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Biomedical subjects

W M Wang

Publications and source records attributed to W M Wang.

At least 19 recordsLinked to original sources
PubMed2006

Randomized comparison of two rescue therapies for Helicobacter pylori infection.

BACKGROUND: Bismuth salts are not available worldwide. It remains unknown whether clarithromycin can replace bismuth salts as an adjuvant agent in the rescue regimens for Helicobacter pylori infection. We therefore designed the prospective study to compare the efficacies of two rescue therapies for H. pylori infection after standard triple therapies. PATIENTS AND METHODS: Ninety-three patients who failed H. pylori eradication using proton pump inhibitor plus clarithromycin and amoxicillin were randomly assigned to undergo rescue therapy with esomeprazole, clarithromycin, tetracycline and metronidazole (ECTM group, n = 46) or esomeprazole, bismuth subcitrate, tetracycline and metronidazole (EBTM group, n = 47). Follow-up endoscopy was performed at 8 weeks after the end of treatment to assess the treatment response. RESULTS: Intention-to-treat analysis demonstrated both groups had similar eradication rates (ECTM 74% vs. EBTM 77%; P = 0.76) and drug compliance (ECTM 94% vs. EBTM 96%; P = 0.68). However, the frequency of adverse events in the ECTM group was higher than that in EBTM group (ECTM 57% vs. EBTM 36%, P = 0.05). In the EBTM group, eradication rate of metronidazole-resistant strains was lower than that of metronidazole-susceptible strains (67%[8/12] vs. 100%[9/9], P = 0.05). However, eradication rates were similar between metronidazole-susceptible and metronidazole-resistant strains in ECTM group (69%[9/13] vs. 70%[7/10], P = 1.00). CONCLUSIONS: The new ECTM second-line therapy can achieve similar eradication rate as standard EBTM therapy. It may be very useful in countries where bismuth salts are not available.

Adult↗
PubMed2005

Tetracycline-resistant clinical Helicobacter pylori isolates with and without mutations in 16S rRNA-encoding genes.

Tetracycline-resistant Helicobacter pylori strains have been increasingly reported worldwide. However, only a small number of tetracycline-resistant strains have been studied with regard to possible mechanisms of resistance and those studies have focused on mutations in the tetracycline binding sites of 16S rRNA-encoding genes. We here report studies of 41 tetracycline-resistant H. pylori strains (tetracycline MICs, 4 to 32 microg/ml) from North America (n = 12) and from East Asia (n = 29). DNA sequence analyses of 16S rRNA-encoding genes revealed that 22 (54%) of the resistant isolates carried one of five different single-nucleotide substitutions (CGA, GGA, TGA, AGC, or AGT) at the putative tetracycline binding site (AGA(965-967)). Single-nucleotide substitutions were associated with reduced ribosomal binding and with slightly increased tetracycline MICs (1 to 2 microg/ml). The 19 tetracycline-resistant isolates with no detectable mutations in the tetracycline binding site had normal tetracycline-ribosome binding. All tetracycline-resistant isolates, including those with and those without mutations in the tetracycline binding site, showed decreased accumulation of tetracycline. These results suggest that tetracycline resistance is multifactorial, involving alterations both in ribosomal binding and in membrane permeability.

Antiporters↗
PubMed2004

The enhancement of nuclear receptor transcriptional activation by a mouse actin-binding protein, alpha actinin 2.

The p160 coactivators, steroid receptor coactivator 1, glucocorticoid receptor interacting protein 1 (GRIP1) and the activator of thyroid and retinoic acid receptor, have two activation domains, AD1 and AD2, which transmit the activation signal from the DNA-bound nuclear receptor to the chromatin and/or transcription machinery. In screening for mammalian proteins that bind the AD2 of GRIP1, we identified a mouse actin-binding protein, alpha actinin 2 (mACTN2). mACTN2 was expressed in the heart, skeletal muscle, lung, brain and testis, but there was no expression in the spleen, liver or kidney. Interestingly, the expression level of mACTN2 in the developing embryo depended on the embryonic stage. We further demonstrated that mACTN2 could enhance two transactivation activities of GRIP1, which in turn could enhance the homodimerization of mACTN2. Importantly, mACTN2 not only served as a primary coactivator for androgen receptor, estrogen receptor and thyroid receptor activities, but also acted synergistically with GRIP1 to enhance these nuclear receptor (NR) functions. However, the NR binding motif, LXXLL, conserved in mACTN2 and other actinin family proteins, might be a dispensable domain for its coactivator roles in NRs. These findings suggested that mACTN2 might play an important role in GRIP1-induced NR coactivator functions.

