Biomedical subjects

Z Tian

Publications and source records attributed to Z Tian.

At least 37 records · Page 2Linked to original sources

PubMed2001

[New progress of surface enhanced Raman spectroscopic studies on a gold electrode in a nonaqueous system].

Based on a highly sensitive new generation confocal microprobe Raman system, the adsorption behavior of thiocyanate (SCN-) on a gold electrode in methanol solution was investigated by SERS for the first time. Preliminary results demonstrated that the interaction between SCN- and the electrode is so strong that its SERS signal can be detected in the whole research potential region (-0.1 V(-)-1.4 V). The orientation change may occur in the potential range -0.6 V-0.7 V. From -0.1 V to -0.6 V SCN- is adsorbed mainly through S end onto Au surface while in the potential range of -0.7 V to -1.2 V it is oriented mainly through N end. The potential dependence of the Raman frequency of nu CN resulted in two different values of electrochemical Stark effect, suggesting the existence of molecular orientation change.

Electrochemistry↗

PubMed2001

[Histological evaluation of the biocompatibility of PDLLA membranes].

OBJECTIVE: To evaluate the histological response and biocompatibility of implanted domestic bio-degradable PDLLA membranes in vivo. METHODS: The domestic biodegradable PDLLA membranes and non-degradable ePTFE membranes were in pairs placed subcutaneously in surgical incision made in the dorsum of rats. The tissue responses to these materials were observed histologically at 1, 2, 4, 8 and 12 weeks after placement. RESULTS: The tissue responses of the two kinds of materials were similar to the non-specific reaction mainly infiltrated with lymphocytes, plasmocytes, macrophages, and foreign body giant cells. The polymorphonuclears and foreign body giant cells infiltrated round the ePTFE membranes existed for a relatively long period, in contrast to that of PDLLA membranes. CONCLUSION: Domestic PDLLA membranes with good biocompatibility will be adapted to making GTR into a single step procedure.

English Abstract↗

PubMed2000

Cross-talk between interleukin 1beta (IL-1beta) and IL-6 signalling pathways: IL-1beta selectively inhibits IL-6-activated signal transducer and activator of transcription factor 1 (STAT1) by a proteasome-dependent mechanism.

Interleukin 1beta (IL-1beta) suppresses the IL-6-dependent induction of type II acute-phase response genes, but the underlying mechanism for this suppression remains uncertain. Here we report that treatment of human hepatocullular carcinoma HepG2 cells with IL-1beta inhibited the IL-6-dependent binding of signal transducer and activator of transcription factor (STAT)1, but not that of STAT3, to the high-affinity serum-inducible element ('SIE'). Furthermore, IL-1beta selectively down-regulated the IL-6-induced tyrosine phosphorylation of STAT1 without affecting the level of STAT1 or tyrosine phosphorylation of STAT3. Kinase assays in vitro indicated that the inhibition of STAT1 phosphorylation by IL-1beta was not due to an upstream blockade of Janus kinase (JAK1 or JAK2) activation. However, pretreatment with the proteasome inhibitor MG132 under conditions that prevented the IL-1beta-dependent activation of the nuclear factor NF-kappaB also blocked the inhibitory effect of IL-1beta on IL-6-activated STAT1. In related experiments, the protein tyrosine phosphatase inhibitor Na(3)VO(4) also antagonized the inhibitory effect of IL-1beta on the activation of STAT1 by IL-6. Taken together, these findings indicate that, by using a proteasome-dependent mechanism, IL-1beta concomitantly induces NF-kappaB activation and dephosphorylates IL-6-activated STAT1; the latter might partly account for the inhibition by IL-1beta of the IL-6-dependent induction of type II acute-phase genes.

Acute-Phase Proteins↗

PubMed2000

IL-1 beta attenuates IFN-alpha beta-induced antiviral activity and STAT1 activation in the liver: involvement of proteasome-dependent pathway.

