7031 Sw 72Nd Av
South Miami FL 33143
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Plasma glucocorticoids differentially modulate phasic and tonic GABA inhibition during early postnatal development in rat spinal lamina II. - Neuroscience letters
Nociceptive processing is tuned by GABAA receptor-mediated inhibition in the spinal cord dorsal horn that undergoes postnatal maturation in rodents. These GABAergic inhibitory postsynaptic currents (IPSCs) are modulated by 3Î±5Î±-reduced steroids during early postnatal development in spinal cord lamina II. Thus an enhanced phasic inhibition is present in neonates and decreases over time. GABA can also activate extrasynaptic receptors, giving rise to tonic inhibition. In this study, we characterized the contribution of plasma corticosterone (CORT) to postnatal maturation of spinal phasic and, for the first time, tonic GABAergic inhibitions. We used Fisher and Lewis rat strains displaying respectively high and low hypothalamic-pituitary-adrenal axis reactivity, compared to control Sprague-Dawley rats. Measured plasma CORT levels were significantly higher in Fisher rats, which also displayed significantly higher mechanical nociceptive thresholds, supporting the hypothesis of an antinociceptive action of CORT. Recorded GABAA IPSCs shortened during maturation in all strains while remaining larger in Fisher rats. Blocking the 5Î±-reduction of steroids in Fisher rats produced a further decrease of IPSC deactivation time constant. In contrast, GABAA tonic inhibition progressively increased during maturation, without any difference among strains. In conclusion, we show that both phasic and tonic GABAergic inhibitions undergo postnatal maturation in lamina II. Moreover spinal production of 3Î±5Î±-reduced steroids that presumably derive from plasma CORT is correlated to spinal GABAA phasic (but not tonic) inhibition and to mechanical nociceptive thresholds.Copyright Â© 2014 Elsevier Ireland Ltd. All rights reserved.
Prevention of SIV rectal transmission and priming of T cell responses in macaques after local pre-exposure application of tenofovir gel. - PLoS medicine
The rectum is particularly vulnerable to HIV transmission having only a single protective layer of columnar epithelium overlying tissue rich in activated lymphoid cells; thus, unprotected anal intercourse in both women and men carries a higher risk of infection than other sexual routes. In the absence of effective prophylactic vaccines, increasing attention is being given to the use of microbicides and preventative antiretroviral (ARV) drugs. To prevent mucosal transmission of HIV, a microbicide/ARV should ideally act locally at and near the virus portal of entry. As part of an integrated rectal microbicide development programme, we have evaluated rectal application of the nucleotide reverse transcriptase (RT) inhibitor tenofovir (PMPA, 9-[(R)-2-(phosphonomethoxy) propyl] adenine monohydrate), a drug licensed for therapeutic use, for protective efficacy against rectal challenge with simian immunodeficiency virus (SIV) in a well-established and standardised macaque model.A total of 20 purpose-bred Indian rhesus macaques were used to evaluate the protective efficacy of topical tenofovir. Nine animals received 1% tenofovir gel per rectum up to 2 h prior to virus challenge, four macaques received placebo gel, and four macaques remained untreated. In addition, three macaques were given tenofovir gel 2 h after virus challenge. Following intrarectal instillation of 20 median rectal infectious doses (MID50) of a noncloned, virulent stock of SIVmac251/32H, all animals were analysed for virus infection, by virus isolation from peripheral blood mononuclear cells (PBMC), quantitative proviral DNA load in PBMC, plasma viral RNA (vRNA) load by sensitive quantitative competitive (qc) RT-PCR, and presence of SIV-specific serum antibodies by ELISA. We report here a significant protective effect (p = 0.003; Fisher exact probability test) wherein eight of nine macaques given tenofovir per rectum up to 2 h prior to virus challenge were protected from infection (n = 6) or had modified virus outcomes (n = 2), while all untreated macaques and three of four macaques given placebo gel were infected, as were two of three animals receiving tenofovir gel after challenge. Moreover, analysis of lymphoid tissues post mortem failed to reveal sequestration of SIV in the protected animals. We found a strong positive association between the concentration of tenofovir in the plasma 15 min after rectal application of gel and the degree of protection in the six animals challenged with virus at this time point. Moreover, colorectal explants from non-SIV challenged tenofovir-treated macaques were resistant to infection ex vivo, whereas no inhibition was seen in explants from the small intestine. Tissue-specific inhibition of infection was associated with the intracellular detection of tenofovir. Intriguingly, in the absence of seroconversion, Gag-specific gamma interferon (IFN-gamma)-secreting T cells were detected in the blood of four of seven protected animals tested, with frequencies ranging from 144 spot forming cells (SFC)/10(6) PBMC to 261 spot forming cells (SFC)/10(6) PBMC.These results indicate that colorectal pretreatment with ARV drugs, such as tenofovir, has potential as a clinically relevant strategy for the prevention of HIV transmission. We conclude that plasma tenofovir concentration measured 15 min after rectal administration may serve as a surrogate indicator of protective efficacy. This may prove to be useful in the design of clinical studies. Furthermore, in vitro intestinal explants served as a model for drug distribution in vivo and susceptibility to virus infection. The finding of T cell priming following exposure to virus in the absence of overt infection is provocative. Further studies would reveal if a combined modality microbicide and vaccination strategy is feasible by determining the full extent of local immune responses induced and their protective potential.
