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Yue Ma

Publications and source records attributed to Yue Ma.

29 records · Page 2Linked to original sources
PubMed2003

Human embryonic stem cells develop into multiple types of cardiac myocytes: action potential characterization.

Human embryonic stem (hES) cells can differentiate in vitro, forming embryoid bodies (EBs) composed of derivatives of all three embryonic germ layers. Spontaneously contracting outgrowths from these EBs contain cardiomyocytes (CMs); however, the types of human CMs and their functional properties are unknown. This study characterizes the contractions and action potentials (APs) from beating EB outgrowths cultured for 40 to 95 days. Spontaneous and electrical field-stimulated contractions were measured with video edge-detection microscopy. beta-Adrenergic stimulation with 1.0 micromol/L isoproterenol resulted in a significant increase in contraction magnitude. Intracellular electrical recordings using sharp KCl microelectrodes in beating EB outgrowths revealed three distinct classes of APs: nodal-like, embryonic atrial-like, and embryonic ventricular-like. The APs were described as embryonic based on the relatively depolarized resting membrane potential and slow AP upstroke. Repeated impalements of an individual beating outgrowth revealed a reproducible AP morphology recorded from different cells, suggesting that each outgrowth is composed of a predominant cell type. Complex functional properties typical of cardiac muscle were observed in the hES cell-derived CMs including rate adaptation of AP duration and provoked early and delayed afterdepolarizations. Repolarization of the AP showed a significant role for IKr based on E-4031 induced prolongation of AP duration as anticipated for human CMs. In conclusion, hES cells can differentiate into multiple types of CMs displaying functional properties characteristic of embryonic human cardiac muscle. Thus, hES provide a renewable source of distinct types of human cardiac myocytes for basic research, pharmacological testing, and potentially therapeutic applications.

Action Potentials↗
PubMed2003

[Antimicrobial resistance of Staphylococcus aureus isolates from inpatients of departments of internal medicine, surgery, and pediatrics and intensive care unit].

OBJECTIVE: To investigate the antimicrobial resistance of Staphylococcus aureus isolates obtained from inpatients of departments of internal medicine, surgery, and pediatrics and intensive care unit (ICU), and study on the differences of resistant rates among the clinical isolates. METHODS: The strains of Staphylococcus aureus were cultured and their antimicrobial resistance was assayed by disc diffusion test (K-B method) and the data was analyzed by WHO NET 5 software. chi(2) test was made to identify the significance of difference. RESULTS: 2 625 strains of Staphylococcus aureus were obtained from the clinical departments of 60 hospitals all over China, among which 1 669 strains (63.3%) were obtained from the inpatients of departments of internal medicine, surgery, and pediatrics and ICU from 1 January to 31 December 2001. Most of the strains were isolated from sputum (34.3%, 572/1 669), secretion (13.2%, 221/1 669), pus (11.7%, 195/1 669), blood (10.2%, 171/1 669), and wound (5.6%, 94/1 669). The resistant rates of Staphylococcus aureus isolates from the inpatients in department pediatrics of to oxacillin, gentamicin, clindamycin, ciprofloxacin, levofloxacin, and chloramphenicol were 23.3%, 16.1%, 29.3%, 11.2%, 4.0% and 14.4% respectively, all significantly lower than those of the isolates from the inpatients of the departments of internal medicine and surgery, and ICU (all P < 0.001). The resistant rates of Staphylococcus aureus isolates from the inpatients of departments of internal medicine and surgery to oxacillin, gentamicin, clindamycin, ciprofloxacin, and levofloxacin were significantly lower than those of isolates from the patients of ICU (all P < 0.001). CONCLUSION: A high isolation rate of multi-drug resistant Staphylococcus aureus among the inpatients of departments of internal medicine, surgery, and pediatrics and ICU. It is important to select appropriate antimicrobial agents based on the origin of bacterial strains and avoid blindness before the results of drug sensitivity are obtained.

Anti-Bacterial Agents↗
PubMed2003

High-level sustained transgene expression in human embryonic stem cells using lentiviral vectors.

Here we describe the sustained expression of transgenes introduced into human embryonic stem (ES) cells using self-inactivating lentiviral vectors. At low multiplicity of infection, vesicular stomatitis virus-pseudotyped vectors containing a green fluorescent protein (GFP) transgene under the control of a human elongation factor 1alpha promoter transduced human ES cells at high efficiency. The majority of the transduced ES cells, which harbored low numbers of integrated vectors, continued to express GFP after 60 days of culture. Incorporation of a scaffold attachment region (SAR) from the human interferon-beta gene into the lentiviral vector backbone increased the average level of GFP expression, and inclusion of the SAR together with a chromatin insulator from the 5' end of the chicken beta-globin locus reduced the variability in GFP expression. When the transduced ES cells were induced to differentiate into CD34(+) hematopoietic precursors in vitro, GFP expression was maintained with minimal silencing. The ability to efficiently introduce active transgenes into human ES cells will facilitate gain-of-function studies of early developmental processes in the human system. These results also have important implications for the possible future use of gene-modified human ES cells in transplantation and tissue regeneration applications.

Animals↗
PubMed2003

[A case control study on the risk factors of male infertility].

