Search PubMed⌕ Search

Biomedical subjects

K M Chow

Publications and source records attributed to K M Chow.

At least 19 recordsLinked to original sources
PubMed2003

Is there a survival advantage in Asian peritoneal dialysis patients?

Over the last decade, epidemiological surveys and qualitative research literature have demonstrated and validated a better survival in the Asian peritoneal dialysis population. This review summarizes the current understanding of Asian peritoneal dialysis patient survival and attempts to scrutinize the supposed survival advantage of this population group. We outlined the published peritoneal dialysis survival data from a literature search, with reference to dialysis patient cohorts from 1983 through 2002 for prevalent cases and 1980 through 2002 for incident patients. Two-year and 5-year patient survival rates in excess of 80% and 60% respectively were demonstrated in Asian countries, which compared favorably with the CANUSA, ADEMEX and most Caucasian series. Better end-stage renal disease patient survival is apparent despite a dialysis adequacy disadvantage, for reasons yet to be identified. As is the case of other racial disparities in medical care, such a difference is a product of more than biological differences and include budgetary barrier, health care system and geographic variation, physician bias and statistical pitfalls. Particular efforts should therefore be made to explore the underlying reason(s) for the Asian peritoneal dialysis patient survival advantage. Alternative approach and guidelines to peritoneal dialysis delivery in Asia might be warranted.

Asia↗
PubMed2002

Fusion of qualitative bond graph and genetic algorithms: a fault diagnosis application.

In this paper, the problem of fault diagnosis via integration of genetic algorithms (GA's) and qualitative bond graphs (QBG's) is addressed. We suggest that GA's can be used to search for possible fault components among a system of qualitative equations. The QBG is adopted as the modeling scheme to generate a set of qualitative equations. The qualitative bond graph provides a unified approach for modeling engineering systems, in particular, mechatronic systems. In order to demonstrate the performance of the proposed algorithm, we have tested the proposed algorithm on an in-house designed and built floating disc experimental setup. Results from fault diagnosis in the floating disc system are presented and discussed. Additional measurements will be required to localize the fault when more than one fault candidate is inferred. Fault diagnosis is activated by a fault detection mechanism when a discrepancy between measured abnormal behavior and predicted system behavior is observed. The fault detection mechanism is not presented here.

Air Movements↗
PubMed2002

The relative risk of 'fetal distress' in pregnancy associated with meconium-stained liquor at different gestation.

Pregnancies complicated with meconium-stained liquor are regarded as at risk of fetal distress. Evidence from animal and human studies indicate that passage of meconium may be related to fetal maturity. This retrospective study attempts to quantify the relative risk of non-reassuring cardiotocography or 'fetal distress' in pregnant women complicated by meconium-stained liquor for preterm, term and post-term pregnancies. A total of 9542 singleton pregnancies, delivered in a tertiary obstetric unit in Hong Kong between 1 July 1996 and 31 June 1999, were included in the study. Of these pregnancies, 1946 (20.4%) were identified as having meconium-stained liquor, ranging from thin to thick staining. There was a strong association between incidence of meconium-stained liquor (P < 0.0005) and moderate/thick meconium-stained liquor with advanced gestational age. The incidence of non-reassuring cardiotocography in women presenting with meconium-stained liquor was significantly higher (9.8% vs. 6.4%). The relative risk of non-reassuring cardiotocography in women with meconium-stained liquor increased with more advanced gestation. Close fetal surveillance during labour is required among these pregnancies. Premature labour is associated with higher incidence of fetal distress but the presence of meconium did not pose an additional risk.

Amniotic Fluid↗
PubMed2002

Unusual muscle pain in two patients with diabetic renal failure.

We report on two patients with diabetic muscle infarct, a painful musculoskeletal disorder complicating longstanding diabetes with established microangiopathy. Both patients had renal failure that was treated by dialysis. The underlying pathophysiological process was considered to be an arterial vascular event mediated through ischaemia-reperfusion injury. Clinicians should be alert to this condition. T2-weighted magnetic resonance imaging was valuable in establishing the diagnosis.

Adult↗
PubMed2001

Expression of the acidic stretch of nardilysin as a functional binding domain.

