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Biomedical subjects

J Wong

Publications and source records attributed to J Wong.

At least 235 records · Page 13Linked to original sources

Applicability of living donor liver transplantation to high-urgency patients.

BACKGROUND: Cadaveric liver donors are scarce in Hong Kong, and the application of liver transplantation to high-urgency patients is limited. We evaluated the use of grafts from living donors in this setting. METHODS: From July 1994 to January 1998, 49 consecutive adult patients who were intensive care unit-bound because of acute or chronic liver failure were put on a high-urgency list for liver transplantation. Family members were not solicited for living donation, and the initiation and decision for living donor liver transplantation (LDLT) was based on the donor's voluntary intent. Assessment of the living donor, including blood tests, computed tomographic volumetry, and angiography, was performed only after informed consent was executed. RESULTS: In 25 of 49 (51%) patients, no family member volunteered as living donor; 23 died awaiting donor organs, and 2 received a cadaveric graft. Twenty-four (49%) patients had 36 family members who volunteered as living donors. Before evaluation of living donor was completed, two patients received a cadaveric liver transplant. LDLT was not performed in nine patients because of recipient contraindications (n=4), ABO blood group incompatibility (n=3), and withdrawal of donor (n=2). Eight of these nine patients died, and one received a cadaveric liver graft. The remaining 13 (27%) patients received grafts from living donors. Four of 5 (80%) patients who underwent cadaveric liver transplantation and 11 of 13 (85%) who underwent LDLT survived. Thus, emergency transplantation from living donors increased the applicability of liver transplantation from 10% to 37%, and the survival rate after emergency LDLT (85%) was superior to that of the remaining patients (11%). CONCLUSIONS: When cadaveric organ donation is scarce, emergency liver transplantation from living donors can be applied to high-urgency adult patients.

Adolescent↗

Hepatectomy for hepatocellular carcinoma: the surgeon's role in long-term survival.

HYPOTHESIS: The surgeon can contribute substantially to the long-term survival rate of patients undergoing hepatectomy for hepatocellular carcinoma (HCC). DESIGN: The long-term survival rate of patients with HCC undergoing hepatectomy has improved, but the contribution of the surgeon to the improved survival rate is unknown. We surveyed 211 consecutive patients undergoing hepatectomy for HCC. The clinical, operative, and pathological factors were analyzed to identify factors that were important in affecting long-term survival. SETTING: A tertiary referral center. PATIENTS: From April 1989 to December 1995, 211 consecutive patients with HCC underwent 153 major and 58 minor hepatectomies. MAIN OUTCOME MEASURES: Disease-free and overall cumulative survival rate. RESULTS: The 5-year disease-free survival rate was 27%. By Cox regression analysis, blood transfusion (relative risk [RR], 1.21; 95% confidence interval [CI], 1.05-1.40) and TNM stage (RR, 1.90; 95% CI, 1.47-2.47) were shown to be independent prognostic factors in the 5-year disease-free survival rate. The 5-year overall cumulative survival rate was 37%. By Cox regression analysis, the preoperative indocyanine green retention value at 15 minutes after injection (RR, 1.03; 95% CI, 1.01-1.06), blood transfusion (RR, 1.191; 95% CI, 1.078-1.316), tumor rupture (RR, 1.48; 95% CI, 1.08-2.04), and TNM stage (RR, 1.62; 95% CI, 1.27-2.07) were shown to be significant independent factors that influenced cumulative survival rate. CONCLUSIONS: The long-term survival of patients with HCC after hepatectomy depends on tumor staging, preoperative hepatic functional reserve, history of blood transfusion, and rupture of HCC. Preoperative liver function and tumor staging cannot be altered; however, the surgeon can play an important role in improving the prognosis if blood transfusion and iatrogenic tumor rupture can be avoided and if function of the liver remnant can be preserved.

Carcinoma, Hepatocellular↗

Tolerance of the liver to intermittent pringle maneuver in hepatectomy for liver tumors.

