The rate-limiting step for glucose transport into the hypothalamus is across the blood-hypothalamus interface.

Specialized glucosensing neurons are present in the hypothalamus, some of which neighbor the median eminence, where the blood-brain barrier has been reported leaky. A leaky blood-brain barrier implies high tissue glucose levels and obviates a role for endothelial glucose transporters in the control of hypothalamic glucose concentration, important in understanding the mechanisms of glucose sensing We therefore addressed the question of blood-brain barrier integrity at the hypothalamus for glucose transport by examining the brain tissue-to-plasma glucose ratio in the hypothalamus relative to other brain regions. We also examined glycogenolysis in hypothalamus because its occurrence is unlikely in the potential absence of a hypothalamus-blood interface. Across all regions the concentration of glucose was comparable at a given plasma glucose concentration and was a near linear function of plasma glucose. At steady-state, hypothalamic glucose concentration was similar to the extracellular hypothalamic glucose concentration reported by others. Hypothalamic glycogen fell at a rate of approximately 1.5 micromol/g/h and remained present in substantial amounts. We conclude for the hypothalamus, a putative primary site of brain glucose sensing that: the rate-limiting step for glucose transport into brain cells is at the blood-hypothalamus interface, and that glycogenolysis is consistent with a substantial blood -to- intracellular glucose concentration gradient.

Comparison of human chromosome 21 conserved nongenic sequences (CNGs) with the mouse and dog genomes shows that their selective constraint is independent of their genic environment.

The analysis of conservation between the human and mouse genomes resulted in the identification of a large number of conserved nongenic sequences (CNGs). The functional significance of this nongenic conservation remains unknown, however. The availability of the sequence of a third mammalian genome, the dog, allows for a large-scale analysis of evolutionary attributes of CNGs in mammals. We have aligned 1638 previously identified CNGs and 976 conserved exons (CODs) from human chromosome 21 (Hsa21) with their orthologous sequences in mouse and dog. Attributes of selective constraint, such as sequence conservation, clustering, and direction of substitutions were compared between CNGs and CODs, showing a clear distinction between the two classes. We subsequently performed a chromosome-wide analysis of CNGs by correlating selective constraint metrics with their position on the chromosome and relative to their distance from genes. We found that CNGs appear to be randomly arranged in intergenic regions, with no bias to be closer or farther from genes. Moreover, conservation and clustering of substitutions of CNGs appear to be completely independent of their distance from genes. These results suggest that the majority of CNGs are not typical of previously described regulatory elements in terms of their location. We propose models for a global role of CNGs in genome function and regulation, through long-distance cis or trans chromosomal interactions.

The social value of health programs: Is age a relevant factor?

In cost-effectiveness analysis (CEA) it is usually assumed that a QALY is of equal value to everybody, irrespective of the patient's age. However, it is possible that society assigns different social values to a QALY according to who gets it. In this paper we discuss the possibility of weighting health benefits for age in CEA. We also examinethe possibility that age-related preferences depend on the size of the health gain. An experiment was performedto test these hypotheses. The results assessing suggest that the patient's age is a relevant factor when assessing health gains.

Phenotype and function of protective T cell immune responses in HIV.

PURPOSE OF REVIEW: Definition of T cell immune correlates in HIV infection remains a lofty goal towards our understanding of the HIV-specific immune response. This review will focus upon recent developments and controversies in our understanding of protective T cell responses against HIV. RECENT FINDINGS: It has become clear that multiple functions and phenotypic markers of T cells must be assessed to accurately characterize the complexity of CD4 and CD8 T cell responses. While evidence indicates that a hallmark of protective immune responses in HIV infection is the presence of 'polyfunctional' T cell responses, a disconnect remains between the function and phenotype of effective HIV-specific T cells. Moreover, there may be inherent differences in the ability of specific human leukocyte antigen class I families to promote CD8 T cell effector versus polyfunctional responses. It remains to be determined how polyfunctional responses arise in HIV infection, which functions are important for control, and whether surface phenotype markers provide an indication of protective capacity. SUMMARY: Polyfunctional and phenotypic assessment of T cell responses have clearly advanced our understanding of HIV specific immune responses. Critical questions remain, however, especially whether polyfunctional T cell responses control, or are controlled by, HIV replication.

