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Biomedical subjects

C M Wong

Publications and source records attributed to C M Wong.

At least 19 recordsLinked to original sources
PubMed1995

Clinical application of a new Palmaz-Schatz coronary stent delivery system with a short (8 mm) nonarticulated stent.

The standard Palmaz-Schatz coronary stent delivery system (SDS), with a 15 mm articulated stent and a 5F protective sheath, is relatively rigid and high in profile. Its use is contraindicated in vessels where there is severe tortuosity proximal to or in the lesion itself. Recently a new SDS, with a short (8 mm) nonarticulated stent, has become available. We present three patients with complex coronary anatomy solved with this new SDS. The first patient had a distal stenosis in an extremely tortuous and diffusely diseased right coronary artery (RCA). The second patient had a severe proximal RCA stenosis occurring at a bend of more than 90 degrees. The third patient had a very long stenosis of the left anterior descending coronary artery involving the ostium, requiring multiple tandem stenting. The availability of this short stent will greatly expand the clinical application of intracoronary stenting to patients with complex coronary anatomy.

Aged↗
PubMed1995

Stress and vulnerability in medical students.

One hundred and forty Hong Kong Chinese students were surveyed early in the second year of their medical education (year 2), and compared with 138 students surveyed prior to beginning their first year of medical school and with 74 non-medical university students in their second year. In year 2 students, distress as reflected in their scores on anxiety and depression self-report scales was high, and these students reported greater utilization of health professional services as compared with the other two groups. In year 2 students, concerns related to the medical school environment and curriculum, and whether one has the endurance and ability to be successful were significant correlates with depression and anxiety. Loss of opportunity to maintain social and recreational sources of gratification correlated with anxiety. There was no difference between the sexes with regard to the development of anxiety and depression symptoms. Academically less successful students reported somewhat higher levels of depressive ideation and symptomatology. Trait anxiety correlated with the development of distress, while optimism protected against the development of distress. Active coping styles and positive reinterpretation as a coping strategy correlated negatively with distress, while wishful thinking correlated positively with distress. These findings emphasize the need for greater attention to the psychological well-being of doctors-in-training, in Hong Kong as in the Western world. These findings should be further explored in longitudinal studies, and may be helpful in designing intervention and support programmes for vulnerable students.

Adult↗
PubMed1995

Body dysmorphic disorder, pathological gambling, and sexual compulsions.

This article focuses on body dysmorphic disorder (BDD), pathological gambling, and sexual compulsions within the realm of obsessive-compulsive spectrum disorders. These three disorders affect sizable numbers of the population, have an early age at onset and chronic courses, and seem to have a preferential response to serotonin reuptake inhibitors (SRIs). They also have a high comorbidity with obsessive-compulsive disorder, depression, and other impulse control disorders. BDD patients lie more toward the compulsive/risk-aversive end of the dimensional model of obsessive-compulsive spectrum disorder and often have poor insight. Pathological gambling patients lie more toward the impulsivity/novelty-seeking end of the OCD spectrum and often have features of inattention. Sexual obsessions and/or compulsions encompass a heterogeneous group of disorders, as exhibited by differential response to SRIs within this group. These three disorders fall within a new and evolving field that requires further investigation and reconceptualization. This concept may have far-reaching consequences and yield more significant treatment outcomes.

Adolescent↗
PubMed1994

Intracoronary stenting in acute myocardial infarction.

Stent implantation into an infarct-related artery during acute myocardial infarction is generally contraindicated because of the risk of stent thrombosis. We report on 3 patients who had successful stenting for an acute occlusive dissection that developed during direct infarct coronary angioplasty and was refractory to conventional prolonged balloon dilatation, with good long-term clinical and angiographic results. The prerequisites for success include proper premedication, presence of only a minimal amount of thrombus in the infarct-related artery, liberal use of intracoronary thrombolytic therapy, as perfect an angiographic result as possible, as well as careful and aggressive post-stenting anticoagulation.

Angioplasty, Balloon, Coronary↗
PubMed1994

Cloning and sequencing show that 4-hydroxybenzoate hydroxylase (PobA) is required for uptake of 4-hydroxybenzoate in Rhizobium leguminosarum.

Mutants of Rhizobium leguminosarum bv. viciae MNF300 and R. leguminosarum bv. trifolii WU95 unable to accumulate 4-hydroxybenzoate lack 4-hydroxybenzoate hydroxylase. The capacity of these mutants to take up and grow on 4-hydroxybenzoate was restored by a 2.0 kb EcoRI-PstI DNA fragment. This contained only one ORF which had over 60% DNA sequence similarity with the structural gene for 4-hydroxybenzoate hydroxylase (pobA) from Pseudomonas spp. and Acinetobacter. Reported effects of metabolic inhibitors and substrate analogues on the apparent uptake of 4-hydroxybenzoate have now been shown to be due to their direct effect on 4-hydroxybenzoate hydroxylase. We propose that uptake of 4-hydroxybenzoate is via a metabolic 'drag' mechanism dependent on the activity of the pobA gene product.

