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Biomedical subjects

S C Wu

Publications and source records attributed to S C Wu.

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

Japanese encephalitis virus antigenic variants with characteristic differences in neutralization resistance and mouse virulence.

Two different plaque variants of Japanese encephalitis virus were selected from a wild-type Taiwanese isolate using Vero cells. One variant was found to exhibit small plaque morphology with retarded virus replication kinetics in Vero cells, and was demonstrated to be resistant to monoclonal antibody (mAb) E3.3 neutralization. The other variant showed large plaque morphology, was sensitive to mAb E3.3 neutralization, and manifested reduced virulence in mice on both intracranial and intraperitoneal inoculations. These two variants propagated in Vero cells retained high levels of infectivity but had relatively low HA titers as compared with the parent strain. The envelope sequences of these two variants showed four amino acid differences at residues E-85 (Glu/Arg), E-306 (Glu/Gly), E-331 (Ser/Arg), and E-387 (Met/Arg). Our results indicated the neutralizing epitope of Japanese encephalitis virus did not overlap with virus virulence determinant.

Animals↗
PubMed1997

The influence of intergenerational exchange on nursing home admission in Taiwan.

This study examines the effect of intergenerational exchange on nursing home admissions among functionally disabled older adults in Taiwan. A group of 317 nursing home residents were randomly selected from all nursing homes in Taipei, the capital of Taiwan. In addition, two community groups were randomly selected as multiple controls in the study. The results showed that intergenerational exchange has a statistically significant effect on nursing home admission after controlling for sociodemographic characteristics and health status. The odds of being admitted into a nursing home was lower for those elderly who provided instrumental assistance to their families before they were disabled. The adjusted relative risk estimate was 0.2 (95% CI = 0.1 - 0.6). It shows that the instrumental assistance the elderly provided to the family before they became disabled was reciprocated when they needed ADL assistance. This finding provides strong support for the social exchange theory.

Journal Article↗
PubMed1997

[Detection of neutralizing antibodies to Japanese encephalitis virus by enzyme-linked immunosorbent assay (ELISA)].

Competitive ELISA was used for the detection of neutralizing antibody to JE. Based on the principle that human serum JE antibody competed with JE monoclonal antibody (MAb) for JE antigen, it was found that 3 JE MAbs (E3-3, NPF-5 and NNN-5) were suitable for competitive ELISA for the detection of JE neutralizing antibody. The sensitivity of cometitive ELISA for 29 JE confirmed serum specimens with titer of plaque reduction neutralization test (PRNT) was checked to be 82.1% (23/28). The specificity of E3-3 MAb to JE used in competitive ELISA was 100%. Correlation coefficient of JE confirmed cases of 57 hemagglutination inhibition (HI) titers in 1995 and 37 PRNT titers in 1994 compared with competitive ELISA were 0.744 and 0.732, respectively. Compared the competitive ELISA titers of 154 sera of healthy people with PRNT titers, the results showed that 70% of the sera could be detected by competitive ELISA which saved a lot of time and manpower.

Antibodies, Viral↗
PubMed1996

Effect of pretreatment counseling on discontinuation rates in Chinese women given depo-medroxyprogesterone acetate for contraception.

The study examined the effect of pretreatment counseling upon discontinuation of 150 mg depo-medroxyprogesterone acetate (Depo-Provera (DMPA)), given for contraception. A total of 421 Chinese women participated, 204 receiving detailed structured pretreatment and ongoing counseling on the hormonal effects and probable side effects of DMPA and 217 receiving only routine counseling. The primary study endpoint was termination rate; secondary endpoints were frequency of medical events and reasons for termination. Study termination rates were significantly lower in the intensive structured counseling group than in the routine counseling group. At one year, the total cumulative termination rates were 11% (23/204) and 42% (92/217), respectively (p < 0.0001). The most common reasons for terminating DMPA were menstrual changes. No pregnancy, serious or unexpected medical events were reported, nor were statistically or clinically significant changes in vital signs observed. We conclude that pretreatment counseling on expected side effects increases the acceptability of DMPA.

Adolescent↗
PubMed1996

A cytopathic infectivity assay of human immunodeficiency virus type 1 in human primary macrophages.

