Cytotoxic and pathogenic properties of Klebsiella oxytoca isolated from laboratory animals

Klebsiella oxytoca is an opportunistic pathogen implicated in various clinical diseases in animals and humans. Studies suggest that in humans K. oxytoca exerts its pathogenicity in part through a cytotoxin. However, cytotoxin production in animal isolates of K. oxytoca and its pathogenic properties have not been characterized. Furthermore, neither the identity of the toxin nor a complete repertoire of genes involved in K. oxytoca pathogenesis have been fully elucidated. Here, we showed that several animal isolates of K. oxytoca, including the clinical isolates, produced secreted products in bacterial culture supernatant that display cytotoxicity on HEp-2 and HeLa cells, indicating the ability to produce cytotoxin. Cytotoxin production appears to be regulated by the environment, and soy based product was found to have a strong toxin induction property. The toxin was identified, by liquid chromatography-mass spectrometry and NMR spectroscopy, as low molecular weight heat labile benzodiazepine, tilivalline, previously shown to cause cytotoxicity in several cell lines, including mouse L1210 leukemic cells. Genome sequencing and analyses of a cytotoxin positive K. oxytoca strain isolated from an abscess of a mouse, identified genes previously shown to promote pathogenesis in other enteric bacterial pathogens including ecotin, several genes encoding for type IV and type VI secretion systems, and proteins that show sequence similarity to known bacterial toxins including cholera toxin. To our knowledge, these results demonstrate for the first time, that animal isolates of K. oxytoca, produces a cytotoxin, and that cytotoxin production is under strict environmental regulation. We also confirmed tilivalline as the cytotoxin present in animal K. oxytoca strains. These findings, along with the discovery of a repertoire of genes with virulence potential, provide important insights into the pathogenesis of K. oxytoca. As a novel diagnostic tool, tilivalline may serve as a biomarker for K oxytoca-induced cytotoxicity in humans and animals through detection in various samples from food to diseased samples using LC-MS/MS. Induction of K. oxytoca cytotoxin by consumption of soy may be in part involved in the pathogenesis of gastrointestinal disease.

The XPF-ERCC1 endonuclease and homologous recombination contribute to the repair of minor groove DNA interstrand crosslinks in mammalian cells produced by the pyrrolo[2,1-c][1,4]benzodiazepine dimer SJG-136

SJG-136, a pyrrolo[2,1-c][1,4]benzodiazepine (PBD) dimer, is a highly efficient interstrand crosslinking agent that reacts with guanine bases in a 5'-GATC-3' sequence in the DNA minor groove. SJG-136 crosslinks form rapidly and persist compared to those produced by conventional crosslinking agents such as nitrogen mustard, melphalan or cisplatin which bind in the DNA major groove. A panel of Chinese hamster ovary (CHO) cells with defined defects in specific DNA repair pathways were exposed to the bi-functional agents SJG-136 and melphalan, and to their mono-functional analogues mmy-SJG and mono-functional melphalan. SJG-136 was >100 times more cytotoxic than melphalan, and the bi-functional agents were much more cytotoxic than their respective mono-functional analogues. Cellular sensitivity of both SJG-136 and melphalan was dependent on the XPF-ERCC1 heterodimer, and homologous recombination repair factors XRCC2 and XRCC3. The relative level of sensitivity of these repair mutant cell lines to SJG-136 was, however, significantly less than with major groove crosslinking agents. In contrast to melphalan, there was no clear correlation between sensitivity to SJG-136 and crosslink unhooking capacity measured using a modified comet assay. Furthermore, repair of SJG-136 crosslinks did not involve the formation of DNA double-strand breaks. SJG-136 cytotoxicity is likely to result from the poor recognition of DNA damage by repair proteins resulting in the slow repair of both mono-adducts and more importantly crosslinks in the minor groove.

Nootropic nefiracetam inhibits proconvulsant action of peripheral-type benzodiazepines in epileptic mutant EL mice

Piracetam and structurally related nootropics are known to potentiate the anticonvulsant effects of antiepileptic drugs. It remains to be seen, however, whether these nootropics inhibit proconvulsant actions of many toxic agents including Ro 5-4864, a specific agonist for peripheral-type benzodiazepine receptors (PBR). The present study was designed to address this issue using EL mice, an animal model of epilepsy. In behavioral pharmacological experiments, EL mice were highly susceptible to convulsions induced by Ro 5-4864 (i.p.) in comparison with nonepileptic DDY mice. Nefiracetam administered orally to EL mice inhibited spontaneous seizures. In DDY mice, convulsions induced by Ro 5-4864 were prevented by nefiracetam when administered by i.v. injection. Aniracetam (i.v.) was partially effective, but piracetam and oxiracetam were ineffective as anticonvulsants. Binding assay for brain tissues revealed a higher density of mitochondrial PBR in EL mice compared with DDY mice. Binding of the PBR ligands Ro 5-4864 to either EL or DDY mouse brain was inhibited by micromolar concentrations of these nootropic agents in the sequence of nefiracetam > aniracetam >> oxiracetam, piracetam. This rank order is identical to potency as anticonvulsants. These data suggest that nefiracetam may prevent toxic effects of PBR agonists through interacting with PBR.

