Movement proteins (BC1 and BV1) of Abutilon mosaic geminivirus are cotransported in and between cells of sink but not of source leaves as detected by green fluorescent protein tagging

Two movement proteins (BV1 and BC1) facilitate the intra- and intercellular transport of begomoviruses in plants. In contrast to other geminiviruses the movement protein BC1 of Abutilon mosaic virus (AbMV) remained in the supernatant after centrifuging plant extracts at 20,000 g. To test whether this unusual behavior results from a distinct intracellular distribution of the protein, the BC1 gene has been fused to the gene of green fluorescent protein (GFP). The resulting plasmids were delivered into nonhost plants (Allium cepa) as well as into mature and immature cells of host plants (Nicotiana tabacum, N. benthamiana) by biolistic bombardment for transient expression in planta. BC1 directed GFP to two different cellular sites. In the majority of nonhost cells as well as in mature cells of host leaves, BC1 was mainly localized in small punctate flecks at the cell periphery or, to a lesser extent, around the nucleus. In sink leaves of host plants, GFP:BC1 additionally developed disc-like structures in the cell periphery. Cobombardment of GFP:BC1 with its cognate infectious DNA A and B did not change their subcellular distribution patterns in source leaves but led to the formation of peculiar needle-like structures in sink leaves. The nuclear shuttle protein (BV1) of AbMV accumulated mainly inside the nuclei as shown by immunohistochemical staining and GFP tagging. In sink cells of host plants it was mobilized to the plasma membrane and to the nucleus of the neighboring cell by coexpressed BC1, GFP:BC1, BC1:GFP, or after cobombardment with the cognate viral DNA. Only under these conditions were GFP:BC1 and BC1:GFP also found in the recipient cell.     

Modification of Si(100) surface by the grafting of poly(ethylene glycol) for reduction in protein adsorption and platelet adhesion

The modification of argon plasma-pretreated single-crystal Si(100) wafer surfaces via the UV-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA) macromonomer (molecular weight approximately 340) for biomaterials applications was explored. The modified Si(100) surfaces were characterized by X-ray photoelectron spectroscopy and atomic force microscopy. Surface peroxide concentrations resulting from the argon plasma treatment and subsequent atmospheric exposure were determined by a coupling reaction with diphenylpicrylhydrazyl. The results suggested that a short plasma treatment time of 10 s and brief air exposure were sufficient for generating an optimum amount of peroxides and hydroperoxides for the subsequent UV-induced graft polymerization. The graft concentration of the PEGMA polymer increased with increasing PEGMA macromonomer concentration for the graft polymerization and with increasing UV graft polymerization time. The PEGMA graft-polymerized silicon surface with a high poly(ethylene glycol) graft concentration was very effective in preventing protein adsorption and platelet adhesion. The grafted PEGMA polymer layer on the Si(100) surface exhibited fairly good stability during storage in a buffer solution.     

Multi-virulence-locus sequence typing clarifies epidemiology of recent listeriosis outbreaks in the United States

Multi-virulence-locus sequence typing (MVLST) was used to analyze isolates from two major listeriosis outbreaks in the United States in 1998 and 2002 that were due to consumption of contaminated hot dogs and turkey deli meat, respectively. MVLST demonstrated high epidemiological relevance and indicated that the two outbreaks were the result of one epidemic.     

氧化苦参碱对LAK细胞活性的影响

ＬＡＫ细胞具有很强的广谱杀瘤作用，而氧化苦参碱具有较强的免疫抑制作用。本文研究了氧化苦参碱对ＬＡＫ细胞活力的影响，结果表明：氧化苦参碱可抑制ＩＬ－２对小鼠脾细胞的促增殖作用，并且对ＩＬ－２活化ＬＡＫ细胞杀伤Ｐ８１５的能力也有抑制作用。当ＩＬ－２（５００ｕ／ｍｌ）与２００μｇ／ｍｌ的氧化苦参碱共同孵育４ｄ后，可使ＬＡＫ细胞杀瘤能力（在效靶比为１００：１时）的８２．５％被抑制。同时氧化苦参碱本身对Ｐ８     

Cooperation between the Cdk inhibitors p27KIP1 and p57KIP2 in the control of tissue growth and development

Cell cycle exit is required for terminal differentiation of many cell types. The retinoblastoma protein Rb has been implicated both in cell cycle exit and differentiation in several tissues. Rb is negatively regulated by cyclin-dependent kinases (Cdks). The main effectors that down-regulate Cdk activity to activate Rb are not known in the lens or other tissues. In this study, using multiple mutant mice, we show that the Cdk inhibitors p27^KIP1 and p57^KIP2 function redundantly to control cell cycle exit and differentiation of lens fiber cells and placental trophoblasts. These studies demonstrate that p27^KIP1 and p57^KIP2 are critical terminal effectors of signal transduction pathways that control cell differentiation.     

