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Biomedical subjects

Y Zhao

Publications and source records attributed to Y Zhao.

At least 523 records · Page 29Linked to original sources
PubMed1999

[Influence of pavulon on facial nerve monitoring during middle ear-mastoid operation].

OBJECTIVE: To evaluate the influence of pavulon (muscle relaxant) on facial nerve monitoring for patient with middle ear-mastoid operation during general anesthesia. METHOD: Intraoperative monitoring of the facial nerve (FNM) was done in 45 ears (44 case). For patient with middle ear-mastoid disease, 38 ears underwent inhaled-intravenous anesthesia with muscle relaxant pavulon (group of general anesthesia), 7 ears underwent local anesthesia (group of local anesthesia). Accelography (ACCG) was used in 10 case for testing the correlation between of FNM and the various degree of recovery from ulnar nerve-musculor blockade. RESULT: FNM could be elicited during different periods of recovery with values of T4/T1 varying from 10%-98%. Pavulon could be used to eliminate muscular vibration from disturbing FNM. Electromyography (EMG) potentials were successfully recorded in 34 ears (89.4%). Anesthesia was uneventful and it may be controled satisfactority. CONCLUSION: Considering the advantage of pavulon. It can be used for general anesthesia during intraoperative monitoring of the facial nerve for children or adults suffering from local complicated diseases.

Adolescent↗
PubMed1999

[High performance liquid chromatography for analysis of reverse transcription polymerase chain reaction (RT-PCR) products].

The polymerase chain reaction is a powerful method for amplifying specific DNA sequences in vitro. Reverse transcribing mRNA into cDNA expands the use of PCR to monitor mRNA expression in biological system. A method for the analysis of RT-PCR products by HPLC was developed. The separation was performed on a nonporous ion exchange resin column with gradient elution of sodium chloride in 20 mmol/L Tris-HCl buffer (pH 9.0) at a flow rate of 1.0 mL/min and the detection wavelength was 260 nm. lambda-DNA-Hind III digest and a series of RT-PCR products were analyzed for studying the mRNA expression of secreted phospholipase A2 after being injured.

Animals↗
PubMed1999

[Distribution of 5-fluorouracil in plasma and pancreatic tissue of rats during the regional arterial infusion chemotherapy].

OBJECTIVE: Compare the pharmacokinetic parameters of 5-FU in the regional arterial infusion chemotherapy with those in the intravenous chemotherapy. METHODS: Wistar rats were randomly divided into two groups: the intravenous group and the regional arterial infusion group. HPLC was used to measure the concentration of 5-FU in the plasma and the pancreas tissue. Penetration index was calculated. RESULTS: In the intravenous group, maximum concentration (Cmax) of 5-FU in the pancreas was 8.42 micrograms/g and the clearance time of the pancreas was 50 min. In the regional arterial infusion group, Cmax of 5-FU in the pancreas was 20.00 micrograms/g and the clearance time of the pancreas was 90 min. They were both greater than those of the intravenous group. Rd was 2.42. CONCLUSIONS: The regional arterial infusion chemotherapy is a better way for treating pancreatic carcinoma than the intravenous chemotherapy.

Animals↗
PubMed1999

[Expression of nm23-H1 gene in oral squamous cell carcinoma and its relation to tumor metastasis].

OBJECTIVE: To make an inquiry into the relation between the expression level of nm23-H1 protein and metastasis of oral squamous cell carcinoma (OSCC). METHODS: We evaluated the expression of nm23-H1 protein in 75 cases of OSCC by immunohistochemical technique (SABC). RESULTS: These immunoreactivities of nm23-H1 protein were most common in the cytoplasm of tumor and epithelia cell. Using single-factor chi-test, we found there was a significant correlation between the expression of nm23-H1 protein and lymph node metastasis of OSCC (P < 0.01), pathology grade (P < 0.05). But no statistical association was found among nm23-H1 protein expression level and tumor size, site and patient's sex, age. Using multi-factor logistic stepwise regression analysis, we found that nm23-H1 protein expression level had more effect on OSCC cervical lymph node metastasis than any other parameters. CONCLUSIONS: The results suggested that nm23-H1 protein play an important role in the suppression of the metastasis of OSCC, and that determining the expression level of nm23-H1 protein may help us prognose the metastasis of OSCC.

