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Biomedical subjects

S M Wang

Publications and source records attributed to S M Wang.

At least 145 records · Page 8Linked to original sources

Is previous abdominal surgery a contraindication to laparoscopic cholecystectomy?

Previous abdominal surgery has been reported as a relative contraindication to laparoscopic cholecystectomy. An analysis of 193 laparoscopic cholecystectomies was undertaken to determine whether this relative contraindication led to increased morbidity, an increased rate of conversion to open cholecystectomy, or longer operating time. The results of 55 patients who had previous abdominal surgery were compared with those of 138 patients without previous abdominal surgery. Morbidity, conversion rate, and operating time were not increased in patients with previous abdominal surgery. We found both previous upper and previous lower abdominal surgery to be risk for laparoscopic cholecystectomy. Laparoscopic cholecystectomy can be performed safely in patients with previous abdominal surgery if we (1) use the cutdown technique initially, (2) dissect the adhesion before the upper midline port is inserted, (3) retrogradely dissect the gallbladder from the liver bed, and (4) divide the cystic artery and duct last.

Abdomen↗

Clinical implications and factors related to left atrial spontaneous echo contrast in chronic nonvalvular atrial fibrillation.

The mechanisms leading to formation of spontaneous echo contrast (SEC), a smoke-like echo on echocardiography, are still controversial. To further explore the clinical implications and factors related to SEC formation, the correlation among echocardiographic variables, hematologic parameters or platelet aggregability, and the occurrence of SEC was studied in 119 patients with chronic nonvalvular atrial fibrillation. There were 75 men and 44 women with a mean age of 65 +/- 10 years (range 38-88). Left atrial SEC was detected in 39 patients (33%) by transesophageal echocardiography. Patients with history of systemic embolism were more frequently found to have left atrial SEC and left atrial thrombus by univariate analysis. Multivariate analysis showed that left atrial SEC (p < 0.001) was the only independent predictor of history of systemic embolism. Age, sex, left atrial or left ventricular dimension, left ventricular ejection fraction, antiplatelet or anticoagulant therapy and the percentage of lone atrial fibrillation were not significantly different between patients with and without left atrial SEC. Among the hematologic parameters, higher hematocrit was found in patients with left atrial SEC, while white blood cell and platelet counts were comparable in both groups. Platelet aggregability with different concentrations of inducers, adenosine diphosphate and collagen, was evaluated by the turbidimetric method in 15 patients with left atrial SEC and in 42 patients without left atrial SEC who were not receiving antiplatelet or anticoagulant therapy. No significant difference was found in platelet aggregability using four inducer concentrations between two groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

[Inorganic element analysis on different compatibility of sini decoction].

Thirteen kinds of inorganic elements in Sini decoction with different compatibility were analysed by atomic absorption spectrophotometry. The change in quantity and kind of medicines has no obvious effect on each element. But the extraction rate is reduced according to the increase in quantity and herb medicines in the prescription.

Calcium↗

Therapeutic effect of liver resection in patients with metastatic liver tumors.

Thirty-five hepatectomies for metastatic liver malignancy were performed from January 1986 to July 1992 at the National Taiwan University Hospital. Twenty-six of them were of colorectal origin and nine were of other origins. We analyzed the risk factors for recurrence and survival rate after hepatectomy of colorectal origin under curative intention with both univariate and multivariate analysis. The calculated median disease free interval after hepatectomy was 11 months (recurrence rate 65% in one year and 85% in two years). The median survival rate was 24 months (calculated one-year survival 86%, two-year survival 41%). In univariate analysis, the number of metastatic lesions and operation procedures significantly affect the recurrence rate (p = 0.033 and p = 0.042, respectively). In survival univariate analysis, only a safety margin > 1 cm and age > 50 years had significant benefit (p = 0.0014 and p = 0.045, respectively). By multivariate analysis, only solitary metastasis was beneficial to the recurrence rate (p = 0.013), an age > 50 years had a borderline beneficial effect to the recurrence rate (p = 0.052), while earlier liver stage, older age, larger safety margin and minor operative procedures positively affected the survival rate (p = 0.039, 0.018, 0.034 and 0.017, respectively). As the sample number was small, it was hard to draw any conclusions for metastatic liver tumors of other origins. The complication rate (5/35) and mortality rate (1/35) of hepatectomy were low. We concluded that for selected cases of metastatic hepatic malignancy, especially from colorectal cancer, hepatectomy is a promising treatment of choice.

