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Biomedical subjects

C K Cheung

Publications and source records attributed to C K Cheung.

At least 37 records · Page 2Linked to original sources
PubMed1995

Factors determining the blood pressure response to enalapril and nifedipine in hypertension associated with NIDDM.

OBJECTIVE: To examine the factors that determine the blood pressure response to enalapril and nifedipine monotherapy in the treatment of hypertension associated with non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS: After a 6-week placebo baseline period, 102 hypertensive NIDDM patients were randomly assigned, double-blindly, to treatment with nifedipine retard (slow release) (n = 52) or enalapril (n = 50). The daily dosage of enalapril was increased, if required, from 10 to 20 to 40 mg and that of nifedipine from 40 to 60 to 80 mg at 4-week intervals during the 12-week titration period. Blood pressure, 24-h urinary albumin excretion (UAE), biochemical data, and serum angiotensin-converting enzyme (ACE) activity were measured at weeks -6, -4, 0, 4, 8, and 12. At week 0, venous blood was also sampled for baseline plasma atrial natriuretic peptide, renin, aldosterone, and serum insulin concentrations. RESULTS: At week 12, the mean daily dose of enalapril was 35 +/- 11.4 mg, and 27 (57%) patients were receiving the maximum daily dose of 40 mg. In the nifedipine group, the mean daily drug dose was 50 +/- 12.9 mg, and 4 (8%) were receiving the maximum daily dose of 80 mg. Despite a dose-dependent fall in the serum ACE activity in the enalapril group, the mean arterial pressure (MAP) was reduced by only 8 mmHg throughout the 12-week titration period compared to a decline of 15, 18, and 19 mmHg at weeks 0, 4, and 12, respectively, in the nifedipine group (P = 0.01 between groups). In the enalapril group, changes in MAP between weeks 0 and 12 correlated significantly with baseline plasma glucose (r = 0.45, P = 0.001) and aldosterone concentrations (r = -0.32, P = 0.02) and UAE (r = 0.3, P = 0.04). There was no statistically significant correlation between the changes in MAP and baseline plasma renin concentration. On multivariate analysis, the baseline renal function, glycemic control, and plasma aldosterone and serum insulin concentrations were all independently related to the changes in blood pressure in the enalapril-treated patients. No such statistical associations were observed in the nifedipine group. CONCLUSIONS: In hypertensive NIDDM patients, the activity of the renin-angiotensin-aldosterone system, the level of serum insulin, glycemic control, renal function, and proteinuria may be important determinants of the blood pressure response to ACE inhibition. Good glycemic control may optimize the antihypertensive efficacy of concomitant ACE inhibitor therapy.

Albuminuria↗
PubMed1995

Abnormal albuminuria as a predictor of mortality and renal impairment in Chinese patients with NIDDM.

OBJECTIVE: Microalbuminuria predicts mortality in non-insulin-dependent diabetes mellitus (NIDDM), but its association with deterioration of renal function remains more controversial than in insulin-dependent diabetes mellitus (IDDM). Using albumin-to-creatinine ratios (ACRs) in random spot urine samples is a convenient method for evaluating albuminuria. We studied prospectively the predictive values of albuminuria in NIDDM when assessed by this urine measurement. RESEARCH DESIGN AND METHODS: Between 1991 and 1992, we restudied the clinical and biochemical status of 403 Chinese NIDDM patients recruited in 1989 after a follow-up period of 26.6 +/- 3.2 months (mean +/- SD). Spot urine ACR was measured on two occasions and microalbuminuria was defined as a mean ACR between 5.6 and 38 mg/mmol. RESULTS: From the original cohort, 29 patients had died mostly because of cardiovascular events with or without renal failure. The overall relative risk of death in patients with abnormal albuminuria was 7.1 (P < 0.001) (microalbuminuria: 3.7, P = 0.04; macroalbuminuria: 11, P < 0.001). On multivariate analysis, the independent predictive factors for mortality were plasma creatinine (wald = 12.1, P < 0.001) and glucose concentrations (wald = 10.4, P < 0.001) in the normo- and microalbuminuric patients (n = 11) and age (wald = 4.4, P = 0.03) and plasma creatinine (wald = 8.2, P < 0.01) in the macroalbuminuric group (n = 18). In the survivors (n = 374), baseline spot urine ACR was independently associated with 2-year spot urine ACR in the normo- (P < 0.001), micro- (P < 0.01), and macroalbuminuric groups (P = 0.01). In addition, baseline spot urine ACR was independently related to 2-year plasma creatinine (P = 0.01) in the macroalbuminuric group. The rates of change of the reciprocal of plasma creatinine ( delta [Cr]-1) were -27.3 +/- 62.5, -43.4 +/- 68.6, and -108.8 +/- 98.81.mumol01.month-1 in the normo-, micro-, and macroalbuminuric groups, respectively (P < 0.001). The delta [Cr]-1 was independently and inversely related to the baseline spot urine ACR (P < 0.001) and 2-year systolic blood pressure (P < 0.001). CONCLUSIONS: Abnormal albuminuria as indicated by a random spot urine ACR > 5.6 mg/mmol predicts increased mortality and is associated with the progression of albuminuria and deterioration of renal function in Chinese NIDDM patients.

