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Biomedical subjects

X Yang

Publications and source records attributed to X Yang.

At least 1,153 records · Page 64Linked to original sources
PubMed1987

Comparison of the thrombolytic efficacy of defibrase and urokinase on canine coronary artery thrombosis and the mechanism of urokinase-induced hemorrhage.

The thrombolytic efficacy of defibrase (DF) and urokinase (UK) was evaluated and compared in a canine model in which left circumflex coronary artery (LCX) thrombus formation was initiated by electrical stimulation (150 UA, DC) of the arterial intimal surface via an implanted copper wire electrode. Forty-eight mongrel dogs were equally divided into 8 groups: six groups for both intravenous (iv) and intracoronary (ic) infusion of DF, UK and normal saline 30 min after complete obstruction by a LCX thrombus, the remaining two groups for iv infusion DF and UK 360 min after occlusion. Results showed that in the control groups no LCX recanalization after infusion occurred, but all the treated groups recanalized when drug infusion started 30 min after occlusion. Thrombus wet weight and infarct size were much higher in the control group. No significant differences were found between treated groups except that the recanalizing speed was fastest by ic UK with the highest occurrence rate of reperfusion arrhythmia. For 6-hour-old thrombi, DF was more effective than UK for recanalization. Thrombus wet weight and infarct size were lower in the recanalized dogs. Both agents reduced plasma plasminogen and fibrinogen significantly but serious incision bleeding was only found in the UK group. In order to study the mechanism underlying UK-induced hemorrhage, we observed the influences of UK and DF on blood coagulation factors in another 12 dogs. Results showed that DF only reduced factor 1 while UK additionally reduced coagulation factors 2, 7, 8 and 10, indicating that the non-selective depletive effect on coagulation factors may be one of the mechanisms of UK-induced hemorrhage. We conclude that both DF and UK can lyse fresh coronary thrombi, DF was more effective than UK on lysing older thrombi, considering its convenient use and less frequency of side effects, DF is therefore considered a more promising agent clinically.

Animals↗
PubMed1984

Depolarizing responses of L-type external horizontal cells in the goldfish retina under intense chromatic background.

The external horizontal cells (EHCs) in the goldfish retina are known to respond with hyperpolarization to monochromatic flashes of all wavelengths. From their spectral responses they are referred to as "monophasic" horizontal cells. However, when the retina is exposed to an intense red background, EHCs showed a depolarizing response to flashes of intermediate and short wavelength of moderate intensity. The depolarizing component is presumably driven by the input from green-sensitive cones.

Animals↗
PubMedDate not supplied

Mediator caused induction of a human bradykinin B1 receptor minigene: participation of c-Jun in the process.

The bradykinin B1 receptor (BKB1R) gene is expressed in selected tissues such as lung and kidney. In these tissues it is expressed at a very low level until induced by inflammatory mediators. Our aim has been to understand the mechanism of this regulatory process. A human BKB1R minigene was constructed. It contained a 1.8 kb promoter, the entire exon I, 1.5 kb of intron I, the entire exon II and intron II, and the luciferase gene as a reporter. Transient transfection of the minigene into SV40-transformed IMR90 cells (IMRSV) resulted in a promoter activity which was activated by the mediators, lipopolysaccharide and (LPS) desArg(10)-kallidin. In contrast, these mediators did not induce the activity of the 1.8 kb promoter construct alone. Thus, motifs exclusive of the promoter such as 5'-UTR and/or intron regions are required for mediator-induced expression of this gene. Promoter activities of both the minigene and the 1.8 kb promoter construct were enhanced in a dose-dependent manner upon cotransfection with c-Jun. Furthermore, cotransfecting c-Jun with the minigene achieved the maximal promoter activity with no further increase in response to mediators. Conversely, the induction of the minigene promoter activity by mediators was abolished upon cotransfection with a dominant negative mutant of c-Jun. Other experiments suggest that multiple AP-1 sites are interactive with the c-Jun upregulation of this gene. Taken together, these results point to c-Jun as a key intermediary in the activation of the expression of this gene by mediators. However, participation of motifs outside of the promoter are necessary to obtain this inducible expression.