Effects of CCK2 receptor blockade on growth parameters in gastrointestinal tract and pancreas in rats

Gastrin has a growth-promoting effect on the oxyntic mucosa of the stomach but has been claimed also to affect other parts of the gastrointestinal tract and pancreas. This report describes the effects of the cholecystokinin, (CCK2) receptor antagonists YM022 and YF476 on various growth parameters in the gastrointestinal tract and pancreas of the rat. YM022 and YF476 were given subcutaneously in doses known to produce maximum and sustained CCK2 receptor blockade. The body weight was not affected. However, the oxyntic mucosal weight, thickness and protein and DNA contents were reduced by 15-20% already within 1-2 days and by about 30% after 4-8 weeks of CCK2 receptor blockade. Hence, the response of the oxyntic mucosa to CCK2 receptor blockade was in the form of hypotrophy (reduced protein content) and hypoplasia (reduced DNA content). There were no obvious effects of CCK2 receptor blockade on the intestine or pancreas (nor on liver, kidney or thyroid). The proton pump inhibitor omeprazole was used to induce hypergastrinaemia and was given with or without YM022. Omeprazole treatment for 4 weeks increased the oxyntic mucosal weight and thickness by 15-20%. YM022 prevented these effects. We conclude that while elevated circulating gastrin levels, acting on CCK2 receptors, exert a growth-promoting effect on the oxyntic mucosa (but not elsewhere), normal serum gastrin levels exert a mucosa-preserving effect.

The heart rate-corrected QT interval of conscious beagle dogs: a formula based on analysis of covariance

Three frequently used and cited formulas used to rate correct the QT interval (Bazett's, Fridericia's, and Van de Water's) were compared and ranked using a large population-based cohort of beagle dogs (99 males and 99 females). In addition, analysis of covariance was used to derive a flexible method to rate correct the QT.interval for heart rate. The method is flexible in that it utilizes pretest or control data to determine the degree of correction. In addition, it can also be used to evaluate whether treatment alters the association between heart rate and QT. Specifically, pretest QT (unadjusted) and heart rate data were used to estimate coefficients in the linear regression log(QT) = alpha + beta log(HR). The estimated slope (beta) from the pretest data was used to heart rate correct the QT interval in the formula log(QT)ca = log(QT) - beta *[log(HR - log(HRm)]. The term "log(HRm)" is included to standardize QTca to a reference value, either a fixed value or an average heart rate for the data set being analyzed. These formulas were retrospectively compared under a typical toxicity study paradigm with a class III antiarrhythmic agent (L-768,673) that selectively prolongs the QT interval by blocking the slow activating component of the delayed rectifying potassium channel (lks). Based on their ability to dissociate the effects of heart rate on the QT interval, the formulas received the following ranking: Covariate Adjustment (preferred) = Van De Water's > Fridericia's > Bazett's (not recommended). Analysis of covariance based on pretest or control data is preferred for moderate to large studies where there are adequate data for estimation of the slope parameter beta, the investigator does not have sufficient control over HR, or treatment alters the association between HR and the QT interval. Conversely, for smaller studies a fixed rate adjustment formula from the literature (such as Van de Water's or Fridericia's equations) may be preferable since the bias from using a fixed formula is likely to be smaller than the variance resulting from estimating beta from a small sample.

[Changes in the ultrastructure of the motor zone of the cortex and various areas of the rats pyramidal system in acute toxic action of phenazepam]

As it was revealed by electron microscopic study, phenazepam (benzodiazepine representative) administered to rats in acute toxic dose caused astrocyte processes swelling mainly in reticular portion of substantia nigra and cerebral areas with high density of GABAergic synapses in initial intoxication stage (one hour after the drug introduction). Following 24 hrs changes of axodendritic and axo-somatic synapse postsynaptic part were detected similar to those of myoneural synapses induced by anti-cholinesterase agents, which allows to suggest the contribution of the increased intracellular calcium ions content. Specific benzodiazepine receptor agonist-flumazenil, introduced 30 min later than phenazepam leaded to the decrease of ultrastructural changes in postsynaptic part of the synapses in reticular zone of substantia nigra. Thus toxic effect of drugs that cause prolonged activity of peripheral and central synapses postsynaptic part results in the alike ultrastructural changes irrespective of their mediator type and is likely to be connected with the growth of intracellular calcium concentration.

