47 research outputs found
A cardiac arrhythmia syndrome caused by loss of ankyrin-B function
No full text220-kDa ankyrin-B is required for coordinated assembly of Na/Ca exchanger, Na/K ATPase, and inositol trisphosphate (InsP(3)) receptor at transverse-tubule/sarcoplasmic reticulum sites in cardiomyocytes. A loss-of-function mutation of ankyrin-B identified in an extended kindred causes a dominantly inherited cardiac arrhythmia, initially described as type 4 long QT syndrome. Here we report the identification of eight unrelated probands harboring ankyrin-B loss-of-function mutations, including four previously undescribed mutations, whose clinical features distinguish the cardiac phenotype associated with loss of ankyrin-B activity from classic long QT syndromes. Humans with ankyrin-B mutations display varying degrees of cardiac dysfunction including bradycardia, sinus arrhythmia, idiopathic ventricular fibrillation, catecholaminergic polymorphic ventricular tachycardia, and risk of sudden death. However, a prolonged rate-corrected QT interval was not a consistent feature, indicating that ankyrin-B dysfunction represents a clinical entity distinct from classic long QT syndromes. The mutations are localized in the ankyrin-B regulatory domain, which distinguishes function of ankyrin-B from ankyrin-G in cardiomyocytes. All mutations abolish ability of ankyrin-B to restore abnormal Ca(2+) dynamics and abnormal localization and expression of Na/Ca exchanger, Na/K ATPase, and InsP(3)R in ankyrin-B(+/-) cardiomyocytes. This study, considered together with the first description of ankyrin-B mutation associated with cardiac dysfunction, supports a previously undescribed paradigm for human disease due to abnormal coordination of multiple functionally related ion channels and transporters, in this case the Na/K ATPase, Na/Ca exchanger, and InsP(3) receptor
Integration of genetics into a systems model of electrocardiographic traits using humanCVD BeadChip
No full text<p>Background—Electrocardiographic traits are important, substantially heritable determinants of risk of arrhythmias and sudden cardiac death.</p>
<p>Methods and Results—In this study, 3 population-based cohorts (n=10 526) genotyped with the Illumina HumanCVD Beadchip and 4 quantitative electrocardiographic traits (PR interval, QRS axis, QRS duration, and QTc interval) were evaluated for single-nucleotide polymorphism associations. Six gene regions contained single nucleotide polymorphisms associated with these traits at P<10−6, including SCN5A (PR interval and QRS duration), CAV1-CAV2 locus (PR interval), CDKN1A (QRS duration), NOS1AP, KCNH2, and KCNQ1 (QTc interval). Expression quantitative trait loci analyses of top associated single-nucleotide polymorphisms were undertaken in human heart and aortic tissues. NOS1AP, SCN5A, IGFBP3, CYP2C9, and CAV1 showed evidence of differential allelic expression. We modeled the effects of ion channel activity on electrocardiographic parameters, estimating the change in gene expression that would account for our observed associations, thus relating epidemiological observations and expression quantitative trait loci data to a systems model of the ECG.</p>
<p>Conclusions—These association results replicate and refine the mapping of previous genome-wide association study findings for electrocardiographic traits, while the expression analysis and modeling approaches offer supporting evidence for a functional role of some of these loci in cardiac excitation/conduction.</p>
Using Orthogonal Functions with a Finite Element Method for Approximating Even-Parity Neutron Flux in Slab Geometry
No full textPadronização de ensaio in vitro para triagem de compostos com potencial atividade imunomodulatória sobre linfócitos B
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Programa de Pós-Graduação em Biotecnologia, Florianópolis, 2011O presente trabalho propôs desenvolver uma metodologia in vitro simples, sensível e reprodutível para a prospecção de compostos obtidos de produtos naturais ou seus derivados sintéticos com potencial atividade imunomodulatória sobre linfócitos B, principal célula efetora da resposta imune humoral, como alternativa ao uso de sistemas experimentais in vivo. O planejamento do estudo fundamentou-se na utilização da linhagem linfoblastóide B humana SKW 6.4, imortalizada via EBV, como modelo preditivo in vitro; na padronização do método ELISA para a titulação de imunoglobulinas totais secretadas em cultura, empregada como parâmetro inicial de avaliação; e na definição de condições experimentais e padrões comparativos que propiciem a análise do modelo selecionado quanto à modulação de suas funções imunes. O protocolo de cultivo celular e demais variáveis foram determinados para placas de cultura de 96 