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Biomedical subjects

D Li

Publications and source records attributed to D Li.

At least 271 records · Page 15Linked to original sources
PubMed2000

Modulation of myocardial SOD and iNOS during ischemia-reperfusion by antisense directed at ACE mRNA.

Renin-angiotensin system (RAS) is involved in the regulation of superoxide dismutase (SOD) and nitric oxide (NO) equilibrium, and its modulation protects hearts from ischemic dysfunction. We examined the effect of a new antisense-oligodeoxynucleotides (AS-ODNs) directed at ACE mRNA on SOD and iNOS expression during myocardial ischemia. Sprague-Dawley rats were treated with saline, AS-ODNs, or inverted-ODNs (IN-ODNs), given with liposome DOTAP/DOPE. Hearts were excised and subjected to 25 min of ischemia followed by 30 min of reperfusion. Ischemia-reperfusion in saline-treated hearts resulted in a decrease in the expression of SOD and an increase in the expression of inducible NOS (iNOS) genes concurrently with myocardial dysfunction. AS-ODNs, but not IN-ODNs, protected hearts against functional deterioration, and upregulated SOD expression and inhibited the expression of iNOS. ACE protein expression was decreased in the rat hearts of the AS-ODNs-treated group, but not in the IN-ODNs group. Thus manipulation of RAS with AS-ODNs directed at ACE mRNA can ameliorate cardiac dysfunction and modulate expression of SOD and iNOS at genomic level.

Animals↗
PubMed2000

Effect of polypeptide CH50 on macrophage activation in vivo and anti-tumor function.

The main features of CH50, a recombinant polypeptide of human fibronectin, activating macrophages in vivo and its anti-tumor function were investigated. After injection of CH50 and(or) transfection of IFN-gamma gene in vivo, several kinds of factors produced by macrophages were determined and the growth of tumor in vivo was measured. CH50 could enhance the production of such factors as NO, TNF and IL-1 by macrophages, but the activation of macrophages was relatively slow when CH50 was used in vivo alone. CH50 and IFN-gamma could synergistically activate macrophages rapidly in vivo no matter whether the injection of CH50 or the transfection of IFN-gamma gene was performed first. Injection of CH50 alone inhibited the formation of tumor nodes in a dose-dependent manner. Low dose of CH50 could strongly inhibit the formation of tumor nodes less than 1 mm, while high dose of CH50 could inhibit those more than 1 mm. A stronger inhibition on the growth of tumor in vivo was obtained by the synergistic effect of CH50 and IFN-gamma. CH50 and IFN-gamma, as double-signal factors for activation of macrophages, will be potentially useful in tumortherapy.

Animals↗
PubMed2000

Construction of eukaryotic expressing vector pCH503 of CH50 and its chemotaxis and anti-tumor function by expression in vivo in mice.

An eukaryotic expressing vector that expresses CH50, a recombinant polypeptide of human fibronectin, in mice was constructed, and its chemotactic and anti-tumor function by in vivo gene transfection was investigated. The plasmid was constructed by recombination techniques. The cDNA fragment coding CH50 polypeptide from a prokaryotic expressing vector of CH50 was ligated with 5'-terminal noncoding region and coding region of signal peptide of mouse IFN-gamma cDNA at 5' side and 3'-terminal noncoden region of human FN cDNA at 3' side. The recombinant cDNA was inserted into plasmid pREP8. The resulted expressing plasmid was designated as pCH503. The macrophages transfected with pCH503 in vivo and cultured in vitro could produce CH50. The expressed product was identified by heparin-affinity chromatography and SDS-PAGE. By counting and Giemsa-staining of coeliac cells and histotomy and staining of muscle tissue, the chemotaxis on immune cells was observed after transfection of pCH503 either in peritoneal cavity or in muscle. The inhibition of gene transfection of pCH503 on melanoma was observed in mice. The number of melanoma nodes in mice was reduced by 50%-60% after coeliac transfection with pCH503. The pCH503, an eukaryotic expressing vector of CH50, can express in vivo in mice. The transfection of pCH503 in vivo has the chemotaxis on immune cells and can inhibit the formation of tumor nodes, suggesting that plasmid pCH503 is potentially useful in combined treatment of tumor.

