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Nonenzymatic reduction of dehydroascorbate into ascorbate by the reduced form (quinol form) of 2-amino-3-carboxy-1,4-naphthoquinone, a strong growth stimulator for bifidobacteria, has been found. The bimolecular reaction rate constant was evaluated as 9 M(-)(1) s(-)(1) at pH 7.0. This reaction has been successfully coupled with enzymatic regeneration of the naphthoquinol by NAD(P)H in cell-free extracts of Bifidobacterium longum 6001. The overall reaction is a regeneration of NAD(P)(+) by dehydroascorbate [or a regeneration of ascorbate by NAD(P)H], in which the naphthoquinone/quinol redox couple functions as an electron transfer mediator. Kinetic study of the reduction of dehydroascorbate with related quinol compounds suggested the significance of the amino substituent of the naphthoquinol. A mechanism of the electron transfer from the quinol to dehydroascorbate is proposed, where the first step of the reaction is a nucleophilic addition of the C(2)-amino substituent of the naphthoquinol to the C(2)-position of dehydroascorbate to form a Schiff base intermediate.  相似文献   
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Dendritic cells (DCs) are professional antigen presenting cells, which initiate primary immune responses and also play an important role in the generation of peripheral tolerance. There is no reliable method established for the isolation of bovine peripheral blood DCs, and furthermore, the phenotypes and the functions of bovine DCs are still not fully clear. In the present study, we have attempted to identify bovine peripheral blood DCs by negative-selection. In bovine peripheral blood mononuclear cells (PBMC), we have newly characterized the phenotype of DCs, which is CD11c+/CD172a+. These cells display features of myeloid type DCs. In the thymic medulla, CD11c+/CD172a+ cells were also present and CD1+/CD172a+ cells were additionally detected as a population of DCs. The data suggest that one of the bovine DCs phenotypes from PBMC is derived from myeloid lineages lacking a CD1 molecule, which then drift to several tissues, and that they then may express a CD1 molecule upon their functional differentiation.  相似文献   
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Carnosine (β‐alanyl‐L‐histidine) and its derivative anserine (β‐alanyl‐1‐methyl‐L‐histidine) are present in high concentrations in the muscle and brain of chickens. They are known as antioxidants and putative neurotransmitters in the brain. If administration of β‐alanine (β‐Ala), one of the constituents of carnosine, could increase the concentrations of these dipeptides in the brain and muscles, it could improve brain function and increase the commercial value of the meat in chickens. As an early step in investigating this hypothesis, in the present study, the effect of dietary β‐Ala on these dipeptide concentrations in the brain, Musculus pectoralis superficialis, Musculus pectoralis profundus and Musculus biceps femoris was investigated in broilers. Four‐week‐old broilers were given a commercial diet or diet containing 0.5, 1 or 2%β‐Ala for 4 weeks. At the end of the experiment, concentrations of both dipeptides were increased in the brain, while taurine concentration was decreased. In the muscles, concentrations of these dipeptides were unchanged. These results indicate that dietary β‐Ala might influence brain function, but is ineffective in increasing the concentrations of carnosine and anserine in the muscles of broilers.  相似文献   
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M cells play a central role in the initiation of mucosal immune responses. However, a primary source of difficulty for investigations of this is the lack of an available specific marker for bovine M cells. As M cells possess irregular and short microvilli, we investigated the distribution and localization of the microvillar proteins actin and villin by immunohistochemistry of the gut of calves. In ileum of the calf, actin and villin were clearly and continuously immunostained in the brush border of the villous epithelia, however, discontinuous immunostaining with patches of no staining were observed in follicle-associated epithelium (FAE). Electron microscopy revealed that M cells had irregular microvilli and lacked the typical brush border, and it was inferred that these patches of no staining might be the intercellular crevices of M cells. As the microvilli of M cells were very sparse, there were several areas of weak immunostaining in calf jejunal FAE. These results suggest that M cells in calf FAE are detectable by the absence of staining for actin and villin.  相似文献   
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The effects of various selective phosphodiesterase (PDE) inhibitors on carbachol (CCh)-induced contraction in the bovine abomasum were investigated. Various selective PDE inhibitors, vinpocetine (type 1), erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA, type 2), milrinone (type 3), Ro20-1724 (type 4), vardenafil (type 5), BRL-50481 (type 7) and BAY73-6691 (type 9), inhibited CCh-induced contractions in a concentration-dependent manner. Among the PDE inhibitors, Ro20-1724 and vardenafil induced more relaxation than the other inhibitors based on the data for the IC50 or maximum relaxation. In smooth muscle of the bovine abomasum, we showed the expression of PDE4B, 4C, 4D and 5 by RT-PCR analysis. In the presence of CCh, Ro20-1724 increased the cAMP content, but not the cGMP content. By contrast, vardenafil increased the cGMP content, but not the cAMP content. These results suggest that Ro20-1724-induced relaxation was correlated with cAMP and that vardenafil-induced relaxation was correlated with cGMP in the bovine abomasum. In conclusion, PDE4 and PDE5 are the enzymes involved in regulation of the relaxation associated with cAMP and cGMP, respectively, in the bovine abomasum.  相似文献   
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Oral examination of two guinea pigs revealed that the unilateral incisor was absent. On radiographic examination, the incisor was identified within the nasal cavity in both patients. Under anesthesia in both patients, the skin was incised from the nostril to 1.5 cm proximal, and the premaxilla and part of the maxilla were exposed. The bone was removed using a surgical drill, and the incisor was exposed in the nasal cavity. The root was grasped with forceps and carefully extracted as it was degraded and very fragile. Diagnosis was easy using oral and radiographic examination. In guinea pig patients where an incisor is absent on oral examination, this condition should be considered.  相似文献   
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The monospecific antibody directed against cytokeratin 18 consistently immunostained microfold cells (M‐cells) in the ileum epithelium of pigs. In adult pigs, M‐cells were numerously distributed in the dome epithelium overlying Peyer's patches, especially in the crypt epithelium to the lower dome epithelium. The M‐cells presented in the crypt epithelium were mostly columnar in shape and showed a gradual transition from columnar cells to pocket‐like cells as they drew near the lower dome epithelium. In contrast, the M‐cells that were sporadically located in the villus epithelium were all columnar and similar to enterocytes in shape. In newborn pigs, a few M‐cells were observed only in the infant dome epithelium, which were all columnar resembling the enterocytes. Of the 19 lectins used, the dome epithelial cells were selectively stained by lectins from Ulex europaeus‐I and Anguuilla anguilla. Especially, the M‐cells were stained by lectin from Anguuilla anguilla although the intensity varied on individual pigs. Lymphoid follicles in the lamina propria were well developed in the adults compared to these in the newborns, and lymphoid cells were more populated in the lower part than the upper part of the dome. The present results provide available information to understand the differentiation and functional heterogeneity of porcine M‐cells.  相似文献   
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