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Biomedical subjects

C H Wu

Publications and source records attributed to C H Wu.

At least 163 records · Page 9Linked to original sources
PubMed1998

Two-dimensional and three-dimensional power Doppler sonographic classification of vascular patterns in cervical lymphadenopathies.

Vascular patterns may reflect some pathologic behaviors of tumors and lymph nodes. Power Doppler ultrasonography, with improved sensitivity and better noise contrast, were used to depict vasculature in 289 cases of cervical lymphadenopathy. Four patterns of vasculature, in addition to avascular nodes, were classified. Benign lymphadenopathies represented 89% and 83% of avascular and hilar type nodes, respectively. However, malignant lymphadenopathies dominated in nodes that were of spotted (72%), peripheral (60%), and mixed type (80%). Correlation between nodal sizes and chronologic changes of vascular patterns in malignant lymphadenopathies implied a reasonable classification. Three-dimensional power angiography, with the advantage of less plane-sampling bias, was further used to validate our classification.

Angiography↗
PubMed1998

Effects of dexamethasone on antigen expressions and proliferation of amoeboid microglial cells in fetal rat brain.

The present study examined the effect of maternal administration of dexamethasone (DEX) on amoeboid microglial cells (AMC) in fetal rats extending from 16 to 20 days postconception (E16 to E20). After an intraperitoneal injection of DEX into pregnant rats at E10, the external morphology and distribution of immunolabelled AMC as detected with OX-42 and ED1 monoclonal antibodies remained unaltered when compared with those of the controls. The major effect of dexamethasone was on microglial cell population. Thus, with OX-42 and ED1, the numbers of immunolabelled AMC in the intermediate zone lateral to the striatum (IZS) of DEX-treated fetuses which remained relatively unchanged at E16 were significantly reduced at E18. However, OX-42 labelled cells showed an unexpected increase in number at E20 following DEX treatment. Microglial response to DEX was also analyzed in sections stained with the isolectin, GSA I-B4, which specifically binds alpha-D-galactosyl glycoproteins on microglia. The number of GSA I-B4 labelled AMC was significantly increased at E16, declined at E18 and remained constant thereafter in DEX-treated rats when compared with that of the controls. A major finding after DEX treatment was the wider occurrence of AMC double labelled with anti-BrdU antibody and GSA I-B4 or OX-42 at E16 compared with those in the controls suggesting that the initial increase of GSA I-B4 labelled AMC may be attributed to their proliferation. The drastic reduction of OX-42 and ED1 positive microglial cells notably at E18 may be due to the downregulation of surface antigens as a result of possible suppressive action of dexamethasone. On the basis of present findings, it is concluded that the antigenic expressions of fetal AMC may be modulated by DEX administrated maternally. Such however appeared to be extremely selective as reflected by the varied expression for certain immune molecules at different stages of brain development. This information would be useful in potential use of glucocorticoids in prenatal therapy of brain pathology via maternal circulation.

Animals↗
PubMed1998

[Properties of the GM-CSF-induced outward K+ current in murine peritoneal exudate macrophages].

Whole-cell patch-clamp technique was used to study the changes of ionic currents in murine peritoneal exudate macrophages (PEMs) prestimulated with granulocyte-macrophage colony-stimulating factor (GM-CSF, 16 ng/ml) for periods from 0.5 up to 6 d. The GM-CSF-treated PEMs developed a GM-CSF-induced transient inactivating outward K+ current (IA). IA showed steady-state inactivation over the physiological voltage range and possessed frequency dependence of inactivation when depolarizing pulses were applied at a frequency of 0.5 Hz. IA was selectively inhibited by extracellular 4-AP (3 mmol/L). When [Ca2+]i was increased (from pCa 8 to 6), the amplitudes of IA were depressed significantly. When the PEMs were exposed to cycloheximide (0.3 microgram/ml), a protein synthesis inhibitor, for 12 h, IA expression was completely suppressed. It was notable that the changes of the current expression, activation behavior and kinetic properties occurred during GM-CSF treatment. When PEMs were pretreated for a 2-d period, the frequency of IA expression reached a peak value (55% in a total of 27 cells), PEMs exhibited the highest density of the corresponding channel proteins, half-maximal activation of IA was most easily achieved with a value of -27.55 mV, and the time course of activation and inactivation during depolarization proceeded rapidly. However, along with continuous incubation with GM-CSF, the number of PEMs expressing IA decreased, the channel proteins were down regulated constantly, the activation curve for IA shifted to positive potentials, and the activation time and inactivation time of IA slowed down. These results indicated that GM-CSF could induce a transient inactivating outward K+ current in PEMs, which may have a close relation to the state of functional activation of macrophages primed with GM-CSF.

