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Biomedical subjects

J Wong

Publications and source records attributed to J Wong.

At least 451 records · Page 25Linked to original sources
PubMed1994

The role of endothelin and endothelin receptor subtypes in regulation of fetal pulmonary vascular tone.

The physiologic role of endothelin-1 (ET-1) and its receptors in regulating fetal pulmonary vascular tone is unknown. We therefore investigated the role of ET-1 and its receptors in the regulation of fetal pulmonary vascular tone using BQ 123 (an ETa receptor antagonist) and 4 Ala ET-1 (an ETb receptor agonist). In six fetal sheep in utero, we found that injections of ET-1 (250 ng/kg fetal weight) into the left pulmonary artery increased left pulmonary blood flow (21.0 +/- 17.5 to 74.7 +/- 32.9 mL/kg/min, p < 0.05) and decreased left pulmonary vascular resistance (6.02 +/- 7.00 to 0.84 +/- 0.48 mm Hg/kg/min/mL, p < 0.05). BQ 123 (5 mg) increased pulmonary blood flow (24.6 +/- 28.7 to 47.7 +/- 27.4 mL/kg/min, p < 0.05) and decreased pulmonary vascular resistance (8.84 +/- 10.32 to 1.43 +/- 0.80 mm Hg/kg/min/mL, p < 0.05); 4 Ala ET-1 (1725 ng/kg) markedly increased pulmonary blood flow (8.6 +/- 6.8 to 69.4 +/- 23.1 mL/kg/min, p < 0.05) and decreased pulmonary vascular resistance (12.02 +/- 10.2 to 0.78 +/- 0.44 mm Hg/kg/min/mL, p < 0.05). The absolute increase in pulmonary blood flow produced by ET-1 was attenuated by glibenclamide (an ATP-dependent potassium channel blocker) (flow increase of 73.4 +/- 34.1 versus 49.3 +/- 16.8 mL/kg/min, p < 0.05). This study demonstrates that ETa receptor activation has a small role in maintaining basal fetal pulmonary vascular tone, and that specific ETb receptor activation produces marked pulmonary vasodilation. The increase in pulmonary flow produced by ET-1 in fetuses is partly mediated by ATP-dependent potassium channels.

Animals↗
PubMed1994

Developmental effects of endothelin-1 on the pulmonary circulation in sheep.

Endothelin-1 (ET-1) is a polypeptide that has potent hemodynamic effects on the pulmonary circulation. To determine whether there are changes in these effects with increasing postnatal age, we investigated the effects of ET-1 (250 ng/kg) at rest and during pulmonary hypertension in eight lambs (< 1 wk old) and 11 juvenile sheep (6-12 mo old). At rest, ET-1 did not change pulmonary arterial pressure in lambs, but increased pulmonary arterial pressure by 64.0 +/- 37.5% (p < 0.05) in sheep. During pulmonary hypertension, ET-1 produced greater decreases in pulmonary arterial pressure in lambs than in sheep (26.6 +/- 3.4% versus 18.7 +/- 8.3%, p < 0.05). In juvenile sheep, the increase in resting pulmonary arterial pressure produced by ET-1 was inhibited by meclofenamic acid, an inhibitor of prostaglandin synthesis (40.3 +/- 9.9% versus 2.3 +/- 4.7%, p < 0.05); during pulmonary hypertension, the decrease in pulmonary arterial pressure produced by ET-1 was inhibited by N omega-nitro-L-arginine, an inhibitor of endothelium-derived nitric oxide synthesis (21.4 +/- 10.7% versus 8.0 +/- 3.6%, p < 0.05) and by glybenclamide, an ATP-dependent potassium-channel blocker (18.8 +/- 8.4% versus 4.0 +/- 4.4%, p < 0.05). The hemodynamic effects of ET-1 on the pulmonary circulation are dependent on postnatal age. Pulmonary vasoconstriction is mediated by prostaglandin production, and pulmonary vasodilation is mediated, in part, by release of endothelium-derived nitric oxide and activation of ATP-dependent potassium channels.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1994

Association of IBM's "A Plan for Life" health promotion program with changes in employees' health risk status.

