Biomedical subjects

Yong Peng

Publications and source records attributed to Yong Peng.

At least 37 records · Page 2Linked to original sources

PubMed2005

Quantification of zeaxanthin dipalmitate and total carotenoids in Lycium fruits (Fructus Lycii).

An HPLC-DAD method has been developed to quantitatively analyze for the content of zeaxanthin dipalmitate, a major carotenoid in Fructus Lycii, in different species of the genus Lycium. Determination was performed using an Alltima C18 column with the mobile phase consisting of acetonitrile and dichloromethane (42:58). The total contents of carotenoids in these samples were also determined by using UV spectrophotometric assay. Total carotenoid concentrations of different Fructus Lycii are within the range of 0.03-0.5%. Zeaxanthin dipalmitate is a predominant carotenoid, comprising 31-56% of the total carotenoids in Fructus Lycii. This study is the first systematic quantification of the carotenoids in the fruits of different Lycium species. The results demonstrated that these methods are reliable and facile techniques for rapid analysis of carotenoids for crude drug and plant-derived food supplements.

Antioxidants↗

PubMed2005

The U937 cell line induced to express CD14 protein by 1,25-dihydroxyvitamin D3 and be sensitive to endotoxin stimulation.

BACKGROUND: CD14 was first described as a differentiation antigen on the surface of myeloid lineage cells. It acts as a glycosylphosphatidylinositol (GPI)-anchored receptor for the complex of lipopolysaccharide (LPS) and plays a key role in the activation of LPS-induced monocytes. The purpose of this study was to observe the expression of CD14 protein and its gene in the human U937 promonocytic cell line when these cells were exposed to 1,25-dihydroxyvitamin D3(VitD3) and investigate their sensitivity to endotoxin stimulation. METHODS: U937 cells were exposed to (0.1 micromol) VitD3 for 24 hours and were induced to express the CD14 mRNA gene and CD14 protein, then their responses were observed when they were stimulated with different concentrations of LPS for different time. RESULTS: The U937 cells induced by VitD3 were found to stably express CD14 mRNA and CD14 protein. And CD14 protein enhanced the sensitivity of U937/CD14 cells to lipopolysaccharide (LPS) stimulation. NF-kappaB in U937/CD14 cells can be activated with low concentration of LPS (1 ng/ml-10 ng/ml), the TNF-alpha mRNA gene was induced, and then TNF-alpha was produced and released into the supernatant of culture. CONCLUSION: VitD3 can induce U937 cell to express the CD14 gene and CD14 protein and enhance the response of this type of cells to LPS stimulation.

Analysis of Variance↗

PubMed2005

[The effect of glycine on CD14 and NF-kappa B in Kupffer cells from rat liver grafts after ischemia-reperfusion injury].

OBJECTIVE: To investigate the effect of glycine on CD14 and NF-kappa B in Kupffer cells from rat liver grafts after ischemia-reperfusion injury (IRI). METHODS: The rats were randomly divided into an IRI group, saline solution preconditioning group, and glycine preconditioning group. Their survival rates, graft functions, and hepatic histopathologic examinations were observed after IRI. Kupffer cells (KCs) following IRI were isolated and cultured to detect CD14 mRNA, NF-kappa B binding activity, and the TNF alpha and IL-1 level in the supernatant of the media. RESULTS: (1) Glycine preconditioning greatly enhanced the one-week survival rate (chi2 = 6.67 and 8.57 respectively), improved graft function, and ameliorated the histopathologic signs of injury. (2) The CD14 mRNA expression level (F = 7.64), NF-kappa B binding activity (F = 11.47), TNF alpha and IL-1 production (F = 14.08 and 9.56 respectively) in the glycine group were significantly lower than those in the other two groups. CONCLUSION: Glycine could efficiently protect rat liver grafts from ischemia-reperfusion injury by repressing the expression of CD14 and NF-kappa B binding activity in Kupffer cells and inhibiting the productions of TNF alpha and IL-1.

