Biomedical subjects
Publications and source records attributed to Peng Zhang.
The authors present a case of acute phlegmonous gastritis occurring in an 11-month-old infant in whom the diagnosis was made by microscopic examination after surgery for perforation of the stomach. The patient recovered uneventfully. The pathogenesis, diagnosis, and treatment in this inflammatory process are discussed.
OBJECTIVES: It has been proposed that successful left ventricular surgical restoration should restore normal helical myofiber orientation. A magnetic resonance imaging technique, magnetic resonance diffusion tensor imaging, has been developed to measure myocyte orientation. By using magnetic resonance diffusion tensor imaging, this study tested the hypothesis that (1) myocyte orientation is altered after anteroapical myocardial infarction and (2) left ventricular surgical restoration restores normal helix angles. METHODS: Thirteen sheep underwent anteroapical myocardial infarction (25% of left ventricular mass). Ten weeks later, animals underwent either aneurysm plication (n = 8) or sham operations (n = 5). Six weeks after this operation, hearts were excised, perfusion fixed in diastole, and underwent magnetic resonance diffusion tensor imaging. Hearts from normal sheep (n = 5) were also harvested and imaged. Primary eigenvectors of the diffusion tensors from magnetic resonance diffusion tensor imaging were resolved into helix angles relative to a local wall coordinate system. Transmural samples of the helix angles were compared at the border zone of the aneurysm or repair (or a comparable distance from the base in normal sheep), 1 cm below the valves, and halfway between. RESULTS: The helical myofiber orientation did not change after myocardial infarction. However, aneurysm plication caused myofibers in the anterior border zone to rotate counterclockwise (-35.6 +/- 10.5 degrees , P = .028) and those in the lateral border zone to rotate clockwise (34.4 +/- 8.1 degrees , P = .031). CONCLUSIONS: Surgical restoration alters myocyte orientation adjacent to the surgical repair. However, myofiber orientation is not abnormal after myocardial infarction, and thus surgical restoration techniques intent on restoring normal helix angles might not be warranted.
OBJECTIVE: Endoventricular patch plasty (the Dor procedure) has gained favor as a surgical treatment for heart failure associated with large anteroapical myocardial infarction. We tested the hypothesis that the Dor procedure reduces left ventricular volume, increases end-systolic elastance, decreases diastolic compliance, and maintains left ventricular function. METHODS: In 6 male Dorsett sheep, the left anterior descending coronary artery and its second diagonal branch were ligated 40% of the distance from apex to base. Sixteen weeks after myocardial infarction, a Dor procedure was performed with a Dacron patch that was 50% of the infarct neck dimension. Absolute left ventricular volume was measured with magnetic resonance imaging, and left ventricular pressure and relative left ventricular volume changes during pharmacologic preload reduction were measured with a volume conductance catheter 2 weeks before and 2 and 6 weeks after the Dor procedure. End-systolic elastance, diastolic compliance, and Starling relationships were calculated from the resultant left ventricular pressure/volume loops. RESULTS: Two weeks after the Dor procedure, the left ventricular volume at end systole and end diastole was significantly reduced, and there was no redilation at 6 weeks. Six weeks after the Dor procedure, the ejection fraction was significantly increased. Although stroke volume increased slightly at 6 weeks, the change was not significant. The slopes of end-systolic elastance, diastolic compliance, and Starling relationships were unchanged at 2 and 6 weeks. CONCLUSIONS: The Dor procedure significantly reduces left ventricular volume. Unlike linear repair, left ventricular volume changes seem stable. The ejection fraction is improved, and left ventricular function (stroke volume and the Starling relationship) is maintained.
An atomic force microscope was used to subnanometer incise a nanomultilayer to consequently expose individual nanolayers and interfaces on which sliding and scanning nanowear/machining have been performed. The letter reports the first observation on the nanoscale where (i) atomic debris forms in a collective manner, most-likely by deformation and rupture of atomic bonds, and (ii) the nanolayer interfaces possess a much higher wear resistance (desired for nanomachines) or lower machinability (not desired for nanomachining) than the layers.
Establishing the relationships among modern amphibians (lissamphibians) and their ancient relatives is necessary for our understanding of early tetrapod evolution. However, the phylogeny is still intractable because of the highly specialized anatomy and poor fossil record of lissamphibians. Paleobiologists are still not sure whether lissamphibians are monophyletic or polyphyletic, and which ancient group (temnospondyls or lepospondyls) is most closely related to them. In an attempt to address these problems, eight mitochondrial genomes of living amphibians were determined and compared with previously published amphibian sequences. A comprehensive molecular phylogenetic analysis of nucleotide sequences yields a highly resolved tree congruent with the traditional hypotheses (Batrachia). By using a molecular clock-independent approach for inferring dating information from molecular phylogenies, we present here the first molecular timescale for lissamphibian evolution, which suggests that lissamphibians first emerged about 330 million years ago. By observing the fit between molecular and fossil times, we suggest that the temnospondyl-origin hypothesis for lissamphibians is more credible than other hypotheses. Moreover, under this timescale, the potential geographic origins of the main living amphibian groups are discussed: (i) advanced frogs (neobatrachians) may possess an Africa-India origin; (ii) salamanders may have originated in east Asia; (iii) the tropic forest of the Triassic Pangaea may be the place of origin for the ancient caecilians. An accurate phylogeny with divergence times can be also helpful to direct the search for "missing" fossils, and can benefit comparative studies of amphibian evolution.