体外免疫法抗MG7人源性单抗的研制及其意义

本文建立了人淋巴细胞体外致敏技术,用本文作者既往制备的鼠抗人胃癌单抗MG7作为免疫原,在体外致敏人淋巴细胞获得成功。经与本文作者在建立的人鼠种间骨髓瘤细胞系FMC-1进行人鼠人双杂交,获得一株能与鼠源性抗体反应,但不与人、羊、马、兔等其他种属动物产生的抗体相反应的人源性单抗HMG7。本文讨论了HMG7可能的应用价值,以及在人淋巴细胞体外致敏过程中应注意的几个环节。     

High density of immobilized galactose ligand enhances hepatocyte attachment and function

Galactosylated surface is an attractive substrate for hepatocyte culture because of the specific interaction between the galactose ligand and the asialoglycoprotein receptor on hepatocytes. In this study, we described a scheme to achieve high density of immobilized galactose ligands on polyethylene terephthalate (PET) surface by first surface-grafting polyacrylic acid on plasma-pretreated PET film under UV irradiation, followed by conjugation of a galactose derivative (1-O-(6'-aminohexyl)-D-galactopyranoside) to the grafted polyacrylic acid chains. A high galactose density of 513 nmol/cm(2) on the PET surface was used in this study to investigate the behavior of cultured hepatocyte. This engineered substrate showed high affinity to fluorescein isothiocyanate-lectin binding. Primary rat hepatocytes, when seeded at a density of 2 x 10(5) cells/cm(2), attached to the galactosylated PET substrate at a similar efficiency compared with collagen-coated substrate. The hepatocytes spontaneously formed aggregates 1 day after cell seeding and showed better maintenance of albumin secretion and urea synthesis functions than those cultured on collagen-coated surface.     

Involvement of ERK, p38 and NF-kappaB signal transduction in regulation of TLR2, TLR4 and TLR9 gene expression induced by lipopolysaccharide in mouse dendritic cells

Toll-like receptors (TLR) are sentinel receptors capable of recognizing pathogen-associated molecule patterns (PAMP) such as lipopolysaccharide (LPS) and CpG-containing oligonucleotides (CpG ODN). TLR2 and TLR4 are major receptors for Gram-positive and Gram-negative bacterial cell wall components, respectively. TLR9 is necessary for CpG signalling. LPS or CpG ODN can activate immature dendritic cells (DC) and induce DC maturation characterized by production of cytokines, up-regulation of co-stimulatory molecules, and increased ability to activate T cells. However, little is known regarding the regulation of TLR gene expression in mouse DC. In this study, we investigated the regulation of TLR2, TLR4 and TLR9 gene expression by LPS in murine immature DC. TLR2, TLR4 and TLR9 mRNA were up-regulated following LPS stimulation. The up-regulation of TLR9 expression coincided with significantly increased production of tumour necrosis factor-alpha induced by LPS plus CpG ODN. While inhibition of extracellular signal-related kinase and NF-kappaB activation suppressed the up-regulation of the expression of TLR2, TLR4 and TLR9 mRNA, inhibition of p38 kinase prevented the up-regulation of TLR2 and TLR4 mRNA expression but enhanced the up-regulation of TLR9 expression. These results demonstrated that TLR2, TLR4 and TLR9 gene expression was differently regulated by LPS in mouse immature DC. Up-regulation of TLR2, TLR4 and TLR9 expression by LPS might promote the overall responses of DC to bacteria and help to explain the synergy between LPS and other bacterial products in the induction of cytokine production.     

Immunoglobulin G from anti-glucose-6-phosphate isomerase antibodies positive patient with rheumatoid arthritis induces synovitis in cynomolgus monkeys

Anti-glucose-6-phosphate isomerase (GPI) antibodies (Abs) solely induce arthritis in mice. High titers of anti-GPI Abs are found in some patients with rheumatoid arthritis (RA), but their pathogenic role remains elusive. The aim of this study was to evaluate the pathogenic role of anti-GPI Abs in cynomolgus monkeys. IgG fractions were separated from sera of anti-GPI Abs-positive RA patients and healthy subjects and directly injected into the metacarpophalangeal joints of 4 cynomolgus monkeys. At day 16, the joints were harvested and examined histologically and immunohistochemically. The expression of C5a receptor (C5aR) molecule in the synovium was quantified by real-time PCR using cDNA from monkey joints. In monkey joints, IgG including anti-GPI Abs resulted in recruitment of granulocytes and mononuclear cells, strong deposition of human IgG on the articular surface, and overexpression of C5aR, but no joint swelling. No infiltrated cells or IgG deposition were observed in monkeys injected with IgGs from healthy subjects. Our results suggest that IgG fraction from RA patients including anti-GPI Abs may play a crucial role in the generation of synovitis in monkeys, although the pathogenesis of anti-GPI Abs in RA patients is still uncertain.