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S T Wang

Publications and source records attributed to S T Wang.

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

Consequences of analysing complex survey data using inappropriate analysis and software computing packages.

In the analysis of complex survey data such as stratified multi-stage cluster samples, ignoring the design effects such as clustering and stratification usually will lead to erroneous conclusions. In this paper, we will demonstrate the consequences in the estimation of means and proportions by two examples from a stratified two-stage cluster sample. A brief review of methodology will be presented, and some suggestions on computational issues will be provided.

Adult↗
PubMed1997

Methionine and cysteine affect glutathione level, glutathione-related enzyme activities and the expression of glutathione S-transferase isozymes in rat hepatocytes.

Methionine and cysteine are constituents of glutathione. To understand the effects of these two sulfur amino acids on the glutathione (GSH)-dependent detoxification defense system, intracellular GSH and GSH-related enzyme activities, including GSH peroxidase, GSH reductase, GSH S-transferase (GST) and gamma-glutamylcysteine synthetase, were determined. In addition, the expression of three GST isozymes and carbonic anhydrase III (CA III) was examined. Hepatocytes isolated from male Sprague-Dawley rats were cultured with 0.1, 0.3, 0.5 or 1.0 mmol/L each of L-methionine and L-cysteine, for up to 7 d. Cells incubated with 0.5 or 1.0 mmol/L methionine and cysteine had increased intracellular GSH. A twofold increase was observed on d 6 compared with freshly isolated hepatocytes (P < 0.05). However, intracellular GSH was lower in cells treated with 0.3 or 0.1 mmol/L each of methionine and cysteine than in cells tested with 0.5 or 1.0 mmol/L. Although the GSH level differed significantly between cells cultured with 0.3 or 1.0 mmol/L of methionine and cysteine, GSH-related enzymes did not differ at these two concentrations. The activity generally remained constant for the first 24 h, then increased up to d 4. Immunodetection analysis revealed no difference in the level of CA III and GST isoforms, Ya, Yb and Yp, with amino acids each at a concentration of at least 0.3 mmol/L. Yp expression steadily increased up to d 7. Most proteins decreased rapidly after 48 h when cultured with 0.1 mmol/L of methionine and cysteine; however, the Yp level increased up to d 6. In conclusion, results indicate that a twofold increase of intracellular GSH is reached by adding methionine and cysteine at a concentration >0.5 mmol/L to the culture medium. The concentrations of methionine and cysteine for maintaining hepatic GSH are higher than for GSH-related enzyme activity and for GST isoform expression.

Amino Acids, Sulfur↗
PubMed1997

Aspirin improves uterine blood flow in the peri-implantation period.

A prospective clinical study at the Infertility Clinic of National Cheng Kung University Hospital investigated the effect of aspirin on infertile women with impaired uterine perfusion. A total of 127 women with unexplained infertility or repeated failure with various assisted-conception techniques were enrolled. Uterine perfusion was assessed by Doppler ultrasound and classified as normal or impaired (pulsatility index < 3.0 or > or = 3.0, respectively). One-third (43/127) of the women were found to have impaired uterine perfusion during their menstrual cycles. Those with impaired uterine blood flow were given aspirin (100 mg/day) starting on day 3 of the next ovulatory cycle. Only 36 women completed both the screening and the aspirin-treated cycles. The pulsatility index was measured in the natural and aspirin-treated cycles in the same group of women and compared using repeated measures analyses of variance. A significant improvement in the uterine blood perfusion (p < 0.05) was detected on the day leutinizing hormone peaked and in the midluteal phase (peri-implantation period) of aspirin-treated cycles. Thus, the use of low-dose aspirin may improve uterine perfusion in women with unexplained infertility and impaired uterine blood flow.

Adult↗
PubMed1997

Receiver operating characteristic plots to evaluate Guthrie, Wallac, and Isolab phenylalanine kit performance for newborn phenylketonuria screening.

