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Biomedical subjects

J Yao

Publications and source records attributed to J Yao.

At least 145 records · Page 8Linked to original sources

A randomized double-blind placebo-controlled study of lamivudine in the treatment of patients with chronic hepatitis B virus infection.

OBJECTIVE: To evaluate the effect of lamivudine on the loss of serum hepatitis B virus (HBV) DNA, HBeAg/antiHBe seroconversion and ALT levels in chronic hepatitis B patients and its safety profile and tolerance compared with placebo. METHODS: Four hundred and twenty-nine patients with chronic HBV infection as defined by positive HBsAg, HBeAg and HBV DNA were enrolled and randomized into lamivudine and placebo groups. Three hundred and twenty-two patients received lamivudine 100 mg daily and 107 patients received placebo treatment for 12 weeks. Then, all patients were offered a further 9-month open label lamivudine treatment. The efficacy and safety were evaluated with clinical, biochemical, hematological and virological parameters. RESULTS: During the 12-week treatment period, 92.2% of lamivudine treated patients became HBV DNA negative (below 1.6 pg/ml) compared with only 14.1% of those receiving placebo (P < 0.01). At the end of 12 week, the sustained negative rate for HBV DNA in the lamivudine treated group was 78.5% compared with the placebo group (11.1%; P < 0.01). There was a trend to a high proportion of patients treated with lamivudine to lose HBeAg (8.1%) and develop antiHBe (10.2%) than treated with placebo (5.3% and 6.4% respectively), but this difference was not statistically significant. Patients with elevated ALT levels at baseline became normal in 60. 3% of the lamivudine treated group compared with the placebo group where only 27.5% were normal (P < 0.01). Lamivudine was well tolerated in a dose of (100 mg daily) and the overall incidence of adverse events was similar to that of the placebo. CONCLUSIONS: Lamivudine (100 mg daily) is very effective in the inhibition of HBV replication, indicated by the rapid loss of serum HBV DNA, and often accompanied by a decrease of serum ALT levels. Lamivudine is well tolerated without severe adverse events during treatment.

Adolescent↗

Effect of cytokines on in vitro bone resorption by cells isolated from giant cell tumor of bone.

OBJECTIVE: To investigate the effect of cytokines on in vitro bone resorption by cells isolated from giant cell tumor of bone. METHODS: Mononuclear stromal cells and multinucleated giant cells (MGC) were isolated from 11 cases of giant cell tumor of bone (GCT) and their bone resorption capability in an in vitro cell-bone resorption model were tested. Expressions of some cytokines were detected by immunohistochemistry, Western blotting analysis and Enzyme-linked immunoabsorbent assay (ELISA) in the GCT. RESULTS: The results showed that MGCs of GCT had capability to resorb bone matrix directly. Fibroblast-like stromal cells (FC) could not only resorb bone matrix directly, but also secret unknown factors to facilitate bone resorption of MGC. Exogenous TNF-alpha could significantly increase the bone resorption by both kinds of stromal cells, while exogenous IL-1 did not. Expression rate of M-CSF and level of TNF-alpha in GCT were higher than in osteosarcoma and normal serum. CONCLUSIONS: The characteristic bone resorption behavior of GCT might be caused by its three major cell components. The M-CSF and TNF-alpha could promote their bone resorption capability.

Animals↗

[Inhibitory effect of phosphorothioae oligodeoxynucleotides on HBV replication and synthesis of antigen in vitro].

OBJECTIVE: To evaluate the effect of triplex forming oligodeoxynucleotides (TFO) and antisense oligodeoxynucleotides (ODNas) on the replication of HBV. METHODS: A 21mer phosphorothioate TFO (TFO21) directed at 1734nt-1754nt sites in HBV core promoter and a 21 mer phosphorothioate ODNas (ODNas21) complementory to the initiation sites of pre C RNA and pregenomic RNA were synthesized. Effect of TFO21 and ODNas21 on HBV replication and synthesis of antigen were observed in 22.1.5 cells. RESULTS: Both TFO21 and ODNas21 showed the inhibition to HBV replication and synthesis of antigen while, ODNcon (control of 21 mer phosphorothioate oligodeoxynucleotides) showed little inhibitory effects. At concentration of 10 mumol/L, TFO21 and ODNas21 inhibited the synthesis of HBsAg and HBeAg by 57.5% and 77%; 61% and 79.6%, respectively. The mixture of TFO21 and ODNas21 was more effective than TFO21 or ODNas21 alone. The inhibitions were dose-dependent. No toxicity was observed in the 22.1.5 cells treated with those oligodeoxynucleotides. CONCLUSION: Triplex forming oligodeoxynucleotides and antisense oligodeoxynucleotides were both potent inhibitor, for HBV replication and synthesis of antigen.