IFN-alphabeta is the only established treatment for viral hepatitis; however, more than 60% of patients are poorly responsive. Because viral hepatitis is associated with inflammation, we hypothesized that inflammation may attenuate the efficacy of IFN therapy. To test this hypothesis, the effect of IL-1beta, one of the major proinflammatory cytokines, on IFN signaling pathway in the liver was examined. Administration of IL-1beta in vivo attenuated IFN-alphabeta-induced STAT1 tyrosine phosphorylation in the liver but not in the spleen. The inhibitory action of IL-1beta in vivo was not affected by depleting hepatic Kupffer cells, suggesting that IL-1beta may directly target IFN-alphabeta signaling in hepatocytes. Indeed, pretreatment of human hepatocellular carcinoma HepG2 cells with IL-1beta suppressed IFN-alphabeta-induced antiviral activity and antiviral protein MxA mRNA expression. Furthermore, IL-1beta attenuated IFN-alphabeta-induced STAT1 binding and tyrosine phosphorylation without affecting the level of STAT1 protein. This inhibitory effect can be reversed by pretreatment with either proteasome inhibitors or transfection of dominant negative NF-kappaB inducing kinase mutants. Taken together, these findings suggest that IL-1beta attenuates IFN-alphabeta-induced STAT1 activation by a proteasome-dependent mechanism. In view of high levels of IL-1beta in the serum or within the liver of patients with chronic liver diseases, attenuation of IFN-alphabeta signaling in the liver by IL-1beta could be one of the mechanisms underlying the resistance to IFN therapy in chronic hepatitis C, and IL-1beta could be a potential therapeutic target for improving the efficacy of IFN therapy.

Adjuvants, Immunologic↗

PubMed2000

Formation of concentration gradient and its application to DNA capillary electrophoresis.

A new method to introduce the concentration gradient into the capillary has been developed and its application to DNA capillary electrophoresis is presented. The concentration gradient produced by mixing 5% w/v polyacrylamide-co-poly(N-dimethylacrylamide) (PAM-co-PDMA) solution and 1 x Tris/N-tris(hydroxymethyl)methyl-3-amino-propanesulfonic acid/EDTA (TT) + 5 M urea buffer was successfully achieved by using two programmable syringe pumps with strict control of dead volume, flow rate, and pressure balance. This method has the advantages of high stability, reproducibility, and versatility. The column with concentration gradient greatly improved the resolution, especially for the large DNA fragments, due to a decrease in band width broadening with time. A column containing 2-4% w/v gradient in four steps had a longer read length, shorter separation time and better resolution (after 380 base) than that of 4% w/v single concentration polymer solution. The number of steps in the gradient had almost no effect on the performance. The change in the average concentration by relocating the position of the same step gradient, i.e., a combination of different low concentration to high concentration polymer solution ratios, resulted in a different migration time, read length and resolution.

Acrylamides↗

PubMed2000

Prevention of neurotoxin damage of 6-OHDA to dopaminergic nigral neuron by subthalamic nucleus lesions.

OBJECT: To investigate the possibility that subthalamic nucleus (STN) ablation could prevent the toxicity of the selective dopaminergic neurotoxin 6-hydroxydopamine (6-OHDA). METHODS: Sixty rats were divided into 6 groups (n = 10). The control group received a unilateral microinjection of 6-OHDA into the right ventral tegmental area (VTA) and the right median forebrain bundle (MFB). Group 1 received an administration of kainic acid (KA) into the right STN and, 1-week later, an injection of 6-OHDA in the right VTA and MFB. Groups 2-5 received an injection of 6-OHDA in the right VTA and MFB, 1 h, 2 h, 3 days, and 7 days before KA in the right STN respectively. Four weeks later, the changes of tyrosine hydroxylase (TH)-positive (dopaminergic) neurons in the SNc were investigated with immunocytochemical and morphometrical methods. RESULTS: The number of TH-positive cells in the SNc on the injected side of treated groups (groups 1-5) and control group were 71.46 +/- 6.84, 57.07 +/- 5.54, 51.09 +/- 4.85, 12.68 +/- 2.67, 4.15 +/- 1.60 and 3.40 +/- 1.54/slice, which decreased to 96.7, 72.9, 69.8, 17.2, 5.6 and 4.4% of the non-injected side, respectively. The number of TH-positive neurons in groups 1-4 significantly increased in comparison with the controls (p < 0.05, 0.01). In group 5, there were no remarkable differences in contrast to the number of TH-positive neurons of the controls (p > 0.05). The difference in the number of TH-positive neurons between groups 1-5 was statistically significant (p < 0.01). CONCLUSION: The results indicate that STN ablation can provide antiglutamate-based neuroprotection of the dopaminergic nigrostriatal pathway against 6-OHDA toxicity.