The attempted synthesis of a ring-expanded guanosine (1) containing the imidazo[4,5-e][1,3]diazepine ring system by condensation of 1-(2'-deoxy-beta-D-erythropentofuranosyl)-4-ethoxycarbonylimidazole-5-carbaldehyde (2) with guanidine resulted in the formation of an unexpected product, 1-(2'-deoxy-beta-D-erythropentofuranosyl)-5-(2, 4-diamino-3, 6-dihydro-1,3, 5-triazin-6-yl)imidazole-4-carboxamide (7). The structure as well as the pathway of formation of 7 was corroborated by isolation of the intermediate, followed by its conversion to the product. Nucleoside 7 showed promising in vitro anti-helicase activity against the West Nile virus NTPase/helicase with an IC50 of 3-10 microg/mL.
We investigate the use of subspace analysis methods for learning low-dimensional representations for classification. We propose a kernel-pooled local discriminant subspace method and compare it against competing techniques: kernel principal component analysis (KPCA) and generalized discriminant analysis (GDA) in classification problems. We evaluate the classification performance of the nearest-neighbor rule with each subspace representation. The experimental results using several data sets demonstrate the effectiveness and performance superiority of the kernel-pooled subspace method over competing methods such as KPCA and GDA in some classification problems.
African cassava mosaic virus (ACMV) is a major contributor to cassava mosaic disease (CMD), the economically most important and devastating disease of cassava in Africa. We have developed transgenic cassava plants with increased ACMV resistance using improved antisense RNA technology by targeting the viral mRNAs of Rep (AC1), TrAP (AC2) and REn (AC3). Viral DNA replication assays in detached leaves demonstrated that replication of two ACMV isolates was strongly reduced or inhibited in most transgenic lines. After ACMV infection of plants using biolistic inoculation, several lines remained symptomless at lower infection pressure (100 ng viral DNA/plant). Symptom development was reduced and attenuated even at higher DNA doses. Transgenic ACMV-resistant plants had significantly reduced viral DNA accumulation in their infected leaves. Short sense and antisense RNAs specific to AC1 were identified in transgenic lines expressing AC1 antisense RNA, suggesting that the short RNAs mediate interference by post-transcriptional gene silencing. Our results demonstrate that resistance to ACMV infection of cassava can be achieved with high efficacy by expressing antisense RNAs against viral mRNAs encoding essential non-structural proteins, providing a new tool to combat CMD in Africa.
Production of transgenic plants is gradually becoming routine in cassava biotechnology. Green cotyledons of maturing somatic embryos (somatic cotyledons for short) and friable embryogenic suspensions (FES) are the target tissues for transformation by Agrobacterium or biolistics. Putative transgenic shoots develop from transformed somatic cotyledons via shoot organogenesis or from FES via somatic embryogenesis under selection. Maturation of transgenic somatic embryos is induced by transfer to maturation medium with reduced concentrations of selective agents. Mature somatic embryos can also develop directly from FES cells under selection. Transgenic plants are regenerated by the elongation of transgenic shootlets from organogenesis experiments and by the germination of or shoot development from transgenic mature embryos cultured without selection. beta-Glucuronidase (GUS) assays and rooting tests can be used to screen for escapes from selection, which improves the regeneration rate of truly transgenic plants.
OBJECTIVE: To construct eukaryotic expression vector of ribosomal protein sl5(RPs15) gene and study its effect on mouse skin fibroblasts in vitro. METHODS: The RPs15 cDNA encoding region of fetal mouse skin was amplified by reverse transcription-polymerase chain reaction (RT-PCR) method and cloned into eukaryotic expression vector pcDNA3.1(-). The recombinant plasmid was transfected into adult mouse skin fibroblasts by FuGENE6 transfection reagents. Then the expression of RPs15 gene, was detected and its biological effect on fibroblasts was measured. RESULTS: The DNA sequencing result of pcDNA3.1/RPs15 was identical with the reported. The RPs15 gene was expressed in transfected fibroblasts. The growth density of fibroblasts decreased with the conformation changing accordingly. CONCLUSIONS: The eukaryotic expression vector pcDNA3.1/RPs15 is successively constructed and can be expressed in mouse skin fibroblasts. The results set up a basis for further study of the effect of RPs15 gene on skin fibroblasts.