Devazepide-induced hyperplasia in the rat liver and bile ducts

Cholecystokinin (CCK) is a potent stimulus of pancreatic enzyme secretion and growth and is known to influence the flow of biliary secretions. It has also been suggested as a trophic stimulus of the biliary tract and liver, but confirmatory studies are lacking. The aim of the present experiment was to study the effects on the rat liver and biliary tract of long-term stimulation of CCK-8S and the CCK-A receptor antagonist devazepide, respectively. Sprague-Dawley male rats had an infusion of sulfated CCK-8, devazepide or sodium chloride by subcutaneously implanted osmotic minipumps. The animals were sacrified 36 h and 3, 7 or 28 days after the start of infusion, and all had an injection of tritiated thymidine (1 mCi/kg) intraperitoneally 1 h prior to death. The liver was dissected out, weighed and processed for its content of protein, DNA and water. After autoradiography, histologic samples were examined for labeled hepatocytes and bile duct epithelium. Devazepide caused an increase in liver protein content from 36 h on. After 3 days labeling index of hepatocytes and liver DNA concentration were increased. On day 7, induced cell proliferation was also seen in the bile duct epithelium, and the increase in liver DNA content and concentration was now more pronounced and persisted throughout the study. After 28 days devazepide also induced increased crude and relative liver weight. A transient reduction in liver weight and liver protein content and concentration was seen after 7 days of CCK-8S infusion. There were no changes of the labeling index of hepatocytes or bile duct epithelial cells or in liver DNA content in the rats receiving CCK-8S infusion. Devazepide induced hyperplastic changes in both the liver and the biliary tract, probably by interfering with the bile secretion, whereas CCK-8S did not exert any similar effects. The results do not support CCK as a hepatotrophic factor.

Chronic bretazenil produces tolerance to chlordiazepoxide, midazolam, and abecarnil

The purpose of the present study was to determine if chronic treatment with a nonsedative benzodiazepine partial agonist would confer tolerance to the rate-decreasing effects of other benzodiazepine ligands in a fixed-interval procedure in rats. A separate group of rats was treated chronically with the sedative benzodiazepine full agonist, chlordiazepoxide, for comparison. It was hypothesized that tolerance would develop rapidly to chlordiazepoxide due to loss of reinforcement density at rate-decreasing doses and that there would probably be cross-tolerance to other rate-decreasing benzodiazepine ligands such as midazolam and abecarnil. Because bretazenil does not produce rate decreases, however, it was not expected that tolerance would be found to chlordiazepoxide, midazolam, or abecarnil. After 8-12 weeks of chronic treatment with either chlordiazepoxide or bretazenil, however (final dose of benzodiazepine = 30 mg/kg/day), tolerance was found to the rate-decreasing effects of chlordiazepoxide, midazolam, and abecarnil in both groups. It is concluded that such tolerance was most likely due to a saturation of benzodiazepine receptors by this high-affinity partial agonist.

Dysfunction of muscarinic M2 receptors after the early allergic reaction: possible contribution to bronchial hyperresponsiveness in allergic guinea-pigs

1. Using a guinea-pig model of allergic asthma, in which the animals display early (0-5 h) and late phase (8-23 h after antigen challenge) bronchoconstrictor reactions, the function of prejunctional inhibitory M2 and postjunctional M3 receptors in isolated tracheal preparations have been investigated. In addition, cardiac M2 receptor function in vitro and bronchial responsiveness to histamine in vivo were evaluated. 2. Sensitivity to inhaled histamine was increased 3.1 fold and 1.6 fold after the early and late allergic reactions (i.e. at 5 h and 23 h after a single ovalbumin challenge), respectively. At 23 h after the last of four allergen challenges, executed on four consecutive days, bronchial hyperresponsiveness to histamine was diminished to 1.3 fold. 3. After the early response, there was no change in cardiac muscarinic M2 receptor function, since in left atria pD2 (-log EC50) and Emax values of pilocarpine and pKB values of AQ-RA 741, a selective M2 receptor antagonist, were not significantly different from controls (unchallenged sensitized animals), and this also applied to methacholine pD2 values for muscarinic M3 receptors in tracheal smooth muscle. 4. Prejunctional inhibitory muscarinic M2 autoreceptors in airway smooth muscle were markedly dysfunctional after the early allergic response, since potentiation of electrically evoked twitch contractions of tracheal preparations by low concentrations of the M2-selective muscarinic receptor antagonists, gallamine, methoctramine, AQ-RA 741 and AF-DX 116, which is the result of M2 receptor blockade, was clearly and significantly diminished compared to controls. However, after the late response, both in single and repeatedly challenged animals, twitch potentiation was not significantly different from and similar to controls, indicating restoration of M2 receptor function during the late allergic reaction.5. It is concluded that dysfunction of muscarinic M2 autoreceptors in the airways of sensitized and challenged guinea-pigs is already present after the early allergic reaction, and that it has recovered after the late response. Since histamine-induced bronchoconstriction involves vagal pathways, the present results suggest that bronchial hyperresponsiveness to histamine is partly due to M2 auto receptor dysfunction, leading to increased release of acetylcholine.