4-Hydroxybenzoate-3-Monooxygenase↗
PubMed1994

Bronchial responsiveness in children exposed to atmospheric pollution in Hong Kong.

Bronchial responsiveness was studied by histamine challenge in 423 school children with mean (SEM) age of 10.85 (0.05) years living in two districts of Hong Kong with contrasting levels of air pollution. Differences between districts of residence were observed, with a higher prevalence of bronchial hyperreactivity (BHR) in children living in the more polluted district (chi 2 = 7.74, df = 3, p = 0.052). Bronchial hyperreactivity was defined as a 20 percent or greater drop in FEV1. The district effect remained after exclusion of children with a history of wheeze and those diagnosed asthmatic for prevalence of BHR (chi 2 = 8.93, df = 3, p = 0.030) and for degree of bronchial reactivity (BR) after adjustment for other socioeconomic factors and smoking in the home (z = 1.97, p = 0.049). Bronchial reactivity was defined as the percentage drop in FEV1 per cumulative histamine dose from postsaline to end dose. The results demonstrate that studies on bronchial responsiveness can be used to assess the effects of air quality on the respiratory health of children and will be employed to measure the impact of new air quality control measures in Hong Kong.

Air Pollution↗
PubMed1992

Prenatal exposure to alcohol enhances thymocyte mitogenic responses postnatally.

Previous studies have shown altered cell-mediated immune responses in animals prenatally exposed to ethanol. The present study was designed to determine the ontogeny of proliferative responses of thymocytes postnatally following prenatal exposure to ethanol. Thymocytes obtained from 44-day old Sprague-Dawley male rats exposed to 5% (w/v) ethanol during the last two weeks of gestation had a significantly greater response to mitogenic stimulation by concanavalin A (Con A, 5.0 micrograms/ml) than controls. A similar trend was observed in rats at postnatal days 30 and 72, but not at day 16. Con A-conditioned thymoblasts from day-44 fetal alcohol-exposed animals were less responsive to further activation by a crude Con A supernatant than controls, but this response normalized by day 72. These findings reveal that the effects of ethanol exposure in utero in male rats include alterations in the development of thymoproliferative responses to mitogen which persist through the peripubertal period and normalize in part by young adulthood.

Animals↗
PubMed1991

Studies on the respiratory health of primary school children in urban communities of Hong Kong.

The first stage of a 2-year survey of respiratory morbidity in primary school children was conducted in two districts of Hong Kong in April/May 1989. One group (2009) of children was from Kwai Tsing District, which had high levels of exhaust emission from factories. The other group (1837) was from Southern District where atmospheric pollution was considered to be relatively low. After adjustment for gender, age, socioeconomic factors, child smoking and exposure to parental smoking, the prevalence ratios of sore throat, evening cough, cough for more than 3 months, morning phlegm and wheezing were found to be significantly higher in Kwai Tsing. The difference between the districts is likely to be related to the environmental air quality. The study, which is continuing, will provide the basis for an evaluation of the impact of new low sulphur fuel regulations introduced in July 1990.

Acute Disease↗
PubMed1991

Changes with age in the proliferative response of splenic T cells from rats exposed to ethanol in utero.

The fetal alcohol syndrome is associated with altered immunity. Several laboratories have confirmed that rodents exposed to ethanol in utero demonstrate both diminished proliferative responses of T cells to mitogens and diminished proliferative responses of T-blast cells to human recombinant interleukin 2 (rIL2). We examined the developmental time course of these altered immune responses by testing the immune function of in utero ethanol-exposed rats at various ages. We found that while diminished splenic T cell proliferative responses could not be detected at 2 weeks, they were present at 6 weeks after birth and suppression was maximal at 6 weeks and 3 months. Thereafter, at 5 and 7 months, the altered immune responses gradually declined and normalized at 8 months of age. Thus, both altered T cell mitogenesis and the blunted IL2-induced proliferative response of T-blast cells could serve as biomarkers of fetal exposure to ethanol.

Age Factors↗
PubMed1991

[Pelvic lipomatosis associated with cystitis glandularis--case report].

Pelvic lipomatosis is a rare benign disease of unknown etiology characterized by the proliferation of infiltrating fatty tissue within the deep bony pelvis. These fatty tissue may enclose the pelvic and retroperitoneal organs and various degrees of luminal compression and obstruction may happen. There is no typical presenting symptoms of pelvic lipomatosis. The major diagnostic methods are radiological examinations. CT scan is the definitive test to confirm the diagnosis. Open biopsy may be necessary when the diagnosis is inconclusive. Various treatment modalities have been tried, but only the diet therapy and complete ablation of fatty tissue ever reported to be successful. Cystitis glandularis, a rare proliferative inflammatory disease of the bladder, is reported to occur concurrently with pelvic lipomatosis in a patient. Herein we report a similar case. A middle-aged male patient was admitted with the chief complaint of painless gross hematuria for two weeks. After admission a series of radiological examinations and endoscopic bladder biopsy were performed. He was proved to be a rare case of pelvic lipomatosis associated with cystitis glandularis.

