Tight junctions are an intercellular adhesion complex of epithelial and endothelial cells, and form a paracellular barrier
that restricts the diffusion of solutes on the basis of size and charge. Tight junctions are formed by multiprotein complexes
containing cytosolic and transmembrane proteins. How these components work together to form functional tight junctions is
still not well understood and will require a complete understanding of the molecular composition of the junction. 相似文献
The effects of selective ibotenate lesions of the complete hippocampus (CHip), the hippocampal ventral pole (VP), or the medial prefrontal cortex (mPFC) in male rats were assessed on several measures related to energy regulation (i.e., body weight gain, food intake, body adiposity, metabolic activity, general behavioral activity, conditioned appetitive responding). The testing conditions were designed to minimize the nonspecific debilitating effects of these surgeries on intake and body weight. Rats with CHip and VP lesions exhibited significantly greater weight gain and food intake compared with controls. Furthermore, CHip-lesioned rats, but not rats with VP lesions, showed elevated metabolic activity, general activity in the dark phase of the light-dark cycle, and greater conditioned appetitive behavior, compared with control rats without these brain lesions. In contrast, rats with mPFC lesions were not different from controls on any of these measures. These results indicate that hippocampal damage interferes with energy and body weight regulation, perhaps by disrupting higher-order learning and memory processes that contribute to the control of appetitive and consummatory behavior. 相似文献
This study is a geographically systematic genetic survey of the easternmost
subspecies of chimpanzee, Pan troglodytes schweinfurthii. DNA was
noninvasively collected in the form of shed hair from chimpanzees of known
origin in Uganda, Rwanda, Tanzania, and Zaire. Two hundred sixty-two DNA
sequences from hypervariable region 1 of which of the mitochondrial control
region were generated. Eastern chimpanzees display levels of mitochondrial
genetic variation which are low and which are similar to levels observed in
humans (Homo sapiens). Also like humans, between 80% and 90% of the genetic
variability within the eastern chimpanzees is apportioned within
populations. Spatial autocorrelation analysis shows that genetic similarity
between eastern chimpanzees decreases clinically with distance, in a
pattern remarkably similar to one seen for humans separated by equivalent
geographic distances. Eastern chimpanzee mismatch distributions (frequency
distributions of pairwise genetic differences between individuals) are
similar in shape to those for humans, implying similar population histories
of recent demographic expansion. The overall pattern of genetic variability
in eastern chimpanzees is consistent with the hypothesis that the subject
has responded demographically to paleoclimatically driven changes in the
distribution of eastern African forests during the recent Pleistocene.
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In dictyostelium discoideum, extracellular cAMP activates adenylate cyclase, which leads to an increase in intracellular cAMP and the rate of cAMP secretion. The signaling response to a constant cAMP stimulus is terminated after several minutes by an adaptation mechanism. The time- course of adaptation stimuli of 10(-6) or 10(-7) M cAMP was assessed. We used a perfusion technique to deliver defined cAMP stimuli to [(3)H]adenosine-labeled amoebae and monitored their secretion of [(3)H]cAMP. Amoebae were pretreated with 10(-6) or 10(-7) M cAMP to periods of 0.33-12 minutes, and then immediately given test stimuli of 10(-8) M to 2.5 x 10(-7) M cAMP. The response to a given test stimulus was progressively attenuated and finally extinguished as the duration of the pretreatment stimulus increased. During concentration of the test stimulus. The responses to test stimuli of 10(-8), 5 x 10(-8), 10(-7), or 2.5 x 10(-7) M cAMP were extinguished after approximately 1, 2.25,2.5, and 10 min, respectively. 1.5 min of stimulation with 10(-7) M cAMP was necessary to extinguish the response of a test stimulus of 10(-8) M cAMP. Our data suggest that adaptation begins within 20 s of stimulation, rises rapidly for approximately 2.5 min, and reaches a plateau after approximately 10 min. The absolute rate of rise was faster during pretreatment with 10(-6) than with 10(-7) M cAMP. These results support a working hypothesis in which the occupancy of surface cAMP receptors leads to changes in two opposing cellular processes, excitation and adaptation, that control the activity of D. discoideum adenylate cyclase. 相似文献
