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41.
Orr MT Wu J Fang M Sigal LJ Spee P Egebjerg T Dissen E Fossum S Phillips JH Lanier LL 《PloS one》2010,5(12):e15184
The CD94 transmembrane-anchored glycoprotein forms disulfide-bonded heterodimers with the NKG2A subunit to form an inhibitory receptor or with the NKG2C or NKG2E subunits to assemble a receptor complex with activating DAP12 signaling proteins. CD94 receptors expressed on human and mouse NK cells and T cells have been proposed to be important in NK cell tolerance to self, play an important role in NK cell development, and contribute to NK cell-mediated immunity to certain infections including human cytomegalovirus. We generated a gene-targeted CD94-deficient mouse to understand the role of CD94 receptors in NK cell biology. CD94-deficient NK cells develop normally and efficiently kill NK cell-susceptible targets. Lack of these CD94 receptors does not alter control of mouse cytomegalovirus, lymphocytic choriomeningitis virus, vaccinia virus, or Listeria monocytogenes. Thus, the expression of CD94 and its associated NKG2A, NKG2C, and NKG2E subunits is dispensable for NK cell development, education, and many NK cell functions. 相似文献
42.
Sébastien Nouaille Lucie Rault Sophie Jeanson Pascal Loubière Yves Le Loir Sergine Even 《Applied and environmental microbiology》2014,80(22):7028-7035
Staphylococcus aureus is a major cause of food poisoning outbreaks associated with dairy products, because of the ingestion of preformed enterotoxins. The biocontrol of S. aureus using lactic acid bacteria (LAB) offers a promising opportunity to fight this pathogen while respecting the product ecosystem. We had previously established the ability of Lactococcus lactis, a lactic acid bacterium widely used in the dairy industry, to downregulate a major staphylococcal virulence regulator, the accessory gene regulator (agr) system, and, as a consequence, agr-controlled enterotoxins. In the present paper, we have shown that the oxygen-independent reducing properties of L. lactis contribute to agr downregulation. Neutralizing lactococcal reduction by adding potassium ferricyanide or maintaining the oxygen pressure constant at 50% released agr downregulation in the presence of L. lactis. This downregulation still occurred in an S. aureus srrA mutant, indicating that the staphylococcal respiratory response regulator SrrAB was not the only component in the signaling pathway. Therefore, this study clearly demonstrates the ability of L. lactis reducing properties to interfere with the expression of S. aureus virulence, thus highlighting this general property of LAB as a lever to control the virulence expression of this major pathogen in a food context and beyond. 相似文献
43.
Le Maréchal C Hernandez D Schrenzel J Even S Berkova N Thiéry R Vautor E Fitzgerald JR François P Le Loir Y 《Journal of bacteriology》2011,193(9):2353-2354
Staphylococcus aureus is a major etiological agent of mastitis in ruminants. We report here the genome sequences of two ovine strains that were isolated from gangrenous (strain O11) and subclinical (strain O46) ewe mastitis. Both strains belong to the same clonal complex. Despite this close genotypic relationship, the two isolates were shown to reproducibly induce highly divergent types of infections, either severe (O11) or mild (O46) mastitis, in an experimental ewe model. 相似文献
44.
Two clusters of rat Nkrp1 genes can be distinguished based on phylogenetic relationships and functional characteristics. The proximal (centromeric)
cluster encodes the well-studied NKR-P1A and NKR-P1B receptors and the distal cluster, the largely uncharacterized, NKR-P1F
and NKR-P1G receptors. The inhibitory NKR-P1G receptor is expressed only by the Ly49s3+ NK cell subset as detected by RT-PCR, while the activating NKR-P1F receptor is detected in both Ly49s3+ and NKR-P1B+ NK cells. The mouse NKR-P1G ortholog is expressed by both NKR-P1D− and NKR-P1D+ NK cells in C57BL/6 mice. The rat and mouse NKR-P1F and NKR-P1G receptors demonstrate a striking, cross-species conservation
of specificity for Clr ligands. NKR-P1F and NKR-P1G reporter cells reacted with overlapping panels of tumour cell lines and
with cells transiently transfected with rat Clr2, Clr3, Clr4, Clr6 and Clr7 and mouse Clrc, Clrf, Clrg and Clrd/x, but not
with Clr11 or Clrb, which serve as ligands for NKR-P1 from the proximal cluster. These data suggest that the conserved NKR-P1F
and NKR-P1G receptors function as promiscuous receptors for a rapidly evolving family of Clr ligands in rodent NK cells. 相似文献
45.
Some leukocyte receptors come in groups of two or more where the partners share ligand(s) but transmit opposite signals. Some
of the ligands, such as MHC class I, are fast evolving, raising the problem of how paired opposing receptors manage to change
in step with respect to ligand binding properties and at the same time conserve opposite signaling functions. An example is
the KLRC (NKG2) family, where opposing variants have been conserved in both rodents and primates. Phylogenetic analyses of
the KLRC receptors within and between the two orders show that the opposing partners have been subject to post-speciation
gene homogenization restricted mainly to the parts of the genes that encode the ligand binding domains. Concerted evolution
similarly restricted is demonstrated also for the KLRI, KLRB (NKR-P1), KLRA (Ly49), and PIR receptor families. We propose
the term merohomogenization for this phenomenon and discuss its significance for the evolution of immune receptors. 相似文献
46.
47.
