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1.
By means of radioimmunoassay a clear-cut peak of melatonin concentration was found in the pineal organ of the pigeon at the middle of the scotophase (Coisin et al. 1982a). The aim of the present study was to identify the cell type responsible for the nocturnal indole metabolism, including melatonin synthesis, in the pineal of this avian species. After a short-term incubation or organ culture in the presence of [3H]-indolic precursors, [3H]-5-hydroxytryptophan or [3H]-5-hydroxytryptamine, the relative amounts of deaminated and acetylated products occurring in the pineal organ were measured by the use of thin layer chromatography and liquid-scintillation counting. It was possible to modify the relative amounts of deaminated and acetylated indoles by the application of some inhibitors of monoamine oxidase and cyclic nucleotide phosphodiesterase. Irrespective of the experimental conditions, high-resolution autoradiography combined with the above-mentioned radiochemical experiments showed that the cells of the receptor line (modified photoreceptor cells) are responsible for indole storage and metabolism, and very probably also for melatonin biosynthesis. The other cell types of the pineal parenchyma did not display significant labeling. 相似文献
2.
The present investigation sought to characterize the adrenergic inhibition of arylalkylamine-N-acetyltransferase in cultured chicken pineal glands. Arylalkylamine-N-acetyltransferase, the melatonin rhythm generating enzyme, displays daily oscillations of activity that are driven by a circadian oscillator. Norepinephrine released at sympathetic nerve endings inhibits the enzyme and appears to play a role in maintaining a circadian rhythm of melatonin release. Chicken pineal glands were isolated in organ culture and the effects of adrenergic agents on the night time peak of N-acetyltransferase activity were studied. Norepinephrine and clonidine prevented 50 to 65% of the nocturnal rise of N-acetyltransferase activity. When applied at middark, norepinephrine and clonidine caused a 50 to 65% inhibition of N-acetyltransferase activity in 2 hours. Dose-response studies indicated clonidine was 100 times more potent than norepinephrine or cirazoline at inhibiting N-acetyltransferase activity. Inhibition of N-acetyltransferase activity was also observed, at micromolar concentration with epinephrine, UK 14,304 and alpha-methylnorepinephrine but not with phenylephrine, isoproterenol or dopamine. Epinephrine and clonidine actions were antagonized by yohimbine but not by prazosin. Destruction of the presynaptic compartment by bilateral superior cervical ganglionectomy did not affect the clonidine-induced inhibition of N-acetyltransferase and its reversal by yohimbine. It is concluded that the adrenergic inhibition of N-acetyltransferase activity in chicken pineal gland probably occurs via stimulation of postsynaptic alpha 2-adrenergic receptors. 相似文献
3.
4.
Veronique Billat Jean C. Renoux Jacques Pinoteau Bernard Petit Jean P. Koralsztein 《European journal of applied physiology and occupational physiology》1994,69(3):271-273
The aim of this study was to measure running times to exhaustion (Tlim) on a treadmill at 100% of the minimum velocity which elicits
max
max in 38 elite male long - distance runners
max = 71.4 ± 5.5 ml.kg–1.min–1 and
max = 21.8 ± 1.2 km.h–1). The lactate threshold (LT) was defined as a starting point of accelerated lactate accumulation around 4 mM and was expressed in
max. Tlim value was negatively correlated with
max (r = -0.362, p< 0.05) and
max (r = –0.347, p< 0.05) but positively with LT (%v
max) (r = 0.378, p < 0.05). These data demonstrate that running time to exhaustion at
max in a homogeneous group of elite male long-distance runners was inversely related to
max and experimentally illustrates the model of Monod and Scherrer regarding the time limit-velocity relationship adapted from local exercise for running by Hughson et al. (1984) . 相似文献
5.
Veronique Blanchard Rita Raisman-Vozari Marc Savasta Etienne Hirsch France Javoy-Agid Claude Feuerstein Yves Agid 《Journal of neurochemistry》1993,61(2):617-626
Abstract: We developed a rapid and sensitive radioimmunohistochemical method for the quantification of tyrosine hydroxylase (TH) at both the anatomical and cellular level. Coronal tissue sections from fresh-frozen rat brains were incubated in the presence of a TH monoclonal antibody. The reaction was revealed with a 35 S-labeled secondary antibody. TH content was quantified in catecholaminergic brain areas by measuring optical density on autoradiographic films or silver grain density on autoradiographic emulsion-coated sections. Regional TH concentrations determined in the locus ceruleus (LC), substantia nigra pars compacta (SNC), and ventral tegmental area (VTA) were significantly increased by 45% after reserpine treatment in the LC but unchanged in the SNC and VTA. Microscopic examination of TH radioimmunolabeling showed a heavy accumulation of silver grains over catecholaminergic cell bodies. In the LC, grain density per cell was heterogeneous and higher in the ventral than in the dorsal part of the structure. After reserpine treatment, TH levels were significantly increased (57%) in the neurons of the LC but not in those of the SNC or VTA. The data support the validity of this radioimmunohistochemical method as a tool for quantifying TH protein at the cellular level and they confirm that TH protein content is differentially regulated in noradrenergic and dopaminergic neurons in response to reserpine. 相似文献
6.