Epidemiological and clinical features, response to HAART, and survival in HIV-infected patients diagnosed at the age of 50 or more. - BMC infectious diseases
Over the last years, the mean age of subjects with HIV infection and AIDS is increasing. Moreover, some epidemiological and clinical differences between younger and older HIV-infected individuals have been observed. However, since introduction of HAART therapy, there are controversial results regarding their response to HAART. The aim of the present study is to evaluate epidemiological and clinical features, response to HAART, and survival in elderly HIV-infected patients with regard to younger HIV-infected patients.A prospective cohort study (1998-2003) was performed on patients from Sabadell Hospital, in Northeast of Spain. The cohort includes newly attended HIV-infected patients since January 1, 1998. For the purpose of this analysis, data was censured at December 31, 2003. Taking into account age at time of diagnosis, it was considered 36 HIV-positive people aged 50 years or more (Group 1, G1) and 419 HIV-positive people aged 13-40 years (Group 2, G2). Epidemiological, clinical, biological and therapy data are recorded. Statistical analysis was performed using Chi-squared test and Fisher exact test, Mann-Whitney U test, Kaplan-Meier, Log Rank test, and Two-Way ANOVA from random factors.G1 showed higher proportion of men than G2. The most common risk factors in G1 were heterosexual transmission (P = 0.01) and having sex with men or women (P < 0.001). G1 and G2 show parallel profiles through the time regarding immunological response (P = 0.989) and virological response (P = 0.074). However, older people showed lower CD4 cell counts at first clinic visit (P < 0.001) and, eventually, they did not achieve the same counts as G2. G1 presented faster progression to AIDS (P < 0.001) and shorter survival (P < 0.001).Older patients have different epidemiological features. Their immunological and virological responses are good. However, older patients do not achieve the same CD4 cell counts likely due to they have lower counts at first clinic visit. Thus, it is essential physicians know older HIV-infected patients features to consider the possibility of HIV infection in these patients with the aim of treatment would not be delayed.
Neuroimmunomodulation in inflammatory bowel disease. How far from "bench" to "bedside"? - Annals of the New York Academy of Sciences
The chronic inflammatory bowel diseases (BID), Crohn's disease and ulcerative colitis, are characterized by recurrent periods of inflammation and tissue destruction. The clinical course is influenced by genetics, environmental factors, and the immune system. Recent insights (bench trials) benefiting from advances in genetic engineering and molecular biology have contributed to clinical care (bedside) in terms of actual or potential therapies. Does the neuroendocrine system significantly modify disease activity? Although conceptually appealing, evidence remains circumstantial. Compelling anecdotal reports exist that "stress" affects disease activity in terms of the frequency and severity of IBD flares (bedside), but the mechanisms underlying these observations are unknown. Evidence that neuroendocrine factors play a significant role in immunomodulation is progressing (bench). (i) Trinitrobenzene sulfonic acid (TNB)-induced colitis, although similar in unstressed Fisher and Lewis rats, shows marked worsening in stressed Lewis rats. (ii) Early studies of rectal pain perception suggest there are specific differences in neuroimaging studies (PET scans) in IBD patients compared to controls. (iii) Levels of substance P (SP) and its receptor are altered. (iv) Preliminary clinical studies with SP receptor antagonists show a trend toward improvement. (v) Importantly, the placebo response in clinical trials is as high as 45%. Evidence that neuroendocrine systems significantly modulate local inflammation is rapidly accumulating (bench), which will facilitate enhanced coordination of clinically relevant therapies (bedside).
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7031 Sw 72Nd Av South Miami, FL 33143
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