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Jun Yang

Publications and source records attributed to Jun Yang.

At least 379 records · Page 21Linked to original sources
PubMed2002

Beacon-like immunoreactivity in the hypothalamus of Sprague-Dawley rats.

Distribution of the novel peptide beacon in the hypothalamus of Sprague-Dawley rats was examined by immunohistochemical methods. Beacon-immunoreactive (irBC) neurons were found in the paraventricular, supraoptic, and accessory neurosecretory nuclei, and intensely labeled fibers in the median eminence and infundibulo-pituitary stalk. Scattered cells and/or fibers were noted in the suprachiasmatic nucleus, arcuate nucleus, retrochiasmatic area, lateral and medial preoptic area, as well as anterior and lateral hypothalamic area. The wide distribution of irBC in the hypothalamus of Sprague-Dawley rats suggests that the peptide may influence, in addition to a proposed role in feeding, a multitude of biological activities associated with the hypothalamic-pituitary axis.

Animals↗
PubMed2002

Cell-cycle-dependent regulation of human aurora A transcription is mediated by periodic repression of E4TF1.

Human aurora A is a serine-threonine kinase that controls various mitotic events. The transcription of aurora A mRNA varies throughout the cell cycle and peaks during G(2)/M. To clarify the transcriptional mechanism, we first cloned the 1.8-kb 5'-flanking region of aurora A including the first exon. Transient expression of aurora A promoter-luciferase constructs containing a series of 5'-truncated sequences or site-directed mutations identified a 7-bp sequence (CTTCCGG) from -85 to -79 as a positive regulatory element. Electromobility shift assays identified the binding of positive regulatory proteins to the CTTCCGG element. Anti-E4TF1-60 antibody generated a supershifted complex. Furthermore, coexpression of E4TF1-60 and E4TF1-53 markedly increased aurora A promoter activity. Synchronized cells transfected with the aurora A promoter-luciferase constructs revealed that the promoter activity of aurora A increased in the S phase and peaked at G(2)/M. In addition, we identified a tandem repressor element, CDE/CHR, just downstream of the CTTCCGG element, and mutation within this element led to a loss of cell cycle regulation. We conclude that the transcription of aurora A is positively regulated by E4TF1, a ubiquitously expressed ETS family protein, and that the CDE/CHR element was essential for the G(2)/M-specific transcription of aurora A.

3T3 Cells↗
PubMed2002

Pancreatitis-associated ascitic fluid induces hepatocyte death independent of local cytokines.

INTRODUCTION: Kupffer-cell-derived cytokines mediate liver injury, yet macrophage pacification does not abolish hepatocyte injury. We undertook this study to examine the role of pancreatitis-associated ascitic fluid (PAAF) in liver injury. METHODS: Pathogen-free PAAF was perfused into healthy rat livers in situ for 60 min (n = 5, sham = 5, LPS = 5). AST, ALT, LDH, and TNF were measured in the effluent. Primary cultures of rat Kupffer cells or hepatocytes were treated with PAAF; AST, ALT, LDH, and TNF were measured and cell proliferation was determined by MTT assay. A hepatocyte human cell line (CCL-13) was treated with PAAF and apoptosis was measured by flow cytometry. RESULTS: Liver perfusion with PAAF induced a >15-fold increase in AST/ALT/LDH (P < 0.001 PAAF vs sham), but not in TNF. In vitro, Kupffer cell viability was sharply reduced by PAAF in a dose-dependent manner; however, 5% PAAF (50% viability) did not induce TNF production from Kupffer cells. PAAF induced a multifold increase in AST/ALT/LDH from fresh hepatocytes (P < 0.001 vs control), which was not attenuated by a protease inhibitor. The CCL-13 cell population was reduced to 15 +/- 2% of baseline by PAAF (P < 0.001 vs control), whereas elastase, trypsin, or TNF had no effect. PAAF increased the percentage of nonviable CCL-13 cells (78 +/- 4% vs 28 +/- 1%, P < 0.001 vs control). Neither protease inhibitor nor heat inactivation of PAAF altered this pattern of hepatocyte death. CONCLUSION: PAAF induces direct hepatocyte injury and death by heat-stable factors other than pancreatic enzymes but not via local production of Kupffer-cell-derived cytokines.

