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Biomedical subjects

X Cheng

Publications and source records attributed to X Cheng.

At least 145 records · Page 8Linked to original sources
PubMed1998

[Preventional intervention of myocardial interstitial fibrosis in murine myocardium with acute myocarditis].

OBJECTIVES: To explore that whether intervening the fibrosis of heart interstitium in acute viral myocarditis is practical or not, and offer the experimental basis for clinic to choose the optimum period to intervene myocardial fibrosis. METHODS: Animals were divided into three groups: myocarditis, myocarditis intervened by Losartan, and normal control. The death rate of every group was compared. HE staining and picrosirius red staining and circularly polarized light were used to investigate myocardial collagen expression. Cardiac output was measured by impedance differentiation, and cardiac index was computed to evaluate cardiac function. RESULTS: The death rate of the group with Losartan was 75.0%, and that of the myocarditis group was 41.7%. The cardiac index of the group with the drug was 0.014 +/- 0.001 ml.min-1.cm2, the myocarditis group 0.019 +/- 0.004 ml.min-1.cm2, and the normal control 0.024 +/- 0.002 ml.min-1.cm2. The scanning area of collagen in the group with the drug was 2.06 +/- 0.77 mm, the myocarditis group 4.72 +/- 2.22 mm and the normal control 3.74 +/- 1.50 mm. CONCLUSIONS: Collagen has increased in acute viral myocarditis, but its main role in this time is to repair the necrotic myocardium, and Losartan may block this process and make lesions develop. Therefore, the acute stage is not an practical period for intervening myocardial fibrosis in viral myocarditis.

Animals↗
PubMed1998

[Effects of an extract of salviae miltiorrhizae (764-3) on structural remodeling of intra-acinar pulmonary artery in pulmonary hypertension due to chronic hypoxia and monocrotaline in rats].

OBJECTIVE: To investigate the effects of an extract of salviae miltiorrhizae (764-3) on the percentage of intra-acinar muscular artery (MA), partal MA(PMA) and nonmuscular MA(NMA) and collagen deposition in the media of MA in rats with hypoxia and MCT-induced pulmonary hypertension. METHOD: Wistar rats were divided into 12 groups. The hypobaric hypoxic 51 kPa (1 kPa = 7.5 mmHg) and MCT (60 mg/kg intraperitoneal injection) rats were treated with 764-3 (20 mg/kg), beta-aminopropionitrile (BAPN, 150 mg/kg) and 764-3 (40 mg/kg), respectively. At each time point, the hemodynamic and morphological parameters were measured. RESULT: After hypoxia for 2 weeks, the percentage of MA increased (P < 0.001), of NMA decreased (P < 0.001) and of PMA no obvious change; and after 4 weeks, the above changes became to be more striking and the collagen content in the media of MA increased (P < 0.001). The MCT-treated rats had more severe changes than the hypoxic rats. Both 764-3 and BAPN could inhibit the changes, decreased the collagen content and BAPN was more effective than 764-3(P < 0.05). CONCLUSION: 764-3 can partially inhibit collagen deposition in pulmonary arterioles attenuate hypoxia and MCT-induced pulmonary hypertension, reduce the percentage of MA, and has a moderate influence on collagen deposition as compared with BAPN.

Animals↗
PubMed1998

[Isolation and purification of the active principle from agkistrodon acutus snake venom by high performance ion-exchange liquid chromatography].

The active component from Agkistrodon acutus snake venom was further purified by high performance ion-exchange liquid chromatography over a Protein-PAK DEAE-8HR column(10.0 mm i.d. x 100 mm). The elution was operated with a linear gradient from 10% to 100% NaCl-0.02 mol/L Tris-HCl buffer(pH 8.0). The quantitative results were calculated as 45.41% based on peak area nomalization and the purity of the active component was 90% determined by electrophoresis.

