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Biomedical subjects

B B Wang

Publications and source records attributed to B B Wang.

At least 19 recordsLinked to original sources
PubMed2001

An evaluation of the performance of cDNA microarrays for detecting changes in global mRNA expression.

The cDNA microarray is one technological approach that has the potential to accurately measure changes in global mRNA expression levels. We report an assessment of an optimized cDNA microarray platform to generate accurate, precise and reliable data consistent with the objective of using microarrays as an acquisition platform to populate gene expression databases. The study design consisted of two independent evaluations with 70 arrays from two different manufactured lots and used three human tissue sources as samples: placenta, brain and heart. Overall signal response was linear over three orders of magnitude and the sensitivity for any element was estimated to be 2 pg mRNA. The calculated coefficient of variation for differential expression for all non-differentiated elements was 12-14% across the entire signal range and did not vary with array batch or tissue source. The minimum detectable fold change for differential expression was 1.4. Accuracy, in terms of bias (observed minus expected differential expression ratio), was less than 1 part in 10 000 for all non-differentiated elements. The results presented in this report demonstrate the reproducible performance of the cDNA microarray technology platform and the methods provide a useful framework for evaluating other technologies that monitor changes in global mRNA expression.

Analysis of Variance↗
PubMed2001

Management strategies and financial performance in rural and urban hospitals.

This study identifies the difference in financial performance between rural and urban hospitals and examines whether or not that difference may be attributed to the emphasis of revenue enhancement over cost management strategies. Hospitals in Virginia were included in this study except for the two state university medical centers. Rural and urban hospitals were compared on 10 performance indicators grouped into four categories: revenues, costs, profits, and productivity. The results suggest that rural hospital profitability is dependent on cost management. Since rural hospitals achieved lower cost, better efficiency and productivity level than urban hospitals in Virginia, they demonstrate a significant higher level of profit.

Analysis of Variance↗
PubMed2001

Managed care, vertical integration strategies and hospital performance.

OBJECTIVE: The purpose of this study is to examine the association of managed care with hospital vertical integration strategies, as well as to observe the relationships of different types of vertical integration with hospital efficiency and financial performance. DATA AND METHODS: The sample consists of 363 California short-term acute care hospitals in 1994. Linear structure equation modeling is used to test six hypotheses derived from the strategic adaptation model. Several organizational and market factors are controlled statistically. PRINCIPAL FINDINGS: Results suggest that managed care is a driving force for hospital vertical integration. In terms of performance, hospitals that are integrated with physician groups and provide outpatient services (backward integration) have better operating margins, returns on assets, and net cash flows (p < 0.01). These hospitals are not, however, likely to show greater productivity. Forward integration with a long-term-care facility, on the other hand, is positively and significantly related to hospital productivity (p < 0.001). Forward integration is negatively related to financial performance (p < 0.05), however, opposite to the direction hypothesized. CONCLUSIONS: Health executives should be responsive to the growth of managed care in their local market and should probably consider providing more backward integrated services rather than forward integrated services in order to improve the hospital's financial performance in today's competitive health care market.

Delivery of Health Care, Integrated↗
PubMed2001

Disaster epidemiology and medical response in the Chi-Chi earthquake in Taiwan.

STUDY OBJECTIVE: We examine the mortality and morbidity associated with earthquakes in the Chi-Chi earthquake in Taiwan in 1999. METHODS: Crude casualty data were collected from the reports of the government, local health bureaus, and 97 hospitals. The demographic data from the annual report of the Department of Interior were also employed for data analysis. Cross tables showing incidence of deaths and injuries by age, sex, time, and geographic distribution were generated to compare the mortality among different subgroups. Multiple regression models were established to explore the risk factors related to the mortality caused by earthquakes. RESULTS: The following results were found: the mortality rate increased with proximity to the epicenter, mortality was higher among the elderly than among young people, 30% of the victims died from head injuries caused by the collapse of dwellings, and the peak of medical demand was 12 hours after the earthquake and significantly increased demand for care lasted as long as 3 days. Furthermore, the regression model indicated that 78.5% of the variation of locality-age-sex-specific mortality was explained by the intensity of the earthquake, age, population density, distance to epicenter, medical beds per 10,000 people, and physicians per 10,000 people. CONCLUSION: The results implied that fragile minorities, specifically the elderly and children, require special consideration and attention in regard to disaster rescue and emergency medical care allocation. Epidemiologic analysis can guide disaster response and preparation.

Adolescent↗
PubMed2001

Allitridum mimics effect of ischemic preconditioning by activation of protein kinase C.

