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Biomedical subjects

J Wong

Publications and source records attributed to J Wong.

At least 343 records · Page 19Linked to original sources
PubMed1997

Some psychological aspects of oocyte donation from known donors on altruistic basis.

OBJECTIVE: To survey a sample of couples along with their chosen oocyte donors regarding psychological variables. DESIGN: Patients in an infertility clinic were interviewed by a counselor using a semistructured interview format designed to gather systematic data. SETTING: Infertility clinic. PATIENT(S): Ten recipient couples along with their donors were seen. RESULT(S): Oocyte recipients ranged in age from 30 to 49 years with a mean age of 40 years. Oocyte donors ranged in age from 21-34 years with a mean age of 29 years. Eighty percent of donors were married or involved in a serious relationship; 90% of donors had at least one child. The major reason for acting as a donor was altruism. Anonymity was a primary concern for recipients and donors: 80% of the sample had not confided in anyone at the present time. 70% did not intend to disclose any information at any time; 80% did not plan to inform the child, while 20% were undecided at the present time; and 90% indicated good to excellent support systems. CONCLUSION(S): The present study provides significant information regarding Canadian couples undergoing the oocyte donation program with known donors.

Adult↗
PubMed1997

A prospective comparison of locally made rapid urease test and histology for the diagnosis of Helicobacter pylori infection.

BACKGROUND: A number of noncommercial preparations of urease test have been described. The present prospective study evaluated the accuracy of one such preparation for the diagnosis of Helicobacter pylori infection. METHODS: From February 1996 to November 1996, all patients undergoing elective upper endoscopy in a single endoscopy facility were included. Three antral biopsy specimens were taken. Two specimens were subjected to histologic examination, and one specimen was placed into a "locally made rapid urease test" (LRUT). Results of histologic examinations were taken as standards for comparison. The final result of LRUT was obtained on scrutiny of color changes at 4 hours after the start of the test. RESULTS: Two thousand three hundred sixteen patients (male/female = 1.5:1) with a mean age of 56.7 +/- 0.4 years were included. Five hundred sixty-two patients (24.3%) had a history of eradication treatment for H. pylori. Nine hundred fifty-three patients (41.1%) were found to be positive for H. pylori on histologic examination. In patients in whom a history of eradication therapy was absent, the sensitivity, specificity, and positive and negative predictive values of the LRUT were 92.8%, 97.6%, 97.5%, and 93.0%, respectively. In patients with a history of eradication treatment, the corresponding figures were 76.1%, 99.6%, 96.2%, and 96.9%. CONCLUSIONS: The locally made rapid urease test provides a simple, safe, rapid, inexpensive, and accurate test for the diagnosis of H. pylori infection.

Biopsy↗
PubMed1997

Liver transplantation in children: the experience of Queen Mary Hospital, Hong Kong.

Seven living-related liver transplants (LRLT) and two reduced-size liver transplants (RSLT) were performed on eight children who suffered from end-stage liver disease, having previously undergone one to three abdominal operations. Their ages at initial transplantation ranged from 8 months to 11 years (mean 35 months, median 12 months). Excluding the two older children aged 7 and 11 years, respectively, the rest of the children weighed 6 to 9.5 kg (mean 7.3 kg) at the time of the initial transplantation. Seven left lateral segments (S2 + 3) and two left lobes (S2 + 3 + 4) were used; of these the smallest graft had a graft-to-recipient body weight ratio of 0.9%. The volunteer living donors were four mothers, two fathers and one sister who were selected after medical and psychiatric evaluations, and their suitability was confirmed by hematological, biochemical, and radiological criteria. During a follow-up period of 3 to 30 months, all eight children are alive and well with normal liver function, one of them having undergone a retransplant LRLT because of hepatitis of undetermined etiology following a RSLT 1.5 years earlier. All seven donors had an uneventful postoperative course and were discharged on day 4 to 7 postoperatively. They have all resumed normal day-to-day activities. There were no complications in the donor group. A variety of complications occurred in the recipients, all of which were overcome. Operating microscope was used to perform all the arterial anastomoses using microvascular techniques. This method has proven to be a major factor in preventing arterial thrombosis even with the smallest of arterial anastomosis where a 1.5-mm diameter recipient artery was anastomosed to a 2.5-mm diameter donor hepatic artery.