Kinetic evidence suggests an acidic region in nardilysin binds polyamines and acts as a regulatory domain. The binding of approximately 5 mol of spermine/mol of nardilysin was demonstrated. The binding curve was sigmoidal exhibiting an IC(50) of approximately 118 microM and a Hill coefficient of 1.8. Spermine diminished the tryptophan fluorescence of the enzyme and increased its sensitivity to protease V8. The acidic stretch from mouse and human nardilysin were expressed as glutathione transferase fusion proteins. All fusion proteins bound spermine with an IC(50) of 40 to 110 microM. The mouse fusion protein bound approximately 7 mol of spermine exhibiting a sigmoidal binding curve and a Hill coefficient of 1.4. The human acidic stretch, containing fewer acidic residues, bound approximately 5 mol of spermine/mol with a hyperbolic binding curve. Chimeric fusion proteins containing the N-terminus of the mouse acidic region fused to the C-terminus of the human acidic region bound approximately 10 mol of spermine, while the opposite chimera bound approximately 4 mol of spermine/mol. The N-terminal region of the mouse acidic domain binds 3--4 mol spermine/mol exhibiting a Hill coefficient of 1.4, while the same region from human nardilysin binds 1 mol of spermine/mol. Spermine enhanced the sensitivity of the mouse acidic domain, but not the human acidic domain, to protease V8. Together the data support a model where the acidic stretch of nardilysin functions as an autonomous domain.

Amino Acid Sequence↗
PubMed2001

The natural history of immunoglobulin a nephropathy among patients with hematuria and minimal proteinuria.

PURPOSE: To determine the natural history of immunoglobulin (Ig) A nephropathy among patients who presented with hematuria and minimal proteinuria, and factors associated with the development of adverse clinical events, such as proteinuria. SUBJECTS AND METHODS: In Hong Kong, all patients who present with isolated hematuria are referred for renal biopsy after urologic diseases are ruled out. We reviewed the clinical course of 72 consecutive patients with histologically confirmed IgA nephropathy who presented with hematuria and minimal proteinuria (0.4 g/day or less). All patients were normotensive and had normal renal function at presentation. Adverse events were defined as proteinuria greater than 1 g per day, hypertension, or impaired renal function (serum creatinine level 120 micromol/L or estimated creatinine clearance < 70 mL per minute). RESULTS: The mean (+/- SD) age at presentation was 27 +/- 8 years; 56 (78%) were female. Nine patients (13%) had grade 2 histologic lesions. During a median follow-up of 7 years, 32 patients (44%) developed adverse events: 24 (33%) developed proteinuria of 1 g per day or more, 19 (26%) became hypertensive, and 5 (7%) developed impaired renal function. Another 30 patients (42%) had persistently abnormal urinalysis examinations. Only 10 patients (14%) had complete resolution of hematuria. The median time for progression from proteinuria (> l g/day) to renal impairment was 84 months (range 56 to 132). In a multivariate analysis, age at presentation (relative risk [RR] per 10 years of age = 2.0; 95% confidence interval [CI], 1.2 to 3.4) and histologic grade (grade 2 versus grade 1, RR = 4.5; 95% CI, 1.7 to 12) were independent predictors of developing an adverse event. CONCLUSIONS: IgA nephropathy that presents with hematuria and minimal proteinuria is usually a progressive disease. Life-long follow-up with regular monitoring of blood pressure and proteinuria is recommended.

Adolescent↗
PubMed2001

Grading of acute and chronic renal lesions in Henoch-Schönlein purpura.

The renal outcome of 34 patients with Henoch-Schönlein purpura nephritis was assessed clinically and by grading acute and chronic renal lesions using a system we applied to primary IgA nephropathy. On a median follow-up period of 65 months, hypertension and the serum levels of creatinine and proteinuria at the time of renal biopsy were correlated with renal survival. Acute glomerular lesions including mesangial hypercellularity, endocapillary proliferation, necrosis, cellular crescents, and leukocytes infiltration were observed, respectively, in 41%, 12%, 50%, 29%, and 32% of the cases. Of these, only glomerular necrotizing lesion and cellular crescent were correlated with the renal survival. Chronic renal lesions based on a grading system applied to primary IgA nephropathy and assessing the extent of glomerular sclerosis (glomerular grading), of tubular loss and interstitial fibrosis (tubulointerstitial grading), and of hyaline arteriolosclerosis demonstrated correlation between these lesions, as well as with renal survival. On follow-up, these chronic renal lesions were predictors of subsequent clinical events associated with disease progression, such as impaired renal function, significant proteinuria, and development of hypertension. Despite some limitations related to the relatively small size, this series indicates that distinction of acute and chronic lesions of Henoch-Schonlein purpura nephritis is important for both the prognosis and management of patients.

Acute Disease↗
PubMed2001

Clinical course of peritonitis due to Pseudomonas species complicating peritoneal dialysis: a review of 104 cases.