Acute Disease↗
PubMed2002

Effect of chronic hypoxia on contents of urotensin II and its functional receptors in rat myocardium.

The cyclic peptide urotensin II (UII) has recently been cloned in mammals and reported to constrict rat pulmonary arteries potently. An enhanced maximal response was shown in rats exposed to chronic hypoxia. The aim of this study was to investigate changes in plasma and myocardial UII levels and its receptor sites in crude sarcolemma of ventricles from chronic hypoxic rats. We observed that rats exposed to chronic hypoxia for 4 weeks developed pulmonary hypertension and right ventricular hypertrophy. Compared with controls, the UII content in hypoxic rats was increased by 97.5% (45.24 +/- 7.1 vs. 22.9 +/- 3.24pg/mg protein, P < 0.01) in the right ventricle and 33.2% (24.89 +/- 0.99 vs. 18.68 +/- 2.04pg/mg protein, P < 0.01) in the left ventricle, respectively. However, there was no significant difference in plasma (27.44 +/- 3.11 vs. 27.82 +/- 5.57pg/ml, P > 0.05) and lung tissue levels (34.03 +/- 4.63 vs. 33.74 +/- 4.06 pg/ mg protein, P > 0.05) between the control and hypoxic groups. The time course of the binding of [125I]UII to crude ventricular sarcolemma was specific and time dependent. Scatchard plot analysis of the data demonstrated that the maximal number of specific binding sites (Bmax) in both the right and left ventricles was upregulated in the hypoxic group. Moreover, Bmax in the right ventricular specimens was upregulated to a greater extent than in the left ventricle (increased by 114% and 25% in the right and left ventricles, respectively, compared with control group, P < 0.01). In contrast, the UII binding affinity in right and left ventricular membranes from hypoxic rats was decreased (the dissociation constant Kd) increased by 20% and 33%, respectively compared with controls, P < 0.01). These results indicate that UII may act as an autocrine and/or paracrine hormone rather than as a circulating hormone, playing important roles in the development of ventricular hypertrophy induced by chronic hypoxia, and that the pathophysiological significance of UII in pulmonary and cardiovascular alteration induced by chronic hypoxia deserves further investigation.

Animals↗
PubMed2002

Nicotinamide therapy protects against both necrosis and apoptosis in a stroke model.

BACKGROUND AND PURPOSE: Nicotinamide protects against brain damage in ischemia-reperfusion. However, the dosage and time of treatment require clarification. It is also not clear if nicotinamide can protect against both necrosis and apoptosis. METHODS: Dose-response and time-effect studies were designed. Transient focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) for 90 min. Different doses of nicotinamide were injected upon reperfusion. In time-effect studies, 500 mg/kg nicotinamide was administered at different times after the onset of reperfusion. Neurological finding scores were recorded. Infarct volumes were measured. RESULTS: In contrast to controls, neurological deficit scores and infarct volumes were greatly reduced by treatment with nicotinamide. The ED(50) of nicotinamide was 239+/-79 mg/kg (P=.95). It was found that nicotinamide injected during the first 6 h of reperfusion could effectively inhibit the development of brain damage. The optimal dose of nicotinamide was 500 mg/kg and gave a maximal response. CONCLUSIONS: Poly(ADP-ribose) polymerase (PARP) plays a key role in DNA repair in stroke. Excessive PARP activity consumes NAD leading to energy depletion and neuronal damage. As an inhibitor of PARP, nicotinamide promotes the supply of energy. The results suggest that early application of nicotinamide at a suitable dosage significantly ameliorates necrotic and apoptotic brain injury after focal ischemia-reperfusion.

