Biomedical subjects

D Zhang

Publications and source records attributed to D Zhang.

At least 127 records · Page 7Linked to original sources

PubMed2001

[Humoral immunization and cell-mediated immunization evoked by HBsAg and B7-2 Ag coexpression recombinant adenovirus vector].

OBJECTIVE: To evoke cytotoxic T lymphocytes (CTL) response and seek for a more effective method to treat chronic hepatitis B. METHODS: The adenovirus vector was constructed with the foreign genes inserted in the early region 1(E1), which directed coexpression of HBV-S and B7-2 antigens by means of an internal ribosomal entry site placed between the two coding sequences. The vector was transfected into 293 cell lines by liposome and the adenovirus expressing the target antigens was obtained by plaque select. The HBsAg and B7-2 antigen expression in in vitro cell culture was measured by ELISA and Western blotting, respectively. The immune responses were measured by ELISA for antibody response and a LDH release assay for CTL activity after immunization with the recombinant adenovirus vector in C57 mice. RESULTS: HBsAg and B7-2 antigens were highly expressed after infecting the 293 and HepG2 cell lines in vitro. The humoral response to hepatitis B surface antigen was mildly induced and could be enhanced by reinjecting a regular dose of HBsAg antigen vaccine. The cell-mediated immune response was highly induced by the recombinant adenovirus infection. No clear side effect was observed after immunization. CONCLUSION: This could be a novel strategy for a development of both preventive and therapeutic vaccines against HBV infection. The recombinant adenovirus vector is an effective and safety vector system suitable to the experiments of gene immunization and gene therapy for incurable diseases.

Adenoviridae↗

PubMed2001

[Comparison of specific immune responses to duck hepatitis B virus in infected, immune, and uninfected ducks].

OBJECTIVE: To explore the factor in determining whether hepadnavirus infection is cleared or becomes chronic. METHODS: Experimental groups were established by inoculation with duck hepatitis B virus (DHBV) at different age and schedule. The kinetics of virus replication and the humoral and cell mediated immune response (CMI) by ducks acutely and chronically infected with, or immune to DHBV infection was measured. RESULTS: Infection of the adolescent animals with DHBV led to a transient viremia. The levels of anti-DHBs and anti-DHBc were higher in acutely infected group than in chronically infected group (P<0.05), but lower than in immune group (P<0.01). CMI analysis showed the response to DHBsAg and DHBcAg by peripheral blood mononuclear cells from acutely infected ducks (10 day pi) was stronger than that from chronically infected ones (P<0.05); however, the level of the response reduced over a period of 5 weeks. There were no differences regarding CMI response in acutely infected or immune ducks. CONCLUSIONS: The immune response especially antigen -specific immune response is the key factor in determining the outcome of the infection.

Animals↗

PubMed2001

[Influence of electroporation on the biological activities of primary rat hepatocytes].

OBJECTIVE: To investigate the influence of electroporation on the biological activities of primary rat hepatocyte and to optimize the electroporation conditions introducing foreign genes into hepatocytes. METHODS: A single-pulse procedure was performed at low voltage (220-400 V) but high capacitance (500-950 microF). Its influence on hepatocyte activities was detected by Trypan blue exclusion (TBE) and MTT analysis. Besides, ALB, ALT and LDH in the supernatants of hepatocytes were tested by biochemical assay. RESULTS: Little hepatocyte damage and high survival rate (>90%) was found from 36 hours till 9th day of culture. At 36th hour after electroporation, ALB, ALT and LDH in the supernatants of Group B (220V, 950 microF) and C (400 V, 950 microF) were higher than those of control group. Whereas TBE and MTT analysis failed to indicate the significant difference of cell viability between electroporation groups and control group. CONCLUSIONS: This electroporation procedure is one of the optimal choices to introduce foreign genes into primary rat hepatocytes.

Animals↗

PubMed2001

[Chemical characteristics of fresh snow in Mount Everest Region].

