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Biomedical subjects

H Y Wong

Publications and source records attributed to H Y Wong.

16 recordsLinked to original sources
PubMed1992

Social stress and atherosclerosis in roosters.

1. Socially stressed roosters fed either plain mash or an atherogenic diet had a greater incidence and severity of aortic atherogenesis than similarly fed non-stressed birds. 2. Results demonstrated a significant atherogenic effect of stress in chickens even in the absence of hyperlipidaemia. 3. Lack of appreciable differences in plasma lipids between stressed and non-stressed birds suggested that the atherogenic effects of stress may be attributable to neuroendocrine responses. 4. Levels of HDLc of plain mash groups were significantly higher than in the atherogenic fed groups. 5. Haemodynamic data showed no treatment-related differences.

Animals↗
PubMed1992

Stroke subtypes among Chinese living in Hong Kong: the Shatin Stroke Registry.

The Shatin Stroke Registry is a prospective study of all patients admitted with acute stroke to a general hospital in Hong Kong where the population is predominantly Chinese. Each patient was examined by a neurologist and 95.5% of the patients had a brain CT. Of 777 patients included in the study, 44.0% had a cortical/subcortical infarct, 18.5% a supratentorial lacunar infarct, 24.2% a supratentorial intracerebral hemorrhage, 5.8% brainstem/cerebellar infarct, 2.9% a brainstem/cerebellar hemorrhage, and 4.5% an uncertain diagnosis. The overall 30-day case fatality rate was 25.4%. Comparison with five stroke registries from the West suggests that intracerebral hemorrhage occurs between two and three times more frequently in the Chinese than in Westerners. Whether there is any difference in the relative frequencies for lacunar infarction remains unclear.

Adult↗
PubMed1992

Effects of diazepam (Valium) on aortic atherogenesis and plasma lecithin: cholesterol acyltransferase activity in cockerels fed an atherogenic diet.

Blood plasma LCAT (lecithin: cholesterol acyltransferase, EC 2.3.1.43) was studied in cockerels fed an atherogenic diet to determine if attenuation of aortic atherogenesis, as a result of simultaneous treatment of the birds with diazepam, might be related to modulation of enzyme activity by the drug. Administration of diazepam (0.6 mg/kg) did not influence LCAT. It was observed that no relationship could be established between enzyme activity and the extent of aortic atherogenesis. In contrast, addition of diazepam in vitro to cockerel plasma caused a concentration-dependent inhibition of LCAT activity. The effect was most pronounced when diazepam was present at a concentration of 50-200 microM, where inhibition of enzyme activity was 25-65%. Thus, pharmacologic doses of diazepam do not appear to affect LCAT in vivo. It is concluded that diazepam attenuates aortic atherogenesis in cockerels fed an atherogenic diet by a mechanism independent of LCAT.

Animals↗
PubMed1991

Enhanced choline and Rb+ transport in human erythrocytes infected with the malaria parasite Plasmodium falciparum.

Human erythrocytes infected in vitro with the malaria parasite Plasmodium falciparum showed a markedly increased rate of choline influx compared with normal cells. Choline transport into uninfected cells (cultured in parallel with infected cells) obeyed Michaelis-Menten kinetics (Km approximately 11 microM). In malaria-parasite-infected cells there was an additional choline-transport component which failed to saturate at extracellular concentrations of up to 500 microM. This component was less sensitive than the endogenous transporter to inhibition by the Cinchona bark alkaloids quinine, quinidine, cinchonine and cinchonidine, but showed a much greater sensitivity than the native system to inhibition by piperine. The sensitivity of the induced choline transport to these reagents was similar to that of the malaria-induced (ouabain- and bumetanide-resistant) Rb(+)-transport pathway; however, the relative magnitudes of the piperine-sensitive choline and Rb+ fluxes in malaria-parasite-infected cells varied between cultures. This suggests either that the enhanced transport of the two cations was via functionally distinct (albeit pharmacologically similar) pathways, or that the transport was mediated by a pathway with variable substrate selectivity.

Animals↗
PubMed1991

Dose-finding study of intramuscular midazolam preanesthetic medication in the elderly.

Intramuscular midazolam frequently results in excessive sedation in elderly patients. The effects of preanesthetic medication with intramuscular midazolam were examined in 100 elderly patients, aged 60-86 yr, given 1, 2, or 3 mg midazolam or placebo using a randomized, double-blind study design. Level of sedation and anxiety were assessed every 15 min for 1 h. Picture cards were presented at the same times in order to assess recall of these cards 24 h later. All three doses of midazolam produced rapid onset of sedation, anxiolysis, and anterograde amnesia. These effects decreased in intensity by 60 min after drug injection. The intensity and extent of these effects were comparable with those reported with higher doses in younger patients, although with the 1-mg midazolam dose the effects were shorter-lived, and a difference from placebo was not consistently seen. Three patients (3%), all older than 70 yr, became unresponsive to vocal and tactile stimuli. This level of drowsiness was unrelated to body weight, age, or ASA physical status. We conclude that in adults between 60-69 yr old, midazolam 2 or 3 mg intramuscularly can be effective as preanesthetic medication without causing excessive drowsiness. However, intramuscular midazolam should be used cautiously, under continuous observation, in patients aged 70 yr and older because excessive drowsiness may occur.

