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Our study was designed to examine how components of complex mixtures can
inhibit the binding of other components to receptor sites in the olfactory
system of the spiny lobster Panulirus argus. Biochemical binding assays
were used to study how two- to six-component mixtures inhibit binding of
the radiolabeled odorants taurine, L-glutamate and
adenosine-5'-monophosphate to a tissue fraction rich in dendritic membrane
of olfactory receptor neurons. Our results indicate that binding inhibition
by mixtures can be large and is dependent on the nature of the odorant
ligand and on the concentration and composition of the mixture. The binding
inhibition by mixtures of structurally related components was generally
predicted using a competitive binding model and binding inhibition data for
the individual components. This was not the case for binding inhibition by
most mixtures of structurally unrelated odorants. The binding inhibition
for these mixtures was generally smaller than that for one or more of their
components, indicating that complex binding interactions between components
can reduce their ability to inhibit binding. The magnitude of binding
inhibition was influenced more by the mixture's precise composition than by
the number of components in it, since mixtures with few components were
sometimes more inhibitory than mixtures with more components. These
findings raise the possibility that complex binding interactions between
components of a mixture and their receptors may shape the output of
olfactory receptor neurons to complex mixtures.
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43.
Ruth H. Striegel-Moore Denise E. Wilfley Melissa B. Caldwell Martha L. Needham Kelly D. Brownell 《Obesity (Silver Spring, Md.)》1996,4(2):109-116
Obesity is a significant health problem among black women in the United States. Black women are two to three times more likely than white women to be obese. The present study sought to examine race differences in attitudes and beliefs about dieting, motivations underlying dieting efforts, and actual dieting strategies and behaviors. To achieve this aim, a subset of female survey respondents (n = 324) was drawn from a pool of more than 20,000 subscribers to Consumer Reports. All survey respondents had made at least one dieting effort within 3 years of the time of the study. For this study, we used all black female respondents (n = 162) and a matched sample (i.e., matched on age, educational attainment, and personal income) of white women (n = 162). Black women did weigh significantly more than Caucasian women, therefore, BMI was used as a covariate in all subsequent analyses. Black and white women were significantly different in a number of domains. Compared to white women, black women experienced less social pressure about their weight, initiated dieting later in life, and were significantly less likely to diet at each developmental milestone. However, the two groups of women did not differ in reasons for undertaking their most recent dieting efforts, or in the types of weight loss strategies they had employed. Nor were there differences between the black and white women in methods for coping responses with dietary relapse or in rates of disordered eating. These findings are discussed in terms of their implications for both treatment and prevention of obesity in black women. 相似文献
44.
Noncontact dipole effects on channel permeation. III. Anomalous proton conductance effects in gramicidin 总被引:3,自引:2,他引:1 下载免费PDF全文
LR Phillips CD Cole RJ Hendershot M Cotten TA Cross DD Busath 《Biophysical journal》1999,77(5):2492-2501
Proton transport on water wires, of interest for many problems in membrane biology, is analyzed in side-chain analogs of gramicidin A channels. In symmetrical 0.1 N HCl solutions, fluorination of channel Trp(11), Trp-(13), or Trp(15) side chains is found to inhibit proton transport, and replacement of one or more Trps with Phe enhances proton transport, the opposite of the effects on K(+) transport in lecithin bilayers. The current-voltage relations are superlinear, indicating that some membrane field-dependent process is rate limiting. The interfacial dipole effects are usually assumed to affect the rate of cation translocation across the channel. For proton conductance, however, water reorientation after proton translocation is anticipated to be rate limiting. We propose that the findings reported here are most readily interpreted as the result of dipole-dipole interactions between channel waters and polar side chains or lipid headgroups. In particular, if reorientation of the water column begins with the water nearest the channel exit, this hypothesis explains the negative impact of fluorination and the positive impact of headgroup dipole on proton conductance. 相似文献
45.
Michael A. Friedman Denise E. Wilfley Kathleen M. Pike Ruth H. Striegel-Moore Judith Rodin 《Obesity (Silver Spring, Md.)》1995,3(1):57-62
This study investigated whether Body Mass Index (BMI) was associated with various aspects of psychological functioning in a sample of largely Caucasian adolescent girls. Three hundred sixty-five adolescent girls ranging from ages 14 through 19 were assessed for general psychological functioning utilizing the Symptom Checklist-90-Revised (SCL-90-R), and functioning specific to eating, shape and weight utilizing the Eating Disorders Inventory (EDI). Excess weight was associated with higher scores on the Bulimia, Body Dissatisfaction and Drive for Thinness subscales of the EDI. Excess weight was not, however, associated with general psychopathology or any of the subscales of the SCL-90-R. The results suggest that excess weight may carry risk for pathology specifically related to eating, shape and weight in adolescent girls, but not for general forms of psychopathology. 相似文献
46.
