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1.
R E Callard K P Rigley S H Smith S Thurstan J G Shields 《Journal of immunology (Baltimore, Md. : 1950)》1992,148(10):2983-2987
The regulation of human B cell proliferation and differentiation by the CD19 surface glycoprotein was investigated. As expected, proliferation induced by costimulation with anti-IgM plus IL-4 or IL-2, or with G28.8 antibody plus IL-4 was inhibited by antibody ligation of CD19. In contrast, proliferation of tonsillar B cells to mitogenic doses of PMA (5 ng/ml) or to EBV were enhanced, and proliferation of B cell lines to BCGF(low) was unaffected. Similarly, specific antibody responses by tonsillar B cells to influenza virus, and Ig secretion by the CESS lymphoblastoid cell line in response to IL-6 were inhibited, whereas polyclonal Ig production in response to EBV was enhanced. These results show that human B cell responses may be inhibited or enhanced by CD19 depending on the stimulating signal used. The difference in response to CD19 ligation did not depend on whether proliferation or differentiation was being measured, or whether stimulation was by surface Ig. In experiments using PMA as a T cell independent mitogen, it was found that ligation of CD19 inhibited proliferation of B cells costimulated with low doses of PMA plus G28.5 (CD40) antibody, but enhanced the response to higher (mitogenic) doses with or without costimulation with G28.5. The change from inhibition to enhancement occurred over a very small increase in PMA dose (0.5-1.0 ng/ml) that corresponded exactly to the lowest dose required for mitogenic activity. Finally, we showed that CD19 ligation inhibited the increase in surface expression of CD23, but not IgM, induced by IL-4, showing that CD19 ligation can have opposed effects on different responses to the same signal. Together our results suggest that CD19 activation of human B cells interacts with other signaling events to enhance or inhibit the subsequent response. 相似文献
2.
Mallikarjun S Beelagi SR Santosh Kumar Uma Bharathi Indrabalan Sharanagouda S Patil Ashwini Prasad KP Suresh Shiva Prasad Kollur Veeresh Santhebennur Jayappa Siddappa B Kakkalameli Chandrashekar Srinivasa Prabhakarareddy Anapalli Venkataravana Chandan Shivamallu 《Bioinformation》2021,17(4):479
Crimean-Congo hemorrhagic fever (CCHF) virus is one among the major zoonosis viral diseases that use the Hyalomma ticks as their transmission vector to cause viral infection to the human and mammalian community. The fatality of infectious is high across the world especially in Africa, Asia, Middle East, and Europe. This study regarding codon usage bias of S, M, and L segments of the CCHF virus pertaining to the host Homo sapiens, reveals in-depth information about the evolutionary characteristics of CCHFV. Relative Synonymous Codon Usage (RSCU), Effective number of codons (ENC) were calculated, to determine the codon usage pattern in each segment. Correlation analysis between Codon adaptation index (CAI), GRAVY (Hydrophobicity), AROMO (Aromaticity), and nucleotide composition revealed bias in the codon usage pattern. There was no strong codon bias found among any segments of the CCHF virus, indicating both the factors i.e., natural selection and mutational pressure shapes the codon usage bias. 相似文献
3.
Paulo HG Mansur Lacordaire KP Cury José OB Leite Adriano A Pereira Nilson Penha-Silva Adriano O Andrade 《Biomedical engineering online》2010,9(1):29
Background
The main problem of tremor is the damage caused to the quality of the life of patients, especially those at more advanced ages. There is not a consensus yet about the origins of this disorder, but it can be examined in the correlations between the biological signs of aging and the tremor characteristics. 相似文献4.
Csönge L Bravo D Newman-Gage H Rigley T Conrad EU Bakay A Strong DM Pellet S 《Cell and tissue banking》2002,3(3):161-168
One of the most important factors concerning the successful clinical outcome after transplantation of osteochondral allografts
is the viability of the cartilage.The viability of cryopreserved cartilage is quite poor, 20–30% cell survival has been published.
