Assessment by survival analysis of the radioprotective properties of propolis and its polyphenolic compounds

The radioprotective effects of propolis and polyphenolic compounds from propolis on the radiation-induced mortality of mice exposed to 9 Gy of gamma-irradiation were studied. Intraperitoneal (i.p.) treatment of mice at doses of 100 mg kg(-1) body weight of propolis (water or ethanolic extract; WSDP or EEP) or its polyphenolic compounds (quercetin, naringin caffeic acid, chrysin) consecutively for 3 d before irradiation, delayed the onset of mortality and reduced the symptoms of radiation sickness. All test compounds provided protection against hematopoietic death (death within 30 d after irradiation). The greatest protection was achieved with quercetin; the number of survivors at the termination of the experiment was 63%. According to statistical analyses by the Kaplan-Meier method and the log-rank test, a significant difference between test components and control was found (p<0.001). Treatment with test components after lethal irradiation was ineffective. These results suggest that propolis and its polyphenolic compounds given to mice before irradiation protect mice from the lethal effects of whole-body irradiation.     

Protective effects of fucoidan against γ-radiation-induced damage of blood cells

Fucoidan, a sulfated polysaccharide purified from brown algae including Fucus vesiculosus and Laminaria japonica, has a variety of biological activities, including antioxidant and antitumor activities. Here, we investigated the radioprotective effects of fucoidan on human monoblastic leukemia cell line U937. Further, animal tests were carried out using Balb/c mice in order to determine the radiation-induced changes in the counts of blood cells, including thrombocytes, erythrocytes, leukocytes and hematocrit. Cell viability was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, wherein fucoidan (1, 10, and 100 μg/mL) was observed to improve recovery from damage caused by 8-Gy radiation in a dose dependent manner. The viability of U937 cells pre-treated with fucoidan also increased in a dose dependent manner. Furthermore, fucoidan at 100 mg/kg was found to protect against changes in the counts of blood cells as follows: on day 28 after irradiation, the thrombocyte count in the irradiated controls decreased to 45% compared with the non-irradiated controls, while that in the fucoidan-treated group was 60%. The hematocrit in the fucoidan-treated group recovered to 75% on day 28, while that in the irradiated control was 68%. The erythrocyte count in the irradiated controls consistently ranged from 64% to 67% throughout the experiment, but that in the fucoidan-treated group increased gradually, ranging from 75% to 80%. The mean number of survival days and 50-day actuarial survival rate increased dose dependently in the fucoidan-treated group. The mean number of survival days and the 50-day actuarial survival rate in this group was 16, 21, and 29 days and 12%, 20%, and 30% at fucoidan doses of 1, 10, and 100 mg/kg. The values of these parameters in the control group were 9 days and 0%, although the difference between the test and control groups was not statistically significant. Our results may prove valuable in the field of radioprotection.     

Relationship between radioprotective and neuromotor effects of S-2(3-aminopropyl-amino)ethylphosphorothioate (WR-2721) in mice

The radioprotective and neuromotor effects of WR-2721 were studied in male albino ICR strain mice. The protective activity was evaluated by graded doses of WR-2721 (50-400 mg/kg, IP) against whole body 60Co gamma irradiation at a single maximal lethal threshold dose rad (i.e., 1250 rad). The neuromotor effects of the drug were assayed by its action, at the same dose range as used in the protection assay, on spontaneous motor activity (SMA) and wire hanging performance (WHP). Drug doses were administered 30 min before radiation exposure and neurobehavioral testings. The results showed a dose-dependent increase in radioprotection and an inhibition in the neuromotor tasks. The radioprotective efficacy was seen at doses at which intrinsic neuromotor deficits were detected (100-400 mg/kg). A dose-related parallelism of protective efficacy and neurobehavioral toxicity (i.e., SMA inhibition and WHP disruption) was also observed. The present findings suggest that WR-2721 induces neuromotor dysfunctions along with its radioprotectivity.     