OBJECTIVE: To study the risk factors of male infertility. METHOD: Case control study including 94 cases and control group with a ratio of 1 to 1. RESULTS: The risk factors of male infertility were long time heavy smoking habit (OR = 3.45, 95% CI: 1.95 - 6.10), illegal sexual intercourse (OR = 7.29, 95% CI: 2.54 - 20.89), growing vegetable under plastic in higher temperature (OR = 6.73, 95% CI: 1.91 - 23.69), contact with benzene chemicals (OR = 20.53, 95% CI: 4.67 - 90.25) and having Ureaplasma urealyticum (Uu) infection (OR = 5.55, 95% CI: 2.28 - 13.53). CONCLUSION: Male infertility was resulted from many factors repeatedly acting on men for long time. In order to prevent male infertility, issues as environmental pollution, occupational protection need to be improved while bad working condition and risky behavior should be changed.

Adult↗
PubMed2003

DNA sequencing of a plasmid with virulence from marine fish pathogen Vibrio anguillarum.

DNA sequence of a plasmid pEIB1 associated with virulence from the marine fish pathogen Vibrio anguillarum was determined using the methods of restriction endonuclease digestion, subcloning, and primer walking. The whole length of obtained pEIB1 DNA sequence was 66 164 bp, and the overall G+C content of DNA sequence is 42.7%. This sequence encodes 44 open reading frames containing the genes of DNA replication, biosynthesis and regulation of the siderophore anguibactin and transport of ferric-anguibactin complexes.

Animals↗
PubMed2003

[Experimental study on using mGTR and venous autografts to repair facial nerve defects in rabbits].

OBJECTIVE: To observe and compare the effects of using mGTR and venous autografts to repair the defect of facial nerve in rabbits. METHODS: mGTR and venous autografts were performed on three groups of rabbits. Then physical and histological examinations were carried out to get the results of these two repair methods. RESULTS: Both the two methods can induce regeneration of facial nerve. The mGTR is more effective and faster in repairing the nerve defect. Three months after operation, the distance of NCV between bilateral facial nerve in mGTR group was (2.10 +/- 1.2) m/s, (6.80 +/- 1.4) m/s in venous autografts, (2.16 +/- 1.6) m/s in nerve transplantation group. Histologically, the facial nerve fibers were arranged regularly and in continuity in mGTR, the facial nerve fibers were arranged irregularly with marked hyperplasia of connective tissues in venous autografts three months after repair. CONCLUSIONS: The mGTR is more effective than venous autografts in repair of facial nerve.

Animals↗
PubMed2002

Porous polymer/bioactive glass composites for soft-to-hard tissue interfaces.

Porous composites consisting of a polysulfone (or cellulose acetate) matrix and bioactive glass particles were prepared by phase separation techniques. Microstructures were designed for potential application as an interconnect between artificial cartilage and bone. The effects of polymer type, concentration and molecular weight, as well as bioactive glass size and content, on the microstructures of the composites were studied. The composites have asymmetric structures with dense top layers and porous structures beneath. The microstructural features depend most strongly on the type of polymer, the interaction between the polymer and bioactive glass, and the glass content. The dense top layer could be removed by abrasion to make a structure with large pores (20-150 microm) exposed. Composites were immersed in simulated body fluid at body temperature. The growth of hydroxycarbonate apatite inside and on the composites demonstrates their potential for integration with bone. Composite modulus and break strength increased with increasing glass content due to the change in composition and pore content.

Adsorption↗
PubMed2002

[The change in sensitivity of methicillin-resistant Staphylococcus aureus to vancomycin].

OBJECTIVE: To determine the shift of susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) isolates to vancomycin in recent years. METHODS: Antimicrobial susceptibility was determined by disk diffusion test (K-B method). The t-test was used to compare the mean diameters of zone of inhibition. RESULTS: The clinical isolates of MRSA from 1994 to 2000 were 218, 187, 292, 237, 351, 886 and 652 in number respectively. The mean diameters (mm) of the inhibition zone of MRSA isolates each year were 19.9, 19.1, 18.6, 17.4, 18.4, 18.2 and 17.8. Comparison of the diameters of the inhibition zone of MRSA isolates (K-B method) showed that the mean diameter of the inhibition zone from the 652 MRSA isolates in 2000 was much less than that of the 218 MRSA isolates in 1994 and the difference was significant (P < 0.001). The resistant rates to chloramphenicol, ciprofloxacin, erythromycin, gentamicin, tetracycline and trimethoprim/sulfamethoxazole were 44.0%, 73.7%, 89.1%, 65.7%, 61.0% and 67.0%. CONCLUSION: Our observation demonstrated that the susceptibility of MRSA to vancomycin gradually decreased from 1994 to 2000. It is important to monitor the antimicrobial susceptibility of Staphylococcus aureus to vancomycin.

Anti-Bacterial Agents↗
PubMedDate not supplied

Capillary electrophoresis separation of autocondensation glycation products of glucosamine.

Glucosamine nonenzymatically forms autocondensation glycation products under physiological conditions. Many studies have reported the effectiveness of oral doses of glucosamine alone or in combination with the galactosamine containing chondroitin in treating osteoarthritis. However, none of these studies has considered whether it is the glucosamine itself and/or one or more of its autocondensation products that exert this effect. A capillary electrophoresis method was developed to monitor the nonenzymatic formation of autocondensation glycation products of glucosamine, galactosamine, and mannosamine under physiological conditions. Major components were detected and separated by CE with a UV detector. The effects of concentration and incubation time on product species were determined. The method described is simple, rapid, and effective.

Electrophoresis, Capillary↗