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51.
A plasma dexamethasone radioimmunoassay 总被引:2,自引:0,他引:2
A double antibody radioimmunoassay for estimation of plasma dexamethasone is reported. Dexamethasone antiserum was produced by immunization of rabbits with dexamethasone-3-carboxymethyloxime-bovine serum albumin conjugate. All the endogenous steroids tested cross reacted less than 1%. Cortisol with a cross reaction of 0.4% gave significant interference in some plasma samples. This Interference could be removed by chromatography. The recoveries of dexamethasone added to plasma and corrected for procedural losses were 99 ± 9% after dichloromethane extraction and 98 ± 10% after paper chromatography. After dichloromethane extraction and after paper chromatography, the intraassay and inter-assay coefficients of variation were less than 11%. The peak dexamethasone levels were observed between 30 and 60 minutes after a single 1 mg oral dose in two normal subjects. The half-times of disappearance from plasma were 4 and 4.5 hours. During a constant infusion (50 μg/70 kg BW/hr) of dexamethasone phosphate, the plasma dexamethasone level reached a level of 250 ng/dl at 8 hours. It is concluded that plasma dexamethasone levels after either oral or intravenous administration may be measured specifically by radioimmunoassay. 相似文献
52.
Liu W Brayton KA Davis WC Mansfield K Lagerquist J Foreyt W Srikumaran S 《Journal of wildlife diseases》2007,43(1):75-81
Pneumonia caused by Mannheimia (Pasteurella) haemolytica is a highly fatal disease of bighorn sheep (Ovis canadensis). Leukotoxin (Lkt), secreted by M. haemolytica, is an important virulence factor of this organism, and is cytolytic to bighorn sheep leukocytes. Previously, we have shown that CD18, the beta subunit of beta2 integrins, serves as the receptor for Lkt on bovine leukocytes. Furthermore, anti-CD18 antibodies inhibit Lkt-induced cytotoxicity of bighorn sheep leukocytes. Therefore, we hypothesized that Lkt utilizes CD18 as its receptor on bighorn sheep leukocytes. Confirmation of bighorn sheep CD18 as a receptor for Lkt requires the demonstration that the recombinant expression of bighorn sheep CD18 in Lkt-nonsusceptible cells renders them susceptible to Lkt. Therefore, we transfected cDNA encoding CD18 of bighorn sheep into a Lkt-nonsusceptible murine cell line. Cell surface expression of bighorn sheep CD18 on the transfectants was tested by flow cytometry with anti-CD18 antibodies. Transfectants stably expressing bighorn sheep CD18 on their surface were subjected to flow cytometric analysis for detection of Lkt binding, and cytotoxicity assays for detection of Lkt-induced cytotoxicity. Leukotoxin bound to the transfectants. More importantly, the transfectants were effectively lysed by Lkt in a concentration-dependent manner, whereas the parent cells were not. These results clearly indicate that M. haemolytica Lkt utilizes CD18 as a receptor on bighorn sheep leukocytes. Identification of CD18 as a receptor for Lkt on bighorn sheep leukocytes should enhance our understanding of the pathogenesis of pneumonia, which in turn should help in the development of control measures against this fatal disease of bighorn sheep. 相似文献
53.
The purpose of this study was to examine the effects of a 5-wk unilateral, isometric strength-training program on plasticity in the spinal Hoffmann (H-) reflex in both the trained and untrained legs. Sixteen participants, 22-42 yr old, were assigned to either a control (n = 6) or an exercise group (n = 10). Both groups were tested for plantar flexion maximal voluntary isometric contractions (MVIC) and soleus H-reflex amplitude in both limbs, at the beginning and at the end of a 5-wk interval. Participants in the exercise group showed significantly increased MVIC in both legs after training (P < 0.05), whereas strength was unchanged in the control group for either leg. Subjects in the exercise group displayed increased (P < 0.05) H-reflex amplitudes on the ascending limb of the recruitment curve (at an equivalent M wave of 5% of the maximal M wave, H(A)) only in the trained leg. Maximal H-reflex and M-wave remained unchanged with training. Increased amplitude of H(A) in the trained limb concurrent with increased strength suggests that spinal mechanisms may underlie the changes in strength, possibly because of increased alpha-motoneuronal excitability or reduced presynaptic inhibition. Despite a similar increase in strength in the contralateral limb of the exercise group, H(A) amplitude was unchanged. We conclude that the cross-education effect of strength training may be due to supraspinal to a greater extent than spinal mechanisms. 相似文献
54.
A method for the glycosylation of anthracyclines featuring benzoylated imidate donors has been developed and utilized in the synthesis of glycosylated 4-deoxy-ε-rhodomycinone derivatives. Due to its high efficiency, regioselectivity, stereoselectivity, and operational simplicity, the method should prove valuable to researchers working with glycosylation of tetracyclic compounds. 相似文献
55.