Antiviral Agents↗

[Comparative experimental study between longitudinal fracture and transverse fracture of mandibular condyle].

OBJECTIVE: To evaluate the secondary effect of childhood miniature pig longitudinal fracture and transverse fracture of mandibular condyle to Temporomandibular Joint (TMJ). METHODS: Longitudinal and transverse fractures on condyle of 14 childhood miniature pigs were created respectively. After 3 and 6 months the TMJs were studied macroscopically and microscopically. RESULTS: The transverse fracture of mandibular condyle brought about TMJ adaptive changes. There was no adhesion between disc and condyle. The longitudinal fracture led usually to bifid condyle deformity and adhesion between disc and condyle. Many fibroblasts and chondrocytes were seen in the adhesion between disc and condyle. Blood vessels and fatty degeneration appeared in the articular disc. CONCLUSION: Two different types of childhood condylar fractures are apparently different in the aspects of secondary lesions on TMJ. It suggests that an evident correlation between mandibular condyle longitudinal fracture and TMJ ankylosis.

Animals↗

[Dynamic changes of neurotrophic factors in different cerebral areas after full cerebral ischemia and reperfusion in old rats].

OBJECTIVE: To explore the relationship between vascular dementia and nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). METHODS: 42 male and female senile Wistar rats were randomized into control and experimental groups. The control group was subdivided into A, and C three groups and the experimental group into 6 subgroups, i.e 15 min of ischemia alone and ischemia combined with reperfusion of 1 h, 6 h, 2 d, 4 d and 9 d. Swimming maze was performed before and after operation. The contents of NGF and BDNF in different parts of brain were examined in different periods of ischemia and reperfusion with ABC method of immunocytochemistry. RESULTS: NGF expression in frontal lobes reached a peak level in 2 days after reperfusion and then disappeared quickly, that in parietal lobes showed a moderate level in 15 minutes of ischemia and reached a peak in 9 days of reperfusion. However, there is no expression in thalamus in early ischemia and reperfusion, but reexpression occurred after 2 days of reperfusion. BDNF expression showed a peak level after 2 days of reperfusion and then decreased in frontal lobes, but a high level of expression that was unchanged in parietal lobes and hippocampal areas. The increasing expression in thalamus occurred only 9 days after reperfusion. CONCLUSION: The distribution of BDNF was wider than that of NGF. There was a good protective action of NGF and BDNF in frontal lobes in the early period of ischemia with reperfusion and there existed persistent and prompt action of the neurotrophic factors in parietal lobes and hippocampal areas. The protective action of NGF in thalamus was poor, but that of BDNF was good.

Animals↗

[Pathogenic gene analysis of Listeria isolated from foods].

In 1996-1997, Listeria in foods from 12 provinces of China were detected by using the national standard examination method GB 4789.30-94 (routine traditional methods). Twenty four strains Listeria monocytogenes and 141 strains Listeria were identified by biochemical procedures and animal toxicity experiment. Polymerase Chain Reaction(PCR) was used to amplify two specific DNA fragments(719 bp and 446 bp) of listeriolysin O and internalin genes with two pairs of primer--Hly1-2 and Inl1-2, respectively. The experiment results showed that 57 strains contained only internalin, 27 strains contained both internalin and listeriolysin O from the pathogenic genes of isolated strains.

Animals↗

[Gas chromatographic method for the analysis of polychlorinated biphenyls in pine needles].

Polychlorinated biphenyls (PCBs) are a class of 209 chemical compounds, in which 1-10 chlorine atoms are attached to a biphenyl molecule. PCBs are members of halogenated aromatic group of environmental pollutants that have been identified worldwide in diverse environmental matrices. PCBs in air, soils, sediment, water, transformer oils and other environmental matrices have been determined in the past years. In this work a method for routine analysis of PCBs in pine needles has been developed. First, extractions were carried out in Soxhlet apparatus with n-hexane as solvent. Then, a silica gel chromatographic column was applied to pretreat the pine needle samples. The reference standard used was clophen 50. The recovery was about 90%, so the feasibility and reliability were assured. After the analysis of PCBs in pine needle samples from four different regions, the distribution of PCBs in environment can be discussed and monitored. In this method, a Shimadzu GC-7A gas chromatograph equipped with a 63Ni electron capture detector was used for the analysis of PCBs. From the results, we can see the PCB pollution in different regions. So evaluation of air pollution level through foliage data is feasible. The sample preparation and analytical method mentioned in this paper is reliable and simple.

