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Biomedical subjects

J Wong

Publications and source records attributed to J Wong.

At least 433 records · Page 24Linked to original sources
PubMed1995

Cancer of the oesophagus and gastric cardia. Standard oesophagectomy and anastomotic technique.

We reviewed the operative results of 785 one-stage resections for carcinoma of the oesophagus and cardia, out of a total of 1,264 patients with this tumour managed over a 12-year period (62%). Resection was considered curative in 321 patients (41%), and was palliative in 464 patients (59%). Seventy percent of patients had operative Stage III disease, while 5% had Stage IV disease. The two most frequently performed procedures were the transthoracic Lewis-Tanner operation (49%), and the transhiatal oesophagectomy (14%). Our results showed comparable operative morbidity, mortality and survival between the two resection groups, with the exception of a higher risk of recurrent nerve injury after the transhiatal operation (18% versus 9%). The results were based on selection criteria favouring patients with increased pulmonary risks for the transhiatal approach, while patients with advanced middle-third tumour were selected for the transthoracic approach. The overall leakage rate was 4%, and was the same for anastomosis made by the hand-sewn method, using a single layer continuous absorbable monofilament suture, and anastomosis made with circular stapler. The leakage rate was the same irrespective of whether the anastomosis was made in the neck or in the chest. However, stapled anastomosis has the disadvantage of a higher risk of fibrotic stricture formation. The 30-day and hospital mortality for the 785 patients was 5% and 14%, respectively. An improvement in the hospital mortality was observed over the 12-year period, with a 16% incidence for the first six years, and 11% for the subsequent six years (P = 0.03). The five-year survival after curative and palliative resection was 35% and 6%, respectively, and was 18% overall.

Anastomosis, Surgical↗
PubMed1995

Pulsatile buttock mass: report of two cases and a review of the literature.

The presence of any pulsatile mass suggests an underlying aneurysm. When such masses occur in the buttock, the differential diagnosis includes aneurysms arising from branches of gluteal vessels or aneurysms developing in a persistent sciatic artery (PSA). The investigation and management of two patients with pulsatile masses are described. Review of the embryologic aspects of these masses and the important literature on the subject led to the conclusions that when a pulsatile buttock mass is encountered, an anomalous PSA should be suspected. A gluteal artery aneurysm can be treated by ligation or occlusion, but for a sciatic artery aneurysm surgical ablation is necessary and distal perfusion must be achieved postoperatively.

Adult↗
PubMed1994

Perioperative nutritional support in patients undergoing hepatectomy for hepatocellular carcinoma.

BACKGROUND: Resection of hepatocellular carcinoma is associated with high rates of morbidity and mortality. Since intensive nutritional support can reduce the catabolic response and improve protein synthesis and liver regeneration, we performed a prospective study to investigate whether perioperative nutritional support could improve outcome in patients undergoing hepatectomy for hepatocellular carcinoma. METHODS: We studied 124 patients undergoing resection of hepatocellular carcinoma. Sixty-four patients (39 with cirrhosis, 18 with chronic active hepatitis, and 7 with no associated liver disease) were randomly assigned to receive perioperative intravenous nutritional support in addition to their oral diet, and 60 patients (33 with cirrhosis, 12 with chronic active hepatitis, and 15 with no associated liver disease) were randomly assigned to a control group. The perioperative nutritional therapy consisted of a solution enriched with 35 percent branched-chain amino acids, dextrose, and lipid emulsion (50 percent medium-chain triglycerides) given intravenously for 14 days perioperatively. RESULTS: There was a reduction in the overall postoperative morbidity rate in the perioperative-nutrition group as compared with the control group (34 percent vs. 55 percent; relative risk, 0.66; 95 percent confidence interval, 0.45 to 0.96), predominantly because of fewer septic complications (17 percent vs. 37 percent; relative risk, 0.57; 95 percent confidence interval, 0.34 to 0.96). There were also a reduction in the requirement for diuretic agents to control ascites (25 percent vs. 50 percent; relative risk, 0.57; 95 percent confidence interval, 0.37 to 0.87), less weight loss after hepatectomy (median loss, 0 kg vs. 1.4 kg, P = 0.01), and less deterioration of liver function as measured by the change in the rate of clearance of indocyanine green (-2.8 percent vs. -4.8 percent at 20 minutes, P = 0.05). These benefits were seen predominantly in the patients with underlying cirrhosis who underwent major hepatectomy. There were five deaths during hospitalization in the perioperative-nutrition group, and nine in the control group (P not significant). CONCLUSIONS: Perioperative nutritional support can reduce complications after major hepatectomy for hepatocellular carcinoma associated with cirrhosis.

