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Biomedical subjects

M J Wang

Publications and source records attributed to M J Wang.

At least 55 records · Page 3Linked to original sources
PubMed1996

The effects of weight levels and gloves on the ability to discriminate weight difference.

In this study, six different types of gloves commonly used in industry (surgical, cotton, nylon, leather, rubber, and whizard knife hand gloves) were evaluated at four different weight levels (8.2, 3, 1.5 and 0.25 kg). Six males and six females voluntarily took part in this study. The dependent variable was the difference limen (or difference threshold) (abbreviated as DL(%)) of the discriminating weight difference (DWD). A nested-factorial design with the subject nested under gender was employed. The results indicate that the weight level had a negatively significant effect on the DL(%). The mean difference thresholds were 3.49, 5.39, 6.08, and 9.45 for the weight levels at 8.2, 3, 1.5, and 0.25 kg, respectively. The individual difference becomes obvious when the weight level is relatively light (0.25 kg). However, the effects of gender, glove, gender x weight, and weight x glove were found to be insignificant, and there was no significant correlation between the DL(%) and glove characteristics (thickness and weight). Subsequently, four additional weight levels (0.01, 0.5, 1 and 15 kg) were considered, and a psychophysical equation was derived: DL(%) = 34.33 x W(0.238) (R2 = 0.98), where W represents the weight level. These results support the power function. A minimum weight difference with 90% confidence of correct detection was suggested.

Adolescent↗
PubMed1996

Endothelin-1 concentrations and optimisation of arterial oxygenation and venous admixture by selective pulmonary artery infusion of prostaglandin E1 during thoracotomy.

In order to improve arterial oxygenation and venous admixture during one lung ventilation, the effect of selective infusion of prostaglandin E1 into the pulmonary artery of the ventilated lung was investigated in 12 adult patients undergoing thoracotomy. Patients' bronchi were intubated with a Mallinckrodt bronchial tube and ventilated with 66% oxygen in air. Cardiopulmonary factors such as systemic and pulmonary arterial pressures, pulmonary vascular resistance, blood gas analyses, cardiac output and airway pressure were measured before and during one-lung ventilation; venous admixture (Qs/Qt) was calculated. Serial blood samples were taken from the pulmonary artery of the ventilated lung for endothelin-1 estimation. One lung ventilation reduced the mean PaO2 from 42.1 (2.3) kPa to 11.8 (1.4) kPa (p < 0.001) and increased Qs/Qt from 10.8 (3.2)% to 39.2 (4.7)% (p < 0.001). Pulmonary vascular resistance also increased from 167 (24) dyne.s.cm-5 to 262 (38) dyne.s.cm-5 (p < 0.05) with a corresponding increase of plasma endothelin-1 (p < 0.05). After 30 min of one lung ventilation, PGE1 was infused continuously into the pulmonary artery of the ventilated lung at a rate which increased incrementally from 0.04-0.10 micrograms.kg-1.min-1. PaO2 increased to 20.7 (2.6) kPa (p < 0.01) and Qs/Qt decreased to 30.6 (3.5)% (p < 0.05). During the infusion, pulmonary vascular resistance reduced to 173 (30) dyne.s.cm-5 (p < 0.01). The plasma endothelin-1 concentration reached a plateau between the end of one lung ventilation (before closing the thorax) and 6 h postoperatively. This correlated inversely with the pre-operative forced expiratory volume in one second (r = -0.68, p < 0.005), declining to normal values 72 h after operation. The selective infusion of PGE1 into the pulmonary artery of the ventilated lung corrected pulmonary vasoconstriction and improved both arterial oxygenation and venous admixture during one lung ventilation for thoracotomy.

Aged↗
PubMed1996

Perioperative changes of plasma endothelin-1 concentrations in patients undergoing cardiac valve surgery.

