Biomedical subjects

Yiping Zhang

Publications and source records attributed to Yiping Zhang.

29 records · Page 2Linked to original sources

PubMed2003

Encephalitogenic activity of truncated myelin oligodendrocyte glycoprotein (MOG) peptides and their recognition by CD8+ MOG-specific T cells on oligomeric MHC class I molecules.

We have previously demonstrated that the 21-residue peptide pMOG(35-55) from myelin oligodendrocyte glycoprotein (MOG) contains an antigenic epitope that activates CD8(+) encephalitogenic T cells in C57BL/6 (B6) mice. To identify the core encephalitogenic epitope of CD8(+) MOG-specific T cells, we have prepared a panel of highly purified peptides of varying lengths, which span the entire length of pMOG(35-55), and tested their binding to recombinant H-2D(b) dimers and their ability to induce EAE. Two of the truncated peptides, pMOG(40-54) and pMOG(44-54), strongly bound recombinant H-2D(b) protein and this complex bound MOG-specific CD8(+) T cells. Interestingly, pMOG(40-54) retained the full capability of inducing paralytic disease, whereas only a part of the B6 mice immunized with pMOG(44-54) developed clinical paralysis and central nervous system (CNS) inflammation. Further deletion of 1 amino acid from either the N- or C-terminus of the peptide pMOG(44-54) dramatically reduced binding to recombinant H-2D(b), and abolished the induction of paralysis and CNS inflammation. Our results demonstrate that the ability of truncated pMOG(35-55) peptides to bind recombinant H-2D(b) protein does not always correlate with their ability of inducing encephalomyelitis. This approach enables the further identification of the core pathogenic epitope within the pMOG(35-55) that activates MOG-specific encephalitogenic CD8(+) T cells.

Animals↗

PubMed2003

Intrathecal B-cell clonal expansion, an early sign of humoral immunity, in the cerebrospinal fluid of patients with clinically isolated syndrome suggestive of multiple sclerosis.

The development of somatically mutated memory and plasma B cells is a consequence of T cell-dependent antigen-challenged humoral immunity. To investigate the role of B cell-mediated humoral immunity in the initiation and evolution of multiple sclerosis (MS), we analyzed Ig variable heavy chain genes of intrathecal B cells derived from patients with a first clinical manifestation suggestive of MS. Sequences of Ig variable regions showed that B cells in the cerebrospinal fluid from most of these patients were clonally expanded and carried somatic hypermutated variable heavy chain genes. The mutations showed a high replacement-to-silent ratio and were distributed in a way suggesting that these clonally expanded B cells had been positively selected through their antigen receptor. In comparison, intrathecal B-cell clonal expansion often precedes both oligoclonal IgG bands and multiple magnetic resonance imaging lesions. Clinical follow-up study showed that patients with clonally expanded intrathecal B cells had a high rate of conversion to clinically definite MS. The findings provide direct evidence of recruitment of germinal center differentiated B lymphocytes into the central nervous system during the initiation of MS. These results indicate B cell-mediated immune response in the cerebrospinal fluid is an early event of inflammatory reaction in the central nervous system of MS. This procedure also provides a more sensitive method to evaluate the association of humoral immunity in the evolution of MS.

Adult↗

PubMed2003

[Effect of iron oxide addition on hydrogen, carbon dioxide and methane geneses in paddy soil].

Paddy soil is an important contributor for atmospheric methane. The methanogenesis is related to the production of acetate, hydrogen and carbon dioxide during the decomposition of organic matter under anaerobic conditions. As electron acceptors, iron (III) oxides can effectively compete with electrons in the transformation of organic matter into methane. Its mechanism maybe relates to the consumption of H2 and CO2. After added ferrihydrite and lepidocrocite, the H2, CO2 and CH4 were determined during the anaerobic incubation of slurries at 25 degrees C for 105 days. The results indicated that the addition of ferrihydrite and lepidocrocite could greatly decrease the concentration of H2, CO2 and CH4, and ferrihydrite had a stronger effect than lepidocrocite. In this system, the balance of organic-C was disturbed, CH4-C and CO2-C were reduced, but the CO3(2-)-C fixed by slurry was greatly increased.

