or in combination with X rays). Smaller delays (up to 9 h) were observed 24 and 48 h after treatment. Two different methods were used to calculate potential doubling times. Both of them gave similar results, but a comparison with the actual population doubling times (determined by cell counting) showed that reasonable estimates could be achieved only for the untreated controls. With cultures subjected to irradiation and/or hyperthermia serious discrepancies were observed. This does not seem to be due to technical problems inasmuch as we are dealing with a whole set of data produced under well-defined in vitro conditions (in contrast to the clinical situation, where potential doubling times have to be estimated from single samples). Our results certainly do not encourage the extension of the method (which was originally intended for the prediction of unperturbed tumor growth) to a post-treatment setting.

Evaluation of the cytogenetic damage and progenitor cell survival in foetal liver of mice exposed to gamma radiation during the early foetal period.

PURPOSE: To investigate the haemopoietic response to low dose gamma irradiation at the early foetal period when the liver is the major haemopoietic organ. MATERIALS AND METHODS: Pregnant Swiss albino mice were exposed to 0.1-1.5 Gy of gamma radiation on the 14th day of gestation. Twenty-four hours (15 day post conception (p.c.)) and 72 h (17 day p.c.) after exposure, the foetuses were dissected out, weighed, and liver weight and mean cellularity were determined. Cytogenetic damage in liver cells was assessed by chromosome aberration analysis and micronucleus (MN) count. The haemopoietic progenitor cell survival at 24 h and 72 h after exposure was measured by exogenous spleen colony assay on day 8 (CFU-S8) and day 12 (CFU-S12) after intravenous injection of the foetal liver cells into adult bone marrow-ablated recipient mice. RESULTS: The foetal body weight at 24 h after exposure showed a significant reduction at doses of 0.5 Gy and above, while the 72 h body weight was significantly lower than control from 0.3 Gy onwards. Liver weight showed a similar reduction for doses from 0.25 to 1.5 Gy at both the post-irradiation observation times. However, when liver weight/body weight ratios were compared, there was no significant difference between the irradiated and control values. Total liver cellularity at 24 h and 72 h after exposure showed a dose-dependent decrease, with significant depletion from control at 0.25 Gy and above. When donor cells were taken at 24 h after exposure (15 day p.c.) the CFU-S8 showed a significant decrease only at 1.0 and 1.5 Gy, while the CFU-S12 suffered such a depletion at 0.25-1.5 Gy. For donor cells recovered at 72 h after exposure, both CFU-S8 and CFU-S12 decreased linear-quadratically with radiation dose and were significantly lower than control at 0.25 Gy. A significant increase in the percent aberrant metaphases and micronucleus counts was seen at 0.1 Gy and 0.15 Gy, respectively, and increased linear-quadratically with radiation dose. CONCLUSIONS: The results demonstrate that the liver, which is the major haemopoietic organ at the early foetal period, is highly sensitive to radiation damage from maternal irradiation. At low doses, the lethal effect on the haemopoietic stem cells appears to develop more slowly than at higher doses.

Influence of gestational age at exposure on the prenatal effects of gamma-radiation.

The abdominal region of pregnant Swiss albino mice was exposed to single dose of 0.5 Gy gamma-radiation at gestation days from 1.5 to 17.5 days post-coitus (p.c). The animals were sacrificed on day 18 p.c. and foetuses were examined for resorption and embryonic death, foetal death, growth retardation, small head, low brain weight, micro-phthalmia and any other gross morphological abnormalities. The period of maximum sensitivity for each effect varied. The only demonstrable effect of irradiation during the pre-implantation period was an increase in prenatal mortality. Resorptions were maximal after exposure between days 2 and 4 p.c. The pre-implantation irradiated embryos which survived did not show any major foetal abnormalities. These results confirm earlier mouse studies using higher doses of X-rays. Small head, low brain weight and microphthalmia were prominent after exposure during the late organogenesis period, especially between days 9 and 13 p.c. But no other externally visible anomalies were detected. These findings demonstrate that mouse organogenesis is very sensitive to radiation-induced retardation of development, even at doses < 1 Gy. One exencephaly, one cleft palate and two cases of open eyelids were observed in the foetuses exposed on days 14.5 and 15.5 p.c.; the number of these cases was too small to indicate a causal relationship with exposure.

Withaferin A: a new radiosensitizer from the Indian medicinal plant Withania somnifera.