The chemistry of fresh snow samples collected in August and September, 1998 from Mount Everest was studied and compared with other fresh snow samples collected in different seasons in this region. The results indicated that major species in precipitation were very low in late summer in Mount Everest region and may be representative of the background of precipitation chemistry of remote regions in the wold. Chemical Characteristics of fresh snow in different seasons had distinct differences and they may reflect different moist source and climatic status. The precipitation in August and September was mainly come from Indian summer monsoon and in April and May it was influenced deeply by the dust of semi-arid and arid regions in central Asia. This indicates the precipitation in this region is climatic sensitively.

Calcium↗

PubMed2001

[Inhibition of HBV gene expression by antisense oligonucleotides using galactosylated poly (L-lysine) as a hepatotropic carrier].

OBJECTIVE: To study the specific inhibition of HBV gene expression by antisense oligonucleotide (ASON) targeted by galactosylated poly (L-lysine) (Gal-PLL). METHODS: According to the results of direct sequencing of PCR amplified products, a 16 mer phosphorthioate analogue of the antisense oligonucleotide (PS-ASON) directed against the HBV U5-like region was synthesized and then linked with one liver-targeting ligand, the Gal-PLL. Using the 2.2.15 cells compared the effect of them on the expression of HBV gene. RESULTS: We identified that HBV DNA in the 2.2.15 cells was from HBV with surface antigen subtype ayw2 by sequencing. The fluorescent histochemistry test indicted that Gal-PLL had a selective affinity to the rat liver tissues. A 2:1 molar ratio of the Gal-PLL to DNA optimized the complex formation. In the same experimental conditions, the inhibitory effects of HBsAg and HBeAg by PS-ASON were 70% and 58%, respectively at a concentration of 10 mumol/L, while by ligand-PS-ASON were 96% and 82%, respectively, and the amount of HBV DNA in culture supernatant and cells was depressed significantly. An unrelated sequence oligonucleotide showed no effectiveness. All the oligonucleotide had no cytotoxicity. CONCLUSION: Antisense oligonucleotides complex with the liver-targeting ligand can be targeted to cells via asialoglycoprotein receptors resulting in specific inhibition of HBV gene expression and replication.

Animals↗

PubMed2001

Myocardial protection of warm blood cardioplegic induction during cardiopulmonary bypass.

In his prospective randomized clinical study, we evaluated the myocardial protection of warm blood cardioplegic induction and cold blood cardioplegic induction, respectively, during cardiopulmonary bypass. Twenty-eight adult patients who underwent valve replacement were randomly divided into two groups: group T (14 cases) received cold (6-8 degrees C) blood cardioplegic induction after ECG showed straight line induced by warm (35-37 degrees C) blood cardioplegia; whereas, group C (14 cases) received cold blood cardioplegic induction only. The effects of myocardial protection of both cardioplegic inductions were evaluated by clinical outcomes, myocardial biochemistry index (cardiac troponin T, cTnT), and myocardial automorphology. The ratio of myocardial auto resuscitation was significantly higher in group T (93%) than that in group C (50%). Only one case in group T (7%) and three cases in group C (21%) needed temporary pacemakers. No case in group T (0%) and five cases (36%) in group C received dopamine. The postoperative mechanical ventilation time and ICU stay time of group T were shorter than those of group C. Myocardial biochemistry indexplasma level of cTnT in group T was lower than that of group C immediately and 6 h after cardiopulmonary bypass. Myocardial morphology-group T had comparably better outcomes than group C. We concluded that warm blood cardioplegic induction during cardiopulmonary bypass, compared with cold blood cardioplegic induction, provides better myocardial protection.

Adult↗

PubMed2001

[The sonochemical-degradation mechanism of toluene in aqueous solution].

The sonochemical degradation of toluene in the airproof aqueous solution was studied, and the mechanism and course of degradation was explored. It was found that the sonication time had great effect on the removal rate of toluene, and the degradation followed a pseudo-first-order kinetic law, and 90%-95% of toluene was removed only after being irradiated for 40 min, types of dissolved gas and pH also had some effects. After aqueous solution was analyzed pH and scanned UV-wavelength and identified components with SMPE-GC-MS, results confirmed that radical-oxidation controlled the sonochemical-oxidation of toluene, and main middle-products included benzaldehyde, bibenzyl, dibutyl phthalate, et al., final products were carbon dioxide and water.

