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Biomedical subjects

C K Cheung

Publications and source records attributed to C K Cheung.

At least 19 recordsLinked to original sources
PubMed2006

Defects in ZnO nanorods prepared by a hydrothermal method.

ZnO nanorod arrays were fabricated using a hydrothermal method. The nanorods were studied by scanning electron microscopy, photoluminescence (PL), time-resolved PL, X-ray photoelectron spectroscopy, and positron annihilation spectroscopy before and after annealing in different environments and at different temperatures. Annealing atmosphere and temperature had significant effects on the PL spectrum, while in all cases the positron diffusion length and PL decay times were increased. We found that, while the defect emission can be significantly reduced by annealing at 200 degrees C, the rods still have large defect concentrations as confirmed by their low positron diffusion length and short PL decay time constants.

Journal Article↗
PubMed2005

By what mechanism do leeches help to salvage ischaemic tissues? A review.

The therapeutic use of leeches in medicine dates back to 50 b.c. and was cited by ancient authors. The medicinal leech, Hirudo medicinalis, has been used with increasing frequency during the past few years by reconstructive surgeons to help salvage ischaemic tissues. We aim to summarise the anatomy, physiology, and pharmacological mechanisms of action of leeches to provide reconstructive surgeons with a theoretical basis for their use.

Animals↗
PubMed2002

PCDD/PCDF, chlorinated pesticides and PAH in Chinese teas.

Four samples of Chinese tea (two green teas, and two brick teas) were analyzed for their concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF), chlorinated pesticides and PAH. The infusions prepared from these teas were also analyzed for PCDD/PCDF. The levels of DDT and its metabolites in tea leaves were within the safety limit of 0.2 mg/kg. Rather high levels of total PAH were obtained in brick tea (1,048-1,162 mg/kg). when compared with green tea (497-517 mg/kg). In terms of PCDD/PCDF, the concentrations of green tea and brick tea differed by a factor of 16, while the concentrations of all infusions were within a factor of 2. The dioxin concentrations in green tea leaves can be explained through uptake of atmospheric PCDD/PCDF. The higher concentrations in the brick tea leaves are due the longer exposure time, and to certain extent, the use of old leaves, branches and roots when making the tea, and additional components such as soil particulates through contamination. Certain Chinese populations drinking a large amount of brick tea (>31 per day) indicated that individuals of these populations consume more tea than Europeans or North Americans result in a comparably higher intake of PCDD/PCDF. Tea consumption can attribute to up to 10% of the TDI recommended by WHO (only PCDD/PCDF considered, no PCB analyzed).

Benzofurans↗
PubMed2000

Cyberostracism: effects of being ignored over the Internet.

Ostracism is such a widely used and powerful tactic that the authors tested whether people would be affected by it even under remote and artificial circumstances. In Study 1, 1,486 participants from 62 countries accessed the authors' on-line experiment on the Internet. They were asked to use mental visualization while playing a virtual tossing game with two others (who were actually computer generated and controlled). Despite the minimal nature of their experience, the more participants were ostracized, the more they reported feeling bad, having less control, and losing a sense of belonging. In Study 2, ostracized participants were more likely to conform on a subsequent task. The results are discussed in terms of supporting K. D. Williams's (1997) need threat theory of ostracism.

Adolescent↗
PubMed1999

Beliefs about elderly people among social workers and the general public in Hong Kong.

Social learning theory expects the social worker to hold more favorable beliefs about elderly people and scapegoat theory expects one having higher self-esteem to be so. The role of social work and self-esteem may be factors explaining ageism at the individual level. Because ageism seems to emerge in Hong Kong as well as other industrialized societies, the study surveyed the general public, social workers, students, elderly center members to (1) determine the relative extent of ageism in terms of beliefs about physical, social, and psychological dimensions of elderly people, and (2) test hypotheses deriving from social learning and scapegoat theories. Analysis of data from 902 respondents showed that people younger than 60 years were more favorable regarding the social dimension and less favorable regarding the psychological dimension of beliefs about elderly people. One with higher self-esteem tended to be more favorable in beliefs about social and psychological dimensions of elderly people but less favorable in the belief about the physical dimension. Although the gerontological social worker was more favorable in the belief regarding the social dimension of elderly people than others, this difference might be attributable to his or her higher self-esteem. Hence the role of social work did not necessarily improve one's image of elderly people in Hong Kong.