Actinin↗
PubMed2001

An efficient method for the culture of Helicobacter pylori from gastric biopsies with two-section petri dishes.

PURPOSE: Helicobacter pylori is the principal cause of chronic gastritis and is strongly associated with peptic ulcer disease and gastric cancer, as well as with gastric lymphoma (mucosa-associated lymphoid tissue [MALT] type). H. pylori could be recovered by many kinds of media, however, it could not be detected efficiently. This study was trying to ameliorate the isolation and detection rate with selective and non-selective media. METHODS: First, type strain (ATCC 43504) was cultured with twelve different kinds of sheep blood agar based on brain heart infusion medium for five days. Then five better non-selective media and five selective media were chosen for the biopsy, which were incubated at 37 degrees C in a microaerophilic incubator for five days. Endoscopic biopsies were collected from 623 patients at Kaohsiung Medical University Hospital. RESULTS: It was found that non-selective media, which contain 5% modified chocolate agar (the ratio of fresh and heated sheep blood is 2) with 1% Isovitalex, had the best detection rate (91.1 +/- 0.6)%. Furthermore, 5% modified chocolate agar with 1% Isovitalex and 1% antibiotics would increase the detection rate to (97.1 +/- 0.3)%. CONCLUSIONS: According to Ansorg's method, the best detection rate (98.4 +/- 0.7)% could be obtained with two-section petri dishes which had 5% modified chocolate agar with antibiotics and the other without antibiotics.

Animals↗
PubMed2001

[Construction of a deep coverage rice BAC library and identification of clones associated with disease-resistant genes].

A BAC library for IRBB56, an accession pyramiding Xa4, xa5 and xa13 three bacterial blight resistance genes, was constructed. The library contains 55,296 clones with an average insert size of 132 kb. Based on a haploid genome size of 450 Mb, the coverage of the library was about 14 genome equivalents that make it one of the most comprehensive BAC libraries available in rice and provide 99.99% possibility to isolate any interested rice genes or sequences in the library. To determine the representation of organelle DNA homologues in the library, the library was screened with three different chloroplast genes and four mitochondrial genes, respectively. Results from this screening showed that less than 1% of clones in the library contain organelle genomic DNA homologues. Then, DNA markers on three different chromosomes linked to Xa4, xa5, and xa13, and a PCR fragment of rice UROD gene, were used to screen the library resulting in a range of 11-106 hits that will promote the isolation of these genes. The deep coverage and the large insert size of the library will facilitate physical mapping, isolation, and cloning of rice genes.

Chromosomes, Artificial, Bacterial↗
PubMed2001

[Construction of a bacterial artificial chromosome (BAC) contig encompassing the bacterial blight resistance gene Xa4 locus in rice].

The gene Xa4 confers dominantly resistance to rice bacterial blight, which has been finely mapped between RFLP markers G181 and L1044, and co-segregated with the resistance gene homologues sequence marker RS13. The three markers were used to screen a rice Bacterial Artificial Chromosome (BAC) library constructed from IRBB56, a Xa4-harborring indica variety, resulting in the detection of totally 128 positive clones. Of the 18 positive clones picked out by RS13, 4 and 6 clones were simultaneously detected by G181 and L1044, respectively. Based on their HindIII restriction patterns, 12 clones were selected out to construct a contig that spanned about 420 kb covering the Xa4 locus, which is a solid base for the isolation of Xa4 gene.

Chromosomes, Artificial, Bacterial↗
PubMed2001

[Amplification and analysis of T-DNA flanking sequences in transgenic rice].

