Eccentric lamellar keratolimbal grafts harvested with a manually guided microkeratome

Background: To perform lamellar keratolimbal allograft transplantation in a one- step procedure with a single graft, we investigated the feasibility of harvesting eccentric lamellar keratolimbal grafts from conventionally processed corneoscleral buttons using a manually guided microkeratome in conjunction with an artificial anterior chamber system. Methods: We used the Moria LSK- One microkeratome and the automated lamellar therapeutic keratoplasty ( ALTK) system ( Antony, France). Ten human donor eyes were used to obtain single- piece lamellar keratolimbal grafts. Specimens were processed for light and electron microscopy. Results: Eccentric keratolimbal grafts could be obtained from all human donor buttons. Grafts include a crescent- shaped limbal and a large corneal portion. No visible damage to the limbal region was discernible. Conclusion: Our data show that the LSK- One microkeratome in conjunction with the ALTK system allows harvesting eccentric keratolimbal grafts from donor corneoscleral buttons. Copyright (c) 2007 S. Karger AG, Basel

microRNA-29b prevents liver fibrosis by attenuating hepatic stellate cell activation and inducing apoptosis through targeting PI3K/AKT pathway

microRNA-29b (miR-29b) is known to be associated with TGF-β-mediated fibrosis, but the mechanistic action of miR-29b in liver fibrosis remains unclear and is warranted for investigation. We found that miR-29b was significantly downregulated in human and mice fibrotic liver tissues and in primary activated HSCs. miR-29b downregulation was directly mediated by Smad3 through binding to the promoter of miR-29b in hepatic stellate cell (HSC) line LX1, whilst miR-29b could in turn suppress Smad3 expression. miR-29b transduction in the liver of mice prevented CCl4 induced-fibrogenesis, concomitant with decreased expression of α-SMA, collagen I and TIMP-1. Ectopic expression of miR-29b in activated HSCs (LX-1, HSC-T6) inhibited cell viability and colony formation, and caused cell cycle arrest in G1 phase by downregulating cyclin D1 and p21cip1. Further, miR-29b induced apoptosis in HSCs mediated by caspase-9 and PARP. miR-29b inhibited its downstream effectors of PIK3R1 and AKT3 through direct targeting their 3'UTR regions. Moreover, knockdown of PIK3R1 or AKT3 suppressed α-SMA and collagen I and induced apoptosis in both HSCs and in mice. In conclusion, miR-29b prevents liver fibrogenesis by inhibiting HSC activation and inducing HSC apoptosis through inhibiting PI3K/AKT pathway. These results provide novel mechanistic insights for the anti-fibrotic effect of miR-29b.published_or_final_versio

Comparative Study of Inference Methods for Bayesian Nonnegative Matrix Factorisation

In this paper, we study the trade-offs of different inference approaches for Bayesian matrix factorisation methods, which are commonly used for predicting missing values, and for finding patterns in the data. In particular, we consider Bayesian nonnegative variants of matrix factorisation and tri-factorisation, and compare non-probabilistic inference, Gibbs sampling, variational Bayesian inference, and a maximum-a-posteriori approach. The variational approach is new for the Bayesian nonnegative models. We compare their convergence, and robustness to noise and sparsity of the data, on both synthetic and real-world datasets. Furthermore, we extend the models with the Bayesian automatic relevance determination prior, allowing the models to perform automatic model selection, and demonstrate its efficiency

Expression of peroxisome proliferator-activated receptor δ in human gastric cancer and its response to specific COX-2 inhibitor

Peroxisome proliferator-activated receptor δ (PPARδ) is ligand-activated transcription factor of the nuclear receptor superfamily which is recently implicated in carcinogenesis. We examined the expression profiles of PPARδ in human gastric cancer, normal gastric mucosa and gastric cancer cell lines by RT-PCR, Western blot and immunohistochemistry. PPARδ mRNA and protein was found to be ubiquitously expressed in all 5 gastric cancer cell lines, 40 gastric cancer samples and 10 normal gastric mucosa from non-cancer patients. Positive immunoreactivity was detected in the nuclei of normal and malignant gastric epithelium. Treatment of gastric cell line MKN45 that overexpressed cyclooxygenase-2 (COX-2) with specific COX-2 inhibitor NS398 resulted in a time- and dose-dependent suppression of PPARδ expression. In contrast, there was no suppression of PPARδ in MKN28 gastric cell line with low COX-2 expression. Our results demonstrated the ubiquitous expression of PPARδ in normal and cancer gastric epithelium. Suppression of PPARδ may be one of the mechanisms underlying the chemopreventive effects of COX-2 inhibitor. © 2004 Elsevier Ireland Ltd. All rights reserved.link_to_subscribed_fulltex

Immunization with Attenuated Salmonella typhimurium Producing Catalase in Protection against Gastric Helicobacter pylori Infection in Mice

