Substituted benzo[d]oxazol-2(3H)-one derivatives with preference for the sigma1 binding site

We describe here the synthesis and the binding interaction with sigma(1) and sigma(2) receptors of a series of new benzo[d]oxazol-2(3H)-one derivatives variously substituted on the N-benzyl moiety. The results of binding studies confirm the notion that the benzoxazolone moiety confers preference towards sigma(1) sites and establish that the ability to bind to sigma(1), but not to sigma(2) receptors, is strongly affected by the kind and the position of the substituents introduced in the N-benzyl ring. In fact, compounds with substitutions in para-position with atoms of Cl, H or F or with a CH(3) group exhibit a higher affinity for sigma(1) receptors than the corresponding ortho-substituted compounds. The highest affinity and selectivity, with K(i) values of 0.1 and 427 nM for sigma(1) and sigma(2) receptors, respectively, and a corresponding K(i)sigma(2)/K(i)sigma(1) selectivity ratio of 4270 were found for the Cl-substituted compound. These results indicate that benzo[d]oxazol-2(3H)-one derivatives are among the most selective and sigma(1) receptor-preferring ligands currently available.     

Factors affecting oviposition site preference by Toxorhynchites splendens in the laboratory

In a series of laboratory oviposition assays, gravid Toxorhynchites splendens exhibited a preference for cups containing Aedes aegypti larval rearing water, but not for cups containing liquid cultures of bacteria, live Ae. aegypti in distilled water, Ae. aegypti larval holding water with reduced bacterial contamination, or methyl propionate at 0.1, 0.2 and 0.3% in distilled water. Preoviposition flight behavior was elicited by dark-colored containers, but few eggs were deposited if they contained no water. An invisible source of humidity placed in cups enhanced oviposition, but a reflective surface placed in dry cups did not. It is concluded that this species is strongly influenced by humidity and visual stimuli in the acceptance of a site for oviposition.     

Immunization with a plasmid encoding a modified hepatitis B surface antigen carrying the receptor binding site for hepatocytes

Intramuscular injection of a plasmid encoding a modified hepatitis B surface antigen (HBsAg) induced humoral and cytotoxic responses in C57BL/6 mice. This modified HBsAg contains a preS1-derived peptide (amino acids 21 to 47), that carries the HBV receptor binding site for hepatocytes fused to the C-terminus of the small protein (at the position of amino acid 223). After a single DNA injection, the immunized mice elicited high titers of anti-HBs and anti-preS1 antibodies, and produced strong HBV specific cytotoxic T-lymphocyte (CTL) responses. The immune response induced after a single injection of this modified HBsAg gene in HBsAg-transgenic mice resulted in the clearance of circulating HBsAg and the appearance of anti-HBs and anti-preS1 antibodies. The high titers of preS1 antibody in transgenic mice were comparable to those found in non-transgenic controls and may be efficient to clear Dane particles existing in sera from chronic carriers. These data indicated that a genetic vaccine consisting of this modified HBsAg gene may have a potential use for both prophylactic and therapeutic purposes.     

Factors associated with preference for cesarean delivery

OBJECTIVE: To study factors related to preference for cesarean delivery, among pregnant women without medical complications. METHODS: A cross-sectional study was carried out among 156 pregnant women, in a private clinic in the city of Osasco, State of S?o Paulo, from October 2000 to December 2001. The pregnant women were at 28 weeks of pregnancy or more, with no formal contraindication for vaginal delivery at the time of the interview. Sociodemographic data and past and present obstetric history were assessed by applying a questionnaire. The pregnant women were specifically asked what their current preference for delivery was. Pearson's Chi-square test and logistic regression for multivariate analysis were performed with a 5% significance level. RESULTS: Sixty-seven pregnant women (42.9%) said they had little motivation to undergo vaginal delivery. In the multivariate analysis, the following variables were statistically significant: previous vaginal birth (p=0.001; ORadj=0.04; 95% CI=0.01-0.12); husband's monthly income greater than 750 reais (p=0.006, ORadj=3.44; 95% CI=1.38-8.33). The women with a previous vaginal delivery presented 25-fold lower chance of choosing cesarean delivery. The opinion that the previous delivery experience was unsatisfactory was marginally associated with the main outcome (p=0.06; ORadj=0.42; 95% CI=0.16-1.05). CONCLUSIONS: Motivation for cesarean delivery is associated with influences such as the type and degree of satisfaction with previous delivery and income.     

