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Biomedical subjects

I K Cheng

Publications and source records attributed to I K Cheng.

At least 73 records · Page 4Linked to original sources
PubMed1993

The requirement of low calcium dialysate in patients on continuous ambulatory peritoneal dialysis receiving calcium carbonate as a phosphate binder.

In the present study we investigated the requirement of low calcium dialysate in 35 patients on continuous ambulatory peritoneal dialysis (CAPD) receiving calcium carbonate as the sole phosphate binder over a 12-month period. Patients with corrected serum calcium > or = 2.85 mmol/L after switching to oral calcium carbonate were given 1 to 3 2-litre exchanges of 2.5 mEq/L calcium dialysate. Serum phosphate level dropped from the pretreatment value of 2.95 +/- 0.62 to a level of between 1.70 +/- 0.41 to 2.03 +/- 0.44 mmol/L 2 weeks after therapy. Corrected serum calcium level increased significantly from 2 weeks onwards. Serum alkaline phosphatase rose initially at 2 and 6 weeks and decreased from 3 months onwards. Serum parathyroid hormone level dropped significantly from a mean pretreatment level of 569 to 320 pg/ml after 12 months (p < 0.001). Serum aluminum decreased significantly from a mean of 1.04 to 0.65 umol/L (p < 0.01). Daily calcium carbonate requirement fluctuated but tended to increase till 8 months and plateaued and ranged from 2.61 +/- 0.57 to 3.98 +/- 2.11 gm. The daily requirement of low calcium dialysate followed a similar trend with approximately three-quarters of patients ultimately requiring at least 1 bag of low calcium dialysate. Eight patients did not require low calcium dialysate. Patients who required low calcium dialysate were significantly older, had a significantly lower pretreatment serum parathyroid hormone and higher serum aluminum levels than those who did not.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

A randomized prospective comparison of oral versus intraperitoneal ciprofloxacin as the primary treatment of peritonitis complicating continuous ambulatory peritoneal dialysis.

The present study compared oral versus intraperitoneal (ip) ciprofloxacin (ciproxin) as primary treatment of bacterial peritonitis in patients receiving continuous ambulatory peritoneal dialysis (CAPD) in a randomized, prospective trial. A total of 54 episodes in 46 patients were recruited for study. After excluding nonbacterial episodes and those not treated according to protocol, 48 episodes evenly divided between the two treatment arms were eligible for analysis. The primary cure rate was 41.7% and 66.7%, respectively, in the oral and ip treatment group. Half of those who failed or relapsed were due to infection with resistant, mostly gram-positive bacteria, which accounted for 79% of culture-positive episodes. Of the gram-positive isolates 42.3% were either resistant or intermediately susceptible to ciproxin compared to 16.7% of gram-negative isolates. The high level of bacterial resistance to ciproxin and treatment failure rate were related to the previous exposure to fluoroquinolones. Inadequate trough peritoneal drug levels also accounted for the failures in the ip but not the oral treatment group. We conclude that oral ciproxin is ineffective as a primary treatment of CAPD peritonitis in patients previously exposed to fluoroquinolones and that when administered ip, a dose of 50 mg/L instead of 25 mg/L of ciproxin should be used as maintenance in order to achieve adequate trough peritoneal drug levels.

Administration, Oral↗
PubMed1993

Single-dose pharmacokinetics of intraperitoneal ofloxacin in patients on continuous ambulatory peritoneal dialysis.

The present study examines the pharmacokinetics of ofloxacin given in a single dose of 200 mg intraperitoneally (ip) in the first bag of three 2-L 8-hour exchanges. Ofloxacin was measured using high-pressure liquid chromatography (HPLC) in the serum and peritoneal effluent over 24 hours. Six patients without and 3 patients with peritonitis were studied. Ofloxacin given ip was almost completely absorbed after an 8-hour dwell, and this was not affected by peritonitis. The time required to reach peak serum concentration was longer than that reported previously following oral administration. Elimination half-life (T1/2) of ofloxacin was markedly prolonged compared to patients with normal renal function. Peritoneal clearance accounted for only one-tenth of total serum clearance. Peritonitis appeared to shorten the T1/2 of ofloxacin, but this was mainly due to an increase in total serum clearance rather than a change in peritoneal clearance. Peritoneal drug concentration > 0.5 mg/L was reached in the second and third exchange by the second hour. No side effects from ip ofloxacin were observed. We concluded that ofloxacin given in a single dose of 200 mg is safe and provides adequate therapeutic serum and peritoneal concentration for more than 24 hours in patients on continuous ambulatory peritoneal dialysis (CAPD) with 8-hour exchanges.

