Search PubMed⌕ Search

Biomedical subjects

Yong Zhang

Publications and source records attributed to Yong Zhang.

At least 109 records · Page 6Linked to original sources
PubMed2006

Inheritance analysis of herbicide-resistant transgenic soybean lines.

Four transgenic soybean lines generated via Agrobacterium-mediated transformation were used to analyze inheritance of the transgenes. Seed chip GUS assay and herbicide leaf painting and spraying assays were applied to test the gus reporter gene and the herbicide resistant bar selectable marker gene, respectively. Three of the four transgenic soybean lines were stably inherited in a Mendelian fashion with co-segregation of both transgenes in a 3:1 segregation ratio in the T(1) progeny, indicating that both transgenes were integrated into the same locus of the soybean genome. Homozygous transgenic progeny plants were obtained in the T(2) generation of these lines, and the transgenes were inherited in five successive generations. However, in one transgenic line, all the T(1) progeny plants showed GUS negative and herbicide sensitive. Southern blotting analysis confirmed that the transgenes were passed into the T(1) progeny, indicating that the transgenes were both silenced. To test if the transgene silencing was due to transcriptional or post-transcriptional level, Soybean mosaic virus (SMV) was inoculated on leaf tissues of the T(1) plants to test possible reverse effects on transgene silencing. Infection with SMV did not suppress transgene silencing, suggesting that transgene silencing in this transgenic line may not be due to post-transcriptional gene silencing.

Gene Silencing↗
PubMed2006

Surface-enhanced Raman scattering from transition metals with special surface morphology and nanoparticle shape.

This discussion focuses on our recent approaches at aiming to optimize surface-enhanced Raman scattering (SERS) activity for transition metals (group VIII B elements), by intentionally fabricating desired surface nanostructures or synthesizing nanoparticles. The SERS activity of transition metals critically depends on the surface morphology of electrodes and on size, shape and aggregation form of nanoparticles. A correct surface roughening procedure for transition-metal electrodes is indispensable for fabricating cauliflower-like nanostructures that show a higher SERS activity. Two more methods have been explored to synthesize nanoparticles, i.e., cubic nanoparticles and gold-core palladium-shell nanostructures, respectively. Their SERS activities are considerably higher than those of normal spherical mono-metallic nanoparticles. To explain these observations, a preliminary theoretical calculation, using the three-dimensional finite difference time domain (3D-FDTD) method, was performed to evaluate the local electromagnetic field on transition metal surfaces. The result is in good agreement with the experimental data.

Journal Article↗
PubMed2006

Expression of nerve growth factor receptors is correlated with progression and prognosis of human pancreatic cancer.

BACKGROUND AND AIM: The aim of the present study was to investigate the prognostic value of the two types of nerve growth factor receptors (NGFR), namely high-affinity receptor TrkA and low-affinity receptor p75NGFR, in pancreatic cancer. METHODS: The mRNA expression of NGFR for TrkA and p75NGFR was examined in 56 human primary pancreatic cancers using real-time quantitative reverse transcription-polymerase chain reaction. RESULTS: Nerve growth factor (NGF) receptors were found in all tumor specimens. It appears that the growth of pancreatic cancer cells stimulated by NGF depended on the expression levels and the ratio of TrkA to p75NGFR. TrkA and p75NGFR were negatively correlated and both were associated with abdominal or back pain and perineural invasion. Regarding this, patients with high TrkA expression levels exhibited more frequent perineural invasion and a higher degree of pain, whereas the results of p75NGFR were opposite. For Cox univariate analyses in the overall survival study, high expression of p75NGFR was associated with longer overall survival, but TrkA exhibited opposite effects and included an effect on perineural invasion and pain. Histoprognostic grading, tumor size and node involvement were not prognostic factors. In Cox multivariate analyses, TrkA and p75NGFR were both prognostic parameters. CONCLUSIONS: The present study found that the expression of TrkA in pancreatic cancer is a marker of tumor aggressiveness. Conversely, we also found that elevated p75NGFR expression is associated with a favorable prognosis. We demonstrated that NGF exerts both stimulatory and inhibitory effects on pancreatic cancers, with the overall effect determined by the expression levels and the ratio of TrkA to p75NGFR.

