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Biomedical subjects

W Huang

Publications and source records attributed to W Huang.

At least 451 records · Page 25Linked to original sources
PubMed1997

[Experimental study on the effect of nitric oxide on cochleas of guinea pigs].

The effects of nitric oxide (NO), 1-monoarginine (L-Arg), sodium nitroprusside (SNP) and N-methyl-1-monoarginine (NMLA) (which is an antagonist of nitric oxide synthase) on endocochlear potential, compound action potential(CAP) and cochlear microphonic(CM) of cochleas were studied by means of perilymphatic perfusion of the agents. The results showed that NMLA reduced EP, CAP and CM, L-Arg perilymphatic perfusion could reverse the change caused by NMLA. Continuous NO perilymphatic release restored the changes of EP, CAP and CM back to normal, sometimes above normal, followed by rapid reduction. After SNP perilymphatic perfusion, EP, CAP and CM went up transiently and then declined gradually and remained at a lower level. Addition of NMLA did not reverse the changes. The change of the latent period of CAP N1 and drift of CM was consistent with their amplitude changes. It was suggested that NO might help maintaining inner ear function under physiological condition and participate in controlling the micromechanical character and sensitivity of cochlear hair cells, undue expression of NO may cause toxicity to cochleas.

Action Potentials↗
PubMed1997

[Growth development of Ligustium chuanxiong Hort].

Experimental studies and chemical analysis have been made on Ligustium chuanxiong in its period of growth, generation and growth of organs, content and accumulation of nutritive elements, accumulation of dry matters, fertilizer consumption, etc.

Apiaceae↗
PubMed1997

[Effect of body position changes and circadian rhythm on cerebral blood flow velocity].

To study the effects of -6 degrees head down tilt (HDT), upright posture and 24 h circadian rhythm on cerebral blood flow (CBF) velocity in humans, the CBF velocity was measured by use of transcranial Doppler technique in the middle cerebral artery (MCA) of 12 healthy male subjects. The results showed that the mean CBF velocity increased significantly during -6 degrees HDT and decreased during upright posture, and CBF velocity was higher in day time than at night.

Blood Flow Velocity↗
PubMed1997

[An observation of the percutaneous absorption of total alkaloids and terpenoid lactones of Tripterygium wilfordii].

The main ingredients of Tripterygium wilfordii are total alkaloids and terpenoid lactones. The authors studied the percutaneous absorption of these compounds on mice by means of ultravillet spectrophotometry. The results showed that these alksloids and lactones could pass through the skin of the mice. The rate of 12-hour percutaneous absorption was 13.40% for the former and 17.60% for the latter. After the application of Tripterygium wilfordii adhesive plaster to the human skin for 12 hours, the two ingredients were absorbed 17.34% and 22.13% respectively. This suggests that Tripterygium wilfordii can really be administered through the skin.

Administration, Topical↗
PubMed1997

[Molecular characterization of genetic defects in hemophilia in Shanghai].

OBJECTIVE: To detect gene mutations in hemophilia A in Shanghai. METHODS: PCR, denaturing gradient gel electrophoresis (DGGE) and DNA sequencing were used. Fifty Chinese cases of hemophilia A without intron 22 inversion, including 24 severe, 9 moderate and 17 mild cases, were screened. Genomic DNA was amplified using GC-clamped primers covering all the exons and flanking intron regions, excluding the middle portion of extron 14 encoding the B domain, but including the thrombin cleavage sites at AA740 and 1689. The amplified GC-clamped PCR fragments were then electrophoresed on DGGE. The abnormal bands were sequenced. RESULTS: Eleven different mutations were identified, including 5 nonsense mutations, 5 missense mutations and one small deletion. Among them, 3 mutations, 466Lys (AAG)-Thr (ACG), 719Tyr (TAC)-Stop (TAG) and 312Ile (ATC)-xxC have not been reported before. CONCLUSION: Apart from intron 22 inversion, most gene mutations in hemophilia A were point mutations resulted from single base substitution. Generally the genetic defects correspond to the clinical manifestations.

Asian People↗
PubMed1997

[Establishment of a coupling method of high performance liquid chromatography and capillary gas chromatography].

