Biomedical subjects

P C Yang

Publications and source records attributed to P C Yang.

At least 19 recordsLinked to original sources

PubMed2001

p53 amino acids 339-346 represent the minimal p53 repression domain.

The p53 tumor suppressor protein functions as an activator and also as a repressor of gene transcription. Currently, the mechanism of transcriptional repression by p53 remains poorly understood. To help clarify this mechanism, we carried out studies designed to identify the minimal repression domain that inhibits p53 transcriptional activities. We found only eight amino acids (339) of the COOH-terminal domain (termed P53MRD) that possess activities of repression. The exact location of this minimal domain is on the E6-binding region, and it lacks the ability of tetramerization. P53MRD is able to repress the transcription of p53 while not affecting VP16. The mutants (amino acids M340P and F341D) of native p53 also lost transcriptional repression of the thymidine kinase chloramphenicol acetyltransferase promoter. These results suggest that this eight-amino acid element is required for the repression of p53.

Binding Sites↗

PubMed2000

Differential gene expression of livers from ApoE deficient mice.

A genomic survey for differentially expressed genes was performed to livers of ApoE deficient mice using human cDNA microarray containing approximately 9,000 human cDNA clones. Due to the homology between mouse and human, hybridization was performed at lower stringency condition, 10 degrees below the regular hybridizing temperature. Gene expression profiles of livers corresponding to high levels of blood cholesterol were generated at genomic scale. Thirty-seven genes were randomly selected from a pool of differentially expressed genes and subjected to semi-quantitative RT-PCR, further confirmed the result from microarray hybridization. These included genes associated with atherosclerosis, and novel genes that implied novel pathways correlated to high levels of blood cholesterol. It is promising using human cDNA microarray, the most complete collection among all species, to study other mammalian systems with satisfying speed and accuracy.

Animals↗

PubMed2000

Correlation of total VEGF mRNA and protein expression with histologic type, tumor angiogenesis, patient survival and timing of relapse in non-small-cell lung cancer.

We have quantified the expression of all 4 isoforms of vascular endothelial growth factor (VEGF) mRNA in non-small-cell lung cancer (NSCLC) using a new kinetic quantitative PCR method, real-time quantitative (RTQ) RT-PCR, and investigated the association between VEGF expression at the mRNA and protein levels and the clinicopathologic variables, tumor angiogenesis, patient survival and timing of relapse. Surgical tumor specimens from 72 NCSLC patients (37 squamous-cell carcinomas, 35 adenocarcinomas) were examined. Twenty-eight patients had stage I, 10 stage II and 34 stage IIIA or IIIB disease. Total VEGF mRNA (all 4 isoforms) was quantified by RTQ RT-PCR, while VEGF protein expression and microvessel number in tumors were assessed immunohistochemically. VEGF mRNA was detected in all 72 tumor samples at significantly higher levels than in adjacent normal tissue. Tumoral VEGF mRNA levels correlated strongly with the VEGF protein staining score and microvessel count. Adenocarcinomas showed significantly higher VEGF mRNA expression and a higher protein staining score than squamous-cell carcinomas. High tumoral VEGF mRNA expression was associated with advanced (IIIA or IIIB) tumor stage, lymph node metastasis, high tumoral microvessel counts, short patient survival (<24 months) and early relapse (<12 months), while a high VEGF protein staining score was associated with high tumoral microvessel counts, short patient survival and early relapse. Patients with high tumoral levels of both VEGF mRNA and protein had significantly shorter survival and earlier relapse. In multivariate analysis, the VEGF protein staining score and nodal status were the most important independent predictors of survival and recurrence. We conclude that RTQ RT-PCR is a sensitive method for detecting and quantifying VEGF mRNA expression in NSCLC and that the expression levels of total VEGF mRNA and protein in NSCLC are strongly associated with histologic type, tumor angiogenesis, survival and timing of relapse. High VEGF expression in adenocarcinomas may contribute to their greater metastatic potential.

Analysis of Variance↗

PubMed2000

Molecular epidemiological studies on foot-and-mouth disease type O Taiwan viruses from the 1997 epidemic.

