X-Ray Structure and Crystal Lattice Interactions of the Taxol Side-Chain Methyl Ester

A colorless, parallelepiped crystal of methyl (2R,3S)-N-benzoyl-3-phenylisoserinate belonging to the space group P2_l with a = 5.414(4), b = 7.813(1), c = 17.802(7) , = 90.87(4)°, Z = 2, V = 752.9 ³, D _calc = 1.32 g cm^–3, and µ_calc = 1.02 cm^–1 was selected and the structure solved using direct methods. Refinement led to a final R = 0.079 for 819 [F _o 5(F_o)] reflections. Intermolecular hydrogen-bonding interactions are prevalent in the crystal lattice of this compound.     

No effect of a Taql polymorphism in DNA at the endothelin I (EDN1) locus on normal blood pressure level or variability

Endothelin is a peptide reported to be one of the most potent vasoconstrictors known. Presumably, endothelin could play a role in the physiological regulation of blood pressure in healthy or hypertensive people. We have studied a normal restriction fragment length polymorphism (RFLP) at the endothelin-I (EDN1) locus detected with the restriction enzyme TaqI. In three different series comprising 166, 120 and 207 unrelated individuals, we found no evidence for association between genotype in this polymorphism and level of systolic or diastolic blood pressure. In two series of 156 and 117 monozygotic (MZ) twin pairs, respectively, there was no difference between genotypes in within-pair variation in systolic or diastolic blood pressure. Thus neither "level gene" nor "variability gene" effects of normal genes at the EDN1 locus could be detected with the polymorphism analyzed, in healthy population samples.     

Morphological and functional similarities between cultured prostatic stromal cells and testicular peritubular myoid cells.

A number of androgen effects on epithelial cells may be mediated by androgen-regulated paracrine factors produced by underlying mesenchymal cells. In previous studies we demonstrated that prostatic stromal cells and testicular peritubular cells, derived from immature rats, produce mediators of androgen action with identical effects on Sertoli cells. In the present paper we further compared the morphological and functional characteristics of both mesenchymal cell types. Cultured prostatic stromal cells and testicular peritubular cells look identical under phase-contrast microscopy, share the ability to form tubular structures and "balls" when cocultured with Sertoli cells, and contain proteins immunoreactive with an antiserum against alpha-smooth muscle isoactin. Two-dimensional gel electrophoresis shows that the pattern of proteins produced by both cell types is nearly identical. Conditioned media from stromal and peritubular cells contain a factor that stimulates transferrin and cGMP production in Sertoli cells. The behavior of the active principle in the media from both cell types is comparable. On reverse-phase HPLC the elution profile of this factor is comparable for media from both cell types. In conclusion, these data point to a striking similarity in the morphological and functional characteristics of mesenchymal cells cultured from the prostate and testis.     

Hallucinogen-induced rotational behavior in rats

LSD, mescaline, and MDMT (5-methoxy-N,N-dimethyltryptamine) in normal rats induced dose-dependent rotation (circling behavior), which was consistent in direction from week to week (1 week separating hallucinogen administration). The direction of LSD-induced rotation for individual animals was the same as amphetamine-induced, but not apomorphine-induced, rotation. Of the three postsynaptic serotonin antagonists (methysergide, cyproheptadine, and 2-bromo-LSD) tested, only methysergide induced rotation; this rotation was consistent in direction from week to week, and was in the same direction as LSD-induced rotation. l-LSD induced weak rotation and was approximately six times less potent than d-LSD. p-Chlorophenylalanine pretreatment increased the sensitivity to LSD, whereas -methyl-p-tyrosine pretreatment blocked LSD-induced rotation. Simultaneous administration of LSD and amphetamine induced rotation significantly greater than amphetamine alone; a similar effect was observed with LSD plus scopolamine. However, apomorphine plus LSD induced rotation similar in magnitude to apomorphine alone. These results suggest that the mechanism by which hallucinogens induce rotation is consistent with an inhibitory action on the serotonin-containing midbrain raphe neurons. The inhibition of raphe neuronal firing could disinhibit nigrostriatal activity (possibly at the level of the substantia nigra). Methysergide-induced rotation could result from partial antagonism of postsynaptic serotonin receptors in the substantia nigra or striatum. The dopaminergic properties of LSD may attenuate rotation resulting from disinhibition of nigrostriatal activity by interacting with presynaptic nigrostriatal dopamine autoreceptors.     

