LOW-PROTEIN DIET IMPAIRS GLUCOSE-INDUCED INSULIN-SECRETION FROM AND CA-45 UPTAKE BY PANCREATIC RAT ISLETS

Glucose-induced insulin secretion rom and Ca-45 uptake by isolated pancreatic islets, derived from rats fed with normal (NPD) or low protein diet (LPD), were studied. Insulin secretion from both types of islets in response to increasing concentrations of glucose followed an S-shaped pattern. However, basal secretion observed at substimulatory concentrations of glucose (0-5.6 mM), as well as maximal release, obtained at 16.7 mM or higher glucose concentrations were significantly reduced in islets from LPD. Furthermore, in LPD rat islets, the dose-response curve to glucose was clearly shifted to the right compared with NPD islets, with the half-maximal response occurring at 8.5 and 14.4 mM glucose for NPD and LPD islets, respectively. In islets from NPD rats, the Ca-45 content, after 5 or 90 min in the presence of 8.3 mM glucose, was higher than that observed for islets kept at 2.8 mM glucose and increased further at 16.7 mM glucose. After 5 min of incubation, the Ca-45 uptake by LPD islets in the presence of 8.3 mM glucose was slightly higher than basal values (2.8 mM glucose); however, no further increase in the Ca-45 uptake was noticed at 16.7 mM glucose. In LPD islets a significant increase in Ca-45 uptake over basal values was registered only at 16.7 mM glucose, after 90 min of incubation. These data indicate that the poor secretary response to glucose observed in islets from LPD rats may be related to a defect in the ability of glucose to increase Ca2+ uptake and/or to reduce Ca2+ efflux from beta-cells.

The 3.4-3.5 Ga Sao Jose do Campestre massif, NE Brazil: remnants of the oldest crust in South America

The oldest fragment of continental crust recognized in South America occurs as an isolated Archean enclave in northeastem Brazil's Borborema Province, ca. 600 Ma Brasiliano-Pan African orogenic belt. This Archean fragment, the Sao Jose do Campestre massif, is surrounded by large tracts of 2.2-2.0 Ga Paleoproterozoic gneisses and is located more than 600-1500 km from the much larger assemblages of Archean rocks found in the Sao Fransciso and Amazonian cratons, located to the south and west, respectively. Geochronological studies of the Sao Jose do Campestre massif show that its oldest rocks contain zircons with U-Pb ages up to 3.5 Ga and Sm-Nd T-DM model ages of more than 3.7 Ga, indicating that they represent reworked crust. This older nucleus is flanked by both reworked and juvenile 3.25 and 3.18 Ga rocks which arc intruded by both 3.00 and 2.69 Ga plutonic bodies. The protracted evolution the Sao Jose do Campestre massif is consistent with that of a larger continental mass as opposed to a small crustal fragment that grew in isolation. As such, the Sao Jose do Campestre massif is interpreted as representing a detached piece of an evolved craton that became entrained with younger rocks during a subsequent Paleoproterozoic accretionary-orogenic event. This hypothesis is bolstered by the presence of Paleoproterozoic gneisses that envelop the Sao Jose do Campestre massif, as well as the existence of ca. 2.0 Ga metamorphic zircon and monazite within its rocks. The occurrence of several different Archean cratonic basement inliers within the greater Paleoproterozoic crustal framework of the Borborema Province suggests that cratonic slices spalled off one or more larger Archean masses prior to the ca. 2.2-2.0 Ga Paleoproterozoic orogenic collage. A important challenge is to link these older fragments to their parent cratons. Although results are not unique, the pattern of ages and isotopic signatures observed in the Sao Jose do Campestre massif is similar to that seen in parts of the Sao Francisco Craton, and it is possible that the Sao Jose do Campestre massif is a fragment of an Archean continental fragment formed during an episode of continental breakup prior to 2200 Ma. (C) 2003 Elsevier B.V. All rights reserved.

Multivariate quality control studies applied to Ca(II) and Mg(II) determination by a portable method

A portable or field test method for simultaneous spectrophotometric determination of calcium and magnesium in water using multivariate partial least squares (PLS) calibration methods is proposed. The method is based on the reaction between the analytes and methylthymol blue at pH 11. The spectral information was used as the X-block, and the Ca(II) and Mg(II) concentrations obtained by a reference technique (ICP-AES) were used as the Y-block. Two series of analyses were performed, with a month's difference between them. The first series was used as the calibration set and the second one as the validation set. Multivariate statistical process control (MSPC) techniques, based on statistics from principal component models, were used to study the features and evolution with time of the spectral signals. Signal standardization was used to correct the deviations between series. Method validation was performed by comparing the predictions of the PLS model with the reference Ca(II) and Mg(II) concentrations determined by ICP-AES using the joint interval test for the slope and intercept of the regression line with errors in both axes. (C) 1998 John Wiley & Sons, Ltd.

