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Biomedical subjects

J C Chan

Publications and source records attributed to J C Chan.

At least 73 records · Page 4Linked to original sources
PubMed2000

Glycaemic control in type 2 diabetes: the impact of body weight, beta-cell function and patient education.

We examined the determinants of glycaemic control in a consecutive cohort of 562 newly-referred Chinese type 2 diabetic patients (57% women) during a 12-month period. All patients underwent a structured assessment with documentation of clinical and biochemical characteristics. Pancreatic beta-cell function was assessed by fasting plasma C-peptide concentration. Insulin deficiency was defined as fasting plasma C-peptide <0.2 pmol/ml. Insulin resistance (IR) was calculated using the homeostasis model assessment (HOMA) based on a product of fasting plasma glucose and insulin concentrations. Treatment was considered appropriate when insulin-deficient patients were treated with insulin and non-insulin-deficient patients were treated with oral agents or diet. Mean (+/-SD) age was 54.3+/-13.8 years (range 17-87 years) and disease duration was 5.0+/-5.9 years. At the time of referral, 70.5% (n=396) were on drug therapy (9% on insulin and 62.8% on oral agents), 20.6% (n=116) were on diet and 9% (n=50) had not received any form of treatment. The mean HbA(lc) was 8.4+/-2.3%. The geometric mean (x// antilog SD) of IR was 4.62x//2.51 (range 0. 63-162.7) and correlated only with waist : hip ratio (WHR, p=0.008). The geometric mean of plasma C peptide was 0.47x//2.89 nmol/l and correlated with BMI (p<0.001). Glycated haemoglobin was correlated positively with age (p=0.013), disease duration (p<0.001), IR (p<0. 001) and negatively with BMI (p<0.001). Glycated haemoglobin was lower in patients who had seen a dietitian (7.9% vs. 8.7%, p<0.001) or diabetes nurse (7.8% vs. 8.7%, p<0.001) or who performed self blood glucose monitoring (7.9% vs. 8.6%, p=0.001) and higher among smokers (8.9% vs. 8.2%, p=0.003). Compared to insulin-deficient patients (n=118), non-insulin-deficient patients (n=413) had features resembling that of the Metabolic Syndrome with increased WHR (p=0.005), blood pressure (p<0.001), BMI (p=0.001) and were older (p=0.04). Amongst the insulin-deficient patients, 27% were treated with oral agents or diet. Patients receiving appropriate therapy (n=362) had a lower HbA(lc) than those treated inappropriately (n=173) (8.2% vs. 8.7%, p=0.02). On multivariate analysis, short disease duration (p<0.001), low IR (p<0.001), high BMI (p=0.001), diabetes education (p<0.001), lack of smoking (p=0. 014) and choice of appropriate treatment (p=0.009) were the independent determinants of good glycaemic control.

Adolescent↗
PubMed2000

Acute suppurative thyroiditis due to foreign body-induced retropharyngeal abscess presented as thyrotoxicosis.

Acute suppurative thyroiditis is an uncommon condition. Most patients have preexisting oropharyngeal fistulae. Penetrating oropharyngeal injuries resulting from swallowed foreign bodies provide an acquired channel of infection spreading into the relatively resistant thyroid gland. The authors describe a patient with infective thyroiditis complicating retropharyngeal abscess caused by a chicken bone that perforated the upper esophagus. Transient thyrotoxicosis complicating acute suppurative thyroiditis is very rare. Pertechnetate and Ga-67 scans confirmed extensive inflammation of the thyroid gland and the release of hormones as the cause, as distinct from concurrent Graves' disease. Awareness of this unusual complication is important to avoid inappropriate treatment for hyperthyroid disease.

Acute Disease↗
PubMed2000

Treatment of Chinese acromegaly with a combination of bromocriptine and octreotide.

