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Biomedical subjects

W Fong

Publications and source records attributed to W Fong.

At least 19 recordsLinked to original sources
PubMed2001

Purification and characterization of grass carp mitochondrial aldehyde dehydrogenase.

The molecular biology and enzymology of aldehyde dehydrogenase (ALDH) have been extensively investigated. However, most of the studies have been confined to the mammalian forms, while the sub-mammalian vertebrate ALDHs are relatively unexplored. In the present investigation, an ALDH was purified from the hepatopancreas of grass carp (Ctenopharygodon idellus) by affinity chromatographies on alpha-cyanocinnamate-Sepharose and Affi-gel Blue agarose. The 800-fold purified enzyme had a specific activity of 4.46 U/mg toward the oxidation of acetaldehyde at pH 9.5. It had a subunit molecular weight of 55000. Isoelectric focusing showed a single band with a pI of 5.3. N-terminal amino acid sequencing of 30 residues revealed a positional identity of approximately 70% with mammalian mitochondrial ALDH2. The kinetic properties of grass carp ALDH resembled those of mammalian ALDH2. The optimal pH for the oxidation of acetaldehyde was 9.5. The K(m) values for acetaldehyde were 0.36 and 0.31 microM at pH 7.5 and 9.5, respectively. Grass carp ALDH also possessed esterase activity which could be activated in the presence of NAD(+).

Aldehyde Dehydrogenase↗
PubMed2001

Determination of right ventricular ejection fraction from reprojected gated blood pool SPET: comparison with first-pass ventriculography.

Gated blood pool (GBP) studies are widely available and relatively inexpensive. We have previously published a simple and convenient method for measuring left ventricle ejection fraction (EF) with increased accuracy from single-photon emission tomography (SPET) GBP scans. This paper describes an extension of this method by which right ventricular EF may also be measured. Gated SPET images of the blood pool are acquired and re-oriented in short-axis slices. Counts from the left ventricle are excluded from the short-axis slices, which are then reprojected to give horizontal long-axis images. Time-activity curves are generated from each pixel around the right ventricle, and an image is created with non-ventricular pixels "greyed out". This image is used as a guide in drawing regions of interest around the right ventricle on the end-diastolic and end-systolic long-axis images. In 28 patients, first-pass ventriculography studies were acquired followed by SPET GBP scans. The first-pass images were analysed a total of four times by two observers and the SPET images were analysed three times each by two observers. The agreement between the two techniques was good, with a correlation coefficient of 0.72 and a mean absolute difference between first-pass and reprojected SPET EFs of 4.8 EF units. Only four of the 28 patients had a difference of greater than 8 EF units. Variability was also excellent for SPET right ventricular EF values. Intra-observer variability was significantly lower for SPET than for first-pass EFs: standard error of the estimate (SEE)=5.1 and 7.3 EF units, respectively (P<0.05). Inter-observer variability was comparable in the two techniques (SEE=5.2 and 6.9 EF units for SPET and first-pass ventriculography, respectively).

Adult↗
PubMed1999

Synergism of energy starvation and dextran-conjugated doxorubicin in the killing of multidrug-resistant KB carcinoma cells.

Here we report that 2-deoxyglucose/Na azide treatment and free/conjugated doxorubicin are synergistic in cell killing. As demonstrated by fluorescence confocal microscopy, KB-V1 cells retained more conjugated doxorubicin than free doxorubicin. Verapamil or 2-deoxyglucose/Na azide enhanced only the retention of the free drug and the small (<70 kDa) conjugates, indicating that P-glycoprotein (P-gp) is not effective against large conjugates. Conjugated doxorubicin was excluded from nuclei. Initially both free and conjugated doxorubicin accumulated in cytoplasmic organelles. Upon 2-deoxyglucose/Na azide treatment, fluorescence labeling of organelles dissipated. Prolonged (24 h) incubation of conjugate-preloaded cells resulted in redistribution of some of the organelle-associated fluorescence to nuclei, suggesting decoupling. The appearance of free doxorubicin was confirmed by capillary electrophoresis. 2-Deoxyglucose/Na azide treatment also retarded decoupling. Our results suggest that energy starvation, in addition to increasing cellular retention of P-gp substrates, may affect cellular fate of conjugated drugs with a possible enhancing effect in cancer cell killing.