Adult↗
PubMed1999

[Apoptosis of human pancreatic carcinoma cell lines induced by combinations of chemotherapeutic drugs].

OBJECTIVE: To investigate the apoptotic in human pancreatic carcinoma cell lines P3, SW1990 and Capan-2 induced by the combined treatment of 5-fluorouracil (5FU), mitomycin C (MMC), carboplatin(CBP) or adriamycine (ADM) or epirubicin (E-ADM). METHODS: The changes of cell morphology were monitored by means of microscopic and fluorescence technique after treated with the combinations of chemotherapeutic drugs. The rate of apoptosis was calculated with flow cytometry and the fragmentation of DNA was measured by agarose gel electrophoresis. RESULTS: The combinations of chemotherapeutic drugs were able to induce the apoptosis of human pancreatic carcinoma cell lines. Compared with the cell necrosis, the dosage of drugs was less and the time was shorter for inducing apoptosis. With the increased dosage and/or the time prolonged for treating the cells, the rate of apoptotic cells was increased. However, the apoptosis reaction of various human pancreatic carcinoma cell lines, which were mentioned above, induced by the same combinations of chemotherapeutic drugs were various different. CONCLUSIONS: The apoptosis process might be a mechanism of an inhibiting cancer cell growth induced by the combinations of chemotherapeutic drugs. The examination of apoptosis reaction for the cells induced by different methods and/or chemotherapeutic drugs could become an important index of testing their ability of inhibiting pancreatic neoplasm.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

[The role of ICAM-1 in leukocyte adherence to endothelial cells induced by hypoxia/reoxygenation].

OBJECTIVE: To determine whether intercellular adhesion molecule-1 (ICAM-1) mediats the polymorphonuclear leukocyte (PMN) adherence to endothelial cells elicited by hypoxia/reoxygenation (H/R). METHODS: Human umbilical vein endothelial cells (HUVEC) monolayers was exposed to hypoxia for 30 min or 120 min then reoxygenated. Count the number of PMN in adhesion assays. Expression of ICAM-1 and ICAM-1 mRNA was detected by immunohistochemical analysis and in situ hybridization. RESULTS: PMN adhesion to HUVEC exposed to H/R was significantly increased (1 fold) as compared with that of control (P < 0.01). H/R induced hyperadherence was significantly diminished by monoclonal antibodies directed at ICAM-1 or CD11a/CD18. The results showed an increased expression of ICAM-1 and ICAM-1 mRNA on HUVEC exposed to H/R. Hypoxic HUVEC might be responsible for PMN adesion. CONCLUSIONS: ICAM-1 mediated the adhesive interaction between PMN and VEC induced by hypoxia/reoxygenation.

Cell Adhesion↗
PubMed1999

p53 gene mutations in non-small cell lung cancer detected by polymerase chain reaction single-strand conformation polymorphism analysis.

Mutations of the p53 tumor suppressor gene are the most frequent genetic alterations detected in human lung cancer. To assess the pathogenic significance of p53 gene alterations in Chinese non-small cell lung cancer (NSCLC), 74 paired samples of primary lung cancer and normal lung tissue far away from the cancer were analyzed for mutations of the p53 gene (exons 5-8) using exon-specific PCR, single-strand conformation polymorphism (PCR-SSCP). p53 mutations were observed in 55.4% (41/74) of the samples. No linkages were detected between the incidence of p53 mutations and histological type, lymph node metastasis, age or sex. Significant association between p53 mutations and degree of differentiation in adenocarcinomas, not in squamous cell carcinomas, was observed. The frequency of p53 mutations in smokers (65.3%) was higher than in nonsmokers (33.3%) and reached statistical significance. We also found p53 mutations in 6/7 samples which had tissue invasion and distant metastasis. These results suggest that smoking could be an important factor in lung carcinogenesis, p53 mutation is a worse prognosis indicator in adenocarcinomas and related to high aggressive behavior of human lung cancer.