Withaferin A, a steroidal lactone isolated from the roots of the Indian medicinal plant Withania somnifera, reduced survival of V79 cells in a dose-dependent manner. LD50 for survival was 16 microM. One-hour treatment with a non-toxic dose of 2.1 microM before irradiation significantly enhanced cell killing, giving a sensitizer enhancement ratio (SER) of 1.5 for 37% survival and 1.4 for 10% survival. SER increased with drug dose, but at higher doses the increased lethality appears to be due to two effects-- drug toxicity and radiosensitization. The drug induced a G2/M block, with a maximum accumulation of cells in G2-M phase at 4 h after treatment with 10.5 microM withaferin A in 1 h. The applicability of this drug as a radiosensitizer in cancer therapy needs to be explored.

Dose-dependent increase in the frequency of micronuclei and chromosomal aberrations by misonidazole in mouse bone marrow.

Cytogenetic effects produced in bone marrow of mice by various doses of misonidazole (MISO, 100 to 1000 mg/kg bodyweight) were studied by assaying the induction of micronuclei (MN) and chromosomal aberrations. Misonidazole increased the frequency of both micronuclei and chromosomal aberrations over normal at 24 h after treatment, however, the values were statistically significant from normal only at drug doses above 250 mg/kg. The increase was proportional to the drug dose with a best fit to linear quadratic model for MN induction. For chromosomal aberrations the data fitted equally well to linear as well as linear quadratic models.

Induction of chromosomal instability in mouse hemopoietic cells by fetal irradiation.

Mice were exposed to 0.25-1.5Gy of gamma radiation on day 14 or 17 of gestation and chromosomal aberrations were scored in the bone marrow at 12 months of age. Irradiation had resulted in low peripheral blood counts, while some animals developed very high leukocyte counts. Exposed animals showed a significant dose dependent increase in the number of aberrant metaphases, compared to unexposed animals. Fragments and polyploidy were the major types of aberrations. Mice with abnormally high blood leukocyte counts showed a higher incidence of chromosomal aberrations, especially high levels of polyploidy than in animals with low blood counts. It is concluded that radiation induced genomic instability in the fetal hemopoietic cells of mouse is transmitted to postnatal and adult bone marrow which may lead to the development of hematological disorders, including malignancies.

Enhancement of bone marrow radioprotection and reduction of WR-2721 toxicity by Ocimum sanctum.

The radioprotective effect of the leaf extract of Ocimum sanctum (OE) in combination with WR-2721 (WR) was investigated on mouse bone marrow. Adult Swiss mice were injected intraperitoneally (i.p.) with OE (10 mg/kg on 5 consecutive days), or 100-400 mg/kg WR (single dose) or combination of the two or double-distilled water (DDW) and whole-body exposed to 4.5 Gy gamma-irradiation (RT). Metaphase plates were prepared from femur bone marrow on days 1, 2, 7 and 14 post-treatment and chromosomal aberrations were scored. The maximum number of aberrant cells was observed at 24 h after irradiation in all the groups. However, pretreatment with OE or WR individually resulted in a significant decrease in aberrant cells as well as different types of aberrations. The combination of the two further enhanced this effect; resulting in a 2-fold increase in the protection factor (PF = 6.68) compared to 400 mg/kg WR alone. The percent aberrant cells decreased linear-quadratically with WR dose when given individually, while in the OE + WR pretreatment animals the values showed a linear dose response. Combination of OE with WR doses above 200 mg/kg completely eliminated rings, polyploidy and pulverization of chromosomes. Percent aberrant cells decreased with time in all groups, though the values remained higher than normal even on day 14 in the RT alone as well as those treated with single agent + RT. WR doses above 200 mg/kg before RT resulted in significantly higher frequency of aberrant cells compared to RT and OE + RT groups on day 14, suggesting delayed WR toxicity; but combination of OE with WR brought down these values to normal level, indicating that OE combination, in addition to enhancing WR protection, may also act as a detoxifier. The protective effect of OE and WR is also reflected in the enhancement of bone marrow CFU survival. Both OE and WR possessed significant free radical scavenging activity in vitro. The combination of the two further enhanced this effect, suggesting that the enhanced free radical scavenging activity by combining the two protectors results in the higher bone marrow cell protection. The significant elevation in chromosome protection obtained by combining OE with WR, with reduction in the latter's toxicity at higher doses, suggests that the combination may have promise for radioprotection in humans.

Protection against radiation-induced chromosome damage in mouse bone marrow by Ocimum sanctum.