Twenty-one patients who underwent cardiac valvular replacement procedures were studied to determine the perioperative changes of plasma endothelin-1 (ET-1) concentration and disposition of ET-1 in the pulmonary and systemic vasculature between patients with elevated (over 20 mmHg) mean pulmonary artery pressure and patients with normal pulmonary artery pressure. The overall profile alterations of plasma ET-1 concentration did not differ between the two groups of patients. The plasma ET-1 levels in the pulmonary artery and right atrium were significantly higher in patients with high pulmonary artery pressure than in patients with normal pulmonary artery pressure. Before cardiopulmonary bypass, significant pulmonary extraction of the plasma ET-1 existed in patients with high pulmonary artery pressure but the pulmonary extraction was not seen after bypass. There was no transpulmonary difference of the plasma ET-1 concentration in patients with normal pulmonary artery pressure either before or after bypass. The high levels of ET-1 in the pulmonary circuit and the pulmonary extraction of the ET-1 in patients with high pulmonary artery pressure might be a protective mechanism for rheumatic valvular patients with elevated pulmonary artery pressure.

Endothelin-1↗
PubMed1996

Blood and central venous pressure responses after serial tourniquet deflation during bilateral total knee replacement.

Thirty-five patients who underwent one-stage bilateral total knee replacement were included in this study to determine whether there was any difference in hemodynamic effects following the deflation of the first and second tourniquets. The values of hemodynamic variables were not significantly different immediately before either the first or the second tourniquet release as compared to preoperative values. The changes in heart rate after the release of the first and second tourniquets showed similar patterns. The systolic and diastolic blood pressure decreased significantly after deflation of the first and second tourniquets. However, the decrease was more marked after the second tourniquet deflation. The level of central venous pressure decreased significantly after the release of the first and second tourniquets but the patterns of change were not significantly different. The need for administration of ephedrine was also higher after the deflation of the second tourniquet than after the first. We conclude that the blood pressure changes after the second tourniquet deflation are more pronounced than those following the first tourniquet deflation. Anesthesiologists must be aware of this phenomenon and prevent marked hemodynamic changes that could be detrimental to high-risk patients.

Aged↗
PubMed1995

Difference between in vivo and in vitro effects of propofol on defluorination and metabolic activities of hamster hepatic cytochrome P450-dependent mono-oxygenases.

We have compared the in vivo and in vitro effects of propofol on cytochrome P450-dependent monooxygenase activities in hamster liver microsomes. Propofol (Diprivan) 10 mg/100 g body weight was injected i.p. twice a day for 2 weeks to induce cytochrome P450 enzymes. Liver microsomes were prepared by differential centrifugation. Metabolism of the cytochrome P450-dependent mono-oxygenase system was evaluated by measuring aniline hydroxylation, benzphetamine demethylation and benzo(a)pyrene hydroxylation. Defluorination of enflurane was assayed by detecting free fluoride metabolites. At similar concentrations as in the in vivo group, propofol in vitro exhibited concentration-dependent inhibition of metabolism of benzphetamine and benzo(a)pyrene. Aniline hydroxylation and defluorination of enflurane were inhibited to 78% of control with propofol 0.25 mmol litre-1. In propofol-treated hamsters, there was only minimal inhibitory or inductive effects on either mono-oxygenase activities or capacity for defluorination. This difference between the in vitro and in vivo effects of propofol on cytochrome P450 mono-oxygenase activities emphasizes the need for care when comparing in vitro and clinical data.

Anesthetics, Intravenous↗
PubMed1995

[Effects of pentagastrin with intracerebroventricular injection on blood pressure and heart rate in rats].

Experiments were carried out on 84 artifially ventilated SD rats anaesthetized with urethane and immobilized with gallamine triethiodide. Injection of pentagastrin (G5) into the rat lateral ventricle resulted in a marked elevation in arterial blood pressure which reached its peak at 3 min (from 12.2 +/- 1.5 to 14.1 +/- 1.7 kPa) and also a significant increase in heart rate from 435 +/- 53.9 to 471.6 +/- 53.2 beats/min. This effect of G5 could be partially antagonized by injection of phentolamine (alpha-receptor antagonist, 10 micrograms) into the lateral ventricle, but not by propanolol (beta-receptor antagonist, 4 micrograms) or atropine (M-receptor antagonist, 4 micrograms). These findings indicate that the central effect of G5 on blood pressure and heart rate is partly mediated by alpha-receptor.

Animals↗
PubMed1995

Differentiation of PC12 cells by infection with an HSV-1 vector expressing nerve growth factor.

