Combined antitumor effect of cyclophosphamide and bromodeoxyuridine in BDF1 mice bearing L1210 ascites tumors

We investigated the combined effect of cyclophosphamide (CPA) and 5-bromo-2'-deoxyuridine (BrdUrd) both in mice bearing L1210 ascites tumors and in L1210 leukemic cells in vitro. Administration of BrdUrd (100 mg/kg) for 5 consecutive days before a single dose (80 mg/kg) of CPA significantly extended the survival of mice by 158%, compared with CPA alone. BrdUrd administered at daily doses of 100 or 200 mg/kg for 5 consecutive days did not extended the survival of mice. An in vitro MTT assay revealed that BrdUrd enhanced the cytotoxic effect of 4-hydroxycyclophosphamide, an active form of CPA, in the L1210 cells. These results indicate that BrdUrd enhanced the antitumor effect of CPA both in vivo and in vitro.     

Modulation of phospholipase A activity in psoriatic skin

The activity of phospholipase A2 was tested both in rat skin and human psoriatic skin before and after systemic treatment with a retinoic acid derivative: RO 10-9359. An increase of activity was found in the rat skin homogenates when the animals were treated with 3 mg/kg/day of the drug for 8 days, while no effect was found following treatment with 1.5 mg/kg/day for 10 days. On the contrary a decrease of this activity was found in homogenates from both involved and uninvolved skin of psoriatic patients after systemic treatment with 1-1.5 mg/kg/day for 10 days. These different results are discussed also in the light of the clinical effect of RO 10-9359 on psoriasis.     

Tumor necrosis factor is a terminal mediator in galactosamine/endotoxin-induced hepatitis in mice

Intravenous injection of murine recombinant tumor necrosis factor alpha(TNF-alpha) to male NMRI albino mice in doses greater than 4 micrograms/kg (specific activity 4 x 10(7) U/mg) resulted in a fulminant hepatitis when animals had been sensitized 1 hr before by intraperitoneal administration of 700 mg/kg galactosamine. Liver injury was assessed by measurement of serum transaminases as well as sorbitol dehydrogenase activity 8 hr after administration of TNF-alpha. Pretreatment with either galactosamine or 40 micrograms/kg TNF-alpha alone did not cause hepatitis. Pretreatment of galactosamine/TNF-alpha-injured mice with 800 mg/kg uridine or with 6 mg/kg calmidazolium fully protected the animals, while administration of either verapamil or nifedipine (100 mg/kg, respectively) had no significant effect. The following inhibitors of generation or action of leukotriene D4, which were previously shown to block galactosamine/endotoxin-induced hepatitis in mice, failed to protect against galactosamine/TNF-alpha-induced intoxication: 200 micrograms/kg dexamethasone, 174 mg/kg BW 755 C or 13 x 10 mg/kg FPL 55712. In addition, unlike in the galactosamine/endotoxin model no prevention was achieved by pretreatment of galactosamine/TNF-alpha-injured animals with the following substances blocking the development of an ischemia/reperfusion syndrome: 2 x 100 mg/kg allopurinol, 3.3 x 10(4) U/kg superoxide dismutase, 10(6) U/kg catalase or 10 micrograms/kg iloprost. We conclude from our results that tumor necrosis factor alpha is likely to act as a final mediator of endotoxin action in a sequence of events which includes formation of leukotriene D4 and reactive oxygen species.     

Potentiation of adenosine A1 receptor agonist CPA-induced antinociception by paeoniflorin in mice

The effect of paeoniflorin (PF), a major constituent isolated from Paeony radix, on N6-Cyclopentyladenosine (CPA), a selective adenosine A1 receptor (A1 receptor) agonist, induced antinociception was examined in mice. In the tail-pressure test, CPA (0.05, 0.1, 0.2 mg/kg, s.c.) could induce antinociception in a dose-dependent manner. PF (5, 10, 20 mg/kg, s.c.) alone failed to exhibit any antinociceptive effect in mice; however, pretreatment of PF (20 mg/kg, s.c.) could significantly enhance CPA-induced antinociception. Additionally, pretreatment of 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX, 0.25 mg/kg, s.c.), a selective A1 receptor antagonist, could antagonize the antinociceptive effect of combining CPA with PF. Furthermore, in the competitive binding experiments, PF did not displace the binding of [3H]-8-Cyclopentyl-1,3-dipropylxanthine ([3H]-DPCPX) but displaced that of [3H]-2-Chloro-N6-cyclopentyladenosine ([3H]-CCPA, a selective A1 receptor agonist) to the membrane preparation of rat cerebral cortex. These results suggested that PF might selectively increase the binding and antinociceptive effect of CPA by binding with A1 receptor.     

