scholarly journals Accumulation of Calcium and Loss of Potassium in the Hippocampus following Transient Cerebral Ischemia: A Proton Microprobe Study

1988 ◽  
Vol 8 (4) ◽  
pp. 531-538 ◽  
Author(s):  
Eduardo Martins ◽  
Kenji Inamura ◽  
Klas Themner ◽  
Klas G. Malmqvist ◽  
Bo K. Siesjö
Keyword(s):  
Hippocampal Neurons ◽  
Plasma Membranes ◽  
Total Calcium ◽  
Calcium Cycling ◽  
Transient Ischemia ◽  
Neuronal Necrosis ◽  
X Ray ◽  
Proton Microprobe ◽  
Calcium Accumulation ◽  
Stratum Oriens

This study explored (a) whether postischemic accumulation of calcium in hippocampal neurons precedes or occurs pari passu with light microscopical signs of delayed neuronal necrosis, and (b) whether calcium initially accumulates in dendritic domains, presumed to have a high density of agonist-operated calcium channels. Transient ischemia of 10-min duration was induced in rats, and the animals were studied after 1, 2, 3, and 4 days of recovery. We measured total calcium and potassium contents in the stratum oriens, pyramidale, radiatum, and moleculare of the CA1 and CA3 sectors, using particle induced x-ray emission (PIXE) in the proton microprobe mode. The results showed significant accumulation of calcium and loss of potassium after 3 and 4 days of recovery in the CA1 sector, which developed neuronal necrosis, but not in the CA3 sector, which showed only occasional damage. In a few animals, calcium accumulation (and loss of potassium) was observed with no or only mild visible damage, but in the majority of animals the accumulation of calcium correlated to signs of neuronal necrosis. Since calcium accumulation was similar in all strata examined, the results failed to reveal preferential accumulation in dendritic or somal regions. Based on our results and those of Dux et al., we emphasize the possibility that delayed neuronal death is, at least in part, caused by increased calcium cycling of plasma membranes and gradual calcium overload of mitochondria.

Immunohistochemical localization of lysosomal cysteine protease cathepsins B and L in monkey hippocampal neurons after transient ischemia

1999 ◽  
Vol 19 (3) ◽  
pp. 302-310
Author(s):  
Yukihiko Kohda ◽  
Katsuhiro Tsuchiya ◽  
Junkoh Yamashita ◽  
Masaki Yoshida ◽  
Takashi Ueno ◽  
...  
Keyword(s):  
Cysteine Protease ◽  
Hippocampal Neurons ◽  
Immunohistochemical Localization ◽  
Transient Ischemia ◽  
Lysosomal Cysteine Protease

Small angle X-ray diffraction studies on the topography of cannabinoids in synaptic plasma membranes

1991 ◽  
Vol 40 (3) ◽  
pp. 547-552 ◽  
Author(s):  
Thomas Mavromoustakos ◽  
De-Ping Yang ◽  
Wanda Broderick ◽  
Donna Fournier ◽  
Alexandros Makriyannis
Keyword(s):  
Small Angle ◽  
Plasma Membranes ◽  
X Ray Diffraction ◽  
Synaptic Plasma Membranes ◽  
X Ray

DATA SMOOTHING TECHNIQUES APPLIED TO PROTON MICROPROBE SCANS OF TELEOST HARD PARTS

1992 ◽  
Vol 02 (03) ◽  
pp. 313-323 ◽  
Author(s):  
I.F. WEST ◽  
G.E. COOTE ◽  
R.W. GAULDIE
Keyword(s):  
Life Histories ◽  
Moving Average ◽  
Sampling Point ◽  
Smoothing Techniques ◽  
Data Smoothing ◽  
X Ray ◽  
Proton Microprobe ◽  
Median Filters ◽  
Data Points ◽  
Hard Structures

We use a proton microprobe to examine the distribution of elements in otoliths and scales of teleost (bony) fish. The elements of principal interest are calcium and strontium in otoliths and calcium and fluorine in scales. Changes in the distribution of these elements across hard structures may allow inferences about the life histories of fish. Otoliths and scales of interest are up to a centimeter in linear dimension and to reveal the structures of interest up to 200 sampling points are required in each dimension. The time needed to accumulate high X-ray counts at each sampling point can be large, particularly for strontium. To reduce microprobe usage we use data smoothing techniques to reveal changing patterns with modest X-ray count accumulations at individual data points. In this paper we review performance for revealing pattern at modest levels of X-ray count accumulations of a selection of digital filters (moving average smoothers), running median filters, robust locally weighted regression filters and adaptive spline filters.

scholarly journals ELECTRON PROBE ANALYSIS OF THE CALCIUM DISTRIBUTION IN CELLS OF THE EMBRYONIC CHICK CHORIOALLANTOIC MEMBRANE I. A CRITICAL EVALUATION OF TECHNIQUES

1972 ◽  
Vol 20 (6) ◽  
pp. 401-413 ◽  
Author(s):  
JAMES R. COLEMAN ◽  
A. RAYMOND TEREPKA
Keyword(s):  
Electron Probe ◽  
Critical Evaluation ◽  
Chorioallantoic Membrane ◽  
Embryonic Chick ◽  
Total Calcium ◽  
Electron Probe Analysis ◽  
X Ray ◽  
Chick Chorioallantoic Membrane ◽  
Minor Losses

The chorioallantoic membrane of the developing chick embryo is an epithelium that actively transports calcium. The methodology utilized to prepare this soft tissue for calcium localization with the electron probe x-ray microanalyzer is presented in detail. The preparative procedures are evaluated according to general histochemical principles and in relationship specifically to electron probe investigations. It is shown that the method employed in these studies preserves the normal fine structure of the tissue, prevents selective loss of calcium, permits only minor losses of total calcium and appears to maintain the distribution of calcium that existed in vivo. Examples are presented of artifacts that can be induced during tissue sectioning and mounting procedures. Problems of defining electron probe resolution in biologic specimens are discussed, and the critical importance of evaluating x-ray images in association with simultaneously generated sample current images is emphasized.