micropoços. Células SKW 6.4 foram fortemente imunoestimuladas em tratamento com PMA ou LPS nas concentrações ótimas de 100ng·mL-1 ou 100µg·mL-1, respectivamente. Condições referenciais de imunossupressão foram estabelecidas após ensaio com 25µg·mL-1 de AZA, 50ng·mL-1 de MPA ou 10ng·mL-1 de RAPA. A secreção de IL-6 pelo modelo in vitro foi claramente modulada na presença de LPS e DEX, possibilitando sua dosagem como parâmetro avaliativo adicional de resposta imunológica. A análise de diferentes extratos polissacarídicos de Agaricus subrufescens conforme o ensaio padronizado revelou significativa atividade imunoestimulatória sobre células SKW 6.4 para frações com maior peso molecular médio (~630kDa), permitindo especular sobre possíveis rotas de ativação e sugerir um método ótimo de purificação para futura aplicação biotecnológica. Os resultados globais alcançados neste estudo demonstraram a sensibilidade e eficácia do ensaio in vitro desenvolvido, viabilizando sua utilização na pesquisa e triagem de compostos com potencial atividade imunomodulatória sobre linfócitos B como possível método substitutivo ao uso de animais de experimentação
IL-10 in Human Newborns : Ontogeny of IL-10 secretion and relation to the secretion of IFN-g, immunoglobulin M, G, and A, and mononuclear cell composition in newborns
No full textThe purpose of this work was to elucidate the ontogeny of interleukin-10 (IL-10) secretion from newborn mononuclear cells (MCs), and to examine its relation to the secretion of interferon-g (IFN-g) and immunoglobulins (Igs). The initial hypothesis was that the decreased immunoglobulin (Ig) synthesis of newborn babies was the result of immature cytokine synthesis regulation, which would lead to excessive IL-10 production, leading in turn to suppressed IFN-g secretion.
Altogether 57 full-term newborns and 34 adult volunteers were enrolled. Additionally, surface marker compositions of 29 premature babies were included. Enzyme-linked immunoassays were used to determine the amount of secreted IL-10, IFN-g, and Igs, and the surface marker composition of MC were analyzed with a FACScan flow cytometer.
The three most important findings were:
1. Cord blood MC, including CD5+ B cells, are able to secrete IL-10. However, when compared with adults, the secretion of IL-10 was decreased. This indicates that reasons other than excessive IL-10 secretion are responsible of reduced IFN-g secretion in newborns.
2. As illustrated by the IL-10 and IFN-g secretion pattern, newborn cytokine profile was skewed towards the Th2 type. However, approximately 25% of newborns had an adult like cytokine profile with both good IL10 and IFN-g secretion, demonstrating that fullterm newborns are not an immunologically homogenous group at the time of birth.
3. There were significant differences in the surface marker composition of MCs between individual neonates. While gestational age correlated with the proportion of some MC types, it is evident that there are many other maternal and fetal factors that influence the maturity and nature of lymphocyte subpopulations in individual neonates.
In conclusion, the reduced ability of neonates to secrete Ig and IFN-g is not a consequence of high IL-10 secretion. However, individual newborns differ significantly in their ability to secrete cytokines as well as Igs.Tutkimuksen tarkoituksena oli selvittää välittäjä-aine IL-10 tuotto vastasyntyneiden napaverestä eristetyistä mononukleaarisista soluista. On yleisesti tiedettyä, että vastasyntyneet ovat herkkiä saamaan vakavia infektioita. Vastasyntyneiden vasta-ainetuotanto on aikuisiin verrattuna selvästi vähäisempää ja mm myös tärkeän välittäjä-aineen, gamma-interferonin (IFN-g) tuotto, on vähäistä verrattuna aikuisiin. Tutkimushypoteesimme oli, että vastasyntyneiden välittäjä-aine tuotanto on kehittymätöntä johtaen suhteettoman suureen IL-10 tuotantoon joka estäisi IFN-g-tuotantoa.
Tutkimuksessa oli mukana kaiken kaikkiaan 57 täysiaikaista vastasyntynyttä, 35 aikuista ja lisäksi 29:den keskosen lymfosyyttien alatyyppien prosentuaaliset määrät tutkittiin. Soluviljelmien tuottama IL-10, IFN-g, IgM, IgG ja IgA tuotanto tutkittiin ELISA-testillä ja lymfosyyttityyppien prosentuaaliset määrät mitattiin virtaus-sytometrillä.
Tulosten perusteella vastasyntyneet, myös heidän ns CD5+ B solut, tuottivat IL-10:tä. Aikuisiin verrattuna vastasyntyneet tuottivat kuitenkin vähemmän IL-10:tä. Muut syyt kuin IL-10 ylimäärä vaikuttaa siis vähäiseen IFN-g tuotantoon.
IL-10 ja IFN-g tuotantoja vertailemalla voitiin todeta, että vastasyntyneiden välittäjä-aine-tuotanto oli IL-10 voittoista. Kuitenkin noin 25% vastasyntyneistä tuotti molempia välittäjä-aineita aikuisten lailla. Vastasyntyneet eivät ole siis homogeeninen joukko välittäjä-aine-tuotannon suhteen.
