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Biomedical subjects

T H Wang

Publications and source records attributed to T H Wang.

At least 91 records · Page 5Linked to original sources
PubMed1997

Diagnostic role of endoscopy, stool culture, and toxin A in Clostridium difficile-associated disease.

This retrospective study was designed to assess the roles of stool culture for Clostridium difficile, detection of the presence of toxin A, and endoscopic examination in the diagnosis of Clostridium difficile-associated disease (CDAD). From January 1994 through September 1996, there were 213 patients with stool cultures positive for C. difficile in National Taiwan University Hospital. Of these, 126 had CDAD. There were 87 asymptomatic carriers of C. difficile in our study, 12 of whom were positive for toxin A. In addition, seven patients with pseudomembranous colitis (PMC), who were either culture-negative or not tested, were included in the study. The positive predictive values of stool cultures for CDAD and PMC were 59% and 32%, respectively. The positive predictive values of toxin A for CDAD and PMC were 41% and 43%, respectively. Seventy-eight patients (59%) improved with supportive treatment after discontinuing antibiotics. We concluded that stool culture for C. difficile and discontinuation of antibiotics should be the standard approach for patients with suspected CDAD. Endoscopic studies can eliminate some other possible causes of diarrhea such as inflammatory bowel disease, allow biopsies of suspicious lesions, and reveal the severity of CDAD. Toxin assay results need to be interpreted together with the clinical data.

Adolescent↗
PubMed1997

Biometric study of acute primary angle-closure glaucoma.

We investigated the biometric characteristics of acute primary angle-closure glaucoma (PACG) patients and sought guidelines to predict subjects at high risk of acute attack. We enrolled 80 patients who suffered acute attack of angle-closure glaucoma and 60 nonglaucoma subjects. The biometric data, measured with A scan ultrasonography, and the outcomes after various treatments were analyzed. Six patients were excluded because they were lost to follow-up. In the acute PACG patients, the axial length (mean +/- standard deviation) was 22.25 +/- 0.77 mm, the anterior chamber depth (corneal thickness included) was 2.28 +/- 0.23 mm, and the lens thickness was 4.94 +/- 0.28 mm. In the nonglaucoma subjects, the axial length was 23.26 +/- 0.76 mm, the anterior chamber depth (corneal thickness included) was 3.11 +/- 0.25 mm, and the lens thickness was 4.48 +/- 0.30 mm. An anterior chamber depth of less than 2.70 mm was the most sensitive (94%) and specific (94%) parameter to differentiate acute PACG patients from nonglaucoma subjects. The intraocular pressure was controlled within the satisfactory range in 58 patients by laser iridectomy, with or without antiglaucoma medication. Eight patients needed additional gonioplasty and eight required filtering surgery to control the intraocular pressure. Our findings provide useful information about the biometric data of eyes of patients with acute angle-closure glaucoma and offer a useful guide to predict those patients at high risk of acute attack.

Acute Disease↗
PubMed1997

Influence of axial length on visual field defects in primary open-angle glaucoma.

With the high frequency of myopia in Taiwan, potential complications or associated conditions, such as glaucoma, are of great concern. To investigate the role of axial length in glaucoma, we enrolled 307 primary open-angle glaucoma (POAG) patients from 1986 through 1996. For the control group, 124 persons were recruited from a survey of a non-glaucoma population and the Ophthalmology Out-patient Department of the National Taiwan University Hospital. Routine eye examination, stereophotography of the optic disc, automated visual field tests, and A-scan ultrasonography were performed on each patient. The Glaucoma Hemifield test was used for analysis of visual field results. The mean axial length was longer in the POAG group than in the control group, especially in the younger age groups (40-59 yr). The POAG group was divided into a short-axial-length (SAL, axial length < 26 mm) group and a long-axial-length (LAL, axial length > or = 26 mm) group. Both subgroups had the deepest visual field defects in the upper and lower nasal areas. The LAL group had deeper visual field defects and the defects were more frequently involved in all sectors analyzed than the SAL group defects. The upper visual field had deteriorated more in the SAL group, whereas the depth of scotoma was similar in the upper and lower hemifields in the LAL group. Our results support the idea that glaucoma patients have a longer axial length than people without glaucoma, and that visual field defects are more pronounced in patients with LAL than in those with SAL.

Adult↗
PubMed1996

Interleukin-3 increases the incidence of 5-azacytidine-induced thymic lymphomas in pBOR-Il-3 mice.