We have developed an HSV-1 vector with mutations in the viral IE 3 and VP16 genes that expresses mouse beta nerve growth factor (NGF) from a latency associated transcript (LAT) promoter modified by insertion of a Rous sarcoma virus (RSV) enhancer. The backbone double mutant vector has reduced cytotoxicity compared with a single mutant deleted for IE 3 and is able to express the reporter luciferase gene in rat pheochromocytoma (PC12) cells at low but relatively stable levels in vitro. Intracellular NGF levels of approximately 3 pg per mg of cellular protein were detected in infected PC12 cells for at least 7 days after infection. Furthermore, infected PC12 cells exhibited differentiated morphology marked by neurite outgrowth similar to that found after exposure of PC12 cells to purified 2.5S beta NGF. A persistent level of 0.2 to 0.3 pM of the expressed NGF was detected in the culture media. The NGF-expressing vector also showed reduced cytotoxicity compared with that of the parental virus in infected PC12 cells. In PC12 cells that overexpress the human proto-oncogene bcl-2, the cytotoxicity of both viruses was significantly reduced. These studies demonstrate that the reduced cytotoxicity of the IE 3-VP16 double mutant virus and the increased duration of transgene expression from the RSV-modified LAT promoter permit terminal differentiation of PC12 cells after infection with an NGF-expressing HSV-1 vector.

Animals↗
PubMed1995

Dietary magnesium deficiency increases Gi alpha levels in the rat heart after myocardial infarction.

OBJECTIVE: Magnesium (Mg) is crucial for the function of G proteins which play important roles in mediating the inotropic effects of beta adrenergic agonists in the heart and are altered in heart failure. This study was performed to determine whether or not dietary Mg deficiency alters functional activity and levels of the two major ventricular G proteins, Gi alpha and Gs alpha in the heart after myocardial infarction (MI). METHODS: Six week old rats were fed an Mg adequate or deficient diet for 6 weeks. At the end of week 3, MI was induced by coronary artery ligation. A sham operation was performed as control. After surgery, surviving animals were maintained on their assigned diets for another 3 weeks. Then, cardiac function was measured, plasma and tissue were collected. RESULTS: Severe hypomagnesemia and increased plasma catecholamine level were observed in all animals fed the Mg deficient diet. A significant reduction of myocardial Mg concentration accompanied by elevated plasma and myocardial calcium concentrations was observed in MI animals with existing Mg deficiency vs. animals fed the Mg adequate diet. Cardiac function was impaired in MI rats and further reduced in MI rats with existing Mg deficiency. Gi alpha level was not altered by either Mg deficiency or MI alone, but was dramatically elevated in animals with combined Mg deficiency and MI (9.9 +/- 0.7 arbitrary unit.mg-1 protein) as compared to MI alone (5.8 +/- 0.6, P < 0.05) and Mg deficiency alone (6.1 +/- 0.8, P < 0.05). Gs alpha level did not differ between groups. GppNHp-, but not fluoride-stimulated adenylyl cyclase activity was slightly reduced in MI animals with existing Mg deficiency. CONCLUSION: The findings suggest that dietary Mg deficiency increases the expression of Gi alpha in the heart after MI, while levels and function of Gs alpha are not compromised during dietary Mg deficiency either with or without MI.

Adenylyl Cyclases↗
PubMed1994

Irradiation of bovine aortic endothelial cells enhances the synthesis and secretion of sulphated glycosaminoglycans.

The effect of X-irradiation on the synthesis of heparan sulphate (HS) and chondroitin/dermatan sulphate (CS/DS) by bovine aortic endothelial cells (BAEC), was studied by measuring the incorporation of [35S]sulphate and [3H]glucosamine into newly synthesized glycosaminoglycan (GAG) chains. Medium extracts from irradiated cultures (5Gy) were found to contain approx. 130% more HS and 200% more CS/DS than unirradiated controls. Smaller increases were observed in cellular extracts, irradiated cultures (5Gy) containing approx. 60% more HS and 100% more CS/DS than unirradiated controls. Structural studies showed no significant changes occurred upon irradiation in either the amounts or distribution of N- and O-sulphate groups in the HS molecule. Values for N-sulphation of 41.1% control and 41.5% irradiated (5Gy) were obtained, the corresponding values for O-sulphation being 19.9% control and 20.2% irradiated. Isotope incorporation data indicated that sulphation of CS/DS may decrease after irradiation, however, analysis of chondroitin ABC lyase derived disaccharides showed no changes in the proportion of non-sulphated and O-sulphated disaccharides. The present study indicates that X-irradiation stimulates the synthesis and secretion of HS and CS/DS proteoglycans (PGs) by BAEC. This could be relevant to many features which are found to be indicative of radiation-induced damage.