Acute and repeated doses (28 days) oral toxicity study of Vicenin-1, a flavonoid glycoside isolated from fenugreek seeds in laboratory mice

Vicenin-1 (fenugreek glycoside) has been proven to possess potent anti-inflammatory and anti-oxidant activity. The objective of the present investigation was to determine in-vivo acute and subacute (28-days repeated dose) oral toxicity of Vicenin-1 isolated from fenugreek seed. Vicenin-1 (93%) was isolated from a hydroalcoholic extract of fenugreek seed and characterized using HPLC, TLC, ¹H NMR and ¹³C NMR. Acute oral toxicity (AOT) and subacute toxicity studies of Vicenin-1 were carried out according to OECD 425 (up-and-down procedure) and OCED 407 guidelines in Swiss albino mice. In AOT, Vicenin-1 showed 10% mortality when administered at a dose of 5000 mg/kg. However, when vicenin-1 was administered for at doses of 37.5, 75, or 150 mg/kg 28-days it did not show any mortality at the administered doses. Vicenin-1 (75 mg/kg) did not show observational, behavioral, biochemical or histopathological toxic effects. There were minor alterations in body weight, hematology, and histopathology of mice administered with Vicenin-1 (150 mg/kg), but these changes were within normal laboratory ranges. The highest concentration of Venicin-1 was found in liver (3.46%) followed by lung (0.65%). In conclusion, Vicenin-1 showed median lethal dose (LD₅₀) of 4837.5 mg/kg with no-observed-adverse-effect levels (NOAEL) at 75 mg/kg and lowest adverse effect levels (LOAEL) at 150 mg/kg for both sexes of mice during AOT and sub-acute toxicity study, respectively.     

Protective effects of delapril combined with indapamide or hydrochlorothiazide in spontaneously hypertensive stroke-prone rats: a comparative dose-response analysis

In previous articles, we have shown that the combination of the angiotensin-converting enzyme (ACE) inhibitor delapril (12 mg/kg/day) and the diuretic indapamide (1 mg/kg/ day) was able to prolong the life span significantly in salt-loaded stroke-prone spontaneously hypertensive rats (SHRsp). Because this finding was partly dependent on the antagonism of salt-loading effects by pharmacologic induction of diuresis, which prevented any increase in blood pressure values, we decided to evaluate whether lower doses of the combination could be equally protective without changing the progression of hypertension. Thus, we studied several treatments with progressively lower doses of delapril (6, 3, or 1.5 mg/kg/day) combined with indapamide (0.5, 0.25, or 0.125 mg/kg/day) or hydrochlorothiazide (2.5, 1.25, or 0.625 mg/kg/day) in salt-loaded SHRsp. Salt-loaded untreated animals were considered to be the control group. In agreement with previous experiments, control rats reached 50% mortality approximately 7 weeks after the beginning of salt loading. The combination of delapril and hydrochlorothiazide at the two lowest doses was not able to delay animal death significantly, whereas treatment with delapril and indapamide at the lowest dose was effective (50% survival rate, 15 weeks). The groups treated with the highest dose of delapril and hydrochlorothiazide or with the intermediate or highest dose of delapril and indapamide did not reach 50% mortality by the end of the experiment, at 44 weeks of treatment (i.e., when animals reached age 1 year). Only the highest delapril and indapamide doses were able to increase diuresis, but for a relatively short period. None of the treatments was able to lower or control blood pressure levels adequately. Therefore, blood pressure levels by themselves were not predictive of rat mortality. In contrast, the maximal value of proteinuria in the weeks preceding death was inversely correlated with the survival time. In conclusion, this study shows that low doses of an ACE inhibitor in combination with a diuretic can be effectively protective in a model of severe hypertension, independent of any change in blood pressure levels.     

Anxiolytic- and antidepressant-like effects of an antagonist at glycineB receptors

L-701,324 [7-chloro-4-hydroxy-3-(3-phenoxy)phenyl-2-(1H)-quinolone], a selective antagonist at glycineB receptors, was studied in behavioral tests used to predict a potential anxiolytic (conflict drinking test in rats, four-plate test in mice) and antidepressant (forced swimming test in rats and mice) activity. In the conflict drinking test in rats, L-701,324 (0.5 mg/kg, but not 0.25 and 1 mg/kg) increased the number of punished licks in a statistically significant manner. In the four-plate test in mice, L-701,324 (2 mg/kg, but no lower doses) significantly increased the number of punished crossings. In the forced swimming test in rats, L-701,324 (0.5 mg/kg) slightly, but statistically significantly, reduced the immobility time; the drug was inactive in doses of 0.25 and 1 mg/kg. In mice, L-701,324 administered only in the highest dose used (2 mg/kg) significantly shortened the immobility time. L-701,324 (given in doses higher then 2 mg/kg) induced motor impairment in animals. The above findings indicate that L-701,324 shows weak anxiolytic- and antidepressant-like activities in the animal models used.     

