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Biomedical subjects

Yu Zhang

Publications and source records attributed to Yu Zhang.

At least 235 records · Page 13Linked to original sources
PubMed2004

Enzymatic reaction of the immobilized enzyme on porous silicon studied by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry.

Desorption/ionization on silicon mass spectrometry (DIOS-MS) is a matrix-free technique that allows for the direct desorption/ionization of low-molecular-weight compounds with little or no fragmentation of analytes. This technique has a relatively high tolerance for contaminants commonly found in biological samples. DIOS-MS has been applied to determine the activity of immobilized enzymes on the porous silicon surface. Enzyme activities were also monitored with the addition of a competitive inhibitor in the substrate solution. It is demonstrated that this method can be applied to the screening of enzyme inhibitors. Furthermore, a method for peptide mapping analysis by in situ digestion of proteins on the porous silicon surface modified by trypsin, combined with matrix-assisted laser desorption/ionization-time of flight-MS has been developed.

Animals↗
PubMed2004

Synthesis and biodistribution of (99m)Tc-carbonyltechnetium-labeled fatty acids.

In order to image myocardial metabolism, (99m)Tc(CO)(3)(+) complexes containing fatty acids were evaluated. At first, 11-(1-imidazolyl)-undecanoic acid (IUA) and 11-(2-(4-bromo-phenylazo)-1-imidazolyl)-undecanoic acid (BPIUA) were synthesized and the corresponding carbonyltechnetium-labeled complexes were prepared. However, unfortunately similar to those of other technetium-labeled fatty acid analogs, the biodistribution studies of (99m)Tc(CO)(3)-IUA and (99m)Tc(CO)(3)-BPIUA in mice demonstrated poor heart-to-blood ratios, thus these complexes cannot be used as heart-imaging reagents. In addition, Tween-80 can improve the biodistribution of the complexes for myocardial imaging.

Animals↗
PubMed2004

Materials design in the performance of all-ceramic crowns.

Results from a systematic study of damage in material structures representing the basic elements of dental crowns are reported. Tests are made on model flat-layer specimens fabricated from various dental ceramic combinations bonded to dentin-like polymer substrates, in bilayer (ceramic/polymer) and trilayer (ceramic/ceramic/polymer) configurations. The specimens are loaded at their top surfaces with spherical indenters, in simulation of occlusal function. The onset of fracture is observed in situ using a video camera system mounted beneath the transparent polymer substrate. Critical loads to induce fracture and deformation at the ceramic top and bottom surfaces are measured as functions of layer thickness and contact duration. Radial cracking at the ceramic undersurface occurs at relatively low loads, especially in thinner layers. Fracture mechanics relations are used to confirm the experimental data trends, and to provide explicit dependencies of critical loads in terms of key variables: material-elastic modulus, hardness, strength and toughness; geometric-layer thicknesses and contact radius. Tougher, harder and (especially) stronger materials show superior damage resistance. Critical loads depend strongly (quadratically) on crown net thickness. The analytic relations provide a sound basis for the materials design of next-generation dental crowns.

Biocompatible Materials↗
PubMed2004

Safety evaluation of a triterpenoid-rich extract from bamboo shavings.

Triterpenoids, which may have significant application to the development of natural medicines and functional foods as biological active components, are widely distributed throughout the plant kingdom. This paper evaluated the safety of a triterpenoid-rich extract of bamboo shavings (EBS) systematically. (i) Acute toxicity test: The oral maximum tolerated dose of EBS was more than 10 g/kg body weight both in rats and in mice, due to the absence of toxicity according to the criteria of acute toxic classifications. (ii) Mutagenicity test: It had no mutagenicity judged by negative experimental results of Ames test, mouse bone marrow cell micronucleus test and mouse sperm abnormality test. (iii) 30 days feeding study: No abnormal symptoms and clinical signs or deaths had been found in rats in each group during the test. No significant difference had been found in body weight, food consumption and food availability of rats in each test group (P>0.05). In addition, no significant differences were found in each hematology value, clinical chemistry value and organ/body weight ratio, either (P>0.05). No abnormality of any organ was found during histopathological examination. It can be concluded that the extract of bamboo shavings is of low toxicity and support the use of EBS for various foods.