Adenocarcinoma↗
PubMed1999

The diagnosis and treatment of gastrinoma: report of 17 cases.

OBJECTIVE: To study the experience of diagnosis and treatment of gastrinoma. METHODS: A retrospective study of 17 patients with gastrinoma seen from 1978 through 1998 in PUMC hospital. RESULTS: Three of the 17 cases were associated with multiple endocrine neoplasia type I (MEN-I) syndrome. Tumors dispersed extensively in pancreas (31%), duodenum (25%), lymphnode (19%) and other place (25%). Ultrasonography and computed tomography (CT) were sensitive in localizing tumor in pancreas and liver, but were not so well for small tumor in duodenum and lymph node. The angiography, percutaneous transhepatic portal sampling (PTPS), scintigraphy and endoscopic ultrasonography (EUS) also can be used. Sixteen of 17 patients underwent 38 operations and 56 percent of the 16 cases underwent several operations. Seven patients at last performed total gastrectomy that was still considered as a choice of treatment. Tumor resection was rare because the advancing of tumor in most cases. CONCLUSIONS: Diagnosing gastrinoma in its early stage and striving for the tumor resection and reducing the metastasis of liver were the cruxes for good prognosis.

Adolescent↗
PubMed1999

[Study on the interaction of Cu2Zn2SOD with CoCl2, Co(His)n by spectral and magnetic resonance analysis].

Direct interaction of Cu2Zn2SOD with inorganic metal compound (CoCl2) and organic metal compound [Co(II)(His)n] was studied by ICP, VIS, NMR and measurement of enzyme activity. It has been found that in aqueous solution, there exists a direct interaction of the metal ions of the active center in the metalloenzyme (Cu2Zn2SOD) with external added CoCl2, Co(His)n. As a result, part of the metal ions in metalloenzyme were replaced and the corresponding metalloenzyme derivatives were produced and the catalytic activity of enzyme were affected. Moreover, the interaction of Co(II)(His)n with Cu2Zn2SOD is stronger and quicker, than that of CoCl2 with this enzyme, as well as the Co(II) from Co(II)(His)n is easier to enter the active center of enzyme.

Cobalt↗
PubMed1999

[Study on the interaction of copper-zinc superoxide dismutase with cobalt (II)-histidine by spectral analysis--II. Effect of amount of external added Co(His)n, phosphate].

The effect of changing the amount of external added Co(His)n and phosphate on the interaction of Cu2Zn2SOD with organic metal compound (Cobalt (II)-Histidine) have been studied by means of ICP, VIS and measurement of enzyme activity. It has found that in aqueous solution, there exists a direct interaction of the metal ions of the active center in the metalloenzyme (Cu2Zn2SOD) with external added Co(His)n. As a result, part of the metal ions in metalloenzyme were replaced and the corresponding metalloenzyme derivatives (Co (II)-substituted derivatives of SOD) were produced and the catalytic activity of enzyme were affected. It has also studied the intensity of interactions in different molar ratios (Cobalt (II)-Histidine) and of the presence of phosphate and got some results under the effect of corresponding factors.

Cobalt↗
PubMed1999

[Study on the interaction of copper-zinc superoxide dismutase with cobalt (II)-histidine by spectral analysis. II. Effects of pH, interaction time].

The direct interaction of Cu2Zn2SOD with organic metal compound (Cobalt (II)-Histidine) was studied by ICP, VIS and the measurement of enzyme activity, and also investigated the effect of pH values and different interaction times for this interaction. The results showed that with the increased in pH values and the more longer interaction times, the intensity of interaction were increased and the corresponding catalytic activity of enzyme were affected.

Cobalt↗
PubMed1999

[Study on the ingredients of reserpine by TLC-FT-SERS].

