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21.
Chest wall motion during epidural anesthesia in dogs 总被引:3,自引:0,他引:3
To determine the relative contribution of rib cage and abdominal muscles to expiratory muscle activity during quiet breathing, we used lumbar epidural anesthesia in six pentobarbital sodium-anesthetized dogs lying supine to paralyze the abdominal muscles while leaving rib cage muscle motor function substantially intact. A high-speed X-ray scanner (Dynamic Spatial Reconstructor) provided three-dimensional images of the thorax. The contribution of expiratory muscle activity to tidal breathing was assessed by a comparison of chest wall configuration during relaxed apnea with that at end expiration. We found that expiratory muscle activity was responsible for approximately half of the changes in thoracic volume during inspiration. Paralysis of the abdominal muscles had little effect on the pattern of breathing, including the contribution of expiratory muscle activity to tidal breathing, in most dogs. We conclude that, although there is consistent phasic expiratory electrical activity in both the rib cage and the abdominal muscles of pentobarbital-anesthetized dogs lying supine, the muscles of the rib cage are mechanically the most important expiratory muscles during quiet breathing. 相似文献
22.
A human muscle adenine nucleotide translocator gene has four exons, is located on chromosome 4, and is differentially expressed 总被引:8,自引:0,他引:8
K Li C K Warner J A Hodge S Minoshima J Kudoh R Fukuyama M Maekawa Y Shimizu N Shimizu D C Wallace 《The Journal of biological chemistry》1989,264(24):13998-14004
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Cyclin D1 transgene impedes lymphocyte maturation and collaborates in lymphomagenesis with the myc gene. 总被引:26,自引:2,他引:24 下载免费PDF全文
S E Bodrug B J Warner M L Bath G J Lindeman A W Harris J M Adams 《The EMBO journal》1994,13(9):2124-2130
Cyclin D1 is the regulatory subunit of certain protein kinases thought to advance the G1 phase of the cell cycle. Deregulated cyclin D1 expression has been implicated in several human neoplasms, most consistently in centrocytic B lymphoma, where the cyclin D1 gene usually has been translocated to an immunoglobulin locus. To determine directly whether constitutive cyclin D1 expression is lymphomagenic, transgenic mice were generated having the cyclin D1 gene linked to an immunoglobulin enhancer. Despite abundant transgene expression, their lymphocytes were normal in cell cycle activity, size and mitogen responsiveness, but young transgenic animals contained fewer mature B- and T-cells. Although spontaneous tumours were infrequent, lymphomagenesis was much more rapid in mice that co-expressed the cyclin D1 transgene and a myc transgene than in mice expressing either transgene alone. Moreover, the spontaneous lymphomas of myc transgenic animals often ectopically expressed the endogenous cyclin D1 gene. These findings indicate that this G1 cyclin can modulate differentiation and collaborate with myc-like genes in oncogenesis. 相似文献
25.
Light-Dependent Tyrosine Phosphorylation in the Cyanobacterium Prochlorothrix hollandica 总被引:3,自引:0,他引:3 下载免费PDF全文
A light-dependent tyrosine kinase activity is present in soluble extracts from the cyanobacterium Prochlorothrix hollandica. The substrate of this tyrosine kinase activity is a soluble 88-kD protein that is phosphorylated when cultures of P. hollandica are adapted to high-light conditions. This phosphoprotein was identified by probing western blots of 32P-labeled soluble proteins from P. hollandica with an antibody specific for phosphotyrosine. This specificity was confirmed by competition experiments in which the antibody binding was abolished completely in the presence of excess phosphotyrosine but not phosphoserine and phosphothreonine. The kinetics of phosphorylation in vivo were determined by probing western blots with this antibody. Within 1 h following a switch from extended darkness to high light (200 [mu]mol photons m-2 s-1), the 88-kD protein was detectable upon India ink staining of western blots. After 3 h, the antibody recognized the phosphorylated form of this polypeptide. Within 6 h of a downshift from high to low light, the 88-kD protein was dephosphorylated. In vitro phosphorylation studies also showed that cell extracts can phosphorylate a tyrosine-containing artificial substrate; acid hydrolysis of both the artificial substrate and the 88-kD protein showed that phosphorylation occurred exclusively on tyrosine residues. Finally, experiments with high-light-adapted Synechococcus sp. PCC7942 suggest that a similar tyrosine phosphorylation event occurs in a phycobilisome-containing cyanobacterium. 相似文献
26.
Cloning and expression of a soluble sialidase from Chinese hamster ovary cells: sequence alignment similarities to bacterial sialidases 总被引:10,自引:2,他引:8
A cDNA encoding a soluble sialidase from Chinese hamster ovary(CHO) cells has been cloned and expressed. Completely degenerateoligonucleotide primers, which were based on the amino acidsequence of peptides obtained from the purified sialidase (Warneret al., Glycobiology, 3, 455463, 1993), and the polymerasechain reaction, with single-stranded cDNA template, were employedto generate a unique oligonucleotide probe. The unique probeof 93 bp was used for screening a 相似文献
27.
Anesthesia and chest wall function in dogs 总被引:4,自引:0,他引:4
28.
Isolation and properties of a soluble sialidase from the culture fluid of Chinese hamster ovary cells 总被引:3,自引:1,他引:2
Warner Thomas G.; Chang Joseph; Ferrari Jeff; Harris Reed; McNerney Thomas; Bennett Greg; Burnier John; Sliwkowski Mary B. 《Glycobiology》1993,3(5):455-463
A Soluble sialidase that can degrade recombinant glycoproteinsexpressed in Chinese hamster ovary (CHO) cells has been isolatedand purified to near homogeneity from the cell culture fluidof this host. Purification of 相似文献
29.
Stereoselectivity of the Chinese hamster ovary cell sialidase: sialoside hydrolysis with overall retention of configuration 总被引:1,自引:1,他引:0
The stereochemical course of enzymatic hydrolysis by the solublesialidase from Chinese hamster ovary cells, expressed as a recombinantprotein in insect Sf9 cells, was determined using proton nuclearmagnetic resonance spectroscopy. 4-Methyl umbelliferyl-N-acetylneuraminic acid was employed as substrate, and the stereoselectivityof the enzyme catalysis was ascertained by monitoring the H3axial and equatorial protons of the sialic acid product overthe reaction course. At both high (3 U) and low concentrations(1 U) of the enzyme, the alpha anomer of the sialic acid wasclearly observed as the initial reaction product. The correspondingbeta anomer of sialic acid appeared much later in the reaction,arising from mutarotation of the alpha anomer. Similar studieswere also carried out using the Salmonella typhimurium LT 2sialidase, a protein of similar size and substrate specificity.Both enzymes apparently cleave the alpha linked sialoside substratewith retention of configuration. Based on the observations ofa wide variety of other glycohydrolytic enzymes that have showna strong correlation of the stereoselectivity of catalysis withactive site topology (Gebler et al, J. Biol. Chem. 267, 1255912561,1992), the results obtained here suggest that the microbialand mammalian sialidases have a homologous active site architectureeven though the molecules do not share significant primary sequencesimilarities. sialidase NMR enzyme mechanism Chinese hamster 相似文献
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