Agkistrodon↗
PubMed1998

[Effect of 764-3 on ventricular collagen deposition in pulmonary hypertension induced by chronic hypoxia and monocrotaline in rats].

OBJECTIVE: To observe the effect of 764-3 on ventricular collagen deposition in pulmonary hypertension induced by chronic hypoxia or monocrotaline (MCT) in rats. METHODS: Wistar rats were divided into 10 groups. The hypobaric hypoxia group received 764-3 20 mg/kg once daily subcutaneously and the MCT group treated with 764-3 40 mg/kg once daily. The hemodynamic and biochemical parameters were measured. RESULTS: At the time of 2 weeks and 4 weeks after treated with hypoxia or MCT, the pulmonary arterial pressure (PAP) of rats raised significantly and the right ventricular collagen content (RVCC) increased markedly. 764-3 could reduce the raised PAP induced either by hypoxia or MCT. It could lower the elevated RVCC of hypobaric hypoxia group at 2 weeks from 76.3 +/- 13.3 to 59.4 +/- 11.4 (P < 0.01), and the RVCC of MCT group lowered from 293.4 +/- 73.9 to 210.1 +/- 37.6(P < 0.01). CONCLUSION: 764-3 could partially prevent right ventricular collagen deposition induced by hypoxia and has therapeutic effect on that induced by MCT.

Animals↗
PubMed1998

[Effects of 764-3 on collagen deposition in hypertensive pulmonary arteries in hypoxic rats].

OBJECTIVE: To investigate the changes of collagen deposition in pulmonary arteries in chronic hypobaric hypoxic rats and the roles of 764-3. METHODS: Wistar rats were divided into 10 groups. The hypoxic (50.7 kPa) rats were treated with 764-3 (20 mg/kg, once daily) and beta-aminopropionitrile (BAPN, 150 mg/kg, twice daily), respectively. At the end of treatment, the hemodynamic morphological and chemical parameters were measured. RESULTS: Comparing with the normals, hydroxyproline (HYP) content of extrapulmonary artery (EPA) increased obviously in hypoxic rats, the smooth muscle cells (SMC) in the media of muscular intra-acinar pulmonary artery showed hypertrophy with change in phenotype, and a striking increment of collagen accumulation (P < 0.001); 764-3 could reduce HYP content of EPA (P < 0.05-0.001), and most of SMC in the media became thin and elongated with reversion of change of SMC phenotype, and collagen accumulation was reduced (P < 0.001). In addition, BAPN was more effective than 764-3 (P < 0.05). CONCLUSIONS: Excessive collagen accumulation in pulmonary arteries plays an important role in the maintenance of hypoxic pulmonary hypertension. 764-3 can partially inhibit collagen deposition in pulmonary arteries, attenuate hypoxic pulmonary hypertension, and has a moderate influence on collagen deposition in compared with BAPN.

Aminopropionitrile↗
PubMed1998

[Observation on effect of shenmai injection in treating patients of congestive heart failure].

OBJECTIVE: To observe the clinical therapeutic effect of Shenmai Injection (SMI) in treating patients of congestive heart failure. METHODS: Effect of 16 cases treated with SMI or potassium magnesium aspartate was observed by randomized crossover method and compared. RESULTS: By using SMI for 2 weeks, patients' left ventricular ejective fraction (LVEF) could be increased from 29.5 +/- 9.0 to 36.6 +/- 10.2 (P < 0.05), the heart function of 68.75% patients was improved, no side effects or toxicity was observed. Potassium magnesium asparate could improve heart function in 37.50% patients only but with no effect on LVEF. CONCLUSION: SMI is an effective and safe therapy in treating patients with congestive heart failure.

Adult↗
PubMed1998

[Analysis of basic data of the study on prevention and treatment of COPD and chronic cor pulmonale].

