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Biomedical subjects

Yan Zhang

Publications and source records attributed to Yan Zhang.

At least 181 records · Page 10Linked to original sources
PubMed2006

[Evaluating comprehensive quality of sediment in Dianchi Lake using adjusted AHP method and 137Cs dating].

It is difficult to evaluate comprehensive quality of sediment and to understand development trend of pollution because of absence of monitoring data, especially history data. Combining the method of 137Cs dating with the ways of general sampling and measurement can easily resolve the problem of absence of data and also provide the possibility for calculating weighted environmental quality comprehensive index using the adjusted analytical hierarchy process (AHP) method. In order to overcome the willfulness the judgment matrix is formed objectively based on calculating monitoring data. Based on the monitoring data of sediment pollution and the weights of various factors gained by adjusted AHP method the comprehensive quality of sediment in each zone of Dianchi Lake was evaluated and the results indicated that the pollution of sediments in each zone at the present be serious more than that in the history. The condition may be related to the industrial development and distribution of industries in Dianchi Lake basin. Therefore, in order to improve the comprehensive quality of sediment in Dianchi Lake and to prevent the secondary pollution of heavy metals in sediment from happening, it is necessary to control the pollutants discharge and to remove the pollutants with various ways.

Cesium Radioisotopes↗
PubMed2006

[Echogenic phospholipids-based gas-filled microbubbles as delivery system of antisense oligodeoxynucleotides].

AIM: To investigate the feasibility of transfer antisense oligodeoxynucleotides (AS-ODNs) by the phospholipids-based gas-filled microbubbles (PGM) under ultrasound activation. METHODS: An antisense oligodeoxynucleotides sequence ZL combined with luciferase reporter plasmid was used. A breast cancer cell line SK-BR-3 was exposed to different conditions to investigate the effects of such factors as ZL concentration, PGM concentration, mechanical index (MI) and ultrasound exposure duration on transfection efficiency and cell viability. The transfection efficiency and cell viability by other lipid vectors such as lipofectamine and liposome were also tested, whose results were comparied with that of PGM. Transfection efficiency was detected by fluorescence microscopy. Cell viability was verified by PI (propidium iodide) assay. RESULTS: Among the factors tested, ultrasound exposure duration, MI and PGM concentration had obvious impacts on transfection efficiency and cell viability. The results showed that the optimal ultrasound condition was the exposure to ultrasound at MI 1.0 for 30 s with 2% PGM concentration, which gave an overall transfection efficiency of 78% +/- 10%, increased nearly 18 folds over the transfection by PGM (4.0%) or lipofectamine (4.3%) without ultrasound. Under same ultrasound conditions, different vectors showed significant difference in transfection efficiency while there are similar results in cell viability. CONCLUSION: Under proper ultrasound conditions, PGM can markedly enhance AS-ODNs transfection efficiency.

Breast Neoplasms↗
PubMed2006

Phase-contrast magnetic resonance angiography for assessment of intracranial venous sinus lesions.

OBJECTIVE: To review the presentations of intracranial venous sinus lesions in phase-contrast (PC) magnetic resonance angiography (MRA) and discuss the diagnostic value of this imaging modality for these lesions. METHODS: This study involved 52 patients with intracranial venous sinus lesions, including 21 with dural venous sinus malformation, 7 dural arteriovenous fistula (6 caroticocaveneous fistula, CCF), 5 venous sinus thrombus and 19 meningioma invading the venous sinuses. All patients underwent PC and time-of-flight (TOF) MRA with a 1.5 Tesla MR scanner, with 28 of them undergoing subsequent digital subtraction angiography (DSA). RESULTS: PC MRA showed extensive hyperintense signals that identified the lesions, feeding arteries, deferent veins and venous sinuses in 21 cases of dural arteriovenous fistula, but the lesion signals appeared homogeneous. In these cases, PC and TOF MRA had equally good performance in displaying the feeding arteries with success in 20 of the 21 cases (95.2%), whereas the former resulted in a greater rate of deferent vein display [90.5% (19/21)] than the latter [76.2% (16/21), P<0.05]. The 6 CCF cases showed ipsilateral cavernous sinus expansion and upper ophthalmic vein dilations. In the 5 cases of venous sinus thrombis, 4 had transverse sinus thrombus and 1 superior sagittal sinus thrombus. All the cases presented signal disappearance in the sinuses in PC MRA and hyperintense signals in MRI, and some cases had also cerebral superficial hemorrhage and edema. The 19 cases of meningioma invading the venous sinus displayed sinus shift, stenosis and occlusion in PC MRA. CONCLUSION: PC MRA has great advantages in displaying the anatomical structure and lesions of the venous sinuses.