The radioprotective effect of the leaf extract of Ocimum sanctum (Ocimum extract, OE) was investigated by taking chromosome aberrations as the end point. Adult Swiss mice were whole-body exposed to 1-6 Gy of gamma radiation with/without pretreatment with 10 mg/kg b.wt. of OE intraperitoneally for 5 consecutive days. Radiation was given 30 min after the last injection. Metaphase plates were prepared from femur marrow on days 1, 2, 7 and 14 post-treatment and the frequency of aberrant cells and individual aberrations were scored. OE alone did not have any significant effect on the chromosomes. Maximum percent of aberrant cells was observed at 24 h in all the exposed groups. The percent aberrant cells showed a linear quadratic increase with radiation dose, in both radiation alone (RT) and OE + RT-treated groups. Exchange (dicentrics and rings) and multiple (pulverized and severely damaged cells) aberrations also showed a similar response. However, the slopes of OE + RT was significantly shallower than RT groups (p < 0.05). A dose-modifying factor of 2.63 was obtained taking percent aberrant cells for 2 Gy as the base. Progressive decline in the percent aberrant cells as well as the number of aberrations with time after irradiation was observed in both RT and OE + RT groups. OE treatment resulted in a faster recovery compared to RT alone group. At doses below 3 Gy, OE pretreatment almost completely eliminated the exchange aberrations from the cell population by day 2. Studies on a chemical system demonstrated that OE significantly reduced the generation of hydroxyl radical; a lower dose of OE (1 mg/ml) was more effective than 5 mg/ml and this effect was more pronounced than that produced by DMSO. These results show that OE affords in vivo protection against radiation-induced cytogenetic damage. Free radical scavenging is a likely mechanism of OE protection.

In vivo radioprotection by alpha-TMG: preliminary studies.

alpha-TMG is a novel water-soluble derivative of Vitamin E that has shown excellent antioxidant activity. The parent compound has demonstrated protection against radiation induced chromosomal damage in vivo. Hence, the preliminary experiments to determine the radioprotective activity of alpha-TMG were carried out in adult Swiss albino mice. Acute toxicity of the drug was studied taking 24h, 72 h and 30 day mortality after a single intraperitoneal injection of 500-2000 mg/kg body weight of the drug. The drug LD(50) for 24h and 72 h/30 day survival were found to be 1120 and 1000 mg/kg body weight, respectively. The optimum time of drug administration and drug dose-dependent effect on in vivo radiation protection of bone marrow chromosomes was studied in mice. Injection of 600 mg/kg of the drug 15 min before or within 5, 15 or 30min after 3Gy whole body gamma radiation resulted in a significant decrease in the aberrant metaphases percent at 24h post-irradiation; the maximum effect was seen when the drug was given immediately after irradiation. Injection of 200-800 mg/kg TMG within 5 min of irradiation with 3 Gy produced a significant dose-dependent reduction in the radiation induced percent aberrant metaphases and in the frequency of micronucleated erythrocytes at 24h after exposure, with a corresponding decrease in the different types of aberrations. The optimum dose for protection without drug toxicity was 600 mg/kg body weight. At this dose, TMG produced 70 and >60% reduction in the radiation induced percent aberrant metaphases and micronucleated erythrocytes, respectively. The high water solubility and effectiveness when administered post-irradiation favor TMG as a likely candidate for protection in case of accidental exposures.

Teratogenic effects of repeated exposures to X-rays and/or ultrasound in mice.

Pregnant Swiss mice were exposed to 9 mGy of 70 kVp X-rays or 10 min of ultrasound (3.5 MHz, approximately 65 mW, ISPTP = 1 W/cm2, ISATA = 240 mW/cm2) on Days 6.5 and 11.5 of gestation in four combinations: X-rays on both days (X + X), ultrasound on both days (U + U), X-rays on Day 6.5 postcoitus (PC) and ultrasound on day 11.5 PC(X + U) and ultrasound at 6.5 days PC and X-rays on day 11.5 PC(U + X). Sham-treated controls were maintained for comparison. Effects on prenatal development, postnatal growth and adult behavior were studied. U + U group showed an increase in percent growth retarded fetuses and a nonsignificant increase was seen in the U + X group. Transient growth retardation was observed in all the exposure groups. This is less likely to be of any biological significance as the animals recovered during postweaning period. The postnatal mortality was significantly higher only in the U + U group. In the X + U group, the exploratory activity was affected at 6 months of age. There was a significant change in the locomotor activity with a reduction in the total activity as 3 and 6 months of age in the U + U group. Latency in learning capacity was also noticed in this group. The results indicate that repeated exposures to ultrasound or its combination with X-rays could be detrimental to the embryonic development and can impair adult brain function when administered at certain stages of organogenesis.