In addition to CD4+ T lymphocytes, cells of monocyte/macrophage lineage are a major target for human immunodeficiency virus type 1 (HIV-1) infection. In vitro studies of HIV-1 infection in human monocyte-derived macrophages can be undertaken by a reproducible cell-based assay. A macrophage-based infectivity assay was developed based on the semi-quantitative scoring of HIV-1 induced cytopathology in monolayer macrophage cultures. The assay exhibited dilution-dependent linearity with all three primary macrophage-tropic isolates tested. The end-point infectivity titers determined by this assay correlated with the results obtained by detecting viral p24 antigen in the culture supernatant. The applications of the assay in both neutralization and anti-viral protocols yielded identical results with the more time-consuming and costly p24 formats. Since the assay offers a simple and low-cost method of measuring HIV-1 infectivity in human primary macrophages, it can be used quite easily for large-scale screening or evaluation of candidate vaccines and anti-viral agents.

Anti-HIV Agents↗
PubMed1996

Transient global amnesia and thalamic hemorrhage.

A left rostral thalamic hematoma was found in a 52-year-old hypertensive man who suffered from a 10-h episode of transient global amnesia (TGA). A neuropsychological study revealed no cognitive impairment in a follow-up period for 5 years. The left rostral part of the thalamus appears to be responsible for his TGA, due probably to an interference of the mamillothalamic tract, ventroamygdalofugal pathway or dorsal noradrenergic bundle.

Amnesia↗
PubMed1996

OKT3 prophylaxis in renal grafts with prolonged cold ischemia times: association with improvement in long-term survival.

The data on patients participating in two randomized, prospective studies with similar immunosuppressive regimens were updated and combined to evaluate the long-term effects of OKT3 according to cold ischemia time (< or = or > 24 hr). Among 159 patients in the OKT3 and 153 in the cyclosporine A (CsA) group, 8 and 12 deaths occurred, respectively (P = NS). In patients with cold ischemia > 24 hours, OKT3 prophylaxis resulted in a lower mean number of rejection episodes per patient than did CsA prophylaxis within one year (mean +/- SEM: 0.87 +/- 0.11 vs. 1.35 +/- 0.14, respectively; P = 0.008) and within five years (1.07 +/- 0.12 vs. 1.49 +/- 0.15, respectively; P = 0.032). In contrast, rejection incidences in patients with cold ischemia < or = 24 hours was not significantly different in the two groups. In all study patients, there was a trend towards higher graft survival rates in the OKT3 group versus the CsA group (at 5 years, 73% vs. 66%, respectively; P = 0.182). Among recipients of kidneys with cold ischemia times > 24 hours, OKT3 patients had significantly higher graft survival than CsA patients at two years (84% vs. 64%, respectively) and at five years (71% vs. 56%, respectively; P = 0.045). Significant differences were not observed in recipients of kidneys with cold ischemia times < or = 24 hours. In conclusion, patients receiving renal grafts with long cold ischemia times strongly benefit from OKT3 prophylaxis.

Adult↗
PubMed1996

A review of nonparametric tests for changepoint problems, with application to a recombinant drug therapy clinical trial.

We review general classes of nonparametric tests for the changepoint problem. We extend these tests to analyze the results of a clinical trial examining whether pretreatment of surgical patients with erythropoietin reduces their subsequent need for blood transfusions. We find a changepoint in baseline hemoglobin levels, below which pretreatment with erythropoietin appears particularly beneficial relative to placebo.

Double-Blind Method↗
PubMed1996

Characterization of an endo-beta-1,4-glucanase gene induced by auxin in elongating pea epicotyls.

A gene (EGL1) encoding an endo-beta-1,4-D-glucanase (EGase, EC 3.2.1.4) of pea (Pisum sativum) has been cloned and characterized. EGL1 encodes a 486-amino acid polypeptide, including a 24-mer putative signal peptide. The mature protein has a calculated molecular mass of 51.3 kD and an isoelectric point of 9.1. This pea EGase shares significant similarity with EGases from other plant species, but it appears to be distinct from the EGases associated with abscission and fruit ripening. Although EGL1 transcripts are detected in all parts of pea plants, they are relatively abundant in flowers and young pods undergoing rapid growth and most abundant in elongating epicotyls of etiolated seedlings. When epicotyl segments (6 mm long, 4 mm from the apical hook) are incubated in a 5 microM solution of the synthetic auxin analog 2,4-dichlorophenoxyacetic acid, the concentration of EGL1 mRNA increases about 10-fold when the segments elongate most rapidly.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1996

Increased excretion of tumor necrosis factor alpha and interleukin 1 beta in urine from patients with IgA nephropathy and Schönlein-Henoch purpura.