Sequence diversity was assessed of the complete VP1 gene directly amplified from 49 clinical specimens during an explosive foot-and-mouth disease (FMD) outbreak in Taiwan. Type O Taiwan FMD viruses are genetically highly homogenous, as seen by the minute divergence of 0.2-0.9% revealed in 20 variants. The O/HCP-0314/TW/97 and O/TCP-022/TW/97 viral variants dominated FMD outbreaks and were prevalent in most affected pig-raising areas. Comparison of deduced amino acid sequences around the main neutralizable antigenic sites on the VP1 polypeptide showed no significant antigenic variation. However, the O/CHP-158/TW/97 variant had an alternative critical residue at position 43 in antigenic site 3, which may be due to selective pressure in the field. Two vaccine production strains (O1/Manisa/Turkey/69 and O1/Campos/Brazil/71) probably provide partial heterologous protection of swine against O Taiwan viruses. The type O Taiwan variants clustered in sublineage A1 of four main lineages in the phylogenetic tree. The O/Hong Kong/9/94 and O/1685/Moscow/Russia/95 viruses in sublineage A2 are closely related to the O Taiwan variants. The causative agent for the 1997 epidemic presumably originated from a single common source of type O FMD viruses prevalent in neighboring areas.

Amino Acid Sequence↗

PubMed2000

Molecular evidence for strain dissemination of Penicillium marneffei: an emerging pathogen in Taiwan.

From January 1987 through December 1998, Penicillium marneffei infection (23 patients) or colonization (1 patient) was diagnosed in a total of 24 patients in Taiwan. Of these 24 patients, 16 (67%) had AIDS and 20 (83%) had disseminated P. marneffei infection. The majority (63%) of the infections were considered indigenous. The number of cases has increased markedly in recent years, with 17 of the 24 cases diagnosed from 1996 through 1998. Twenty preserved isolates of P. marneffei, recovered from 11 patients treated at National Taiwan University Hospital during the period of January 1996 through December 1998, were studied to determine the epidemiology of P. marneffei infections. Among the 20 isolates, a total of 8 strains (highly related isolates) were identified on the basis of tests for susceptibility to 5 antifungal agents, for chromosomal DNA restriction fragment-length polymorphism types, and for randomly amplified polymorphic DNA patterns. One of the strains (6 isolates) was isolated from 4 patients treated in 1997 and 1998. Strain spreading of P. marneffei may partially contribute to the increased number of infections caused by this organism in immunosuppressed patients in Taiwan.

Adolescent↗

PubMed2000

Oxidative stress disrupts glucocorticoid hormone-dependent transcription of the amiloride-sensitive epithelial sodium channel alpha-subunit in lung epithelial cells through ERK-dependent and thioredoxin-sensitive pathways.

The amiloride-sensitive epithelial Na(+) channel (ENaC) plays a critical role in the maintenance of alveolar fluid balance. It is generally accepted that reactive oxygen and nitrogen species can inhibit ENaC activity and aggravate acute lung injury; however, the molecular mechanism for free radical-mediated ENaC inhibition is unclear. Previously, we showed that the expression of the alpha-subunit of ENaC, alpha-ENaC, which is indispensable for ENaC activity, is repressed by Ras activation in salivary epithelial cells. Here, we investigated whether exogenous H(2)O(2) modulates alpha-ENaC gene expression in lung epithelial cells through a similar molecular mechanism. Utilizing transient transfection reporter assays and site-directed mutagenesis analyses, we found that the glucocorticoid response element (GRE), located at -1334 to -1306 base pairs of the alpha-ENaC 5'-flanking region, is the major enhancer for the stimulated alpha-ENaC expression in A549 lung epithelial cells. We further demonstrate that the presence of an intact GRE is necessary and sufficient for oxidants to repress alpha-ENaC expression. Consistent with our hypothesis, exogenous H(2)O(2)-mediated repression of alpha-ENaC GRE activity is partially blocked by either a specific inhibitor for extracellular signal-regulated kinase (ERK) pathway activation, U0126, or dominant negative ERK, suggesting that, in part, activated ERK may mediate the repressive effects of H(2)O(2) on alpha-ENaC expression. In addition, overexpression of thioredoxin restored glucocorticoid receptor action on the alpha-ENaC GRE in the presence of exogenous H(2)O(2). Taken together, we hypothesize that oxidative stress impairs Na(+) transport activity by inhibiting dexamethasone-dependent alpha-ENaC GRE activation via both ERK-dependent and thioredoxin-sensitive pathways. These results suggest a putative mechanism whereby cellular redox potentials modulate the glucocorticoid receptor/dexamethasone effect on alpha-ENaC expression in lung and other tight epithelia.

