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Biomedical subjects

H Huang

Publications and source records attributed to H Huang.

622 records · Page 35Linked to original sources
PubMedDate not supplied

Dioxins from thermal and metallurgical processes: recent studies for the iron and steel industry.

In thermal metallurgical processes such as iron ore sintering and metal smelting operations, large flows of off-gases are generated. Mainly due to residue recycling in such processes, chlorine and volatile organics are always present in the feed. As a consequence of "de novo" formation, the off-gases from such processes typically contain dioxins in the range 0.3-30 ng I-TEQ/Nm3. So far there are only very few studies about the mechanisms of dioxin formation and destruction in these metallurgical processes. In an European Union (EU) research project "Minimization of dioxins in thermal industrial processes: mechanisms, monitoring and abatement (MINIDIP)", integrated iron and steel plant has been selected as one of the industrial sectors for further investigation. A large number of particulate samples (feed, belt siftings, electrofilter) were collected from the iron ore sintering installations from various steel plants and analyzed for their organochlorocompound contents. Measurable amounts of PCDD/F, PCBz, PCB were found for all samples. The various parameters influencing their de novo synthesis activity were also evaluated in laboratory experiments, and such activity was found to be moderate for samples from the ore sinter belt, but extremely high for some ESP dusts. Fine dust is active in a wide range of temperatures starting at 200 degrees C and declining above 450 degrees C; the optimal temperature for de novo synthesis was found to be around 350 degrees C; some inhibitors, such as triethanolamine, may reduce de novo activity by 50%, and lowering the O2 concentration in the gas stream leads to a much lower amount of PCDD/F formation. On the basis of their relative mass, typical operating conditions and specific activity of the different samples, the regions in the sintering plant where de novo synthesis may take place were tentatively established.

Journal Article↗
PubMedDate not supplied

Fingerprints of dioxin from thermal industrial processes.

PCDD/F homologue profiles and 2,3,7,8 chlorine-substituted congener patterns are studied using principal component analysis and hierarchical cluster analysis. Measurement data from different industrial metallurgical processes such as iron and steel manufacturing, copper smelters and aluminium plants are compared. It appears that the PCDD/F homologue profiles from industrial metallurgical processes are similar to those from municipal solid waste incinerators. The 2,3,7,8 chlorine-substituted congener pattern from copper smelters is also very similar to that of municipal solid waste incinerators. However, the 2,3,7,8 chlorine-substituted congener pattern from an aluminum plant is very different, 2,3,7,8-TCDF being by far the most important TCDF congener.

Benzofurans↗
PubMedDate not supplied

Myocardial expression of endothelin-1 in murine Trypanosoma cruzi infection.

Chagas' disease, caused by Trypanosoma cruzi, is an important cause of myocarditis and chronic cardiomyopathy and is accompanied by microvascular spasm and myocardial ischemia. We reported previously that infection of cultured endothelial cells with T. cruzi increased the synthesis of biologically active endothlein-1 (ET-1). In the present study, we examined the role of ET-1 in the cardiovascular system of CD1 mice infected with the Brazil strain of T. cruzi and C57BL/6 mice infected with the Tulahuen strain during acute infection. In the myocardium of infected mice myonecrosis and multiple pseudocysts were observed. There was also an intense vasculitis of the aorta, coronary artery, smaller myocardial vessels and the endocardial endothelium. Immunohistochemistry studies employing anti-ET-1 antibody revealed increased expression of ET-1 that was most intense in the endocardial and vascular endothelium. Elevated levels of mRNA for preproET-1, endothelin converting enzyme and ET-1 were observed in the same myocardial samples. Plasma ET-1 levels were significantly elevated in infected CD1 mice 10-15 days post infection. These observations suggest that increased levels of ET-1 are a consequence of the initial invasion of the cardiovascular system and provide a mechanism for infection-associated myocardial dysfunction.

Animals↗
PubMedDate not supplied

Association of air pollution with hospital outpatient visits in Beijing.

Data collected at a community-based hospital in Beijing, China, were analyzed in an assessment of the association of air pollution with daily outpatient visits. Total suspended particle (TSP) measurements were available for 210 d (mean, 388 micrograms/m3; maximum, 1,255 micrograms/m3), and sulfur dioxide (SO2) measurements were available for 2 d (mean, 119 micrograms/m3; maximum, 478 micrograms/m3). The average number of daily hospital outpatient visits was 1,386; approximately 8.5% of these visits were to the surgery department, 7.9% were to the pediatrics department, and 20.6% were to the internal medicine department. A large increase in nonsurgery outpatient visits was observed in association with increases in both SO2 and TSP in linear regression models, after adjusting for temperature, humidity, season, and day of the week. The estimated effects (in which the most polluted days were compared with the least polluted days) on nonsurgery outpatient visits were increases of 20% (SE = 5%) and 17% (SE = 4%) in association with increases in SO2 and TSP, respectively. In a department-specific analysis, the association was found to be 1.5- to 2.0-fold stronger for pediatrics and internal medicine visits than for other types of visits. The separate associations of SO2 and TSP with internal medicine visits remained statistically significant when both SO2 and TSP were considered simultaneously and when adjustment was made for surgery visits. SO2 and TSP were found to be significant, independent predictors of internal medicine visits in both winter and summer.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Development of infection resistant polyurethane biomaterials using textile dyeing technology.