When single mast cells were isolated by micromanipulation, specific H-2 antigen-bearing mast cells were degranulated upon incubation with alloimmune sera (DAAD). When specific alloantigens were presented by lymphoid cells only, no degranulation occurred. Only antigen-bearing mast cells were degranulated, irrespectively of the presence of antigen-bearing lymphoid cells. Therefore, in DAAD, anaphylactic alloantibodies can and must recognize specific H-2 antigens on the mast cell membrane and simultaneously deliver the degranulation signal, through an Fc-Fc receptor interaction on the surface of the same mast cell. 相似文献
7.
R Lebar J M Boutry C Vincent R Robineaux G A Voisin 《Journal of immunology (Baltimore, Md. : 1950)》1976,116(5):1439-1446
Complement-dependent demyelinating activity of whole brain homogenate (WBH)-induced experimental allergic encephalomyelitis (EAE) sera was tested on long term tissue cultures of in vitro myelinated fetal guinea pig cerebellum. Complement-fixing (CF) auto-antibodies were shown to be the responsible agents, as demonstrated in experiments where all reagents belonged to the same species: guinea pigs of outbred (Hartley) and even of inbred (S2 or S13) strains. These antibodies were of the IgG2 class as shown by Sephadex G-200 and DEAE cellulose fractionation experiments. The corresponding auto-antigen was present in the homogenate and myelin of the central nervous system (CNS) tissue. It was different from the encephalitogenic basic protein of CNS myelin (BP), as shown in experiments where the demyelinating auto-antibodies were induced, detected, and absorbed by WBH or by CNS myelin but not by BP. They were neither induced by nor cross-reacting with cerebroside and peripheral nervous system (PNS) tissue. 相似文献
8.
9.
H T Duc R G Kinsky J Kanellopoulos G A Voisin 《Journal of immunology (Baltimore, Md. : 1950)》1975,115(4):1143-1150
The influence of the course of immunization on the facilitating-enhancing activity of antibody classes has been studied by passive enhancement of growth of A/JAX sarcomas in CBA and IC mice and of C57BL/6 EL 4 leukemia in BALB/c mice. The influence of dilution of antibodies and complexing to antigens was also studied. During immunization (with several boosters), the enhancing capacity of sera increased together with 7S IgG antibody activity, but showed no correlation with 19S IgM antibody activity. It also was mercaptoethanol resistant. IgG1 to be more enhancing than an equal number of hemagglutinating units of IgG2a. When concentrated on a small amount (10(5)) of target sarcoma I cells, complement-fixing IC anti-A antibodies were even inhibitory on Sa I allografted to IC recipients. Progressive dilutions reversed this situation, IgG1 activity disappearing and IgG2 acquiring enhancing activity. After complexing to corresponding antigens IgG2 also (and immune sera with inhibitory properties) acquired enhancing properties. These results may provide a basis for understanding the discrepancies between the results of several groups of authors studying the class(es) of enhancing anibodies. 相似文献
10.
Karim Arafah Sbastien Nicolas Voisin Victor Masson Cdric Alaux Yves Le Conte Michel Bocquet Philippe Bulet 《Proteomics》2019,19(23)
Honey bees play a critical role in the maintenance of plant biodiversity and sustainability of food webs. In the past few decades, bees have been subjected to biotic and abiotic threats causing various colony disorders. Therefore, monitoring solutions to help beekeepers to improve bee health are necessary. Matrix‐assisted laser desorption ionization–mass spectrometry (MALDI–MS) profiling has emerged within this decade as a powerful tool to identify in routine micro‐organisms and is currently used in real‐time clinical diagnosis. MALDI BeeTyping is developed to monitor significant hemolymph molecular changes in honey bees upon infection with a series of entomopathogenic Gram‐positive and ‐negative bacteria. A Serratia marcescens strain isolated from one naturally infected honey bee collected from the field is also considered. A series of hemolymph molecular mass fingerprints is individually recorded and to the authors' knowledge, the first computational model harboring a predictive score of 97.92% and made of nine molecular signatures that discriminate and classify the honey bees’ systemic response to the bacteria is built. Hence, the model is challenged by classifying a training set of hemolymphs and an overall recognition of 91.93% is obtained. Through this work, a novel, time and cost saving high‐throughput strategy that addresses honey bee health on an individual scale is introduced. 相似文献