Localisation of drug permeability along the rat small intestine, using markers of the paracellular, transcellular and some transporter routes

The small intestine is the major site of drug absorption. Some reports in the literature have evoked the concept of “absorption windows” in the small intestine: are there specific regions where drug absorption is significantly higher than others? To investigate this question, we used an everted gut sac method to study the permeability of drugs and markers every 3–4 cm down the entire small intestine in rat. These markers were chosen to be representative of the mechanisms by which drugs cross the small intestinal mucosa: paracellular and transcellular passive diffusion, via influx transporters, and a drug (digoxin) that is effluxed from cells by P-glycoprotein (P-gp). The passive diffusion and influx transporter markers gave similar profiles with a plateau of permeability along the jejunum, and with the exception of L-Dopa, lower permeability in the ileum. Digoxin showed a linear decrease in the profile from the proximal jejunum to the ileum. Permeability in the duodenum was two to three times lower than the jejunum for all compounds. There were no narrow specific regions of high permeability and so the concept of discrete “absorption windows” along the small intestine as suggested from some pharmacokinetic studies may be related to other effects such as pH and/or solubility.     

Characterization of T cell receptors reactive to HCRTNH2, pHA273-287, and NP17-31 in control and narcolepsy patients

Narcolepsy type 1 (NT1), a disorder caused by hypocretin/orexin (HCRT) cell loss, is associated with human leukocyte antigen (HLA)-DQ0602 (98%) and T cell receptor (TCR) polymorphisms. Increased CD4⁺ T cell reactivity to HCRT, especially DQ0602-presented amidated C-terminal HCRT (HCRT_NH2), has been reported, and homology with pHA_273–287 flu antigens from pandemic 2009 H1N1, an established trigger of the disease, suggests molecular mimicry. In this work, we extended DQ0602 tetramer and dextramer data to 77 cases and 44 controls, replicating our prior finding and testing 709 TCRs in Jurkat 76 T cells for functional activation. We found that fewer TCRs isolated with HCRT_NH2 (∼11%) versus pHA_273–287 or NP_17–31 antigens (∼50%) were activated by their ligand. Single-cell characterization did not reveal phenotype differences in influenza versus HCRT_NH2-reactive T cells, and analysis of TCR CDR3αβ sequences showed TCR clustering by responses to antigens but no cross-peptide class reactivity. Our results do not support the existence of molecular mimicry between HCRT and pHA_273–287 or NP_17–31.

Narcolepsy type 1 (NT1) is caused by a loss of hypocretin/orexin (HCRT) neurons in the mediolateral hypothalamus (1–3), with recent data suggesting reversion of the human and animal phenotype with orexin agonists. The disease is strongly associated with human leukocyte antigen (HLA) DQB1*06:02/DQA1*01:02 (98% vs. 25%) (DQ0602) and displays weaker genetic associations with other immune loci, thus suggesting autoimmunity (4–9), although not meeting all criteria for being classified as an autoimmune disease (10). Like other autoimmune diseases, NT1 presents with increased comorbidity with other autoimmune conditions and asthma (11–13).Onset of NT1 is often abrupt and seasonal, and association with both Streptococcus pyogenes (14, 15) and influenza A infections (16) suggests that it may be triggered by winter infections. Most strikingly, prevalence of NT1 increased several folds in mainland China and Taiwan following the 2009 to 2010 “swine flu” H1N1 influenza pandemic (pH1N1) (4, 17, 18), although association with the pandemic is less clear in other countries (19). Vaccination with the pH1N1 vaccine Pandemrix has also been associated with an elevated relative risk for developing narcolepsy of 5- to 14-fold in children and adolescents and 2- to 7-fold in adults (18, 20–22). As Pandemrix is an AS03-adjuvanted vaccine containing the artificially produced reassortant strain X-179A, a mix of A/Puerto Rico/8/1934 (PR8), an old H1N1 strain derived from pre-2009 seasonal H1N1, and the key H1N1 2009 surface proteins hemagglutinin (HA) and neuraminidase (NA) (23), flu proteins are likely critically involved in triggering NT1. Evidence showing that HLA and T cell receptor (TCR) genetic associations are universal (9, 24–27) is also consistent with a flu trigger, as influenza A infections occur on a global basis (28). Importantly, however, even with Pandemrix vaccination in Europe, only ∼1 in 16,000 vaccinated children developed NT1, thus demanding the consideration of additional factors to fully explain the initiation of NT1 (29).Unlike in other autoimmune diseases, autoantibodies against HCRT cell proteins, HCRT itself (30–32), or other targets such as TRIB2 (33, 34) or HCRT receptor 2 (35–38) have not been consistently found. This has led to the suggestion that HCRT cell loss may be primarily T cell mediated, with limited or no involvement of autoantibodies. Consistent with this hypothesis, mounting evidence suggests involvement of CD4⁺ T cell reactivity to HCRT in NT1 (39–41), notably toward amidated fragments of the secreted, mature peptide (HCRT_54–66-NH2 and HCRT_86–97-NH2, homologous peptides collectively denoted as HCRT_NH2) (42), as critical factors in the development of the disease. Furthermore, CD8⁺ mediation of HCRT cell death has also been shown to cause NT1 in an animal model (43) and Pedersen and colleagues (44) recently highlighted the presence of CD8⁺ T cell responses against intracellular proteins contained in HCRT neurons in narcolepsy patients. Of additional interest is the observation that the TCR polymorphisms associated with NT1 are quantitative trait loci for TRAJ24 (decreasing), TRAJ28, and TRBV4-2 (increasing) usage in peripheral T cells in both controls and patients (29). A significant L to F coding polymorphism located within the antigen-binding complementarity-determining region (CDR) 3 loop of TRAJ24 expressing TCRs is also associated with NT1. Altogether, this suggests that T cell responses involving TRAJ24- or TRAJ28- and TRBV4-2–bearing TCRs may be bottleneck responses in a causative autoimmune T cell response, leading to HCRT cell death (4, 14, 17–19, 45).Based on the evidence provided above, our group hypothesized that a CD4⁺ T cell–mediated response directed against specific flu epitopes could lead to molecular mimicry with HCRT itself, potentially HCRT_NH2, subsequently recruiting CD8⁺ cytotoxic T cells and leading to HCRT cell death. To test this hypothesis, we screened 135 DQ0602 tetramers binding peptides originating from Pandemrix, wild-type 2009 H1N1, and two autoantigens (HCRT and RFX4) for the presence of antigen-restricted CD4⁺ T cells (42). After this systematic survey, it was established that CD4⁺ T cell populations recognizing influenza pHA_273–287 (pH1N1 specific) and PR8 (H1N1 pre-2009 and H2N2)-restricted NP_17–31 epitopes were increased in NT1 versus DQ0602 controls. Supporting this finding, this difference was also present in post-Pandemrix cases versus controls and was stronger in recent onset cases (42). Additionally, studies of single cells recognizing these peptides revealed that TCR clones carrying TRBV4-2 and TRAJ24 were retrieved from both HCRT_NH2 and pHA_273–287 tetramers (42), suggesting involvement of these clones in molecular mimicry and disease pathophysiology. Similarly, Jiang et al. (39) isolated TRAJ24-positive cells recognizing DQ0602 bound to HCRT_87–100 tetramer, many of which expressed perforin and granzyme-B, suggesting a terminally differentiated effector T cell (T_EMRA) phenotype. In one case, a TRAJ24 clone isolated from a narcoleptic patient showed elevated TCR reactivity toward HCRT_87–97-NH2 when transfected in Jurkat 76 (J76) cells, thus implying a role for TRAJ24 reactivity toward DQ0602-HCRT in narcolepsy autoimmunity (39).Here, we extend prior work from our group by doubling the number of patients and controls and increasing the representation of TRAJ24F narcolepsy susceptibility–associated alleles in these subjects. Results validated an increased frequency of pHA_273–287 and HCRT_54–66-NH2 tetramer-positive CD4⁺ T cells in NT1, while also testing isolated T cell clones for potential activation by their cognate ligands when expressed in J76 cells. Importantly, we also analyzed TCR CDR3αβ sequences in this larger dataset and conducted expression profiling of the corresponding T cells, providing insights into T cell characteristics in narcolepsy.     