Animals↗
PubMed1994

One-stage repair of aortopulmonary septal defect and interrupted aortic arch.

Surgical repair of an aortopulmonary septal defect, interrupted aortic arch and the duct that coexists in this setting usually includes closure of the aortopulmonary septal defect, reconstruction of the arch, and interruption of the duct. A 20-month-old girl underwent a successful one-stage repair of such anomalies in which an intraarterial baffle was used. A Gore-Tex baffle was used both to close the aortopulmonary septal defect and to conduct the ascending aortic blood flow through the duct into the descending aorta. We recommend use of this intraarterial baffle as an alternative to the repair of an aortopulmonary septal defect and an interrupted aortic arch with a widely patent duct.

Aorta, Thoracic↗
PubMed1994

Posttransfusion hepatitis C virus infection in children.

Hepatitis C virus (HCV) infection was investigated retrospectively and prospectively in children who had open heart surgery. The retrospective study included 196 patients who had open heart surgery 2 to 6 years before enrollment and were regularly followed. Antibody to HCV was detected in eight cases, and seven of these eight patients had viremia caused by HCV infection. The other patient's anti-HCV titer gradually decreased and HCV ribonucleic acid was absent throughout the course. Four of these eight had persistent viral replication without clinical evidence of hepatitis; the other three had viremia and chronic hepatitis. The HCV infection rate in the retrospective study group was about 4%. The HCV was of genotype 2 in five cases and of genotype 3 in two cases. The clinical outcome was not related to sex, age, amount of transfusion, or HCV genotype. For the prospective study, we enrolled 94 patients. Of the 56 enrolled after the initiation of anti-HCV screening in the blood bank, none was infected by HCV. Of the 94 patients, 38 were enrolled before screening; 4 had abnormal liver function 1 to 3 months after operation, and 2 were infected with HCV. One patient had an acute but resolving course; the other had persistent anti-HCV and HCV viremia, although the liver function test results returned to the normal range. The HCV in both cases belonged to genotype 2. We conclude that in Taiwan the seroconversion rate of HCV in children who underwent open heart surgery was 4% to 5%. Anti-HCV screening in donor blood significantly decreased the incidence of posttransfusion hepatitis C.

Acute Disease↗
PubMed1994

Improved cell survival by the reduction of immediate-early gene expression in replication-defective mutants of herpes simplex virus type 1 but not by mutation of the virion host shutoff function.

Derivatives of herpes simplex virus type 1 (HSV-1) have elicited considerable interest as gene transfer vectors because of their ability to infect a wide range of cell types efficiently, including fully differentiated neurons. However, it has been found that infection of many types of cell with vectors derived from replication-defective mutants of HSV-1 is associated with cytopathic effects (CPE). We have previously shown that viral gene expression played an important role in the induction of CPE caused by an HSV-1 mutant deleted for the essential immediate-early gene 3 (IE 3) (P.A. Johnson, A. Miyanohara, F. Levine, T. Cahill, and T. Friedmann, J. Virol. 66:2952-2965, 1992). We have investigated which viral genes might be responsible for CPE by comparing the ability of each of the individual genes expressed by an IE 3 deletion mutant during a nonproductive infection to inhibit biochemical transformation after cotransfection of BHK or CV-1 cells with a selectable marker gene. Transfection of IE genes 1,2, and 4 individually all caused a marked inhibition of colony formation, while transfection of IE 5 and the large subunit of ribonucleotide reductase had little effect. These results suggested that it would be necessary to mutate or reduce the expression of nearly all HSV-1 IE genes to reduce virus-induced CPE. Therefore, we have used VP16 mutants, which are unable to transinduce IE gene expression (C. I. Ace, T. A. McKee, J. M. Ryan, J. M. Cameron, and C. M. Preston, J. Virol. 63:2260-2269, 1989), to derive two replication-defective strains: 14H delta 3, which is deleted for both copies of IE 3, and in 1850 delta 42, which has a deletion in the essential early gene UL42. The IE 3-VP16 double mutant, 14H delta 3, is significantly less toxic than a single IE 3 deletion mutant over a range of multiplicities of infection, as measured in a cell-killing assay, and has an enhanced ability to persist in infected cells in a biologically retrievable form. In contrast, the UL42-VP16 double mutant, in 1850 delta 42, showed reduced toxicity only at low multiplicities of infection. To test the role of the virion host shutoff function as an additional candidate to influence virus-induced CPE, we have introduced a large insertion mutation into the virion host shutoff gene of an IE 3 deletion mutant and the double mutant 14H delta 3.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Difference in efficacy of the Cell Saver in coronary bypass grafting surgery and cardiac valvular reoperations.

