Electrophysiological effects of E-5842, a sigma1 receptor ligand and potential atypical antipsychotic, on A9 and A10 dopamine neurons.

Extracellular single unit recording techniques were used to study the effects of the novel potential atypical antipsychotic E-5842, (4-(4-fluorophenyl)-1,2,3,6-tetrahydro-1-[4-(1,2,4-triazol-1-il)bu tyl]pyridine citrate), a preferential sigma1 receptor ligand, on the activity of dopamine cells in substantia nigra pars compacta (A9) and ventral tegmental area (A10) in anesthetized rats. Acute i.v. administration of E-5842 (up to 3.2 mg kg(-1)) did not change the spontaneous activity of the dopamine neurons, which still responded to the inhibitory effect of a subsequent administration of high dose of apomorphine. Acute administration of E-5842 (20 mg kg(-1), i.p.) did not change the number of spontaneously active A9 or A10 dopamine cells. Chronic administration of E-5842 (20 mg kg(-1) day(-1) x 21 days, s.c.) decreased the number of spontaneously active A10 but not A9, dopamine neurons. This effect was reversed by the administration of apomorphine, thus, indicating a possible depolarization inactivation phenomenon. Our results suggest an influence of E-5842 on dopaminergic neurotransmission, although the exact mechanism remains unknown. The effect of E-5842 on A10 is similar, in some ways, to the effects observed with several atypical antipsychotics and suggest the atypicality of the compound and that E-5842 may exert its antipsychotic effects without causing significant extrapyramidal side effects.     

Excitotoxic injury profiles of low-affinity kainate receptor agonists in cortical neuronal cultures.

Neurotoxic profiles of putative agonists for low-affinity kainate subtypes of L-glutamate receptors (GluR5-7) were determined in cultured cortical neurones. Rank order of neurotoxic potency (microM): (S)-5-iodowillardiine (9) approximately = (2S,4R,6E)-2-amino-4-carboxy-7-(2-naphthyl)hept-6-enoic acid (LY339434, 11) > (2S,4R)-4-methylglutamate (33) > kainate (100) > (RS)-2-amino-3-(hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid (ATPA, 360). Using ionotropic glutamate receptor antagonists, neurotoxicity induced by kainate, ATPA and (S)-5-iodowillardiine appeared to involve a GluR5-7 component, unlike LY339434 and (2S,4R)-4-methylglutamate. These putative GluR5-7 agonists exhibited complex excitotoxic profiles highlighting the importance of studying native glutamate receptors.     

Evaluation of the management of tuberculosis in children in Madagascar. Results of a multicentric study

In Madagascar, tuberculosis remains an important cause of morbidity and letality with a Risk of Annual Tubercular Infection about 1% in 1996 in spite of a vaccination rate of 82.6% and tubercular drugs free of charge. In 1995, the National Tubercular Control Program detected 7,000 cases of pulmonary tuberculosis and expected more than 12,000 cases per year. This study was carried out in order to review the management and the treatment of the child tuberculosis in Madagascar. This retrospective study was conducted in four pediatric units of the General hospital of Befelatanana (A and B), Ambohimiandra Hospital and Regional Hospital Centre of Toliara for a twenty four months period from January 1997 to December 1998. All the less than 15-year-old children medical files were consulted. 214 cases were suspected of tuberculosis. 133 of them were treated upon clinical presumption basis and/or radiological exams (33 bacteriological and/or histopathological exams were only realized). 56% of the cases were vaccinated by BCG vaccine. Respiratory diseases with fever motive 46% of hospitalization. The majority of these children are living in poor conditions and 38% of them had malnutrition. Were found as clinical manifestations: 47% of pulmonary tuberculosis (among them 20% were smear-positive pulmonary tuberculosis), 12% had ganglionar tuberculosis, 10% peritoneal tuberculosis, 8% a tubercular meningitis, 5% a Pott-disease and 2% a miliary-disease. Mortality increases with suffocation. 18% of cases died, especially infants and in tubercular meningitis. The authors conclude that management and treatment of tuberculosis need an early diagnosis. But the diagnosis is difficult in front of non specific clinical manifestations in children and due to lack of means and national agreement which settle up diagnosis and therapy. A scoring system based upon clinical signs in agreement with complementary medical tests is desirable.     