Administration, Oral↗
PubMed2004

Regulation of ADF/cofilin phosphorylation and synaptic function by LIM-kinase.

To investigate the role of the LIM-kinase (LIMK) family in the regulation of ADF/cofilin phosphorylation and synaptic function in the mammalian central nervous system (CNS), we conducted biochemical and electrophysiological analysis using mice that were genetically altered in the expression of LIMK-1 and LIMK-2. We showed here that while LIMK-2 knockout mice exhibited minimal abnormalities, the LIMK-1/2 double knockout mice were more severely impaired in both ADF/cofilin phosphorylation and excitatory synaptic function in the CA1 region of the hippocampus. These results indicate a critical role for the LIMK family in the regulation of ADF/cofilin and synaptic function in the brain.

Actin Depolymerizing Factors↗
PubMed2004

Theoretical studies on vibrational spectra of some halides of Group IIB elements.

The vibrational spectra of Group IIB elements halides MX2 and their dimers M2X4 (M=Zn(II), Cd(II) and Hg(II); X=F, Cl, Br and I) have been systematically investigated by ab initio RHF and B3LYP methods with LanL2MB, LanL2DZ and SDD basis sets. The optimized geometries, calculated vibrational frequencies are evaluated via comparison with the experimental data. The vibrational frequencies, calculated by these methods with different basis sets, are compared to each other too. The best results can be obtained by RHF/SDD method, with this method, the deviations for MX2 and Hg2X4 are <7%. Some vibrational frequencies of M2X4 that have not been experimentally reported are also predicted.

Cadmium Compounds↗
PubMed2004

Biodegradation of polycyclic aromatic hydrocarbons by Pichia anomala.

Pichia anomala 2.2540, isolated from soil contaminated by crude oil, degraded naphthalene, dibenzothiophene, phenanthrene and chrysene, both singly and in combination. The yeast degraded 4.5 mg naphthalene l(-1) within 24 h. Phenanthrene was degraded after a lag of 24 h. When a mixture of all four polycyclic aromatic hydrocarbons was treated at either 0.1-1.6 mg l(-1) or 3.1-5.3 mg l(-1), naphthalene was completely degraded first within 24 h, followed by phenanthrene and dibenzothiophene after 48 h. Chrysene, which remained in the mixture even after 96 h, could be degraded along with naphthalene. Chrysene at 0.7 and 1 mg l(-1), in the presence of 4.3 and 65 mg naphthalene l(-1), respectively, was removed within 96 h.

Biodegradation, Environmental↗
PubMed2004

Mechanisms of selection mediated by interleukin-7, the preBCR, and hemokinin-1 during B-cell development.

Many of the stromal-derived signals and factors that regulate B lymphopoiesis have been identified. We review recent evidence from our laboratory that shows that there are at least three phases during B-cell development when cells direct their own maturation, independent of stromal cells. Following the expression of the preB-cell receptor (preBCR), cells acquire the ability to proliferate in low levels of interleukin-7 (IL-7), which acts as a self-selecting mechanism to expand cells that have successfully expressed a preBCR in environments that are non-permissive to preBCR- cells. Second, the preBCR is required for a contact-mediated event between B-cell progenitors. Disruption at this stage prevents the further maturation of progenitors to the lipopolysaccharide (LPS)-responsive stage. Finally, the transition from IL-7 receptor to mature antigen receptor-based signaling is enhanced by a novel member of the tachykinin family, hemokinin-1. This series of maturation, survival, and differentiation signals is generated by B-lineage cells as they progress through developmental checkpoints on the way to becoming functionally mature cells.

Animals↗
PubMed2004

Chaotic vibrations of a vocal fold model with a unilateral polyp.

A nonlinear model was proposed to study chaotic vibrations of vocal folds with a unilateral vocal polyp. The model study found that the vocal polyp affected glottal closure and caused aperiodic vocal fold vibrations. Using nonlinear dynamic methods, aperiodic vibrations of the vocal fold model with a polyp were attributed to low-dimensional chaos. Bifurcation diagrams showed that vocal polyp size, stiffness, and damping had important effects on vocal fold vibrations. An increase in polyp size tended to induce subharmonic patterns and chaos. This study provides a theoretical basis to model aperiodic vibrations of vocal folds with a laryngeal mass.