BACKGROUND: Hepatectomy can be performed with a low mortality rate, but massive hemorrhage during the operation remains a potentially lethal problem. The Pringle maneuver is traditionally used during hepatectomy to reduce blood loss, but the effect on the metabolic function of hepatocytes is potentially harmful. Although our randomized study showed that an intermittent Pringle maneuver is safe and effective during hepatectomy, the upper limit of the duration of the Pringle maneuver is not known. HYPOTHESIS: The liver can tolerate intermittent Pringle maneuver if the duration is not excessive. DESIGN: From July 20, 1995, to November 25, 1997, 112 patients underwent hepatectomy for liver tumors. The data of 50 patients who had hepatectomy without the Pringle maneuver were compared with those of 62 patients who had a liver transection using a Pringle maneuver for 20 minutes and a 5-minute clamp-free interval. The data were collected prospectively. MAIN OUTCOME MEASURES: The surface area of liver transection was measured, and blood loss during liver transection per centimeter square of transection area was calculated. Routine liver biochemical tests, arterial ketone body ratio (AKBR), and plasma cytokine-interleukin (IL) 1alpha, 1beta, 2, and 6, and tumor necrosis factor alpha--levels were measured before and after the operation. The morbidity and hospital mortality rates were also compared among the patients with different ischemic durations and those without an intermittent Pringle maneuver. SETTING: Tertiary referral center. RESULTS: The cutoff point of accumulated ischemic time that induced substantial liver damage, as shown by the postoperative recovery rate of the AKBR, was found to be 120 minutes. Compared with the control group, the patients whose accumulated ischemic time was shorter than 120 minutes had less blood loss related to transection area (10 mL/cm2 vs 22 mL/cm2; P<.001), less blood transfused (0 L vs 0.6 L; P = .004), a shorter transection time related to transection area (2.0 min/cm2 vs 2.8 min/ cm2; P = .002), a significantly higher AKBR in the first 2 hours after liver transection, an equal recovery rate of the AKBR, and a comparable increase of the plasma level of IL-6 postoperatively. For the patients whose accumulated ischemic time was longer than 120 minutes, blood loss from the transection area was less than for the control group (14 mL/cm2 vs 22 mL/cm2; P<.05), but the transection time related to the transection area and the blood transfusion volume did not differ from those of the control group. Furthermore, they had a significantly lower recovery rate of the AKBR and higher plasma levels of IL-6 postoperatively than the control group.

Adult↗

Altered endothelial function in lambs with pulmonary hypertension and acute lung injury.

Acute lung injury produces pulmonary hypertension, altered vascular reactivity, and endothelial injury. To determine whether acute lung injury impairs the endothelium-dependent regulation of pulmonary vascular tone, 16 lambs were studied during U46619-induced pulmonary hypertension without acute lung injury, or air embolization-induced pulmonary hypertension with acute lung injury. The hemodynamic responses to endothelium-dependent (acetylcholine, ATP, ET-1, and 4 Ala ET-1 [an ETb receptor agonist]) and endothelium-independent (nitroprusside and isoproterenol) vasodilators were compared. During U46619-induced pulmonary hypertension, all vasodilators decreased pulmonary arterial pressure and vascular resistance (P < 0.05). During air embolization-induced pulmonary hypertension, the pulmonary vasodilating effects of acetylcholine, ATP, and 4 Ala ET-1 were attenuated (P < 0.05); the pulmonary vasodilating effects of nitroprusside and isoproterenol were unchanged; and the pulmonary vasodilating effects of ET-1 were reversed, producing pulmonary vasoconstriction (P < 0.05). During air embolization, the pulmonary vasoconstricting effects of ET-1 were blocked by BQ 123, an ETa receptor antagonist. The systemic effects of the vasoactive drugs were similar during both conditions. We conclude that pulmonary hypertension with acute lung injury induced by air embolization results in endothelial dysfunction; there is selective impairment of endothelium-dependent pulmonary vasodilation and an altered response to ET-1 from pulmonary vasodilation to vasoconstriction. This altered response to ET-1 is associated with decreased ETb receptor-mediated vasodilation and increased ETa receptor-mediated vasoconstriction. Endothelial injury and dysfunction account, in part, for the altered regulation of pulmonary vascular tone during pulmonary hypertension with acute lung injury.

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

Prospective evaluation of selective defunctioning stoma for low anterior resection with total mesorectal excision.

