Biomedical subjects

Y Zeng

Publications and source records attributed to Y Zeng.

At least 37 records · Page 2Linked to original sources

PubMed2004

Study of renal function matching between Banna Minipig Inbred line and human.

Pigs have been thought to be ideal candidates for xenotransplant donors. However besides the immunological barrier, physiological and pharmacokinetic comparabilities of kidney function between donor animals and humans are important factors for successful xenotransplantation. As a unique large inbred animal, Banna Minipig Inbred (BMI) has been reported to be a potential large animal suitable for xenotransplantation. However, its physical and pharmacokinetic compatibilities with humans have not been documented. The purpose of this investigation was to measure renal routine function, glomerular filtration rate (GFR), renal blood flow (ERPF), and drug metabolism to evaluate comparability to humans. The results suggested that the renal function of BMI was similar to that of humans to eliminate nonprotein nitrogenous end products of metabolism. Pharmacokinetics of p-aminohippurate (PAH) and inulin--the most widely used methods to assess ERPF and GFR--showed that BMI showed lower values than humans for GFR, but similar function to humans in ERPF. The pharmacokinetics of cefazolin; a widely used model drug to study kidney drug metabolizing capacity, showed greater overall renal drug elimination of BMI than of humans. These results suggested that BMI did show comparable data to human renal function.

Adult↗

PubMed2004

Activation of human coagulation system by liver-derived clotting factors of Banna minipig inbred line.

The liver synthesizes most of the coagulation factors that play a major role in arresting hemorrhage. Matching hepatic coagulation factors is an important premise in successful xenotransplantation. As a unique inbred pig, the Banna minipig inbred (BMI) animals have a huge potential value for pig-to-human xenotransplantation, due to its clear genetic background and tiny interindividual differences. Whether the coagulation factors synthesized by porcine liver can trigger human clotting pathways has not been reported. This study focused on the activities of BMI coagulant factors synthesized exclusively by the liver to activate human clotting pathways. In these experiments we prepared coagulant factors II, V, VII, X, and XII synthesized exclusively by liver from BMI and humans. The factors were used in common correction tests, added to the corresponding factor-deficient human plasma to determine prothrombin times or activated partial thromboplastin time, thereby calculating BMI and human coagulant factor activities. BMI clotting factors XII, VII, and X triggered human intrinsic, extrinsic, and common pathways, respectively. BMI clotting factors II, V, VII, X, and XII activities were 3.2-, 3.7-, 4.7-, 2.9-, and 4.5-fold as potent as those from humans.

Adult↗

PubMed2004

Study of hepatic function matching between Banna minipig inbred and humans.

As a unique inbred pig Banna minipig inbred (BMI) is potentially suitable for pig-to-human xenotransplantation due to its clear genetic background and minor interindividual differences. Previous studies of BMI have focused on immunological barriers between BMI and humans. However, a comparison of liver function between donor animals and humans is an essential premise for successful xenotransplantation. In this study, we investigated routine hepatic functions, protein electrophoresis, and drug metabolism to compare capacity of liver synthesis, metabolism, and drainage between BMI and humans. The results showed no significant differences in the concentrations of albumin and globulin synthesized in the liver (alpha1, alpha2, and beta-globulin). Serum enzyme activities in BMI were higher than those in humans, and levels of total bilirubin and direct-reacting bilirubin of BMI were lower than those of humans. In BMI, the clearance of antipyrine, a widely used model drug to study hepatic drug metabolism, was 16 times greater than that by humans, with a mean residual time of antipyrine in BMI, one-tenth of that in human. These findings suggested that BMI livers are similar to humans in albumin and alpha, beta-globulin synthesis, but stronger in bilirubin elimination, enzyme activity, and drug metabolism. BMI livers may have stronger functions compared with those of humans. No incompatibility was identified in hepatic function between BMI and humans.

Adult↗

PubMed2004

Biomechanical properties of the rat oesophagus in experimental type-1 diabetes.

