Biomedical subjects

Yong Peng

Publications and source records attributed to Yong Peng.

48 records · Page 3Linked to original sources

PubMed2003

Synthesis of endotoxin receptor CD14 protein in Kupffer cells and its role in alcohol-induced liver disease.

AIM: To observe the synthesis of endotoxin receptor CD14 protein and its mRNA expression in Kupffer cells (KCs), and evaluate the role of CD14 in the pathogenesis of liver injury in rats with alcohol-induced liver disease (ALD). METHODS: Twenty-eight Wistar rats were divided into two groups: ethanol-fed group and control group. Ethanol-fed group was fed ethanol (dose of 5g-12 g/kg/d) and control group received dextrose instead of ethanol. Two groups were sacrificed at 4 wk and 8 wk, respectively. KCs were isolated and the synthesis of CD14 protein and its mRNA expression in KCs were determined by flow cytometric analysis (FCM) or the reverse transcription polymerase chain reaction (RT-PCR) analysis. The levels of plasma endotoxin and alanine transaminase (ALT) were measured by Limulus Amebocyte Lysate assay and standard enzymatic procedures respectively, and the levels of plasma tumor necosis factor (TNF)-alpha and interleukin (IL)-6 were both determined by ELISA. The liver pathology change was observed under light and electric microscopy. RESULTS: In ethanol-fed group, the percentages of FITC-CD14 positive cells were 76.23 % and 89.42 % at 4 wk and 8 wk, respectively. Compared with control group (4.45 % and 5.38 %), the difference was significant (P<0.05). The expressions of CD14 mRNA were 7.56+/-1.02 and 8.74+/-1.37 at 4 wk and 8 wk, respectively, which were significantly higher compared with the control group (1.77+/-0.21 and 1.98+/-0.23) (P<0.05). Plasma endotoxin levels at 4 wk and 8 wk increased significantly in ethanol-fed group (129+/-21 ng/L and 187+/-35 ng/L) than those in control rats (48+/-9 ng/L and 53+/-11 ng/L)(P<0.05). Mean values of plasma ALT levels increased dramatically in ethanol-fed rats (112+/-15 IU/L and 147+/-22 IU/L) than those in the control animals (31+/-12 IU/L and 33+/-9 IU/L) (P<0.05). In ethanol-fed rats, the levels of TNF-alpha were 326+/-42 ng/L and 402+/-51 ng/L at 4 wk and 8 wk, respectively which were significantly higher than those in control group (86+/-12 ng/L and 97+/-13 ng/L) (P<0.05). The levels of IL-6 were 387+/-46 ng/L and 413+/-51 ng/L, which were also higher than control group (78+/-11 ng/Land 73+/-10 ng/L) (P<0.05). In liver section from ethanol-fed rats, there were marked pathological changes including steatosis, cell infiltration and necrosis. No marked pathological changes were seen in control group. CONCLUSION: Ethanol administration led to a significant synthesis of endotoxin receptor CD14 protein and its gene expression in KCs, which maybe result in the pathological changes of liver tissue and hepatic functional damages.

Animals↗

PubMed2003

In vitro expression of CD14 protein and its gene in Kupffer cells induced by lipopolysaccharide.

OBJECTIVE: To observe expression of CD14 protein and its gene in Kupffer cells induced by lipopolysaccharide (LPS) and explore the role of CD14 in LPS-induced Kupffer cell activation. METHODS: Kupffer cells were isolated from Wistar rat livers by in situ collagenase digestion, followed by culture and incubation with 100 microg/ml LPS for 0, 30, 60 and 120 min, respectively. CD14 protein expressed on the membrane of Kupffer cells was examined using confocal microscopy and Western blotting analysis. Expression of CD14 mRNA in Kupffer cells was determined by reverse transcription polymerase chain reaction (RT-PCR). Tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 in the supernatant were measured using enzyme-linked immunosorbent assay (ELISA) kit. RESULTS: Expression of CD14 mRNA and CD14 protein in isolated Kupffer cells was upregulated quickly after LPS stimulation and increased with time. Likewise, there was a time-dependent increase of TNF-alpha and IL-6 in the supernatant with upregulation of CD14 expression. There were significant differences between normal and LPS-stimulated Kupffer cells (P<0.05). CONCLUSIONS: LPS can upregulate expression of CD14 protein and its gene in isolated Kupffer cells. CD14 may play an important role in the activation of LPS-induced Kupffer cells.

Analysis of Variance↗

PubMed2003

[Cloning and expression of human single-chain Fv antibody against amyloid beta peptide involved in Alzheimer's disease].