Low anterior resection with total mesorectal excision for rectal carcinoma is associated with a high anastomotic leakage rate, and the effectiveness of a defunctioning stoma in preventing anastomotic leakage remains controversial. In this study a policy of selective defunctioning stoma for stapled colorectal anastomosis after low anterior resection with total mesorectal excision in 148 consecutive patients was evaluated prospectively. A defunctioning stoma was performed in 61 patients (41%) considered at high risk of anastomotic leakage. Clinical leakage occurred in 2 patients (3.3%) with a stoma and 11 patients (12.6%) without a stoma (p = 0.047). Among those without a stoma, the leakage rate among male patients (20.9%) was significantly higher than that for female patients (4. 5%) (p = 0.022). Leakage subsided with conservative treatment in the two patients with a stoma, but seven patients without a stoma developed peritonitis requiring laparotomy. No deaths resulted from leakage, and there was one hospital death (0.6%) in the whole group. Median hospital stay was similar with and without a stoma (13.0 vs. 12.0 days) (p = 0.290). Closure of the stoma was associated with no mortality, a morbidity rate of 8.7%, and a median hospital stay of 6. 0 days. In conclusion, a defunctioning stoma is effective in preventing clinical anastomotic leakage after low anterior resection with total mesorectal excision. The relatively high incidence of leakage in the low risk group indicates the difficulty of predicting anastomotic leakage and hence the need for more liberal use of a defunctioning stoma especially in male patients.

Adult↗

Epidemiology of atherosclerotic peripheral arterial occlusive disease in Hong Kong.

The epidemiology of atherosclerotic peripheral arterial disease (PAD) has rarely been studied in Asia. A prospective vascular registry consisting of 510 Chinese patients with PAD from a teaching hospital in Hong Kong disclosed a male/female ratio of 1.6:1.0 with a mean age of 72 years. The predominant pattern was femoropopliteal occlusive disease (49%). Half of all patients had tissue loss on presentation, more so in women (67%) than men (38%). Demographic and biochemical risk factors examined showed many similarities with the West, included smoking (59%), hypertension (55%), diabetes mellitus (42%), hypercholesterolemia (55%), elevated low density lipoprotein (LDL) (60%), triglycerides (31%), hyperfibrinogenemia (62%), and hyperglycemia (49%). Chinese female patients with PAD were older and had a high prevalence of diabetes mellitus (54%). Smoking is less a problem in women (28%). They suffered predominantly from femoropopliteal and distal vessel disease, and two-thirds presented with tissue loss. Female patients also have significantly higher levels of fasting glucose, cholesterol, triglyceride, LDL, and very low density lipoprotein (VLDL). Male patients were mostly smokers (80%) with a higher proportion of aortoiliac disease. Critical ischemia in the form of tissue loss was associated with female sex (p < 0.001), age (p < 0.001), nonsmoking (p < 0.001), diabetes (p < 0.005), a low hemoglobin/hematocrit (p < 0.001), a high white blood cell count (p < 0.001), and high levels of fibrinogen (p < 0.01) and cholesterol (p < 0.05). An increasing incidence of PAD was noted in Hong Kong. Most of the patients present late with advanced ischemia. It is possible that this disease pattern represents only a fraction of the true incidence of PAD in the territory.

Adolescent↗

An exon map of the AZFc male infertility region of the human Y chromosome.

STS markers spanning the AZFc region of human Y Chromosome (Chr) were used to isolate a series of 14 P1 artificial chromosome (PAC) clones covering at least 560 kb of DNA. End clone analysis of these PAC clones was used to derive 10 new STS markers. Together with other markers mapped to the region, an STS content analysis was used to assemble these PAC clones into three distinct contigs. A minimum tiling path of ten PAC clones was subjected to exon trapping to identify potentially new genes mapping to the AZFs region. In all, 39 potential exons were isolated, including 2 exons from the DAZ gene, 3 exons from the BPY2 gene, 2 exons from the PRY gene, and 1 exon from a member of the RBM II gene family; all these genes have been shown previously to map to the AZFc region. One further exon was found that shows homology to the DFFRY gene, which maps to Yq11. 2, indicating that there may be a further copy of this gene or a pseudogene in the distal Yq euchromatin. The majority of the remaining potential exons appear to be novel, suggesting that additional genes lie in the AZFc region. Mapping of these exons by PCR analysis of somatic cell hybrids has shown that six of these exons are homologous to autosomal sequences, and five to sequences on the X Chr. RT-PCR analysis of primary cDNA from adult testis, brain, liver, and skeletal muscle mRNA has shown that 11 of the novel exons are expressed in one or a combination of these tissues, indicating that they form parts of genuine transcripts.

