Inactivation of deamino-oxytocin,deamino-carba1-oxytocin, [D-Lys8]-, and [D-Arg8]vasopressins by kidney cell particles

Zusammenfassung Die Inaktivierung von Carba-, Deamino- und 8-d-substituierten Analogen der neurohypophysäuren Hormone durch Schweinenierenhomogenate verläuft mit der gleichen Geschwindigkeit wie die des Oxytocins und Vasopressins.     

Nanobody-induced perturbation of LFA-1/L-plastin phosphorylation impairs MTOC docking, immune synapse formation and T cell activation

The T cell integrin receptor LFA-1 orchestrates adhesion between T cells and antigen-presenting cells (APCs), resulting in formation of a contact zone known as the immune synapse (IS) which is supported by the cytoskeleton. L-plastin is a leukocyte-specific actin bundling protein that rapidly redistributes to the immune synapse following T cell–APC engagement. We used single domain antibodies (nanobodies, derived from camelid heavy-chain only antibodies) directed against functional and structural modules of L-plastin to investigate its contribution to formation of an immune synapse between Raji cells and human peripheral blood mononuclear cells or Jurkat T cells. Nanobodies that interact either with the EF hands or the actin binding domains of L-plastin both trapped L-plastin in an inactive conformation, causing perturbation of IS formation, MTOC docking towards the plasma membrane, T cell proliferation and IL-2 secretion. Both nanobodies delayed Ser⁵ phosphorylation of L-plastin which is required for enhanced bundling activity. Moreover, one nanobody delayed LFA-1 phosphorylation, reduced the association between LFA-1 and L-plastin and prevented LFA-1 enrichment at the IS. Our findings reveal subtle mechanistic details that are difficult to attain by conventional means and show that L-plastin contributes to immune synapse formation at distinct echelons.     

EGF-induced programmed cell death of human mammary carcinoma MDA-MB-468 cells is preceded by activation of AP-1

MDA-MB-468 is a human mammary adenocarcinoma cell line that overexpresses the epidermal growth factor (EGF) receptor and undergoes programmed cell death (apoptosis) in response to EGF treatment. Programmed cell death was shown to be greatly enhanced when cells were growth-arrested prior to EGF treatment. Apoptosis was characterized by an initial rounding up and detachment of the cells from their substrate starting about 12 h after EGF treatment, followed by chromatin condensation, nuclear fragmentation and oligonucleosomal fragmentation of the DNA at about 24 to 48 h. Cell death was dependent on de novo protein synthesis. We found a rapid induction of c-fos, c-jun and junB at the mRNA level after about 30 min of EGF treatment and a more delayed upregulation of fosB and fra-1. The junD gene was expressed in the absence of EGF, and it was moderately induced within 30 min of growth factor addition. The increase of the different fos and jun mRNAs were paralleled by an increase of activator protein-1 (AP-1) DNA binding activity. A characterization of the AP-1 complex revealed similar levels of several Fos and Jun proteins. Based on the kinetics of AP-1 accumulation and cell death, it seems likely that AP-1 contributes to the apoptotic cell death of EGF receptor-overexpressing MDA-MB-468 cells. Received 21 July 1997; received after revision 6 November 1997; accepted 6 November 1997     

Tolerance to,and symmetrical cross-tolerance between,cannabionol and 295-1295-1295-1

Summary Tolerance to, and symmetrical cross-tolerance between, cannabinol and ⁹-tetrahydrocannabinnol (THC) occurs in rabbits which uniquely exhibit behavioral convulsions with THC.This research was supported by funds (grant No.DA01448) and cannabinoids from the National Institute on Drug Abuse.     

Natural killer cell activation by dendritic cells: balancing inhibitory and activating signals

Natural killer (NK) cells have originally been identified by their spontaneous cytolytic potential against tumor cells, which, however, might result from pre-activation due to prior pathogen exposure. Resting NK cells, on the contrary, require activation by bystander antigen-presenting cells to reach their full functional competence. In this review, we will summarize studies on how dendritic cells (DCs), the most potent type of antigen-presenting cell, communicate with human NK cells to activate them in secondary lymphoid organs and to integrate signals from activated NK cells at sites of inflammation for their own maturation. Furthermore, we will review aspects of the immunological synapse, which mediates this cross-talk. These studies provide the mechanistic understanding of how mature DCs can activate NK cells and survive to go on for the activation of adaptive immunity. This feature of DCs, to activate different waves of immune responses, could be harnessed for immunotherapies, including vaccinations.     

Suppressor of cytokine signaling-1 inhibits caspase activation and protects from cytokine-induced beta cell death

Pancreatic beta cell damage caused by pro-inflammatory cytokines interleukin-1β (IL-1β), interferon-γ (IFNγ) and tumor necrosis factor-α (TNFα) is a key event in the pathogenesis of type 1 diabetes. The suppressor of cytokine signaling-1 (SOCS-1) blocks IFNγ-induced signaling and prevents diabetes in the non-obese diabetic mouse. Here, we investigated if SOCS-1 overexpression in primary beta cells provides protection from cytokine-induced islet cell dysfunction and death. We demonstrate that SOCS-1 does not prevent increase in NO production and decrease in glucose-stimulated insulin secretion in the presence of IL-1β, IFNγ, TNFα. However, it decreases the activation of caspase-3, -8 and -9, and thereby, promotes a robust protection from cytokine-induced beta cell death. Our data suggest that SOCS-1 overexpression may not be sufficient in preventing all the biological activities of IFNγ in beta cells. In summary, we show that interference with IFNγ signal transduction pathways by SOCS-1 inhibits cytokine-stimulated pancreatic beta cell death.     

