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Biomedical subjects

K K Pun

Publications and source records attributed to K K Pun.

At least 19 recordsLinked to original sources
PubMed1992

Idiopathic hypercalciuria causing osteoporosis and hypocalcemia.

Idiopathic hypercalciuria, though a common cause of nephrolithiasis, has not been recognized to cause hypocalcemia and severe bone disease. We describe an adolescent with idiopathic hypercalciuria who presented initially with severe hypocalcemia and osteoporosis and this was later complicated by recurrent renal calculi formation after calcium and vitamin D supplement. After treatment with thiazide, hypercalciuria was controlled and serum biochemistry normalized. While idiopathic renal hypercalciuria may cause a negative calcium balance in adults, a variant of this syndrome with severe renal calcium leak occurring in a growing subject could lead to severe hypocalcemia and osteoporosis.

Adolescent↗
PubMed1992

Total and regional bone densities in dialysis patients.

Total and regional bone mineral densities (BMD) of ten male haemodialysis (HD) patients and ten male patients on continuous ambulatory peritoneal dialysis (CAPD) were measured using dual-energy X-ray absorptiometry (DEXA), and compared with that of age- and sex-matched controls. Our data showed that patients with renal failure on dialysis had reduced bone densities as manifested by a reduction in total body BMD, femoral neck BMD, and Ward's triangle BMD. In addition, head BMD and femoral trochanter BMD were also reduced in HD patients. Among HD patients, the length of the period of dialysis correlated with serum level of parathyroid hormone and the reductions in total body BMD and head BMD. Furthermore, there was a strong negative correlation between bone density of the skull and serum parathyroid hormone. Our results demonstrated regional variations in the reduction of bone density in patients with asymptomatic renal bone disease. DEXA bone scan is a useful adjunct in the early assessment of renal osteodystrophy and bone density of the skull can be used as a monitor in hyperparathyroid bone disease.

Adult↗
PubMed1991

Rapid postmenopausal loss of total body and regional bone mass in normal southern Chinese females in Hong Kong.

Osteoporosis is a major health problem in Hong Kong, affecting about 200,000 patients among a population of 6 million. To evaluate the rate of bone loss and determinants of low bone mass among the Southern Chinese, we measured the total body and regional bone mass with the XR-26 dual-energy X-ray absorptiometry in 90 normal females. The results show that the total and regional bone densities were stable before menopause, with a change of around 0.5% every year. After menopause, a rapid loss is evident for total body and regional bone mass. The rate of bone loss varies from 1.2% for the pelvis to 3.1% for the Ward's triangle per year. Thus, by the age of 70, most Southern Chinese females would have lost at least 25% of their bone. Age, body weight, and skeletal area are important determinants for the total body bone mass. Bone densities in weight-bearing regions, including hip, pelvis, spine and legs correlate strongly with each other (r = 0.68, P less than 0.001). Correlation is poor among unrelated regions, such as between head and arms (r = 0.39, P greater than 0.5). To conclude, normal Chinese women in Hong Kong lose bone rapidly after menopause at a rate of about 2% per year. This may account for the major incidence of osteoporosis-related complications in Hong Kong.

Absorptiometry, Photon↗
PubMed1991

Rhabdomyolysis associated with cranial diabetes insipidus.

Rhabdomyolysis has been reported to be associated with hyperosmolality in diabetic ketoacidosis and non-ketotic hyperosmolal state. Whether the rhabdomyolysis was due to hyperosmolality per se or whether hyperglycaemia also played a role is not clear. We hereby report a case of cranial diabetes insipidus with hypernatraemia and hyperosmolality complicated by rhabdomyolysis. None of the known risk factors, such as coma, hypokalaemia, hypophosphataemia, diabetic ketoacidosis or non-ketotic hyperosmolality, were present in this patient. We believe that severe hyperosmolality per se is an important predisposing factor for non-traumatic rhabdomyolysis, and serum muscle enzymes should be closely monitored in the management of patients with diabetes insipidus.

Adult↗
PubMed1991

Propylthiouracil hypersensitivity with circumstantial evidence for drug-induced reversible sensorineural deafness: a case report.

Severe adverse reactions to propylthiouracil occur in 1-5% of patients. Three major side effects, namely agranulocytosis, hepatotoxicity and drug-induced hypersensitivity, have been described though these syndromes are not distinct entities and there can be overlaps in the clinical manifestations. The drug-induced hypersensitivity may be an immune-mediated reaction with multiorgan involvement in which a combination of polyarthritis, cutaneous vasculitis and fever is common. We report a patient with propylthiouracil-induced hypersensitivity with an unusual combination of high spiking fever, migratory polyarthritis, reversible sensorineural deafness, normochromic normocytic anaemia, leucocytosis and hepatotoxicity associated with polyclonal activation of multiple autoantibodies. This case illustrates the highly variable clinical manifestations of the syndrome. The prompt recovery upon withdrawal of the drug indicates the importance of early diagnosis.

