bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low-temperature hydrothermal alteration of natural metamict zircons from the Eastern Desert, Egypt
Authors: Geisler T. , Rashwan A. A. , Rahn M. K. W. , Poller U. , Zwingmann H. , Pidgeon R. T. , Schleicher H. , Tomaschek F. 
Published: June 2003

AbstractThe chemical and structural alteration of metamict zircon crystals from a 619 ±17 (2σ) Ma old, posttectonic granite in the southern part of the Eastern Desert, Egypt was studied. The crystals show simple oscillatory growth zones with metamictization–induced fractures, which provided pathways for fluid infiltration. Electron and ion microprobe analyses reveal that metamict, i.e. U and Th–rich, areas are heavily enriched in Ca, Al, Fe, Mn, LREE, and a water species, and have lost Zr and Si as well as radiogenic Pb. These chemical changes are the result of an intensive reaction with a low–temperature (120—200°C) aqueous solution. The chemical reactions probably occurred within the amorphous regions of the metamict network. During the zircon–fluid interactions the metamict structure was partially recovered, as demonstrated by micro-Raman and -infrared measurements. A threshold degree of metamictization, as defined empirically by an α–decay dose, Dc, was necessary for zircons to undergo hydrothermal alteration. It is proposed that Dc marks the first percolation point, where the amorphous domains start to form percolating clusters in the metamict network and where bulk chemical diffusion is believed to increase dramatically. The time of the hydrothermal alteration is determined by a lower intercept age of a U-Pb SHRIMP discordia of 17.9 (2σ) Ma, which is in good agreement with an apatite fission track age of 22.2 (2σ) Ma. The hydrothermal alteration event occurred contemporaneously with the main rifting phase of the Red Sea and widespread low- temperature mineralizations along the Red Sea coast.
Hydroxylian pseudorutile in an adamellite from the Nkambe area, Cameroon
Authors: Tetsopgang S. , Koyanagi J. , Enami M. , Kihara K. 
Published: June 2003

AbstractHydroxylian pseudorutile in an adamellite from Cameroon has been identified using EPMA, FT-IR and single-crystal XRD analysis. TiO2 and Fe2O3 contents range between 60.6 and 67.9 wt.% and 22.2 and 36.5 wt.%, respectively, and totals vary from 90.1 to 98.1 wt.%. The SiO2 (0.03 —1.40 wt.%), Al2O3 (0.02—0.68 wt.%) and CaO (0.03—0.44 wt.%) contents increase systematically and MnO (0.04—0.69 wt.%) decreases slightly with decreasing Fe3+/Ti values. The MgO content is <0.06 wt.%. H2O contents (1.3—7.5 wt.%) are greater in parts of crystals with lower Fe3+/Ti, suggesting solid solution between the end-members Fe3+2Ti3O9 and Fe3+Ti3O6(OH)3. The lattice parameters are a = 2.85 Å and c = 4.57 Å with hexagonal symmetry and point group 6/mmm.
Chromian tourmaline and associated Cr-bearing minerals from the Nevado-Fildbride Complex (Betic Cordilleras, SE Spain)
Authors: Torres-Ruiz J. , Pesquera A. , López Sánchez-Vizcaíno V. 
Published: June 2003

AbstractChromian tourmaline, in association with other Cr-bearing minerals (amphibole, mica, epidote, chlorite, titanite, rutile and chromian spinel), occurs in fine calc-schist levels within metacarbonate rocks from the Nevado-Filabride Complex, SE Spain. Electron microprobe analyses of tourmaline and coexisting minerals document both chemical differences dependent on the host-rock type and an irregular distribution of Cr at grain scale. Tourmaline is Na-rich dravite, with average Mg/(Mg+Fe) ratios of 0.83 and 0.63 a.p.f.u. and Cr contents of 0.32 and 0.18 a.p.f.u., in dolomitic and ankeritic marbles, respectively. Tourmaline contains small but significant concentrations of Zn (av. 0.01 a.p.f.u.) and in ankeritic marble it also contains Ni (av. 0.04 a.p.f.u.). Zn-rich chromian spinel appears as small relict inclusions in silicates, with average Cr, Fe, Al and Zn contents of 1.201, 1.241, 0.411 and 0.107 a.p.f.u., respectively. Amphibole, epidote, mica and chlorite show average Cr contents of 0.088, 0.138, 0.115 and 0.267 a.p.f.u., respectively, in dolomitic marbles, and 0.103, 0.078, 0.065 and 0.185 a.p.f.u., respectively, in ankeritic marbles. Cr-silicates formed through metamorphic reactions involving detrital Cr-rich spinel, in addition to clay minerals and carbonates. The B necessary to form tourmaline was probably derived from the leaching of underlying evaporitic rocks.
Thermal expansion of nepheline-kalsilite crystalline solutions
Authors: Hovis G. L. , Crelling J. , Wattles D. , Dreibelbis B. , Dennison A. , Keohane M. , Brennan S. 
Published: June 2003