Free Radicals↗

PubMed2001

[Cloning and sequence analysis of light chain gene of human antibody against HBV pre-S2].

OBJECTIVE: To obtain the gene of light chain of human antibody against HBV pre-S2. METHODS: A human antibody against HBV pre-S2 displayed on phage was obtained from the constructed human immunoglobulin phage displaying library through four rounds panning of "adherence-elution-amplification" with Pre-S2 (120aa-145aa) short peptide synthesized and help phage. The positive clone of anti-pre-s2 was characterized by ELISA competitive inhibition assay. The plasmid from the positive clone was amplified by PCR with designed oligonucleotide primers of kaph light chain. The light chain fragment was amplified with PCR and plasmid pUC18 digested by restriction endonuclease SacI & XbaI, respectively, then it was subcloned into the plasmid pUC18 and was transformed into E.coli XL1-blue sensitized by CaCl2. The recombinant plasmid pUC18-kaph was sequenced. RESULTS: The competitive inhibition rate of the positive clone of anti-pre-S2 was 65% at 1:50 dilution. Sequence was compared with data in gene bank through internet and analyzed with Blast. According to the sequence and ELISA competitive inhibition assay the integral gene of kaph light chain of human antibody against HBV-PreS2 was obtained. Its variable region located on 1-328bp including three hypervariable regions (82-105bp, 145~177bp, 274~309bp) and four frame regions (1-81bp, 106-144bp, 178-273bp, 310-328bp). Its constant region was located on 329-645bp. CONCLUSIONS: The HBV pre-S2 kaph light chain is screened from phage antibody displaying library by antigen-antibody special response.

Base Sequence↗

PubMed2001

[Construction of a dicistronic expression plasmid vector containing double-valent hepatitis B surface gene].

OBJECTIVE: In order to enhance vaccine response, we constructed a dicistronic expression plasmid containing double HBsAg immunogenes. METHODS: At first, pcDNA3.1 plasmid vector was digested with NheI and EcoRI to get the coding sequence of the small (S) surface protein of HBV, then cloned into pCI-neo vector and named it pCI-S. By PCR amplification, the product of IRES-S was digested with SalI & BamHI, and cloned into pBluescript IIK+S to generate pBKS-IRES-S vector, then subcloned to the pCI-S plasmid to generate pCI-S-IRES-S, which is a dicistronic plasmid of double value HBsAg genes. RESULTS: Two plasmids we constructed were digested with related restriction nucleic enzymes. Sequence analysis of HBsAg and IRES-S gene did not reveal any mutation. CONCLUSIONS: The construction of dicistronic plasmid of divalue HBsAg immunogenes has been well cloned, which is convenient for further research on cell expression and gene immunization in animals.

Antigens, Viral↗

PubMed2001

Protein structural domain parsing by consensus reasoning over multiple knowledge sources and methods.

Domain parsing, or the detection of signals of protein structural domains from sequence data, is a complex and difficult problem. If carried out reliably it would be a powerful interpretive and predictive tool for genomic and proteomic studies. We report on a novel approach to domain parsing using consensus techniques based on Hidden Markov Models (HMMs) and BLAST searches built from a training set of 1471 continuous structural domains from the Dali Domain Dictionary (DDD). Validation on an independent test sample of family-matched structural domain sequences from the Scop database yields a consensus prediction performance rate of 75.5%, well above the 58% obtained by simple agreement of methods.

Algorithms↗

PubMed2001

[A study on quantitative assessment of osteoporosis based on texture analysis].

A quantitative assessment on osteoporosis by using texture analysis has been developed on the basis of coherence mapping, two-dimensional power spectral estimation with modulated transfer function correction and fractal features analysis on trabecular pattern of bone X-ray images. Three objective features of trabecular pattern are selected to form a feature set that can be used in automatic classification for two grades of bone: normal bone and the bone with a medium degree of osteoporosis. This set of features is extracted from each of 16 sample bone X-ray images. With the use of Euclidean norm in the feature space, a center of cluster of each grade of bone is defined as the prototype. For each bone X-ray image, the distance from its features to the two prototypes in feature space is computed to provide an objective judgement on the degree of osteoporosis. The machine classification of 10 bone X-ray images based on the developed prototype is given, and the result indicates that the proposed method is potentially applicable to the objective diagnosis of osteoporosis.

