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Biomedical subjects

C W Lam

Publications and source records attributed to C W Lam.

At least 109 records · Page 6Linked to original sources
PubMed1998

Body fatness and serum lipids of 11-year-old Chinese children.

It has been suggested that distribution of body fat has a stronger bearing on health risk than total body fat. Magnetic resonance imaging (MRI) was used to examine the distribution of fat and correlated with body fat assessed by the usual clinical methods-weight, weight-for-height, body mass index (BMI), triceps and subscapular skinfold thickness in 11-y-old Chinese children. Lipid profiles were used as indicators for coronary risk. Eighty-eight subjects had body fat distribution estimated by MRI, while 49 had serum lipids measured. Anthropometric parameters correlated significantly with total fat at the umbilical level measured by MRI (weight: r = 0.90 in boys, 0.75 in girls; BMI: r = 0.94 in boys, 0.87 in girls; percent median weight-for-height: r = 0.90 in boys, 0.79 in girls, triceps skinfold thickness: r = 0.89 in boys, 0.90 in girls; subscapular skinfold thickness: r = 0.93 in boys, 0.88 in girls). Obese subjects had proportionally less visceral fat than subcutaneous fat at umbilical level. Using stepwise multiple regression, predictive factors for high-density lipoprotein cholesterol were BMI in boys and breast-staging in girls. For triglycerides, it was genital staging in boys and for total cholesterol, it was breast-staging in girls. Visceral fat was not a significant determinant of serum lipids.

Adipose Tissue↗
PubMed1998

Glucose-6-phosphatase gene (727G-->T) splicing mutation is prevalent in Hong Kong Chinese patients with glycogen storage disease type 1a.

Glycogen storage disease type la (GSD1a) is an autosomal recessive metabolic disorder caused by a deficiency in glucose-6-phosphatase (G6Pase). We analyzed the G6Pase genes of two unrelated Chinese families with GSD1a. DNA sequencing of all five exons and the exon-intron boundaries revealed a G T transversion at nucleotide 727 (727G-->T) in exon 5, which has previously been reported to cause abnormal splicing. In one family, the subject and her affected sister were confirmed to be homozygous for this mutation and their parents to be heterozygotes. In the other family, the proband was identified to be heterozygous for this mutation, and a novel mutation, the 341delG in exon 2, was identified. This mutation alters the reading frame and creates a stop codon TAA 15 codons downstream from the mutation, resulting in a truncated protein. Family studies revealed that the father was heterozygous for the 727G-->T mutation and that the mother was heterozygous for the 341delG mutation. This is the first time that the 727G T mutation has been found in Chinese patients or outside Japan. Since we only tested two GSD1a families and found 727G-->T in both, we believe that this mutation may also be prevalent in our local Chinese population. To investigate allele frequencies, we screened 385 Chinese healthy volunteers and found two asymptomatic carriers. Our findings suggest that the 727G-->T mutation is indeed prevalent in Hong Kong.

Base Sequence↗
PubMed1998

The effect of dentine surface treatment on pulpward pressure transmission during crown cementation: a laboratory study.

Thirty extracted human premolars received standardised full crown preparations. The teeth were randomly assigned into three groups: smeared (control), etched (phosphoric acid gel), and bonded (Scotchbond MP). Each tooth was perfused with saline to establish perfusion rates at baseline for all groups, and the post-etching stage for etched and bonded groups, post-bonding stage for bonded group, and post-cementation stage for all groups. Crowns made with four layers of die-spacing were cemented with zinc phosphate cement at 100N. Pulpal pressures were measured with a pressure transducer. It was concluded that dentine bonding agents may have the potential to reduce pulpal damage caused by pressure transmission from cementation.

Acid Etching, Dental↗
PubMed1998

A simple assessment of peritoneal transport in stable continuous ambulatory peritoneal dialysis patients.