OBJECTIVE: To screen out the specific antibody clones against amyloid beta peptide 40, and clone the antibody gene and express it in a bacterial system, so as to provide a solid basis for novel diagnostic and therapeutic methods for Alzheimer's Disease. METHODS: beta amyloid peptide 40 was bound on the solid surface of Nunc plates as antigen to screen the binding clones from a phage-display human single-chain Fv antibody library. After five rounds of bio-panning, the host E. coli TG1 was infected with eluted filamentous phage from the last turn of selection. 55 well-separated colonies were picked randomly from the plates and the specific positive clones were identified by ELISA test. The single-chain Fv antibody gene was sequenced and their amino acids sequence was deduced. The scFv antibody gene was sub-cloned into a protokayotic expression vector pGEX-6P-1 and transformed into bacteria strain BL21 to express the glutathione-S-transferase (GST) fusion single-chain antibody. RESULTS: ELISA test showed that 33 of the 55 clones could bind amyloid beta peptide 40 and 10 of the 33 clones could be inhibited by amyloid beta peptide 40 itself to below 50% of its original binding activities. Five of the 10 clones could also be inhibited by amyloid beta peptide 1-16 to the same level, which meant that the binding epitope of the antibody from the 5 clones was between first to sixteenth amino acids at amino-end of amyloid beta peptide 40. DNA sequencing data demonstrated that the gene of the single-chain antibody specifically against amyloid beta peptide 40 was consisted of 768 bp and the deduced amino acids sequence confirmed its typical antibody structure. The complement determinant regions and framework regions were discriminated empirically. After cloning the antibody gene into a protokayotic system, the GST fusion antibody was expressed as the expected size. CONCLUSIONS: After five rounds of bio-panning and subsequently serial ELISA testing, the specific antibody clones against amyloid beta peptide 40 were screened out successfully. The antibody gene DNA sequence and amino acids sequence were analyzed and confirmed. The fusion antibody was expressed as expected in the bacterial system.

Alzheimer Disease↗

PubMed2003

[Chemical synthesis of biodegradable poly-para-dioxanone and its application for mandibular fracture fixation].

OBJECTIVE: To observe mandibular fracture healing after synthesized bioabsorable poly-para-dioxanone (PDS) ligature fixation. METHODS: Para-dioxanone monomer was prepared by chemical reactions of metallic sodium, ethylene glycol and other raw materials. PDS was synthesized by polymerizing the purified para-dioxanone in the presence of catalyst under the conditions of negative pressure and certain temperature. PDS ligature was obtained by processing the polymer into small granules, drying and melt-extruding through a spinnerette. Eighteen adult male New Zealand rabbits were assigned randomly into two groups. After mandibular fracture models were created, reductions of the artificial fractures were accomplished by means of transosseous PDS ligatures on each of 12 rabbits in experimental group. While the other six rabbits without any internal fixation were set as control. Schedules for killing were arranged to give postoperative samples at two-week interval till 12th week. RESULTS: Radiographical and histological examinations demonstrated that all fractures fixed with PDS ligatures healed without any complication. Periosteal and cartilaginous osteogenesis was observed in newly formed external callus. In contrast, bone fragment migration and the consequent nonunion occurred in the control group. PDS ligature degraded and absorbed without interference with osseous union and healing. The tensile strength reduction of PDS ligature was prior to its absorption in vivo. CONCLUSION: The synthesized PDS is a colorless, flexible, themoplastic and monofilament fiber, which can be sterilized by ethylene oxide embalmment without serious loss of tensile strength. It seems that the application of this macromolecular material in internal fixation is of great worth for further study.

Absorbable Implants↗

PubMed2002

Solvation model dependency of helix-coil transition in polyalanine.

Helix-coil transitions in polyalanine molecules of length 10 are studied by multi-canonical Monte Carlo simulations. The solvation effects are included by either a distance-dependent dielectric permittivity or by a term that is proportional to the solvent-accessible surface area of the peptide. We found a strong dependence of the characteristics of the helix-coil transition from the details of the solvation model.

Biophysical Phenomena↗

PubMed2002

Liver sinusoidal endothelial cell injury by neutrophils in rats with acute obstructive cholangitis.