Pharmacological interactions with circling behaviour induced by the piperidinyl indole derivative RU 23686

When administered i.p. from doses of 10 mg/kg, RU 23686 [5-methoxy 3-(4-piperidinyl) 1H-indole hydrochloride], a drug with relatively weak stimulant properties, induces contralateral (C) circling behaviour in rats with a unilateral electrolytic lesion in the striatum and a more complex effect with ipsilateral (1) and/or C circling in rats with a 6-hydroxydopamine (6-OHDA) lesion in the dopamine (DA) nigro-striatal tract. Interactions of RU 23686 with pharmacological agents have been studied in order to investigate the extent to which different neurotransmitters may be implicated in the circling behaviour induced by this compound.In striatal of 6-OHDA lesioned rats, methyl p-tyrosine (MT) did not modify C turns, while in the latter case only I turns were decreased. FLA 63, propranolol, and desipramine were also inactive in rats with a unilateral striatal lesion. Haloperidol reduced the effects of a 10 mg/kg dose of RU 23686 in striatal lesioned rats but was without effect against a dose of 20 mg/kg; in 6-OHDA lesioned rats, haloperidol blocked induced I turns but either did not affect or increased C turns. Phenoxybenzamine and p-chlorophenylalanine (PCPA), but not methysergide, p-chloroamphetamine (PCA), or fluoxetine, reduced the effect of RU 23686 in rats with a striatal lesion. In nigro-striatal lesioned rats, PCPA exhibited a differing effect according to the predominance of I or C turns: in rats with a mainly C response, C turns were decreased and I turns preserved, whereas in rats with a majority of I responses, these were depressed. In both types of lesions, animals reserpinized 48 h before RU 23686 exhibited an increase in their C circling, even in 6-OHDA lesioned animals where I turns predominated. In both rotational models, apomorphine-induced circling was potentiated by RU 23686.It is concluded that I circling, which is blocked by haloperidol and MT, could be related to a presynaptic action causing DA release. On the other hand, C turns do not depend on apomorphine-sensitive DA receptors in the striatum. A minor or indirect role of 5-hydroxytryptamine (5-HT) containing areas is suggested from the response to PCPA and the lack of effect of other drugs interfering with 5-HT. Results obtained from interactions with phenoxybenzamine, caffeine, and reserpine and the bimodal response to RU 23686 observed in 6-OHDA lesioned rats could indicate an interference with adrenergic processes.     

Studies on human memory: The interactions of diazepam,scopolamine, and physostigmine

Seventy volunteers were injected with diazepam (0.3 mg/kg), scopolamine (8 g/kg), or placebo, followed 70 min later by another injection of physostigmine, physostigmine and methscopolamine (in case of diazepam treatment), or placebo. Physostigmine was given in two doses, 16 and 32 g/kg; methscopolamine, 8 and 16 g/kg. Subjects (Ss) were tested in groups of 5 in a double blind procedure with treatments distributed according to a Latin square design. Prior to treatment, Ss heard a series of lists of words, followed by an immediate recall test. Following the first injection, delayed free recall and recognition tests were given. The second drug was then injected, followed by a presentation of another two sets of lists which were tested similarly. Subjective feelings were also evaluated with a rating questionnaire.Diazepam and scopolamine did not affect recall of information which had been learned prior to drug injection. However, both drugs impaired the learning or acquisition of new information. Physostigmine, especially in its high dose, antagonized most of the memory deficits produced by scopolamine while those of diazepam remained. This is a strong indication that scopolamine acts centrally through an anticholinergic mechanism while diazepam may act through a different system.     

