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Biomedical subjects

Qiang Zhao

Publications and source records attributed to Qiang Zhao.

At least 37 records · Page 2Linked to original sources
PubMed2005

Direct proteins electrochemistry based on ionic liquid mediated carbon nanotube modified glassy carbon electrode.

A novel glassy carbon electrode modified by a gel containing multi-walled carbon nanotubes (MWNTs) and ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) is reported. The gel is formed by grinding of MWNTs and BMIPF6. Such gel is then coated on the surface of a glassy carbon electrode. We have employed scanning electron microscopy, Fourier transform infrared spectrometry (FTIR) and cyclic voltammetry to characterize the modified electrode. The direct electron transfers of hemoglobin and catalase on the modified electrode have been observed and studied in detail electrochemically. Hemoglobin is verified to be adsorbed on the modified electrode with the retention of conformation, which has been proved by microscopic FTIR. The electrochemical response of the adsorbed hemoglobin on the modified electrode is very stable, and shows repeated changes in the different pH solutions. It also has shown electrocatalysis to the reduction of oxygen and trichloroacetic acid. Catalase adsorbed on the gel modified electrode still keep activity to hydrogen peroxide. This work provides a simple and easy approach to construct biosensors based on the carbon nanotubes and ionic liquids.

Carbon↗
PubMed2005

Programmed humidifying in drug stability experiments.

The stability of penicillin potassium, as a solid state model, was investigated by a programmed humidity and temperature controlled method. An optimization calculational approach to data handling is suggested. The stability of drugs which are unstable to both heat and moisture could be studied by a single pair of experiments, one with programmed humidity control and one non-isothermal, rather than many standard isothermal studies, each at constant relative humidity. The controlling system, based on a pocket computer, was found to be accurate and reliable. The results indicated that the kinetic parameters obtained were comparable to those from isothermal studies.

Drug Stability↗
PubMed2005

Repair of sheep metatarsus defects by using tissue-engineering technique.

Tissue-engineering bone with porous ,betatricalcium phosphate (3-TCP) ceramic and autologous bone marrow mesenchymal stem cells (MSC) was constructed and the effect of this composite on healing of segmental bone defects was investigated. 10-15 ml bone marrow aspirates were harvested from the iliac crest of sheep, and enriched for MSC by density gradient centrifugation over a Percoll cushion (1. 073 g/ml). After cultured and proliferated, tissue-engineering bones were constructed with these,cellS seeded onto porous f-TCP, and then the constructs were implanted in 8 sheep left metatarsus defect (25 mm in length) as experimental group. Porous ,-TCP only were implanted to bridge same size and position defects in 8 sheep as control group, and 25 mm segmental bone defects of left metatarsus were left empty in 4 sheep as blank group. Sheep were sacrificed on the 6th, 12th, and 24th week postoperatively and the implants samples were examined by radiograph, histology, and biomechanical test. The 4 sheep in blank group were sacrificed on the 24th week postoperatively. The results showed that new bone tissues were observed either radiographic or histologically at the defects of experimental group as early as 6th week postoperatively, but not in control group, and osteoid tissue, woven bone and lamellar bone occurred earlier than in control group in which the bone defects were repaired in "creep substitution" way, because of the new bone formed in direct manner without progression through a cartilaginous intermediate. At the 24th week, radiographs and biomechanical test revealed an almost complete repair of the defect of experimental group, only partly in control group. The bone defects in blank group were non-healing at the 24th week. It was concluded that engineering bones constructed with porous -TCP and autologous MSC were capable of repairing segmental bone defects in sheep metatarsus beyond "creep substitution" way and making it healed earlier. Porous ,-TCP being constituted with autologous MSC may be a good option in healing critical segmental bone defects in clinical practice and provide insight for future clinical repair of segmental defect.

Animals↗
PubMed2005

Paracrine action enhances the effects of autologous mesenchymal stem cell transplantation on vascular regeneration in rat model of myocardial infarction.