Animals↗
PubMed1998

Colonofiberscopic diagnosis of intestinal tuberculosis.

The purpose of this study was to assess the predictive value of colonofiberscopy in the diagnosis of intestinal tuberculosis. The records of more than 14,000 colonofiberscopic examinations performed at the National Taiwan University Hospital from 1971 to 1995 were studied retrospectively. Colonofiberscopic diagnosis of intestinal tuberculosis required at least one of the following: circumferential ulcers, a single transverse axis ulcer with uneven base and elevated or nodular margin surrounded by nodular and hyperemic mucosa, or pseudopolyps. Sixty cases were diagnosed as intestinal tuberculosis based on these criteria, 29 of which were confirmed by histologic or bacteriologic findings or on the basis of clinical response to antituberculosis therapy. The positive predictive value of colonofiberscopy for intestinal tuberculosis was thus 43.3% (95% confidence interval 31-57%). Secondary intestinal tuberculosis with pulmonary tuberculosis accounted for 84% of cases. The most commonly involved area of the gastrointestinal tract was the ileocecal region, followed by the ascending colon and ileum. Based on our findings, colonofiberscopic examination with histopathologic and bacteriologic study of biopsy specimens is a powerful tool for the diagnosis of intestinal tuberculosis.

Adolescent↗
PubMed1998

Proclass protein family database: new version with motif alignments.

ProClass is a protein family database which organizes non-redundant sequence entries into families defined collectively by the ProSite patterns and PIR superfamilies. The database consists of about 100,000 entries, more than half of which are classified in about 3,000 families. The new version includes links to various protein family/domain and structural class databases and contains gapped motif alignments for all ProSite patterns. The motif sequences are retrieved from both SwissProt and PIR-international databases, including numerous new members detected by our GeneFIND family identification system. The motif collection represents a 50% increase from those catalogued in ProSite. The ProClass database can be used to maximize family information retrieval, help organize protein sequence databases, and support full-scale genomic annotation. The database and its query program are freely available for on-line record retrieval and direct file transfer from our WWW server at http:/(/)diana.uthct.edu/proclass.html+ ++.

Amino Acid Sequence↗
PubMed1998

One-week low-dose triple therapy is effective in treating Helicobacter pylori-infected patients with bleeding peptic ulcers.

Proton pump inhibitor (PPI)-based triple therapy, which combines a PPI and two antibiotics, is highly effective in eradicating Helicobacter pylori infection in peptic ulcer patients, even if given for only 1 week. However, the application of this regimen in patients with bleeding ulcers has not been adequately investigated. We studied the effectiveness of triple therapy in treating 122 patients with proven H. pylori infection, and bleeding stigmata on endoscopy; 97 had duodenal ulcer (DU), 15 had gastric ulcer (GU), and 10 had both types of ulcers. A regimen of omeprazole (20 mg), metronidazole (500 mg), and clarithromycin (250 mg) twice daily was administered for 1 week as soon as the patient could eat normally after bleeding, followed by omeprazole (20 mg) daily for 3 additional weeks. Follow-up endoscopy and 13C-urea breath tests (UBTs) were performed at least 4 weeks after triple therapy. A total of 104 patients completed the study, 83 with DU, 12 with GU, and nine with both. The overall ulcer healing rate was 97.1% and the eradication rate was 91.3%. Patients with and without H. pylori eradication did not differ significantly in terms of age, gender, UBT titer, units of blood transfused, or interval between endoscopy and the beginning of triple therapy. We conclude that 1-week low-dose PPI-based triple therapy is effective in eradicating H. pylori infection in patients with bleeding peptic ulcers. When followed by 3 weeks of additional PPI treatment, a satisfactory ulcer healing rate can also be achieved.

Adult↗
PubMed1997

Palytoxin-induced single-channel currents from the sodium pump synthesized by in vitro expression.