The gastrointestinal tract remodels its morphology and circumferential stress-strain properties in diabetes mellitus. This study adds one more piece of mechanical knowledge, namely the oesophageal shear modulus and its dependence on the circumferential and longitudinal stresses and strains of oesophagus in diabetic rats and control rats. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50 mg kg(-1) body weight). The diabetic rats lived up to 28 days after the induction of diabetes. The oesophagus was studied in vitro using a triaxial machine. Stepwise elongation and inflation plus continuous twist were carried out with measurement of the resultant forces. Circumferential and longitudinal stresses and strains were computed from steady-state values of longitudinal force, outer diameter and the applied pressure. The shear modulus was computed from the twist angle-torque relationship. The circumferential and longitudinal stress-strain relationships were exponential. The circumferential stiffness increased 1 week after induction of diabetes (P < 0.001). The longitudinal stiffness increased in the 4-week diabetic rats (P < 0.001). The shear modulus varied as function of longitudinal strain and pressure. The oesophagus became stiffer in shear 4 weeks after the induction of diabetes (P < 0.001).

Animals↗

PubMed2004

Identification of a novel HLA-F allele - HLA-F*010102.

We describe herein the identification of HLA-F*010102 by cloning the full-length coding sequence with reverse-transcription polymerase chain reaction (RT-PCR). This new allele was found in two Han Chinese individuals in the course of cloning major histocompatibility complex class Ib (MHC Ib) cDNA. It was identical to HLA-F*010101 except for a single-nucleotide substitution in codon -1 (GCG --> GCA). This nucleotide change represents a synonymous mutation, as both triplets code for an alanine. The cDNA of this allele was 48 bp shorter than HLA-F*010101 due to splicing out exon 7. Analysis of the deduced amino acid sequence revealed that the product of this new allele had the identical extracellular domain and transmembrane region but had a shorter cytoplasmic tail.

Alleles↗

PubMed2003

Vaccination with minigenes encoding for novel 'self' antigens are effective in DNA-vaccination against neuroblastoma.

The induction of T-cell mediated immunity against neuroblastoma is a challenge due to poor immunogenicity of this malignancy. Here, we demonstrate the induction of protective immunity in a syngeneic murine neuroblastoma model following vaccination with minigenes comprising of three novel natural MHC class I ligands. First, after immunoprecipitation of MHC class I from NXS2 cells, peptides were eluted and examined in tandem-MS analysis which lead to the identification of three novel natural MHC class I peptide ligands, TEALPVKLI from ribonucleotide reductase M2, NEYIMSLI from Ser/Thr protein phosphatase 2A and FEMVSTLI with unknown origin. Second, we constructed two different minigenes, one encoding for the three novel epitopes and the second for three known mTH derived epitopes with high predicted binding affinity to MHC class I by cloning them into the mammalian expression vector pCMV-3FUB. This lead to constructs with an ubiquitin-tag upstream the inserted epitopes in order to facilitate proteasomal degradation. Furthermore the epitopes were separated by a spacer peptide (AAY), which proved to be a preferential proteasome cleavage site. Third, we demonstrate the induction of protective immunity against neuroblastoma using an attenuated strain of Salmonella typhimurium as a carrier harboring pCMV 3FUb vectors encoding for the two minigenes. These findings establish proof of concept that disruption of self tolerance against neuroblastoma associated epitopes may be an effective adjuvant therapeutic strategy.

Animals↗

PubMed2003

Allelic variation in 5-HT1A receptor expression is associated with anxiety- and depression-related personality traits.

The 5-HT1A receptor plays a critical role in the pathophysiology of anxiety and depression as well as in the mode of action of anxiolytic and antidepressant drugs. Human 5-HT1A gene transcription is modulated by a common C-1016G single nucleotide polymorphism (SNP) in its upstream regulatory region. In the present study, we evaluated the role of the HTR1A-1019 polymorphism in the modulation of individual differences in personality traits by an association study of a sample of healthy volunteers. Personality traits were assessed with two different methods, NEO personality inventory (NEO-PI-R) and Tridimensional Personality Questionnaire (TPQ). There was a significant effect of the HTR1A-1019 polymorphism on NEO Neuroticism with carriers of the G allele showing higher scores than individuals homozygous for the C variant. The effect was primarily due to associations with the Neuroticism facets Anxiety and Depression. Carriers of the G allele also exhibited higher TPQ Harm Avoidance scores. Our findings indicate a role of allelic variation in 5-HT1A receptor expression in the development and modulation of anxiety- and depression-related personality traits.

