Incidence and clinical presentation of posttransfusion TT virus infection in prospectively followed transfusion recipients: emphasis on its relevance to hepatitis

BACKGROUND

A novel transfusion-transmissible human DNA virus, TT virus (TTV), has been discovered recently. An attempt was made to determine the incidence and clinical outcome of TTV infection in recipients of blood transfusion.

STUDY DESIGN AND METHODS

Serial serum samples collected as part of a prospective study of posttransfusion hepatitis were examined for TTV DNA by a nested PCR assay.

RESULTS

Among 150 adults undergoing cardiac surgery, posttransfusion specimens from 59 individuals were positive for TTV DNA. Pretransfusion sera were found to be positive in 13 of these individuals. Therefore, 46 (33.6%) of the 137 previously uninfected patients developed new TTV viremia after transfusion. Among the 46 patients, 3 were coinfected with HCV, 5 were coinfected with HGV, and 38 were infected with TTV alone. No apparent symptoms or signs were noted in the 38 patients infected by TTV alone or the 5 infected with HGV plus TTV. The average peak serum ALT activity was 31 IU per L, with persistently normal levels in 34 of the 38 patients with TTV infection alone. In 8 other patients who subsequently developed well-documented non-A-G hepatitis, 3 were positive for TTV (3/8 vs. 46/137, p = 0.8). In 12 patients followed for more than 1 year, TTV viremia persisted in every case.

CONCLUSION

In this population, TTV is transmitted by transfusion to approximately 30 percent of patients who undergo cardiac surgery. Most of the infections appear to become persistent. Despite the high prevalence rate, TTV does not appear to cause hepatitis on its own.

Strong association of antiepithelial cell antibodies with HLA-DR3 or DR7 phenotype in patients with recurrent oral ulcers

BACKGROUND

Previous studies showed that antiepithelial cell antibodies (anti-ECA) were present in 71% (15/21) of patients with recurrent oral ulcers (ROU) and that there was a strong association of human leukocyte antigen (HLA)-DRw9 with ROU in Chinese patients. In this study, we assessed anti-ECA in a larger group of Chinese patients with ROU (n = 88) in order to further investigate the association of anti-ECA with HLA-DR and -DQ antigens.

METHODS

The anti-ECA in the sera of ROU patients were detected by an indirect immunofluorescence technique with rat esophagus as the substrate, and the HLA-DR and -DQ antigens in ROU patients were typed by a standard microcytotoxicity assay using Terasaki's oriental tray.

RESULTS

The rate of anti-ECA positivity was significantly higher (p < 0.0001) in ROU patients (68%) than in healthy control subjects (0%). Furthermore, the rate of anti-ECA positivity in patients with major or minor oral ulcers (72%) was significantly higher (29%) than that in patients with herpetiform ulcers (p < 0.05). There was a significant increase in the frequency of DR3 or DR7 antigen expression (p < 0.0001, pc [p corrected] < 0.001, relative risk [RR] = 4.3, etiologic fraction = 0.41) in anti-ECA-positive ROU patients compared with the corresponding frequencies in healthy control subjects. There was also a significant increase in the frequency of DR7 or DRw9 antigen expression (p < 0.005, pc < 0.05, RR = 4.7, etiologic fraction = 0.45) compared to healthy controls.

CONCLUSIONS

Because only DR3 or DR7 antigen occurred more frequently in anti-ECA-positive than in anti-ECA-negative ROU patients (p < 0.0007, pc < 0.05, RR = 19.6, etiologic fraction = 0.51), we concluded that the gene coding for DR3 or DR7 antigen may contribute to the presence of anti-ECA in Chinese patients with ROU.

Association of HLA-te22 antigen with anti-nuclear antibodies in Chinese patients with erosive oral lichen planus