Chromatography, Gas↗

[Determination of conversion of asymmetric hydrosilylation of acetophenone by gas chromatography].

A gas chromatographic method to determine the conversion of asymmetric hydrosilylation of acetophenone has been established. The gas chromatographic conditions were as follows: column, 10% PEG20M on white 102 support (DMCS), 1 m x 2 mm i.d. stainless-steel column; column temp., 160 degrees C; injector temp., 200 degrees C; thermal conductivity detector temp., 190 degrees C; carrier gas H2 with flow rate of 50 mL/min. The results show that the method is simple and rapid, and has good reproducibility. The coefficient of variation of the method was less than 1% (n = 6). The results were also confirmed with 1HNMR.

Acetone↗

[The effect of N+ implantation on SOD activity of Deinococcus radiodurans and induction of Mn-SOD].

The induction of Mn-SOD and effect of N+ of 20 keV implantation on SOD activity of D. radiodurans were investigated. The results were as follows: (1) SOD activity of D. radiodurans had a little change when implantation dose was less than 8 x 10(14) N+/cm2, and increased gradually from 8 x 10(14) to 60 x 10(14) N+/cm2, and then decreased rapidly; (2) the test of adding H2O2 and CHCl3-CH3CH2OH which could inhibit different types of SOD showed that most SOD activity of D. radiodurans was constituted by Fe-SOD in general physiology and less then 8 x 10(14)N+/cm2 dose, and higher implantation dose induced increase of Mn-SOD activity.

Deinococcus↗

[Cloning the representative strains of China HIV-1 subtypes B, C and E for heteroduplex mobility analysis (HMA)].

OBJECTIVE: To clone the HIV-1 env gene and establish the HMA reagents suitable for use with the Chinese HIV strains. METHODS: Using Nest-PCR technique, we amplified env gene from representative strains which contain the most proximate consensus of China HIV-1 subtypes B, C and E. The genes were then cloned into pGEM-Teasy vector for HMA subtyping. RESULT: The env gene of representative strains of China HIV-1 subtypes B, C and E were amplified and cloned into plasmids. The plasmids were used in HMA and compared with those standard env gene of other countries. The heteroduplex bands obtained with ours env genes were more proximate to homoduplex bands. The homogeneity of the corresponding China HIV-1 subtypes with standard TH14(B), IND868(C), MA959 (C) and TH22(E) are 90.2%(B), 88.3%(C), 83.7(C)% and 92.3%(E) respectively. CONCLUSION: The HMA reagents we established in this study have higher sensitivity in HMA analysis for China HIV-1 strains when compared with the international HMA reagents. The HMA reagents also provide new reference reagents for UNAIDS HIV isolation network.

Acquired Immunodeficiency Syndrome↗

[Relationship between HBV DNA serum level and acute exacerbation of the disease in chronic hepatitis B patients].

OBJECTIVE: In this study, we evaluated the relationship between HBV DNA serum level and acute hepatic exacerbation of the disease in chronic hepatitis B patients. METHODS: A series of serum samples from 14 patients of acute exacerbation of chronic hepatitis B were analyzed for alteratieus in serum HBV DNA and alanine transaminase (ALT) level before, during, and after episode of an acute exacerbation. The serum HBV DNA concentrations were tested by the quantitative polymerase chain reaction (PCR) using the AmpliSensor assay. RESULTS: 1. Serum HBV DNA average level in 11 patients significantly increased from 7.148 +/- 2.008(logarithm) at 2-8 weeks before maximum injury of liver to 8.416 +/- 2.160 (logarithm), the time that ALT reached its peak, and then, following the declining of ALT level, decreased to 6.093 +/- 1.428 (logarithm). In 9 of 11 cases, the HBV DNA peak value occurred before the ALT peak level or at the same time; 2. Two patients who experienced several episodes of acute exacerbation showed that the appearance of acute hepatic injury and the relatively normal liver function occurred alternatively. Whereas, one patient with liver cirrhosis showed persistence of high level viremia in three episodes of acute exacerbation in one year. CONCLUSION: 1. This investigation revealed a clear correlation between increasing level of serum HBV DNA and acute exacerbation of patients with chronic hepatitis B. The findings suggest that host's immune response which causes acute exacerbation of liver injury in patients with chronic hepatitis B is triggered by the change of viremia and HBV replication; 2. Patients with severe chronic active hepatitis and persistent hepatitis B virus replication are at very high risk of rapid progression to cirrhosis.