Animals↗

PubMed2005

[An experimental study of the inhibitory effects on the activation of endotoxin-induced Kupffer cells through short hairpin RNA targeting interleukin-1 receptor associated kinase-4 gene].

OBJECTIVE: To explore the inhibitory effects on the activation of endotoxin-induced Kupffer cells (KCs) through short hairpin RNA (shRNA) targeting interleukin-1 receptor associated kinase-4 (IRAK-4) gene. METHODS: Two effective transfection shRNA plasmid (pSIIRAK-4-A, pSIIRAK-4-B) and one invalidated plasmids (pSIIRAK-4-C) targeting IRAK-4 gene were constructed. The isolated mouse KCs were divided into three groups: the normal control group, the RNAi control group (pSIIRAK-4-C) and the RNAi effective group (pSIIRAK-4-A, pSIIRAK-4-B). Then KCs were stimulated with 0.1 microg/ml lipopolysaccharide (LPS) after 24 h transfection with the constructed plasmid. The expression of IRAK-4 gene and protein level were determined by RT-PCR and Western blot at 6 h after LPS stimulation, and the activities of NF-kappaB in KCs and the TNFalpha level were estimated by ELISA at 0 h, 1 h, 3 h, 6 h and 12 h. RESULTS: The level of IRAK-4, the activities of NF-kappaB and the TNF-alpha level in the RNAi effective group were evidently lower than those in normal and RNAi control groups (P < 0.01) at 1 h, 3 h, and 6 h. Especially, the pSIIRAK-4-A group in which the changes of the above indices were of no difference (P > 0.05), had better inhibited effects than that of the pSIIRAK-4-B group (P < 0.01). CONCLUSION: The shRNA targeting IRAK-4 gene could effectively inhibit the activation of endotoxin-induced KCs.

Animals↗

PubMed2004

Synthesis, structure-activity relationships, and in vivo properties of 3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-ones as corticotropin-releasing factor-1 receptor antagonists.

Corticotropin releasing factor (CRF) is the primary regulator of the hypothalamus-pituitary-adrenal (HPA) axis, coordinating the endocrine, behavioral, and autonomic responses to stress. It has been postulated that small molecules that can antagonize the binding of CRF1 to its receptor may serve as a treatment for anxiety-related and/or affective disorders. Members within a series of 3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-ones, exemplified by compound 2 (IC50 = 0.70 nM), were found to be very potent antagonists of CRF1. Compound 8w showed high CRF1 receptor binding affinity and was examined further in vivo. The compound was efficacious in a defensive withdrawal model of anxiety in rats and had a long half-life and reasonable oral bioavailability in dog pharmacokinetic studies.

Administration, Oral↗

PubMed2004

Expression of toll-like receptor 4 and MD-2 gene and protein in Kupffer cells after ischemia-reperfusion in rat liver graft.

AIM: To investigate the expression of toll-like receptor 4 (TLR4) and MD-2 gene and protein in Kupffer cells (KCs) and their role in ischemia-reperfusion (IR) injury of rat liver graft. METHODS: KCs were isolated at 0 (control group), 2, 12, 24 h (IR group) following IR in rat liver graft. mRNA expression of TLR4 and MD-2 was detected by RT-PCR analysis, protein expression of TLR4/MD-2 was detected by flow cytometric (FCM) analysis, and tumor necrosis factor-alpha (TNF-alpha) level in supernatant was measured by ELISA. Then isolated KCs were incubated with anti-TLR4 polyclonal antibody (anti-TLR4 group), and TNF-alpha level was measured again. RESULTS: The mRNA and protein expression of TLR4/MD-2 and the level of TNF-alpha in IR group increased significantly at 2 h following IR, and reached the maximum at 12 h, and slightly decreased at 24 h, but were still significantly higher than those in the control group (P<0.01). The expression of these factors was markedly decreased after anti-TLR4 antibody treatment as compared with the IR group (P<0.01). CONCLUSION: Lipopolysaccharide (LPS) following IR can up-regulate TLR4/MD-2 gene and protein expression in KCs, and synthesize cytokine TNF-alpha. Anti TLR4 antibody can inhibit the production of TNF-alpha induced by LPS. TLR4 and its partner molecule MD-2 may play an important role in Kupffer cell activation and IR injury.

