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Biomedical subjects

T Y Chan

Publications and source records attributed to T Y Chan.

At least 37 records · Page 2Linked to original sources
PubMed2000

Renal kallikrein-kinin system, but not renal dopamine system, mediates the natriuretic response to intravenous saline infusion in healthy Chinese subjects.

1. To assess the role of renal dopamine (DA), sympathetic nervous system (SNS) activity and the renal kallikrein-kinin system in sodium excretion in Chinese subjects, we studied the effects of intravenous saline infusion on the urinary excretions of sodium, free DA, free noradrenaline (NA) and kallikrein in eight healthy males aged 23-25 years. 2. After a baseline period of 1 h (hour 0), these subjects received 11 of 0.9% saline over 2 h (hours 1 and 2), followed by a 4-h recovery period (hours 3-6). From hours 0-4, subjects remained in the supine position, except to void urine. Distilled water was given orally throughout the study to ensure an adequate diuresis. 3. A 31-39% increase in sodium excretion (P < 0.05) was seen during hours 2 and 3. Urinary DA did not change throughout the study period. Urinary free NA showed no changes while the subjects remained supine, but an increase of 91-105% (P < 0.02) was seen after the subjects became ambulatory. However, there was a 103-140% increase in urinary kallikrein excretion (P < 0.05) during the saline infusion. Urinary kallikrein was still much higher (by 74%) than the basal level 1 h after the completion of the saline infusion. 4. There is no evidence from the present study that renal DA or SNS play any role in the natriuretic response to saline infusion in Chinese subjects. The brisk urinary kallikrein response, despite a relatively small salt load, suggests that the renal kallikrein-kinin system may play an important role in extracellular fluid volume and sodium homeostasis in Chinese subjects.

Adult↗
PubMed2000

Early role of neutrophil L-selectin in posttraumatic acute lung injury.

OBJECTIVE: To investigate whether early numerical and functional changes in circulating neutrophils and expression of neutrophil L-selectin and soluble L-selectin are related to the subsequent development of posttraumatic acute lung injury (ALI), the systemic inflammatory response syndrome, sepsis, and organ failure. DESIGN: Prospective study of whole blood and plasma samples to assess numerical and functional changes in circulating neutrophils and in soluble L-selectin. SETTING: The emergency department of a university hospital. PATIENTS: A total of 147 patients admitted to the resuscitation room after trauma were compared with 69 control subjects. Ten patients developed ALI. LABORATORY ANALYSIS: Flow cytometry of whole blood and ELISA of plasma. RESULTS: Total leukocyte and neutrophil counts, expression of L-selectin, and the ratio of neutrophil to plasma L-selectin increased with injury and were highest in those who developed ALI. Soluble L-selectin decreased with injury severity and was lowest in those who developed ALI. CONCLUSIONS: Early changes in the average expression of L-selectin per cell do not correlate with the development of subsequent posttraumatic ALI. However, the development of ALI is related to the total expression of L-selectin in the neutrophil mass, and the most striking association is in those with lower concentrations of plasma L-selectin.

Adult↗
PubMed2000

Toxicity of complementary therapies: an eastern perspective.

Chinese traditional medicine is used extensively in Chinese populations, and other Asian countries employ similar therapies. Herbal treatments have a major role in these systems, and although most have a well-established safety record, occasional adverse effects are seen. Problems arise when toxic herbs are used in excessive doses, with improper preparation, or when they are substituted erroneously. There may also be adulteration with Western drugs or heavy metals, and interactions between herbs and Western drugs may also occur. It is always prudent to obtain a complete history of the use of herbal medications during any clinical assessment, particularly in Asian patients.

Complementary Therapies↗
PubMed2000

Alternative therapies and medical science: designing clinical trials of alternative/complementary medicines--is evidence-based traditional Chinese medicine attainable?

Evidence-based traditional Chinese medicine is attainable. With good planning and a positive attitude, the remedies used in traditional Chinese medicine (TCM) and Chinese proprietary medicines can be studied at a standard acceptable to modern science. The identification of an active principal should not delay the search for effective remedies from the TCM pharmacopoeia. Herbal mixtures can be validly tested to establish their efficacy. Problems with potential batch-to-batch variation can be circumvented by appropriate randomization. Subsequent independent screening and randomization to treatment and placebo arms can allow for the individualization of treatments by TCM practitioners. However, clearly defined treatments are required and should be recorded in a manner that enables other suitably trained researchers to reproduce them reliably (e.g., using prescriptions in Chinese). Quality control of TCM is a prerequisite of credible clinical trials. Correct natural ingredients must be used without adulteration or erroneous substitution. Evidence of safety in man is essential, and in lieu of data from formal toxicity studies, clear, convincing, and impartial evidence of safety is needed based on their long-term use in mainstream TCM practice backed up by publications in the Chinese medical/scientific literature.