Interleukin-3 (Il-3) is a glycoprotein produced by a CD4+CD8- subpopulation of T-lymphocytes. Il-3 has been associated with the proliferation of bone marrow stem cells and their differentiation to granulocytes, macrophages, basophil/mast cells, megakaryocytes, erythroid cells, and neutrophils. The pBOR-Il-3 transgenic mice were developed by pronuclear microinjection to study how chemical insults modulate transcription of the Il-3 gene driven by a long-terminal repeat (LTR) of an endogenous retrovirus and to determine the biological consequences of interleukin-3 expression. We injected 5-azacytidine, a demethylating agent, to increase the LTR-driven expression of Il-3. Upon 5-azacytidine treatment, both the pBOR-Il-3 and the FVB/N nontransgenic controls developed thymic lymphomas. The pBOR-Il-3 mice developed thymic lymphomas at a higher frequency than the FVB/N mice. The thymic lymphoma cells were of a T-cell origin, as determined by T-cell receptor gene rearrangement analysis, and, in most cases, were of monoclonal origin. According to flow cytometric analysis of CD3, CD4, and CD8 cell surface markers, the thymic lymphoma cells did not lose their ability to differentiate, but the differentiation process was aberrant. Flow cytometric analyses also revealed that in pBOR-Il-3 mice the thymic lymphomas are mostly of a CD8+CD4- origin, whereas in the FVB/N group, the predominant type of thymic lymphoma is of a CD4+CD8- origin.

Animals↗
PubMed1996

A prospective study of transfusion-transmitted GB virus C infection: similar frequency but different clinical presentation compared with hepatitis C virus.

To study the incidence and outcome of GB virus C (GBV-C) infection in blood recipients. Serum samples collected in a prospective study were examined for GBV-C RNA by a nested polymerase chain reaction assay. Among the 400 adults who underwent cardiac surgery, 40 were positive for GBV-C RNA, including six whose pretransfusion sera were already positive and seven coinfected with hepatitis C virus (HCV) during transfusion. The risk of transmission was estimated to be approximately 0.46% per donor. GBV-C viremia was detectable 1 week after transfusion and could persist for 8 years. However, no evident symptoms or signs were noted in the 25 patients infected by GBV-C alone, and the average peak serum alanine aminotransferase activity was 31 IU/L only (range, 12 to 123), with persistently normal levels in 20 patients. In the seven patients coinfected with HCV, the clinical courses of posttransfusion hepatitis were similar to those infected by HCV alone. In eight patients with posttransfusion non-A approximately E hepatitis, only one was positive for GBV-C RNA. Sixty samples were chosen to test hepatitis G virus (HGV) sequences, 26 of the 30 GBV-C positives were positive for HGV RNA in contrast to none of the 30 GBV-C negative samples. In conclusion, GBV-C can be transmitted by transfusion in approximately 9% of patients who underwent cardiac surgery. Nevertheless, this virus does not seem to cause classic hepatitis in most instances.

Acute Disease↗
PubMed1996

Absence of extensive genetic heterogeneity of hepatitis C virus in antibody-negative chronic hepatitis C.

Hepatitis C virus (HCV) carriers usually have antibodies to HCV; however, there are viremic individuals without these antibodies. To investigate whether variations of the viral genome are responsible for this discrepancy, the nucleotide and deduced amino acid sequences of HCV capsid and nonstructural regions obtained from 15 viremic patients were examined. These 15 patients were infected with type 1b HCV, and 10 did not have antibody to HCV assayed with second-generation tests. The nucleotide homology of the 5 seropositive and 10 seronegative patients with the HCV prototype sequence were 91.6% and 91.9%, respectively, in the capsid region. There was no apparent difference in the deduced amino acid sequences between the two groups of patients studied (94% vs. 95%). The nucleotide and amino acid sequences of a part of the nonstructural region 3 also showed similar results. These findings suggest that absence of antibodies against both capsid and nonstructural peptides in HCV carriers is not caused by genetic heterogeneity of the viral epitopes.

Adult↗
PubMed1996

Superinfection by homotypic virus in hepatitis C virus carriers: studies on patients with post-transfusion hepatitis.