In vivo modulation of cisplatin cytotoxicity by the cholecystokinin antagonist MK-329 in human pancreatic cancer xenografts

We have previously reported that the cholecystokinin antagonist MK-329 (also known as L-364,718 or devazepide) synergistically enhances sensitivity to cisplatin (DDP) in MIA-PaCa2 human pancreatic cancer cells in tissue culture. In this study, we examined the ability of MK-329 to modulate DDP sensitivity in vivo using MIA-PaCa2 pancreatic cancer xenografts growing subcutaneously in athymic nude mice. Twenty-four hours after tumor inoculation, mice received either DDP intraperitoneally, MK-329 subcutaneously, both DDP and MK-329 or drug vehicles alone. Both DDP and MK-329 alone caused a reduction in the rate of tumor growth. The combination of DDP and MK-329 resulted in enhanced tumor growth delay compared to DDP or MK-329 treated mice. Although MK-329 alone was not nephrotoxic, the addition of MK-329 to DDP treatment resulted in a significant increase in weight loss and nephrotoxicity compared to mice treated with DDP alone; this was reflected by an increase in the plasma BUN levels. Although we believe that the enhanced anti-tumor effect of DDP/MK-329 combination therapy may be independent MK-329's capability to block CCK receptors, the role of CCK receptor blockade in potentiating DDP-induced nephrotoxicity less clear.

[The effect of fenazepam and phenobarbital on the course of pregnancy in rats and on the early postnatal development of their progeny]

Examining the effects of phenazepam and phenobarbital on the course of pregnancy and the development of offsprings has revealed that phenobarbital that has an embryotoxic effect reduced the number of rat offsprings and diminished their weight, but failed to affect the behavioral responses of newborn rats. On the contrary, phenazepam had no embryotoxic effect, but on entering the newborn rats' organism with milk it inhibited some behavioral reactions in the early postnatal period.

Chronic administration of and dependence on halazepam, diazepam, and nordiazepam in the dog

Halazepam administered chronically to dogs in oral doses of 180 and 450 mg/kg/day produced physical dependence which was revealed by a flumazenil precipitated abstinence syndrome and measured by the Nordiazepam Precipitated Abstinence Scale score (NPAS) (McNicholas et al., 1988; Sloan et al., 1990). This abstinence as measured by the NPAS score was more severe in diazepam- and halazepam-dependent than in nordiazepam-dependent dogs whereas the incidence of precipitated clonic seizures was greater in the diazepam- and nordiazepam-dependent than in the halazepam-dependent dogs. Pharmacokinetic studies showed that in the dog the major conversion of halazepam, like diazepam, was to nordiazepam and an oxazepam conjugate. Appreciable quantities of oxazepam, 3-OH halazepam and its conjugated metabolite were also identified in plasma. The NPAS score obtained in the halazepam-dependent dogs, however, was greater than the NPAS score obtained in nordiazepam-dependent dogs who had nordiazepam plasma levels over three times higher than those obtained in the halazepam-dependent dogs. Further, the precipitated abstinence observed in the halazepam-, diazepam- and nordiazepam-dependent dogs differed in qualitative as well as in quantitative aspects including marked differences in the time course of abstinence signs. These data argue that the different dependencies produced by halazepam, diazepam and nordiazepam are not due solely to either the parent compound or to a single metabolite but most likely to their combined effects.

Toxicokinetics of Ro 5-4864, lindane and picrotoxin compared

The effects produced by IP administration of these three agents in the rat were compared because of in vitro evidence that each modulates the picrotoxinin site of the GABAA receptor. For each, hypothermia had the lowest threshold and convulsions the next, with hypophagia produced only by the highest dose of either Ro 5-4864 or lindane. Convulsant effects had a shorter latency and a shorter duration than did hypothermia. Hypophagia, when present, lasted the longest. Myoclonus was the seizure type with the lowest threshold for all three agents. At the highest dose, lindane produced a high incidence of maximal clonic (hopping) seizures, whereas Ro 5-4864 and picrotoxin produced a high incidence of maximal tonic seizures instead. On a mole/kg basis, picrotoxin was 40 times more effective than the other two agents and produced seizures which started later, peaked later, and persisted longest. Ro 5-4864 and lindane were effective at equimolar concentrations and, in combination, produced effects which suggested either dose-addition or synergism. The data are consistent with the hypothesis that the toxic effects of both Ro 5-4864 and lindane may be attributable, at least in part, to an action at a subpopulation of GABAA receptors.