Brain↗

Helicobacter pylori status and endoscopy follow-up of patients having a history of perforated duodenal ulcer.

BACKGROUND: The aim of this study was to determine whether the recurrence of symptoms or ulcer disease in patients with a history of perforated duodenal ulcer is related to Helicobacter pylori infection. METHODS: One hundred sixty-three consecutive patients with history of perforated duodenal ulcer unrelated to nonsteroidal anti-inflammatory drugs underwent upper endoscopy. Any recurrent symptoms or complications were documented. Regardless of the endoscopic findings, three antral biopsy specimens were taken for histologic examination and a rapid urease test. RESULTS: There was a preponderance of men (male/female = 5.3:1). The mean age was 55.9 years. Sixty-seven (41.1%) patients gave a history of recurrent epigastric pain, seven of whom also had a history of bleeding ulcer. Upper endoscopy was performed at a mean of 74.5 +/- 7.1 months after operation. Positive endoscopic findings were noted in 68 (41.7%) patients; H. pylori was found in the biopsy specimens from 77 (47.2%) patients. Recurrent duodenal ulcer was found in 29 (17.8%) patients and was significantly related to male gender, recurrent epigastric pain, bleeding ulcer, longer interval from previous operation, and positive H. pylori status. Positive H. pylori status and male gender were independent factors associated with recurrent duodenal ulcer. CONCLUSIONS: Recurrent ulcer disease in patients with a history of perforated duodenal ulcer is related to H. pylori infection.

Adolescent↗

Is physical activity as effective in reducing risk of cardiovascular disease as estrogen replacement therapy in postmenopausal women?

Coronary heart disease (CHD) is known as a disease of postmenopausal women. While hormone replacement therapy is recommended increasingly to postmenopausal women for the prevention of CHD, the potential impact of non-pharmacologic interventions on cardiovascular disease reduction has been largely unexplored. The purpose of this article is to develop the understanding of the research literature on three risk factors by which estrogen and physical activity, a non-pharmacologic intervention, may confer cardiovascular protection in postmenopausal women. Three risk factors are lipoproteins, systolic pressure, and changes in the vascular endothelial functions. Effects of estrogen and physical activity on these biological factors are compared.

Cardiovascular Diseases↗

Contribution of basic sciences to academic success in nursing education.

The present study set out to examine the contribution of basic sciences to academic success in nursing education. A number of regression analysis models were used to analyze the relationships among predictor and criterion variables. Data analyses showed that basic sciences and grade point average of nursing courses in year 3 and 4 contributed significantly to student success in the program (p < 0.001). The cumulative grade point average was the only significant predictor of the licensure examination success. These results suggested that the content in science courses may have unique relevance to nursing and, therefore, may have a factor in their predictive value.

Achievement↗

Liver transplantation in infants.

PURPOSE: In view of the earlier reports that children below 1 year of age constitute a high-risk group for liver transplantation, the authors reviewed their experience in performing orthotopic liver transplantation in this age group. METHODS: The records of 9 children aged less than 1 year who underwent 6 living-related liver transplants and 3 reduced-size liver transplants between December 1993 and June 1997 were reviewed. RESULTS: Five reexplorations were required for 3 children who had 1 or more of the following early complications: bleeding from hepatic vein to inferior vena cava anastomosis (n = 1), right hepatic vein stump bleeding (n = 1), intraabdominal hematoma (n = 2), jejuno-jejunostomy leakage (n = 1), and colonic perforation (n = 1). Late complications include stricture at the biliary-enteric anastomosis requiring percutaneous balloon dilatation (n = 3) and hepatitis of undetermined etiology requiring retransplantation (n = 1). There was no hepatic artery thrombosis despite the small arteries available for anastomosis. Follow-up ranged from 19 to 61 months (mean, 40 months). Patient survival rate was 100%, and graft survival with good liver function was 89%. All living donors, 2 fathers and 4 mothers, are well. CONCLUSIONS: Liver transplantation in infants less than 1 year of age is technically demanding but feasible and still can be performed with a good outcome. Age alone (under 1 year) should not be considered as a contraindication for liver transplantation.