Urinary proteins (5 mg/ml) collected from a group of 16 patients including 13 with IgA nephropathy and 3 with Schönlein-Henoch purpura (SHP) and from a control group consisting of 6 patients with diabetic nephropathy, 5 patients with hypertensive nephrosclerosis, and 5 healthy hospital staff members were studied for the contents of interleukins (IL) 1 beta, 2, 4, 6, and 12 and tumor necrosis factor alpha (TNF-alpha). Eleven patient with IgA nephropathy or SHP (11/16) but only 1 of the controls (1/16) had TNF-alpha activity in urinary proteins (p < 0.01). The IL-1 beta activity exhibited a similar tendency but to a lesser extent (10 of 16 patients with IgA nephropathy or SHP vs. 2 of 16 with other conditions, p < 0.05). Conversely, the detection rates of IL-2, IL-4, and IL-6 in both groups were not significantly different. IL-12 was not found in any of the samples from both groups. Sera and nonpurified urine samples from the same individuals were also measured for cytokines. IL-1 beta, IL-2, IL-4, and IL-12 were absent in all these samples, but TNF-alpha was found in four of the serum samples from patients with IgA nephropathy. Urinary proteins (2 mg/ml) were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereby peptides of 52, 49, 45, 34, 30, and 11 kD could be demonstrated in the patients with IgA nephropathy or SHP. Urinary proteins (200 micrograms/ml from patients with IgA nephropathy or SHP exerted a mitogen-like effect on the normal human mononuclear cells, as demonstrated by 3H-thymidine incorporation. In addition, these urinary proteins (400 micrograms/ml) enhanced the proliferative activity of the cultured rat glomerular mesangial cells. The exaggerated proliferation of rat glomerular mesangial cells exerted by urine proteins from 2 patients with active disease was markedly suppressed after treatment with glucocorticoids/cyclophosphamide. These results suggest that patients with IgA nephropathy or SHP can excrete excessive amounts of TNF-alpha and IL-1 beta in the urine. The inconsistent presence of these two cytokines in urine and serum may indicate that they can be produced locally and that they are implicated in the development of mesangial inflammation and glomerular damage.

Adolescent↗
PubMed1996

Large-scale Vero cell culture on microcarriers in a twenty-liter stirred tank fermentor.

In biotechnology, animal cell culture is an important process for the production of many biologicals such as vaccines, monoclonal antibodies, or other recombinant products. Among many established continuous cell lines, Vero cells can be maintained in many passages in cultures without inducing tumorigenicity and have been recommended by World Health Organization for the production of human biologicals. Owing to its anchorage-dependent growth characteristics, Vero cells can be grown on microcarrier in a suspension vessel where microcarrier provides the culture system with a high culture surface to volume ratio. In this paper we compared the growth kinetics of Vero cells on Cytodex 1 microcarrier in a 20-liter fermentor vs. 100 ml spinner flask culture. The kinetics of Vero cell growth in the 20-liter fermentor was similar to the results obtained from small spinner flask culture, as determined by cell specific growth rate or corresponding doubling time. The approximately 150-fold increase in culture vessel volume did not compromise the growth kinetics of Vero cells, suggesting the system is applicable for large stirred-tank fermentor cultures.

Animals↗
PubMed1996

Urinary PCO2 for hemodynamically unstable patients.

BACKGROUND: Gastric intramural pH (pHi) derived from gastric PCO2 has been successfully used to assess splanchnic ischemia for patients with unstable hemodynamics, but with some limitations. Urinary bladder, also an easily accessible hollow viscus, should provide as a useful route for the same purpose. However, no study has used urinary PCO2 to evaluate the adequacy of perfusion in critically ill patients. METHODS: Fifty patients admitted to intensive care unit were included and divided into hemodynamically stable and unstable groups. Several parameters such as arterial pressure, dopamine dosage, heart rate, serum lactate, arterial blood gas, urinary PCO2, and concentrations of Na, K and Cl in urine were measured. Patients with some other renal or pre-renal conditions that might affect urinary PCO2 were excluded. RESULTS: Urinary PCO2 was markedly higher (78.6 +/- 9.9 vs. 43.1 +/- 1.7 mmHg, p < 0.0001) in unstable group. Serum anion gap level, dopamine dosage and heart rate were significantly higher and PaO2/FiO2 ratio as well as mean arterial pressure was lower in unstable group. Serum lactate, arterial pH and other parameters failed to distinguish between groups. Dopamine dosage significantly correlated with urinary PCO2 (r = 0.5357, p = 0.0149) in unstable group. CONCLUSIONS: With careful selection of patients, urinary PCO2 can effectively differentiate hemodynamically unstable patients from stable ones. It also correlates significantly with dopamine dosage in patients with unstable hemodynamics.