Design and synthesis of imidazoline derivatives active on glucose homeostasis in a rat model of type II diabetes. 2. Syntheses and biological activities of 1,4-dialkyl-, 1,4-dibenzyl, and 1-benzyl-4-alkyl-2-(4',5'-dihydro-1'H-imidazol-2'-yl)piperazines and isosteric analogues of imidazoline

Piperazine derivatives have been identified as new antidiabetic compounds. Structure-activity relationship studies in a series of 1-benzyl-4-alkyl-2-(4',5'-dihydro-1'H-imidazol-2'-yl)piperazines resulted in the identification of 1-methyl-4-(2', 4'-dichlorobenzyl)-2-(4',5'-dihydro-1'H-imidazol-2'-yl)piperazine, PMS 812 (S-21663), as a highly potent antidiabetic agent on a rat model of diabetes, mediated by an important increase of insulin secretion independently of alpha2 adrenoceptor blockage. These studies were extended to find additional compounds in these series with improved properties. In such a way, substitution of both piperazine N atoms was first optimized by using various alkyl, branched or not, and benzyl groups. Second, some modifications of the imidazoline ring and its replacement by isosteric heterocycles were carried out, proceeding from PMS 812, to evaluate their influence on the antidiabetic activity. The importance of the distance between the imidazoline ring and the piperazine skeleton was studied third. Finally, the influence of the N-benzyl moiety was also analyzed compared to a direct N-phenyl substitution. The pharmacological evaluation was performed in vivo using glucose tolerance tests on a rat model of type II diabetes. The most active compounds were 1,4-diisopropyl-2-(4', 5'-dihydro-1'H-imidazol-2'-yl)piperazine (41a), PMS 847 (S-22068), and 1,4-diisobutyl-2-(4',5'-dihydro-1'H-imidazol-2'-yl)piperazine (41b), PMS 889 (S-22575), which strongly improved glucose tolerance without any side event or hypoglycemic effect. More particularly, PMS 847 proved to be as potent after po (100 micromol/kg) as after ip administration and appears as a good candidate for clinical investigations.     

Synthesis, biological activity, and conformational analysis of four seco-D-15,19-bisnor-1alpha,25-dihydroxyvitamin D analogues, diastereomeric at C17 and C20.

The synthesis of four CD-ring-modified 19-nor-1alpha, 25-dihydroxyvitamin D(3) derivatives lacking C15, referred to as 6C analogues, and diastereomeric at C17 and C20 is described. The synthesis involves an Ireland-Claisen rearrangement of a 3-methyl-substituted ester of (1R)-3-methyl-2-cyclohexen-1-ol as the key step, followed by elaboration of the side chain, transformation into a C8 cyclohexanone derivative, and final Wittig-Horner coupling with the 19-nor A-ring phosphine oxide. Despite possessing a more flexible side chain than the parent hormone, biological evaluation showed an unexpected superagonistic antiproliferative and prodifferentiating activity (10-50 times higher as compared to that of 1alpha,25(OH)(2)D(3)) for the diastereomer with the "natural" configuration at C17 and C20. The other diastereomers exhibit a 25-90% decrease in activity. All four analogues show a decreased binding affinity (45% or less), and their calcemic activity is 4-400 times less than that of 1alpha,25(OH)(2)D(3). The conformational behavior of their side chain was studied using molecular mechanics calculations, and the result is presented as volume maps. A relative activity volume was determined by subtraction of the volume map of the least active analogue from the volume map of the most active one. This shows three regions corresponding to preferred orientations in space of the side chain of the active analogue. One of these regions was found to overlap with the region that is preferentially occupied by the most active of the four diastereomeric 22-methyl-substituted 1alpha,25(OH)(2)D(3) analogues.     