Antidotal effects of buprenorphine on the behavioral alterations accompanying cocaine and combined cocaine-ethanol toxicity.

The present study examined the effects of buprenorphine (BUP), a mixed opioid agonist-antagonist, on the behaviors accompanying cocaine (COCA) and combined cocaine-ethanol (EtOH) toxicity in the surviving mice. Using the activity-counting instrument Supermex, the relationship between the toxic signs and the corresponding behavioral alterations could be assessed. In the COCA-only group, a prolonged increase in the activity counts was caused by a high dose of COCA (75 mg/kg ip). Furthermore, this COCA-induced hyperactivity included ataxic behaviors that were accompanied by visible toxic signs, which were not observed in the mice with no drug treatment. A depressive dose of EtOH (3 g/kg ip) did not significantly modify the mortality rate in the COCA-only group in spite of its anticonvulsant effects. However, the peak activity counts in the survivors were attenuated in the COCA-EtOH group as compared to the COCA-only group. BUP attenuated the mortality rate in both COCA and COCA-EtOH groups, even without any anticonvulsant effects, but the most effective dose differed between the COCA (BUP: 0.25 mg/kg ip) and COCA-EtOH (BUP: 0.5 mg/kg ip) groups. At these BUP doses, the prolonged suppression of the morbid hyperactivity in the COCA-BUP group and the restoration of normal behavior in the COCA-EtOH-BUP group both seemed to be correlated with a good prognosis in the survivors; there was an early recovery from an increased blood pressure (BP), increased heart rate (HR) and decreased respiratory rate (RR) in the COCA-BUP group, and an early recovery from a decreased BP, decreased HR and decreased RR in the COCA-EtOH-BUP group.     

Antioxidant and immunomodulatory activity of the alkaloidal fraction of Cissampelos pareira linn

The alkaloidal fraction (AFCP) of roots of Cissampelos pareira Linn. was screened for in-vitro antioxidant activity and immunomodulatory activity in mice. The HPTLC finger print profile was also established for the identification of AFCP which was found to contain 0.176 % of berberine. AFCP possess strong antioxidant activity which was revealed by its ability to scavenge the stable free radical DPPH, superoxide ion and to inhibit lipid peroxidation in rat liver homogenate induced by iron/ADP/Ascorbate complex. AFCP was found to have significant immunosuppressive activity at lower doses (25 and 50 mg/kg) while no activity was observed at higher doses (75 and 100 mg/kg). Humoral antibody titre was significantly (p<0.01) lowered by AFCP at the doses of 25 and 50 mg/kg. Delayed type hypersensitivity response was also significantly (p<0.01) suppressed by the AFCP at the dose of 75 mg/kg. Thus the present study revealed the immunosuppressive and antioxidant activities of the alkaloidal fraction of C. pareira roots.     

The effect of melatonin on peripheral blood cells during total body irradiation in rats

Melatonin, has been reported to participate in the regulation of a number of important physiological and pathological process. It has also the ability to protect the genetic material of hematopoietic cells of mice from damaging effects of acute total body irradiation. The objective of this study was to the potential radioprotective effects of pharmacological doses of melatonin in total body irradiated rat's peripheral blood cells. Forty adult rats were divided into 4 equal groups. Group 1 received no melatonin or irradiation (control group), while group 2 received only melatonin (5 mg/kg, i.p.). Group 3 received only total body irradiation (RT) by 5 Gy of gamma irradiation only and group 4 received RT plus melatonin (5 mg/kg, i.p., 30 min before RT). An hour and a half following RT, blood samples were taken. Leukocytes and thrombocytes number and hemoglobin levels were measured in all groups. Five mg/kg dose of melatonin significantly protected leukocytes and as well as thrombocytes number against y irradiation. There were no significant differences between Hb levels. Our results suggest that melatonin administration prior to irradiation prevented radiation damage on peripheral blood cells. Melatonin radioprotection is achieved by its ability as a scavenger for free radicals generated by ionizing radiation and acts probably as a growth factor, especially for granulocytes in bone marrow.     