Imidazo[1,2-b]Pyridazines. XVI. Synthesis and Central Nervous System Activities of Some 6-(Chloro, Alkylthio, Phenylthio, Benzylthio or Pyridinylmethylthio)-3-(unsubstituted, benzamidomethyl or methoxy)-2-(styryl or benzoyl)imidazo[1,2-b]pyridazines

1994 ◽  
Vol 47 (11) ◽  
pp. 1989 ◽  
Author(s):  
GB Barlin ◽  
LP Davies ◽  
PW Harrison ◽  
NW Jacobsen ◽  
AC Willis
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Rat Brain ◽  
Plasma Membranes ◽  
Benzodiazepine Receptors ◽  
X Ray

Some 6-( chloro, alkylthio, phenylthio, benzylthio or pyridinylmethylthio )-3-( unsubstituted , benzamidomethyl or methoxy )-2-styrylimidazo[1,2-b] pyridazines and 6-chloro-3-( unsubstituted and benzamidomethyl )-2-benzoylimidazo[1,2-b] pyridazines have been prepared and tested for their ability to displace [3H]diazepam from rat brain plasma membranes. The structures of 6-chloro-2-benzoyl[and 6-fluoro-2-(4′-tolyl)] imidazo [1,2-b] pyridazine have been confirmed by X-ray analyses. The reactions of 6-methylthio(and 6-phenylthio)pyridazin-3-amines with 3-bromo-1-phenylpropane-1,2-dione also have been investigated. The 6-substituted 3-unsubstituted 2-styryl(and benzoyl ) imidazo [1,2-b] pyridazines did not bind strongly to rat brain benzodiazepine receptors; nor did the 3-benzamidomethyl or 3-methoxy derivatives (cf. the 2-phenyl analogues). However, 3-benzamidomethyl-6-(pyridin-3-ylmethylthio)-2-styrylimidazo[1,2-b] pyridazine was an exception with IC50 68 nM.

scholarly journals Correlating STED and synchrotron XRF nano-imaging unveils cosegregation of metals and cytoskeleton proteins in dendrites

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Florelle Domart ◽  
Peter Cloetens ◽  
Stéphane Roudeau ◽  
Asuncion Carmona ◽  
Emeline Verdier ◽  
...  
Keyword(s):  
Trace Metals ◽  
Neuronal Plasticity ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Memory Formation ◽  
Stimulated Emission ◽  
X Ray ◽  
Nano Imaging ◽  
Zinc Chelation ◽  
Synaptic Level

Zinc and copper are involved in neuronal differentiation and synaptic plasticity but the molecular mechanisms behind these processes are still elusive due in part to the difficulty of imaging trace metals together with proteins at the synaptic level. We correlate stimulated-emission-depletion microscopy of proteins and synchrotron X-ray fluorescence imaging of trace metals, both performed with 40 nm spatial resolution, on primary rat hippocampal neurons. We reveal the co-localization at the nanoscale of zinc and tubulin in dendrites with a molecular ratio of about one zinc atom per tubulin-αβ dimer. We observe the co-segregation of copper and F-actin within the nano-architecture of dendritic protrusions. In addition, zinc chelation causes a decrease in the expression of cytoskeleton proteins in dendrites and spines. Overall, these results indicate new functions for zinc and copper in the modulation of the cytoskeleton morphology in dendrites, a mechanism associated to neuronal plasticity and memory formation.

Development of instrumentation to measure rapid calcium transits in neonatal rat ventricular myocytes

1988 ◽  
Vol 46 ◽  
pp. 44-45
Author(s):  
H. K. Hagler ◽  
A. C. Morris ◽  
L. M. Buja
Keyword(s):  
Intracellular Calcium ◽  
Cell Injury ◽  
Ventricular Myocytes ◽  
Calcium Transients ◽  
Neonatal Rat ◽  
Free Calcium ◽  
Total Calcium ◽  
X Ray ◽  
Calcium Indicators ◽  
Electron Microscopes

Changes in the intracellular calcium levels in cardiac myocytes are important in the regulation of normal cardiac function and have been implicated in contributing to irreversible cell injury with ischemia or hypoxia. Intracellular measurement of total calcium changes with subcellular resolution have become routine using rapid cryofixation, cryosectioning, cryotransfer and energy dispersive x-ray microanalysis in analytical electron microscopes. The x-ray microanalysis technique measures total calcium changes within subcellular compartments, but does not distinguish between the bound and free calcium. With the successful development of fluorescent calcium indicators which may be introduced into cells without significantly buffering the intracellular calcium levels, it has become possible to measure rapid calcium transients during contraction. The primary requirements in the development of a system to utilize the fluorescent calcium indicators were to resolve calcium transients in individual cells (since the response to perturbations such as hypoxia is heterogeneous) and develop a system which would be flexible enough to accommodate new indicators as they become available.

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