Adenocarcinoma↗
PubMed2006

Factors influencing the prevalence of gallstones in liver cirrhosis.

BACKGROUND AND AIMS: To investigate the prevalence of gallstone disease in Chinese patients with liver cirrhosis and to identify risk factors for cholelithiasis. METHODS: Blood samples were tested and ultrasonographic examination of the upper abdomen was conducted to observe the prevalence of gallstones in 90 compensated cirrhotic patients (Child-Pugh A), 180 decompensated cirrhotic patients (Child-Pugh B, C) and 300 controls. Risk factors for gallstone formation (age, sex, pregnancy, family history) and the characteristics of liver cirrhosis (Child class, inside diameter of portal vein), and gallbladder (wall thickness) were assessed. RESULTS: Gallstones were found more often in cirrhotic patients (23.7%) than in controls (7.33%, P < 0.001). The prevalence of gallstones in decompensated cirrhotic patients was higher than that of the compensated cirrhotic patients (P < 0.001). Advanced age, female sex, family history of gallstones, gallbladder wall thickness 4 mm or greater and inside diameter of portal vein 13 mm or greater were significantly associated with gallstone disease in patients with liver cirrhosis. Multivariate analysis revealed that age (P < 0.001), sex (P = 0.0005) and thickness (4 mm or greater) of the gallbladder wall (P = 0.0064) were independently associated with gallstone disease in such patients. CONCLUSIONS: This study confirms the high prevalence of cholelithiasis in liver cirrhosis. Age and sex are risk factors for gallstones and gallbladder wall thickness could be an additional risk factor for the development of gallstone in patients with liver cirrhosis.

Abdomen↗
PubMed2006

Identification of melanoma-specific peptide epitopes by HLA-A2.1-restricted cytotoxic T lymphocytes.

HLA-A2.1-associated peptides, extracted from human melanoma cells, were used to study epitopes for melanoma-specific HLA-A2.1-restricted cytotoxic T lymphocytes (CTLs) by epitope reconstitution, active peptide sequence characterization and synthetic peptide verification. CTL were generated from tumor-involved nodes by in vitro stimulation, initially with autologous melanoma cells and subsequently with allogeneic HLA-A2.1 positive melanoma cells. The CTLs could lyse autologous and allogeneic HLA-A2.1 positive melanomas, but not HLA-A2.1 negative melanomas or HLA-A2.1 positive non-melanomas. The lysis of melanomas could be inhibited by anti-CD3, anti-HLA class I and anti-HLA-A2.1 monoclonal antibodies. HLA-A2.1 molecules were purified from detergent-solubilized human melanoma cells by immunoaffinity column chromatography and further fractionated by reversed phase high performance liquid chromatography. The fractions were assessed for their ability to reconstitute melanoma-specific epitopes with HLA-A2.1 positive antigen-processing mutant T2 cells. Three reconstitution peaks were observed in lactate dehydrogenase release assay. Mass spectrometry and ion-exchange high performance liquid chromatography analysis were used to identify peptide epitopes. Peptides with a mass-to-charge ratio of 948 usually consist of nine amino acid residues. The data from reconstitution experiments confirmed that the synthetic peptides contained epitopes and that the peptides associated with HLA-A2.1 and recognized by melanoma-specific CTL were present in these different melanoma cells. These peptides could be potentially exploited in novel peptide-based antitumor vaccines in immunotherapy for CTL.

Antibodies, Monoclonal↗
PubMed2006

Dominance of HIV-1 subtype CRF01_AE in sexually acquired cases leads to a new epidemic in Yunnan province of China.