Aim. To evaluate the protective effect of live attenuated Salmonella typhimurium expressing catalase against gastric Helicobacter pylori infection in mice, and to explore the underlying mechanisms of the protective immune reaction. Materials and Methods The H. pylori catalase gene was introduced into attenuated S. typhimurium strain SL3261. C57BL/6 mice were orally immunized with the SL3261 vaccine strain expressing catalase or with SL3261 alone or phosphate-buffered saline (PBS). Mice were sacrificed 4 weeks after immunization and 5 weeks after H. pylori challenge, respectively. Results. All PBS control mice were infected. Eight of 13 (61.5%) mice immunized with the SL3261 vaccine strain and three of 14 (21%) mice immunized with SL3261 alone showed protection against H. pylori infection. Serum anti-H. pylori IgG2a levels of S. typhimurium-immunized mice were higher than those of PBS controls, both before and after H. pylori challenge, while there were no differences for IgG1 and IgA. Similarly, mRNA expression of interleukin (IL)-2, IL-12 and interferon-γin the gastric mucosa of S. typhimurium-immunized mice was significantly higher than that of PBS controls both before and after challenge. Moreover, S. typhimurium-immunized mice were characterized by marked infiltration of lymphocyte and mononuclear cells in the gastric mucosa after challenge. IL-4 and IL-10 were not detected in any of the three groups. IL-6 expression was increased in the PBS group compared with the S. typhimurium-immunized groups after challenge. Conclusions. This study demonstrates that oral immunization of mice with catalase delivered by an attenuated S. typhimurium strain offers protection against H. pylori infection. This protective immunity was mediated through a predominantly Thl-type response and was associated with post-immunization gastritis.link_to_subscribed_fulltex

Upregulation of heme oxygenase-1 and p21 confers resistance to apoptosis in human gastric cancer cells

Both heme oxygenase-1 (HO-1) and p21 WAF1/Cip1 (p21) are involved in the pathogenesis of human cancer and their functions are closely associated with apoptosis. However, how these two molecules regulate apoptosis in human gastric cancer is unknown. In this study, we studied how HO-1 and p21 were regulated in two gastric cancer cell lines, MKN-45 with wild p53 and MKN-28 with mutant p53. The cells were treated with hemin and cadmium to induce HO-1. The result showed that HO-1 protein was significantly induced by hemin and cadmium in both cells tested. Following the HO-1 expression, p21 level was also markedly induced. The cells with increased HO-1 and p21 showed obviously resistantance to apoptotic stimuli. The levels of HO-1 and p21 induced were significantly inhibited by p38 mitogen-activated protein kinase (p38 MAPK) inhibitor (SB203580) and extracellular-regulated kinase (ERK) inhibitor (PD098059). Parallel to decreased HO-1 and p21 expression, the kinase inhibitors also significantly attenuated the resistance of the cells to apoptosis. The elevated HO-1 and p21 was further found to be associated with increase activity of the nuclear NF-κB and the inhibition of NF-κB led to the block of their induction. The elevated HO-1 and p21 were also demonstrated to be related to increased cellular inhibitor of caspase inbitory protein-2 (c-IAP2) and decreased caspapse-3 activity. It was noted that the above changes observed were not different between MKN-45 and MKN-28 cells, suggesting the functions of HO-1 and p21 were irrespective of the status of p53. In conclusion, we demonstrate that the resistance to apoptosis in gastric cancer cells with elevated HO-1 and p21 is independent of p53 status in a p38 MAPK- and ERK-mediated pathway with elevated C-IAP2 and decreased caspase-3 activity and that this pathway is sensitive to the inhibition of NF-κB.link_to_subscribed_fulltex

The existence of a putative regulatory element in 3′-untranslated region of proto-oncogene HOX11's mRNA

HOX11 encodes a homeodomain-containing transcription factor which directs the development of the spleen during embryogenesis. While HOX11 expression is normally silenced through an unknown mechanism in all tissues by adulthood, the deregulation of HOX11 expression is associated with leukemia, such as T-cell acute lymphoblastic leukemia. The elucidation of regulatory elements contributing to the molecular mechanism underlying the regulation of HOX11 gene expression is of great importance. Previous reports of HOX11 regulatory elements mainly focused on the 5′-flanking region of HOX11 on the chromosome related to transcriptional control. To expand the search of putative ds-elements involved in HOX11 regulation at the post-transcriptional level, we analyzed HOX11 mRNA 3′-untranslated region (3′UTR) and found an AU-rich region. To characterize this AU-rich region, in vitro analysis of HOX11 mRNA 3′UTR was performed with human RNA-binding protein HuR, which interacts with AU-rich element (ARE) existing in the 3′UTR of many growth factors' and cytokines' mRNAs. Our results showed that the HOX11 mRNA 3′UTR can specifically bind with human HuR protein in vitro. This specific binding could be competed effectively by typical ARE containing RNA. After the deletion of the AU-rich region present in the HOX11 mRNA 3′UTR, the interaction of HOX11 mRNA 3′UTR with HuR protein was abolished. These findings suggest that HOX11 mRNA 3′UTR contains cis-acting element which shares similarity in the action pattern with ARE-HuR interactions and may involve in the post-transcriptional regulation of the HOX11 gene.link_to_subscribed_fulltex