Animals↗
PubMed2002

Galactosylated alginate as a scaffold for hepatocytes entrapment.

Galactose moieties were covalently coupled with alginate through ethylenediamine as the spacer for enhancing the interaction of hepatocytes with alginate. Adhesion of hepatocytes onto the galactosylated alginate (GA)-coated polystyrene (PS) surface showed an 18-fold increase as compared with that of the alginate-coated surface and it increased with an increase in the concentration of GA. The morphologies of attached hepatocytes were observed to spread out at the 0.15 wt% GA-coated PS surface while round cells were observed at the 0.5 wt% GA-coated PS surface. Inhibition of hepatocytes attachment onto the galactose-carrying PS-coated surface occurred with the addition of the GA into the hepatocyte suspension, indicating the binding of GA with hepatocytes via the patch of asialoglycoprotein receptors. Primary hepatocytes were entrapped in the GA/Ca2+ capsules (GAC). Higher cell viability and more spheroid formation of hepatocytes were obtained in the GAC than in the alginate/Ca2+ capsules (AC). Moreover, liver functions of the hepatocytes such as albumin secretion and urea synthesis in the GAC were improved in comparison with those in the AC.

Alginates↗
PubMed2002

Preparation of alginate/galactosylated chitosan scaffold for hepatocyte attachment.

Galactose-carrying lactobionic acid was covalently coupled with chitosan for determining hepatocyte specificity. Galactosylated chitosan (GC) was reacted with Ca-alginate (ALG) gel through the electrostatic interaction of carboxylic groups of alginate with amine groups of GC. Highly porous, three-dimensional sponge composed of ALG and GC was prepared to provide specific hepatocyte recognition signals and enhance the mechanical property of the ALG sponge. Observation of the sponge through scanning electron microscopy revealed that sponge was a highly porous microstructure with interconnected pores. Porosity and pore size of the sponge were greatly dependent on the content and molecular weight of GC, and freezing temperature. The mechanical property of the ALG/GC sponge was enhanced with an increase of the GC content. Spheroid formation and viability of hepatocytes of the ALG/GC sponge were higher than those of the ALG one.

Alginates↗
PubMed2002

Application of REDOR subtraction for filtered MAS observation of labeled backbone carbons of membrane-bound fusion peptides.

Clean MAS observation of 13C-labeled carbons in membrane-bound HIV-1 and influenza fusion peptides was made by using a rotational-echo double-resonance spectroscopy (REDOR) filter of directly bonded 13C-15N pairs. The clean filtering achieved with the REDOR approach is superior to filtering done with sample difference spectroscopy. In one labeling approach, the peptide had labels at a single 13C carbonyl and its directly bonded 15N. The resulting chemical shift distribution of the filtered signal is used to assess the distribution of local secondary structures at the labeled carbonyl. For the influenza peptide, the Leu-2 carbonyl chemical shift distribution is shown to vary markedly with lipid and detergent composition, as well as peptide:lipid ratio, suggesting that the local peptide structure also has a strong dependence on these factors. Because most carboxylic- and amino-labeled amino acids are commercially available, this REDOR approach should have broad applicability to chemically synthesized peptides as well as bacterially synthesized proteins. In a second labeling approach, the HIV-1 fusion peptide had U-13C, 15N labeling over three sequential residues. When a 1.6 ms REDOR dephasing time is used, only backbone 13C signals are observed. The resulting spectra are used to determine spectral linewidths and to assess feasibility of assignment of uniformly labeled peptide.

Carbon Isotopes↗
PubMed2002

An iron delivery pathway mediated by a lipocalin.

