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Biomedical subjects

J C Chan

Publications and source records attributed to J C Chan.

At least 307 records · Page 17Linked to original sources
PubMed1990

Bites by the white-lipped pit viper (Trimeresurus albolabris) and other species in Hong Kong. A survey of 4 years' experience at the Prince of Wales Hospital.

The case records of 242 snake bite victims admitted to the Prince of Wales Hospital in Hong Kong between September 1984 and October 1988 were studied retrospectively. When the snake was identified, the White-lipped pit viper (Trimeresurus albolabris) was by far the commonest species involved. In addition to local oedema and inflammation, evidence of a significant blood clotting disturbance was present in at least 10% of cases, defibrination and thrombocytopenia being the commonest findings. Since such abnormality was not always sought the true figure is likely to be higher. Three fatalities occurred, one of which was secondary to a probable White-lipped pit viper bite, one to a bite by Chinese cobra and one to a bite by Russell's viper.

Adult↗
PubMed1990

10-year survey of referrals to a pediatric nephrology program.

To provide a realistic picture of the patient case load of a pediatric nephrologist in a teaching hospital, we analyzed the number, the demographics, and the reasons for patient referral to our pediatric nephrology program over a 10-year period. Between January 1, 1978, and December 31, 1987, 1,523 pediatric patients were referred to the Medical College of Virginia for evaluation and treatment of renal and electrolyte disorders. The most common reason for referral was a fluid-electrolyte disorder (30%), followed by hematuria/proteinuria (22%), chronic glomerulonephropathies (10%), hypertension (5%), nephrotic syndrome (6%), end-stage renal disease (3%), urinary tract infections (5%), and acute glomerulonephritis (3%). More than 25% of the patients were under 1 year of age at initial presentation. The rest are equally distributed among the other pediatric age groups, including adolescents. Fifty-eight percent of these patients were white, and 41% were black. Males accounted for 54% of the referrals and females for 46%. Percutaneous renal biopsies were performed under ultrasound guidance on 167 patients or a rate of 17 procedures per year. Fifty-one patients, ranging in age from 0.5 to 19 years, were followed for end-stage renal disease during the 10-year study period. Glomerular disorders accounted for 61% of the end-stage renal diseases and anatomic disorders for 39%. The yearly incidence of end-stage renal diseases over this time was 9.8 patients/million children. Twenty-six (51%) of these patients received one or more kidney transplants during the study period.

Child↗
PubMed1989

Monoclonal antibody recognizing a carcinoembryonic antigen epitope differentially expressed in human colonic carcinoma versus normal adult colon tissues.

Murine hybridomas were generated against purified carcinoembryonic antigen (CEA), and their monoclonal antibodies (MAb) were assayed for their ability to recognize specific CEA epitopes. One of the MAb, designated 7F, was found to recognize an epitope of CEA that was expressed in human colonic carcinoma tissues but not in normal colonic tissues. When extracts of 13 colonic carcinoma tissues and 9 normal colonic tissues were examined with the Western blot technique using MAb 7F, 11 colonic carcinoma tissues (85%) reacted with 7F, but none of the 9 normal colonic tissues (including many obtained from the areas adjacent to the colonic carcinomas) did. Western blot analysis indicated a Mr 180,000 band in 11 of 13 (85%) colonic carcinoma extracts. The limit of detectability of CEA was 0.5 micrograms/lane. According to immunohistochemical techniques, 16 of 18 (89%) formalin-fixed paraffin-embedded sections of colonic carcinomas reacted with MAb 7F, whereas 9 of 9 (100%) frozen sections of colonic carcinomas reacted with the antibody. Of the 32 paraffin-embedded and frozen sections of normal colonic tissues examined, none showed any reactivity with MAb 7F. MAb 7F did not react with nonspecific cross-reacting antigen either. This antibody has been examined for its usefulness in detecting CEA in suspension and has been found to work both in sandwich enzyme-linked immunosorbent assays and in sandwich radioimmune assays. The detection of CEA in colon tumors but not in normal colonic tissues may be attributed to two possible explanations. It is possible that the level of CEA expression in normal colonic tissue is below the sensitivity of the assays employed. Alternatively, MAb 7F may recognize a "specific" epitope of CEA which was found in colon tumors but not in CEA of normal colonic tissues. At the present time, it is not possible to discern between these two possibilities. Nevertheless, MAb 7F was capable of detecting the differential expression of CEA in colonic carcinomas and, therefore, may be useful for the immunodiagnosis, radioimaging, and immunotherapy of colon cancer.