Activities of Daily Living↗
PubMed1997

Early results with partial left ventriculectomy.

OBJECTIVE: We sought to determine the role of partial left ventriculectomy in patients with dilated cardiomyopathy. METHODS: Since May 1996 we have performed partial left ventriculectomy in 53 patients, primarily (94%) in heart transplant candidates. The mean age of the patients was 53 years (range 17 to 72 years); 60% were in class IV and 40% in class III. Preoperatively, 51 patients were thought to have idiopathic dilated cardiomyopathy, one familial cardiomyopathy, and one valvular cardiomyopathy. As our experience accrued we increased the extent of left ventriculectomy and more complex mitral valve repairs. For two patients mitral valve replacement was performed. For 51 patients the anterior and posterior mitral valve leaflets were approximated (Alfieri repair); 47 patients also had ring posterior annuloplasty. In 27 patients (51%) one or both papillary muscles were divided, additional left ventricular wall was resected, and the papillary muscle heads were reimplanted. RESULTS: Echocardiography showed a significant decrease in left ventricular dimensions after resection (8.3 cm to 5.8 cm), reduction in mitral regurgitation (2.8+ to 0), and increase in forward ejection fraction (15.7% to 32.7%). Cardiac index did not increase significantly (2.2 to 2.4 L/min per square meter). Eight patients (15%) required a perioperative left ventricular assist device; one died and was the only perioperative mortality (1.9%). At 11 months, actuarial survival was 87% and freedom from relisting for transplantation was 72%. CONCLUSIONS: Improved selection criteria are necessary to avoid early failures, and much more follow-up and analyses of data are mandatory. However, the operation may become a biologic bridge, or even alternative, to transplantation.

Cardiomyopathy, Dilated↗
PubMed1997

Preoperative chemotherapy versus surgical therapy alone for squamous cell carcinoma of the esophagus: a prospective randomized trial.

OBJECTIVE: This study investigated the role of preoperative chemotherapy in squamous cell cancer of the esophagus. METHODS: A prospective randomized trial was undertaken in 147 patients: 74 received preoperative chemotherapy comprising cisplatin and 5-fluorouracil and 73 had surgical therapy alone. End points were cancer and therapy-related deaths. RESULTS: Sixty-six patients (89%) in the chemotherapy group underwent resection compared with 69 (95%) in the control group (p = not significant). Of the 60 patients who had resection after completing the chemotherapy program, 35 (58%) had a significant response, of whom four (6.7%) had a complete pathologic response. Postoperative mortality rates were 8.3% and 8.7% in the chemotherapy and control groups, respectively (p = not significant). Significant downstaging was evident with chemotherapy; curative resections were possible in 67% of these patients compared with 35% in the control group (p = 0.0003). T3 and T4 tumors were found in 67% and 91% of the chemotherapy and control groups, respectively (p = 0.0002). The respective figures for N1 disease were 70% and 88% (p = 0.009). An intent-to-treat analysis of survival showed no significant difference between the two groups. Median survivals were 16.8 and 13 months, respectively (p = 0.17). Of those who completed the chemotherapy and resection, responders fared better than control patients. Median survivals were 42.2 months and 13.8 months, respectively (p = 0.003). Median survival (8.3 months) was worse for nonresponders than for control patients (p = 0.03). The recurrence pattern suggested a significant reduction in locoregional disease with chemotherapy. CONCLUSIONS: Preoperative chemotherapy was safe and resulted in significant downstaging and an increased likelihood of curative resection. Survival was not better than that in the surgery-alone group, but responders did fare better than nonresponders.

Aged↗
PubMed1997

Thoracoscopic esophagectomy for esophageal cancer.