Adolescent↗

PubMed2003

The effect of epidermal growth factor on the incremental Young's moduli in the rat small intestine.

Biomechanical remodelling of the rat small intestine after treatment with epidermal growth factor (EGF) subcutaneously for 2 days (n=6), 4 days (n=6), 7 days (n=6), and 14 days (n=4) was studied. The incremental circumferential, longitudinal and cross moduli close to the in vivo state were computed from bi-axial test data (combined inflation and axial stretching) by a least square method. The moduli in the circumferential direction and the longitudinal direction differed in all groups, i.e. the mechanical properties were anisotropic in both normal and EGF-treated rats. Time-dependent variation existed for the Young's moduli in all directions during EGF treatment (P<0.05). The circumferential modulus decreased during the first 7 days of EGF treatment and it almost remodelled back to that of the control group after 14 days treatment. The incremental modulus in the circumferential direction ranged between 17.4 and 24.2 kPa. The modulus in the longitudinal direction ranged between 22.9 and 32.4 kPa. The longitudinal modulus after 4 days EGF treatment was significantly larger than that of control group (P<0.02). The cross modulus decreased during the first 4 days of EGF treatment thereafter it increased to a maximum at 7 days. The values for the cross moduli were between 4.7 and 6.6 kPa. In conclusion, the mechanical properties in the intestinal wall are anisotropic and remodel during treatment with EGF.

Adaptation, Physiological↗

PubMed2001

Stressed apoptotic tumor cells express heat shock proteins and elicit tumor-specific immunity.

In attempting to develop effective anticancer immunotherapies, the relative ability of apoptotic cells to induce an immune response remains an important but controversial consideration. A novel gene-transfer approach was used by which rapid induction of pure apoptosis can be selectively achieved in a transfected tumor cell population following exposure to a semisynthetic dimerizing ligand, AP20187. Inoculation of BALB/c mice with apoptotic and viable 12B1-D1 leukemia cells, at a 12:1 ratio subcutaneously, led to early tumor growth. Heat stress up-regulated the expression of membrane heat shock proteins (HSP72 and HSP60) on apoptotic 12B1-D1 cells, and stressed apoptotic cells were capable of generating a T-cell-mediated specific antitumor response. Pulsing of stressed apoptotic leukemia cells onto syngeneic dendritic cells resulted largely in rejection of coinjected viable 12B1-D1 cells. Mice rejecting the primary 12B1-D1 inoculum were immune to the same but not to a different leukemia challenge. Our findings indicate that tumor immunogenicity is dependent on whether cells are stressed before apoptosis induction and suggest that the immune system is capable of distinguishing between stressed and nonstressed cells undergoing programmed cell death. (Blood. 2001;97:3505-3512)

Animals↗

PubMed2001

Regional characteristics of sulfur and lead isotope ratios in the atmosphere at several Chinese urban sites.

Sulfur and lead isotope ratios in the atmosphere were measured at several selected sites (Harbin, Changchun, Dalian, Waliguan, Shanghai, Nanjing, Guiyang) in China and Tsukuba (Japan), to reveal regional sources characteristics over Eastern Asia. Average S isotope ratios for SO2 and sulfate in the atmosphere in China were close to those of the coals used in each region, indicating a considerable contribution of coal combustion to the sulfur compounds in the atmosphere. Most northern cities had around 5% sulfur isotope ratio, while Guiyang, a southwestern city in China, showed a considerably lower sulfur isotope ratio (about -3%) because of the unusually light sulfur isotope ratio of coals in this region. These were considerably different from the value (-1.4%) for Tsukuba (Japan). Lead isotope ratios also suggested that coal combustion considerably contributed to atmospheric lead in some cases in China. At the same time, influences by the emission of Chinese lead ores were also observed in northern cities. Seasonal variations of both sulfur and lead isotope ratios indicated the existence of a certain amount of industrial sources other than coal combustion. In addition, fractionation effect between SO2 and sulfate showed a seasonal tendency (high in winter (0-6%) and low in summer (-1-3%)), suggesting the oxidation pathway of SO2 changed seasonally.