Antibodies, Monoclonal↗
PubMed1989

Secretion, glycosylation, and phosphorylation of rat-specific, transformation-associated proteins in Moloney murine sarcoma virus-transformed rat cells.

Previously, we detected, by monoclonal antibody, three Moloney murine sarcoma virus (Mo-MSV)-activated intracellular transformation-associated proteins (TAP), (P66, P63, and P60) in several Mo-MSV-transformed rat cell lines (Chan et al., Biochem. Biophys. Res. Commun., 134: 1223-1230, 1986) and found the release of TAP into the extracellular medium with a change from three intracellular polypeptides to two extracellular polypeptides (P68 and P64) (Li et al., Virology, 156: 91-100, 1987). Since then, we have further analyzed TAP in terms of their secretion, glycosylation, and phosphorylation in a temperature-sensitive Mo-MSV-transformed normal rat kidney (NRK) cell line, the 6M2 line, and found these results. Extracellular TAP were detected by immunoblotting and immunoprecipitation techniques as two polypeptides (P68 and P64). The secretion of TAP was rapid, with a 50% secretion rate of 78 min. Both intracellular (except for P63) and extracellular TAP were glycosylated. As a result of inhibition of glycosylation by the antibiotic tunicamycin, a fourth intracellular TAP (P58) and a third extracellular TAP (P60) were found. The new results suggest that the intracellular TAP were probably changed from four polypeptides (P66, P63, P60, and P58) to three (P66, P63, and P60) during the glycosylation process. Likewise, the three extracellular TAP were changed to two (P68 and P64) as a result of further glycosylation and subsequent secretion into the extracellular medium. Inhibition of glycosylation by tunicamycin (0.5 microgram/ml) reduced the TAP secretion rate by about 39%. Extracellular TAP (P68 and P64) as well as P85gag-mos and P58gag were found to be phosphoproteins.

Animals↗
PubMed1989

Protein intake and renal function in children.

To evaluate the effects of protein intake on renal tubular functions, seven metabolic studies were performed on five adolescents with mild, chronic renal insufficiency. After equilibration, patients were randomly assigned to two periods of four days each on either a high-protein diet (HPD) or a low-protein diet (LPD), with energy intakes remaining the same during both periods. High protein intake resulted in significantly higher mean (+/- SD) daily creatinine excretion and clearance rates. The HPD was associated with significantly increased excretion rates of potassium, phosphate, sulfate, and calcium. Net acid excretion with the HPD was nearly threefold higher than that observed with the LPD. These differences were unassociated with urinary pH, which remained similar with both diets. We conclude that different protein intakes affect urinary excretion of creatinine, potassium, phosphate, sulfate, calcium, and net acid.

Adolescent↗
PubMed1989

Internuclear ophthalmoplegia in tuberculous meningitis.

Two patients with tuberculous meningitis and internuclear ophthalmoplegia are described. Despite treatment with anti-tuberculosis chemotherapy and corticosteroids, both patients died. In one case autopsy showed severe basal meningitis with diffuse brain stem infarction secondary to widespread vasculitis.

Adult↗
PubMed1989

Ofloxacin compared with amoxycillin in treating infective exacerbations in bronchiectasis.

Forty-one hospitalized adult patients of bronchiectasis (non-cystic fibrotic) with infective exacerbations were entered into a randomized, double-blind, placebo-controlled study comparing ofloxacin (200 mg tid) and amoxycillin (1 g tid) both orally for ten days. In the ofloxacin group (20 patients), improvement in sputum purulence was excellent in 14, and fair in five patients with one failure. In the amoxycillin group (21 patients), improvement in sputum purulence was excellent in eight, fair in five and poor in eight patients. Mean drug levels on day 5 were 4.1 mg l-1 for serum (2 h post-dosage) and 4.0 mg l-1 for sputum for ofloxacin, and 18.4 mg l-1 for serum and 0.3 mg l-1 for sputum for amoxycillin. Ofloxacin thus yielded higher sputum concentration and appeared to be more effective and also better tolerated than amoxycillin in infective episodes of bronchiectasis.