Adult↗
PubMed1994

Transcriptional repression of Xenopus TR beta gene is mediated by a thyroid hormone response element located near the start site.

We report here the detailed analysis of the promoter of a thyroid hormone receptor (TR) gene that is regulated by the hormone itself. The receptor gene, TR beta A, is one of the two TR beta genes in Xenopus laevis. It has two transcription start sites. The mRNAs derived from one of them are up-regulated by thyroid hormone, whereas those derived from the other are independent of the hormone. We have characterized the hormone-inducible promoter using a transient transfection assay in a Xenopus tissue culture cell line (A6). Deletion and mutational analysis identifies the first amphibian thyroid hormone response element (TRE). This TRE consists of near perfect direct repeats of AGGTCA with a 4-base pair spacing similar to mammalian TREs. The TRE forms specific complexes with extracts of A6 cells that have similar sequence specificities as those found for the complexes between mammalian TRs and TREs. However, unlike TREs found in other thyroid hormone-inducible promoters, this TRE is located at the putative transcription start site and mediates transcriptional repression by unliganded TRs. The addition of thyroid hormone at physiological concentrations overcomes the repression and induces further transcriptional activation at higher concentrations. These results suggest a potential mechanism for the regulation of amphibian metamorphosis, a process that is entirely controlled by thyroid hormone.

Animals↗
PubMed1994

Small cell carcinoma of the esophagus.

BACKGROUND: Small cell carcinoma of the esophagus is regarded as having a poor prognosis with frequent systemic dissemination. METHODS: A review of the records and histologic sections of 11 patients with primary small cell carcinoma of the esophagus seen in 11 years was undertaken. They were analyzed and compared with the more common squamous cell carcinomas and adenocarcinomas. RESULTS: Small cell carcinoma of the esophagus constituted 1% of all esophageal tumors and was mainly located at the middle and lower thirds (90%) of the esophagus. Primary treatment consisted of tumor resection in five patients (46%), chemotherapy and radiotherapy in two (18%); surgical bypass in one (9%), radiotherapy after exploratory laparotomy in one (9%), intubation in one (9%), and no active intervention in one (9%). Two of the five resected tumors were Stage IIB disease, and three were Stage III disease. Five of the six patients in the non-resection group had distant metastases at presentation (45% of all patients). The median survival of patients who had chemotherapy (three of whom also had radiotherapy) was 16.7 months (range, 2.8-72 months) and was 2.2 months (range, 4 days to 9.1 months) for those with no chemotherapy. The overall median survival was 3.1 months for all patients. The prognosis was not significantly different from those with squamous cell carcinomas or adenocarcinomas. CONCLUSIONS: Small cell carcinoma of the esophagus should be regarded as a systemic disease, and multimodality treatment, including chemotherapy, should be used. Surgery may be offered in selected patients to manage local disease as part of a chemotherapy-based treatment program.

Adenocarcinoma↗
PubMed1994

Resection for extrahepatic recurrence of hepatocellular carcinoma.