The protective effect of adenosinergic agents, Ro 5-4864 and carbamazepine against hypoxic stress-induced neurotoxicity in mice

Mice subjected to hypoxic stress resulted in increased respiratory rate, tremor and convulsions followed by death. The latencies for convulsion and death following hypoxic stress were 33.29 +/- 1.20 and 34.36 +/- 1.16 min, respectively. In the present study effects of adenosinergic agents Ro 5-4864, a "peripheral-type" benzodiazepine receptor agonist, and carbamazepine were studied on hypoxic stress-induced neurotoxicity. Adenosinergic agents such as adenosine, 2-chloroadenosine, N6-cyclohexyladenosine and dipyridamole increased the latencies for convulsions and death due to hypoxia. Theophylline (50 mg/kg i.p.), an adenosine receptor antagonist, reversed this protective effect of adenosinergic agents. Pretreatment with Ro 5-4864 (10, 20 mg/kg i.p.) also offered theophylline (50 mg/kg, i.p.)-sensitive protection against hypoxic stress. Similarly, carbamazepine treatment (10-30 mg/kg, i.p.) significantly prolonged the latencies for convulsion and death following hypoxic stress. Prior treatment with theophylline (50 mg/kg, i.p.) reversed this protective effect of carbamazepine, indicating the possible involvement of adenosinergic mechanism in the observed protective effect of carbamazepine. These results indicate that the adenosinergic mechanism may be responsible for the observed neuroprotective effect of these agents against hypoxia.

[1,4-Disubstituted 1,3-dihydro-2H-1,5-benzo- and chlorobenzodiazepin-2-ones with activity on the central nervous system]

In pursuing the study on pyridodiazepinone derivatives, in order to verify the variation of biological activity induced by replacement of the heteroaromatic with an aromatic nucleus and by the introduction of chlorine on the benzene ring, a series of 1-[(dialkylamino)alkyl]-4-phenyl-1,3-dihydro-2H-1,4-benzodiazepin- 2-ones and of 7-chloro-analogues were prepared. Some benzodiazepinones and their 7-chloro-analagous were subjected to pharmacological experimentation in order to evaluate and compare their effect upon mice with regard to exploratory activity, motor coordination and spontaneous motility. In addition their anti-strychnine, anti-cardiazole, anti-amphetamine and anti-reserpine activities were also evaluated.

Modulatory effect of alpha 2 adrenoceptor agonists on Ro 5-4864-induced convulsions in rats and mice

The protective effect of various alpha 2 adrenoceptor agonists such as clonidine, guanfacine, B-HT 920 and ICI 106270 was investigated against Ro 5-4864-induced convulsions in mice and rats. Clonidine and ICI 106270 exhibited a profound anticonvulsant effect while equivalent doses of guanfacine and B-HT 920 were less effective. The anticonvulsant effect of clonidine and ICI 106270 was reversed by pretreatment with yohimbine or idazoxan, indicating the involvement of alpha 2 adrenoceptors in their protective effect. Diazepam, clonazepam, CL 218, 872 and pentobarbitone exhibited a different profile of protective action, as these agents protected the animals from apparent mortality as compared to clonidine and ICI 106270 which prolonged the latencies of jerk and convulsion. Modulatory effects of alpha 2 adrenoceptors in central GABA function and multiple sites for Ro 5-4864-induced seizures are explained.

Physical dependence on clonazepam in dogs

Six dogs were, under constant environmental conditions, treated for 7 weeks with clonazepam (0.5 mg/kg b.i.d. orally). Already after 1 week of treatment, slight symptoms of withdrawal could be elicited by intravenous injection of flumazepil (Ro 15-1788). When clonazepam was finally withdrawn, a self-limiting abstinence syndrome was observed in all dogs, consisting of behavioral alterations (listlessness, wet dog shakes, dorsal recumbency), tremor, a severe clonic-tonic seizure in 1 case, hyperthermia, and weight loss. The syndrome was most pronounced on days 2 and 3 after withdrawal, after 1 week all signs of physical dependence had disappeared.