BACKGROUND: Dating back to the first epidemic among injection drug users in 1989, the Yunnan province has had the highest number of human immunodeficiency virus type 1 (HIV-1) infections in China. However, the molecular epidemiology of HIV-1 in Yunnan has not been fully characterized. METHODS AND FINDINGS: Using immunoassays, we identified 103,015 accumulated cases of HIV-1 infections in Yunnan between 1989 and 2004. We studied 321 patients representing Yunnan's 16 prefectures from four risk groups, 11 ethnic populations, and ten occupations. We identified three major circulating subtypes: C/CRF07_BC/CRF08_BC (53%), CRF01_AE (40.5%), and B (6.5%) by analyzing the sequence of p17, which is part of the gag gene. For patients with known risk factors, 90.9% of injection drug users had C/CRF07_BC/CRF08_BC viruses, whereas 85.4% of CRF01_AE infections were acquired through sexual transmission. No distinct segregation of CRF01_AE viruses was found among the Dai ethnic group. Geographically, C/CRF07_BC/CRF08_BC was found throughout the province, while CRF01_AE was largely confined to the prefectures bordering Myanmar. Furthermore, C/CRF07_BC/CRF08_BC viruses were found to consist of a group of viruses, including C, CRF08_BC, CRF07_BC, and new BC recombinants, based on the characterization of their reverse transcriptase genes. CONCLUSIONS: This is the first report of a province-wide HIV-1 molecular epidemiological study in Yunnan. While C/CRF07_BC/CRF08_BC and CRF01_AE are codominant, the discovery of many sexually transmitted CRF01_AE cases is new and suggests that this subtype may lead to a new epidemic in the general Chinese population. We discuss implications of our results for understanding the evolution of the HIV-1 pandemic and for vaccine development.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Influence of temperature fluctuation on thermophilic anaerobic digestion of municipal organic solid waste.

A laboratory-scale experiment was carried out to assess the influence of temperature fluctuation on thermophilic anaerobic digestion of municipal organic solid waste (MOSW). Heating failure was simulated by decreasing temperature suddenly from 55 degrees C to 20 degrees C suddenly; 2 h time is needed for temperature decrease and recovery. Under the conditions of 8.0 g/(L.d) and 15 d respectively for MOSW load and retention time, following results were noted: (1) biogas production almost stopped and VFA (volatile fatty acid) accumulated rapidly, accompanied by pH decrease; (2) with low temperature (20 degrees C) duration of 1, 5, 12 and 24 h, it took 3, 11, 56 and 72 h for the thermophilic anaerobic digestion system to reproduce methane after temperature fluctuation; (3) the longer the low temperature interval lasted, the more the methanogenic bacteria would decay; hydrolysis, acidification and methanogenesis were all influenced by temperature fluctuation; (4) the thermophilic microorganisms were highly resilient to temperature fluctuation.

Archaea↗
PubMed2006

UV irradiation controlled cold vapor generation using SnCl2 as reductant for mercury speciation.

A simple and ultrasensitive method, which was based on cold vapor generation (CVG) coupled to atomic fluorescence spectrometry (AFS), was proposed for speciation analysis of inorganic mercury (Hg2+) and methylmercury (MeHg) in water samples. In the presence of UV irradiation, all the mercury (MeHg+Hg2+) in a sample solution can be reduced to Hg0 by SnCl2; without UV irradiation, only Hg2+ species can be determined. So the concentration of MeHg can be obtained from the difference of the total mercury and Hg2+ concentration; thus, speciation analysis of Hg2+ and MeHg was simply achieved without chromatographic separation. Under the optimized experimental conditions, the limits of detection were 0.01 ng mL-1 for both Hg2+ and MeHg. The sensitivity and limit of detection were not dependent on the mercury species, and a simple Hg2+ aqueous standard series can be used for the determination of both Hg2+ and MeHg.

Journal Article↗
PubMed2006

[Tumor inhibiting and immunoloregulation effects of Mylabris Mixture on H22 cancer-bearing mice].