Lipoprotein binding preference of CD36 is altered by filipin treatment

The class B scavenger receptor CD36 binds multiple ligands, including oxidized and native lipoprotein species. CD36 and the related receptor SR-B1 have been localized to caveolae, domains that participate in cell signaling, transcytosis, and regulation of cellular cholesterol homeostasis. Previous work has indicated that the ligand preference of CD36 may depend on the cell type in which it is expressed. To determine if the presence or absence of caveolae is the determining factor for lipoprotein preference, we treated CHO-CD36 and C32 cells with filipin. Filipin treatment rapidly increased the binding capacity of CD36 for the native lipoproteins HDL and LDL, but did not affect the binding capacity of CD36 for oxidized LDL. Filipin treatment affected the distribution of caveolin and CD36 suggesting that the presence caveolae may modulate the ligand preference of CD36. However, its molecular mechanism how CD36 and caveolin interaction in regulating lipoprotein transport remains to be further studied.     

Homology modeling in tandem with 3D-QSAR analyses: a computational approach to depict the agonist binding site of the human CB2 receptor

CB2 receptor belongs to the large family of G-protein coupled receptors (GPCRs) controlling a wide variety of signal transduction. The recent crystallographic determination of human β2 adrenoreceptor and its high sequence similarity with human CB2 receptor (hCB2) prompted us to compute a theoretical model of hCB2 based also on β2 adrenoreceptor coordinates. This model has been employed to perform docking and molecular dynamic simulations on WIN-55,212-2 (CB2 agonist commonly used in binding experiments), in order to identify the putative CB2 receptor agonist binding site, followed by molecular docking studies on a series of indol-3-yl-tetramethylcyclopropyl ketone derivatives, a novel class of potent CB2 agonists. Successively, docking-based Comparative Molecular Fields Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) studies were also performed. The CoMSIA model resulted to be the more predictive, showing r(ncv)(2) = 0.96, r(cv)(2) = 0.713, SEE = 0.193, F = 125.223, and r(2)(pred) = 0.78. The obtained 3D-QSAR models allowed us to derive more complete guidelines for the design of new analogues with improved potency so as to synthesize new indoles showing high CB2 affinity.     

Synthesis and structure-activity relationships of novel arylalkyl 4-benzyl piperazine derivatives as sigma site selective ligands

Continuing our previous work that established that some chromones substituted by an aryl alkyl piperazino alkyl side chain are potent and selective sigma ligands and could be interesting in the treatment of psychosis, we synthesized 60 new compounds, replacing the chromone moiety by various cyclic systems. Many derivatives bind to the sigma sites in the nanomolar range and are generally selective in comparison with 5HT(1A) and the D(2) receptors. One of the most potent ligands of these series, 1-(2-naphthyl methyl)-4-benzyl piperazine 29, has been studied in various pharmacological tests. Although it doesn't have potential in the treatment of psychosis, the results we obtained confirm the data which indicates that such derivatives could be interesting in the treatment of inflammatory diseases.     