An on-line coupling system of normal phase microbore HPLC and capillary GC has been established, in which retention gap technique with on-column injection and partially concurrent solvent evaporation with early vapor exit were used. The conditions suitable for the coupling system of HPLC and CGC must be determined experimentally since the factors have to be adjusted with respect to solvent evaporation temperature and column inlet pressure etc. The suitable solvent evaporation temprature for the mobile phase used for this system, n-hexane, was about 70 degrees C. A temperature much, lower or higher than 70 degrees C will influence the GC analysis. In addition, solvent evaporation temperature and column inlet pressure are interacting, that is, higher solvent evaporation temperature needs higher inlet pressure. At the above evaporation temperature, the suitable inlet pressure for this system was about 0.2MPa. In order to minimize the extra-column effect on the LC peaks, thin transfer-line and connectors of zero-dead volume between LC column and GC column must be used. The separation and analysis of aromatics in a light diesel fuel was performed by using this system with 15cm x 2mm i.d. YGW (5microm) silica LC column and 60m x 0.25mm i.d. OV-101 GC column under the above conditions. The analytical results show that the system of on-line coupling of HPLC with CGC is a reliable analytical tool for microcomponents in complex mixtures, especially for those requiring sample preparation prior to GC.

English Abstract↗
PubMed1997

Characterization of N5-methyltetrahydrofolate uptake in cultured human retinal pigment epithelial cells.

PURPOSE: To determine the identity of the transport process that is responsible for the uptake of N5-methyltetrahydrofolate, the predominant form of folate in blood, into cultured human retinal pigment epithelial cells. METHODS: Human retinal pigment epithelial cells were cultured on an impermeable plastic support, and the characteristics of the uptake of radiolabeled N5-methyltetrahydrofolate into the cells were investigated. The expression of the folate receptor and the reduced-folate transporter in these cells was evaluated by functional assays and by Northern blot analysis. In addition, the characteristics of N5-methyltetrahydrofolate uptake in these cells were compared with those in folate transport-defective human breast cancer cells that were manipulated to express functionally by transfection the cloned human folate receptor and the human reduced-folate transporter. RESULTS: Transport of N5-methyltetrahydrofolate into these cells occurred by a single saturable process with a Michaelis-Menten constant of 0.13 +/- 0.01 microM. The process was specific for such reduced folates as N5-methyltetrahydrofolate and N5-formyltetrahydrofolate. Nonreduced folate interacted with this transport process only weakly. The transport process was inhibited by anion transport inhibitors. Results of Northern blot analysis indicated the presence of transcripts specific for the reduced-folate transporter in these cells. These cells expressed very small amounts of the folate receptor evidenced from the binding of folate and from the detectable presence of folate receptor-specific transcript, but there was no evidence for participation of the receptor in the observed transport of N5-methyltetrahydrofolate. There was also no evidence in these cells for expression of the folate transporter that prefers nonreduced folate as a substrate. CONCLUSIONS: Transport of N5-methyltetrahydrofolate in human retinal pigment epithelial cells occurs exclusively through the reduced-folate transporter. The folate receptor is expressed at negligible levels in these cells and does not participate in the observed transport. Because the cells were cultured on impermeable supports, making the basolateral membrane inaccessible for transport measurements, it is speculated that the observed findings are related to the transport function of the apical membrane of these polarized cells.

Carrier Proteins↗
PubMed1997

Biological and clinical significance of cytogenetic study on 100 acute lymphoblastic leukemia and 219 acute non-lymphoblastic leukemia.