Afferent Pathways↗

PubMed2000

Stereotactic biopsy for intracranial space-occupying lesions: clinical analysis of 550 cases.

OBJECT: To investigate the role of stereotactic biopsy in planning the optimal management of intracranial space-occupying lesions. PATIENTS AND METHODS: Between December 1989 and December 1999, stereotactic biopsy was performed in 550 patients with intracranial mass lesions that were deep-seated or located in the functional area. There were 340 males and 210 females, and their ages ranged from 4 to 75 years. All the procedures were done under local anesthesia with a Leksell stereotactic system. A CT scan was used to determine the coordinates in the first 420 cases and the Aero Tech Stereotactic Surgical Plan System in the subsequent 130 patients. RESULTS: Brain tumors were diagnosed pathologically in 475 patients (86.4%), inflammatory process in 44 (8.0%), other lesions in 12 (2.2%) and no conclusive diagnosis was found in 19 (3.4%). The overall positive rate of biopsy was 96.6%, and the positive rate for brain tumor was 86.4%. Intracranial hematomas after biopsy were found in 13 cases (2.4%). Seizures occurred during the operation in 7 cases (1.2%), and slight and transient neurological deficits were found in 23 cases (4.2%). There were no deaths or other serious complications. CONCLUSIONS: The results suggest that the stereotactic biopsy is a reliable method to obtain histopathological diagnosis of intracranial mass lesions, and it is also of great help in selecting the appropriate management.

Adolescent↗

PubMed2000

[Effects of adhesive proteins on endothelialization of PC crosslinking yak pericardial materials--an experimental study].

To investigate the conditions of endothelialization of biomaterials, we examined in vitro the growth properties of endothelial cells on PC treated yak pericardial materials. After rinsed in normal saline (0.9%), the surface of PC crosslinking yak pericardial materials was precoated with three kinds of adhesive proteins--Laminin (La), Fibronectin(FN) and Collagen-I(CL-I). Ednothelial cells(EC) from the canine were seeded on the precoated materials, and on the uncoated materials as control. The result showed that in the La and FN groups the seeded EC survived and grew on the patches, while in the CL-I group and uncoated group the seeded EC on and around the patches did not continue to live. Conclusively, in this experiment, PC yak pericardial materials had cytotoxicity; the cytotoxicity of PC crosslinking yak pericardial materials could be decreased by La and FN precoating; La and FN promoted the adhesion and growth of EC on the PC yak pericardial materials patches; the materials met the needs of endothelialization in vitro, prominently in the La group; there was significant difference in endothelialization between La and FN groups (P < 0.05); CL-I had no part in promoting EC adhesion and growth.

Animals↗

PubMed2000

The expression of E-cadherin-catenin complex in adenoid cystic carcinoma of salivary glands.