AIM: The objective of this study is to elucidate the potential role of poly-morphonuclear neutrophils (PMN) in the development of such a sinusoidal endothelial cell (SEC) injury during early acute obstructive cholangitis (AOC) in rats. METHODS: Twenty one Wistar rats were divided into three groups: the AOC group, the bile duct ligated group (BDL group), and the sham operation group (SO group). The common bile duct (CBD) of rats in AOC group was dually ligated and 0.2 ml of the E. Coli O(111) B(4) (5 X 10(9)cfu/ml) suspension was injected into the upper segment, in BDL group, only the CBD was ligated and in SO group, neither injection of E. Coli suspension nor CBD ligation was done, but the same operative procedure. Such group consisted of seven rats, all animals were killed 6h after the operation. Morphological changes of the liver were observed under light and electron microscope. Expression of intercellular adhesion molecule-1 (ICAM-1) mRNA in hepatic tissue was determined with reverse transcription polymerase chain reaction (RT-PCR). The serum levels of alanine aminotransferase (ALT) were determined with an autoanalyger and cytokine-induced neutrophil chemoattractant (CINC) was determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Neutrophils was accumulated in the hepatic sinusoids and sinusoidal endothelial cell injury existed in AOC group. In contrast, in rats of BDL group, all the features of SEC damage were greatly reduced. Expression of ICAM-1 mRNA in hepatic tissue in three groups were 7.54 +/- 0.82, 2.87 +/- 0.34, and 1.01 +/- 0.12, respectively. There were significant differences among three groups (P<0.05). The serum CINC levels in the three groups were 188 +/- 21 ng.L(-1), 94+/-11 ng.L(-1), and 57+/-8 ng.L(-1), respectively. There were also significant differences among the three groups (P<0.05). Activity of the serum ALT was 917 +/- 167 nkat.L(-1), 901 +/- 171 nkat.L(-1), and 908 +/- 164 nkat.L(-1), respectively, (P<0.05). CONCLUSION: Hepatic SEC injury occurs earlier than hepatic parenchymal cells during AOC. Recruitments of circulating neutrophils in the hepatic sinusoidal space might mediate the SEC injury, and ICAM-1 in the liver may modulate the PMN of accumulation.

Acute Disease↗

PubMed2002

Characterization of proteolipid protein-peptide-specific CD(4)(+) T cell of experimental allergic encephalomyelitis in Biozzi AB/H mice.

OBJECTIVE: To detect the function of proteolipid protein (PLP) peptide (residues 56 - 70)-specific CD(4)(+) T cells in experimental allergic encephalomyelitis (EAE) in Biozzi AB/H mice (H-2A(g7)). METHODS: Biozzi AB/H mice were immunized by synthetic PLP(56 - 70) peptide (DYEYLINVIHAFQYV) which was emulsified by sonication with complete Freund's adjuvant, a EAE model proven histologically and clinically. Murine splenocytes and spinal cord infiltrated (SCI) T cells were stimulated by PLP(56 - 70), then the CD(4)(+) T cells were isolated by Dynabeads, and confirmed by staining with anti-CD(4) antibody. Finally, the IL2 bioassay and IFN-gamma/IL4 ELISA were done to detect T cell proliferation and cytokine secretion after PLP(56 - 70) stimulation. RESULTS: The histology of murine spinal cord showed a great number of lymphocytes infiltrated the spinal cord; the clinical signs showed high scores (4.3) on the peak, as well as a good EAE model. After being isolated by Dynabeads, CD(4)(+) T cells showed high purification (> 99%) by staining with anti-CD(4) antibody. IL2 bioassay showed that those T cells were PLP(56 - 70)-specific T cells. ELISA showed that those T cells had high IFN-gamma/IL4 ratio, indicating that they are T helper 1 (Th1) cells. CONCLUSIONS: PLP(56 - 70)-specific splenocytes and SCI CD(4)(+) T cells in EAE from Biozzi AB/H mice were detected and showed that both of them were PLP(56 - 70)-specific Th1 cells. It is beneficial to understand what kind of role these T cells play in the development of EAE.

Amino Acid Sequence↗

PubMed2002

Cartilage end-plate rupture of the lumbar vertebrae: report of 7 cases.

The authors report the clinical manifestations, imaging features, surgical approaches and the outcome of 7 cases of cartilage end-plate rupture of the lumber vertebrae, attempting to explore the pathogenesis and describe the clinical and pathological features of the disease. The diagnosis and treatment are also discussed in brief.

Adult↗

PubMed2002

The cross-reactivity of I-A(g7) and I-A(d) tetramers.