BACKGROUND: There are several reports that engrafted mesenchymal stem cells (MSCs) stimulate angiogenesis in the ischemic heart, but the mechanism remains controversial. We hypothesize that transplantation of MSCs enhances vascular regeneration through a paracrine action. METHODS: A transmural myocardial infarction was created by ligation of the left anterior descending coronary artery in rats. Those with an ejection fraction less than 0.70 1 week after myocardial infarction were included. Autologous MSCs (1 x 10(7); 0.2 mL) or culture medium (0.2 mL) was injected intramyocardially into the periinfarct zone (50 microL/injection at four sites; n = 20/group). At 2 weeks after transplantation, Western blot analysis was used to assay the paracrine factors and proapoptotic proteins. Echocardiography to assess heart function was performed on additional groups at 8 weeks after implantation. RESULTS: The angiogenic factors basic fibroblast growth factor, vascular endothelial growth factor, and stem cell homing factor (stromal cell-derived factor -1alpha) increased in the MSC-treated hearts compared with medium-treated hearts. This was accompanied by a downregulation of proapoptotic protein Bax in ischemic myocardium. Similarly, capillary density increased about 40% in MSC-treated hearts compared with medium-treated hearts (p = 0.001). Left ventricular contractility, indicated by fractional shortening, improved in MSC-treated hearts at 2 months after implantation (MSCs: 48.6% +/- 19.9%; medium: 18.7% +/- 6.4%; p = 0.004). CONCLUSIONS: Autologous MSC transplantation attenuates left ventricular remodeling and improves cardiac performance. The major mechanism appears to be paracrine action of the engrafted cells, increasing angiogenesis and cytoprotection.

Angiogenesis Modulating Agents↗
PubMed2005

[Upregulating the expression of angiogenesis-related genes by transplanting autologous mononuclear bone marrow cells into myocardial infarction scar and the periphery].

OBJECTIVE: To detect the regulation of angiogenic genes involved in the processes of collateral development. METHODS: Myocardial infarction (MI) scar was induced by cryoinjury in New Zealand rabbits. Four weeks after MI, 24 hours before cell transplantation, bone marrow was aspirated from the right thigh bone and mononuclear bone marrow cells (BMCs) were isolated by Ficoll density gradient centrifugation. Then the mononuclear BMCs (n = 8) or IMDM culture medium (n = 8) were transplanted into infarction scar and the periphery. Four weeks after mononuclear BMCs transplantation, DNA microarray analysis was performed to detect the regulation of angiogenesis-related genes in infarction scar and the periphery. And the differences of angiogenic genes expression were compared among several important growth factors by Western blot. RESULTS: DNA microarray analysis showed the detail regulation of genes involved in the angiogenic processes. There were 15 genes upregulated over 3 times in the infarction scar. In addition, we also found more genes are involved in the process of angiogenesis in its periphery than in the infarction scar (40 genes vs. 15 genes). Western bolt analysis further demonstrated that mononuclear BMCs transplantation was capable of increasing the levels of VEGF, FGF and Angiopoietin-I expression in the infarction scar and its periphery, compared with the control group, P < 0.05. CONCLUSION: These findings indicate that the natural angiogenic processes leading to collateral development are extremely complex, since many kinds of bone marrow-derived growth factors involved in the processes after mononuclear BMCs transplantation into infarction sites.

Animals↗
PubMed2005

[Effect of RGD peptide on adhesive stability of human umbilical vein endothelial cell on polyethylene terephthalate surface].

In this study for exploring the effect of RGD peptide on adhesive stability of endothelial cells biomaterial surface, all materials were divided into three groups, RGD group (PET covalently grafted synthetic RGD peptides), control group (PET precoated with fibronectin) and blank group (Non-coated surface). Cultured human umbilical vein endothelial cells (HUVECs) were seeded on the materials, then adhesive stability of HUVECs on the varied PET surfaces was observed under steady flow condition, and effects of shear stress and shear time on adherent cells were compared. The results showed that the resistance adherent endothelial cells to detachment by flow was shear stress and shear time dependent. Comparison three groups under the same condition revealed that the ECs retention rates of RGD-grafted or fibronectin-coated group were much higher than that of the non-coated group. Under 8.19 dyne/cm2 shear stress after 4h, retention rates were 13.73% (blank group), 43.33% (RGD group) and 40.75% (control group) respectively. These data indicated that RGD peptide can improve the adhesive stability of endothelial cell on biomaterial and the effect of RGD in vivo needs further studies.

Biocompatible Materials↗
PubMed2005

[Kinetic study on the degradation of penicillin potassium at different temperature and relative humidity].

OBJECTIVE: To perform a kinetic analysis and formulation of the degradation of penicillin potassium in the solid phase at different temperature and relative humidity. METHODS: Penicillin potassium was incubated in a temperature-and-humidity-controlled oven at different temperature and relative humidity, and was determined by HPLC at suitable time intervals during the incubation. RESULTS: The reaction rate was expressed as -dc/dt=k(c0-c+B), where c is the residual concentration, k degradation rate constant, c0 original concentration and B a constant related to original concentration of degradant. Degradation curves were fitted with c=c0-Bexp (kt)+B. The k was expressed as k=Aexp(-Ea/RT)exp(mHr), where active energy E. is 77.26 kJ/mol and constant m 0.1159. CONCLUSION: The degradation of penicillin potassium could be expressed with c=c0-Bexp [Aexp (-Ea/RT)exp (mHr)t]+B.