Despite the critical need for iron in many cellular reactions, deletion of the transferrin pathway does not block organogenesis, suggesting the presence of alternative methods to deliver iron. We show that a member of the lipocalin superfamily (24p3/Ngal) delivers iron to the cytoplasm where it activates or represses iron-responsive genes. Iron unloading depends on the cycling of 24p3/Ngal through acidic endosomes, but its pH sensitivity and its subcellular targeting differed from transferrin. Indeed, during the conversion of mesenchyme into epithelia (where we discovered the protein), 24p3/Ngal and transferrin were endocytosed by different cells that characterize different stages of development, and they triggered unique responses. These studies identify an iron delivery pathway active in development and cell physiology.

Acute-Phase Proteins↗
PubMed2002

Melatonin reduces memory changes and neural oxidative damage in mice treated with D-galactose.

To investigate the role of melatonin in D-galactose-induced amnesic mice, the avoidance/escape and water maze tests were performed to evaluate their learning and memory function. Spectrophotometry was employed to determine the content of thiobarbituric acid-reactive substances (TBARS) and the activities of antioxidative enzymes in the brain. The present results demonstrate that D-galactose-induced amnesic mice had significantly decreased learning and memory function. The reduced activities of superoxide dismutase and glutathione peroxidase and increased levels of TBARS were found in brain tissue of the amnesic mice. Melatonin, administered (ig) at doses of 0.1, 1, or 10 mg/kg to the D-galactose-treated mice for 3 months, was sufficient to block these changes. These data suggest that D-galactose is involved in accelerating the brain aging process by elevating free radical generation and reducing antioxidative enzyme activities in vivo. Furthermore, the antioxidative activity of melatonin on the D-galactose-treated mice may account for, at least partially, the improvement of learning and memory function in the aging and amnesic model.

Amnesia↗
PubMed2002

Identification and characterization of a new member of serpin family- HongrES1 in rat epididymis.

A full length cDNA named HongrES1 was isolated and cloned by screening rat epididymis cDNA library using a mouse EST as a probe and 5'RACE followed. It contained 1590bp nucleotides and its predicted protein had 415 amino acid residues including a serpin (serine protease inhibitor) conserved domain. Tissue distribution pattern showed it was specifically expressed in adult rat epididymis; moreover, in situ hybridyzation indicated this gene was expressed in a limited region of the cauda epididymis near vas deference. Such kind of expression pattern sugested that HongrES1 had potential function in male reproduction.

Amino Acid Sequence↗
PubMed2002

Overweight is an independent risk factor for cardiovascular disease in Chinese populations.

In the last decade of the 20th century, cardiovascular disease was the leading cause of death in China, accounting for one-third of the total deaths. In comparison with western populations, the mean body weight or body mass index (BMI) of the Chinese population was lower, but showed an increasing trend. Whether the variation within lower levels of BMI or waist circumference was associated with other risk factors of cardiovascular disease, and whether they contribute independently to the risk of cardiovascular disease in the Chinese population, was investigated in this study. In keeping with a uniform study design, in each of 14 study populations at different geographical locations and with different characteristics, the incidence rates of stroke, coronary heart disease (CHD) and the causes of death were monitored in approximately/= 100000 residents from 1991 to 1995 using the MONICA procedure. Risk factors were surveyed in a random cluster sample of 1000 subjects (35-59 years of age) from each population under surveillance using internationally standardized methods and a centralized system to ensure quality control. Among the risk factors, body weight, height, and waist and hip circumferences were measured. Cross-sectional stratified analyses were used to analyse the relationship of BMI (kg m(-2)) or waist circumference to other metabolic risk factors. Ten cohorts among the 14 study populations with 24734 participants were surveyed from 1982 to 1985 as a baseline for further study and were followed-up for 9 years taking the events of stroke, CHD and different causes of death as end-points. Cox regression models were used to explore the association of BMI with the relative risks of stroke, CHD and total death. The survey in 14 random samples with a total number of 19 741 subjects showed that the mean BMI (20.8-25.1) and waist circumference (67.8-86.7 cm) were much lower than those of western populations. There was, however, variation in the anthropometric measurements among populations within China. Thus, rates of overweight varied from 2.7% to 48.1% and obesity from 0% to 9.5% on the basis of the World Health Organization (WHO) classification, but these values were lower than those found in western populations. Data from the 10 cohort samples compared with baseline data in the early 1980s showed that the mean BMIs increased significantly in eight populations during the early 1990s with the differences ranging from 0.5 to 2.5 kg m(-2). Despite the lower level of BMI and the lower rate of overweight, cross-sectional analyses showed that the prevalence of hypertension, high fasting serum glucose, high serum total cholesterol and low high-density lipoprotein cholesterol (HDL-C) and their clustering were all raised with increases in BMI or waist circumference. The prospective cohort study showed that the BMI was one of the independent risk factors for stroke and CHD in Chinese populations. Hence, in a Chinese population characterized by lower levels of BMI and great variability in rates of overweight, variation of BMI was significantly related to the prevalence of other metabolic risk factors and their clustering. Overweight was one of the independent risk factors for stroke and CHD, both at population and individual levels. Given the increasing trends of BMI in the last 10 years, during the period of economic transition there is a need to encourage the population to adopt healthy dietary habits and to increase their physical activity. Health education and health promotion are important for the prevention and non-pharmacological therapy of cardiovascular disease in China.