Palytoxin, the most potent animal toxin, is proposed to convert Na+/K(+)-ATPase into a cation-selective ion channel. Because of the ubiquity of pumps and channels in the living tissues used to study its mechanism of action, it is difficult to rule out that another site may be involved. In order to show that palytoxin selectively acts on Na+/K(+)-ATPase, two entirely in vitro methods were employed: (1) a cell-free expression system to synthesize the rat alpha 3 and beta 1 subunit proteins, and (2) single-channel recording of the synthetic Na+/K(+)-ATPase reconstituted in a planar lipid bilayer. Upon addition of palytoxin, single-channel currents were induced which had a conductance of 10 pS, in agreement with previous studies. In control experiments, when the cDNAs for Na+/K(+)-ATPase subunits were omitted, no single-channel currents were induced with palytoxin. Thus, the results show unambiguously that the Na+/ K(+)-ATPase is the site of action for palytoxin. Because palytoxin turns the Na+/K(+)-ATPase into a channel which can be detected by the exquisitely sensitive single-channel recording technique, the present results are the first to demonstrate the activity of in vitro synthesized Na+/K(+)-ATPase.

Acrylamides↗
PubMed1997

Artificial neural networks for molecular sequence analysis.

Artificial neural networks provide a unique computing architecture whose potential has attracted interest from researchers across different disciplines. As a technique for computational analysis, neural network technology is very well suited for the analysis of molecular sequence data. It has been applied successfully to a variety of problems, ranging from gene identification, to protein structure prediction and sequence classification. This article provides an overview of major neural network paradigms, discusses design issues, and reviews current applications in DNA/RNA and protein sequence analysis.

Algorithms↗
PubMed1997

Sequencing and immunochemical characterization of the American cockroach per a 3 (Cr-PI) isoallergenic variants.

Two additional members of the American cockroach (Periplaneta americana) Per a 3 (Cr-PI) allergen, C13 and C28, were isolated and sequenced. They encoded proteins of 470 and 393 amino acids with two and no potential N-glycosylation sites, respectively. The molecular weights for C13 and C28 cloned proteins are 56,200 and 46,7000, with PI values of 7.06 and 6.54. C13 and C28 display 95.4% identity with several overlapping predicted central antigenic determinants. Both allergens were also found to have a 95% sequence homology with previously cloned C20 and share similar antigenic determinants, as defined by the structural prediction and ELISA analysis. However, the recombinant C13 and C28 allergens showed 26.3 and 94.7% skin reactivities on asthmatic patients while C20 elicited 47.4%. While no sequence similarity was found to other known allergens, these two aromatic amino acid-rich allergens were highly related to insect hemolymph proteins (28.7-36.5%), as with C20 cloned protein. Results suggest that these two are isoallergenic variants of C20. Sequence variations among isoforms, resulting a significant difference in skin reactivities, will be useful in elucidating the allergenic determinants.

Adolescent↗
PubMed1997

Response of amoeboid and ramified microglial cells to lipopolysaccharide injections in postnatal rats--a lectin and ultrastructural study.

The present study describes the response of amoeboid and ramified microglial cells in the corpus callosum to intraperitoneal lipopolysaccharide injections in postnatal rats as examined by lectin histochemical staining and electron microscopy. In 1 day old rats receiving endotoxin injections and sacrificed at various time intervals, the lectin labelling of amoeboid/ramified microglia was greatly enhanced. The increased labelling persisted in some ramified microglia in rats killed at 14 and 21 days of age; otherwise in normal or control animals of the corresponding stages, the same cells were very weakly stained. In rats killed at 2 days of age after intraperitoneal lipopolysaccharide injection, the number of microglia appeared to increase, but this was reduced at 7 days of age. The lectin-labelled amoeboid/ramified microglia were frequently seen adherent to the outer walls of the callosal blood vessels where infiltrated lymphocytes were also observed. Ultrastructurally, some lectin-labelled microglial cells underwent degeneration and were engulfed by other lectin-positive cells. After endotoxin injections, microglial cells, notably the amoeboid form, showed extensive ruffling at their cell membrane, massive accumulation of lysosomes and increased staining of lectin at their Golgi apparatus. A similar lectin labelling pattern was also observed in ramified microglia of lipopolysaccharide-injected rats. It is concluded that both amoeboid and ramified microglial cells in postnatal rats responded to endotoxin injections as reflected by their enhanced lectin labelling at the surface membrane, lysosomes and Golgi apparatus. It is suggested that such changes may be involved in synthesis and/or modification of galactosyl glycoconjugates probably for the increased production of membranous glycoproteins or lysosomal enzymes.

Animals↗
PubMed1997

Heterogeneity of antigen expression and lectin labeling on microglial cells in the olfactory bulb of adult rats.