We used ROC plots to evaluate the clinical performance of the Guthrie, Wallac, and Isolab assays for newborn phenylketonuria (PKU) screening and assessed the screening discriminatory power of these three assays by the area under the ROC plot, Youden's J index, and the likelihood ratio. The use of these plots not only allows us to pinpoint the exact cutoff value in screening, but also provides a direct comparison of these three different assays in clinical outcome performance. The optimum cutoff for the newborn PKU screening is a blood phenylalanine concentration of 0.30, 0.27, and 0.18 mmol/L for the Guthrie, Wallac, and Isolab assays, respectively. We conclude that the Wallac and Isolab kits, like the Guthrie assay, are suitable for newborn PKU screening.

Humans↗
PubMed1997

Surgical treatment of seat belt type injury of the thoracolumbar spine.

BACKGROUND: Seat belt type injury of thoracolumbar spine is an uncommon injury characterized by disruption of the posterior elements of the spine. The fracture has long been treated conservatively, but progressive kyphotic deformity developed frequently. METHODS: From January, 1991 through December, 1992, 10 cases of seat belt type injury of the thoracolumbar spine were encountered at our hospital with an incidence of 8% in overall spinal fractures. Of these patients, eight patients were male and two were female, average age 30.7 years old. The causes included motor-vehicle accident in five patients, fall from height in four, and stricken by a falling electric pole in one. None of the victims of motor vehicle accidents wore seat belt. All of them received open reduction, posterior internal fixation and posterior fusion. RESULTS: After follow-up for an average of 42.2 months, the average kyphotic angulation was 5.7 degrees. Back pain and function of these patients were all rated good. None of them suffered from neurologic deficit. One patient with breakage of transpedicular screws was encountered during follow-up, but there was no complaint. CONCLUSIONS: In treating seat belt type injuries of spinal column, benefits of operation outweigh the risks. Besides, the clinical result is satisfactory and more aggressive surgical approach should be encouraged.

Accidents, Traffic↗
PubMed1996

Vitamin E protection of cell morphology and protein thiols in rat hepatocytes treated with tert-butyl hydroperoxide.

Effects of vitamin E on cell morphology and cellular protein thiols under oxidative stress was investigated in cultured rat hepatocytes with different vitamin E status. Hepatocytes were incubated in the presence or absence of 100 microM alpha-tocopherol succinate for 24 h then treated with 1.5 mM t-butyl hydroperoxide (t-BH) for different time intervals. Lipid peroxidation, as determined by thiobarbituric acid-reactive substances, was completely inhibited over 60 min of treatment in cells incubated with alpha-tocopherol. The change of cell morphology, as determined by surface blebs formation, was correlated with cellular vitamin E status. Surface blebs were formed in 25.1 +/- 5.2 min in the presence of alpha-tocopherol in contrast to 11.1 +/- 2.9 min in its absence. In cells with alpha-tocopherol, surface blebs were induced even though lipid peroxidation was inhibited. Comparing the depletion of membrane protein thiols with t-BH treatment, twice as many (40%) thiols were lost over 60 min in the absence of alpha-tocopherol whereas 20% were lost in the presence of alpha-tocopherol. In addition, the extent of thiol modification of carbonic anhydrase III, as determined by combining isoelectric focusing analysis with immunoblotting, further demonstrated that alpha-tocopherol helps maintain protein thiols in the reduced state. Results indicate that vitamin E protects cell morphology and prevents the loss of protein thiols with t-BH treatment, and on cell morphology protection is associated with protein thiols rather than membrane lipids.

Animals↗
PubMed1996

Glutathione and glutathione-related enzyme activities of male and female rat hepatocytes under various culture conditions.

