Biomedical subjects

W Liu

Publications and source records attributed to W Liu.

At least 235 records · Page 13Linked to original sources

PubMed2001

Boiler briquette coal versus raw coal: Part I--Stack gas emissions.

Stack gas emissions were characterized for a steam-generating boiler commonly used in China. The boiler was tested when fired with a newly formulated boiler briquette coal (BB-coal) and when fired with conventional raw coal (R-coal). The stack gas emissions were analyzed to determine emission rates and emission factors and to develop chemical source profiles. A dilution source sampling system was used to collect PM on both Teflon membrane filters and quartz fiber filters. The Teflon filters were analyzed gravimetrically for PM10 and PM2.5 mass concentrations and by X-ray fluorescence (XRF) for trace elements. The quartz fiber filters were analyzed for organic carbon (OC) and elemental carbon (EC) using a thermal/optical reflectance technique. Sulfur dioxide was measured using the standard wet chemistry method. Carbon monoxide was measured using an Orsat combustion analyzer. The emission rates of the R-coal combustion (in kg/hr), determined using the measured stack gas concentrations and the stack gas emission rates, were 0.74 for PM10, 0.38 for PM2.5, 20.7 for SO2, and 6.8 for CO, while those of the BB-coal combustion were 0.95 for PM10, 0.30 for PM2.5, 7.5 for SO2, and 5.3 for CO. The fuel-mass-based emission factors (in g/kg) of the R-coal, determined using the emission rates and the fuel burn rates, were 1.68 for PM10, 0.87 for PM2.5, 46.7 for SO2, and 15 for CO, while those of the BB-coal were 2.51 for PM10, 0.79 for PM2.5, 19.9 for SO2, and 14 for CO. The task-based emission factors (in g/ton steam generated) of the R-coal, determined using the fuel-mass-based emission factors and the coal/steam conversion factors, were 0.23 for PM10, 0.12 for PM2.5, 6.4 for SO2, and 2.0 for CO, while those of the BB-coal were 0.30 for PM10, 0.094 for PM2.5, 2.4 for SO2, and 1.7 for CO. PM10 and PM2.5 elemental compositions are also presented for both types of coal tested in the study.

Air Pollution↗

PubMed2001

Developmental expression of the POU transcription factor qBrn-2 during somitic myogenesis in quail.

We prepared a specific antiserum to the qBrn-2 protein and examined the developmental distribution of this protein during quail somitic myogenesis. In contrast to its mammalian homolog N-Oct-3, qBrn-2 exhibited an impressive spatio-temporal profile in somitic myogenesis, in addition to the orthodox expression observed in the developing neural tube. In somites, qBrn-2 was expressed in the outer epithelial cells, but not in the core cells. During the somite differentiation, qBrn-2 expression was enhanced and restricted to myotome. The location of qBrn-2 expression seemed to overlap with that of myf5 and myoD in myotome. However, in cells that just began to express myf5 or myoD, qBrn-2 expression was not obvious. As embryonic development proceeded, qBrn-2 positive cells in myotome migrated dorsally and ventrally, and qBrn-2 expression was still observed at dorsal and ventral muscle masses in the forelimb. On the basis of our observations, it seems that qBrn-2 may play important roles in the determination, differentiation and migration of muscle precursor cells, in addition to its known roles in neurogenesis.

Animals↗

PubMed2001

Substrate-structure dependence of ribotoxins on cleaving RNA in C. camphora ribosome.

Cinnamomin, a type II ribosome-inactivating protein (RIP) isolated from the seeds of Camphora tree (Cinnamomum camphora), could not inactivate its own (autologous) ribosome. Among five RIPs (Cinnamomin A-chain, ricin A-chain, trichosanthin, gelonin, and soporin-S6) tested, only saporin-S6 could cleave the N-glycosidic bond of RNA in C. camphora ribosome to release a specific RNA fragment (R-fragment) after treatment with aniline, which was shorter than that from rat liver ribosome. The amount of saporin-S6 to inactivate C. camphora ribosome was about 1000 times higher than that required for rat liver ribosome. Extra-ribosomal factors (S-100) in the post-ribosomal supernatant could not promote RNA N-glycosidase activity of cinnamomin and gelonin to C. camphora ribosome. These results indicated that there were some changes in the microenvironments of Sarcin/Ricin domain of C. camphora ribosome that abolished the recognition and catalysis of many RIPs. In addition, the length of C. camphora 5.8S ribosomal RNA was found to be longer than that of rat 5.8S ribosomal RNA.