The purpose of this study was to determine the frequencies of the presence of serum anti-nuclear antibodies (ANA) and smooth muscle antibodies (SMA) in 76 patients with oral lichen planus (OLP), in 77 patients with other oral mucosal diseases, and in 41 healthy control subjects. HLA phenotypes in some of the patients with OLP and recurrent aphthous ulcers (RAU) were determined to show whether there was an association of HLA antigens with the presence of autoantibodies. Indirect immunofluorescence techniques with mouse liver or stomach as the substrate were used to detect the serum ANA or SMA, respectively. The B lymphocytes isolated from peripheral blood were used for HLA typing by means of a standard microcytotoxicity assay. We found that the positive rate of serum ANA in patients with OLP (29%, p < 0.01), especially in patients with erosive OLP (34%, p < 0.001), was significantly higher than that in the normal control subjects (5%). The frequency of serum SMA in patients with OLP (20%, p < 0.01), in patients with RAU (17%, p < 0.01), or in patients with oral squamous cell carcinomas (41%, p < 0.001) was also significantly higher than that in normal control individuals (0%). In the erosive OLP group, the HLA-Te22 antigen occurred more frequently in patients with positive ANA (75%, p < 0.05) than in those with negative ANA (25%). We conclude that there is an association of HLA-Te22 antigen with ANA in Chinese patients with erosive OLP.

Expression of p53 protein in oral submucous fibrosis, oral epithelial hyperkeratosis, and oral epithelial dysplasia

BACKGROUND AND PURPOSE

In our previous study, positive p53 staining was observed in 47 of 81 (58%) cases of oral squamous cell carcinoma associated with areca quid (AQ) chewing and cigarette smoking. This study looked for expression of p53 protein in premalignant oral lesions in patients who chewed AQ or smoked cigarettes, or both.

METHODS

Expression of p53 protein was examined in histologic sections of oral submucous fibrosis (OSF, n = 50), epithelial hyperkeratosis (EH, n = 10), epithelial dysplasia (ED, n = 10), and normal oral mucosa (NOM, n = 10) with antibodies against p53 protein using an immunoperoxidase technique.

RESULTS

Positive p53 staining was observed in 30 (60%) OSF specimens, four (40%) EH specimens, seven (70%) ED specimens, and none of the NOM specimens. Only four (8%) of the OSF specimens and none of the EH specimens had more than 25% p53-positive keratinocytes. However, in four (40%) of the ED specimens, more than 50% of the keratinocytes were p53-positive. The degree of p53 staining increased with the morphologic transformation of normal-appearing epithelial cells into dysplastic epithelial cells. There was no significant correlation between expression of p53 in OSF epithelium and the clinicohistologic parameters of patients with OSF.

CONCLUSIONS

These results demonstrate that p53 is often present in precancerous lesions of patients who chew AQ and smoke cigarettes. We suggest that p53 may play a role in dysplastic cell transformation in premalignant oral lesions.

Effects of continuous calcitonin treatment on osteoclasts derived from cocultures of mouse marrow stromal and spleen cells

BACKGROUND

Continuous calcitonin (CT) treatment for bone diseases associated with increased bone resorption may be followed by prolonged depression of osteoclast response to CT. The mechanisms of this "escape" phenomenon remain unclear.

METHODS

We examined the effects of continuous CT treatment on cell formation, calcitonin receptor (CTR) expression, response to CT, and bone resorption of osteoclasts in a coculture of mouse marrow stromal and spleen cells in the presence of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. Cells were cocultured and treated with salmon CT (sCT) for 7, 14, or 21 days. The effects of continuous CT treatment on osteoclast formation was determined by quantitation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs). CTR expression in osteoclasts was determined by binding of [125I]sCT in autoradiography. Bone resorption and CT responsiveness were assessed by examining the formation of resorption pits and by enumerating osteoclast reattachment on dentine slices after sCT rechallenge.

RESULTS

TRAP-positive MNCs appeared in cocultures treated with sCT and were similar in number and morphology to those in control cultures, regardless of the concentration and duration of sCT treatment. A decrease in CTR expression was identified as a loss of silver grains from the TRAP-positive cells in cocultures receiving sCT treatment for 14 or 21 days. Partial recovery of CTR expression in TRAP-positive cells was evident in cocultures treated with sCT for only the first 7 days of coculture. TRAP-positive MNCs in cocultures treated with sCT for 14 or 21 days were resistant to the rechallenge with sCT. They attached to dentine slices and caused numerous resorption pits compared with control cells and cells treated with sCT for the first 7 days of coculture (p < 0.01).

CONCLUSION

These findings suggest that the escape phenomenon that develops after continuous CT treatment may be due, at least in part to: 1) loss of responsiveness to CT in existing osteoclasts; and 2) development of new osteoclasts that are CTR-deficient and, therefore, refractory to CT rechallenge.