Animals↗
PubMed2000

Augmentation of recombinant CH50 polypeptide on the function of macrophages of mice during chemotherapy.

The immunosuppressive model of mice was made by intraperitoneal injection of cyclophosphamide. The effect of CH50, a recombinant polypeptide of human fibronectin, on macrophages of mice was observed. The results showed that continuous intraperitoneal injection of CH50 could prevent the reduction of the number of monocytes in periphery blood and abdominal cavity by chemotherapeutic agents, enhance the metabolic activity and cytotoxicity of macrophages and augment the proliferation of splenocytes. The results suggested that CH50 is a product which could be used to improve the efficacy of chemotherapy of tumors.

Adjuvants, Immunologic↗
PubMed2000

Carvedilol prevents epinephrine-induced apoptosis in human coronary artery endothelial cells: modulation of Fas/Fas ligand and caspase-3 pathway.

BACKGROUND: Several studies have shown that carvedilol, a multiple action neurohumoral antagonist, reduces mortality in patients with congestive heart failure (CHF). In addition to being a beta-adrenoceptor antagonist, carvedilol is a potent antioxidant. Since there is evidence for elevation of catecholamine levels in plasma and coronary artery endothelial cell injury in CHF, the present study was designed to test the hypothesis that carvedilol inhibits epinephrine-induced apoptosis, and the inhibitory effect is mediated by modulation of Fas, Fas ligand (FasL) and caspase-3 pathway, in cultured human coronary artery endothelial cells (HCAECs). METHODS AND RESULTS: HCAECs were exposed to epinephrine alone, carvedilol + epinephrine, or atenolol + epinephrine for 24 h. Epinephrine increased the number of apoptotic cells, measured by in situ nick end-labeling staining (from 4.2 +/- 1.3% to 28.6 +/- 6.0%, P < 0.01, n = 6) and by DNA laddering on agarose gel electrophoresis. Epinephrine also increased Fas and FasL protein expression (P < 0.01 vs. control, n = 6), and activated intracellular protease caspase-3 (P < 0.01 vs. control, n = 6). These effects of epinephrine were completely inhibited by carvedilol. Atenolol in equimolar concentration also attenuated epinephrine-mediated effects, but the effects of atenolol were less marked than those of carvedilol (P < 0.01). To explore the basis of differential effects of carvedilol and atenolol, effects of these agents on epinephrine-induced lipid peroxidation was measured. Lipid peroxidation was completely blocked by carvedilol, whereas equimolar concentration of atenolol had much less (P < 0.05) effect. CONCLUSION: Epinephrine induces apoptosis in HCAECs, and this effect is associated with activation of Fas-FasL and caspase-3 signal transduction pathway. Carvedilol can, more effectively than atenolol, inhibit these effects of epinephrine. The potent antioxidant effect of carvedilol is probably responsible for the superior effect.

Antioxidants↗
PubMed2000

Triterpenoids from Tripterygium wilfordii.

The extract (T(II)) of Tripterygium wilfordii Hook f. afforded four triterpenoids: wilforic acid D (3beta,24-epoxy-2alpha-hydroxy-24R*-ethoxy-29-friedelanoic acid); (E) 3beta,24-epoxy-2-oxo-3alpha-hydroxy-29-friedelanoic acid; (F) 2beta-hydroxy-3-oxo-friedelan-29-oic acid; 29-hydroxy-3-oxo-olean-12-en-28-oic acid and 17 known triterpenoids. Their structures were established on the basis of spectroscopic studies. In a bioactivity analysis, only the known dulcioic acid compound showed a significant inhibitory effect on cytokine production.