BACKGROUND: Good results have been reported with combined use of octreotide and bromocriptine in acromegalic Caucasians. Data concerning the efficacy and tolerability of this combination treatment in Chinese acromegalic patients are scanty. AIM: The aim of this study was to assess the efficacy and tolerability of combined therapy using bromocriptine and octreotide in the treatment of acromegaly in Chinese patients and to compare the cost-effectiveness of various regimes. METHODS: Sixteen Chinese acromegalic patients with growth hormone (GH) concentration not suppressible to below 5 mU/L (2 microg/L) during an extended OGTT were recruited to undergo four phases of the study. During the study period, the patients were given bromocriptine alone, bromocriptine and low dose octreotide, bromocriptine and medium dose octreotide, and medium dose octreotide alone. Plasma concentrations of GH and insulin-like growth factor-1 (IGF-1) were measured before and after the completion of each phase. RESULTS: The number of patients reaching target GH concentrations was significantly higher when treated with octreotide compared to baseline (p<0.05). Bromocriptine alone had a significant effect but not to the extent of octreotide alone. A combination of low dose octreotide and bromocriptine is as efficacious in the treatment of acromegaly as high dose octreotide. None of the patients suffered from serious adverse effects. CONCLUSION: The results confirmed the usefulness and tolerability of bromocriptine and octreotide in Chinese acromegalics. The most cost-effective regime in this study was a combination of low dose octreotide and bromocriptine.

Acromegaly↗
PubMed2000

Acupuncture for episodic tension-type headache: a multicentre randomized controlled trial.

A multicentre, randomized clinical trial was undertaken to test the hypothesis that acupuncture is more efficacious than sham control procedure in the prevention of episodic tension-type headache. Fifty subjects were randomized to receive a course of treatment with either brief acupuncture or a sham procedure. Subjects were followed up for 3 months. Changes in headache were assessed by daily diary, the primary outcome measure being the number of days with headache. No significant differences were found between the changes in the two groups for any measure at any time point. Results also show that patient blinding was successful. In conclusion, this study does not provide evidence that this form of acupuncture is effective in the prevention of episodic tension-type headache.

Acupuncture Therapy↗
PubMed2000

Presence of mitochondrial tRNA(Leu(UUR)) A to G 3243 mutation in DNA extracted from serum and plasma of patients with type 2 diabetes mellitus.

AIMS/BACKGROUND: An A to G substitution at base pair 3243 in the mitochondrial tRNA(Leu(UUR)) gene (mt3243) is commonly associated with maternally inherited diabetes and deafness, and other diseases. It is possible that cell free mitochondrial DNA exists in serum and plasma from these patients, and these samples might be a source of material for the detection of such mutations. METHODS: Sixteen patients with type 2 diabetes mellitus and 25 healthy subjects were tested for the 3243 mutation by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis. Plasma and serum from the 41 subjects were tested blind, without knowledge of the final diagnosis. RESULTS: PCR amplification of the mtRNA(Leu(UUR)) region in mitochondrial DNA (mtDNA) in serum samples revealed the presence of mtDNA in all samples. After ApaI digestion of the amplified DNA fragments, mt3243 was detected in the serum and plasma samples of the seven patients with diabetes who had previously been found to have this mutation in their leucocyte DNA. None of the serum/plasma samples from the healthy subjects or those patients negative for mt3243 in their leucocytes had this mutation (p < 0.001). In addition, the degree of heteroplasmy of mt3243 appeared to be higher in serum and plasma samples than in leucocytes among mt3243 carriers (p < 0.05). CONCLUSIONS: Therefore, mtDNA and associated mutations are present and detectable in serum and plasma. Plasma and serum might be alternative sources for the molecular diagnosis of mt3243 associated diabetes mellitus, as well as other mitochondrial mediated diseases.

Adult↗
PubMed2000

Combined factor VII/protein C deficiency results in intrauterine coagulopathy in mice.

To determine whether an additional loss of the coagulation factor VII (FVII) gene influenced the coagulopathy observed in protein C gene-deficient (PC(-/-)) embryos and neonates, we crossed mice doubly heterozygous for the factor VII (FVII(+/-)) and protein C (PC(+/-)) genes to produce offspring possessing the 9 predicted genotypic combinations. FVII(-/-)/PC(-/-) embryos, although present at their expected Mendelian frequency, displayed a phenotype that had not been observed in either the FVII or PC singly deficient embryos. At E12.5 days postcoitum (dpc), FVII(-/-)/PC(-/-) embryos demonstrated an intra- and extravascular coagulopathy that progressed with substantial concomitant hemorrhage and peripheral edema by E17.5dpc, resulting in mortality immediately after birth. FVII(+/-)/PC(-/-) embryos showed a less severe phenotype, suggesting a gene dosage effect. The lack of rescue of PC(-/-) embryos and neonates and augmented coagulopathy resulting from an additional heterozygous or homozygous FVII deficiency are probably due to increased factor Xa and thrombin generation, resulting from loss of FVIIa-dependent tissue factor pathway inhibitor function and the absence of control at the levels of factors Va and VIIIa. The presence of fibrin in embryos in the absence of fetal FVII suggests that significant clot-generating potential exists outside of the embryonic factor VII-dependent pathway.

