Helicity conservation and factorization-suppressed charmless B decays

Toward the goal of extracting the weak angle alpha, the decay B^0/B^0-bar to a_0^{+/-}pi^{-/+} was recently measured. The decay B^0 to a_0^+pi^- is not only forbidden in the factorization limit of the tree interaction, but also strongly suppressed for the penguin interaction if short-distance QCD dominates. This makes extraction of alpha very difficult from a^{+/-}\pi^{-/+}. We examine the simlar factorization-suppressed decays, in particular, B^0\to b_1^+pi^-. The prospect of obtaining alpha is even less promising with b_1^{+/-}pi^{-/+}. To probe how well the short-distance dominance works, we emphasize importance of testing helicity conservation in the charmless B decays with spins.Comment: The version to appear in Phys. Rev. D after minor alteration

A semisynthetic strategy to generate phosphorylated and acetylated histone H2B

Proteins are subject to numerous post-translational modifications (PTMs) that can alter the chemical structure, and hence function, of the molecule. The astonishing diversity of PTMs possible on proteins is exemplified by histones, nuclear proteins that form the protein core of the nucleosome particle. Histones can be modified in a variety of ways including acetylation, phosphorylation, methylation, ADP-ribosylation and ubiquitylation. Moreover, many, if not all, of these modifications can occur in combination. Indeed, there is growing evidence that functional cross-talk between histone PTMs is essential for the regulation of gene expression and ultimately cell fate and identity. Biochemical studies into the role of histone PTMs are often confounded by the difficulty associated with obtaining large quantities of homogeneously modified proteins. For this reason chemical approaches to obtaining post-translationally modified histones have received considerable attention in recent years. Among the available strategies, the protein ligation approach, expressed protein ligation (EPL), offers the most flexibility in terms of the number and type of PTMs that can be incorporated. To date, EPL has been used to generate phosphorylated, acetylated, and methylated forms of histone H3, acetylated H4, and ubiquitylated H2B. Nonetheless, many modified histones have yet to be accessed using semi-synthesis. A notable case in point is the N-terminal region of H2B, which has been described to possess several PTMs, including (poly)lysine acetylation and serine 14 phosphorylation, which have been implicated in transcription and apoptotic chromatin compaction, respectively. Differentially modified semi-synthetic H2B analogs would be useful to assess the affect of acetylation on both antibody recognition as well as on the efficiency of phosphorylation. In this report, we describe a general semi-synthetic route to H2B that allows the installation of PTMs into an otherwise native polypeptide background

Human papillomavirus 16 L2 inhibits the transcriptional activation function, but not the DNA replication function, of HPV-16 E2

In this study we analysed the outcome of the interaction between HPV-16 L2 and E2 on the transactivation and DNA replication functions of E2. When E2 was expressed on its own, it transactivated a number of E2-responsive promoters but co-expression of L2 led to the down-regulation of the transcription transactivation activity of the E2 protein. This repression is not mediated by an increased degradation of the E2 protein. In contrast, the expression of L2 had no effect on the ability of E2 to activate DNA replication in association with the viral replication factor E1. Deletion mutagenesis identified L2 domains responsible for binding to E2 (first 50 N-terminus amino acid residues) and down-regulating its transactivation function (residues 301–400). The results demonstrate that L2 selectively inhibits the transcriptional activation property of E2 and that there is a direct interaction between the two proteins, although this is not sufficient to mediate the transcriptional repression. The consequences of the L2–E2 interaction for the viral life cycle are discussed

Charge and critical density of strange quark matter

The electric charge of strange quark matter is of vital importance to experiments. A recent investigation shows that strangelets are most likely highly negatively charged, rather than slightly positively charged as previously believed. Our present study indicates that negative charges can indeed lower the critical density, and thus be favorable to the experimental searches in heavy ion collisions. However, too much negative charges can make it impossible to maintain flavor equilibrium.Comment: 4 pages, LATeX with REVTeX style, one PS figure. To be published in Phys. Rev. C 59(6), 199

Final-state interaction and s-quark helicity conservation in B -> J/psi K*

The Section of charm quark spin conservation is deleted since it involves more dynamical assumptions than previously stated. A few comments are added in view of new experimental results.Comment: To replace the earlier version of hep-ph/0106354. Minor additions and one deletion with no change in the main argument nor the conclusio

Mass formulas and thermodynamic treatment in the mass-density-dependent model of strange quark matter

The previous treatments for strange quark matter in the quark mass-density-dependent model have unreasonable vacuum limits. We provide a method to obtain the quark mass parametrizations and give a self-consistent thermodynamic treatment which includes the MIT bag model as an extreme. In this treatment, strange quark matter in bulk still has the possibility of absolute stability. However, the lower density behavior of the sound velocity is opposite to previous findings.Comment: Formatted in REVTeX 3.1, 5 pages, 3 figures, to appear in PRC6