Adolescent↗
PubMed2006

[Application of CTA and CAD\CAM techniques in mandible reconstruction with free fibula flap].

OBJECTIVE: To explore the application of computed tomographic angiography (CTA) and computer aided design\manufacture (CAD\CAM) techniques in mandible reconstruction with free fibula flap. METHODS: 7 cases of complex mandible defect were reconstructed with free fibula flap. Patients' lower extremity vasculature was evaluated by preoperative CTA examination; mandible tumor resection and reconstruction were simulated by CAD technique, the surgical template was manufactured with CAM technique preoperatively; and fibula flap was shaped according to surgical template during mandible reconstruction operation. RESULTS: Preoperative CTA examination performed without complication, the desired anatomy was adequately demonstrated in all patients. All of flaps survived, patients' facial contour are symmetry approximately. CONCLUSIONS: CTA and CAD\CAM techniques have important value for complex mandible reconstruction in selection of donor site, planning of operation and shaping of fibula flap.

Adolescent↗
PubMed2006

[The prognosis and cytogenetic characteristics of acute erythroid leukemia: a report of 55 cases].

OBJECTIVE: To explore the prognosis and cytogenetic characteristics of acute erythroid leukemia. METHODS: We selected 55 patients with acute erythroid leukemia and reviewed the cytogenetic characteristics of these cases. With case-control studies, 55 patients were classified as primary or MDS transformed leukemia depending on the absence or presence of MDS history. In addition, we also classified these 55 cases as normal or abnormal karyotype. We analyzed the treatment response to allogenic hematopoietic stem cell transplantation or chemotherapy and the survival and prognosis of all the groups with Kaplan-Meier and Log-Rank. RESULTS: 45 patients and cytogenetic studies and there were 18 cases with normal karyotypes and 27 cases with aberrant karyotypes. The detection rate of chromosomal abnormality was 60.0%. In the cases with chromosomal abnormality, there were 17 cases with multiple chromosomal abnormality and 10 cases with simple chromosomal abnormality. 10 cases had excess of hypodiploid or hyperdiploid. In 18.5% (5/27) of the cases with aberrant karyotypes 5 chromosomes were involved and in 25.9% (7/27) 7 or 8 chromosomes were involved. The 55 patients were followed up and their treatment response was evaluated. In these patients, total complete remission rate was 63.6%. Among them, the complete remission rate of acute erythroid leukemia with MDS history was lower than that without MDS history (42.8% vs 85.2%, P < 0.05). The complete remission rate of acute erythroid leukemia with aberrant karyotypes was lower than that with normal karyotypes (37.0% vs 83.3%, P < 0.01). The median follow-up was 30 months (3 - 79 months). During follow-up, the overall survival and disease-free survival of the patients with aberrant karyotypes or MDS history who received transplantation were longer than those who received chemotherapy (P < 0.01). Chromosomal abnormality and previous MDS history were the major factors that influenced prognosis. 16 patients received allogeneic haemopoietic stem cell transplantation. Among them, 9 cases had aberrant karyotypes and previous MDS history and 4 cases had no response to chemotherapy. After transplantation, 11 cases survived without any disease. The median survival was 28 months and 2-year survival 68.7% (11/16). CONCLUSIONS: Acute erythroid leukemia patients with aberrant karyotypes or MDS history are usually resistant to chemotherapy. The survival of these patients is short and the prognosis poor. Allogeneic haemopoietic stem cell transplantation could improve survival and prognosis. The patients with aberrant karyotypes or MDS history should receive allogeneic haemopoietic stem cell transplantation as early as possible.