Animals↗

PubMed2004

Endonuclease-mediated mRNA decay requires tyrosine phosphorylation of polysomal ribonuclease 1 (PMR1) for the targeting and degradation of polyribosome-bound substrate mRNA.

PMR1 is an endonuclease that is activated by estrogen to degrade Xenopus albumin mRNA. A previous report showed that the functional unit of endonuclease-mediated mRNA decay is a approximately 680-kDa polysome-bound complex that contains both PMR1 and substrate mRNA. PMR1 contains two domains involved in endonuclease targeting to polysomes, an N-terminal domain that lies between residues 200 and 250, and a C-terminal domain that lies within the last 100 residues. Loss of either domain inactivated PMR1 targeting to polysomes and stabilized albumin mRNA. The current study identified a phosphorylated tyrosine residue within the C-terminal polysome-targeting domain and showed that this modification is required for PMR1-mediated mRNA decay. Changing this tyrosine to phenylalanine inactivated the targeting of PMR1 to polysomes, blocked binding of PMR1 to the functional complex containing its substrate mRNA, prevented the targeting of a green fluorescent protein fusion protein to this complex, and stabilized albumin mRNA to degradation by PMR1 in vivo. A general tyrosine kinase inhibitor inhibited the phosphorylation of PMR1, which in turn inhibited PMR1-catalyzed degradation of albumin mRNA. These results indicate that one or more tyrosine kinases functions as a regulator of endonuclease-mediated mRNA decay.

Albumins↗

PubMed2004

Design, synthesis, and biological evaluation of 1,2,3,7-tetrahydro-6h-purin-6-one and 3,7-dihydro-1h-purine-2,6-dione derivatives as corticotropin-releasing factor(1) receptor antagonists.

A growing body of evidence suggests that CRF(1) receptor antagonism offers considerable therapeutic potential in the treatment of diseases resulting from elevated levels of CRF, such as anxiety and depression. A series of novel 1,2,3,7-tetrahydro-6H-purin-6-one and 3,7-dihydro-1H-purine-2,6-dione derivatives was synthesized and evaluated as corticotropin releasing factor-1 (CRF(1)) receptor antagonists. Compounds within this series, represented by compound 12d (IC(50) = 5.4 nM), were found to be highly potent CRF(1) receptor antagonists. In addition, compounds 12d and 12j were determined to be selective CRF(1) antagonists. The synthesis, structure-activity relationships and pharmacokinetic properties of compounds within this series is presented.

Animals↗

PubMed2004

Down-regulation of p21WAF1 promotes apoptosis in senescent human fibroblasts: involvement of retinoblastoma protein phosphorylation and delay of cellular aging.

It has been suggested that genes which exercise checkpoint control during cell cycle traverse are equally important to the process of apoptotic cell death. In this study, we show that the key cell cycle regulatory gene p21(WAF1) is also involved in the execution of apoptosis. p21(WAF1) expression was down-regulated during NaBu-induced apoptosis of senescent normal diploid human 2BS fibroblasts. Conversely, when p21(WAF1) expression was actively suppressed in 2BS cells by a stably transfected antisense p21(WAF1) construct, apoptosis was accelerated and senescence was delayed, as shown by several markers of cell aging. Down-regulation of p21(WAF1) by antisense caused an increase in the phosphorylation and inactivation of pRb. Phosphorylation of pRb was further enhanced upon induction of apoptosis by NaBu. Our results suggest that p21(WAF1), acting through the phosphorylation of pRb, regulates whether 2BS cells cease to proliferate and become senescent but resistant to apoptosis, or whether they accelerate proliferation while becoming more susceptible to apoptotic stimuli.