Carbon Dioxide↗

PubMed2003

[Effect of low molecular weight organic acids on Pb2+ adsorption and desorption by constant charge soil colloids].

The isothermal curves of Pb2+ adsorption-desorption by soil colloids followed Freundlich and Langmuir equation. The adsorption constant Ka showed the trend of old manured loessal soil > yellow loessal soil > dark cultivated loessal soil > yellow cinamon soil, which was consistent with surface charge density sigma 0, an indicator of the strength of Pb2+ adsorption by each soil colloid. Low molecular-weight organic acids (LMWOAs) made Pb2+ adsorbed amount decreased and adsorption affinity increased, and the effect of citric acid was larger than that of oxalic acid. The constant Kd of residual Pb2+ adsorption after desorption showed the trend of old manured loessal soil > yellow cinamon soil > dark cultivated loessal soil > yellow loessal soil, which reflected the adsorption strength of residual Pb2+ after desorption, and was related to the contents of organic matter and free ferric oxide. The isothermal curves of Pb2+ desorption from soil colloids were obvious higher than those of Pb2+ adsorption. In NaNO3 and oxalic acid background solution, the isothermal curves of Pb2+ adsorption were far away from those of Pb2+ desorption, showing that the hysteretic degree between adsorption and desorption was very large. The isothermal curves of Pb2+ desorption from soil colloids were closed to those of Pb2+ adsorption in citric acid background solution, which showed that the Pb adsorption and desorption was reversible.

Adsorption↗

PubMed2003

[Temporal-spatial distribution characteristics of microclimate in tropical secondary forest canopy gap in Xishuangbanna].

Based on the data obtained from vertical gradient measurements of microclimatic elements of canopy gap in tropical secondary forest of Xishuangbanna in fog-cool and dry-hot season, the daytime characteristics of temporal-spatial distribution and variation of trunk surface temperature, air temperature, water vapor pressure and relative humidity in canopy gap were discussed. The data showed that gap edge had not only a remarkable thermal effect, but also a significant water vapor effect. These effects resulted in environmental heterogeneity in canopy gap. The results provided a basis for further studying heat and water vapor transport, microclimatic formation, biodiversity, and forest succession in canopy gap.

Climate↗

PubMed2002

Animal models of ankylosing spondylitis.

The pathology of ankylosing spondylitis (AS) and related spondyloarthropathies (SpA) characteristically involve a sacroiliitis and inflammation of the intervertebral discs (IVD) in the lumbar spine, and an enthesitis at sites of ligamentous insertions into bone. The proteoglycans aggrecan and versican are large molecules that aggregate with hyaluronic via a globular 1 domain. These domains share significant homology at the level of B and T cell epitope recognition. Both proteoglycans are present in the intervertebral disc and hyaline cartilages of the sacroiliac joint, as well as in entheses. Whereas aggrecan is most concentrated in the nucleus of the IVD and in articular cartilages and endplates, versican is generally absent from these tissues except in the sacroiliac joint, but is concentrated in ligaments and the annulus. Immunity to these molecules in BALB/c mice results in an AS-like pathology, including sacroiliitis, enthesitis, and discitis. The pathology of AS is closely associated with the expression of the class I molecule human leukocyte antigen-B27. Rats bearing this transgene develop an AS-like pathology, as well as other various signs of autoimmunity. Ankylosing spondylitis is characterized by an ankylosing pathology whereby bone formation in the annulus leads to intervertebral fusion. Mice bearing the ank/ank defect gene develop a bony ankylosis of the spine like that seen in advanced AS and related SpA. These three animal models provide insight into the pathogenesis of SpA, and opportunities to investigate their pathology in relationship to human disease where investigation of the pathobiology is very difficult, because of restricted access to involved tissues.

Animals↗

PubMed2002

The characterization of versican and its message in human articular cartilage and intervertebral disc.

