856 research outputs found
IN VIVO E IN VITRO MODULATORY EFFECT OF HUMAN IMMUNODEFICIENCY VIRUS TYPE-1 (HIV-1)TAT PROTEIN ON PROTEIN KINASE C ACTIVITY
No full textExtracellular HIV-1 Tat protein shows a pleiotropic activity on the survival/proliferation of different cell types, which may be relevant to the pathogenesis of the immune suppression as well as of the frequent neoplastic disorders observed during the course of HIV-1 disease. Therefore, we investigated the effect of recombinant Tat on the protein kinase C (PKC) activity in Jurkat CD4(+) T lymphoma cells by using a serine substituted specific PKC peptide substrate, which allowed the evaluation of the whole catalytic activity of both Ca++-dependent and Ca++-independent PKC isoforms. High concentrations of recombinant Tat (1 mu g/ml) induced an early (5 min) stimulation followed by a secondary (30-60 min) inhibition of PKC in whole Jurkat cell homogenates. Immuno-localization experiments showed that recombinant Tat protein was rapidly taken up by Jurkat cells within the first 5 min from the addition in culture, thus suggesting the possibility that the secondary inhibitory phase of Tat on PKC activity in Jurkat cells could be due to a direct interaction between the two proteins. Consistently, PKC immunoprecipitated from Jurkat cells or purified from rat brain was significantly inhibited by the addition of high (0.1-1 mu g) but not low (1-10 ng) doses of Tat in a cell-free in vitro assay. The inhibition of PKC catalytic activity mediated by 1 mu g of Tat was at least partially due to competition among substrates. The present data may help in understanding the opposite effects on the survival/proliferation of different cell types observed in the presence of picomolar (stimulation) vs nanomolar (inhibition) concentrations of recombinant Tat
HIV-1 TAT PROTEIN SUPPRESSES THE NERVE GROWTH FACTOR (NGF)- MEDIATED DIFFERENTIATION OF PC12 RAT PHEOCHROMOCYTOMA CELL LINE
No full textIn order to evaluate the effect of the regulatory human immunodeficiency virus-type 1 (HIV-1) Tat protein on the process of neuronal differentiation, two tat-transfected and mock-transfected PC12 cell lines were cultured in the absence or presence of 100-1000 ng/ml of nerve growth factor (NGF). As expected, NGF was able to induce a clearcut morphological differentiation of mock-transfected PC12 into sympathetic-like neurons, also reducing the percentage of cells in S phase. On the other hand, NGF was unable to reduce the percentage of PC12-tat cells in S phase and/or to induce their neuronal differentiation. Only the addition in culture of 5 mu g/ml neutralizing anti-Tat antibody plus 1000 ng/ml NGF was effective in decreasing the percentage of PC12-tat in S phase and inducing partial signs of neuronal differentiation in serum-free cultures. The ability of Tat protein to suppress the neuronal differentiation pathway controlled by NGF further contribute to the definition of its role in tumor promotion during the course of HTV-1 disease
Factors influencing the first thousand days of life: Elena Capitani
No full textBACKGROUND: The first 1000 days are crucial for the health of the baby and the well-being of the mother-baby dyad, which forms a single complex organism with its co-metabolism expressed through sophisticated neurobiological, epigenetic and microbiome development mechanisms. This study aims to investigate how much social support can influence the path of pregnancy and motherhood. METHODS: The retrospective observational study was conducted on a sample of mothers enrolled through social networks who were administered a questionnaire from July to September 2021. The questionnaire consisted of 37 questions: 11 analyzed sociodemographic variables, 20 were on current / any previous pregnancies and breastfeeding, and 6 were used to calculate the Maternity Social Support Scale (MSSS-Webster et al.). STATA 14 was used for statistical analysis. RESULTS: Our sample consisted of 3447 women. 88.0% wanted the pregnancy, and 63.5% planned it. The average of the Maternity Social Support Scale (MSSS) was 23.91 points. A low MSSS score correlates with a higher risk of cessation of breastfeeding before 6 months of age, a higher risk of not having spontaneous labour, a higher risk of cesarean section and a higher risk of not having a spontaneous birth. On the other hand, a higher MSSS total score is a protective factor concerning breastfeeding duration, which is more likely to be longer-lasting (>6 months), to have spontaneous onset labour with a higher probability of spontaneous delivery. CONCLUSIONS: The results showed that most of our sample have good friends who support them, can often count on their family, and receive help from their partner/husband. The outcomes of pregnancy, childbirth and motherhood are strongly influenced and conditioned by the social context in which they occur and the support the woman can receive. The presence or lack of this support can affect the health of newborns. KEY MESSAGES: • The first 1,000 days is a vulnerable phase in which parents, institutions and health professionals should create early interventions for the proper development and promotion of good health. • the outcomes of pregnancy, birth and motherhood are strongly influenced and conditioned by the social context, but especially by the presence or lack of support that can affect the health of newborns