Although heterotypic superinfection and mixed infections of hepatitis C virus (HCV) may be possible for hepatitis flares in chronic hepatitis C, the possibility of homotypic HCV superinfection in HCV carriers with post-transfusion hepatitis has not been explored. Six HCV carriers with post-transfusion non-A, non-B hepatitis found in a prospective study of post-transfusion hepatitis were included. Serum samples before transfusion and during hepatitis were selected to determine genotypes of HCV and nucleotide sequences of the hypervariable region (HVR). The genotypes identified before and after transfusion were concordant in all. There were four with type 1b and one each with type 2a and type 2b. Amplified nucleotide sequences of the HVR before transfusion and during hepatitis were compared in four patients, and a > 95% homology was observed in three, suggesting persistence of original viruses. In contrast, only a 51% homogeneity was seen in a given patient, suggesting a homotypic HCV superinfection. Phylogenetic tree analysis validated further these findings. This study implies that HCV carriers can be reinfected by homotypic HCV, and this may contribute to hepatitis flares in chronic hepatitis C. These findings also confirm a weak or inadequate protective immunity in HCV infection and justify protection from reinfection of HCV of patients with chronic hepatitis C.

Adult↗
PubMed1996

Chronic hepatitis C without anti-hepatitis C antibodies by second-generation assay. A clinicopathologic study and demonstration of the usefulness of a third-generation assay.

To study the clinicopathologic features of hepatitis C viremic patients negative for hepatitis C antibodies (anti-HCV) by current second-generation assay, we categorized 139 consecutive histologically verified patients with chronic non-A, non-B hepatitis into three groups: 121 (87%) were positive for second-generation anti-HCV (group A); 10 (7%) were negative for second-generation anti-HCV but positive for HCV RNA (group B); and 8 (6%) were negative for both antibodies and viremia (group C). Six (60%) of group B patients could be, further detected by a new third-generation assay, but none of group C patients was third-generation anti-HCV-positive. The demographic features, mean peak serum alanine aminotransferase levels, HCV genotype distribution, and histologic changes were comparable among the three groups. The study indicates that most patients with chronic hepatitis C in Taiwan could be identified by current second-generation assay, and viremic but antibody seronegative patients were clinicopathologically similar to the seropositives. Most patients of the latter group could be diagnosed by a third-generation assay, indicating the usefulness of this assay.

Chronic Disease↗
PubMed1996

Serotyping of hepatitis C virus in chronic type C hepatitis in Taiwan: correlation with genotypes.

To evaluate the usefulness of a new serologic assay to group hepatitis C virus (HCV), genotypes identified by this serotyping method were compared to those identified by a polymerase chain reaction (PCR) assay with type-specific primers in 71 Taiwanese patients with chronic type C hepatitis. The group-specific antibodies against different HCV genotypes were detected by using an enzyme-linked immunosorbent assay (ELISA) based on group-specific recombinant peptides (C14-1 and C14-2) within the NS4 region. Among 71 patients positive for current second-generation HCV antibodies, HCV RNA was detected in 55 patients by PCR with primers from the 5' untranslating region, and in 52 by genotype-specific PCR. In 49 (89%) of 55 viremic patients, the results of serotyping by ELISA showed complete agreement with those determined by PCR genotyping, and none of the patients showed a group opposite to that of HCV genotype. The positive rate of group-specific antibodies (69/71;97%) was even better than that of the PCR (55/71;78%). We conclude that this new serotyping assay is highly sensitive and specific for the determination of HCV genotypes, and will be useful in future epidemiologic studies, as well for clinical application.

Adult↗
PubMed1996

Topical ointment therapy benefits premature infants.

OBJECTIVE: Premature infants have an ineffective epidermal barrier. The aim of this study was to investigate the cutaneous and systemic effects of preservative-free topical ointment therapy in premature infants. STUDY DESIGN: We conducted a prospective, randomized study of 60 infants less than 33 weeks' estimated gestational age. The treated infants received therapy for 2 weeks with twice-daily preservative-free topical ointment therapy while the control group received no topical treatment or as-needed therapy with a water-in-oil emollient. Data collection included transepidermal water loss (TEWL) measurement, skin condition evaluations, fungal and quantitative bacterial skin cultures, analysis of fluid requirements, patterns of weight low or gain, and the incidence of blood and cerebrospinal fluid cultures positive for microorganisms. RESULTS: We found that topical ointment therapy significantly decreased TEWL during the first 6 hours after the initial application. TEWL was decreased by 67% (p = 0.0001) when measured 30 minutes after application and 34% (p = 0.001) when measured 4 to 6 hours after application. We also observed significantly superior skin condition scores in the treated group on study days 7 and 14 (p = 0.001) and 0.0004, respectively). Quantitative bacterial cultures revealed significantly less colonization of the axilla on day 2, 3, or 4 and on day 14 (p = 0.008 and 0.04, respectively). The incidence of positive findings in blood and/or cerebrospinal fluid cultures was 3.3% in the treated group of infants versus 26.7% in the control group (p = 0.02). There was no statistical difference in the fluid requirements or patterns of weight gain or loss during the 2 weeks of the study. CONCLUSIONS: Preservative-free topical ointment therapy decreased TEWL for 6 hours after application, decreased the severity of dermatitis, and decreased bacterial colonization of axillary skin. Infants treated with ointment had fewer blood and cerebrospinal fluid cultures positive for microorganisms. These data support the use of topical ointment therapy in very premature infants during the first weeks after birth.

