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排序方式: 共有72条查询结果,搜索用时 15 毫秒
1.
Manabu Sakakibara Carlos Collin Alan Kuzirian Daniel L. Alkon Eliahu Heldman Shigetaka Naito Izja Lederhendler 《Journal of neurochemistry》1987,48(2):405-416
Type B photoreceptors of the nudibranch mollusc Hermissenda crassicornis receive excitatory synaptic potentials (EPSPs) whose frequency is controlled by potential changes of a neighboring cell known as the S optic ganglion cell which is thought to be electrically coupled to the presynaptic source of these EPSPs, the E optic ganglion cell. The frequency of the EPSPs increases when a conditioned stimulus (light) is paired with an unconditioned stimulus (rotation) during acquisition of a Pavlovian conditioned response. The results of the present study are consistent with an adrenergic origin for these EPSPs. Noradrenergic agonists (greater than 100 microM), norepinephrine and clonidine, only slightly depolarize the type B cell but clearly prolong its depolarizing response to light. Serotonin, by contrast, causes hyperpolarization of the type B cell's resting potential as well as after a light step. Clonidine reduces voltage-dependent outward K+ currents (IA, an early current, ICa2+-K+, a late Ca2+-dependent current) that control the type B cell's excitability (and thus its light response and membrane potential). These effects of clonidine are reduced or blocked by the alpha 2-receptor antagonist, yohimbine (0.5 microM), but not the alpha 1-blocker, prazosin. The same yohimbine concentration also blocked depolarizing synaptic excitation of the type B cell in response to depolarization of a simultaneously impaled S optic ganglion cell. Histochemical techniques (both the glyoxylic acid method of de la Torre and Surgeon and the formaldehyde-induced fluorescence or Falck-Hillarp method) demonstrated the presence of a biogenic amine(s) within a single neuron in each optic ganglion as well as three or four cells within the vicinity of previously identified visual interneurons. No serotonergic neurons were found within the optic ganglion or in proximity to visual interneurons. A clonidine-like synaptic effect on type B cells, therefore, could amplify conditioning-specific changes of membrane currents by increasing type B depolarization and possibly, as well, by elevating intracellular second messengers. 相似文献
2.
Steven Romanoff 《Human ecology: an interdisciplinary journal》1983,11(3):339-343
Matses women of the Peruvian Amazon rain forest hunt with men, and couples bring back more meat than men alone. This results from the association of women with capture of collared peccary, a large catch. Typical Amazonian beliefs about women persist, but some new features (like day care) are pertinent to Matses hunting adaptation. 相似文献
3.
(1) A synaptosomal fraction obtained from locust nervous tissue has been shown to possess an active γ-aminobutyric acid transport mechanism. This activity is preserved and even enriched by the membrane vesicles derived from osmotically shocked synaptosomes. (2) Electron-microscopy examination indicates that the above membrane vesicles are derived predominantly from the neuronal plasma membrane and are devoid of any internal cellular organelles and components. Active transport of γ-aminobutyric acid into these vesicles has been demonstrated with artificially imposed ion gradients as the sole energy source. (3) γ-Aminobutyric acid transport can be driven by an Na+ gradient (out>in) and /or by a gradient of Cl? (out>in). This process is absolutely dependent on the simultaneous presence of both types of ion in the external medium. The stimulation of the process by valinomycin indicates that γ-aminobutyric acid transport is an electrogenic process which is stimulated by a membrane potential (interior negative). 相似文献
4.
David A. Doron David M. Jacobowitz Eliahu Heldman Ciora Feuerstein Harvey B. Pollard John M. Hallenbeck 《In vitro cellular & developmental biology. Animal》1991,27(9):689-697
Summary Microvascular endothelial cells from the adult rat brain were cultured on Matrigel and found to express many differentiated
properties including secretion of prostacyclin (PGI2) and von Willebrand’s factor (vWF). Brain microvascular endothelial cells (BMECs) were purified by dextran and percoll gradients
after enzymatic treatment and cultured under various conditions. BMECs that were plated on Matrigel stained positively for
factor VIII-related antigen and incorporated Di-I-acetylated low density lipoprotein, whereas BMEC plated on fibronectin,
gelatin, or uncoated dishes did not express any of the above properties which are characteristic of endothelial cells. vWF
was measured by a sensitive ELISA in the culture media of BMECs plated on different types of matrices. Specificity of the
anti-human vWF antibodies for the rat vWF was verified by immunoabsorption on a solid phase, sodium dodecyl sulfate, and Western
blot analysis. BMECs also secreted vWF into the culture media only when the cells were plated on Matrigel, and this secretion
was augmented after a 6 h incubation with an interleukin-1 tumor necrosis factor-α mixture, but not by lipopolysaccharide. From different matrices tested, only Matrigel permitted the secretion of PGI2 by BMECs. Cells also proved to be sensitive to mechanical stimulation and became refractory to secretagogue if the mechanical
stimulation was serially repeated. Under the best conditions, stimulation of the cells with bradykinin (1μM) substantially increased PGI2 secretion. These data indicate that growth of BMECs on Matrigel in vitro permits the expression of classical endothelial
cell markers in a manner similar to the behavior of these cells in situ.
