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Biomedical subjects

M Yan

Publications and source records attributed to M Yan.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Different serum lipid adjustment drugs for the treatment of hyperlipidemic fatty liver].

OBJECTIVE: To research the effect of different serum lipid adjustment drugs, Simvastatin and Fenofibrate, on hyperlipidemic fatty liver. METHODS: The rat models of hyperlipidemic fatty liver induced by high fat diet were treated with Fenofibrate and Simvastatin respectively to investigate the change of the liver index, liver function, the serum and liver lipid, MDA, and pathologic histology. RESULTS: The liver index and the content of triglyceride (TC1.80 +/-0.20/2.10+/-0.33), total cholesterol (TG 0.76+/-0.18/1.09+/-0.31), MDA both in the serum and the liver in the model group were significantly higher than those in control group. Slight or moderate hepatic steatosis was observed in model group. Fenofibrate decreased serum triglyceride, total cholesterol, and MDA both in serum and liver significantly, but increased the ALT, ALP, liver index, liver lipids, and finally leading to severe hepatic steatosis. Simvastatin lowered the level of lipid and MDA both in serum and liver, and liver histology was improved nearly to normal. Moreover, little side effect on the liver was observed. CONCLUSIONS: Simvastatin can be applied for prevention and treatment of hyperlipidemic fatty liver safely and effectively, while Fenofibrate can not.

Animals↗
PubMed2001

[The preliminary result of osteoid callus allograft for bone healing].

OBJECTIVE: To investigate the feasibility of osteoid callus allograft as a kind of bone healing promoting materials. METHODS: The osteoid callus was obtained at one week after bilateral femoral fracture of a SD rat, then was kept at -196 C for 2 weeks. The bone defect model which bone repair was in intra-membranous osteogenesis was made at bilateral tibial shaft in 5 rats, and filled with the osteoid callus in the left defect area, the right side was filled with allogenous cancellous as control group. The specimen were processed with undecalcified technique and the sections were staining with light blue and sofranin T. RESULTS: After 2 weeks, there were cartilage and bone formation in the defect area of osteoid callus graft group(3/4), medullary cavity formation in bone tissue with cartilage arround it, fibrous tissues between new bone and host bone. While there were no cartilage or bone formation in the control group. CONCLUSION: The allograft osteoid callus is not absorbed by immunological rejection, but changed into bone tissue through endochondral osteogenesis. It is inspiring to develop osteoid callus allograft as a kind of material for bone healing.

Animals↗
PubMed2000

Induction of ref-1 ensures AP-1 activation in intracellular oxidative environment of IL-2-stimulated BA/F3beta cells.

Our previous study of interleukin-2 (IL-2) signaling found that redox factor-1 (Ref-1) mRNA was upregulated by IL-2. In this study, we further studied the function of Ref-1 in the potential redox regulation of IL-2 signaling in BA/F3beta cells. Western blot analysis confirmed that IL-2 stimulation increases Ref-1 protein. Flow cytometric assay by using 2',7'-dichlorofluorescin diacetate indicated that IL-2 stimulation results in an oxidative shift of intracellular environment. However, IL-2-induced activator protein-1 (AP-1) is oxidation-sensitive. Gel shift assays of nuclear extracts immunodepleted of Ref-1 protein demonstrated that IL-2-induced AP-1 DNA binding is dependent on the presence of Ref-1. This was further confirmed by the restoration of AP-1 DNA binding upon the re-addition of immunoprecipitated Ref-1. Additionally, reporter gene assays showed that AP-1 transcriptional activity was enhanced by the overexpression of Ref-1 and attenuated by the introduction of antisense Ref-1. These results suggest that the induction of Ref-1 ensures AP-1 activation in the intracellular oxidative environment of IL-2-stimulated BA/F3beta cells.

Base Sequence↗
PubMed2000

Two-amino acid molecular switch in an epithelial morphogen that regulates binding to two distinct receptors.

Ectodysplasin, a member of the tumor necrosis factor family, is encoded by the anhidrotic ectodermal dysplasia (EDA) gene. Mutations in EDA give rise to a clinical syndrome characterized by loss of hair, sweat glands, and teeth. EDA-A1 and EDA-A2 are two isoforms of ectodysplasin that differ only by an insertion of two amino acids. This insertion functions to determine receptor binding specificity, such that EDA-A1 binds only the receptor EDAR, whereas EDA-A2 binds only the related, but distinct, X-linked ectodysplasin-A2 receptor (XEDAR). In situ binding and organ culture studies indicate that EDA-A1 and EDA-A2 are differentially expressed and play a role in epidermal morphogenesis.