Aged↗
PubMed1991

Hypertension, lipoprotein(a), and apolipoprotein A-I as risk factors for stroke in the Chinese.

We analyzed the serum concentrations of lipids and lipoproteins and the prevalence of other risk factors in a case-control study of 304 consecutive Chinese patients with acute stroke (classified as cerebral infarction, lacunar infarction, or intracerebral hemorrhage) and 304 age- and sex-matched controls. For all strokes we identified the following risk factors: a history of ischemic heart disease, diabetes mellitus, or hypertension; the presence of atrial fibrillation or left ventricular hypertrophy; a glycosylated hemoglobin A1 concentration of greater than 9.1%; a fasting plasma glucose concentration 3 months after stroke of greater than 6.0 mmol/l; a serum triglyceride concentration 3 months after stroke of greater than 2.1 mmol/l; and a serum lipoprotein(a) concentration of greater than 29.2 mg/dl. We found the following protective factors: a serum high density lipoprotein-cholesterol concentration of greater than 1.59 mmol/l and a serum apolipoprotein A-I concentration of greater than or equal to 106 mg/dl. The patterns of risk factors differed among the three stroke subtypes. When significant risk factors were entered into a multiple logistic regression model, we found a history of hypertension, a high serum lipoprotein(a) concentration, and a low apolipoprotein A-I concentration to be independent risk factors for all strokes. The attributable risk for hypertension was estimated to be 24% in patients aged greater than or equal to 60 years. In this population, in which cerebrovascular diseases are the third commonest cause of mortality, identification of risk factors will allow further studies in risk factor modification for the prevention of stroke.

Apolipoprotein A-I↗
PubMed1991

The radiological (CT) and clinical sequelae of primary intracerebral haemorrhage.

To determine the radiological and clinical outcome of primary intracerebral haemorrhage, a prospective study was carried out involving computed tomography (CT) of 388 consecutive Chinese patients admitted with acute stroke to a large public hospital in Hong Kong. Further CT and functional assessment were performed 3 months later in 71% of survivors. The patients were admitted over a 6 month period. 120 (31%) were found to have had presumed primary intracerebral haemorrhage. Of these, 64 patients (53%) died within 3 months. From 40 of the 56 survivors who returned for a follow-up study at 3 months, 30 were functionally independent and five mildly disabled; only five were significantly disabled. Follow-up CT showed no residual lesion in 27%, low attenuation areas in 37%, slit-like lesions in 25% and calcification in 10% of patients. The size of residual lesions correlated statistically with the degree of residual disability, although the association was not close. It is concluded that primary intracerebral haemorrhage accounts for a high percentage of strokes among Hong Kong Chinese with more than half of the patients dying within 3 months. Many survivors, in whom follow-up CT appearances are variable, show good functional recovery.

Activities of Daily Living↗
PubMed1991

Pentamorphone for management of postoperative pain.

The efficacy, duration, and safety of the synthetic opioid pentamorphone in the treatment of acute postoperative pain were evaluated in a randomized, double-blind study of 72 patients given 0.08, 0.16, or 0.24 micrograms/kg of pentamorphone or a placebo intravenously in the recovery room after major abdominal or orthopedic surgery. Only patients given 0.24 micrograms/kg of pentamorphone experienced decreased pain intensity and increased sedation, both transient in duration. Although the two higher doses of pentamorphone delayed the patient's request for supplemental morphine, the total amount of morphine required within the first hour was not different between treatments. No acute cardiorespiratory changes were observed. Pentamorphone (0.08-0.24 micrograms/kg) was ineffective for treating acute postoperative pain after major surgery.

Adult↗
PubMed1991

Effects of diazepam, psychosocial stress and dietary cholesterol on pituitary-adrenocortical hormone levels and experimental atherosclerosis.