To study clinical outcome of G-CSF-mobilized allo-peripheral blood stem cell (PBSC) and allo-bone marrow (BM) transplantation for patients with leukemia, donors were injected G-CSF 8-10 microg/(kg.d) for 5 days, PBSC were collected on day 4-5 and G-CSF mobilized BM was extracted on day 7. Conditioning regimen consisting of fludarabine, busulfan and cyclophosphamide. The results showed that transplanted cells in all patients were engrafted, the median days of neutrophil exceeding 0.5 x 10(9)/L and platelet exceeding 20 x 10(9)/L were 10.2 days (range 9 - 12 days) and 12.5 days (range 12 - 14 days), respectively. Patients were monitored up to 100 days, 4 of 12 patients (33.3%) developed II aGVHD, 10 of 12 patients (83.3%) developed limited cGVHD. The median follow-up duration was 5 months. Two patients died, the others were alive in disease-free situation. In conclusion, allogeneic transplantation of G-CSF mobilized PBSC plus BM was safe and effective treatment for patients with leukemia, the therapy provides rapid and sustained engraftment without increase in incidence of aGVHt and cGVHD.
D64B, an achromatic early mutation, was discovered from indica rice preserver line D63B. D64B were crossed with inhomogeneous sterile lines, preserver lines and restorer lines, most of their F1 shared the same heading dates as D64B. The results indicated that D64B possessed the characteristic of dominant earliness. To analyze the earliness trait, positive and negative crosses F2 and BC1 from the cross of D64B and Shuhui 527 were cultivated. Their heading dates showed double apices distributing with same apex values. According to apex vale value -103 d, plants of the F2 and BC1 were separated into early plants and late plants, which were tested with Chi2 value. The results suggested that the segregation ratio of number of early to late plant fitted to 3:1 and 1:1 for positive and negative cross F2 and BC1, respectively, and that the earliness of D64B was controlled by a single dominant major gene. To map the gene, the polymorphisms between D64B and Shuhui 527 was analyzed with reported 356 SSR primers and 59 primers showed polymorphisms. The earliness-lateness near isogenic pools, early plants and late plants from F2 of Shuhui 527 x D64B were further amplified with the 59 primers. The results indicated that there were polymorphisms on both RM279 and RM71. Their results being analyzed with MAPMAKER/EXP3.0 software, the dominant major gene was located on the top arm of rice chromosome 2 and between the two SSR markers, RM279 and RM71, with genetic distance of 12.6 cM and 13.3 cM, respectively. According to reported data, the gene was first discovered and tentatively named as Ef-3(t). In breeding practice, sterile line D64A had been bred with D64B.
The aim of this research is to find substitute barrier materials for natural clay from two kinds of municipal sludge: waterworks sludge (S(W)) and dredging sludge (Sd). Laboratory tests were performed firstly to determine their Atterberg limits and hydraulic conductivity. Based on the results, the use of waterworks sludge was recommended. Then, shear strength tests were performed and it was found the shear resistance property of waterworks sludge is strong enough to maintain slope stability. In order to evaluate the possibility of secondary pollution, the heavy metal contents of waterworks sludge was determined and the results indicated that secondary pollution is unlikely happened. Finally, economic analysis proves that reusing waterworks sludge as barrier will reduce the lost a great for both landfill and waterworks. Based on the results, waterworks sludge was proposed to use and a further long-term simulated landfill test was suggested.
OBJECTIVE: To investigate the feasibility of gene transfection of bone marrow mesenchymal stem cell (BMSC) by cationic lipid. METHODS: The relative optimal transfection condition was determined by scale transfection experiment in vitro and the transient transfection efficiency of enhanced green fluorescence protein (EGFP) gene for rat BMSC was determined with Lipofectamine2000 (LP2000). The relationship between cell cycle status and the expression of the gene was analyzed. The intensity and the ratio of EGFP gene expression versus time was determined by flow cytometry. In the in vivo study, the transgenic rat BMSC was injected into the myocardium of inbred rats, and the in vivo transcription of EGFP gene and the EGFP-expressing BMSC were traced in the myocardium after transplantation using reverse transcription-polymerase chain reaction and fluorescent microscopy, respectively. RESULTS: EGFP gene transfection efficiency in BMSC was different under different transfection condition (DNA concentration and DNA: LP2000). Cationic lipid-mediated transfection demonstrated marked toxicity to BMSC. Cell cycle status restricted the expression efficiency of the gene introduced by cationic lipid. The EGFP expressing-BMSC and in vivo transcription of the EGFP gene could be detected in rat myocardium post implantation. CONCLUSION: Cationic lipid is an effective carrier for gene-modified cell transplantation therapy.