We studied the peritoneal transport properties in 175 stable continuous ambulatory peritoneal dialysis (CAPD) patients seeking a simple and handy assessment of peritoneal permeability to small solutes. Measurement of creatinine in biological fluid was known to suffer from interference by high glucose concentration in the sample. Furthermore, the interference is also affected by the creatinine concentration of the specimen. Peritoneal transport properties were studied by determining the dialysate to plasma ratio of creatinine concentration (D/P) at the fourth hour of the peritoneal equilibration test, and the mass transfer area coefficient of creatinine (MTACCr) or glucose (MTACGlu). The ratio of glucose concentration in peritoneal dialysate effluent (PDE) at 4 and 0 h (G4/G0) was examined and compared with various peritoneal parameters. There were significant logarithmic correlations between D/P or G4/G0 with MTACCr (r=0.96 and 0.79, respectively, p < 0.0001). The correlation between G4/G0 and D/P was linear (r=-0.82, p < 0.0001). A fairly good agreement was present between G4/G0 and D/P by Bland and Altman's method. The bias was -0.93% with 95% confidence interval -23.29% to 21.43% of the measured value. Systematic error was found when D/P or G4/G0 were compared with MTACCr. D/P under estimated MTACCr in the high range. The reverse happened for G4/G0. Net ultrafiltration (NUF) also correlated with MTACCr, D/P and G4/G0 (r=-0.32, p < 0.001; -0.26, p < 0.01; and 0.16, p < 0.05, respectively. In conclusion, the use of G4/G0 as a measure of peritoneal transport in CAPD is an acceptable alternative to D/P. It is highly reproducible and avoids correction of interference when creatinine transport parameters are measured. Because of the logarithmic relations of G4/G0 (or D/P) with MTACCr, the former should not be directly converted to MTACCr. Such a simple measure of peritoneal permeability is, however, most convenient for serial monitoring and can be useful to detect early loss of ultrafiltration or solute clearance.

Creatinine↗
PubMed1998

Rifapentine and isoniazid in the continuation phase of treating pulmonary tuberculosis. Initial report.

A randomized comparison has been made of three times weekly rifampin plus isoniazid (HR3) with rifapentine plus isoniazid given once weekly (HRp1) or on 2 of 3 wk (HRp1.2/3) in the continuation phase of 6-mo regimens (each starting with an initial 2 mo of 4-drug therapy) for the treatment of pulmonary tuberculosis in 672 Chinese patients in Hong Kong. Because of poor bioavailability of the rifapentine used (produced in China), its dose size was increased from 600 mg initially to about 750 mg in the last third of patients to obtain serum concentrations similar to those with rifapentine of Western origin; all doses were given after a meal promoting absorption. After initial exclusions, an intent to treat analysis, done on the remaining 592 patients, showed 45 adverse treatment events in 7 of 190 HR3 patients, in 17 of 199 HRp1 patients, and in 21 of 203 HRp1.2/3 patients; of these, 42 were bacteriological or radiographic relapses after the end of treatment (HR3 versus HRp1, p = 0.04; HR3 versus HRp1.2/3, p = 0.01). Patients with organisms initially sensitive or resistant to isoniazid or streptomycin had similar relapse rates. The high relapse rate in the HRp1 regimen suggests that the rifapentine dose should be increased. Similarity of relapse rates, 8.9% and 10.4%, after the HRp1 and HRp1.2/3 regimens, respectively, indicates that irregularity in taking rifapentine/isoniazid could be tolerated. The few adverse side effects in the continuation phase in the rifapentine regimens were less frequent than in the HR3 regimen.

Adolescent↗
PubMed1998

Pleural fluid pseudouridine in malignant and benign pleural effusions.

Pseudouridine in urine and plasma has been proved to be a useful tumour marker in many malignant conditions. We studied its usefulness in pleural fluid for distinguishing malignant from non-malignant pleural effusions. Pleural fluid pseudouridine concentrations in different groups of patients with pleural effusion (31 malignant, 29 benign, 16 unknown, 1 double pathology) was measured and compared. Its usefulness in distinguishing malignant from non-malignant pleural effusions was analysed by receiver-operating characteristic (ROC) curve analysis. Pseudouridine concentrations in the malignant group were significantly higher than the non-malignant group (P < 0.017, Bonferroni adjustment) with values overlapping extensively at the lower end. The area-under-the curve (AUC) value in the ROC curve analysis was 0.675 (P < 0.05). We conclude that the pleural fluid pseudouridine is of limited clinical value in distinguishing malignant from non-malignant pleural effusion due to its extensive overlap. However, it is useful when the concentration is higher than 65 mumol/L, which indicates malignancy.

Area Under Curve↗
PubMed1998

Pituitary-adrenal suppression in preterm, very low birth weight infants after inhaled fluticasone propionate treatment.