Apoptosis↗

PubMed2004

Cloning and expression of a fibrinolytic enzyme (subtilisin DFE) gene from Bacillus amyloliquefaciens DC-4 in Bacillus subtilis.

A strong fibrinolytic enzyme produced by Bacillus amyloliquefaciens DC-4, subtilisin DFE, was isolated from douchi, a traditional Chinese soybean-fermented food. Based on the high homology between the N-terminal sequence of subtilisin DFE and that of subtilisin BPN, PCR primers were designed that allowed for the amplification and cloning of the intact subtilisin DFE gene. Sequence analysis indicated the presence of a 1149-bp open reading frame encoding 382 amino acid residues. The enzyme was actively expressed by the Escherichia coli-Bacillus subtilis shuttle expression vector pSUGV4 in the protease-deficient strain B. subtilis WB600, and its biochemical characteristics were the same as those of the original subtilisin DFE isolated from the donor strain, i.e., its molecular weight is approximately 28 kDa and it is a serine protease.

Amino Acid Sequence↗

PubMed2004

Highly efficient gene expression of a fibrinolytic enzyme (subtilisin DFE) in Bacillus subtilis mediated by the promoter of alpha-amylase gene from Bacillus amyloliquefaciens.

Subtilisin DFE is a fibrinolytic enzyme produced by Bacillus amyloliquefaciens DC-4. The promoter and signal peptide-coding sequence of alpha-amylase gene from B. amyloliquefaciens was cloned and fused to the sequence coding for pro-peptide and mature peptide of subtilisin DFE. This hybrid gene was inserted into the Escherichia coli/Bacillus subtilis shuttle plasmid vector, pSUGV4. Recombinant subtilisin DFE gene was successfully expressed in B. subtilis WB600 with a fibrinolytic activity of 200 urokinase units ml(-1).

Bacillus subtilis↗

PubMed2004

Protective effect of nitric oxide induced by ischemic preconditioning on reperfusion injury of rat liver graft.

AIM: Ischemic preconditioning (IP) is a brief ischemic episode, which confers a state of protection against the subsequent long-term ischemia-reperfusion injuries. However, little is known regarding the use of IP before the sustained cold storage and liver transplantation. The present study was designed to evaluate the protective effect of IP on the long-term preservation of liver graft and the prolonged anhepatic-phase injury. METHODS: Male Sprague-Dawley rats were used as donors and recipients of orthotopic liver transplantation. All livers underwent 10 min of ischemia followed by 10 min of reperfusion before harvest. Rat liver transplantation was performed with the portal vein clamped for 25 min. Tolerance of transplanted liver to the reperfusion injury and liver damage were investigated. The changes in adenosine concentration in hepatic tissue and those of nitric oxide (NO) and tumor necrosis factor (TNF) in serum were also assessed. RESULTS: Recipients with IP significantly improved their one-week survival rate and liver function, they had increased levels of circulating NO and hepatic adenosine, and a reduced level of serum TNF, as compared to controls. Histological changes indicating hepatic injuries appeared improved in the IP group compared with those in control group. The protective effect of IP was also obtained by administration of adenosine, while blockage of the NO pathway using Nomega-nitro-L-arginine methyl ester abolished the protective effect of IP. CONCLUSION: IP appears to have a protective effect on the long-term preservation of liver graft and the prolonged anhepatic-phase injuries. NO may be involved in this process.

Adenosine↗

PubMed2004

Improved two-cuff technique for orthotopic liver transplantation in rat.