OBJECTIVE: To study the microsatellite abnormalities of the aromatic amine exposure-associated transitional cell carcinoma (TCC) and sporadic TCC of urinary bladder, and to evaluate the potential of microsatellite analysis on detection of this diseases. METHODS: Based on our previous investigations, 5 microsatellite markers (D17S695, D9S162, D3S1295, DBH and D3S1234) that had high frequencies of loss of heterozygosity (LOH) in sporadic TCC, were selected for analysis with the bladder lesions derived from 16 patients with aromatic amine exposure history. The microsatellite analysis with urine sediments from the post-operated patients was also carried out. RESULTS: There was at least one informative marker out of the 5 microsatellite foci showed polymorphism in the DNA derived from 16 patients examined. Within 87.50% (14/16) patients, LOH was detected in the bladder lesions at least with one microsatellite marker. The LOH frequency of D3S1295 was higher in occupational TCC patients than that in sporadic TCC patients. The diagnostic accordance rate of patients showed LOH in at least one microsatellite marker with patients diagnosed by pathology was 81.25% (13/16). In the urine sediments from 8 TCC post-operated patients, LOH was found at least with one microsatellite marker. CONCLUSION: There could be a different LOH pattern in aromatic amine exposure-associated TCC, and genes near D3S1295 might play a role in the occupational exposure-associated TCC.
A new upconversion luminescence agent, 40CdF2 x 60BaF2 x 0.8Er2O3, was synthesized and its fluorescent spectra were determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks shown in the fluorescent spectra whose wavelengths are all below 387 nm under the excitation of 488 nm visible light. This upconversion luminescence agent was mixed into nano rutile TiO2 powder by ultrasonic and boiling dispersion and the novel doped nano TiO2 photocatalyst utilizing visible light was firstly prepared. The doped TiO2 powder was charactered by XRD and TEM and its photocatalytic activity was tested through the photocatalytic degradation of methyl orange as a model compound under the visible light irradiation emitted by six three basic color lamps. In order to compare the photocatalytic activities, the same experiment was carried out for undoped TiO2 powder. The degradation ratio of methyl orange in the presence of doped nano TiO2 powder reached 32.5% under visible light irradiation at 20 h which was obviously higher than the corresponding 1.64% in the presence of undoped nano TiO2 powder, which indicate the upconversion luminescence agent prepared as dopant can effectively turn visible lights to ultraviolet lights that are absorbed by nano TiO2 particles to produce the electron-cavity pairs. All the results show that the nano rutile TiO2 powder doped with upconversion luminescence agent is a promising photocatalyst using sunlight for treating the industry dye wastewater in great force.
AIM: To establish a fingerprint analysis method of Fritillaria hupehensis. METHODS: fingerprint was performed by HPLC-ELSD. Hypersil ODS column was used; the mobile phase was composed of methanol (with 0.05% triethylamine) and water with gradient elution; flow rate was 1.0 mL x min(-1); recording time was 60 min; drift tube temperature was 75 degrees C; gas flow rate was 1.9 L x min(-1). RESULTS: HPLC fingerprint of Fritillaria hupehensis was obtained. CONCLUSION: A reliable method was provided for controlling the quality of Fritillaria hupehensis.
Infarcted segments of myocardium demonstrate functional impairment ranging in severity from hypokinesis to dyskinesis. We sought to better define the contributions of passive material properties (stiffness) and active properties (contracting myocytes) to infarct thickening. Using a finite-element (FE) model, we tested the hypothesis that infarcted myocardium must contain contracting myocytes to be akinetic and not dyskinetic. A three-dimensional FE mesh of the left ventricle was developed with echocardiographs from a reperfused ovine anteroapical infarct. The nonlinear stress-strain relationship for the diastolic myocardium was anisotropic with respect to the local muscle fiber direction, and an elastance model for active fiber stress was incorporated. The diastolic stiffness (C) and systolic material property (isometric tension at longest sarcomere length and peak intracellular calcium concentration, T(max)) of the uninfarcted remote myocardium were assumed to be normal (C = 0.876 kPa, T(max) = 135.7 kPa). Diastolic and systolic properties of the infarct necessary to produce akinesis, defined as an average radial strain between -0.01 and 0.01, were determined by assigning a range of diastolic stiffnesses and scaling infarct T(max) to represent the percentage of contracting myocytes between 0% and 100%. As C was increased to 11 times normal (C = 10 kPa) the percentage of T(max) necessary for akinesis increased from 20% to 50%. Without contracting myocytes, C = 250 kPa was necessary to achieve akinesis. If infarct stiffness is <285 times normal, contracting myocytes are required to prevent dyskinetic infarct wall motion.