Malaria-infected mice are cured by oral administration of new artemisinin derivatives

In four or five chemical steps from the 1,2,4-trioxane artemisinin, a new series of 23 trioxane dimers has been prepared. Eleven of these new trioxane dimers cure malaria-infected mice via oral dosing at 3 x 30 mg/kg. The clinically used trioxane drug sodium artesunate prolonged mouse average survival to 7.2 days with this oral dose regimen. In comparison, animals receiving no drug die typically on day 6-7 postinfection. At only 3 x 10 mg/kg oral dosing, seven dimers prolong the lifetime of malaria-infected mice to days 14-17, more than double the chemotherapeutic effect of sodium artesunate. Ten new trioxane dimers at only a single oral dose of 30 mg/kg prolong mouse average survival to days 8.7-13.7, and this effect is comparable to that of the fully synthetic trioxolane drug development candidate OZ277, which is in phase II clinical trials.     

Toxicity and neuropharmacology of cyclopiazonic acid

Cyclopiazonic acid (CPA) was found to have many pharmacological properties in common with the antipsychotic drugs chlorpromazine and reserpine. Thus, in mice CPA at ip doses of 5-14 mg/kg body weight produced hypokinesia, hypothermia, catalepsy, ptosis, sedation without loss of righting reflex, tremor, gait disturbance, dyspnoea, opisthotonus, atypical convulsion and prolonged barbiturate-induced sleep. The ip LD50 of CPA was found to be 13 +/- 0.05 mg/kg. The tremors induced by near-lethal doses of CPA were associated with voluntary or forced movements (action tremors); they worsened during the days following treatment, but they were weak compared with the exhausting and continuous tremors of the whole body caused by 20 mg tremorine/kg (used for comparison). When death occurred only 24-259 min after administration of CPA (11-14 mg/kg), it was preceded by dypsnoea, cyanosis, opisthotonus and clonic leg movements and tonic extension of hind legs (convulsions). When death was delayed (2-6 days after CPA administration), it was preceded by prostration, ptosis, hypothermia, tremor and cessation of food and water intake resulting in cachexia; convulsions were not seen in this group of mice. CPA did not affect the rate of convulsion or death caused by either maximal electroshock or metrazol administration but it did delay the onset of metrazol-induced seizures. In rabbits, 10 mg CPA/kg body weight initially produced tachycardia, tachypnoea and sedation with an activated electroencephalogram. Of three rabbits given 10 mg CPA/kg one died, and in this rabbit slow delta waves were seen just before and during a brief period with clonic leg movements. In this animal death was accompanied by tonic extension of the hind legs, respiratory arrest and cardiac fibrillation; and epileptiform EEG was not seen at any time. The unexpected EEG activation with sedation in rabbits treated with CPA was similar to the effect of reserpine on EEG.     

On the role of central nervous system catecholamines and 5-hydroxytryptamine in the nialamide-induced behavioural syndrome

