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Biomedical subjects

C C Shek

Publications and source records attributed to C C Shek.

At least 19 recordsLinked to original sources
PubMed1998

Determination of the solute removal index for urea by using a partial spent dialysate collection method.

In 22 hemodialysis patients, during a dialysis session, the solute removal index (SRI) for urea obtained from the use of a partial spent dialysate collection method was compared with that derived from the use of a total spent dialysate collection technique. The partial spent dialysate collection method was used to harvest a small representative sample of the total spent dialysate. The volumes of spent dialysate collected by the partial and the total spent dialysate collection methods were 1.7 +/- 0.4 L and 129.6 +/- 15.3 L, respectively. The total amount of urea nitrogen removed by dialysis as estimated by the partial spent dialysate collection method was similar to that determined by the total spent dialysate collection approach. As a result, the SRI value for urea obtained by the partial spent dialysate collection method (namely, 63% +/- 8%) correlated very well (r = 0.95, P < 0.001) with that derived by the total spent dialysate collection technique (namely, 62% +/- 8%). Our data suggest that it is feasible to use a simple partial spent dialysate collection method to obtain SRI results in patients treated with hemodialysis.

Female↗
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

Effects of lithium therapy on bone mineral metabolism: a two-year prospective longitudinal study.

Many studies showed an increased occurrence of primary hyperparathyroidism during lithium therapy. We studied 53 patients receiving lithium therapy prospectively for 2 yr. Serum PTH levels were unequivocally elevated. The baseline PTH level was 2.8 +/- 1.2 pmol/L and increased progressively to 3.9 +/- 1.5 pmol/L after 2 yr (P < 0.0005). There was no change in serum calcium, alkaline phosphatase, inorganic phosphate concentrations or tubular reabsorption of phosphate in relation to glomerular filtration rate. Fasting urinary reabsorption of calcium increased significantly (P < 0.0005), which was concordant with the PTH change. Fasting and 24-h urinary excretion of calcium decreased significantly (P < 0.0005), suggesting reduced, rather than enhanced, bone resorption as in primary hyperparathyroidism. This may be the main mechanism in maintaining normocalcemia, despite PTH elevation, during lithium therapy.

Adolescent↗
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

Lithium pharmacokinetics in Chinese manic-depressive patients.

The pharmacokinetics of lithium was studied in 16 manic-depressive Chinese adults who were on lithium therapy in Hong Kong. A two-compartment open model was used to describe the plasma data obtained. The steady-state volume of distribution and total plasma clearance were estimated to be 63.4 +/- 38.3 L and 1.47 +/- 0.49 L/hr, respectively, which were similar to those reported in studies of Caucasian subjects. The lithium clearance was found to be significantly related to lean body mass (r = 0.646, p < 0.01) but not to either total body weight, age, or creatinine clearance. Interindividual variability in lithium clearance was substantially reduced to a coefficient of variation of 24.6% from 33.3% when lean body mass was considered. The combined plasma and urine data indicate that the rate and extent of lithium absorption were similar to those of earlier studies in Caucasian subjects on a standard lithium dosage.

Adult↗
PubMed1997

A partial dialysate collection method.

This study validates Ing's partial dialysate collection method, which employs proportionate collection using a side tube capped with a small-gauge plastic needle. The urea nitrogen and creatinine levels of the small representative fraction of spent dialysate collected in the above fashion are undistinguishable from those obtained from the total spent dialysate. The estimated urea nitrogen removed during hemodialysis using this approach is similar to that using the total dialysate collection method; Ing's method is simple and useful in quantifying the dialysis dosage and in its assessment of the nutritional status of patients on hemodialysis.

Bicarbonates↗
PubMed1995

Effects of fluvastatin on lipid profile and apolipoproteins in Chinese patients with hypercholesterolemia.

The effects of fluvastatin treatment on lipid profile and apolipoproteins were assessed in a group of 31 Chinese patients with hypercholesterolemia, maintained on a constant low-fat diet. Some patients had the additional cardiovascular risk factors of hypertension and non-insulin-dependent diabetes mellitus, and 6 patients had familial hypercholesterolemia. Baseline lipid levels were measured after a 4-week placebo period, and these were repeated after 4 weeks of treatment with fluvastatin 20 mg daily, and after 4 weeks of treatment with fluvastatin 40 mg daily. Total cholesterol, low density lipoprotein cholesterol, and apolipoprotein (apo) B were each reduced to the same extent with the 2 doses of fluvastatin (-20%, -26%, and -20%, respectively). Triglycerides and very low density lipoprotein cholesterol were also reduced by about 12% with the 2 doses of fluvastatin. Apo A-I was increased by 7% and high density lipoprotein cholesterol (HDL-C) was increased by 10% with the 40 mg dose. The increase in HDL-C was due to increases in both HDL2-C (18%) and HDL3-C (7%). Lipoprotein(a) levels did not show any significant change with the 2 doses of fluvastatin in this short-term study. One patient developed reversible asymptomatic elevation of liver enzymes with the higher dose of fluvastatin; otherwise the drug was well tolerated and no patients had to be withdrawn from the study.