Adult↗
PubMed1991

1,25-Dihydroxycholecalciferol and peritoneal macrophage chemotaxis in patients on continuous ambulatory peritoneal dialysis.

Single graded doses of 1,25-dihydroxycholecalciferol of 2 and 4 micrograms were added intraperitoneally into the overnight 1.5% glucose dialysate of 6 patients on continuous ambulatory peritoneal dialysis. The effect on peritoneal macrophage chemotaxis and random migration was studied and compared with the baseline when no 1,25-(OH)2D3 was added. No consistent effect on peritoneal macrophage chemotaxis was observed. Random migration was significantly depressed at 4 micrograms when compared with baseline (5.4 +/- 1.9 vs. 12.2 +/- 3.7 cells/high-power field, p less than 0.05). The potential clinical role of 1,25-(OH)2D3 as an immune modulator requires further study.

Adult↗
PubMed1991

Dietary calcium intake and other risk factors: study of the fractured patients in Hong Kong.

Osteoporosis has become a major health problem among the elderly in Hong Kong. This study compares the level of dietary calcium intake and the differences in various risk factors among elderly fracture patients and elderly without fractures. Furthermore, this study identifies the relationship between the risk factors and the amount of calcium intake; and classifies the fracture patients and the low calcium intake group. Although the design of the present study precludes testing causal hypotheses, the findings are suggestive of factors that are likely to be important in a program to reduce fractures among elderly populations.

Aged↗
PubMed1990

Addisonian crisis as presenting feature in malignancies.

Metastases to the adrenal glands are common in patients with malignancy but malignant disease presenting as Addisonian crisis is rare. The authors presented two patients with acute Addisonian crises due to metastatic infiltration of the adrenal glands. They were otherwise asymptomatic from the primary tumor. Computed tomographic scan showed bilateral adrenal enlargement and transcutaneous biopsy confirmed metastatic adenocarcinoma in the adrenals. Adequate glucocorticoid replacement improves quality of life and prolongs survival.

Acute Disease↗
PubMed1990

Desensitization of parathyroid hormone receptors on cultured bone cells.

Administration of excessive amounts of parathyroid hormone (PTH) in the treatment of osteoporosis can reverse the beneficial effects of a low-dose, intermittent regime. To investigate the direct actions and the possible cellular mechanisms of PTH in inducing desensitization of PTH receptors, we studied the effects of desensitization on rat osteoblastic UMR-106 cells. When the osteoblasts were preincubated with bPTH-(1-34), complete refractoriness to a subsequent challenge with the hormone developed within 1 h and at hormone concentrations as low as 5 nM. When osteoblasts thus desensitized were incubated in hormone-free medium, recovery of the cAMP responses began within 2 h and reached maximum after 16 h. Cycloheximide did not affect the process of desensitization. [Nle8,Nle18,Tyr34]bPTH-(3-34)amide significantly impaired the desensitization process by PTH-(1-34) but did not have stimulatory effect on cAMP responses. No significant heterologous desensitization was obvious after preincubation with isoprenaline (50 microM), prostaglandin E1 (50 microM), or prostaglandin E2 (50 microM) for 2 h. Binding experiments with [125I]PLP-(1-36)amide after desensitization revealed that there was an approximate twofold decrease in receptor affinities as analyzed by Scatchard analysis, showing that the decrease in affinity was prominent in the process of desensitization. When the cells were treated with monensin during desensitization, PTH challenge after desensitization produced significantly lower cyclic AMP responses. Recovery after desensitization occurred over a period of 16 h. Inclusion of monensin, but not cycloheximide, impaired the recovery. The results show that homologous desensitization of rat osteoblasts to PTH is brought about by the occupancy of receptors by PTH-(1-34) but not by cAMP generation itself.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclic AMP↗
PubMed1990

Absorption of intranasal salmon calcitonin in normal subjects and hypogonadic men.

The absorption kinetics of intranasal salmon calcitonin were assessed in 4 normal subjects and 9 patients with Klinefelter's syndrome. After administration, absorption occurred within 5 minutes. There was a highly significant correlation between the amount administered and the amount absorbed (r = -0.83, P less than 0.0005).

Administration, Intranasal↗
PubMed1990

Circulating somatostatin after oral glucose in hypothyroidism.

The response of circulating somatostatin-like immunoactivity (SLI) to oral glucose and its relation to other pancreatic islet cell hormones were studied in 10 hypothyroid subjects before and after treatment. None of the patients suffered from diabetes mellitus or obesity. Compared with normal controls, the hypothyroid subjects had higher fasting and stimulated SLI levels but lower fasting pancreatic glucagon levels. Integrated glucose and insulin responses following glucose ingestion were normal, but the peak insulin response was delayed to 120 min suggesting impaired pancreatic beta-cell response to oral glucose. On the other hand, the peak response of plasma C-peptide was higher probably because of a reduction in metabolic clearance. In both hypothyroid subjects and controls, a significant correlation was found between the maximal increment of SLI and the maximal decrement of glucagon following oral glucose. In conclusion, plasma SLI is increased in hypothyroidism. The changes in SLI may be due to either an increased hormonal secretion or a reduced metabolic clearance in hypothyroidism. This elevated SLI might contribute to the slower gastrointestinal motility observed in hypothyroidism. Our data also suggest that the reduction in glucagon secretion may be secondary to the increase in circulating SLI.