Aged↗
PubMed1992

Post-transplant erythrocytosis: role of erythropoietin and male sex hormones.

Seventeen patients with post-renal transplant erythrocytosis and 17 non-erythrocytotic controls, matched in age, sex, serum creatinine and source of donor kidney, were studied to determine the role of erythropoietin, male sex hormones (testosterone, FSH, LH), and various patient risk factors in post-transplant erythrocytosis. Serum erythropoietin was significantly greater in erythrocytotic patients (35.6 +/- 5.7 mU/ml) than non-erythrocytotic patients (18.8 +/- 2.6 mU/ml) (P less than 0.05) and normal subjects (22.5 +/- 0.95 mU/ml) P less than 0.05). Serum testosterone was similar between the male study (13.2 +/- 6.2 nmol/l) and control (13.1 +/- 6.0 nmol/l) patients. This might be due to the greater basal LH in the male control subjects (13.9 +/- 11.7 IU/l versus 8.0 +/- 3.3 IU/l in erythrocytotic males, P = 0.084). Basal FSH in the male controls was greater than that in the study group (13.7 +/- 14 IU/l versus 6.8 +/- 2.9 IU/l, P = 0.067). Among the demographic risk factors, only the smoking history was important. There were more smokers among the erythrocytotic patients than controls (P = 0.051).

Adult↗
PubMed1992

Lovastatin in glomerulonephritis patients with hyperlipidaemia and heavy proteinuria.

Lovastatin, a 3-hydroxy-3-methylglutaryl coenzyme A inhibitor, was given to 14 patients with unremittent nephrotic syndrome (heavy proteinuria with hyperlipidaemia) for 6 months. Treatment was started at an initial dose of 20 mg/day, increasing to a maximum of 80 mg/day. Treatment was well tolerated except in two patients: one developed rhabdomyolysis and one severe hypertriglyceridaemia requiring an additional antihyperlipidaemic agent. Lovastatin was effective in reducing serum cholesterol, LDL-C and apolipoprotein B in the remaining 12 patients. Cholesterol was reduced by 31% from 8.24 +/- 0.49 mmol/l (mean +/- SEM) to 5.7 +/- 0.18 mmol/l after 6 months (P less than 0.001). LDL-C was normalized to 3.26 +/- 0.21 mmol/l from a pretreatment value of 5.76 +/- 0.48 mmol/l (P less than 0.001), a decrease of 43%. Serum apolipoprotein B was also normalized to 1.11 +/- 0.09 g/l from a basal level of 1.51 +/- 0.10 g/l (P less than 0.05). Triglyceride, HDL-C and apolipoprotein A1 concentrations were unchanged. Proteinuria as well as renal albumin clearance were unchanged. GFR by plasma radioisotope Cr-EDTA clearance for the whole group was unaltered by treatment. However, among those with relatively good pretreatment renal function (GFR greater than 70 ml/min per 1.73 m2), GFR increased at the end of 6 months' treatment (118.2 +/- 15 ml/min per 1.73 m2 versus 77.6 +/- 8.4 ml/min per 1.73 m2 in wash-out phase).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The impact of donor and recipient hepatitis B surface antigen status on liver disease and survival in renal transplant recipients.

