Continuous treatment with lamivudine delays clinical progression in patients with chronic hepatitis B and advanced fibrosis or cirrhosis by significantly reducing the incidence of hepatic decompensation and the risk of hepatocellular carcinoma.

No abstract

Iron uptake systems were the genes in K. pneumoniae that were highly up-regulated in response to sera. Although there are multiple iron transporter systems in NTUH-K2044, a mutation in all 3 loci (irp2, iuc, and iroA) is necessary to decrease virulence. The tonB mutant is a potential vaccine candidate because it can induce a significant protective immune response against challenge with a wild-type strain.

Genomic heterogeneity has been shown to be associated with Klebsiella pneumoniae strains causing pyogenic liver abscesses (PLA) and metastatic infections. In order to explore the mechanism responsible for genomic heterogeneity in K. pneumoniae, we compared the complete genomic sequences of strains NTUH-K2044 and MGH78578. An ϳ76-kbp DNA fragment located adjacent to an asparagine (asn) tRNA gene was present in NTUH-K2044 but not in MGH78578. This fragment could be divided into three regions with different functions, and structurally it resembled a functional integrative and conjugative element (ICE), ICEEc1, in Escherichia coli. The 5 region of this fragment contained genes similar to a high-pathogenicity island (HPI) of Yersinia pestis and Yersinia pseudotuberculosis. The middle region was similar to part of a large plasmid in K. pneumoniae, and the 3 region contained genes responsible for DNA conjugative transfer. Therefore, this DNA fragment was designated ICEKp1. Precise excision and extrachromosomal circularization of ICEKp1 were detected in K. pneumoniae wild-type strain NTUH-K2044. ICEKp1 could integrate into the asn tRNA loci of the chromosome of another K. pneumoniae isolate. The prevalence of ICEKp1 was higher in PLA strains (38 of 42 strains) than in non-tissue-invasive strains (5 of 32 strains). Therefore, ICEKp1 may contribute to the transmission of the HPI and result in K. pneumoniae PLA infection-associated genomic heterogeneity.

Percutaneous ethanol injection therapy appears to be as safe and effective as resection, and both treatments can be considered first-line options for small hepatocellular carcinoma.

Klebsiella pneumoniae liver abscess with metastatic complications is an emerging infectious disease in Taiwan. To identify genes associated with liver infection, we used a DNA microarray to compare the transcriptional profiles of three strains causing liver abscess and three strains not associated with liver infection. There were 13 clones that showed higher RNA expression levels in the three liver infection strains, and 3 of these 13 clones contained a region that was absent in MGH 78578. Sequencing of the clones revealed the replacement of 149 bp of MGH 78578 with a 21,745-bp fragment in a liver infection strain, NTUH-K2044. This 21,745-bp fragment contained 19 open reading frames, 14 of which were proven to be associated with allantoin metabolism. The K2044 (⌬allS) mutant showed a significant decrease of virulence in intragastric inoculation of BALB/c mice, and the prevalence of this chromosomal region was significantly higher in strains associated with liver abscess than in those that were not (19 or 32 versus 2 of 94; P ‫؍‬ 0.0001 [ 2 test]). Therefore, the 22-kb region may play a role in K. pneumoniae liver infection and serve as a marker for rapid identification.

To understand the RNA expression in response to acid stress of Helicobacter pylori in genomic scale, a microarray membrane containing 1,534 open reading frames (ORFs) from strain 26695 was used. Total RNAs of H. pylori under growth conditions of pH 7.2 and 5.5 were extracted, reverse transcribed into cDNA, and labeled with biotin. Each microarray membrane was hybridized with cDNA probe from the same strain under two different pH conditions and developed by a catalyzed reporter deposition method. Gene expression of all ORFs was measured by densitometry. Among the 1,534 ORFs, 53 ORFs were highly expressed (м30% of rRNA control in densitometry ratios). There were 445 ORFs which were stably expressed (<30% of rRNA in densitometry) under both pH conditions without significant variation. A total of 80 ORFs had significantly increased expression levels at low pH, while expressions of 4 ORFs were suppressed under acidic condition. The remaining 952 ORFs were not detectable under either pH condition. These data were highly reproducible and comparable to those obtained by the RNA slot blot method. Our results suggest that microarray can be used in monitoring prokaryotic gene expression in genomic scale.Helicobacter pylori is the causative agent of chronic superficial gastritis in humans, and the presence of this organism increases risk of development of peptic ulcer disease and adenocarcinoma and mucosa-associated lymphoid tissue lymphoma of the distal stomach (2,3,10,19,21). The mechanism of pathogenesis remains largely unknown. The ability to survive under acidic stomach conditions might be one of the virulence mechanisms. Monitoring the response of H. pylori genes during acid stress may be helpful to understand the pathogenesis.Expression of many bacterial genes is induced in response to environmental stimuli (17). For technical reasons, only a limited subset of genes could be simultaneously analyzed until recently. Differential display of subsets of mRNA on a sequencing gel allows a broad search for expression differences (11, 15), but the method has been difficult to standardize. An rRNA subtraction approach has been used to identify differentially expressed genes in Mycobacterium avium (23); however, removal of rRNA by subtraction caused loss of mRNA. Chuang et al. (6) have analyzed differentially expressed genes in Escherichia coli by a method based on hybridization to spot overlapping clones. This method required subcloning and subsequent sequencing for the identification of relevant genes.Recently, a system for monitoring of a large number of gene expressions has been developed in eukaryotes using DNA microarray (5, 23, 24) or oligonucleotide microarray (16,22,29). Labeled cDNA, or in vitro-transcribed mRNA, was hybridized to the high-density probe microarray. Microarrays are able to analyze the expression of hundreds of genes in a single hybridization experiment. DNA array has also been recently adopted for monitoring gene expressions in bacteria. Unfortunately, since bacterial mRNA could not be separated from r...

Our results suggest that chromosomal heterogeneity is present in tissue-invasive K. pneumoniae strains. A genotype containing all 3 regions is strongly associated with PLA and metastatic infection. These regions may serve as convenient markers for the rapid diagnosis of emergent tissue-invasive strains.