The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform

Reinier M Mann - One of the best experts on this subject based on the ideXlab platform.

  • The influence of metal speciation on the bioavailability and sub-Cellular Distribution of cadmium to the terrestrial isopod, Porcellio dilatatus.
    Chemosphere, 2011
    Co-Authors: Carla Filipa Calhôa, Marta S Monteiro, Amadeu M V M Soares, Reinier M Mann
    Abstract:

    Abstract Cadmium is a non-essential toxic metal that is able to bioaccumulate in both flora fauna and has the potential to biomagnify in some food chains. However, the form in which cadmium is presented to consumers can alter the bioavailability and possibly the internal Distribution of assimilated Cd. Previous studies in our laboratory highlighted differences in Cd assimilation among isopods when they were provided with a plant-based food with either Cd biologically incorporated into plant tissue or superficially amended with ionic Cd 2+ . Cd is known for its high affinity for sulphur ligands in cysteine residues which form the basis for metal-binding proteins such as metallothionein. This study compares Cd assimilation efficiency (AE) in Porcellio dilatatus fed with food amended with either cadmium cysteinate or cadmium nitrate in an examination of the influence of Cd speciation on metal bioavailability followed by an examination of the sub-Cellular Distribution using a centrifugal fractionation protocol. As hypothesized the AE of Cd among isopods fed with Cd(NO 3 ) 2 (64%, SE = 5%) was higher than AE for isopods fed with Cd(Cys) 2 (20%, SE = 3%). The sub-Cellular Distribution also depended on the Cd species provided. Those isopods fed Cd(Cys) 2 allocated significantly more Cd to the cell debris and organelles fractions at the expense of allocation to metal-rich granules (MRG). The significance of the difference in sub-Cellular Distribution with regard to toxicity is discussed. This paper demonstrates that the assimilation and internal detoxification of Cd is dependent on the chemical form of Cd presented to the isopod.

James R. Connor - One of the best experts on this subject based on the ideXlab platform.

  • Regional and Cellular Distribution of mitochondrial ferritin in the mouse brain
    Journal of neuroscience research, 2010
    Co-Authors: Amanda M. Snyder, Elizabeth B. Neely, Sonia Levi, Paolo Arosio, James R. Connor
    Abstract:

    Iron and mitochondrial dysfunction are important in many neurodegenerative diseases. Several iron transport proteins have been identified that are associated with mitochondria, most recently mitochondrial ferritin. Here we describe the Cellular Distribution of mitochondrial ferritin in multiple regions of the brain in C57/BL6 mice. Mitochondrial ferritin was found in all regions of the brain, although staining intensity varied between regions. Mitochondrial ferritin was detected throughout the layers of cerebral cortex and in the cerebellum, hippocampus, striatum, choroid plexus, and ependymal cells. The cell type in the brain that stains most prominently for mitochondrial ferritin is neuronal, but oligodendrocytes also stain strongly in both gray matter and in white matter tracts. Mice deficient in H-ferritin do not differ in the mitochondrial ferritin staining pattern or intensity compared with C57/BL6 mice, suggesting that there is no compensatory expression of these proteins. In addition, by using inbred mouse strains with differing levels of iron content, we have shown that regional brain iron content does not affect expression of mitochondria ferritin. The expression of mitochondria ferritin appears to be more influenced by mitochondrial density. Indeed, at an intraCellular level, mitochondrial ferritin immunoreaction product is strongest where mitochondrial density is high, as seen in the ependymal cells. Given the importance and relationship between iron and mitochondrial activity, understanding the role of mitochondrial ferritin can be expected to contribute to our knowledge of mitochondrial dysfunction and neurodegenerative disease.

  • Cellular Distribution of iron in the brain of the Belgrade rat.
    Neuroscience, 1999
    Co-Authors: Joseph R. Burdo, Sharon Menzies, Kevin G. Dolan, Michelle A. Romano, R.j. Fletcher, Laura M. Garrick, Michael D Garrick, J. Martin, James R. Connor
    Abstract:

    Abstract In this study, we investigated the Cellular Distribution of iron in the brain of Belgrade rats. These rats have a mutation in Divalent Metal Transporter 1, which has been implicated in iron transport from endosomes. The Belgrade rats have iron-positive pyramidal neurons, but these are fewer in number and less intensely stained than in controls. In the white matter, iron is normally present in patches of intensely iron-stained oligodendrocytes and myelin, but there is dramatically less iron staining in the Belgrade rat. Those oligodendrocytes that stained for iron did so strongly and were associated with blood vessels. Astrocytic iron staining was seen in the cerebral cortex for both normal rats and Belgrade rats, but the iron-stained astrocytes were less numerous in the mutants. Iron staining in tanycytes, modified astrocytes coursing from the third ventricle to the hypothalamus, was not affected in the Belgrade rat, but was affected by diet. The results of this study indicate that Divalent Metal Transporter 1 is important to iron transport in the brain. Iron is essential in the brain for basic metabolic processes such as heme formation, neurotransmitter production and ATP synthesis. Excess brain iron is associated with a number of common neurodegenerative diseases. Consequently, elucidating the mechanisms of brain iron delivery is critical for understanding the role of iron in pathological conditions.