Antineoplastic Agents↗
PubMed1999

[An investigation of the polymorphism of HLA class II alleles in the Han population in Hubei Province of China].

OBJECTIVE: To investigate the polymorphism of HLA class II alleles in the Han population in Hubei province. METHODS: The alleles of DRB1*(n=168), DQB1*(n=160) and DPB1*(n=93) were typed by using the polymerase chain reaction/sequence specific primer(PCR/SSP) and polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) techniques. RESULTS: 39 HLA-DRB1, 15 DQB1 and 17 DPB1 alleles were found. Alleles with higher frequencies are DRB1*0901 (GF=14%), *1501(GF=11.3%), *0301(GF=7.1%), *0803(GF=4.8%); DQB1*0301(GF=18.8%), *0303(GF=18.4%), *0201(GF=10%), *0302(GF=8.4%); DPB1*0501(GF=31.2%), *0401(GF=15.1%), *0201(GF=14%), *0402(GF=11.8%), respectively. As compared with Caucasians, the Han people in Hubei province have higher gene frequencies of DRB1*0901, *1001, *0803; DQB1*0303, *0502 and DPB1*0501, *0202; and lower gene frequencies of DRB1*0301, *0401, *1301; DQB1*0201, *0603 and DPB1*0401, suggesting that Hubei Hans have their own layout of HLA class II allele frequencies. CONCLUSION: These data may serve as normal reference values for the Han population in south China.

Alleles↗
PubMed1998

CT-simulator based brachytherapy planner: seed localization and incorporation of biological considerations.

Radiation dose prescription, interpretation, and planning can be problematic for brachytherapy due to high spatial heterogeneity, varying and various dose rates, absence of superimposed calculated isodose distributions onto affected tissues, and lack of dose volume histograms. A new treatment planner has been developed to reduce these limitations in brachytherapy planning. The PC-based planning system uses a CT-simulator to sequentially scan the patient to generate orthogonal images (to localize seed positions) and subsequently axially scan the patient. This sequential scanning procedure avoids using multiple independent patient scans, templates, external frames, or fiducial markers to register the reconstructed seed positions with patient contours. Dose is computed after assigning activity to (low dose rate) Ir192, linear Cs137, or I125 seeds or dwell times (high dose rate) to the Ir192 source. The planar isodose distribution is superimposed onto axial, coronal, or sagittal views of the tissues following image reconstruction. The treatment plan computes (1) direct and cumulative volume dose histograms for individual tissues, (2) the average, standard deviation, and coefficient of skewness of the dose distribution within individual tissues, (3) an average (over all tissue pixels) survival probability (S) and average survival dose DASD for a given radiation treatment, (4) normal tissue complication probability (NTCP) delivered to a given tissue. All four computed quantities account for dose heterogeneity. These estimates of the biological response to radiation from laboratory-based studies may help guide the evaluation of the prescribed low- or high-dose rate therapy in retrospective and prospective clinical studies at a number of treatment sites.

Brachytherapy↗
PubMed1998

A tobacco and alcohol use profile of San Francisco's Chinese community.

Relatively little is known about Asian American tobacco and alcohol use patterns. This is particularly true of Chinese living in the United States--either U.S.-born or non-U.S.-born Chinese. This article presents data from a research project studying tobacco and alcohol use patterns in San Francisco's Chinese community. Data were secured both from focus groups and a self-report telephone survey of a random sample of 1,808 Chinese residents in San Francisco. This results indicate that the prevalence of both tobacco and alcohol use is lower for San Francisco's Chinese population than for the general population. Moreover, those persons who report smoking tend to be different from those who report consuming alcohol. The study concludes that specific, culturally relevant tobacco and alcohol prevention programs should be designed to better reach this target population.

Adolescent↗
PubMed1998

Optimization in hybridoma cell culture.