The CAP1/Prss8 catalytic triad is not involved in PAR2 activation and protease nexin-1 (PN-1) inhibition.

Serine proteases, serine protease inhibitors, and protease-activated receptors (PARs) are responsible for several human skin disorders characterized by impaired epidermal permeability barrier function, desquamation, and inflammation. In this study, we addressed the consequences of a catalytically dead serine protease on epidermal homeostasis, the activation of PAR2 and the inhibition by the serine protease inhibitor nexin-1. The catalytically inactive serine protease CAP1/Prss8, when ectopically expressed in the mouse, retained the ability to induce skin disorders as well as its catalytically active counterpart (75%, n=81). Moreover, this phenotype was completely normalized in a PAR2-null background, indicating that the effects mediated by the catalytically inactive CAP1/Prss8 depend on PAR2 (95%, n=131). Finally, nexin-1 displayed analogous inhibitory capacity on both wild-type and inactive mutant CAP1/Prss8 in vitro and in vivo (64% n=151 vs. 89% n=109, respectively), indicating that the catalytic site of CAP1/Prss8 is dispensable for nexin-1 inhibition. Our results demonstrate a novel inhibitory interaction between CAP1/Prss8 and nexin-1, opening the search for specific CAP1/Prss8 antagonists that are independent of its catalytic activity.-Crisante, G., Battista, L., Iwaszkiewicz, J., Nesca, V., Mérillat, A.-M., Sergi, C., Zoete, V., Frateschi, S., Hummler, E. The CAP1/Prss8 catalytic triad is not involved in PAR2 activation and protease nexin-1 (PN-1) inhibition.

Is carbohydrate-deficient transferrin a specific marker for alcohol abuse? A study in patients with chronic viral hepatitis.

Carbohydrate-deficient transferrin, a transferrin isoform, is hailed as a new marker of chronic alcohol abuse, but its specificity is, however, not unequivocally accepted. The aim of the present study was therefore to determine carbohydrate-deficient transferrin levels in patients with chronic hepatitis B and C with or without documented chronic alcohol intake. Carbohydrate-deficient transferrin was measured using a double-antibody radioimmunoassay (CDTect, Pharmacia) in serum samples from 66 patients (45 males and 21 females; mean age: 39 years) with chronic viral hepatitis B (n = 20) or C (n = 46). Diagnosis of the underlying liver disease was established by liver biopsy. Carbohydrate-deficient transferrin levels were raised in 15 patients [23%; hepatitis B (n = 2) and hepatitis C (n = 13)]. In patients with chronic hepatitis B, the carbohydrate-deficient transferrin level was raised in two abstainers. In the 46 patients with chronic hepatitis C, 10 (22%) patients with an alcohol consumption of < 60 g/day for the men and 30 g/day for the women had raised carbohydrate-deficient transferrin levels. The overall specificity of carbohydrate-deficient transferrin for chronic alcohol abuse was thus 78%, suggesting an association between elevated carbohydrate-deficient transferrin levels and the presence of chronic viral hepatitis. Carbohydrate-deficient transferrin levels were not correlated with the histological grading or staging of chronic hepatitis B and C, or with biological markers of hepatic synthesis and cellular damage. Thus, an increased carbohydrate-deficient transferrin level may occur in patients with chronic viral hepatitis in the absence of chronic alcohol abuse. This fact should be kept in mind by physicians when using this marker to detect alcohol abuse.