Aged↗
PubMed1995

Immunoassay of a tartrate-resistant acid phosphatase in serum.

A tartrate-resistant acid phosphatase (TRACP) was purified from cord plasma by use of cation-exchange chromatography (carboxymethyl Sepharose), gel-filtration chromatography (Sephacryl S-200), and preparative isoelectric focusing. After raising polyclonal antibodies to the purified TRACP in rabbit, we used the antiserum to develop an ELISA. The antiserum cross-reacted with an extract of bone, but not with extracts of spleen, erythrocytes, platelets, or osteoblasts or with prostatic acid phosphatase. With this ELISA we determined the concentration of serum TRACP in healthy men to be 197 (61-301) micrograms/L (median and range). Serum TRACP concentrations were significantly higher in children and postmenopausal women and in patients with chronic renal failure, hyperparathyroidism, or hyperthyroidism. Estrogen replacement therapy of postmenopausal women for 3-6.5 months decreased their serum TRACP concentration by 70%.

Acid Phosphatase↗
PubMed1994

Atrial natriuretic peptide and renin-angiotensin-aldosterone system in non-insulin-dependent diabetes mellitus.

A total of 78 Chinese patients with clinically uncomplicated non-insulin-dependent diabetes (NIDDM) who had plasma creatinine concentrations of < 150 mumol/l were studied. Antihypertensive treatment was discontinued for at least six weeks prior to measurements of routine biochemistry, proteinuria, plasma atrial natriuretic peptide (ANP) concentrations and components of the renin-angiotensin-aldosterone system (RAAS). BP was measured on three occasions during the six weeks period prior to these measurements. At the end of the six week period, a total of 33 patients had definite hypertension (supine BP > or = 160/95 mmHg). The hypertensive patients had significantly higher plasma sodium (mean +/- SD): 140.3 +/- 1.9 vs. 138.5 +/- 2.0 mmol/l, P < 0.001) and lower plasma potassium (3.8 +/- 0.5 vs. 4.2 +/- 0.5 mmol/l, P < 0.01) concentrations. These were associated with reduced plasma aldosterone (median (range): 297 (98-1145) vs. 448.5 (93-1330) pmol/l, P < 0.01) and renin concentrations (16.8 (7.4-71.8) vs. 23.5 (7.4-83.7) ng/l, P = 0.06). The hypertensive patients also had significantly higher plasma ANP concentrations (36.5 (20.5-125.1) vs. 23.2 (11.7-63.0) pg/ml, P < 0.001), serum angiotensin converting enzyme (ACE) activity (65 (26-140.9) vs. 47 (22-106) units/l, P < 0.001) and urinary albumin excretion (UAE) (35.4 (1.6-4800) vs. 7.8 (1.8-310.4) mg/day, P < 0.001). Glycaemic control and renal function were similar between the two groups. Mean arterial pressure (MAP) correlated positively with plasma ANP concentration (r = 0.53, P < 0.001) and serum ACE activity (r = 0.37, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Obesity, albuminuria and hypertension among Hong Kong Chinese with non-insulin-dependent diabetes mellitus (NIDDM).