Adult↗
PubMed2006

[Monitoring bcr-abl mRNA levels by real-time quantitative RT-PCR in chronic myeloid leukemia patients after hematopoietic stem cell transplantation].

OBJECTIVE: To evaluate the value of real time quantitative RT-PCR (Q-PCR) for monitoring bcr-abl mRNA levels in chronic myeloid leukemia (CML) patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: Quantification of bcr-abl mRNA was performed on 316 bone marrow samples from 112 patients with CML after HSCT by Q-PCR using the TaqMan probe system. The bcr-abl mRNA level was normalized by control gene abl. Cytogenetic response was evaluated with fluorescent in-situ hybridization (FISH). RESULTS: The reproducible sensitivity of Q-PCR was 5 copies. The coefficients C(T) of interassay and intraassay variation for abl and bcr-abl were all below 2.0%. 289 bone marrow samples were collected from 101 CML patients who achieved a sustained complete cytogenetic response (CCyR) one month post allo-HSCT in a period of 6 - 60 months (median 12 months) at different intervals. In general, the median bcr-abl levels gradually decreased with the prolongation of time after HSCT: the median bcr-abl levels were 0.035% (0 - 0.406%) at 1 month post allo-HSCT (+ 1 month), 0.006% (0 - 0.683%) at +3 month, 0% (0 - 0.225%) at +6 month and remained 0% till +24 months. The highest level in CCyR patients detected at + 6 month was 0.068%. The bcr-abl mRNA level was decreased by 3 log in sustained CCyR patients at + 1 month compared with the newly diagnosed CML-CP patients (33.0%, data unpublished). On the contrary, Q-PCR results ranged from 0.12% to 13.45% in 8 cytogenetic non-responders or relapsed patients post allo-HSCT. Among them, 5 patients' samples were collected 1 - 2 months before cytogenetic relapse, the results were ranged from 0.09% to 3.42%. If 0.09% was assumed 0.09% as a threshold, 9 sustained CCyR patients (8.9%) were tested once higher than that within 6 month after HSCT but decreased to 0% eventually. 2 blast crisis patients achieved CCyR within 1.6 and 3 months after HSCT, but hematological relapse occurred after 1 and 1.5 months, and their bcr-abl mRNA levels increased dramatically from 0% and 0.14% to 46.9% and 75.9% respectively. CONCLUSIONS: Q- PCR is a sensitive, precise and reliable technique, and can be used to monitor CML patients post allo-HSCT regularly. Patients in blast phase of CML should be monitored more frequently.

Adolescent↗
PubMed2005

Analysis of estrogenic compounds in Polygonum cuspidatum by bioassay and high performance liquid chromatography.

The estrogenic activity of traditional Chinese herb-Polygonum cuspidatum Sieb. et Zucc. was investigated by a recombinant yeast screening (YES) assay. Anthraquinones are the main components in the plant, of which emodin is the most abundant one. The ethyl acetate fraction of the ethanol extract of Polygonum cuspidatum was separated on a silica gel TLC plate and seven sub-fractions were collected. The results of bioassay demonstrated that Hzs1 and Hzs6 showed higher estrogenic activities than that of others and the potency of these two compounds were approximately 10(-4) g/L and 10(-3) g/L, respectively. HPLC analysis was performed to determine the activities and the active components. Combining the results of HPLC analysis and estrogenic activity test by YES led to the conclusion that an unknown bioactive compound might exist in the extraction of Polygonum cuspidatum.

Biological Assay↗
PubMed2005

The crystal structure of 5'-deoxy-5'-methylthioadenosine phosphorylase II from Sulfolobus solfataricus, a thermophilic enzyme stabilized by intramolecular disulfide bonds.