Drug Stability↗
PubMed2005

[Charge control and IR analysis of amine on diarylide yellow pigment PY14].

To study the reaction of amine with dairylide yellow pigment (PY14) used in electrophoretic display, especially the reaction mechanism between polyisobutylene imide (PIBI) and PY14, some amines were selected to react with PY14. At the same time, tetraethylene pentamine was treated with HCl. The zeta potential and IR of the above products were tested. Based on the zeta potential and IR frequency, the charge control intensities of different amines on PY14 were compared, and it is confirmed that the reaction of PY14 with amines is Lewis reaction, the charge control of secondary and primary amines with less steric obstacle is stronger. The PY14 zeta potential value reverse is due to the adsorption of bigger reverse ion.

English Abstract↗
PubMed2005

Myoangiogenesis after cell patch cardiomyoplasty and omentopexy in a patient with ischemic cardiomyopathy.

We describe a procedure to promote angiogenesis and impregnation of skeletal myoblast into infarcted myocardium. At the completion of coronary artery bypass surgery, the midline sternotomy incision was extended to open the abdomen, and the greater omentum was tailored to reach the myocardium. Four pieces of autologous rectus muscle were applied to the infarcted left ventricle. This implantation was reinforced by the greater omentum. Incisions were closed in the usual manner. Postoperatively, the patient showed significant improvements in left ventricular ejection fraction (from 0.15 to 0.40) and in exercise tolerance (from 3 METs to 6 METs, or 100%). Computed tomographic angiography and positron emission tomography demonstrated improved myocardial viability and vascularity in the ischemic segments of the left ventricle. Omentopexy and cell patch cardiomyoplasty in conjunction with coronary artery bypass surgery may stimulate myogenesis and angiogenesis in avascular, dyskinetic scar tissue of left ventricle; in this preliminary study, this procedure appeared to improve the functional capacity of the left ventricle.

Cardiomyoplasty↗
PubMed2004

Crystallization and preliminary crystallographic studies of human coactosin-like protein (CLP).

The human coactosin-like protein (CLP) belongs to the actin-depolymerizing factor (ADF) family of actin-binding proteins. CLP interacts with 5-lipoxygenase (5LO) and filamentous actin (F-actin) via different binding sites. The full-length CLP comprising of 142 amino acids has been overexpressed in Escherichia coli. Crystals of CLP were obtained using the hanging-drop vapour-diffusion technique with ammonium sulfate as precipitant at pH 8.5. Diffraction data to 1.9 A resolution were collected from a crystal belonging to space group P2(1), with unit-cell parameters a = 25.6, b = 55.2, c = 37.4 A, beta = 96.0 degrees. There is one molecule per asymmetric unit.

Actins↗
PubMed2004

[Orthotopic heart transplantation: clinical experience on 56 patients].

OBJECTIVE: To summarize the clinical experience on 56 patients undergoing orthotopic heart transplantation. METHODS: Between May 2000 and December 2003 56 patients, 47 with cardiomyopathy, 2 with end-stage valvular heart disease, 2 with end-stage ischemic heart disease, 2 with primary malignant cardiac tumor, 1 with complicated congenital heart disease, 1 with muscular dystrophy cardiomyopathy, and 1 with refractory malignant ventricular arrhythmias, underwent orthotopic heart transplantation in the Transplantation Center of Fudan University. The operative procedures included 19 conventional Stanford orthotopic cardiac transplantation in 19 cases and bicaval anastomotic cardiac transplantation in 37 cases. Postoperatively, the patients were prescribed with cyclosporine A + corticosteroids + MMF or FK506 + corticosteroids + MMF as anti-rejection therapy. RESULTS: One patient undergoing his fifth operation died of bleeding 3 days after operation. All survivors were followed-up for 12.4 months on average. Five patients died within 1 year postoperatively with a one-year survival rate of 91%. One patient died of allograft vasculopathy 38 months after operation. Other patients enjoyed heart function recovering to class I-II (NYHA). CONCLUSION: With proper recipient selection, excellent donor heart conservation, bicaval anastomotic technique, and efficient postoperative surveillance and treatment, heart transplantion may produce satisfying mid-term results.