  • Cellular Distribution of iron, transferrin, and ferritin in the hypotransferrinemic (Hp) mouse brain
    The Journal of Comparative Neurology, 1995
    Co-Authors: Thomas K. Dickinson, James R. Connor
    Abstract:

    Hypotransferrinemic (Hp) mice have a point mutation or small deletion in the transferrin (Tf) gene, resulting in defective splicing of precursor Tf mRNA. Hp animals produce < 1% of normal Tf levels and require supplemental serum or purified Tf for survival. Because of the lack of endogenous brain Tf, we examined regional and Cellular Distributions of iron and iron regulatory proteins (Tf and ferritin) in selected brain regions of Hp mice. The regional Distribution of iron, Tf, and ferritin in Hp brain was similar to normal except for the pattern of iron staining in hippocampus. The Cellular Distribution of iron, ferritin, and Tf was similar between Hp and normal animals. The predominant cell type staining for Tf and iron was oligodendrocytes. Qualitative observations suggest that the number of cells staining for iron was similar between Hp and normal mice, whereas the number of Hp Tf-positive cells was reduced. Ferritin immunostaining was similar in both cases. However, ferritin-positive cells were predominantly astrocytes, an observation unique to mice among species studied previously. Western blot analysis revealed that Tf present in Hp brain was of exogenous origin (from supplemental injections). Presumably, Tf transports the iron found in Hp oligodendrocytes. These data demonstrate that, despite reduced endogenous Hp brain Tf, iron and plasma Tf migrate or are transported to the appropriate cells (oligodendrocytes), bringing into question the role of endogenous brain Tf in extraCellular iron transport.

  • Isoforms of ferritin have a specific Cellular Distribution in the brain.
    Journal of Neuroscience Research, 1994
    Co-Authors: James R. Connor, Stanley A Benkovic, K. L. Boeshore, Sharon Menzies
    Abstract:

    Ferritin is the major iron storage protein and accounts for the majority of the iron in the brain. Thus, ferritin is a key component in protecting the brain from iron induced oxidative damage. The high lipid content, high rate of oxidative metabolism, and high iron content combine to make the brain the organ most susceptible to oxidative stress. The role of oxidative damage and disruption of brain iron homeostasis is considered clinically important to normal aging and a potential pathogenic component of a number of neurologic disorders including Alzheimer's disease and Parkinson's disease. Little is known, however, of the mechanism by which the brain maintains iron homeostasis at either the whole organ or Cellular level. In this study we report the Cellular Distribution of the two isoforms of ferritin in the brain of adult subhuman primates. A subset of neurons immunolabel specifically for the H-chain ferritin protein, whereas cells resembling microglia are immunolabeled only after exposure to the L-chain ferritin antibody. Only one cell type immunostains for both H-and L-chain ferritin; these cells are morphologically similar and have the same Distribution pattern as oligodendrocytes. Neither ferritin isoform is usually detected in astrocytes. These data indicate considerable differences in iron sequestration and use between neurons and glia and among neuronal and glial subtypes. This information will be essential in determining the role of each of these cells in maintaining general brain iron homeostasis and the relative abilities of these cells to withstand oxidative stress. © 1994 Wiley-Liss, Inc.

Carla Filipa Calhôa - One of the best experts on this subject based on the ideXlab platform.

  • The influence of metal speciation on the bioavailability and sub-Cellular Distribution of cadmium to the terrestrial isopod, Porcellio dilatatus.
    Chemosphere, 2011
    Co-Authors: Carla Filipa Calhôa, Marta S Monteiro, Amadeu M V M Soares, Reinier M Mann
    Abstract:

    Abstract Cadmium is a non-essential toxic metal that is able to bioaccumulate in both flora fauna and has the potential to biomagnify in some food chains. However, the form in which cadmium is presented to consumers can alter the bioavailability and possibly the internal Distribution of assimilated Cd. Previous studies in our laboratory highlighted differences in Cd assimilation among isopods when they were provided with a plant-based food with either Cd biologically incorporated into plant tissue or superficially amended with ionic Cd 2+ . Cd is known for its high affinity for sulphur ligands in cysteine residues which form the basis for metal-binding proteins such as metallothionein. This study compares Cd assimilation efficiency (AE) in Porcellio dilatatus fed with food amended with either cadmium cysteinate or cadmium nitrate in an examination of the influence of Cd speciation on metal bioavailability followed by an examination of the sub-Cellular Distribution using a centrifugal fractionation protocol. As hypothesized the AE of Cd among isopods fed with Cd(NO 3 ) 2 (64%, SE = 5%) was higher than AE for isopods fed with Cd(Cys) 2 (20%, SE = 3%). The sub-Cellular Distribution also depended on the Cd species provided. Those isopods fed Cd(Cys) 2 allocated significantly more Cd to the cell debris and organelles fractions at the expense of allocation to metal-rich granules (MRG). The significance of the difference in sub-Cellular Distribution with regard to toxicity is discussed. This paper demonstrates that the assimilation and internal detoxification of Cd is dependent on the chemical form of Cd presented to the isopod.