[Induction of osteointegration of rabbit mandibular central fissure with guided tissue regeneration]

OBJECTIVE:To observe the effect of guided tissue regeneration (GTR) on induction of ostegenesis in developmental bone clefts,and provide a basis for the use of GTR to repair bony clefts in cleft lip and palate patients.METHODS:The e-PTFE membrane was placed on the labial and lingual sides of the rabbit mandibular central fissure.A radiological and pathological study was performed to determine the healing of the fissure integration.RESULTS:The results showed that the bony cleft was completely integrated 4 weeks after placement of the barrier membrane.CONCLUSION:GTR is an effective approach to reconstruct bony cleft,and is likely to be used in repair of alveolar cleft and cleft palate.

Loss of heterozygosity at chromosome 13q in hepatocellular carcinoma: identification of three independent regions

Loss of heterozygosity (LOH) on chromosome 13q is one of the most common genetic alterations in hepatocellular carcinoma (HCC) and might be involved in liver cancer development through inactivation of tumour suppressor genes. In order to narrow down the region of 13q loss, we examined the pattern of loss of heterozygosity (LOH) in tumours from 88 HCC patients, using 18 microsatellite markers on 13q. Thirty-eight of the 88 tumours (43%) showed LOH for at least one marker. Of these, two tumours (5%) showed 13q whole arm allelic loss, while the remaining 36 tumours (95%) had partial allelic loss. The LOH pattern defined by the 36 tumours suggested the existence of at least three different smallest common deleted regions which might be involved in the carcinogenesis of HCC. The first, the most centromeric in the 13q12.3 is, close to the BRCA2 gene, defined by D13S171; the second, the most telomeric region in the 13q31-32 band, is defined by D13S154 and D13S157; the third, the intermediate region at 13q14.3, which is near the RB gene, is defined by loci D13S268. The rate of LOH at 13q31-32 was significantly higher in Hepatitis B-surface antigen (HBsAg)-positive patients than HBsAg-negative HCC patients, pointing to a candidate gene related to the development of HBsAg-positive HCCs.

The role of gastric acid and Helicobacter pylori in the natural course of duodenal ulcer

This study was conducted using roxatidine acetate or Mylanta combined with metronidazole and amoxicillin to evaluate the role of acid and Helicobacter pylori in the natural course of the duodenal ulcer. Eighty-three patients with H. pylori positive duodenal ulcers were randomly allocated into one of four treatment groups. Group A: roxatidine 75 mg hs for 8 weeks; Group B: the same as group A + metronidazole 250 mg and amoxicillin 250 mg qid for 1 week on the 3rd week; Group C: Mylanta (combined hydroxide of magnesium and aluminum) 20 ml qid for 8 weeks; Group D: the same as group C + metronidazole 250 mg and amoxicillin 250 mg qid for 1 week on the 3rd week. Repeated endoscopies were performed on the 8th week post the initial treatment and the sixth and 12th month post the termination of treatment, or, at the earliest recurrence of symptoms. Eradication of H. pylori was considered to be successful if the culture, histology and CLO test all showed negative. The ulcer healing rates of Groups A, B, C and D were 95%, 100%, 61% and 86%, respectively, with a significant difference between A and C. The eradication rates of groups B and D were 81% and 62%, respectively, without any significant difference. The 12 months cumulative ulcer recurrence rates were 72%, 15%, 80% and 22%, respectively, with a significant difference between each paired groups with and without antibiotics. In conclusions, roxatidine is effective in the healing of duodenal ulcer. One-week roxatidine-based triple therapy is powerful in the eradication of H. pylori. Potent acid suppression is sufficient to heal the duodenal ulcer. Eradication of H. pylori can potentiate ulcer healing under insufficient acid suppression. A causal role for H. pylori in recurrent duodenal ulcer is strongly supported by a much lower recurrence of ulcer in H. pylori free patients.

New techniques for DNA sequence classification

DNA sequence classification is the activity of determining whether or not an unlabeled sequence S belongs to an existing class C. This paper proposes two new techniques for DNA sequence classification. The first technique works by comparing the unlabeled sequence S with a group of active motifs discovered from the elements of C and by distinction with elements outside of C. The second technique generates and matches gapped fingerprints of S with elements of C. Experimental results obtained by running these algorithms on long and well conserved Alu sequences demonstrate the good performance of the presented methods compared with FASTA. When applied to less conserved and relatively short functional sites such as splice-junctions, a variation of the second technique combining fingerprinting with consensus sequence analysis gives better results than the current classifiers employing text compression and machine learning algorithms.