AbstractEleven nepheline-kalsilite crystalline solutions with various proportions of K:Na have been studied from room temperature to 1050/11500C by X-ray powder diffraction. Nepheline expansion is relatively high and little affected by composition, whereas kalsilite expansion is lower but affected to a significant degree by K:Na ratio. The generally higher rate of expansion in nepheline is apparently related to the collapse of the tetrahedral framework around the smaller of its two alkali sites. Occupancy of these sites by the relatively small Na ion fürther extends the potential for thermal vibration before the structure is stretched to the critical degree required for phase transformation. Once the structure changes to that of kalsilite, with its single alkali site, an increase in content of the larger K ion limits the degree to which kalsilite can expand. Crucial to the overall expansion behaviour of these minerals are the specific tetrahedral configurations of nepheline vs. kalsilite, the number and geometry of their alkali sites, the occupancies of those sites, and the flexibility inherent in each structure that allows for adjustment with increasing temperature.
The influence of next nearest neighbours on cation radii in spinels: the example of the Co3O4-CoCr2O4 solid solution
Authors: O’Neill H. St. C. 
Published: June 2003

AbstractLattice parameters and crystal structures of the synthetic spinels Co3O4, CoCr2O4, and solid solutions in the binary join Co3O4-CoCr2O4, have been determined by powder X-ray diffraction structural refinements. In all these spinels the cation distribution is completely normal at room temperature, and the tetrahedrally coordinated cation site is occupied only by Co2+. The ionic radius of Co2+(tet) increases from 0.556(3) in Co3O4 to 0.599(4) in CoCr2O4. In the spinel structure, the interatomic distance between the tetrahedral cations and oxygen are geometrically independent of those between the octahedral cations and oxygen; thus the variation in effective ionic radii is ascribed to next-nearest neighbour effects, induced by covalent tendencies in the low-spin Co3+-O bond. The results demonstrate that the assumption of constant ionic radii even within an isomorphic group such as the oxide spinels needs to be made with caution.
Hydrogen bonding in ikaite, CaCO3.6H2O
Authors: Swainson I. P. , Hammond R. P. 
Published: June 2003

AbstractIkaite is a metastable hexahydrate of calcium carbonate, forming in aqueous conditions near freezing conditions. Neutron powder diffraction data of synthetic deuterated ikaite, collected at seven temperatures from 4 to 270 K, were refined. The linear thermal expansion coefficients are quite anisotropic, being smaller in the direction of the C—O bond. A review of the hydrogen-bonding scheme around the (CaCO03) ion pair is given and an additional weak potential hydrogen bond is suggested. Temperature-dependent growth of the atomic displacement factors of the carbonate O1 atom agrees with the previous suggestion of a possible low-frequency, hindered librational mode of the carbonate group.
Preparation of TEM samples by focused ion beam (FIB) techniques: applications to the study of clays and phyllosilicates in meteorites
Authors: Lee M. R. , Bland P. A. , Graham G. 
Published: June 2003

AbstractTransmission electron microscope samples were prepared of ALH 78045 and ALH 88045, two clay-and phyllosilicate-bearing Antarctic meteorites, using argon ion milling and focused ion beam (FIB) techniques. ALH 78045 contains clay- and phyllosilicate-filled veins that have formed by terrestrial weathering of olivine, orthopyroxene and metal. Very narrow (∼10 nm) intragranular clay-filled veins could be observed in the TEM samples prepared by argon ion milling, whereas differential thinning and lack of precision in the location of the electron-transparent areas hindered the study of wider (5 — 15 μm) phyllosilicate-filled intergranular veins. Using the FIB instrument, electron-transparent slices were cut from specific parts of the wider veins and lifted out for TEM study. Results show that these veins are occluded by cronstedtite, a mixed-valence Fe-rich phyllosilicate. This discovery shows that silicates can be both dissolved and precipitated during terrestrial weathering within the Antarctic ice. ALH 88045 is one of a small number of known CM1 carbonaceous chondrites. This meteorite is largely composed of flattened ellipsoidal aggregates of serpentine-group phyllosilicates. To determine the mineralogy and texture of phyllosilicates within specific aggregates, TEM samples were prepared by trenching into the cut edge of a sample using the FIB instrument. Results show that Mg-rich aggregates are composed of lath-shaped serpentine crystals with a ∼0.73 nm basal spacing, which is typical of the products of low temperature aqueous alteration within asteroidal parent bodies. Results of this work demonstrate that the FIB has enormous potential in a number of areas of Earth and planetary science.
Serine phosphorylation of STAT3 is essential for Mcl-1 expression and macrophage survival
Authors: Liu Hongtao , Ma Yingyu , Cole Shawn M. , Zander Christopher , Chen Kun-Hung , Karras Jim , Pope Richard M. 
Published: June 2003