Adult↗
PubMed2002

Super pairwise alignment (SPA): an efficient approach to global alignment for homologous sequences.

Sequence analysis is the basis of bioinformatics, while sequence alignment is a fundamental task for sequence analysis. The widely used alignment algorithm, Dynamic Programming, though generating optimal alignment, takes too much time due to its high computation complexity O(N(2)). In order to reduce computation complexity without sacrificing too much accuracy, we have developed a new approach to align two homologous sequences. The new approach presented here, adopting our novel algorithm which combines the methods of probabilistic and combinatorial analysis, reduces the computation complexity to as low as O(N). The computation speed by our program is at least 15 times faster than traditional pairwise alignment algorithms without a loss of much accuracy. We hence named the algorithm Super Pairwise Alignment (SPA). The pairwise alignment execution program based on SPA and the detailed results of the aligned sequences discussed in this article are available upon request.

Algorithms↗
PubMed2002

p21 modulates threshold of apoptosis induced by DNA-damage and growth factor withdrawal in prostate cancer cells.

Current therapy for advanced prostate cancer is largely based on androgen deprivation and is mostly palliative because all patients eventually relapse with androgen-independent disease. Doxorubicin (Dx), an anthracycline used commonly as a chemotherapeutic agent in relapsed prostate cancer, is a strong inducer of p53 expression and p21(CIP1/WAF1) (p21) transactivation. Previous reports suggest that p21 may have a role in the modulation to chemotherapy-induced apoptosis, prostate cancer progression and androgen regulation. In order to investigate if p21 has a pro-survival role in the response of prostate cancer cells to cellular stress, we exposed two androgen-regulated human prostate cancer cell lines (MDA PCa 2b and LNCaP) to Dx and growth factor withdrawal. We then studied expression of p53 and p21, cell-cycle kinetics and apoptosis. We have found that p53 protein accumulated in a dose- and time-dependent manner after Dx treatment, while p21 expression increased over time with low but decreased with high Dx doses. Apoptosis occurred in parallel with p21 down-modulation. Dx treatment of p53 knockout cells demonstrated that p21 induction was strictly p53 dependent. Reduction of p21 levels in prostate cancer cells with an antisense p21 adenovirus resulted in sensitization to Dx and accelerated onset of apoptosis in response to growth factor withdrawal. The evidence presented here also suggests that caspase activation mediates the apoptosis in this system and supports that p21 may modulate the threshold of apoptosis in prostate cancer. These observations may thus provide implications onto the integration of chemotherapy and androgen ablation.