Microglia in different layers of the rat olfactory bulb expressed a variety of membrane antigens except for CD4 (OX-35). Bulb microglial cells bearing complement receptor type 3 (OX-42) were ubiquitous and their immunoreactivity varied considerably in different bulb layers. Although very few in number, labeled microglia in all layers also expressed major histocompatibility complex class I antigen (OX-18), leukocyte common antigen (OX-1) and unknown macrophage antigen (ED-2). The latter was localized in cells distributed almost exclusively in the perivascular spaces. The immunoreactivity of ED-1, an unknown cytoplasmic or lysosomal membrane antigen in macrophages, was localized in labeled microglia which were concentrated mainly in the granule cell layer and periglomerular zone of the bulb. A variable number of microglial cells were stained with OX-6 (major histocompatibility complex class II antigen) and they were located predominantly in the periglomerular zone and at the junction between the granule cell layer and the subependymal layer. Ultrastructural study using GSA I-B4 lectin labeling showed that microglia in different layers of the bulb exhibited similar labeling patterns in their subcellular structures. A remarkable feature was the occurrence of some microglia in the olfactory nerve layer, subependymal layer and granule cell layer adjacent to the subependymal layer in which the cells showed intense lectin labeling at their Golgi apparatus, a feature which was absent in microglia of other bulb layers. Present results showed the regional differences in microglial antigen expressions and lectin labeling within the olfactory bulb. It is therefore suggested that the cells subserve very different specific functions depending on their ambient microenvironments. The heterogeneity of microglial functions in the olfactory bulb may be related to the progressive regeneration and degeneration of its containing neurons.

Animals↗
PubMed1997

Leptospirosis: an ignored cause of acute renal failure in Taiwan.

Leptospirosis, caused by a spirochete, is the most common zoonosis in domestic or wild animals. Animals excrete infected urine in soil or water and may cause human infections through abrased wound, mucosa, conjunctiva, or by swallowing contaminated water. Clinical presentations of leptospirosis are mostly subclinical. Five to ten percent of leptospirosis are fatal, causing fever, hemorrhage, jaundice, and acute renal failure (Weil's syndrome). Leptospirosis has been ignored as a cause of acute renal failure in Taiwan. We report two patients with leptospirosis who presented with high fever, abdominal pain, jaundice, and acute renal failure. Patient 1 died on day 12 of admission of multiple organ failure associated with pancytopenia, hypogammaglobulinemia, and reactive hemophagocytosis. Leptospirosis was recognized after death. Patient 2 was admitted with similar presentations 2 weeks later. Penicillin and doxycycline were given early in the course, and azotemia, jaundice, respiratory failure, and aseptic meningitis gradually improved. Renal biopsy showed interstitial nephritis. Several tubular clearance tests showed proximal tubular defect with severe bicarbonate wasting (FeHCO3- 20.9%) and incomplete type II renal tubular acidosis without affecting the distal nephron. After 80 days of treatment, this patient was discharged with recovery of conscious level and renal function. This is the first leptospirosis patient with detailed tubular functional and morphological studies of the kidney. Diagnosis of leptospirosis was made by microscopic agglutination test (MAT) for antibody to leptospira and by polymerase chain reaction (PCR) for leptospira DNA in blood and urine (interrogans serogroup australis in case 1 and Leptospira borgpetersenii serogroup ballum in case 2). Because active surveillance has resulted in 13 cases diagnosed as leptospirosis islandwide thereafter, underestimation and ignorance of leptospirosis as a cause of acute renal failure may occur in Taiwan. Therefore, an area with a low leptospirosis incidence may actually have a very high incidence. Leptospirosis should be suspected in febrile patients with jaundice and renal failure when pathogens cannot be identified by traditional culture for microorganisms.

Abdominal Pain↗
PubMed1997

Molecular cloning and nucleotide sequencing of bioF (7-keto-8-amino pelargonic acid synthetase), bioC and bioD (dethiobiotin synthetase) genes of Erwinia herbicola.

The biotin operon of Erwinia herbicola Eho 10 was cloned and characterized by complementation of E. coli biotin mutants. The operon was found to contain five genes arranged in the order, bioABFCD. The nucleotide sequences of bioF (7-keto-8-aminopelargonic acid synthetase), bioC and bioD (dethiobiotin synthetase) were determined and analyzed. The nucleotide sequences and deduced amino acid sequences of bioFCD were compared with the corresponding sequences from Escherichia coli, Bacillus sphaericus, Serratia marcescens and Brevibacterium flavum.

Acyltransferases↗
PubMed1997

Poor pre-dialysis glycaemic control is a predictor of mortality in type II diabetic patients on maintenance haemodialysis.