Immunosuppressive Agents↗
PubMed2000

Synthesis of 7alpha-hydroxy derivatives of regulatory oxysterols.

7alpha-Hydroxy derivatives of oxysterols are of considerable interest because of their possible involvement in regulation of cholesterol metabolism. This paper describes stereoselective syntheses and complete characterization of the 7alpha-hydroxy derivatives of four key oxysterols: 25-hydroxycholesterol, 27-hydroxycholesterol, 24(S)-hydroxycholesterol, and 24(S), 25-epoxycholesterol.

Bile Acids and Salts↗
PubMed2000

Type XV collagen in human colonic adenocarcinomas has a different distribution than other basement membrane zone proteins.

In situ carcinomas must penetrate their own basement membrane to be classified as invasive, and subsequently infiltrate surrounding connective tissue and cross vascular basement membranes to metastasize hematogenously. Accordingly, in many studies, integral basement membrane components, including type IV collagen, laminin, and heparan sulfate proteoglycan, have been localized in a spectrum of tumors to gain insight into their role in neoplasia. A number of recently identified extracellular matrix molecules and isoforms of the aforementioned proteins have been localized to the basement membrane zone, illustrating another level of biochemical heterogeneity in these structures. As the complexity of these matrices becomes more apparent, their roles in maintaining homeostasis and in tumor biology falls into question. Of the new group of collagens localized to the basement membrane zone, type XV was the first to be characterized (Cell Tissue Res, 286:493-505, 1996). This nonfibrillar collagen has a nearly ubiquitous distribution in normal human tissues via a strong association with basement membrane zones, suggesting that it functions to adhere basement membrane to the underlying stroma. To begin investigation of this protein in malignant tumors, we have localized type XV in human colonic adenocarcinomas and compared its distribution with that of type IV collagen and laminin. Collagens XV and IV and laminin were found in all normal and colonic epithelial, muscle, fat, neural, and vascular basement membrane zones, as shown previously. In moderately differentiated, invasive adenocarcinomas, laminin and type IV collagen were sometimes observed as continuous, linear deposits around some of the malignant glands, but more often they were seen in either discontinuous deposits or were completely absent. In contrast, type XV collagen was characterized as virtually absent from the basement membrane zones of malignant glandular elements in moderately differentiated tumors. Nevertheless there were also similarities; all 3 proteins were usually present in the stroma and adjacent vascular basement membrane zones surrounding invasive glands. The loss of type XV collagen from these malignant epithelial basement membrane zones and its increased interstitial expression suggests a role for this protein in the invasive process and the possibility that it may provide a sensitive indicator of tumor invasion.

Adenocarcinoma↗
PubMed2000

Children's experience of violence in China and Korea: a transcultural study.

OBJECTIVE: There were two aims: First, to compare children's rates of being battered in home, by peers, and by teachers among students between China and Korea, and second, to identify particular risk factors for such violence. METHODS: Children in grades four through six in Shanghai (238 cases) and Yanji (245 cases) in China and Seoul (248 cases) and Kimpo (241 cases) in Korea were surveyed by questionnaire method. They were asked to complete the Straus' Conflict Tactics Scale and their frequencies in the three situations respectively, and other demographic items. RESULTS: Family violence during the last 1 year was experienced in 70.6% (minor 42.2%; serious 22.6%) of the children in China and 68.9% (minor 9.4%; serious 51.3%) of those in Korea. Experience rates of violence by peers were 42.7% (minor 25.7%; serious 13.7%) in China and 26.0% (minor 11.5%; serious 14.3%) in Korea. Finally, rates of corporal punishment by teachers were 51.1% (minor 28.0%; serious 4.1%) in China and 62.0% (minor 8.8%; serious 43.8%) in Korea. The most important and common risk factor for violence in one situation was the presence of violence in another situation. CONCLUSIONS: The findings indicate that the differences in children's overall experience rates were not particularly striking. However, Korean children experienced more severe forms of violence from family members and from teachers. Findings of risk factors clearly imply that there are children vulnerable to violence from multiple sources.