A total of 412 Hong Kong Chinese diabetic patients were studied on at least two occasions 8-16 weeks apart. Although 28% were insulin-treated, only 3.6% had insulin-dependent diabetes (IDDM). In the remaining 397 patients with non-insulin-dependent diabetes (NIDDM), the mean (s.d.) body mass index (BMI) was 24.4 +/- 3.2 kg/m2 in females and 24.2 +/- 3.2 kg/m2 in males. Obesity was present in 17% of males (BMI > 27 kg/m2) and 40% of females (BMI > 25 kg/m2). Established hypertension was present in 49%. Abnormal albuminuria, defined as a mean urinary albumin/creatinine (UA/Cr) ratio greater than 5.4 mg/mmol based on two random spot urine samples, was present in 47%. On stepwise multiple regression analysis, UA/Cr ratio (R2 = 0.34, F = 65.4, P < 0.001) showed significant associations with systolic blood pressure (standardized regression coefficient beta = 0.40, P < 0.001), plasma creatinine concentration (beta = 0.27, P < 0.001) and glycosylated haemoglobin (beta = 0.20, P < 0.001). While the prevalence of hypertension increased with increasing severity of proteinuria, 40% of normoalbuminuric patients had hypertension. Among patients diagnosed before the age of 35 (n = 67), 52% were insulin-treated although only 10% were insulin-dependent. Among these NIDDM patients of young onset (n = 59), obesity was present in 25% of males and 56% of females. Overall, 18% of these patients had a blood pressure greater than 140/90 mmHg and 27% had abnormal albuminuria. In Hong Kong Chinese, diabetes mellitus is predominantly non-insulin-dependent even in the young. Obesity is more prevalent among females. Abnormal albuminuria is relatively common and is closely associated with hypertension and glycaemic control. In the light of increasing prevalence of diabetes among overseas Chinese, our findings may have important implications in the management of Chinese diabetic patients.

Adolescent↗
PubMed1993

Protein excretion after prolonged exercise.

Random urine samples were obtained from 16 healthy subjects (nine men and seven women) before and after a 100 Km hill walk for the estimation of total protein, albumin, N-acetyl-beta-glucosaminidase (NAG), retinol binding protein (RBP) and creatinine. The excretion of total protein, albumin and NAG (expressed in relation to creatinine excretion) increased significantly after the walk. The relative clearance of protein and albumin also increased. In four subjects serial measurements were made for 4 days and the excretion of albumin and NAG on the fourth day were similar to the pre-walk values. We conclude that proteinuria of prolonged exercise is at least partly due to reduced tubular reabsorption.

Acetylglucosaminidase↗
PubMed1992

Comparison of enalapril and nifedipine in treating non-insulin dependent diabetes associated with hypertension: one year analysis.

OBJECTIVES: To compare the efficacy, safety, and tolerance of enalapril and nifedipine in hypertensive patients with non-insulin dependent diabetes. DESIGN: One year double blind follow up of patients randomly allocated to either enalapril or nifedipine with matching placebos for the alternative drug. SETTING: Metabolic Investigation Unit, Hong Kong. SUBJECTS: 102 patients were randomised: 52 to nifedipine and 50 to enalapril. At baseline 44 patients had normoalbuminuria, 36 microalbuminuria, and 22 macroalbuminuria. MAIN OUTCOME MEASURES: Blood pressure, albuminuria, and parameters of renal function and glycaemic control. RESULTS: In patients who completed one year's treatment the median dose required by the nifedipine group (n = 49) was 60 mg/day; seven (14%) required additional diuretics. Of 41 patients given enalapril, 37 required the maximum dose (40 mg/day) and 27 (76%) required diuretics. At one year mean arterial blood pressures were similar in both groups. Albuminuria fell by 54% in the enalapril group and 11% in the nifedipine group (p = 0.006). Fractional albumin clearance ratio fell by 47% in the enalapril group and increased by 3% in the nifedipine group (p = 0.009). Creatinine clearance fell similarly in both groups but plasma creatinine concentration was increased by 20% in the enalapril group versus 8% in the nifedipine group (p = 0.001). CONCLUSION: Patients taking enalapril often required diuretics to control blood pressure. Enalapril reduced proteinuria significantly more than nifedipine in the microalbuminuric and macroalbuminuric patients but increased plasma creatinine concentrations. Longer follow up is required to clarify the importance of enalapril's antiproteinuric effect.

Albuminuria↗
PubMed1992

The inter-relationships between albuminuria, plasma albumin concentration and indices of glycaemic control in non-insulin-dependent diabetes mellitus.

We studied the relationship between albuminuria (measured as albumin/creatinine ratio (alb/Cr) in a random urine sample) and measures of glycaemic control (fructosamine, HbA1 and glucose) in 470 patients with non-insulin-dependent diabetes mellitus (NIDDM). Albumin excretion was in the microalbuminuric range (alb/Cr ratio > 5.4-40.3) in 112 (23.8%) and in the macroalbuminuric range (alb/Cr ratio > 40.3 mg/mmol) in 89 patients (18.9%). Fourteen percent (n = 67) of patients had a normal plasma HbA1 (< or = 8.5%) while 27% (n = 127) had a normal plasma fructosamine concentration (< or = 2.2 mmol/l). Using stepwise multiple regression analysis, plasma fructosamine concentration was found to be independently and negatively associated with urine albumin/creatinine ratio (B = 0.24, P < 0.006) in the macroalbuminuric group. Further analysis of the relationship between plasma albumin concentration and indices of glycaemic control showed that plasma albumin concentration correlated negatively with random plasma glucose concentration in the normoalbuminuric patients (r = -0.16, P = 0.008) but not in microalbuminuric or macroalbuminuric groups. HbA1 was not correlated with plasma albumin concentration. Our results indicate that albuminuria has an effect on the plasma fructosamine concentration which is independent of plasma albumin concentration.