Splicing variation of the versican message and size heterogeneity of the versican core protein were analyzed in human articular cartilage and intervertebral disc. Splicing variation of the message was studied by PCR analysis to detect the presence or absence of exons 7 and 8, which encode large chondroitin sulfate attachment regions. At all ages in normal cartilage from the third trimester fetus to the mature adult, the presence of the versican isoform possessing exon 8 but not exon 7 (V1) could be readily detected. The message isoforms possessing neither exon 7 nor 8 (V3) or both exons 7 and 8 (V0) were only detectable in the fetus, and the isoform possessing only exon 7 (V2) was never detected. In osteoarthritic cartilage and in adult intervertebral disc the versican message pattern was the same as that observed in the normal adult with only the isoform possessing exon 8 being detected. Core protein heterogeneity was studied by immunoblotting following enzymic removal of the glycosaminoglycan chains from the proteoglycan, using an antibody recognizing the globular G1 region of versican. All articular cartilage extracts from the fetus to the mature adult contained multiple core protein sizes of greater than 200 kDa. The adult cartilage extracts tended to have an increased proportion of the smaller sized core proteins and osteoarthritic cartilage possessed similar core protein sizes to the normal adult. In contrast, intervertebral disc at all post-natal ages showed a greater range of size heterogeneity with a prominent component of about 50 kDa. The abundance of this component increased if the samples were treated with keratanase prior to analysis, suggesting that the G1 region of versican in disc can be substituted with keratan sulfate. The increased presence of versican in the disc relative to articular cartilage may suggest a more pronounced functional role for this proteoglycan, particularly in the nucleus pulposus.

Adolescent↗

PubMed2002

[Effects of mercury and cadmium on the activity of urease in soils. I. Urea concentration].

Relationship between urease activity and heavy metals(Hg and Cd) under the condition of different urea concentration was studied. The results showed that the added urea concentration had an obvious positive effect on urease activity. Line and Langmuir models could be well described the relationship within the urea concentration tested. The calculation of urease parameters such as urea percent, urea-varying percent, and the maximum superficial urease activity reflected that Hg and Cd could remarkably reduce the positive effect from added urea, combined pollution of Hg + Cd displayed the most inhibition of the positive effect, and Hg produced the most ecological toxicity acting on soil urease activity. There was an adsorption mechanism in the enzyme reaction.

Cadmium↗

PubMed2002

[A primary study on thermal effect of soil-plant-atmosphere continuum in tropical seasonal rain forest gap].

Made use of measurement data of microclimatic elements of canopy gap in tropical seasonal rain forest in fog-cool and dry-hot season in Xishuangbanna, the daytime characteristics of temporal-spatial distribution and variation of soil surface temperature, air temperature, and leaf temperature of understory plants in canopy gap were discussed. The finding showed that influenced by fog and solar altitude, the maximum value of microclimatic elements displayed at different site of gap in different time and season and there existed phenomenon about higher value area of leaf temperature dynamic displacement. In addition, the direction of heat transferring of soil-plant-atmosphere continuum varied with time and season, indeed at the same time, the different part of gap had the different heat transferring directions. The results would supply a research basis for further studying heat and water vapor transport, microclimatic formation, biodiversity and succession of canopy gap.

Hot Temperature↗

PubMed1997

Polyoxoanion Coordination Chemistry: Synthesis and Characterization of the Heterometallic, Hexanuclear Clusters [{Zn(bipy)(2)}(2)V(4)O(12)], [{Zn(phen)(2)}(2)V(4)O(12)].H(2)O, and [{Ni(bipy)(2)}(2)Mo(4)O(14)].