Infection is a major complication when using biomaterials such as polyurethane in the clinical setting. The purpose of this study was to develop a novel infection resistant polyurethane biomaterial using textile dyeing technology. This procedure results in incorporation of the antibiotic into the polymer, resulting in a slow, sustained release of antibiotic from the material over time, without the use of exogenous binder agents. Polycarbonate based urethanes were synthesized that contained either a non-ionic (bdPU) or anionic (cPU) chain extender within the polymer backbone and cast into films. The fluoroquinolone antibiotic ciprofloxacin (Cipro) was applied to bdPU and cPU using textile dyeing technology, with Cipro uptake determined by absorbance reduction of the "dyebath." These dyed bdPU/cPU samples were then evaluated for prolonged Cipro release and antimicrobial activity by means of spectrophotometric and zone of inhibition assays, respectively. Cipro release and antimicrobial activity by dyed cPU segments that were aggressively washed persisted over 9 days, compared with dyed bdPU and dipped cPU control segments that lasted < 24 hours. Dyed cPU segments, which remained in a static wash solution, maintained antimicrobial activity for 11 days (length of study), whereas controls again lost antimicrobial activity within 24 hours. Thus, application of Cipro to the cPU polymer by means of dyeing technology results in a slow sustained release of antibiotic with persistent bacteriocidal properties over extended periods of time.

Anti-Infective Agents↗
PubMedDate not supplied

The effect of Epstein-Barr virus gene BHRF1 expression on radioresistance of nasopharyngeal carcinoma cells.

In order to investigate the effect of the expression of Epstein-Barr virus gene BHRF1 on the apoptotic resistance of nasopharyngeal carcinoma cells to radiation, a highly expressing vector for BHRF1 was constructed and transfected into the nasopharyngeal carcinoma cell line CNE2. Then, the biologic alterations of the cells were tested after 60Co radiation. The results showed that, in the BHRF1-expressing cells, the apoptotic index was far lower than in the control groups after 60Co radiation, and cells recovered faster from the radiation, with a higher cell-proliferative rate, stronger ability of colony formation and tumor development in nude mice than that in the control groups. Given the functional homology of BHRF1 with bcl-2, our data indicate that BHRF1 expression could prohibit nasopharyngeal carcinoma cellular apoptosis caused by radiation and in this way contribute to oncogenic transformation.

Animals↗
PubMedDate not supplied

Transcriptional profile of mechanically induced genes in human vascular smooth muscle cells.

Vascular smooth muscle cells must monitor and respond to their mechanical environment; however, the molecular response of these cells to mechanical stimuli remains incompletely defined. By applying a highly uniform biaxial cyclic strain to cultured cells, we used DNA microarray technology to describe the transcriptional profile of mechanically induced genes in human aortic smooth muscle cells. We first identified vascular endothelial growth factor (VEGF) as a mechanically induced gene in these cells; VEGF served as a positive control for these experiments. We then used a DNA microarray with 5000 genes with putative functions to identify additional mechanically induced genes. Surprisingly, relatively few genes are mechanically induced in human aortic smooth muscle cells. Only 3 transcripts of 5000 were induced >2.5-fold: cyclooxygenase-1, tenascin-C, and plasminogen activator inhibitor-1. Downregulated transcripts included matrix metalloproteinase-1 and thrombomodulin. The transcriptional profile of mechanically induced genes in human aortic smooth muscle cells suggests a response of defense against excessive deformation. These data also demonstrate that in addition to identifying large clusters of genes that respond to a given stimulus, DNA microarray technology may be used to identify a small subset of genes that comprise a highly specific molecular response.

Cells, Cultured↗
PubMedDate not supplied

Comparison of several enzymes between normal physeal and tibial dyschondroplastic cartilage of broiler chickens.

Normal physeal and dyschondroplastic cartilage of broiler chickens was examined for six enzymes by isoelectric focusing in thin-layer polyacrylamide slab gels. Acid phosphatase (ACP), esterase (EST), malate dehydrogenase (MDH), and peroxidase (PRX) were present in the normal physeal cartilage but not in the dyschondroplastic cartilage. Staining intensity of glucose-6-phosphate isomerase (GPI) and triose-phosphate isomerase (TPI) was reduced in the dyschondroplastic cartilage compared with that of the physeal cartilage. Differences in the presence of these enzymes possibly demonstrated their roles in processes of bone formation, cartilage resorption, and calcification. ACP could be involved in calcification. Lack of EST and PRX may be related to the failure of vascular invasion in dyschondroplastic cartilage of afflicted birds. A deficiency of MDH and reduced GPI and TPI in dyschondroplastic cartilage may reflect a reduction in the activity of energetic metabolism, causing the dissipation of energy and necrotic cells.

Acid Phosphatase↗