Exons↗
PubMedDate not supplied

p53 down-regulates human bradykinin B1 receptor gene expression.

The tumor suppressor, p53, has been shown to transcriptionally activate or silence a number of target genes. As an activator, p53 relies on its specific consensus sequence within the promoter. It is not clear whether p53 requires a specific DNA binding site in its action as a gene repressor. This report demonstrates that the human BKB1R gene is a p53 target. Expression of p53 in transiently transfected SV40-transformed IMR90 cells strongly suppressed luciferase reporter activity driven by a 1.8 kb BKB1R promoter as well as its minigene. These down-regulations were p53 dose-dependent. p53 reduced both basal and induced promoter activities of the minigene. Expression of p53 abolished the inducibility of the minigene. Induction of endogenous p53 expression by etoposide also inhibited promoter activity and minigene inducibility. Replacing the region containing both the putative p53 binding site and the TATA-box with a basal adenovirus promoter in the 1.8 kb promoter construct did not prevent p53 from inhibiting BKB1R promoter activity. Thus suppression by p53 is not mediated by competition with the TATA-binding protein and is not through interaction with the putative p53-binding site. p53 also does not appear to suppress BKB1R gene expression through interaction with c-Jun which functions in the inducibility of this gene [Yang et al., 2001].

Binding Sites↗
PubMedDate not supplied

Scar skin and dapple apple viroids are seed-borne and persistent in infected apple trees.

The closely related apple scar skin viroid (ASSV) and dapple apple viroid (DAV) were identified in whole seeds from infected pome fruits by hybridization of extracted nucleic acids with a 32P-labelled ASSV cRNA probe. Viroid amounts were greater in seed coats and subcoats than in seed cotyledons and embryos. ASSV or DAV was also detected in nucleic acid extracts from infected seeds, cotyledons and embryos by reverse transcription/polymerase chain reaction with viroid-cDNA-specific primers followed by Southern blot hybridization analysis of the amplified products with an ASSV cRNA probe. These results indicate that ASSV and DAV are seed-borne. ASSV and DAV were also found in the anthers, petals, receptacles, leaves, bark and roots of infected trees. The results suggest that viroid-infected trees constitute potential sources of the viroid in field spread. ASSV and DAV infections have been observed sporadically in commercial orchards in the United States and Canada and the infected trees have been eliminated. The use of viroid-free sources of seeds, seedlings, rootstocks and budwood should greatly reduce the risk of the future spread of the viroid.

Animals↗
PubMedDate not supplied

In situ localization of progesterone receptors in normal mouse mammary glands: absence of receptors in the connective and adipose stroma and a heterogeneous distribution in the epithelium.

In normal mammary glands of both rodents and humans, progesterone promotes the proliferation of epithelial cells and several lines of evidence suggest that this action of progesterone may be mediated by progesterone receptor (PR). It is well established that normal mammary development involves a complex interplay between the epithelial cells and the surrounding fatty stroma. Furthermore, during mammary development, there is a change in both the relative proportion of epithelial cells and the steady-state levels of PR. Therefore, towards understanding the precise role of PR in mammary development, we have generated a highly sensitive antibody against mouse PR and examined its pattern of localization. Immunoreactive PR was detected only in the epithelial cells of the ducts while both the adipose and fibrous stroma surrounding these ducts were receptor negative. Similarly, PR mRNA was also associated only with the ductal epithelial cells. Approximately only 45-50% of the ductal cells were receptor positive and this distribution remained unchanged whether or not the tissues had been exposed to estrogen, suggesting that they may represent a distinct subpopulation. The potential significance of these findings to mammary development is discussed.