Myxedema ascites with elevated serum CA 125 concentration

We report a case of myxedema ascites and markedly elevated serum CA 125 concentration. The cause of ascites and elevated tumor markers in hypothyroidism remains unknown. Diagnosis was characterized by no evidence of malignancy seen by transvaginal ultrasonography or abdominal computed tomography and ascites resolution with serum CA 125 normalization after adequate hormonal treatment. Our data suggest that hypothyroidism should be considered in patients with ascites and elevated serum CA 125.

Magnetic behavior of interstitial Fe impurities in divalent Ca, Sr, and Yb hosts

We have used a first-principles real-space approach to investigate the electronic structure and the magnetic behavior of interstitial Fe impurities in divalent Ca, Sr, and Yb hosts. The dependence of the local moment as a function of lattice relaxation around the impurity is obtained and contrasted with that of interstitial Fe in trivalent and tetravalent Zr, Y, Ti, and Sc hosts. The trends obtained for local moment formation at the impurity site an in agreement with experimental time-differential perturbed gamma-ray angular distribution technique observations.

Caries resistance of lased human enamel with Er : YAG laser - morphological and ratio Ca/P analysis

Objective: In vitro analysis of caries resistance of dental enamel under caries simulation after irradiation with Er:YAG laser. Background Data: More susceptible to caries development spots at adjacent hard tissues from cavity preparations of dental tissues using burrs or lasers are quite common. Methods: Thirteen caries-free third permanent human molars were distributed as follows: G1: sound control and caries control; G2: Er:YAG 100, 200, 300, or 400 mJ/ 10 Hz/ 3 sec.; G3: the same parameters of G2 followed by artificial caries simulation, through dynamic model of demineralization and remineralization (DE/RE). Caries resistance analysis was evaluated through scanning electron microscopy (SEM) and Ca/P rate (X-Rays spectroscopy - EDX). Results: Photomicrographs showed that the Er:YAG laser created craters with rough aspect which became more evident as the energy per pulse was increased, but without change of regular morphology of enamel prisms. Significant statistical changes among the irradiated and control groups was observed considering the Ca/P ratio. Conclusion: Irradiated groups showed higher caries resistance than control groups. However, it is not possible to affirm that the enamel surface accidental irradiation could be a benefit to caries resistance for other situations can be considered, as biofilm deposit, which could increase the caries susceptibility.

The Serido Group of NE Brazil, a late Neoproterozoic pre- to syn-collisional basin in West Gondwana: insights from SHRIMP U-Pb detrital zircon ages and Sm-Nd crustal residence (T-DM) ages

The Serido Group is a deformed and metamorphosed metasedimentary sequence that overlies early Paleoproterozoic to Archean basement of the Rio Grande do Norte domain in the Borborema Province of NE Brazil. The age of the Serido Group has been disputed over the past two decades, with preferred sedimentation ages being either Paleoproterozoic or Neoproterozoic. Most samples of the Serido Formation, the upper part of the Serido Group, have Sm-Nd T-DM ages between 1200 and 1600 Ma. Most samples of the Jucurutu Formation, the lower part of the Serido Group, have T-DM ages ranging from 1500 to 1600 Ma; some basal units have T-DM ages as old as 2600 Ma, reflecting proximal basement. Thus, based on Sm-Nd data, most, if not all, of the Serido Group was deposited after 1600 Ma and upper parts must be younger than 1200 Ma.Cathodoluminescence photos of detrital zircons show very small to no overgrowths produced during ca. 600 Ma Brasiliano deformation and metamorphism, so that SHRIMP and isotope dilution U-Pb ages must represent crystallization ages of the detrital zircons. Zircons from meta-arkose near the base of the Jucurutu Formation yield two groups of ages: ca. 2200 Ma and ca. 1800 Ma. In contrast, zircons from a metasedimentary gneiss higher in the Jucurutu Formation yield much younger ages, with clusters at ca. 1000 Ma and ca. 650 Ma. Zircons from metasedimentary and metatuffaceous units in the Serido Formation also yield ages primarily between 1000 and 650 Ma, with clusters at 950-1000, 800, 750, and 650 Ma. Thus, most, if not all, of the Serido Group must be younger than 650 Ma. Because these units were deformed and metamorphosed in the ca. 600 Ma Brasiliano fold belt during assembly of West Gondwana, deposition probably occurred ca. 610-650 Ma, soon after crystallization of the youngest population of zircons and before or during the onset of Brasiliano deformation.The Serido Group was deposited upon Paleoproterozoic basement in a basin receiving detritus from a variety of sources. The Jucurutu Formation includes some basal volcanic rocks and initially received detritus from proximal 2.2-2.0 Ga (Transamazonian) to late Paleoproterozoic (1.8-1.7 Ga) basement. Provenance for the upper Jucurutu Formation and all of the Serido Formation was dominated by more distal and younger sources ranging in age from 1000 to 650 Ma. We suggest that the Serido basin may have developed as the result of late Neoproterozoic extension of a pre-existing continental basement, with formation of small marine basins that were largely floored by cratonic basement (subjacent oceanic crust has not yet been found). Immature sediment was initially derived from surrounding land; as the basin evolved much of the detritus probably came from highlands to the south (present coordinates). Alternatively, if the Patos shear zone is a major terrane boundary, the basin may have formed as an early collisional foredeep associated with south-dipping subduction. In any case, within 30 million years the region was compressed, deformed, and metamorphosed during final assembly of West Gondwana and formation of the Brasiliano-Pan African fold belts. (C) 2003 Elsevier B.V. All rights reserved.

