150 research outputs found
Synthesis and properties of epitaxial thin films of c-axis oriented metastable four-layered hexagonal BaRuO3BaRuO3
We have grown epitaxial thin films of c-axis oriented metastable four-layered hexagonal BaRuO3BaRuO3 on a (111) SrTiO3SrTiO3 substrate by 90° off-axis sputtering techniques. X-ray diffraction and transmission electron microscopy reveal that the films are single domains of c-axis four-layered hexagonal structures with an in-plane epitaxial arrangement of BaRuO3BaRuO3 [20]∥SrTiO3[110].[21̄1̄0]∥SrTiO3[110]. Surfaces with smooth terraces having a step height of a half unit cell (∼4.7 Å) have been observed by scanning tunneling microscopy. The in-plane electrical resistivity of the films is metallic, with a room temperature value of 810 μΩ cm and slightly curved temperature dependence. Their magnetic susceptibility is Pauli paramagnetic. The metastable layered metallic oxide can be used for understanding new solid-state phenomena and device applications. © 2000 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69917/2/APPLAB-77-3-364-1.pd
Chromosomes. CENP-C reshapes and stabilizes CENP-A nucleosomes at the centromere
Inheritance of each chromosome depends upon its centromere. A histone H3 variant, centromere protein A (CENP-A), is essential for epigenetically marking centromere location. We find that CENP-A is quantitatively retained at the centromere upon which it is initially assembled. CENP-C binds to CENP-A nucleosomes and is a prime candidate to stabilize centromeric chromatin. Using purified components, we find that CENP-C reshapes the octameric histone core of CENP-A nucleosomes, rigidifies both surface and internal nucleosome structure, and modulates terminal DNA to match the loose wrap that is found on native CENP-A nucleosomes at functional human centromeres. Thus, CENP-C affects nucleosome shape and dynamics in a manner analogous to allosteric regulation of enzymes. CENP-C depletion leads to rapid removal of CENP-A from centromeres, indicating their collaboration in maintaining centromere identity.NIH grants: (GM082989, CA186430, GM008275, GM008216, GM007229); American Heart Association predoctoral fellowship; American Cancer Society postdoctoral fellowship; NSF grant: (agreement DMR-0944772)
Developmental Trajectories of Body Mass Index Among Japanese Children and Impact of Maternal Factors during Pregnancy
Background
The aims of this study were to 1) determine the distinct patterns of body mass index (BMI) trajectories in Japanese children, and 2) elucidate the maternal factors during pregnancy, which contribute to the determination of those patterns.
Methodology/Principal Findings
All of the children (1,644 individuals) born in Koshu City, Japan, between 1991 and 1998 were followed in a longitudinal study exploring the subjects’ BMI. The BMI was calculated 11 times for each child between birth and 12 years of age. Exploratory latent class growth analyses were conducted to identify trajectory patterns of the BMI z-scores. The distribution of BMI trajectories were best characterized by a five-group model for boys and a six-group model for girls. The groups were named “stable thin,” “stable average,” “stable high average,” “progressive overweight,” and “progressive obesity” in both sexes; girls were allocated to an additional group called “progressive average.” Multinomial logistic regression found that maternal weight, smoking, and skipping breakfast during pregnancy were associated with children included in the progressive obesity pattern rather than the stable average pattern. These associations were stronger for boys than for girls.
Conclusions/Significance
Multiple developmental patterns in Japanese boys and girls were identified, some of which have not been identified in Western countries. Maternal BMI and some unfavorable behaviors during early pregnancy may impact a child’s pattern of body mass development. Further studies to explain the gender and regional differences that were identified are warranted, as these may be important for early life prevention of weight-associated health problems
Establishment of an In Vitro Assay for Assessing the Effects of Drugs on the Liver Stages of Plasmodium vivax Malaria
Plasmodium vivax (Pv) is the second most important human malaria parasite. Recent data indicate that the impact of Pv malaria on the health and economies of the developing world has been dramatically underestimated. Pv has a unique feature in its life cycle. Uninucleate sporozoites (spz), after invasion of human hepatocytes, either proceed to develop into tens of thousands of merozoites within the infected hepatocytes or remain as dormant forms called hypnozoites, which cause relapses of malaria months to several years after the primary infection. Elimination of malaria caused by Pv will be facilitated by developing a safe, highly effective drug that eliminates Pv liver stages, including hypnozoites. Identification and development of such a drug would be facilitated by the development of a medium to high throughput assay for screening drugs against Pv liver stages. We undertook the present pilot study to (1) assess the feasibility of producing large quantities of purified, vialed, cryopreserved Pv sporozoites and (2) establish a system for culturing the liver stages of Pv in order to assess the effects of drugs on the liver stages of Pv. We used primaquine (PQ) to establish this assay model, because PQ is the only licensed drug known to clear all Pv hepatocyte stages, including hypnozoites, and the effect of PQ on Pv hepatocyte stage development in vitro has not previously been reported. We report that we have established the capacity to reproducibly infect hepatoma cells with purified, cyropreserved Pv spz from the same lot, quantitate the primary outcome variable of infected hepatoma cells and demonstrate the inhibitory activity of primaquine on the infected hepatoma cells. We have also identified small parasite forms that may be hypnozoites. These data provide the foundation for finalizing a medium throughput, high content assay to identify new drugs for the elimination of all Pv liver stages
Acute and rapid degradation of endogenous proteins by Trim-Away.