The hydrothermal reactions of vanadium oxide and molybdenum oxide starting materials with divalent first-row transition metal cations in the presence of nitrogen donor chelating ligands yield the heterometallic hexanuclear clusters [{Zn(bipy)(2)}(2)V(4)O(12)] (2), [{Zn(phen)(2)}(2)V(4)O(12)].H(2)O (3.H(2)O), and [{Ni(bipy)(2)}(2)Mo(4)O(14)] (4). A similar reaction in the presence of excess 2,2'-bipyridine yields [Zn(bipy)(3)](2)[V(4)O(12)].11H(2)O (1.11H(2)O), a species with an isolated {V(4)O(12)}(4)(-) cluster. The structure of 2 consists of a {V(4)O(12)}(4)(-) ring covalently attached to each of two {Zn(bipy)(2)}(2+) moieties through the terminal oxo groups of alternate vanadium sites. In contrast, the structure of 3 exhibits a {V(4)O(12)}(4)(-) ring linked through oxo groups of adjacent vanadium sites to two {Zn(phen)(2)}(2+) moieties. The structure of 4 is constructed from two {Mo(2)O(7)}(2)(-) units linked through two {Ni(bipy)(2)}(2+) groups to form a cyclic 12-membered {Mo(4)Ni(2)O(6)} core. Crystal data: [Zn(bipy)(3)](2)[V(4)O(12)].11H(2)O (1.11H(2)O), a = 21.910(4) Å, b = 14.044(2) Å, c = 23.815(4) Å, beta = 106.15(1) degrees, monoclinic, C2/c, Z = 4; [{Zn(bipy)(2)}(2)V(4)O(12)] (2), a = 12.017(2) Å, c = 15.120(2) Å, tetragonal P4(2)/n, Z = 2. [{Zn(o-phen)(2)}(2)V(4)O(12)].H(2)O (3.H(2)O), a = 18.182(2) Å, b = 11.3668(9) Å, c = 23.455(2) Å, beta = 97.815(7) degrees, monoclinic P2(1)/c, Z = 4; [{Ni(bipy)(2){(2)Mo(4)O(14)] (4), a = 12.323(2) Å, c = 14.897(4) Å, tetragonal P4(2)2(1)2, Z = 2.

Journal Article↗

PubMed1996

Hydrothermal Syntheses and Structural Characterization of Layered Vanadium Oxides Incorporating Organic Cations: alpha-, beta-(H(3)N(CH(2))(2)NH(3))[V(4)O(10)] and alpha-, beta-(H(2)N(C(2)H(4))(2)NH(2))[V(4)O(10)].

Four new layered mixed-valence vanadium oxides, which contain interlamellar organic cations, alpha-(H(3)N(CH(2))(2)NH(3))[V(4)O(10)] (1a), beta-(H(3)N(CH(2))(2)NH(3))[V(4)O(10)] (1b), alpha-(H(2)N(C(2)H(4))(2)NH(2))[V(4)O(10)] (2a), and beta-(H(2)N(C(2)H(4))(2)NH(2))[V(4)O(10)] (2b), have been prepared under hydrothermal conditions and their single-crystal structures determined: 1a, triclinic, space group P&onemacr;, a = 6.602(2) Å, b = 7.638(2) Å, c = 5.984(2) Å, alpha = 109.55(3) degrees, beta = 104.749(2) degrees, gamma = 82.31(3) degrees, Z = 1; 1b, triclinic, P&onemacr;, a = 6.387(1) Å, b = 7.456(2) Å, c = 6.244(2) Å, alpha = 99.89(2) degrees, beta = 102.91(2) degrees, gamma = 78.74(2) degrees, Z = 1; 2a, triclinic, P&onemacr;, a = 6.3958(5) Å, b = 8.182(1) Å, c = 6.3715(7) Å, alpha = 105.913(9) degrees, beta = 104.030(8) degrees, gamma = 94.495(8) degrees, Z = 1; 2b, monoclinic, space group P2(1)/n, a = 9.360(2) Å, b = 6.425(3) Å, c = 10.391(2) Å, beta = 105.83(1) degrees, Z = 2. All four of the compounds contain mixed-valence V(5+)/V(4+) vanadium oxide layers constructed from V(5+)O(4) tetrahedra and pairs of edge-sharing V(4+)O(5) square pyramids with protonated organic amines occupying the interlayer space.

Journal Article↗