Baloxavir-oseltamivir combination therapy inhibits the emergence of resistant substitutions in influenza A virus PA gene in a mouse model.

Baloxavir marboxil (BXM) treatment-emergent polymerase acid (PA) I38X amino acid substitution (AAS) in the resistant variants of influenza viruses raise concerns regarding their emergence and spread. This study investigated the impact of 1 or 5 mg/kg BXM and 25 mg/kg oseltamivir phosphate (OS) (single or combination therapy) on the occurrence of resistance-related substitutions during the sequential lung-to-lung passages of AH1N1)pdm09 virus in mice. Deep sequencing analysis revealed that 67% (n = 4/6) of the population treated with BXM single therapy (1 or 5 mg/kg) possessed the treatment-emergent PA-I38X AAS variants (I38T, I38S, and I38V). Notably, BXM-OS combination therapy impeded PA-I38X AAS emergence. Although the doses utilized in the mouse model may not be directly translated into the clinically equivalent doses of each drugs, these findings offer insights toward alternative therapies to mitigate the emergence of influenza antiviral resistance.

Identification of Mycobacterial Genes Involved in Antibiotic Sensitivity: Implications for the Treatment of Tuberculosis with ß-Lactam-Containing Regimens.

In a Mycobacterium smegmatis mutant library screen, transposon mutants with insertions in fhaA, dprE2, rpsT, and parA displayed hypersusceptibility to antibiotics, including the ß-lactams meropenem, ampicillin, amoxicillin, and cefotaxime. Sub-MIC levels of octoclothepin, a psychotic drug inhibiting ParA, phenocopied the parA insertion and enhanced the bactericidal activity of meropenem against Mycobacterium tuberculosis in combination with clavulanate. Our study identifies novel factors associated with antibiotic resistance, with implications in repurposing ß-lactams for tuberculosis treatment.

Targeting the chromosome partitioning protein ParA in tuberculosis drug discovery.

OBJECTIVE: To identify inhibitors of the essential chromosome partitioning protein ParA that are active against Mycobacterium tuberculosis. METHODS: Antisense expression of the parA orthologue MSMEG_6939 was induced on the Mycobacterium smegmatis background. Screening of synthetic chemical libraries was performed to identify compounds with higher anti-mycobacterial activity in the presence of parA antisense. Differentially active compounds were validated for specific inhibition of purified ParA protein from M. tuberculosis (Rv3918c). ParA inhibitors were then characterized for their activity towards M. tuberculosis in vitro. RESULTS: Under a number of culture conditions, parA antisense expression in M. smegmatis resulted in reduced growth. This effect on growth provided a basis for the detection of compounds that increased susceptibility to expression of parA antisense. Two compounds identified from library screening, phenoxybenzamine and octoclothepin, also inhibited the in vitro ATPase activity of ParA from M. tuberculosis. Structural in silico analyses predict that phenoxybenzamine and octoclothepin undergo interactions compatible with the active site of ParA. Octoclothepin exhibited significant bacteriostatic activity towards M. tuberculosis. CONCLUSIONS: Our data support the use of whole-cell differential antisense screens for the discovery of inhibitors of specific anti-tubercular drug targets. Using this approach, we have identified an inhibitor of purified ParA and whole cells of M. tuberculosis.

The effect of zotepine, risperidone, clozapine and olanzapine on MK-801-disrupted sensorimotor gating.