The efficacy of the Cell Saver in reducing transfusion requirements in patients who underwent either coronary artery bypass grafting (CABG) or reoperation for valvular replacement (Redo) were prospectively studied in 112 patients. In 41 patients, the Cell Saver was used from the beginning of the surgery (group 1), and in the other patients, no blood conservation techniques were undertaken (group 2). Perioperative hematological profile, postoperative chest tube drainage and transfusion requirements were examined in all patients. More red cells could be retrieved from the Redo patients than from the CABG patients (p < 0.05) during operation. The use of the Cell Saver in CABG patients reduced the total amount of blood transfusion required (p < 0.001). However, in the Redo patients, the use of the Cell Saver did not reduce the transfusion requirements during hospitalization. Furthermore, the amount of platelet concentrates transfused in the group 1 Redo patients was greater than the group 2 Redo patients. The use of the Cell Saver did not increase the postoperative chest tube drainage in either the CABG or the Redo patients. We conclude that the Cell Saver is useful in CABG patients, as far as the reduction of transfusion requirements is concerned; however, its efficacy in reducing transfusion requirements for Redo patients is questionable.

Blood Transfusion, Autologous↗
PubMed1994

Change of blood pressure and urine flow rate during cardiopulmonary bypass and its relation to postoperative renal function.

The relationship between the perfusion flow, the mean arterial pressure (MAP) and the urine flow rate during cardiopulmonary bypass (CPB) and the effect of oliguria developed during CPB on the postoperative renal dysfunction were studied prospectively in 69 open heart surgery patients. The MAP, the perfusion flow and the urine flow rate were monitored every five minutes during the first 45 minutes after the commencement of CPB and after the removal of the aortic cross clamp (AX). The serum creatinine (Cr), creatinine clearance (CCr) and blood urea nitrogen were measured before operation, as well as on the first, second and third postoperative days. The dosage of catecholamines and diuretics used and the duration of intubation and hospitalization in the intensive care unit were also recorded. The urine flow rate correlated with MAP much better than the perfusion flow during CPB (r = 0.4768, p < 0.0001). The urine flow rate and MAP decreased significantly after the initiation of CPB and after the release of the AX; however, oliguria developed only during the first 30 minutes of CPB. There were no differences in postoperative Cr, postoperative CCr, doses of catecholamines or diuretics, and the duration of intubation between patients with or without development of oliguria during CPB. Parameters measured during CPB could not predict CCr during the first three postoperative days. We conclude that it is MAP rather than perfusion flow which correlates with the urine flow rate during CPB. Periods of oliguria during CPB did not correlate with or help in the prediction of the development of postoperative renal dysfunction.

Blood Pressure↗
PubMed1994

Hyperbilirubinemia after cardiac operation. Incidence, risk factors, and clinical significance.