Mapping of c-fos gene expression in the brain during morphine dependence and precipitated withdrawal, and phenotypic identification of the striatal neurons involved

The c-fos gene is expressed in the central nervous system in response to various neuronal stimuli. Using in situ hybridization, we examined the effects of chronic morphine treatment and withdrawal on c-fos mRNA in the rat brain, and particularly within identified striatal neurons. Morphine dependence was induced by subcutaneous implantation of two pellets of morphine for 6 days and withdrawal was precipitated by administration of naltrexone. Placebo animals and morphine-dependent rats showed a very weak c-fos mRNA expression in all the structures studied. Our study emphasized the spatial variations in c-fos mRNA expression, and also revealed a peak expression of c-fos mRNA at 1 h after naltrexone-precipitated withdrawal in the projection areas of dopaminergic neurons, noradrenergic neurons and in several regions expressing opiate receptors. Interestingly, morphine withdrawal induces c-fos mRNA expression in the two efferent populations of the striatum (i.e. striatonigral and striatopallidal neurons) both in the caudate putamen and nucleus accumbens. Moreover, the proportions of activated neurons during morphine withdrawal are different in the caudate putamen (mostly in striatopallidal neurons) and in the shell and core parts of the nucleus accumbens (mostly in striatonigral neurons). The activation of striatopallidal neurons suggests a predominant dopaminergic regulation on c-fos gene expression in the striatum during withdrawal. On the contrary, c-fos induction in striatonigral neurons during withdrawal seems to involve a more complex regulation like opioid-dopamine interactions via the mu opioid receptor and the D1 dopamine receptor coexpressed on this neuronal population or the implication of other neurotransmitter systems.     

Structure‐based design,synthesis, and pharmacologic evaluation tf peptide RGS4 inhibitors

Abstract: Regulators of G‐protein signaling (RGS) proteins form a multifunctional signaling family. A key role of RGS proteins is binding to the G‐protein Gα‐subunit and acting as GTPase‐activating proteins (GAPs), thereby rapidly terminating G protein‐coupled receptor (GPCR) signaling. Using the published RGS4–G_iα1 X‐ray structure we have designed and synthesized a series of cyclic peptides, modeled on the G_iα Switch I region, that inhibit RGS4 GAP activity. These compounds should prove useful for elucidating RGS‐mediated activity and serve as a starting point for the development of a novel class of therapeutic agent.     

联合应用化疗药物对三氧化二砷耐药白血病细胞的毒性实验研究

目的:探讨化疗药物联合应用对三氧化二砷(As2O3)耐药白血病细胞(K562/AS2)的毒性作用。方法:细胞毒实验采用MTT法,二药合用时细胞毒性作用采用ChouTalalay联合指数法分析,细胞表面P糖蛋白(Pgp)和细胞内柔红霉素(DNR)浓度测定采用流式细胞术测定。结果:K562/AS2细胞对三氧化二砷、柔红霉素、鬼臼乙叉苷(VP16)、三尖杉酯碱(H)、米托蒽醌(NVT)和阿糖胞苷(AraC)的耐药倍数分别为7.4、2.9、3.8、3.6、2.8和1.1。K562细胞和K562/AS2细胞的细胞表面Pgp或细胞内任意荧光强度无显著的统计学意义(P>0.05)。As2O3与DNR、VP16、H或NVT联合应用时,对K562、K562/AS2和Pgp表达的白血病细胞(K562/A02)细胞的联合指数均大于1。异搏定与DNR联合应用时,对K562和K562/AS2细胞的联合指数均大于1,但是对K562/A02细胞的联合指数均小于1。结论:K562/AS2细胞对As2O3、DNR、VP16和NVT耐药,其机制与Pgp表达无关。异搏定联合应用DNR可以逆转K562/A02对DNR的耐药性,不能逆转DNR对As2O3耐药细胞的耐药性。As2O3与DN、VP16、H和NVT联合应用时,对K562、K562/AS2和K562/A02细胞的毒性均为拮抗作用。     

Treatment failures secondary to drug interactions with divalent cations and fluoroquinolone

We observed four cases of therapeutic failures while patients were simultaneously taking medications that contained divalent cations and oral fluoroquinolones. Patients improved after conversion to the intravenous formulation of the same antibiotics, proper spacing of the divalent cation, or conversion to a different antibiotic class. Patients prescribed oral fluoroquinolones should receive instructions on proper separations of these antibiotics with divalent cations. Health care professionals should be cognizant of these interactions and educated on their potential deleterious effect.