BACKGROUND: In type II diabetic patients, a better glycaemic control has been reported to slow down the progression of nephropathy. The effect of pre-dialysis glycaemic control on the long term prognosis in type II diabetics on haemodialysis is still uncertain. The purpose of this study is to evaluate the effect of glycaemic control before starting maintenance haemodialysis on the clinical outcome in type II diabetic haemodialysis patients. METHODS: One hundred and thirty-seven type II diabetics receiving regular haemodialysis in a single university hospital were enrolled. The patients were classified as either good or poor glycaemic control group according to their glycaemic control within 6 months before starting haemodialysis. Serum albumin, haematocrit, cholesterol, triglyceride, residual renal function, diabetic complications, and patient survival were analysed in both groups. RESULTS: There was no significant difference in age, gender, predialysis albumin level, cholesterol level, triglyceride level, and residual renal function between the two groups. The 1-year (94.5% vs 80.0%), 3-year (82.9% vs 58.1%), and 5-year (75.8% vs 21.8%) cumulative survival rates were lower in the poor glycaemic control group than in the good glycaemic control group (P < 0.001). The poor glycaemic control group also had more cardiovascular morbidity during the period of dialysis (P < 0.001). The increase in cardiovascular complications also accounted for the increased mortality during the course of haemodialysis. CONCLUSIONS: We conclude that poor glycaemic control before starting dialysis is a strong predictor of cardiovascular morbidity and survival for type II diabetics on haemodialysis. These results imply that better glycaemic control before dialysis might be important in improving the long-term prognosis in type II diabetics on haemodialysis.

Aged↗
PubMed1997

Evaluation of swallowing safety with fiberoptic endoscope: comparison with videofluoroscopic technique.

Videofluoroscopy has long been viewed as the "gold standard" of swallowing examination for the comprehensive information it provides. However, it is not very efficient and accessible in some practical situations. In this study, we tried to use a modified technique of fiberoptic endoscopic examination of swallowing (FEES) in evaluating dysphagic patients. For each examination, a spoonful of pudding and dyed water were fed in sequence three times. The pharyngeal swallowing events were observed with fiberscope panoramically and videotaped. Twenty-eight chronic dysphagic patients underwent both videofluoroscopy and FEES in 2 weeks. Comparison of the results revealed that disagreements in premature oral leakage to the pharynx, pharyngeal stasis, laryngeal penetration, aspiration, effective cough reflex, and velopharyngeal incompetence were 39.3%, 10.7%, 14.3%, 14.3%, 39.3%, and 32.1%, respectively. FEES was found to be more sensitive in detecting these risky features of swallowing, except with respect to premature leakage. Possible causes of the discrepant results are discussed, and the limitation of videofluoroscopy in practical usage is discussed. FEES is conclusively a safer, more efficient, and sensitive method than videofluoroscopy in evaluating swallowing safety.

Adult↗
PubMed1997

Weighted least-squares reconstruction methods for positron emission tomography.

We present unpenalized and penalized weighted least-squares (WLS) reconstruction methods for positron emission tomography (PET), where the weights are based on the covariance of a model error and depend on the unknown parameters. The penalty function for the latter method is chosen so that certain a priori information is incorporated. The algorithms used to minimize the WLS objective functions guarantee nonnegative estimates and, experimentally, they converged faster than the maximum likelihood expectation-maximization (ML-EM) algorithm and produced images that had significantly better resolution and contrast. Although simulations suggest that the proposed algorithms are globally convergent, a proof of convergence has not yet been found. Nevertheless, we are able to show that the unpenalized method produces estimates that decrease the objective function monotonically with increasing iterations.

Algorithms↗
PubMed1997

Analysis of cross-reactive allergens from American and German cockroaches by human IgE.

Serum from atopics hypersensitive to the American cockroach were examined for their specific IgE to American and German cockroaches by the fluoroallergosorbent test (FAST). Of 44 sera tested, 86.4% (38/44) contained IgE to American and German cockroaches, and 13.6% (6/44) were found to be positive for American cockroach alone by FAST. Nine individual sera containing IgE antibodies to both cockroaches were used to analyze the cross-reacting allergens in the crude American and German cockroach extracts by FAST inhibition and immunoblotting FAST-inhibition studies showed various degrees but similar inhibition of binding of human IgE to solid-phase American cockroach extract. Proteins from both cockroach extracts were separated on SDS-PAGE followed by immunoblotting, and the results showed considerable heterogeneity in the IgE-binding patterns with each of the cockroach extracts for the same nine individual sera. Components with apparent molecular weights of 60, 52, 49, 38, and 12 kDa from both the American and German cockroaches were able to bind IgE antibody. These results suggest the presence of cross-reactive allergens in the American and the German cockroaches.

Adolescent↗