Adult↗

Can cecal diverticulitis be differentiated from acute appendicitis?

Cecal diverticulitis is a rare disease entity, the diagnosis of which remains a difficult problem. The clinical picture of cecal diverticulitis is almost indistinguishable from acute appendicitis. We reviewed 11 cases of pathologically documented cecal diverticulitis who underwent treatment from May 1981 to April 1992. They were diagnosed incorrectly as acute appendicitis, ruptured appendicitis or appendiceal abscess prior to operative intervention. Thirty patients diagnosed correctly with acute appendicitis from March 1992 to April 1992 were included for a comparative study. We found that cecal diverticulitis presented with a longer duration of symptoms, initial pain over the right lower quadrant of the abdomen, older age, less migration of pain, nausea, vomiting, fever and leukocytosis, and an incidence of Alvarado's score > or = 7 than acute appendicitis.

Acute Disease↗

Plasma endothelin levels and surgically correctable pulmonary hypertension.

To know the changes in plasma endothelin of patients with pulmonary hypertension, we studied 32 patients with valvular heart disease. Among them, 22 patients had pulmonary hypertension (group I) and 10 had pulmonary arterial pressures in the normal range (group II). Plasma endothelin-1 concentrations of the patients in group I were significantly greater than those of the patients in group II (p < 0.05). No significant difference in plasma endothelin-3 concentrations existed between the two groups. Cardiac output and pulmonary capillary wedge pressure had a linear correlation with plasma endothelin-1 levels. There was also a significant correlation between plasma endothelin-1 levels and hemodynamic indicators of severity of pulmonary hypertension, such as mean pulmonary arterial pressure and pulmonary vascular resistance (p < 0.05). All patients in this study underwent surgical procedures for the correction of valvular lesions. All patients in group I showed a decrease in pulmonary arterial pressures, and their plasma endothelin-1 levels decreased from 3.84 +/- 0.20 pg/mL to 1.66 +/- 0.07 pg/mL (p < 0.05), whereas the plasma endothelin-3 levels had only slight variation from 0.64 +/- 0.11 pg/mL to 0.75 +/- 0.06 pg/mL (p > 0.05) between the preoperative and the postoperative stages. The results demonstrated that plasma endothelin-1 rather than endothelin-3 had a role in pulmonary hypertension. Several pieces of evidence pointed out that endothelin-1 functioned as a reactive mediator during vasoconstriction in the case of pulmonary hypertension rather than as a triggering factor of pulmonary hypertension.

Adolescent↗

Plasma endothelin level changes during hemorrhagic shock.

The purpose of this study was to analyze changes in plasma endothelin-1 levels during hemorrhagic shock. Thirty-two mongrel dogs were divided into four equal groups with group I as the controls and groups II through IV as experimental groups. The dogs in the experimental groups underwent hemorrhagic procedures. The mean blood pressure was kept at the level of 65 mm Hg in group II, 50 mm Hg in group III, and 40 mm Hg in group IV. Blood samples were collected from each dog under the following conditions: (1) after induction of anesthesia, when the animals were hemodynamically stable, before the start of shock; (2) 1 minute after the mean arterial pressure dropped to the level designed for each group (shock 1); (3) 15 minutes after shock 1; (4) 30 minutes after shock 1; (5) 1 hour after shock 1; (6) 2 hours after shock 1; (7) 4 hours after shock 1; and (8) 8 hours after shock 1. Plasma endothelin-1 levels both in arterial and venous blood were analyzed in each dog. The results showed that (1) arterial endothelin-1 concentrations were considerably lower than venous concentrations at the baseline level; (2) after the shock-1 point, plasma endothelin-1 concentrations increased, first markedly and then evenly throughout the oligemic period; (3) elevation of plasma endothelin-1 levels was significantly linearly correlated with the amount of blood loss at the time of 2 hours after shock and thereafter; (4) the arterial/venous ratio of plasma endothelin-1 levels during the oligemic period was higher than that in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

The role of microtubules in pigment translocation in goldfish xanthophores.