To evaluate the association of participation in IBM's "A Plan for Life" program with changes in blood pressure, serum total, high-density lipoprotein, and non-high-density lipoprotein cholesterol, body mass index, and cigarette smoking, we compared changes in these measures over a 1- to 5-year period among program participants and nonparticipants initially found to be at risk. After adjustment for age, sex, time to follow-up, and baseline values, the proportion of participants no longer at high risk was significantly greater than the corresponding proportion of nonparticipants in the areas of blood pressure total and non-high-density lipoprotein cholesterol and smoking cessation.

Adolescent↗
PubMed1994

Massive acute pulmonary embolism in protein S deficiency--a case report.

A young man with a history of deep vein thrombosis and pulmonary embolism 11 years ago presented again with acute pulmonary embolism and was treated initially with intravenous heparin at our institution. Five days later he had another massive bout of pulmonary embolism causing hypotension. Pulmonary angiography confirmed the presence of thrombi in both pulmonary arteries, with complete obstruction of the left pulmonary artery. He was treated successfully by emergency pulmonary embolectomy. Blood investigations later confirmed the diagnosis of protein S deficiency and he was started on warfarin therapy for life. Massive pulmonary embolism should be treated aggressively. Thrombolytic therapy accelerates clot lysis, reduces pulmonary pressures, restores pulmonary capillary volume and reverses right heart failure faster than heparin alone. There is also a trend towards decreased mortality with thrombolysis. In the presence of shock, the patient should be resuscitated and if facilities for emergency embolectomy are available, surgery is a viable alternative to thrombolysis, especially if the clot burden is massive. In young patients with recurrent venous thromboembolism in the absence of obvious predisposing factors, it is important to exclude inherited plasma protein deficiencies of protein S, protein C, antithrombin III, plasminogen and fibrinogen.

Acute Disease↗
PubMed1994

The T cell antigen receptor CD3:CD4 molecular complex is diminished on the surface of pulmonary lymphocytes.

CD4, a 55-kd cell surface glycoprotein, binds to class II major histocompatibility complex (MHC) (Ia) antigens and functions as a coreceptor for the T cell antigen receptor (Ti alpha beta)-CD3 complex. We have observed that critical elements of the T cell antigen multireceptor complex, including Ti alpha beta, CD3, CD4, but not CD8, were diminished on CD45RO+ pulmonary T lymphocytes but not CD45RO+ peripheral blood T lymphocytes (PBL). Epitopes mapping from the first (D1) to the fourth (D4) extracytoplasmic Ig-like domains of CD4 were expressed to a lesser degree on pulmonary T cells than on PBL (P = 0.002). CD4 expression on pulmonary T cells did not increase after 72 hours of ex vivo culture in complete medium but was restored toward control levels by stimulation with phytohemagglutinin, anti-CD3, or interleukin-2. CD4 mRNA isolated from lung T cells and PBL co-migrated on Northern blots and the total levels of CD4 mRNA were comparable, suggesting that diminished CD4 expression by pulmonary T cells might reflect a posttranscriptional change. To determine whether CD4bright T cells convert with mitogen stimulation to CD4dim cells, PBLs were stimulated with immobilized anti-CD3, anti-CD4, or a molecularly engineered anti-CD3:CD4 bispecific monoclonal antibody and the ratio of the CD4:CD3 mean fluorescence staining intensities was calculated at days 3 and 13. The CD4:CD3 ratio decreased primarily for cells stimulated with anti-CD3:CD4, suggesting that co-ligation of CD3 and CD4 is required for the generation of CD4dim T cells. We conclude that diminished Ti alpha beta-CD3:CD4 expression is a characteristic of T cells in lung that is not shared by peripheral blood T cells in vivo, and speculate that this change reflects T cell activation in a millieu of limited interleukin-2 availability.