OBJECTIVE: To further investigate the role that cytogenetic may play in the diagnosis and prognosis of leukemia, a study was conducted in 319 acute leukemias. METHODS: 100 patients with acute lymphoblastic leukemia (ALL) and 219 patients with acute non-lymphoblastic leukemia (ANLL) were from Rui Jin Hospital, Xin Hua Hospital, Ren Ji Hospital and Shanghai Children's Hospital. Their cytogenetic data were analyzed together with those of morphology, immunology and clinical prognosis. RESULTS: In ALL group, 48 cases were karyotypically normal whereas 52 cases revealed chromosomal changes, among which 32 had quantitative abnormalities and 20 had qualitative abnormalities. The translocation t(9; 22) was identified in 11 out of 20 cases of structural aberrations (55%). Specific structural aberrations t(9; 22) and t(8; 14) were detected to be related to B-lineage associated differentiation antigens and t(8; 14) also with ALL-L3 according to FAB classification. With regard to clinical prognosis, the survival rate of structural aberration subset decreased significantly compared with the normal karyotype subset (P < 0.05). However, no statistically significant difference was found between hyperdiploidy subset (not including near-triploidy) and normal karyotype subset (P > 0.75). In ANLL group, 80% of de novo patients and relapsed patients had chromosomal abnormalities. Importantly, structural aberrations accounted for 73% of these abnormalities and frequently corresponded to specific types of FAB classification. Relevant prognostic studies demonstrated that t(15; 17) subset had the best overall survival probability, followed by t(8; 21) and normal karyotype subset, while the numerical aberration subset showed a relatively poor prognosis. CONCLUSION: Our data confirmed that cytogenetic study is important for the molecular study of the leukemogenesis. On the other hand, it also provides an independent parameter for prognosis in acute leukemia.

Adolescent↗
PubMed1997

[Immunohistochemical locating and quantitative studies of 5-hydroxytryptamine and 5-hydroxytryptamine receptor in placental villi of patients with pregnancy induced hypertension].

OBJECTIVE: To supply evidence of relationship between pregnancy induced hypertension (PIH) and 5-hydroxytryptamine (5-HT) and 5-hydroxytryptamine receptor (5-HTR) synthesized by placental villi. METHODS: Five normal placentas and 15 placentas of PIH were used for studying localization and quantification of 5-HT and 5-HTR in placental villi by using immunohistochemical and in situ quantitative methods. RESULTS: Syncytiotrophoblasts and capillary endothelium in placental villi of control group showed 5-HT and 5-HTR positive immunoreaction, but in placental villi of group with PIH, syncytiotrophoblasts appeared 5-HT and 5-HTR weak positive immunoreaction and capillary endothelium appeared 5-HT and 5-HTR weak positive or negative immunoreaction. The results of in situ quantitation showed that the content of 5-HT and 5-HTR in placental villus syncytiotrophoblasts of group with PIH were significantly lower than those in the control group. CONCLUSIONS: The content of 5-HT and its receptor in placenta may be related to PIH.

Adult↗
PubMed1997

[The effect of substance P upon middle ear effusion of secretory otitis media and the mode of action].

This experiment aimed to explore the effects of substance P (SP) on secretory otitis media (SOM). Both immunohistochemistry ABC-GDN and image pattern analysis technique were adopted to investigate the relation between SP content of SOM middle ear mucosa and middle ear effusion, and observe the effect of SP receptor antagonist spantide and histamine H2 receptor blocker cimetidin on middle ear effusion. The findings showed: middle ear mucosa SP content tended to increase, and had positive correlation with middle ear effusion, intra-abdominally injecting 1 mg/ml Spantide and 1 mg/ml Cinetidin per day could have middle ear effusion decreased obviously, but the quantities of reduction were more significant. The results suggest that SP plays a role in SOM, might accelerate vasodilation and increase the permeability of cupillary in middle ear mucosa mediated by histamine.

Animals↗
PubMed1997

[Effects of composite blood-activating decoction on adhesive function of bone marrow stroma cells in radiation injured mice].

OBJECTIVE: To evaluate the effect of commonly used "blood activating and stasis-removing" Chinese herbal drugs on adhesive function of bone marrow stroma cells in acute radiation injured mice. METHODS: After irradiation by 8 Gy 60Co gamma-ray, each mouse was intraperitoneally injected immediately with 0.2 ml 100% composite blood-activating decoction (CBAD) twice a day for 6 days. On the 7th day, the femura were taken and the bone karyocyte (BMC) suspension was made. According to long term bone marrow culture procedure, on the 12th day, the fibroblastic colony forming units were counted, and on the 28th day, the adhesion of culture stroma cells to normal murine BMC was observed. RESULTS: The adhesion of culture stroma cells to normal murine BMC was 67.8 +/- 17.2% in normal group, while in CBAD group, it was 55.8 +/- 10.5%. The difference was insignificant (P > 0.05). In the control group, the value was 47.7 +/- 13.6%, which was significantly lower than that in normal group (P < 0.02). CONCLUSION: The commonly used "blood-activating and stasis-removing" Chinese herbal drugs can enhance the adhesive function of bone marrow stroma cells in acute radiation injured mice.