Isolation of a Helicobacter pylori protein, FldA, associated with mucosa-associated lymphoid tissue lymphoma of the stomach

BACKGROUND & AIMS

The growth of gastric mucosa-associated lymphoid tissue lymphoma (MALToma) seems to depend on the stimulation of Helicobacter pylori. We attempted to identify specific antigen(s) from H. pylori strains associated with MALToma.

METHODS

Membranous and secreted proteins of H. pylori were compared on sodium dodecyl sulfate-polyacrylamide gel electrophoresis by Western blot using sera from patients with MALToma.

RESULTS

A 19-kilodalton protein was seen in all strains isolated from patients with MALToma but uncommonly in other strains. The protein was purified and sequenced. Amino acid sequence comparison showed it was an FldA homologue, a putative flavodoxin protein. DNA sequencing in 26 strains revealed that a nucleotide G insertion at position 481 of the fldA gene was more frequently observed in strains associated with MALToma than other strains (9/9 vs. 6/17; P = 0.002). The mutation caused a short truncation. A recombinant protein with this truncation was expressed and tested. Sera of 12 (70.6%) of 17 patients with MALToma were positive for the antibody to the recombinant protein, and 7 (16.7%) of 42 control patients were positive (12/17 vs. 7/42; P < 0.0001).

CONCLUSIONS

Truncated FldA of H. pylori is associated with gastric MALToma. It may be involved in the pathogenesis of gastric MALToma. Antibody to this antigen could be used as a serological marker of the disease.

Loss of heterozygosity and microsatellite instability in hepatocellular carcinoma in Taiwan

Elucidation of the basic genetic changes of human hepatocellular carcinoma is important for the understanding and treatment of this cancer. We used microsatellite polymorphism markers to study 30 cases of hepatocellular carcinoma (34 tumours) on all human chromosomes. DNA from 34 pairs of hepatocellular carcinomas and corresponding non-tumour parts was prepared. Loss of heterozygosity (LOH) and microsatellite instability on 23 chromosomes were investigated by 231 sets of microsatellite markers. More than 20% LOH was shown for loci on 16q (47.1%), 13q (32.4%), 17p (32.4%), 5q (26.5%), 11p (23.5%) and 9p (20.6%). The commonly affected regions were mapped to 16q12.1, 16q12.2, 16q24, 13q12.1-32, 17p13, 5q32, 5q34, 5q3, 11p15, 11q23-24 and 9p21. Hepatitis B virus carriers had a significantly higher frequency of LOH on chromosomes 5q, 11p and 16q. Furthermore, larger tumour size tended to have higher frequency of LOH at D16S409 locus (16q12.1). Microsatellte instability was only found in 12 of 231 markers and the frequency is very low. These data suggest that the chromosomes 16q, 13q, 17p, 5q, 11p and 9p might participate in hepatocarcinogenesis. However, microsatellite instability might play little role in the development of this cancer in Taiwan.

Chromosomal abnormality in hepatocellular carcinoma by comparative genomic hybridisation in Taiwan

The elucidation of the genetic changes of hepatocellular carcinoma (HCC) is very important for understanding the molecular mechanism of liver carcinogenesis. In order to identify the gains or losses in DNA sequence copy number in HCC, we used comparative genomic hybridisation to study 40 cases (44 tumours) of HCC. Tumour DNA and DNA from non-neoplastic liver tissue were labelled with different fluorochromes and then simultaneously hybridised to normal metaphase spread chromosomes. An image acquisition system was used to quantitate signal intensities contributed by tumour and reference DNA along the entire length of each chromosome. Regions of amplification and deletion were demonstrated as quantitative alterations. Losses were prevalent on chromosome regions 16q (43%), 17p (20%), 13q (20%), 4q (15%) and 8p (15%). Gains frequently occurred on 8q (30%), 1q (20%), 6p (20%) and 17q (18%). Hepatitis B virus carriers had a significantly higher frequency of losses on chromosome 16q. Furthermore, the minimal region of losses was narrowed down to 16q11-q22. This study confirms the presence of previously known chromosomal aberrations in HCC and highlights a new significant correlation between losses on chromosome 16q and hepatitis B virus carriers.

