1,721,244 research outputs found
Fluoronyboite from Jianchang (Su-Lu, China) and nyboite from Nybo (Nordfjord, Norway): A petrological and crystal-chemical comparison of these two high-pressure amphiboles
No full textThermoelasticity, cation exchange, and deprotonation in Fe-rich holmquistite: Toward a crystal-chemical model for the high-temperature behavior of orthorhombic amphiboles
No full textThe thermoelastic behavior of a crystal of Fe-rich holmquistite with crystal-chemical formula A(K0.01Na0.01)B(Li1.88Mg0.10Na0.02)C(Mg1.68Fe1.422+ Mn0.022+ Al1.88)TSi8.00O22W[(OH)1.97F0.03] was studied by single-crystal X‐ray diffraction at temperatures up to 1023 K, where isothermal annealing in air for 160 h yielded the loss of 0.85 H apfu coupled with oxidation of M1Fe. A complex pattern of cation exchanges was deciphered by comparing structure refinements done before and after annealing. Li migration from the M4 to M3 site is responsible for nonlinearity of the c parameter around 600 K during the first annealing. Cooling of the partially deprotonated crystal to room temperature (RT) showed discontinuities in trends of the b and c parameters around 820-800 K, which cannot be ascribed to a phase transition and can be explained by a rearrangement of the structural units affecting the geometry of the M4 polyhedron. Such discontinuities have never been observed in amphiboles before and must be related to dimensional constraints deriving from the peculiar composition of this amphibole, which contains the smallest possible homovalent constituents, i.e., BLi, CAl, and TSi. The calculated thermoelastic parameters are: Fe-rich holmquistite: αa = 1.36(2)×10-5; αb = 0.55(1)×10-5; αc = 1.5(1)×10-5 - 6.7(9)×10-9; αV = 3.5(3)×10-5 - 0.8(3)×10-8 (polynomial); 2.58(6)×10-5 (linear); partially deprotonated Fe-rich holmquistite: αa = 1.324(9)×10-5 (RT-1023 K); αb = 0.60(1)×10-5 (RT-773 K); αc = 0.68(2)×10-5 (RT-773 K); αV = 2.59(2)×10-5 (RT-773 K). Fe-rich holmquistite is much stiffer than all the previously studied orthorhombic Pnma and Pnmn amphiboles. The results of this work allow progress toward a general model that may explain how the amphibole structure responds to non-ambient conditions, and allows the release of water in diverse geological environments
B-cell lymphomagenesis and human autoimmune models.
No full textAbstract
The concept that B-cell lymphomagenesis represents a multistep process is widely accepted. Pathogenetic events should be better defined both in early and late stages of lymphoproliferation. In the past few years, novel study approaches have been focused on understanding the mechanisms of lymphomagenesis. In particular, immune stimulation by infectious agents or autoantigens, T-cell help, altered immunocompetence, and local cytokine networks seem to be crucial in favouring B-cell expansions. In turn, actively proliferating B cells are at higher risk of undergoing genetic alterations that make the clone capable of fully autonomous growth, i.e., fully neoplastic. Peculiar human autoimmune diseases predisposing to B-cell lymphoma represent relevant models to characterize and dissect the temporal sequence of the different lyphomagenetic events. The present review, particularly, focuses on Sjoegren's syndrome, and on recent findings regarding the putative role of hepatitis C virus in B-cell lymphoproliferation. The biologic and clinical implications may be of major relevance for other B-cell disorders characterized by higher prevalence and morbidity
Case report 381: Membranous lipodystrophy (MLD).
No full textThis disease was recognized for the first time by Jarvi in 1964
and named "Hereditary Folycystic Osteodysplasia (HPO)" [5].
In 1973, Nasu et al. [6] reported an autopsied case that pre-
sented the same features as HPO and because of the histological
findings, the authors of that manuscript called the entity
"Membranous Lipodystrophy". Up to the present time only
27 cases have been reported in the world literature, exclusively
in four countries - Finland, Japan, Norway and the USA [1-7].
Mental changes and corresponding lesions of the central
nervous system have been associated often with MLD [1, 3,
6], but the relationship between pathological changes in the
skeleton and brain remains unclear. The etiology of the disease
is unknown. Hakola [3] reported three affected members in
the same family, but this observation was not confirmed in
other reports.
In summary, a fascinating case of an entity called "mem-
branous lipodystrophy" has been described in a 35-year-old
woman. Multiple, cyst-like disseminated, skeletal lesions were
present throughout (except for the spine, innominate bones,
ribs and skull). In addition, resorption of bone and a very
thin periosteum were identified. Coarse and irregular trabeculae
also were noted. Associated with the skeletal lesions in this
instance, were hydrocephalus, cerebral cortical atrophy and
multiple calcifications in the basal ganglia bilaterally.
The development of mental changes and lesions of the cen-
tral nervous system as indicated are said to be associated con-
sistently with MLD. The cause of the disorder is considered
to be unknown.
The pathological studies were described in depth and the
differential diagnosis was considered.