OBJECTIVE: The basic data were analysed to carry out the project of "the study on prevention and treatment of COPD and chronic cor pulmonale population" and to provide some scientific basis for making strategies of prevention and treatment of COPD and chronic cor pulmonale in communities. METHOD: The basic survey of the study was carried out on 102,230 rural people in the spring of 1992. At first the family inquiry into the chronic airway inflammation history and smoking index > or = 300 were made in population aged 15 years or more. Those with FEV1/FVC < 70% in lung function were considered as having COPD, and chronic cor pulmonale was diagnosed according to national criteria by chest radiography and electrocardiography. RESULT: There were 67,251 people aged > or = 15 years in 102,230 population, among them 33,119 were male and 34,132 were female. Of the 7,400 subjects who should be investigated, 6,536 subjects were really investigated (88.3%), which accounted for 9.7% of > or = 15 year population. 2,020 people were diagnosed as having COPD, the prevalence of COPD being 3.0% in total population(> or = 15 years), and the highest was 4.5% in Beijing. The prevalences of COPD in smokers, subjects with chronic airway inflammation history and both of them were 24.6%, 34.7% and 40.4%, respectively. The sole smoking accounted for 40.7% and chronic airway inflammation history for 28.4% in the all COPD causes, respectively. 71.6% of COPD were related to smoking. 452 patients were diagnosed as having chronic cor pulmonale, which accounted for 23.1% of COPD, for 6.7@1000 of > or = 15 year population, for 4.4@1000 in total population. CONCLUSION: The basic data demonstrate that the prevalence of COPD and chronic cor pulmonale are quite high. There are remarkable differences of the prevalences among different regions. The primary causes of COPD and chronic cor pulmonale are smoking and chronic airway inflammation. The strategy of prevention and treatment of them should be a comprehensive one, the key measure be smoking cessation and controling airway inflammation.

Adolescent↗
PubMed1998

[Preliminary studies on chemical constituents and pharmacological action of Eclipta prostrata L].

OBJECTIVE: To study the pharmacologically active components of Eclipta prostrata. METHOD: The components were extracted by alcohol and isolated by silica gel column and subjected to pharmacological screening. RESULT: Four compounds were isolated from E. prostrata, of which two were identified as stigmasterol and alpha-terthienyl. CONCLUSION: alpha-Terthienyl was isolated from the plant for the first time. The EtOAc part of alcoholic extraction exhibits significant hepatoprotective activity against carbon terachloride-induced liver injury in rats.

Alanine Transaminase↗
PubMed1998

[Ultrasound biomicroscopic dark room provocative test].

OBJECTIVE: To compare the clinical application of ultrasound biomicroscopic (UBM) dark room provocative test and traditional one in screening primary angle-closure glaucoma (PACG). METHOD: 22 eyes (22 cases) with PACG in prodromal stage and 30 eyes (15 cases) with deep anterior chamber and wide angle of 15 normal persons were observed in this trial. Traditional dark room provocative test and UBM dark room provocative test were performed on all the 52 eyes at the same day time on separate days. With different positive diagnostic criteria, the sensitivity of the two methods was compared by using chi-square analysis. RESULTS: After staying in dark room for 2 hours, in PACG group, the intraocular pressure (IOP) in 10 of 22 eyes raised more than 1.07 kPa (1 kPa = 7.5 mmHg), and in 12 eyes less than 1.07 kPa or had no changes; appositional angle closure was found by Goldmann gonioscopy in 8 eyes; 3 eyes in two quadrants, 5 eyes in more than two quadrants; the appositional angle closure was found by ultrasound biomicroscopy in 15 eyes; 3 eyes in one quadrant, 5 eyes in two quadrants, 7 eyes in more than two quadrants. In the control group, IOP raised more than 1.07 kPa in 3 eyes. There was no appositional angle closure found in the control group. With the appositional angle closure as a positive diagnostic criterion, the sensitivity of the traditional test and UBM dark room test was 31.8% and 68.2%, respectively. With statistic chi-square test, there is a statistically significant difference between the two methods (P < 0.05). CONCLUSIONS: The sensitivity of UBM dark room provocative test is higher than that of the traditional one. The specificity of both methods is 100%. UBM dark room provocative test elevates the sensitivity and specificity of traditional dark room test, and reduces the false negative or positive rate in screening PACG, that is helpful to its accurate diagnosis.