Cannonite [Bi2O(SO4)(OH)2] from Alfenza (Crodo, Italy): Crystal structure and morphology
No full textCanonite from Alfenza grows as crowded, radiating, acicular aggregates covering bismuthinite
crystals. Individual crystals have a lozenge-shaped habit on {010}, the presumed cleavage plane of
cannonite. Crystal structure refinements in the P21/c space group of two single crystals led to the
following cell parameters: a = 7.7196(5) A ̊ , b = 13.8856(9), c = 5.6980(4), b = 109.174(1)o (R1 =
0.0424); and a = 7.7100(8), b = 13.8717(14), c = 5.6939(6), b = 109.155(2)o (R1 = 0.0438). Hydrogen
atoms were also localized in the density-difference Fourier map and refined with soft restraints on the
bond distances. Raman and IR spectroscopy confirm the presence of OH groups and the absence of
molecular water, and deliver OH···O geometry wholly comparable with the structure refinement.
Electron microprobe analyses revealed no significant levels of elements other than those expected in
the ideal formula except fluorine which was present up to 0.14 a.p.f.u. The crystal structure can be
described in terms of anion-centred OBi4 edge-sharing tetrahedra forming chains running parallel to z
and strongly cemented along x by isolated SO4 tetrahedra. Each OBi4 tetrahedron is further connected
along y by OH groups, making walls of composition Bi4O2(SO4)2(OH)4 parallel to (010). These walls
are tied to each other along y by fewer Bi–O–S bridges and weaker OH···O bonds
The peculiar crystal-chemistry of phlogopite from metasomatized peridotites: evidence from laboratory and nature
No full textExperimental petrology suggested that phlogopite has a peculiar mineral chemistry at high pressure: excess of Si coupled with a decrease in IVAl and deficiency in K+Na. This K-edenite exchange, □XIISi(K+Na)-1Al-1, where □XII is a vacancy in the interlayer, should imply that phlogopites incorporate significant amount of talc component. At high pressure conditions, however, in a fluid saturated system, a talc component might translate into a 10 Å phase component, being the latter phase the product of the reaction talc + H2O = 10 Å phase occurring at P = 4-5 GPa and at T = 600-700 °C. We aim to study the structure of natural and synthetic phlogopites showing this peculiar mineral chemistry. Samples were analysed by single-crystal X-ray diffraction, powder X-ray diffraction with full profile fitting, EMP, SIMS, TEM and Mössbauer spectroscopy. The natural samples were recovered from spinel and garnet wedge peridotites of the Ulten Zone Eastern Italian Alps, (Italy), whereas synthetic ones were obtained from high pressure synthesis in a K-doped lherzolite system. The single crystal X-ray refinements of natural phlogopites, together with the EMP analysis, showed two coupled substitutions: Tschermak (Si + Mg = IVAl + VIAl) and talc exchanges (□ + Si = K + Al), with no octahedral vacancies. The Rietveld refinement of the synthetic samples confirmed the ipersilicic character and K deficiency found with EMPA and SIMS analysis. The c lattice parameter of both synthetic and natural phlogopites positively correlates with the increase of vacancies at the interlayer site, pointing toward the c lattice parameter of the 10Å phase. The tetrahedral α rotation angle of natural phlogopites was about 9°, lower than that expected by Tschermak substitution. The present data indicate that the 10 Å phase component, instead of the talc component, stabilizes the phlogopite structure by reducing the α rotation under high pressure condition. This increases the pressure conditions needed to reach the upper limit value for the tetrahedral rotation
Electron diffraction tomography for the characterization of sub-micrometric minerals: application to metamict phases
No full textSingle-crystal X-ray diffraction can be performed only on crystalline domains of some cubic microns, while most
of hitherto unsolved minerals and many new synthetic phases do not grow in crystals of such dimensions. On
the other hand, interpretation of X-ray powder diffraction data may be problematic for polyphasic samples and
structures characterized by large cell parameters or pseudo-symmetry. Electron diffraction is able to deliver 3D
structural data from single crystallites of few nanometers. This ability derives from the high cross section
between electrons and matter and the possibility to focus the electron beam into a nanometric probe. In the
last years, electron diffraction tomography (EDT) emerged as an efficient method for acquiring complete and
quasi-kinematic data sets for ab-initio structure determination of sub-micrometric phases (Kolb et al., 2011).