BACKGROUND: The first orthotopic liver transplantation in rat (ROLT) was reported by Lee in 1973. Kamada innovatively applied cuff technique to ROLT in 1979. However, the operative procedures were highly demanding and the operative mortality was relatively high. The purpose of this study was to improve the model of ROLT, simplify operative procedures, and enhance the successful rate of operation. METHODS: Orthotopic liver transplantation was performed in 160 Wistar rats by improved two-cuff technique. The portal vein between donor and recipient was anastomosed with the cuff technique. The same method was used to anastomose the infrahepatic vena cava. The suprahepatic vena cava and the hepatic artery were anastomosed by microvascular suturing and the bile duct was anastomosed end to end by a Teflon catheter. RESULTS: The average time for donor operation, graft preparation and anhepatic phase was 31 minutes, 14 minutes and 13 minutes, respectively. The anastomosis time for the suprahepatic vena cava, portal vein, infrahepatic vena cava, hepatic artery and bile duct was 7 minutes, 2 minutes, 2 minutes, 8 minutes and 1 minute, respectively. The main causes for operative mortality were pneumothorax, anesthesia, air embolism and massive bleeding, and the successful rate of operation was 92.5%. The causes for death after operation were stoma bleeding, infection, biliary obstruction and graft failure. CONCLUSION: The improved two-cuff technique can reduce operative mortality, enhance survival rate, and serve as an ideal method for the establishment of animal model of ROLT.

Anastomosis, Surgical↗

PubMed2004

[A rapid method for identification of genus lycium by FTIR spectroscopy].

In this article, a method of using Fourier-transform infrared spectroscopy (FTIR) to identify 7 species and 3 variations of genus lycium (Gouqi) in China is described. This method is based on the additive IR absorptions of the chemical components and the differences of their relative contents in various Gouqi. These differences are reflected in the FTIR spectra. The method provides a novel fingerprinting technique for the identification and differentiation of traditional Chinese medicine. Such technique can serve as a rapid, simple, reliable and non-destructive analytical method for Gouqi as a Chinese material medication.

China↗

PubMed2003

Helix versus sheet formation in a small peptide.

Segments with the amino acid sequence EKAYLRT (glutamine-lysine-alanine-tyrosine-leucine-arginine-threonine) appear in naturally occurring proteins both in alpha-helices and beta-sheets. For this reason, we have used this peptide to study how secondary structure formation in proteins depends on the local environment. Our data rely on multicanonical Monte Carlo simulations where the interactions among all atoms are taken into account. Results in gas phase are compared with that in an implicit solvent. We find that both the solvated molecule and EKAYLRT in gas phase form an alpha-helix when not interacting with other molecules. However, in the vicinity of a beta-strand, the peptide forms a beta-strand. Because of this change in secondary structure our peptide may provide a simple model for the alpha-->beta transition that is supposedly related to the outbreak of prion diseases and similar illnesses.

Amino Acid Sequence↗

PubMed2003

Purification and characterization of an extracellular alkaline serine protease with dehairing function from Bacillus pumilus.

An extracellular alkaline serine protease (called DHAP), produced by a Bacillus pumilus strain, demonstrates significant dehairing function. This protease is purified by hydrophobic interaction chromatography, ion exchange, and gel filtration. DHAP had a pI of 9.0 and a molecular weight of approximately 32,000 Dalton. It shows maximal activity at pH 10 and with a temperature of 55 degrees C; the enzyme activity can be completely inhibited by phenylmethylsulfonyl fluoride (PMSF) and diisopropyl fluorophosphates (DFP). The first 20 amino acid residues of the purified DHAP have been determined with a sequence of AQTVPYGIPQIKAPAVHAQG. Alignment of this sequence with other alkaline protease demonstrates its high homology with protease from another B. pumilus strain.

Amino Acid Sequence↗

PubMed2003

Purification and characterization of a fibrinolytic enzyme produced by Bacillus amyloliquefaciens DC-4 screened from douchi, a traditional Chinese soybean food.