Comparison of acute cardiovascular effects of cadmium and captopril in relation to oxidant and angiotensin converting enzyme activity in rats

Cadmium (0.1, 0.32, 1.0 mg/kg i.v.) produced dose dependent hypertensive response in pentobarbitone anesthetized Sprague-Dawley (S-D) rats. The peak hypertensive effect was observed within 15 min of cadmium administration. This response gradually decreased over 1-h observation period. Heart rate did not change significantly. Serum malondialdehyde (MDA) levels increased with cadmium administration. The lower dose of cadmium (0.1 mg/kg i.v.) increased serum MDA to 0.14 +/- 0.02 nmol/mL as compared to 0.12 +/- 0.01 nmol/mL in the control group and was not statistically significant. However, mid (0.32 mg/kg i.v.) and high doses (1.0 mg/kg i.v.) raised serum MDA levels significantly (P < 0.01). Cadmium inhibited serum angiotensin converting enzyme (ACE) levels at all the three tested doses and was statistically significant (P < 0.01). Captopril (1.0, 3.2 mg/kg i.v.) produced a dose dependent mild hypotensive response. The peak effect was observed within 5 min. Cadmium produced inhibition of serum ACE levels, however, a dose response effect was not observed. Captopril (3.2 mg/kg i.v.) decreased serum ACE levels to 5.4 +/- 1.1 U/mL (control levels 10.7 +/- 1.4 U/mL). Serum MDA levels were decreased by captopril treatment. A correlation between serum ACE and MDA following higher dose of cadmium was found. These results indicate that acute administration of cadmium, an inorganic blocker of ACE and calcium channels cadmium produced hypertensive response while captopril produced mild hypotensive response in rats.     

The effect of amifostine, a cytoprotective agent, on paraquat toxicity in mice

Background

Paraquat (PQ) is a highly poisonous herbicide with a variety of toxic effects, most notably pulmonary fibrosis. In alveolar epithelial cells, it is converted to a PQ radical and subsequently generates other reactive species resulting in lipid peroxidation and cell destruction. Amifostine is a thiophosphate prodrug approved by the FDA for the prevention of toxicities associated with cisplatin and therapeutic radiation. When amifostine is converted to an active metabolite (WR-1065), it functions as an oxygen and DNA radical scavenger that has been shown to protect against lipoperoxidation. The aim of this study was to determine whether amifostine improves survival or lung injury resulting from PQ toxicity.

Methods

Swiss mice (n = 23 per group) were given an approximate LD₇₅ dose of PQ intraperitoneal (60 mg/kg). Thirty minutes prior to PQ injection, group 1 was pretreated with 200 mg/kg of amifostine subcutaneously (s.c.). Subsequent doses of amifostine at 75 mg/kg were administered 4 hours after PQ injection, and injections continued every 8 hours for a total of 6 doses (cumulative dose: 575 mg/kg). Four hours after PQ injection, group 2 received 200 mg/kg of amifostine subcutaneously. Subsequent doses of amifostine at 75 mg/kg were administered every 8 hours (cumulative dose: 575 mg/kg). Four hours after PQ injection, group 3 received 100 mg/kg of amifostine subcutaneously. Subsequent doses of amifostine at 30 mg/kg were administered every 8 hours (cumulative dose: 250 mg/kg). Group 4 received equivolume injections of sterile 0.9% saline s.c. at the same time intervals. We removed lungs from all mice for histologic analysis and injury scoring.

Results

The number of surviving mice in groups 1, 2, 3, and 4 were 17, 18, 17, and 17 respectively. The Kaplan-Meier with log rank analysis showed no differences in survival. Lung injury scores did not differ between treatment groups and the control group for either dead or surviving mice.

Conclusion

Amifostine does not appear to improve survival or lung injury due to PQ toxicity at the doses administered.     

The effect methoxsalene on hypnotic and subhypnotic doses of pentobarbital.

The effect of several doses of methoxsalen on hypnotic action of 40 mg/kg of pentobarbital in mice was studied. Methoxsalen was injected 30 minutes before the barbiturate. The highest methoxsalen dose of 22 mg/kg extended the duration of the hypnotic action of pentobarbital about 10 times compared to the control. The effect decreased with time, and 96 hours after this single dose of methoxsalen it was not significantly different from that observed with the control animals receiving only 40 mg/kg pentobarbital. The other methoxsalen doses (10, 5, and 2 mg/kg) exhibited an equal effect on the hypnotic action of pentobarbital, and only in the first measuring time. The effect could not be detected after 24 hours, and no dose dependence was observed. Small doses of methoxsalen of 2 and 1 mg/kg injected 30 minutes before a subhypnotic pentobarbital dose of 30 mg/kg produced sleep in 75% of animals of the both groups. In the control group, this dose produced no sleep in none of the animals.     