Dizocilpine (MK-801; 0.3 mg/kg i.p.)-induced disruption in prepulse inhibition of the acoustic startle response (PPI) can be preferentially restored by "atypical" antipsychotics. In contrast, some findings indicate that not all of the "atypical" antipsychotics, such as clozapine and risperidone, are effective in restoring the NMDA antagonist-induced deficits in PPI. In our study, we evaluated the effect of four different "atypical" antipsychotic drugs on deficits in PPI induced by MK-801. Zotepine and risperidone have high affinities to D2-like and 5-HT2A receptors, while clozapine and olanzapine have multipharmacological profiles with the highest affinities to serotonin 5-HT1A,2A/2C receptors and muscarinic receptors. Results have shown that MK-801 disrupted PPI and increased the ASR in rats. Our results showed no effect of zotepine (1 and 2 mg/kg) and risperidone (0.1 and 1 mg/kg) on disrupted PPI by MK-801. Administration of clozapine (5 and 10 mg/kg) and olanzapine (2.5 and 5 mg/kg) restored the deficits in PPI induced by MK-801. Additionally, we found a decrease of approximately 46% in PPI after administration of clozapine (5 mg/kg) and olanzapine (2.5 and 5 mg/kg) without MK-801 treatment. In summary, the four "atypical" antipsychotics had different efficacies to restore the disrupted PPI by MK-801. Only clozapine and olanzapin restored the MK-801-induced deficits in PPI.

Elevation of extracellular cortical noradrenaline may contribute to the antidepressant activity of zotepine: an in vivo microdialysis study in freely moving rats.

The antipsychotic, zotepine, as well as possessing affinity for dopamine D1- and D2-1ike receptors, has high affinity for the noradrenaline (NA) transporter and inhibits [3H]NA uptake by rat frontal cortex synaptosomes, in vitro. The present studies investigated the effects of zotepine on extracellular NA in the frontal cortex of freely moving rats using in vivo microdialysis. Removal of calcium from the perfusate reduced extracellular NA by 70.5% and prevented the 50 mM KCl-stimulated increase in NA levels. Zotepine (0.5-1.5 mg kg(-1) i.p.), evoked biphasic, dose-dependent rises in extracellular NA with maximal increases observed at 60 min (+ 171.0%) and 240 min (+ 211.5%) post-treatment. The increases in NA levels were sustained for up to 100 min post-dosing. Clozapine (10.0 mg kg(-1) i.p.), resulted in a smaller, transient increase in NA levels (+ 72.0%) which lasted for 20 min post-treatment. Neither ziprasidone (3.0 mg kg(-1) i.p.) nor olanzapine (1.0 mg kg(-1) i.p.) influenced extracellular NA. Systemic treatment with the antidepressant desipramine (0.3 mg kg(-1) i.p.) resulted in a prolonged elevation of NA levels over 240 min (maximal increase of + 354.3%), whilst local infusion of nisoxetine (1-100 microM) through the dialysis probe increased NA levels in a concentration-dependent manner (up to 587.8% of control values). These data suggest that the inhibition of NA uptake by zotepine and its subsequent prolonged elevation of extracellular cortical NA may underlie the reported antidepressant properties of zotepine in schizophrenic patients.

In vitro and in vivo electrocardiographic evaluation of the novel calcium antagonist monatepil on cardiac conduction system.

Effects of monatepil ([(+/-)-N-(6,11-dihydrodibenzo[b, e]thiepin-11-yl)-4-(p-fluorophenyl)-1-piperazinebutyramide]m aleate, AJ-2615, CAS 103377-41-9), a novel calcium antagonist, on the cardiac conduction system were compared by electrocardiography with those of the existing calcium antagonists (diltiazem, verapamil and nifedipine) in isolated rabbit heart preparations in vitro and in anesthetized and conscious dogs in vivo. Monatepil (10(-7) mol/l) prolonged the atrio-His bundle conduction time (AH interval) in the Langendorff perfused rabbit heart, like diltiazem, verapamil and nifedipine. This prolongation was decreased to 1/10 in the presence of 3.6% bovine serum albumin. In anesthetized dogs, monatepil (0.1-1.0 mg/kg i.v.), unlike diltiazem and verapamil, did not prolong AH interval. In conscious dogs, monatepil even at 100 mg/kg p.o. did not affect electrocardiograms. At the high dose of 300 mg/kg p.o., only a slight prolongation of the QT interval was found, but the QTc interval was not affected. Diltiazem at 10 mg/kg p.o. caused a prolongation of the PR interval and a disappearance of QRS waves. In conscious renal hypertensive dogs, repeated administration of monatepil (10 mg/kg/d p.o. for 29 days) had little effect on the conduction system of the heart examined by electrocardiograms, albeit a persistent fall in blood pressure continued throughout the administration period. The above results suggest that monatepil is a highly safe drug in the treatment of hypertension.

