scholarly journals Neurofilament Proteolysis after Focal Ischemia; When Do Cells Die after Experimental Stroke?

1999 ◽  
Vol 19 (6) ◽  
pp. 652-660 ◽  
Author(s):  
Jaroslaw Aronowski ◽  
Ki-Hyun Cho ◽  
Roger Strong ◽  
James C. Grotta
Keyword(s):  
Time Course ◽  
Infarct Volume ◽  
Focal Ischemia ◽  
Cellular Damage ◽  
Experimental Stroke ◽  
Infarct Core ◽  
Similar Time ◽  
The Core ◽  
Tetrazolium Staining ◽  
Previous Demonstration

To determine the occurrence and time-course of presumably irreversible subcellular damage after moderate focal ischemia, rats were subjected to 1, 3, 6, 9, or 24 hours of permanent unilateral middle cerebral and common carotid occlusion or 3 hours of reversible occlusion followed by 3, 6, or 21 hours of reperfusion. The topography and the extent of damage were analyzed with tetrazolium staining and immunoblot using an antibody capable of detecting breakdown of neurofilament. Neurofilament proteolysis began after 3 hours in the infarct core but was still incomplete in penumbral regions up to 9 hours. Similarly, tetrazolium-staining abnormalities were observed in the core of 50% of animals after 3 hours of ischemia. At 6 hours of permanent ischemia, infarct volume was maximal, and further prolongation of occlusion to 9 or 24 hours did not increase abnormal tetrazolium staining. In contrast to permanent ischemia and in agreement with the authors' previous demonstration of “reperfusion injury” in this model, prolongation of reperfusion from 3 hours to 6 and 21 hours after 3 hours of reversible occlusion gradually augmented infarct volume by 203% and 324%, respectively. Neurofilament proteolysis initiated approximately 3 hours after ischemia was quantitatively greatest in the core and extended during reperfusion to incorporate penumbra with a similar time course to that of tetrazolium abnormalities. These data demonstrate that, at least as measured by neurofilament breakdown and mitochondrial failure, extensive cellular damage is not present in penumbral regions for up to 9 hours, suggesting the potential for rescuing these regions by appropriate and timely neuroprotective strategies.

Abstract P534: Relationship Between rCBF and Pial Collateral Recruitment in Experimental Acute Ischemic Stroke

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Niloufar Saadat ◽  
Greg Christoforidis ◽  
Marek Niekrasz ◽  
Steven Roth ◽  
Timothy Carroll
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Infarct Volume ◽  
Mean Diffusivity ◽  
Cerebrovascular Reactivity ◽  
Poor Correlation ◽  
P Value ◽  
Infarct Core ◽  
The Core ◽  
Normal Ranges

Purpose: The purpose of this study was to assess the relationship between relative cerebral blood flow (rCBF) by MRI and leptomeningeal collateral recruitment in an experimental acute ischemic stroke model. Methods: This study was approved by the local IACUC. Eight mongrel canines (20-30kg) underwent endovascular middle cerebral artery occlusion (MCAO). Anesthetics were chosen not to interfere with cerebrovascular reactivity. Physiologic parameters were maintained within normal ranges. Pial collateral recruitment was angiographically assessed using a previously published 11-point scale. After the MCAO, subjects underwent DSC and DTI MRI (3T Achieva, Philips Healthcare, Best, Netherlands) in order to derive rCBF and infarct volume by diffusion restriction on mean diffusivity maps. DSC images were imported into Visage software (Visage Imaging; Richmond Australia). The region of interest was drawn on the penumbra and infarct core and corresponding contralateral side. Infarct volume was calculated by using a quantitative voxel-wise threshold by setting a threshold of 1.5 SD relative to normal values based on an ROI drawn to cover the entire contralateral normal hemisphere exclusive of the ventricles. Results: The pial collateral recruitment was strongly correlated with the rCBF on the penumbral region (r 2 = 0.7823, P-value= 0.003), and with the infarct volume measured two hours following occlusion (r 2 = 0.933376, P value= 0.00009.). There was a poor correlation between the pial collateral recruitment and the rCBF ratio on the core region (R 2 =0.4447, p-value= 0.07.) Conclusion: Preliminary data from this study suggests rCBF from the penumbral regions in experimental MCAO has a closer association with pial collateral recruitment relative to rCBF in the core infarct zone. This information has the potential to affect the interpretation of angiographic studies in acute ischemic stroke and underscores the importance of assessing regional differences in rCBF.