Expression of p53 protein correlates with decreased survival in patients with areca quid chewing and smoking-associated oral squamous cell carcinomas in Taiwan

Expression of p53 protein was examined in oral squamous cell carcinoma (SCC) from patients who were areca quid (AQ) chewers and/or tobacco smokers, using anti-p53 antibodies with an immunoperoxidase technique. Positive p53 stain was observed in 47 of 81 (58%) cases of oral SCC. p53 overexpression was found to be higher in patients without AQ chewing and smoking habits than in patients with these two habits (80% vs 52%, P=0.076). No significant correlation was found between p53 expression and the patients' age, sex, cancer location, clinical staging, primary tumor TNM status, or histological differentiation of SCC. The Kaplan-Meier analysis showed that the prognosis for patients with p53-negative tumors was significantly better than that for patients with p53-positive tumors (P<0.05). A significant correlation was also observed between positive lymph node status and poor prognosis (P<0.05). These results suggest that p53 may serve as an adjuvant marker of poor survival in patients with oral SCCs in Taiwan.

Genetics of vitamin D 1alpha-hydroxylase deficiency in 17 families

Vitamin D-dependent rickets type I (VDDR-I), also known as pseudo-vitamin D-deficiency rickets, appears to result from deficiency of renal vitamin D 1alpha-hydroxylase activity. Prior work has shown that the affected gene lies on 12q13.3. We recently cloned the cDNA and gene for this enzyme, mitochondrial P450c1alpha, and we and others have found mutations in its gene in a few patients. To determine whether all patients with VDDR-I have mutations in P450c1alpha, we have analyzed the P450c1alpha gene in 19 individuals from 17 families representing various ethnic groups. The whole gene was PCR amplified and subjected to direct sequencing; candidate mutations were confirmed by repeat PCR of the relevant exon from genomic DNA from the patients and their parents. Microsatellite haplotyping with the markers D12S90, D12S305, and D12S104 was also done in all families. All patients had P450c1alpha mutations on both alleles. In the French Canadian population, among whom VDDR-I is common, 9 of 10 alleles bore the haplotype 4-7-1 and carried the mutation 958DeltaG. This haplotype and mutation were also seen in two other families and are easily identified because the mutation ablates a TaiI/MaeII site. Six families of widely divergent ethnic backgrounds carried a 7-bp duplication in association with four different microsatellite haplotypes, indicating a mutational hot spot. We found 14 different mutations, including 7 amino acid replacement mutations. When these missense mutations were analyzed by expressing the mutant enzyme in mouse Leydig MA-10 cells and assaying 1alpha-hydroxylase activity, none retained detectable 1alpha-hydroxylase activity. These studies show that most if not all patients with VDDR-I have severe mutations in P450c1alpha, and hence the disease should be referred to as "1alpha-hydroxylase deficiency."

Helicobacter pylori-seronegative gastric carcinoma: a subset of gastric carcinoma with distinct clinicopathologic features

BACKGROUND/AIMS

The frequent association of gastric atrophy and intestinal metaplasia in gastric cancer (GC) might preclude serologic detection of Helicobacter pylori (H. pylori) infection in GC. By using polymerase chain reaction (PCR) for detection, we would like to determine whether there exists a subset of genuinely H. pylori-negative GC patients, and whether they have distinct clinicopathologic features or not.

METHODOLOGY

IgG antibodies against H. pylori were determined by ELISA in sera, and H. pylori DNA was detected by PCR in resected gastric specimens from 160 GC patients. Clinicopathologic characteristics were then compared among group A: seropositive, group B: seronegative but PCR-positive, and group C: seronegative and PCR-negative.

RESULTS

Among 160 patients, 105 (65.6%) were classified as group A, 25 (15.6%) as group B, and 30 (18.8%) as group C. Group B patients were older and had more infiltrative tumor growth than group A. Group C had a significantly higher frequency of female predominance, and their cancers were of a more cardiac location and of the diffuse histologic subtype than those of groups A and B.

CONCLUSIONS

A significant portion (15.6%) was negative to ELISA but positive to PCR, suggesting that older ages and infiltrative tumor growth might preclude serologic detection of H. pylori infection by impairing humoral responses. Although the majority (81.2%) has a strong association with H. pylori infection, an H. pylori-negative subset indeed exists and has distinct clinicopathologic features, supporting that causes other than H. pylori infection are involved in GC carcinogenesis.