Administration, Topical↗
PubMed1996

Ultrasound-guided cutting biopsy for the diagnosis of hepatocellular carcinoma--a study based on 420 patients.

BACKGROUND/AIMS: To evaluate ultrasound-guided cutting biopsy for hepatocellular carcinoma, we report findings from 10 years of experience. METHODS: We performed 455 ultrasound-guided cutting biopsies of hepatic tumors in 420 patients with hepatocellular carcinoma from 1981 to 1990. RESULTS: Liver tissues were adequately sampled for a histological diagnosis of hepatocellular carcinoma in the initial biopsy in 391 sessions. The remaining 64 were proved to have hepatocellular carcinoma after subsequent studies. Ultrasound-guided biopsy changed the initial diagnosis in 9 of the 420 patients: three had been diagnosed with liver abscess, and six with metastatic liver tumors. Complications of the biopsy were rare: the tumor had spread to the chest wall in nine, and internal bleeding was noted in five patients. There was no mortality and no other sequelae. CONCLUSIONS: Ultrasound-guided biopsy of hepatic tumors is important in the diagnosis of liver cancer, but this technique should be applied only when the image diagnosis and results of fine needle biopsy are equivocal to minimize possible complications. For patients with small HCCs, who are candidates for surgical resection of hepatocellular carcinoma or liver transplantation, it should not be considered as a first-step invasive procedure.

Adolescent↗
PubMed1996

Organization of the Haemophilus ducreyi 35000 chromosome.

A physical and rudimentary genetic map of the Haemophilus ducreyi strain 35000 genome was constructed. Pulsed-field gel electrophoresis was used to separate restriction fragments of H. ducreyi DNA digested with Sfil, I-Ceul, or Sfil plus I-Ceul. The sizes of the fragments were determined, and the circular chromosome was estimated to be 1757 kbp. The six I-Ceul fragments and four Sfil fragments were ordered into macrorestriction maps using Southern blot hybridization with random H. ducreyi clones as probes. It was shown that both H. ducreyi and the distantly related Haemophilus influenzae have six rrn operons marked by the locations of the I-Ceul sites. However, the two species displayed distinct I-Ceul restriction patterns. A second H. ducreyi strain, CIP542, displayed an identical I-Ceul pattern to that of H. ducreyi 35000, but Sfil digests of teh two strains were distinct. The orientation of the six rrn operons was determined and thirteen identified H. ducreyi genes positioned on the map of strain 35000.

Blotting, Southern↗
PubMed1996

Intragenic homozygous deletions of MTS1 gene in gastric cancer in Taiwan.

The multiple tumor suppressor 1 (MTS1) and 2 (MTS2) genes, located on chromosome 9p21, have been reported to be deleted or mutated in many malignant cell lines and in a high percentage of some primary carcinomas. To determine whether these genes are altered, and if so, what is the nature of the alterations, in human gastric adenocarcinoma, we investigated their frequency of mutation by Southern blotting, polymerase chain reaction (PCR) and direct sequencing in 55 patients. Furthermore, loss of heterozygosity (LOH) of chromosome 9p21 at the IFNA locus and D9S171 was assessed. Homozygous deletions of exon 1 of the MTS1 gene were identified in 5 of 55 (9.1%) primary tumors. No deletion of MTS2 gene was noted. LOH was observed in 7 (14.3%) of 49 informative cases (5 cases at IFNA locus, 2 cases at D9S171 and one case with combined LOH at D9S171 and homozygous deletion at exon 1 of MTS1). Direct sequencing of PCR products of the MTS1 and MTS2 gene did not reveal any point mutation in these 55 patients. These data indicate that alterations of the MTS1 and MTS2 genes are infrequently encountered. Additional studies of LOH with more microsatellite markers near 9p21 are mandatory to elucidate whether another tumor suppressor gene exists in the vicinity of MTS1 in primary gastric adenocarcinoma.

Blotting, Southern↗
PubMed1996

Screening techniques for angle-closure glaucoma in rural Taiwan.