Based on the formation kinetics of monoclonal antibody, the bench-scale culture of hybridoma cells in a bioreactor was optimized by the application of perfusion culture mode, the supplement of potassium acetate, and the fortification of nutrients. When the bioreactor was operated with the daily perfusion of medium of 1/2 working volume, viable cell density in bioreactor was 11 x 10(5) cells/ml and antibody concentration 28 mg/L. After supplement with 1 g/L potassium acetate, the cell density kept constant and antibody production was improved to 38 mg/L. The fortification of nutrients such as amino acids and vitamins raised the cell density up to 42 x 10(5) cells/ml and, responsively, antibody concentration to 94 mg/L.

Animals↗
PubMed1997

Budd-Chiari syndrome: diagnosis with ultrasound and nuclear medicine calcium colloid liver scan following non-diagnostic contrasted CT scan.

Budd-Chiari syndrome is a rare condition characterized by thrombosis within the hepatic veins and inferior vena cava. A case of Budd-Chiari syndrome is presented in a patient who presented acutely 3 days following laparoscopic cholecystectomy for acalculous cholecystitis. A discussion of pathology and findings on calcium colloid scintigram, CT scan and Doppler ultrasound is provided.

Acute Disease↗
PubMed1995

Identification and characterization of a cell envelope protein of Haemophilus influenzae contributing to phase variation in colony opacity and nasopharyngeal colonization.

Haemophilus influenzae undergoes spontaneous phase variation in colony morphology. Organisms from transparent colonies efficiently colonize the nasopharynx in an infant rat model of H. influenzae carriage, whereas organisms from more opaque colonies are deficient at colonization. A genetic approach relying on the transformability of H. influenzae was used to identify a locus contributing to opacity variation. By screening a library of chomosomal DNA from an opaque variant of strain Rd, it was possible to isolate a single clone capable of transforming a transparent Rd host to a more opaque phenotype. A region containing two genes, designated oapA and oapB, was identified. The deduced amino acid sequence of oapB has similarity to a consensus sequence for bacterial lipoproteins. Genetically defined mutations in oapA were transformed into the transparent Rd to confirm that this gene is required for expression of the transparent colony phenotype. Although oapA lacks a signal sequence, gene fusions to phoA show that OapA is secreted in H. influenzae and undergoes phase variation in expression. Mutagenesis of oapA in strain Rd, and type b strain Eagan, resulted in loss of the ability to colonize the nasopharynx of infant rats. The type b mutant, however, was as virulent as its parent strain when inoculated intraperitoneally. This suggests that the contribution of OapA to pathogenesis is limited to events associated with colonization of the mucosal surface.

Animals↗
PubMed1995

Reversible ischaemia in hypertrophic cardiomyopathy.

Atypical and typical chest pains are common symptoms in patients with hypertrophic cardiomyopathy. Some of these chest pains seem to be caused by ischaemia. It is difficult to objectively demonstrate ischaemia in hypertrophic cardiomyopathy. The first line treatment for chest pain considered to be ischaemic in patients with hypertrophic cardiomyopathy is the use of either a beta blocker or calcium blocker. Septal myectomy can be effective in patients with symptoms refractory to conventional treatment but is associated with significant morbidity and mortality. Recently dual chamber pacing has been advocated in such patients. In some cases dual chamber pacing alleviates chest pain in hypertrophic cardiomyopathy by an anti-ischaemic action, presumably by reducing the left ventricular outflow tract gradient and perhaps by causing an associated decrease in left ventricular outflow tract gradient and perhaps by causing an associated decrease in left ventricular end diastolic pressure.

Adult↗
PubMed1995

[Chemical components of decoction of radix Paeoniae and radix Glycyrrhizae].

Eleven compounds were isolated from the water extract of the decoction of Radix Paeoniae and Radix Glycyrrhizae, namely benzoic acid, formononetin, isoliguiritigenin, liquiritigenin, 4',7-dihydroxyflavone, formononetin-7-glucoside, liquiritin, gallic acid, paeoniflorin, isoliquiritin and glycyrrhizin acid.

Anti-Inflammatory Agents, Non-Steroidal↗