Humans↗
PubMed2004

Nonlinear dynamic analysis of voices before and after surgical excision of vocal polyps.

Phase space reconstruction, correlation dimension, and second-order entropy, methods from nonlinear dynamics, are used to analyze sustained vowels generated by patients before and after surgical excision of vocal polyps. Two conventional acoustic perturbation parameters, jitter and shimmer, are also employed to analyze voices before and after surgery. Presurgical and postsurgical analyses of jitter, shimmer, correlation dimension, and second-order entropy are statistically compared. Correlation dimension and second-order entropy show a statistically significant decrease after surgery, indicating reduced complexity and higher predictability of postsurgical voice dynamics. There is not a significant postsurgical difference in shimmer, although jitter shows a significant postsurgical decrease. The results suggest that jitter and shimmer should be applied to analyze disordered voices with caution; however, nonlinear dynamic methods may be useful for analyzing abnormal vocal function and quantitatively evaluating the effects of surgical excision of vocal polyps.

Adult↗
PubMed2004

Changes in the T-cell receptor V beta gene repertoire after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: We distinguished graft-versus-host disease (GVHD) from graft-versus-leukemia (GVL) effects and to investigate the distribution of T-cell receptor (TCR) V beta gene repertoire in individuals with leukemia before and after allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: Peripheral blood mononuclear cells (PBMC) were obtained from 10 normal individuals, 8 donors and 11 patients with leukemia before and after transplantation. Polymerase chain reaction (PCR) amplification of complementarity-determining region 3 (CDR3) of 24 TCR V beta genes was used to examine serial samples of PBMC. The PCR products were further analyzed by genescan to evaluate clonality of T cells. RESULTS: The 24 TCR V beta gene repertoire displayed highly diverse and polyclonal spectratypes in all normal individuals and 4 of 8 donors. Another 4 donors expressed part of the 24 TCR V beta subfamily and 1 donor had oligoclonality. The expressions of the 24 TCR V beta subfamilies were skewed and restricted in 11 leukemia patients before and after transplantation. Some absences of 24 TCR V beta subfamily expression were quite similar between the recipients pro-transplantation and related donors. The number of subfamilies expressed increased over time post-transplantation, but the restricted expressions of the subfamily could last 6 - 30 months after transplantation. All patients with GVHD and some without GVHD exhibited T cell clonal expansion. The expansive T cell clone was distributed in V beta 2-3, 16-17, 18-19, 21 and V beta 23 in patients with GVHD and in V beta 7, 9, 16 and 19 in patients without GVHD. One patient with syngeneic-HSCT (syn-HSCT) had V beta 15 and 16 T cell expansion after transplantation. One patient displayed V beta 18 T cell expansion after donor lymphocyte infusion (DLI). CONCLUSIONS: Normal individuals express the entire 24 TCR V beta gene repertoire and have polyclonal distribution. However, the TCR V beta gene repertoire is only partially expressed in some donors. The TCR V beta gene repertoire is restrictedly expressed in a skew fashion in patients with leukemia before and after transplantation. The number of TCR V beta gene subfamilies increases over time post-transplantation. GVHD and GVL effects may induce the proliferation of T cell clones. Clinical GVL response may be distinguished from GVHD alloreactivity through the host MHC antigen.

Graft vs Host Disease↗
PubMed2004

Misoprostol in labour induction of term pregnancy: a meta-analysis.