OBJECTIVE: To investigate the cross-reactivity between glutamic acid decarboxylase (GAD)-I-A(g7) and I-A(d) tetramer in diabetes-prone non-obese diabetic (NOD) mice (I-A(g7)) and diabetes-free Balb/c mice (I-A(d)). METHODS: Two GAD peptide I-A(g7) and I-A(d) tetramers were generated and compared for phenotype and function of sorted GAD peptide I-A(g7) and I-A(d) tetramer-positive (tet+) T cells. RESULTS: The cross-reactivity is shown in either tetramer positive percentage or tetramer staining intensity. The NOD and Balb/c derived-tet+ T cells were able to be cross-stained by GAD peptide I-A(g7) and I-A(d) tetramers, and responded to both irradiated NOD and Balb/c splenotyes under stimulation by synthetic and recombinant GAD peptides. CONCLUSION: Although I-A(g7) and I-A(d) are closely related in biochemical and biological aspects, their most notable difference is the presence or absence of a negatively charged residue at position beta57 that links to insulin-dependent diabetes mellitus.

Amino Acid Sequence↗

PubMed1999

Effect of HCV NS(3) protein on p53 protein expression in hep atocarcinogenesis.

AIM:To investigate hepatocarcinogenesis by detecting the effect of HCV NS(3) protein on p53 protein expression in hepatocellular carcinoma (HCC) and pericarcinomatous liver tissue (PCLT).METHODS:The expression of HCV NS(3) and p53 protein was detected with immunohistochemical technique (SP method) in specimens of HCC and PCLT from 47 patients with negative HBV.RESULTS:The positive rate of HCV NS(3) protein was lower in HCC (62%) than in PCLT (83%) (P < 0.025). The better differentiaton of cancer cells, the stronger expression of HCV NS(3) protein (P < 0.025). The positive rate of p53 protein in HCC (81%) was higher than in PCLT (47%) (P < 0.025). The worse differentiaton of cancer cells, the stronger expression of p53 protein (P < 0.05). The p53 protein expression was not correlated with the HCV NS(3) protein expression in HCC (P < 0.5), whereas their expression was closely related to PCLT (P < 0.01), and the expression rate of p53 protein in the cases of positive HCV NS(3) protein was higher than that in the cases of negative HCV NS(3) protein.CONCLUSION:HCV NS(3) protein may exert its hepatocarcinogenic effect in early stage on host cells by endogenous pathway which may bring about mutation of p53 gene and transformation of hepatocytes.

Journal Article↗

PubMedDate not supplied

Characterization of a protein-based adhesive elastomer secreted by the Australian frog Notaden bennetti.

When provoked, Notaden bennetti frogs secrete an exudate which rapidly forms a tacky elastic solid ("frog glue"). This protein-based material acts as a promiscuous pressure-sensitive adhesive that functions even in wet conditions. We conducted macroscopic tests in air to assess the tensile strength of moist glue (up to 78 +/- 8 kPa) and the shear strength of dry glue (1.7 +/- 0.3 MPa). We also performed nanomechanical measurements in water to determine the adhesion (1.9-7.2 nN or greater), resilience (43-56%), and elastic modulus (170-1035 kPa) of solid glue collected in different ways. Dry glue contains little carbohydrate and consists mainly of protein. The protein complement is rich in Gly (15.8 mol %), Pro (8.8 mol %), and Glu/Gln (14.1 mol %); it also contains some 4-hydroxyproline (4.6 mol %) but no 5-hydroxylysine or 3,4-dihydroxyphenylalanine (L-Dopa). Denaturing gel electrophoresis of the glue reveals a characteristic pattern of proteins spanning 13-400 kDa. The largest protein (Nb-1R, apparent molecular mass 350-500 kDa) is also the most abundant, and this protein appears to be the key structural component. The solid glue can be dissolved in dilute acids; raising the ionic strength causes the glue components to self-assemble spontaneously into a solid which resembles the starting material. We describe scattering studies on dissolved and solid glue and provide microscopy images of glue surfaces and sections, revealing a porous interior that is consistent with the high water content (85-90 wt %) of moist glue. In addition to compositional similarities with other biological adhesives and well-known elastomeric proteins, the circular dichroism spectrum of dissolved glue is almost identical to that for soluble elastin and electron and scanning probe microscopy images invite comparison with silk fibroins. Covalent cross-linking does not seem to be necessary for the glue to set.

Adhesiveness↗

PubMedDate not supplied

Evaluation for collagen products for cosmetic application.

Collagen is an important component for cosmetic formulation, where it is an effective natural humectant with high substantivity. Commercial collagen preparations have a wide range of properties. In the present study, various techniques have been used to examine three distinct commercial collagens that illustrate the range of properties that are available. The usefulness of the various techniques for assessing collagen quality and batch-to-batch variation is discussed. The results indicate that there are several simple, cheap, and effective methods, such as gel electrophoresis, that provide excellent information on collagen quality. The appropriate selection of tests allows informed decisions on the choice of which collagen preparation to use to provide the desired functionality and shelf life of a formulation.

Amino Acids↗