Femur↗

PubMed2001

[Characteristics of litter and its contained water in three succession communities in Dinghushan Mountain].

Studies on the characteristics of litter and its contained water in three succession communities in Dinghushan Mountain showed that the standing mass of litter was in the order of pine forest > mixed forest > broad-leaved forest, and the annual litterfall was broad-leaved forest > mixed forest > pine forest, indicating that the return rate of nutrients was lower in pine forest than in broad-leaved forest. The proportion of leaf litter decreased in the order of pine forest > mixed forest > broad-leaved forest, and that of branch, flower, and fruit litter was on the contrary, because the broad-leaved forest had the largest amount of branches and the biggest scope of canopy. The staturation water content of litter in pine forest, mixed forest and broad-leaved forest was 329.0%, 313.0% and 295.0%, respectively, showing no significant difference, but the water content of litter in three communities differed significantly, followed the order of broad-leaved forest > mixed forest > pine forest. The evaporation ratio of litter water to free water in broad-leaved forest, mixed forest and pine forest was 78.9%, 82.45% and 91.22%, respectively.

Biodegradation, Environmental↗

PubMed2001

[Spatial pattern and temporal dynamics of Atylotus pallitarsis population in Songnen Plain].

The spatial pattern and its time series dynamics of Atylotus pallitarsis population were examined in this paper. The results showed that the amount of this population was closely related to temperature and humidity, and its blood peak time appeared at about 14:00 o'clock in the afternoon. The population cattle was aggregated distribution and emigration throughout the day, the aggregated distribution pattern was loose mass community, the distribution of insects in the community was at random.

Animals↗

PubMed2001

[Humoralism and its influence on western medicine].

As the cornerstone of the ancient theories in the west, humoralism had been a dominative theory in medicine from the ancient Greek time to the 19th century, prior to the birth of the bacterial theory of disease. As a theory of holistic medicine in the west in ancient period, humoralism was similar to traditional Chinese medicine in its viewpoints of health and disease. Therefore, the review of its origin, cardinal principles and its evolution, is not only significant in the correct understanding of ancient western medicine and its appraisal, but also for the interpretation of traditional Chinese medicine as a reference.

History, Ancient↗

PubMed2001

[The etiology and clinical characteristics of central diabetes insipidus, a retrospective study of 408 cases].

OBJECTIVE: To study the etiology and clinical characteristics of central diabetes insipidus (CDI). METHODS: The clinical data of 408 cases with CDI treated in Peking Union Medical College Hospital between 1956 and 2000, including 113 cases caused by tumors in sella region, were analyzed retrospectively. Follow-up for three months to 16 years was made to 35 cases of CDI without etiological diagnosis during the first visit. RESULTS: Most of the cases among children and youngsters fell ill at the age of 8-12 years, while most of the adult cases fell ill at the age of 25-35 years. Idiopathic CDI accounted for 52%. CDI caused by tumor in sella region accounted for about 33% among the child and youngster cases, among which germinoma made up about 65%. CDI caused by tumor in sella region accounted for about 22% in adult cases. Trauma-induced CDI accounted for 11% among adult cases, and about 5% among child and youngster cases. All the CDI cases caused by histiocytosis X, accounting for 3%, were children. A correct diagnosis was made within the period of two years' follow-up among 86% of the cases. For those with brain tumors, the long-term survival rate reached 80% with radiotherapy and/or operation performed without delay. CONCLUSION: GH deficiency accompanied with growth failure is a potential indicator of CDI caused by space occupying lesion in sella region. A sudden alleviation of polydipsia may indicate the dysfunction of adrenal cortex. MRI is the most valuable examination means for tumor in sella region. Regular clinical follow-up with serial brain MRI may discover the covert tumor in sella region in cases diagnosed originally as idiopathic CDI. The cases without a correct diagnosis during the first visit should be followed-up every 3 to 6 months. The prognosis of the patients with CDI without tumor is satisfactory after ADH replacement. Radiotherapy is the most effective treatment of germinoma in sella region.