BACKGROUND: Minimal access surgery is an alternative to open surgery in esophageal surgery. Its role in cancer resection is controversial. METHODS: Thoracoscopic esophageal resection was attempted in 22 patients who had increased operative risk. Postoperative outcomes of these patients were compared with the outcomes of 63 patients who underwent open thoracotomy resection during the same period. RESULTS: Thoracoscopy was completed in 18 patients. Conversion to thoracotomy was necessary because of locally advanced tumor in three patients, and a bypass procedure was performed in another patient because of poor ventilation during thoracoscopy and the finding of metastatic disease. The median thoracoscopy time was 110 minutes (range, 55 to 165 minutes). The total operating times were 240 minutes (range, 165 to 360 minutes) and 250 minutes (range, 190 to 420 minutes) for thoracoscopy and thoracotomy, respectively, p = 0.5. Blood loss was significantly less than that of open resection; medians were 450 ml (range, 200 to 800 ml) and 700 ml (range, 300 to 2500 ml) for thoracoscopy and thoracotomy, respectively, p < 0.01. The median number of lymph nodes removed at thoracoscopy was 7 (range, 2 to 13) compared with 13 (range, 5 to 34) in the thoracotomy group. Bronchopneumonia affected 17% of both groups of patients. Only one patient who was converted to open thoracotomy died. Port site recurrence developed in one patient. Overall survival rates were not significantly different. CONCLUSIONS: Thoracoscopic esophageal resection was a feasible option. Clear advantages over open thoracotomy were not demonstrated, although patients who were selected for thoracoscopy had worse performance status. This technique deserves further investigation in dedicated centers.

Adult↗
PubMed1997

Indocyanine green hyperfluorescence associated with serous retinal pigment epithelial detachment in age-related macular degeneration.

PURPOSE: Indocyanine green (ICG) angiography may improve visualization of choroidal neovascularization (CNV) associated with serous retinal pigment epithelial detachment (RPED) in age-related macular degeneration (AMD). The features of ICG hyperfluorescence associated with serous RPED and therapeutic effect of ICG-directed laser photocoagulation in eyes with serous RPED is evaluated. DESIGN: Retrospective review of all simultaneous fluorescein/ICG angiograms (n = 918) performed over an 18-month period to identify 44 eyes in 39 patients with serous RPED secondary to AMD on fluorescein angiography. PARTICIPANTS: Thirty-nine patients with AMD, aged 53 to 89 years, participated. INTERVENTION: Eyes were nonrandomly treated with ICG-directed laser photocoagulation or observation. MAIN OUTCOME MEASURES: Characteristics of ICG hyperfluorescence associated with a serous RPED are reviewed. Final visual acuity and anatomic appearance of the serous RPED are given. RESULTS: Twenty-three (52%) of the 44 eyes had an isolated serous RPED without obvious CNV, and 21 (48%) of the 44 eyes had a serous RPED associated with occult CNV on fluorescein angiography. Indocyanine green angiography demonstrated underlying CNV in 19 eyes (83%) with an isolated serous RPED and in all 21 eyes (100%) with serous RPED and occult CNV. The pattern of ICG hyperfluorescence revealed focal CNV in 15 eyes and plaque CNV in 4 eyes with an isolated serous RPED. In eyes with serous RPED and occult CNV, focal CNV and plaque CNV were noted with ICG in 8 and 13 eyes, respectively. No follow-up was available for two eyes. Twenty eyes were treated with ICG-directed laser photocoagulation. In these eyes, the visual acuity remained stable in 6 eyes (30%) and decreased in 14 eyes (70%). Twenty-two eyes were observed, and the visual acuity remained stable in 8 (36%), improved in 2 (9%), and decreased in 12 eyes (55%). CONCLUSIONS: Although ICG angiography may enhance visualization of CNV associated with serous RPED in AMD, ICG-directed laser treatment did not appear to improve visual acuity when compared with observed eyes in this series.

Aged↗
PubMed1997

The induction of ICAM-1 in human cerebromicrovascular endothelial cells (HCEC) by ischemia-like conditions promotes enhanced neutrophil/HCEC adhesion.