The effect of culture medium on glutathione (GSH) dependent detoxification defence system of primary cultured hepatocyte from either male or female rats was studied. Intracellular reduced (GSH) and oxidized glutathione (GSSG), and six GSH-related enzyme activities, including GSH peroxidase (GSH Px), GSH reductase (GSH Rd), cytosolic GSH S-transferase (cGST), microsomal GSH S-transferase (mGST), gamma-glutamyl transpeptidase (GTP), and gamma-glutamylcysteine synthetase (GCS), were investigated during a 6-day culture. Media free of fetal bovine serum (FBS) and with 2.5 or 10% FBS were used. Whatever the medium, there was an initial decrease of intracellular GSH and GSSG, a threefold increase of GSH at day 3 and fourfold increase of GSSG at day 4, later decreasing to their original level at day 6. The activities of all six GSH-related enzymes of male and female hepatocytes remained relatively stable during the first 72h, then gradually decreased to 50-80% of initial activities. With the exception of cGST, time-course profiles of other enzyme activities were not significantly different among various media. In both sexes, higher cGST activity was maintained for cells cultured in the presence of FBS. Results of immunoblotting analysis of cytosolic GST isozymes indicate that the placental form of GST (Yp) was markedly increased after plating and the extent of increase of Yp was higher in the presence of FBS. Despite the culture medium, the level of GST isoform Ya was maintained steadily for 6 days, however, Yb was maintained during the first 3 days and then decreased. In terms of the gender difference, GSH Px and GTP activities of hepatocytes from females were significantly greater than of males over the entire culture period. Results indicate that FBS seems not to be absolutely essential in maintaining GSH level and most of the GSH-related enzyme activities in rat hepatocytes. Furthermore, GSH levels and GSH-related enzyme activities of hepatocytes from female rats were similar to those from male rats.

Aminoacyltransferases↗
PubMed1996

The detection of S-glutathionation of hepatic carbonic anhydrase III in rats treated with paraquat or diquat.

Protein S-glutathionation has been demonstrated to be one of the cellular responses under oxidative stress and may be involved in many cellular metabolisms. In this study, the effect of redox cycling bipyridylium compounds, paraquat and diquat, on this protein modification was investigated. Male Sprague-Dawley rats were administered i.p. either paraquat at 20 or 40 mg/kg body wt. or diquat at 85 or 170 mg/kg body wt., respectively. The liver was examined at different time points for taking the measurement of the S-glutathionation of carbonic anhydrase III (CA III), thiobarbituric acid-reactive substances (TBARS), vitamin E depletion, glutathione (GSH) and glutathione disulfide (GSSG) contents. The extent of S-glutathionation of CA III was chosen as a marker and was determined by a method combining isoelectric focusing analysis with immunoblotting. Those results indicated that paraquat and diquat significantly increased the generation of TBARS and showed a time-dependent response. The significant effect on vitamin E depletion was only obtained in rats treated with a high dose of diquat for 2 h. Hepatic cellular GSSG contents did not increase but tended to decrease all of the treatments. Although oxidative damage was actually generated in liver, based on the increase of TBARS generation and vitamin E depletion, no increase of CA III S-glutathionation was observed. We propose that the reason for this observation under this circumstance is probably due to the reversible characteristic of CA III S-glutathionation, which has been demonstrated in our previous study (Chai et al., 1991) Arch. Biochem. Biophys. 384, 270-278) and named as dethiolation.

Animals↗
PubMed1996

Regulatory effects of dietary n-3 and n-6 lipids on plasma and hepatic lipid levels, liver cell number and microsomal protein content in spontaneously hypertensive rats.