Air Pollution↗

PubMed2001

Accumulation of caveolin in the endoplasmic reticulum redirects the protein to lipid storage droplets.

Caveolin-1 is normally localized in plasma membrane caveolae and the Golgi apparatus in mammalian cells. We found three treatments that redirected the protein to lipid storage droplets, identified by staining with the lipophilic dye Nile red and the marker protein ADRP. Caveolin-1 was targeted to the droplets when linked to the ER-retrieval sequence, KKSL, generating Cav-KKSL. Cav-DeltaN2, an internal deletion mutant, also accumulated in the droplets, as well as in a Golgi-like structure. Third, incubation of cells with brefeldin A caused caveolin-1 to accumulate in the droplets. This localization persisted after drug washout, showing that caveolin-1 was transported out of the droplets slowly or not at all. Some overexpressed caveolin-2 was also present in lipid droplets. Experimental reduction of cellular cholesteryl ester by 80% did not prevent targeting of Cav-KKSL to the droplets. Cav-KKSL expression did not grossly alter cellular triacylglyceride or cholesteryl levels, although droplet morphology was affected in some cells. These data suggest that accumulation of caveolin-1 to unusually high levels in the ER causes targeting to lipid droplets, and that mechanisms must exist to ensure the rapid exit of newly synthesized caveolin-1 from the ER to avoid this fate.

Amino Acid Sequence↗

PubMed2001

Cloning and functional expression of a degradation-resistant novel isoform of p27Kip1.

p27(Kip1) is an inhibitor of cyclin-dependent kinases. It has been implicated as having a role in the induction of growth arrest at the G(1) phase of the cell cycle in response to anti-mitogenic signals such as cell contact and serum starvation. Proteasome-mediated degradation plays an important role in the rapid inactivation of p27(Kip1), causing quiescent cells to re-enter the cell cycle. Although the existence of a second isoform has been suggested, no such isoform was isolated. Through screening of a cDNA library derived from growth-arrested confluent porcine endothelial cells, we obtained clones for a novel isoform of p27(Kip1) in addition to the original isoform. The novel isoform differed from the original isoform at the C-terminus. The tissue-specific expression of the original and novel isoforms was demonstrated at the mRNA and protein levels. An in vitro degradation assay demonstrated this novel isoform to be resistant to proteasome-mediated destruction. The expression as a fusion protein with green fluorescent protein revealed this isoform to be targeted to the nucleus by a bipartite nuclear-localization signal with a C-terminal part different from that of the original isoform. The expression of the novel isoform caused the growth arrest of HeLa cells and an accumulation of cells in the G(0)/G(1) phase, and this effect was similar to that seen with the original isoform. The present study suggests that the novel isoform functions as a negative regulator of the cell cycle, and may play a distinct role. The novel isoform was named p27(Kip1R) because of its resistance to degradation.

Alternative Splicing↗

PubMed2001

Dendritic-cell-peptide immunization provides immunoprotection against bcr-abl-positive leukemia in mice.

