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Biomedical subjects

J Wong

Publications and source records attributed to J Wong.

At least 19 recordsLinked to original sources
PubMed1992

Endoscopic biliary drainage for severe acute cholangitis.

BACKGROUND: Emergency surgery for patients with severe acute cholangitis due to choledocholithiasis is associated with substantial morbidity and mortality. Because recent results suggested that emergency endoscopic drainage could improve the outcome of such patients, we undertook a prospective study to determine the role of this procedure as initial treatment. METHODS: During a 43-month period, 82 patients with severe acute cholangitis due to choledocholithiasis were randomly assigned to undergo surgical decompression of the biliary tract (41 patients) or endoscopic biliary drainage (41 patients), followed by definitive treatment. Hospital mortality was analyzed with respect to the use of endoscopic biliary drainage and other clinical and laboratory findings. Prognostic determinants were studied by linear discriminant analysis. RESULTS: Complications related to biliary tract decompression and subsequent definitive treatment developed in 14 patients treated with endoscopic biliary drainage and 27 treated with surgery (34 vs. 66 percent, P greater than 0.05). The time required for normalization of temperature and stabilization of blood pressure was similar in the two groups, but more patients in the surgery group required ventilatory support. The hospital mortality rate was significantly lower for the patients who underwent endoscopy (4 deaths) than for those treated surgically (13 deaths) (10 vs. 32 percent, P less than 0.03). The presence of concomitant medical problems, a low platelet count, a high serum urea nitrogen concentration, and a low serum albumin concentration before biliary decompression were the other independent determinants of mortality in both groups. CONCLUSIONS: Endoscopic biliary drainage is a safe and effective measure for the initial control of severe acute cholangitis due to choledocholithiasis and to reduce the mortality associated with the condition.

Acute Disease↗
PubMed1992

Pickled vegetables in the aetiology of oesophageal cancer in Hong Kong Chinese.

Oesophageal cancer is common in Chinese populations, but individual-based epidemiological studies have provided little explanation. A case control study with 400 cases and 1598 controls (800 hospital and 798 general practice) was conducted among Hong Kong Chinese. In multivariate analyses, statistically significant effects on risk were detected for several potentially preventable exposures with high attributable risks (ARs). These included preference for consuming drinks or soups at high temperature (AR = 14%), infrequent consumption of green leafy vegetables (AR = 15%) and citrus fruits (AR = 26%), ingestion of pickled vegetables (AR = 29%), tobacco smoking (AR = 44%), and alcohol drinking (AR = 48%). On the assumption of multiplicative risk, the combined AR due to these exposures was 89%. This is the first case control study to show an association between pickled vegetable consumption and oesophageal cancer risk. The finding considerably strengthens the evidence for carcinogenicity of N-nitroso compounds in man and helps to explain the very high risk among Chinese.

Aged↗
PubMed1992

Infected femoral pseudoaneurysm in intravenous drug abusers.

The result of surgical treatment of 21 infected femoral pseudoaneurysms in 19 intravenous drug addicts was evaluated. Eight pseudoaneurysms involved only the common or superficial femoral artery and 13 involved the femoral bifurcation. Excision and ligation was performed as the sole procedure in 19 instances, and revascularization by bypass through the obturator route was carried out in two. The mean follow-up was 12.3 months. One patient required an above-knee amputation. The resultant ischaemia was greater after triple vessel ligation (mean ankle:brachial pressure index (ABPI) 0.41) than single vessel ligation (mean ABPI 0.58). Postoperative bleeding occurred in one patient. Intermittent claudication was present in 14 patients after excision and ligation. Claudication was universal and more severe after triple than after single vessel ligation. There was no subsequent limb loss. Excision and ligation is safe and is the treatment of choice for infected femoral pseudoaneurysm in drug addicts.

Adult↗
PubMed1992

Self-setting hydroxyapatite cement: a novel skeletal drug-delivery system for antibiotics.