Antibodies, Bispecific↗
PubMed1994

Squamous cell carcinoma of the oesophagus with mucin-secreting component (muco-epidermoid carcinoma and adenosquamous carcinoma): a clinicopathologic study and a review of literature.

The clinicopathological features of 11 cases of primary oesophageal squamous cell carcinomas with mucin-secreting component (eight muco-epidermoid and three adenosquamous carcinomas) are presented. The incidence was 2.2% of all resected primary oesophageal tumors. The mean age was 64 years and the male to female ratio was 4.5:1. The mean diameter of these tumours was 4 cm. Twenty-seven per cent of these tumours were in the upper, 46% in the middle and 27% in the lower portion of the oesophagus. The age, sex and site distribution of these tumors were similar to those of squamous cell carcinomas. The medium survival of these patients was 15 months. The world literature concerning this rare entity was reviewed and compared with the findings of the present study. No major racial differences were noted. In addition, the classification of this group of tumours was also discussed.

Aged↗
PubMed1994

Squamous cell carcinoma of the esophagus with mucin-secreting component. Mucoepidermoid carcinoma.

Among 1058 patients with cancer of the esophagus, 20 patients with mucoepidermoid or adenosquamous cell carcinoma of the esophagus and cardia, together defined as squamous cell carcinoma with a mucin-secreting component, were seen over a 10-year period. Their records were reviewed and appropriate comparisons were also made with the more common squamous cell carcinomas and adenocarcinomas. Squamous cell carcinoma with mucin-secreting component comprised 1.9% of all tumors encountered. Clinical features including age, male predominance, symptoms at presentation, length of tumor, and appearance of tumor did not differ from those of squamous cell and adenocarcinoma. The location of these tumors, however, followed that of squamous cell carcinomas, with 55% in the middle third and 25% in the lower third. Adenocarcinomas were found predominantly at the cardia (83%). Operability and resectability rates were higher than those of squamous cell and adenocarcinomas. Primary treatment consisted of resection in 19 of the 20 patients (95%); 18 of them had a one-stage resection and 1 patient had a two-stage resection. Postresection staging showed that 5% had stage I disease, 16% had stage II, and 79% had stage III disease. None of the patients who underwent resection died within 30 days of the operation. The mortality after 30 days was 10.5%. The 1 patient in whom intubation was the primary treatment had distant metastases at the time of presentation (stage IV). The overall median survival was 9.2 months. The median survival for patients who had their tumors resected was 9.5 months. The survival improved to 33 months for curative resection but was only 8.7 months for palliative resection. The 1-, 2-, and 5-year survivals were 46%, 39%, and 0%, respectively. This prognosis was not significantly different from that of patients with squamous cell carcinoma or adenocarcinoma.

Adenocarcinoma↗
PubMed1993

Early treatment of acute biliary pancreatitis by endoscopic papillotomy.