The mineral charoite was one of the first structures determined on the basis of EDT data, and still one of the
trickiest crystallographic cases faced by electron diffraction. Despite the fact that charoite is a well-known and
commercially exploited mineral, its symmetry and structure determination was hampered because two
commensurate and pseudo-symmetric polytypes grow together inside fibers less than 1 μm thick
(Rozhdestvenskaya et al., 2011). In recent years, tomographic electron diffraction has been used for the
characterization of several minerals and products of experimental geology occurring as minor, sub-micrometric
phases in poly-mineralogical associations. The porous (S2)1+x[Bi9-xTex(OH)6O8(SO4)2]2 was the first natural phase
initially recognized, and subsequently structurally determined, by EDT alone (Capitani et al., 2014).
Recently, EDT has been employed for the characterization of metamict phases. Metamict minerals undergo
structural changes and amorphization due to the radioactive decay of hosted elements. Phase identification is
commonly done on the basis of compositional data alone, or by powder diffraction performed after the sample
has been heated in order to produce re-crystallization. Still, different compositional and mineralogical domains
may merge in the process. We therefore exploited EDT for the characterization of sub-micrometric crystalline
relicts in metamict domains, allowing single-crystal ab-initio determination of natural samples without the
need of any physical treatment
Selective modulation of specific protein kinase C (PKC) isoforms in primary human megakaryocytic vs. erythroid cells.
No full textWe have investigated the pattern of expression of classical (alpha, betaI, betaII, gamma), novel (delta) and atypical (zeta) protein kinase C (PKC) isoforms during the course of human hematopoietic differentiation along the closely related megakaryocytic and erythroid lineages. Using in situ immunofluorescence analysis, freshly isolated human pluripotent CD34+ hematopoietic progenitor cells expressed detectable amounts of all the PKC isoforms investigated. On the other hand, clear-cut differences in terms of PKC staining were noticed between cells belonging to the erythroid and megakaryocytic lineages, obtained after 9 days of serum-free liquid culture in the presence of specific growth factors. Specifically, 1) erythroid cells showed a very weak expression of PKC-alpha, -betaI, -betaII, and -gamma, while megakaryocytes showed an enhanced expression of all classical PKC isoforms, predominantly confined to the cytoplasm; 2) the expression of PKC-delta increased in the cytoplasmic and nuclear compartments of both erythroid and megakaryocytic cells with respect to CD34+ cells; and 3) atypical PKC-zeta isoform showed a striking accumulation in the nucleus during both erythroid and megakaryocytic differentiation
Changes of nuclear protein kinase C activity and isotype composition in PC12 cell proliferation and differentiation.