Influence of gestational age to low-level gamma irradiation on postnatal behavior in mice.

The present investigation was carried out to study the effects of in utero exposure to low-level gamma radiation (0.25, 0.35, or 0.50 Gy) on the postnatal neurophysiology and neurochemistry of the mouse. Pregnant Swiss albino mice were irradiated on days 11.5, 12.5, 14.5, or 17.5 post coitus (PC) and allowed to deliver. Locomotor and exploratory activities, learning and memory functions, and emotional activities were tested at 3 months of age using behavior tests. A representative group of animals was killed and hippocampal biogenic amines, noradrenaline, dopamine, serotonin (5-HT), and 5-HT's metabolite 5-hydroxy indoleactetic acid (5-HIAA), were measured. Exposure to 0.25 Gy at any of the gestation days did not produce any significant impairment in brain functions. However, an increase in gamma irradiation to 0.50 Gy on all the gestation days produced significant impairment in locomotor (open-field test) and anxiolytic (light and dark area test) activities, learning (hole board test), memory functions (active avoidance test), and emotional activity (rearings). The late fetal period is relatively resistant to radiation-induced impairment of brain functions. Both of the organogenesis gestation days showed a higher sensitivity than the fetal gestation days studied. Even a lower dose of 0.35 Gy when exposed on the late organogenesis days 11.5 and 12.5 PC, produced significant reduction in locomotor and exploratory activities. Day 11.5 PC showed a higher sensitivity than the other PC days studied. Biogenic amines did not show significant change after any of the exposures on any of the gestation days. The results suggest a threshold between 0.25 to 0.35 Gy for postnatal neurobehavior changes.

Effect of late fetal irradiation on adult behavior of mouse: Dose-response relationship.

Pregnant Swiss mice were exposed to 0.3-1.5 Gy of gamma radiation on day 17 of gestation and allowed to deliver the offspring. When the F1 mice were 6 months old, they were subjected to a number of behavioral tests. Open-field and dark-bright arena tests were conducted to study locomotor and exploratory activities. Learning and memory were tested by holeboard activity, conditioned avoidance response, and radial arm maze performance. After all the tests, 20 animals (10 males and 10 females) from each group were killed, and their brain weight was taken. The open-field and dark-bright arena tests showed a significant dose-dependent decrease in the locomotor and exploratory activities. Reduction in time spent in the dark area and higher locomotor activity in the bright area indicated a reduced aversion to bright light. But the emotional activities like rearing and grooming did not change. The learning and memory functions also showed a significant impairment, even at 0.3 Gy. The deficit in the performance in the holeboard test, conditioned avoidance response, as well as maze-learning efficiency, decreased linearly with increase in radiation dose. The brain weight showed a linear dose-dependent decrease. But the brain/body weight ratio was not significantly affected even at 1.5 Gy. These results demonstrate that exposure of a mouse on day 17 of gestation to radiation doses below 1.0 Gy can induce significant impairment in the adult brain function, without producing any notable effects on brain morphology. This study also suggests that the retardation of higher brain function by exposures during the late fetal period may have a threshold of around 0.3 Gy.

Effect of prenatal ultrasound exposure on adult behavior in mice.

Pregnant Swiss mice were exposed to diagnostic levels of ultrasound (3.5 MHz, Maximum acoustic output: ISPTP = 1 W/cm2 and ISATA = 240 mW/cm2, acoustic power = 65 mW) for 10 min on days 11.5 or 14.5 postcoitus (PC). At 3 and 6 months postpartum, offspring were subjected to the following behavioral tests: bright and dark arena test for locomotor/exploratory activity and passive avoidance test for learning and memory. Anxiolytic activity and latency in learning were noticed in the ultrasound-treated animals. The effect was more pronounced in the 14.5 days PC group than in the 11.5 days PC group. But memory was not affected in the ultrasound-exposed animals. There was a nonsignificant decrease in the total locomotor activity at 6 months of age in all the exposed animals. Thus, the present data demonstrate that exposure to diagnostic ultrasound during late organogenesis period or early fetal period in mice may cause changes in postnatal behavior as evidence by selected adult offspring behavioral tests. However, any conclusive statement in this regard should await results from more detailed investigations.