Weanling male spontaneously hypertensive rats were fed semipurified diets containing either corn or fish oil for 8 weeks. Rats fed on fish oil diet had significantly lower plasma triglyceride, total cholesterol and HDL-cholesterol levels than rats fed on corn oil diet (P < 0.05). Moreover, rats fed on fish oil diet had significantly lower liver total lipid and triglyceride concentrations than rats fed on corn oil diet (P < 0.05). Dietary lipids were reflected in plasma fatty acid composition. Rats fed on fish oil diet had significantly greater plasma eicosapentaenoate (EPA) and docosahexaenoate (DHA) (n-3 PUFAs) with an accompanying decrease in plasma linoleate (LA) and arachidonate (AA) (n-6 PUFAs), in comparison with the rats fed corn oil (P < 0.05). Those results would suggest that the n-3 PUFAs were incorporated into plasma lipids at the expense of the n-6 PUFAs. Rats fed on corn oil diet had significantly greater liver DNA content than rats fed on fish oil diet (P < 0.05), thereby implying that the n-3 PUFAs in fish oil had an inhibitory effect on liver cell proliferation. Furthermore, rats fed on fish oil diet had significantly greater hepatic microsomal protein content than rats fed on corn oil diet (P < 0.05), indicating that fish oil exerted a stimulatory effect on hepatic microsomal enzymes.

Animals↗
PubMed1996

Patellar dislocation after total knee arthroplasty.

BACKGROUND: Patellar problem is an important cause of nonseptic failure of the current condylar design of total knee arthroplasties. Patellar dislocation after total knee arthroplasty is infrequent but can cause disabling symptoms. METHODS: From March, '84 to July, '92, 1652 total knee arthroplasties were performed at this Hospital. Of these 1100 knees in 978 patients were available to be followed up regularly at the Outpatient Department. Eleven cases of patellar dislocation after total knee arthroplasty were encountered during follow-up. Among these patients, nine patients had received operation at this Hospital; the other two patients had been referred here by the other hospitals. All 11 patients had been treated with surgical methods: proximal realignment of the quadriceps alone in 6 knees, lateral retinacular release combined with revision of the malaligned components in 2 knees, combined proximal and distal realignment in 2 knees and patellar tendon transfer in 1 knee. RESULTS: After an average follow-up of 21.8 months, from April, '84 to April, '93, there was one redislocation, unfortunately caused by trauma. Using the average knee rating scale of the Hospital for Special Surgery, New York, USA, the results of 90.5 were satisfactory and encouraging. CONCLUSIONS: Patellar dislocation after total knee arthroplasty can cause disabling symptoms, including pain, weakness, limited range of motion, extension lag and difficulty when climbing up or down stairs. The cause of patellar dislocation after total knee arthroplasty was error in surgical technique in this series. Revision of the component should be performed in those with malaligned component. Proximal realignment is recommended in those with quadriceps imbalance. Distal realignment is recommended only when proximal realignment alone has failed to restore proper patellar tracking, this should be carried out with great caution due to the potential for serious complications.

Aged↗
PubMed1996

Acute monteggia fractures in children.

BACKGROUND: Monteggia fracture rarely occurs in children. If it occurs, type I fracture is most commonly seen. We study the functional results of nonsurgical management in acute cases. METHODS: From July, 1988 through October, 1994, we encountered 15 cases of acute Monteggia fractures, accounting for 2.3% of forearm fractures. Twelve were males and three were females, at an average age of 7 years and 10 months. Nine fractures occurred on left non-dominant side, six occurred on right dominant side. There were eleven type I (73.3%), no type II, three type III (20%), and one type IV (6.7%) fractures. All of these patients received closed reduction with long arm casting, and the most stable position of fracture was supination of the forearm and flexion of the elbow. RESULTS: After follow-up for an average of 45.9 months, all fractures were found to unite without residual deformity of ulna or dislocation of the radial head. The functional results were excellent. Posterior interosseous nerve palsy occurred in one patient before treatment, and recovered spontaneously. CONCLUSIONS: Unlike adults, children with Monteggia fractures can get excellent results from closed reduction with long arm casting.

Casts, Surgical↗
PubMed1995

Interference with uterine blood flow by clomiphene citrate in women with unexplained infertility.