OBJECTIVE: To evaluate the efficacy and safety of misoprostol in term labour induction. DATA SOURCES: Data from published English and Chinese literatures about misoprostol in term labour induction were identified from Medline and CBMdisk (using the search terms "misoprostol" and "labour induction") before 2001; hand searches of reference lists of original studies and reviews (including meta-analyses) and contact with investigators in this field before 2001. STUDY SELECTION: Studies were included if they had data on misoprostol and labour induction. Altogether 623 articles were found and 124 were admitted, including 19,287 cases. DATA EXTRACTION: Data were collected on efficacy and incidence of side-effects of misoprostol and oxytocin. Data were checked for consistency within the published articles and converted into a standard format for incorporation into a central database. DATA SYNTHESIS: The average successful induction rate, rates of caesarean section; incidence of tachysystole, hypertonus of uterus and precipitous labour, and rates of meconium stained amniotic fluid between the misoprostol and oxytocin groups were significantly different (P < 0.05). There were no significant differences between the two groups concerning the average interval from the administration of misoprostol and oxytocin to the onset of labour, duration of the total stage of labour, incidence rate of foetal distress, neonatal asphyxia (1-minute Apgar score < and= 7), postpartum haemorrhage or amount of blood loss in postpartum. CONCLUSIONS: Misoprostol is a superior agent over oxytocin on the induction of term labour, but its application might increase the risk of precipitous labour, abnormal uterine contractions or meconium stained amniotic fluid. Therefore, the dosages and regimens of the agent need further investigation.

Female↗
PubMed2004

[Hematopoietic stem cell transplantation for patients with chronic myelogenous leukemia].

BACKGROUND & OBJECTIVE: Chronic myelogenous leukemia (CML) is a malignant hematological disease.CML patients are commonly treated with hematopoietic stem cells transplantation (HSCT). This study was designed to evaluate the effect of HSCT on the patients with CML. METHODS: Forty-four patients with CML were treated by HSCT, including 8 cases treated with purging autologous transplantation, 30 cases with related donor allogeneic HSCT (allo-HSCT), and 6 cases with unrelated donor allo-HSCT. The conditioning regimen was TBI (total-body irradiation)+CY (CTX) protocol in 31 patients and modified BuCY (hydroxyurea, busulfan, Ara-C, CTX) protocal in 12 patients, and MACC (Melphalan, Ara-C, CTX and CCNU) protocol in one patient. CsA (cyclosporine) and MTX were used in the patients with related donor allo-HSCT, and CsA and MTX added to mycophenolate mofetil (MMF) and antithymocyte globulin (ATG) were used in the patients with unrelated donor all-HSCT for graft versus host disease (GVHD) prophylaxis. Otherwise, CsA was only used in the patients with accelerated phase(AP) and blast crisis(BC) for GVHD prophylaxis. Kaplan-Meier survival analysis model was used to estimate the overall survival (OS) and the disease-free survival (DSF) at 5 years after transplantation. RESULTS: Eight patients with autologous transplantation, except one case died of transplantation-related-complication, obtained part or complete cytogenetic remission within 3 months after transplantation. One patient, who was BC and obtained complete remission (CR) in hematology before transplantation,obtained complete molecular remission for 81 months after autologous transplantation. All patients obtained CR, except one patient died of hepatic veno-occlusive disease (VOD) and one case did not obtained CR, in 36 patients with allo-HSCT after transplantation. The incidence of infection and VOD during transplantation were 38.6% and 9.1%, respectively. The incidences of hemorrhagic cystitis (HC) and cytomegalovirus (CMV) pneumonia after transplantation were 15.9% and 11.4%, respectively. VOD, HC, and CMV pneumonia did not occur in the patients with autologous transplantation. The incidence of acute GVHD in the patients with related and unrelated donor transplantation were 40.0% and 33.3%, respectively. The incidence of chronic GVHD was 43.4% in the patients with related donor transplantation. The rates of transplant-related mortality (TRM) in the patients with autologous and allogeneic transplantation were 12.5% and 16.7%, respectively. The rates of relapse in patients with autologous and related donor transplantation were 37.5% and 13.3%, respectively. The DFSs at 5 years in patients with autologous and related donor transplantation after transplantation were 18.7% and 53.7%, respectively. The DFS at 5 years in patients with CP (chronic phase) or AP and BC before transplantation were 66.4% and 26.7%, respectively. CONCLUSION: all-HSCT shows higher clinical cure rate to CML patients with CP. CsA+MTX+MMF+ATG protocol is more effective for acute GVHD prophylaxis and can decrease the incidence and severity of acute GVHD in patients with unrelated donor transplantation. Autologous transplantation with bone marrow purged can prolong the survival time and a few patients may be cured with autologous transplantation in CML.

Adolescent↗
PubMed2004

[Effect of heparin on umbilical blood flow in patients with fetal growth retardation].