Vastasyntyneet erosivat huomattavasti myös eri lymfosyyttien prosentuaalisten osuuksien suhteen. Tuloksiin vaikutti selvästi raskauden kesto syntymähetkellä, mutta myös monet muut sekä äitiin että lapseen liittyvät seikat vaikuttivat lymfosyyttien alatyyppien määriin ja kypsyyteen.
Edellä mainittujen välittäjä-aineiden ja vasta-aineiden tuotannossa oli siis selviä yksilöllisiä eroja. Yleisesti ottaen vastasyntyneiden vähäinen vasta-ainetuotanto ja IFN-g tuotanto ei kuitenkaan johtunut lisääntyneestä IL-10 tuotannosta.ei saavutettav
Generation of a neonatal sepsis model in humanized mice
No full textStreptococcus agalactiae (group B streptococcus (GBS)) is a gram-positive bacterium and a harmless commensal in the gastrointestinal and vaginal flora of healthy adults. In neonates however, GBS is a leading cause for pneumonia, respiratory failure, bacteremia, sepsis and meningitis. In this study, a new animal model for GBS-induced sepsis is introduced, a mouse featuring a human immune system (humanized mouse). The immune system of humanized mice and human neonates exhibit similar deficiencies, making the animals a well suited infection model for human newborn infants. This novel animal model was used to analyze the effect of two drugs routinely used in the clinic: Betamethasone, for fetal lung maturation and Indomethacin to prevent labor. Although both drugs are frequently utilized in the perinatal care, little is known about their effect on the neonatal immune system and on disease progression in GBS-induced sepsis. Initially (1 day post infection) Betamethasone treatment did not induce marked changes in cytokine levels and leukocyte populations, but resulted in a systemic reduction of live bacteria in infected animals. After 3 days, both Betamethasone and Indomethacin led to a reduction of T and B cells in the spleen, an increase in B cells in the bone marrow (BM) and a decrease in myeloid cells in the BM. These changes in leukocyte populations were accompanied by a systemic increase of live bacteria. While the systemic increase in live GBS and the changes in leukocyte populations in the BM after Indomethacin treatment were not pronounced, the drug led to increased interleukin-8 levels in the serum of infected animals. Both drugs did not induce prominent changes in the analyzed leukocyte populations and in bacterial clearance after prolonged infection (7 days). This study shows that both drugs exerted influences on human immune cells in vivo during an ongoing bacterial infection. Since treatment also increases the bacterial load, which can induce or increase organ damage, both drugs should be given in combination with antibiotics to reduce the bacterial burden
NASPGHAN Clinical Report on the Evaluation and Treatment of Pediatric Patients with Internal Penetrating Crohn Disease: Intraabdominal Abscess with and Without Fistula
No full textThe natural history of pediatric Crohn disease (CD) remains unpredictable, although some trends are observed that differentiate children from adults. Pediatric CD often presents with more severe disease and more frequent need for immunosuppressive therapy (1). Growth failure, present in 15% to 20% of patients, is a unique characteristic of pediatric CD not seen in adult-onset CD (2). Colonic disease distribution is common in patients younger than 10 years (1). The need for surgical intervention also varies, with 1 study reporting the actuarial risk of having undergone an extensive intestinal resection being 48.6% ± 5% in a childhood-onset group versus 14.6% ± 2% in the adult-onset group (P \u3c 0.001) (1). More recently, long-term follow-up of patients enrolled in pediatric registries shows a cumulative surgical rate of 14% to 17% at 5 years and 28% at 10 years (3,4)
Two Types of K⁺ Channel Subunit, Erg1 and KCNQ2/3, Contribute to the M-Like Current in a Mammalian Neuronal Cell
No full textThe potassium M current was originally identified in sympathetic ganglion cells, and analogous currents have been reported in some central neurons and also in some neural cell lines. It has recently been suggested that the M channel in sympathetic neurons comprises a heteromultimer of KCNQ2 and KCNQ3 (Wang et al., 1998) but it is unclear whether all other M-like currents are generated by these channels. Here we report that the M-like current previously described in NG108–15 mouse neuroblastoma x rat glioma cells has two components, “fast” and “slow”, that may be differentiated kinetically and pharmacologically. We provide evidence from PCR analysis and expression studies to indicate that these two components are mediated by two distinct molecular species of K+ channel: the fast component resembles that in sympathetic ganglia and is probably carried byKCNQ2/3 channels, whereas the slow component appears to be carried by merg1a channels. Thus, the channels generating M-like currents in different cells may be heterogeneous in molecular composition