1. Intraperitoneal administration of nialamide, 200 mg/kg, to mice elicited a pronounced increase in motor activity and rectal temperature concomitant with a gradual increase in the concentrations of 5-hydroxytryptamine (5-HT), noradrenaline (NA) and dopamine in the brain.2. In mice treated with L-tryptophan, 300 mg/kg, 1 h before nialamide, the increase in motor activity appeared earlier than after nialamide alone, and the hyperthermia was more pronounced. The increase in 5-HT concentrations in the brain was more pronounced in these animals, whereas the concentrations of NA and dopamine were of the same magnitude as after nialamide alone.3. Treatment with p-chlorophenylalanine methylester-HCl (PCPA), 400 mg/kg, 24 h before nialamide partially antagonized the increase in motor activity and the accumulation of NA and dopamine was not significantly different from that observed after nialamide alone.4. Treatment with PCPA, 800 mg/kg, 72, 48 and 24 h before nialamide, completely antagonized the increase in motor activity and rectal temperature. The accumulation of brain 5-HT was greatly depressed in these animals. The concentrations of dopamine 1, 3 and 6 h and the concentration of NA 6 h after the nialamide injection were significantly lower in the mice given PCPA 800 mg/kg x 3, than in the mice given nialamide alone.5. Administration of DL-5-hydroxytryptophan, 30 mg/kg, 1 h after the nialamide injection, to mice pretreated with PCPA, 800 mg/kg x 3, restored the increase in motor activity and rectal temperature.6. L-Tryptophan, 300 mg/kg, given 1 h before nialamide to mice pretreated with PCPA, 800 mg/kg x 3, elicited a moderate increase in motor activity and a slight increase in the accumulation of 5-HT in the brain when compared to that after PCPA, 800 mg/kg x 3, and nialamide.7. Administration of alpha-methyltyrosine methylester, 200 mg/kg, 2 h before nialamide partially antagonized the increase in motor activity and completely antagonized the increase in rectal temperature elicited by nialamide alone. The accumulation of brain NA and dopamine was inhibited in these animals.8. It is concluded that the excitation in mice, elicited by nialamide, is mediated largely via brain 5-HT, but that also the brain catecholamines seem to contribute to this effect.     

Analgesic activity of derivatives of 7-amino-2,3-polymethylenindoles and their congeners

Some N-trifluoromethylsulphonyl and N-trifluoroacetylderivatives of 7-amino-2,3-polymethyleneindoles and of 7-amino-3-propylindole [(I) - (XIII)] were prepared and tested, together with corresponding aniline derivates [(XIV) - (XIX)] and with N-trifluoromethylsulphonylcyclopentylamine (XX), against formic acid induced writhings in mice. With very few exceptions, at the oral dose of 0.167 mmole/kg, they proved from 2 to 3.4 times more active than acetanilide.     

Toxicologic evaluation of injectable acemannan in the mouse, rat and dog.

Acemannan, the USAN-accepted name for long-chain polydispersed beta-(1,4)-acetylated polymannose with interspersed 0-acetyl groups with a mannose monomer/acetyl ratio of approximately 1:1 and extracted from Aloe vera (barbadensis Miller), was administered as a 1.0 mg/ml solution to mice, rats and dogs, either as single dose or repeated at 4-d intervals for 8 doses by iv or ip routes. No significant signs of intoxication and no deaths occurred in animals treated with the single injection of acemannan at dosages of 80 mg/kg iv or 200 mg/kg ip in mice, 15 mg/kg iv or 50 mg/kg ip in rats, and 10 mg/kg iv or 50 mg/kg ip in dogs. On repeated injections systemic toxicity was limited to obvious transient discomfort that appeared dose related. There was accumulation of macrophages and monocytes without subsequent inflammatory reaction in lungs of the iv-treated animals, and in liver and spleen and on peritoneal surfaces of ip-treated animals. The effects were not considered adverse, but were consistent with the known immune stimulating activity of acemannan. A few deaths occurred in mice and rats that were suggestive of resulting from improper injection or sequella of necrosis of the injection site. The NOAELs for acemannan determined from these repeated injection studies were 20 mg/kg iv or ip in the mouse, 4.0 mg/kg iv and 50 mg/kg ip in the rat, and 1.0 mg/kg iv in dogs; 5.0 mg acemannan/kg ip in the dog was considered to be LOAEL, based on the emesis and abdominal discomfort induced.     

Morphological and hematological changes in young turkey poults acutely exposed to cyclopiazonic acid

This study characterized morphological changes, further evaluating previously observed gross changes and dehydration () associated with oral administration of CPA to turkey poults. Poults were dosed with cyclopiazonic acid (CPA) at 0, 5, or 10?mg CPA/kg/d orally for 2 days. CPA effects on feed and water intake, hematological values, histology, and cardiac papillary muscle ultrastructure were evaluated. Poults given 10?mg CPA/kg/d had significantly (P?<?0.05) decreased body weight, feed consumption, and water intake at 24 and 48?h. Turkeys administered CPA at 10?mg/kg had significant hematological changes, including leukocytosis, heterophilia, and lymphocytosis. Histopathologic changes consisting of mucofibrinous necrotizing proventriculitis and ventriculitis, multifocal ulcerative enteritis, and mild multifocal granulomatous hepatitis occurred in all poults dosed with 10?mg CPA/kg/d. This study confirmed CPA toxicity in turkeys, exploring a lower dose range of this mycotoxin in a commercially important food species.     