Effect of loss of DNA mismatch repair on development of topotecan-, gemcitabine-, and paclitaxel-resistant variants after exposure to cisplatin.

Loss of DNA mismatch repair (MMR) causes genomic instability by markedly increasing the frequency of sporadic mutations in both coding and noncoding sequences. Little is known about how loss of MMR affects sensitivity to the mutagenic effect of chemotherapeutic agents. We wanted to determine how loss of MMR affects the ability of cisplatin, a known mutagen, to generate human tumor cell variants resistant to other drugs with which cisplatin is commonly combined in treatment regimens. We compared the ability of cisplatin to produce variants resistant to topotecan, gemcitabine, and paclitaxel in two pairs of MMR-proficient and -deficient cells that included sublines of the human colon carcinoma cell line HCT-116 and sublines of the human endometrial adenocarcinoma cell line HEC59. Cells were exposed to increasing concentrations of cisplatin for 1 h, and the surviving population was tested for the frequency of variants resistant to these single molecular target drugs 10 days later. The frequency of variants increased linearly with cisplatin concentration for all three drugs. Cisplatin was 2.6 +/- 0.3- (S.D.), 3.6 +/- 0.9-, and 2.3 +/- 0.1-fold more potent at producing topotecan-, gemcitabine-, and paclitaxel-resistant variants in the MMR-deficient than in the MMR-proficient HCT116 cells (P <.05 for all). Cisplatin was 1.4 +/- 0.3- and 1.4 +/- 0.4-fold more potent at generating topotecan- and gemcitabine-resistant variants in MMR-deficient HEC59 cells than in MMR-proficient HEC59+ch2 cells. Cisplatin was not more potent in generating paclitaxel-resistant variants in the MMR-deficient HEC59 cells. Spontaneous rates of generation of cells resistant to these three drugs were also measured in the HCT116 sublines. MMR-deficient HCT116 cells exhibited rates of generation of resistant variants that were 1.94- and 1.51-fold higher (P <.05) than those in the MMR-proficient cells for topotecan and gemcitabine, respectively; loss of MMR had no effect on the rate of generation of variants resistant to paclitaxel. We conclude that the loss of MMR increases the ability of cisplatin to generate variants resistant to topotecan, gemcitabine, and possibly paclitaxel and that MMR also plays a role in controlling the spontaneous rate of generation of variants resistant to topotecan and gemcitabine.     

Assessment of the adrenergic effects of orphenadrine in rat vas deferens.

The peripheral adrenergic effects of orphenadrine, an antiparkinsonian drug, have been evaluated in the rat vas deferens to investigate whether these properties are the same as those of other phencyclidine ligands. In the low micromolar range, orphenadrine enhanced electrically-evoked and exogenous noradrenaline contractile responses in the epididymal portion of rat vas deferens. It also induced spontaneous activity that was inhibited by prazosin (1 microM) but not by atropine (20 nM). It inhibited accumulation of [3H]noradrenaline in rat vas deferens (IC50 = 14.2+/-2.3 microM). Orphenadrine competitively inhibited [3H]nisoxetine binding in rat vas deferens membranes (Ki = 1.05+/-0.20 microM). It can be concluded that orphenadrine, at low micromolar concentrations, interacts with the noradrenaline reuptake system inhibiting its functionality and thus potentiating the effect of noradrenaline.     

4-Hydroxy-1-[2-(4-hydroxyphenoxy)ethyl]-4-(4-methylbenzyl)piperidine: a novel, potent, and selective NR1/2B NMDA receptor antagonist.