The self-incompatible (SI) Brassica napus line W1, which carries the 910 S allele, was transformed with an inactive copy of the 910 S locus receptor kinase (SRK) gene. Two transformed lines were analyzed based on their heritable ability to set self-seed. The first line was virtually completely self-compatible (SC), and reciprocal pollinations with the original W1 line demonstrated that only the stigma side of the SI phenotype was altered. An analysis of the expression of endogenous SRK-910 demonstrated that the mechanism of transgene action is via gene suppression. Furthermore, the expression of the S locus glycoprotein gene present in the 910 allele (SLG-910), SLG-A10, which is derived from a nonfunctional S allele, and an S locus-related gene were also suppressed. When the transgene was crossed into another SI line carrying the A14 S allele, it was also capable of suppressing the expression of the endogenous genes and of making this line SC. The second transgenic line studied was only partly SC. In this case as well, only the stigma phenotype was affected, although no gene suppression was detected for endogenous SRK-910 or SLG-910. In this line, the expression of the transgene most likely was causing the change in phenotype, and no effect was observed when this transgene was crossed into the other SI line. Therefore, this work reinforces the hypothesis that the SRK gene is required, but only for the stigma side of the SI phenotype, and that a single transgene can alter the SI phenotype of more than one S allele. 相似文献
Alignment of RNA secondary structures is important in studying functional RNA motifs. In recent years, much progress has been
made in RNA motif finding and structure alignment. However, existing tools either require a large number of prealigned structures
or suffer from high time complexities. This makes it difficult for the tools to process RNAs whose prealigned structures are
unavailable or process very large RNA structure databases. 相似文献
Although decision-making using the heart-team approach is apparently intuitive and has a class I recommendation in most recent guidelines, supportive data is still lacking. The current study aims to demonstrate the individualised clinical pathway for mitral valve disease patients and to evaluate the outcome of all patients referred to the dedicated mitral valve heart team.
Methods
All patients who were evaluated for mitral valve pathology with or without concomitant cardiac disease between 1 January 2016 and 31 December 2016 were prospectively followed and included. Patients were evaluated, and a treatment strategy was determined by the dedicated mitral valve heart team.
Results
One hundred and fifty-eight patients were included; 67 patients were treated surgically (isolated and concomitant surgery), 20 by transcatheter interventions and 71 conservatively. Surgically treated patients had a higher 30-day mortality rate (4.4%), which decreased when specified to a dedicated surgeon (1.7%) and in primary, elective cases (0%). This was also observed for major adverse events within 30 days. Residual mitral regurgitation >grade 2 was more frequent in the catheter-based intervention group (23.5%) compared to the surgical group (4.8%).
Conclusion
In conclusion, the implementation of a multidisciplinary heart team for mitral valve disease is a valuable approach for the selection of patients for different treatment modalities. Our research group will focus on a future comparative study using historical cohorts to prove the potential superiority of the dedicated multidisciplinary heart-team approach.
It has been proposed that memory for odors does not have a short-term (or
working) memory system. The distinction between short- and long- term
memory in other sensory modalities has been generally supported by three
main lines of evidence: capacity differences between the proposed systems,
evidence of differential coding, and differential memory losses in
neuropsychological patients. The present paper examines these issues in an
effort to establish a similar distinction for the memory of olfactory
stimuli. Each of these lines of evidence is examined in relation to the
literature on olfactory memory. Based on this examination, it seems that
there is at least preliminary support from each of these lines of evidence
to advocate a distinction between a long- and short-term memory for
olfactory stimuli. Emphasis is placed upon the qualitative similarity of
olfactory memory to other memory systems. This similarity is further
highlighted through an examination of the literature pertinent to serial
position effects in memory for olfactory stimuli.
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