Adipose Tissue↗
PubMedDate not supplied

Intravascular MR-monitored balloon angioplasty: an in vivo feasibility study.

PURPOSE: To develop a new method for monitoring balloon angioplasty by using an intravascular magnetic resonance (MR) imaging technique. MATERIALS AND METHODS: Nine New Zealand White rabbits were used: seven for technique refinement, including surgery, device insertion, stenosis creation, and MR protocol development; and two for the final MR imaging of the balloon angioplasty. The in vivo experimental method involved insertion of a catheter antenna and a balloon catheter, via femoral arteriotomies bilaterally, into the target site of the upper abdominal aorta, where a stenosis was artificially created by binding a plastic cable tie. Then, the entire process of the dilation of the stenosis with balloon inflation was monitored under MR fluoroscopy. RESULTS: Catheter insertions were successful, and a 5-mm-long stenosis of the aorta was produced in all nine rabbits. Eight complete balloon angioplasty procedures were satisfactorily monitored and recorded, showing clearly the stenosis of the aorta at the beginning of the procedure, the dilation of the stenosis during the balloon inflation, and the complete opening of the stenosis after balloon dilation. CONCLUSION: Preliminary results of in vivo balloon angioplasty monitored with intravascular MR imaging are presented. MR fluoroscopy, based on the intravascular MR imaging technique, may represent a potential alternative to x-ray fluoroscopy for guiding interventional treatment of cardiovascular diseases.

Angioplasty, Balloon↗
PubMedDate not supplied

Functions of mammalian Smad genes as revealed by targeted gene disruption in mice.

The Smad genes are the intracellular mediators of TGF-beta signals. Targeted mutagenesis in mice has yielded valuable new insights into the functions of this important gene family. These experiments have shown that Smad2 and Smad4 are needed for gastrulation, Smad5 for angiogenesis, and Smad3 for establishment of the mucosal immune response and proper development of the skeleton. In addition, these experiments have shown us the importance of gene dosage in this family, as several of its members yielded haploinsufficiency phenotypes. These include gastrulation and craniofacial defects for Smad2, accelerated wound healing for Smad3, and the incidence of gastric cancer for Smad4. Combinatorial genetics has also revealed functions of Smads in left/right isomerism and liver development.

Animals↗
PubMedDate not supplied

Prevalence and correlates of sexual dysfunction among young adult married women in rural China: a population-based study.

The study investigates prevalence of sexual dysfunction (SD), sexual satisfaction and their correlates in the rural female population in China. An anonymous cross-sectional study was carried out in a random sample of 1178 married of age 20-39 years in Dengfeng County, Henan, China. The prevalence of having at least one SD was 43 and 38% of the respondents were satisfied with their sexual life; 64.0% thought that sex was not important to them; and 85.7% believed that they do not have adequate sex-related knowledge. Having SD and high sexual satisfaction were associated with high mental health or vitality quality of life scores and better perceived health status. Other independent predictors of SD included sociodemographic variables, biological variables, life style factors and masturbation. It is concluded that SD was prevalent among the studied women and were associated with mental health. The sexual health among married women needs to be improved in rural China.

Adult↗
PubMedDate not supplied

Co-occurrence of sexual dysfunction within young married couple dyads living in rural China: a population-based study.

A total of 298 randomly selected married couple dyads in rural China were studied. Sexual dysfunction (SD) was reported by 84 (28.2%) of the husbands and 136 (45.6%) of the wives. Co-occurrence of SD was reported by 51 of the married couples; hence, SD co-occurred in the spouses of 60.7% of the husbands with SD and 37.5% of wives reporting SD. Pain during intercourse but not other SD of the wives was associated with SD of the husbands. Men's SD including inability to achieve orgasm, finding sex not pleasurable and lack of interest in sex, but not premature ejaculation or erectile dysfunction, were associated with the presence of SD among the wives. Decision-making control on sexual matters, communication between the spouses on sexual problems, the seeking of professional help, perceived adequacy of sexual knowledge as well as mental health and vitality quality of life indices were associated with co-occurrence of SD within the couple dyads.