Amino Acid Sequence↗
PubMed2000

Single chain spectroscopy of conformational dependence of conjugated polymer photophysics.

Single molecule confocal fluorescence microscopy was used to perform photoluminescence spectroscopy on single, isolated molecules of the conjugated polymer poly[2-methoxy, 5-(2'-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV). We show that the fluorescence from single chains of this electroluminescent polymer depends strongly on chain conformation. The time evolution of the spectra, emission intensity, and polarization all provide direct evidence that memory of the chain conformation in solution is retained after solvent evaporation. Chains cast from toluene solution are highly folded and show memory of the excitation polarization. Exciton funneling to highly aggregated low energy regions causes the chain to mimic the photophysical behavior of a single chromophore. Chains cast from chloroform, however, behave as multichromophore systems, and no sudden discrete spectral or intensity jumps are observed. These also exhibit different spectroscopy from the folded chromophores.

Journal Article↗
PubMed2000

Interaction of the TNF homologues BLyS and APRIL with the TNF receptor homologues BCMA and TACI.

BLyS (also called TALL-1, THANK, or BAFF) [1] [2] [3] [4] is a member of the tumor necrosis factor (TNF) gene family that stimulates proliferation and immunoglobulin production by B cells. BLyS interacts with the TNF receptor (TNFR) homologue TACI (transmembrane activator and CAML-interactor) [5], and treatment of mice with a TACI-Fc fusion protein abolishes germinal center formation after antigenic challenge [6]. Here we report a novel interaction between BLyS and another TNFR homologue, BCMA (B cell maturation antigen) [7] [8]. Further, the TNF homologue APRIL [9], a close relative of BLyS, also bound to BCMA and TACI. BLyS or APRIL activated nuclear factor-kappaB (NF-kappaB) through TACI and BCMA, and each ligand stimulated immunoglobulin M (IgM) production by peripheral blood B cells. These results define a dual ligand-receptor system that may play an important role in humoral immunity.

Amino Acid Sequence↗
PubMed2000

A novel protein MAJN binds to Jak3 and inhibits apoptosis induced by IL-2 deprival.

To find a possible signal interacting with the Jak3 N-terminal, we screened the human peripheral blood cDNA library through both a two-hybrid system and a tyrosine-phosphorylation-modified two-hybrid system using the N-terminal of Jak3 as bait. Results showed that one new homologue of myosin heavy chain, designated MAJN (molecule associated with Jak3 N-terminal), could bind to Jak3 in a tyrosine-phosphorylation-independent manner. The interaction between Jak3 and MAJN was further confirmed by immunoprecipitation in BAF-B03 beta cells. To investigate the function of MAJN, we have constructed the BAF-B03 beta/MAJN cell line that stably expresses MAJN and found that overexpression of MAJN can partially inhibit the apoptosis induced by interleukin-2 deprival. Further studies are needed to elucidate how MAJN executes its function to antagonize BAF-B03beta cell death in the absence of IL-2.

Apoptosis↗
PubMed2000

Retinoic acid inhibition of cardiac mesenchyme formation in vitro correlates with changes in the secretion of particulate matrix from the myocardium.

Retinoic acid has been associated with a variety of cardiac defects. A percentage of these defects are related to changes in the endocardial cushions. Studies in mice and older chick embryos have shown a decrease in mesenchymal cell formation attributable to retinoic acid and have suggested that retinoic acid was affecting the extracellular matrix. In this study we have tested the effect of retinoic acid on cardiac mesenchyme formation in vitro and then tested retinoic acid treated myocyte cultures for changes in the expression of hLAMP-1, fibronectin and transferrin members of the particulate matrix that is required for mesenchyme formation. Initial experiments tested the effect of retinoic acid on mesenchymal cell formation first in atrioventricular canal and outflow tract explant cultures and then in AV endothelial monolayer cultures using myocyte conditioned media or the particulate matrix fraction from retinoic acid treated myocyte cultures. In all cases, mesenchymal cell formation was suppressed while no suppression was observed when MyoCM was included with retinoic acid. Protein analysis showed that retinoic acid had a stimulatory effect on protein synthesis. ELISA assays revealed that retinoic acid treated myocyte cultures contained significantly more hLAMP-1 and fibronectin than either normal or DMSO controls. However, transferrin was not affected by retinoic acid treatment in these experiments. Our results suggest that retinoic acid affects the expression of the particulate matrix and that these changes may be responsible for the observed decrease in mesenchymal cell formation.

Animals↗
PubMed2000

Identification of a receptor for BLyS demonstrates a crucial role in humoral immunity.