Clinical Medicine↗
PubMed2000

Improvements in the packaging of drugs and chemicals may reduce the likelihood of severe intentional poisonings in adults.

Because of the inconvenience and longer time required to punch out the tablets, strip packaging may reduce the number of tablets that can be readily swallowed by adults with self-poisonings. In fact, hospital-based studies of paracetamol poisoning in the U.K. and Hong Kong have shown that blister packs were associated with fewer tablets being ingested and large overdoses were mostly from loose preparations. In Australia, following the change in packaging for carbamazepine from bottles of tablets to blister packs, a marked decrease in the reported number of tablets ingested by patients was seen. Reducing the maximum number of tablets that can be available in individual preparations or prescriptions may also reduce the likelihood of severe poisonings. In France, but not in the UK, the content of each pack of paracetamol has been legally limited to 8 g. This was thought to be one reason why severe liver damage and deaths after paracetamol poisonings are less common in France than in the UK. Medicated oils containing methyl salicylate pose the threat of rapid-onset, severe salicylate poisoning if swallowed. To reduce the amount of methyl salicylate that can be readily swallowed, the methyl salicylate content and the size of the bottle and its opening should be restricted. In adults with Dettol poisoning, serious complications such as pulmonary aspiration are more likely if a large amount is ingested. Similarly, the risk may be reduced by restricting the size of bottle and its opening.

Acetaminophen↗
PubMed2000

Obesity is the key determinant of cardiovascular risk factors in the Hong Kong Chinese population: cross-sectional clinic-based study.

OBJECTIVES: To examine the interrelationships between obesity and various cardiovascular risk factors, and to investigate the relative importance of insulin and obesity in their associations with various pathophysiologies. DESIGN: Cross-sectional clinic-based study. SETTING: Medical clinics at a university teaching hospital, Shatin, Hong Kong. PARTICIPANTS: A heterogeneous cohort of 767 Hong Kong Chinese subjects with a mean age of 43 (standard deviation, 14) years. MAIN OUTCOME MEASURES: Body mass index, waist circumference, plasma insulin, insulin resistance index, fasting plasma glucose and lipid levels, blood pressure, and 24-hour urinary albumin excretion. RESULTS: Pathophysiological abnormalities and risk factors are frequently clustered to varying degrees. Compared with the control subjects, patients with at least one component of the metabolic syndrome were more obese, hyperinsulinaemic, insulin resistant, hyperglycaemic, hypertensive, dyslipidaemic, and albuminuric (all variables, P<0.001). Increasing degrees of body mass index, waist circumference, plasma insulin level, and insulin resistance index were associated with an increasing number of risk factors after adjusting for age and sex (all variables, P<0.02). Multiple regression analysis showed that obesity, as reflected by either the body mass index or waist circumference, had a closer association than plasma insulin with the fasting plasma glucose concentration, blood pressure, and high-density lipoprotein-cholesterol and triglyceride concentrations. Using 19.0-20.9 kg/m(2) as the reference body mass index interval, the lowest cardiovascular risk was associated with a body mass index of <23.0 kg/m(2). There was an increased risk of 3.1 and 5 times when the body mass index was 23. 0-24.9 kg/m(2) and > or =25 kg/m(2), respectively. CONCLUSIONS: Obesity, hyperinsulinaemia, and insulin resistance are characteristic features of Hong Kong Chinese patients who have various components of the metabolic syndrome. Obesity has a greater effect than plasma insulin on various pathophysiologies.

Adult↗
PubMed1999

Do peripheral blood counts have any prognostic value following trauma?