Doxycycline potentiates antitumor effect of cyclophosphamide in mice

Cyclophosphamide (CPA) is a widely used chemotherapeutic drug in neoplasias. It is a DNA and protein alkylating agent that has a broad spectrum of activity against variety of neoplasms including breast cancer. The therapeutic effectiveness of CPA is limited by the high-dose hematopoietic, renal, and cardiac toxicity that accompanies the systemic distribution of liver-derived activated drug metabolites. The present study examines the potential of combining well-tolerated antibiotic doxycycline (DOX) with CPA and understanding the mechanism of cell killing. Interestingly, we found that DOX significantly enhances the tumor regression activity of CPA on xenograft mice model bearing MCF-7 cells. DOX also potentiates MCF-7 cell killing by CPA in vitro. In presence of DOX (3 microg/ml), the IC50 value of CPA decreased significantly from 10 to 2.5 mM. Additional analyses indicate that the tumor suppressor p53 and p53-regulated proapoptotic Bax were upregulated in vivo and in vitro following CPA treatment in combination with DOX, suggesting that upregulation of p53 may contribute to the enhancement of antitumor effect of CPA by DOX. Furthermore, downregulation of antiapoptotic Bcl-2 was observed in animals treated with CPA and CPA plus DOX when compared to untreated or DOX-treated groups. Our results raise the possibility that this combination chemotherapeutic regimen may lead to additional improvements in treatment of breast cancer.     

氧化苦参碱对环磷酰胺抗癌活性和毒性的影响

氧化苦参碱能够诱导小鼠肝细胞微粒体细胞色素P-450。氧化苦参碱与环磷酰胺合用对艾氏癌实体型有协同抑制作用,机制之一为氧化苦参碱提高了环磷酰胺的代谢激活,并使环磷酰胺减少剂量1/2,其抑瘤作用仍相当于原剂量,而环磷酰胺引起白细胞降低的毒性明显减轻。     

The temporal relationship between bacterial lipopolysaccharide and monocrotaline exposures influences toxicity: shift in response from hepatotoxicity to nitric oxide-dependent lethality

Liver injury from a variety of hepatotoxicants, including the food-borne phytotoxin monocrotaline (MCT), can be augmented by exposure to a noninjurious dose of the inflammagen bacterial lipopolysaccharide (LPS). In a previous study, a nontoxic dose of LPS given 4 h after MCT resulted in synergistic hepatotoxicity within 12-18 h. This study was designed to determine whether temporal differences in MCT and LPS exposure affect toxicity. When LPS (3.4 x 10(6) EU/kg; iv) was given one hour before MCT (100 mg/kg; ip), hepatotoxicity developed between 4 and 8 h after MCT administration, and mortality was much greater than when LPS was administered 4 h after MCT. To explore this difference, the temporal relationship between LPS and MCT exposure (7.4 x 10(6) EU/kg and 100 mg/kg, respectively) was altered. Twenty-four-hour survival was high in animals that received LPS 4 h before (86%) or after (88%) MCT, but it decreased markedly when LPS was administered 1 h before MCT (17%). Using this latter dosing regimen, animals became moribund as early as 4 h after MCT administration. Since liver injury was similar from regimens that differed greatly in mortality, death appeared to result from extrahepatic causes. To explore a role for nitric oxide (NO)-induced shock in this regimen, animals were treated with aminoguanidine (AG), an inhibitor of inducible NO synthase, prior to administration of LPS given an hour before MCT. In the cotreated animals, AG significantly attenuated mortality and decreased plasma nitrate/nitrite concentrations, markers of NO biosynthesis. Hence, the primary target of toxicity from MCT and LPS cotreatment appeared to shift from the liver to an extrahepatic site or sites as exposure to these agents occurred closer together temporally. NO appears to be causally involved in the deaths of animals treated with LPS 1 h before MCT.     

Inhibition and induction of drug metabolism by psoralens: alterations in duration of sleep induced by hexobarbital and in clearance of caffeine and hexobarbital in mice.