Butadienes↗

PubMed2000

The decline of porcine sperm motility by geldanamycin, a specific inhibitor of heat-shock protein 90 (HSP90).

Sperm motility is an important parameter for fertility. The molecular mechanisms of mammalian sperm motility are still largely undefined. Our previous observations suggested that heat shock protein 90 (HSP90) may be associated with porcine sperm motility. The aim of the present study was to further characterize the plausible novel function of HSP90 on sperm motility. Semen from normal, sexually mature boars with sperm motility higher than 80% was used. An HSP90-specific inhibitor, geldanamycin (GA), was added to diluted semen at 0.5, 1.0, 2.5 or 5.0 microg/mL and the semen was then incubated at 37 degrees C for 15, 30, 45 or 60 min. Sperm motility was determined by using computer-assisted semen analyzer at the end of incubation. The results indicated that GA significantly reduced sperm motility in a dose and time dependent manner. Moreover, incubation of semen with 5.0 microg/mL GA for 15 min completely stopped sperm motility. To test the reversibility of the GA effect on sperm motility, GA was removed after 30 min incubation and was replaced with fresh extender alone or with extender plus 5 mM caffeine, then incubated for another 15, 30, 45 or 60 min. The results showed that simply removing GA did not reverse the inhibitory effect on sperm motility, while adding caffeine partially reversed this inhibitory effect. However, the effect of 2.5 or 5.0 microg/mL GA was not reversed by caffeine. Considering the specificity of GA targeting to HSP90, the above observations suggested that HSP90 may play a crucial role in regulating porcine sperm motility.

Animals↗

PubMed2000

Clinical and microbiological characteristics of bacteremia caused by Acinetobacter lwoffii.

A retrospective study was conducted to analyze the clinical features and pathogenic roles of bacteremia caused by Acinetobacter lwoffii during a 4-year period. Acinetobacter lwoffii (formerly Acinetobacter calcoaceticus var. lwoffii) is recognized as normal flora of the skin, oropharynx and perineum of healthy individuals. There are few reports of Acinetobacter lwoffii bacteremia associated with indwelling catheters in humans, particularly in immunocompromised hosts. The records of 18 patients with Acinetobacter lwoffii bacteremia whose underlying conditions included cancer (11 patients), systemic lupus erythematosus (n=1), chronic obstructive pulmonary disease (n = 2) and other diseases (n = 4), all but one of whom had indwelling catheters during the bacteremic episode, were examined. The clinical syndromes were classified as probable catheter-related bacteremia (n = 14), definite catheter-related bacteremia (n = 2), primary bacteremia (n = 1) or biliary tract infection (n = 1). The infections improved after removal of the catheter and/or appropriate antimicrobial therapy. One death was attributable to the bacteremic event. The results of this study show that indwelling catheter-related Acinetobacter lwoffii bacteremia in immunocompromised hosts appears to be associated with a low risk of mortality.

Acinetobacter Infections↗

PubMed2000

Ultrasound-guided transthoracic biopsy of the chest.

Recent studies have confirmed that US is a very useful diagnostic tool for various diseases of the chest. The image information provided by US is helpful for etiologic diagnosis and clinical management. US-guided needle biopsy provides a precise and safe approach for transthoracic tissue sampling of lesions. The diagnostic yield is high, and the procedure is relatively easy and very safe. Color Doppler US and amplitude US angiography further extend the diagnostic potential and safety of this invasive procedure. Vascular information can be obtained and the needle shaft can be visualized clearly while conducting a biopsy. US examination and US-guided needle aspiration biopsy have now become indispensable diagnostic tools for various chest diseases.