Abstract WP150: Superior Neuroprotective Efficacy of Elovanoids, a Novel Class of Homeostatic Lipid Mediators, in Experimental Stroke

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Nicolas G Bazan ◽  
Andre Obenaus ◽  
Pranab Mukherjee ◽  
Bokkyoo Jun ◽  
Larissa Khoutorova ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Infarct Volume ◽  
Methyl Esters ◽  
Lipid Mediators ◽  
Cellular Damage ◽  
Experimental Stroke ◽  
Omega 3 ◽  
Sprague Dawley ◽  
Signaling Mechanism ◽  
Ischemic Core

Objectives: Ischemic stroke triggers a pattern of cellular and molecular disturbances that include lipid peroxidation, uncompensated oxidative stress, and neuronal injury. Recently, we have uncovered and characterized a novel neuroprotective signaling mechanism, which involves the activation of the biosynthesis of a family of lipid mediators in the brain made from omega-3 very-long-chain polyunsaturated fatty acids, that we named Elovanoids (ELVs). The present study evaluated ELVs, made of 32 and 34 C atoms in length (ELV-N32 and ELV-N34) and their potential mechanisms of action in cerebral ischemia. Methods: Male Sprague-Dawley rats were subjected to 2 h of middle cerebral artery occlusion (MCAo). Sodium salts (Na) or methyl esters (Me) ELVs were dissolved in artificial CSF and administered into right lateral ventricle at 3 h after onset of stroke. There were five groups: ELV-N32-Na, ELV-N32-Me, ELV-N34-Na, ELV-N34-Me (5μg/50μl), and CSF (50μl). Neurological function was evaluated on days 1, 3, and 7 after MCAo. Ex vivo MRI and immunohistochemistry were conducted on day 7. Results: All ELV treatments greatly improved neurologic scores in a sustained fashion up to the 7-day survival period. Ischemic core and penumbra volumes (computed from T2WI) were significantly reduced by all ELV treatments, and total lesion volumes were significantly reduced by ELV-N32-Na, ELV-N32-Me, ELV-N34-Na, and ELV-N34-Me compared to CSF-treated group (by 60%, 56%, 99%, and 91%, respectively). ELV-treated rats showed less infarction with an increased number of NeuN- and GFAP-positive cells as well as SMI-71-positive vessels in the cortex and less IgG staining in the cortex. ELV-mediated protection was extensive in the frontal-parietal cortex (tissue was salvaged by 57-96%), subcortex (73-75%), and total infarct volume, correction for brain swelling was dramatically reduced in all ELV-treated groups by 55-91%. Conclusion: We have shown that the administration of ELVs provides high-grade neurobehavioral recovery, decreases ischemic core and penumbra volumes, as well as attenuates cellular damage, blood vessel integrity, and BBB disruption.

Abstract WMP74: Cofilin-Actin Rod Formation in Experimental Stroke is Attenuated by Therapeutic Hypothermia and Overexpression of the Inducible 70-kDa Heat Shock Protein (Hsp70)

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Kota Kurisu ◽  
Je Sung You ◽  
Seok Joon Won ◽  
Zhen Zheng ◽  
Raymond A. Swanson ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Therapeutic Hypothermia ◽  
Infarct Volume ◽  
Neuroprotective Effect ◽  
Experimental Stroke ◽  
Infarct Core ◽  
Ischemic Lesion ◽  
Neurological Outcomes ◽  
Heat Shock Protein Hsp70