AIM: To investigate whether allitridum has the effect of pharmacological preconditioning and whether protein kinase C (PKC) plays a role in myocardial protection. METHODS: Thirty-four isolated rabbit hearts which subjected to 30 min of regional myocardial ischemia and 2 h reperfusion, were randomly divided into 5 groups: control group, ischemic preconditioning (PC) group, allitridum (A) group, polymyxin B (Poly B) group, allitridum + polymyxin B (A + Poly B) group. Infarct size was determined by triphenyltetrazolium staining. RESULTS: Pharmacological preconditioning in hearts with a 5 -min allitridum infusion 10 min before the prolonged regional ischemia resulted in significantly smaller infarcts (7 % +\- 6 % of risk area) than in control hearts (25 % +\- 7 %, P < 0.05). There is no significant difference in infarct size between (A+Poly B) group and control hearts (23 % +\- 5 % vs 25 % +\- 7 %, P > 0.05). CONCLUSION: These data indicate that allitridum can precondition rabbit ischemic myocardium and this protection can be effectively blocked by administration of Poly B, an inhibitor of PKC, implying that PKC has an important role in preconditioning.

Allyl Compounds↗
PubMed2000

Exploiting polymerase promiscuity: A simple colorimetric RNA polymerase assay.

We developed a convenient colorimetric assay for monitoring RNA synthesis from DNA-dependent RNA polymerases (DdRp) and viral RNA-dependent RNA polymerases (RdRp). ATP and GTP with a p-nitrophenyl moiety attached to the gamma-phosphate were synthesized (PNP-NTPs). These PNP-NTPs can be used for RNA synthesis by several RNA polymerases, including the RdRps from brome mosaic virus and bovine viral diarrhea virus and the DdRps from bacteriophage T7 and SP6. When the polymerase reactions were performed in the presence of alkaline phosphatase, which digests the p-nitrophenylpyrophosphate side-product of phosphoryl transfer to the chromogenic p-nitrophenylate, an increase in absorbence at 405 nm was observed. These nucleotide analogues were used in continuous colorimetric monitoring of polymerase activity. Furthermore, the PNP-NTPs were found to be stable and utilized by RNA polymerases in the presence of human plasma. This simple colorimetric polymerase assay can be performed in a standard laboratory spectrophotometer and will be useful in screens for inhibitors of viral RNA synthesis.

Adenosine Triphosphate↗
PubMed2000

Assessment of similarity between dissolution profiles.

In vitro dissolution equivalence has been assessed through profile comparison between the test and reference formulations for postapproval changes. Functions of the absolute mean difference and average squared mean differences were two of the often-used criteria to evaluate distance or similarity between general profiles. The two functions and their method of moment estimators are studied in this paper as an application to similarity assessment of two dissolution profile. Due to the complexity of the distributions of these estimators, the confidence intervals obtained from the bootstrap method were used for testing the hypothesis of dissolution similarity. The size and power of two procedures are examined with a simulation study. A numerical example is used to illustrate the application of the procedures.

Algorithms↗
PubMed1999

Trends in hospital efficiency among metropolitan markets.

This study evaluates trends in efficiency among American hospital markets. A total of 6010 hospitals were identified for use in the analysis from the American Hospital Association's Annual Surveys for 1989 and 1993. Using data envelopment analysis (DEA), a longitudinal study of hospital efficiency was conducted on all 314 metropolitan markets in the United States. Results suggest that large hospital markets generally demonstrated higher inefficiency. The major inefficiencies exist in the availability of hospital services, the number of operating beds, the utilization of hospital staffing and operating expenses. Consequently, the large hospital market had a significant excess of health manpower that resulted in inefficiency that amounted to approximately $23 billion. From a policy perspective, this study has shed some light on the need to establish more specific policies to address inefficiency in the health care industry.

American Hospital Association↗
PubMed1998

Molecular and biochemical basis of galactosemia.