Adult↗

[Progress of surface enhanced Raman spectroscopic studies in nonaqueous systems].

In this report, we describe the applications and theoretical aspects of SERS phenomenon in nonaqueous systems, which mainly involves the structure of solid/nonaqueous system, the adsorption of some neutral and organic molecules, inorganic ions and other complex compound molecules, the process and mechanism of some electrochemical oxidation reduction reactions in organic solvents etc.. In this review, we also depict the similarities and differences in SER spectra of aqueous and non-aqueous systems.

English Abstract↗

[Analysis of the spectrum of solid sodium carboxyl in N+ ion implantation].

The changes in molecular structure of PhCOONa and CH3COONa samples in 25 keV N+ ions implantation were measured by UV-spectrum. The dose response of UV-absorption was deduced. It was found that a new compound with UV-absorption could be produced in implanted CH3COONa sample. The cyano-group could be produced in PhCOONa and CH3COONa samples implanted by the N+ ion beam.samples implanted by the N+ ion beam.

English Abstract↗

Clinical application of transthoracic volume-rendered three-dimensional echocardiography in the assessment of mitral regurgitation.

Two-dimensional echocardiography (2-DE) and Doppler methods are generally used for assessing mechanisms and severity of mitral regurgitation (MR). Recently, 3-dimensional echocardiography (3-DE) has been applied successfully in various cardiac disorders, but its value in evaluating the mechanism and the severity of MR are not known. We studied 30 patients with MR using 2-DE and 3-DE. Volume-rendered gray-scale 3-DE images of the mitral valve apparatus and MR jets were reconstructed. Maximal volume of the MR jet by 3-DE was compared with mitral regurgitant volume and fraction, regurgitant jet area and the ratio of jet area to left atrial area, and semiquantitative grading derived from 2-DE methods. Our results demonstrated that 3-DE aided in a better depiction of the mitral apparatus and its abnormalities in 70% of the patients. The origin, direction, and morphology of the MR jet were better delineated in 3-DE volumetric display. Quantitative analysis, however, showed only a weak to moderate correlation between 3-DE maximal MR jet volume and 2-DE mitral regurgitant volume (y = 0.5x + 11.4, r = 0.7), regurgitant fraction (y = 0.5x + 8.2, r = 0.65), mitral regurgitant jet area (y = 0.2x + 5, r = 0.51), jet area to left atrial area ratio (y = 0.53x + 7.6, r = 0.54), and semiquantitative grading of MR (y = 9.1x - 1.8, r = 0.74). In conclusion, 3-DE aids in a better understanding of the mechanisms of MR and morphology of the regurgitant jets. Its quantitative ability, when reconstruction of the jet alone is used, may be limited.

Adult↗

Measurements and day-to-day variabilities of left ventricular volumes and ejection fraction by three-dimensional echocardiography and comparison with magnetic resonance imaging.

The aim of this study was to assess day-to-day variability of left ventricular (LV) volume and ejection fraction (EF) calculated from 3-dimensional echocardiography (3-DE) and to compare the reproducibility of the measurement with magnetic resonance imaging. Forty-six subjects were examined including 15 normal volunteers (group A) and 31 patients with LV dysfunction (group B). Precordial 3-DE acquisition was performed at 2 degrees rotational intervals and repeated 1 week later. Magnetic resonance imaging was performed at 0.5 T. End-diastolic and end-systolic LV volumes were derived using Simpson's rule by manual endocardial tracing of 8 equidistant parallel LV short-axis slices with 3-DE, whereas 9-mm slices were used with magnetic resonance imaging. The mean +/- SD of end-diastolic and end-systolic LV volumes (ml) and EF (%) from magnetic resonance imaging were 182 +/- 75, 121 +/- 76, and 39 +/- 18, whereas those from 3-DE were 182 +/- 76, 121 +/- 77, and 39 +/- 18 respectively. Day-to-day measurements of end-diastolic and end-systolic LV volumes, and EF on 3-DE were not significantly different as assessed with SEE (2.7, 1.1, and 2.4, respectively). Intra- and interobserver SEE for calculating end-diastolic and end-systolic LV volumes and EF for magnetic resonance imaging were 6.3, 4.7, and 2.1 and 13.6, 11.5, and 4.7, respectively, whereas those for 3-DE were 3.1, 4.4, and 2.2 and 6.2, 3.8, and 3.6, respectively. Day-to-day variability of LV volume and EF calculation on 3-DE were small and not significantly different for normal and dysfunctional left ventricles. Observer variabilities of 3-DE were fewer than those of magnetic resonance imaging. Therefore, 3-DE is recommended for serial assessment of LV volume and EF in normal and abnormally shaped ventricles.