The purpose of this study was to develop a new storage method which improves the chondrocyte viability. The talus of cadaveric
donors was used as a model tissue to compare human osteochondral allograft cartilage viability following cryopreservation
with that remaining after prolonged refrigerated storage. Full-thickness cartilage punch biopsies had been cryopreserved,
and tali were divided into two matched groups and stored in TCM for 60 days at +4 °C, either with or without regular medium
replacement. The cartilage of each graft was biopsied and assayed for viability on every third day by the MTT reduction assay.
During 4 °C storage, a recurring pattern of large fluctuations in apparent cartilage viability was observed in every stored
graft, with or without medium replacement. These fluctuations did not appear in control specimens of either fresh or cryopreserved
human skin that were assayed in parallel with the cartilage biopsies, so the viability fluctuation seems an intrinsic property
of the cartilage in these conditions. Cartilage stored for 60 days at +4 °C showed significantly higher viability (35.2 ±
3.3 %) than fresh cartilage that had been cryopreserved (21.6 ± 1.8 %). This was true even when cryopreserved and thawed cartilage
was subjected to a 3 day post thaw incubation under presumably favorable conditions (17.7 ± 1.6 %). These viability assay
results, (reflective of intracellular metabolic activity), were corroborated by the fluorescent dye mixture SYTO-16 and propidium
iodide. The data indicate that long-term stored refrigerated cartilage appears to retain a viability higher than that of cryopreserved
cartilage for up to and perhaps beyond 60 days of storage. There was no viability index difference between the medium replaced
and non-replaced groups. Although an exceptional result, in one individual case, more than 65% viable cells could be detected
in the talar cartilage after 60 days storage at +4 °C.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
Cross-linking of surface immunoglobulin on B lymphocytes induces both intracellular Ca2+ release and Ca2+ influx: analysis with indo-1 总被引:11,自引:0,他引:11
M K Bijsterbosch K P Rigley G G Klaus 《Biochemical and biophysical research communications》1986,137(1):500-506
The new Ca2+-probe indo-1 has a high fluorescence intensity, which allows low intracellular dye loadings. Stimulation of indo-1-loaded mouse B cells with anti-Ig antibodies provoked rapid rise of free cytoplasmic Ca2+ from 100 nM to greater than 1 microM, followed by a decline to a plateau at 300-400 nM. The initial rapid rise was not detected in quin2-loaded cells, presumably due to the Ca2+-buffering effects of the dye. The sustained Ca2+ increase was due to influx, whereas the initial rise was caused by release from intracellular stores. The magnitudes of Ca2+ release and inositol trisphosphate release were closely correlated. Concanavalin A does not provoke inositol trisphosphate release in mouse B cells. It did not induce a rapid initial Ca2+ rise in indo-1-loaded B cells either, but only a sustained increase to 200-300 nM. Finally, Ca2+ influx induced by both anti-Ig and concanavalin A were not affected by membrane depolarization. 相似文献
6.
7.
In wetlands the effects of fire on vegetation dynamics are somewhat uncertain. A change detection analysis in the herbaceous wetlands of KwaMbonambi, South Africa, which were subject to frequent fires, revealed that in 1937 the study area comprised grassland (69%), herbaceous wetland (25%), indigenous swamp forest (4%) and tree plantations (1%). However, by 1970, tree plantations occupied 78% of the landscape and grasslands and herbaceous wetlands had declined to 9% and 6%, respectively, whereas indigenous swamp forest had increased to 6%. By 2009 tree plantations had been removed from the wetland areas. Despite this opportunity for herbaceous wetlands to recover their historical extent, they decreased to only 2%, mostly changing to indigenous swamp forest or to an herbaceous/fern (Stenochlaena tenuifolia)/woodland mosaic. Fire records showed suppression of fire to be an important contributing factor, particularly in wetlands that had been disturbed by tree plantations, although subsequently removed. A pilot burning experiment revealed that S. tenuifolia did not inhibit fire. It is therefore practicable to increase fire frequency to prevent the mosaic developing into forest. A conceptual model of the influence of fire regime on wetland vegetation type is presented and priorities for further research on wetlands and fire are recommended. 相似文献
8.