Ninety-eight renal transplant recipients who had been followed for 1-6.5 years (median 3.2 years) were reviewed to determine the effect of donor and recipient hepatitis B surface antigen status on the incidence of hepatitis and on patient survival. The cumulative risk of developing hepatitis posttransplant was significantly higher in hepatitis B surface antigen-positive versus hepatitis B surface antigen-negative patients (P = 0.001). Nine (60%) of 15 patients who were hepatitis B surface antigen-positive prior to transplantation, 3 (75%) of 4 patients who became hepatitis B surface antigen-positive after transplantation, and 17 (22%) of 79 patients who were persistently hepatitis B surface antigen-negative developed hepatitis posttransplant. Five hepatitis B surface antigen-negative patients received allografts from hepatitis B surface antigen-positive donors. None of the five, including one who was initially seronegative, became hepatitis B surface antigen-positive posttransplant. Of the four patients who became HBsAg-positive posttransplant, three received kidneys from donors of unknown HBsAg status in China, while one was transplanted with a kidney from a HBsAg-negative donor. In summary, we found that the risk of developing hepatitis after renal transplantation was significantly higher in hepatitis B surface antigen-positive patients. However, both patient and graft survival were similar in hepatitis B surface antigen-positive and hepatitis B surface antigen-negative patients. The transplantation of kidneys from HBsAg-positive donors to HBsAg-negative patients did not result in clinically significant hepatitis or chronic HBsAg carriage. De novo hepatitis B infection may arise from sources other than the kidney itself.

Adult↗
PubMed1992

Hypocalcemia and myocardial function in uremia.

To investigate whether hypocalcemia affects cardiac performance in uremic patients, we studied the hemodynamic changes with short- and long-term correction of hypocalcemia in 4 uremic patients on dialysis using continuous wave Doppler study. At rest, 1 h of intravenous calcium infusion increased calcium level from 1.74 +/- 0.17 to 1.92 +/- 0.16 mmol/l (p less than 0.05). Cardiac output represented by minute distance increased from 10.5 +/- 2.0 to 12.1 +/- 2.5 m (p less than 0.05), but heart rate and blood pressure were unchanged. The peak velocity and acceleration of ascending aortic blood flow increased during calcium infusion. With long-term replacement, calcium level increased from 1.74 +/- 0.17 to 1.94 +/- 0.15 mmol/l (p less than 0.05), but resting hemodynamics were unchanged. On exercise testing, exercise duration increased from 10.6 +/- 1.6 min to 12.9 +/- 1.5 min (p less than 0.01), but hemodynamic parameters at peak exercise were similar. We conclude that acute calcium replacement enhanced cardiac contractility in uremic patients, but cardiac performance at rest and peak exercise was not improved with long-term therapy. This reflects different cardiac responses to acute versus chronic calcium replacement.

Adult↗
PubMed1992

Amino-aciduria and enzymuria in patients with artificial heart valves.

Fifteen patients with artificial heart valves and evidence of chronic intravascular haemolysis were studied for proximal tubular dysfunction. Three patients had haemosiderinuria and haemoglobinuria; 2 had haemoglobinuria alone. Increased urinary amino acid nitrogen occurred in 8, raised fractional beta 2-microglobulin excretion in 2, hypophosphataemia in 4, renal glycosuria in 1 and enhanced fractional urate excretion in 1. Urinary N-acetyl-beta-glucosaminidase (NAG) excretion increased in 7; the mean urinary NAG/creatinine ratio was raised to twice the upper limit of the normal range. Renal haemosiderosis due to chronic intravascular haemolysis could cause tubular injury.

Acetylglucosaminidase↗
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

Focal sclerosing glomerulopathy. Risk factors of progression and optimal mode of treatment.

Focal sclerosing glomerulopathy and especially focal segmental glomerulosclerosis (FSGS) have been recognized as a distinct clinical entity, however, there still exist controversies in terms of prognostic risk factors of progression and optimal mode of treatment. A total of 32 patients (2 with focal global sclerosis; FGS, the remainder with FSGS) were followed up for a mean period of 82 months (3-240 months). Fourteen presented with nephrotic syndrome and 18 had proteinuria with or without hypertension. Thirteen patients, all of whom except 1 were nephrotic, received steroid treatment with or without other immunosuppressive agents (cyclophosphamide/cyclosporin A/azathioprine). Three of the steroid-treated remained stable in complete remission; 5 nephrotic non-responders had renal death. The mean slope of 1/creatinine versus time for steroid-treated and non-treated groups was -0.23 and -0.043, respectively (p = 0.04), suggesting that nephrotic range proteinuria might be prognostically important. However, for the population of FSGS/FGS as a whole, only the initial serum creatinine predicted renal survival (p = 0.001 by Cox's regression model). Hypertension and hypercholesterolaemia were not important variables by themselves. Nevertheless, we found that the 9 patients treated with antihyperlipidaemics (gemfibrozil/probucol/cholestyramine/maxEPA) fared better, mean slope being -0.023 versus -0.103 for non-treated, though not reaching statistical significance (p = 0.96). Controlled prospective study involving a larger number of patients might be worthwhile.