Adult↗

Sequence requirements for stabilization of a peptide reverse turn in water solution--proline is not essential for stability.

To probe the sequence requirements for stabilization of a reverse turn conformation in a short peptide in water solution, the behavior of two series of peptides was investigated by nuclear magnetic resonance (NMR) spectroscopy. The peptides have the general sequences XPGDV and AXGDV, where X is a representative subset of all 20 naturally occurring amino acids. The residues chosen at positions 3 and 4, Gly and Asp, respectively, were shown to give the greatest population of reverse turns in a previous study [Dyson, H. J., Rance, M., Houghten, R. A., Lerner, R. A. & Wright, P. E. (1988) J. Mol. Biol. 201, 161-200]. Within this framework, the identity of the first residue of the turn (X in XPGDV) does not greatly influence the turn population, although a small but significant increase is observed for residues such as Ala which have a preference for backbone conformations in the alpha region of (phi,psi) space. The series AXGDV was initially studied for completeness only, since it was expected that the turn would not be stabilized in such a small linear peptide in the absence of proline. In contrast, it appears that a significant population of type II turn conformations is to be found in peptides in the series AXGDV, although proline remains one of the most favorable residues at position 2. These results indicate that while residues at all positions within the turn can influence the turn population, the presence of Gly-Asp as the third and fourth members of the sequence gives a strong bias towards type II turn formation regardless of the residues at positions 1 and 2. Our results give a final prediction that the sequence with the highest intrinsic propensity for turn formation is APGD.

Amino Acid Sequence↗

Proteolytic processing of rubella virus nonstructural proteins.

The genomic RNA of rubella virus contains two long open reading frames (ORF), a 5'-proximal ORF that codes for the nonstructural proteins and a 3'-proximal ORF that encodes the structural proteins. The cDNA encoding the nonstructural protein ORF of the wild-type M33 strain of rubella virus has been obtained and sequenced. Comparison between the nonstructural proteins of the M33 and Therien strains of rubella virus revealed a 98% homology in nucleotide sequence and 98.1% in deduced amino acid sequence. To examine the processing of rubella virus nonstructural protein, the complete nonstructural protein ORF was expressed in BHK cells using a pSFV expression vector. Three nonstructural protein products (p200, p150, and p90) with molecular weights of 200, 150, and 90 kDa were identified using antisera raised against synthetic peptides corresponding to regions of the nonstructural proteins. p200 is the polyprotein precursor, while p150 and p90 are the cleavage products. Site-directed mutagenesis of the Cys-1151 residue (one of the catalytic dyad residues of the viral protease) and of the Gly-1300 residue (the viral protease cleavage site) abrogated protease activity and p200 precursor cleavage, respectively. Coexpression of mutant constructs in BHK cells indicated that rubella virus protease can function both in cis and in trans.

Animals↗

Three-dimensional echocardiography: clinical relevance and application.

Three-dimensional (3D) echocardiography has recently become a practical reality. It is now practicable to perform 3D echocardiography using transthoracic and transesophageal acoustic windows both in adults and children. The unique image projections that 3D echocardiography yields appear to have enormous potential for displaying intracardiac anatomy in exquisite detail. An important aspect of 3D echocardiography is its ability to supply accurate quantitative data without the use of geometric assumptions. In particular, coupled to contrast ultrasound agents, 3D echocardiography could be valuable in the assessment of myocardial perfusion abnormalities. Early clinical experience suggests that 3D echocardiography is likely to play a valuable role in the evaluation of various cardiac disorders, especially in cardiac surgery. In this section, we will review the use of volume-rendered 3D echocardiography in the diagnosis and assessment of cardiac disorders with particular emphasis on the clinical application of this new methodology.

Echocardiography, Three-Dimensional↗