Protein depletion is a key approach to understanding the functions of a protein in a biological system. We recently developed the Trim-Away approach in order to rapidly degrade endogenous proteins without prior modification. Trim-Away is based on the ubiquitin ligase and Fc receptor TRIM21, which recognizes antibody-bound proteins and targets them for degradation by the proteasome. In a typical Trim-Away experiment, protein degradation is achieved in three steps: first, introduction of an antibody against the target protein; second, recruitment of endogenous or exogenous/overexpressed TRIM21 to the antibody-bound target protein; and third, proteasome-mediated degradation of the target protein, antibody and TRIM21 complex. Protein degradation by Trim-Away is acute and rapid, with half-lives of ~10-20 min. The major advantages of Trim-Away over other protein degradation methods are that it can be applied to any endogenous protein without prior modification; that it uses conventional antibodies that are widely available; and that it can be applied to a wide range of cell types, including nondividing primary human cells, for which other loss-of-function assays are challenging. In this protocol, we describe the detailed procedures for antibody preparation and delivery in mouse oocytes and cultured cells via microinjection and electroporation. In addition, we provide recommendations for antibody selection and validation, and for the generation of TRIM21-overexpressing cell lines for cases in which endogenous TRIM21 is limited. A typical Trim-Away experiment takes just a few hours.The research leading to these results received financial support from the Medical Research Council (MC_U105192711 and MC_U105181010), the Max Planck Society, the European Community’s Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 241548, European Research Council (ERC) Starting Grant no. 337415 and a Wellcome Trust Investigator Award
Construct validity of a continuous metabolic syndrome score in children
<p>Abstract</p> <p>Objective</p> <p>The primary purpose of this study was to examine the construct validity of a continuous metabolic syndrome score (cMetS) in children. The secondary purpose was to identify a cutpoint value(s) for an adverse cMetS based on receiver operating characteristic (ROC) curve analysis.</p> <p>Methods</p> <p>378 children aged 7 to 9 years were assessed for the metabolic syndrome which was determined by age-modified cutpoints. High-density-lipoprotein cholesterol, triglycerides, the homeostasis assessment model of insulin resistance, mean arterial pressure, and waist circumference were used to create a cMetS for each subject.</p> <p>Results</p> <p>About half of the subjects did not possess any risk factors while about 5% possessed the metabolic syndrome. There was a graded relationship between the cMetS and the number of adverse risk factors. The cMetS was lowest in the group with no adverse risk factors (-1.59 ± 1.76) and highest in those possessing the metabolic syndrome (≥3 risk factors) (7.05 ± 2.73). The cutoff level yielding the maximal sensitivity and specificity for predicting the presence of the metabolic syndrome was a cMetS of 3.72 (sensitivity = 100%, specificity = 93.9%, and the area of the curve = 0.978 (0.957-0.990, 95% confidence intervals).</p> <p>Conclusion</p> <p>The results demonstrate the construct validity for the cMetS in children. Since there are several drawbacks to identifying a single cut-point value for the cMetS based on this sample, we urge researchers to use the approach herein to validate and create a cMetS that is specific to their study population.</p
Medroxyprogesterone Acetate Alters Mycobacterium Bovis BCG-Induced Cytokine Production in Peripheral Blood Mononuclear Cells of Contraceptive Users
Most individuals latently infected with Mycobacterium tuberculosis (M.tb) contain the infection by a balance of effector and regulatory immune responses. This balance can be influenced by steroid hormones such as glucocorticoids. The widely used contraceptive medroxyprogesterone acetate (MPA) possesses glucocorticoid activity. We investigated the effect of this hormone on immune responses to BCG in household contacts of active TB patients. Multiplex bead array analysis revealed that MPA demonstrated both glucocorticoid and progestogenic properties at saturating and pharmacological concentrations in peripheral blood mononuclear cells (PBMCs) and suppressed antigen specific cytokine production. Furthermore we showed that PBMCs from women using MPA produced significantly lower levels of IL-1α, IL-12p40, IL-10, IL-13 and G-CSF in response to BCG which corresponded with lower numbers of circulating monocytes observed in these women. Our research study is the first to show that MPA impacts on infections outside the genital tract due to a systemic effect on immune function. Therefore MPA use could alter susceptibility to TB, TB disease severity as well as change the efficacy of new BCG-based vaccines, especially prime-boost vaccine strategies which may be administered to adult or adolescent women in the future
Efficacy of Structural-Level Condom Distribution Interventions: A Meta-Analysis of U.S. and International Studies, 1998–2007