Ischemic brain injury is exacerbated by leukocyte infiltration and formation of vasogenic edema. In this study we demonstrate that intercellular adhesion molecule-1 (ICAM-1) is dramatically (3 to 15-fold) up-regulated in human cerebromicrovascular endothelial cells (HCEC) by a 16 h exposure to the cytokine, IL-1 beta (50-200 u/ml), the phorbol ester, TPA (1-100 nM), or by simulated in vitro ischemia/reperfusion. These treatments also significantly increased the adhesion of allogeneic neutrophils to HCEC monolayers. Both IL-1 beta- and TPA-induced expression of ICAM-1 and increased neutrophil adhesion to HCEC were inhibited by the transcriptional inhibitor, actinomycin D (AcD; 1-10 micrograms/ml), and by an anti-ICAM-1 antibody (ICAM-1 Ab). By contrast, ischemia-induced neutrophil adhesion was only slightly affected by AcD and ICAM-1 Ab alone, but it was abolished by the combination of anti-ICAM-1 and anti-CD18 antibodies. The increase in surface expression of ICAM-1 and neutrophil adhesion by IL-1 beta, TPA and ischemia were significantly reduced by the cyclo-oxygenase (COX) inhibitors, indomethacin (100-300 microM) and dexamethasone (10-50 microM). These results indicate that ICAM-1 expression in HCEC can lead to enhanced neutrophil adhesion and that COX activation in HCEC likely plays a role in the processes by which leukocyte adhesion and recruitment take place in the brain during inflammation and ischemia in vivo.

Blood-Brain Barrier↗
PubMed1997

Effects of portacaval shunting on hyperdynamic circulation in bile duct-ligated cirrhotic rats.

BACKGROUND/AIMS: Liver cirrhosis and portal hypertension are associated with hyperdynamic circulation. Portacaval shunts are widely used to prevent recurrent hemorrhage, but the hemodynamic effects caused by these procedures have not been well characterized in cirrhosis. We therefore compared the hemodynamic effects of both end-to-side and side-to-side portacaval shunts in normal and cirrhotic rats. METHODS: Sprague-Dawley rats were divided into six groups according to the operations they underwent. End-to-side or side-to-side portacaval shunts were performed in both rats with cirrhosis induced by bile duct ligation and sham-operated rats. Systemic and regional blood flows were measured by the radioactive microsphere method. RESULTS: Portal pressures in the shunted rats decreased significantly. Cardiac index in cirrhotic rats (557 +/- 27 ml.min-1.kg-1) was significantly higher than controls (455 +/- 21 ml.min-1.kg-1), but the two types of shunts did not further increase cardiac index in either the cirrhotic or the sham-operated rats. After shunting, hepatic arterial flows approximately doubled. Portal tributary blood flows in the end-to-side shunted sham (108 +/- 13 ml.min-1.kg-1) and cirrhotic (139 +/- 19 ml.min-1.kg-1 groups were significantly higher than their respective controls (62 +/- 8 and 76 +/- 5 ml.min-1.kg-1). Portosystemic shunting indices were > 99% in both the end-to-side and side-to-side shunted groups in cirrhotic and sham-operated rats. CONCLUSIONS: The hyperdynamic circulation in cirrhotic rats was not augmented by portacaval shunting operations (either end-to-side or side-to-side), despite essentially total portosystemic blood diversion. Compensatory increase in the hepatic arterial blood flow to the liver remained intact even in cirrhotic rats. A selective redistribution of cardiac output to the mesenteric vascular bed was observed after the shunting procedure. However, there were no significant differences in hemodynamics between the end-to-side and side-to-side shunted groups.

Animals↗
PubMed1997

Livedo reticularis, rhabdomyolysis, massive intestinal infarction, and death after carbon dioxide arteriography.

In patients with renal insufficiency or hypersensitivity to iodinated contrast material, carbon dioxide gas (CO2) is generally considered a safe alternative contrast media for digital subtraction angiography. However, we herein report a previously undescribed fatal complication of CO2 angiography in a patient with acute renal dysfunction and congestive heart failure. The possible pathogenetic mechanisms of this complication are discussed.