Antibiotics, Antineoplastic↗
PubMed2002

Pain control in outpatient hysteroscopy.

Office hysteroscopy has become increasingly used as first line investigation for abnormal uterine bleeding and other diseases involving the uterine cavity. The main limitation to its widespread use is pain and low patient tolerance. This review examines current literature on analgesia used in outpatient hysteroscopy with the purpose of establishing guidelines on methods of pain relief for the procedure. However, the review has failed to find substantial or conclusive evidence for the routine use of local analgesia in outpatient hysteroscopy. Most literature suggests that it is a well-tolerated procedure and recommends analgesic use only in selected patients. Additional research is indicated for developing superior narrow diameter hysteroscopes and endometrial biopsy devices to improve the acceptability of office hysteroscopy.

Ambulatory Care↗
PubMed2002

Regulation of proinflammatory cytokines in human lung epithelial cells infected with Mycoplasma pneumoniae.

Mycoplasma pneumoniae is a small bacterium without a cell wall that causes tracheobronchitis and atypical pneumonia in humans. It has also been associated with chronic conditions, such as arthritis, and extrapulmonary complications, such as encephalitis. Although the interaction of mycoplasmas with respiratory epithelial cells is a critical early phase of pathogenesis, little is known about the cascade of events initiated by infection of respiratory epithelial cells by mycoplasmas. Previous studies have shown that M. pneumoniae can induce proinflammatory cytokines in several different study systems including cultured murine and human monocytes. In this study, we demonstrate that M. pneumoniae infection also induces proinflammatory cytokine expression in A549 human lung carcinoma cells. Infection of A549 cells resulted in increased levels of interleukin-8 (IL-8) and tumor necrosis factor alpha mRNA, and both proteins were secreted into culture medium. IL-1 beta mRNA also increased after infection and IL-1 beta protein was synthesized, but it remained intracellular. In contrast, levels of IL-6 and gamma interferon mRNA and protein remained unchanged or undetectable. Using protease digestion and antibody blocking methods, we found that M. pneumoniae cytoadherence is important for the induction of cytokines. On the other hand, while M. pneumoniae protein synthesis and DNA synthesis do not appear to be prerequisites for the induction of cytokine gene expression, A549 cellular de novo protein synthesis is responsible for the increased cytokine protein levels. These results suggest a novel role for lung epithelial cells in the pathogenesis of M. pneumoniae infection and provide a better understanding of M. pneumoniae pathology at the cellular level.

Bacterial Proteins↗
PubMed2002

Metanephric mesenchyme contains embryonic renal stem cells.

Renal epithelial cells derive from either cells of the metanephric mesenchyme or ureteric bud cells, but the origin of other renal cells is unclear. To test whether metanephric mesenchymal cells generate cells other than epithelial, we examined the developmental potential of a metanephric mesenchymal cell line (7.1.1 cells) and of primary cultures of metanephric mesenchymal cells. 7.1.1 Cells express both mesenchymal and epithelial markers and, on confluence, form well-defined monolayers expressing epithelial junctional proteins. However, 7.1.1 cells as well as primary cultures of metanephric mesenchymal cells also generate spindle-shaped cells that are positive for alpha-smooth muscle actin, indicating that they are myofibroblasts and/or smooth muscle; this differentiation pathway is inhibited by collagen IV and enhanced by fetal calf serum or transforming growth factor-beta(1). Transforming growth factor-beta(1) also induces expression of smooth muscle proteins, indicating that the cells differentiate into smooth muscle. 7.1.1 Cells as well as primary cultures of metanephric mesenchymal cells also express vascular endothelial growth factor receptor 2 and Tie-2, suggesting that the metanephric mesenchymal cells that generate epithelia may also differentiate into endothelial cells. The pluripotency of the 7.1.1 cells is self-renewing. The data suggest that the metanephric mesenchyme contains embryonic renal stem cells.

Animals↗