The genetic activity of anthramycin, tomaymycin and sibiromycin in bacterial forward- and reverse-mutation assays and in the mouse bone-marrow micronucleus test

The genetic activity of the structurally similar antitumor antibiotics anthramycin, tomaymycin and sibiromycin was evaluated in the standard Ames Salmonella/microsome mutagenicity assay, a Salmonella typhimurium forward-mutation assay and the micronucleus test. None of the test drugs showed any significant genetic activity in forward or reverse Salmonella mutation assays. The ability of mouse-liver enzymes to produce mutagens from the drugs was examined in the Salmonella reverse-mutation assay and was generally negative. As the concentrations of sibiromycin increased, some activity was detected in the presence of liver S-9 fractions from Aroclor-induced mice. This observation could not be verified at higher concentrations in the reverse-mutation assay due to cytotoxicity, and in the forward-mutation assay due to interference with the selection process by S-9. Cytogenetic evaluation of anthramycin and tomaymycin in the micronucleus test also gave negative results. However, significant increases in the frequency of micronucleated polychromatic erythrocytes were observed in the bone marrow of sibiromycin-treated mice. The results suggest that, except for some possible activity of sibiromycin, these drugs are generally devoid of any marked genetic activity in the test systems employed.

Studies on tomaymycin. III. Synthesis and antitumor activity of tomaymycin analogs

The syntheses and antitumor activity of tomaymycin analogs are described. Structural modification of such parts of tomaymycin as the ethylidenepyrrole ring, animal bond, and substituents of the benzene ring are discussed.

[Table for determining minimal toxic dosage]

The authors suggest a rapid, simple and economical method for the measurement of the minimal toxic dose for the drugs with marked dose-effect dependence. The method is based on the use of the precalculated tables, with minimal consumption of laboratory animals. The data obtained, while providing for statistical significance, make it possible to measure, as the minimal toxic dose, the TD10 rather than the TD16, which raises the method sensitivity.

[Pharmacology of uxepam]

A new daytime tranquilizer uxepam--1-methyl-4-carbamoyl-5-phenyl-7-chloro-1,3,4,5-tetrahydro-2H-1, 4-benzodiazepine-2-on (RGH-3331) administered to animals removes emotional-behavioral abnormalities under conflict situation, reduces aggressiveness induced by electric and painful stimulation, prevents convulsions induced by corasole and electric shock, prolongs the hypnotic effect of hexenal. When applied in high doses the drug suppresses the avoidance reflex, orienting-research behavior and motor activity, disturbs movement coordination. Within wide dosage range uxepam potentiates the summation activity in the central nervous system. As regards anxiolytic activity, the drug does not yield to diazepam and compares very favourably with chlordiazepoxide. The sedative and myorelaxant effects displayed by uxepam are insignificant. The data obtained make it possible to attribute uxepam to daytime tranquilizers.

Acute treatment with pyrrolo(1,4)benzodiazepine antitumor antibiotics alters in vitro hepatic drug metabolizing activity in rats

The pyrrolo(1,4)benzodiazepine antitumor antibiotic, anthramycin, shares a number of toxicities with the widely used anticancer agent adriamycin. We investigated whether acute doses of anthramycin and the structurally related compounds, sibiromycin and tomaymycin, would depress P-450-dependent drug biotransformations as has been reported for adriamycin. Alterations in drug metabolism rates were determined in rats using 50 and 75% of the approximate 7-day LD50 determined in mice. 4 days post dosing ethylmorphine demethylase and aniline hydroxylase activities in liver 9000 g supernatant were depressed from 26 to 76%. Tomaymycin lowered drug metabolism in a dose-related manner, while sibiromycin produced the greatest amount of depression. Like adriamycin, the pyrrolo(1,4)benzodiazepines possess the ability to depress hepatic drug metabolism and therefore may affect the disposition of compounds with which they are co-administered.

Comparative anticonvulsant activity and neurotoxicity of clobazam, diazepam, phenobarbital, and valproate in mice and rats

The 1.5-benzodiazepine (clobazam), the 1,4-benzodiazepine (diazepam), and two nonbenzodiazepine antiepileptic drugs (phenobarbital and valproate) were evaluated in mice and rats with a battery of well-standardized anticonvulsant test procedures. The results obtained indicate that clobazam and valproate exhibit a wider range of experimental anticonvulsant activity than either diazepam or phenobarbital. Except for clobazam by the maximal electroshock seizure (MES) test in rats, clobazam and valproate are effective in nontoxic doses against MES and all four chemically induced seizures (Metrazol, bicuculline, picrotoxin, and strychnine). Clobazam is effective by the MES test in rats only in doses that exceed the median minimal toxic dose. Phenobarbital is effective against all of the above tests, but minimal toxic doses must be employed to prevent strychnine seizures. Diazepam, on the other hand, is effective in nontoxic doses against seizures induced by Metrazol, bicuculline, and picrotoxin, but protects animals from maximal electroshock and strychnine seizures only when given in toxic doses. When compared on the basis of protective indices (PI = TD50/ED50) calculated from intraperitoneal data, the PIs for clobazam were 1.6 to 13 times higher than those for diazepam. Overall, except for the MES test in rats, the PIs for clobazam were from 1.5 to 44 times higher than those for any of the other three substances. With respect to the MES test in rats, the PI for clobazam was 10.8 times higher than that for diazepam; however, the PIs for phenobarbital and valproate were 3.5 and 4.4 times higher, respectively, than that for clobazam. These data suggest that the spectrum of anticonvulsant activity for the 1,5-benzodiazepine (clobazam) is superior to that for the 1,4-benzodiazepine (diazepam). Also, the broad experimental profile of anticonvulsant activity of clobazam agrees well with its reported broad clinical efficacy.