Animals↗
PubMed1996

Mek1 phosphorylation site mutants activate Raf-1 in NIH 3T3 cells.

MAP (mitogen-activated protein) kinases are activated by a family of dual specificity kinases called Meks (MAP kinase/Erk kinase). Mek1 can be activated by Raf by phosphorylation on serine 218 and serine 222. Mutation of these sites to acidic residues leads to constitutively active Mek1 in some cases. When fibroblast lines were infected with high titer retroviral stocks carrying these Mek1 genes, the resultant transformation and morphological changes correlated with the kinase activity of the respective Mek1 enzymes. Although [Asp218]- and [Asp218,Asp222]Mek immunoprecipitated from clonal cell lines could phosphorylate kinase-inactive Erk1 equally well in vitro, the endogenous MAP kinase activity was 5-7-fold greater in [Asp218]Mek1-infected clonal lines, and did not correlate with the degree of transformation. Analysis of the Erk1 pathway revealed Raf-1 activation, which correlated qualitatively with the MAP kinase activity seen in the [Asp218]- and [Asp218,Asp222]Mek1-infected clonal cell lines. Expression of dominant negative Ras did not affect the elevated Raf-1 activity observed in these cells, however. These data suggest that Mek1 phosphorylation site mutants activate Raf-1 and MAP kinase by a Ras-independent pathway and that the mechanism by which transformation occurs may utilize pathways that are MAP kinase-independent.

3T3 Cells↗
PubMed1996

Sodium-dependent carnitine transport in human placental choriocarcinoma cells.

The JAR human placental choriocarcinoma cells were found to transport carnitine into the intracellular space by a Na(+)-dependent process. The transport showed no requirement for anions. The Na+-dependent process was saturable and the apparent Michaelis-Menten constant for carnitine was 12.3 +/- 0.5 microM. Na+ activated the transport by increasing the affinity of the transport system for carnitine. The transport system specifically interacted with L-carnitine, D-carnitine, acetyl-DL-carnitine and betaine. 6-N-Trimethyllysine and choline had little or no effect on carnitine transport. Of the total transport measured, transport into the intracellular space represented 90%. Plasma membrane vesicles prepared from JAR cells were found to bind carnitine in a Na(+)-dependent manner. The binding was saturable with an apparent dissociation constant of 0.66 +/- 0.08 microM. The binding process was specific for L-carnitine, D-carnitine, acetyl-DL-carnitine, and betaine. 6-N-Trimethyllysine and choline showed little or no affinity. It is concluded that the JAR cells express a Na(+)-dependent high-affinity system for carnitine transport and that the Na(+)-dependent high-affinity carnitine binding detected in purified JAR cell plasma membrane vesicles is possibly related to the transmembrane transport process.

Binding Sites↗
PubMed1996

Megavoltage imaging with a large-area, flat-panel, amorphous silicon imager.

PURPOSE: The creation of the first large-area, amorphous silicon megavoltage imager is reported. The imager is an engineering prototype built to serve as a stepping stone toward the creation of a future clinical prototype. The engineering prototype is described and various images demonstrating its properties are shown including the first reported patient image acquired with such an amorphous silicon imaging device. Specific limitations in the engineering prototype are reviewed and potential advantages of future, more optimized imagers of this type are presented. METHODS AND MATERIALS: The imager is based on a two-dimensional, pixelated array containing amorphous silicon field-effect transistors and photodiode sensors which are deposited on a thin glass substrate. The array has a 512 x 560-pixel format and a pixel pitch of 450 microns giving an imaging area of approximately 23 x 25 cm2. The array is used in conjunction with an overlying metal plate/phosphor screen converter as well as an electronic acquisition system. Images were acquired fluoroscopically using a megavoltage treatment machine. RESULTS: Array and digitized film images of a variety of anthropomorphic phantoms and of a human subject are presented and compared. The information content of the array images generally appears to be at least as great as that of the digitized film images. CONCLUSION: Despite a variety of severe limitations in the engineering prototype, including many array defects, a relatively slow and noisy acquisition system, and the lack of a means to generate images in a radiographic manner, the prototype nevertheless generated clinically useful information. The general properties of these amorphous silicon arrays, along with the quality of the images provided by the engineering prototype, strongly suggest that such arrays could eventually form the basis of a new imaging technology for radiotherapy localization and verification. The development of a clinically useful prototype offering high-quality images, ultimately with an approximately 52 x 52-cm2 detection surface, is anticipated.