Adolescent↗
PubMed1991

Effect of cyclosporine A on circulating immune complexes in IgA nephropathy.

This work was undertaken to examine the effect of cyclosporine A (CyA) on the serum concentration of circulating immune complexes in 22 patients with IgA nephropathy during an infection-free period. They were randomly divided into 2 groups: 11 patients received oral cyclosporine A (5 mg/kg/day) for 12 weeks and 11 patients received placebo (0.05 ml/kg/day). A significant reduction of proteinuria was observed in patients on CyA therapy but not in those receiving placebo. IgG-circulating immune complexes (CIC) were determined by solid phase Clq enzyme immunoassay (Clq EIA) and radial immunodiffusion (RID) and IgA-CIC were determined by solid phase anti-C3 enzyme immunoassay (anti-C3 EIA) and radial immunodiffusion. There was no change in IgA-CIC measured by RID and anti-C3 EIA after 12 weeks of CyA therapy. Similarly, changes in IgG-CIC were not demonstrated with CyA therapy. No apparent decrease in IgG-CIC or IgA-CIC was observed with placebo treatment. Our study suggests that immunomodulation by CyA therapy does not affect the IgA-CIC and IgG-CIC levels in patients with IgA nephropathy.

Adult↗
PubMed1991

Histoplasma capsulatum infection associated with continuous ambulatory peritoneal dialysis.

Fungal infection has become increasingly more important in patients undergoing continuous ambulatory peritoneal dialysis. We report here a case of Histoplasma capsulatum infection in such a Hong Kong Chinese patient who presented with fever and peritonitis. Histoplasma capsulatum was isolated from the dialysis fluid and histoplasma antibody was detected in the serum. The patient responded to the combined treatment of fluconazole, 5-flurocytosine and amphotericin B. This is the first reported case of histoplasmosis in Hong Kong.

Amphotericin B↗
PubMed1991

Hepatitis C infection among dialysis patients: a comparison between patients on maintenance haemodialysis and continuous ambulatory peritoneal dialysis.

Three hundred and thirty-nine dialysis patients from two centres (278 patients on continuous ambulatory peritoneal dialysis (CAPD) and 61 on maintenance haemodialysis (HD) were tested for antibody against hepatitis C virus (anti-HCV) using first-generation enzyme immunoassay kits (Ortho Diagnostics). Anti-HCV was detected in five (1.8%) CAPD patients and ten (16.4%) HD patients (P less than 0.00001). Anti-HCV was confirmed to be positive in three (1.1%) CAPD patients and eight (13.2%) HD patients using neutralisation enzyme immunoassay kits (Abbott Laboratories). The marked difference in prevalence of anti-HCV among CAPD and HD patients was related to a significantly greater transfusion requirement of the HD patients. All the anti-HCV positive patients had been transfused. The risk of HCV infection was significantly increased in those who had received more than five units of blood. Four (26.7%) anti-HCV positive patients had one or more episodes of elevated serum alanine aminotransferase (ALT) values.

Adult↗
PubMed1991

Hepatitis C in renal transplant recipients.

Sera from 130 renal transplant recipients were tested for antibody to hepatitis C virus (anti-HCV). Anti-HCV was detected in 6.2% of patients: 15.4% of patients who had maintenance hemodialysis (HD) and 2.2% of those who had continuous ambulatory peritoneal dialysis (CAPD) before transplantation (P less than 0.05). The similarity in prevalence of anti-HCV with patients currently on dialysis and the absence of transfusion during posttransplant follow-up suggest that most patients acquired HCV infection through transfusion during dialysis. The proportion of anti-HCV-positive patients who had one or more episodes of elevation in serum transaminase level was similar to that of hepatitis B surface antigen (HBsAg)-positive patients, 75% vs. 72.2%. However, anti-HCV was only detected in 25% of HBsAg-negative patients who had recurrent elevations in serum transaminase level. It is not clear whether the low prevalence of anti-HCV in these patients is related to the presence of other non-A, non-B hepatitis virus (es) or a decrease in titer of anti-HCV secondary to immunosuppression posttransplantation.

Adolescent↗