Comparison of behavioral and radioprotective effects of WR-2721 and WR-3689.

The behavioral effects of the radioprotectant agents ethiofos, S-2-(3-aminopropylamino)ethylphosphorothioic acid (WR-2721) and S-2-(3-methylaminopropyl)aminoethylphosphorothioic acid (WR-3689) were evaluated in rats trained to respond under a multiple fixed-interval 120-s, fixed-ratio 50-response (mult FI FR) schedule of milk reinforcement. Each compound produced dose-dependent reductions in responding under both schedules over the same dose range (100-180 mg/kg, IP); ED50s indicated that WR-3689 was slightly more potent than WR-2721. On several performance measures, WR-3689 produced greater decrements during a second dose-effect determination, whereas WR-2721 had more pronounced effects during the initial one. In a second series of studies, low (56 mg/kg) and high (180 mg/kg) doses of both drugs were tested for radioprotective effects in rats responding under an FR-50 schedule of milk reinforcement and exposed to a nonlethal (5 gray, Gy) or lethal (10 Gy) dose of ionizing radiation (60Co gamma rays). Neither dose of radiation altered FR response rates on the day of exposure (day 1). Five Gy of gamma radiation produced a 25-40% reduction in response rates on days 2-5 (24-72 h) after exposure. Neither dose of WR-2721 or WR-3689 provided significant protection against these performance decrements. All groups exposed to 10 Gy experienced a progressive decline in FR responding on days 2-5 after exposure. Performance of groups that received pretreatment with the 180-mg/kg dose of either drug or the 56-mg/kg dose of WR-3689 was maintained at significantly higher levels than saline-treated controls on days 4-5 after exposure to 10 Gy; however, even at these higher levels of performance response rates remained below 50% of preirradiation control levels. Subsequently, 56 and 180 mg/kg WR-3689 and 180 mg/kg WR-2721 were found to provide protection against the lethal consequences of the 10-Gy exposure. Thus, neither WR-2721 nor WR-3689 afforded any significant short-term protection against radiation-induced performance decrements when these drugs were administered at either behaviorally ineffective or behaviorally disruptive doses. Rather, the beneficial effects of these drugs paralleled their ability to antagonize radiation-induced lethality.     

Citrus extract modulates genotoxicity induced by cyclophosphamide in mice bone marrow cells

The protective effect of citrus extract was investigated by using the micronucleus assay for anticlastogenic activity in mouse bone marrow cells; liver glutathione (GSH) content was determined against toxicity induced by cyclophosphamide. Mice were orally (gavage) pretreated with solutions of citrus peel extract (Citrus aurantium var. amara) prepared at three different doses (100, 200 and 400 mg kg(-1;) body weight) for 7 consecutive days. Then mice were injected intraperitoneally on the seventh day with cyclophosphamide (50 mg kg(-1)) and after 24 h killed for the evaluation of micronucleated polychromatic erythrocytes (MnPCEs) in bone marrow cells. Non-protein thiol levels in liver were estimated in mice injected with citrus extract with or without cyclophosphamide treatment. Administration of citrus extract before cyclophosphamide treatment significantly reduced the frequency of MnPCEs in mice bone marrow compared with the group treated with cyclophosphamide alone (P<0.0001-0.05). Citrus extract at a dose of 400 mg kg(-1) reduced MnPCEs 2.8 fold against genotoxicity induced by cyclophosphamide. Administration of cyclophosphamide depleted the GSH level in liver. Citrus extract showed excellent scavenging effects on 1,1-diphenyl-2-picryl hydrazyl radical (DPPH) at a concentration of 1.6 mg mL(-1). Application of citrus extract 1 h before cyclophosphamide treatment allowed GSH content to reach the normal level. It appeared that citrus extract, particularly flavonoids constituents with antioxidative activity, may return the GSH level to normal in stress conditions and reduces genotoxicity induced by cyclophosphamide in bone marrow cells.     