Hypomyelination Caused by Scap Deletion is Slowly Rescued by Extracellular Lipids that Alter Myelin Structure

Myelination requires a massive increase in glial cell membrane synthesis. Here we demonstrate that the acute phase of myelin lipid synthesis is regulated by SREBP cleavage activation protein (SCAP), an activator of sterol regulatory element-binding proteins (SREBPs). Deletion of SCAP in Schwann cells led to a loss of SREBP-mediated gene expression, congenital hypomyelination and abnormal gait. Interestingly, aging SCAP mutant mice showed partial regain of function; they exhibited improved gait and produced small amounts of myelin indicating a slow SCAP-independent uptake of external lipids. Accordingly, extracellular lipoproteins promoted myelination by SCAP mutant Schwann cells. However, SCAP mutant myelin never reached normal thickness and had biophysical abnormalities concordant with abnormal lipid composition. These data demonstrate that SCAP mediated regulation of glial lipogenesis is key to the proper synthesis of myelin membrane. The described defects in SCAP mutant myelination provide new insights into the pathogenesis, and open new avenues for treatment strategies, of peripheral neuropathies associated with lipid metabolic disorders.

Connexin26 is regulated in rat urothelium by the scaffold protein IB1/JIP-1.

Proper function of the wall of bladder requires gap junctional communication for coordinating the responses of smooth muscle (SMC) and urothelial cells exposed to urine pressure. In the rat bladder, Cx43 is expressed by SMC and urothelial cells, whereas Cx26 expression is restricted to the epithelium. We used a model of bladder outlet obstruction, in which a ligature is placed around the urethra to increase voiding pressure. Increased fluid pressure was associated with increased Cx43 and Cx26 mRNA expression and with the activation of a signaling cascade including the transcription factor c-Jun, which is a component of the AP-1 complex. The signaling pathway of the c-Jun NH2 terminal kinase (JNK) requires the presence of the scaffold protein Islet-Brain1/c-Jun amino-terminal kinase Interacting Protein-1 (IB1/JIP-1). Under stress conditions resulting from urine retention, we have found a reduced content of IB1/JIP-1 in urothelial cells, which in turn induced a drastic increase of JNK and AP-1 binding activities. The stress-induced activation of JNK was prevented by overexpressing IB1/JIP-1, using a viral gene transfer approach, a condition which also resulted in a decrease in Cx26 mRNA. The data show that: 1) mechanical stress of urothelial cells activates in vivo JNK, as a consequence of a regulated expression of IB1/JIP-1 and 2) that urothelial Cx26 may be directly regulated by the AP-1 complex.

Small airways function declines after allogeneic haematopoietic stem cell transplantation.

Bronchiolitis obliterans (BO) following allogeneic haematopoietic stem cell transplantation (HSCT) affects peripheral airways. Detection of BO is presently delayed by the low sensitivity of spirometry. We examined the relationship between peripheral airway function and time since HSCT, and compared it with spirometry and clinical indices in 33 clinically stable allogeneic HSCT recipients. The following measurements were performed: lung function, exhaled nitric oxide, forced oscillatory respiratory system resistance and reactance, acinar (S(acin)) and conductive airways ventilation heterogeneity and lung clearance index (LCI) measured by multiple breath nitrogen washout. 22 patients underwent repeat visits from which short-term changes were examined. Median time post HSCT was 12 months. Eight patients were clinically diagnosed as having BO. In multivariate analysis, time since HSCT was predicted by S(acin) and forced expiratory volume in 1 s % predicted. 20 patients had abnormal S(acin) with normal spirometry, whereas none had airflow obstruction with normal S(acin). S(acin) and LCI were the only measures to change significantly between two visits, with both worsening. Change in S(acin) was the only parameter to correlate with change in chronic graft-versus-host disease grade. In conclusion, peripheral airways ventilation heterogeneity worsens with time after HSCT. S(acin) may be more sensitive than spirometry in detecting BO at an early stage, which needs confirmation in a prospective study.

FAM161A, associated with retinitis pigmentosa, is a component of the cilia-basal body complex and interacts with proteins involved in ciliopathies.