Algal Proteins↗

PubMed2001

Penile anatomy under the pubic arch: reconstructive implications.

PURPOSE: We have previously defined the anatomy of the neurovascular bundle in the normal and hypospadiac penis. These studies were based on analysis of the fetal penis distal to the pubic arch without total inclusion of the crural bodies. To our knowledge the neuroanatomy beneath the pubic arch has not been well described. We defined the nerve distribution under the pubic arch and the relationship of the nerves to the crural bodies, corporeal bodies and urethra of the penis. MATERIALS AND METHODS: Eight normal human fetal penile specimens (at 17.5 to 29 weeks of gestation and 1 hypospadiac specimen at 32 weeks were serially sectioned and stained with Masson's trichrome, and the neuronal markers protein gene product 9.5 and S-100. These specimens were unique in that they contained the whole penis from the glans to the crural bodies beneath the pubic arch. Older specimens were decalcified before fixation. Computer reconstruction with commercially available graphics software allowed 3-dimensional analysis of the nerves and crural bodies in relation to the pubic arch and surrounding structures. RESULTS: The nerves of the penile shaft and glans surrounded the corporeal bodies, extending from the junction of the urethral spongiosum to the classic 11 and 1 o'clock positions with a paucity of nerves at the 12 o'clock position in the dorsal midline. Beneath the pubic arch the nerves to the penis were an extension of the dorsal neurovascular bundle of the prostate. The nerves formed 2 bundles following a path just under the pubic arch in close proximity to the bone, superior to the urethra and medial to the origin of the crural bodies. The nerve bundles joined the corporeal bodies at the proximal origin, where the 2 crural bodies fused together. At this point perforating branches into the corporeal bodies from the cavernous nerves were documented. As the dorsal nerves joined the dorsal aspect of the corporeal bodies, they immediately began to fan out along the surface of the corporeal tissue to the junction of the urethral spongiosum. Three-dimensional reconstruction showed the relationship of the nerves to the pubic arch and urethra in multiple views. CONCLUSIONS: A precise understanding of penile anatomy beneath the pubic arch and at the origin of the crural bodies is important for preserving neuronal structures. This anatomy is especially germane in children undergoing posterior urethral reconstruction secondary to trauma, intersex requiring feminizing genitoplasty and severe hypospadias.

Fetus↗

PubMed2001

[High polymorphism at the human P gene locus in Chinese Han and Tibetan populations].

OBJECTIVE: The authors studied two synonymous sites polymorphism (A355A, G780G) and one intervening sequence polymorphism(IVS13-15) of human P gene in 181 and 171 individuals sampled from Chinese Han and Tibetan populations respectively. METHODS: Genomic DNA was extracted from the ACD-blood specimens collected from 352 healthy unrelated individuals by phenol-chloro methods. The amplification of three fragments was performed using PCR technique; the product was digested with restricted enzyme. Agarose electrophoresis was used for typing the PCR product. RESULTS: There were two alleles at each exon variety locus; the allele frequencies in both A355A and G780G were of significant differences between the two populations ( chi(2)=24.54,chi(2)=37.05,P>0.001). No significant difference was found in allele frequency in IVS13-15 locus between the two populations (chi(2)=2.06,P>0.05). And in each of the populations, no significant difference was noted in the genotype frequency between the male and the female. The test for Hardy-Weinberg equilibrium showed that the genotype distributions observed in the two populations were correspondent with the expected. CONCLUSION: There is a remarkable difference in the distribution of allele frequencies at P gene locus between Chinese Han and Tibetan populations, which is related to the variation in skin pigmentation of these two Chinese population.