Mitochondrial DNA variation and genetic structure in populations of Drosophila melanogaster 总被引:5,自引:0,他引:5
The understanding of the genetic structure of a species can be improved by
considering together data from different types of genetic markers. In the
past, a number of worldwide populations of Drosophila melanogaster have
been extensively studied for several such markers, including allozymes,
chromosomal inversions, and quantitative characters. Here we present
results from a study of restriction- fragment-length polymorphisms of
mitochondrial DNA (mtDNA) in 92 isofemale lines from many of the same
geographic populations of D. melanogaster. Eleven restriction enzymes were
used, of which four revealed restriction-site polymorphism. A total of 24
different haplotypes were observed, of which 18 were unique to single
populations. In many populations, the unique haplotypes have reached high
frequency without being observed in neighboring populations. A Wagner
parsimony tree reveals that mutationally close variants show geographical
clumping, suggesting local differentiation of mtDNA in populations. The
Old-World and the New-World populations are differentiated, with the
predominant Old-World haplotype being virtually absent from the New World.
These results contrast with those for the nuclear genes, in which many loci
show parallel clines in different continents, and suggest a common origin
of D. melanogaster populations in North America.
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47.
The molecular organization of the beta-globin complex of the deer mouse, Peromyscus maniculatus 总被引:1,自引:0,他引:1
Padgett RW; Loeb DD; Snyder LR; Edgell MH; Hutchison CA d 《Molecular biology and evolution》1987,4(1):30-45
Recombinant DNA clones have been isolated that contain 80 kb of the
beta-globin complex from the deer mouse, Peromyscus maniculatus.
Comparisons of this complex with that from the laboratory mouse, Mus
domesticus (with an order 5'-Hbby, Hbb-bhO, Hbb-bhl, Hbb-bh2, Hbb-bh3,
Hbb-bl, Hbb-b2 3') highlight organizational trends in the beta-globin
complex since the two species diverged. Unlike other mammals studied thus
far, the deer mouse possesses three adult genes. Partial sequence analysis
indicates that each of the three adult genes is intact and hence may be
functional. Hybridization of one of the two Mus pseudogenes, Hbb-bh3, to
genomic blots from Peromyscus reveals that it has a homologous counterpart
in Peromyscus. Homologous genes to the two gamma-like Mus genes, Hbb-bhO
and Hbb-bhl, are also found in Peromyscus. The strong hybridization between
the Hbb-bhl genes and significant nucleotide similarity between the Hbb-bhO
genes suggest that both pairs are important for the ontogeny of these mice
although no known product has been identified for the Hbb-bhO genes. The
presence of Hbb-bhO and Hbb-bhl in Peromyscus suggests that the duplication
that created this related gene set occurred before the two lineages
diverged. A single gene for Hbb-y has been isolated from Peromyscus. The
adult region in Peromyscus has undergone significant divergence from the
same region in Mus, having three rather than two adult genes, the
acquisition of at least 15 kb of extra DNA relative to Mus, and possibly
the loss of the Hbb-bh2 pseudogene. The nonadult region of the complex, in
contrast, contains the same set of genes apparently distributed over the
same amount of DNA as in the Mus beta- globin complex. This observation
suggests that the embryonic region of the complex is more evolutionarily
stable than the adult region.
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48.
Sharon LR Simon Lise Lamoureux Margot Plews Michael Stobart Jillian LeMaistre Ute Ziegler Catherine Graham Stefanie Czub Martin Groschup J David Knox 《Proteome science》2008,6(1):23
Background
The bovine spongiform encephalopathy (BSE) epidemic and the emergence of a new human variant of Creutzfeldt-Jakob Disease (vCJD) have led to profound changes in the production and trade of agricultural goods. The rapid tests currently approved for BSE monitoring in slaughtered cattle are all based on the detection of the disease related isoform of the prion protein, PrPd, in brain tissue and consequently are only suitable for post-mortem diagnosis. Objectives: In instances such as assessing the health of breeding stock for export purposes where post-mortem testing is not an option, there is a demand for an ante-mortem test based on a matrix or body fluid that would permit easy access and repeated sampling. Urine and urine based analyses would meet these requirements. 相似文献49.
50.
Brian E. Saelens James F. Sallis Denise E. Wilfley Kevin Patrick John A. Cella Richard Buchta 《Obesity (Silver Spring, Md.)》2002,10(1):22-32
Objective: This study evaluates the post-treatment and short-term follow-up efficacy of, as well as participant satisfaction for, a 4-month behavioral weight control program for overweight adolescents initiated in a primary care setting and extended through telephone and mail contact. Research Methods and Procedures: 44 overweight adolescents were randomly assigned to either a multiple component behavioral weight control intervention (Healthy Habits [HH]; n = 23) or a single session of physician weight counseling (typical care [TC]; n = 21). Weight, height, dietary intake, physical activity, sedentary behavior, and problematic weight-related and eating behaviors and beliefs were assessed before treatment, after the 4-month treatment, and at 3-month follow-up. Participant satisfaction and behavioral skills use were measured. Results: HH adolescents evidenced better change in body mass index z scores to post-treatment than TC adolescents. Body mass index z scores changed similarly in the conditions from post-treatment through follow-up. Behavioral skills use was higher among HH than TC adolescents, and higher behavioral skills use was related to better weight outcome. Energy intake, percentage of calories from fat, physical activity, sedentary behavior, and problematic weight-related or eating behaviors/beliefs did not differ by condition or significantly change over time independent of condition. The behavioral intervention evidenced good feasibility and participant satisfaction. Discussion: A telephone- and mail-based behavioral intervention initiated in primary care resulted in better weight control efficacy relative to care typically provided to overweight adolescents. Innovative and efficacious weight control intervention delivery approaches could decrease provider and participant burden and improve dissemination to the increasing population of overweight youth. 相似文献