Age Factors↗

Analysis and pharmacokinetics of quetiapine and two metabolites in human plasma using reversed-phase HPLC with ultraviolet and electrochemical detection.

A sensitive and specific HPLC assay for the measurement of the antipsychotic compound quetiapine in human plasma has been developed and validated. The assay employs a three-step liquid liquid extraction of quetiapine and its 7-hydroxylated and 7-hydroxylated, N-dealkylated metabolites from human plasma, and utilizes ultraviolet (UV) detection of quetiapine and electrochemical detection of the metabolites. The method provides a linear response from a quantitation limit of 2.50 to 500 ng ml(-1) for each analyte using 0.4 ml plasma. The assay is applicable from 500 to 5000 ng ml(-1) by sample dilution with de-ionized water. The inter-assay precision of quetiapine in plasma calibration standards across 4 validation days averaged 11.9% relative standard deviation (RSD) over the range 2.50 to 500 ng ml(-1), with intra-assay precision averaging 16.0% RSD and mean accuracy of 98.6% of theory. Similarly, the inter-assay precision of the 7-hydroxylated metabolite in plasma calibration standards across 4 validation days averaged 13.7% RSD over the range 2.50 to 500 ng ml(-1), with intra-assay precision averaging 17.6% RSD and mean accuracy of 109% of theory. The 7-hydroxylated, N-dealkylated metabolite demonstrated inter-assay precision of 16.2% RSD, intra-assay precision of 19.9% RSD, and mean accuracy of 104% of theory over the range 2.50 to 500 ng ml(-1). The present assay method was used to support a study comparing the pharmacokinetic profile of quetiapine with the time course of dopamine D2 and serotonin 5-HT2 receptor occupancy in the brain using positron emission tomography (PET). We describe in this paper the bioanalytical method and the plasma concentrations of quetiapine and its metabolites resulting from this study.

Adult↗

Screening for asymptomatic carotid stenosis in patients with peripheral vascular disease: a prospective study and risk factor analysis.

Screening for asymptomatic carotid artery stenosis using color flow duplex scan was performed on 186 Chinese patients with peripheral vascular disease. They consist of 121 male and 65 females, with a mean age of 70.6 years. A carotid bruit was present in 43 (23.1%) of the patients. Internal carotid artery stenosis of 70% or greater was detected in 46 patients (24.7%) including six total occlusions. Another 79 patients (42.5%) had internal carotid artery stenosis in the 30-69% range. Significant internal carotid artery stenosis was associated with age, male sex, the quantity and duration of smoking and a carotid bruit, and inversely with cholesterol, triglyceride and VLDL. Age, the number of cigarettes consumed per day, and carotid bruit were independent significant predictors of > or =70% internal carotid artery stenosis on logistic regression analysis. The degree of internal carotid artery stenosis is more severe in patients with a carotid bruit, and correlated positively with age (P<0.01), the number of cigarettes smoked (P = 0.04), and the duration of smoking (P = 0.03). Multiple linear regression analysis showed that only the age of the patient bears a significant relationship with the degree of internal carotid artery stenosis (P<0.01). There was no relationship between the degree of lower limb ischemia with carotid stenosis. The prevalence of > or =70% internal carotid artery stenosis in a high risk population with peripheral vascular disease was 24.7%. Routine duplex screening is worthwhile in this group of patients, particularly in male, elderly smokers.

Aged↗

Non-small-cell lung cancer: practice patterns of extrathoracic imaging.