Glaucoma, Angle-Closure↗
PubMed1998

Gamma-glutamyl cysteine synthetase up-regulates glutathione and multidrug resistance-associated protein in patients with chemoresistant epithelial ovarian cancer.

Cellular detoxification, such as that mediated by the glutathione (GSH) system, is involved in the metabolism of various cytotoxic agents. Little is known, however, about the clinical relevance of cellular detoxification in chemoresistance. To elucidate the relevance of the GSH system to the resistance to chemotherapy observed in patients with ovarian cancer, we assayed the expression of mRNA encoded by the multidrug resistance-associated protein (MRP) and gamma-glutamyl cysteine synthetase (gamma-GCS) genes, as well as the level of GSH protein in 32 patients with epithelial ovarian cancer after chemotherapy. Tumors of 14 of the 32 patients responded to chemotherapy, whereas 18 did not. The levels of MRP and gamma-GCS transcripts in tumors from nonresponders were each about 2-fold higher than in responders. In contrast, the level of GSH did not differ between the two groups. We observed coordinated expression of gamma-GCS mRNA and GSH protein levels, and between gamma-GCS and MRP in nonresponders, but not in responders. Expression of MRP-encoded mRNA did not correlate to GSH level, however, in either group. These results suggest that gamma-GCS may up-regulate GSH and MRP expression in tumors unresponsive to chemotherapeutic agents, and that the GSH system may be involved in the mechanism of chemoresistance in ovarian cancer.

ATP-Binding Cassette Transporters↗
PubMed1997

Selection of peptides that functionally replace a zinc finger in the Sp1 transcription factor by using a yeast combinatorial library.

We have developed a strategy for the identification of peptides able to functionally replace a zinc finger domain in a transcription factor. This strategy could have important ramifications for basic research on gene regulation and for the development of therapeutic agents. In this study in yeast, we expressed chimeric proteins that included a random peptide combinatorial library in association with two zinc finger domains and a transactivating domain. The library was screened for chimeric proteins capable of activating transcription from a target sequence in the upstream regulatory regions of selectable or reporter genes. In a screen of approximately 1.5 x 10(7) transformants we identified 30 chimeric proteins that exhibited transcriptional activation, some of which were able to discriminate between wild-type and mutant DNA targets. Chimeric library proteins expressed as glutathione S-transferase fusions bound to double-stranded oligonucleotides containing the target sequence, suggesting that the chimeras bind directly to DNA. Surprisingly, none of the peptides identified resembled a zinc finger or other well-known transcription factor DNA binding domain.

Amino Acid Sequence↗
PubMed1997

The use of exfoliative cell samples to map clonal genetic alterations in the oral epithelium of high-risk patients.

Although it is widely accepted that clonal genetic alterations are an essential component of tumor progression, little is known of the distribution of such changes in high-risk lesions or how such clones are altered over time. We explored the feasibility of using exfoliative cells collected by scraping the mucosal surface to detect allelic loss in oral lesions of 22 patients (14 squamous cell carcinomas, 2 carcinomas in situ, and 6 dysplasias). The data show that the patterns of allelic loss observed in these samples closely represent those observed in biopsies of the same region. Furthermore, early indications are that this approach can be used to detect recurrent outgrowth of clones of altered cells in patients after therapy.

Adult↗
PubMed1997

Essential role of the first intron in the transcription of hsp90beta gene.