Adolescent↗

PubMed2001

[Comparison and analysis of clinicopathology of lung cancer between 1980s and 1990s in the Shenyang area (1,224 cases)].

OBJECTIVE: To compare the changes in pathogenetis and histopathology of lung cancer between 1980s and 1990s in the Shenyang area. METHODS: The HE stained sections of 572 cases of lung cancer from 1981-1990 and 652 cases from 1991-2000 were reviewed. Parts of these samples were also studied with immunohistochemistry and in situ hybridization. RESULTS AND CONCLUSIONS: By comparing the finding in the 1980s and those of the 1990s, it was found that (1) the incidence of lung cancer in women increased. (2) the highest incidence occurred in the 61 to 70 year of old group in 1990s, in 1980s it was 51-60 years. (3) there was an increased incidence of adenocarcinoma, especially papillary adenocarcinoma and acinar adenocarcinoma and bronchioloalveolar carcinoma in the 1990s.

Adult↗

PubMed2001

Optimal timing of coronary stenting in unstable angina patients.

OBJECTIVE: To assess the efficacy and safety of intracoronary stenting in the acute phase of unstable angina pectoris (UAP). METHODS: Fifty-five patients with UAP were randomized to early (Group I, n = 29) and delayed interventional treatment (Group II, n = 26). Coronary angiography and stenting were performed within 48 hours in Group I and 7-10 days later in Group II. Procedural success rate, time interval from admission to angina relief and duration of hospitalization were recorded. Cardiac events within 30 days were observed as well. RESULTS: Clinical characteristics and angiographic features were similar between the two groups. There was no significant difference in the procedural success rate (93% versus 96%), but the cardiac event rate within 30 days was significantly lower in Group I than in Group II (0% versus 9.2%, P < 0.05). The time interval from admission to angina relief (4.4 +/- 3.1 days versus 5.7 +/- 2.9 days) and the duration of hospitalization (8.8 +/- 3.2 days versus 13.5 +/- 3.1 days) were significantly reduced in Group I (both P < 0.05). CONCLUSIONS: Intracoronary stent implantation is effective and safe in the acute phase of UAP. Early percutaneous coronary intervention results in rapid improvement in symptomatology and a shorter hospitalization. Its long-term effect has to be confirmed in a future randomized study.

Aged↗

PubMed2001

Intracoronary stent implantation under intracoronary ultrasound guidance with aspirin and ticlopidine therapy.

OBJECTIVE: To observe the immediate angiographic and intravascular ultrasound (IVUS) results and their effects on one month clinical outcomes in forty-one patients who submitted to coronary stent deployment with IVUS guidance. METHODS: All patients were allocated to coronary stent implantation with high inflation pressure. After good angiographic results (< 20% residual stenosis), all patients underwent IVUS and higher-pressure dilatation would be necessary if criteria for optimal coronary stent implantation were not met. The optimal criterion of IVUS for stent implantation was the ratio of intrastent lumen cross-sectional area to the average of the proximal and distal reference lumen cross-sectional areas > or = 80%. All patients had aspirin and ticlopidine therapy on the day of angioplasty and during the one month follow-up period. RESULTS: Optimal criteria of IVUS were obtained without any further intrastent dilatation in twenty-five patients but intrastent higher-pressure dilatation was performed in fourteen patients whose ultrasound results did not reach the criteria. In these patients, we increased the minimal intrastent lumen area 25.7% (P < 0.05). Thirty-five patients (90%) had good minimal intrastent lumen area of IVUS. There were no deaths, myocardial infarction, acute stent thrombosis or need for revascularization during the study and the one month follow-up. CONCLUSIONS: Intracoronary stent deployment under IVUS guidance, including combining aspirin and ticlopidine therapy, had beneficial ultrasound results and good clinical outcomes after one month follow-up.

Aged↗