The crystal structure of Sulfolobus solfataricus 5'-deoxy-5'-methylthioadenosine phosphorylase II (SsMTAPII) in complex with 5'-deoxy-5'-methylthioadenosine (MTA) and sulfate was determined to 1.45A resolution. The hexameric structure of SsMTAPII is a dimer-of-trimers with one active site per monomer. The oligomeric assembly of the trimer and the monomer topology of SsMTAPII are almost identical with trimeric human 5'-deoxy-5'-methylthioadenosine phosphorylase (hMTAP). SsMTAPII is the first reported hexameric member in the trimeric class of purine nucleoside phosphorylase (PNP) from Archaea. Unlike hMTAP, which is highly specific for MTA, SsMTAPII also accepts adenosine as a substrate. The residues at the active sites of SsMTAPII and hMTAP are almost identical. The broad substrate specificity of SsMTAPII may be due to the flexibility of the C-terminal loop. SsMTAPII is extremely thermoactive and thermostable. The three-dimensional structure of SsMTAPII suggests that the unique dimer-of-trimers quaternary structure, a CXC motif at the C terminus, and two pairs of intrasubunit disulfide bridges may play an important role in its thermal stability.

Binding Sites↗
PubMed2005

Enhanced external counterpulsation improves endothelium-dependent vasorelaxation in the carotid arteries of hypercholesterolemic pigs.

BACKGROUND: Enhanced external counterpulsation (EECP) has been demonstrated to be an effective method for the treatment of atherosclerotic vascular disease. However, the exact mechanism underlying the beneficial effects of EECP is not completely clear. We hypothesized that EECP leads to improvement in endothelial function, contributing to its clinical benefits. METHODS: Fifteen male domestic pigs were initially divided into 2 dietary groups: one consumed a normal feeding (NF) of pig chow (n=5), and one consumed a high-fat (HF) pig chow (n=10). After 8 weeks on the NF or HF diet, 5 HF pigs received EECP treatment (HF+EECP) 1 h daily for 6 weeks and the remaining 5 HF pigs continued to be fed by high cholesterol diet. At the end of 6-week EECP treatment, the carotid arterial rings from all of the pigs were harvested. Endothelium-dependent and -independent vasorelaxation to acetylcholine (ACh) and sodium nitroprusside (SNP) were measured in a dose-dependent manner. RESULTS: The high fat diet resulted in increase in plasma cholesterol and triglyceride levels (p<0.05). Endothelium-dependent vasorelaxation was decreased in the HF group compared to the NF control (p<0.05). However, EECP treatment partially improved impaired endothelium-dependent vasorelaxation in the HF+EECP group compared to the HF control (p<0.05). Endothelium-independent vasorelaxation was not significantly different among the three groups. CONCLUSIONS: Endothelium-dependent vasorelaxation is impaired in the hypercholesterolemic pigs. EECP treatment significantly improves hypercholesterolemia-induced diminished endothelium-dependent vasorelaxation. It suggests that amelioration in endothelial function may at least in part contribute to the beneficial effects of EECP treatment in clinical practice.

Acetylcholine↗
PubMed2005

Heart rate-corrected QT interval duration is significantly associated with blood pressure in Chinese hypertensives.

INTRODUCTION: Many studies demonstrated that a prolonged heart rate-corrected QT interval (QTc) increases the risk of malignant ventricular arrhythmias and sudden death. METHODS: We measured the electrocardiogram and blood pressure of 1480 hypertensive patients and assessed the relationship between the length of QTc and blood pressure. RESULTS: The mean QTc is longer in female than in male participants. There was a positive association between QTc and blood pressure in both men and women. The estimated increase in systolic and diastolic blood pressure for each 100-millisecond increase in QTc was 6.4 and 5.0 mm Hg in men and 3.7 and 2.5 mm Hg in women, respectively. CONCLUSION: Our study demonstrated a significant positive relationship between the QTc interval and baseline blood pressure in a Chinese hypertensive population.

Adult↗
PubMed2005

High-performance liquid chromatography-tandem mass spectrometry for identification of isoflavones and description of the biotransformation of kudzu root.