Three hundred and two consecutive patients who had undergone cardiac operation for various cardiac lesions were studied prospectively to evaluate the incidence, risk factors, and the associated mortality of postoperative hyperbilirubinemia after cardiopulmonary bypass. Concentrations of the serum total (conjugated and unconjugated) bilirubin, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, albumin, globulin, and serum haptoglobin were measured before the operation and again on the first, second, and seventh postoperative days. Postoperative hyperbilirubinemia was defined as occurrence of a serum total bilirubin concentration of more than 3 mg/dl in any measurement during the postoperative period. Logistic regression was done to identify possible risk factors for postoperative hyperbilirubinemia. Overall incidence of postoperative hyperbilirubinemia was 35.1%; the incidence of postoperative hyperbilirubinemia was higher in patients whose valves were replaced with mechanical prostheses than in those without prostheses (p < 0.00001). In patients with postoperative hyperbilirubinemia, 70% of the increase of total bilirubin on the first postoperative day came about from an increase in unconjugated bilirubin. Serum haptoglobin decreased significantly at the same time (p < 0.01). Development of the postoperative hyperbilirubinemia was associated with a higher mortality (5.6% versus 0.5%, p < 0.01) and higher frequency of use of intraaortic balloon counterpulsation, especially for patients in whom the highest postoperative total bilirubin occurred after the first 2 days. The numbers of valves replaced, preoperative right atrial pressure, and preoperative total bilirubin concentration are the significant risk factors that, in combination, correctly predict the occurrence of postoperative hyperbilirubinemia in 80% of the patients. We concluded that postoperative hyperbilirubinemia results mainly from an increase in unconjugated bilirubin and is associated with higher mortality, especially for patients in whom highest postoperative total bilirubin occurred late after operation. Patients with the higher preoperative right atrial pressure and total bilirubin level who then underwent multiple valve replacement procedures are at greater risk for development of postoperative hyperbilirubinemia.

Cardiac Surgical Procedures↗
PubMed1993

Differences in temperature changes between pediatric and adult patients after cardiopulmonary bypass.

Nasopharyngeal (NPT) and rectal (RT) temperatures were continuously monitored in 51 adult or pediatric patients undergoing cardiac surgical procedures until 1 hour after the termination of cardiopulmonary bypass (CPB). The measurement also included the lowest NPT achieved and the dwelling time at that temperature on CPB, the rewarming time, the time on CPB, and the time that the chest remained opened after CPB. After the termination of CPB, the decrease of NPT (afterdrop) was significantly greater in the adult group than in the pediatric group. The mean decrease in adult patients was 1.34 +/- 0.65 degrees C versus 0.63 +/- 0.8 degrees C in pediatric patients. The combination of the NPT at the end of bypass (EndNPT), body weight times the EndNPT, and the dwelling of the lowest temperature times the EndNPT could predict 45% of the afterdrop. It is concluded that afterdrop occurs to a lesser degree in pediatric patients than in adults. This may be due to more efficient supplying of external heat to pediatric patients in whom there is a larger body surface area to weight ratio.

Adult↗
PubMed1993

Comparison of the combined effects of atropine and neostigmine with atropine and edrophonium on the occurrence of postoperative nausea and vomiting.

To investigate the effects of different types of anticholinesterase on the incidence of the postoperative nausea and vomiting, 100 ASA class I-II adult premenopausal female patients undergoing elective lower abdominal surgery were randomized into two groups. In both groups, anesthesia was induced with thiopental and fentanyl and 50% nitrous oxide and 0.5-1.5% of isoflurane were used for anesthetic maintenance with succinylcholine 1 approximately 1.5 mg/kg for intubation and atracurium 0.3 mg/kg/hr for maintenance of muscle relaxation. Patients received reversal agents for neuromuscular blockade after operation when the evoked train-of-four (TOF) count returned to four visual responses. A mixture of atropine 8 micrograms/kg and edrophonium 0.75 mg/kg was given to the first group of patients while atropine 15 micrograms/kg and neostigmine 40 micrograms/kg was given to another group of patients. All the patients were observed for the occurrence of nausea or vomiting for 2 hours after the operation in the recovery room. The incidence of nausea was not statistically significantly different in both groups (20% in neostigmine group and 26% in edrophonium group). The occurrence of vomiting was also similar in both groups (8% in neostigmine group and 6% in edrophonium group). We concluded that there were no difference in the incidence of postoperative nausea or vomiting with the use of either neostigmine or edrophonium with atropine for antagonizing neuromuscular blockade after the lower abdominal surgery.

Adult↗