OBJECTIVE: To investigate the effect of heparin on umbilical blood flow in pregnant women with fetal growth retardation (FGR). METHODS: A total of 103 FGR women were randomized into control group (n=37), standard heparin group (n=35) and low-molecular-weight heparin group (n=31). Low-molecular-weight dextran was given in the control group, and the other two groups received agents for intervention as indicated. The umbilical blood flow, 1-minute Apgar score, body weight and gestational age of the neonates were measured and compared between the 3 groups. RESULTS: As the gestational age increases, the systolic/diastolic (S/D) ratio, pulsatility index (PI) and resistance index (RI) were significantly lowered in the two heparin groups in comparison with those in the control group (P<0.05). One-minute Apgar score and body weight of the neonates were significantly greater in the two heparin groups (P<0.05), and the gestational age was also significantly longer (P<0.05). No statistical differences in the indices measured were noted between the two heparin groups (P>0.05). CONCLUSIONS: Heparin, which is safe for both the mothers and their fetuses, might improve fetal growth and development, increase neonate body weight, prolong the gestational age and raise the one-minute Apgar score.

Birth Weight↗
PubMed2004

Effect of acute alcoholism on hepatic enzymes and oxidation/antioxidation in rats.

BACKGROUND: Around the world more and more people suffer from acute alcoholism. The purpose of this study was to determine hepatic enzymes and oxidation/antioxidation in rats with acute alcoholism. METHODS: Rats were randomly divided into three groups: control, low-dose alcohol, and high-dose alcohol. Each alcohol group (n=12) was intravenously infused with ethanol at a dose of 0.3 or 0.7 g/kg body weight respectively. The control group (n=11) was intravenously infused with normal saline at a dose of 0.5 g/kg body weight. Blood was collected for detection of hepatic enzymes and index of oxidation/antioxidation. RESULTS: The ratio of AST to ALT was 2.44+/-0.46, 2.57+/-0.60 and 3.03+/-0.46 in the three groups, and the difference was significant between the control and high-dose alcohol groups (P</=0.05). No significant changes were observed in the levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein (Tp), albumin (Alb), alkaline phosphatase (ALP), cholinesterase (ChE), total bilirubin (TB), C-reactive protein (CRP) and amylase. The levels of serum nitric oxide (NO) in the 3 groups were 39.2+/-73.25 mol/L, 42.30+/-4.60 mol/L and 47.86+/-4.66 mol/L, and significant difference was seen between the control group and the high-dose alcohol group (P<0.01). No significant difference was found in the levels of serum superoxide dismutase (SOD), glutathione (GSH), malondiethylaldehyde (MDA), and CRP in the 3 groups. CONCLUSION: The ratio of AST to ALT appears to be a useful index for acute alcohol intoxication. NO is involved in the mechanism of acute alcohol intoxication.

Alcoholic Intoxication↗
PubMed2004

[Therapeutic effects of chemotherapeutic regimen with pirarubicin for adult high-risk acute leukemia].

OBJECTIVE: To evaluate the therapeutic effects of chemotherapeutic regimen with pirarubicin in the management of adult high-risk acute leukemia. METHODS: Twenty-nine high-risk acute leukemia patients were selected as the treatment group and another 29 patients with similar pretreatment conditions as the control group. In the treatment group, 18 patients had acute non-lymphocytic leukemia (ANLL), and 8 had acute lymphocytic leukemia (ALL) and 3 had mixed leukemia, all received treatment regimens with pirarubicin+cytarabine, vincristine+pirarubicin+prednisone, Vincristine+pirarubicin+L-asparaginase (L)+prednisone or pirarubicin+cytarabine+vincristine+prednisone. Routine therapeutic regimens were adopted in the management of the control. RESULTS: In ANLL patients, the overall remission rate was significantly higher in the treatment group than in the control group (77.78% vs 44.44%, P=0.031). Patients in the treatment group had greater marrow suppression and higher incidence of infections than the control group (P=0.012). CONCLUSION: Regimens with pirarubicin is more effective than the routine regimens in the management of patients with high-risk ANLL and produce greater but tolerable marrow suppression.

Adolescent↗