Galactosemia is a clinically heterogeneous autosomal recessive inborn error of metabolism caused by deficiency of galactose-1-phosphate uridylyltransferase (GALT). Despite the numerous point mutations identified in the GALT gene, the prevalence of these mutations in different ethnic groups has not been studied. Reports on genotype/phenotype correlation are not consistent due to the small sample sizes studied and the lack of a sensitive enzyme assay. We applied multiplex PCR/ASO dot blot analysis to screen 293 galactosemic patients for 17 known point mutations in exons 5, 6, and 10. Our data demonstrate that only 7 of these mutations were detected in our patients, accounting for 65% of the GALT mutant alleles. Although Q188R is the most common mutation in Caucasian and Hispanic patients, the S135L mutation is most common in African-Americans. Another mutation, F171S, was observed only among African-American patients. An improved, sensitive, and accurate method was used to measure GALT activity in patient's red blood cells. The results indicated that patients homozygous for Q188R have no enzyme activity while those homozygous for S135L had residual enzyme activity. Interestingly, both Q188R/S135L and S135L/F171S compound heterozygotes demonstrated zero enzyme activity. Overall, 85% of Q188R compound heterozygotes also did not have any enzyme activity, whereas the remaining Q188R and the majority of S135L compound heterozygotes expressed variable amounts of GALT activity. We speculate that heterodimeric subunit interaction plays an important role in determining the overall enzymatic activity. Various genotypes thus result in biochemical and clinical heterogeneity among the patients.

Amino Acid Substitution↗
PubMed1996

Neutrophil rolling altered by inhibition of L-selectin shedding in vitro.

The L-selectin adhesion molecule is involved in guiding leukocytes to sites of inflammation. L-selectin is cleaved by an unusual proteolytic activity at a membrane-proximal site resulting in rapid shedding from the cell surface. Although it has been demonstrated that L-selectin mediates, in part, the early event of leukocyte rolling under hydrodynamic flow, the contribution of shedding to L-selectin function has remained unknown. Here we show that hydroxamic acid-based metalloprotease inhibitors block L-selectin downregulation from the cell surface of stimulated neutrophils, without affecting Mac-1 mobilization or general neutrophil activation, and inhibit cleavage of L-selectin in a cell-free system. Unexpectedly, the hydroxamic acid-based inhibitors reduced neutrophil rolling velocity under hydrodynamic flow, resulting in increased neutrophil accumulation. These results suggest that L-selectin is cleaved in seconds--much faster than previously suspected--during the process of rolling under hydrodynamic flow, and that shedding of L-selectin may contribute significantly to the velocity of leukocyte rolling. L-selectin shedding during rolling interactions may be physiologically important for limiting leukocyte aggregation and accumulation at sites of inflammation.

Cell Adhesion↗
PubMed1996

Identification of a nuclear-specific cyclophilin which interacts with the proteinase inhibitor eglin c.

We have identified a novel human cyclophilin (hCyP-60) which interacts with the proteinase inhibitor eglin c using the yeast two-hybrid system. A cDNA isolated from a Raji B lymphocyte library reveals a domain showing sequence similarity to known cyclophilins flanked by unique N- and C-terminal residues. In addition, hCyP-60 contains a tyrosine residue (Tyr 389) instead of a tryptophan residue found in most eukaryotic cyclophilins at a position important for cyclosporin binding. Northern and Western analysis reveal widespread expression with considerable tissue-specific variation. Specifically, the highest levels of mRNA are detected in the thymus, pancreas, testis, and K-562 cell line, while the most protein is detected in the kidney. Immunohistochemistry indicates a nuclear-specific localization both in transfected cells and tissue sections. hCyP-60's specific subcellular localization and conserved amino acid sequence suggest that it may play a specific role in the nucleus.

Amino Acid Isomerases↗
PubMed1996

Human cathepsin O2, a matrix protein-degrading cysteine protease expressed in osteoclasts. Functional expression of human cathepsin O2 in Spodoptera frugiperda and characterization of the enzyme.

Cathepsin O2, a human cysteine protease predominantly present in osteoclasts, has been functionally expressed in Spodoptera frugiperda Sf9 cells using the Autographa californica nuclear polyhedrosis virus. Following in vitro activation at pH 4.0 with pepsin, active enzyme with an apparent molecular weight of 29,000 was obtained. N-terminal sequencing revealed the typical processing site for cysteine proteases of the papain family with a proline in the position adjacent to the N-terminal alanine residue. The S2P2 subsite specificity of human cathepsin O2 is similar to cathepsin S but distinguished from cathepsins L and B. Similar to cathepsin S, cathepsin O2 is characterized by a bellshaped pH activity profile and is stable at pH 6.5 for 30 min at 37 degrees C. Cathepsin O2 is further distinguished by its potent collagenolytic activity against Type I collagen between pH 5 and 6, and elastinolytic activity against insoluble elastin at pH 7.9. Its capacity to efficiently degrade Type I collagen and its high expression in osteoclasts suggest that cathepsin O2 may play a major role in human osteoclastic bone resorption.

Amino Acid Sequence↗
PubMed1995

Prenatal identification of i(Yp) by molecular cytogenetic analysis.