In xanthophores, microtubules were observed to radiate out from the microtubule organization center which was also the center of a central pigment mass. A similar pattern of microtubules was identified in both cells with dispersed or aggregated pigments. Brief vinblastine incubation, which depolymerized the microtubules of pigment-aggregated cells, failed to disrupt the central pigment mass. Subsequent removal of the vinblastine and the addition of ACTH dispersed pigment granules before the reassembly of microtubules. These results suggest that a radiating microtubular system is not essential to the maintenance or the dispersion of the aggregated pigment mass. Prolonged incubation with vinblastine eventually dispersed the aggregated pigment mass even in an ACTH-free medium, suggesting that certain components responsible for pigment association were finally destroyed by vinblastine. Moreover, these dispersed pigments could be induced to reaggregate into small clusters in the absence of microtubules, and finally into a large, tight aggregate when the microtubule system was fully reconstituted. We thus conclude that microtubules may serve to guide the centripedal movement of small pigment clusters toward the cell center, and they may not be essential to pigment dispersion and the maintenance of the central pigment mass.

Adrenocorticotropic Hormone↗

Distributional pattern of diverticular disease of the colon in Taiwan.

From May 1981 to October 1991, 66 patients with diverticular disease of the colon were analyzed retrospectively. Data were obtained from medical records. There were 29 men and 37 women, ranging in age from 32 to 85 years, with a mean age of 58.7 years. Forty-nine patients had a singular site of distribution in the diverticulum, and 17 patients had more than two sites of distribution in the diverticula. The locations of the diverticular disease were sigmoid colon (45.4%), ascending colon (36.4%), cecum (33.3%), descending colon (18.2%), transverse colon (12.1%) and rectum (1.5%). The left-sided lesions (46.9%) were approximately equal to the right-sided lesions (43.9%).

Adult↗

[Ultrastructure changes of the remnant regenerating hepatocytes after partial hepatectomy in rats].

In spite of its highly functionally differentiated characteristics, the remnant liver has the capability of regeneration after massive hepatectomy either in human beings or in experimental animals. This experiment was performed to study the ultrastructural changes of the regenerated hepatocytes after massive hepatectomy. Male Wistar rats weighing around 200g were used in this study. Partial hepatectomy with resection of the median and left lateral lobes (67.31%) was performed. The rats were sacrificed at 6, 24, 48 and 72 hours after the operation. The remnant liver was inspected under a light and electron microscope. We found that: (1) the glycogen in the cytoplasm of hepatocyte nearly disappeared 6 hours after hepatectomy, with a decrease of rough endoplasmic reticulum (RER) and an increase of smooth endoplasmic reticulum (SER) and lysosomes were noted; (2) 24 hours after hepatectomy, (the nuclear membrane became zigzag shaped and the reappearance of glycogen and an increase of RER, autophagosome and lipid droplets were noted. (3) the number of mitosis increased markedly at 48 hours postoperatively; and (4) 72 hours after hepatectomy, the lysosome and RER returned to preoperative condition with some RER became dilated; SER was hardly found and lipid droplets became bigger and increased; and the nuclear membrane shape was still a zigzag at this time.

Animals↗

Intraoperative irrigation of the colon and primary anastomosis: report of three cases.

Three male patients with obstructive left-sided colonic lesions received intraoperative irrigation of the colon and primary anastomosis after resection of the lesions. Their postoperative courses were smooth except for one patient with mild wound infection. Intraoperative irrigation of the colon is an effective method of facilitating primary anastomosis in the management of obstructive left-sided colonic lesions.

Aged↗

Effect of pH on endothelin-1 secretion of aortic strips.

In this study, aortic strips taken from mongrel dogs were used as experimental material. After preparation, the aortic strips were incubated in a designed control medium or an experimental medium (adding thrombin or epinephrine to the control medium). The pH value of each incubation medium mentioned above was adjusted with HCl or NaOH to a level of 8.0, 7.4, 7.0 and 6.6, respectively, in order to investigate the influence of medium acidity on the production of endothelin-1 from endothelial cells using aortic strips. After a designated time duration (one hour, three hours, six hours and 12 hours, respectively), the incubation media were collected for assay of endothelin-1. The results demonstrated that the endothelin-1 level of the incubation medium was elevated when: 1) the incubation time was lengthened; 2) the incubation medium was more acidic; 3) the aortic strips were incubated with a stimulant, such as thrombin and epinephrine; and 4) the endothelial cells on the aortic strips were intact. This indicates that the secretion of endothelin-1 is: 1) time-dependent, 2) pH-dependent, 3) stimulant-dependent and 4) endothelium-dependent.

Animals↗

Liver resection for hepatic metastasis from colorectal carcinoma.