B lymphocyte stimulator (BLyS) is a member of the tumor necrosis factor (TNF) superfamily. BLyS stimulates proliferation of, and immunoglobulin production by, B cells. However, the relative importance of BLyS in physiological B cell activation is unclear. We identified a B cell receptor for BLyS through expression cloning as TACI, an orphan TNF receptor homologue of unknown function. Binding of BLyS to TACI activated signaling by nuclear factor-kappa B (NF-kappa B). In vitro soluble TACI-Fc fusion protein blocked BLyS-induced NF-kappa B activation in B lymphoma cells and IgM production in peripheral blood B cells. In vivo treatment of immunized mice with TACI-Fc inhibited production of antigen-specific IgM and IgGI antibodies and abolished splenic germinal center (GC) formation. Thus, BLyS activity must play a critical role in the humoral immune response.

Animals↗
PubMed2000

[A mechanistic model of phasic and phenological development of wheat. I. Assumption and description of the model].

The temperature effectiveness for wheat development was non-linearized and the apical and phenological development stages were systematically predicted by the scale of physiological development time which was based on the ecophysiological development process. The predicted apical development stages included single ridge stage, double ridge stage, floral initiation stage, stamen and pistil initiation stage, anther seperation stage, tetrad stage, and heading stage, while the predicted phenological development stages included germination stage, emergence stage, tillering stage, winterovering stage, green-turning stage, jointing stage, booting stage, heading stage, flowering stage, grain filling stage, and maturity stage. Four cultivar specific parameters were used to describe the genotypic differences of wheat development. They were temperature sensitivity, physiological vernalization time, photoperiod sensitivity, and intrinsic earliness, reflecting the genetic properties of different cultivars in thermal effectiveness, vernalization, photoperiod response and shortest time required for reaching flowering, respectively. The four parameters determined the physiological development time required for each development stage of different cultivars.

Models, Biological↗
PubMed2000

[Two-phase linear models of leaf emergence at different tillering positions in wheat and effects of different varieties and sowing dates].

Dynamics of leaf emergence shows the development progress and its relationship with growth in wheat. It was found that two-phase linear model equations (phase I faster than phase II) divided by glum differentiation stage could describe leaf emergence progress in relation to growing degree days (GDD) after sowing in wheat. This pattern was consistent in main stems and tillers of normal development with both winter-and-spring type varieties. The beginning of phase II shifted to an earlier development stage on main stems of winter type varieties of early planting (EP, September 30) and late planting (LP, March 2), and on T3 of both varieties of EP, MP (middle planting, on October 30) and LP due to their abnormal development. The thermal rate of leaf emergence on main stem was relatively high and steady during development for winter type variety of MP, and quickened with the postponing of sowing for spring type variety. The above results illustrated the difference of leaf emergence at different tillering positions, and the biological characteristics affected by different varieties and sowing dates.

Germination↗
PubMed2000

[The study of RDS gene mutation and clinical phenotype in a family with primary retinitis pigmentosa].

OBJECTIVE: To investigate retinal degeneration slow (RDS) gene mutation in a Chinese family with primary retinitis pigmentosa (RP) and the association of the mutation with clinical phenotypes and to explore the pathogenesis of RP. METHODS: Blood DNA from 2 patients in the same family with RP and 2 normal persons was analyzed by molecular genetic methods. RDS gene mutation was screened out by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis. The mutant RDS gene fragment was cloned, then sequenced with an automatic DNA sequencer using a dideoxy chain termination protocol. The phenotype of the patients with the gene mutation were examined and determined by clinical ophthalmologic examinations. RESULTS: The PCR-RFLP analysis of the RDS gene in 2 patients with RP revealed codon 216 mutation of RDS gene. The mutation was heterozygous, and not found in 2 normal persons as controls. The alteration in the DNA sequence was identified as a heterozygous transversional change of C to T at the second nucleotide in codon 216 of RDS gene, resulting in the amino acid replacement of proline residue with leucine residue (Pro216Leu). The ocular finding of the patients with Pro216Leu mutation of RDS gene included severe visual loss and diffuse distribution of pigmentary changes with macular degeneration. CONCLUSIONS: The Pro216Leu mutation of RDS gene is found in Chinese patients with RP. The gene mutation is associated with the ocular phenotype, diffuse RP with macular degeneration.

Adult↗
PubMed2000

[The detection of disparity evoked potentials in anisometropes].