Developmental toxicity assessment of arsenic acid in mice and rabbits

To evaluate potential effects of exposure to inorganic arsenic throughout major organogenesis, CD-1 mice and New Zealand White rabbits were gavaged with arsenic acid dosages of 0, 7.5, 24, or 48 mg/kg/d on gestation days (GD) 6 through 15 (mice) or 0, 0.19, 0.75, or 3.0 mg/kg/d on GD 6 through 18 (rabbits) and examined at sacrifice (GD 18, mice; GD 29, rabbits) for evidence of toxicity. Two high-dose mice died, and survivors at the high and intermediate doses had decreased weight gains. High-dose-group fetal weights were decreased; no significant decreases in fetal weight or increases in prenatal mortality were seen at other dosages. Similar incidences of malformations occurred in all groups of mice, including controls. At the high dose in rabbits, seven does died or became moribund, and prenatal mortality was increased; surviving does had signs of toxicity, including decreased body weight. Does given lower doses appeared unaffected. Fetal weights were unaffected by treatment, and there were no effects at other doses. These data revealed an absence of dose-related effects in both species at arsenic exposures that were not maternally toxic. In mice, 7.5 mg/kg/d was the maternal No-Observed-Adverse-Effect-Level (NOAEL); the developmental toxicity NOAEL, while less well defined, was judged to be 7.5 mg/kg/d. In rabbits, 0.75 mg/kg/d was the NOAEL for both maternal and developmental toxicity.     

Comparison of pharmacokinetics and tissue disposition of an antisense phosphorothioate oligonucleotide targeting human Ha-ras mRNA in mouse and monkey

The plasma pharmacokinetics and tissue disposition of ISIS 2503 were studied in mice following single and multiple bolus intravenous (iv) injections of 1-50 mg/kg, and in monkeys following single and multiple 2-h iv infusions of 1-10 mg/kg and bolus iv injections of 1 mg/kg of ISIS 2503. ISIS 2503 and its metabolites were measured in plasma, urine, and tissues using solid-phase extraction followed by capillary gel electrophoresis (CGE). In both species, the plasma clearance of ISIS 2503 was characterized by rapid distribution to tissues, and to a lesser extent, metabolism. The plasma clearance in mice was at least two-fold more rapid than in monkeys at equivalent doses. The plasma disposition (t1/2) increased with dose. The highest concentrations of oligonucleotide were consistently observed in the kidney and liver in both species. At equivalent doses, tissue concentrations in monkeys were much higher than tissue concentrations in mice. Urinary excretion of total oligonucleotide was a minor elimination pathway in both species at doses < 10 mg/kg. However, urinary excretion of total oligonucleotide in mice was increased to 12-29% as dose increased from 20 to 50 mg/kg.     

Anticlastogenic activity of morin against whole body gamma irradiation in Swiss albino mice

Anticlastogenic activity of morin was explored against whole body gamma radiation, at a dose rate of 1.66 Gy/min in Swiss albino mice pretreated intraperitoneal or orally. Pretreatment with morin 10, 25, 50, 75, 100, 125, and 150 mg/kg, i.p. delayed and reduced percentage mortality and increased mean survival times in mice irradiated with 10 Gy gamma radiation. Intraperitoneal route was found superior to oral route. An i.p. dose of 100 mg/kg was found to be the most effective dose in preventing radiation-induced weight loss, increasing the mean survival times and reducing percentage mortality. Morin (100 mg/kg) pretreatment effectively maintained spleen index (spleen weight/body weight x 100) and stimulated endogenous spleen colony forming units. Pretreatment with morin (100 mg/kg) significantly reduced dead, inflammatory, and mitotic cells in irradiated mice jejunum along with a significant increase in goblet cells and rapidly multiplying crypt cells. Morin (100 mg/kg) also maintained the villus height close to normal, prevented mucosal erosion and basement membrane damage in irradiated jejunum. Nuclear enlargement in epithelial cells of jejunum was lower in morin treated mice compared to radiation control. Morin (100 mg/kg) also significantly elevated the endogenous antioxidant enzymes viz. glutathione S transferase (GST), superoxide dismutase (SOD) and reduced glutathione (GSH), in normal mice at 2, 4 and 8 h post treatment. Drastic decrease in endogenous enzymes (GSH, GST, catalase and SOD) and total thiols was observed in irradiated mice at 2, 4 and 8 h post irradiation, while pretreatment with morin (100 mg/kg) prevented this decrease. Morin (100 mg/kg) also elevated radiation LD(50) from 9.2 to 10.1 Gy, indicating a dose modifying factor (DMF) of 1.11.     

