14,769 research outputs found
The peptide motif of the single dominantly expressed class I molecule of the chicken MHC can explain the response to a molecular defined vaccine of infectious bursal disease virus (IBDV)
Full text linkIn contrast to typical mammals, the chicken MHC (the BF-BL region of the B locus) has strong genetic associations with resistance and susceptibility to infectious pathogens as well as responses to vaccines. We have shown that the chicken MHC encodes a single dominantly expressed class I molecule whose peptide-binding motifs can determine resistance to viral pathogens, such as Rous sarcoma virus and Marek’s disease virus. In this report, we examine the response to a molecular defined vaccine, fp-IBD1, which consists of a fowlpox virus vector carrying the VP2 gene of infectious bursal disease virus (IBDV) fused with ?-galactosidase. We vaccinated parental lines and two backcross families with fp-IBD1, challenged with the virulent IBDV strain F52/70, and measured damage to the bursa. We found that the MHC haplotype B15 from line 15I confers no protection, whereas B2 from line 61 and B12 from line C determine protection, although another locus from line 61 was also important. Using our peptide motifs, we found that many more peptides from VP2 were predicted to bind to the dominantly expressed class I molecule BF2*1201 than BF2*1501. Moreover, most of the peptides predicted to bind BF2*1201 did in fact bind, while none bound BF2*1501. Using peptide vaccination, we identified one B12 peptide that conferred protection to challenge, as assessed by bursal damage and viremia. Thus, we show the strong genetic association of the chicken MHC to a T cell vaccine can be explained by peptide presentation by the single dominantly expressed class I molecule
Una interpretación de a-ka-na-jo ( a3-ka-na-jo)
Full text linkThe author studies the word a-ka-na-jo in the PY Cn 328 tablet and taking into account some factors she proposes αγναιος as the reading of this word.The author studies the word a-ka-na-jo in the PY Cn 328 tablet and taking into account some factors she proposes αγναιος as the reading of this word
Environmental influences over the last 16 ka on compound-specific δ13C variations of leaf wax n-alkanes in the Hani peat deposit from northeast China
Full text linkCompound-specific carbon isotope ratios (δ13C) of leaf wax n-alkanes (C21-C33 odd carbon numbered n-alkanes) were measured in the Hani peat sequence from northeast China. These data were compared with lipid biomarker compositions to assess changes in local vegetation and paleoclimate for the last 16 ka The δ13C values of n-alkanes range between -36.6 and -30.7‰, showing that the compounds originate from C3 plants. Much larger variations (∼5.4‰) in the n-alkane δ13C values than those of atmospheric CO2 during the last 16 ka (< 0.5‰) indicate that the isotopic values were affected by environmental factors in addition to the postglacial δ13C variations in the atmospheric reservoir. The stratigraphic records of δ13C reveal decoupled fluctuations among the individual n-alkanes, particularly between 15.5 to 11.4 ka. Synchronous excursions in the δ13C offsets among individual n-alkanes (Δδ13C) and lipid biomarker paleoplant proxies (Paq, and C23/C31 and C27/C31) from 14.9 to 13.2 ka and 12.7 to 11.6 ka suggest that vegetational changes are the most likely causes for the decoupled δ13C variations. Parallel fluctuations of the δ13C values of terrestrial higher plant-derived C29 and C31 n-alkanes and the n-alkane average chain-length (ACL) from 11 to 6 ka indicate that the δ13C variations responded to net evaporation changes. Negative shifts in the n-alkane δ13C values coinciding with the ACL decreases at 10.5-9.3 ka and 8.1 ka indicate the short-term onset and fluctuations of the summer monsoon strength in eastern China during the early Holocene
NRF2 and chemoprevention: signaling, epigenetics and role in intestinal carcinogensis
No full textPrevention is better than cure. The carcinogenesis could take as long as 20 to 30 years to develop from initiated cells to malignant tumor, therefore providing us various opportunities to prevent the appearance of tumors with the use of chemopreventive compounds in the early stage. Chemoprevention becomes an increasing important concept and has led to the intense research about the mechanisms of actions of various chemopreventive compounds. They can be generally classified into blocking agents and suppressing agents. The chemopreventive compounds usually prevent or slow progression of cancer by maintaining a low oxidative stress and inflammatory environment in cells. This is brought about by the activation of Nrf2, the key protein being investigated in our lab. In this dissertation, I will be discussing the use of compounds as suppressing agents and blocking agents, how compounds activates Nrf2 signaling, how novel Nrf2 interaction partner IQGAP1 mediates Nrf2-Keap1 signaling axis, how expression level of Nrf2 could be regulated epigenetically, apart from the well-known post-translational control by Keap1-Ubiquitinase-Protesome axis and finally how loss of Nrf2 could enhance intestinal tumorigenesis in Apc(min/+) mice.Ph.D.Includes bibliographical referencesIncludes vitaby Ka Lung Cheun
Nearby fibroblasts' response to multiple acupuncture needle revolutions on fibroblast populated collagen gels
No full textAcupuncture is an ancient Chinese healing practice, and an alternative therapy for alleviating pain and chronic disorders. For over twenty years, research is trying to understand the mechanisms that lead to its therapeutic effect. Our laboratory investigates the cellular and molecular events in the connective tissue that occur by acupuncture needling. An in vitro assay was developed to evaluate some of the potential contributors to acupuncture’s effects using a cellular collagen gel as a loose connective tissue mimic. It was hypothesized besides immediate changes to cells under mechanical loading from an acupuncture needle, there were chemical factors released to nearby cells in acupuncture. This thesis investigates whether mechanically stimulating collagen gels with fibroblasts at different revolutions would release chemical factors to nearby fibroblasts where flow cytometry was used to observe cell proliferation as an indicator. Results reveal mechanically stimulating cellular collagen gels at different revolutions does not cause any changes in cell proliferation to nearby cells. However, dead stained mechanically stimulated cellular collagen gels showed cell death occurs around the acupuncture needle. It is possible there were no effects in cell proliferation because when a cellular collagen gel was needle manipulated, some chemical factors were released into the nearby cells. Then as needle manipulation increased, more chemical factors were released, but restricted by the larger amount of cell death around the needle from the increasing rotation.M.S.Includes bibliographical referencesby Ka Po Ch
Cartilage development and degeneration:a Wnt Wnt situation
Full text linkMatrix Extracellular Phosphoglycoprotein (MEPE) is a member of a family of
proteins called small integrin-binding ligand, N-linked glycoproteins (SIBLINGs)
which play key roles in biomineralisation. Altered MEPE expression is associated
with several phosphate and bone-mineral metabolic disorders such as oncogenic
osteomalacia and hypophosphatemic rickets. Despite this, it remains undetermined
what impact MEPE has on the growth plate; the cartilage anlagen from which
endochondral ossification, the process responsible for linear bone growth, occurs.