OBJECTIVE: To investigate the affection of anisometropia on stereopsis and its mechanism. METHODS: A new set of static random-dot stereograms was utilized as a stimulus to elicit evoked potentials in 20 anisometropes and 40 normal subjects. RESULTS: Under the stimulus of different degrees of disparity in anisometropes, the P(250) waves related to stereopsis could be recorded. However, the percentage of their P(250) wave amplitude over the plane figure was significantly lower than that of normal persons (P < 0.05). The P(250) wave mean amplitude of severe anisometropes (aniseikonia >or= 5%) in fine disparity (14' and 23') was lower than that in mild anisometropes (aniseikonia < 5%, P < 0.05). CONCLUSIONS: Anisometropia may affect and disturb the stereopsis. The degree of disturbance is related to the degree of anisometropia. The higher the degree of anisometropia, the lower the amplitude of the P(250) potential, and the main defect is at the part of fine disparity.

Adolescent↗
PubMed2000

[Cytochrome P450IA1 and the genetic susceptibility to esophageal carcinoma].

OBJECTIVES: To explore the susceptibility to esophageal carcinoma (EC) in different population with different cytochrome P450 IA1 (CYPIA1) genotype, and study the synergistic effects between CYPIA1 and smoking. METHODS: A case-control study (case = 111, control = 114) was used to compare the frequency of CYPIA1 genotype between EC and controls with a PCR method. RESULTS: The distribution of three genotypes of CYPIA1 in EC and controls was significantly different (chi(2) = 19.35, P < 0.01). There was a synergistic effect between the mutation of CYPIA1 4,889 site and smoking (SIA = 1.56), and a significant dose-response effect was observed. The risk of individual whose CYPIA1 4,889 site is mutated was 3 times higher than those not mutated. CONCLUSIONS: The mutation of CYPIA1 ,89 site maybe one of important host susceptible factors of EC, and the risk would increase significantly in smokers.

Aged↗
PubMed2000

[Audiological findings and mitochondrial DNA mutation in a large family with matrilineal sensorineural hearing loss].

OBJECTIVE: To explore audiological features of matrilineal non-syndromic deafness and its molecular mechanism. METHODS: A large family with 41 members having inherited deafness was studied. Complete history and the data of general and otolaryngological examinations were collected. All subjects were screened for mitochondrial DNA A1555G mutation by molecular analysis. Audiological evaluation included puretone audiometry, auditory brainstem responses and transiently evoked otoacoustic emissions. RESULTS: All subjects were in good health generally. Molecular analysis showed that all maternal relatives with or without hearing loss harbored the A1555G mitochondrial mutation. No mutation was found among spouses and paternal relatives. Audiological results showed notable symmetric bilateral sensorineural hearing loss in 17 of 20 maternal relatives, in which 5 cases had a progressive hearing loss in the recent 11 years. The age of appearance of hearing loss ranged from 1 to 50 years. CONCLUSION: All hearing-impaired subjects of this family had late-onset sensorineural hearing loss. Most of which were progressive. The A1555G mitochondrial mutation in the 12S rRNA gene is responsible for the disorder. Other factors, such as nuclear genes or environmental determinants, may influence the clinical expression of mutant mtDNA.

Acoustic Impedance Tests↗
PubMed2000

[Whole genome-wide scanning for a large pedigree with matrilineal deafness].

OBJECTIVE: To search responsible nuclear genes for matrilineal non-syndromic deafness. METHODS: Whole genome-wide scanning was performed to analyze the 365 short tandem repeats in a deaf pedigree with maternal inheritance using DNA pooling strategy. Frequencies of allele in one patient pool were compared with that in one unaffected relative pool as well as in one normal control pool. Linkage analysis was also conducted in some positive loci. RESULTS: Allele from 45 loci occurred more frequently in the patient pool than that in the unaffected relative pool and the control pool. No linkage was found from any candidate locus investigated. CONCLUSION: 45 positive loci obtained from this family may be as the candidate positions for matrilineal non-syndromic deafness.

Deafness↗
PubMed1999

The use of ATP and initiating nucleotides during postrecruitment steps at the activated adenovirus E4 promoter.

Permanganate probing has been used to follow the progress and ATP dependence of promoter opening during activated adenovirus E4 initiation and clearance. Using templates designed to restrict synthesis to defined positions, formation of a 3-nucleotide-long RNA was found to be sufficient to trigger expansion of the initial transcription bubble. This occurred by a discrete transition that expanded the downstream limit of melting from position 1 to 15. Subsequent clearance of the bubble from the promoter region also occurred without detectable intermediates. Thus, initial opening, extension, and the clearance of the promoter bubble appear to occur as discrete, unique transitions. The apparent K(m) values for these three steps were determined to be near 5, 9, and 50 microM, respectively. Comparison of these values with ATPase activities within known transcription factors raises the possibility that different activities could be responsible for each step.

Adenosine Triphosphate↗