Infrequent mutations and no methylation of CDKN2A (P16/MTS1) and CDKN2B (p15/MTS2) in hepatocellular carcinoma in Taiwan

CDKN2A (p16INK4A/MTS1) and CDKN2B (p15INK4B/MTS2) have recently been shown to be potent inhibitors of the cyclin D/cyclin-dependent kinase-4 complex. Both genes are candidates for the putative tumour suppressor genes located at chromosome 9p21 and are frequently inactivated in many human cancers through homozygous deletion. More recently, another reported pathway of inactivation involves loss of transcription associated with de novo methylation of the 5' CpG island of p16/MTS1 and p15/MTS2 in human cancers. We examined a total of 34 tumours from 30 hepatocellular carcinoma (HCC) patients for deletion, mutation and DNA methylation of these two genes by polymerase chain reaction (PCR) amplification, sequence analysis and Southern blot. Homozygous deletions of P16/MTS1 exon 1 were only identified in 1 of 30 cases (3%). Homozygous deletions of p15 exon 1 or exon 2 were found in 7 of 30 cases (13%). Automated sequencing analysis of p16 exon 1 and 2 and p15 exon 1 and 2 failed to demonstrate mutations in either p16 or p15 in any of these specimens. No aberrant 5' CpG island hypermethylation of p16 or p15 was found in any of the primary tumours by Southern blot. These data suggest that the p16/MTS1 gene has a limited role in HCC. However, deletions of the p15/MTS2 gene are found in 13% HCC and might be involved in a subset of HCC.

Antibodies to E2 protein of hepatitis G virus in children: different responses according to age at infection

OBJECTIVES

To study viral persistence and antibody responses after hepatitis G virus (HGV) infection in children of various ages.

STUDY DESIGN

We performed an enzyme immunoassay for antibodies to E2 protein (anti-E2) of HGV and reverse-transcription polymerase chain reaction assay for HGV RNA on serum samples.

RESULTS

Of 28 infants born to HGV RNA-positive mothers, 17 were found to be positive for HGV RNA. None were positive for anti-E2. All 17 infected infants continued to have viremia except 1 who converted to HGV RNA-negative status at 24 months. Six infants had mild elevations of alanine aminotransferase levels (5 HGV-positive and 1 HGV-negative). An additional 14 HGV-infected children (aged 6 months to 14 years) with posttransfusion HGV infection were tested for anti-E2 3 months and 12 months after blood transfusion. None of the HGV RNA-positive serum samples were positive for anti-E2; however, 4 of the 8 children with resolving HGV infection were positive for anti-E2 1 year later.

CONCLUSIONS

Mother-to-infant transmission of HGV resulted in a high viral persistence rate and lack of immune responses to HGV. In contrast, anti-E2 appeared in children who recovered from posttransfusion HGV infection. Mode of transmission and age at infection may be important factors in determining persistent HGV infection and defective immune response to HGV.

Optimized conditions for growth and fermentation of Helicobacter pylori

This study attempted to optimize the growth conditions of Helicobacter pylori by comparing the growth of H. pylori in an anaerobic jar and an incubator. It was found that the primary isolation rate of H. pylori from gastric biopsies was higher in an anaerobic incubator (28/30) than in an anaerobic jar (21/30). In addition, growth rate in the subsequent passage was also higher in an incubator. By comparing different supplements in the liquid media, it was found that most strains grew best in Brucella broth containing 5% fetal calf serum, and some strains grew well with the supplement of 0.2% of beta-cyclodextrin. A large scale culture using a bioreactor indicated that a defoaming agent, polypropylenglycol, profoundly inhibited the growth of H. pylori. However, fermentation could be successfully performed by continuously infusing mixed airs composed of 5% O2, 10% CO2 and 85% N2. Moreover, the production of secreted proteins of H. pylori strains grown in the bioreactor was the same as that in an anaerobic jar. Results presented herein can be used to further optimize conditions for enhancing the growth of H. pylori.