Biopsy, Needle↗

PubMed2000

Reactive pulmonary artery vasoconstriction in pulmonary consolidation evaluated by color Doppler ultrasonography.

A total of 122 patients with pulmonary consolidation on chest radiographs underwent color Doppler ultrasonography to evaluate hemodynamic change in regional pulmonary artery in pulmonary consolidation due to various causes. The diseases underlying pulmonary consolidation included 66 simple pneumonia, 37 obstructive pneumonia, 13 tumor consolidation and 6 pulmonary infarctions. Blood flow signals in consolidation were detected by color-flow mapping. The degree of reactive vasoconstriction was evaluated from analysis of the spectral waveform of the blood flow in the segmental pulmonary artery by several vessel resistance-indicating Doppler ultrasound (US) indices, including pulsativity index (PI), resistive index (RI), and acceleration time (AT). The results showed that reactive vasoconstriction was most marked in obstructive pneumonia, followed by simple pneumonia, and least in tumor consolidation (p < 0.001, Kruskal-Wallis test and p < 0.001, Dunn's test for comparison of PI, RI and AT values between different groups of pulmonary consolidation). No flow was detected in pulmonary infarction. We conclude that color Doppler US is a useful tool for evaluating reactive vasoconstriction in pulmonary consolidation. The different degrees of reactive vasoconstriction may be helpful in exploring the possible etiology of pulmonary consolidation.

Blood Flow Velocity↗

PubMed2000

Serial antinuclear antibodies titre in pleural and pericardial fluid.

The antinuclear antibodies (ANA) test has been a cornerstone of the evaluation of connective tissue disease. The aim of this study was to investigate the diagnostic value of the ANA test in pleural or pericardial effusions of unknown causes. Over a 3-yr period, a total of 126 pleural fluid and 30 pericardial fluid samples were analysed. ANA tests were performed using a commercially available kit. The ANA kit used an indirect immunofluorescent antibody method with a human epithelial (HEP-2) cell line as substrate. Patients with high fluid ANA titre (>1:160) received a second aspiration 2 weeks after the initial aspiration if diagnosis was not confirmed. ANA results were positive in 39 pleural and 10 pericardial fluid samples. All but one of the effusions with positive ANA testing were exudative. Eleven pleural or pericardial effusions due to active systematic lupus erythematosus were identified and all had high ANA titres (1:160) with various staining patterns. Thirty-eight of 145 patients (26%) with effusions of nonlupus aetiologies had positive ANA testing in pleural or pericardial fluid. Thirteen of these 38 patients had high ANA titre. Malignant or paramalignant effusions constituted 11 of the 13 samples. In conclusion, although a negative antinuclear antibodies test makes a diagnosis of lupus serositis unlikely, high antinuclear antibodies titres in pleural or pericardial fluid are not diagnostic of lupus serositis even when as high as 1:5,120. An unexplained high antinuclear antibodies titre in pleural or pericardial effusion warrants search for malignancy.

Adolescent↗

PubMed2000

Quantification of VEGF mRNA expression in non-small cell lung cancer using a real-time quantitative reverse transcription-PCR assay and a comparison with quantitative competitive reverse transcription-PCR.