Bacillus amyloliquefaciens DC-4, which produces a strongly fibrinolytic enzyme, was isolated from douchi, a traditional Chinese soybean-fermented food. A fibrinolytic enzyme (subtilisin DFE) was purified from the supernatant of B. amyloliquefaciens DC-4 culture broth and displayed thermophilic, hydrophilic and strong fibrinolytic activity. Subtilisin DFE was demonstrated to be homogeneous by SDS-PAGE and isoelectric focusing electrophoresis, and has molecular mass of 28000 Da and a pI of 8.0. The optimal reaction pH value and temperature were 9.0 and 48 degrees C, respectively. Subtilisin DFE not only hydrolyzed fibrin but also several synthetic substrates, particularly Suc-Ala-Ala-Pro-Phe-pNA, and phenylmethylsulfony fluoride can completely inhibit its fibrinolytic activity. These results indicated that subtilisin DFE is a subtilisin-family serine protease, similar to nattokinase from Bacillus natto. The first 24 amino acid residues of the N-terminal sequence of subtilisin DFE were AQSVPYGVSQIKAPALHSQGFTGS, which is identical to that of subtilisin K-54, and different from that of NK and CK. Results from subtilisin DFE gene sequence analysis showed that subtilisin DFE is a novel fibrinolytic enzyme.

Amino Acid Sequence↗

PubMed2003

Role of NF-kB in multiple organ dysfunction during acute obstructive cholangitis.

AIM: To elucidate the role of NF-kB activation in the development of multiple organ dysfunction (MOD) during acute obstructive cholangitis (AOC) in rats. METHODS: Forty-two Wistar rats were divided into three groups: the AOC group, the group of bile duct ligation (BDL group), and the sham operation group (SO group). All the animals in the three groups were killed in the 6th and 48th hour after operation. Morphological changes of vital organs were observed under light and electron microscopy. NF-kB activation was determined with Electrophoretic Mobility Shift Assay (EMSA). Arterial blood gas analyses and the serum levels of lactate dehydrogenase (LDH), alanine aminotransferase (ALT), blood urea nitrogen (BUN) and creatinine were performed. The concentrations of TNF-alpha and IL-6 in plasma were also measured. RESULTS: The significant changes of histology and ultrastructure of vital organs were observed in AOC group. By contrast, in BDL group, all the features of organs damage were greatly reduced. Expression of NF-kB activation in various tissues increased in AOC group when compared to other two groups. At 6 h, the arterial pH in three groups was 7.52+/-0.01, 7.46+/-0.02, and 7.45+/-0.02, and the blood pCO(2) was 33.9+/-0.95 mmHg, 38.1+/-0.89 mmHg, 38.9+/-0.94 mmHg, there was difference in three groups (P<0.05). At 48 h, the blood pH values in three groups was 7.33+/-0.07, 7.67+/-0.04, and 7.46+/-0.03, and blood HCO(3)(-) was 20.1+/-1.29 mmol x L(-1), 26.7+/-1.45 mmol x L(-1) and 27.4+/-0.35 mmol x L(-1), there was also difference in three groups (P<0.05). In AOC group, Levels of LDH, ALT, BUN and creatinine were 1,6359.9+/-2,278.8 nkat x L(-1), 5,796.2+/-941.9 nkat.L(-1), 55.7+/-15.3 mg/dl, and 0.72+/-0.06 mg/dl, which were higher than in SO group (3,739.1+/- 570.1 nkat x L(-1), 288.4+/-71.7 nkat x L(-1), 12.5+/-2.14 mg/dl, and 0.47+/-0.03 mg/dl) (P<0.05). Levels of plasma TNF-alpha and IL-6 in AOC at 48 h were 429+/-56.62 ng x L(-1) and 562+/-57 ng x L(-1), which increased greatly when compared to BDL group (139+/-16 ng x L(-1), 227+/-43 ng x L(-1)) and SO group (74+/-10 ng x L(-1), 113+/-19 ng x L(-1)) (P<0.05). CONCLUSION: The pathological damages and the NF-kB activation of many vital organs excised during AOC. These findings have an important implication for the role of NF-kB activation in MOD during AOC.

Acute Disease↗