Animals↗
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

Hyperfibrinogenaemia did not improve after treating hyperglycaemia in Chinese type 2 diabetic patients.

Diabetic patients have higher cardiovascular risk than non-diabetic subjects, and fibrinogen has been reported to be one of the independent predictors for diabetic vascular complications. We examined 101 subjects (24 men, 77 women) who were newly diagnosed with type 2 diabetes. Thirty non-diabetic subjects were recruited as controls. The mean (standard deviation, SD) baseline fibrinogen concentrations in men and women were 3.87 (1.17) and 3.42 (1.00) g/L, respectively (not significantly different). Of these 101 subjects, 70 were treated with diet alone and 31 were treated with oral agents. After a mean (SD) follow-up period of 2.38 (0.63) years, there was an 18.5% increase in the fibrinogen concentration from 3.53 (1.06) g/L at baseline to 3.97 (1.07) g/L at follow-up (P < 0.001). The normal subjects had a mean (SD) follow-up period of 1.17 (0.38) years, and showed no significant change in their fibrinogen concentrations from 3.49 (0.90) g/L at baseline to 3.15 (0.61) g/L at follow-up. In the 101 diabetic subjects, only changes in plasma triglyceride correlated with the changes in fibrinogen concentration. Using multivariate analysis with age, sex, duration of diabetes, baseline and changes in body mass index, blood pressure, glycaemic and lipid parameters as independent variables (R2 = 0.106, F= 6.840, P = 0.011), triglyceride (beta = 0.282, P = 0.011) was identified as the only independent variable that predicted the changes in the fibrinogen concentrations. Improved glycaemic control was not accompanied by a reduction in plasma fibrinogen concentration.

Adult↗
PubMed2000

Diabetes insipidus.

Explore the source record for details and available documents.

Deamino Arginine Vasopressin↗
PubMed2000

Combined use of fasting plasma glucose and HbA1c predicts the progression to diabetes in Chinese subjects.

OBJECTIVE: We have previously suggested using the paired values of fasting plasma glucose (FPG) and HbA1c to identify potential diabetic subjects. In this article, we followed up on 208 nondiabetic subjects and examined their rates of progression to diabetes. We analyzed their likelihood of becoming diabetic according to their baseline FPG and HbA1c concentrations. RESEARCH DESIGN AND METHODS: Between 1988 and 1995, 2,877 Chinese subjects with risk factors for diabetes underwent screening. Of these, 2,250 had FPG <7.8 mmol/l and 2-h plasma glucose (PG) <11.1 mmol/l. Of these 2,250 subjects, 265 were randomly recruited for an annual oral glucose tolerance test (OGTT) until they progressed to develop diabetes. Of those 265 subjects, 57 had baseline FPG > or =7.0 mmol/l and were excluded from the present analysis. Hence, the progression of glucose tolerance in 208 subjects who were nondiabetic according to the new American Diabetes Association diagnostic criteria (FPG < 7.0 mmol/l and 2-h PG < 11.1 mmol/l) was examined RESULTS: Of the 208 nondiabetic subjects, 26 (12.5%) were men and 182 (87.5%) were women. After a mean follow-up of 1.60 +/- 1.16 years (range 1-7, median 1), 44 (21.2%) progressed to develop diabetes and 164 (78.8%) remained nondiabetic. Those who were diabetic at the end of the study had a high likelihood ratio (LR) of 9.3 to have baseline FPG > or =6.1 mmol/l and baseline HbA1c > or =6.1%. This was compared with a low LR of 0.6-1.1 in diabetic subjects who had either FPG <6.1 mmol/l or HbA1c <6.1% or both at baseline. The crude rate of progression to diabetes was more than five times higher (44.1 vs. 8.1%) in those whose baseline FPG was > or =6.1 mmol/l and baseline HbA1c was > or =6.1% compared with those whose baseline FPG was <6.1 mmol/l and baseline HbA1c was <6.1%. CONCLUSIONS: For Chinese subjects with risk factors for glucose intolerance, the use of paired FPG and HbA1c values helped to identify potential diabetic subjects. Those with an FPG > or =6.1 mmol/l and HbA1c > or =6.1% had a rate of progression to diabetes more than five times higher than those with an FPG <6.1 mmol/l and an HbA1c <6.1% after a mean follow-up of 1.6 years. Those with an FPG > or =6.1 but <7.0 mmol/l, especially if their HbA1c was > or =6.1%, should undergo an OGTT to confirm diabetes. Subjects with an FPG <6.1 mmol/l and/or an HbA1c <6.1% should have regular screening using the paired values of FPG and HbA1c.