1. Hexobarbital (100 mg/kg i.p.) sleeping times in male CD-1 mice pretreated (-1 h) with a single i.p. injection of 150 mumol/kg of psoralen or coumarin analogues were increased, most markedly (6-fold) by linear, methoxy-substituted psoralens. 2. Hexobarbital sleeping times of mice which received three daily injections (231 mumol/kg; 50 mg/kg) of 8-methoxypsoralen (8-MOP) were 44% of controls (corn oil). 3. The whole-body half-life of caffeine (1 mg) in mice was 10.2, 1.2, and 0.37 h following 8-MOP (50 mg/kg per day) x 1, vehicle, and 8-MOP x 3 respectively. 4. The whole-body concentrations of hexobarbital (100 mg/kg dose) in mice 30 min after dosing were 14.3 +/- 0.9, 8.4 +/- 0.3, and 5.2 +/- 0.5 micrograms/ml (1 mouse = 150 ml) following 8-MOP (50 mg/kg per day) x 1, vehicle, and 8-MOP x 3 respectively. 5. It is concluded that, administered acutely, psoralen analogues inhibit hexobarbital metabolism in mice; and 8-MOP administered acutely inhibits the metabolism of caffeine and hexobarbital, but administered repeatedly increases their metabolism.     

Cross-tolerance between morphine- and nicotine-induced conditioned place preference in mice

The acquisition of morphine and nicotine conditioned place preference (CPP) and cross-tolerance between the response of two drugs was studied in mice. A biased CPP paradigm was used to study the effect of the agents. Morphine (5 mg/kg) and nicotine (1 mg/kg) induced CPP. Naloxone (0.5, 1 and 2 mg/kg), but not mecamylamine (0.025, 0.05 and 0.1 mg/kg), induced conditioned place aversion (CPA). Both antagonists reversed CPP induced by morphine and nicotine. Administration of one daily dose of morphine (12.5, 25 or 50 mg/kg) for 3 days or nicotine (0.5, 1 or 2 mg/kg) three times a day for 12 days, in order to develop tolerance to the drugs, reduced the conditioning induced by morphine (5 mg/kg) or nicotine (1 mg/kg). CPA-induced by naloxone was reduced in animals, which were rendered tolerant to morphine (50 mg/kg) or nicotine (2 mg/kg). Mecamylamine, however, which did not induce any response in the nontolerant mice, elicited CPP in the tolerant animals. It is concluded that there may be a cross-tolerance between morphine- and nicotine-induced CPP.     

Relationship between schistosomicidal drug efficacy, gonadal steroid hormonal changes and state of disease immunopathology in murine schistosomiasis mansoni

The schistosomicidal efficacy of praziquantel (2 x 500 mg/kg), oxamniquine (1 x 100 mg/kg) and combined one-third the curative dose of each of them (333 mg/kg praziquantel + 33 mg/kg oxamniquine), were correlated to gonadal steroid hormonal changes and state of disease immunopathology, in mice infected with 100 Schistosoma mansoni (S. mansoni) cercariae. Maximum efficacy recorded with combination regimen particularly 4 weeks after treatment, was accompanied by maximum reduction in granuloma volume (65%), least fall in testosterone level (-56.2 and -60.2% in male and female mice respectively) and increased progesterone level (+33.9 and +81.5% in male and female mice respectively). These findings revealed a potentiated effect of combination therapy on mature infection and the possible involvement of gonadal steroid hormones in affecting the efficacy of schistosomicidal drugs and state of disease immunopathology.     