OBJECTIVE: To investigate the effect of clomiphene citrate on the uterine blood flow in women with unexplained infertility. METHODS: Twenty-one women who had normal uterine blood flow (pulsatility index [PI] less than 3 from the LH peak to the middle luteal phase of a natural ovulatory cycle) were enrolled in this study. Patients were given clomiphene citrate (100 mg/day) from days 5-9 of the next ovulatory cycle. The PI values measured in the natural and clomiphene citrate-treated cycles were compared using repeated measures analysis of variance. Their correlations with the estradiol (E2) and progesterone concentrations in the treatment cycle were calculated using the Pearson correlation coefficient. RESULT: In the natural cycles of those with normal uterine blood flow, the highest impedance of uterine blood flow was detected at the late follicular phase, then blood flow increased during the luteal phase. In the clomiphene citrate-treated cycles, a statistically significant decrease in uterine blood flow also occurred during the early luteal phase (P < .05). No significant correlation of E2 or progesterone serum concentrations with PI values of the uterine artery could be found in either natural or clomiphene citrate-treated cycles. CONCLUSION: The use of clomiphene citrate decreases the uterine blood flow during the early luteal phase, a periimplantation stage.

Adult↗
PubMed1995

[Morphometric analysis of corneal epithelium in normal subjects and soft contact lens wearers].

It is difficult to perform specular microscopic observation of the corneal epithelium in vivo due to the interference of light scattering by the tear film layer. In this study, we clearly observed the morphology of superficial corneal epithelial cells with a specular microscope contact lens that has the same refractive index as the corneal tissue. A total of 61 corneas from normal subjects and 21 corneas from soft contact lens wearers who had worn their lenses on a regular daily basis were studied using a specular microscope to take pictures of the corneal epithelium. The pictures were then analyzed with a computer-assisted morphometric analysis system. In normal subjects, the mean epithelial cell area and corresponding mean coefficient of variation (CV) were 618 +/- 97 microns 2 and 30.7 +/- 5.0% respectively. There was a significant correlation between the mean epithelial cell area and age in male group (p < 0.05) but not in the female group; whereas a significant correlation existed between CV and age in the female group only (p < 0.05). In the soft contact lens group, the mean epithelial cell area was 675 +/- 143 micron 2 and the CV was 29.6 +/- 6.0%. Compared to the corneal epithelium of normal subjects, the epithelial cell area and CV in the soft contact lens group was not significantly different; however, abnormal morphologic patterns in the corneal epithelium appeared more frequently. Our study showed that modified specular microscopy is a noninvasive and clinically valuable method by which to assess subtle alterations in the corneal epithelium that are barely detectable with routine slit lamp biomicroscopy.

Adolescent↗
PubMed1994

Serum level of squamous cell carcinoma antigen and tumor size are useful to identify preoperatively patients at high risk of cervical cancer.

BACKGROUND: The benefit of postoperative adjuvant therapy for patients with cervical cancer is uncertain, and moreover, may increase morbidity. In this study, patient age, clinical stage of the cancer, tumor size, and levels of serum squamous cell carcinoma cell antigen and carcinoembryonic antigen were studied in patients with Stage Ib and IIa squamous cell carcinoma of the uterine cervix to determine if these parameters can be used, before the surgical intervention, to distinguish patients who require postoperative adjuvant therapy from those who do not. METHODS: Ninety-nine patients were studied. After surgery, patients were classified either as high risk or low risk according to the results of histopathologic findings. The age of the patient was noted, and FIGO stage, squamous cell carcinoma antigen, carcinoembryonic antigen, and clinical tumor size were determined. A univariate analysis and then a stepwise logistic regression procedure were performed to select significant clinical predictors from among the five variables mentioned above. Any selected predictors were further analyzed by the receiver operator characteristic curve. RESULTS: Serum squamous cell carcinoma antigen and clinical tumor size measured by colposcopic examination were significant clinical predictors of the treatment strategy postoperatively. From the receiver operator characteristic curve, a sensitivity of 84.2%, a specificity of 91.8%, a positive predictive value of 84.5% were attained. CONCLUSIONS: Serum squamous cell carcinoma antigen assays and clinical tumor size estimated by colposcopic examination are helpful in identifying patients who require postoperative adjunctive therapy.

