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排序方式: 共有1331条查询结果,搜索用时 12 毫秒
31.
The Cretaceous superchron geodynamo: observations near the tangent cylinder 总被引:1,自引:0,他引:1 下载免费PDF全文
Tarduno JA Cottrell RD Smirnov AV 《Proceedings of the National Academy of Sciences of the United States of America》2002,99(22):14020-14025
If relationships exist between the frequency of geomagnetic reversals and the morphology, secular variation, and intensity of Earth's magnetic field, they should be best expressed during superchrons, intervals tens of millions of years long lacking reversals. Here we report paleomagnetic and paleointensity data from lavas of the Cretaceous Normal Polarity Superchron that formed at high latitudes near the tangent cylinder that surrounds the solid inner core. The time-averaged field recorded by these lavas is remarkably strong and stable. When combined with global results available from lower latitudes, these data define a time-averaged field that is overwhelmingly dominated by the axial dipole (octupole components are insignificant). These observations suggest that the basic features of the geomagnetic field are intrinsically related. Superchrons may reflect times when the nature of core-mantle boundary heat flux allows the geodynamo to operate at peak efficiency. 相似文献
32.
Simon Giroux Jinwang Xu T. Jagadeeswar Reddy Mark Morris KevinM. Cottrell Caroline Cadilhac James A. Henderson Oliver Nicolas Darius Bilimoria Francois Denis Nagraj Mani Nigel Ewing Rebecca Shawgo Lucille L’Heureux Subajini Selliah Laval Chan Nathalie Chauret Francoise Berlioz-Seux Mark N. Namchuk Anne-Laure Grillot Youssef L. Bennani Sanjoy K. Das John P. Maxwell 《ACS medicinal chemistry letters》2014,5(3):240-243
33.
34.
Optimising care of patients with chronic disease: patient‐oriented education may improve disease knowledge and self‐management 下载免费PDF全文
Brittany J. Ruffin W. Neil Cottrell Veronique S. Chachay Katharine M. Irvine Patricia C. Valery 《Internal medicine journal》2017,47(8):952-955
Many patients with chronic disease do not possess the knowledge and skills required to access and interpret appropriate health information. A pilot study in people with liver cirrhosis (n = 50) identified that only 54% of patients could recall being given written information by a clinician and 64% had self‐sought information, most commonly using the Internet. Many patients reported difficulties understanding the material and the majority wanted more accessible information. A pilot chronic disease educational booklet was well received by the study participants with 85% reporting it was helpful and 78% using it in between clinic appointments. 相似文献
35.
OBJECTIVE: To examine college athletic trainers' confidence in helping female athletes who have eating disorders. DESIGN AND SETTING: We mailed a 4-page, 53-item survey to head certified athletic trainers at all National Collegiate Athletic Association Division IA and IAA institutions (N = 236). A 2- wave mailing design was used to increase response rate. SUBJECTS: A total of 171 athletic trainers returned completed surveys for a response rate of 77%. Eleven institutions either did not identify their head athletic trainer or did not have an identifiable mailing address. Two surveys were undeliverable because of incorrect mailing addresses. MEASUREMENTS: The survey consisted of 4 subscales: (1) efficacy expectation, (2) outcome expectation, (3) outcome value, and (4) experience in dealing with eating disorders. Content validity was established by review from a national panel of experts. Reliability ranged from.66 to.73 for the subscales. RESULTS: Although virtually all athletic trainers (91%) had dealt with a female athlete with an eating disorder, only 1 in 4 (27%) felt confident identifying a female athlete with an eating disorder, and only 1 in 3 (38%) felt confident asking an athlete if she had an eating disorder. One in 4 athletic trainers (25%) worked at an institution that did not have a policy on handling eating disorders. Almost all athletic trainers (93%) felt that increased attention needs to be paid to preventing eating disorders among collegiate female athletes. CONCLUSIONS: Collegiate athletic programs are encouraged to develop and implement eating-disorder policies. Continuing education on the prevention of eating disorders among athletes is also strongly recommended. 相似文献
36.
Cottrell GA 《Pflügers Archiv : European journal of physiology》2005,450(3):168-177
A molecular biological approach was used to analyse the importance of different amino acids for ligand activation and for determining the action of amiloride on peptide- (Phe-Met-Arg-Phe-NH2, FMRFamide)-gated Na+ channels, members of the degenerin/epithelial Na channel (DEG/ENaC) family. Amiloride is a low-affinity blocker of most DEG/ENa channels, but has an unusual enhancing effect on responses of some of them. Chimeras were expressed in Xenopus oocytes and studied electrophysiologically. Differences in properties of channels from Helix aspersa and Helisoma trivolvis highlighted a sequence of 50 residues of the extracellular domain, near the first transmembrane segment (TM1), that affected sensitivity to FMRFamide, and whether amiloride blocked or enhanced the response to FMRFamide. Comparisons of chimeras prepared from H. aspersa and the extracellular domains of two other species, Aplysia californica and Lymnaea stagnalis and the preparation of further constructs, showed that amino acids 128–134 in the H. aspersa sequence are important in determining the predominant effect of amiloride and influencing the EC50 of FMRFamide. The results also showed that amino acids in this region are influenced by amino acids in other regions of the extracellular domain so as to affect not only the magnitude of responses, but also their time course and desensitisation. 相似文献
37.