Modification of bone marrow radiosensensitivity by medicinal plant extracts.

Withaferin A (WA), a steroidal lactone, and Plumbagin (Pl), a naphthoquinone, from the roots of Withania somnifera and Plumbago rosea, respectively, have been shown to possess growth inhibitory and radiosensitizing effects on experimental mouse tumours. An aqueous extract of the leaves of Ocimum sanctum (OE) was found to protect mice against radiation lethality. Therefore, the radiomodifying effects of the above plant products on the bone marrow of the adult Swiss mouse was studied. Single doses of WA (30 mg kg-1) or Pl (5 mg kg-1) were injected intraperitoneally (ip) and OE (10 mg kg-1) was injected ip once daily for five consecutive days. Administration of extracts was followed by 2 Gy whole body gamma irradiation. Bone marrow stem cell survival was studied by an exogenous spleen colony unit (CFU-S) assay. The effects of WA and Pl were compared with that of cyclophosphamide (CP) and radioprotection by OE was compared with that of WR-2721 (WR). Radiation reduced the CFU-S to less than 50% of normal. WA, CP and Pl significantly enhanced this effect and reduced the CFU-S to almost the same extent (to < 20% of normal), although individually WA and Pl were less cytotoxic than CP. These results indicate that radiosensitization by WA and Pl is not tumour specific. OE significantly increased CFU-S compared with radiotherapy (RT) alone. OE+RT gave a higher stem cell survival (p < 0.05) than that produced by WR+RT. While WR alone had a toxic effect, OE treatment showed no such effect, suggesting that the latter may have an advantage over WR in clinical application.

A comparative study of radioprotection by Ocimum flavonoids and synthetic aminothiol protectors in the mouse.

The radioprotective effects of two flavonoids, orientin (Ot) and vicenin (Vc), obtained from the leaves of Ocimum sanctum, and the synthetic compounds WR-2721 and MPG (2-mercaptopropionyl glycine) have been compared by examining chromosome aberration in cells of bone marrow in irradiated mice. Healthy adult Swiss mice were injected intraperitoneally (i.p.) with 50 micrograms kg-1 body weight of Ot or Vc; 20 mg kg-1 of MPG; 150 mg kg-1 of WR-2721 or double distilled water (DDW). They were exposed to whole body irradiation of 2.0 Gy gamma radiation 30 min later. After 24 h, chromosomal aberrations were studied in the bone marrow of the femur by routine metaphase preparation after colchicine treatment. Radiation (2 Gy) increased the number of aberrant cells from less than 1% in controls to almost 20%. Pre-treatment with all the protective compounds resulted in a significant reduction in the percentage of aberrant metaphases as well as in the different types of aberration scored. Vc produced the maximum reduction in percent aberrant cells while MPG was the least effective; Ot and WR-2721 showed an almost similar effect. However, WR-2721 was the most effective against reduction of complex an almost similar effect. However, WR-2721 was the most effective against reduction of complex aberrations, followed by Vc. Neither flavonoids had any systemic toxicity, even at 200 mg kg-1 body weight. Considering the low dose needed for protection and the high margin between the effective and toxic doses, the ocimum flavonoids may be promising for human radiation protection.

Multimodality treatment using AK-2123, hydralazine, radiation & hyperthermia on a transplantable mouse tumour.

The in vivo response of a transplantable mouse tumour, Sarcoma 180 to AK-2123 (AK), local irradiation (RT) and local hyperthermia, as influenced by a vasoactive drug, hydralazine (HDZ), was assessed on the basis of tumour cure (complete response CR), volume doubling time (VDT), regrowth delay (RD) and animal survival up to 120 days. A single ip injection of 200 mg/kg b.wt. AK produced more than 15 per cent CR. Combination of any two agents resulted in a better response than the single agent treatments. AK in combination with 43 degrees C, 30 min (HT) was more effective than HT combination with 10 Gy. The presence of 5 mg/kg HDZ, injected immediately after 5 Gy, in combination with AK increased the therapeutic effect over that produced by AK+10Gy. Combination of all the three agents (AK+10Gy+HT) produced 100 per cent CR and prolonged disease free animal survival. A similar response could be obtained by the presence of HDZ with a lower radiation dose of 5 Gy in combination with AK and HT (AK+5Gy+HDZ+HT). This multimodality treatment offers the possibility of further reduction in the doses of individual agents, and in the possible side effects on normal tissues without compromising the tumour cure effect.