A new method for analysing the ingredients of reserpine by thin layer chromatography (TLC) and surface-enhanced Raman spectroscopy (SERS) is reported in this paper. The results show that the characteristic spectral bands of reserpine satuated at the thin layer with the amount of sample about 2 microg were obtained. The difference between SERS and solid spectra was found. An absorption model of reserpine and silver sol was proposed. This method can be used to analyse the chemical ingredients with high sensitivity.

Chromatography, Thin Layer↗
PubMed1998

Cloning and characterization of a novel transforming growth factor-beta1-induced TIAF1 protein that inhibits tumor necrosis factor cytotoxicity.

To determine how TGF-beta1 protects L929 fibroblasts against TNF-alpha cytotoxicity, we report the isolation and characterization of a novel cDNA encoding a 12-kDa TGF-beta1-induced antiapoptotic factor, designated TIAF1. GFP-tagged TIAF1 protein is present mostly in perinuclear and nuclear locations. TIAF1 inhibits the cytotoxic effects of TNF-alpha and overexpressed TNF receptor adaptors TRADD, FADD, and RIP. L929 stable transfectants expressing TIAF1 do not have significant changes in the expression of TNF receptors and effector or regulatory proteins in apoptosis, which may account for the acquired TNF resistance in these cells. Notably, these cells have a significantly suppressed IkappaB-alpha protein expression, and IkappaB-alpha degradation is blocked when exposing these cells to TNF-alpha. Similarly, stimulation of untransfected L929 cells with TGF-beta1 results in suppression of IkappaB-alpha expression and retarded IkappaB-alpha degradation in response to TNF-alpha. Despite the fact that the mechanism for blocking TNF cytotoxicity is unknown, TIAF1 is apparently involved in TGF-beta1 inhibition of IkappaB-alpha expression and suppression of TNF-mediated IkappaB-alpha degradation.

Amino Acid Sequence↗
PubMed1998

Ser727-dependent recruitment of MCM5 by Stat1alpha in IFN-gamma-induced transcriptional activation.

Stat1alpha is a latent cytoplasmic transcription factor activated in response to interferon-gamma (IFN-gamma). The C-terminal 38 amino acids of Stat1alpha are required to trigger transcription and therefore may possibly serve as a transcription activation domain (TAD). Here we show that the C-terminus of Stat1alpha is an independent TAD which can interact with a specific group of nuclear proteins. Mutation of the Stat1 Ser727 and Leu724 decreases its transcriptional activity and affinity for the nuclear proteins. One of the interacting proteins was identified as MCM5, a member of the mini-chromosome maintenance (MCM) family involved in DNA replication. Both in vitro and in vivo interaction of Stat1alpha and MCM5 were demonstrated. Furthermore, the in vitro interaction required Ser727 and was enhanced by its phosphorylation. Transient over-expression of MCM5 enhanced transcriptional activation by Stat1alpha in a Ser727-dependent manner. Finally, changes in the level of nuclear localized MCM5 during the cell cycle correlated with the changes in transcriptional response to IFN-gamma acting through Stat1alpha. These results strongly suggest that MCM5 is recruited through interaction with Stat1alpha in a Ser727- and Leu724-dependent manner to play a role in optimal transcriptional activation.

Cell Cycle↗
PubMed1998

[Study on the analytical method for organochlorine pesticide residue using gas chromatography-mass spectrometry].