BACKGROUND: Most patients with acute biliary pancreatitis have stones in the biliary tract or ampulla of Vater. Because these stones may be passed spontaneously soon after a patient is admitted to the hospital, the importance of early operative removal is not known. We tested the hypothesis that endoscopic papillotomy within 24 hours of admission decreased the incidence of complications in patients with acute biliary pancreatitis. METHODS: We studied 195 patients with acute pancreatitis who were randomly assigned to one of two groups: 97 patients underwent within 24 hours after admission emergency endoscopic retrograde cholangiopancreatography (ERCP) followed by endoscopic papillotomy for ampullary and common-bile-duct stones, and 98 patients received initial conservative treatment and selective ERCP with or without endoscopic papillotomy only if their condition deteriorated. RESULTS: One hundred twenty-seven patients ultimately proved to have biliary stones. Emergency ERCP with or without endoscopic papillotomy resulted in a reduction in biliary sepsis as compared with conservative treatment (0 of 97 patients vs. 12 of 98 patients, P = 0.001). The decrease in biliary sepsis occurred both in patients predicted to have mild pancreatitis (0 of 56 patients in the group that received emergency ERCP vs. 4 of 58 patients in the conservative-treatment group, P = 0.14) and in patients predicted to have severe pancreatitis (0 of 41 patients vs. 8 of 40 patients, P = 0.008). In all patients who had unrelenting biliary sepsis, persistent ampullary or common-bile-duct stones were identified. There were no major differences in the incidence of local complications (10 patients in the group that received emergency ERCP vs. 12 patients in the conservative-treatment group) or systemic complications (10 patients vs. 14 patients) of acute pancreatitis between the two groups, but the hospital mortality rate was slightly lower in the group undergoing emergency ERCP with or without endoscopic papillotomy (5 patients vs. 9 patients, P = 0.4). CONCLUSIONS: Emergency ERCP with or without endoscopic papillotomy is indicated in the treatment of patients with acute pancreatitis.

Acute Disease↗
PubMed1993

The Shatin community mental health survey in Hong Kong. II. Major findings.

A large-scale community survey in Shatin, Hong Kong, is presented with a modified two-phase design using flagged and nonflagged subsamples. A modified Self-Reporting Questionnaire and the Diagnostic Interview Schedule (version III) were used as the screening and diagnostic instruments, respectively. Lifetime rates for 19 Diagnostic Interview Schedule/DSM-III diagnoses are presented. The most common diagnoses in Shatin were tobacco dependence, generalized anxiety disorder, alcohol abuse and/or dependence, all phobias, and dysthymic disorder. The male-predominant disorders were tobacco dependence, alcohol abuse/dependence, pathological gambling, and antisocial personality. The female-predominant disorders were generalized anxiety disorder, all phobias, dysthymic disorder, major depressive disorder, obsessive-compulsive disorder, and bereavement.

Adolescent↗
PubMed1993

Hepatic resection for hepatolithiasis.

OBJECTIVE: To analyze the results of hepatic resection for hepatolithiasis. DESIGN: A retrospective study of case records of patients with hepatolithiasis undergoing hepatic resection. These patients had been followed up for 3 to 38 months. They were referred to Queen Mary Hospital, a tertiary referral center in Hong Kong. PATIENTS: Of 172 patients with hepatolithiasis seen between January 1984 and December 1981, 63 patients underwent hepatic resection because the affected liver segments were destroyed by repeated infection (n = 51), multiple cholangitic liver abscesses were found in the affected liver segments (n = 9), or concomitant intrahepatic cholangiocarcinoma was diagnosed (n = 3). INTERVENTION: Left lateral segmentectomy was performed in 42 patients, left hepatic lobectomy in 15 patients, right hepatic lobectomy in one patient, and segmentectomy in five patients. MAIN OUTCOME MEASURES: Postoperative morbidity and mortality analysis. RESULTS: Contrary to hepatic resection in a normal liver, dissection to isolate inflow and outflow vasculature was difficult in 52% of cases owing to severe inflammatory fibrosis at the liver hilum, at the umbilical fissure, or at the junction of hepatic vein with inferior vena cava. The operative morbidity rate was 32% and the mortality rate was 2%. The majority of complications were wound infection, subphrenic abscesses, or biliary fistulas, which could be due to the presence of infected bile (85%) and liver abscesses (25%) in this disease. Statistical analysis of the preoperative hematological and biochemical variables and the amount of intraoperative blood loss could not identify any factor with significance in correlating with the development of postoperative complications. Stones recurred in 16% after a median follow-up of 47 months. CONCLUSION: Hepatic resection is a satisfactory treatment for hepatolithiasis. The postoperative septic complication rate is high and is an intrinsic problem related to liver resection in a septic condition.