We studied the effects of psychosocial stress (S) and diazepam (D) on plasma lipids, adrenocorticotropin (ACTH), and corticosterone (B) levels of cockerels fed an atherogenic diet (AD) consisting of 2% cholesterol plus 5% cottonseed oil added to plain mash (PM). Seventy-six eight-week-old DeKalb cockerels were randomly assigned to the following groups: I. PM; II. PM + D; III. PM + S; ;IV. PM + S + D; V. AD; VI. AD + D; VII. AD + S and VIII. AD + S + D. S was induced by housing two birds to a cage and pairing them to a different bird daily. D was administered daily by gavage. Plasma ACTH and B levels were analyzed by RIA. Aortic atherosclerosis was grossly graded on a scale of 0-4 and also by gravimetric planimetry. After 10 weeks: 1. S birds had a significantly higher incidence and severity (p less than 0.04) of aortic atherogenesis and elevated ACTH and B levels (p less than 0.001) compared to unstressed PM groups. 2. AD significantly elevated the plasma levels of cholesterol, triglycerides, and the lipoprotein cholesterol that was precipitated by heparin-manganese (LDL-C + VLDL-C), compared to initial and/or PM levels (p less than 0.001). AD birds had a greater incidence and more severe aortic lesions in comparison to PM groups (p less than 0.002). Plasma hormone levels were significantly lower in birds fed AD alone compared to controls and stressed birds. 3. D significantly reduced the severity of aortic atheroma as well as decreased hormone levels in all treated groups (p less than 0.001). Therefore, we conclude that aortic atherosclerosis in cockerels can be induced by S and/or AD, and D can markedly reduce atherogenesis under these conditions. Since both AD and D decreased plasma ACTH and B levels, the anti-atherogenic action of D in these birds does not seem to directly involve these pituitary-adrenocortical hormones.

Adrenocorticotropic Hormone↗
PubMed1990

Effect of dietary cholesterol on the lipoprotein profile and binding of radioiodinated lipoproteins to hepatic membranes in the cockerel (Gallus domesticus).

1. Cockerels fed a cholesterol-supplemented diet experienced a marked elevation of lipoprotein particles of density less than or equal to 1.006 g/ml (VLDL) and a diminution of lipoprotein particles of density 1.02-1.05 g/ml (LDL). 2. Unlike VLDL of some cholesterol-fed animals, cholesterol-fed cockerel VLDL did not display beta-mobility on agarose gel electrophoresis. 3. [125I]LDL and [125I]HDL binding to cockerel liver membranes was not affected by cholesterol feeding. 4. Different lipoprotein types appear to bind to a common site on cockerel liver membranes. 5. The results suggest that liver cells of cockerels may not possess LDL binding sites that are analogous to those of mammalian species.

Animals↗
PubMed1990

Acute and long-term changes in serum lipids after acute stroke.

We studied serum lipid profiles in 171 patients less than or equal to 48 hours after the onset of acute stroke and 3 months later. The 83 patients suffering cerebral infarction had significantly higher serum concentrations of total cholesterol, low density lipoprotein-cholesterol, and apolipoprotein B and significantly lower serum concentrations of triglycerides and lipoprotein (a) less than or equal to 48 hours after ictus than 3 months later. The lipid profiles of the 53 patients suffering lacunar infarction were similar on both occasions, the only significant differences being higher total cholesterol and low density lipoprotein-cholesterol concentrations less than or equal to 48 hours after ictus. No significant changes were observed among the 35 patients suffering cerebral hemorrhage apart from a significantly higher concentration of high density lipoprotein3-cholesterol less than or equal to 48 hours after ictus. Our study, with many patients classified according to stroke subtype, gives results different from those of previous studies with much fewer patients. We conclude that in studies of serum lipid and lipoprotein concentrations as risk factors for cerebral infarction, comparing values obtained less than or equal to 48 hours after admission with control values may incorrectly identify certain lipid fractions as risk factors.

Aged↗
PubMed1989

Healing of gastric ulcer in the elderly: a double-blind study of cetraxate versus ranitidine.

Forty-nine Chinese patients, ages 65 years or over, with endoscopically and pathologically diagnosed benign gastric ulcer, completed a randomized double-blind double dummy trial in treatment with either cetraxate 200 mg four times daily or ranitidine 150 mg two times daily for 12 weeks or less if the gastric ulcer had completely healed. All patients tolerated the procedure well. At the end of the 4th, 8th, and 12th weeks ulcer healing was complete in 2 (8%), 11 (42%), and 17 (65%), respectively, of the cetraxate group (26 patients); and in 8 (35%), 18 (78%), and 22 (96%), respectively, of the ranitidine group (23 patients). All the differences in the healing rates were statistically significant. Pain relief was significantly earlier with ranitidine. Incidences of side effects were similar and not serious in the two groups. The results suggest that at the doses prescribed to the elderly, ranitidine is significantly more effective than cetraxate in gastric ulcer healing and pain relief.

Aged↗
PubMed1975

The cockerel as an animal model for atherosclerosis research.

The chicken is a good animal model for the study of atherosclerosis research because it is: 1. Omnivorous. 2. Small and suitable for prolonged laboratory investigation. 3. Able to develop spontaneous atherosclerosis. 4. Capable of producing atherosclerosis after cholesterol feeding with elevated hypercholesterolemia. A diet of 1/4% cholesterol plus 5% cottonseed oil added to starter-grower-mash resulted in aortic atherosclerosis with a slight but significant increase in plasma cholesterol. 5. Plasma levels of cholesterol and triglyceride are similar to those in humans. 6. Lipid composition of high and low density lipoproteins as well as chylomicrons resembles those of humans. 7. Has been noted that there is no essential difference between vascular lesions seen in chickens as a result of cholesterol diet and that of atherosclerosis observed in man.

Animals↗