High-performance liquid chromatography-tandem mass spectrometry has been used to identify isoflavone aglycones and glycosides in kudzu root. Fourteen isoflavones were detected. Among these, six were identified by comparison with authentic standards. Tentative identifications of the other isoflavones are based on UV spectra, mass spectra of protonated and deprotonated molecules, and MS-MS data. Several are reported for the first time in kudzu root. The bioactivity and bioavailability of isoflavone aglycones are usually greater than those of their glycosides. To improve the bioavailability of kudzu root isoflavones, crude beta-glycosidases prepared from microbes were used to hydrolyze the isoflavone glycosides. Several MS modes are combined not only to identify the isoflavones in kudzu root, but also to describe the biotransformation of kudzu root isoflavone glycosides. It is also proved that crude beta-glycosidases have high selectivity toward the O-glycosides of isoflavones.

Biotransformation↗
PubMed2005

Trifluoromethyl group as a pharmacophore: effect of replacing a CF3 group on binding and agonist activity of a glucocorticoid receptor ligand.

Compound 1, a potent glucocorticoid receptor ligand, contains a quaternary carbon bearing trifluoromethyl and hydroxyl groups. This paper describes the effect of replacing the trifluoromethyl group on binding and agonist activity of the GR ligand 1. The results illustrate that replacing the CF3 group with a cyclohexylmethyl or benzyl group maintains the GR binding potency. These substitutions alter the functional behavior of the GR ligands from agonists to antagonists. Docking studies suggest that the benzyl analog 19 binds in a similar fashion as the GR antagonist, RU486. The central benzyl group of 19 and the C-11 dimethylaniline moiety of RU486 overlay. Binding of compound 19 is believed to force helix 12 to adopt an open conformation and this leads to the antagonist properties of the non-CF3 ligands carrying a large group at the center of the molecule.

Cells, Cultured↗
PubMed2005

Constitutive activating mutation of the FGFR3b in oral squamous cell carcinomas.

A G to T mutation at nucleotide position 2128 in the human FGFR3b coding region resulting in a Cys for Gly substitution (G697C) in the tyrosine kinase domain was observed in 62% (44/71) of oral squamous cell carcinomas (OSCC) examined. Immunostained FGFR3b was found in the cytoplasm of prickle cells in normal epithelia, and FGFR3b was localized in the cytoplasm and nucleus in non-FGFR3b mutant OSCC. Overexpressed FGFR3b protein on plasma membranes was noted in OSCC bearing the FGFR3b mutation. Enhanced tyrosine kinase activity of G697CFGFR3b was confirmed. Our results indicate that G697C is an activating mutation causing constitutive ligand-independent FGFR3b signaling. This mutation may be involved in the progression of OSCC and thus the FGFR3b coding sequence may have diagnostic or prognostic value for OSCC.

Carcinoma, Squamous Cell↗
PubMed2005

Cationic albumin-conjugated pegylated nanoparticles as novel drug carrier for brain delivery.