Aged↗
PubMed1996

Changepoint statistics for assessing a treatment-covariate interaction.

We formulate a stochastic process approach, related to that of Miller and Siegmund (1982, Biometrics 38, 1001-1016), for comparing two treatments in the setting where a covariate might affect the difference between the treatments. We illustrate the approach with data from a recent clinical trial examining whether pretreating subjects scheduled for major elective surgery with erythropoietin reduces their subsequent requirement for blood transfusion. The approach is valuable in identifying a changepoint in baseline hemoglobin level below which subjects appear to be more responsive to the infusion of erythropoietin.

Analysis of Variance↗
PubMed1996

Pilot study on the effects of a computer-based medical image system.

Current medical imaging systems are developed for the purpose of data management. Evaluations of these systems are usually done by assessing users' subjective appreciation rather than objectively gauging performance influence. The present report discusses the evaluation of a medical image presentation system prototype utilizing a cognitive approach. Experimental results showed hypothesized performance improvement attributed to advanced presentation techniques. However, this improvement was almost inadvertently masked by users' previous strategies and interactions with new technology. Overall these data demonstrate the potential benefit of implementing such a system in actual practice as well as provide an example of applying the cognitive approach in evaluating the usability of medical systems.

Cognition↗
PubMed1995

The P50 evoked potential component and mismatch detection in normal volunteers: implications for the study of sensory gating.

Sensory gating is a complex, multistage, multifaceted physiological function believed to be protecting higher cortical centers from being flooded with incoming irrelevant sensory stimuli. Failure of such mechanisms is hypothesized as one of the mechanisms underlying the development of psychotic states. Attenuation of the amplitude of the P50 evoked potential component with stimulus repetition is widely used to study sensory gating. In the current study, we investigated the responsiveness of the P50 component to changes in the physical characteristics of ongoing trains of auditory stimuli. Forty normal volunteers were studied in a modified oddball paradigm. At all cerebral locations studied, P50 amplitudes were higher in response to infrequent stimuli. We postulate that the increase in P50 amplitude reflects the system's recognition of novel stimuli or "gating in" of sensory input. The ratio of the amplitude of the responses to the infrequent stimuli to those of the frequent stimuli was significantly higher for the posterior temporal regions. This finding provides further evidence that the temporal lobes may be significantly involved in sensory gating processes. Although this study only included normal subjects, the data generated contribute to the understanding of sensory gating mechanisms that may be relevant to psychotic states.

Adolescent↗
PubMed1995

Gene activation by UV light, fungal elicitor or fungal infection in Petroselinum crispum is correlated with repression of cell cycle-related genes.

The effects of UV light or fungal elicitors on plant cells have so far been studied mostly with respect to defense-related gene activation. Here, an inverse correlation of these stimulatory effects with the activities of several cell cycle-related genes is demonstrated. Concomitant with the induction of flavonoid biosynthetic enzymes in UV-irradiated cell suspension cultures of parsley (Petroselinum crispum), total histone synthesis declined to about half the initial rate. A subclass of the histone H3 gene family was selected to demonstrate the close correlation of its expression with cell division, both in intact plants and cultured cells. Using RNA-blot and run-on transcription assays, it was shown that one arbitrarily selected subclass of each of the histone H2A, H2B, H3 and H4 gene families and of the genes encoding a p34cdc2 protein kinase and a mitotic cyclin were transcriptionally repressed in UV-irradiated as well as fungal elicitor-treated parsley cells. The timing and extent of repression differed between the two stimuli; the response to light was more transient and smaller in magnitude. These differential responses to light and elicitor were inversely correlated with the induction of phenylalanine ammonia-lyase, a key enzyme of phenylpropanoid metabolism. Essentially the same result was obtained with a defined oligopeptide elicitor, indicating that the same signaling pathway is responsible for defense-related gene activation and cell cycle-related gene repression. A temporary (UV light) or long-lasting (fungal elicitor) cessation of cell culture growth is most likely due to an arrest of cell division which may be a prerequisite for full commitment of the cells to transcriptional activation of full commitment of the cells to transcriptional activation of pathways involved in UV protection or pathogen defense. This conclusion is corroborated by the observation that the histone H3 mRNA level greatly declined around fungal infection sites in young parsley leaves.

Amino Acid Sequence↗