BACKGROUND: Peritonitis due to Pseudomonas species is a serious complication in continuous ambulatory peritoneal dialysis (CAPD) patients. The clinical course of peritonitis due to Pseudomonas complicating CAPD remains unclear. METHODS: All of the Pseudomonas species episodes of peritonitis in our dialysis unit were studied from 1995 to 1999. During this period, there were 859 episodes of peritonitis recorded, 113 of which were caused by the Pseudomonas species. Nine episodes were excluded because they were mixed growth. The remaining 104 episodes in 68 patients were reviewed. RESULTS: The underlying renal diagnosis and prevalence of comorbid conditions of the 68 patients were similar to those found in our entire dialysis population. There was a history of antibiotic therapy within 30 days of the onset of peritonitis due to the Pseudomonas species in 69 episodes (66.3%). In 47 episodes (45.2%) there was a concomitant exit site infection. The overall primary response rate was 60.6% and the complete cure rate was 22.1%. The presence of exit site infection was associated with a lower primary response rate (22 in 47 vs. 41 in 57 episodes, P < 0.01) and a lower complete cure rate (5 in 47 vs. 18 in 57 episodes, P < 0.02). The episodes that had received recent antibiotic therapy had a significantly lower complete cure rate than the de novo cases (8 in 69 vs. 15 in 35 episodes, P < 0.001). Episodes receiving third-generation cephalosporin as part of the initial antibiotic regimen had a significantly higher primary response rate than the ones that initially received aminoglycoside (54 in 81 episodes vs. 8 in 22 episodes, P < 0.05), but their complete cure rates were similar. Twenty-four cases failed to respond to antibiotics and the Tenckhoff catheter was removed. The chance of returning to CAPD was higher when the Tenckhoff catheter was removed on day 10 than on day 15 (9 in 14 cases vs. 5 in 10 cases), although the result was not statistically significant. The Tenckhoff catheter was removed and replaced at another site simultaneously in another 14 cases after the effluent cleared up. None of these patients had a relapse of peritonitis within three months. CONCLUSIONS: Recent antibiotic therapy is the major risk factor for peritonitis due to the Pseudomonas species. Exit site infection and recent antibiotic therapy are associated with poor therapeutic response to antibiotics. When the therapeutic response is suboptimal, early Tenckhoff catheter removal may help preserve the peritoneum for further peritoneal dialysis. Elective Tenckhoff catheter exchange after clearing up the peritoneal dialysis effluent may also reduce the likelihood of relapse. It is desirable to use third-generation cephalosporin in the initial antibiotic regimen for peritonitis treatment in localities with a high incidence of peritonitis due to the Pseudomonas species.

Adult↗
PubMed2001

Reversible renal failure in paroxysmal nocturnal hemoglobinuria.

A Chinese patient with paroxysmal nocturnal hemoglobinuria (PNH) developed acute nonoliguric renal failure with intercurrent urinary tract infection and hemolysis. There was no evidence of renal vein thrombosis. Renal biopsy showed features of acute tubular necrosis (ATN) and hemosiderosis. Magnetic resonance imaging (MRI) showed characteristic features of renal hemosiderosis. The patient was stabilized with temporary hemodialysis and intravenous fluid. The renal function fully recovered 3 weeks later. We review the literature and summarize the clinical features of this disease entity. To our knowledge, this case is the first to report such disorder with thorough investigation including concomitant diagnostic MRI imaging and renal biopsy.

Acute Kidney Injury↗
PubMed2001

Contribution of gene polymorphisms in the renin-angiotensin system to macroangiopathy in patients with diabetic nephropathy.

The renin-angiotensin system is important in the control of hemodynamic status and pathogenesis of macrovascular disease, which is a major cause of morbidity and mortality in patients with type 2 diabetes with nephropathy. Serum angiotensin-converting enzyme (ACE) and angiotensinogen (Atg) levels are related to their respective gene polymorphisms. Seventy patients with type 2 diabetes with overt nephropathy (serum creatinine >/= 1.5 mg/dL) were studied. Serum ACE activity was measured by the spectrophotometric method. ACE deletion/insertion (D/I) and Atg M235T genotypes were determined by polymerase chain reaction. Patients with and without macroangiopathy were compared. Those with macroangiopathy had increased ACE activity (median, 60.9 U/L; range, 37.9 to 100 U/L versus without macroangiopathy, 47.9 U/L; range, 11.2 to 84.5 U/L; P = 0.01) and prevalence of ACE DD/DI genotypes (DD/DI:II: with macroangiopathy, 61%:39% versus without macroangiopathy, 34%:66%; P = 0.03). Multivariate analysis using age; sex; duration of diabetes; glycemic, blood pressure, and lipid level control; serum creatinine level; and presence of the ACE D allele showed that presence of the D allele (P = 0.03; odds ratio, 1.8; confidence interval, 1.1 to 3.1) and serum creatinine level (P = 0.0007) were independent risk factors for macroangiopathy. Association of the D allele became insignificant after serum ACE activity was included in the analysis in which only serum ACE activity (P = 0.004) and serum creatinine level (P = 0.01) were independent risk factors. Neither Atg M235T nor its synergistic effect with the ACE D allele showed an association with macroangiopathy. In conclusion, the ACE D allele is associated with macroangiopathy in Chinese patients with type 2 diabetes with nephropathy. The association is dependent on its effect on serum ACE activity, which is an independent risk factor for the development of macroangiopathy.

Aged↗