The work of this thesis has characterised the ATDC5 cell line and the metatarsal
organ culture as useful in vitro models of endochondral ossification. These will
prove vital in the pursuit of underpinning the molecular mechanisms involved in
endochondral bone growth. These models form the basis of the further studies in
this thesis examining the role of MEPE within this highly orchestrated process.
Before such role can be defined, this thesis details the spatial and temporal
localisation patterns of MEPE in 10-day- and 4-week-old murine growth plates.
More specifically, MEPE protein and mRNA were preferentially expressed by the
hypertrophic chondrocytes as shown by immunohistochemistry and in situ
hybridisation respectively. Microdissection of the murine growth plate confirmed
this. Localisation of the cleavage product of MEPE, a 2.2kDa acidic serine- and
aspirate-rich motif (ASARM) peptide, followed a similar pattern of expression.
The localisation of MEPE to sites of mineralisation serves to strengthen its potential
role in chondrocyte matrix mineralisation. This thesis identified this role in both
mineralising ATDC5 cells and the metatarsal organ culture. The ASARM peptide
was found to be the functional component of MEPE and this function was
dependent upon its post-translational phosphorylation. Phosphorylated (p)ASARM
peptides significantly inhibited chondrocyte matrix mineralisation without altering
the proliferation or differentiation of the chondrocyte cells, or their ability to
produce an extracellular matrix. mRNA analysis by qPCR indicted a feedback
system by which the pASARM peptide functions to allow the release of further
ASARM peptides. Moreover, the pASARM peptide inhibited mRNA expression of
markers of vascular angiogenesis highlighting a novel mechanism by which they
may inhibit chondrocyte matrix mineralisation.
This thesis also determines the regulatory cross-talk between the chondrocytes of
the murine growth plate, with the most abundant bone cell type, the osteocyte. This
cross-talk inhibits chondrocyte matrix mineralisation and is attributed to sclerostin,
an osteocyte-specific secretory protein. Furthermore, it is shown that sclerostin acts
through the MEPE-ASARM axis to regulate chondrocyte matrix mineralisation and
thus endochondral ossification.
The work described herein has characterised and validated in vitro models of
growth plate chondrocyte matrix mineralisation and has used these to identify the
role of MEPE within chondrocyte matrix mineralisation
Duan wei xia mu xie lei de xin xing he nei DNA fen zi xi tong biao ji zhi jian ding
No full textLeung Ka Chun.Thesis M.Phil. Chinese University of Hong Kong 2013.Includes bibliographical references (leaves 100-110).Abstracts also in Chinese.Title from PDF title page (viewed on 21, September, 2016).Leung Ka Chun
San zhong chao jian dai teng hu dui gao wen de sheng li fan ying ji zhuan lu ti yan jiu
No full textWong, Ka Wing Karen.Thesis M.Phil. Chinese University of Hong Kong 2014.Includes bibliographical references (leaves 143-157).Abstracts also in Chinese.Title from PDF title page (viewed on 30, November, 2016).Wong, Ka Wing Karen
The application of S-band polarimetric radar measurements to Ka-band attenuation prediction
Full text linkIn September 1993, the National Aeronautics and Space Administration's Advanced Communications Technology Satellite (ACTS) was deployed into a geostationary orbit near 100° W longitude. The ACTS satellite employs two Ka-band beacons, one at 20.185 GHz and another at 27.505 GHz. Impairments due to rain attenuation and tropospheric scintillations will significantly affect new technologies for this spectrum. Heavy rain at Ka-band can easily produce 30 dB of attenuation along the propagation path. Propagation experiments being conducted in seven different climatic zones involve multiyear attenuation measurements along the satellite-earth slant path. Measurements in the B2 climatic zone are made with an ACTS propagation terminal located in northeast Colorado. In order to gain more understanding about the physical processes that are responsible for Ka-band attenuation, the Colorado State University CHILL S-band polarimetric radar is used to take radar measurements along the slant path. The Colorado Front Range experiences a variety of weather conditions throughout the year ranging from upslope rain conditions to winter storms. Four such events measured along the slant path are illustrated in this paper. They include two convective cases and two "bright-band" cases. The S-band polarimetric radar data is used to initialize radar-based attenuation-prediction models, which are applied to the four precipitation events described. The comparisons of predicted attenuation to measured attenuation are quite good. It was also found during the course of the experiment that water droplets standing on the antenna surface can cause appreciable attenuation at Ka-band frequencies. That finding needs to be recognized in future model development and statistical analysis
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