An i(Yp) is a rare marker chromosome. We present a case of de novo 46,X,i(Yp) detected prenatally in an amniotic fluid specimen. Fluorescence in situ hybridization (FISH) studies using a panel of Y-specific biotinylated DNA probes identified the marker chromosome as i(Yp). Comparative genomic hybridization (CGH) studies further confirmed the diagnosis. Upon pregnancy termination, external examination of the fetus revealed a generally well-developed male fetus with slight facial dysmorphism and prominent rocker-bottom feet. The molecular cytogenetic data in this case proved very useful in genetic counselling and served as a good example illustrating the important role of molecular techniques for accurate identification of marker chromosomes.

Adult↗
PubMed1993

A homeotic gene cluster patterns the anteroposterior body axis of C. elegans.

In insects and vertebrates, clusters of Antennapedia class homeobox (HOM-C) genes specify anteroposterior body pattern. The nematode C. elegans also contains a small cluster of HOM-C genes, one of which has been shown to specify positional identity. Here we show that two additional C. elegans HOM-C genes also specify positional identity and that together these three HOM-C genes function along the anteroposterior axis in the same order as their homologs in other organisms. Thus, HOM-C-based pattern formation has been conserved in nematodes despite the many differences in morphology and embryology that distinguish them from other phyla. Each C. elegans HOM-C gene is responsible for a distinct body region; however, where their domains overlap, two HOM-C genes can act together to specify the fates of individual cells.

Amino Acid Sequence↗
PubMed1993

Discrepancy in mosaic findings between chorionic villi and amniocytes: a diagnostic dilemma involving 45,X, 46,XY, and 47,XYY cell lines.

Discrepancies between cytogenetic findings in chorionic villi (CV) and fetal tissue have been reported. Several embryogenic models have been proposed to explain such discrepancies. We describe a case in which analysis of the direct preparation showed 24% 45,X and 76% 46,XY, with 43% 45,X and 57% 46,XY cells in cultured villi. Amniocentesis results disclosed 97% 46,XY and 3% 47,XYY. No 45,X cells were found in cultured amniocytes. These findings suggest that nondisjunction occurred early in postzygotic cleavage resulting in 3 cell lines. It is postulated that through selection, the less viable 45,X cells died out among those destined to become fetus proper but persisted among the cytotrophoblast and extraembryonic mesoderm cells. While there is probably selection against all aneuploid cell lines, 47,XYY cells are more likely to survive in the fetus. An explanation for the lack of 47,XYY cells in the CV might be simply that the tissue sampled was not representative of the cytogenetic make up of the entire placenta.

Adult↗
PubMed1993

Mosaicism in chorionic villus sampling: an analysis of incidence and chromosomes involved in 2612 consecutive cases.

The incidence of chromosome mosaicism was analysed in 2612 consecutive chorionic villus sampling (CVS) cases. True mosaicism was found in five cases (0.19 per cent). Confined placental mosaicism (CPM) occurred in 51 cases (1.9 per cent). The chromosomes most frequently encountered in CPM were 2, 7, 8, and the sex chromosomes. Three types of CPM as proposed by Kalousek et al. (1992) were observed. Cases with CPM had a statistically significant association with spontaneous abortion (chi 2 = 3.92, p < 0.05). Based on the data analysed, we conclude that (1) CPM is as likely to occur in cultured chorionic villi as in the direct preparation; (2) as with amniocyte culture, chromosome 2 mosaicism occurs commonly in villus culture; (3) the incidence of false-positive results can be greatly reduced and concern about maternal cell contamination can be alleviated by using both direct cytotrophoblast preparation and cultured chorionic stroma cells in all cases; and (4) follow-up cytogenetic and obstetrical studies, such as ultrasound and fetal monitoring, should always be considered in cases where CPM is suspected.

Cells, Cultured↗
PubMed1993

Characterization of i(18p) in prenatal diagnosis by fluorescence in situ hybridization.

A case is presented in which chorionic villus direct preparation and cultured chorionic villus cells revealed a 47,XX+mar karyotype. The marker was a small metacentric chromosome and appeared to be i(18p)--isochromosome 18p. Follow-up studies in both amniotic fluid and fetal fibroblasts confirmed the karyotype. In order to characterize the marker, a panel of biotinylated DNA probes was used, including a whole chromosome 18 probe, chromosome 18-specific alpha satellite DNA, Yac clones, and a pan-telomeric probe. These studies show that the marker is a monocentric i(18p) in which about 80 per cent of chromosome 18 alpha satellite DNA has been lost.

Adult↗