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Biomedical subjects

B L Wong

Publications and source records attributed to B L Wong.

15 recordsLinked to original sources
PubMed2001

High-sensitivity determination of the degradation products of chemical warfare agents by capillary electrophoresis-indirect UV absorbance detection.

Capillary electrophoresis coupled with indirect UV absorbance detection was employed for the determination of the chemical warfare agent degradation products: methylphosphonic acid, ethyl methylphosphonate, isopropyl methylphosphonate, and pinacolyl methylphosphonate. Glutamic acid was used as a buffering agent at its isoelectric point (pH 3.22). In its zwitterionic form, glutamic acid does not act as a competing co-anion in the system, thus providing buffering capacity while maintaining high sensitivity. The indirect probe (phenylphosphonic acid) concentration was lowered to 1 mM from the 10 mM in previous literature studies, further enhancing sensitivity. Detection limits of 2 microM were achieved with hydrodynamic injection and up to 100-fold lower using electrokinetic injection. The increased buffering capacity of this system over previous methods led to migration time reproducibility RSD values of 0.18 to 0.22%. This represents a 10-fold improvement in reproducibility over previous studies with comparable or improved sensitivity.

Buffers↗
PubMed2001

3D-QSAR model of flavonoids binding at benzodiazepine site in GABAA receptors.

With flavone as a structural template, three-dimensional quantitative structure-activity relationship (3D-QSAR) studies and ab initio calculations were performed on a series of flavonoids. A reasonable pharmacophore model was built through CoMFA, CoMSIA, and HQSAR analyses and electrostatic potential calculations. A plausible binding mode for flavonoids with GABA(A) receptors was rationalized. On the basis of the commonly recognized binding site, the specific S1 and S2 subsites relating to substituent positions were proposed. The different binding affinities could be explained according to the frontier orbitals and electrostatic potential (ESP) maps. The ESP could be used as a novel starting point for designing more selective BZ-binding-site ligands.

Benzodiazepines↗
PubMed1982

Purification of a lymphoid cell line product with leukocyte inhibitory factor activity.

Leukocyte inhibitory factor (LIF), a lymphokine that inhibits the random and directed migration of polymorphonuclear (PMN) leukocytes, was purified from a human non-T, non-B leukemia cell line (Reh). From 10 liters of serum-free supernatant, 1.3 microgram of protein with LIF activity was obtained by the sequential use of affinity chromatography with concanavalin A-Sepharose, hydrophobic chromatography with hexylagarose, and gel filtration chromatography. The specific activity of LIF recovered represented an 80,000-fold purification over that of the initial crude serum-free supernatants, and the preparation at that point was estimated to be 80--90% pure. To both assess the purity of the preparation and provide a further purification step, Reh LIF activity recovered by the above procedures was subjected to isoelectric focusing. One major stainable protein band was identified; its isoelectric point was pH 5.4--5.5. Gels run in parallel for recovery of biologic activity revealed only one region (pH 5.4--5.5) with ability to inhibit PMN leukocyte migration. Iodination of Reh LIF resulted in a loss of biologic activity, but isoelectric focusing of this material revealed one major 125I-labeled band (pH 5.1) and several minor bands. The coincidence of biologic LIF activity with one stainable protein band as identified by isoelectric focusing implies that the final product may be homogeneous.

Cell Line↗
PubMed1970

Shear degradation of fibrinogen in the circulation.

Plasma fibrinogen in vitro suffers a loss in clottability due to shearing. From calculation of the mass average shear to which plasma is subjected in the circulation, it is estimated that the half-life of fibrinogen is 4 days. This is in excellent agreement with reports that the half-life of fibrinogen in the circulatory system is 4 to 5 days. Hence shearing may be the mechanism for fibrinogen degradation in the circulatory system.

Aorta↗
PubMedDate not supplied

Steroid therapy and cardiac function in Duchenne muscular dystrophy.

Duchenne muscular dystrophy leads to progressive deterioration in skeletal and cardiac muscle function. Steroids prolong ambulation and improve respiratory muscle strength. The authors hypothesized that steroid treatment would stabilize cardiac muscle function. Echocardiograms performed from 1997 to 2004 for 111 subjects 21 years of age or younger with Duchenne muscular dystrophy were restrospectively reviewed. The medical record was reviewed for steroid treatment. Untreated and steroids-treated subjects did not differ in age, height, weight, body mass index, systolic and diastolic blood pressure, or left ventricular mass. The shortening fraction was lower in the untreated group. Of those treated, 29 received prednisone and 19 received deflazacort. There was no difference in the shortening fraction between the two treated subgroups. Treated subjects not receiving steroids still had a normal shortening fraction, which was no different from the shortening fraction of those still receiving treatment. As compared with the treated subjects, the untreated subjects 10 years of age or younger were 4.4 times more likely to have a shortening fraction less than< 28% (p = 0.03), and the untreated subjects older than 10 years were 15.2 times more likely to have a shortening fraction less than< 28% (p < 0.01). This retrospective study suggests that the progressive decline in cardiac function of patients with Duchenne muscular dystrophy can be altered by steroid treatment. The effect appears to be sustained beyond the duration of treatment and independent of steroid type.

Adolescent↗