OBJECTIVE: The aim of this study was to investigate the expression of the E-cadherin-catenin (E-cad-cat) complex in human salivary adenoid cystic carcinoma (ACC) and determine the effects of E-cad-cat expression on tumor differentiation, metastasis, and invasion, as well as its clinical significance. METHODS: The expression of adhesion molecules, which included E-cadherin, alpha-catenin, and beta-catenin, on 10 cases of normal salivary glands, and 50 cases of human salivary ACC were investigated by immunohistochemistry. RESULTS: Strong and stable expression of E-cad-cat complex showed in normal salivary glands tissues. However, weaker expression and even complete absence, of the positive signals were shown on all ACC cases. Coexpression of E-cad-cat were detected in 29 (58%) of the 50 ACC specimens. Positive staining of E-cad-cat complex were detected in 7 (39%) of the 18 ACC primary sites that had aggressive phenotype of nerve and vasculature. CONCLUSION: Strong positive signals of E-cad-cat complex are shown in normal salivary glands, and the down-regulated expression were observed in ACC cases. The expression of E-cad-cat complex is associated with a more aggressive phenotype on nerve and vasculature. No association with various histopathologic subtypes was found. However, absent or low E-cad expression was observed more frequently in solid carcinomas than in cribriform or tubular carcinomas. Down-regulation of E-cad-cat complex may be associated with canceration of normal salivary glands. The expression levels of E-cad-cat were positively correlated to the differentiation of ACC tumor cells.

Antibodies, Monoclonal↗

PubMed2000

[Evaluation of modified maze procedure by Doppler tissue imager].

Since 1998 the cardiac surgeons of WCUMS have performed modified maze procedure for treating the patients with rheumatic mitral valve disease accompanied with chronic atrial fibrillation (Af). In this study, echocardiography, especially Doppler Tissue Imager (DTI), was used to evaluate atria contraction and function of such patients before and after the operation. 14 rheumatic mitral disease patients, aged 27-60 years, were chosen; among them, 11 had mitral stenosis, 3 mitral regurgitation. The control group consisted of 16 cases, aged 24-67 years, with normal echocardiogram. Before and half-1 year after the operation, left atrium, left ventricle, right atrium and ventricle were measured, and cardiac function and posterior wall motion of left atrium were measured. Velocity of mitral valve annual and tricuspid valve annual was measured in DTI. The results showed: There was no age difference between the two groups. The motion of posterior wall of left atrium was 4.18 +/- 0.37 mm in the operation group, 4.09 +/- 0.29 mm in the control group (P > 0.05). No difference in velocity of mitral/tricuspid valve annual between the two groups was observed; 3 peaks of mitral valve annual were S 0.11 +/- 0.02, e 0.11 +/- 0.01, a 0.09 +/- 0.01 (m/s) in operation group, and S 0.08 +/- 0.00, e 0.10 +/- 0.01, a 0.08 +/- 0.01 (m/s) in control group, (P > 0.05, respectively); 3 peaks of tricuspid valve annual were S 0.10 +/- 0.01 vs 0.11 +/- 0.08, e 0.11 +/- 0.08 vs 0.10 +/- 0.01, a 0.10 +/- 0.10 vs 0.09 +/- 0.01 (m/s), (P > 0.05, respectively). The diameter of left atrium after operation in cases of mitral stenosis decreased significantly, compared with that before operation (P < 0.01). The diameter of right atrium after operation decreased significantly, compared with that before operation (P < 0.01). There was no significant change in right ventricle/left ventricle/EF and FS. The diameter of left atrium after operation in cases of mitral regurgitation decreased significantly, compared with that before operation (P < 0.01). The diameter of left ventricle after operation decreased significantly, compared with that before operation (P < 0.05). No significant change in right ventricle/right atrium/EF and FS was noted. The authors conclude the DTI, as a new diagnostic method in echocardiography, has high sensitivity and is less influenced when used to observe motion of atrium-ventricle annual influenced. It can avoid the error caused by deviation of blood displacement. In the rheumatic mitral valve disease patients who had mitral valve replacement and modified maze procedure, atrial contraction respores, the risk of thromboembolism decreases and prognosis improves. So the operation is worth doing.

Adult↗

PubMed2000

[Preliminary echocardiographic evaluation on prosthetic valve replacement of preserving the subvalvular apparatus with artificial chorade for mitral stenosis].