Amphiphilic binding site of ethanol in reversed lipid micelles

Proton and phosphorous NMR spectroscopy were used to study a model membrane system consisting of reversed lipid micelles to test the hypothesis that alcohol and anesthetics compete with water for the same hydrogen bonding sites on lipid surfaces. When low concentrations of water and ethanol were added in equal parts in the absence of lipid and nonpolar solvent, the NMR spectrum consisted of a combination of all water and ethanol peaks, except for the ethanol OH peak. Compared with pure water, the bulk water peak became broader and shifted downfield to 5.1. In reversed micelles made of water, DPPC, and nonpolar solvent, the addition of ethanol caused a conspicuous upfield shift of the bulk water peak and also broadened and decreased its height. This effect was magnified as ethanol concentration increased, indicating that alcohol alters the organization of water and moves water protons into a new domain where nearby atoms are more able to shield water protons. Water shifted the P-31 resonant frequency of DPPC downfield, and the effect magnitude varied with water concentration. Ethanol did not cause such a shift, suggesting that only water was interacting in the phosphorous region. Two-dimensional nuclear Overhauser effect (NOESY) spectroscopy indicated that the ethanol methylene is adjacent to the methylene next to the carbonyl of the DPPC fatty acid moiety, at least in some configurations. Interaction at this point is also indicated by the transformation from an apparent pentet to a doublet of triplets at certain ethanol/water ratios.     

Homology modelling and binding site mapping of the human histamine H1 receptor

Three-dimensional model of the human histamine H1 receptor was developed by homology modelling using the high resolution structure of bovine rhodopsin as template. Genetic algorithm based docking calculations were used to identify the role of several amino acids having an effect on agonist or antagonist binding. Binding mode analyses of mepyramine, desloratidine, loratidine and acrivastine allowed us to rationalise their binding affinity. Binding site mapping resulted in seven new potential aromatic interaction points (Tyr 108, Phe 184, Phe 190, Phe 199, Phe 424, Trp 428, Tyr 431), that took part in forming the lipophilic pocket of the antagonist binding cavity.     

Decreased GABAA benzodiazepine binding site densities in postmortem brains of Cloninger type 1 and 2 alcoholics

Ethanol modulates the GABA_A receptor to cause sedative, anxiolytic and hypnotic effects that are qualitatively similar to benzodiazepines and barbiturates. The aim of this study was to explore if GABA_A receptor density is altered in post-mortem brains of anxiety-prone Cloninger type 1 and socially hostile type 2 alcoholic subtypes when compared to controls. The GABA_A binding site density was measured by whole-hemisphere autoradiography with tritium labeled flunitrazepam ([³H]flunitrazepam) from 17 alcoholic (nine type 1, eight type 2) and 10 non-alcoholic post-mortem brains, using cold flumazepam as a competitive ligand. A total of eight specific brain areas were examined. Alcoholics displayed a significantly (p < 0.001, bootstrap type generalizing estimating equations model) reduced [³H]flunitrazepam binding site density when compared to controls. When localized, type 2 alcoholics displayed a significantly (p ≤ 0.05) reduced [³H]flunitrazepam binding site density in the internal globus pallidus, the gyrus dentatus and the hippocampus, whereas type 1 alcoholics differed from controls in the internal globus pallidus and the hippocampus. While previous reports have demonstrated significant alterations in dopaminergic and serotonergic receptors between type 1 and type 2 alcoholics among these same subjects, we observed no statistically significant difference in [³H]flunitrazepam binding site densities between the Cloninger type 1 and type 2 alcoholics.     

Exercise increases the preference for salt in humans

Salt preference was evaluated in 21 male students before and after 1 h routine exercise by measuring their preferred concentration of NaCl in tomato soup. Before exercise, baseline measures of preference were similar to those of 21 matched student controls that did not exercise. Immediately after exercise, the amount of NaCl added to flavour the soup increased by approximately 50% in comparison to pre-exercise baselines and to non-exercising controls. Concentration of sugar flavouring tea was unaltered. Twelve hours after exercise, preferred concentrations of both salt in soup and of sugar in tea were elevated. There were no changes, at any of these time intervals, in the preferences of the control students that did not exercise. These delayed and non-specific changes in preferences are attributed to hunger. However, we speculate that the immediate and specific increase in NaCl preference after exercise is due to sodium loss (in perspiration) and/or sympathetic arousal that activates the hormones, aldosterone and angiotensin II in humans, and that in animals increases salt preference. Our findings provide further evidence for the physiological regulation of salt preference in humans.     