Search for the decay K+→π+ννˉK^+\to \pi^+ \nu \bar\nu in the momentum region Pπ<195 MeV/cP_\pi < 195 {\rm ~MeV/c}

We have searched for the decay $K^+ \to \pi^+ \nu \bar\nu$ in the kinematic region with pion momentum below the $K^+ \to \pi^+ \pi^0$ peak. One event was observed, consistent with the background estimate of $0.73\pm 0.18$. This implies an upper limit on $B(K^+ \to \pi^+ \nu \bar\nu)< 4.2\times 10^{-9}$ (90% C.L.), consistent with the recently measured branching ratio of $(1.57^{+1.75}_{-0.82}) \times 10^{-10}$, obtained using the standard model spectrum and the kinematic region above the $K^+ \to \pi^+ \pi^0$ peak. The same data were used to search for $K^+ \to \pi^+ X^0$, where $X^0$ is a weakly interacting neutral particle or system of particles with $150 < M_{X^0} < 250 {\rm ~MeV/c^2}$.Comment: 4 pages, 2 figure

The Chinese Herbal Medicine Tien-Hsien Liquid Inhibits Cell Growth and Induces Apoptosis in a Wide Variety of Human Cancer Cells

ABSTRACT Objective: Tien-Hsien liquid (THL) is a commercially available Chinese herbal mixture that has been used as an anticancer dietary supplement for more than 10 years. We recently showed that THL has strong immunomodulatory effects on peripheral blood mononuclear cells (PBMC) and T cells. To investigate the antitumor activity of THL further, we sought to test whether THL could induce apoptosis in various human cancer cell lines based on the fact that THL contains several components with tumor killing functions. Design: The growth inhibitory effect of THL on human cervical carcinoma C-33A cells, human lung carcinoma H1299 cells, and human PBMC was assessed by counting viable cells using the trypan blue dye exclusion method. The apoptosis-inducing activity of THL in H1299 cells was assessed by analyzing the cells with four assays: (1) Hoechst 33258 nuclear DNA staining; (2) the terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) assay; (3) the nucleosomal DNA fragment ladder assay; and (4) the sub-G 1 cell analysis. The activities of caspase-8, -9, and -3 in H1299 cells treated with or without THL were also measured to elucidate the possible mechanism underlying THL apoptosis-inducing effect. Finally, the apoptotic effect of THL on fifteen human cancer cell lines and normal human cells were analyzed by the TUNEL assay. Results: THL could induce apoptosis in all human cancer cell lines tested but not in normal human cells. THL treatment of H1299 cancer cells resulted in activation of caspase-8, -9, and -3 and the inhibitors of these caspases could partially block THL-induced apoptosis. Conclusions: THL has been used by numerous patients with cancer for many years with no known adverse effect. Our present study showing that THL had a broad-range tumor killing function has provided a molecular basis underlying THL therapeutic activity. Furthermore, because THL had apoptotic effects only on cancer cells but not on normal cells, this selectivity suggests that THL could be a potential cancer therapeutic agent. 24

Further search for the decay K+→π+ννˉK^+ \to \pi^+ \nu \bar \nu in the momentum region P < 195 MeV/c

We report the results of a search for the decay $K^+ \to \pi^+ \nu \bar \nu$ in the kinematic region with $\pi^+$ momentum $140 < P < 195$ MeV/c using the data collected by the E787 experiment at BNL. No events were observed. When combined with our previous search in this region, one candidate event with an expected background of $1.22 \pm 0.24$ events results in a 90% C.L. upper limit of $2.2 \times 10^{-9}$ on the branching ratio of $K^+ \to \pi^+ \nu \bar \nu$. We also report improved limits on the rates of $K^+ \to \pi^+ X^0$ and $K^+ \to \pi^+ X^1 X^2$ where $X^0, X^1, X^2$ are hypothetical, massless, long-lived neutral particles.Comment: 5 pages, 3 figures, Accepted for publication in Phys. Rev.

Impact of CP phases on the search for sleptons tau and nu_tau

We study the decays of the tau-sleptons (stau_{1,2}) and tau-sneutrino (snu_tau) in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters A_tau, mu and M_1 (U(1) gaugino mass). We show that the effect of the CP phases of these parameters on the branching ratios of stau_{1,2} and snu_tau decays can be quite strong in a large region of the MSSM parameter space. This could have an important impact on the search for stau_{1,2} and snu_tau and the determination of the MSSM parameters at future colliders.Comment: 15 pages, 5 figures, LaTeX2