The purpose of this study was to evaluate the preliminary results after prosthetic valve replacement of preserving the subvalvular apparatus with artificial chorade for mitral stenosis. 20 patients had received operation with expanded polytetrafluoroethylene(e-PTFE) as artificial chordade. The patients were followed up by means of echocardiography. The time of follow-up study varied from 4 to 18 months with a mean of 6 months. The left atrial, ventricular dimension as well as ventricular function were assessed. In addition, the length of artificial chorade and obstruction of left ventricular outflow track were observed. The results showed that left atrial diameter (LAD, from 57.59 +/- 13.51 mm to 47.05 +/- 9.55 mm), left ventricular end-diastolic dimension (LVEDD, from 46.23 +/- 12.56 mm to 42.41 +/- 10.86 mm), left ventricular end-systolic dimension (LVESD, from 33.50 +/- 10.20 mm to 29.68 +/- 8.40 mm) decreased (P < 0.01), and ejection fraction (EF, from 52.59 +/- 11.89% to 58.36 +/- 8.03%) increased (P < 0.05) after operation. There were no significant changes of fractional shortening (FS, from 29.23 +/- 8.99% to 31.05 +/- 6.08%). The length of artificial chorade ranged from 2.6 cm to 4.3 cm (the mean, 3.2 cm). There was no case of obstruction of left ventricular outflow track. It is believed that the result of preliminary echocardiographic observation on prosthetic valve replacement of preserving the subvalvular apparatus with artificial chorade for mitral stenosis is satisfactory.

Adult↗

PubMed2000

[Development of a system for Polymyxa graminis infection and transmission of wheat yellow mosaic virus].

In growth chambers, a system was developed for infection of Polymyxa graminis to wheat(Triticum aestivum L.), which is an obligate parasite. By the system, the fungus could be propagated in large quantity rapidly and the life cycle of P. graminis in wheat was observed in a period of 13 to 15 days. The methods for separating P. graminis as single cystosori from cultured wheat roots or dried roots were simplified. By tests for the factors affecting on P. graminis infection, including inocula types, seedling age of host plants, temperatures, pH value and nutrient contents etc., the system was modified to more perfection. With an integration of optimal temperature and other elements in the system, which affect on infection and development of P. graminis, wheat yellow mosaic virus (WYMV) was transmitted constantly and efficiently by the fungal vector. In average, 70% of wheat plants inoculated by the viruliferous fungi could infected by WYMV and the typical symptom of wheat mosaic disease would appear at 30 days post-inoculation mechanically.

Ascomycota↗

PubMed2000

[A quantum chemical study of pi-back-donation bond and Raman intensity of 1 sigma + electronic state of Pt-CO molecule].

The Raman spectroscopic properties of Pt-CO molecule have been investigated based on the electronic state 1 sigma + determined by the HF and B3LYP methods. The result shows that the calculated stretching vibrational frequencies of the Pt-C and C-O bonds depend on the method and the basis sets used. It indicates that it is important to adopt an appropriate method to describe pi-donation and pi-back-donation bond. The result of the differential Raman scattering cross section for the stretching vibrations of the Pt-C and C-O bond shows that the latter is significantly larger value compared to the former.

Adsorption↗

PubMed2000

[Two-dimensional surface Raman imaging of a roughened iron electrode in saline solution].

By using a confocal microprobe Raman system and proper surface roughening procedure for iron, the pit corrosion behavior of bare iron electrode in 3.4% NaCl (saline solution) solution has been investigated. The surface-enhanced Raman scattering (SERS) spectra of the corrosion products due to the pit corrosion at positive potential was obtained with high ratio of signal to noise. The application of SERS technique has been extended successfully to the study of iron corrosion. The two-dimensional surface Raman imaging acquired at 660 cm-1 was obtained also with the utility of surface Raman image technique. Results show that different iron oxides should coexist in the pit corrosion region and the distribution of the corrosion products was not uniform.

Chemical Phenomena↗

PubMed2000

[Surface Ramam spectropscopy for in situ investigating silicon etching process].