Systemic corticosteroids prescribed for treatment of pulmonary diseases in preterm, very low birth weight infants caused severe suppression of the hypothalamic-pituitary-adrenal axis and produced serious physiological and metabolic disturbances. However, the effect of inhaled corticosteroids on their pituitary-adrenal functions is not known. We prospectively evaluate the pituitary-adrenal function using the human CRH stimulation test in a cohort of very low birth weight infants at risk for hypothalamic-pituitary-adrenal axis suppression in a double blind, randomized pilot study designed for assessing the efficacy and adverse effects of inhaled fluticasone propionate in newborn preterm infants who required mechanical ventilation for treatment of respiratory distress syndrome. Twenty-five preterm (< 32 gestational weeks), very low birth weight (< 1500 g) infants were randomized to receive inhaled fluticasone propionate (n = 13) or a placebo inhaler (n = 12). The medication was given every 12 h (fluticasone propionate, 1,000 micrograms/day) for 14 days. All surviving infants had their pituitary-adrenal functions assessed by human CRH test on the following morning immediately after completion of the 2-week course. All basal (0 min) and post-stimulation (15, 30, and 60 min) plasma ACTH and serum cortisol concentrations were significantly suppressed in the inhaled fluticasone group compared to their corresponding levels in the placebo group [basal plasma ACTH concentrations (F = 6.0; P = 0.02), poststimulation plasma ACTH concentrations (F > 8.6; P < 0.01), basal serum cortisol concentrations (F = 5.6; P = 0.03), and poststimulation serum cortisol concentrations (F > 15.6; P < 0.001)]. This is the first study in very low birth weight infants that demonstrates unequivocally that cumulative high dose inhaled corticosteroids can induce moderately severe suppression of both the pituitary and adrenal glands. The systemic bioactivity is probably associated with pulmonary vascular absorption, which effectively circumvents the hepatic first pass metabolism. Until the question of safety can be adequately addressed, inhaled fluticasone propionate should be used with cautionin preterm infants.

Administration, Inhalation↗
PubMed1998

Acute effects of a surgical menopause on serum concentrations of lipoprotein(a).

OBJECTIVE: The aim of this study was to investigate acute changes in serum concentrations of lipoprotein(a) and other atherogenic lipids and lipoproteins after a surgical menopause. METHODS: A total of 100 premenopausal Chinese women who were booked for hysterectomy for benign gynecological disorders were recruited. They study group comprised 40 subjects undergoing hysterectomy as well as bilateral oophorectomy. The control group consisted of 60 subjects undergoing hysterectomy with conservation of the ovaries. Complete data were available from 30 of the 40 subjects in the study group and from 44 of the 60 controls. Serum concentrations of lipoprotein(a) and other atherogenic lipids and lipoproteins were measured before surgery and these measurements were repeated 3 days, 8 weeks and 6 months postoperatively. Those study patients who received hormone replacement therapy and control patients who became menopausal, according to biochemical criteria, during the study period were excluded from analysis. RESULTS: Three days after surgery, there was a significant increase in the mean lipoprotein(a) concentration in the control group from 19.1 to 23.0 mg/dl (p < 0.01), but there was no significant change in the study group. There were no significant changes from baseline in the mean lipoprotein(a) concentration in either group 8 weeks or 6 months after surgery. There was a significant increase in the mean concentration of total cholesterol in the study group 8 weeks after surgery from 5.08 to 5.45 mmol/l (p < 0.01), in low density lipoprotein cholesterol from 3.22 to 3.49 mmol/l (p < 0.01), and in apolipoprotein B from 95.6 to 103.0 mg/dl (p < 0.05). However, the mean concentrations 6 months after surgery were not significantly different from baseline levels. The mean concentrations of high density lipoprotein cholesterol, apolipoprotein A-1 and triglycerides also did not differ significantly from baseline in the study group, either 8 weeks or 6 months after surgery. CONCLUSIONS: These results suggest that any increase in concentrations of lipoprotein(a), and other atherogenic lipids and lipoproteins which occur after the menopause, develops relatively slowly. The changes in concentrations which occurred within 8 weeks of surgery were probably an acute-phase reaction after surgery rather than a response to a decreasing estradiol concentration.

Adult↗
PubMed1998

Penicillium marneffei infection and solitary pulmonary nodule.

We report on a patient infected with human immunodeficiency virus who presented with fever, a solitary pulmonary nodule, and cervical lymphadenopathy. The diagnosis of Penicillium marneffei infection was made from an excisional lymph node biopsy and a sputum culture. The microbiology, pathology, diagnosis, and treatment of the case are discussed. A high level of clinical suspicion is necessary for making an early diagnosis and improving the outcome of infection.

Journal Article↗
PubMed1998

Bilevel positive airway pressure nasal mask ventilation in patients with acute hypercapnic respiratory failure.