Equipment Design↗
PubMed1996

Selection and characterization of amino acid substitutions at residues 237-240 of TEM-1 beta-lactamase with altered substrate specificity for aztreonam and ceftazidime.

Recently, natural variants of TEM-1 beta-lactamase with amino acid substitutions at residues 237-240 have been identified that have increased hydrolytic activity for extended-spectrum antibiotics such as ceftazidime. To identify the sequence requirements in this region for a given antibiotic, a random library was constructed that contained all possible amino acid combinations for the 3-residue region 237-240 (ABL numbering system) of TEM-1 beta-lactamase. An antibiotic disc diffusion method was used to select mutants with wild-type level activity or greater for the extended-spectrum cephalosporin ceftazidime and the monobactam aztreonam. Mutants that were selected for optimal ceftazidime hydrolysis contained a conserved Ala at position 237, a Ser for Gly substitution at position 238, and a Lys for Glu at position 240. Mutants selected for aztreonam hydrolysis exhibited a Gly for Ala substitution at position 237, a Ser for Gly substitution at position 238, and a Lys/Arg for Glu at position 240. The role of the A237G substitution in differentiating between ceftazidime and aztreonam was further investigated by kinetic analysis of the A237G, E240K, G238S:E240K, and A237G:G238S:E240K enzymes. The A237G single mutant and the G238S:E240K double mutant exhibited increases in catalytic efficiency for both ceftazidime and aztreonam. However, the triple mutant A237G:G238S:E240K, displayed a 12-fold decrease in catalytic efficiency for ceftazidime but a 3-fold increase for aztreonam relative to the G238S:E240K double mutant. Thus, the A237G substitution increases ceftazidime hydrolysis when present alone but antagonizes ceftazidime hydrolysis when it is combined with the G238S:E240K substitutions. In contrast, the A237G substitution acts additively with the G238S:E240K substitutions to increase aztreonam hydrolysis.

Amino Acid Sequence↗
PubMed1996

Cigarette advertising and onset of smoking in children: questionnaire survey.

OBJECTIVE: To investigate uptake of smoking in a cohort of 11 to 12 year olds related to awareness of advertised cigarette brands named. DESIGN: Self completed questionnaires administered to whole classes of schoolchildren in June 1993 and June 1994. SETTING: Primary, middle, and secondary schools in the north and south of England. SUBJECTS: 1450 pupils aged 11 and 12 years at the time of the first survey. MAIN OUTCOME MEASURES: Onset of smoking and brands smoked by the second survey related to cigarette brands named in the first one. Less advertised brands were used as the base for calculating odds ratios. RESULTS: Girls who named the most advertised brands-namely, Benson and Hedges alone (odds ratio = 2.50, 95% confidence interval = 1.18 to 5.30) or Benson and Hedges and Silk Cut (2.15, 1.04 to 4.42) in the first survey were at greatest risk of taking up smoking by the second one. The difference was similar but not significant for boys. Boys and girls who named the least advertised brands in the first survey were at no greater risk of taking up smoking by the second survey than those who named no brands (boys odds ratio = 0.49 (0.24 to 1.01); girls 0.79 (0.38 to 1.62)). New smokers were more likely to smoke any available brand (29.5%) or a less advertised brand such as Embassy (24.6%) than the most advertised ones, Benson and Hedges (19.7%) and Silk Cut (14.8%). Established smokers were more selective, only 15% smoking any available brand and 38.3% smoking Benson and Hedges. CONCLUSIONS: Cigarette advertising appears to increase children's awareness of smoking at a generic level and encourages them to take up the behaviour, beginning with any cigarettes which are available and affordable.

Adolescent↗