One hundred and eighteen patients who suffered from metastatic liver tumors from colorectal carcinoma during the period from January 1980 to June 1991 at the National Taiwan University Hospital were retrospectively reviewed. The modes of treatment included hepatic resection (n = 18), transarterial embolization (TAE, n = 17), chemotherapy only (C/T, n = 36), and no treatment (n = 47). In the 18 patients who underwent hepatic resection during the last 10 years, the types of surgery included: wedge resection (n = 8), segmentectomy (n = 2), right hepatic lobectomy (n = 5), left hepatic lobectomy (n = 2) and extended right hepatic lobectomy (n = 1). There were no operative mortalities in this series. The overall three-year actuarial survival rate of the resection group was 57.5%. It was better than that of the TAG group (17%, p < 0.05). For a solitary tumor, the three-year actuarial survival rate rose to 64% in the resection group. There were no three-year survivors in the nonsurgical solitary tumor group. This experience defends aggressive surgical treatment of resectable hepatic metastatic liver cancer from colorectal carcinoma as a safe procedure which is able to prolong a patient's life.

Adult↗

Specific activation of glucuronide prodrugs by antibody-targeted enzyme conjugates for cancer therapy.

Cancer chemotherapy may be improved by increasing antineoplastic drug specificity for tumor cells. We have synthesized a glucuronide prodrug that can be enzymatically converted to an antineoplastic agent at tumor cells that are able to bind beta-glucuronidase-monoclonal antibody conjugates. The glucuronide prodrug BHAMG, the tetra-n-butyl ammonium salt of (p-di-2-chloroethylaminophenyl-beta-D-glucopyranoside) uronic acid, was 150 times less toxic than the parent drug, N,N-di-(2-chloroethyl)-4-hydroxyaniline, to HepG2 human hepatoma cells and over 1000-fold less toxic than the parent drug to AS-30D rat hepatoma cells in vitro. In the presence of beta-glucuronidase, BHAMG was activated and became as toxic as the parent drug N,N-di-(2-chloroethyl)4-hydroxyaniline. A conjugate (RH1-beta G) was formed by linking beta-glucuronidase to a monoclonal antibody which binds to an antigen expressed on the surface of AS-30D cells. The concentration of BHAMG causing 50% inhibition of AS-30D cellular protein synthesis was reduced over 1000-fold, from greater than 770 microM to less than 0.74 microM after these cells were preincubated with RH1-beta G. Specificity of BHAMG activation at antigen-positive cells was shown by monoclonal antibody RH1 blocking of RH1-beta G conversion of BHAMG to toxic drug and by the inability of BHAMG to be converted to active drug when antigen-negative control cells were preincubated with RH1-beta G. Our results show that the targeted-beta-glucuronidase activation of BHAMG can increase the specificity of chemotherapy for rat hepatoma in vitro and suggest that the targeted activation of glucuronide prodrugs may be useful for cancer therapy.

Aniline Mustard↗

Two distinct membrane-bound phosphatidylinositol-4-phosphate phosphatases in bovine brain.

Solubilized phosphatidylinositol-4-phosphate 4-phosphatase from bovine brain resolved into two peaks of activity by ion exchange chromatography. Both exhibited substantial detergent binding characteristic of integral membrane proteins, and both appear specific for phosphatidylinositol-4-phosphate, but their pH optima differ: the earlier eluting fraction (peak 1) is optimally active between pH 5.5 and 6, whereas the later eluting fraction (peak 2) is most active around pH 8.5. Detergent inhibition studies suggest that peak 2, but not peak 1, interacts with phosphatidylinositol-4-phosphate in the context of a single mixed micelle. Further characterization of these activities should help shed light on the biological function of polyphosphoinositide phosphatases.

Animals↗

A PCR-based assay for reporter gene expression.

Transient transfection is a widely used tool for the identification of cis-acting regulatory elements. These elements are detected by their effect on the expression of a reporter gene, which is quantified by measuring the reporter gene product in the form of mRNA, protein (hGH), or enzymes (CAT, luciferase). Measurements of mRNA levels have several advantages over enzyme or protein assays. However, mRNA quantification by RNase protection or S1 mapping has considerably lower signal-to-background ratio than protein assays and is therefore less sensitive. In this paper we report the development of a system that takes advantage of the polymerase chain reaction (PCR) to quantify rabbit beta-globin reporter gene expression. Cells are co-transfected with constructs whose activity is to be tested and a reference plasmid with a small deletion in the second exon of the beta-globin gene. We show that the ratio of the two amplified cDNA signals is a highly reliable measure of test gene expression. The sensitivity of this assay is at least 1000-fold higher than RNase protection.

Animals↗