Adult↗
PubMed2000

Outcomes of screening for diabetes in high-risk Hong Kong Chinese subjects.

OBJECTIVE: To examine the significance of individual risk factors on the development of diabetes in subjects who underwent screening for diabetes. RESEARCH DESIGN AND METHODS: A total of 1,649 Chinese subjects underwent screening for diabetes. They were asymptomatic but had known risk factors for diabetes, including a positive family history of diabetes, a past history of gestational diabetes, obesity, hypertension, and/or dyslipidemia. Another 799 age-matched subjects from the community who had no risk factors for diabetes were used as the comparison group. RESULTS: Of the 1,649 subjects who underwent screening, 241 (14.6%) had diabetes. In these subjects, 989 (60.0%) had 1 risk factor, 502 (30.4%) had 2 risk factors, 141 (8.6%) had 3 risk factors, and 17 (1.0%) had 4 or 5 risk factors for diabetes. Of the 799 control subjects, 29 (3.6%) had diabetes. Compared with the comparison group, the odds ratio (95% CI) of having diabetes after adjustment for age was 5.2 (3.5-7.7) in the 1,649 subjects with known risk factors. The odds ratio of having diabetes increased from 3.7 in subjects with 1 risk factor to 28.4 in subjects with 4 or 5 risk factors. CONCLUSIONS: In men, age, BMI, family history of diabetes, and dyslipidemia, and in women, age, BMI, hypertension, dyslipidemia, total cholesterol, and history of gestational diabetes are associated with increased odds of developing diabetes. These risk factors have additive effects on the odds of having diabetes. Early and regular screening for diabetes and other cardiovascular risk factors is essential in these high-risk individuals.

Adult↗
PubMed2000

Diabetes in Hong Kong Chinese: evidence for familial clustering and parental effects.

OBJECTIVE: To investigate transmission patterns of diabetes and their relationships with clinical characteristics in Hong Kong Chinese patients with late-onset (age > or =35 years) type 2 diabetes. RESEARCH DESIGN AND METHODS: This study involved 2,310 patients consecutively selected from a hospital clinic-based diabetes registry. These patients all reported the diabetes status of their parents as well as siblings. RESULTS: Approximately 36% of the 2,310 patients reported at least 1 affected parent or sibling (25 and 21% reported at least 1 diabetic parent and sibling, respectively). These patients, irrespective of their sex, were more likely to have a diabetic mother than a diabetic father (17 vs. 13% of the male patients and 18 vs. 9% of the female patients, P<0.01). The male patients were more likely than the female patients to have a diabetic father (13 vs. 9%, P<0.01). The female patients with a diabetic mother were found to have higher levels of plasma total cholesterol compared with the female patients with a diabetic father in multiple comparisons with adjustment for significance (5.56+/-1.30 vs. 5.09+/-0.95 mmol/l, P<0.05). In 2-group comparisons, there was also evidence that the male patients with a diabetic father had higher BMI values than the male patients with a diabetic mother (25.9+/-3.5 vs. 25.0+/-3.5 kg/m2, P<0.05). CONCLUSIONS: We found familial clustering of diabetes in the Hong Kong Chinese population as well as a significant maternal influence and a male sex-specific paternal effect. We suggest that both maternal and paternal factors may be implicated in the development of type 2 diabetes in the Chinese population.

Adult↗
PubMed2000

Absence of microsatellite instability in primary myelodysplastic syndrome.

Using polymerase chain reaction (PCR), we examined a panel of 10 microsatellite markers (BAT26, BAT40, D2S123, D4S171, D8S87, D10S197, D12S89, Tp53, D18S58, PLCpr) covering nine chromosomal arms for microsatellite instability (MSI) in 29 patients with primary MDS. Bone marrow DNA was compared with corresponding constitutional DNA derived from buccal epithelial cells. Apart from BAT26 and BAT40 that were mononucleotide (poly A) repeats, the others were dinucleotide (CA) repeats. The patients comprised 10 cases of refractory anemia (RA), three cases of refractory anemia with ringed sideroblasts (RARS), nine cases of refractory anemia with excess of blasts (RAEB), four cases of refractory anemia with excess of blasts in transformation (RAEBt), and three cases of chronic myelomonocytic leukemia (CMML). Serial samples were available in seven patients, in which four showed transformation into higher disease grade or acute myeloid leukemia (AML). Genetic alterations at one locus (three at D2S123, one at D4S171) were evident in four cases, and loss of heterozygosity at Tp53 was detected in one case. Accordingly, none of the 29 patients with primary MDS nor the seven with disease progression in this study exhibited MSI. This shows that MSI may not be important in the pathogenesis or progression of MDS in contrast to other genetic mechanisms, notably recurrent chromosomal abnormalities that dysregulate the expression or function of genes controlling cell growth, differentiation and apoptosis.