Chronic myelogenous leukemia (CML) is a clonal disorder characterized by proliferation of cells that possess the bcr-abl fusion gene resulting in the production of one of two possible chimeric 210-kDa tyrosine kinase proteins. Since these chimeric proteins are expressed only in leukemic cells they have the potential to serve as tumor-specific antigens for cytotoxic T lymphocytes (CTL). Using the 12B1 murine leukemia cell line, derived by retroviral transformation of BALB/c bone marrow cells with the bcr-abl (b3a2) fusion gene, we have demonstrated that intravenous inoculation of 12B1 cells into BALB/c mice results in a disseminated acute leukemia analogous to human CML in blast crisis. Histological sections of liver and spleen and polymerase chain reaction analysis of peripheral blood, bone marrow, liver, spleen and lymph nodes confirmed the presence of bcr-abl+ leukemia cells in these murine tissues, while Western blot data demonstrated the expression of the fusion protein in 12B1 cells. Immunization of mice with dendritic cells (DC) loaded with the synthetic bcr-abl chimeric nonapeptide, GFKQSSKAL, led to a 150 times higher frequency of bcr-abl-specific CTL precursors in the spleen than in mice immunized with peptide alone. In vitro re-stimulation of DC-peptide-primed splenocytes resulted in substantial secretion of interferon gamma and augmented cytolytic activity against 12B1 targets. Finally, vaccination with peptide-loaded DC significantly prolonged survival of BALB/c mice that were challenged with 12B1 leukemia. The capacity to generate bcr-abl-specific CTL in vivo by DC-based immunization may have clinical implications in the treatment of CML.

Animals↗

PubMed2001

The studies of hemoglobinopathies and thalassemia in China--the experiences in Shanghai Institute of Medical Genetics.

BACKGROUND: In the past two decades, a large-scale survey of hemoglobinopathies and thalassemia was carried out in mainland China, involving nearly one million people in 28 provinces. The incidences of hemoglobin (Hb) variants, alpha-thalassemia and beta-thalassemia were 0.33%, 2.64% and 0.66%, respectively. The chemical structural analysis identified 67 Hb variants. Among them, 20 are new variants. The analysis of the alpha-globin gene organization in 111 HbH patients showed 76 cases (68.5%) were of the deletion type, 8 had Hb Constant Spring and the other cases were of non-deletion type. The results of the molecular characterization of more than 200 beta-thalassemia alleles showed that the most common types of beta-thalassemia mutations in China are CD 41/42 (-4 bp), IVS-II-nt.654 C-->T, CD 17 A-->T, CD 71/72 (+A) and -28 A-->G. METHODS: To explore the simple method for molecular diagnosis of beta-thalassemia, multiplex allele-specific amplification (MAS-PCR) was used that could simultaneously detect the above five common types of beta-thalassemia mutations. RESULTS: Based on the molecular analysis of beta-thalassemia intermedia, beta-thalassemia homozygotes or compound heterozygotes combined with alpha-thalassemia, as well as the conjunctive abnormalities of beta-thalassemia heterozygote with triplicated haplotype of alpha-globin genes, were the most common cause of thalassemia intermedia in China. We also used the RT-PCR quantitation method to show that the most common beta-thalassemia allele, IVS-II-nt.654 C-->T, still produced a small amount (about 15%) of normally spliced beta-globin mRNA, therefore, causing beta+-thalassemia. In clinical trials of hydroxyurea (HU) treatment for beta-thalassemia patients, we found that HU may enhance the expression of the beta-globin gene in some patients, leading to an alleviation of clinical symptoms. In the studies of the reversal of aberrant splicing of IVS-II-nt.654 C-->T allele by the antisense approach, we constructed a mammalian expression vector that can produce an antisense RNA targeting against the aberrant splice sites of IVS-II-nt.654 C-->T pre-mRNA. CONCLUSIONS: The results indicated that the antisense RNA produced from the vector could efficiently suppress the aberrant splicing pattern and restore the correct splicing pathway in vitro and in vivo, leading to the improvement of globin chain biosynthesis in thalassemia cells.

China↗

PubMed2001

A comparison of biomechanical properties between human and porcine cornea.

Due to the difficulty in obtaining human corneas, pig corneas are often substituted as models for cornea research. The purpose of this study is to find the similarities and differences in the biomechanical properties between human and porcine corneas. Uniaxial tests were conducted using an Instron apparatus to determine their tensile strength, stress-strain relationship, and stress-relaxation properties. The tensile strength and stress-strain relation were very similar but significant differences between the two tissues were observed in the stress-relaxation relationship. Under the same stretch ratio lambda=1.5, porcine cornea relaxed much more than human cornea. If tensile strength and the stress-strain relation are the only mechanical factors to be investigated, porcine cornea can be used as a substitute model for human cornea research. However, when stress relaxation is a factor, porcine corneas cannot be used as an appropriate model for human corneas in mechanical property studies. It is very difficult to get enough specimens of human cornea, so we did the experiments for stress-strain relationship at a specific value of strain rate (corresponding to the velocity of loading 10mm/min), and for stress relaxation at a specific stretch ratio lambda=1.5.