Adult↗
PubMed1994

Hyperammonemic encephalopathy due to essential amino acid hyperalimentation.

Hyperammonemic encephalopathy has occasionally been reported in uremic patients receiving hyperalimentation with essential amino acid (EAA) as a source of nitrogen as one of the remaining treatment options when the enteric routes were prohibited. We encountered this complication in a patient with normal renal function. A rat animal model was designed to elucidate the mechanism of hyperammonemia resulting from hyperalimentation with EAA as a source of nitrogen. Sixty-four male Long-Evan rats were divided into eight groups receiving feeds ad libitum or different formula of hyperalimentation. Hyperammonemia was found in every rat given hyperalimentation with EAA as the only nitrogen source. Using the Tukey honestly significant difference test, the results were significantly higher (p < 0.001) than that of the control group which were given feeds ad libitum and those groups given hyperalimentation for the same number of days but with mixed amino acid (MAA) as the nitrogen source. Adding arginine to EAA for a further four days after initial administration of EAA hyperalimentation for three days only slightly lowered the mean serum ammonia level. When compared to that of the three-day EAA hyperalimentation group, the difference was not statistically significant. Adding arginine, citrulline, and ornithine to EAA for a further four days significantly lowered the mean serum ammonia level. When we changed EAA hyperalimentation to MAA hyperalimentation for a further four days, the mean serum ammonia level decreased dramatically to nearly normal. Hyperalimentation using EAA as the exclusive source of nitrogen resulted in hyperammonemia. A deficiency of arginine or other amino acids of the urea cycle failed to account completely for the hyperammonemia observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids, Essential↗
PubMed1994

A further study of LDT and IFAT tests in evaluating the control of kala-azar in China.

Kala-azar (KA) used to be highly prevalent in Shandong Province in China and, according to the survey made in 1950, the average prevalence rate was 350 per million. Through mass treatment and sandfly control, the prevalence rate was brought down to 3 per 100,000 in 1958 and the disease was basically eliminated. Since 1972, only 18 residual patients have been detected and no newly infected cases have appeared. In the meantime, the vector density had been reduced to such a low level that sandflies could not be found in 85% of the villages. For further evaluation of the control measures, an immunological survey on a relatively large scale was conducted in 78 townships located in 24 counties of 13 prefectures and cities in 1990. A total of 10,239 rural residents of different ages had the Leishmanin dermal test (LDT). None of the people under 30 years of age was positive (0/8020), while in those aged above 30, the average positive rate was 4.4% (98/2219). During the survey, blood samples were also taken from 4232 people for indirect fluorescent antibody test (IFAT); results were all negative. This indicates that the transmission of KA had been completely interrupted since the early 1960s and the province is now a non-endemic area of KA. Further analyses of the data showed that LDT is of great value in epidemiological investigation of KA, for the evaluation of control measurements, the ascertainment of the past and present status of the disease, and detection of subclinical infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Purification and characterization of DNA methylase from HL-60 cells.

A solid leukemia sarcoma has been successfully developed after subcutaneous inoculation of the cultured human promyelocytic leukemia cells (HL-60 cells) into nude mice. The solid leukemia sarcoma is a more plentiful source than the cultured cells for enzymatic study and its growing environment is closer to that of the human body than the cultured cells. We established an efficient procedure of purifying HL-60 cells DNA methylase which includes: disruption of HL-60 cells by homogenization and sonication, removing the cell fragments and cellular particles by centrifuge and ultracentrifuge (105,000 g); removing endogenous DNA by streptomycin sulfate, salting out by (NH4)2SO4, ion exchange chromatography on DEAE-cellulose (DE-52), gel filtration over Sephadex G-100 column. The DNA methylase from HL-60 cells has been purified 204 fold by this procedure. The purified enzyme shows a single-band on PG-PAGE. A 479-kD molecular weight of this enzyme is measured by PG-PAGE. The enzyme properties of HL-60 DNA methylase are also studied.

Animals↗