The efficacy and complications of bilevel positive airway pressure nasal mask ventilation for 22 patients with acute hypercapnic respiratory failure were reviewed retrospectively. The median patient age was 73 years (range, 57-92 years). The most common primary diagnosis (77%) was chronic obstructive pulmonary disease. The median duration of ventilation was 72.0 hours (range, 0.9 hours to 35 days). Within a median of 12 hours (range, 1-24 hours) after the initiation of therapy, there were significant improvements in the arterial oxygen and carbon dioxide tensions, oxygenation ratio, and arterial-alveolar ratio. Fourteen patients (64%) were treated successfully. Success with therapy was associated with a lower Acute Physiology and Chronic Health Evaluation score, a higher arterial oxygen tension, higher oxygenation and arterial-alveolar ratios, and lower respiratory and pulse rates. Complications were uncommon. We conclude that bilevel positive airway pressure nasal mask ventilation can be useful for patients with acute hypercapnic respiratory failure but who are otherwise clinically stable.

Journal Article↗
PubMed1997

Biochemical investigation of young hospitalized Chinese children: results over a 7-year period.

During the seven years from January 1989 to December 1995, we investigated 2,269 Chinese infants and young children for metabolic disorders in Hong Kong. These young patients, all aged under 4 years and originated from southern China, were ill with no apparent cause and had clinical manifestations suggestive of inherited metabolic diseases. A spot urine and a plasma sample were obtained from each patient for biochemical analysis, including urinary organic acid identification and plasma amino acid analysis. Six cases of mucopolysaccharidosis, four multiple carboxylase deficiency, three 2-methylacetoacetyl CoA thiolase deficiency, two methymalonic aciduria, one glutaric aciduria type I, one glutaric aciduria type II, one a-oxoglutaric aciduria, and one case of orotic aciduria were detected. There were also single suspected cases of medium-chain acyl-CoA dehydrogenase deficiency and isovaleric aciduria. No primary amino acid disorder, such as phenylketouria and maple syrup urine disease, has been detected. Our results suggest that a different pattern of inherited metabolic diseases exists in the southern Chinese when compared with the Chinese in other regions of China.

Child, Preschool↗
PubMed1997

Differences in the effect of cigarette smoking on endothelial function in chinese and white adults.

BACKGROUND: The prevalence of coronary artery disease in southern China is approximately one fifth that in "westernized" countries, even though approximately 70% of Chinese men smoke cigarettes and Chinese women have substantial passive exposure to cigarette smoke. OBJECTIVES: Endothelial dysfunction is an early event in atherosclerosis and occurs in young white active and passive smokers; we compared endothelial physiology in healthy young Chinese and white smokers and nonsmokers. PATIENTS: 144 healthy adults who were 16 to 45 years of age: 72 Chinese persons in a village in southern China and 72 white persons in Australia and England who were matched for exposure to cigarette smoke. Each ethnic group comprised 36 controls (lifelong nonsmokers with no regular exposure to cigarette smoke; 16 men and 20 women) and 36 active or passive smokers (15 men and 21 women). MEASUREMENTS: Arterial endothelial function was tested with high-resolution external vascular ultrasonography, and brachial artery diameter was measured at rest, after flow increase (which causes endothelium-dependent dilatation), and after administration of sublingual nitroglycerin (an endothelium-independent dilator). RESULTS: Endothelium-dependent dilatation was similar in Chinese (7.9%) and white (8.4%) nonsmokers (P > 0.2). Among white persons, endothelium-dependent dilatation was lower in active or passive smokers (3.9%) than in nonsmokers (8.4%) (P < 0.001). Among Chinese persons, dilatation was not significantly lower in active or passive smokers (7.3%) than in nonsmokers (7.9%) (P > 0.2). Dilatation was higher in Chinese active or passive smokers (7.3%) than in white active or passive smokers (3.9%) (P < 0.001). Dilatation responses to nitroglycerin were similar in all groups (P = 0.17). CONCLUSION: Young Chinese adults have less evidence of arterial endothelial dysfunction than young white adults with similar direct or indirect exposure to cigarette smoke.

Adolescent↗
PubMed1997

Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) triggered by valproate therapy.

UNLABELLED: We report in this study a patient who developed repeated convulsions as a result of valproate therapy. MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) was subsequently diagnosed and a nucleotide 3243 A-->G mutation was detected in the mitochondrial DNA. This mutation predisposes the patient to the detrimental effects of valproate on oxidative phosphorylation. CONCLUSION: We support the suggestion of Ponchaut et al. [14] that valproate should not be given to patients suspected of having mitochondrial diseases. In addition, for patients whose seizures worsen with valproate therapy, an inborn error of mitochondrial metabolism should be suspected. The underlying mitochondrial DNA defects should be sought for family screening and genetic counselling.

Anticonvulsants↗
PubMed1997

Plasma total antioxidant capacity in an adult Hong Kong Chinese population.