Aged↗
PubMed1997

Pre-operative chemotherapy for squamous cell carcinoma of the oesophagus: do histological assessment and p53 overexpression predict chemo-responsiveness?

Pre-operative chemotherapy is increasingly used in the treatment of oesophageal carcinoma. However, no features have been identified which can reliably predict a positive response to chemotherapy. The aim of this study was to examine whether histological features and p53 overexpression could predict such response. Prechemotherapy endoscopic biopsies from 55 patients, who subsequently completed two courses of chemotherapy followed by surgical resection, were studied. Patients were classified into responders and non-responders according to clinical and pathological findings. Pathological features of the endoscopic biopsies examined included adequacy of the tumour tissue, histological grade, degree of keratinisation, histologic patterns, mitotic rates and nuclear pleomorphism. Biopsy specimens were also tested for p53 overexpression using p53 protein specific mouse monoclonal antibody DO-7 on paraffin sections. Histologic features and p53 expression were correlated to chemoresponsiveness. 76% (42 of 55) of patients had sufficient biopsy tissue for assessment. Response to chemotherapy was evident in 64% (n = 27) of patients. None of the non-responders had tumours with high-grade nuclear pleomorphism compared with 37% (10 of 27) of responders (P = 0.01). All patients with high-grade nuclear pleomorphism responded to chemotherapy. No significant differences were found between the responders and non-responders with respect to tumour differentiation (P = 0.7), degree of keratinisation (P = 0.3) and mitotic rates (P = 0.8). Overall, p53 overexpression was noted in 67% (28 of 42) of patients. This was more prevalent in non-responders (12/15) compared to responders (16/27), but this was not statistically significant (P = 0.08). The degree of p53 overexpression had no significant relationship with responsiveness to chemotherapy. High-grade nuclear pleomorphism, identified on pretreatment biopsy specimens, correlated with response to chemotherapy, whereas p53 overexpression did not correlate with response. Improved tissue sampling and further investigations should be done so that the assessment of prechemotherapeutic endoscopic biopsies can have significant impact on clinical decision making.

Aged↗
PubMed1997

Antitumor 8-chlorobenzocycloheptapyridines: a new class of selective, nonpeptidic, nonsulfhydryl inhibitors of ras farnesylation.

Ras farnesylation by farnesyl protein transferase (FPT) is an intracellular event that facilitates the membrane association of the ras protein and is involved in the signal transduction process. FPT inhibition could be a novel, noncytotoxic method of treating ras dependent tumor growth. We report here three structural classes of 8-chlorobenzocycloheptapyridines as novel, nonpeptidic, nonsulfhydryl FPT inhibitors having antitumor activity in mice when dosed orally. We discuss structural and conformational aspects of these compounds in relation to biological activities as well as a comparison to the conformation of a bound tetrapeptide FPT inhibitor.

Animals↗
PubMed1997

Lipoprotein (a) and its relationship to risk factors and severity of atherosclerotic peripheral vascular disease.

OBJECTIVES: To determine the significance of Lipoprotein (a) (Lp(a)) as a risk factor for atherosclerotic lower limb peripheral vascular disease (PVD), and its relationship to other demographic and biochemical variables and disease pattern and severity. DESIGN: Prospective case-control study. MATERIAL AND METHODS: Demographic and biochemical risk factors, lipoprotein fractions and Lp(a) were measured in 200 patients with PVD and 200 age- and sex-matched control subjects. Lp(a) levels were correlated with traditional risk factors and clinical and vascular laboratory disease parameters. RESULTS: Patients with PVD have a higher incidence of smoking, hypertension, and diabetes mellitus; and had significantly higher levels of serum cholesterol, triglycerides, LDL, VLDL, apolipoprotein B, fasting glucose, fibrinogen, plasminogen, haematocrit, white cell and platelet counts; but lower levels of HDL and apolipoprotein A1. Fasting Lp (a) concentration is an independent risk factor for PVD and is significantly higher in the patients (median = 26.1 mg/dl [4.8-195], mean = 36.5 +/- 32.6 mg/dl) than in controls (median = 18.2 mg/dl [5.4-216], mean = 27.2 +/- 28.1 mg/dl; p < 0.0001). In patients with PVD, Lp(a) correlated positively with plasma LDL, cholesterol, fibrinogen, renal disease, and apolipoprotein B. Fasting levels of > 24 mg/dl incurred a two-fold increase in risk of PVD. Patients with a higher Lp(a) have a significantly higher incidence of resting pain and ulcerations, and regression analysis confirmed smoking and Lp(a) level to be associated with the SVS category of disease severity. CONCLUSIONS: Lipoprotein (a) is a significant independent risk factor for PVD. Lp(a) levels correlated with LDL, cholesterol, fibrinogen, apolipoprotein B and disease severity. An elevated Lp(a) level may be associated with more severe forms of PVD.