A total of 277 patients with hepatocellular carcinoma (HCC) underwent hepatic resection over a 20-year period. Twelve of 36 patients with recurrence confined to extrahepatic organs underwent surgical resection. There were no complications but one patient died in hospital from secondary intrahepatic recurrence. The 1-, 2- and 5-year survival rates for these 12 patients after hepatic resection were 92, 52 and 26 per cent respectively and were better than those of 24 patients who did not undergo resection for recurrence. The mean survival following resection for recurrent disease was 19.7 months and the longest survival time was nearly 8 years. Secondary recurrence after resection of metastases developed more commonly in the liver than in extrahepatic organs. Among the eight patients who survived for more than 4 months after the second operation, secondary recurrence developed in the liver and extrahepatic organs in eight and four patients respectively. In selected patients with isolated extrahepatic recurrence of HCC, surgery is effective in controlling extrahepatic disease and offers the only chance of long-term survival.

Abdominal Neoplasms↗
PubMed1994

Preoperative endoscopic drainage for malignant obstructive jaundice.

The role of preoperative endoscopic drainage for patients with malignant obstructive jaundice was evaluated in a randomized controlled trial. A total of 87 patients were assigned to either early elective surgery (44 patients) or endoscopic biliary drainage followed by exploration (43). Thirty-seven patients underwent successful stent insertion and 25 had effective biliary drainage. Complications related to endoscopy occurred in 12 patients. After endoscopic drainage significant reductions of hyperbilirubinaemia, indocyanine green retention and serum albumin concentration were observed. Patients with hilar lesions had a significantly higher incidence of cholangitis and failed endoscopic drainage after stent placement. The overall morbidity rate (18 patients versus 16) and mortality rate (six patients in each group) were similar in the two treatment arms irrespective of the level of biliary obstruction. Despite the improvement of liver function, routine application of endoscopic drainage had no demonstrable benefit. Endoscopic drainage is indicated only when early surgery is not feasible, especially for patients with distal obstruction.

Aged↗
PubMed1994

Matrix crystals in cytologic urine specimens: observations on their mineral composition by energy dispersive X-ray microanalysis and morphologic scanning electron microscopy.

Crystals consisting by light microscopy of organic matrix (matrix crystals) encountered in cytologic urine specimens of 8 patients were examined for mineral phase components by scanning electron microscopy with energy dispersive X-ray microanalysis (SEM-EDX) and by morphologic scanning electron microscopy (SEM) performed separately in four of the eight cases. Whenever possible (three cases) mineralized crystals present in these specimens were examined separately by SEM-EDX for comparison of mineral phase composition with that of the corresponding matrix forms. Although by SEM-EDX components of matrix, glass and slide preparation media interfere with the precise estimation of the mineral phase components, the results of this method supported by the SEM morphology suggest that crystals consisting of organic matrix include a mineral phase, the lattice structure of which provides them from the early stages of formation with the characteristic morphology of the fully mineralized forms. This also suggests that organic matrix plays a role in the nucleation of minerals during the formation of certain urinary crystals.

Adult↗
PubMed1994

Modulation of human fibroblast activity by selected angiogenesis inhibitors.