Adult↗
PubMed1990

Delayed decline in plasma atrial natriuretic peptide levels after an abrupt reduction in atrial pressures: observation in patients with dual-chamber pacing.

The effect of an abrupt reduction in atrial pressures on atrial natriuretic peptide (ANP) secretion was studied in four patients with complete atrioventricular block with a dual-chamber pacemaker when the pacing mode was changed from the VVI to the DVI mode at an equal rate of 70/min. Simultaneous continuous hemodynamic monitoring was performed using a balloon-tipped thermodilution catheter. With DVI pacing, there was an immediate decrease of right atrial pressure from 4.5 +/- 0.9 to 1.8 +/- 1.1 mm Hg, and a reduction of pulmonary arterial wedge pressure from 7 +/- 0.8 to 4.5 +/- 0.9 mm Hg, together with a rise in cardiac output from 3.1 +/- 0.2 to 3.7 +/- 0.2 L/min. However, despite a constant hemodynamic status after dual-chamber pacing, the arterial ANP level steadily decreased from 151 +/- 26 pg/ml to a steady low level of 78 +/- 15 pg/ml after 20 minutes of dual-chamber pacing (percentage reduction- 48 +/- 8%, p less than 0.05). This persisted until the end of the study at 60 minutes. The time-dependent decay in ANP secretion after an abrupt and constant change in hemodynamic status should be considered when interpreting ANP levels.

Aged↗
PubMed1990

Vitamin D status among patients with fractured neck of femur in Hong Kong.

Vitamin D deficiency leads to secondary hyperparathyroidism initially and then to mild osteomalacia, both of which conditions may be aymptomatic and may predispose to bone fracture. To assess the importance of vitamin D deficiency in predisposing to fractured neck of femur, we studied the vitamin D status, dietary intake and socio-economic characteristics in 69 patients with fractured neck of femur (group A), 28 normal subjects with age above 60 (group B), and 101 normal volunteers (group C). Patients with fractured neck of femor had significantly lower levels of serum 25-hydroxy-cholecalciferol compared with subjects of groups B and C. There is no statistically significant difference in other biochemical parameters, including calcium, phosphate, and alkaline phosphatase. Patients with fractured neck of femur and with 25-hydroxycholecalciferol below 20 ng/mL were characterized by a home-bound and/or institutionalized life-style, smaller living place, and limited access to open space. To conclude, hypovitaminosis D is a common problem among elderly patients with fractured neck of femur in Hong Kong. The fact that such vitamin D deficiency is associated with muscle weakness may contribute to falls, and thus indirectly account for an increased rate of hip fractures over the normal control.

Aged↗
PubMed1990

25-Hydroxycholecalciferol and insulin-like growth factor I are determinants of serum concentration of osteocalcin in elderly subjects with and without spinal fractures.

Osteocalcin is one of the major proteins in the osseous matrix. To evaluate the determinants and thus the physiological control of osteocalcin production in normal and osteoporotic subjects, the serum levels of osteocalcin, 25-hydroxycholecalciferol (25-OH-D3), and insulin-like growth factor I (IGFI) were measured by radioimmunoassay in 44 subjects over 60 years old. Circulating osteocalcin, 25-OH-D3, and IGFI were 0.28 +/- 0.10 nmol/L (1.65 +/- 0.96 ng/mL), 70.5 +/- 25.1 nmol/L (28.3 +/- 10.1 ng/mL), and 23.8 +/- 12.0 nmol/L in 27 healthy controls respectively, as compared with 0.09 +/- 0.09 nmol/L (0.52 +/- 0.52 ng/mL), 48.2 +/- 19.9 nmol/L (19.35 +/- 7.91 ng/mL), and 16.56 +/- 6.96 nmol/L in 17 patients with spinal fractures. Significant correlation was found between osteocalcin and 25-OH-D3 level, as well as between osteocalcin and IGFI. The results show that IGFI and 25-OH-D3 are important determinants for serum concentration of osteocalcin in elderly subjects with and without spinal fractures.

Aged↗
PubMed1990

Discriminant factors affecting early outcome of radioiodine treatment for Graves' disease.

Pretreatment clinical, biochemical, iodine-131 (131I) scan and tracer-kinetic parameters were studied in 827 Chinese patients with Graves' disease treated with radioactive iodine. One year after 131I therapy, 56.7% were euthyroid, 33.9% were still thyrotoxic and 9.4% were hypothyroid. Discriminant analysis of all pretreatment variables identified thyroid mass, presenting free thyroxine index and 4 h 131I uptake as the three variables most helpful in discriminating the early outcome group of 131I therapy. The findings suggest that patients with large goitres and severe disease may require higher doses of 131I for treatment of Graves' disease.

Adult↗