Allelic drop-out may occur with a primer binding site polymorphism for the commonly used RFLP assay for the -1131T>C polymorphism of the Apolipoprotein AV gene

Apolipoprotein AV (ApoAV) gene variant, -1131T>C, is associated with increased triglyceride concentrations in all ethnic groups studied. An MseI based RFLP analysis is the most commonly used method for genotyping this SNP. We genotyped a large cohort comprising 1185 Asian Indians and 173 UK Caucasians for -1131T>C using an ARMS-PCR based tetra-primer method. For quality control, we re-genotyped approximately 10% random samples from this cohort utilizing the MseI RFLP, which showed a 2.9% (3/102) genotyping error rate between the two methods. To investigate further, we sequenced the 900 bp region around the -1131T>C polymorphism in 25 Asian Indians and 15 UK Caucasians and found a number of polymorphisms including the -987C>T polymorphism. Further analysis of the -987C>T SNP showed a higher rare allele frequency of 0.23 in Asian Indians (n = 158) compared to 0.09 in the UK Caucasians (n = 157). This SNP is located 4 bp from the 3' end of the RFLP forward primer and is in weak linkage disequilibrium with -1131T>C variant (r² = 0.084 and D' = 1). Repeated RFLP analysis of seven subjects heterozygous for -987C>T (seven times), showed discordant results with the sequence at -1131T>C SNP nearly one third (15/49) of the time. We conclude that presence of -987C>T polymorphism in the forward primer of the MseI RFLP assay may lead to allelic drop-out and generate unforeseen errors in genotyping the -1131T>C polymorphism. Our results also emphasise the need for careful quality control in all molecular genetic studies, particularly while transferring genotyping methods between various ethnic groups.     

Association of time preference for health with age and disease severity

This study assessed the relationship between time preference for health and age and disease severity. An implicit time preference for health was inferred in 59 patients with chronic obstructive pulmonary disease (COPD) using the time tradeoff method with 10-year and 30-year perspectives. The preference rate was calculated by solving the resulting nonlinear equation, solvable for 50 patients.Among the resulting rates, 4 were negative, 8 zero, and 38 positive. The time preference rate ranged from −10.8% to 75.0%, with a median of 6.6%, and a mean of 11.5%. In correlation analysis, the implicit time preference rate was associated with age;however, there was little association with markers of disease severity. In multivariate analysis, only age was a significant predictor of time preference rate after controlling for the other variables in the model.

     

Toxicity of a Substituted Hydrazine for Turkeys

Turkeys were fed a diet containing 45 ml 1,1-dimethylhydrazine 50 lb feed for three weeks. Mortality did not occur, but turkeys did not eat normal quantities of feed nor did they make normal weight gains during this period. Mild anemia developed after one week. Early ultrastructural evidence of cytopathologic effects in the liver was seen after exposure for one week. An increase of glycogen, deposition of lipid in swollen smooth endoplasmic reticulum, and displacement of mitochondria were noted in the hepatic cells of turkeys exposed to the chemical for two weeks. There was gross, histologic, and electron microscopic evidence of advanced hepatic fatty metamorphosis in turkeys killed after exposure to DMH for three weeks and, as a result, large lipid globules replaced much of the cytoplasm of hepatic cells.     

Imipramine treatment and preference for sweets

Antidepressant-induced changes in food preference were investigated in a group of 40 depressed patients before and during treatment with imipramine. As part of a validated survey, the Pittsburgh Appetite Test, self-reported food preference was categorized by both nutrient and hedonic properties to define individual response. After 4 months of treatment, 14 patients (35%) expressed a clear desire for high-carbohydrate/high-fat foods with a sweet taste. Within this group, eight patients already preferred these foods while medication-free, while six subjects demonstrated a change in preference to these foods during treatment. The other 26 patients (65%) showed no consistent changes in food preference. These results suggest that while approximately one-third of imipramine-treated patients report a preference for sweets, only 15% actually developed this preference during treatment.