Tag retention,wound healing,and subsequent reproductive history of southern right whales following satellite‐tagging 下载免费PDF全文
This paper presents data from 48 resightings of 16 southern right whales that were satellite‐tagged on the South African coast in September 2001, up to and including 2012. Tag performance in terms of number of days with locations received was significantly higher in males than females, and lowest in cows with calves, and attributed to behavioral differences leading to variable degrees of antenna damage. Resightings occurred from 4 to 4,054 d after tagging: tags were retained in all whales seen within 27 mo, but were apparently shed in all but one individual seen within 36 mo of tagging. The exception was a whale that still had the tag present 11 yr after tagging. Healing at the tag site occurred gradually and within 5 yr of tagging (and 2 yr after tag shedding). No significant difference in the subsequent frequency of calving was detected between 12 tagged and 382 untagged females photographed contemporaneously, and although statistical power was low, a 21% or greater reduction in calving rate in tagged females would seem incompatible with the observations. The death of one female 3 yr after tagging was more likely attributable to a ship strike on an animal debilitated by a prolapsed uterus. 相似文献
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57.
Background
Modelling proteins with multiple domains is one of the central challenges in Structural Biology. Although homology modelling has successfully been applied for prediction of protein structures, very often domain-domain interactions cannot be inferred from the structures of homologues and their prediction requiresab initiomethods. Here we present a new structural prediction approach for modelling two-domain proteins based on rigid-body domain-domain docking. 相似文献58.
Immobilized-biomembrane affinity chromatography for binding studies of membrane proteins 总被引:1,自引:0,他引:1
Gottschalk I Lagerquist C Zuo SS Lundqvist A Lundahl P 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2002,768(1):31-40
Analyses of specific interactions between solutes and a membrane protein can serve to characterize the protein. Frontal affinity chromatography of an interactant on a column containing the membrane protein immobilized in a lipid environment is a simple and robust approach for series of experiments with particular protein molecules. Regression analysis of the retention volumes at a series of interactant concentrations shows the affinity of the protein for the interactant and the amount of active binding sites. The higher the affinity, the fewer sites are required to give sufficient retention. Competition experiments provide the affinities of even weakly binding solutes and the non-specific retention of the primary interactant. Hummel and Dreyer size-exclusion chromatography allows complementary analyses of non-immobilized membrane materials. Analyses of the human facilitative glucose transporter GLUT1 by use of the inhibitor cytochalasin B (radioactively labeled) and the competitive substrate D-glucose (non-labeled) showed that GLUT1 interconverted between two states, exhibiting one or two cytochalasin B-binding sites per two GLUTI monomers, dependent on the membrane composition and environment. Similar analyses of a nucleoside transporter, a photosynthetic reaction center, nicotinic acetylcholine receptors and a P-glycoprotein, alternative techniques, and immobilized-liposome chromatographic approaches are presented briefly. 相似文献
59.
I Christopher McManus Hannah M Mitchison Eddie MK Chung Georgina F Stubbings Naomi Martin 《BMC pulmonary medicine》2003,3(1):1-12
Background
Although the pathophysiological defect in primary ciliary dyskinesia (PCD; Siewert's / Kartagener's syndrome) is now well characterised, there are few studies of the impact of the condition upon health function, particularly in later life. This study assesses the health impact of the condition in a large group of patients. In addition, it assesses the similarity in age of diagnosis, symptoms and problems of those with situs inversus (PCD-SI) and those with situs solitus (PCD-SS).Methods
Postal questionnaire sent to members of the UK Primary Ciliary Dyskinesia Family Support Group. The questionnaire contained the St. George's Respiratory Questionnaire (SGRQ) and the SF-36 questionnaire for assessing health status.Results
93 questionnaires were returned, representing a 66% response rate. Replies were received from similar numbers of PCD-SI and PCD-SS. Individuals with PCD-SI did not show a significant tendency to be diagnosed earlier, and neither did they show any difference in their symptoms, or the relationship of symptoms to age. Respiratory symptoms were fairly constant up until the age of about 25, after which there was a slow increase in symptoms, and a decline in health status, patients over the age of 40 being about one and a half standard deviations below the mean on the physical component score of the PCS. Patients diagnosed earlier in life, and hence who had received more treatment for their condition, had better scores on the SGRQ Impact and Activity scores.Conclusions
PCD is a chronic condition which has a progressively greater impact on health in the second half of life, producing significant morbidity and restriction of life style. Early diagnosis, and hence earlier treatment, may improve symptoms and the impact of the condition. 相似文献60.
Cecilia Engdahl Anna E B?rjesson Huamei F Forsman Annica Andersson Alexandra Stubelius Andree Krust Pierre Chambon Ulrika Islander Claes Ohlsson Hans Carlsten Marie K Lagerquist 《Arthritis research & therapy》2014,16(4):R150