OBJECTIVE: To investigate the mechanisms of tumor inhibiting and immunoloregulation of Mylabris Mixture on H22 cancer-bearing mice. METHODS: H22 cancer-bearing mice were chosen to observe the effects of tumor inhibiting and detect the proliferation function of T lymphocytes, the toxicity function of NK cells, the changes of T lymphocytes and the contents of interferon-gamma and interleukin-4. RESULTS: Mylabris Mixture could obviously inhibit the growth of H22 cancer in mice, and the tumor inhibition rat was 65.76%. The stimulation index of T lymphocyte transformation and percentage of NK cells in Mylabris Mixture-treated group were obviously higher than those in the normal control group. The subpopulation proportion of T lymphocytes in Mylabris Mixture-treated group was changed more than the normal control group. The production of interferon-gamma and interleukin-4 by T lymphocytes obviously increased in Mylabris Mixture-treated group (P<0.05, P<0.001). CONCLUSION: Mylabris Mixture has the effect of inhibiting the growth of tumor constitution, and regulating immunological function on mice with tumor. Its mechanisms include the reinforcement of T lymphocyte immune function, NK cell killing function and humoral immune function.

Animals↗
PubMed2006

[Molecular cloning and functional analysis of bovine mammary gland matrix attachment regions].

The bovine genomic DNA was extracted from bovine blood, then bovine mammary gland matrix attachment region (BMARs) was cloned using a pair of primers, which were designed based on the related sequences in GenBank through bio-software Primer5.0 and Vector7.0. Upon preliminary analysis with bio-software, BMARs was TA cloned into PMD-18 T vector. By means of adding Kpn2 I and Xho I to 5' upstream of sensitive and antisensitive primers respectively, expressing vector BE was constructed after BMAR was cloned into the downstream of the reporter gene in pEGFP-C1. Bovine ear fibroblast cells were transfected by expressing vector BE with Lipofectamine.Compared with control bovine ear fibroblast cells transfected with pEGFP-C1, the effect of cloned BMR was apparent in dispelling position effect and enhancing gene expression.

Animals↗
PubMed2006

[Shape coefficient--a new concept to describe the vascular stent mechanical property].

In this paper, we advance a concept, shape coefficient, to describe the mechanical properties of shape factor concretely. Two sorts of shape coefficient are deduced from the plastic theory of bending beam. Under conditions of the same material and radius,a simple form of shape coefficient is acquired. The relevant computing results and experiment show that the limit load of vascular stent exists,and vascular stents in different width-thickness have the same shape coefficient so long as they are the same shape. These reveal the significance of the concept of shape coefficient and verify the correctness of the formula.

Angioplasty, Balloon, Coronary↗
PubMed2006

[Nuclear transfer and mitochondria].

Mitochondria, which can produce and supply energy for mammals, are involved in many cellular events of growth, development, aging, apoptosis as well as diseases. Nuclear transfer could result in mitochondria heteroplasmy in cloned embryos and offspring, affecting the phenotypes of the individuals and even causing mitochondrial diseases. This text has expounded the biological functions and the hereditary characteristics of the mitochondria in mammals, and analyzed the change of donor and recipient mitochondria in embryos and offspring derived from intraspecific and interspecific embryonic or somatic nuclear transfer as well as several factors which might influence mitochondrial heteroplasmy in the process of nuclear transfer. The mitochondrial diseases it may cause and their solutions are also briefly presented.

Animals↗
PubMed2006

[The application of co-culture system on the in vitro development of bovine somatic nuclear transferred embryos].

To establish a co-culture system of nuclear transferred embryos in bovine, effects of co-culture cell types, passages and cryopreservation as well as addition of BFF or FBS were investigated. The results showed that embryos co-cultured with oviductal epithelial cell and granulosa cell achieved significantly higher blastocyst rate compared with the control group (P < 0.05) and co-cultured with oviductal epithelial cell had more embryo cell number than those with granulosa cell. Passages of co-culture cells significantly affected the blastocyst rate and embryo cell number (P < 0.05), and cryopreservation decreased the blastocyst rate and embryo cell number remarkably. Supplemention of BFF increased blastocyste rate significantly (P < 0.05). In conclusion, co-cultured with fresh primary oviductal epithelial cell along with addition of 10% BFF in SOFaa could improve development of nuclear transferred bovine embryo in vitro.

Animals↗
PubMed2006

[Cerebral ischemia manifested as recurrent loss of consciousness].

