Amino acid transporter SNAT5 localizes to glial cells in the rat brain

The SNAT5 transporter is a neutral amino acid carrier whose function remains unclear. Structural and mechanistically, SNAT5 is closely related to the SNAT3 transporter that mediates the efflux of glutamine from glial cells and that participates in the glutamate-glutamine cycle in the brain. In this study, we have analyzed the distribution of SNAT5 in the rat central nervous system using specific antibodies. Through immunoblotting we observed that SNAT5 is ubiquitously but unevenly distributed in the CNS. It accumulates most intensely in the neocortex, the hippocampus, the striatum, and the spinal cord, whereas moderate levels were found in the thalamus, hypothalamus, and brainstem. Light microscopy revealed that the distribution of SNAT5 paralleled that of the vesicular glutamate transporter vGLUT1 in the forebrain regions, whereas in the diencephalon and brainstem, SNAT5 staining was better correlated with that of vGLUT1 and vGLUT2. However, the cellular localization differed from that of the glutamatergic markers, since SNAT5 was expressed exclusively in astrocyte cell bodies and their processes, ensheathing glutamatergic GABAergic and glycinergic terminals. The presence of SNAT5 in astrocyte processes was confirmed by electron microscopy. They were seen not only to surround different neuronal structures, but they were also found in astrocyte endfeet. Taking into consideration the higher levels of SNAT5 in the neighborhood of glutamatergic terminals and the ability of this transporter family to promote the efflux of amino acids from intracellular stores (including glutamine and perhaps glycine), this transporter is likely to be involved in glutamatergic pathways in the brain.     

Effects of melanocortin receptor activation and blockade on ethanol intake: a possible role for the melanocortin-4 receptor

BACKGROUND: The melanocortin (MC) system is composed of peptides that are cleaved from the polypeptide precursor pro-opiomelanocortin. A growing body of literature suggests that the MC system modulates neurobiological responses to drugs of abuse. Because ethanol has direct effects on central pro-opiomelanocortin activity, it is possible that MC neuropeptides participate in the control of voluntary ethanol consumption. Here we assessed the possibility that MC receptor (MCR) agonists modulate ethanol intake via the MC3 receptor (MC3R) and/or the MC4 receptor (MC4R) and whether the MCR antagonist AgRP-(83-132) controls ethanol consumption. METHODS: Mc3r-deficient (Mc3r) and wild-type (Mc3r) littermate mice were given intraperitoneal (10 mg/kg) and intracerebroventricular (1.0 microg ICV) doses of melanotan II (MTII), a nonselective MCR agonist. To assess the role of MC4R, C57BL/6J mice were given an ICV infusion of the highly selective MC4R agonist cyclo(NH-CH2-CH2-CO-His-d-Phe-Arg-Trp-Glu)-NH2 (1.0 or 3.0 microg). Finally, na?ve C57BL/6J mice were given an ICV infusion of AgRP-(83-132) (0.05 and 1.0 microg). RESULTS: MTII was similarly effective at reducing ethanol drinking in Mc3r-deficient (Mc3r) and wild-type (Mc3r) littermate mice. Furthermore, ICV infusion of the MC4R agonist significantly reduced ethanol drinking, whereas ICV infusion of AgRP-(83-132) significantly increased ethanol drinking in C57BL/6J mice. Neither MTII nor AgRP-(83-132) altered blood ethanol levels at doses that modulated ethanol drinking. CONCLUSIONS: The present results suggest that MC4R, and not MC3R, modulates MCR agonist-induced reduction of ethanol consumption and that ethanol intake is increased by the antagonistic actions of AgRP-(83-132). These findings strengthen the argument that MCR signaling controls ethanol consumption and that compounds directed at MCR may represent promising targets for treating alcohol abuse disorders in addition to obesity.     

Immunological profile of patients awaiting a renal transplant

BACKGROUND: A renal transplant is the best possible treatment for patients with terminal renal failure. Advances in the development of techniques of screening of pre-formed antibodies have contributed to a notable improvement in the results obtained with allogenic transplants. METHODS: The aim of the present work is to study the nature, class, isotype and specificity of antibodies detected in patients awaiting renal transplantation at Complejo Hospitalario Universitario Juan Canalejo, as well as their relation with the level of anti-human leucocyte antigen (HLA) sensitization. RESULTS: In all patient groups, there was a predominance of IgG. The distribution of anti-HLA antibody class showed that the most frequent pattern corresponded to a mixture of class I and class II antibodies for all groups. The study of specificity of anti-HLA antibody showed that of the patients with at least one previous transplant, 72% developed specific anti-HLA antibodies against some of the incompatible antigens of the donor, 12% against HLA antigens not related with the phenotype of the donor and in 16% it was not possible to determine their specificity. Most patients developed antibodies against antigens of locus B, probably because of that the number of incompatibilities contributed by the donors is also greater for locus B. CONCLUSIONS: The exhaustive study of sera of patients on a waiting list for transplantation with respect to the nature, isotype, class and specificity of the antibody is important since it is possible that different antibodies can bring about, in the transplant, events that will have different consequences for the survival of the graft.     

