Putative Zinc Finger Protein Binding Sites Are Over-Represented in the Boundaries of Methylation-Resistant CpG Islands in the Human Genome

Majority of CpG dinucleotides in mammalian genomes tend to undergo DNA methylation, but most CpG islands are resistant to such epigenetic modification. Understanding about mechanisms that may lead to the methylation resistance of CpG islands is still very poor.Using the genome-scale in vivo DNA methylation data from human brain, we investigated the flanking sequence features of methylation-resistant CpG islands, and discovered that there are several over-represented putative Transcription Factor Binding Sites (TFBSs) in methylation-resistant CpG islands, and a specific group of zinc finger protein binding sites are over-represented in boundary regions ( approximately 400 bp) flanking such CpG islands. About 77% of the over-represented putative TFBSs are conserved among human, mouse and rat. We also observed the enrichment of 4 histone methylations in methylation-resistant CpG islands or their boundaries.Our results suggest a possible mechanism that certain putative zinc finger protein binding sites over-represented in the boundary regions of the methylation-resistant CpG islands may block the spreading of methylation into these islands, and those TFBSs over-represented within the islands may both reinforce the methylation blocking and promote transcription. Some histone modifications may also enhance the immunity of the CpG islands against DNA methylation by augmenting these TFs' binding. We speculate that the dynamical equilibrium between methylation spreading and blocking is likely to be responsible for the establishment and maintenance of the relatively stable DNA methylation pattern in human somatic cells

Comparison of the efficacy of lamivudine and telbivudine in the treatment of chronic hepatitis B: a systematic review

<p>Abstract</p> <p>Background</p> <p>Chronic viral hepatitis B remains a global public health concern. Currently, several drugs, such as lamivudine and telbivudine, are recommended for treatment of patients with chronic hepatitis B. However, there are no conclusive results on the comparison of the efficacy of lamivudine (LAM) and telbivudine (LdT) in the treatment of chronic hepatitis B.</p> <p>Results</p> <p>To evaluate the comparison of the efficacy of LAM and LdT in the treatment of chronic hepatitis B by a systematic review and meta-analysis of clinical trials, we searched PUBMED (from 1990 to April 2010), Web of Science (from 1990 to April 2010), EMBASE (from 1990 to April 2010), CNKI (National Knowledge Infrastructure) (from 1990 to April 2010), VIP database (from 1990 to April 2010), WANFANG database (from 1990 to April 2010), the Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Review. At the end of one-year treatment, LdT was better than LAM at the biochemical response, virological response, HBeAg loss, therapeutic response, while less than at the viral breakthrough and viral resistance, but there was no significant difference in the HBeAg seroconversion and HBsAg response. LdT was better than LAM at the HBeAg seroconversion with prolonged treatment to two years.</p> <p>Conclusions</p> <p>In summary, LdT was superior in inhibiting HBV replication and preventing drug resistance as compared to LAM for CHB patients. But LdT may cause more nonspecific adverse events and can lead to more CK elevation than LAM. It is thus recommended that the LdT could be used as an option for patients but adverse events, for example CK elevation, must be monitored.</p

Proteomic analysis of differentially expressed proteins in hepatitis B virus-related hepatocellular carcinoma tissues

<p>Abstract</p> <p>Background</p> <p>Hepatocellular carcinoma (HCC), a major cause of cancer death in China, is preceded by chronic hepatitis and liver cirrhosis (LC). Although hepatitis B virus (HBV) has been regarded as a clear etiology of human hepatocarcinogenesis, the mechanism is still needs to be further clarified. In this study, we used a proteomic approach to identify the differential expression protein profiles between HCC and the adjacent non-tumorous liver tissues.</p> <p>Methods</p> <p>Eighteen cases of HBV-related HCC including 12 cases of LC-developed HCC and 6 cases of chronic hepatitis B (CHB)-developed HCC were analyzed by two-dimensional electrophoresis (2-DE) combined with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), and the results were compared to those of paired adjacent non-tumorous liver tissues.</p> <p>Results</p> <p>A total of 17 differentially expressed proteins with diverse biological functions were identified. Among these, 10 proteins were up-regulated, whereas the other 7 proteins were down-regulated in cancerous tissues. Two proteins, c-Jun N-terminal kinase 2 and ADP/ATP carrier protein were found to be up-regulated only in CHB-developed HCC tissues. Insulin-like growth factor binding protein 2 and Rho-GTPase-activating protein 4 were down-regulated in LC-developed and CHB-developed HCC tissues, respectively. Although 11 out of these 17 proteins have been already described by previous studies, or are already known to be involved in hepatocarcinogenesis, this study revealed 6 new proteins differentially expressed in HBV-related HCC.</p> <p>Conclusion</p> <p>These findings elucidate that there are common features between CHB-developed HCC and LC-developed HCC. The identified proteins are valuable for studying the hepatocarcinogenesis, and may be potential diagnostic markers or therapeutic targets for HBV-related HCC.</p