The human HSP90 gene family contains introns. There are two typical heat shock elements (HSE) in the first intron of human hsp90beta gene. As detected by chloramphenicol acetyl transferase (CAT) reporter activity assays, the HSE-containing intron is essential in maintaining high constitutive expression and is critical for heat shock inducibility of the human hsp90beta gene. Cellular heat shock factor 1 (HSF 1) shows much higher binding affinity toward the intronic HSEs in comparison to an atypical HSE in the 5' flanking sequence. Novel initiation sites found in the first intron probably also contribute to constitutive and heat-inducible expression of the hsp90beta gene in Jurkat cells.

Chloramphenicol O-Acetyltransferase↗
PubMed1997

Expression, purification, mass spectrometry, crystallization and multiwavelength anomalous diffraction of selenomethionyl PvuII DNA methyltransferase (cytosine-N4-specific).

The type II DNA-methyltransferase (cytosine N4-specific) M.PvuII was overexpressed in Escherichia coli, starting from the internal translation initiator at Met14. Selenomethionine was efficiently incorporated into this short form of M.PvuII by a strain prototrophic for methionine. Both native and selenomethionyl M.PvuII were purified to apparent homogeneity by a two-column chromatography procedure. The yield of purified protein was approximately 1.8 mg/g bacterial paste. Mass spectrometry analysis of selenomethionyl M.PvuII revealed three major forms that probably differ in the degree of selenomethionine incorporation and the extent of selenomethionine oxidation. Amino acid sequencing and mass spectrometry analysis of selenomethionine-containing peptides suggests that Met30, Met51, and Met261 were only partially replaced by selenomethionine. Furthermore, amino acid 261 may be preferentially oxidized in both native and selenomethionyl form. Selenomethionyl and native M.PvuII were crystallized separately as binary complexes of the methyl donor S-adenosyl-L-methionine in the monoclinic space group P2(1). Two complexes were present per asymmetric unit. Six out of nine selenium positions (per molecule), including the three that were found to be partially substituted, were identified crystallographically.

Amino Acid Sequence↗
PubMed1997

Structure of pvu II DNA-(cytosine N4) methyltransferase, an example of domain permutation and protein fold assignment.

We have determined the structure of Pvu II methyltransferase (M. Pvu II) complexed with S -adenosyl-L-methionine (AdoMet) by multiwavelength anomalous diffraction, using a crystal of the selenomethionine-substituted protein. M. Pvu II catalyzes transfer of the methyl group from AdoMet to the exocyclic amino (N4) nitrogen of the central cytosine in its recognition sequence 5'-CAGCTG-3'. The protein is dominated by an open alpha/beta-sheet structure with a prominent V-shaped cleft: AdoMet and catalytic amino acids are located at the bottom of this cleft. The size and the basic nature of the cleft are consistent with duplex DNA binding. The target (methylatable) cytosine, if flipped out of the double helical DNA as seen for DNA methyltransferases that generate 5-methylcytosine, would fit into the concave active site next to the AdoMet. This M. Pvu IIalpha/beta-sheet structure is very similar to those of M. Hha I (a cytosine C5 methyltransferase) and M. Taq I (an adenine N6 methyltransferase), consistent with a model predicting that DNA methyltransferases share a common structural fold while having the major functional regions permuted into three distinct linear orders. The main feature of the common fold is a seven-stranded beta-sheet (6 7 5 4 1 2 3) formed by five parallel beta-strands and an antiparallel beta-hairpin. The beta-sheet is flanked by six parallel alpha-helices, three on each side. The AdoMet binding site is located at the C-terminal ends of strands beta1 and beta2 and the active site is at the C-terminal ends of strands beta4 and beta5 and the N-terminal end of strand beta7. The AdoMet-protein interactions are almost identical among M. Pvu II, M. Hha I and M. Taq I, as well as in an RNA methyltransferase and at least one small molecule methyltransferase. The structural similarity among the active sites of M. Pvu II, M. Taq I and M. Hha I reveals that catalytic amino acids essential for cytosine N4 and adenine N6 methylation coincide spatially with those for cytosine C5 methylation, suggesting a mechanism for amino methylation.