Rice transformation mediated by Agrobacterium tumefaciens has technically matured to some extent, but the mechanics of T-DNA integration in transgenic rice remains largely unknown. Using thermal asymmetric interlaced PCR (TAIL-PCR), we analyzed the flanking sequences of T-DNAs in transgenic rice plants, in which the resistance gene for rice bacterial blight disease, Xa21, had been integrated stably. Sequence analysis of 24 fragments amplified by TAIL-PCR showed that of them 14 were rice genomic DNA, 9 contained vector backbone sequences, and one was a fragment of the exogenous gene Xa21. The characteristics of the 14 rice genomic DNA sequences at T-DNA integrated sites are significantly different from those of the reported rice genomic sequences into which exogenous genes were integrated through direct DNA transformation methods. T-DNA border sequences integrated in rice genome have similar features as those integrated in dicotyledonous genomes. In the backbone containing flanking sequences (37.5%, 9/24) vector backbones appeared in different types.

Base Sequence↗
PubMed2001

Factors affecting the isotopic composition of organic matter. (1) Carbon isotopic composition of terrestrial plant materials.

The stable isotope composition of the light elements (i.e., H, C, N, O and S) of organic samples varies significantly and, for C, is also unique and distinct from that of inorganic carbon. This is the result of (1) the isotope composition of reactants, (2) the nature of the reactions leading to formation and post-formational modification of the samples, (3) the environmental conditions under which the reactions took place, and (4) the relative concentration of the reactants compared to that of the products (i.e., [products]/[reactants] ratio). This article will examine the carbon isotope composition of terrestrial plant materials and its relationship with the above factors. delta13C(PDB) values of terrestrial plants range approximately from -8 to -38%, inclusive of C3-plants (-22 to -38%), C4-plants (-8 to -15%) and CAM-plants (-13 to -30%). Thus, the delta13C(PDB) values largely reflect the photosynthesis pathways of a plant as well as the genetics (i.e., species difference), delta13C(PDB) values of source CO2, relevant humidity, CO2/O2 ratios, wind and light intensity etc. Significant variations in these values also exist among different tissues, different portions of a tissue and different compounds. This is mainly a consequence of metabolic reactions. Animals mainly inherit the delta13C(PDB) values of the foods they consume; therefore, their delta13C(PDB) values are similar. The delta13C(PDB) values of plant materials, thus, contain information regarding the inner workings of the plants, the environmental conditions under which they grow, the delta13C(PDB) values of CO2 sources etc., and are unique. Furthermore, this uniqueness is passed on to their derivative matter, such as animals, humus etc. Hence, they are very powerful tools in many areas of research, including the ecological and environmental sciences.

Animals↗
PubMed2001

Diagnosis of Helicobacter pylori infection by stool antigen test in southern Taiwan.

Helicobacter pylori (H. pylori) has been found to be associated with various gastrointestinal diseases. Confirmation of H. pylori infection includes invasive and non-invasive methods. There has been increasing interest in noninvasive tests recently. However, the geographical differences among H. pylori strains have been emphasized recently and the H. pylori strain in Taiwan showed a high cagA positive result and different vacA subtype when compared with those of Western countries. The aim of this study is to access and compare the reliability and the diagnostic accuracy of the stool H. pylori antigen tests by spectrophotometry and by the visual method, especially in Southern Taiwan. Thirty-two patients (18 men and 14 women; age range: 23-91 y/o, mean: 50.5 y/o) who underwent gastroendoscopy at Kaohsiung Medical University Hospital were enrolled in this study. H. pylori infection status was confirmed by culture or two positive test results on CLO test, histology and 13C-urea breath test (13C-UBT). The exclusion criteria included previous gastrointestinal tract surgery, use of antibiotics, proton pump inhibitor or compounds containing bismuth within 1 month of the study. Among them, 14 patients were with duodenal ulcer (DU), 4 with gastric ulcer (GU), 12 with non-ulcer dyspepsia, and 2 with GU and DU. Those patients had their stool collected for ELISA tests of H. pylori stool antigen (HpSA). The HpSA tests were positive in 16 of 18 patients diagnosed as H. pylori positive, and negative in 13 of 14 patients as H. pylori negative. The sensitivity and specificity were 88.9% and 92.9% respectively. The positive and negative predictive values were 94.1% and 86.7% respectively. The concordance of HpSA accessed by spectrophotometry and visual method is 100%, which makes this test even easier and cheaper. We concluded that stool HpSA test is a noninvasive, accurate, reliable, rapid and easy way to diagnose H. pylori infection in Southern Taiwan, either by spectrophotometry or by visual assessment.

Adult↗
PubMed2000

The association between Helicobacter pylori infection and functional dyspepsia in patients with irritable bowel syndrome.