Child↗
PubMed2000

Effect of acute and subchronic subcutaneous urocortin on blood pressure and food consumption in ob/ob mice.

Corticotropin-releasing factor and urocortin belong to a hypothalamic peptide family thought to be important in appetite regulation. The present study compared the appetite-suppressant effect of subcutaneous urocortin in obese mice to its cardiovascular effects. Acutely, urocortin (100 nmol/kg iv) reduced blood pressure and increased heart rate in urethane anesthetized nonobese mice; effects similar to those produced by subcutaneous urocortin (10 and 100 nmol/kg sc) in nonobese and ob/ob mice. Over this same dose range (10-100 nmol/kg sc), urocortin dramatically inhibited food consumption in the ob/ob mouse. To determine if the acute hypotensive effect of urocortin (10 nmol/kg sc) in the ob/ob mouse persisted after repeated urocortin administration, animals were pretreated for 3 days with urocortin (10 nmol/kg sc) or vehicle. Following urocortin pretreatment, urocortin-induced hypotension was similar to the effect in vehicle pretreated mice. However, urocortin-induced appetite suppression was reduced following 3 days of pretreatment with urocortin (10 nmol/kg sc) to ob/ob mice. These data suggest that the hypotensive and appetite-suppressant effects of urocortin are mediated by different mechanisms and tolerance to the hypotension did not readily occur in obese animals.

Animals↗
PubMed2000

Developmental expression of the Xenopus Nkx2-1 and Nkx2-4 genes.

The homeodomain transcription factor Nkx2-1 (TTF-1) plays an essential role in the development of the thyroid, lung and ventral forebrain. We report the cloning and developmental expression patterns of two Xenopus NK-2 genes, Nkx2-1 and Nkx2-4, that are closely related to Nkx2-1. These genes show readily distinguishable expression patterns during development. Similar to its orthologues in chicken and mouse, the Xenopus Nkx2-1 gene is expressed in the developing thyroid, lung, and ventral forebrain. In contrast, expression of Nkx2-4 is specifically localized to the ventral diencephalon.

Amino Acid Sequence↗
PubMed2000

Thalicosides A1-A3, minor cycloartane bisdesmosides from Thalictrum minus.

Three new cycloartane bisdesmosides, two of which are based on a new genin, were isolated from the above-ground parts of Thalictrum minus. Thalicosides A1-A3 (1-3) were characterized as 3-O-beta-D-galactopyranosyl-29-O-beta-D-glucopyranosyl-3beta,16beta++ +, 29-trihydroxy-22(S),25-epoxycycloartane (1); 3-O-alpha-L-arabinopyranosyl-29-O-beta-D-glucopyranosyl-3beta,1 6beta, 29,22(S)-tetrahydroxycycloart-24-ene (2); and 3-O-alpha-L-arabinopyranosyl-29-O-beta-D-glucopyranosyl-3beta,1 6beta, 29-trihydroxy-22(S),25-epoxycycloartane (3), respectively. The structural assignments of these new compounds were based on interpretation of spectroscopic data. Thalicoside A2 showed in vitro inhibition of the fungus Candida albicans and also activity against Staphylococcus aureus.

Anti-Bacterial Agents↗
PubMed2000

Sesquiterpene alkaloids from Tripterygium hypoglaucum and Tripterygium wilfordii: a new class of potent anti-HIV agents.

Five new sesquiterpene pyridine alkaloids [triptonines A (1) and B (2), and wilfordinines A (3), B (4), and C (5)] and two known compounds (peritassine A and hypoglaunine C) were isolated from Tripterygium hypoglaucum and a clinically used extract of Tripterygium wilfordii. The structures of 1-5 were elucidated by spectroscopic methods. The anti-HIV activity of 1, 2, and several related compounds was evaluated. Triptonine B (2) demonstrated potent anti-HIV activity with an EC(50) value of <0.10 microg/mL and an in vitro therapeutic index value of >1000.

