879 resultados para k(L)a


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Inositol 1,4,5-trisphosphate (IP3) receptors are ligand-gated channels that release intracellular Ca2+ stores in response to the second messenger, IP3. We investigated the potential role of IP3 receptors during nuclear envelope assembly in vitro, using Xenopus egg extracts. Previous work suggested that Ca2+ mobilization is required for nuclear vesicle fusion and implicated IP3 receptor activity. To test the involvement of IP3 receptors using selective reagents, we obtained three distinct polyclonal antibodies to the type 1 IP3 receptor. Pretreatment of membranes with two of the antibodies inhibited IP3-stimulated CA2+ release in vitro and also inhibited nuclear vesicle fusion. One inhibitory serum was directed against 420 residues within the "coupling" domain, which includes several potential regulatory sites. The other inhibitory serum was directed against 95 residues near the C terminus and identifies an inhibitory epitope(s) in this region. The antibodies had no effect on receptor affinity for IP3. Because nuclear vesicle fusion was inhibited by antibodies that block Ca2+ flux, but not by control and preimmune antibodies, we concluded that the activation of IP3 receptors is required for fusion. The signal that activates the channel during fusion is unknown.

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Unlike most normal adult tissues, cyclic growth and tissue remodeling occur within the uterine endometrium throughout the reproductive years. The matrix metalloproteinases (MMPs), a family of structurally related enzymes that degrade specific components of the extracellular matrix are thought to be the physiologically relevant mediators of extracellular matrix composition and turnover. Our laboratory has identified MMPs of the stromelysin family in the cycling human endometrium, implicating these enzymes in mediating the extensive remodeling that occurs in this tissue. While the stromelysins are expressed in vivo during proliferation-associated remodeling and menstruation-associated endometrial breakdown, none of the stromelysins are expressed during the progesterone-dominated secretory phase of the cycle. Our in vitro studies of isolated cell types have confirmed progesterone suppression of stromal MMPs, but a stromal-derived paracrine factor was found necessary for suppression of the epithelial-specific MMP matrilysin. In this report, we demonstrate that transforming growth factor beta (TGF-beta) is produced by endometrial stroma in response to progesterone and can suppress expression of epithelial matrilysin independent of progesterone. Additionally, we find that an antibody directed against the mammalian isoforms of TGF-beta abolishes progesterone suppression of matrilysin in stromal-epithelial cocultures, implicating TGF-beta as the principal mediator of matrilysin suppression in the human endometrium.

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Glycoproteins expressing the Lutheran blood group antigens were isolated from human erythrocyte membranes and from human fetal liver. Amino acid sequence analyses allowed the design of redundant oligonucleotides that were used to generate a 459-bp, sequence-specific probe by PCR. A cDNA clone of 2400 bp was isolated from a human placental lambda gt 11 library and sequenced, and the deduced amino acid sequence was studied. The predicted mature protein is a type I membrane protein of 597 amino acids with five potential N-glycosylation sites. There are five disulfide-bonded, extracellular, immunoglobulin superfamily domains (two variable-region set and three constant-region set), a single hydrophobic, membrane-spanning domain, and a cytoplasmic domain of 59 residues. The overall structure is similar to that of the human tumor marker MUC 18 and the chicken neural adhesion molecule SC1. The extracellular domains and cytoplasmic domain contain consensus motifs for the binding of integrin and Src homology 3 domains, respectively, suggesting possible receptor and signal-transduction function. Immunostaining of human tissues demonstrated a wide distribution and provided evidence that the glycoprotein is under developmental control in liver and may also be regulated during differentiation in other tissues.

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The Ly-6 locus encodes several cell surface proteins whose functions are unknown. Although it is hypothesized that these proteins may be receptors, there is no direct evidence that they bind a ligand. Herein we present evidence that Ly-6A.2, a Ly-6 protein expressed on T lymphocytes, binds a ligand expressed on normal thymocytes and splenic B and T cells. We find that transgenic thymocytes that overexpress Ly-6A.2 spontaneously aggregate in culture. This homotypic adhesion requires the overexpression of Ly-6A.2 because it is not observed in cultures of nontransgenic thymocytes. The aggregation of Ly-6A.2 transgenic thymocytes is inhibited by phosphatidylinositol-specific phospholipase C (which removes Ly-6A.2 and other glycosylphosphatidylinositol-anchored proteins from the membrane). Some anti-Ly-6A.2 monoclonal antibodies, including nonactivating ones and Fab' fragments, inhibit this aggregation. In contrast, other anti-Ly-6A.2 monoclonal antibodies increase the aggregation of transgenic but not nontransgenic thymocytes. To further examine whether Ly-6A.2 mediates adhesion (versus inducing another adhesion pathway) reaggregation assays were performed with paraformaldehyde-fixed Tg+ thymocytes. Paraformaldehyde-fixed Tg+ thymocytes reaggregate in culture and this aggregation is also blocked by phosphatidyl-inositol-specific phospholipase C and anti-Ly-6A.2 monoclonal antibodies. These results indicate that the homotypic adhesion of cultured Ly-6A.2 transgenic thymocytes is directly mediated by Ly-6A.2 and, more importantly, strongly suggests that Ly-6A.2 binds a ligand that is expressed on thymocytes. Tg+ thymocytes also bind to nontransgenic thymocytes, B cells, and T cells, indicating that normal cells naturally express the Ly-6A.2 ligand.