Detection of hepatitis B surface antigen, hepatitis B core antigen, and hepatitis B virus DNA in parotid tissues

SummaryObjectiveTo examine the presence of hepatitis B surface antigen (HBsAg), hepatitis B core antigen (HBcAg), and hepatitis B virus (HBV) DNA in parotid tissues from patients with positive serum HBV markers.MethodsHBsAg and HBcAg were examined in parotid biopsy tissues from patients with suspected parotid tumor and positive serum HBV markers by immunocytochemistry, and HBV DNA was detected in parotid tissues by PCR.ResultsAmong the 22 patients with a parotid tumor, only one was pathologically confirmed as a neoplasm; all others were benign. HBsAg and HBcAg were present in parotid cells with positive rates of 45.5% (10/22) and 40.9% (9/22), respectively, with an overall positive rate of 54.5% (12/22). Of the 22 cases with serum markers of HBV infection, seven (31.8%) had both HBsAg and HBcAg in the parotid cells. HBV DNA was present in seven of the 12 samples in which hepatitis B antigen was detected (58.3%).ConclusionsHBV in saliva might originate from the infected salivary glands and the infectious saliva could transmit HBV

Cannabinoid Receptor Subtype 2 (Cb2R) Agonist Gw405833 Reduces Agonist-Induced Ca2+ Oscillations In Mouse Pancreatic Acinar Cells

Emerging evidence demonstrates that the blockade of intracellular Ca 2+ signals may protect pancreatic acinar cells against Ca 2+ overload, intracellular protease activation, and necrosis. The activation of cannabinoid receptor subtype 2 (CB 2 R) prevents acinar cell pathogenesis in animal models of acute pancreatitis. However, whether CB 2 Rs modulate intracellular Ca 2+ signals in pancreatic acinar cells is largely unknown. We evaluated the roles of CB 2 R agonist, GW405833 (GW) in agonist-induced Ca 2+ oscillations in pancreatic acinar cells using multiple experimental approaches with acute dissociated pancreatic acinar cells prepared from wild type, CB 1 R-knockout (KO), and CB 2 R-KO mice. Immunohistochemical labeling revealed that CB 2 R protein was expressed in mouse pancreatic acinar cells. Electrophysiological experiments showed that activation of CB 2 Rs by GW reduced acetylcholine (ACh)-, but not cholecystokinin (CCK)-induced Ca 2+ oscillations in a concentration-dependent manner; this inhibition was prevented by a selective CB 2 R antagonist, AM630, or was absent in CB 2 R-KO but not CB 1 R-KO mice. In addition, GW eliminated L-arginine-induced enhancement of Ca 2+ oscillations, pancreatic amylase, and pulmonary myeloperoxidase. Collectively, we provide novel evidence that activation of CB 2 Rs eliminates ACh-induced Ca 2+ oscillations and L-arginine-induced enhancement of Ca 2+ signaling in mouse pancreatic acinar cells, which suggests a potential cellular mechanism of CB 2 R-mediated protection in acute pancreatitis

A Hepatic Protein, Fetuin-A, Occupies a Protective Role in Lethal Systemic Inflammation