Alkaloids↗
PubMed2000

Complete nucleotide sequence and infectious cDNA clone of the RNA1 of a Chinese isolate of broad bean wilt virus 2.

The nucleotide sequence of the RNA1 of broad bean wilt virus 2 (BBWV2) isolate B935 has been determined from overlapping cDNA clones. It contains 5956 nucleotides in length excluding the 3' terminal poly(A) tail and contains a single long open reading frame (ORF) of 5613 nucleotides extending from nucleotide 234 to 5846. A repeated motif has been found in the 5' non-coding region. The predicted polyprotein encoded by the long ORF is 1870 amino acid in length with a molecular weight of 210 K. Amino acid sequence comparisons between portions of the BBWV2 RNA1-encoded polyprotein and proteins encoded by several species in Comoviridae revealed the putative functions of BBWV2 RNA1-encoded proteins and the same general genetic organization as that of comoviruses and nepoviruses. Based on the determined sequence, full-length cDNA clone of RNA1 designated as pU1FL was constructed. Together with transcripts from full-length cDNA clone of RNA2 (pU2FL), transcripts from pU1FL infected Chenopodium quinoa successfully.

Amino Acid Motifs↗
PubMed2000

Transformation of rice with the Arabidopsis floral regulator LEAFY causes early heading.

Onset of flowering, or heading date, is an important agronomic trait of cereal crops such as rice and early-heading varieties are required for certain regions in which rice is cultivated. Since the floral control gene LEAFY from Arabidopsis can dramatically accelerate flowering in dictoyledonous plants, the usefulness of LEAFY for manipulating heading date in rice has been tested. Constitutive expression of LEAFY from the cauliflower mosaic virus 35S promoter caused early flowering in transgenic rice, with a heading date that was 26-34 days earlier than that of wild-type plants. Early flowering was accompanied by a small yield penalty and some panicle abnormality. These observations suggest that floral regulatory genes from Arabidopsis are useful tools for heading date improvement in cereal crops.

Arabidopsis↗
PubMed2000

Sociable and prosocial dimensions of social competence in Chinese children: common and unique contributions to social, academic, and psychological adjustment.

A sample of 6th-grade children (N = 470), initially aged 12 years, in Shanghai, People's Republic of China, participated in this longitudinal study. Data on children's sociability and prosocial orientation were collected from peer assessments. Information on indexes of adjustment was obtained from multiple sources. The results indicated that sociable and prosocial functions were 2 overlapping, but distinct, dimensions of social competence and had common as well as unique contributions to the prediction of adjustment in specific areas. Whereas prosocial orientation was mainly predictive of social and school adjustment and externalizing problems, sociability uniquely contributed to the prediction of internalizing problems and emotional adjustment. Finally, prosocial orientation and sociability might moderate the development of adjustment difficulties.

Achievement↗
PubMed2000

Parental warmth, control, and indulgence and their relations to adjustment in Chinese children: a longitudinal study.

A sample of children, initially 12 years old, in the People's Republic of China participated in this 2-year longitudinal study. Data on parental warmth, control, and indulgence were collected from children's self-reports. Information concerning social, academic, and psychological adjustment was obtained from multiple sources. The results indicated that parenting styles might be a function of child gender and change with age. Regression analyses revealed that parenting styles of fathers and mothers predicted different outcomes. Whereas maternal warmth had significant contributions to the prediction of emotional adjustment, paternal warmth significantly predicted later social and school achievement. It was also found that paternal, but not maternal, indulgence significantly predicted children's adjustment difficulties. The contributions of the parenting variables might be moderated by the child's initial conditions.

Adaptation, Psychological↗