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971.
M. G. Barrutia A. Villena B. Razquin R. P. Gomariz A. Zapata 《Cellular and molecular life sciences : CMLS》1985,41(11):1393-1394
Summary The periphery of splenic lymphoid follicles, an area rich in reticulum fibers, contains presumptive interdigitating cells characterized by low electron density, scantiness of cytoplasmic organelles, abundant surface foldings and, sometimes, electrondense granules of unknown significance. 相似文献
972.
B. Blum J. Israeli O. Hart M. Farchi 《Cellular and molecular life sciences : CMLS》1989,45(10):991-996
Summary Transient sympathetically-mediated depressor effects were induced by stimulation of a small locus in the lateral hypothalamic peri-fornical region, medial to the fields of Forel. The ganglionic blocking agent, atropine methyl nitrate (ATMN), was used to show that muscarinic as well as non-muscarinic sympathetic ganglion receptor neurotransmission was involved. Evidence is presented that stimulation of this LH site co-activates a number of mechanisms and that depending on which of these are activated, the ganglionic blocking agent ATMN may either block, reverse or potentiate the depressor effect. 相似文献
973.
Dopamine receptors are classified into D1 and D2 subtypes on the basis of their pharmacological properties and the intracellular responses they mediate. The cerebral D2 dopamine receptor is the target of drugs used to alleviate the main symptoms of schizophrenia. Although it is considered to be a single molecular entity, there is evidence that multiple D2-receptor subtypes exist. A complementary DNA encoding a D2 receptor has recently been cloned and the deduced 415-amino-acid sequence indicates that it belongs to the large superfamily of receptors coupled to G proteins, and that its topology consists of seven transmembrane domains. In this family, the genes are frequently without introns and each is believed to encode a unique polypeptide product. Here we show that the gene for the D2 receptor produces two receptor isoforms by alternative messenger RNA splicing, providing a route to receptor diversity in this family. One isoform corresponds to the D2(415) receptor, but the second contains an additional sequence encoding a 29-amino-acid fragment, defining a novel D2(444) receptor isoform. Expression of the two isoforms is tissue-specific, and both are regulated by guanyl nucleotides. As the extra sequence is located within a putative cytoplasmic loop that binds to G proteins, the two isoforms might interact with different G proteins and thereby initiate distinct intracellular signals. 相似文献
974.
Human genetics. Bone disease cracks genetics 总被引:2,自引:0,他引:2
975.
976.
977.
Fischer rat 3T3 (FR3T3) fibroblasts transfected with a cellular myc gene can be induced to grow and form colonies in soft agar by treatment either with epidermal growth factor (EGF) alone or with the combination of platelet-derived growth factor (PDGF) and type-beta transforming growth factor (TGF-beta). We now show that induction of anchorage-independent growth by each of these sets of growth factors involves different cellular pathways which can be distinguished by their sensitivity to retinoic acid. Colony formation induced by the combined action of PDGF and TGF-beta is 100-fold more sensitive to inhibition by retinoic acid than is colony formation induced by treatment of the myc-transfected cells with EGF. Moreover, retinoic acid (10(-8) M) is inhibitory for colony growth whenever TGF-beta is present, regardless of whether the effects of TGF-beta are stimulatory, as occurs in the presence of PDGF, or inhibitory, as found in the presence of EGF. 相似文献
978.
Interaction with antigen-presenting accessory cells is thought to be an important step in B-cell activation, and the B-cell receptor CD22, which is coordinately expressed with surface immunoglobulin, has been proposed to participate in the antigen response. Here we show that CD22 has a structure closely related to myelin-associated glycoprotein (MAG, a neuronal adhesion protein), and mediates monocyte and erythrocyte adhesion. Like CD2, the T-cell erythrocyte receptor, CD22 may facilitate antigen recognition by promoting antigen-nonspecific contacts with accessory cells. 相似文献
979.
We studied the distribution of an immunoreactive substance resembling growth hormone-releasing factor (GRF) in the hypothalamus and pituitary gland of the rainbow trout by immunofluorescence methods. The GRF-like immunoreactive perikaryon was observed in colchicine-treated fish. The majority of GRF-containing neurons were located in the nucleus lateral tuberis; others were located in the caudal part of the preoptic nucleus of the hypothalamus. The GRF-like immunoreactive neuronal processes projected into the pars distalis via the pars nervosa of the pituitary gland. The distribution of the GRF-like immunoreactive substance in the hypothalamus and pituitary gland suggests that GRF plays a physiological role in the regulation of growth hormone release from the pituitary gland of rainbow trout, as it does in mammals. 相似文献
980.