Tenon's fibroblast (TF) bleb encapsulation is a common cause of filtering surgery failure. Various pharmacologic agents have been used in an attempt to inhibit this response. The effects of three angiogenesis inhibitors were studied. AGM-1470, a fumagillin analog and hydrocortisone 21-phosphate (HC21P) complexed with heparin or with the heparin analog beta-cyclodextrin tetradecasulfate (BCD-TDS) in modulating human tenon's fibroblasts in cell culture. It has been clinically demonstrated that well vascularized blebs are associated with a poorer prognosis. In addition to reducing bleb neovascularization, angiogenesis inhibitors may have an additional therapeutic role in decreasing fibroblast activity. Drug effects were assessed by studying cell growth rates by cell Coulter counting and rate of wound closure. TF's were grown in DMEM with 10% FBS and 1% PCN-strep with fungizone. Angiogenesis inhibitors were added to growth medium in varying concentrations: AGM-1470 alone, HC21P complexed with heparin and HC21P complexed with BCD-TDS. Controls were grown in control medium alone, medium with added ethanol, or with added BCD-TDS, heparin or HC21P. We found a dose related inhibition of cell growth with all of the angiogenesis inhibitor combinations, which was not seen in the control groups. Tenon's fibroblast proliferation was significantly inhibited by AGM-1470 as seen in the four higher concentrations (P < 0.05) with insignificant inhibition at the lowest concentration of AGM-1470 (P = 0.38). The heparin:HC21P and heparin:BCD-TDS combinations demonstrated significant inhibition at all concentrations (P < 0.05). Wound closure was significantly inhibited by all the added agents, except AGM-1470 and the controls. The rate of wound closure was significantly reduced by the highest concentrations of the heparin:HC21P and heparin:BCD-TDS combinations (P < 0.05), although it was not significantly affected by lower concentrations (P > 0.05). Rank order of potencies of these agents for inhibition of TF proliferation was AGM-1470, BCD-TDS:HC21P, heparin:HC21P, HC21P, while the rank order of potencies for these agents for inhibition of wound closure was HC21P, heparin:HC21P, BCD-TDS:HC21P, AGM-1470. These selected angiogenesis inhibitors appear to have marked inhibitory effects on TF proliferation and migration, which may have a potential clinical role in modulating wound healing associated with glaucoma filtering surgery.

Cell Division↗
PubMed1994

Neodymium:yttrium-aluminum-garnet laser for the treatment of tracheobronchial recurrences in esophageal carcinomas.

Tracheobronchial recurrence occurred in 55 of 559 patients (9.8%) after resection of their esophageal carcinomas and in 22 of 109 patients (20.2%) after a bypass operation. The risk of airway recurrence increases if residual disease is present in the mediastinum at resection. The median survival of 55 patients diagnosed with tracheobronchial recurrence before July 1988 was 3.7 weeks. After July 1988, there were 22 patients in whom tracheobronchial recurrence developed, 19 of whom were treated by neodymium:yttrium-aluminum-garnet laser under local anesthesia. Additional external radiotherapy was offered to 8 patients who responded to laser treatment and were in satisfactory condition. Four of these patients (21%) had complete tumor regression. Partial regression occurred in 7 patients (37%): 2 were treated by combined therapy and 5 by laser alone. Most tolerated the laser treatment well, but the procedure was abandoned in 6 patients because of smoke inhalation. A tracheoesophageal fistula developed in 2 patients. The median survival for the entire group was 7.4 weeks, with 3 long survivors who lived more than 1 year. The combined application of laser and external radiotherapy is effective for the treatment of tracheobronchial recurrences in patients with esophageal carcinoma.

Bronchial Neoplasms↗
PubMed1994

Pharmacokinetic interactions between midazolam and propofol: an infusion study.

We have tested the hypothesis that the synergistic interaction which occurs when midazolam and propofol are combined for i.v. sedation is caused by an increase in the free plasma concentration of one of the drugs. Six patients undergoing general anaesthesia received an infusion of propofol with the addition of an infusion of midazolam commenced 30 min later. Another six patients received an infusion of midazolam with the addition of an infusion of propofol 30 min later. All infusions were administered via pharmacokinetic model-controlled syringe pumps programmed to maintain a constant plasma concentration. Venous blood samples were taken before and after introduction of the second infusion for later analysis. Free plasma concentration of midazolam increased from 2.0 (SD 1.5) ng ml-1 to 2.2 (1.9) ng ml-1 after introduction of the propofol infusion (P = 0.32). Free propofol plasma concentration was unchanged at 18.5 (5.3) ng ml-1 before and 18.7 (7.8) ng ml-1 after introduction of the midazolam infusion (P = 0.94). It was concluded that the observed synergism with this combination cannot be explained solely by alteration in free plasma concentration of either of these drugs when they are administered together.