This systematic review examines the overall efficacy of U.S. and international-based structural-level condom distribution interventions (SLCDIs) on HIV risk behaviors and STIs and identifies factors associated with intervention efficacy. A comprehensive literature search of studies published from January 1988 through September 2007 yielded 21 relevant studies. Significant intervention effects were found for the following outcomes: condom use, condom acquisition/condom carrying, delayed sexual initiation among youth, and reduced incident STIs. The stratified analyses for condom use indicated that interventions were efficacious for various groups (e.g., youth, adults, males, commercial sex workers, clinic populations, and populations in areas with high STI incidence). Interventions increasing the availability of or accessibility to condoms or including additional individual, small-group or community-level components along with condom distribution were shown to be efficacious in increasing condom use behaviors. This review suggests that SLCDIs provide an efficacious means of HIV/STI prevention
Interferon Regulatory Factor-1 (IRF-1) Shapes Both Innate and CD8+ T Cell Immune Responses against West Nile Virus Infection
Interferon regulatory factor (IRF)-1 is an immunomodulatory transcription factor that functions downstream of pathogen recognition receptor signaling and has been implicated as a regulator of type I interferon (IFN)-αβ expression and the immune response to virus infections. However, this role for IRF-1 remains controversial because altered type I IFN responses have not been systemically observed in IRF-1-/- mice. To evaluate the relationship of IRF-1 and immune regulation, we assessed West Nile virus (WNV) infectivity and the host response in IRF-1-/- cells and mice. IRF-1-/- mice were highly vulnerable to WNV infection with enhanced viral replication in peripheral tissues and rapid dissemination into the central nervous system. Ex vivo analysis revealed a cell-type specific antiviral role as IRF-1-/- macrophages supported enhanced WNV replication but infection was unaltered in IRF-1-/- fibroblasts. IRF-1 also had an independent and paradoxical effect on CD8+ T cell expansion. Although markedly fewer CD8+ T cells were observed in naïve animals as described previously, remarkably, IRF-1-/- mice rapidly expanded their pool of WNV-specific cytolytic CD8+ T cells. Adoptive transfer and in vitro proliferation experiments established both cell-intrinsic and cell-extrinsic effects of IRF-1 on the expansion of CD8+ T cells. Thus, IRF-1 restricts WNV infection by modulating the expression of innate antiviral effector molecules while shaping the antigen-specific CD8+ T cell response
First nationwide survey on cardiovascular risk factors in Grand-Duchy of Luxembourg (ORISCAV-LUX)
BACKGROUND: The ORISCAV-LUX study is the first baseline survey of an on-going cardiovascular health monitoring programme in Grand-Duchy of Luxembourg. The main objectives of the present manuscript were 1) to describe the study design and conduct, and 2) to present the salient outcomes of the study, in particular the prevalence of the potentially modifiable and treatable cardiovascular disease risk factors in the adult population residing in Luxembourg. METHOD: ORISCAV-LUX is a cross-sectional study based on a random sample of 4496 subjects, stratified by gender, age categories and district, drawn from the national insurance registry of 18-69 years aged Luxembourg residents, assuming a response rate of 30% and a proportion of 5% of institutionalized subjects in each stratum. The cardiovascular health status was assessed by means of a self-administered questionnaire, clinical and anthropometric measures, as well as by blood, urine and hair examinations. The potentially modifiable and treatable risk factors studied included smoking, hypertension, dyslipidemia, diabetes mellitus, and obesity. Both univariate and multivariate statistical analyses used weighted methods to account for the stratified sampling scheme. RESULTS: A total of 1432 subjects took part in the survey, yielding a participation rate of 32.2%. This figure is higher than the minimal sample size of 1285 subjects as estimated by power calculation. The most predominant cardiovascular risk factors were dyslipidemia (69.9%), hypertension (34.5%), smoking (22.3%), and obesity (20.9%), while diabetes amounted 4.4%. All prevalence rates increased with age (except smoking) with marked gender differences (except diabetes). There was a significant difference in the prevalence of hypertension and of lipid disorders by geographic region of birth. The proportion of subjects cumulating two or more cardiovascular risk factors increased remarkably with age and was more predominant in men than in women (P<0.0001). Only 14.7% of men and 23.1% of women were free of any cardiovascular risk factor. High prevalence of non-treated CVRF, notably for hypertension and dyslipidemia, were observed in the study population. CONCLUSION: The population-based ORISCAV-LUX survey revealed a high prevalence of potentially modifiable and treatable cardiovascular risk factors among apparently healthy subjects; significant gender and age-specific differences were seen not only for single but also for combined risk factors. From a public health perspective, these preliminary findings stress the urgent need for early routine health examinations, preventive interventions and lifestyle behavioural changes, even in young asymptomatic adults, to decrease cardiovascular morbidity and mortality in Luxembourg
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