A reliable quantitative method for measuring gene product expression is important in investigating the relationship between growth factors and tumor biological behavior. In this study, we quantified the expression of vascular endothelial growth factor (VEGF) mRNA in 104 paired samples of lung cancer tissue and the surrounding nontumorous lung tissue using a new kinetic quantitative polymerase chain reaction (PCR) method, ie, real-time quantitative reverse transcription-PCR (RTQ RT-PCR). The samples consisted of 46 squamous cell carcinomas, 50 adenocarcinomas, and 8 undifferentiated cell carcinomas. In 17 cases, the results obtained were compared with those obtained using quantitative competitive RT-PCR (QC RT-PCR). Using RTQ RT-PCR, VEGF mRNA expression was detected and quantified in all 104 (100%) lung cancer samples and their normal counterparts. VEGF mRNA expression in the lung cancer tissue was significantly higher than in the normal counterparts (95% CI: 0.575 approximately 1.727, p < 0.001; paired t test). In 68 (65.4%) cases, VEGF mRNA expression was higher in the cancer tissue than normal tissue. VEGF mRNA expression was higher in nonsquamous cell carcinoma (p = 0.02), and higher in tumor with hilar or mediastinal lymph node metastasis (p = 0.024). QC RT-PCR was able to detect and quantify VEGF mRNA expression in 15/17 (88%) lung cancer samples and 12/17 (70.6%) normal tissue samples. The values for VEGF mRNA expression were higher in the tumor in 13 (76%) cases. Comparison of the values of the VEGF mRNA expression quantified using RTQ RT-PCR or QC RT-PCR showed a good correlation between results obtained using these two methods, both in cancer tissue (r = 0.68, p = 0.0025) and normal counterpart (r = 0.53, p = 0.027). Agreement between the results for the relative expression of VEGF mRNA expression in cancer and normal tissue obtained using these two methods was seen in 14/16 cases (88%). We conclude that RTQ RT-PCR is as accurate as QC RT-PCR and is more sensitive than QC RT-PCR in detecting and quantifying VEGF mRNA expression in lung cancer and normal tissues, and both methods reveal that the VEGF mRNA expression is higher in lung cancer tissue than in healthy lung tissue.

Base Sequence↗

PubMed2000

Active ion secretion and permeability of rabbit maxillary sinus epithelium, impact of staphylococcal enterotoxin B.

The aim of this study was to investigate the impact of staphylococcal enterotoxin B (SEB), a model superantigen, on the physiologic functions of rabbit maxillary sinus epithelium. Rabbit sinus mucosae were separated under a surgical microscope and mounted in Ussing chambers to record short-circuit current, conductance, and permeability to horseradish peroxidase. The results showed that SEB evoked increases in sinus epithelial cell baseline short-circuit current, conductance, and permeability to horseradish peroxidase. When tumor necrosis factor-alpha (TNF-alpha) was added to the Ussing chambers, we got results similar to those obtained by SEB stimulation in vitro; the effects of SEB on sinus epithelial cells could be blocked by pretreatment with anti-TNF-alpha antibody. These results demonstrate that SEB is able to alter the function of sinus epithelial cells and to affect the capability of the epithelial defensive barrier, which may be mediated by TNF-alpha.

Animals↗

PubMed2000

Recurrent bacteremic peritonitis caused by Enterococcus cecorum in a patient with liver cirrhosis.

Enterococcus cecorum (formerly Streptococcus cecorum), originally isolated from poultry intestines, has rarely been encountered in human diseases. A 60-year-old man with liver cirrhosis and hepatocellular carcinoma developed peritonitis on the seventh day of his hospitalization. Cultures of one blood sample and one ascites fluid sample obtained on that day both grew E. cecorum. The patient received intravenous cefoxitin therapy and initially responded well. Unfortunately, another episode of peritonitis associated with septic shock developed 24 days after the start of treatment, and culture of one blood specimen yielded the same organism. The isolates were identified by the conventional biochemical tests, the API Rapid ID 32 Strep system, and the API ZYM system (both systems from bioMerieux, Marcy L'Etoile, France) and were further confirmed by cellular fatty acid chromatography and 16S rRNA gene partial sequencing. The identical biotype, antibiotype, and random amplified polymorphic DNA pattern of the three isolates documented the long-term persistence of this organism in the patient. To the best of our knowledge, this is the first clinical description of recurrent bacteremic peritonitis caused by E. cecorum.

Bacteremia↗

PubMed2000

Recurrent infections and chronic colonization by an Escherichia coli clone in the respiratory tract of a patient with severe cystic bronchiectasis.

A 39-year-old woman with cystic bronchiectasis had repeated pulmonary infections from 1996 to 1999, and 6 of a total of 28 isolates of Escherichia coli from sputum specimens were studied. Their identical antibiotype and randomly amplified polymorphic DNA patterns indicated a single clone of E. coli, which persistently colonized the respiratory tract, causing recurrent infections.

Adult↗

PubMed2000

Glucagon-like peptide-2 enhances intestinal epithelial barrier function of both transcellular and paracellular pathways in the mouse.