Aged↗
PubMed2000

Diphenyleneiodium chloride blocks inflammatory cytokine-induced up-regulation of group IIA phospholipase A(2) in rat mesangial cells.

Inflammatory cytokines, interleukin 1beta and tumor necrosis factor-alpha, potently stimulate rat mesangial cells to express and secrete group IIA phospholipase A(2) (PLA(2)). Cytokine-induced up-regulation of PLA(2) has been blocked by inhibitors (antioxidants) of the transcription factor, nuclear factor-kappaB (NF-kappaB), suggesting a role for NF-kappaB in the regulation of group IIA PLA(2) expression. Reactive oxygen species such as H(2)O(2), which are elevated in mesangial cells after cytokine activation, can mimic cytokine-induced NF-kappaB activation. However, the source of reactive oxygen species generation in mesangial cells, produced by cytokine stimulation, has yet to be clarified. Recently, tumor necrosis factor-alpha has been demonstrated to increase superoxide radical generation in mesangial cells. Therefore, we hypothesized that a selective NADPH oxidase inhibitor, diphenyleneiodium chloride (DPI), could block cytokine-induced group IIA PLA(2) up-regulation by attenuating NF-kappaB binding. To test this hypothesis, we isolated rat mesangial cells and characterized them by ultrastructural and immunochemical methods. This homogeneous mesangial cell population was responsive to cytokine as evidenced by an increase in steady-state levels of group IIA PLA(2) mRNA and extracellular enzymatic activity over time. DPI (0.02-20 microM), added 90 min before cytokine activation, inhibited both group IIA PLA(2) mRNA and enzymatic activity in a concentration-dependent manner. By electrophoretic mobility shift analysis, cytokine activation also increased specific NF-kappaB binding to one of two NF-kappaB consensus elements in the rat group IIA PLA(2) promoter and also was suppressed by DPI pretreatment. Antibodies to NF-kappaB p65 (Rel A) and p50 (but not normal rabbit IgG) supershifted this retardation signal and verified the type of NF-kappaB species as the classical p50/p65 heterodimer.

Animals↗
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↗
PubMed2000

Genetics of type 2 diabetes mellitus.

Type 2 diabetes mellitus is a heterogeneous disease that is caused by both genetic and environmental factors. Only a minority of cases of type 2 diabetes are caused by a single-gene defect, such as maturity-onset diabetes of youth (mutated MODY gene), syndrome of insulin resistance (insulin receptor defect), and maternally inherited diabetes and deafness (mitochondrial gene defect). The genetic component of the more common form of type 2 diabetes is probably complex and involves the interactions of multiple genes and environmental factors. The candidate gene approach has identified several genes that regulate insulin signalling and secretion, but their contributions to diabetes are small. Recent genome scan studies have been conducted to identify major susceptibility loci that are linked with type 2 diabetes. This information would provide new insights into the identification of novel genes and pathways that lead to this complex disease.

Amyloid↗
PubMed2000

Heterogeneity of diabetes mellitus in the Hong Kong Chinese population. The Chinese University of Hong Kong-Prince of Wales Hospital Diabetes Research and Care Group.

Diabetes mellitus is a massive public health problem that has major socio-economic implications. There are now local and international data that confirm the high prevalence of diabetes in Chinese populations living in affluent societies such as Hong Kong. The heterogeneity of diabetes mellitus, especially among patients with a young onset of the disease, is being increasingly recognised. Genetic factors appear to be a particularly important factor in these young diabetic patients, who face a long duration of disease. Understanding the pathogenesis and genetic basis of diabetes mellitus and its complications are of fundamental importance to improving the diagnosis and treatment of this heterogeneous disease. Despite its complications, diabetes mellitus is a very treatable and preventable disease. The challenge lies in the effective delivery of quality and affordable care to high-risk individuals. To this end, these concerted efforts among academics, clinicians, scientists, health care professionals, administrators, and policy makers are required to defuse this health care time bomb.

Adult↗