A novel approach using a self-setting hydroxyapatite (HAP) cement as a skeletal drug-delivery system has been proposed to solve the problem of delivering drugs to skeletal tissue at sufficiently high local concentrations for desirable therapeutic effects. HAP cements loaded with antibiotics can be formed in situ and can be used as bonding materials between bone and prostheses, as well as drug-release devices. The cement also possesses sufficient mechanical strength to be a potential bone grafting material. Using cephalexin and norfloxacin as model drugs, we observed continuous in vitro release profiles of these compounds from cement pellets loaded 0.9-4.8% by weight with one of the drugs. This drug-release pattern correlated well with the Higuchi model. This hydroxyapatite cement drug-delivery system can be applied in the treatment of osteomyelitis and infected compound fractures.

Anti-Bacterial Agents↗
PubMed1992

Gross and histological abnormalities of the foregut in familial adenomatous polyposis: a study from a South East Asian Registry.

Polyps in the stomach and duodenum are frequently found in familial adenomatous polyposis. Cancer arising from some of these polyps may be an important cause of death in patients who have had large bowel resections. This study aims to determine the nature and distribution of foregut polyps in Chinese patients. Twenty-five patients with familial adenomatous polyposis were gastroscoped by a single operator using the end viewing video-endoscopy system. Representative biopsies of normal mucosa or polyps where appropriate were taken from the gastric fundus, antrum and the duodenum. Twenty-five patients were studied. Male = 17, female = 8. Median age was 32 years (range = 17-63 yrs). Nineteen patients were found to have macroscopically visible polyps in the foregut. Ten patients had gastric polyps alone, three patients had duodenal polyps alone whilst six patients had both gastric and duodenal polyps. Twelve, one and three patients had more than 20 polyps in the gastric fundus, antrum and duodenum respectively. Only one patient had polyps which were larger than 10 mm. The commonest polyp in the gastric fundus was the fundic gland polyp whilst hyperplastic and adenomatous polyps were the commonest polyps in the gastric antrum and duodenum respectively. Five patients had adenomatous polyps of which four had duodenal adenomas alone whilst one patient had adenomas in the duodenum, gastric antrum and fundus. Seventy-six per cent of our patients with familial adenomatous polyposis had foregut polyposis. Adenomatous polyps were found in 56% of patients with duodenal polyps or 20% of patients with foregut polyps but hyperplastic and hamartomatous polyps occur commonly in patients with familial adenomatous polyposis as well.

Adenomatous Polyposis Coli↗
PubMed1992

Choice of palliation for malignant hilar biliary obstruction.

Clinical data from 50 consecutive patients with unresectable hilar tumors situated at or proximal to the common hepatic duct were retrospectively analyzed to aid in the selection of appropriate palliative measures. Thirty-four patients had cholangioenteric bypass (CEB) to either left (28 patients), right (3 patients), or both (3 patients) intrahepatic ductal systems. Sixteen patients had nonoperative drainage (NOD) established either endoscopically (4 patients), percutaneously (9 patients), or using a combined endoscopic-percutaneous approach (3 patients). When compared with patients with CEB, patients with NOD had more frequent medical problems (p less than 0.03) and lower serum albumin levels on admission (p less than 0.03). While comparable postprocedural complications (13 CEB patients versus 4 NOD patients) were observed, patients with NOD had a significantly higher hospital mortality (9 CEB patients versus 9 NOD patients, p less than 0.05). Excluding the 12 patients (6 CEB patients versus 6 NOD patients) who died within 30 days after drainage, the quality of survival of the remaining 38 patients was analyzed with reference to 6 objective parameters. Although patients with NOD had significantly more frequent admissions relating to their catheters (p less than 0.02), there was no qualitative difference in the survival rate between the two groups of patients. For selected high-risk patients with limited life expectancy, NOD should be offered. However, additional prospective studies are required to decide the best choice of palliation for patients who are not at such high risk.

Aged↗
PubMed1992

Immediate and long-term results of percutaneous balloon aortic valvuloplasty: a report of 33 procedures.