Amino Acid Sequence↗
PubMed1997

DNA containing 4'-thio-2'-deoxycytidine inhibits methylation by HhaI methyltransferase.

4'-Thio-2'-deoxycytidine was synthesized as a 5'- protected phosphoramidite compatible with solid phase DNA synthesis. When incorporated as the target cytosine (C*) in the GC*GC recognition sequence for the DNA methyltransferase M. HhaI, methyl transfer was strongly inhibited. In contrast, these same oligonucleotides were normal substrates for the cognate restriction endonuclease R. HhaI and its isoschizomer R. Hin P1I. M. HhaI was able to bind both 4'-thio-modified DNA and unmodified DNA to equivalent extents under equilibrium conditions. However, the presence of 4'-thio-2'-deoxycytidine decreased the half-life of the complex by >10-fold. The crystal structure of a ternary complex of M. HhaI, AdoMet and DNA containing 4'-thio-2'-deoxycytidine was solved at 2.05 A resolution with a crystallographic R-factor of 0.186 and R-free of 0.231. The structure is not grossly different from previously solved ternary complexes containing M. HhaI, DNA and AdoHcy. The difference electron density suggests partial methylation at C5 of the flipped target 4'-thio-2'-deoxycytidine. The inhibitory effect of the 4'sulfur atom on enzymatic activity may be traced to perturbation of a step in the methylation reaction after DNA binding but prior to methyl transfer. This inhibitory effect can be partially overcome after a considerably long time in the crystal environment where the packing prevents complex dissociation and the target is accurately positioned within the active site.

DNA↗
PubMed1997

Crystal structure of human UP1, the domain of hnRNP A1 that contains two RNA-recognition motifs.

BACKGROUND: Heterogeneous nuclear ribonucleoprotein (hnRNP) A1 is one of the most abundant core proteins of hnRNP complexes in metazoan nuclei. It behaves as a global regulator of alternative pre-mRNA splicing by antagonizing the activities of several serine/arginine-rich splicing factors (SR proteins), resulting in the activation of distal alternative 5' splice sites and skipping of optional exons. Purified hnRNP A1 has nucleic acid annealing activity. The protein also shuttles continuously between the nucleus and the cytoplasm, a process mediated by signals within its C-terminal glycine-rich domain. The N-terminal region of human hnRNP A1, termed unwinding protein 1 (UP1), contains two RNA-recognition motifs (RRMs), RRM1 and RRM2. Understanding the structural elements by which hnRNP A1 interacts with RNA will have broad implications for studies of RNA processing. RESULTS: The crystal structure of UP1 has been determined to 1.9 A resolution. Each RRM independently adopts the characteristic RRM fold, consisting of a four-stranded antiparallel beta-pleated sheet and two alpha helices packed on one side of the beta sheet. The two RRMs are antiparallel and held in close contact, mainly by two Arg-Asp ion pairs. As a result, the two four-stranded beta sheets are brought together to form an extended RNA-binding surface. A segment of the linker connecting the two RRMs is flexible in the absence of bound RNA, but the general location of the linker suggests that it can make direct contacts with RNA. Comparison with other RRM structures indicates that a short 310 helix, found immediately N-terminal to the first beta strand in RRM1, may interact with RNA directly. CONCLUSIONS: The RRM is one of the most common and best characterized RNA-binding motifs. In certain cases, one RRM is sufficient for sequence-specific and high affinity RNA binding; but in other cases, synergy between several RRMs within a single protein is required. This study shows how two RRMs are organized in a single polypeptide. The two independently folded RRMs in UP1 are held together in a fixed geometry, enabling the two RRMs to function as a single entity in binding RNA, and so explaining the synergy between the RRMs. The UP1 structure also suggests that residues which lie outside of the RRMs can make potentially important interactions with RNA.

Amino Acid Sequence↗