Retinitis pigmentosa (RP) is a retinal degenerative disease characterized by the progressive loss of photoreceptors. We have previously demonstrated that RP can be caused by recessive mutations in the human FAM161A gene, encoding a protein with unknown function that contains a conserved region shared only with a distant paralog, FAM161B. In this study, we show that FAM161A localizes at the base of the photoreceptor connecting cilium in human, mouse and rat. Furthermore, it is also present at the ciliary basal body in ciliated mammalian cells, both in native conditions and upon the expression of recombinant tagged proteins. Yeast two-hybrid analysis of binary interactions between FAM161A and an array of ciliary and ciliopathy-associated proteins reveals direct interaction with lebercilin, CEP290, OFD1 and SDCCAG8, all involved in hereditary retinal degeneration. These interactions are mediated by the C-terminal moiety of FAM161A, as demonstrated by pull-down experiments in cultured cell lines and in bovine retinal extracts. As other ciliary proteins, FAM161A can also interact with the microtubules and organize itself into microtubule-dependent intracellular networks. Moreover, small interfering RNA-mediated depletion of FAM161A transcripts in cultured cells causes the reduction in assembled primary cilia. Taken together, these data indicate that FAM161A-associated RP can be considered as a novel retinal ciliopathy and that its molecular pathogenesis may be related to other ciliopathies.

The gene MAPK8IP1, encoding islet-brain-1, is a candidate for type 2 diabetes.

Type 2 diabetes is a polygenic and genetically heterogeneous disease . The age of onset of the disease is usually late and environmental factors may be required to induce the complete diabetic phenotype. Susceptibility genes for diabetes have not yet been identified. Islet-brain-1 (IB1, encoded by MAPK8IP1), a novel DNA-binding transactivator of the glucose transporter GLUT2 (encoded by SLC2A2), is the homologue of the c-Jun amino-terminal kinase-interacting protein-1 (JIP-1; refs 2-5). We evaluated the role of IBi in beta-cells by expression of a MAPK8IP1 antisense RNA in a stable insulinoma beta-cell line. A 38% decrease in IB1 protein content resulted in a 49% and a 41% reduction in SLC2A2 and INS (encoding insulin) mRNA expression, respectively. In addition, we detected MAPK8IP1 transcripts and IBi protein in human pancreatic islets. These data establish MAPK8IP1 as a candidate gene for human diabetes. Sibpair analyses performed on i49 multiplex French families with type 2 diabetes excluded MAPK8IP1 as a major diabetogenic locus. We did, however, identify in one family a missense mutation located in the coding region of MAPK8IP1 (559N) that segregated with diabetes. In vitro, this mutation was associated with an inability of IB1 to prevent apoptosis induced by MAPK/ERK kinase kinase 1 (MEKK1) and a reduced ability to counteract the inhibitory action of the activated c-JUN amino-terminal kinase (JNK) pathway on INS transcriptional activity. Identification of this novel non-maturity onset diabetes of the young (MODY) form of diabetes demonstrates that IB1 is a key regulator of 3-cell function.