The effect of fasting on oral acute toxicity of drugs in rats and mice

The oral acute toxicity of 3 beta-adrenoceptor stimulants, 2 beta-adrenoceptor blockers, and 2 anti-gastric ulcer drugs was studied in 8-week old, SD-JCL rats and ICR-JCL mice, fasted overnight for 17-20 hours. The results were compared with those from rats and mice allowed to feed normally. The order of the fed:fasted ratio of LD50 values in rats was pirenzepin less than propantheline less than pindolol less than salbutamol less than orciprenaline less than fenoterol less than bunitrolol, and was in the range 1.3-4.7. The increased toxicity in fasted animals was considered to be related to acceleration in gastric emptying and intestinal absorption, but not to a general change in the condition of the test system or a decrease in the detoxification ability of the liver because after intraperitoneal administration acute toxicity was similar in fed and fasted rats.

A toxicologic evaluation of ethyl fluclozepate (CM 6912)

This paper presents the results of acute, subacute, and chronic toxicity studies on ethyl fluclozepate (CM 9612). Acute toxicity was studied in rats and mice of both sexes by oral and intraperitoneal routes. This study established the very low toxicity of this compound. The LD0 by the oral route in these two species is at least higher than 4 g/kg, whereas by the intraperitoneal route the compound has a LD50 of 645 mg/kg at the lowest level. The 3- and 6-month subacute and chronic toxicity studies were carried out in baboons and in rats. The only effects observed during these studies were sedation in the baboon, a slight decrease of the heart rate also in baboons (6 months), and the presence of foam cells in rat lungs after only 6 months of treatment. The sedation and the decrease of heart rate are not toxic effects, but rather the consequence of the anxiolytic activity of CM 6912. Pulmonary foam cells occurred in rats only after a long period of treatment (6 months) and at very high dose levels. This lesion was considered evidence of pulmonary phospholipidosis, a change known to occur frequently with compounds of this nature.

Antitumor effect of a new antibiotic, neothramycin

A new anthramycin-group antitumor antibiotic, neothramycin, isolated from a Streptomyces culture, showed activity against experimental tumors such as lymphocytic leukemia P388 ascites sarcoma-180, hepatoma AH130, Walker carcinosarcoma-256 and mouse mammary adenocarcinoma (CCMT). In particular, the tumor growth inhibition ratio was as high as 96% when neothramycin was injected intraperitoneally at a daily dose of 2 mg/kg into Wistar strain rats previously inoculated with Walker carcinosarcoma-256 by the subcutaneous route. Successive intraperitoneal injections of the compound were more effective than a single injection with the P388 system.

[Development of the progeny in prenatal fhenazepam exposure]

It was established in rat experiments that phenazepam in a dose of 100 mg/kg (1/7 LD50) per os administered during different periods of pregnancy exerts no embryotoxic or teratogenic effects recorded by means of the routine procedures applied in teratologic studies. In a dose of 10 mg/kg, however, phenazepam affects the formation of behavioral reactions in the postnatal period of ontogenesis.

[Preclinical study of the safety of a new tranquilizer, phenazepam]

Chronic toxicity of the benzodiazepine series tranquilizer phenazepam (5 and 50 mg/kg) administered per os for 1.3 and 6 months was studied in experiments on white rats, guinea pigs and dogs. It has been shown during varying time of observation that the drug neither decreases weight gain in the animals nor adversly acts on the blood or produces local irritating action. Histopathological changes in some internal organs proved irreversible. Administered at varying periods of pregnancy, phenazepam at an oral dose of 100 mg/kg exerted no embryotoxic or teratogenic action.

Anticonvulsant action of a 1,5-benzodiazepine, clobazam, in reflex epilepsy

Clobazam, an anxiolytic 1,5-benzodiazepine, has been evaluated as an anticonvulsant in 2 animal models. In mice showing sound induced seizures, clobazam, 1--4 mg/kg, i.p., blocked seizure responses for 1--2 hr. In Senegalese baboons Papio papio showing photically induced myoclonus or seizures, clobazam, 2--12 mg/kg, i.v., totally prevented such responses for up to 6 hr. In baboons pretreated with allylglycine, 170--185 mg/kg, a similar but briefer protection was induced by clobazam. Neurological toxicity was not prominent (transient, slight nystagmus after clobazam, 2--6 mg/kg; muscular hypotonia after clobazam, 12 mg/kg). The possibility that 1,5-benzodiazepines are superior to 1,4-benzodiazepines in the therapy of epilepsy requires clinical investigation.