Journal Article↗
PubMed1999

Job satisfaction, work values, and sex differences in Taiwan's organizations.

This study of 927 employees in Taiwan is an attempt to explain job satisfaction and sex differences with reference to work values. Initially, the results confirmed that both job satisfaction and work values consisted of 4 common dimensions pertaining to the task, team, reward, and status. Subsequent analyses showed that male employees had higher rank and higher task, team, and status satisfaction than did female employees. The sex difference was not attributable to differences in work values. Placing higher values on the task and team dimensions and a lower value on the reward dimension seemed to lead to greater job satisfaction.

Adult↗
PubMed1999

Public evaluation of an announcement of public interests communicated by an AIDS patient.

Announcements of public interests (APIs) on television (TV) have been an important means of AIDS prevention. Recently in Hong Kong, the first API on TV which was communicated by a male AIDS patient, named J.J., was displayed on the screen from April to December, 1995. The objective of this study is to examine the effectiveness of this API, as compared with other APIs previously shown in Hong Kong. Collecting data from a random sample of 1,275 residential respondents in Hong Kong through a telephone survey, this study demonstrated that the public gave very favorable evaluation on J.J.'s API, when compared with other APIs. Remarkable impacts of J.J.'s API on the public included increasing concern for AIDS, condom use, and testing blood for HIV infection, and reducing the number of sex partners. The impacts tended to be more salient on male than female viewers. Some of these impacts also appeared to vary by different levels of education and family income.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Validating an American scale in Hong Kong: the Center for Epidemiological Studies Depression Scale (CES-D).

The construct validity of a Chinese-language version of the Center for Epidemiological Studies Depression Scale (CES-D; Radloff, 1977) was tested on a sample of 138 Hong Kong Chinese married couples. Confirmatory factor analysis identified 2 factors: (a) depressive symptom factors and (b) interpersonal problem factors. Those factors attained convergent, discriminant, and structural validity when evaluated against social desirability. The CES-D also manifested nomological validity in terms of its significant relationships with measures of life satisfaction and stressful life events.

Adult↗
PubMed1997

Accuracy, precision and user-acceptability of self blood glucose monitoring machines.

The performance of six self-monitoring blood glucose (SMBG) machines (Accutrend, Reflolux S, Companion 2, Glucometer GX, Glucometer IV and One Touch II) were examined using venous blood samples from 88 patients. Whole blood glucose (BG) values were measured by four machines from each brand. Machine-generated whole blood glucose (BG) values were corrected before comparison with laboratory plasma glucose values, measured by a glucose oxidase method. Based on error grid analysis, most of the corrected machine-generated BG values were clinically acceptable. Accutrend, Glucometer IV and Companion 2 showed the greatest consistency between machines of the same brand. Over 80% of corrected BG values generated by Glucometer IV fell within +/-10% of the reference values. One Touch II yielded the most reproducible results with a mean CV of 2.7% and was considered the most user friendly machine. More studies are required to examine the performance of these machines in the hands of patients.

Analysis of Variance↗
PubMed1997

World understanding and well-being in a Hong Kong Chinese marital context.

According to social constructionist theory, an individual's understanding of the world serves to maintain social order and well-being. In this study, this assertion was tested by investigating a mediating process through the contribution of world understanding to problem-solving confidence. Causal modeling with data from 138 married couples in Hong Kong supported this mediating process: World understanding was positively related to problem-solving confidence, which in turn was positively related to well-being, defined by life satisfaction and depression. In addition, social support and exposure to information were possible determinants of one's world understanding. Social support also contributed to problem-solving confidence and well-being. The causal model was applicable to both husbands and wives.