Supported by grant 1 RO1 NS2822501 from National Institutes of Health, Bethesda, MD. 相似文献
5.
Gelbart Y Frankenburg S Pinchasov Y Krispel S Eliahu D Drize O Morag E Bartfeld D Lotem M Peretz T Pitcovski J 《Protein expression and purification》2004,34(2):183-189
gp100 is a melanoma-associated antigen found to carry immunogenic epitopes that can induce a CTL response against tumor cells. Production and purification of large quantities of this polypeptide may be important in the context of diagnosis and vaccinating against melanoma. To overcome the hydrophobic nature of gp100, we cloned and expressed only a part of the protein, and obtained a hydrophilic recombinant polypeptide (HR-gp100) that contained most of the immunogenic peptides. High yield was achieved in an Escherichia coli expression system. The protein was purified by AKTA Prime using anionic-columns. Polyclonal antibodies developed in chicken against HR-gp100 were efficient at detecting gp100 in melanoma cells, as determined by Western blot analysis and by immunohistochemistry. HR-gp100 can be used to develop a vaccine against melanoma. Antibodies to HR-gp100 may be used to detect tumors of melanocytic origin or to determine the level of gp100 expression in tumors prior to immunotherapy with the protein or one of its peptides. 相似文献
6.
Chamoun D Choi D Tavares AB Udoff LC Levitas E Resnick CE Rosenfeld RG Adashi EY 《Biology of reproduction》2002,67(3):1003-1012
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9.
Eliahu Heldman Ayala Balan Ora Horowitz Sarit Ben-Zion Michael Torten 《FEBS letters》1985,180(2):243-248
Antiparaoxon immune sera were employed in a new immunoassay based on competition between acetylcholinesterase and antibodies for the binding ofparaoxon. Unlike radioimmunoassay, the new assay described herein can be extended to predict the feasibility of antibodies to confer in vivo protection of acetylcholinesterase against organophosphate poisoning. The toxicity of paraoxon was reduced in mice which were pre-injected with the immune sera. 相似文献
10.
Arnon T Potikha T Sher D Elazar M Mao W Tal T Bosmans F Tytgat J Ben-Arie N Zlotkin E 《Insect biochemistry and molecular biology》2005,35(3):187-195
Long-chain neurotoxins derived from the venom of the Buthidae scorpions, which affect voltage-gated sodium channels (VGSCs) can be subdivided according to their toxicity to insects into insect-selective excitatory and depressant toxins (beta-toxins) and the alpha-like toxins which affect both mammals and insects. In the present study by the aid of reverse-phase HPLC column chromatography, RT-PCR, cloning and various toxicity assays, a new insect selective toxin designated as BjalphaIT was isolated from the venom of the Judean Black Scorpion (Buthotus judaicus), and its full primary sequence was determined: MNYLVVICFALLLMTVVESGRDAYIADNLNCAYTCGSNSYCNTECTKNGAVSGYCQWLGKYGNACWCINLPDKVPIRIPGACR (leader sequence is underlined). Despite its lack of toxicity to mammals and potent toxicity to insects, BjalphaIT reveals an amino acid sequence and an inferred spatial arrangement that is characteristic of the well-known scorpion alpha-toxins highly toxic to mammals. BjalphaITs sharp distinction between insects and mammals was also revealed by its effect on sodium conductance of two cloned neuronal VGSCs heterloguously expressed in Xenopus laevis oocytes and assayed with the two-electrode voltage-clamp technique. BjalphaIT completely inhibits the inactivation process of the insect para/tipE VGSC at a concentration of 100 nM, in contrast to the rat brain Na(v)1.2/beta1 which is resistant to the toxin. The above categorical distinction between mammal and insect VGSCs exhibited by BjalphaIT enables its employment in the clarification of the molecular basis of the animal group specificity of scorpion venom derived neurotoxic polypeptides and voltage-gated sodium channels. 相似文献