6,075 research outputs found
Glucose metabolism in different regions of the rat brain under hypokinetic stress influence
Glucose metabolism in rats kept under long term hypokinetic stress was studied in 7 brain regions. Determination was made of the regional levels of glucose, lactate, glutamate, glutamine, aspartate, gamma-aminobutyrate and the incorporation of C-14 from plasma glucose into these metabolites, in glycogen and protein. From the content and activity data the regional glucose flux was approximated quantitatively. Under normal conditions the activity gradient cortex and frontal pole cerebellum, thalamus and mesencephalon, hypothalamus and pons and medulla is identical with that of the regional blood supply (measured with I131 serum albumin as the blood marker). Within the first days of immobilization a functional hypoxia occurred in all brain regions and the utilization of cycle amino acids for protein synthesis was strongly diminished. After the first week of stress the capillary volumes of all regions increased, aerobic glucose metabolism was enhanced (factors 1.3 - 2.0) and the incorporation of glucose C-14 via cycle amino acids into protein was considerably potentiated. The metabolic parameters normalized between the 7th and 11th week of stress. Blood supply and metabolic rate increased most in the hypothalamus
Voronoi Cells of Discrete Point Sets
It is well known that all cells of the Voronoi diagram of a Delaunay set are polytopes. For a finite point set, all these cells are still polyhedra. So the question arises, if this observation holds for all discrete point sets: Are always all Voronoi cells of an arbitrary, infinite discrete point set polyhedral? In this paper, an answer to this question will be given. It will be shown that all Voronoi cells of a discrete point set are polytopes if and only if every point of the point set is an inner point. Furthermore, the term of a locally finitely generated discrete point set will be introduced and it will be shown that exactly these sets have the property of possessing only polyhedral Voronoi cells
Quasi-hydrostatic intracluster gas under radiative cooling
Quasi-hydrostatic cooling of the intracluster gas is studied. In the
quasi-hydrostatic model, work done by gravity on the inflow gas with dP \neq 0,
where P is the gas pressure, is taken into account in the thermal balance. The
gas flows in from the outer part so as to compensate the pressure loss of the
gas undergoing radiative cooling, but the mass flow is so moderate and smooth
that the gas is considered to be quasi-hydrostatic. The temperature of the
cooling gas decreases toward the cluster center, but, unlike cooling flows with
dP = 0, approaches a constant temperature of \sim 1/3 the temperature of the
non-cooling ambient gas. This does not mean that gravitational work cancels out
radiative cooling, but means that the temperature of the cooling gas appears to
approach a constant value toward the cluster center if the gas maintains the
quasi-hydrostatic balance. We discuss the mass flow in quasi-hydrostatic
cooling, and compare it with the standard isobaric cooling flow model. We also
discuss the implication of \dot{M} for the standard cooling flow model.Comment: 5 pages, 1 figure, accepted for publication in A&
Calcitonin receptor-like receptor is expressed on gastrointestinal immune cells
Background/Aims: Pharmacological and morphological studies suggest that the gut mucosal immune system and local neuropeptide-containing neurones interact. We aimed to determine whether gut immune cells are targets for calcitonin gene-related peptide (CGRP), which has potent immune regulatory properties. Methods: Using density gradient centrifugation, rat lamina propria mononuclear cells (LP-MNCs) and intra-epithelial lymphocytes (IELs) were isolated. RT-PCR was employed for the detection of mRNA of rat calcitonin receptor-like receptor (CRLR), which is considered to represent the pharmacologically defined CGRP receptor-1 subtype, as well as mRNA of the receptor activity-modifying proteins, which are essential for CRLR function and determine ligand specificity. A radioreceptor assay was employed for the detection of specific CGRP binding sites. Results: RT-PCR and DNA sequencing showed that LP-MNCs and IELs express CRLR. Incubation of isolated LP-MNCs with radiolabelled alphaCGRP revealed the existence of specific binding sites for CGRP. Conclusion: These novel data indicate that mucosal immune cells of the rat gut are a target for CGRP and provide significant evidence that CGRP functions as an immune regulator in the gut mucosa. Copyright (C) 2002 S. Karger AG, Basel
The Isoelectric Focusing of Creatine Kinase Variants: I. The Heterogeneity of Creatine Kinase in Human Heart Cytosol and Mitochondria
Peer Reviewe
Удаление серосодержащих соединений из дизельной фракции в процессе окислительного обессеривания
Metabolic costs of bat echolocation in a non-foraging context support a role in communication
The exploitation of information is a key adaptive behavior of social animals,
and many animals produce costly signals to communicate with conspecifics. In
contrast, bats produce ultrasound for auto-communication, i.e., they emit
ultrasound calls and behave in response to the received echo. However,
ultrasound echolocation calls produced by non-flying bats looking for food are
energetically costly. Thus, if they are produced in a non-foraging or
navigational context this indicates an energetic investment, which must be
motivated by something. We quantified the costs of the production of such
calls, in stationary, non-foraging lesser bulldog bats (Noctilio albiventris)
and found metabolic rates to increase by 0.021 ± 0.001 J/pulse (mean ±
standard error). From this, we estimated the metabolic rates of N. albiventris
when responding with ultrasound echolocation calls to playbacks of
echolocation calls from familiar and unfamiliar conspecific as well as
heterospecific bats. Lesser bulldog bats adjusted their energetic investment
to the social information contained in the presented playback. Our results are
consistent with the hypothesis that in addition to orientation and foraging,
ultrasound calls in bats may also have function for active communication
The role of the voltage-gated potassium channel proteins Kv8.2 and Kv2.1 in vision and retinal disease: Insights from the study of mouse gene knock-out mutations
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