Baroreceptor and sympathetic responses to acebutolol,a 646-1646-1646-1agent,in rabbits

Summary Baroreceptor activity was increased after i.v. infusion of acebutolol in rabbits with an intact circulation, and in rabbits with a total cardiopulmonary by-pass. In rabbits with an intact circulation, renal nerve activity was reduced.We wish to thank Mrs H. Bodard and Mrs F. Raimbault for their technical collaboration and Specia Laboratories for supplying acebutolol. This work was supported by a grant from INSERM (ATP No. 15.75.38).     

Rab44, a novel large Rab GTPase,negatively regulates osteoclast differentiation by modulating intracellular calcium levels followed by NFATc1 activation

Rab44 is an atypical Rab GTPase that contains some additional domains such as the EF-hand and coiled-coil domains as well as Rab-GTPase domain. Although Rab44 genes have been found in mammalian genomes, no studies concerning Rab44 have been reported yet. Here, we identified Rab44 as an upregulated protein during osteoclast differentiation. Knockdown of Rab44 by small interfering RNA promotes RANKL-induced osteoclast differentiation of the murine monocytic cell line, RAW-D or of bone marrow-derived macrophages (BMMs). In contrast, overexpression of Rab44 prevents osteoclast differentiation. Rab44 was localized in the Golgi complex and lysosomes, and Rab44 overexpression caused an enlargement of early endosomes. A series of deletion mutant studies of Rab44 showed that the coiled-coil domain and lipidation sites of Rab44 is important for regulation of osteoclast differentiation. Mechanistically, Rab44 affects nuclear factor of activated T-cells c1 (NFATc1) signaling in RANKL-stimulated macrophages. Moreover, Rab44 depletion caused an elevation in intracellular Ca²⁺ transients upon RANKL stimulation, and particularly regulated lysosomal Ca²⁺ influx. Taken together, these results suggest that Rab44 negatively regulates osteoclast differentiation by modulating intracellular Ca²⁺ levels followed by NFATc1 activation.     

Effects of pertussis toxin on alpha 1-agonist-mediated phosphatidylinositide turnover and myocardial cell hypertrophy in neonatal rat ventricular myocytes

In neonatal rat ventricular myocytes pretreatment with pertussis toxin did not affect 1 microM (-)-norepinephrine stimulation of inositol phosphates or myocardial cell hypertrophy as measured either by protein radiolabelling or by myocardial cell protein content. Thus guanine nucleotide protein(s) ADP-ribosylated by pertussis toxin do not play a role in two alpha 1-adrenoceptor-mediated processes, phosphatidylinositide turnover and induction of myocardial cell hypertrophy.     

Novel wide band gap alloyed semiconductors,x(LiGaO_2)_(1/2)-(1-x)ZnO,and fabrication of their thin films

Oxide semiconductor alloys of x(LiGaO2) 1/2-(1-x) ZnO were fabricated by the solid state reaction betweenβ-LiGaO2 and ZnO and rf-magnetron sputtering.For the solid state reaction,the wurtzite-type single phases were obtained in the composition range of x≤0.38.The formation range of the alloys was wider than that of the(Mg1-xZnx) O system,because the β-LiGaO 2possesses a wurtzite-derived structure and approximately the same lattice constants with ZnO.The electrical resistivity and energy band gap of the 0.38(LiGaO2) 1/2-0.62ZnO alloyed ceramic were 0.45-cm and 3.7 eV,respectively,at room temperature.For the alloying by sputtering,the films consisting of the wurtzite-type single phase were obtained over the entire composition range of x(LiGaO2) 1/2-(1-x) ZnO.The energy band gap was controllable in the range from 3.3 to 5.6 eV.For the as-deposited film fabricated using the 0.4(LiGaO2) 1/2-0.6ZnO alloyed ceramic target,the energy band gap was 3.74 eV,and the electrical resistivity,carrier density and the Hall mobility at room temperature were 3.6-cm,3.4×1017 cm-3and 5.6 cm 2 V-1s-1,respectively.     

Synthesis of the anomeric 9-(2-deoxy-1-D-glucosyl)-adenines and their anhydro derivatives

Zusammenfassung Synthesen von 9-(2-Deoxy-1-D-glukosyl)-adenin und 1-(9-Adenyl)-pseudo-D-glukal werden beschrieben. Diese Substanzen wirken bei der Maus erheblich antileukämisch.     

Differential inhibition of mitochondrial respiratory control by N-1-substituted, 3-, 4-substituted pyridinium halides

Summary Several N-1-alkyl-, 3-, and 4-carbamidopyridinium halides were synthesized and determined to be inhibitors of mitochondrial oxidative phosphorylation. L-Glutamate respiration was most depressed by N-1-dodecylpyridinium bromide whereas succinate respiration was most depressed by N-1-dodecylisonicotinamide bromide. Combination of inhibitors with mitochondrial sites may involve lipophilic interactions as modified by steric restrictions.     

Thyroxine administration and the uptake of amino acids by liver cell nucleolus,nucleus and cytoplasm,and by other cell types

Résumé L'administration de thyroxine cause une chute de l'incorporation de la phénylalanine-H³ et du tryptophane-H³ par divers organes, excepté le foie. Le cytoplasme et les noyaux des hépatocytes ont presenté une plus grande concentration de substance injectée.

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This investigation was supported by grants from Fundaçao de Amparo à Pesquisa do Estado de São Paulo, Rockefeller Foundation, and Conselho Nacional de Pesquisas.

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The help of Profs.L. C. U. Junqueira andC. P. Leblond as well as the technical assistance of MissE. Freymüller are acknowledged.