A structure-based search and screen of our compound library identified N-(2-phenoxyethyl)-4-benzylpiperidine (8) as a novel N-methyl-D-aspartate (NMDA) receptor antagonist that has high selectivity for the NR1/2B subunit combination (IC(50) = 0.63 microM). We report on the optimization of this lead compound in terms of potency, side effect liability, and in vivo activity. Potency was assayed by electrical recordings in Xenopus oocytes expressing cloned rat NMDA receptors. Side effect liability was assessed by measuring affinity for alpha(1)-adrenergic receptors and inhibition of neuronal K(+) channels. Central bioavailability was gauged indirectly by determining anticonvulsant activity in a mouse maximal electroshock (MES) assay. Making progressive modifications to 8, a hydroxyl substituent on the phenyl ring para to the oxyethyl tether (10a) resulted in a approximately 25-fold increase in NR1A/2B potency (IC(50) = 0.025 microM). p-Methyl substitution on the benzyl ring (10b) produced a approximately 3-fold increase in MES activity (ED(50) = 0.7 mg/kg iv). Introduction of a second hydroxyl group into the C-4 position on the piperidine ring (10e) resulted in a substantial decrease in affinity for alpha(1) receptors and reduction in inhibition of K(+) channels with only a modest decrease in NR1A/2B and MES potencies. Among the compounds described, 10e (4-hydroxy-N-[2-(4-hydroxyphenoxy)ethyl]-4-(4-methylbenzyl)piperid ine, Co 101244/PD 174494) had the optimum pharmacological profile and was selected for further biological evaluation.     

Effects of PNU-109,291, a selective 5-HT1D receptor agonist, on electrically induced dural plasma extravasation and capsaicin-evoked c-fos immunoreactivity within trigeminal nucleus caudalis.

We studied the effects of PNU-109291 [(S)-(-)-1-[2-[4-(4-methoxyphenyl)-1-piperazinyl]ethyl]-N-methyl-isoc hroman-6-carboxamide], a receptor agonist showing 5000-fold selectivity for primate 5-HT1D versus 5-HT1B receptors (Ennis et al., J. Med. Chem. 41, 2180-2183), on dural neurogenic inflammation and on c-fos like immunoreactivity within trigeminal nucleus caudalis evoked by electrical and chemical activation of trigeminal afferents, respectively. Subcutaneous injection of PNU-109291 in male guinea pigs dose-dependently reduced dural extravasation of [125I]-labeled bovine serum albumin evoked by trigeminal ganglion stimulation with an IC50 of 4.2 nmol kg(-1). A dose of 73.3 nmol kg(-1) blocked the response completely. The selective 5-HT1B/1D receptor antagonist GR-127935 (> or = 2 micromol kg(-1) i.v.) prevented this effect. In addition, the number of c-fos immunoreactive cells within guinea pig trigeminal nucleus caudalis induced by chemical meningeal stimulation (intracisternally administered capsaicin) was reduced by more than 50% with PNU-109291 (> or = 122.2 nmol kg(-1) administered s.c. 45 min before and 15 min after capsaicin). These data indicate that the 5-HT1D receptor subtype plays a significant role in suppressing meningeal neurogenic inflammation and attenuating trigeminal nociception in these guinea pig models. Since 5-HT1D receptor mRNA and protein are expressed in trigeminal ganglia but not vascular smooth muscle, the 5-HT1D receptor subtype may become a useful therapeutic target for migraine and related headaches.     

Xanthine oxidase inhibitors from Brandisia hancei

Xanthine oxidase is a key enzyme associated with the incidence of hyperuricemia-related disorders. Repeated chromatography of the enzyme inhibitory part of the water extract of the twigs and leaves of Brandisia hancei (Scrophulariaceae) gave a flavone luteolin, an iridoid glycoside mussaenoside, two beta-sitosterol glycosides daucosterol and beta-sitosterol gentiobioside, and five phenylethanoids arenarioside, brandioside, acteoside, 2'-O-acetylacteoside and isoacteoside. Luteolin and isoacteoside inhibited the xanthine oxidase (XO, EC 1.2.3.2) with the IC50 values at 7.83 and 45.48 microM, respectively. Isoacteoside was found to be the first phenylethanoid that decreased substantially the formation of uric acid by inhibiting competitively xanthine oxidase (Ki value: 10.08 microM). Furthermore, the study suggested that the caffeoylation of the 6'-hydroxyl group of the phenylethanoids was essential for the enzyme inhibitory action.