Adult↗
PubMed1990

Urinary levels of proteins and metabolites in workers exposed to toluene. A cross-sectional study.

We measured urinary excretion of albumin and retinol-binding proteins to investigate the occurrence of early renal dysfunction in 45 paint workers exposed principally to toluene, and in the same number of unexposed control subjects matched individually for sex and age. Two biological indicators of personal toluene absorption, namely urine hippuric acid and o-cresol, were also measured in the exposed subjects. A significantly higher level and increased prevalence of elevated retinol-binding protein in the urine of exposed workers was found, whereas no significant difference in urinary albumin concentration was seen between the two groups. Urinary concentrations of retinol-binding protein was correlated (r = 0.399, P less than 0.006) with that of o-cresol, but not with hippuric acid or employment duration. The results suggest a dose-dependent early tubular effect due to toluene exposure that might be useful for monitoring individuals exposed to toluene at work.

Adult↗
PubMed1990

A case control study of some hematological and biochemical variables in acute stroke and their prognostic value.

Hematocrit, total white cell and platelet counts, plasma urea and creatinine concentrations were estimated in 291 patients (mean age 70 +/- 12 years) admitted consecutively over a 6-month period to a district general hospital with acute stroke. Urinary albumin/creatinine ratio was also determined in a subgroup of patients during a follow-up visit 3 months after ictus. Results were compared with those from age- and sex-matched community controls. Total white cell count was elevated in all types of stroke compared with values from control subjects. Platelet count, plasma urea and creatinine concentrations were higher and the plasma albumin/globulin ratio was lower among patients with ischemic stroke. Elevated total white cell count, urea and creatinine, which were of prognostic significance, were found to be associated with the severity of stroke as indicated by the Glasgow coma score, and did not have any independent prognostic value. Elevated hematocrit was not shown to be a risk factor and did not have any prognostic significance. A low plasma albumin/globulin ratio, an index of plasma viscosity, was a possible risk factor for ischemic strokes. Urinary albumin/creatinine ratios in the highest quintile increased the risk of stroke 13-fold.

Aged↗
PubMed1990

Urinary excretion of albumin and enzymes in non-insulin-dependent Chinese diabetics.

Urine albumin (Alb), total protein (TP) and creatinine (Cr) concentrations and the activities of N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP) and gamma-glutamyl transpeptidase (GGT) were measured in untimed random urine samples from 157 non-insulin-dependent (NIDDM) diabetic subjects and 54 healthy subjects. In NIDDM subjects the excretions of TP, Alb, NAG, AAP, GGT (expressed in relation to creatinine) were significantly higher and were abnormal in 59.9%, 68.8%, 47.2%, 41.4% and 13.4% of the subjects, respectively. However, 24.5%, 22.4% and 6.1% of NIDDM subjects with normal Alb/Cr ratio had abnormal excretion of NAG, AAP and GGT, respectively. Alb/Cr ratio was greater than 26.8 mg/mmol (considered to be equivalent to albumin excretion of 250 mg/24 h) in 14.6% and between 2.5-26.8 mg/mmol (equivalent to albumin excretion rates of 20-250 mg/24 h) in 54.1% of subjects. In those diabetic subjects with clinical retinopathy only Alb/Cr ratio was higher. Arterial blood pressure was significantly correlated with Alb/Cr (r = 0.365) and NAG/Cr (r = 0.204). We conclude that prevalence of abnormal Alb/Cr is relatively common among Chinese NIDDM subjects.

Acetylglucosaminidase↗
PubMed1989

Automated immunoturbidimetric methods for the determination of retinol binding protein, prealbumin and transferrin in urine.

We describe the development of rapid and simple automated methods for the estimation of retinol binding protein (RBP), prealbumin (PA) and transferrin (TRF) in urine. These methods measure the turbidity formed as a result of reaction between the protein and a specific antibody in a phosphate buffer containing 70 g/L polyethyleneglycol as accelerator for the antigen antibody reaction. The method for retinol binding protein (RBP) correlated well when compared with a method based on enzyme-linked immunosorbent assay (ELISA) (r = 0.978). The recoveries were 93-104%, 84-95% and 84-100% for RBP, PA and TRF respectively. The between-batch coefficients of variation were 2.6-10.6, 2.8-12.6 and 4.2-8.7% respectively. The analytical range of the method was 0.0625 to 40 mg/L for RBP, 0.28 to 45 mg/L for PA and 0.14 to 70 mg/L for TRF. The methods can be performed manually using a simple spectrophotometer or can be easily automated.