It is believed by the editor that this case report, describing
this entity, is a significant contribution to the literature on a
disease of great interest, probably unknown to many pphysicians
On the symmetry and atomic ordering in (OH,F)-rich spessartine: towards a new hydrogarnet end-member
No full text""The symmetry and crystal chemistry of a (OH,F)-rich spessartine. from Junzico Xijang, Wushan Spessartine Mine,. Yunxiao Co., Fujian Province, P.R. China, with composition. X(Mn2+. 2.87Fe2+. 0.09Ca0.04) Y(Al1.94Fe3+. 0.06) Z[(SiO4)2.52. (OH1.11F0.81)] have been studied by single-crystal X-ray. structure refinement and FTIR spectroscopy. This sample is. tetragonal, space group I41\\\/acd, with a = b = 11.6347(3) Å,. c = 11.6449(3) Å, c\\\/a = 1.006, Rall 3.1% (θmax = 55°). The. two independent tetrahedra differ significantly both in. terms of refined bond-lengths and site-scattering values, the. latter allowing to confirm the extent of the (OH,F) substitution. and to its preferential ordering at O3, the site occupied. by the anions coordinated to Z2. FTIR spectra consist of a. prominent peak at 3568 cm-1 and a doublet at 3622-3632. cm-1. Pleochroic curves suggest assignment to a unique OH. dipole, involved in two different hydrogen bonds (O3-. H...O2 and O3-H...O3, the latter showing two different, OH.... H and O-H...F, configurations). The observed space. group and composition imply: (a) that lowering in symmetry. is related to the presence of (OH,F)4 groups; (b) the. existence of a new hydrogarnet end-member with ideal. composition XMn3. YAl2. Z[(SiO4)2(OH)4] and significant F. content, the first related to the pyralspite series; the sample. of this work is close to its 50:50 solid solution with spessartine.. Geometric considerations and the very limited increase. in volume with respect to spessartine suggest that the presence. of F is a requisite for the incorporation of significant. amount of monovalent anions in pyralspites."
Activation of infiltrating cytotoxic T lymphocytes and lymphoma cell apoptotic rates in gastric MALT lymphomas - Differences between high-grade and low-grade cases
No full textIn this study, we have characterized infiltrating T lymphocytes from 13 low-grade and 17 high-grade primary gastric MALT lymphomas by immunohistochemistry, with particular regard to the presence, activation, and topographic distribution of cytotoxic effecters. Although the prevalence of CD4+ and CD8+ cells was similar in low- and high-grade lymphomas, higher numbers of TIA-1+ cytotoxic effecters were found in this latter group of cases (11.6 versus 7.8%; P = 0.004), Activation of CD8+ cytotoxic T lymphocytes (CTLs) was significantly more pronounced in high than in low-grade lymphomas, as shown by immunostaining for perforin (8.7 versus 4.0%; P = 0.001) and granzyme-B (GrB) (8.7% versus 3.0%; P < 0.0001), Of note, CD20/GrB double labeling showed that high-grade lymphomas carried a markedly higher content (about ninefold) of activated CTLs relative to the number of CD20+ lymphoma B cells (0.081 +/- 0.076 versus 0.009 +/- 0.011; P < 0.0001). Moreover, high-grade lymphomas showed significantly increased apoptotic rates compared to low grade cases (5.3 and 1.1% of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells, respectively; P < 0.0001). In the whole series, the percentage of GrB+ cells and the GrB+/CD20+ ratio showed a strong Linear correlation with the number of TUNEL-labeled cells. These findings, together with the frequent colocalization of CTLs and TUNEL+ neoplastic cells, suggested that apoptotic death of lymphoma cells may be due at least in part to the killing by cytotoxic effecters. Our results are consistent with the occurrence of host antitumor cell-mediated immune responses in gastric MALT lymphomas, Moreover, the finding of stronger cytotoxic responses in high than in low-grade cases is of potential usefulness in the design of more effective therapeutic strategies for the management of these disorders.In this study, we have characterized infiltrating T lymphocytes from 13 low-grade and 17 high-grade primary gastric MALT lymphomas by immunohistochemistry, with particular regard to the presence, activation, and topographic distribution of cytotoxic effectors. Although the prevalence of CD4+ and CD8+ cells was similar in low- and high-grade lymphomas, higher numbers of TIA-1+ cytotoxic effectors were found in this latter group of cases (11.6 versus 7.8%; P = 0.004). Activation of CD8+ cytotoxic T lymphocytes (CTLs) was significantly more pronounced in high- than in low- grade lymphomas, as shown by immunostaining for perforin (8.7 versus 4.0%; P = 0.001) and granzyme-B (GrB) (8.7% versus 3.0%; P < 0.0001). Of note, CD20/GrB double labeling showed that high-grade lymphomas carried a markedly higher content (about ninefold) of activated CTLs relative to the number of CD20+ lymphoma B cells (0.081 ± 0.076 versus 0.009 ± 0.011; P < 0.0001). Moreover, high-grade lymphomas showed significant..
The crystal structure of beryllonite from the type locality and comparison with isopointal structures
No full textThe crystal structure of beryllonite, NaBePO4, has been re-evaluated based on high-resolution X-ray diffraction data using a single crystal from the type locality, Stoneham (Maine, USA). Beryllonite is monoclinic, with a = 8.1309(2) Å, b = 7.7974(2) Å, c = 14.1918(4) Å, ß = 90.039(1)°, V = 899.76(4) Å3, space group P21/n (no. 14), Z = 12. Full anisotropic crystal-structure refinement converged to an R1 value of 0.0504 based on all 9435 unique reflections in the θ range 2–50°. The crystal structure consists of a framework of PO4 and BeO4 tetrahedra sharing all vertexes with adjacent tetrahedra. On the (010) plane, each tetrahedron shares three vertexes with three different tetrahedra forming a quasi-ditrigonal 63 net with alternating PO4 and BeO4 tetrahedra. The remaining vertex of each PO4 and BeO4 tetrahedra points outside the (010) plane and allows corner-linkage among the tetrahedral sheets. Na-centred polyhedra with six-and nine-fold coordinations are located in channels defined by the framework of tetrahedral rings. Beryllonite is isostructural with several natural and synthetic compounds and for these, a quantitative comparison of the crystal-chemical features is reported
Association Between B-Type Epstein-Barr-Virus and Hodgkins-Disease in Immunocompromised Patients
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