AbstractThe Bcl-2 family member Mcl-1 is essential for macrophage survival. However, the mechanisms that contribute to the expression of Mcl-1 in these cells have not been fully characterized. The present study focused on the role of signal transducer and activator of transcription 3 (STAT3) in regulation of Mcl-1 in macrophages. Sodium salicylate (NaSal) treatment induced apoptotic cell death in primary human macrophages in a dose- and time-dependent fashion. Incubation with NaSal resulted in the loss of mitochondrial transmembrane potential, the release of cytochromecand second mitochondria-derived activator of caspase/direct IAP binding protein with low pH of isoelectric point (pI) from the mitochondria, and the activation of caspases 9 and 3. Western blot analysis and reverse transcription—polymerase chain reaction demonstrated that NaSal down-regulated the expression of Mcl-1. Electrophoretic mobility shift assay and Western blot analysis for phosphorylated STAT3 demonstrated that STAT3 was constitutively activated in macrophages and that this STAT3 activation was suppressed by NaSal. The activation of STAT3 in macrophages was dependent on Ser727 phosphorylation, in the absence of detectable Tyr705phosphorylation. Ectopic expression of STAT3 in murine RAW264.7 macrophages rescued the inhibition of Mcl-1 promoter-reporter gene activation and the cell death induced by NaSal treatment, while a dominant-negative STAT3 resulted in cell death. To confirm its role in primary macrophages, STAT3 antisense (AS) oligodeoxynucleotides (ODNs) were employed. STAT3 AS, but not control, ODNs decreased STAT3 and Mcl-1 expression and resulted in macrophage apoptosis. These observations demonstrate that the STAT3-mediated expression of Mcl-1 is essential for the survival of primary human in vitro differentiated macrophages. (Blood. 2003;102:344-352)
Result of high-dose imatinib mesylate in patients with Philadelphia chromosome—positive chronic myeloid leukemia after failure of interferon-α
Authors: Cortes Jorge , Giles Francis , O'Brien Susan , Thomas Deborah , Garcia-Manero Guillermo , Rios Mary Beth , Faderl Stefan , Verstovsek Srdan , Ferrajoli Alessandra , Freireich Emil J. , Talpaz Moshe , Kantarjian Hagop 
Published: June 2003

Abstract
Imatinib at 400 mg daily is effective in chronic-phase chronic myeloid leukemia (CML) after interferon failure, although only a few patients achieve a molecular remission. We investigated whether higher doses of imatinib may be more effective. Thirty-six patients with chronic-phase CML after failure on interferon-α were treated with 400 mg imatinib twice daily. Median time from diagnosis was 25 months (range, 10-135 months); 4 patients (11%) had clonal evolution. All 11 patients with active disease achieved complete hematologic response. Excluding patients with fewer than 35% Ph-positive metaphases before the start of therapy, 19 (90%) of 21 evaluable patients achieved a major cytogenetic response. Of 27 evaluable patients, 24 (89%) achieved a complete cytogenetic response. Quantitative polymerase chain reaction was performed in bone marrow every 3 months. Of 32 evaluable patients, 18 (56%) showed BCR-ABL/ABL percentage ratios lower than 0.045%, including 13 (41%) with undetectable levels. With a median follow-up of 15 months, all patients were alive in chronic phase. Toxicities were similar to those reported with standard dose; 71% of patients continue to receive 600 mg or more of imatinib daily. In conclusion, high-dose imatinib induces complete cytogenetic responses in most patients with chronic-phase CML after interferon failure. This is accompanied by a high rate of molecular remission. (Blood. 2003;102:83-86)
Targeting the cell cycle machinery for the treatment of cardiovascular disease
Authors: Bicknell Katrina A , Surry Elizabeth L , Brooks Gavin 
Published: June 2003