No full textTo establish whether protein kinase C was involved in the nuclear events underlying cell differentiation and proliferation, rat pheochromocytoma PC12 cells, serum-starved for 24 h, were treated with either differentiating doses of nerve growth factor or high serum concentrations, which represented a powerful mitogenic stimulus. Western blot analysis with isoform-specific antibodies, performed on whole cell homogenates, cytoplasms, and purified nuclei, showed that PKC isotypes alpha, beta I, beta II, delta, epsilon, eta, and zeta were expressed in PC12 cells and that all of them, except for beta I, were found at the nuclear level, variably modulated depending on the cell treatment. Compared to serum-stimulated cells, in which an early (1 day) and marked rise of protein kinase C activity was followed by a plateau, nerve growth factor-treated cells showed a progressive increase of protein kinase C activity coincident with the onset and maintenance of the differentiated phenotype. Western blot analysis of nuclei isolated from fully differentiated cells demonstrated an increase of protein kinase C alpha, paralleled by enhanced phosphotransferase activity along with the nerve growth factor treatment, and complete loss of the delta isotype. In contrast, in nuclei of proliferating PC12 cells, after an early but modest increase at 1 day of mitogenic stimulation, protein kinase C activity reached a plateau. Isotype-specific analysis indicated a concomitant increase of protein kinase C beta II, delta, and zeta and the appearance of protein kinase C epsilon and eta at the nuclear level. Considering the relative intensity of the cytoplasmic and nuclear immunoreactive bands under the three conditions examined, clear-cut translocation to the nucleus occurred for PKC epsilon and eta in serum-stimulated cells. Additional nuclear accumulation of PKC by translocation from the cytoplasm was prominently induced for the zeta isoform after mitogenic stimulation and for PKC alpha during prolonged NGF treatment. Our data suggest that nuclear translocation and selective activation of distinct protein kinase C isoforms play a relevant role in the control of proliferation and differentiation of the same cell type and that nuclear protein kinase C is crucial to the induction and persistence of the differentiated neuronal phenotype of PC12 cells
Thermal decomposition of cement–asbestos at 1100 °C: how much “safe” is “safe”?
No full textThe products of cement-asbestos treated in air at 1100 degrees C were characterized by a multi-methodological approach to determine: (i) the effective deactivation of harmful asbestos fibers; (ii) the mineralogy and microstructure of the inert product and its possible use as a secondary raw material (SRM); and (iii) any potential health hazard of the SRM. For this purpose, energy-dispersive X-ray fluorescence spectrometry (EDXRF), X-ray powder diffraction (XRPD), scanning, and transmission electron microscopy (SEM and TEM) analyses were performed. The powdered SRM was also analyzed by dynamic laser scattering and solution leaching experiments, to determine grain size distribution and possible elements release. Our results confirm the deactivation of crocidolite and chrysotile asbestos fibers, but at the same time evidence a significant fraction of nanoparticles in the SRM and some critical releases of SO42-, F- and Cr6+ in solution. Both the nanoparticle fraction and the critical elemental release may pose human health concern and adversely affect potential applications of the SRM. Strategies to control the grain size distribution through adjusted thermal treatment conditions and microwave-assisted grinding operations are discussed. Possible routes to safely reuse the SRM are indicated
The 6H-SiC structure model: Further refinement from SCXRD data from a terrestrial moissanite
No full textThe crystal structure of a terrestrial 6H-SiC moissanite has been refined in the P63mc S.G. from area detector single crystal X-ray data, down to an R-index on the observed reflections of 0.0205. The cell parameters refined over all the collected reflections are a = 3.0810(2) and c = 15.1248(10) Å. The average Si-C bond lengths are 1.8898 Å, with average bonds along the stacking direction (1.8993 Å) slightly longer than those along the bilayer (1.8862 Å). The interlayer distances, defined as the distances along [0001] between Si-Si layers, which may occur either in cubic (c) or hexagonal (h) configurations, are maximal at the c-h interface (2.5270 Å) and minimal at the h-c interface (2.5165 Å), entailing that the h-bilayer is not equidistant from either c-bilayers. All the tetrahedral angles are identical within the experimental error and close to the ideal value of 109.47°, but those at the c-h interface, where a significant distortion of 0.15° is recorded. Finally, the anisotropic displacement factors are utterly very small, identical among different atoms within the experimental error, and significantly spherical. It thus appears that the 6H-SiC structure is affected by a slight relaxation along the [0001] stacking direction with respect to the ideal cubic structure, and that the relaxation is mainly accomplished at the c-h interface, i.e., at the twin-like boundary, where a bilayer in cubic configuration links a bilayer in antiparallel, hexagonal configuration. As far as we know this is the first crystal structure refinement of a natural 6H-SiC moissanite. Possible implications on the polytype stability in the light of these results are briefly discussed
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