Improvement of the ferroelectric properties of ABO(3) (A= Pb, Ca, Ba; B=Ti, Zr) films

High-quality ABO(3)/LaNiO3 (A = Ph, Ca, Ba; B = Ti, Zr) hetero structures have been grown on LaAlO3 (1 0 0) substrate by the chemical solution deposition method and crystallized by a microwave oven technique. The structural, morphological and electric properties were characterized by means of X-ray diffraction (XRD), atomic force microscope (AFM), and dielectric and ferroelectric measurements. XRD patterns revealed single-phase polycrystalline and oriented thin films whose feature depends on the composition of the films. The AFM surface morphologies showed a smooth and crack-free surface with the average grain size ranging from 116 to 300 nm for both LaNiO3 electrode and the ferroelectric films. Dielectric measurements on these samples revealed dielectric constants as high as 1800 at frequency of 100 KHz. Such results showed that the combination of the chemical solution method with the microwave process provides a promising technique to grow high-quality thin films with good dielectric and ferroelectric properties. (c) 2005 Elsevier Ltd. All rights reserved.

Non-Ohmic and dielectric properties of a Ca2Cu2Ti4O12 polycrystalline system

An investigation was made into the non-Ohmic and dielectric properties of a Ca2Cu2Ti4O12 perovskite-type system. Compared to the traditional CaCu3Ti4O12-based composition, the imbalance between the Ca and Cu atoms caused the formation of a polycrystalline system presenting similar to 33.3 mol % of CaCu3Ti4O12 (traditional composition) and similar to 66.7 mol % of CaTiO3. As for non-Ohmic properties, the effect of this Ca and Cu atom imbalance was that a nonlinear electric behavior of similar to 1500 was obtained. This high nonlinear electrical behavior emerged in detriment to the ultrahigh dielectric property frequently reported. The high non-Ohmic property was explained by the existence of Schottky-type barriers, whose formation mechanism may be similar to that proposed for traditional metal oxide non-Ohmic devices, according to similarities discussed herein. (c) 2006 American Institute of Physics.

High sinterability of Ca-PZT, synthesized by polymeric and partial oxalate process

This study includes Ca-PZT in the morphotropic phase boundary, MPB process combining the Pechini method, (ZT) and the Partial oxalate method (Ca-PZT) by obtaining single phase particles of ZT phase with a high specific surface area (similar to 110 m(2)/g at 550 degrees C) and narrow particle size distribution. Lead and calcium oxalates were precipitated onto the ZT particle surface and reacted to a solid state interface ZT/Ca-PZT/PbO-CaO. A deviation of a coexistence region from F-T- and F-R-phases to F-R-phase (Zr rich region) was observed. Strong surface area reduction occurs by Ca-PZT crystallization at about 700 degreesC, and demonstrated high sinterability (2.40 m(2)/g - 350 nm) with apparent densities near to 99.9%. Different processing methods did not demonstrate superior results. Studies of calcined powder shows a high sinterability of powder calcined 3 h at 700 degrees C and sintered 3 h at 1000 degreesC coming up to 99.8% of relative density. (C) 2001 Kluwer Academic Publishers.