Adult↗
PubMed1989

Effects of bicarbonate-containing versus lactate-containing peritoneal dialysis solutions on superoxide production by human neutrophils.

Human neutrophils were isolated from healthy volunteers and exposed to either bicarbonate-containing (pH 7.4) or lactate-containing (pH 5.2) peritoneal dialysis solution in vitro. Superoxide production by neutrophils was measured by a method based on the superoxide dismutase-inhibitable reduction of ferricytochrome c. Bicarbonate-containing peritoneal dialysis solution was found to be superior to the lactate-containing one in facilitating the production of superoxide anion by human neutrophils.

Adult↗
PubMed1989

The effects of exogenous rat growth hormone therapy on growth of uremic rats fed an 8% protein diet.

Although the mechanisms underlying the inhibitory effects of chronic renal insufficiency on growth are poorly understood, large doses of growth hormone (GH) have been used to improve growth. The present study examines the effects of rat GH and a reduced (8%) protein diet on 75% nephrectomized weanling rats by measuring changes in growth parameters, food utilization, serum albumin concentration, and muscle water content. Significantly greater improvement in growth was found in the GH-treated uremic rats compared with the uremic controls. The mean percent change in wt, length (nose to tail tip), and cranial biparietal diameter was significantly increased in the GH-treated uremic rats, compared with the uremic controls, but foot length and femur length showed only moderate improvement. Food utilization efficiency and serum albumin concentration were significantly higher in GH-treated uremic rats compared with uremic controls, achieving levels that were not different from sham-operated rats. Muscle water content was not significantly different between GH-treated uremic rats, uremic controls, and sham-operated rats. Thus, rat GH treatment administered at an early age in mild renal insufficiency significantly improved overall growth, food efficiency, and serum albumin concentrations, despite a low protein diet, suggesting that further evaluation of this form of therapy for growth failure of uremia is warranted.

Animals↗
PubMed1989

High incidence of pulmonary tuberculosis in the non-HIV infected immunocompromised patients in Hong Kong.

In areas where tuberculosis is endemic, clinicians managing immunocompromised patients (ICP) are confronted with the possibility of Mycobacterium tuberculosis as a pathogen. To determine the incidence and clinical pattern of, the diagnostic approach to, and potential therapeutic implications of pulmonary tuberculosis in this patient population, we reviewed 62 non-HIV infected ICP in Hong Kong who had bronchoscopy because of pulmonary infiltrates. Pulmonary tuberculosis was the second most common cause after bacterial infections. Clinical and radiographic presentations of 12 patients with tuberculosis were nonspecific. Flexible bronchoscopy for tuberculosis carried a diagnostic sensitivity of 91.7 percent. We conclude that for the non-HIV infected ICP from areas where tuberculosis is endemic: M tuberculosis should be suspected as the pathogen; radiographic findings are diagnostically not helpful; FB is a sensitive diagnostic test for tuberculosis and in smear-negative cases where tuberculosis is suspected, initiation of empiric anti-tuberculosis therapy should be considered while awaiting culture results.

Adult↗
PubMed1989

X-linked hypophosphatemia.

X-linked hypophosphatemia is a common cause of metabolic rickets in children in this country. The gene defect is localized to the Xp22 region in man. Research into this disorder has been enhanced by the discovery of a mutant gene named Hyp on the X chromosome of mice that produces a syndrome similar to the human disease. These mutant genes in humans and mice alike result in low renal tubular reabsorption of phosphate, rickets, and osteomalacia. The renal synthesis of 1,25-dihydroxyvitamin D is unresponsive to low phosphate stimuli in both. A second mutant gene on the X chromosome of mice, Gy, also causes low renal tubular reabsorption of phosphate. The underlying defects in both the human disease and the mouse models are unknown. The availability of these murine models should advance our understanding of this clinical disorder and provide an environment for the testing of novel therapies.

Animals↗