Adolescent↗
PubMed2004

Electrochemical investigation of dopamine at the water/1,2-dichloroethane interface.

Dopamine is an important neurotransmitter in mammalian central and peripheral nervous systems and is also a medicament to cure some neuropsychosis. In this work, ion transfer (IT), facilitated ion transfer (FIT) of protonated dopamine, and electron transfer (ET) between dopamine and ferrocene are investigated at the water/1,2-dichloroethane (W/DCE) interface. The IT and FIT reactions of protonated dopamine can be observed simultaneously within the same potential window. The experimental results demonstrate that dibenzo-18-crown-6, dibenzo-24-crown-8, and benzo-15-crown-5 work well with the protonated dopamine. The amperometric detection of dopamine based on either the IT or the FIT of protonated dopamine can get rid of the interference of ascorbic acid, and the lowest concentration that can be determined is approximately 0.05 microM by differential pulse voltammetry. For the ET reaction, its kinetics can be evaluated by scanning electrochemical microscopy, and the results show that the relationship between rate constants and driving force at the unmodified W/DCE interface obeys the Butler-Volmer equation in a rather wide potential region. When the W/DCE interface is modified by egg lecithin, the ET rate constants decrease with increasing concentration of egg lecithin, which indicates that egg lecithin hinders the ET reaction. When the driving force is increased to a certain degree, the linear relationship between ET rate constants and the driving force is distorted. These results will be helpful to understand both the pharmacodynamics and the neural signal transmission mechanism of dopamine at biological membranes and also provide a novel way to detect dopamine.

Dopamine↗
PubMed2004

Generalized log-rank test for mixed interval-censored failure time data.

This paper considers the problem of non-parametric treatment comparisons when mixed interval-censored failure time data are available, which often occurs in clinical trials and epidemiological studies. By mixed interval-censored data, we mean that the survival time of interest is observed to belong to an interval or to be right-censored. For the problem, we generalize the most commonly used log-rank test for right-censored survival data. Numerical studies are conducted and reported to evaluate and compare the proposed test with the existing method, which indicate that the presented method works well. We apply the method to a data set arising from an AIDS cohort study, that motivated the study.

Cohort Studies↗
PubMed2004

Structural features of the rice chromosome 4 centromere.

A complete sequence of a chromosome centromere is necessary for fully understanding centromere function. We reported the sequence structures of the first complete rice chromosome centromere through sequencing a large insert bacterial artificial chromosome clone-based contig, which covered the rice chromosome 4 centromere. Complete sequencing of the 124-kb rice chromosome 4 centromere revealed that it consisted of 18 tracts of 379 tandemly arrayed repeats known as CentO and a total of 19 centromeric retroelements (CRs) but no unique sequences were detected. Four tracts, composed of 65 CentO repeats, were located in the opposite orientation, and 18 CentO tracts were flanked by 19 retroelements. The CRs were classified into four types, and the type I retroelements appeared to be more specific to rice centromeres. The preferential insert of the CRs among CentO repeats indicated that the centromere-specific retroelements may contribute to centromere expansion during evolution. The presence of three intact retrotransposons in the centromere suggests that they may be responsible for functional centromere initiation through a transcription-mediated mechanism.

Base Sequence↗
PubMed2004

Rational design of azepane-glycoside antibiotics targeting the bacterial ribosome.

RNA recognition by natural aminoglycoside antibiotics depends on the 2-deoxystreptamine (2-DOS) scaffold which participates in specific hydrogen bonds with the ribosomal decoding-site target. Three-dimensional structure information has been used for the design of azepane-monoglycosides, building blocks for novel antibiotics in which 2-DOS is replaced by a heterocyclic scaffold. Azepane-glycosides showed target binding and translation inhibition in the low micromolar range and inhibited growth of Staphylococcus aureus, including aminoglycoside-resistant strains.

Aminoglycosides↗
PubMed2004

[Infection after cardiac transplantation: prevention and management].

OBJECTIVE: To explore and sum up the characteristics of infection after cardiac transplantation and to discuss the prophylaxis and management. METHOD: From May 2000 to April 2003, 36 patients received orthotopic heart transplantation, the clinical data were observed and analyzed. RESULTS: Infection occurred in 2 (6%) cases, both belonged to lung infection caused by human cytomegalovirus. The 2 cases were cured by ganciclovir intravenously. CONCLUSION: Good prophylactic method may decrease post cardiac transplantation infection significantly. It is very important to early diagnose and treat infection.

Adolescent↗