Aged↗
PubMed1997

Cells in space

How does one treat in a seriously injured astronaut in outer space or even another planet? To answer such a question, the US National Aeronautical Space Administration (NASA) has embarked on a program of growing tissues--and possibly whole organs--in space. NASA has developed a unique rotating bioreactor that allow cells to be grown in a microgravity environment that eliminates almost all shear forces placed upon a cell culture system while entering space. Back on earth, this novel bioreactor has led to exciting discoveries and applications by scientists trying to get cells to differentiate and form their natural three-dimensional tissue matrices--the holy grail of tissue engineers. NASA's bioreactor has allowed various labs to culture cells and even viruses previously impossible to grow using traditional methods. These successes are attributed to the bioreactor's ability to provide an unique environment that closely resembles tissue differentiation during embryogenesis, and thus allowing cellular expression of surface epitopes similar to that of intact tissues. It also appears that cells grown in a microgravity, low-shear environment allows for greater chemical signaling, probably as a result of more surface contact between cells. Realizing the bioreactor's commercial potential, Santa Monica, California-based VivoRx licensed exclusive rights from NASA for both therapeutic and diagnostic commercial applications. VivoRx has, in the past, successfully transplanted encapsulated islet cells from cadavers and porcine pancreas into insulin-dependent diabetics, perhaps a major breakthrough in the treatment of diabetes. However, pancreas from cadavers are in very short supply. The bioreactor may be the answer; VivoRx hopes the bioreactor will allow them to propagate enough human islet cells to use their cell-based approach to treat a large diabetic population. The company has already successfully grown islet cells generated from the bioreactors, and is beginning FDA-approved Phase I/II clinical trials.

Bioreactors↗
PubMed1997

Activators and repressors: making use of chromatin to regulate transcription.

Metazoans and yeast use enzymes that modulate histone acetylation and nucleosomal integrity in order to regulate transcription. Repressor complexes deacetylate histones and stabilize nucleosomes. Activator complexes acetylate histones and disrupt nucleosomes. Variation in chromatin structure makes a major contribution to gene regulation. Here we discuss the enzymatic complexes and molecular machines that make use of chromatin to control transcription.

Animals↗
PubMed1997

Four additional cases of Burkholderia gladioli infection with microbiological correlates and review.

Burkholderia gladioli has only recently been reported to be a human pathogen. Four cases of B. gladioli infection (including bacteremia, pneumonia, and cervical adenitis) in two adults and two young children are reported. Three of these four patients were severely immunocompromised. Commercial systems were frequently unable to identify this bacterium correctly. Antimicrobial susceptibility patterns indicated that B. gladioli strains were susceptible to the quinolones, aminoglycosides, and imipenem. In vitro laboratory investigations demonstrated that B. gladioli strains were susceptible to complement-mediated lysis of pooled human serum, thus implying that healthy individuals should be immune to infection. These four cases together with three previously reported cases suggest that B. gladioli primarily causes disease in severely immunocompromised individuals. The lack of mortality associated with infection, coupled with susceptibility to serum and lack of recognizable virulence-associated factors, suggests that this species has a low pathogenic potential.

Adult↗