OBJECTIVE: To demonstrate the clinical characteristics of cerebral ischemia that mainly manifested as recurrent loss of consciousness and to explore the pathogenesis of these incidents. METHODS: Twelve patients who had cerebral ischemia that manifested mainly as recurrent loss of consciousness were retrospectively studied. Their risk factors, clinical characteristics, cranial MRIs, angiograms and perfusion images were recorded in detail. The patients were followed up for at least 90 days. RESULTS: Every patient had at least one risk factor for cerebrovascular disease. The clinical manifestations in most of the patients are syncope-like incidents, but the duration was longer, lasting for minutes to hours, but mostly less than 24 hours. These patients could be sorted into three types according to the angiographic data: type A severe stenosis in anterior circulation (mostly on both sides); type B severe stenosis in posterior circulation; and type C multiple severe stenosis (in both anterior and posterior circulation). Cerebral blood flow was severely reduced in the stenotic arteries as shown by angiogram. The perfusion studies in type A patients also showed diffuse hypoperfusion of cerebrum. In one case, the patient lost his consciousness when the Angioguard (a protective guidewire) passed through the stenosis, and he regained consciousness when the stent was fully-opened in a few minutes. All the 12 patients received medical therapy. Four patients who were ineffective with medical treatment along received stent angioplasty and there was no incident during the follow-up. Six of the remaining eight patients with medical treatment alone had ischemic strokes within 90 days, including two with disabling strokes. CONCLUSIONS: Recurrent loss of consciousness is a rare manifestation of large cerebral artery stenosis. The probable mechanism may be diffuse hypoperfusion in cerebrum or brainstem. These patients are in high risk of stroke. Interventional therapy to revascularize the cerebral circulation may be a rational treatment.

Aged↗
PubMed2006

[Treatment of cleft lip and palate: past, present and future].

Comparing the survey results of 224 Centers of Cleft Lip and Palate in the United States with the current status in China, and reviewing the experience and lessons systemically, we could get a conclusion that the repair of cleft lip and palate depends on the experience and excellent skills of the surgeons, and its important role in combined and sequential treatment (team approach) of cleft lip and palate should not be ignored. The team approach program requires multidisciplinary cooperation and good compliance of the patients. In order to improve the treatment outcomes of cleft lip and palate, it is necessary for us to study the advanced program and methods and combined the situation of our country.

China↗
PubMed2006

[Knockdown of Hsp701A induces K562 cells apoptosis by RNA interference].

AIM: To investigate the apoptosis of K562 cells induced by RNA interference(RNAi) targeting Hsp701A. METHODS: Small interference RNA (siRNA) targeting Hsp701A was generated and its eukaryotic expression vectors was constructed and transected into K562 cells. Proliferation, apoptosis and cell cycle of the transected cells was respectively detected by MTT colorimetry and FCM. RESULTS: The eukaryotic expression vector of siRNA against Hsp701A was successfully constructed and transfected into K562 cells, which markedly decreased the expression of Hsp701A on both mRNA and protein level. K562 cells transfected with the vector exhibited slower proliferation, increased apoptosis and increased G(0)/G(1) arrest. CONCLUSION: The inhibition of Hsp701A gene by RNAi may provide a foundation for the development of novel therapeutic strategy for chronic granulocyte leukemia (CML).

Apoptosis↗
PubMed2006

[Determination of metallic elements in different parts of Salvia miltiorrhiza by FAAS].

The root, stem and leaf of Salvia miltiorrhiza were digested with HNO3-HClO4 (4:1), and the contents of five metallic elements such as K, Cu, Zn, Fe and Mg were detected by flame atomic absorption spectrophotometry. The recovery ratio by standard addition is 99.7%-104.4% and RSD is less than 2%. It was found that the content sequence of metallic elements is as follows: K>Mg >Fe>Zn>Cu. K, Cu, Zn, Fe and Mg in the leaf are clearly richer than those in the root and stem. The content ratio of Zn to Cu is relatively lower than that in the terrestrial angiosperms. The results provide a useful data for discussing the relationship between the contents of these elements in Chinese medicinal herb Salvia miltiorrhiza and the medical effects. Furthermore they also provide a data for the distribution of these elements in different parts of Salvia miltiorrhiza.

Drugs, Chinese Herbal↗