Adult↗
PubMed1993

Level of anastomosis and anorectal manometry in predicting function following anterior resection for adenocarcinoma.

The clinical and physiological consequences of sphincter preservation after resection of rectal carcinoma at various levels were evaluated. Thirty-two patients (mean age 59.2 years; range 31-79 years) who had undergone curative surgery at least one year previously and were not given adjuvant therapy, were studied with 19 normal controls. Three blinded observers independently assessed clinical sphincter function, level of anastomosis (ANL) and anorectal manometry. 85.7% had an increase in stool frequency but their normal lifestyles were unaffected. The mean stool frequency was 3.1 (range 2 to 8) times/day. The anal maximal basal and maximum squeeze pressures, rectal volume of first sensation (VIS) and urge, maximum tolerable volume and compliance were all significantly impaired (P < 0.05). Patients with poorer function had significantly lower ANLs (P < 0.05). On multiple regression analysis, the ANL and the VIS significantly predicted stool frequency (P < 0.05). ANL below 6 cm was significantly associated with impaired frequency of stools (P < 0.05). This may be a subgroup of patients whose residual rectal reservoir function is compromised and may theoretically benefit from colonic pouches.

Adenocarcinoma↗
PubMed1993

Appraisal of hepaticocutaneous jejunostomy in the management of hepatolithiasis.

Hepaticocutaneous jejunostomy offers the advantage of permanent percutaneous access to the biliary tract in patients with complex biliary problems. The long-term value, however, has not been assessed. In 41 patients who underwent this procedure for intrahepatic stones, there was no hospital mortality, and the postoperative morbidity rate was 10%. The presence of the cutaneous stoma facilitated postoperative flexible choledochoscopy for dilatation of biliary strictures and extraction of residual stones. On follow-up, symptoms recurred in 12 patients (29%) at a median time of 27 months (range: 1 to 97 months). Reconstruction of the cutaneous stoma and flexible choledochoscopy via the jejunal loop helped to resolve the acute cholangitis (n = 4) and to eradicate recurrent stones in all cases. Hepaticocutaneous jejunostomy was also beneficial in the management of three patients who experienced further recurrence of symptoms. There was no major difficulty in reconstructing the cutaneous stoma and in performing choledochoscopy via the jejunal loop. The overall complication rate related to the cutaneous stoma was 15%. Repeat laparotomy for recurrent disease was required in only one patient who underwent a second bilio-enteric anastomosis for a nondilatable left duct stricture. We conclude that hepaticocutaneous jejunostomy is a valuable procedure in the management of hepatolithiasis.

Adult↗
PubMed1993

Prediction of the severity of acute pancreatitis.

We conducted a prospective study to validate our previous finding that serum urea and plasma glucose levels on admission could predict the outcome of acute pancreatitis. Forty-two (24%) of 176 patients developed complications related to the attack of acute pancreatitis and were classified as having severe disease. By logistic regression analysis of 17 admission parameters, serum urea and plasma glucose levels were again the factors with independent significance in defining the outcome. By adopting the same cutoff levels as in our previous study (serum urea level greater than 7.4 mmol/L and plasma glucose level greater than 11.0 mmol/L), and the presence of either factor above the cutoff level as indicative of severe disease, the sensitivity of prediction was 79%, specificity 67%, and overall accuracy 70%. All the deaths were correctly predicted by this urea/glucose criteria. The overall accuracy was also found to be comparable with those of the APACHE II (cutoff level greater than 11) and Ranson's scoring systems. We conclude that the simple prognostic criteria for acute pancreatitis were validated; these criteria have the potential to stratify risk rapidly at the time of admission for patients who might benefit from an aggressive interventional protocol.

Acute Disease↗
PubMed1993

Human menopausal gonadotropin during in vitro maturation of human oocytes retrieved from small follicles enhances in vitro fertilization and cleavage rates.