Animals↗

PubMed2001

Gene therapy restores vision in a canine model of childhood blindness.

The relationship between the neurosensory photoreceptors and the adjacent retinal pigment epithelium (RPE) controls not only normal retinal function, but also the pathogenesis of hereditary retinal degenerations. The molecular bases for both primary photoreceptor and RPE diseases that cause blindness have been identified. Gene therapy has been used successfully to slow degeneration in rodent models of primary photoreceptor diseases, but efficacy of gene therapy directed at photoreceptors and RPE in a large-animal model of human disease has not been reported. Here we study one of the most clinically severe retinal degenerations, Leber congenital amaurosis (LCA). LCA causes near total blindness in infancy and can result from mutations in RPE65 (LCA, type II; MIM 180069 and 204100). A naturally occurring animal model, the RPE65-/- dog, suffers from early and severe visual impairment similar to that seen in human LCA. We used a recombinant adeno-associated virus (AAV) carrying wild-type RPE65 (AAV-RPE65) to test the efficacy of gene therapy in this model. Our results indicate that visual function was restored in this large animal model of childhood blindness.

Animals↗

PubMed2001

The R region found in the human foamy virus long terminal repeat is critical for both Gag and Pol protein expression.

It has been suggested that sequences located within the 5' noncoding region of human foamy virus (HFV) are critical for expression of the viral Gag and Pol structural proteins. Here, we identify a discrete approximately 151-nucleotide sequence, located within the R region of the HFV long terminal repeat, that activates HFV Gag and Pol expression when present in the 5' noncoding region but that is inactive when inverted or when placed in the 3' noncoding region. Sequences that are critical for the expression of both Gag and Pol include not only the 5' splice site positioned at +51 in the R region, which is used to generate the spliced pol mRNA, but also intronic R sequences located well 3' to this splice site. Analysis of total cellular gag and pol mRNA expression demonstrates that deletion of the R region has little effect on gag mRNA levels but that R deletions that would be predicted to leave the pol 5' splice site intact nevertheless inhibit the production of the spliced pol mRNA. Gag expression can be largely rescued by the introduction of an intron into the 5' noncoding sequence in place of the R region but not by an intron or any one of several distinct retroviral nuclear RNA export sequences inserted into the mRNA 3' noncoding sequence. Neither the R element nor the introduced 5' intron markedly affects the cytoplasmic level of HFV gag mRNA. The poor translational utilization of these cytoplasmic mRNAs when the R region is not present in cis also extended to a cat indicator gene linked to an internal ribosome entry site introduced into the 3' noncoding region. Together these data imply that the HFV R region acts in the nucleus to modify the cytoplasmic fate of target HFV mRNA. The close similarity between the role of the HFV R region revealed in this study and previous data (M. Butsch, S. Hull, Y. Wang, T. M. Roberts, and K. Boris-Lawrie, J. Virol. 73:4847--4855, 1999) demonstrating a critical role for the R region in activating gene expression in the unrelated retrovirus spleen necrosis virus suggests that several distinct retrovirus families may utilize a common yet novel mechanism for the posttranscriptional activation of viral structural protein expression.

Gene Expression Regulation, Viral↗

PubMed2001

Identification of a vibrational frequency corresponding to H-atom translocation in hypericin.

Using time-resolved infrared spectroscopy, ab initio quantum mechanical calculations and synthetic organic chemistry a region in the infrared spectrum of triplet hypericin has been found between 1400 and 1500 cm-1 corresponding to the translocation of the hydrogen atom between the enol and the keto oxygens, O...H...O. This result is discussed in the context of the photophysics of hypericin and of eventual measurements to observe directly the excited-state H-atom transfer.

Anthracenes↗