The purpose of this study was to evaluate the immediate and long-term clinical and haemodynamic effects of Percutaneous Balloon Aortic Valvuloplasty (PBAV). Thirty-three procedures were performed in 27 patients, 11 males and 16 females with a mean age of 72 years. The peak to peak systolic gradient across the aortic valve decreased by 52%, from 67 +/- 24 mmHg to 31 +/- 15 mmHg (p < 0.0001) and the aortic valve area increased by 35%, from 0.48 +/- 0.16 to 0.67 +/- 0.21 cm2 (p < 0.001) after PBAV. There were no procedural deaths. Minor complications occurred in seven patients. Eighty-one per cent of patients (27 procedures) showed immediate symptomatic improvement, five remained symptomatic and one died in hospital before discharge. In a mean follow-up of 17 +/- 12 months (range six to 38 months), eight patients died due to congestive cardiac failure, six underwent repeat PBAV, three died due to noncardiac causes and three had recurrent symptoms controlled on medical therapy. Event free survival at 15 months was 43%. In conclusion PBAV produces a satisfactory immediate clinical and haemodynamic result, however, considering the high rate of symptom recurrence, this procedure has a beneficial role only in short-term palliation of severely symptomatic patients who are unable to undergo aortic valve replacement.

Actuarial Analysis↗
PubMed1992

Combined effects of laser irradiation and chemical inhibitors on the dissolution of dental enamel.

It has previously been shown that the susceptibility of human teeth to acid dissolution can be reduced by the presence of various chemical agents in the dissolution medium or by pretreatment of the teeth with laser irradiation. Now synergism between these two approaches to improving acid resistance has been demonstrated. Extracted human teeth were irradiated with a continuous-wave carbon dioxide laser at a wavelength of 10.6 microns. Energy doses of either 65 or 130 J/cm2 given over periods of 2 or 4 s, respectively, were applied and the teeth subjected to a severe acid challenge (0.1 M acetate buffer, pH 4.5, no calcium or phosphate common ion present) for 24 h. Mineral loss was assessed by measurement of mineral density profiles with quantitative microradiography. Experiments were carried out in the presence or absence of three chemical inhibitors with distinctly different mechanisms of action: ethane-1-hydroxy-1, 1-diphosphonic acid, fluoride, and dodecylamine HCl. Laser irradiation alone was found to lead to increased resistance of the teeth to acid challenge, with the higher energy dose being more effective than the lower dose. Each of the chemical inhibitors was effective on both lased and unlased teeth, with the percent reduction of dissolution greater when the inhibitors were applied to teeth lased with an energy dose of 130 J/cm2 which were already more resistant to acid challenge than were unlased teeth or teeth lased with a dose of 65 J/cm2.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1992

Initial dissolution rate studies on dental enamel after CO2 laser irradiation.

The influence of CO2 laser irradiation on the dissolution behavior of human dental enamel has been investigated. Human enamel was irradiated by a continuous-wave CO2 laser at 10.6 microns and initial dissolution rates (IDRs) were measured in 0.1 mol/L acetate buffer, pH = 4.5, both with and without calcium and/or phosphate common ion, by means of a rotating disk assembly. The effects of (1-hydroxyethylidene) bisphosphonic acid (EHDP), fluoride (F), and dodecylamine HCl (DAC) at various levels upon the IDR were also determined. All of the findings were consistent with the hypothesis that CO2 laser irradiation converts dental enamel to hydroxyapatite (HAP) possessing site #2 character (Yamamoto et al., 1986). The dissolution driving force function, KHAP = aCa10aPO4(6)aOH2, was found to have a value of 10(-129.9) after being lased, as compared with 10(-121.4) before being lased. The IDR values for EHDP (3 mmol/L) and DAC (3 mmol/L) were essentially zero as expected for site #2 HAP. For solution F, the deduced dissolution driving force function, KFAP = aCa10aPO4(6)aF2 was 10(-128.6) after being lased as compared with 10(-116.3) before being lased. These results all support the hypotheses (1) that laser irradiation may convert the surface of human dental enamel to an apatite of significantly lower effective solubility (i.e., site #2 HAP) than that of unlased enamel; and (2) that there is significant synergism between laser treatment and these chemical dissolution rate inhibitors (again consistent with site #2 HAP). Simple model calculations indicate that, in both the presence and absence of fluoride, these laser-induced changes in the driving force for dissolution should dramatically lessen the susceptibility of enamel to the types of acid challenge that might be encountered in the mouth.