Adolescent↗

PubMed2001

Role of angiogenesis inhibitors in cancer treatment.

Angiogenesis is essential for the growth of both primary and metastatic tumors. This process, more complex than was previously thought, requires the coordinated activities of multiple factors and cell types. For tumors to develop a neovascular blood supply, tumor and host cells must secrete pro-angiogenic factors that offset the activities of inhibitory angiogenic factors. In addition, the newly derived tumor endothelium must respond to survive in a relatively caustic microenvironment. Thus, endothelial-cell survival factors are essential in the maintenance of this neovasculature. Because redundant factors and pathways regulate angiogenesis, inhibition of any single pathway is unlikely to lead to prolonged response in most patients with solid malignancies. Since anti-angiogenic therapy is unlikely to induce tumor regression, the criteria for efficacy must be evaluated by means other than the standard criteria used to evaluate cytotoxic chemotherapy regimens. Understanding the basic principles that drive tumor angiogenesis will lead to the development of therapies that will likely prolong survival without the toxicity associated with standard chemotherapy.

Angiogenesis Inhibitors↗

PubMed2001

[Effects of pesticide imidacloprid and its metabolites on soil respiration].

Soil respiration was measured using NaOH absorbing technique. Imidacloprid were applied to soil samples at concentration of 0, 10, 40, 100 micrograms.g-1, its hydrolysis and photolysis products were applied at 40 micrograms.g-1. The more significant effect at higher concentration of imidacloprid was observed. The effect of its hydrolysis product was minor than imidacloprid, but the photolysis products of 10 min have stronger effect, the effect decreased greatly in 30 min. Soil respiration recovered after 13 days. It showed that imidacloprid and its metabolites have little effect on soil microorganism.

Carbon Dioxide↗

PubMed2001

[Localization and position effect of human APPSWE gene on transgenic mice by means of in situ fluorescence hybridization].

In situ fluorescence hybridization (FISH) was used to study the integration and localization of human APPSWE gene on chromosomes of transgenic mice. It was found that in 2 founder mice, 34 and 36 metaphases of 80 metaphases observed had shown obvious specific hybridizing signals, the detection rates were 42.5% and 45%, respectively; meanwhile, in 1 F1 and 1 F2 mice, 33 and 30 metaphases out of 100 metaphases observed had specific hybridizing signals, the detection rates were 33% and 30%, respectively. The transgenes were localized on chromosome 8, 1, 17 and 2. The results indicated that transgene APPSWE were integrated stably into the chromosomes of transgenic mice and could be transmitted to offsprings through germ cells. The transgenes were randomly integrated into multiple sites of mice chromosomes. Meanwhile, the phenotypes of transgenic mice were also studied and different integrated sites had obvious effects on the pheonotypes.

Amyloid beta-Protein Precursor↗

PubMed2001

[HCV core protein activates expression of vascular endothelial growth factor in HepG(2) cells].

OBJECTIVE: To explore the effect of HCV core protein on vascular endothelial growth factor (VEGF) in HepG(2) cells. METHODS: The HCV core gene cDNA was recoverd by PCR, and cloned into PBK-CMV. The recombinant plasmid (PBK-HCVc) and the vector-alone were transfected into HepG(2) cells with liposome. After being selected with G418,resistant colonies were obtained. The reverse transcription PCR and Western blot was analyzed to show HCV core protein expression. VEGF was analyzed by immunohistochemical and Western blot; VEGF mRNA was analyzed by in situ hybridization and reverse transcription PCR. RESULTS: The results suggest that the recombinant plasmid could express HCV core protein efficiently under the control of vector's promoter. The VEGF of HepG(2)-C cells was higher than that of HepG(2)-CMV. CONCLUSIONS: HCV C protein can activates the expression of VEGF in HepG(2) cells and may contributes to viral carcinogenesis.

Endothelial Growth Factors↗

PubMed2001

[Comparison study between biological vision and computer vision].

The development and bearing of biology vision in structure and mechanism were discussed, especially on the aspects including anatomical structure of biological vision, tentative classification of reception field, parallel processing of visual information, feedback and conformity effect of visual cortical, and so on. The new advance in the field was introduced through the study of the morphology of biological vision. Besides, comparison between biological vision and computer vision was made, and their similarities and differences were pointed out.