In situ surface Raman spectroscopy has been extended to study silicon electrode surfaces by optimizing the Raman system and the surface roughening method. The time-dependent etching processes were monitored in a dilute HF aqueous solution and the initial oxidation processes of the hydrogen-terminated surface in different pHs were studied at the open circuit potential. The results indicate that the silicon surface could be overwhelmingly terminated with hydrogen rather than fluorine in the HF-based solution. The smoothening effect of OH- on the silicon surface is through the attack of the = SiH2 site. It demonstrates that Raman spectroscopy is a powerful in situ technique for investigating the etching process of silicon surface.

Electrochemistry↗

PubMed2000

[Application of confocal microprobe Raman spectroscopy in the analysis of interfaces].

Confocal microprobe Raman spectroscopy has been applied to the study of liquid/gas and solid/liquid interfaces. With the help of the resonance Raman effect, the aggregation process of TSPP has been monitored at the liquid/gas interface using Raman spectroscopy, which is shown to have very different behavior compared with that in the bulk. The solution layer analysis has been performed in the interfacial region above a Pt electrode under reaction, and the solution composition is monitored in situ during the electrochemecial reaction. Taking the advantage of high spatial resolution of the confocal microscope, the surface enhanced Raman imaging has been performed on the electrodeposited gold surface.

Electrochemistry↗

PubMed1999

[Effect of activated donor-type NK cells on allogeneic bone marrow transplantation in mice].

OBJECTIVE: To study the effect of activated donor-type NK cells on allogeneic bone marrow transplantation(BMT). METHODS: Four hours before or 72 hours after transfusing bone marrow cells(containing T cells), the activated donor-type NK cells were injected into tumor-bearing mice conditioned by irradiation. The effect of these NK cells were assessed by CFU-S, CFU-GM, survival, body weight, histopathology and lung metastases in the recipients. RESULTS: The transfusion of activated donor-type NK cells markedly increased CFU-S and CFU-GM numbers. When these NK cells were transfused 4 hours before BMT, they augmented GVT yet inhibited GVHD as evidenced by increases in survival duration and body weight, reduction in grade of histopathological changes and decrease in lung metastases. However, when activated donor-type NK cells were transfused 72 hours after BMT, they exacerbated GVHD. CONCLUSIONS: The activated donor-type NK cells could prevent GVHD and produce significant GVT effects and also resulted in greater hematopoietic reconstitution if they were at the initial stage of allogeneic BMT in mice. Thereafter, the activated donor-type NK cells were detrimental and could exacerbate the subsequent GVHD, these results also demonstrated that GVT and GVHD could be dissociable phenomena.

Animals↗

PubMed1999

[Experimental study of LAK and activated NK cells affecting hematopoiesis in mice].

OBJECTIVE: To study the relationship between LAK/activated NK cells and hematopoiesis as well as the effects of LAK/activated NK cells on hematopoietic reconstitution after syngeneic bone marrow transplantation(BMT) in mice. METHODS: 1. LAK/activated NK cells were cocultured with bone marrow cells(BMC) in semi-solid agar medium to determine their effects on CFU-GM formation. 2. Syngeneic LAK/activated NK cells were transferred with BALB/c BMCs into lethally irradiated syngeneic recipients to determine their effects on hematopoietic reconstitution. RESULTS: When BMC were cultured under optimal growth conditions in the presence of exogenous hematopoietic growth factors, the effects of LAK/activated NK cells were mainly inhibitory. However, when BMCs were cultured under growth-limiting conditions without exogenous hematopoietic growth factors, the LAK/activated NK cells could support CFU-GM formation. Syngeneic LAK/activated NK cells significantly increased CFU-S and CFU-GM numbers after syngeneic BMT, and also significantly improved platelet and white blood cell count. CONCLUSIONS: LAK/activated NK cells could be bidirectionally regulate CFU-GM formation in vitro and promote hematopoietic reconstitution after syngeneic BMT in mice.

Animals↗