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Biomedical subjects

K M Chow

Publications and source records attributed to K M Chow.

At least 19 recordsLinked to original sources
PubMed2003

Risk factors for thiazide-induced hyponatraemia.

BACKGROUND: Thiazide-induced hyponatraemia is common and potentially life threatening. In the absence of well-defined risk factors for this complication, guidelines for prescribing cannot be established. AIM: To examine whether a subgroup of patients is particularly susceptible to this complication. DESIGN: Retrospective case-control study. METHODS: We defined and recruited cases of symptomatic hyponatraemia that necessitated hospitalization from January 1996 to April 2002. Controls were selected from 8420 patients being prescribed thiazides and seen at the same institution during that period of time. RESULTS: There were 223 cases and 216 controls, with a median 115 days thiazide use. Cases were older than controls (76 +/- 9 vs. 66 +/- 13 years, p < 0.001) and lighter (52.3 +/- 10.3 vs. 63.4 +/- 3 kg, p < 0.001). By univariate analysis, serum potassium level, use of indapamide, elderly home institutionalization and physical immobility were risk factors for thiazide-induced hyponatraemia, but gender, duration of thiazide use, concomitant therapy with loop diuretics, angiotensin-converting enzyme inhibitors or non-steroidal anti-inflammatory drugs, and renal function were not. By stepwise logistic regression analysis, patient age, body weight and serum potassium were the only independent predictive factors. Each 10-year increment of age was associated with a two-fold increase in risk (hazards ratio 2.14, 95%CI 1.59-2.88). For a 5 kg increment in mass, there was a 27% decrease in odds ratio (odds ratio 0.77, 95%CI 0.68-0.87). One SD increase in serum potassium (0.84 mmol/l) was associated with a 63% decrease in risk (odds ratio 0.37, 95%CI 0.27-0.50; p < 0.0001). DISCUSSION: Hyponatraemia is a common problem after thiazide therapy. Extra caution and close monitoring are warranted when prescribing thiazides for elderly patients with low body mass.

Aged↗
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↗
PubMed2003

Parathyroid hormone and mineral metabolism do not have significant impact on pulse pressure in patients undergoing peritoneal dialysis.

BACKGROUND: Pulse pressure, a surrogate for arterial stiffness, has been shown to have substantial impact on predicting patient mortality. Excess cardiac risk in the end-stage renal disease population could be mediated by elevated arterial stiffness, which might in turn result from secondary hyperparathyroidism and abnormal calcium metabolism. METHODS: A cross-sectional study was carried out to examine a possible relationship between pulse pressure and secondary hyperparathyroidism among 126 prevalent patients undergoing continuous ambulatory peritoneal dialysis. RESULTS: The mean values for calcium and intact parathyroid hormone level were 2.48 mmol/l and 50.5 pmol/l, respectively. No correlation was found between pulse pressure and the plasma PTH levels (r = -0.15, p = 0.11) or calcium-phosphorus product (r = -0.08, p = 0.38). In a multivariate regression analysis, on the other hand, elevated pulse pressure was directly associated with age (2.1 mmHg per 10-year increase) and the presence of diabetes mellitus (6.9 mmHg) (both p < 0.001). Pulse pressure was also inversely associated with hemoglobin level. CONCLUSION: The magnitude of arterial pulse pressure in a peritoneal dialysis population was not significantly affected by parathyroid disease and alterations in mineral metabolism with end-stage renal disease. In agreement with similar observations in hemodialysis populations, it is postulated that abnormalities in conduit vessel stiffness (as measured by pulse pressure) are substantially caused by atherosclerosis, in which intimal calcification (as distinct from medial calcification in the context of hyperparathyroidism) plays a more important role.

Adult↗
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↗