RATIONALE AND OBJECTIVES: The purpose of this study was to identify practice patterns of extrathoracic imaging in patients newly diagnosed with non-small-cell lung, cancer. MATERIALS AND METHODS: The authors retrospectively reviewed the charts of 125 patients (71 men, 54 women; mean age, 67 years) from five hospitals (25 patients each) with newly diagnosed non-small-cell lung cancer. Charts were reviewed for cancer cell type, evidence of metastatic disease, and performance and results of extrathoracic imaging, including computed tomography (CT) and magnetic resonance (MR) imaging of the brain, bone scanning, and abdominal CT. RESULTS: Of 125 patients, 77 (62%) underwent extrathoracic imaging. These patients included 64 (64%) of 100 patients with clinical symptoms or laboratory signs of metastatic disease and 13 (52%) of 25 patients with no such indications. Extrathoracic imaging did not differ according to cancer cell type: It was performed for 30 (60%) of 50 patients with squamous cell carcinoma, 26 (60%) of 43 patients with adenocarcinoma, and 16 (73%) of 22 patients with non-small-cell lung cancer that was not further characterized. Brain CT or MR imaging bone scanning, or abdominal CT were performed in only 48%, 39%, and 30% of patients, respectively. Brain CT or MR images or bone scans revealed metastatic disease in seven of 20 and nine of 22 patients with clinical symptoms or laboratory signs of disease, respectively. These examinations revealed disease in four of 40 and two of 27 patients without such symptoms or signs, respectively (P < .05). No significant differences emerged among the practice patterns at the five participating hospitals. CONCLUSION: No consensus was found on performance of extrathoracic imaging in patients with newly diagnosed non-small-cell lung cancer.

Abdomen↗

Major hepatectomy for hepatocellular carcinoma in patients with an unsatisfactory indocyanine green clearance test.

BACKGROUND: Liver failure is the commonest cause of postoperative death in patients with hepatocellular carcinoma (HCC). With the improvement in operative technique and perioperative care, the limit of hepatic functional reserve may be lowered. The aim of this study was to evaluate the postoperative morbidity, mortality and survival rates in patients with an indocyanine green (ICG) retention value higher than 14 per cent, after major hepatectomy for HCC. METHODS: From January 1994 to December 1997, 117 patients underwent major hepatectomy for HCC; 92 patients had preoperative ICG retention at 15 min lower than 14 per cent (median 8.3 (range 1.6-13.8) per cent), while 25 patients had ICG retention greater than 14 per cent (17.4 (range 14.3-35.3) per cent). Data were collected prospectively and analysed retrospectively. RESULTS: The two groups of patients were similar in terms of age, sex ratio, preoperative platelet count, liver biochemistry, Child-Pugh status and operative procedures performed, but the prothrombin time was significantly longer in the high ICG group. The operative blood loss (1.5 litres), the amount of blood transfused and the number of patients requiring blood transfusion were similar. The postoperative complication rate (41 versus 40 per cent), duration of hospital stay (12 versus 13 days), hospital mortality rate (1 versus 4 per cent) and median survival time (47 versus 45 months) were not significantly different. CONCLUSION: With meticulous surgical technique to decrease intraoperative blood loss and good perioperative care, selected patients with limited hepatic functional reserve can achieve a good immediate postoperative result and a survival rate similar to that of patients with good hepatic functional reserve.

Adolescent↗

Vascular surgical society of great britain and ireland: autologous transfusion reduces blood transfusion requirements in aortic surgery

BACKGROUND: Elective aortic surgery is associated with a blood loss that warrants a routine blood crossmatch of 4-6 units. Autologous transfusion strategies to reduce blood requirements were evaluated in a pilot study involving six hospitals in the North West. METHODS: Eighty patients undergoing elective aortic surgery were randomized to either autologous (a combination of acute normovolaemic haemodilution and intraoperative cell salvage) or homologous transfusion. The transfusion trigger, in the absence of pressing clinical need, was 8 g dl-1 haemoglobin for both groups. RESULTS: Randomization achieved two groups well matched for age, aneurysm or occlusive surgery, aspirin intake, estimated blood volume, preoperative haemoglobin and aneurysm size. In the 'best' hospitals (n = 49) mean(s.d.) blood loss (630(49) ml) was significantly lower (P < 0.01) than that in the 'worst' hospitals (1077(110) ml, n = 31) and fewer patients required transfusion (nine of 42 versus 15 of 30; P < 0.05). No significant differences were found between homologous and autologous groups for all variables measured in the 'best' hospitals. In the 'worst' hospitals blood requirements were significantly higher (P < 0.05) for the homologous group (800(112) ml) compared with the autologous group (489(65) ml), although blood loss was similar (1239(195) versus 915(92) ml respectively). CONCLUSION: Autologous transfusion techniques significantly reduced homologous blood requirements in aortic surgery where blood loss exceeded 800 ml.

Journal Article↗