  • The influence of metal speciation on the bioavailability and sub-Cellular Distribution of cadmium to the terrestrial isopod, Porcellio dilatatus
    'Elsevier BV', 1
    Co-Authors: Carla Filipa Calhôa, Monteiro, Marta S., Soares, Amadeu M. V. M., Mann, Reinier M.
    Abstract:

    Cadmium is a non-essential toxic metal that is able to bioaccumulate in both flora fauna and has the potential to biomagnify in some food chains. However, the form in which cadmium is presented to consumers can alter the bioavailability and possibly the internal Distribution of assimilated Cd. Previous studies in our laboratory highlighted differences in Cd assimilation among isopods when they were provided with a plant-based food with either Cd biologically incorporated into plant tissue or superficially amended with ionic Cd(2+). Cd is known for its high affinity for sulphur ligands in cysteine residues which form the basis for metal-binding proteins such as metallothionein. This study compares Cd assimilation efficiency (AE) in Porcellio dilatatus fed with food amended with either cadmium cysteinate or cadmium nitrate in an examination of the influence of Cd speciation on metal bioavailability followed by an examination of the sub-Cellular Distribution using a centrifugal fractionation protocol. As hypothesized the AE of Cd among isopods fed with Cd(NO(3))(2) (64%, SE = 5%) was higher than AE for isopods fed with Cd(Cys)(2) (20%, SE = 3%). The sub-Cellular Distribution also depended on the Cd species provided. Those isopods fed Cd(Cys)(2) allocated significantly more Cd to the cell debris and organelles fractions at the expense of allocation to metal-rich granules (MRG). The significance of the difference in sub-Cellular Distribution with regard to toxicity is discussed. This paper demonstrates that the assimilation and internal detoxification of Cd is dependent on the chemical form of Cd presented to the isopod. (C) 2010 Elsevier Ltd. All rights reserved

Johannes C Baayen - One of the best experts on this subject based on the ideXlab platform.

  • expression and Cellular Distribution of multidrug resistance related proteins in the hippocampus of patients with mesial temporal lobe epilepsy
    Epilepsia, 2004
    Co-Authors: Eleonora Aronica, Marja Ramkema, Filiz Ozbasgerceker, S. Redeker, Edwin A Van Vliet, Jan A. Gorter, George L. Scheffer, Paul Van Der Valk, Rik J Scheper, Johannes C Baayen
    Abstract:

    Summary: Purpose: This study investigated the Cellular Distribution of different multidrug resistance (MDR)-related proteins such as P-glycoprotein (P-gp), the multidrug resistance–associated proteins (MRP) 1 and 2, and the major vault protein (MVP) in normal and sclerotic hippocampus of patients with medically refractory mesial temporal lobe epilepsy (MTLE). Methods: Single- and double-label immunocytochemistry was used on brain sections of control hippocampus and of hippocampus of refractory MTLE patients. Results: In TLE cases with hippocampal sclerosis (HS), all four MDR proteins examined that had low or no expression in control tissue were upregulated, albeit with different Cellular Distribution patterns. P-gp immunoreactivity (IR) was observed in astrocytes in regions with diffuse reactive gliosis. In 75% of HS cases, strong P-gp IR was detected in blood vessels, with prominent endothelial labeling. Reactive astrocytes displayed low MRP1 IR. However, glial MRP1 expression was noted in glial endfoot processes around blood vessels. Neuronal MRP1 expression was observed in hypertrophic hilar neurons and in a few residual neurons of the CA1 region. Hippocampal MRP2 expression was observed in the large majority of HS cases in blood vessels. Hypertrophic hilar neurons and blood vessels within the sclerotic hippocampus expressed major vault protein (MVP). Conclusions: These findings indicate that MDR proteins are upregulated in concert in the hippocampus of patients with refractory MTLE, supporting their role in the mechanisms underlying drug resistance. The specific cell-Distribution patterns within the sclerotic hippocampus suggest different Cellular functions, not necessarily linked only to clinical drug resistance.

Mauro Sola-penna - One of the best experts on this subject based on the ideXlab platform.