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After a penetrating lesion in the central nervous system, astrocytes enlarge, divide, and participate in creating an environment that adversely affects neuronal regeneration. We have recently shown that the neural cell adhesion molecule (N-CAM) partially inhibits the division of early postnatal rat astrocytes in vitro. In the present study, we demonstrate that addition of N-CAM, the third immunoglobulin-like domain of N-CAM, or a synthetic decapeptide corresponding to a putative homophilic binding site in N-CAM partially inhibits astrocyte proliferation after a stab lesion in the adult rat brain. Animals were lesioned in the cerebral cortex, hippocampus, or striatum with a Hamilton syringe and needle at defined stereotaxic positions. On one side, the lesions were concomitantly infused with N-CAM or with one of the N-CAM-related molecules. As a control, a peptide of the same composition as the N-CAM decapeptide but of random sequence was infused on the contralateral side of the brain. We consistently found that the population of dividing astrocytes was significantly smaller on the side in which N-CAM or one of the N-CAM-related molecules was infused than on the opposite side. The inhibition was greatest in the cortical lesion sites (approximately 50%) and was less pronounced in the hippocampus (approximately 25%) and striatum (approximately 20%). Two weeks after the lesion, the cerebral cortical sites infused with N-CAM continued to exhibit a significantly smaller population of dividing astrocytes than the sites on the opposite side. When N-CAM and basic fibroblast growth factor, which is known to stimulate astrocyte division in vitro, were coinfused into cortical lesion sites, astrocyte proliferation was still inhibited. These results suggest the hypothesis that, by reducing glial proliferation, N-CAM or its peptides may help create an environment that is more suitable for neuronal regeneration.

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[sharḥ Muḥammad ibn Ḥamzah ibn Muḥammad al-ʻUṭhmānī (al-Fanārī) ; taṣḥīḥ Mīrzā Ḥāshim ibn Ḥasan ibn Muḥammad ʻAlī al-Kīlānī al-Ashkūrī].

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With: Thalāthat alwāḥ al-jafrīyah al-mutaḍamminah asmāʼ mulūk Āl ʻUthmān (f. 4v-5r) -- al-Durr al-munaẓẓam fī sharḥ al-ism al-aʻẓam / ʻAbd al-Raḥmān ibn Muḥammad al-Bisṭāmī (f. 5v-39r).

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Written in one column, 20 lines per page, in black rubricated in red. Text framed within double red lines and each line framed within a red line.

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The neuro-anatomical substrates of major depressive disorder (MDD) are still not well understood, despite many neuroimaging studies over the past few decades. Here we present the largest ever worldwide study by the ENIGMA (Enhancing Neuro Imaging Genetics through Meta-Analysis) Major Depressive Disorder Working Group on cortical structural alterations in MDD. Structural T1-weighted brain magnetic resonance imaging (MRI) scans from 2148 MDD patients and 7957 healthy controls were analysed with harmonized protocols at 20 sites around the world. To detect consistent effects of MDD and its modulators on cortical thickness and surface area estimates derived from MRI, statistical effects from sites were meta-analysed separately for adults and adolescents. Adults with MDD had thinner cortical gray matter than controls in the orbitofrontal cortex (OFC), anterior and posterior cingulate, insula and temporal lobes (Cohen’s d effect sizes: −0.10 to −0.14). These effects were most pronounced in first episode and adult-onset patients (>21 years). Compared to matched controls, adolescents with MDD had lower total surface area (but no differences in cortical thickness) and regional reductions in frontal regions (medial OFC and superior frontal gyrus) and primary and higher-order visual, somatosensory and motor areas (d: −0.26 to −0.57). The strongest effects were found in recurrent adolescent patients. This highly powered global effort to identify consistent brain abnormalities showed widespread cortical alterations in MDD patients as compared to controls and suggests that MDD may impact brain structure in a highly dynamic way, with different patterns of alterations at different stages of life.

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"LBL-6807."

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Exquisite album of calligraphy (muraqqaʻ or murakkaa) with design for a monumental inscription to appear in stone on a commemorative range marker (menzil taşı) of Bilâl Ağa (d.1807?), likely executed by Yesari Mehmed Esad Efendi (d.1798), the great Ottoman master of nastaʻlīq (talik).

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Mode of access: Internet.