Abstract
Cardiovascular disease represents a major clinical problem affecting a significant proportion of the world's population and remains the main cause of death in the UK. The majority of therapies currently available for the treatment of cardiovascular disease do not cure the problem but merely treat the symptoms. Furthermore, many cardioactive drugs have serious side effects and have narrow therapeutic windows that can limit their usefulness in the clinic. Thus, the development of more selective and highly effective therapeutic strategies that could cure specific cardiovascular diseases would be of enormous benefit both to the patient and to those countries where healthcare systems are responsible for an increasing number of patients. In this review, we discuss the evidence that suggests that targeting the cell cycle machinery in cardiovascular cells provides a novel strategy for the treatment of certain cardiovascular diseases. Those cell cycle molecules that are important for regulating terminal differentiation of cardiac myocytes and whether they can be targeted to reinitiate cell division and myocardial repair will be discussed as will the molecules that control vascular smooth muscle cell (VSMC) and endothelial cell proliferation in disorders such as atherosclerosis and restenosis. The main approaches currently used to target the cell cycle machinery in cardiovascular disease have employed gene therapy techniques. We will overview the different methods and routes of gene delivery to the cardiovascular system and describe possible future drug therapies for these disorders. Although the majority of the published data comes from animal studies, there are several instances where potential therapies have moved into the clinical setting with promising results.
Efficacy and irritancy of enhancers on the in-vitro and in-vivo percutaneous absorption of curcumin
Authors: Fang Jia-You , Hung Chi-Feng , Chiu Hsien-Chih , Wang Jhi-Joung , Chan Te-Fu 
Published: June 2003

Abstract
Curcumin is a predominant compound derived from the rhizomes of Curcuma longa L., and shows antibacterial, anti-inflammatory and antineoplastic activity. The in-vitro and in-vivo skin absorption of curcumin was investigated after application of enhancers using Wistar rat as an animal model. The enhancers selected in this study included terpenes, flavonoids and cholestanol. The irritant profiles of these enhancers were also established by transepidermal water loss (TEWL) and histological observations. Cyclic monoterpenes generally showed stronger enhancement of curcumin permeation than the other enhancers. Modulation of concentration and pretreatment duration of enhancers possibly indicated that the enhancers have varied ability and mechanisms to enhance curcumin permeation. Terpineol produced the highest TEWL values among the enhancers tested, whereas ketocholestanol produced no, or only a negligible, increase in TEWL as compared with control. The results showed that skin disruption and inflammation did not necessarily correspond to the enhancing efficiency of the enhancers.
Studies on the transport of thyrotropin-releasing hormone (TRH) analogues in Caco-2 cell monolayers
Authors: Urayama Akihiko , Yamada Shizuo , Deguchi Yoshiharu , Ohmori Yuki , Kimura Ryohei 
Published: June 2003

Abstract
The transport mechanisms of thyrotropin-releasing hormone (TRH) and its pharmacologically active analogues ((3-methyl-His2)TRH (MeTRH), taltirelin, montirelin, azetirelin) across Caco-2 cell monolayers were characterized. The results of kinetic analysis showed a linear relationship between the concentration (over the range 0.5–10 mm) and apical-to-basolateral transport rate of these agents. The permeability coefficients (Papp) of these agents were not substantially different from each other, and their (Papp) ratios of the basolateral-to-apical over the apical-to-basolateral transport were close to one (0.73–1.23). The cellular transport of [3H]MeTRH at low concentrations (3–15 nm) showed a linear relationship between the concentration and transport rate. The transport of [3H]MeTRH in Caco-2 cell monolayers was neither affected by TRH nor TRH analogues, and there was little difference in (Papp) values between [3H]MeTRH and [14C]mannitol. The cell-per-medium ratio of [3H]MeTRH in the cellular uptake experiment was similar to the value of [14C]mannitol. A large excess of TRH and MeTRH did not significantly influence cell-per-medium ratios of [3H]MeTRH in Caco-2 cell monolayers. The k'IAM value, which represents lipophilicity, was decreased in the following order: montirelin &gt; taltirelin &gt; TRH &gt; azetirelin, and the values varied from 0.234 to 1.028. These results indicate that a paracellular passive diffusion may be the major route for the transport of TRH and its analogues in Caco-2 cell monolayers.
Tolerance to the hypnotic and electroencephalographic effect of gamma-hydroxybutyrate in the rat: pharmacokinetic and pharmacodynamic aspects
Authors: Van Sassenbroeck Diederik K , de Paepe Peter , Belpaire Frans M , Boon Paul A , Buylaert Walter A 
Published: June 2003