Amines↗
PubMed1992

The Singapore Polyposis Registry.

The Singapore Polyposis Registry was established in 1989 in Singapore General Hospital. The aim is to provide a central registry service to all doctors in Singapore to facilitate in identification, surveillance and management of families and individuals at high risk of getting colorectal cancer from FAP (Familial Adenomatous Polyposis) and HNPCC (Hereditary Non-polyposis Colorectal Cancer). Both have an autosomal dominant inheritance that gives rise to colorectal cancer at any early age if untreated. They account for 5-6% of all colorectal cancers. Sixteen FAP families with 139 members have been evaluated. Fifty-eight members are affected and 81 are at risk or unaffected. Those who have been screened positive have a much lower risk of cancer (13%) compared with those who presented with the disease (89%) and death from colorectal cancer in the corresponding groups were nil and 58%. Eight HNPCC families with 36 affected and 170 at-risk members have been registered. Colonoscopic surveillance have just started: one case of Dukes' A cancer in a 26 year-old patient, and two cases with polyps have been diagnosed. Advances in molecular genetics and the identification of APC (Adenomatous Polyposis Coli) gene in the FAP locus of Chromosome 5 have made it possible to diagnose FAP genetically. This has important impact on management in terms of prenatal diagnosis and dietary and chemoprevention programmes in addition to surgical intervention.

Adenomatous Polyposis Coli↗
PubMed1992

Surgery for malignant obstructive jaundice: analysis of mortality.

Surgery on patients with malignant obstructive jaundice carries formidable morbidity and mortality rates. Clinical records of 120 consecutive patients who had a serum total bilirubin levels of 100 mumol/L or greater before exploration were analyzed retrospectively to provide guidelines for better management. Although most patients underwent bilienteric bypass to either the extrahepatic (n = 45) or intrahepatic ductal system (n = 28), resection was possible in 32 (26.7%). Complications developed in 42 patients (35%), among whome 12 (10%) required reexploration and 32 (26.7%) died within the same hospitalization. Identification of risk factors associated with hospital deaths after surgery was conducted on 84 of the 120 (group A) patients randomly selected from the entire study period. Based on multivariate analysis, age greater than 65 years, a raised serum aspartate transaminase value greater than 90 IU, and serum urea level greater than 7 mmol/L before surgery were the risk factors selected from 39 different clinical (n = 6), laboratory (n = 26), and operative (n = 7) parameters studied. The predictive value was validated in the remaining 36 patients (group B), and a high-risk patient population had been isolated. Because both serum urea and aspartate transaminase values correlated significantly with the necessity of urgent exploration, aggressive nonoperative treatment should be used to control the emergency. Alternative therapeutic options or perioperative management should be considered for the selected high-risk patients before definitive surgical biliary decompression.

Adult↗
PubMed1992

Anastomotic complications after esophagectomy for cancer. A comparison of neck and chest anastomoses.