OBJECTIVES: To compare the IVF rates of oocytes retrieved from small follicles (< 2 mL in volume) with those of oocytes retrieved from large follicles and to test the effect of adding gonadotropins to the IVF medium on the fertilization rates of oocytes from small follicles. DESIGN: Oocytes were retrieved with endovaginal ultrasound (US) guidance from patients undergoing infertility treatment in our IVF program. Oocytes were grouped according to the volume of the originating follicle and subjected to our routine procedure for IVF. HMG was added to the IVF medium for some of the oocytes from small follicles. SETTING: Toronto Fertility and Sterility Institute is affiliated with the University of Western Ontario and University of Toronto and is equipped for RIA, endovaginal US monitoring and oocyte retrieval, and for processing and culturing gametes and embryos. PATIENTS: Infertile patients admitted to our IVF program. INTERVENTIONS: Patients underwent ovarian stimulation with hMG before oocyte retrieval. No other interventions were introduced to the processing and culturing the gametes and embryos except the addition of hMG to the medium of some of the small follicle-originated oocytes with the informed consent from the patients. MAIN OUTCOME MEASURES: Rates of fertilization, cleavage of the fertilized embryos before replacement, and meiotic status of some of the oocytes from small follicles. RESULTS: Most of the oocytes from small follicles did not complete the first meiotic division; they had low rates of fertilization and cleavage compared with oocytes from large follicles, and these rates were improved by the addition of hMG to the IVF medium. CONCLUSIONS: Oocytes from small follicles are probably less mature and require a more physiological environment to achieve normal rates of fertilization and cleavage.

Adult↗
PubMed1993

A comparison of transhiatal and transthoracic resection for oesophageal carcinoma.

We compared the results of 327 transthoracic (TT) resections and 82 transhiatal (TH) resections for carcinoma of the oesophagus operated on between July 1982 and June 1991. Significantly more patients with carcinoma of the lower third of the oesophagus (54% versus 28%) and with increased pulmonary risks for surgery (61% versus 22%) were selected for the TH approach as compared with the TT approach. Results showed comparable intraoperative complications between the two groups. 5% of patients in the TH group required a thoracotomy for control of haemorrhage (3 patients) and repair of bronchial tear (1 patient) which occurred during the transmediastinal dissection. Postoperatively, mechanical ventilation requirement and complications involving the cardio-pulmonary systems were similar between the two groups. Anastomotic leakage occurred in 3% and 4%, respectively for the TH and TT patients (p = NS), whereas hoarseness occurred in 16% and 5%, respectively (p = 0.001). The 30-day mortality rates and hospital mortality rates were comparable between the two groups as were the overall survival rates. Our results suggested that while TH resection did not diminish the operative morbidity and mortality rates overall, it is appropriate for patients with increased pulmonary risks to be preferentially selected for this approach, and for tumours located in the upper and lower portion of the thoracic oesophagus where dissection of the tumour can be carried out mostly under vision.

Aged↗
PubMed1993

Current expectations for survival and complications in coronary artery bypass grafting.

The outcome of coronary artery bypass surgery is best assessed in terms of two independent components: the operative mortality and complications on the one hand, and the late survival and relief of symptoms on the other. The expected operative mortality rate in a particular patient can be calculated with reasonable accuracy from preoperative risk factors. This calculation also enables results from different units to be compared by correcting for the preoperative risk factors in the patient population. Despite improvements in cardiopulmonary bypass, there is still a low but appreciable incidence of subtle neuropsychological changes induced by coronary artery bypass grafting. The expected long-term results of the procedure must be determined from the results of surgery in the past. However, allowance must be made for two new influences. One is the expected improvement in the long-term results of current surgery, due to the improved longevity of currently used graft conduits such as the internal mammary artery. The other is the worsening of late results of present-day coronary artery bypass grafting caused by the greater number of preoperative risk factors in patients currently accepted for surgery, such as old age, impaired left ventricular function, and reoperation.

Coronary Artery Bypass↗