Autoanalysis↗
PubMed1989

Urinary excretion of transferrin by non-insulin-dependent diabetics: a marker for early complications?

We measured concentrations of transferrin (TRF, in micrograms), and creatinine (Cr, in millimoles) in samples of untimed urine from 53 healthy subjects and 157 non-insulin-dependent diabetic (NIDD) subjects. The urinary TRF/Cr ratio was significantly higher in the NIDD group (P less than 0.001). If NIDD subjects are grouped according to their Alb/Cr ratio into normal albuminuria (Group A, Alb/Cr less than 2.5 mg/mmol), microalbuminuria (Group B, Alb/Cr 2.5-26.8 mg/mmol), and macroalbuminuria (Group C, Alb/Cr greater than 26.8 mg/mmol), the TRF/Cr ratios in all three groups exceeded those for healthy controls. Moreover, this ratio was higher in Group B than in Group A and higher in Group C than in Group B. The value for TRF/Cr was clearly abnormal (i.e., exceeded the 95th percentile value found in healthy subjects) in 61%, 95%, and 100% of Group A, B, and C subjects, respectively. The TRF/Cr ratio was significantly higher in those NIDD subjects with clinical retinopathy, and it correlated with arterial pressure. Evidently, TRF/Cr may be increased early in NIDD subjects, and it may be a sensitive marker for detecting development of complications of diabetes.

Adult↗
PubMed1989

Urinary excretion of some proteins and enzymes during normal pregnancy.

Total protein (TP), albumin (Alb), transferrin (TRF), retinol-binding protein (RPB), N-acetyl-beta-glucosaminidase (NAG), alanine aminopeptidase (AAP), gamma-glutamyltransferase (GGT), and creatinine (Cr) were measured in random (untimed) urine samples from 29 nonpregnant women and from pregnant subjects (11 in the first trimester, 34 in the second, and 37 in the third). The excretion of TP, Alb, TRF, NAG, and AAP (relative to creatinine) and the RBP concentration were all higher (P less than or equal to 0.05) in the second and third trimesters compared with values for the nonpregnant controls. The GGT/Cr ratio was significantly higher only in the third trimester. The increase in low-molecular-mass proteins and tubular enzymes suggests that at least part of the increase in Alb, TRF, and TP results from decreased tubular reabsorption. We conclude that excretion of both high- and low-molecular-mass proteins is increased during pregnancy.

Adult↗
PubMed1988

Massive hydrothorax in continuous ambulatory peritoneal dialysis: diagnosis, management and review of the literature.

Recurrent massive hydrothorax is an uncommon but serious complication in patients on continuous ambulatory peritoneal dialysis (CAPD). Accurate confirmative diagnostic procedures of the pleuroperitoneal communication is lacking and the management remains difficult. We reported three patients who developed massive hydrothorax at different periods after commencement of CAPD treatment (1.5-9 months). These patients underwent different investigatory procedures for demonstrating the pleuroperitoneal communication. We conclude that both technetium 99m-tagged macroaggregated albumin intraperitoneal radionuclide scan and stereoisomeric analysis of lactate in the peritoneal and pleural fluid are safe and reliable procedures to demonstrate the pleuroperitoneal communication. The massive hydrothorax was successfully treated in two patients by pleurodesis induced by intrapleural administration of oxytetracycline combined with 10-days small volume intermittent peritoneal dialysis. The clinical findings of 18 other cases previously reported in the literature are also reviewed.

Adult↗
PubMed1988

Protein nutritional status in elderly Chinese in Hong Kong.

Daily intakes of protein and energy were estimated in a group of 417 apparently healthy elderly Chinese subjects aged 60 years and over, living independently in the community. The mean protein intake was 1.2 g/kg body weight, well above the WHO/FAO/UNU recommendation of 0.8 g/kg, and comparable to intakes of elderly Americans and Britons. Plasma total protein, albumin, prealbumin, retinol binding protein and transferrin concentrations were also measured. No age- or sex-related differences were found and the values were comparable to published values for elderly Caucasians. Plasma prealbumin and retinol binding protein concentrations correlated with protein intake and with arm muscle area. Protein nutritional status appears adequate for elderly Chinese living in the community.

Aged↗