A gas chromatographic-electron ionization--mass spectrometric method (GC-EIMS) was developed for determining organochlorine pesticide residues. Ten organochlorine pesticides including alpha, beta, gamma and delta isomers of hexachlorocyclohexane(HCH), pp'-DDE, pp'-DDT,op'-DDT,pp'-DDT,pentachloronitrobenzene (Quintozene, PCNB) and hexachlorobenzene(HCB) were determined respectively. Targeted pesticide analyses were separated on DB-5 capillary column. The optimum chromatographic conditions and MS parameter were determined. In test condition, each constituent in the standard mixture was separated efficiently. The retention time of each compound and its characteristic ion were determined in fullscan mode from 50 to 450 amu. The values of their mass spectrum on the total ion current(TIC) with fullscan mode agree with those of NIST and pesticide libraries. The characteristic ions were selected to quantify at m/z 181 for the isomers of HCH, m/z 284 for HCB, m/z 295 for PCNB, m/z 246 for pp'-DDE, m/z 235 for pp'-DDD, op'-DDT and pp'-DDT. The accuracy and reliability were proved respectively by linear test, precise test and recovery test. The linear ranges of PCNB and pp'-DDT are 0.0025-0.50 microgram/ml. The ranges of the isomers of HCH, pp'-DDE, pp'-DDD and op'-DDT are 0.0020-0.40 microgram/ml. The limits of detection are 0.0025 ng for PCNB and pp'-DDE, but 0.0020 ng for the isomers of HCH, HCB, pp'-DDE, pp'-DDD and op'-DDT.

Gas Chromatography-Mass Spectrometry↗
PubMed1998

Resonance raman characterization of the heme domain of soluble guanylate cyclase.

We report the resonance Raman characterization of the heme domain of rat lung soluble guanylate cyclase (sGC) expressed in Escherichia coli. Like heterodimeric sGC isolated from bovine lung, the sGC heme domain [beta1(1-385)] and its heme ligand mutant H105G(Im) contain a stoichiometric amount of heme, which is five-coordinate, high-spin ferrous in both beta1(1-385) and chemically reduced H105G(Im). In the presence of NO, both beta1(1-385) and H105G(Im) form a five-coordinate nitrosyl heme complex with a nu(Fe-NO) value of 525 cm-1 and a nu(NO) value of 1676 cm-1. For the first time, the Fe-N-O bending mode near 400 cm-1 has been identified in a five-coordinate nitrosyl heme complex. Both beta1(1-385) and H105G(Im) form a six-coordinate, low-spin complex with CO. We find evidence for two binding conformations of the Fe-CO unit. The conformation that is more prevalent in beta1(1-385) has a nu(Fe-CO) value of 478 cm-1 and a delta(Fe-C-O) value of 567 cm-1, whereas the dominant conformation in H105G(Im) is characterized by a nu(Fe-CO) value of 495 cm-1 and a delta(Fe-C-O) value of 572 cm-1. We propose that in the dominant conformation of H105G(Im)-CO the Fe-CO unit is hydrogen bonded to a distal residue, while this is not the case in beta1(1-385). Reexamination of sGC isolated from bovine lung tissue indicates that it also has two binding conformations for CO; the more populated form is not hydrogen-bonded. We propose that the absence of hydrogen-bond formation between a distal residue and exogenous ligands is physiologically relevant in lowering the oxygen affinity of heterodimeric sGC and, therefore, stabilizing the ferrous, active form of the enzyme under aerobic conditions.

Animals↗
PubMed1998

State-dependent receptive-field restructuring in the visual cortex.

To extract important information from the environment on a useful timescale, the visual system must be able to adapt rapidly to constantly changing scenes. This requires dynamic control of visual resolution, possibly at the level of the responses of single neurons. Individual cells in the visual cortex respond to light stimuli on particular locations (receptive fields) on the retina, and the structure of these receptive fields can change in different contexts. Here we show experimentally that the shape of receptive fields in the primary visual cortex of anaesthetized cats undergoes significant modifications, which are correlated with the general state of the brain as assessed by electroencephalography: receptive fields are wider during synchronized states and smaller during non-synchronized states. We also show that cortical receptive fields shrink over time when stimulated with flashing light spots. Finally, by using a network model we account for the changing size of the cortical receptive fields by dynamically rescaling the levels of excitation and inhibition in the visual thalamus and cortex. The observed dynamic changes in the sizes of the cortical receptive field could be a reflection of a process that adapts the spatial resolution within the primary visual pathway to different states of excitability.

Animals↗