Aerospace Medicine↗

PubMed2001

[Investigation of the clinicopathologic features, immunophenotype and Epstein-Barr virus infection of primary central nervous system lymphoma].

OBJECTIVE: To investigate the clinicopathological features, immunophenotypes and EB virus infection of 25 cases of primary central nervous system lymphoma (PCNSL). METHODS: Immunohistochemical staining was performed using monoclonal antibodies, L26 (CD20), kappa,lambda for B lymphocytes, UCHL-1 (CD45RO) for T lymphocytes, CS1-4 for latent membrane protein-1 (LMP-1) and GFAP for gliocytes. In situ hybridization was used for detection of EB virus encoded small nuclear RNAs (EBER1/2). RESULTS: All of the 25 PCNSL were of B lymphocyte origin with high-grade malignancy. Only 2/25 (8%) cases showed positive signal in EBER1/2 in situ hybridization. CONCLUSION: This group of PCNSL were all B-cell lymphomas, and the role of EB virus in this group of PCNSL was uncertain.

Adolescent↗

PubMed2001

[Soil macropore and its studying methodology].

This paper discusses the definition, size, types, formation of soil macropores. Soil macropore (> 0.03 mm) is the pore space that provides preferential paths of flow. The shape of macropore varies from crack or fissure, through to cylindrical pipe. Macropore is formed in main ways: by plant roots and soil fauna; wet-dry and freeze-thaw cycles; chemical weathering. The studying method of macropore divided into direct measurement and indirect description, which suitability and limitation are also reviewed.

Plant Roots↗

PubMed2001

[Adsorption of weak deep blue GR on hydroxy-aluminum montmorillonite].

Hydroxy-alumium montmorillonite may serve as potential adsorbents for organic pollutants from wastewater. It was synthesized by titrating Na-montmorillonite with hydroxy-aluminum solution (OH-/Al3+ molar ratio was 2.4). From powder XRD data, it was shown that the interlayer(d001) of montmorillonite was increased greatly from 12.58A to 18.63A. Seven modified montmorillonite samples, including hydroxy-aluminum montmorillonite, were used to remove the dye of weak deep blue GR from water. The results showed that hydroxy-alumium montmorillonite had very high adsorption ability, only 0.0200 g could treat 25 ml weak deep GR with 95% removal. The different adsorption mechanisms of weak deep blue GR on modified montmorillonite: surface adsorption, ion-exchanging and partion, were suggested.

Adsorption↗

PubMed2001

[An experimental study on the recombinant composite skin graft consisting of human epithelium and acellular xeno-dermis].

OBJECTIVE: To observe the effects of the recombinant composite skin graft consisting of human epithelium and acellular xeno-dermis on full thickness skin loss wounds, so as to find a new wound covering material. METHODS: Forty-two nude mice with full thickness skin loss on the back were grafted with the composite skin (compound skin grafting group, G) and human keratinocyte sheet (control group, C), respectively. The wound healing conditions, such as wound healing rate and wound contraction rate, were observed at different time points after the operation. Simultaneously, wound tissue samples were harvested for histological examination. RESULTS: The wound healing rate in G group was much higher than that in C group. In contrast, the wound contraction rate in G group was obviously lower than that in C group (P < 0.05). It was indicated by histological examination that there was full differentiation of epithelium, orderly collagen proliferation and obvious reconstruction of the epithelial-dermal conjunction structure in G group. There was no obvious sign of acute immune rejection. CONCLUSION: The wound covering with recombinant composite skin graft of human epithelium and acellular xeno-dermis could improve wound healing quality. The composite skin could be a new skin substitute.

Animals↗

PubMed2001

[Relationship between placenta growth factor and the pathogenesis of pregnancy induced hypertension syndrome].