Human MSH2 binds to trinucleotide repeat DNA structures associated with neurodegenerative diseases 总被引:5,自引:5,他引:5
The expansion of trinucleotide repeat sequences is associated with several
neurodegenerative diseases. The mechanism of this expansion is unknown but
may involve slipped-strand structures where adjacent rather than perfect
complementary sequences of a trinucleotide repeat become paired. Here, we
have studied the interaction of the human mismatch repair protein MSH2 with
slipped-strand structures formed from a triplet repeat sequence in order to
address the possible role of MSH2 in trinucleotide expansion. Genomic
clones of the myotonic dystrophy locus containing disease-relevant lengths
of (CTG)n x (CAG)n triplet repeats were examined. We have constructed two
types of slipped-strand structures by annealing complementary strands of
DNA containing: (i) equal numbers of trinucleotide repeats (homoduplex
slipped structures or S-DNA) or (ii) different numbers of repeats
(heteroduplex slipped intermediates or SI-DNA). SI-DNAs having an excess of
either CTG or CAG repeats were structurally distinct and could be separated
electrophoretically and studied individually. Using a band-shift assay, the
MSH2 was shown to bind to both S-DNA and SI-DNA in a structure- specific
manner. The affinity of MSH2 increased with the length of the repeat
sequence. Furthermore, MSH2 bound preferentially to looped-out CAG repeat
sequences, implicating a strand asymmetry in MSH2 recognition. Our results
are consistent with the idea that MSH2 may participate in trinucleotide
repeat expansion via its role in repair and/or recombination.
相似文献
38.
Incomplete rescue of cystic fibrosis transmembrane conductance regulator deficient mice by the human CFTR cDNA 总被引:2,自引:2,他引:2
Rozmahel R; Gyomorey K; Plyte S; Nguyen V; Wilschanski M; Durie P; Bear CE; Tsui LC 《Human molecular genetics》1997,6(7):1153-1162
We have used a mouse model to study the ability of human CFTR to correct
the defect in mice deficient of the endogenous protein. In this model,
expression of the endogenous Cftr gene was disrupted and replaced with a
human CFTR cDNA by a gene targeted 'knock-in' event. Animals homozygous for
the gene replacement failed to show neither improved intestinal pathology
nor survival when compared to mice completely lacking CFTR. RNA analyses
showed that the human CFTR sequence was transcribed from the targeted
allele in the respiratory and intestinal epithelial cells. Furthermore, in
vivo potential difference measurements showed that basal CFTR chloride
channel activity was present in the apical membranes of both nasal and
rectal epithelial cells in all homozygous knock-in animals examined. Ussing
chamber studies showed, however, that the cAMP-mediated chloride channel
function was impaired in the intestinal tract among the majority of
homozygous knock-in animals. Hence, failure to correct the intestinal
pathology associated with loss of endogenous CFTR was related to
inefficient functional expression of the human protein in mice. These
results emphasize the need to understand the tissue- specific expression
and regulation of CFTR function when animal models are used in gene therapy
studies.
相似文献
39.
Counselling dilemmas associated with the molecular characterisation of two Angelman syndrome families. 下载免费PDF全文
H L Gilbert J L Buxton C T Chan T McKay S Cottrell S Ramsden R M Winter M E Pembrey S Malcolm 《Journal of medical genetics》1997,34(8):651-655
We report the molecular characterisation of two families with Angelman syndrome referred for prenatal diagnosis, in which atypical molecular findings resulted in counselling dilemmas. The first is a familial case of Angelman syndrome in which the two affected children have mutations which affect the imprinting mechanism, as shown by the presence of paternal DNA methylation patterns at D15S63 and SNRPN and biparental inheritance of 15q11-q13 markers. DNA prepared from a 21 week fetal blood sample detected a fetus with normal maternal and paternal DNA methylation patterns at D15S63, but inheritance of the same maternal chromosome 15q11-q13 as the two affected sibs. This is probably a result of germline mosaicism in the mother. The second is a case of Angelman syndrome with an atypical deletion of 15q11-q13, which involves both unusual proximal and distal breakpoints. The deletion was characterised in order to assess the risk of Angelman syndrome in a second pregnancy in the mother of this child. 相似文献
40.
Airway eosinophilia and expression of interleukin-5 protein in asthma and in exacerbations of chronic bronchitis 总被引:6,自引:0,他引:6
M. SAETTA A. DI STEFANO P. MAESTRELLI G. TURATO CE. MAPP M. PIENO G. ZANGUOCHI G. DEL PRETE† L. M. FABBRI 《Clinical and experimental allergy》1996,26(7):766-774
Background An increased nutnber of eosinophils in the bronchial mucosa has been demonstrated both in asthma and in exacerbations of chronic bronchitis. Oiyective To investigate whether the airway eosinophilia present in asthma and in chronic bronchitis during exacerbations is associated with interleukin (IL)-5 protein expression in the bronchial mucosa. Methods We obtained bronchial biopsies in 18 subjects with asthma (four intrinsic, seven extrinsic and seven occupational) and in II subjects with chronic bronchitis examined during an exacerbation. The findings were compared wilh those of bronchial biopsies from 10 subjects with chronic bronchitis examined under baseline conditions and from seven normal subjects, taken as controls. By immunohistochemistry, we assessed the expression of IL-5 protein and the number of eosinophils (EG2), mast cells ftryptase), and T-lymphocytes (CD3) in the submucosa. Results As compared with controls, the number of eosinophils was increased to a similar degree in both asthma (P < 0.001) and in exacerbations of ehronic bronchitis (P < 0.001). whereas the number of I L-5 immunopositive cells was increased significantly only in asthma (P < 0.01). No diflerences were observed in the number of tnast cells and T-lymphocytes between the four groups of subjects examined. Conciusions This study shows that the degree of airway eosinophilia is similar in asthma and in exacerbations of ehronic bronchitis, but only in asthma is it associated with an increased expression of I L-5 protein in the bronchial tnucosa. 相似文献