海南省HIV-1基因亚型分析

目的 分析海南省人类免疫缺陷病毒-1(HIV-1)基因亚型,监测HIV毒株的流行状况.方法 从88份HIV-1抗体阳性的血浆中提取RNA,逆转录后采用PCR法扩增HIV-1基因序列中的env及pol基因,对扩增产物进行核苷酸序列测定,经比对分析而确定基因亚型.构建最大似然(ML)进化树,分析感染者间的传播链.结果 88份样品中,有83份样品被扩增出HIV-1的env及pol基因片段;共发现6种HIV-1亚型和重组型,其中CRF01-AE亚型70份,B'亚型8份,C亚型2份,B亚型和CRF08-BC、CRF01-AE/B'重组亚型各1份.在ML进化树上83份样品分成4个传播群(66/83)和非传播群(17/83),其中传播群1最庞大(59/83).结论 海南省HIV/AIDS的HIV-1基因亚型至少有6种,其中CRF01-AE为主要亚型,占84.33%(70/83),主要分布在静脉吸毒者及其性伴侣之间,形成了一个庞大的传播群.其次为B'亚型(9.6%).另外的4种亚型(6%)仅见单个病例.提示海南省静脉吸毒为主要的感染途径(67.5%);经性接触传播的亚型种类复杂多样,包括本次检出的全部亚型和重组株.     

Modeling Relationships Involving Perceived Recovery Orientation of Mental Health Teams Among Quebec Mental Health Professionals

The Journal of Behavioral Health Services & Research - While mental health (MH) services are expected to support client recovery, very little is known about services provided by MH teams in...     

Malaria PCR Detection in Cambodian Low-Transmission Settings: Dried Blood Spots versus Venous Blood Samples

In the context of malaria elimination, novel strategies for detecting very low malaria parasite densities in asymptomatic individuals are needed. One of the major limitations of the malaria parasite detection methods is the volume of blood samples being analyzed. The objective of the study was to compare the diagnostic accuracy of a malaria polymerase chain reaction assay, from dried blood spots (DBS, 5 μL) and different volumes of venous blood (50 μL, 200 μL, and 1 mL). The limit of detection of the polymerase chain reaction assay, using calibrated Plasmodium falciparum blood dilutions, showed that venous blood samples (50 μL, 200 μL, 1 mL) combined with Qiagen extraction methods gave a similar threshold of 100 parasites/mL, ∼100-fold lower than 5 μL DBS/Instagene method. On a set of 521 field samples, collected in two different transmission areas in northern Cambodia, no significant difference in the proportion of parasite carriers, regardless of the methods used was found. The 5 μL DBS method missed 27% of the samples detected by the 1 mL venous blood method, but most of the missed parasites carriers were infected by Plasmodium vivax (84%). The remaining missed P. falciparum parasite carriers (N = 3) were only detected in high-transmission areas.