[In vivo cytogenetic studies of 10-chloro-11b-(2-fluorophenyl)-7-(2-hydroxyethyl)-2, 3, 5, 11b-tetrahydrooxazolo-(3, 2-d) (1, 4) benzodiazepine-6(7H)-one (MS-4101) on rat bone marrow cells (author's transl)]

Chromosome aberrations induced by MS-4101, diazepam, and nitrazepam were studied in Sprague-Dawley rats. Female rats were administered orally via stomach tube daily doses of 200, 500 and 2000 mg/kg of MS-4101, 200 and 500mg/kg of diazepam, 40 and 200mg/kg of nitrazepam and 20 and 50 mg/kg of cylcophosphamide as the positive control for one, 5 and 10 days. In this study, we used bone marrow cells derived from rat femur at 6 or 24 hours after the last drug administration. No significant chromosome aberrations were seen in the treated groups with MS-4101, diazepam, and nitrazepam when compared with the nontreated control. The increase of structural aberration on gap and break was observed in the group of cyclophosphamide as the positive control. These findings indicate that MS-4101, and diazepam and nitrazepam as similar comparative drugs, do not have the potential of induction of chromosome aberrations in rat bone marrow cells.

Central nervous system activity of a novel class of annelated 1,4-benzodiazepines, aminomethylene-2,4-dihydro-1H-imidazo[1,2-a][1,4]benzodiazepin-1-ones

The synthesis and CNS activity of a noval class of annelated 1,4-benzodiazepines, the aminomethylene-2,4-dihydro-1H-imidazo[1,2-a][1,4]benzodiazepines, are described. An investigation of the structure--activity relationships in the series derived from 8-chloro-2,4-dihydro-2-dimethylaminomethylene-6-phenyl-1H-imidazo[1,2-a][1,4]-benzodiazepin-1-one (10) led to the synthesis of a group of compounds with potent minor tranquillizer activity.

Synthesis and central nervous system evaluation of some 5-alkoxy-3H-1,4-benzodiazepin-2(1H)-ones

A series of 1-R-5-alkoxy-3H-1,4-benzodiazepin-2(1H)-ones was prepared and evaluated for central nervous system depressant activity. Several of these compounds, in particular, 7-chloro-5-ethoxy-1-methyl-3H-1,4-benzodiazepin-2(1H)-one (2), gave a profile and activity level similar to diazepam when measured in mice.

Sedative-hypnotic properties of a new benzodiazepine in comparison with flurazepam. Pharmacological and clinical findings

The sedative-hypnotic effects of a new benzodiazepine, 1-(2-hydroxyethyl)-3-hydroxy-7-chloro-1,3-dihydro-5-(o-fluorophenyl)-2H-1,4-benzodiazepin-2-one (SAS 643), were compared with those of flurazepam in mice and rats as well as in a double-blind clinical trial. It was found that SAS 643 has a potency 2--4 times greater than that of flurazepam while it is about one half less toxic than the latter drug. The results of the clinical trial confirm the greater activity of SAS 643 and indicate that the new benzodiazepine causes a significantly less amount of hangover than flurazepam.

Pharmacological properties of 6,7-tetramethylene-5-phenyl-1,2-dihydro-3H-thieno[2,3-e](1,4)-diazepin-2-one (QM-6008, thiadipone), a new psychotropic drug

The pharmacological actions of 6,7-tetramethylene-5-phenyl-1,2,-dihydro-3H-thieno]2,3-e](1,4)-diazepin-2-one (QM-6008, thiadiapone), a new psychotropic drug, have been studied. QM-6008 shares many of the psychosedative effects in rodents of benzodiazepines. The electroencephalographic actions in rats and rabbits of QM-6008 and chlordiazepoxide are also rather similar. This new compounds is endowed with clear conflict attenuating properties in an approach-avoidance schedule and can be considered, in consequence, as a new potentially useful anxiolytic drug. In other operant conditioning procedures in rats--Variable Interval and Discriminated Avoidance--QM-6008 induces an increase in response rate which is not generally shared by chlordiazepoxide. The psychopharmacological data collected in the present work leal to classify this new thienodiazepine derviative within the fram of tranquilizers of the benxodaizapine type. The sedative effects of QM-6008 appear howerer to be less potent and the psychostimulatn effects more markde than those ofchlordiazeposide.