Adult↗
PubMed1990

Cochlear implant in Hong Kong Cantonese.

Cochlear implant surgery was performed in four Cantonese-speaking postlingually deaf Chinese adults, using the House/3M single channel device. This article outlines the methodology, including preoperative assessment and postoperative rehabilitation; and explains the necessary modifications in speech and audiologic work-up in Cantonese-speaking patients. Salient features of Cantonese phonetics, especially its tonal characteristics, are described. The findings of the study are presented. The results of the cochlear implant would suggest a performance superior to that of the hearing aid. Furthermore, the cochlear implant is able to detect tonal cues. This quality of the cochlear implant may prove to be a valuable asset to a tonal language-speaking cochlear implantee.

Adult↗
PubMed1988

Interaction of estrogen-nitrosourea conjugates with the estrogen receptor in rat uterus.

Several estrogen-nitrosourea conjugates have been synthesized with the aim of producing more selective cytotoxic agents. The conjugates were shown to compete with estradiol for binding to cytosolic estrogen receptor in rat uterus; the relative binding affinities for N-(2-chloroethyl)-N'-(3,17 beta-dihydroxyestra-1,3,5(10)-trien-17 alpha-yl)methyl-N-nitrosourea (17 alpha-CNU), N-(2-chloroethyl)-N'-(3-hydroxyestra-1,3,5(10)-trien-17 beta-yl)-N-nitrosourea (17 beta-CNU), and N-(2-chloroethyl)-N'-2,3-di(p-hydroxyphenyl)-pentanyl-N-nitrosoure a (HEX-CNU) were 2, 0.4, and 0.2, respectively, using a binding affinity of 100 for estradiol. In the ligand exchange assay, cytosolic receptors preloaded with 17 alpha-CNU and HEX-CNU were found to lose some of their estradiol (E2) binding sites, suggesting that binding to estrogen receptor (ER) may be irreversible. An increase of nuclear accumulation of ER was observed in the presence of 17 alpha-CNU and HEX-CNU. In the rat system, even at a 10,000-fold excess, these two agents failed to show any antagonism of the uterotrophic effect of E2 in vivo. The low binding affinity and instability of these conjugates may account for their lack of antiestrogen activity. On the other hand, 17 alpha-CNU at 100 or 1000 micrograms/day and HEX-CNU at 1000 micrograms/day demonstrated significant uterotrophic activity. This study did not resolve whether the stimulation of uterine growth was due to the parent estrogen-nitrosourea conjugate or to decomposition and/or metabolic products.

Animals↗
PubMed1987

Byssinosis and other respiratory problems in the cotton industry of Hong Kong.

Between February 1982 and October 1984, a total of 2,317 workers from all levels of cotton processing--carding, blowing, spinning and weaving--were studied in a citywide cross-sectional survey. The workers were administered the British MRC Questionnaire in local dialect and their pre- and postshift lung functions were assessed by portable spirometers. The prevalence of byssinosis for the whole industry was 2.3%, being much greater in the more dusty processes (blowing and carding, 5.6%; weaving 1.6%). Even more important was the prevalence of chronic obstructive airways disease (COAD) (13.8%) and a combination of nonspecific respiratory symptoms (10.0%), characterized by chest tightness and dyspnea, but not related to any specific day of the week such as those seen in typical byssinosis. The importance of these two large groups of respiratory problems in relation to byssinosis and the pathogenesis of respiratory diseases in people exposed to cotton dust is discussed.

Adult↗
PubMed1987

Redox reactions occurring during secondary ion mass spectrometry of some heteroanthracycline antitumor antibiotic precursors.

Positive and negative secondary ion mass spectra of the title compounds were produced by bombardment of solid deposits by 13 and 23 KeV cesium ions, respectively, and analyzed with a time-of-flight mass spectrometer. In addition to familiar protonation and alkali (mainly sodium) ion addition processes observed in the positive ion spectra and proton abstractions in the negative ion spectra (which enable determination of molecular weight) there is evidence from both spectral modes for oxidation-reduction processes in which species such as [M - H]+, [M - H + Na]+. and [M + 1]- are formed. It is argued that these may be formed rapidly from pre-associated molecules during bombardment/ionization rather than as a result of radiation damage. Sodium ion addition is apparently facilitated by the presence of electron pair donor groups, especially if chelation is possible.

Antibiotics, Antineoplastic↗