BACKGROUND: Both lymphocytosis and lymphopenia have been observed following trauma and each has been claimed to predict mortality. An understanding of the early temporal changes in leucocyte counts may help to explain why such discrepancies have been found. The purpose of this study was to determine the early serial changes in peripheral leucocyte counts following injury. METHODS: A whole blood cell counter was used to measure serial total leucocyte, granulocyte, lymphocyte and monocyte counts from 20 patients in the first 3 h following blunt injury. Four to six peripheral blood samples were taken from each subject and grouped into 20 min intervals. RESULTS: Granulocytosis, lymphocytosis and monocytosis were evident within 40 min of injury. A biphasic granulocyte and monocyte response was observed in the first 3 h following trauma. Lymphocytes showed a linear resolution towards normal (regression coefficient -0.022; p < 0.01) with some individuals developing a lymphopenia. No correlation with injury severity was observed. CONCLUSION: Rapid mobilisation and subsequent redistribution of leucocytes occurs early following injury. Temporal changes will affect any predictive value of circulating leucocytes and studies must be precise with respect to blood sampling time.

Adolescent↗
PubMed1999

Follow-up of atypical prostate needle biopsies suspicious for cancer.

OBJECTIVES: To determine both how the diagnosis of an atypical biopsy influences a urologist's decision to repeat the biopsy and the outcome of rebiopsy. METHODS: Of 200 atypical biopsies that we confirmed from outside consultations to the Johns Hopkins Hospital from 1992 to 1993, we were able to retrieve follow-up information for 144 cases. Each atypical biopsy was evaluated for the reason for atypia (atrophic glands, rule out [r/o] adenosis, atypical not otherwise specified [NOS; insufficient cytologic and/or architectural atypia], r/o prostatic intraepithelial neoplasia [PIN], inflammation, crush artifact) and a favored diagnosis (cancerous, benign, and undetermined). RESULTS: Of the 144 atypical biopsies, 92 were rebiopsied (63.9%). The time from the initial atypical biopsy to rebiopsy ranged from 0.5 months to 3 years (63% less than 6 months; 39% less than 3 months). Rebiopsy revealed carcinoma in 48.9%, benign in 38%, atypical in 8.7%, and PIN in 4.4%. The median prostate-specific antigen (PSA) value was lower in men who did not undergo a repeat biopsy (6 versus 7.8) (rank sum analysis, P = 0.04). No correlation was found between PSA level and results of the rebiopsy. Of the atypical biopsies in which cancer was favored, 61% were cancerous on rebiopsy versus 33% where a benign process was favored. The three reasons for atypical biopsies that seemed to correlate with outcome of rebiopsy were atypical NOS (68% cancer on rebiopsy); inflammation (63% cancer on rebiopsy); and r/o adenosis (36% cancer on rebiopsy). CONCLUSIONS: Although 48.9% of the rebiopsied cases were cancerous, only 63% of men underwent rebiopsy, raising a concern that cancers are being missed in those cases not rebiopsied after an atypical diagnosis. Although there was a trend for serum PSA to correlate with outcome of rebiopsy, this correlation was not significant, and even men with serum PSA less than 4 ng/mL had a 33% risk of cancer on rebiopsy. Although histologic features of the atypical foci may be useful as factors in determining the urgency for rebiopsy, they also were not statistically significant in predicting outcome. Men with atypical diagnoses should undergo rebiopsy regardless of serum PSA levels and regardless of why the lesions were atypical.

Adult↗
PubMed1999

Management of NIDDM by family doctors in Hong Kong: a questionnaire survey.

The management approach to non-insulin-dependent diabetes mellitus among family doctors in Hong Kong was studied using two case histories. In 1996, all 804 fellows, members and associate members of the Hong Kong College of Family Physicians were sent a letter and a questionnaire. Of the 512 who responded, 405 were male and 95 were female (12 were discarded) with ages ranging from 24 to 77 years (median 40). For the 48-year-old obese man who showed improvements in blood glucose and symptoms after diet for 6 weeks (Case 1), most respondents suggested adding a sulphonylurea (39.0%) or metformin (21.1%), or continuing diet (35.2%). Younger and more junior doctors tended to use metformin plus diet. Of 192 respondents who wanted to use a sulphonylurea, gliclazide (45.8%) and glibenclamide (42.7%) were chosen most often. For the 76-year-old overweight woman with symptomatic diabetes despite diet therapy (Case 2), most respondents suggested adding a sulphonylurea (41.9%), metformin (25.6%) or both (19.2%). Younger and more junior doctors tended to use metformin plus diet, whereas older doctors tended to use insulin plus diet. Older and more experienced doctors tended to use diet plus metformin and sulphonylurea. Of 208 respondents who wanted to use a sulphonylurea, gliclazide (47.8%) and glibenclamide (30.1%) were chosen most often. The management approach to NIDDM varied with the age and experience of the doctor.