Adult↗
PubMed1994

The prevalence of hypercalcaemia in pulmonary and miliary tuberculosis--a longitudinal study.

We studied the prevalence of hypercalcaemia in 34 Chinese patients with pulmonary (n = 32) or miliary (n = 2) tuberculosis. None of these subjects were given vitamin D or calcium supplements. Plasma calcium levels were measured at presentation and at 1- to 2-monthly intervals after treatment. During the 6-month study period, two patients (6%) developed hypercalcaemia (plasma calcium greater than 2.51 mmol/l), as compared to figures of 16% to 28% in the United States and India. By correcting the plasma calcium to a normal albumin, five (15%) of our patients were hypercalcaemic, as compared to a figure of 48% in Greece. Apart from variations in methodology, discrepancies in the reported prevalence of hypercalcaemia in tuberculosis may be due to differences in sun exposure, and vitamin D and calcium intake.

Adolescent↗
PubMed1993

Lithium-associated transient thyrotoxicosis in 4 Chinese women with autoimmune thyroiditis.

Four Chinese female patients who suffered from manic-depressive disorder and underlying autoimmune thyroiditis developed transient episodes of thyrotoxicosis during maintenance lithium therapy. Endocrinologically speaking, three of them had "Hashitoxicosis", while the other had silent lymphocytic thyroiditis. Albeit rare among Western patients, such lithium-associated thyroid dysfunctions appeared to be more likely to occur in Hong Kong Chinese. They seemed to involve multiple aetiological factors, such as autoimmune thyroid disease, the toxic and immunomodulatory roles of lithium and perhaps genetic and dietary factors. Because of their self-limiting nature, the importance of avoiding unnecessary and potentially deleterious antithyroid treatment is emphasised.

Adolescent↗
PubMed1993

17 alpha-Hydroxylase deficiency with persistence of müllerian ducts in a genotypic male and paradoxical aldosterone secretion.

We report a case of congenital adrenal hyperplasia due to 17 alpha-hydroxylase deficiency in a Chinese genotypic male patient. Despite the male genotype, normal female external genitalia were present and with the introduction of cyclical oestrogen therapy withdrawal bleeding occurred, confirming the presence of functional endometrial tissue. We believe this to be the first report of persistent Mullerian duct structures in a genotypic male with 17 alpha-hydroxylase deficiency. It could be explained by either impaired secretion or impaired action of anti-Mullerian hormone. Further, contrary to the usual finding of suppressed aldosterone secretion, this patient had measurable levels of plasma aldosterone.

Adolescent↗
PubMed1992

Thyroid abnormalities during chronic lithium treatment in Hong Kong Chinese: a controlled study.

Fifty Chinese psychiatric patients on chronic lithium treatment and the same number of sex- and age-matched control outpatients were assessed by a thyroidologist and underwent laboratory investigations. Lithium patients had a higher rate of goitres (50% vs 10%, P < 0.0001) and a higher mean TSH level (P < 0.005) than controls. Thyroid antibodies were detected in 7 older manic-depressive patients as opposed to 1 control, but not in patients with recurrent unipolar mania. Five patients, but no controls, had single or multiple episodes of hyperthyroidism, which was followed in 2 of them by biochemical hypothyroidism. It is suggested that variations in iodine status, dietary goitrogens, immunogenetic makeup and their complex interactions with chronic lithium treatment may contribute to ethnically different patterns of thyroid abnormalities.

Adolescent↗
PubMed1992

Folate concentration in Chinese psychiatric outpatients on long-term lithium treatment.

Among 46 Chinese and mostly manic-depressive (85%) outpatients attending a lithium clinic in Hong Kong, virtually no patients had low serum (0%) or erythrocyte (2%) folate. Their mean folate levels did not differ from lithium-free outpatients. Although serum folate correlated negatively with lithium dose (P less than 0.002) and serum level (P less than 0.01), lithium treatment probably did not by itself cause low folate. Folate level was not related to diagnosis, duration of mental illness, other drug usage or spot affective morbidity. Patients with a good response to lithium in the previous one year had a higher mean serum folate level than those with unsatisfactory response (P less than 0.05). These data suggest that folate deficiency is uncommon among Chinese psychiatric outpatients, but support recent evidence that folate at high concentrations enhances lithium prophylaxis.

Ambulatory Care↗
PubMed1992

Age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of bone metabolism in Chinese women.