BACKGROUND AND AIMS: Glucagon-like peptide-2 (GLP-2) is a recently identified potent intestinotrophic factor. We have evaluated the effect of GLP-2 treatment on intestinal epithelial barrier function in mice. METHODS: CD-1 mice were injected subcutaneously with GLP-2 or a protease resistant analogue, h[Gly(2)]GLP-2, twice daily for up to 10 days. Saline injected mice served as controls. Jejunal segments were mounted in Ussing chambers. Tissue conductance was measured and unidirectional fluxes were determined for (i) Na(+) and the small inert probe Cr-EDTA (both transported via the paracellular pathway) and (ii) the macromolecule horseradish peroxidase (HRP, transported via the transcellular pathway). RESULTS: Mice treated with GLP-2 or h[Gly(2)]GLP-2 for 10 days demonstrated significantly reduced intestinal conductance and fluxes of Na(+), Cr-EDTA, and HRP. Electron microscopy confirmed that GLP-2 reduced endocytic uptake of HRP into enterocytes. Functional changes (evident by four hours) preceded morphological changes (evident by 48 hours). CONCLUSIONS: GLP-2 enhances intestinal epithelial barrier function by affecting both paracellular and transcellular pathways and thus may be of therapeutic value in a number of gastrointestinal conditions.

Animals↗

PubMed2000

US-guided transthoracic cutting biopsy for peripheral thoracic lesions less than 3 cm in diameter.

PURPOSE: To evaluate the safety and accuracy of ultrasonography (US)-guided transthoracic cutting biopsy for diagnosing peripheral thoracic lesions (<3 cm). MATERIALS AND METHODS: Fifty consecutive patients with peripheral thoracic lesions less than 3 cm in diameter underwent US-guided percutaneous transthoracic cutting biopsy with a modified technique. Fifty lesions (43 parenchymal lung, two pleural, two chest wall, and three anterior mediastinal lesions) were sampled for biopsy. The final diagnosis was based on histopathologic analysis of surgical specimens (n = 18) or clinical follow-up (n = 32). RESULTS: The histology recovery rate was 98% (49 lesions), and the correct diagnosis was obtained in 48 lesions (96%). Twenty-four (48%) lesions were malignant, and 26 (52%) were benign. The diagnostic accuracy for malignant lesions was 92% (22 of 24 lesions). A specific benign diagnosis was made in 17 (65%) of the 26 benign lesions, and the negative predictive value for malignancy was 93% (26 of 28 lesions). Only two patients (4%) developed postbiopsy pneumothorax, and three (6%) developed postbiopsy hemoptysis. Biopsy helped prevent surgery or thoracoscopy in 32 patients (64%): 18 patients with benign disease and 14 with multiple metastases or inoperable cancer. CONCLUSION: US-guided transthoracic cutting biopsy appears to be a safe and effective method for diagnosing peripheral thoracic lesions less than 3 cm in diameter. The high diagnostic accuracy for benign lesions and metastatic lung cancer can help prevent surgery in many cases.

Adolescent↗

PubMed2000

Chronic stress impairs rat growth and jejunal epithelial barrier function: role of mast cells.

We examined the impact of chronic stress on rat growth rate and intestinal epithelial physiology and the role of mast cells in these responses. Mast cell-deficient (Ws/Ws) rats and +/+ littermate controls were submitted to water avoidance stress or sham stress, 1 h/day, for 5 days. Seven hours after the last sham or stress session, jejunal segments were mounted in Ussing chambers, in which secretion and permeability were measured. Body weight (as a growth index) and food intake were determined daily. Stress increased baseline jejunal epithelial ion secretion (indicated by short-circuit current), ionic permeability (conductance), and macromolecular permeability (horseradish peroxidase flux) in +/+ rats, but not in Ws/Ws rats, compared with nonstressed controls. Stress induced weight loss and reduced food intake similarly in the groups. In +/+ rats, these parameters remained altered 24-72 h after the cessation of stress. Modulation of stress-induced mucosal mast cell activation may help in the management of certain intestinal conditions involving epithelial pathophysiology.

Animals↗