A liver-derived protein, fetuin-A, was first purified from calf fetal serum in 1944, but its potential role in lethal systemic inflammation was previously unknown. This study aims to delineate the molecular mechanisms underlying the regulation of hepatic fetuin-A expression during lethal systemic inflammation (LSI), and investigated whether alterations of fetuin-A levels affect animal survival, and influence systemic accumulation of a late mediator, HMGB1.LSI was induced by endotoxemia or cecal ligation and puncture (CLP) in fetuin-A knock-out or wild-type mice, and animal survival rates were compared. Murine peritoneal macrophages were challenged with exogenous (endotoxin) or endogenous (IFN-γ) stimuli in the absence or presence of fetuin-A, and HMGB1 expression and release was assessed. Circulating fetuin-A levels were decreased in a time-dependent manner, starting between 26 h, reaching a nadir around 24-48 h, and returning towards base-line approximately 72 h post onset of endotoxemia or sepsis. These dynamic changes were mirrored by an early cytokine IFN-γ-mediated inhibition (up to 50-70%) of hepatic fetuin-A expression. Disruption of fetuin-A expression rendered animals more susceptible to LSI, whereas supplementation of fetuin-A (20-100 mg/kg) dose-dependently increased animal survival rates. The protection was associated with a significant reduction in systemic HMGB1 accumulation in vivo, and parallel inhibition of IFN-γ- or LPS-induced HMGB1 release in vitro.These experimental data suggest that fetuin-A is protective against lethal systemic inflammation partly by inhibiting active HMGB1 release

Genetic and phenotype changes following in vitro interactions between Helicobacter pylori strains

Background:  The purpose of the present paper was to determine whether in vitro interaction between different Helicobacter pylori strains leads to changes in antibiotic susceptibility, cagA, vacAM2 and DNA fingerprint patterns. Methods:  Three H. pylori strains with known antibiotic susceptibility, cagA, vacAM2 status and polymerase chain reaction–random amplified polymorphic DNA (PCR-RAPD) fingerprint analysis were suspended in phosphate buffered saline (PBS pH 7.0), and the suspensions were mixed in equal proportion prior to culture on chocolate agar plates. Subcultures were performed five times every 3 days. As a control, each of the three strains was also subcultured separately. Antibiotic susceptibility testing, PCR for cagA, vacAM2 and PCR-RAPD analysis were done. Results:  Surviving strain of the two H. pylori strains in each combination demonstrated change in resistance to both antibiotics but no change in sensitivity. CagA status of the surviving strain varied as compared to the vacAM2 status, which did not change. The PCR-RAPD fingerprint showed unique band pattern. Conclusion:  DNA transformation follows in vitro interaction. Helicobacter pylori strain with antibiotic resistance is likely to dominate in such in vitro interactions between various strains

Antibiotic susceptibility of Helicobacter pylori in the Chinese population

Aim: To assess antibiotic susceptibility of Helicobacter pylori (H. pylori) strains to metronidazole, clarithromycin and tetracycline in the Chinese population, and to test the stability of antibiotic resistance in H. pylori 1 year after storage at -80°C. Methods: Fifty H. pylori strains isolated from patients with peptic ulcer disease were recovered from storage at -80°C. Susceptibility of these strains to metronidazole, clarithromycin and tetracycline was determined by using validated disk diffusion tests, which was repeated 1 year after storage at -80°C. The DNA profiles of each strain were determined by using the polymerase chain reaction-based–random amplified polymorphic DNA fingerprinting technique (PCR-RAPD). This was repeated if any change in antibiotic susceptibility pattern was noticed. Results: The resistance rate was 50% to metronidazole and 8% to clarithromycin. None of the strains was resistant to tetracycline. A dual resistance to metronidazole and clarithromycin was demonstrated in three H. pylori strains. The antibiotic susceptibility test reproduced itself in 92% (36 of 39) of the strains 1 year later; the three strains with dual resistance exhibited susceptibility to both antibiotics. Variation in antibiotic susceptibility pattern in the three H. pylori strains was associated with change in the RAPD fingerprint. Conclusion: The prevalence of resistance in H. pylori is high to metronidazole but low to clarithromycin in the Chinese population. The disk diffusion test appears to be a simple and reliable test, while antibiotic resistance in some H. pylori strains may disappear after long-term storage at -80°C. © 2001 Blackwell Science Asia Pty Ltd