OBJECTIVE: To determine whether pregnancy induced hypertension syndrome (PIHs) is associated with placenta growth factor (PLGF). METHODS: PLGF level in the maternal and umbilical venous serum collected from 23 PIHs patients and 20 normotensive controls was measured by enzyme linked immunoassay (ELISA), and expression of PLGF and its mRNA in the placenta and decidua from them was assessed by the immuno-histochemistry and reverse transcriptional-polymerase chain reaction (RT-PCR). RESULTS: (1) PLGF levels in the maternal serum from PIHs [(112.7 +/- 63.8) micrograms/L] were significantly lower than those from normal pregnancies [(200.3 +/- 140.9) micrograms/L], (P < 0.05), and they were correlated with infant birth weight and placental mass (r = 0.4, r = 0.6). (2) Expression of PLGF in sycytiotrophoblast and villous mesenchyme and decidua from PIHs significantly decreased respectively (P < 0.01, P < 0.01, P < 0.05), and expression of PLGF in sycytiotrophoblast was associated with the severity of PIHs (P < 0.05). (3) The transcription of total PLGF mRNA in the placenta and decidua from PIHs decreased significantly (P < 0.05 and P < 0.05 respectively). Particularly, the transcription of PLGF-2 mRNA decreased significantly in the placenta from PIHs. CONCLUSION: The abnormal expression of PLGF may play an important role in the pathogenesis of placental ischaemia hypoxia in PIHs.

Adult↗

PubMed2001

In vitro renaturation of recombinant human pro-urokinase expressed in Escherichia coli.

OBJECTIVE: Recombinant human pro-urokinase forms insoluble inclusion body when overexpressed in Escherichia coli. It must be denatured and renatured in vitro so that it can acquire activity. This study aimed at increasing the renaturation yield of denaturant pro-urokinase. METHODS: We evaluated the basic renaturation conditions of pro-urokinase through qualitative and quantitative analysis of pH, temperature, denatured concentration, protein concentration, and the ratio of reduced and oxidized thiol reagents. We also compared the effects of nonspecific additives, step-wise dilution and urea gradient dialysis. RESULTS: We defined the optimal conditions of pro-urokinase renaturation with a yield of about 20%-30%. CONCLUSION: Different recombinant denatured proteins have different renaturation conditions due to their different molecular sizes, molecular constructions, disulfide bond numbers, and hydrophobicity. The renaturation yield can be increased by optimizing the renaturation conditions of a specific protein.

Cysteine↗

PubMed2001

[Study of the route of intrahepatic metastasis of primary hepatic carcinoma].

OBJECTIVE: To study the relationship between pylic countercurrent blood-flow and intrahepatic metastasis of hepatocarcinoma. METHODS: Portal vein-hepatic artery fistula and pylic countercurrent blood flow in the liver were examined by color Doppler ultrasound. Patients examined were divided into four groups: group 1, hepatocarcinoma with background of hepatitis, group 2, hepatocarcinoma without background of hepatitis, group 3, hepatitis and group 4, normal liver. RESULTS: Pylic countercurrent flood flow was most frequently observed in group 1 patients. Intrahepatic metastasis was more frequent in group 1 than in group 2 patients. There was no statistically significant difference in the frequency of portal vein-hepatic artery fistula formation around and inside of tumor between group 1 and group 2 patients. CONCLUSION: Intrahepatic metastasis of hepatocarcinoma is due to countercurrent blood flow in the portal system.

Bile Ducts, Intrahepatic↗

PubMed2001

[beta-elemene induces apoptosis of K562 leukemia cells].

OBJECTIVE: To investigate the apoptosis-inducing effect of beta-elemene on K562 leukemia cells. METHODS: Hoechst 33342 and PI fluorescence staining, DNA fragmentation, electron microscopy, flow cytometry, and immunocytochemistry were used to evaluate the effect of beta-elemene on K562 cells. RESULTS: beta-elemene heatment induced the formation of apoptotic bodies and DNA ladder. The effect was dose- and time-dependent. The expression of bcl-2 was decreased in beta-elemene treated cells as compared with the untreated control cells. CONCLUSION: beta-elemene exerts its cytotoxic effect on K562 leukemic cells by the induction of apoptosis.

Apoptosis↗