Determination of the beginning of follow-up in longitudinal studies applied to HIV infections

BACKGROUND: In cohort or longitudinal studies, subjects are recruited some time after the beginning of the problem, as in HIV infection. The aim of this paper is to show several imputation techniques of the beginning of follow up and evaluate its use in the framework of a study of HIV progression. METHODS: Three subcohorts of HIV+ subjects recruited in Valencia and Castellón CIPS up to 1996 are available. Seroconversion date was estimated for 244 Seroincidents, 887 seroprevalents with CD4 measurements and 337 without CD4 measurements. For seroincidents midpoint between last HIV- and first HIV+ visits was considered. For prevalent with CD4 serocon version date was imputed from 5 random samples of a progression model of infection to a CD4 level. For prevalent without CD4 seroconversion date was imputed from 5 random samples of HIV incidence density obtained from the other subcohorts. The imputation was repeated 500 times, assigning the seroconversion date as the median of imputations and obtaining confidence limits from 5 and 95 percentiles. Imputation validity was tested comparing time to AIDS and death for each one of the 3 groups. RESULTS: 443 and 405 deaths were observed among the 1468 subjects. Median of seroconversion was January 1993 for incidents, January 1991 for prevalents with CD4 and November 1988 for prevalents without CD4. The latest group showed a worse survival and AIDS free time compared to the other two cohorts. CONCLUSIONS: The imputation tools used showed their usefulness to reduce the survival bias in observational studies. Their generalization depends on the viability of incident cohorts, the availability of a progression marker or a origin on time.     

Tumor cell-specific BRCA1 and RASSF1A hypermethylation in serum, plasma, and peritoneal fluid from ovarian cancer patients

Because existing surgical and management methods can consistently cure only early-stage ovarian cancer, novel strategies for early detection are required. Silencing of tumor suppressor genes such as p16INK4a, VHL, and hMLH1 have established promoter hypermethylation as a common mechanism for tumor suppressor inactivation in human cancer and as a promising target for molecular detection in bodily fluids. Using sensitive methylation-specific PCR, we screened matched tumor, preoperative serum or plasma, and peritoneal fluid (washes or ascites) DNA obtained from 50 patients with ovarian or primary peritoneal tumors for hypermethylation status of the normally unmethylated BRCA1 and RAS association domain family protein 1A tumor suppressor genes. Hypermethylation of one or both genes was found in 34 tumor DNA (68%). Additional examination of one or more of the adenomatous polyposis coli, p14ARF, p16INK4a, or death associated protein-kinase tumor suppressor genes revealed hypermethylation in each of the remaining 16 tumor DNA, which extended diagnostic coverage to 100%. Hypermethylation was observed in all histologic cell types, grades, and stages of ovarian tumor examined. An identical pattern of gene hypermethylation was found in the matched serum DNA from 41 of 50 patients (82% sensitivity), including 13 of 17 cases of stage I disease. Hypermethylation was detected in 28 of 30 peritoneal fluid DNA from stage IC-IV patients, including 3 cases with negative or atypical cytology. In contrast, no hypermethylation was observed in nonneoplastic tissue, peritoneal fluid, or serum from 40 control women (100% specificity). We conclude that promoter hypermethylation is a common and relatively early event in ovarian tumorigenesis that can be detected in the serum DNA from patients with ovary-confined (stage IA or B) tumors and in cytologically negative peritoneal fluid. Analysis of tumor-specific hypermethylation in serum DNA may enhance early detection of ovarian cancer.     

Short communication: liver toxicity of lopinavir-containing regimens in HIV-infected patients with or without hepatitis C coinfection

Liver toxicity is a common side effect of antiretroviral therapy, particularly in subjects coinfected with the hepatitis C virus (HCV). The incidence of severe liver toxicity after initiation of treatment with lopinavir (LPV) as well as its possible association with LPV plasma levels were assessed in 120 HIV-infected patients (52% coinfected by HCV). The incidence of severe liver toxicity at 3 months was 1.7% and the cumulative incidence at 12 months was 4%. The development of severe liver toxicity was associated with HCV coinfection but not with LPV plasma levels.     

Risperidone in the treatment of patients with delirium

BACKGROUND: The aim of this study was to evaluate the efficacy and safety of risperidone in the treatment of patients with delirium. METHOD: We conducted a prospective, multicenter, observational 7-day study in 5 university general hospitals. Sixty-four patients (62.5% male [N = 40]; mean age: 67.3 +/- 11.4 years) hospitalized due to a medical condition who met criteria for delirium according to DSM-IV were enrolled in the study. Fifty-six patients received 7 days of treatment or less, while 8 patients continued treatment for more than 7 days. Effectiveness was assessed using the Trzepacz Delirium Rating Scale (DRS), the positive subscale of the PANSS (PANSS-P), the Mini-Mental State Examination (MMSE), and the Clinical Global Impressions scale (CGI). Safety assessment included the UKU Side Effect Rating Scale. Risperidone was administered at the time of diagnosis, and treatment was maintained according to clinical response. Response to treatment was defined as a reduction in DRS score to below 13 within the first 72 hours. Data were gathered from April to December 2000. RESULTS: Risperidone (mean dose = 2.6 +/- 1.7 mg/day at day 3) was effective in 90.6% (58/64) of the patients and significantly improved all symptoms measured by the scales from baseline to day 7 (mean scores: DRS, 22.5 +/- 4.6 at baseline to 6.8 +/- 7.0 at day 7; PANSS-P, 21.5 +/- 8.8 to 10.1 +/- 7.3; MMSE, 13.1 +/- 10.9 to 26.4 +/- 8.9; and CGI, 4.5 +/- 0.9 to 1.9 +/- 1.2) (Friedman test, p <.001 in all cases). Two patients (3.1%) experienced adverse events, but none showed extrapyramidal symptoms. CONCLUSIONS: Low-dose risperidone proved to be a safe and effective drug in the treatment of symptoms of delirium in medically hospitalized patients. These data provide the rationale for a prospective randomized controlled trial.