Adolescent↗
PubMed1994

A prospective evaluation of pharmacokinetic model controlled infusion of propofol in paediatric patients.

We have tested a published algorithm for pharmacokinetic model controlled infusion of propofol to supplement 67% nitrous oxide for general anaesthesia in Chinese children aged 4-10 yr. Initially we studied 10 children undergoing minor procedures with spontaneous ventilation; mean duration of surgery was 38 min and mean propofol infusion rate 497 micrograms kg-1 min-1. The precision of the model was 24.8% and bias -18.5%. The model was revised using an iterative linear least squares regression procedure and the revised model tested prospectively in another 20 children. The precision of the revised model was 21.5% (range in individuals 8.4-43.1%) and bias -0.1% (range -30 to 42%). Mean propofol infusion rate required to maintain anaesthesia was 474 micrograms kg-1 min-1 (range 125-737 micrograms kg-1 min-1). The mean blood concentration required for satisfactory anaesthesia was 6.6 micrograms ml-1 (range 3-11 micrograms ml-1) and the mean blood concentration at the time of waking, which occurred 40 min after switching off the infusion, 0.86 microgram ml-1 (range 0.40-1.45 micrograms ml-1). Our patient population required different pharmacokinetic variables from those in the previous study. Recovery was slow because of the high infusion rates required to maintain satisfactory anaesthesia and large difference between the blood concentration required for anaesthesia and that at which waking occurred.

Algorithms↗
PubMed1994

Diethylamine/nitric oxide (NO) adduct, an NO donor, produces potent pulmonary and systemic vasodilation in intact newborn lambs.

Nitric oxide (NO), a labile humoral factor produced by vascular endothelial cells, is a potent vasodilator and an important mediator of pulmonary vascular tone. Nucleophile/NO adducts are a new class of compounds that spontaneously and predictively release NO. We investigated the hemodynamic effects of intravenous (i.v.) infusions of a recently developed NO-donor drug, the diethylamine-nitric oxide adduct (DEA/NO), in 17 intact newborn lambs. At rest, DEA/NO (1-2 microgram.kg-1.min-1) produced dose-dependent decreases in mean pulmonary (from 10.6 +/- 8.6 to 21.2 +/- 7.9%, p < 0.05) and systemic arterial pressure (from 13.2 +/- 11.7 to 31.0 +/- 15.4%, p < 0.05). Similarly, during pulmonary hypertension induced by infusion of U46619, DEA/NO (0.5-2.0 micrograms.kg-1.min-1) produced dose-dependent decreases in mean pulmonary (from 7.3 +/- 5.6 to 24.1 +/- 13.3%, p < 0.05) and systemic arterial pressure (from 2.2 +/- 3.8 to 20.3 +/- 12.9%, p < 0.05). Cardiac output (CO), heart rate (HR), systemic arterial blood gases, and pH were unchanged; atrial pressures decreased at higher doses. Equimolar infusions of S-nitroso-N-acetyl-penicillamine, nitroglycerin (NTG), and sodium nitroprusside (SNP) produced similar decreases in pulmonary and systemic arterial pressure. The nucleophile/NO adducts are potent vasodilators; their predictable and quantitative release of NO make them potentially useful research tools. In addition, because these compounds may decrease the incidence of tolerance and the risk from toxic metabolites associated with use of other nitrovasodilators, they may be clinically useful.

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

Evaluation of indocyanine green retention and aminopyrine breath tests in patients with malignant biliary obstruction.