Molecular mechanisms of clarithromycin resistance in Helicobacter pylori

Combination antibiotic therapy for Helicobacter pylori has now become the standard means of treating peptic ulcer diseases. Clarithromycin is a newly adopted antibiotic for H. pylori eradication. However, resistance to clarithromycin reduces the efficacy of clarithromycin-containing regimens. We explored mechanisms of clarithromycin resistance by evaluating H. pylori for macrolide resistance mechanisms reported in H. pylori and other bacteria. Degenerate polymerase chain reaction analysis of the H. pylori genome failed to yield products homologous to methylase, a drug inactivation enzyme, or efflux pumps. Clarithromycin selection in Escherichia coliNM522, transformed with an expression library that was constructed with genomic DNA from a clarithromycin-resistant strain of H. pylori, revealed six clones that conferred clarithromycin resistance consistently after retransformation. Southern hybridization and DNA sequencing revealed that four of the six clones contained the same locus. Comparison of DNA and amino acid sequences showed that the 1.3-kb DNA fragment had significant homology to the 3-oxoadipate CoA-transferase subunit A (yxjD) and subunit B (yxjE) of Bacillus subtilis. However, the clarithromycin inactivation assay and knockout mutation analysis showed that the gene increased clarithromycin resistance in E. coli, but not in H. pylori. In contrast, sequencing of the 23S rRNA gene in six clarithromycin-resistant H. pylori clinical isolates revealed an A to G transitional mutation at position 2515 of the 23S rRNA gene in all isolates. Natural transformation with the 23S rRNA gene from resistant strains conferred clarithromycin resistance in clarithromycin-sensitive strains. We conclude that the 23S rRNA mutation is sufficient to confer clarithromycin resistance and that it is the major mechanism of clarithromycin resistance in H. pylori.

Identification of cell types responsible for bone resorption in rheumatoid arthritis and juvenile rheumatoid arthritis

Focal resorption of bone at the bone-pannus interface is common in rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA) and can result in significant morbidity. However, the specific cellular and hormonal mechanisms involved in this process are not well established. We examined tissue sections from areas of bone erosion in patients with RA and JRA. Multinucleated cells (MNCs) were present in resorption lacunae in areas of calcified cartilage and in subchondral bone immediately adjacent to calcified cartilage, as previously described. mRNA for the calcitonin receptor (CTR) was localized to these MNCs in bone resorption lacunae, a finding that definitively identifies these cells as osteoclasts. These MNCs were also positive for tartrate-resistant acid phosphatase (TRAP) mRNA and TRAP enzymatic activity. Occasional mononuclear cells on the bone surface were also CTR positive. Mononuclear cells and MNCs not on bone surfaces were CTR negative. The restriction of CTR-positive cells to the surface of mineralized tissues suggests that bone and/or calcified cartilage provide signals that are critical for the differentiation of hematopoietic osteoclast precursors to fully differentiated osteoclasts. Some MNCs and mononuclear cells off bone and within invading tissues were TRAP positive. These cells likely represent the precursors of the CTR-TRAP-positive cells on bone. Parathyroid hormone receptor mRNA was present in cells with the phenotypic appearance of osteoblasts, in close proximity to MNCs, and in occasional cells within pannus tissue, but not in the MNCs in bone resorption lacunae. These findings demonstrate that osteoclasts within the rheumatoid lesion do not express parathyroid hormone receptor. In conclusion, the resorbing cells in RA exhibit a definitive osteoclastic phenotype, suggesting that pharmacological agents that inhibit osteoclast recruitment or activity are rational targets for blocking focal bone erosion in patients with RA and JRA.

Antibody to a Helicobacter pylori species specific antigen in patients with adenocarcinoma of the stomach

This study attempted to identify a possible antibody response to Helicobacter pylori, which is associated with patients with adeno-carcinoma of the stomach. By using proteins of H. pylori as the antigen, pooled sera from gastric cancer and non-cancer patients were used as the first antibody for Western blot analysis. Antibody responses to a 26 kD secreted protein were observed in pooled cancer sera, but not in pooled sera from non-cancer patients. The protein was purified, while amino acid sequences revealed that it was a H. pylori species specific protein. The gene of this protein was cloned and a recombinant protein was expressed in E. coli. In addition, an antibody to the recombinant protein was tested in each individual patient using Western blot analysis. None of the forty non-gastric cancer patients were positive for the antibody to the recombinantly expressed 26 kD species specific protein. Meanwhile, six of the twenty four cancer patients tested positive (0/40 vs 6/24, p < 0.01). Results presented herein demonstrate that the species specific protein of H. pylori can be useful in detecting H. pylori associated with adenocarcinoma of the stomach.

Prevalence and infectivity of hepatitis G virus and its strain variant, the GB agent, in volunteer blood donors in Taiwan

BACKGROUND

The prevalence of hepatitis G virus (HGV) and its strain variant, the GB agent (GBV-C) is high in non-virus-inactivated plasma products, but, persistent infection in recipients is relatively low.

