Big-Bang Nucleosynthesis with Unstable Gravitino and Upper Bound on the Reheating Temperature

We study the effects of the unstable gravitino on the big-bang nucleosynthesis. If the gravitino mass is smaller than \sim 10 TeV, primordial gravitinos produced after the inflation are likely to decay after the big-bang nucleosynthesis starts, and the light element abundances may be significantly affected by the hadro- and photo-dissociation processes as well as by the p n conversion process. We calculate the light element abundances and derived upper bound on the reheating temperature after the inflation. In our analysis, we calculate the decay parameters of the gravitino (i.e., lifetime and branching ratios) in detail. In addition, we performed a systematic study of the hadron spectrum produced by the gravitino decay, taking account of all the hadrons produced by the decay products of the gravitino (including the daughter superparticles). We discuss the model-dependence of the upper bound on the reheating temperature.Comment: 32 pages, 11 figure

Big-Bang Nucleosynthesis and Gravitino

We derive big-bang nucleosynthesis (BBN) constraints on both unstable and stable gravitino taking account of recent progresses in theoretical study of the BBN processes as well as observations of primordial light-element abundances. In the case of unstable gravitino, we set the upper limit on the reheating temperature assuming that the primordial gravitinos are mainly produced by the scattering processes of thermal particles. For stable gravitino, we consider Bino, stau and sneutrino as the next-to-the-lightest supersymmetric particle and obtain constraints on their properties. Compared with the previous works, we improved the following points: (i) we use the most recent observational data, (ii) for gravitino production, we include contribution of the longitudinal component, and (iii) for the case with unstable long-lived stau, we estimate the bound-state effect of stau accurately by solving the Boltzmann equation.Comment: 27 pages, 16 figure

Measurement of hepatitis B virus core-related antigen is valuable for identifying patients who are at low risk of lamivudine resistance

ArticleLIVER INTERNATIONAL. 26(1): 90-96 (2006)journal articl

Cellular immunity in children with successful immunoprophylactic treatment for mother-to-child transmission of hepatitis B virus

Background: The administration of hepatitis B immunoglobulin followed by hepatitis B vaccine can result in a protective efficacy of almost 90% in mother-to-child transmission of hepatitis B virus (HBV). However, little is known about immunity against HBV infection in children after immunoprophylactic treatment. We tried to assess the association between T-cell responses and viremia in children after successful prophylactic treatment. Methods: Thirteen children and their 8 HBV carrier mothers (8 families), who were positive for human leukocyte antigen (HLA)-A24, were enrolled in this study. All of the 13 children received immunoprophylactic treatment and became negative for hepatitis B surface antigen (HBsAg) after birth. HBV-specific cytotoxic T lymphocyte (CTL) responses were evaluated using IFNγ - enzyme-linked immunosorbent spot (ELISPOT) and major histocompatibility complex class I peptide pentamer assays. Serum HBV DNA was measured by real-time PCR. Results: Significant HBV-specific T-cell responses were detected in 2 (15%) of the 13 children by ELISPOT. However, the frequency of HLA-A24-HBV-specific CTLs was very low in both HBV carrier mothers and children using pentamers. Of the 13 children, 4 (31%) were positive for serum HBV DNA. However, the levels of serum HBV DNA were 100 copies/ml or less. One of the 2 children in whom significant HBV-specific CTL responses were detectable was positive for serum HBV DNA. Conclusions: HBV core and polymerase-specific T-cell responses were detected and a low-dose viremia was observed in children after successful immunoprophylaxis treatment. Although the presence of viremia was not related to HBV-specific T-cell responses, CTLs might play a role in the control of HBV infection in children born to HBsAg-positive mothers after immunoprophylactic treatment. </p

Mass spectrum of primordial black holes from inflationary perturbation in the Randall-Sundrum braneworld: a limit on blue spectra

The mass spectrum of the primordial black holes formed by density perturbation in the radiation-dominated era of the Randall-Sundrum type-2 cosmology is given. The spectrum coincides with standard four-dimensional one on large scales but the deviation is apparent on smaller scales. The mass spectrum is initially softer than standard four-dimensional one, while after accretion during the earliest era it becomes harder than that. We also show expected extragalactic diffuse photon background spectra varying the initial perturbation power-law power spectrum and give constraints on the blue spectra and/or the reheating temperature. The most recent observations on the small scale density perturbation from WMAP, SDSS and Lyman-\alpha Forest are used. What we get are interpreted as constraints on the smaller scale inflation on the brane connected to the larger one at the scale of Lyman-\alpha Forest. If we set the bulk curvature radius to be 0.1 mm and assume the reheating temperature is higher than 10^6 GeV, the scalar spectral index from the smaller scale inflation is constrained to be n \lesssim 1.3. Typically, the constraints are tighter than standard four-dimensional one, which is also revised by us using the most recent observations.Comment: 19 pages, 6 figures; typos corrected, references added, published in JCA

