Biomedical subjects

W C Mak

Publications and source records attributed to W C Mak.

3 recordsLinked to original sources

PubMed2006

Biosensor for rapid determination of 3-hydroxybutyrate using bi-enzyme system.

A bi-enzyme-based Clark electrode was developed for the determination of 3-hydroxybutyrate. This sensor is based on the specific dehydrogenation by 3-hydroxybutyrate dehydrogenase (HBDH, E.C. 1.1.1.30) in combination with salicylate hydroxylase (SHL E.C. 1.14.13.1). The enzymes were entrapped by a poly(carbamoyl) sulfonate (PCS) hydrogel on a Teflon membrane. The principle of the determination scheme is as follows: the specific detecting enzyme, HBDH, catalyses the specific dehydrogenation of 3-hydroxybutyrate consuming NAD(+). The products, NADH, initiate the irreversible decarboxylation and the hydroxylation of salicylate by SHL in the presence of oxygen. SHL forces the equilibrium of dehydrogenation of 3-hydroxybutyrate by HBDH to the product side by consuming NADH. Dissolved oxygen acts as an essential material for SHL during its enzymatic reactions. This results in a detectable signal due to the SHL-enzymatic consumptions of dissolved oxygen in the measurement of 3-hydroxybutyrate. Interferences from different amino acids and electroactive substances were found to be minimal due to the specificity of HBDH and the application of a Teflon membrane. The sensor has a fast response (2s) and short recovery time (2 min) with a linear range between 8 and 800 microM 3-hydroxybutyrate and a detection limit of 3.9 microM. A good agreement (R(2)=0.9925) with theoretical calculation was obtained in spiked serum sample measurements.

3-Hydroxybutyric Acid↗

PubMed2005

Kawasaki disease in Hong Kong, 1994 to 2000.

OBJECTIVE: To describe the epidemiology, clinical characteristics, and management of Kawasaki disease in children in Hong Kong. DESIGN: Retrospective survey of medical records from July 1994 to June 1997, and prospective data collection from July 1997 to June 2000. SETTING: Hospitals with a paediatric unit in Hong Kong. PATIENTS: Patients diagnosed with Kawasaki disease between July 1994 and June 2000 in public hospitals in Hong Kong. MAIN OUTCOME MEASURES: Incidence of Kawasaki disease and coronary artery aneurysm rates. RESULTS: A total of 696 cases of Kawasaki disease were reported. There were 435 (62.5%) boys and 261 (37.5%) girls giving a male to female ratio of 1.7:1. The age ranged from 1 month to 15 years 5 months with a median of 1.7 years. Infants (<1 year) constituted the largest group of patients (223, 32.0%) and overall, 638 (91.7%) were younger than 5 years. Skin rash, conjunctivitis, and oral signs were among the principal clinical features present in over 80% of cases. Prominent cervical lymph nodes larger than 1.5 cm were less commonly found (24%). Coronary artery aneurysms or ectasia were present in 15.7% (109/696), 8.5% (59/696), and 5.0% (35/696) of patients at 2, 4, and 8 weeks, respectively. The incidence of Kawasaki disease per 100,000 children under 5 years was significantly higher in the prospective study period than in the retrospective period (39 vs 26, P<0.001). CONCLUSION: The incidence of Kawasaki disease is high in Hong Kong and is 39 per 100,000 children below 5 years of age. The coronary artery aneurysm prevalence is 5%. Intravenous gamma-globulin and high-dose aspirin is the mainstay of treatment.

Adolescent↗

PubMed2004

Nanoscale surface engineered living cells with extended substrate spectrum.

We report on cell surface engineering of living microorganisms by using Layer-by-Layer (LbL) technology to extend the substrate spectrum. The yeast Arxula adeninivorans LS3 (Arxula) was employed as a model organism and biological template. By using LbL technology, Arxula cells were encapsulated by polyelectrolyte and enzyme layers. The biological activity of the Arxula was retained after the encapsulation process. The polymeric capsule surrounding the Arxula provides a stable interface for surface engineering of living cells. LbL of polyelectrolytes followed by an enzyme layer of lactate oxidase were assembled. The outer enzyme layer provides an additional biological function for Arxula to convert the unfavourable substrate lactate into the favourable substrate pyruvate, thus extending the substrate spectrum of the organism. Moreover, capsule stability and enzyme conjugate stability of the surface engineered Arxula were studied.

Journal Article↗