Thalidomide attenuates nitric oxide mediated angiogenesis by blocking migration of endothelial cells
KP Tamilarasan Gopi Krishna Kolluru Megha Rajaram M Indhumathy R Saranya Suvro Chatterjee 《BMC cell biology》2006,7(1):17-13
Background
Thalidomide is an immunomodulatory agent, which arrests angiogenesis. The mechanism of anti-angiogenic activity of thalidomide is not fully understood. As nitric oxide is involved in angiogenesis, we speculate a cross-talk between thalidomide and nitric oxide signaling pathway to define angiogenesis. The aim of present study is to understand the mechanistic aspects of thalidomide-mediated attenuation of angiogenesis induced by nitric oxide at the cellular level. 相似文献9.
The fruit fly, Drosophila melanogaster, innately avoids even low levels of CO2. CO2 is part of the so-called Drosophila stress odor produced by stressed flies, but also a byproduct of fermenting fruit, a main food source, making the strong avoidance behavior somewhat surprising. Therefore, we addressed whether feeding states might influence the fly’s behavior and processing of CO2. In a recent report, we showed that this innate behavior is differentially processed and modified according to the feeding state of the fly. Interestingly, we found that hungry flies require the function of the mushroom body, a higher brain center required for olfactory learning and memory, but thought to be dispensable for innate olfactory behaviors. In addition, we anatomically and functionally characterized a novel bilateral projection neuron connecting the CO2 sensory input to the mushroom body. This neuron was essential for processing of CO2 in the starved fly but not in the fed fly. In this Extra View article, we provide evidence for the potential involvement of the neuromodulator dopamine in state-dependent CO2 avoidance behavior. Taken together, our work demonstrates that CO2 avoidance behavior is mediated by alternative neural pathways in a context-dependent manner. Furthermore, it shows that the mushroom body is not only involved in processing of learned olfactory behavior, as previously suggested, but also in context-dependent innate olfaction. 相似文献
10.
Csönge L Bravo D Newman-Gage H Rigley T Conrad EU Bakay A Strong DM Pellet S 《Cell and tissue banking》2002,3(3):151-159
The aim of this study was to adapt a reliable, reproducible and simple viability assay for cartilage and osteochondral studies.
The previous assays (radioisotope uptake, assessment of matrix components, histological methods, oxygen consumption etc.)
were complex, laborious, time consuming or suffer from difficulty of interpretation. MTT assay was chosen because it has been
widely and successfully used in different cell and tissue studies, but has not been published on human solid articular cartilage.
Fresh intact cartilage samples of human tali were tested to investigate the assay. The reliability of the MTT assay was also
tested by an fluorescent dye combination. The MTT assay is based on the production of purple formazan pigment from methyltetrazolium
salt by the mitochondrial enzymes of viable chondrocytes. The enzyme kinetics of the reaction was also investigated because
it was unknown in the case of cartilage. The amount of pigment formed can be measured by spectrophotometry after extraction
by methyl cellosolve. The color density is proportional to mitochondrial enzyme activity, reflecting the number of viable
chondrocytes. The optimal reagent concentration, biopsy size, and incubation period were established. There is a linear relationship
between the cartilage weight and the pigment production activity. A 9.8% nonspecific raction was observed in the negative
controls. The enzyme kinetics of the reaction was also investigated. The MTT clevage up to 0.1% (w/v) follows the Michaelis
kinetics. We calculated the Michaelis constant (2835 ± 130 μM), the maximal velocity (36 ± 3.2 × 10−5μMsec−1) and the velocity constant (1.27 ± 0.2 × 10−7sec−1) of the reaction. The latter is a significant marker for each tissue type. The viability of cartilage was also assessed and
calculated by a fluorescent dye combination comprising 1 μg/ml propidium iodide (PI) and 4 μM/ml SYTO-16 stains. The PI stains
dead cells (red fluorescence), the SYTO-16 stains live cells (green fluorescence). The staining can be visualised simultaneously,
and the live/dead ratio can be calculated by image analysis software from saved image files. The MTT assay is a simple, non-expensive,
efficient, reliable, reproducible, sensitive viability test for cartilage studies. The MTT reduction assay and the staining
method were corrobative.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献