Defending the genome from the enemy within:mechanisms of retrotransposon suppression in the mouse germline

The viability of any species requires that the genome is kept stable as it is transmitted from generation to generation by the germ cells. One of the challenges to transgenerational genome stability is the potential mutagenic activity of transposable genetic elements, particularly retrotransposons. There are many different types of retrotransposon in mammalian genomes, and these target different points in germline development to amplify and integrate into new genomic locations. Germ cells, and their pluripotent developmental precursors, have evolved a variety of genome defence mechanisms that suppress retrotransposon activity and maintain genome stability across the generations. Here, we review recent advances in understanding how retrotransposon activity is suppressed in the mammalian germline, how genes involved in germline genome defence mechanisms are regulated, and the consequences of mutating these genome defence genes for the developing germline

Virologic and clinical characteristics of HBV genotypes/subgenotypes in 487 Chinese pediatric patients with CHB

<p>Abstract</p> <p>Background</p> <p>The association of hepatitis B virus (HBV) genotypes/subgenotypes with clinical characteristics is increasingly recognized. However, the virologic and clinical features of HBV genotypes/subgenotypes in pediatric patients remain largely unknown.</p> <p>Methods</p> <p>Four hundred and eighty-seven pediatric inpatients with CHB were investigated, including 217 nucleos(t)ide analog-experienced patients. HBV genotypes/subgenotypes and reverse transcriptase (RT) mutations were determined by direct sequencing. The stage of fibrosis and degree of inflammatory activity were evaluated by the Metavir score system.</p> <p>Results</p> <p>Among 487 enrolled pediatric patients, HBV genotype C2 and B2 were the most two prevalent (73.7% and 21.1%). Comparing with HBV/B2 infected patients, no significant difference was observed in the incidence rate and mutant patterns of lamivudine- or adefovir-resistant mutations in HBV/C2 infected patients (<it>P </it>> 0.05). Importantly, we found that the degree of hepatic inflammation degree, fibrosis stage and ALT level were significantly higher in HBV/C2-infected HBeAg positive patients than it was in HBV/B2-infected ones.</p> <p>Conclusions</p> <p>The pediatric patients with HBV/C2 infection might be more susceptible to develop severe liver pathogenesis.</p

Molecular characterization of hepatitis B virus X gene in chronic hepatitis B patients

BACKGROUND: HBV-X protein is associated with the pathogenesis of HBV related diseases, specially in hepatocellular carcinomas of chronic patients. Genetic variability of the X gene includes genotypic specific variations and mutations emerging during chronic infection. Its coding sequence overlaps important regions for virus replication, including the basal core promoter. Differences in the X gene may have implications in biological functions of the protein and thus, affect the evolution of the disease. There are controversial results about the consequences of mutations in this region and their relationship with pathogenesis. The purpose of this work was to describe the diversity of HBV-X gene in chronic hepatitis patients infected with different genotypes, according to liver disease. METHODS: HBV-X gene was sequenced from chronic hepatitis B patient samples, analyzed by phylogeny and genotyped. Nucleotide and aminoacid diversity was determined calculating intragenetic distances. Mutations at 127, 130 and 131 aminoacids were considered in relation to liver disease. RESULTS: The most prevalent genotype detected in this cohort was F (F1 and F4), followed by D and A. Most of the samples corresponding to genotypes A and F1 were HBeAg(+) and for genotypes D and F4, HBeAg(−) samples were represented in a higher percentage. Intragenetic distance values were higher in HBeAg(−) than in positive samples for all genotypes, and lower in overlapped regions, compared to single codification ones. Nucleotide and aminoacid diversities were higher in HBeAg(−), than in HBeAg(+) samples. CONCLUSIONS: Independently of the infecting genotypes, mutations at any of 127, 130 and/or 131 aminoacid positions and HBeAg(−) status were associated with mild liver disease in this cohort

Constraints on Supersymmetric Models from Catalytic Primordial Nucleosynthesis of Beryllium

The catalysis of nuclear reactions by negatively charged relics leads to increased outputs of primordial ^6Li and ^9Be. In combination with observational constraints on the primordial fractions of ^6Li and ^9Be, this imposes strong restrictions on the primordial abundance and the lifetime of charged relics. We analyze the constraints from the catalysis of ^9Be on supersymmetric models in which the gravitino is the lightest supersymmetric particle and a charged slepton--such as the lighter stau--the next-to-lightest supersymmetric particle (NLSP). Barring the special cases in which the primordial fraction of the slepton NLSP is significantly depleted, we find that the ^9Be data require a slepton NLSP lifetime of less than 6x10^3 seconds. We also address the issue of the catalytic destruction of ^6Li and ^9Be by late forming bound states of protons with negatively charged relics finding that it does not lead to any significant modification of the limit on the slepton lifetime.Comment: 31 pages, 8 figures; minor additions, matches published versio