OBJECTIVE: Irritable bowel syndrome (IBS) is associated with an exaggerated response to a variety of physiological and nonphysiological gastrointestinal stimuli. Many patients with IBS also have functional dyspepsia. Our aim was to examine the hypothesis that Helicobacter pylori (H. pylori) infection may predispose IBS patients to functional dyspepsia. METHODS: In 69 IBS patients, dyspeptic symptoms, H. pylori status, and sociodemographic and psychological variables (perceived stress, trait anxiety, and depression) were assessed. Sociodemographic and psychological variables were also evaluated in 52 control subjects. RESULTS: Mean scores for perceived stress (17.1 +/- 6.0 vs 14.9 +/- 6.0, p = 0.05), trait anxiety (45.6 +/- 9.1 vs 41.1 +/- 7.8, p = 0.004) and depression (9.9 +/- 8.4 vs 5.0 +/- 5.5, p = 0.0002) were higher in IBS patients than in controls. In all, 33 of the 69 patients (47.8%) had H. pylori infection, and this was associated with relevant symptoms of epigastric pain (odds ratio [OR] = 6.77, 95% confidence interval [CI] 1.89-24.3) and postprandial upper abdominal fullness (OR = 4.23, 95% CI 1.38-13.2). H. pylori infection and female gender were independent predictors of the presence of relevant dyspepsia (OR = 8.31, 95% CI 2.35-29.5 and 6.06, 95% CI 1.71-21.5, respectively). Symptom intensity was associated with the level of perceived stress (total relevant symptom number > or =3 vs <3, OR = 1.16 per point on a 40-point perceived stress scale, 95% CI 1.01-1.34). CONCLUSIONS: In IBS patients, the presence of dyspepsia is associated with H. pylori infection, female gender, and perceived stress.

Adult↗
PubMed2000

[Molecular tagging of a new recessive gene for late heading in a rice cultivar 8987].

8987 is a late flowering (lf) indica cultivar. In this study, genetic analysis for lf was carried out in the crosses between 8987 and four varieties with different heading time. Inheritance of lf in F1 plants and F2 populations clearly revealed that the lf of 8987 is controlled by one recessive gene. Bulked-segregant method and cosegregation analysis in F2 population were used to screen molecular markers, which were linked with lf gene. The results showed that the lf gene was mapped between the two RFLP marker C213 and RG404 on chromosome 7. The tagged gene will be utilized in molecular marker assisted selection in the future rice breeding program for new varieties.

Chromosome Mapping↗
PubMed2000

[Introduction of wide spectrum rice bacterial blight resistance gene Xa21 into two-line genic male sterile rice variety Pei'ai 64S].

Agrobacterium-mediated transformation of two-line genic male sterile Indica rice variety Pei'ai 64S was conducted using a cloned gene, Xa21, as the foreign gene and mature embryo calli as the recipients. A total of 46 transgenic plants had been obtained. The PCR analysis and Southern blotting showed the integration of Xa21 gene into the genome the transgenic plants. Results of inoculation with philippine race 6 of Xanthomonas oryzae pv. oryzae indicated that most of transgenic plants obtained high resistance to rice bacterial blight disease (Xoo). Analyses of T1 plants of the tested transgenic lines showed that integrated Xa21 gene could be steadily inherited and segregated in a 3:1 ratio.

Oryza↗
PubMed2000

[Integration of the genetic map and the physical map of the subterminal region on the longer arm of rice chromosome 6].

The region between RFLP markers G342 and R1167 was the subterminal part of the longer arm on the rice chromosome 6, because Shen et al. (1998) mapped two telomeric repeat associated sequences distal to G342. In order to integrate the genetic map and the physical map of the region, G342 and R1167 were firstly used to screen BAC library. Based on the positive clones detected by the two markers and chromosome walking by using the outer most insert-end of the overlapping clones, a contig containing 16 BAC clones which spanned 500 kb was constructed. All the insert-ends of the BAC clones could be amplified with thermal asymmetric interlaced PCR. Fourteen insert-ends were subcloned. Seven of them were identified as a single or low copy sequences and five were mapped on the expected sites flanking G342 or R1167. The insert fragment isolated from the minimum tile BAC clones of the contig was used to screen a cDNA library and four different positive clones were detected.