Sertraline and cocaine-induced locomotion in mice

The effects of repeated treatment with the serotonin uptake blocker sertraline on cocaine-induced locomotion in female C57BL/6ByJ mice were examined in three paradigms. First, when animals were treated for 2 weeks with a daily injection of 8 mg/kg IP of sertraline (or placebo) and challenged with cocaine (25 mg/kg IP) 1 h after the final sertraline injection, their cocaine-induced locomotion was the same as that of placebo-pretreated controls. Second, animals were treated for 2 weeks with cocaine (25 mg/kg IP once a day) (or saline) and then for 2 weeks with sertraline (8 mg/kg IP once a day) (or placebo). Locomotion induced by cocaine (25 mg/kg IP) administered 1 h after the final sertraline (placebo) injection was higher in cocaine- than saline-pretreated mice (sensitization), but there was no difference between sertraline- and placebo-pretreated animals. Third, daily treatment with sertraline (8 mg/kg IP) did not change the locomotor stimulatory effect of cocaine (25 mg/kg IP) administered after a 3-week continuous infusion of cocaine (22 mg/kg/day SC) by osmotic minipumps or after three, four, or seven injections of cocaine (15 or 25 mg/kg IP). After cocaine administration (25 mg/kg IP), animals pretreated repeatedly with sertraline (8 mg/kg IP once a day for 2 weeks) had the same plasma or brain levels of cocaine as those pretreated with placebo; there was no difference between cocaine- and saline-treated mice in brain levels of sertraline or desmethylsertraline.     

Carbon monoxide (CO)-induced hypoxia in mice: evaluation as an experimental model of cerebral ischemia for drug screening

An injection of 12.5 ml of carbon monoxide (CO) gas into an air-filled chamber (780 ml in volume) caused the death of the ICR or ddY mouse (6-8 weeks old) inside. The average survival time was 2.5 min for either sex of animals treated with nothing or saline and never exceeded 8 min. Pretreatment with pentobarbital Na (30 mg/kg, i.p.), hopantenate Ca (100 mg/kg, i.p.), vinpocetine (5 mg/kg, i.p. or 50 mg/kg, p.o.), flunarizine HCl (5 mg/kg, i.p.), glucose (6 g/kg, i.p.), phenobarbital (30 mg/kg, i.p.), phenytoin (20 mg/kg, i.p.), arginine HCl (100 mg/kg, i.p. or 1 g/kg, p.o.) and alanine (100 mg/kg, i.p. or 1 g/kg, p.o.) prolonged the survival time of male mice. Insofar as tested, female mice responded rather poorly to these pretreatments. Survival for longer than 8 min occurred in some of the drug-pretreated animals of either sex. To be noted is the finding that most of the animals which survived 8 min once were able to survive the second 8 min on the following day without any drug-treatment. Monitoring of the time course of carboxyhemoglobin formation revealed that the carboxyhemoglobin level reached a plateau of 70% saturation within 2 min and then gradually increased. The lethal level was about 72%. Pentobarbital decreased the formation rate but did not elevate the lethal level. The results indicate that the CO-induced hypoxia model of mice is usable for screening of drug candidates which may be effective for treatment of human ischemic diseases.     

Individual and combined effects of N6-cyclopentyladenosine, flunarizine and diazepam on aminophylline-induced recurrent generalized seizures in mice

Protective effects of anticovulsant agents, N6-cyclopentyladenosine (CPA) and flunarizine (FLN) against aminophylline (AMPH) (280 mg/kg)-induced convulsions were tested in different groups of mice. All drugs were administered by intraperitoneal route. CPA (2 mg/kg and 4 mg/kg) delayed the time to onset of clonic convulsions (p < 0.05). The standard drug diazepam (DZP, 2.5 mg/kg) increased the time to onset of clonic and tonic convulsions to a statistically significant extent (p < 0.05 and p < 0.01, respectively). The AMPH-induced mortality (90.9%) was significantly reduced (p < 0.02) following the test anticonvulsants--CPA (2 mg/kg and 4 mg/kg), FLN (10 mg/kg) and the combination of CPA with FLN (though not to a significant extent), indicating partial involvement of adenosinergic and calcium related mechanisms, while DZP afforded maximum protection. However, none prevented the mortality in mice over 24 h. The results show the lethal effects of AMPH-induced seizures and involvement of multiple and complex neurotransmitter systems in this process which requires further investigation.     

Injurious effect of buthionine sulfoximine, an inhibitor of glutathione biosynthesis, on the lethality and urotoxicity of cyclophosphamide in mice

The effect of buthionine sulfoximine (BSO), a glutathione biosynthesis inhibitor, on the acute lethal toxicity and urotoxicity induced by cyclophosphamide (CPA) was examined in mice. Pretreatment of mice with BSO (500 mg/kg, i.p.) 5 hr prior to CPA resulted in enhanced lethality and urotoxicity of CPA. In contrast, administration of cysteamine decreased the lethality and urotoxicity of CPA.