In vitro and in vivo evaluation of a melamine dendrimer as a vehicle for drug delivery

Cell-based and acute and subchronic in vivo toxicity profiles of a dendrimer based on melamine reveal that this class of molecules warrants additional study as vehicles for drug delivery. In cell culture, a substantial decrease in viability was observed at 0.1 mg/mL. For the acute studies, mice were administered 2.5, 10, 40 and 160 mg/kg of dendrimer via i.p. injection. At 160 mg/kg, 100% mortality was seen 6-12 h after injection. For the other cohorts, blood chemistry work revealed no renal damage was taking place at 48 h. Liver enzyme activity nearly doubled for the mice treated at 40 mg/kg suggesting hepatotoxicity. For the subchronic studies, three i.p. injections of 2.5-40 mg/kg of dendrimers were administered at 3-week intervals. No mortality was observed. Forty-eight hours following the last administration, blood chemistry revealed no renal damage, but liver damage was indicated by elevated serum enzyme activity at the highest dose. Histopathological data further confirms that doses up to 10 mg/kg show no hepatic damage at subchronic doses. However, subchronic doses at 40 mg/kg lead to extensive liver necrosis.     

Neurobehavioral actions of cannabichromene and interactions with delta 9-tetrahydrocannabinol

1. Neither cannabichromene (CBC) nor delta 9-tetrahydrocannabinol (THC) protected mice from electroshock-induced seizures, although THC inhibited postictal mortality. Minor effects were produced on seizure latency and duration. 2. CBC had a weak analgetic action in mice; THC had a moderate and lengthy effect, which was potentiated at 2 hr by concurrent CBC. 3. Both CBC (10-75 mg/kg, i.p.) and THC (20 mg/kg) reduced motility of mice, the THC equalling the highest dose of CBC. 4. Performance of a conditioned avoidance response was strongly impaired by THC, but not by CBC, nor did CBC combined with THC have influence on the effects of THC.     

Combinations of favipiravir and peramivir for the treatment of pandemic influenza A/California/04/2009 (H1N1) virus infections in mice

Favipiravir, an influenza virus RNA polymerase inhibitor, and peramivir, an influenza virus neuraminidase inhibitor, were evaluated alone and in combination against pandemic influenza A/California/04/2009 (H1N1) virus infections in mice. Infected mice were treated twice daily for 5 d starting 4 h after virus challenge. Favipiravir was 40%, 70%, and 100% protective at 20, 40, and 100 mg/kg/d. Peramivir was 30% protective at 0.5 mg/kg/d, but ineffective at lower doses when used as monotherapy. Combinations of favipiravir and peramivir increased the numbers of survivors by 10-50% when the 0.025, 0.05, and 0.1 mg/kg/d doses of peramivir were combined with 20 mg/kg/d favipiravir and when all doses of peramivir were combined with 40 mg/kg/d favipiravir. Three-dimensional analysis of drug interactions using the MacSynergy method indicates strong synergy for these drug combinations. In addition, an increase in lifespan for groups of mice treated with drug combinations, compared to the most effective monotherapy group, was observed for the 0.025, 0.05, and 0.1 mg/kg/d doses of peramivir combined with favipiravir at the 20 mg dose level. Therefore, the 20 mg/kg/d dose of favipiravir was selected for further combination studies. Increased survival was exhibited when this dose was combined with peramivir doses of 0.1, 0.25 and 0.5 mg/kg/d (1 mg/kg/d of peramivir alone was 100% protective in this experiment). Improved body weight relative to either compound alone was evident using 0.25, 0.5, and 1 mg/kg/d of peramivir. Significant reductions in lung hemorrhage score and lung weight were evident on day 6 post-infection. In addition, virus titers were reduced significantly on day 4 post-infection by combination therapy containing favipiravir combined with peramivir at 0.25 and 0.5 mg/kg/d. These data demonstrate that combinations of favipiravir and peramivir perform better than suboptimal doses of each compound alone for the treatment of influenza virus infections in mice.