562 residents of Jin Shan aged 40 years and above underwent examinations to compare the sensitivity and specificity of oblique flashlight, peripheral slit beam and ultrasonographic evaluation of the anterior chamber depth to gonioscopy in detecting cases of PACG. Among 5441 eligible individuals aged 40 and above, 562 (10.3%) underwent screening for PACG, of whom 17 (3.02%) were defined as cases, and 10 (1.78%) as suspects. Home visits indicated that respondents for screening were similar to the population as a whole. Only 35% of PACG cases reported symptoms consistent with acute angle closure, and only 18% were previously diagnosed. When compared to gonioscopy, only ultrasonographic measurement of AC depth provided an adequate mix of sensitivity and specificity. Ultrasonography in combination with tonometry provided a sensitivity of 88% with a specificity of 92%. Sensitivity and specificity for ultrasonography in combination with refractive status were 84% and 83% respectively. Shallower AC depth (p = 0.0001), shorter axial globe length (p = 0.001), greater than 2D of hyperopia (p < 0.001), high grades of nuclear sclerotic cataract (p < 0.0001) and an increased cup-to-disc ratio (p = 0.002) were significantly correlated with a diagnosis of PACG.

Adult↗
PubMed1996

Helicobacter pylori in tumor tissues of patients with advanced gastric adenocarcinoma: high prevalence but failure to detect integration.

Helicobacter pylori has been known to be associated with gastric adenocarcinoma by case control studies. However, significant portion of patients with gastric carcinoma are negative for H. pylori by serological test. To further detect the presence of H. pylori infection in serum and tissue of patients with gastric adenocarcinoma, paired tissues and serum samples from 32 patients with gastric adenocarcinoma were tested. Antibodies to H. pylori were tested by an enzyme linked immunosorbent assay (ELISA) and a Western blot analysis. H. pylori in tumor and non-tumor parts of gastric tissues were examined by histology and polymerase chain reaction (PCR). For serum antibody, eighteen (56%) of these patients were positive by ELISA while 24 (75%) were positive by Western blot. For tissue H. pylori genome, 14 were positive by histology while 28 (87%) were positive by PCR. Southern blot analysis of both tumor and non-tumor tissues revealed no evidence of integration of H. pylori DNA in the human genomes. These results suggest that H. pylori infection can be detected in most patients with gastric adenocarcinoma, and PCR and Western blot can further identify seronegative patients.

Adenocarcinoma↗
PubMed1996

p53, apoptosis and human cancers.

More than half of human cancers contain p53 mutations. Structural analyses of p53-DNA interactions indicate that hot spots of p53 mutation are often either involved in direct contact with target DNA or those that maintain specific conformation of p53. One significant consequence of the loss of wild type p53 function is inhibition of apoptosis, which may be through the inability of mutant p53 to transcriptionally activate bax gene expression. Quantitative correlation among ultraviolet-induced p53 mutations of keratocytes, inhibition of apoptosis and the development of squamous cell cancer of the skin further suggest a central role of inhibited apoptosis between p53 mutations and tumorigenesis. Hypoxia-mediated selection for p53 mutant cells with diminished apoptotic potential in solid tumors may account for the high prevalence of p53 mutations in human cancers. Our increasing understanding of the role of p53 mutations and apoptosis in human cancers has also provided some insights into strategies for anticancer therapy. Studies reconstituting the wild-type p53 through gene therapy have been encouraging. More importantly, further elucidation of the mechanisms of therapy-induced p53-independent apoptosis in cancer cells will facilitate the development of more efficient, less toxic anticancer therapy.

Apoptosis↗
PubMed1996

Transmission of hepatitis C virus between spouses: the important role of exposure duration.

OBJECTIVES: Although interspousal transmission of hepatitis C virus (HCV) has been studied, the factors responsible for it remain unclear. METHODS: To investigate the transmission of HCV between spouses and the related risk factors, 100 anti-HCV-positive index patients and their spouses were studied. RESULTS: Overall, anti-HCV was detected in 17 (17%) spouses, 15 of whom were also positive for HCV RNA, and 11 couples were infected with the same genotype. The anti-HCV-positive rate was higher in spouses married longer than 20 yr compared with those married less than 20 yr (22 vs 6%, p < 0.05), and the infection was correlated with the duration of their actual exposure to the index patients but not with serum HCV titers. The infected couples had more frequent sexual contacts and more commonly shared tooth-brushes than those with uninfected spouses. CONCLUSION: Spouses of patients with chronic hepatitis C have a higher risk of acquiring HCV that increases with longer marriage and duration of exposure, and they should be educated about how to avoid contracting HCV infection from their spouses.

Female↗