Adult↗
PubMed1997

Toward a theoretically based measurement model of the good life.

A theoretically based conceptualization of the good life should differentiate 4 dimensions-the hedonist good life, the dialectical good life, the humanist good life, and the formalist good life. These 4 dimensions incorporate previous fragmentary measures, such as life satisfaction, depression, work alienation, and marital satisfaction, to produce an integrative view. In the present study, 276 Hong Kong Chinese husbands and wives responded to a survey of 13 indicators for these 4 good life dimensions. Confirmatory hierarchical factor analysis showed that these indicators identified the 4 dimensions of the good life, which in turn converged to identify a second-order factor of the overall good life. The model demonstrates discriminant validity in that the first-order factors had high loadings on the overall good life factor despite being linked by a social desirability factor. Analysis further showed that the second-order factor model applied equally well to husbands and wives. Thus, the conceptualization appears to be theoretically and empirically adequate in incorporating previous conceptualizations of the good life.

Adult↗
PubMed1997

Parental distress and children's problems among single-parent families in China.

The coercion model explains reciprocal relationships between parents' and children's adjustment problems, with the mediation of parenting behavior and social relationships. A survey of 301 single parents in Guangzhou, China, was performed to test such a model with reference to parental distress, perceived behavioral problems and anxiety of the eldest child, acceptance of the child, and experienced social pressure and social support. Structural equation modeling demonstrated a good fit of the coercion model as a theoretically based and simplified representation of the relationships, supporting the hypotheses that (a) the parent's acceptance helps prevent the child's behavioral problems, (b) the child's behavioral problems and anxiety contribute to the parent's distress, (c) the child's behavioral problems and anxiety invite social pressure on the parent, (d) social pressure on the parent aggravates and social support for the parent attenuates the parent's distress, (e) social pressure on and social support for the parent facilitate the parent's acceptance of his or her child. However, the effect of parental distress on acceptance of the child was not significant.

Anxiety↗
PubMed1997

Interference of creatinine measurement in CAPD fluid is dependent on glucose and creatinine concentrations.

BACKGROUND: High glucose concentration in CAPD fluid is known to interfere with creatinine measurement, which is required for assessment of peritoneal membrane permeability and adequacy of dialysis. Correction formulae have been proposed but they may be method/analyser-dependent. We studied such interference in detail. METHODS: CAPD fluid was diluted to prepare six specimens with glucose concentrations ranging from 9.1 to 154.4 mmol/l. To each specimen, creatinine standard was added to give five different concentrations from 50 to 800 mumol/l. The 30 specimens were assayed for creatinine with six routine clinical chemistry analysers (Hitachi 911 and 747, Technicon RAXT and SMAC3, Beckman CX7, and Kodak Ektachem 700). Creatinine interference was calculated by subtracting the apparent creatinine concentration with corresponding baseline creatinine concentration (measured at glucose = 9.1 mmol/l) in the same series. RESULTS: At constant creatinine concentration, interference increased with increasing glucose concentration to varying extents (up to 200%) amongst the six analysers. At constant glucose concentration, interference decreased with increasing creatinine concentration in analysers using the alkaline picrate reaction but increased in the Kodak analyser using enzymatic assay. CONCLUSION: Interference of creatinine measurement in CAPD fluid is dependent on glucose and creatinine concentrations, and each centre should derive specific correction formulae for its analytical system.

Ascitic Fluid↗
PubMed1997

Motor power pharmacodynamics of subarachnoid hyperbaric 5% lidocaine in the sitting position.