Age Factors↗
PubMed1998

Estimates on the incidence of antidiabetic drug-induced severe hypoglycaemia in Hong Kong.

In order to estimate the incidence of severe hypoglycaemia (defined as episodes severe enough to require hospitalization in general medical wards) among known diabetics in Hong Kong in 1990, both the total number of such admissions to the Prince of Wales Hospital and the age and sex distribution and number of known diabetics among its catchment population were defined. The latter was derived from the 1991 census and two studies or the prevalence of diabetes mellitus in Chinese subjects in the New Territories East region in 1987 and 1990. The incidence of severe hypoglycaemia was generally higher in women than in men and in older than in younger subjects. The incidence was 15-19 times higher in subjects aged >or=60 years than in those aged <or=59 years (men 3.51 versus 0.17%, women 6.86 versus 0.43%, overall 5.16 versus 0.29%). As many as 24.16% of the subjects aged 70-74 years had severe hypoglycaemia in 1990. The overall incidence of severe hypoglycaemia in all known diabetics was 1.40%. Based on the data from a drug utilization study (70.24% and 5.93% of diabetics receiving sulphonylureas and insulins, respectively), it could be estimated that in 1990, the incidence of hypoglycaemia requiring hospitalization in general medical wards was 1.42% for sulphonylureas and 6.84% for insulins.

Journal Article↗
PubMed1998

Leukocyte L-selectin is up-regulated after mechanical trauma in adults.

BACKGROUND: Infection and multiple organ failure remain the principal causes of late mortality after trauma despite advances in the resuscitation of injured patients. Because a better understanding of postinjury leukocyte trafficking is essential to the development of possible therapeutic measures aimed at preventing these complications, we have performed a study of one factor in the early posttrauma endothelial adhesion behavior of monocytes, lymphocytes, and neutrophils: their cell surface expression of L-selectin (CD62L). We have also studied the plasma levels of soluble L-selectin in these patients. METHODS: Two venous blood samples were taken from each of 41 trauma patients at median times of 1 and 20 hours after injury. The study group included 16 patients with major (Injury Severity Score (ISS) > or = 16), 17 with moderate (ISS = 9-15), and 8 with minor (ISS < 9) trauma. Cell surface L-selectin was measured on leukocyte subsets by staining with specific fluorescent-labeled monoclonal antibodies to CD62L and using flow cytometry. Both the percentage of cells expressing the molecule and the mean channel fluorescence were measured. Levels of soluble L-selectin were measured in the plasma, sampled concurrently, by enzyme-linked immunosorbent assay. RESULTS: Monocytes, lymphocytes, and neutrophils all showed an early increase in cell surface L-selectin expression as measured by mean channel fluorescence (p < 0.0001, p < 0.001, and p < 0.0001, respectively), and this persisted in later samples taken at a median 20 hours after injury (p < 0.0001,p < 0.0001, and p < 0.01). Only monocytes showed an increased percentage of cells expressing the molecule in the early phase (p < 0.02), and this remained in the later phase (p < 0.001). Monocytes also showed a further significant increase in mean channel fluorescence (p < 0.02) between the two periods. No significant changes in levels of plasma soluble L-selectin were found at either stage. CONCLUSION: An increase in the expression of L-selectin on each of three leukocyte populations has been demonstrated in the early phase after trauma. This would tend to promote rolling behavior of leukocytes and increase their contact with the vascular endothelium. There were marked differences in the later responses of the three populations, which may represent differential control of their behavior.

Adolescent↗
PubMed1998

Plasma melatonin profile and hormonal interactions in the menstrual cycles of anovulatory infertile women treated with gonadotropins.

The patterns of plasma melatonin, gonadotropins, sex steroids and prolactin were studied in anovulatory infertile females undergoing ovulation induction with hMG/hCG. Melatonin levels were found to fluctuate during the menstrual cycle of these subjects with a nadir at mid-cycle and peak occurring at the early follicular/late luteal phases of the cycle (p < 0.05). Melatonin correlated negatively with estradiol during the follicular phase (r=-0.5180, p < 0.05) and positively with LH (5 + 0.6321, p < 0.05) in the luteal phase, respectively. Correlational analyses by partial and multiple correlations suggest that the effects of estradiol and LH on melatonin in the follicular phase are interdependent whereas the effect of LH on melatonin in the luteal phase is independent of the effects of other hormones. The results suggest that hormonal interactions and phases of the cycle are important variables contributing to the fluctuations in melatonin levels during the menstrual cycle.

Adult↗