Abstract
Tolerance to gamma-hydroxybutyrate (GHB) has been suggested in illicit users and has been described for the hypnotic effect in the rat. The aim of this study was to investigate whether tolerance is also observed for the EEG effect, and whether the EEG can give insight into the pharmacodynamic aspects of GHB tolerance. In three series of experiments, rats were pre-treated with either the GHB precursor gamma-butyrolactone (GBL) or saline intraperitoneally twice daily. In the first series, a reduction in sleeping time was observed in the GBL pre-treated rats compared with controls. In the second series, a fast infusion of GHB (300 mg kg−1 over 5 min) was given after 10 days pre-treatment. The GHB plasma concentration-time curves showed a slightly faster decrease in GHB concentration in the GBL pre-treated rats, suggesting a small induction of the GHB metabolism (Vmax = 2882 ± 457 μg min−1 kg−1 vs 2205 ± 315 μg min−1 kg−1, P&lt;0.01). In contrast to controls, GBL pre-treated rats did not lose righting reflex. In the third series, a slow infusion of 480 mg kg−1 h−1 was given after 7 days pre-treatment, which allowed fitting a sigmoid Emax model to the EEG amplitude versus GHB plasma concentration curve. This showed reduced end-organ sensitivity to GHB in the GBL pre-treated rats (EC50 (concentration required to obtain 50% depression of the baseline effect) = 653 ± 183 μg mL−1 vs 323 ± 68 μg mL−1, P &lt; 0.001). In conclusion, chronic pre-treatment with gamma-butyrolactone in the rat results in a reduced sleeping time and this tolerance is reflected by the EEG. This can mainly be explained by reduced end-organ sensitivity.
Kinetics of metabolism and degradation of mometasone furoate in rat biological fluids and tissues
Authors: Teng X W , Cutler D J , Davies N M 
Published: June 2003

Abstract
Mometasone furoate (MF) is a potent glucocorticoid developed for the treatment of glucocorticoid-responsive inflammatory disorders. The in-vitro and ex-vivo kinetics of the degradation and metabolism of MF were studied in selected biological fluids of rat and subcellular fractions of different rat tissues. In-vitro, MF was found to degrade slowly into four products in serum and urine, and metabolized rapidly and extensively in rat liver, minimally in extrahepatic tissues, including intestine, stomach, lung and kidney. Further investigation found that the microsomal fraction was the major intracellular site of MF 6β-hydroxylation in rat liver. Using chemical inhibitors, CYP3A was found to be the major enzyme involved in the in-vitro MF 6β-hydroxylation in rat liver microsomes. Enzyme kinetic studies in rat liver microsomes showed that the overall metabolic process of MF followed biphasic Michaelis-Menten kinetics, while 6β-hydroxylation obeyed monophasic Michaelis-Menten kinetics. The kinetic parameters derived from the kinetic models along with the enzyme inhibition studies suggest that MF is mainly metabolized via 6β-hydroxylation mediated by CYP3A primarily, and also biotransformed via other pathway(s) catalysed by other enzymes in rat liver in-vitro.
Hepatic biotransformation of the new calcium-mimetic agent, RWJ-68025, in the rat and in man — API-MS/MS identification of metabolites
Authors: Wu Wu-Nan , McKown Linda A , Rybczynski Philip J , Demarest Keith 
Published: June 2003

Abstract
The in-vitro biotransformation of a new calcium-mimetic agent and benzenemethanamine analogue, RWJ-68025, was studied after incubation with rat and human hepatic S9 fractions in the presence of an NADPH-generating system. Unchanged RWJ-68025 (44–48% of the sample) plus 12 metabolites were profiled, quantified, and tentatively identified on the basis of API (ionspray)-MS and MS/MS data, and ethyl derivatization for phenolic and carboxylic metabolites. Four metabolic pathways for RWJ-68025 were proposed: pathway 1, O-demethylation; pathway 2, phenyl oxidation; pathway 3, methyl oxidation; and pathway 4, N-dealkylation/acetylation. Pathway 1 formed a major metabolite, O-desmethyl-RWJ-68025 (M1; RWJ-68311; 26% in rat; 16% in human fraction). Pathway 2 produced one major (M2; 12–17% in rat and human fraction) and two minor phenolic metabolites (M4 and M5; all &lt;1% in both species), and in conjunction with step 1, formed hydroxy-M1 (M3; 4–5% in both species). Pathways 3 and 4 formed seven minor oxidized metabolites (M6–M12). RWJ-68025 was extensively metabolized in the rat and human hepatic S9 fractions.