STUDY DESIGN AND METHODS

Stored samples from transfusion donors and recipients in a prospective study of posttransfusion hepatitis were tested for HGV RNA and antibody to the E2 protein (anti-E2).

RESULTS

Thirty-two (2.1%) of the 1500 qualified donors were positive for HGV RNA. Twenty-four persons had received a transfusion of blood from one of these 32 viremic donors. Of these 24 recipients, 3 were positive for HGV RNA before transfusion. Of the remaining 21 recipients, 8 became viremic after transfusion, while the other 13 were not infected. Four of the eight infected recipients were persistently positive for HGV RNA, while four became negative in 1 to 3 years. Three of the four patients with HGV clearance seroconverted to anti-E2 positivity. Comparison of the viral titer, viral sequences at E2, storage period of blood donations, and clinical data in the infected and noninfected recipients revealed no significant differences. However, the noninfected recipients seemed to have a higher prevalence of anti-E2 before transfusion.

CONCLUSION

The prevalence of HGV viremia in volunteer blood donors in Taiwan is 2.1 percent, and blood from 0.6 percent of them actually causes HGV infection in the recipients. In half of infected recipients, clearance of HGV occurs. Anti-E2 appears in most recipients whose viremia is cleared.

Overexpression of mutant p53 and c-erbB-2 proteins and mutations of the p15 and p16 genes in human gastric carcinoma: with respect to histological subtypes and stages

Although the mechanism remains obscure, two histological subtypes of gastric carcinoma (GC), the diffuse and intestinal types, differ drastically in epidemiological, clinical, pathological and biological characteristics. We investigated whether the genetic alterations of several oncogenes and tumour suppressor genes could be correlated with the two histological subtypes. In 60 patients with GC, the overexpression of mutant p53 and c-erbB-2 oncoproteins was studied using immunohistochemical stains. Mutations of the p15 and p16 tumour suppressor genes were assessed by polymerase chain reaction, Southern blotting, and direct DNA sequencing. Overexpression of c-erbB-2 and p53 was found in 21 (35.0%) and 27 (45.0%) patients, respectively. Overexpression of the c-erbB-2 oncoprotein was more common in the intestinal type (15/32, 46.9%) and the advanced stage (19/45, 42.2%) than in the diffuse type (6/28, 21.4%) and the early stage (2/15, 13.3%) of GC (P<0.05). Similarly, p53 overexpression was more frequently found in the intestinal type (19/32, 59.4%) and the advanced stage (24/45, 53.3%) than in the diffuse type (8/28, 28.6%) and the early stage (3/15, 20.0%) of GC (P<0.05). Homozygous deletions of p16 in exon 1 were found in six (10.0%) patients. Five of them had the intestinal-type advanced GC. Neither point mutations of p16 nor alterations of p15 were detected. The frequency of alterations of p53, c-erbB-2, and p16 was not related to sex and Helicobacter pylori infection. No correlation of genetic changes between any two genes was observed. Our preliminary results indicate alterations in the p15 gene were not important in gastric tumorigenesis, while infrequent homozygous deletions in the p16 gene play a limited role in tumour progression of intestinal-type GC. Moreover, overexpression of c-erbB-2 and p53 is frequently encountered in the intestinal-type advanced GC. Alterations of p53, c-erbB-2 and p16 genes may function independently of each other in gastric carcinogenesis. The association between genetic alterations and histological subtypes supports the notion that a distinct pathogenesis may exist in different histological subtypes.

Multiple pathways to bypass the enhancer requirement of sigma 54 RNA polymerase: roles for DNA and protein determinants

Sigma 54 is a required factor for bacterial RNA polymerase to respond to enhancers and directs a mechanism that is a hybrid between bacterial and eukaryotic transcription. Three pathways were found that bypass the enhancer requirement in vitro. These rely on either deletion of the sigma 54 N terminus or destruction of the DNA consensus -12 promoter recognition element or altering solution conditions to favor transient DNA melting. Each of these allows unstable heparin-sensitive pre-initiation complexes to form that can be driven to transcribe in the absence of both enhancer protein and ATP beta-gamma hydrolysis. These disparate pathways are proposed to have a common basis in that multiple N-terminal contacts may mediate the interactions between the polymerase and the DNA region where melting originates. The results raise possibilities for common features of open complex formation by different RNA polymerases.