Chromosome Mapping↗
PubMed2000

Simplified 13C-urea breath test for the diagnosis of Helicobacter pylori infection--the availability of without fasting and without test meal.

The conventional 13C-urea breath test (13C-UBT) for detecting Helicobacter pylori infection was performed during fasting state and with a test meal to delay gastric emptying during the test. For the convenience of propagating this test, we assessed the availability of non-fast and without test meal in 13C-UBT for the diagnosis of H. pylori infection. One hundred and five consecutive patients who received endoscopic examination were studied. All of them received endoscopic biopsy for urease test, culture and histopathology to determine whether there was a presence of H. pylori infection. Each patient received four separate 13C-UBT under the following four testing conditions. Test I) fasting state with test meal (100 ml fresh milk), Test II) non-fast (taking usual food) but with test meal, Test III) fasting state without test meal, and Test IV) non-fast and without test meal. The excess delta 13CO2 values were calculated via the breathed samples that were collected at 15 minutes after ingestion of 13C-urea. There were 61 H. pylori positive and 44 negative patients in this study, with an excess delta 13CO2 values 3.0, 4.0, 3.5 and 4.0 as a cut-off value in the four tests respectively, according to the ROC curve. The results of test I, a conventional procedure, had a good correlation with the gold standard. The sensitivity and specificity were 100% and 95% respectively. The alternative procedures in other tests also have high sensitivity and specificity at 15-minute detecting time. The sensitivity of the tests II, III and IV at 15-minute detecting times were 98%, 98% and 100%, and the specificities of those were 95%, 98% and 95% respectively. We therefore suggest that fasting and test meal possibly be omitted when the cut-off value is 4.0 per mil in the simplified 13C-UBT (non-fast and without test meal, and detection at 15 minutes after ingestion of 13C-urea) which is a simple and available procedure for clinical diagnosis of H. pylori infection.

Adult↗
PubMed1999

Endoscopic hydrogen peroxide spray may facilitate localization of the bleeding site in acute upper gastrointestinal bleeding.

BACKGROUND AND STUDY AIMS: A major problem encountered in the emergency endoscopic management of acute upper gastrointestinal (UGI) bleeding is poor localization of the bleeding site, which can be obscured by blood or clots. Traditional attempts to overcome this problem have been by physical methods, which have usually proved unsatisfactory. The aim of this prospective study was to show that hydrogen peroxide can be used as a dissolution agent, resulting in an alteration of the characteristics of blood clots and allowing a clearer visual field. PATIENTS AND METHODS: Twenty patients with acute UGI bleeding (13 male, seven female) were included in the study. The suspected site of bleeding was initially sprayed with 200 ml of saline and then with 25-175 ml of 3 % H2O2. Pictures of the visual field were taken before and after irrigation with both saline and H2O2. These pictures were evaluated by three gastroenterologists and scored using the following visual clearance scoring system: -3, marked worsening of visual field; -2, moderate worsening; -1, slight worsening; 0, no change; +1, slight improvement; +2, moderate improvement; + 3, marked improvement. In cases of active oozing or spurting, after initial hemostasis was achieved the bleeding point was injected with pure ethanol or cauterized with a heater probe. In order to assess the safety of 3 % H2O2 endoscopic biopsies of the antrum and the duodenal bulb were performed before and 30 minutes after its use and examined by a pathologist. RESULTS: There was a significant improvement in the mean visual clearance score after irrigation with H2O2 compared to irrigation with saline alone (2.13 vs. 0.43, P<0.001). During endoscopic examination there were 19 patients with active oozing from the ulcer base covered by an adherent blood clot; 12 of these (63.1%) achieved initial hemostasis after H2O2 spraying. Eleven of 18 (61.1 %) patients complained of a mild epigastric burning sensation during H2O2 irrigation. There was no clinically significant change in the histology of the antrum and the duodenal bulb after H2O2 therapy. CONCLUSIONS: We concluded that H2O2 is a safe and effective way to clear the visual field, facilitating the localization of the bleeding site during emergency endoscopy for acute UGI bleeding, with only mild side effects. In some cases H2O2 therapy can also induce temporary hemostasis. We recommended the use of hydrogen peroxide to improve endoscopic visualization, especially in cases where an adherent blood clot covers the suspected bleeding site.

Adult↗