Impaired hepatic function is a major contributory factor to the high incidence of postoperative morbidity and mortality in patients with malignant biliary obstruction. Dynamic hepatic function tests such as indocyanine green (ICG) retention and aminopyrine breath tests were evaluated in such patients to define whether they were clinically useful for prediction of postoperative morbidity and mortality. Forty-four patients with malignant biliary obstruction undergoing surgery for relief of obstructive jaundice were recruited into the study. Indocyanine green retention and aminopyrine breath tests were carried out in all patients pre-operatively and repeated in 36 patients postoperatively. The ICG retention was abnormal in all patients before surgery and there was significant improvement 2 weeks after surgery (32.8 +/- 2.5% vs 18.3 +/- 2.8%, P = 0.001). The change in ICG retention levels correlated with the serum bilirubin levels but the pre-operative ICG retention value could not predict postoperative morbidity and mortality. The aminopyrine breath test was abnormal in all but one patient. It correlated with pre-operative prothrombin time of the patients before surgery but it did not improve significantly after surgery and was not predictive of postoperative outcome. It is concluded that both ICG retention and aminopyrine breath tests have limited clinical value in the pre-operative evaluation of patients with malignant biliary obstruction.

Aged↗
PubMed1994

Catheter ablation of the atrioventricular node using radiofrequency energy.

BACKGROUND: Catheter ablation of the atrioventricular (AV) junction using stored direct current (DC) energy from a standard DC Cardioverter defibrillator was first reported in 1982. Since then many patients have been treated using this procedure for refractory supraventricular arrhythmias, usually atrial fibrillation and flutter. Undesirable thermal effects such as barotrauma and arcing are largely responsible for complications associated with the use of DC energy. This report details our experience of catheter ablation of the AV junction using radiofrequency (RF) energy in a series of 30 consecutive patients. METHODS: RF ablations were performed using steerable Mansfield (Webster Laboratories) 4 mm tipped electrodes and locally assembled RF energy delivery system. RESULTS: The procedure was successful in 27/30 (90%) patients using RF energy, while three patients required DC energy to achieve successful AV junction ablation. General anaesthesia was required in nine patients, six of whom required this for cardioversion to sinus rhythm so that an adequate His Bundle spike could be recorded and three for DC ablation. Dual chamber permanent pacemakers with automatic mode switching were implanted in four patients who had paroxysmal atrial fibrillation or flutter and the remainder had ventricular rate responsive pacemakers. CONCLUSIONS: In patients with drug refractory paroxysmal atrial fibrillation and flutter and in patients with established atrial fibrillation where control of the ventricular rate is difficult, catheter ablation of the AV junction using RF energy is a safe and effective procedure with a high success rate.

Atrial Fibrillation↗
PubMed1994

Chronic nitric oxide inhibition in utero produces persistent pulmonary hypertension in newborn lambs.

Persistent pulmonary hypertension of the newborn (PPHN) is associated with chronic intrauterine events. Acute nitric oxide (NO) inhibition attenuates the normal increase in pulmonary blood flow at birth. We investigated whether chronic NO inhibition in utero causes persistent pulmonary hypertension. 11 fetal lambs received either a continuous infusion of N omega-nitro-L-arginine (an NO synthesis inhibitor) or 0.9% saline. Before infusion, acetylcholine (dependent upon endogenous NO production) and sodium nitroprusside (which releases its own NO) produced potent pulmonary vasodilation. After 10.5 +/- 1.5 d of infusion, acetylcholine did not produce pulmonary vasodilation in N omega-nitric-L-arginine-treated fetal lambs, but did in saline-treated fetal lambs; sodium nitroprusside produced pulmonary vasodilation in both groups. Immediately after birth, at 140 d of gestation, during the 3-h study period, mean pulmonary arterial pressure did not decrease in N omega-nitro-L-arginine-treated lambs; the increase in pulmonary blood flow and decrease in pulmonary vascular resistance were markedly attenuated compared to saline-treated lambs. These hemodynamic derangements were reversed by L-arginine. There were no anatomic abnormalities in the pulmonary circulation. Chronic NO inhibition in utero reproduces many of the physiologic derangements of PPHN. Intrauterine events which result in endothelial dysfunction and inhibition of NO may produce the physiologic derrangements of PPHN.

Animals↗