Adult↗
PubMedDate not supplied

A new approach to detect QRS complexes based on a histogram and genetic algorithm.

A new approach, based on a histogram and genetic algorithm (GA), has been developed to rapidly and reliably detect QRS complexes of the ECG curve. Here, the new approach is described and the principle of the histogram and GA is explained. The results of detection of QRS complexes using the new method are given. Additionally, as an example of its novel application, the P-wave and f-wave (when atrial fibrillation is absent and present, respectively) are extracted easily and efficiently from the ECG curve using the method.

Algorithms↗
PubMedDate not supplied

Arsenic trioxide induces apoptosis in cisplatin-sensitive and -resistant ovarian cancer cell lines.

Arsenic trioxide (As(2)O(3)), has been used for centuries in traditional Chinese medicine; it has considerable efficacy in the treatment of relapsed acute promyelocytic leukemia, inducing partial differentiation and promoting apoptosis of malignant promyelocytes. Although a number of studies have demonstrated that As(2)O(3) has potent activity against cell growth in a series of leukemia cell lines, little information is available regarding this compound's effect on cell growth in solid tumor cell lines. In this study, we investigated the effects of As(2)O(3)in vitro on ovarian cancer cell lines sensitive (3AO) and resistant (3AO/CDDP) to cisplatin. The 3-(4,5-dimethy-thiazoyl-2-yl)-2,5-diphenyl-tetrazolium bromide assay was used to evaluate cytotoxicity. Flow cytometric analysis was used to determine the apoptosis, cell cycle distribution. We clearly demonstrated that As(2)O(3) induced cell apoptosis and inhibition of cell growth in both the cell lines. Furthermore, we identified that As(2)O(3)-induced apoptosis involved Fas pathway. As(2)O(3) is an active agent against ovarian cancer cells and could be effective in the clinical treatment of ovarian cancer.

Apoptosis↗
PubMedDate not supplied

Effects of dichloroisoproterenol on macromolecular synthesis and differentiation in Tetrahymena vorax.

The effect of dichloroisoproterenol on macrostomal cell formation in Tetrahymena vorax was examined and the drug was found to be 50% inhibitory at a concentration of 88 microM. Cellular uptake and incorporation of a variety of radiolabelled precursors was monitored in the presence of dichloroisoproterenol. The results demonstrate a strong, concentration-dependent inhibitory effect on RNA and protein biosynthesis, with a lesser inhibition observed for lipid biosynthesis. These data indicate that dichloroisoproterenol's reported effects on vacuole formation and processing in Tetrahymena are nonspecific with regard to phagocytic processes, but result from a general suppression of macromolecular synthesis.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Disturbance of the determination of germinal and somatic nuclei by heat shock in Paramecium caudatum.

During conjugation of Paramecium caudatum, nuclear determination occurs soon after the third postzygotic division: one of the four anterior nuclei becomes the micronucleus and the remaining three degenerate, while four posterior nuclei differentiate into macronuclear anlagen. Macronuclear differentiation is supposed to be dependent on a cytoplasmic differentiation factor. In this study, postzygotic cells were subjected to heat shock for 30 min and nuclear changes were observed by staining with carbol fuchsin solution. When heat shock was initiated during the period from metaphase to telophase of the third postzygotic division, cells showed an excess of macronuclear anlagen and were typically amicronucleate. Abnormal nuclear localization around the end of the third (last) postzygotic division may explain the origin of these kinds of cells. A similar phenomenon appeared after treatment with actinomycin D or emetine. Since heat shock did not inhibit macronuclear differentiation but destroyed the formation of micronuclei, some factor(s) probably plays an essential role in nuclear determination, especially in the protection of the micronuclei.

Animals↗