Characterization of PHO1 and PHO1;H1 gene function in Arabidopsis thaliana

Summary Phosphorus is one of the major macronutrients required for plant growth and development. Plant roots acquire phosphorus as inorganic phosphate (Pi), which is further distributed to the shoot, via the transpiration stream and root pressure, where Pi is imported again into cells. PHO1 in Arabidopsis has been identified as a protein involved in the loading of Pi into the root xylem. PHO1 does not have any homology to described Pi transporters including the Pht1 family of H+/ Pi cotransporters. PHO1 bears two domains, SPX and EXS domains, previously identified in Saccharomyces cerevisiae proteins involved in Pi transport and/or sensing, or in sorting proteins to endomembranes. Phylogenetic analysis of the PHO1 gene family revealed the presence of three clusters, with PHO1 and PHO1;H1 forming one cluster. The biological significance behind this cluster was demonstrated by the complementation of the pho1 mutant with only PHO1 and PHO1;H1, of all the PHO1 family members, when expressed under the PHO1 promoter. PHO1 has been shown to be expressed mostly in the root vascular cylinder and at low level in the shoot. PHO1;H1 had a different expression pattern, being expressed in both root and shoot vascular cylinder to the same level, with the levels in leaves increasing with the leaf maturity, suggesting additional role of PHO1;H1 in the Pi mobilization in leaves. In order to further explore the role of PHO1, Pi dynamics was studied on plants expressing PHO1 at different levels compared to the wild type: PHO1 overexpressors, PHO1 underexpressors and the pho1 mutant. Overexpression of the PHO1 protein in the shoot vascular tissue was shown to lead to increased Pi efflux out of the leaf cells and Pi accumulation in the shoot xylem apoplast compared to wild type, confirming the hypothesized role of PHO1 in xylem loading with Pi. The overexpression of PHO1 in the shoot was responsible far both changed Pi dynamic and stunted growth of PHO1 overexpressors, as shown by grafting experiments between wild type and PHO1 overexpressor. We found a ca. 2 fold decrease of shoot phosphorus and a 5-10 fold decrease in vacuolar Pi content in the PHO1 underexpressors and the pho1 null mutant compared to wild type, consistent with the role of PHO1 in the transfer of Pi from the root to the shoot. Shoot Pi deficiency results in a poor growth of the pho1 mutant. Grafting experiments between pho1 and wild type confirmed that both Pi deficiency and stunt growth of the pho1 mutant were dependent on the pho1 root, further supporting the importance of PHO1 in the root xylem loading with Pi. The pho1 mutant and the PHO1 underexpressors accumulated 8-15 fold more Pi in the root relative to wild type. In contrast to the pho1 mutant, the growth of PHO1 underexpressors was not impaired by the low shoat Pi content. This finding suggests that either PHO1 protein or root Pi concentration is important in Pi signaling and development of Pi deficiency symptoms leading to reduced growth. Résumé Le phosphore est l'un des nutriments essentiels à la croissance et au développement des plantes. Les racines absorbent le phosphore sous forme de phosphate inorganique (Pi) qui est dirigé, par la transpiration et la pression de la racine, vers les feuilles où le phosphate est acquis par les cellules. La protéine PHO1 a été démontrée indispensable au chargement du Pi dans le xylème des racines d'Arabidopsis. PHO1 ne démontre pas d'homologie aux transporteurs de Pi connus, incluant la famille Pht1 de cotransporteurs H+/Pi qui ont comme fonction le transport du phosphate à l'intérieur de la cellule. PHO1 contient deux domaines, SPX et EXS, aussi présents dans des protéines de Saccharomyces cerevisiae impliquées dans le transport ou la perception du phosphate, ou dans la localisation des protéines vers différentes membranes. Le génome d'Arabidopsis contient onze gènes homologues à PHO1. Neuf de ces homologues sont répartis en trois groupes. PHO1 et PHO1;H1 forment un de ces groupes. Nos travaux ont démontré que seuls PHO1;H1 et PHO1, sous contrôle du promoteur PHO1, peuvent complémenter le mutant pho1. PHO1 est exprimé principalement dans le cylindre vasculaire de la racine et faiblement dans la partie aérienne. Le degré d'expression de PHO1;H1 est similaire dans le cylindre vasculaire de la racine et des feuilles. Ceci suggère que PHO1;H1 est aussi impliqué dans la mobilisation du Pi dans les feuilles, en plus de son rôle dans le transfert du Pi dans le xylème des racines. Afin de mieux explorer le rôle de PHO1, la dynamique du phosphate a été observée dans trois lignées de plantes transgéniques: un sur-expresseur de PHO1, un sous-expresseur de PHO1 et le mutant pho1. La sur-expression de PHO1 dans le tissue vasculaire des feuilles a provoqué l'efflux du Pi vers l'espace apoplastic du xylème, ce qui confirme le rôle de PHO1 dans le chargement du Pi dans le xylème. La sur-expressìon de PHO1 dans la rosette est responsable d'un changement de la dynamique du Pi et de la diminution de la croissance, ce qui fut démontré par une expérience de greffe de la rosette du sur-expresseur de PHO1 sur les racines du sauvage. On a observé pour le sous-expresseur de PHO1 et le mutant pho1 une diminution du phosphore d'environ 2 fais au niveau des feuilles, et une diminution de 5-10 fois du Pi dans les vacuoles des feuilles, par rapport au sauvage. Ceci confirme le rôle proposé de PHO1 dans le transfert du Pi des racines aux feuilles. La carence de Pi chez pho1 implique une diminution de la taille de la rosette. Pour expliquer ce phénotype une autre expérience de greffe démontra que la cause de ce changement provenait des racines. Ceci renforce l'hypothèse de l'importance du rôle de PHO1 dans le xylème de la racine pour le chargement du Pi. Le mutant phot et le sous-expresseur de PHO1 accumulent 8-15 fois plus de Pi dans leurs racines comparé au sauvage. Cependant, contrairement au phot mutant, le sous-expresseur de PHO1 avait une croissance comparable au sauvage malgré le niveau bas du Pi dans les feuilles. Ceci suggère que la taille de la rosette lors d'une carence en Pi chez Arabidopsis serait la conséquence d'un changement de concentration de Pi dans les racines ou d'une influence de la protéine PHO1.