In this paper, a novel drug carrier for brain delivery, cationic bovine serum albumin (CBSA) conjugated with poly(ethyleneglycol)-poly(lactide) (PEG-PLA) nanoparticle (CBSA-NP), was developed and its effects were evaluated. The copolymers of methoxy-PEG-PLA and maleimide-PEG-PLA were synthesized by ring opening polymerization of D,L-lactide initiated by methoxy-PEG and maleimide-PEG, respectively, which were applied to prepare pegylated nanoparticles by means of double emulsion and solvent evaporation procedure. Native bovine serum albumin (BSA) was cationized and thiolated, followed by conjugation through the maleimide function located at the distal end of PEG surrounding the nanoparticle's surface. Transmission electron micrograph (TEM) and dynamic light scattering results showed that CBSA-NP had a round and regular shape with a mean diameter around 100 nm. Surface nitrogen was detected by X-ray photoelectron spectroscopy (XPS), and colloidal gold stained around the nanoparticle's surface was visualized in TEM, which proved that CBSA was covalently conjugated onto its surface. To evaluate the effects of brain delivery, BSA conjugated with pegylated nanoparticles (BSA-NP) was used as the control group and 6-coumarin was incorporated into the nanoparticles as the fluorescent probe. The qualitative and quantitative results of CBSA-NP uptake experiment compared with those of BSA-NP showed that rat brain capillary endothelial cells (BCECs) took in much more CBSA-NP than BSA-NP at 37 degrees C, at different concentrations and time incubations. After a dose of 60 mg/kg CBSA-NP or BSA-NP injection in mice caudal vein, fluorescent microscopy of brain coronal sections showed a higher accumulation of CBSA-NP in the lateral ventricle, third ventricle and periventricular region than that of BSA-NP. There was no difference on BCECs' viability between CBSA-conjugated and -unconjugated pegylated nanoparticles. The significant results in vitro and in vivo showed that CBSA-NP was a promising brain drug delivery carrier with low toxicity.

Albumins↗
PubMed2005

CYP2C9*3 allelic variant is associated with metabolism of irbesartan in Chinese population.

OBJECTIVE: There is considerable variability in the individual pharmaceutical dosages required to achieve optimal therapeutic effects, which may be due to environmental or genetic factors. The objective of this study was to test the presence of the CYP2C9*3 allelic variant in the Chinese population and to investigate the association of this variant with both metabolism and therapeutic efficacy of irbesartan on essential hypertension. METHODS: In this study, we enrolled 711 subjects from Taihu County and 376 subjects from Dongzhi County in Anhui Province, China. All subjects received a single oral dose of 150 mg irbesartan daily for 28 days. The plasma concentration of irbesartan at 24 h after dosing on the 27th day and at 6 h after dosing on the 28th day was detected using fluorescence-high-performance liquid chromatography. CYP2C9 genotypes were determined using polymerase chain reaction-restriction fragment length polymorphism. RESULTS: No CYP2C9*2 allele was found in 235 Chinese samples and was removed from further study. The mean frequency of the CYP2C9*3 allele was 3.65%, while no CYP2C9*3/*3 genotype was detected. Multiple linear regression analyses revealed that the CYP2C9*3 allele carriers had significantly higher irbesartan concentrations in plasma at 6 h (Taihu: P < 0.0001; Dongzhi: P = 0.03) and 24 h (Taihu: P < 0.0001; Dongzhi: P = 0.00013) after dosing. No significant association was found between the CYP2C9*3 allelic variant and the therapeutic effect of irbesartan on essential hypertension. CONCLUSION: Our study suggests that the CYP2C9*3 plays an important role in the metabolism of irbesartan and/or is in linkage disequilibrium with another potential CYP2C9 allele, both of which possibly modify the pharmacokinetics of irbesartan.

Administration, Oral↗
PubMed2005

Unintentional injuries at school in China--patterns and risk factors.

OBJECTIVE: To describe the rate and pattern of unintentional school injuries among primary and middle school students and to explore the major risk factors involved. STUDY DESIGN: A cross-sectional survey of more than 10,000 students attending 6 primary and 4 middle schools selected randomly from all schools in Maanshan City of Anhui Province in eastern China was conducted to collect information on school injuries occurring in the 12-month period before the survey. Rate ratios for risk factors were estimated using the negative binomial regression analysis. RESULTS: The annual person-based school injury rate was 5.22 (95% CI: 3.90-6.53) percent. The annual event-based injury rate was 5.40 (95% CI: 4.04-6.76) per 100 students. Most injuries in school were relatively mild and only 1.53% (9/590) of the episodes resulted in hospitalization. The most frequent injures were falls (73%), and the most commonly injured sites were the upper limbs (46%). Male sex, primary school grades, poor health status, poor ability to concentrate, bad risk-taking behavior and high study-related stress were important risk factors. CONCLUSION: This study provided useful baseline information on school injuries in China and identified important risk factors that would be important in planning prevention strategies.

Accident Prevention↗