Leakage, tumor recurrence, and stricture formation at the anastomosis are serious problems after esophagectomy for cancer of the esophagus or cardia. Because the prevalence of these postoperative complications may be affected by whether an anastomosis is made in the neck or in the chest, a comparison was made between anastomoses made at these two sites. During a period of some 7 years, we studied prospectively 411 patients who underwent resection for cancer of the esophagus or cardia and, after immediate reconstruction, had an anastomosis made in the neck or chest. The anastomotic leak rate for the neck anastomosis group was 4.3% and for the chest anastomosis group, 3.7% (p = not significant). The difference between leak rates of anastomoses fashioned by hand-sewn (5.0%) or stapled (3.0%) techniques was also not significant. The median upper resection margins in the neck and chest anastomosis groups were 4.5 cm and 3.5 cm, respectively. The corresponding rates of anastomotic tumor recurrence were 6.1% and 8.1% (p = not significant). The prevalence of benign stricture formation was significantly higher in the chest anastomosis group (19.2%) than in the neck anastomosis group (9.0%) (p = 0.002). This difference was a reflection of a significantly increased prevalence of stricture formation when an anastomosis was made by the stapler technique than with the hand-sewn method, and whereas most of the anastomoses in the neck were hand sewn (90%) the majority of those in the chest were stapled (80%). There were thus no statistically significant differences between the sites in terms of anastomotic leak and tumor recurrence rates, and the higher stricture rate in the chest anastomosis group was the result of more stapled anastomoses.

Anastomosis, Surgical↗
PubMed1992

Single lung transplantation: replacement therapy for end-stage lung disease.

Advances in immunosuppression and operative techniques have allowed single lung transplantation to become a viable treatment option at selected medical centers. We describe eight patients, all from the southeastern United States, who had single lung transplantation at Vanderbilt University Medical Center from March 1990 to June 1991. Their diagnoses represent a diverse set of diseases including idiopathic pulmonary fibrosis, primary pulmonary hypertension, emphysema, and pulmonary veno-occlusive disease. After thorough evaluation, the average waiting period to transplantation was 165 days. The posttransplantation periods were conspicuous for rejection, infection, and other complications. All of these recipients have either returned to an active life or are actively recuperating; this center's first single lung recipient has now survived 15 months. Our initial experience with single lung transplantation is encouraging, yet broader application requires that the paucity of donor organ availability be rectified.

Adult↗
PubMed1992

A comparison of outcome after resection for squamous cell carcinomas and adenocarcinomas of the esophagus and cardia.

Among 625 patients with squamous cell carcinoma and 134 patients with adenocarcinoma of the esophagus and cardia, a one stage resection was performed upon 375 patients of the squamous carcinoma group (excluding pharyngolaryngoesophagectomy) and 92 patients in the adenocarcinoma group. The patients formed the basis of the current analysis. Male to female ratio was 7:1 for those with squamous carcinoma compared with 3.6:1.0 for those with adenocarcinoma (p = 0.037). Most squamous carcinomas were located in the middle one-third (56.3 percent) and lower one-third (33.0 percent) of the esophagus. Adenocarcinomas were predominantly found at the cardia (91.3 percent) and lower one-third (6.5 percent). Postoperatively, respiratory complications occurred in 34.4 percent of patients in the group with squamous carcinoma and in 19.6 percent of patients in the group with adenocarcinoma (p = 0.01). Cardiac complications occurred in 28.3 percent of patients in the group with squamous carcinoma and in 16.3 percent of patients in the group with adenocarcinoma (p = 0.03). Anastomotic leaks were uncommon for both groups (4.3 and 5.4 percent, respectively). Anastomotic recurrence occurred in 6.1 and 7.6 percent of patients, respectively. Respiratory complications, malignant cachexia and sepsis accounted for most of the deaths in the hospital. The 30 day mortality rates for patients with squamous carcinoma and adenocarcinoma were comparable (4.8 and 6.5 percent, respectively) (p = 0.33). After 30 days, mortality rates differed significantly (11.7 and 3.3 percent, respectively) (p = 0.026). The overall hospital mortality rates, however, were comparable (16.5 and 9.8 percent, respectively) (p = 0.14). The overall five year survival rate for both groups was 15 percent. For patients with squamous carcinomas, the five year survival rate after curative resection was 31 percent compared with 5 percent for palliative resection. For patients with adenocarcinomas, the respective five year survival rates were 35 and zero percent. It was concluded that the two types of tumor differ significantly in the incidence of postoperative morbidity, but mortality and the long term survival rates were similar.

Adenocarcinoma↗