Incremental neural networks for function approximation

A new strategy for incremental building of multilayer feedforward neural networks is proposed in the context of approximation of functions from R-p to R-q using noisy data. A stopping criterion based on the properties of the noise is also proposed. Experimental results for both artificial and real data are performed and two alternatives of the proposed construction strategy are compared.

Between Equity and Differentiation: An Analytical Schema of the Social Function of Education

The educational sphere has an internal function relatively agreed by social scientists. Nonetheless, the contribution that educational systems provide to the society (i.e., their social function) does not have the same degree of consensus. Taking into consideration such theoretical precedent, the current article raises an analytical schema to grasp the social function of education considering a sociological perspective. Starting from the assumption that there is an intrinsic relationship between the internal and social functions of social systems, we suggest there are particular stratification determinants modifying the internal pedagogical function of education, which impact on its social function by creating simultaneous conditions of equity and differentiation. Throughout the paper this social function is considered a paradoxical mechanism. We highlight how this paradoxical dynamic is deployed in different structural levels of the educational sphere. Additionally, we discuss eventual consequences of this paradoxical social function for the inclusion possibilities that educational systems offer to individuals.

Th2 lymphoproliferative disorder of LatY136F mutant mice unfolds independently of TCR-MHC engagement and is insensitive to the action of Foxp3+ regulatory T cells.

Mutant mice where tyrosine 136 of linker for activation of T cells (LAT) was replaced with a phenylalanine (Lat(Y136F) mice) develop a fast-onset lymphoproliferative disorder involving polyclonal CD4 T cells that produce massive amounts of Th2 cytokines and trigger severe inflammation and autoantibodies. We analyzed whether the Lat(Y136F) pathology constitutes a bona fide autoimmune disorder dependent on TCR specificity. Using adoptive transfer experiments, we demonstrated that the expansion and uncontrolled Th2-effector function of Lat(Y136F) CD4 cells are not triggered by an MHC class II-driven, autoreactive process. Using Foxp3EGFP reporter mice, we further showed that nonfunctional Foxp3(+) regulatory T cells are present in Lat(Y136F) mice and that pathogenic Lat(Y136F) CD4 T cells were capable of escaping the control of infused wild-type Foxp3(+) regulatory T cells. These results argue against a scenario where the Lat(Y136F) pathology is primarily due to a lack of functional Foxp3(+) regulatory T cells and suggest that a defect intrinsic to Lat(Y136F) CD4 T cells leads to a state of TCR-independent hyperactivity. This abnormal status confers Lat(Y136F) CD4 T cells with the ability to trigger the production of Abs and of autoantibodies in a TCR-independent, quasi-mitogenic fashion. Therefore, despite the presence of autoantibodies causative of severe systemic disease, the pathological conditions observed in Lat(Y136F) mice unfold in an Ag-independent manner and thus do not qualify as a genuine autoimmune disorder.