Peroxisome proliferator-activated receptor-gamma Pro12Ala polymorphism, Helicobacter pylori infection and non-cardia gastric carcinoma in Chinese

Background: Peroxisome proliferator-activated receptor γ inhibits the growth and induces apoptosis of gastric cancer cells. A common polymorphism at codon 12 of this gene (Pro12Ala) has been shown to confer protection against diabetes and colorectal cancer. Aim: To study the association between peroxisome proliferator-activated receptor γ gene polymorphism, Helicobacter pylori infection and gastric cancer in Chinese. Methods: One hundred and four consecutive patients with non-cardia gastric adenocarcinoma and 104 matched controls were examined. Peroxisome proliferator-activated receptor γ Pro12Ala polymorphism was analysed by polymerase chain reaction-restriction fragment length polymorphism. Results: The frequency of peroxisome proliferator-activated receptor γ G (Ala12) allele was significantly higher among cancer patients (19.2%) than in control (8.7%; OR 2.5, 95% CI 1.1-5.8). While H. pylori infection was more prevalent in gastric cancer patients (OR 3.0; 95% CI 1.6-5.7), the combination of peroxisome proliferator-activated receptor γ G allele and H. pylori infection further increased the risk of gastric cancer (OR 12.8, 95% CI 3.2-50.5). The presence of the Ala12 did not increase the risk of gastric cancer in H. pylori-negative subjects. Conclusion: Our study suggests the potential association between peroxisome proliferator-activated receptor γ polymorphism and H. pylori infection in the development of non-cardia gastric cancer. © 2006 Blackwell Publishing Ltd.link_to_subscribed_fulltex

Rosiglitazone suppresses gastric carcinogenesis by up-regulating HCaRG expression

Our previous study demonstrated that PPARγ ligand rosiglitazone prevents gastric carcinogenesis in rats induced by chemical carcinogen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). In this study, we attempted to identify novel anticancer mechanisms of rosiglitazone. By examining the gene expression profiles of MNNG-induced and rosiglitazonetreated gastric cancer with Uniset Rat I Bioarray microarray, we identified a gene that showed prominent responses in the rosiglitazone-treated group. The hypertension-related, calcium-regulated gene (HCaRG) was significantly upregulated in rat gastric carcinoma of the rosiglitazone-treated group when compared with the MNNG group. We further examined HCaRG expression in human gastric cancer and found that the expression of HCaRG was down-regulated in human gastric cancerous tissue. Rosiglitazone markedly induced the expression of HCaRG in the AGS cell line. The up-regulation of HCaRG may be one of the mechanisms underlying the chemopreventive effect of rosiglitazone in gastric cancer.link_to_subscribed_fulltex

High level virion production and surface antigen expression with 1.5 copies of hepatitis B viral genome

The present study aimed to construct a 1.5X hepatitis B virus (HBV) replication system in vitro that could generate high level of HBV viruses. This system would help compare the replication capacity among the virus strains associated with high and low risk of hepatocellular carcinoma (HCC). Four strains of HBV were isolated from two HCC patients and two HBV carriers. After molecular cloning, four corresponding constructs named as HBV-1.5Xs were generated. Each of them has one and a half copies of HBV 3.2 kb genome, a 5′-end redundant sequence of 1.1 kb to nt715 and a 3′-end redundant sequence of 500 bp to nt2325 that situated after the poly (A) sequence. The HepG2 cells were transfected with the HBV-1.5Xs, and the levels of HBsAg, HBeAg and viral DNA were then detected in both the supernatant and the cells. After 24 h and 48 h of transfection, a high OD value of HBsAg of 3.5 was observed in the supernatant and also in some of the diluted cell lysate samples. The HBeAg level was relatively low in all strain samples of HBV. The log 10 values of viral loads were also determined with the cell lysate having a higher value (10-11 per ml) than that of the supernatant (6-7 per ml). The results showed that the novel HBV-1.5X system was capable to generate high level of HBV in a consistent manner. However, no significant difference was found among the replication capacities among these strains in vitro. The HBV-1.5X system may be a useful platform that assists the establishment of stable cell lines and transgenic mice for the investigation of viral pathogenesis, particularly for the various strains of HBV. © 2009 Elsevier B.V. All rights reserved.link_to_subscribed_fulltex