OBJECTIVES: To examine plasma total antioxidant capacity (TAOC) in a Chinese population with a lower incidence of cardiovascular disease compared with Caucasian populations, in relation to dietary intake, age, sex, and the presence of cardiovascular diseases. DESIGN AND METHODS: As part of a randomized territory-wide survey stratified by sex and 10-year age groups; 728 subjects (367 men, 361 women) were recruited. Dietary intake assessment was by a food frequency questionnaire; plasma TAOC was estimated by the ABTS method. RESULTS: The TAOC values were normally distributed, the mean +/- SD being 1.78 +/- 0.18 mmol/L. The mean value was higher in men compared with women, inspite of a lower dietary intake of vitamins A and C per 1000 kcal in the former. Subjects who consumed water spinach twice or more a week had higher mean levels. No difference in mean levels was observed between those with and without hypertension or cardiovascular disease. CONCLUSION: Measurement of plasma TAOC as a risk factor in epidemiological studies of cardiovascular diseases may have limited use, since TAOC include substances associated with a protective effect as well as increased risk.

Adult↗
PubMed1997

Changes in atherogenic lipids and lipoproteins during natural and hyperstimulated cycles in healthy women.

OBJECTIVE: To compare changes in the concentrations of Lp(a) lipoprotein and other atherogenic lipids and lipoproteins in natural and hyperstimulated ovarian cycles. DESIGN: Open, prospective study. SETTING: Academic department in a teaching hospital. PATIENT(S): Normal ovulatory women served as controls and the treatment group consisted of women undergoing ovarian hyperstimulation. INTERVENTION(S): The treatment group received hMG on a fixed regimen. MAIN OUTCOME MEASURE(S): Measurements of serum lipids and lipoproteins were made in both natural and hyperstimulated cycles. RESULT(S): There was a significant increase in the median concentration of Lp(a) lipoprotein from 10.1 to 10.7 mg/dL in the luteal compared with the proliferative phase of unstimulated cycles. In hyperstimulated cycles, there was a significant increase in the median concentration of Lp(a) lipoprotein from 9.7 mg/dL in the proliferative phase to 11.3 mg/dL in the luteal phase. Reductions in concentrations of total cholesterol and low-density lipoprotein cholesterol were found in the luteal phase of hyperstimulated cycles. CONCLUSION: Concentrations of Lp(a) lipoprotein increase during the luteal phase of both natural and hyperstimulated ovarian cycles.

Adult↗
PubMed1997

Sensitization to inhaled allergens as a risk factor for asthma and allergic diseases in Chinese population.

BACKGROUND: Allergen sensitization is associated with asthma and allergic disease in children, but such a relationship has not been confirmed in Chinese populations. OBJECTIVES: The objective of this study was to evaluate the effects of allergen sensitization and family history of atopy on asthma and allergic disease in Chinese schoolchildren from three southeast Asian populations. METHODS: Written questionnaires on respiratory and allergic symptoms were completed by parents of children of secondary-school age (age range 12 to 18 years) in Hong Kong (n = 1062), Kota Kinabalu in eastern Malaysia (n = 409), and San Bu in southern China (n = 737). A subsample of school-children underwent skin prick testing to common inhalant allergens (Hong Kong 471 children, Kota Kinabalu 321, San Bu 647). RESULTS: The prevalence of asthma and allergic disease in schoolchildren was highest in Hong Kong, intermediate in Kota Kinabalu, and lowest in San Bu. However, the overall rate of atopic sensitization was similar in the three populations (49% to 63%). House dust mite and cockroach were the two most common allergens causing sensitization and these gave rise to more than 95% of the positive skin test results in all three populations. By regression analysis, mite allergy was associated with rhinitis and asthma in all three populations, and a family history of asthma, rhinitis, or eczema was strongly associated with respective symptoms in the subjects. After adjusting for age, sex, atopic status, and family history of allergic disease, the place of residence remained a significant independent factor for asthma (odds ratio [OR] = 1.0 for Hong Kong, 0.57 for Kota Kinabalu, 0.15 for San Bu, p < 0.001), rhinitis (OR = 1.0 for Hong Kong, 0.59 for Kota Kinabalu, 0.15 for San Bu, p < 0.001), or eczema (OR = 1.0 for Hong Kong, 0.35 for Kota Kinabalu, 1.01 for San Bu, p < 0.001). CONCLUSION: Sensitization to indoor allergens was a significant risk factor for asthma and allergic disease, and familial clustering of disease was common in the region. However, the marked difference in disease prevalence in the three southeast Asian populations of Chinese schoolchildren cannot be explained by atopic sensitization and family history alone, and the place of residence was an independent risk factor for asthma and allergies, which suggests an important environmental role in disease pathogenesis.

Adolescent↗