OBJECTIVE: To study the age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of calcium metabolism in Chinese women who habitually have a low calcium intake. DESIGN: Cross-sectional study. SUBJECTS: One hundred and fifty-six healthy Chinese women aged 20-83 years. None were on any medication or vitamin supplements. Subjects over the age of 60 years were all living in a hostel; younger subjects were nurses or subjects attending a family clinic for minor illnesses. MEASUREMENTS: Fasting blood and urine samples were collected for biochemical measurements and calcium absorption was measured using 45Ca by the method of Marshall and Nordin. Bone density was measured by dual energy X-ray densitometry (Norland X R20 X-ray bone densitometer) at the left hip and lumbar spine. Serum parathyroid hormone was measured by a chemiluminometric assay. RESULTS: Plasma ionized calcium concentration, alkaline phosphatase, bicarbonate, plasma creatinine and serum B2 microglobulin were significantly higher in the elderly than in the young, whereas plasma phosphate and the anion gap were higher in the young. Urinary excretion of calcium, phosphate and hydroxyproline were all higher in older women. Plasma parathyroid hormone concentration was positively correlated with age even after taking into account the decline in renal function (as indicated by the rise in B2 microglobulin (r = 0.506, P less than 0.001). Serum concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were not lower in the older women. Fractional calcium absorption from an oral load of radiolabelled calcium was significantly lower in the older women and 37% of the older women were below the 2.5 percentile found in the younger women. Bone density measured by dual energy X-ray densitometry was also significantly lower in the elderly. CONCLUSION: In Chinese women there is an increase in PTH and a decrease in calcium absorption with age in spite of the presence of normal vitamin D metabolites.

Absorption↗
PubMed1992

Hypercalcemia in active pulmonary tuberculosis and its occurrence in relation to the radiographic extent of disease.

The prevalence of hypercalcemia in tuberculosis in Hong Kong and its occurrence in relation to the radiographic extent of disease were studied in 57 patients with sputum smear (n = 44) and/or culture positive (n = 13) pulmonary tuberculosis and in five patients with military tuberculosis prior to treatment. Only one (1.6%) patient had a corrected plasma calcium level above the reference range for our laboratory. There was a positive relationship between the corrected plasma calcium levels and the radiographic extent of disease (r = 0.37), p < 0.01). As the occurrence of hypercalcemia in tuberculosis is known to be influenced by the calcium intake, our finding of a low prevalence of "absolute" hypercalcemia in Hong Kong could be related to the low dietary calcium intake in these subjects.

Adult↗
PubMed1991

Nephrogenous cyclic AMP in primary hepatocellular carcinoma patients with or without hypercalcaemia.

OBJECTIVE: To study the relationship between the excretion of nephrogenous cyclic AMP (NcAMP) and other blood and urine parameters as an index of PTH-like activity in patients with primary hepatocellular carcinoma. DESIGN: After overnight fast, a double voided urine and a blood sample were collected from each subject for determination of various analytes and results compared between various groups. PATIENTS: Fifty-five consecutive untreated patients with primary hepatocellular carcinoma, 14 healthy controls and eight patients with cirrhosis only. MEASUREMENTS: Serum calcium, phosphate, alkaline phosphatase, albumin, creatinine and urinary calcium, creatinine and hydroxyproline were measured by routine methods. cAMP was measured in plasma and urine by a radioimmunoassay (Diagnostic Products Corporation) and PTH measured in serum by an immunoradiometric assay (Nichols Institute). TmP/GFR, NcAMP etc. were calculated according to various published methods. RESULTS: Four out of 55 patients (7%) with primary hepatocellular carcinoma had hypercalcaemia. These four patients had significantly lower (P less than 0.05) phosphate, PTH and TmP/GFR and elevated NcAMP (P less than 0.001) compared with normocalcaemic hepatocellular carcinoma and cirrhotic patients, and healthy controls. The excretion of hydroxyproline and calcium was significantly elevated (P less than 0.001) in the hypercalcaemic patients. Bone resorption was found to be the major cause of hypercalcaemia in three of the four hypercalcaemic patients. Fifteen hepatocellular carcinoma patients (29%) with normocalcaemia had suppressed PTH. CONCLUSION: We conclude that a PTH-like humoral factor such as PTH related peptide is the cause of hypercalcaemia in patients with primary hepatocellular carcinoma, and that in some normocalcaemic patients with this tumour PTH is suppressed.

Adult↗
PubMed1991

Hyponatremia in a hospital population.

The frequency, causes, and outcome of hyponatremia (plasma sodium less than 125 mmol/L), and the value of some routine investigations were studied during a six month period in a hospital population. The incidence and prevalence of hyponatremia were 1.5 and 2.6 per 100 patients per day, respectively. A majority of patients (75%) developed hyponatremia in the hospital. The commonest cause of hyponatremia was normovolemic hyponatremia (79 patients). Hypovolemic and hypervolemic hyponatremia were seen in 63 and 21 patients, respectively. Urine osmolality did not differ between the three groups, and was of little diagnostic value. The mortality in the hyponatremic patients was 41.7%.

Adolescent↗