Vegard?Bruun?WyllerEmail author Even?Fagermoen Dag?Sulheim Anette?Winger Eva?Skovlund Jerome?Philip?Saul 《BioPsychoSocial medicine》2014,8(1):22
Background
Orthostatic intolerance is common in chronic fatigue syndrome (CFS), and several studies have documented an abnormal sympathetic predominance in the autonomic cardiovascular response to gravitational stimuli. The aim of this study was to explore whether the expectancies towards standing are contributors to autonomic responses in addition to the gravitational stimulus itself.Methods
A total of 30 CFS patients (12–18 years of age) and 39 healthy controls underwent 20° head-up tilt test and a motor imagery protocol of standing upright. Beat-to-beat cardiovascular variables were recorded.Results
At supine rest, CFS patients had significantly higher heart rate, diastolic blood pressure, and mean arterial blood pressure, and lower stroke index and heart rate variability (HRV) indices. The response to 20° head-up tilt was identical in the two groups. The response to imaginary upright position was characterized by a stronger increase of HRV indices of sympathetic predominance (power in the low-frequency range as well as the ratio low-frequency: high-frequency power) among CFS patients.Conclusions
These results suggest that in CFS patients expectancies towards orthostatic challenge might be additional determinants of autonomic cardiovascular modulation along with the gravitational stimulus per se.48.
Rune Aune Mentzoni Bj?rn S?trevik Helge Molde Nora Wiium J?rn Hetland Ida Fagerland Linn Tinnesand Nordnes Sunniva Straume Storemark Ingrid Nesdal Fossum St?le Pallesen 《PloS one》2014,9(10)
The use of nicotine in the form of “snus” is substantial and increasing in some geographic areas, in particular among young people. It has previously been suggested that addictions may operate through a mechanism of attentional bias, in which stimuli representative of the dependent substance increase in salience, thus increasing the addictive behavior. However, this hypothesis has not been tested for the case of snus. The current experiment used a modified Stroop task and a dot-probe task to investigate whether 40 snus users show an attentional bias towards snus-relevant stimuli, compared to 40 non-snus users. There were no significant differences between the two groups on reaction times or accuracy on either Stroop or dot-probe task, thus failing to show an attentional bias towards snus-relevant stimuli for snus users. This could imply that other mechanisms may contribute to maintenance of snus use than for other addictions. However, this is the first experimental study investigating attentional bias in snus users, and more research is warranted. 相似文献
49.
Even Fj?re Ulrike L. Aune Kristin R?en Alison H. Keenan Tao Ma Kamil Borkowski David M. Kristensen Guy W. Novotny Thomas Mandrup-Poulsen Brian D. Hudson Graeme Milligan Yannan Xi John W. Newman Fawaz G. Haj Bj?rn Liaset Karsten Kristiansen Lise Madsen 《The Journal of biological chemistry》2014,289(23):16032-16045
Chronic low grade inflammation is closely linked to obesity-associated insulin resistance. To examine how administration of the anti-inflammatory compound indomethacin, a general cyclooxygenase inhibitor, affected obesity development and insulin sensitivity, we fed obesity-prone male C57BL/6J mice a high fat/high sucrose (HF/HS) diet or a regular diet supplemented or not with indomethacin (±INDO) for 7 weeks. Development of obesity, insulin resistance, and glucose intolerance was monitored, and the effect of indomethacin on glucose-stimulated insulin secretion (GSIS) was measured in vivo and in vitro using MIN6 β-cells. We found that supplementation with indomethacin prevented HF/HS-induced obesity and diet-induced changes in systemic insulin sensitivity. Thus, HF/HS+INDO-fed mice remained insulin-sensitive. However, mice fed HF/HS+INDO exhibited pronounced glucose intolerance. Hepatic glucose output was significantly increased. Indomethacin had no effect on adipose tissue mass, glucose tolerance, or GSIS when included in a regular diet. Indomethacin administration to obese mice did not reduce adipose tissue mass, and the compensatory increase in GSIS observed in obese mice was not affected by treatment with indomethacin. We demonstrate that indomethacin did not inhibit GSIS per se, but activation of GPR40 in the presence of indomethacin inhibited glucose-dependent insulin secretion in MIN6 cells. We conclude that constitutive high hepatic glucose output combined with impaired GSIS in response to activation of GPR40-dependent signaling in the HF/HS+INDO-fed mice contributed to the impaired glucose clearance during a glucose challenge and that the resulting lower levels of plasma insulin prevented the obesogenic action of the HF/HS diet. 相似文献
50.
Species–area curves from islands and other isolates often differ in shape from sample‐area curves generated from mainlands or sections of isolates (or islands), especially at finer scales. We examine two explanations for this difference: (1) the small‐island effect (SIE), which assumes the species–area curve is composed of two distinctly different curve patterns; and (2) a sigmoid or depressed isolate species–area curve with no break‐points (in arithmetic space). We argue that the application of Ockham’s razor – the principle that the simplest, most economical explanation for a hypothesis should be accepted over less parsimonious alternatives – leads to the conclusion that the latter explanation is preferable. We hold that there is no reason to assume the ecological factors or patterns that affect the shapes of isolate (or island) curves cause two distinctly different patterns. This assumption is not required for the alternative, namely that these factors cause a single (though depressed) isolate species–area curve with no break‐points. We conclude that the theory of the small‐island effect, despite its present standing as an accepted general pattern in nature, should be abandoned. 相似文献