BACKGROUND: Repetitive dynamometric measurement using a plantar flexion power device (PFPD) provides detailed data describing the onset and offset of motor block following spinal administration of lidocaine. The aim of this study was to evaluate administration of two doses of spinal lidocaine in the sitting position to determine whether our dynamometric model produces data consistent with our current understanding of the pharmacokinetics of subarachnoid, hyperbaric, 5% lidocaine. METHODS: Twenty male patients (54 to 80 yr) undergoing cystoscopy received spinal anaesthesia with either 75 mg (n = 10) or 100 mg of hyperbaric lidocaine 5%, in the sitting position, under standardised conditions. Plantar flexion muscle power was recorded during onset and offset of anaesthesia using a load cell interfaced with a computer (PFPD). RESULTS: Onset of paralysis following spinal block in the sitting position was rapid and complete with motor power declining exponentially to 5% of preoperative values by 8.5 min in all patients. There was no difference in decay or recovery of plantar flexion motor power data between dosage groups in the sitting position. Measurement using the PFPD shows that onset of motor paralysis is described by an exponential decay and that motor recovery occurs at a fixed rate. Extent of block to cold and pinprick was similar in both dosage groups in the sitting position (median T4). CONCLUSION: This study shows that in the sitting position, doses less than 75 mg of 5% hyperbaric lidocaine are required to significantly improve ambulatory times.

Aged↗
PubMed1996

Albuminuria, insulin resistance and dyslipidaemia in Chinese patients with non-insulin-dependent diabetes (NIDDM).

In order to examine relationships between albuminuria, insulin resistance, and dyslipidaemia in non-insulin-dependent diabetes (NIDDM), we studied 164 Chinese patients (68 men, 96 women), treated with diet or oral hypoglycaemic agents, on three occasions during a 6-week period. Antihypertensive treatment, if previously prescribed, was withdrawn for at least 2 weeks before the study period. Insulin resistance was calculated from simultaneous fasting plasma glucose and insulin concentrations using the homeostasis model assessment (HOMA) method. Based on two of three 24 h urinary collections, 87 (53%) patients had normoalbuminuria, 46 (28%) microalbuminuria, and 31 (19%) macroalbuminuria. Despite similar glycaemic control, patients with abnormal albuminuria had higher mean arterial pressure, fasting plasma total cholesterol, triglyceride and serum apo B concentrations and were more insulin resistant than normoalbuminuric patients. Albuminuria correlated with mean arterial pressure (r = 0.31, p < 0.001), triglyceride (r = 0.36, p < 0.001), total cholesterol (r = 0.28, p = 0.001), apolipoprotein B (apo B) (r = 0.25, p = 0.003), and insulin resistance (r = 0.25, p < 0.002). These close associations may contribute to the increased cardiovascular risk in Chinese NIDDM patients with abnormal albuminuria.

Albuminuria↗
PubMed1996

Conservative orientation as a determinant of hopelessness.

Conservative orientation is identified with reference to authoritarianism, work ethic belief, just world belief, and endorsement of individualistic causes of social problems. This over-arching orientation is hypothesized to affect hopelessness and to be affected by self-esteem with reference to ego development theory and learned helplessness theory. Causal modeling of data obtained from 1st-year college students (N = 556) in Hong Kong supports the hypotheses, showing that a student's hopelessness relates to his or her conservative orientation, even when self-esteem is controlled. This relationship can be interpreted by ego development and learned helplessness theories and cannot be explained as a spurious effect. Through the theories, hopelessness is interpreted as a result of maladaptive development and fatalistic, alienated, and helpless outlooks. This maladaptive development and the outlooks in turn result from students' conservative and individualistic orientation.

Adolescent↗
PubMed1995

Increased bone resorption and decreased bone formation in Chinese patients with hip fracture.

Biochemical markers of bone formation (bone-specific alkaline phosphatase and osteocalcin) and bone resorption (hydroxyproline excretion and bone isoenzyme of acid phosphatase) were measured in 30 patients (15 M and 15 F) with hip fracture and 30 healthy subjects matched for age and sex. Bone isoenzyme of tartrate-resistant acid phosphatase (TRACP) was measured by a recently developed specific immunoassay. Serum osteocalcin concentration and bone-specific alkaline phosphatase activity were significantly lower and serum TRACP concentration and urinary hydroxyproline excretion were elevated in patients compared with healthy subjects. We suggest that there is reduced bone formation and increased bone resorption in patients with hip fracture.

Acid Phosphatase↗