The effect of prednisolone, thromboxane, and platelet-activating factor receptor antagonists on lymphocyte and platelet migration in experimental cardiac transplantation.

Three agents that significantly prolong cardiac allograft survival were tested in Lewis rats that were recipients of hearts from Lewis X Brown-Norway F1 hybrid donors. In the presence of azathioprine, the effects of daily administration of either the thromboxane antagonist (L 640,035), the platelet-activating factor (PAF) antagonist (BN 52021) or prednisolone were evaluated on the infiltration of cardiac allografts by syngeneic lymphocytes and platelets labeled with 111indium. As anticipated, platelet deposition was reduced by the thromboxane antagonist and unaffected by the PAF antagonist; the latter is likely due to the known absence of PAF receptors in rat platelets. In addition prednisolone had no effect. The increased accumulation of lymphocytes on days 4-5 was also unaffected by all three drugs. These experiments indicate that, in this model, graft survival is not necessarily related to lymphocyte and platelet infiltration of the graft. The data also provide evidence for the efficacy of the thromboxane receptor antagonist L 640,035 in preventing platelet deposition in vivo.

Induction of dopaminergic supersensitivity after a single dose of the neuroleptic isofloxythepin.

The development of dopaminergic supersensitivity was evaluated, after single oral administration of the long-acting neuroleptic drug isofloxythepin, in nigrostriatal and tuberoinfundibular system in the rat. Isofloxythepin (5 mg/kg orally) increased concentration homovanillic acid (HVA) in the striatum for up to 24 h after administration, whereas a significant decrease below control values was found after 4-5 days. A similar biphasic effect appeared in behavior, since there was an enhancement of apomorphine stereotypy 4-5 days after administration of isofloxythepin (5 and 10 mg/kg orally). Both findings agree with the hypothesis of development of nigrostriatal dopaminergic supersensitivity at long intervals after isofloxythepin. On the other hand, the increase in prolactin (PRL) secretion induced by isofloxythepin indicated only the blocking action of this drug on dopamine receptors in the tuberoinfundibular system, and provided no evidence for tuberoinfundibular dopaminergic supersensitivity after neuroleptic treatment. It is concluded that a single dose of isofloxythepin is capable of inducing dopaminergic supersensitivity in the nigrostriatal system, but not in the tuberoinfundibular system.

Absence of noxious effects of selected neuroleptics in dominant-lethal mutagenesis assay.

In a dominant-lethal assay in mice the following tricyclic neuroleptics were tested: prothiaden, imipramine, oxyprothepin decanoate and docloxythepin. No dominant-lethal effect was induced by these neuroleptics, even when administered at doses many times as great as clinical doses. The reduced percentages of pregnancies, in females who had copulated with males receiving docloxythepin, observed during and immediately after its administration, were directly connected with marked sedation induced in the males by this neuroleptic.

[Pharmacologic effect of protracted neuroleptics, fluphenazine oenanthate and oxyprothepine oenanthate (VUFB 9447)]. / Die pharmakologische Wirkung der protrahierten Neuroleptika, Fluphenazin-Oenanthat und Oxyprothepin-Oenanthat (VUFB 9447).

Two neuroleptica with protracted effect, i.e. Fluphenazin-Oenanthat and Oxyprothepin-Oenanthat, were tested on rats, dogs and rabbits. It was found that both drugs, after intramuscular injection in doses between 5--30 mg/kg, produced a long-lasting neuroleptic effect, in particular the inhibition of conditioned reflexes in rats, the antagonistic effect against apomorphine vomiting in dogs and the EEG-brain activity specific for neuroleptica. Hardly any differences were found between the effects of the two drugs. Both neuroleptica caused interesting spike activity in the EEG-registration particularly in the limbic structures which have hitherto not been described in the literature.