Background and Purpose: Cofilin-actin rods are covalently linked aggregates of cofilin -1 and actin. Under ischemic conditions, these rods have been observed in neuronal processes, but their significance is unknown. Here, we explored a potential role of these rods in two different models of neuroprotection from experimental stroke—therapeutic hypothermia and the 70-kDa heat shock protein (Hsp70). Methods: Male C57/BL6 mice were subjected to distal middle cerebral artery occlusion (dMCAO), and treated with hypothermia. Cooling (31°C, 2hrs) was begun at the onset of dMCAO. A neuroprotective effect of hypothermia was validated by functional assessments and infarct volume measurement. Cofilin-actin rod formation was assessed by histological analysis at 4 and 24hrs after dMCAO. Its expression was analyzed in three different regions, infarct core (the center of the infarct), penumbra (area salvaged by intervention and a fixed distance from the midline), and ischemic borderzone (border of ischemic lesion). In addition, Hsp70-overexpressing transgenic (Tg) mice and Hsp70-deficient (Ko) mice were also subjected to dMCAO, and cofilin-actin rod expression was assessed in same manner. Results: As shown previously by our lab, both hypothermia and Hsp70 Tg mice had smaller lesion sizes and improved neurological outcomes compared to normothermic and wildtype (Wt) mice. Hsp70 Ko mice had larger lesion sizes and worsened neurological outcomes. Following dMCAO, cofilin-actin rods were increased, but were reduced by hypothermia in the ischemic core (24hrs, p<0.05), penumbra (4 and 24hrs, p<0.05), and ischemic borderzone (4 and 24hrs, p<0.05). Among Hsp70 Tg mice, cofilin-actin rod formation was decreased in the ischemic borderzone (4 and 24hrs, p<0.05), while Hsp70 Ko mice showed increased rod formation in the penumbra (4 and 24hrs, p<0.05). Conclusions: Cofilin-actin rod formation was suppressed under conditions of improved neurological outcome, and increased under circumstances where outcome was worsened. This suggests that cofilin-actin rods may act to participate in or exacerbate ischemic pathology, and warrants further study as a potential therapeutic target.

Postnatal growth rate and gonadal development in circadian tau mutant hamsters reared in constant dim red light

Reproduction ◽  
2000 ◽  
pp. 327-330 ◽  
Author(s):  
RJ Lucas ◽  
JA Stirland ◽  
YN Mohammad ◽  
AS Loudon
Keyword(s):  
Time Course ◽  
Red Light ◽  
Somatic Growth ◽  
Postnatal Growth ◽  
Gonadal Development ◽  
Testicular Development ◽  
Wild Type ◽  
Similar Time ◽  
Syrian Hamsters ◽  
Body Weights

The role of the circadian clock in the reproductive development of Syrian hamsters (Mesocricetus auratus was examined in wild type and circadian tau mutant hamsters reared from birth to 26 weeks of age under constant dim red light. Testis diameter and body weights were determined at weekly intervals in male hamsters from 4 weeks of age. In both genotypes, testicular development, subsequent regression and recrudescence exhibited a similar time course. The age at which animals displayed reproductive photosensitivity, as exhibited by testicular regression, was unrelated to circadian genotype (mean +/- SEM: 54 +/- 3 days for wild type and 59 +/- 5 days for tau mutants). In contrast, our studies revealed a significant impact of the mutation on somatic growth, such that tau mutants weighed 18% less than wild types at the end of the experiment. Our study reveals that the juvenile onset of reproductive photoperiodism in Syrian hamsters is not timed by the circadian system.

scholarly journals TGF-β1 increases permeability of ciliated airway epithelia via redistribution of claudin 3 from tight junction into cell nuclei

2021 ◽  
Author(s):  
Carolin Schilpp ◽  
Robin Lochbaum ◽  
Peter Braubach ◽  
Danny Jonigk ◽  
Manfred Frick ◽  
...  
Keyword(s):  
Time Course ◽  
Atopic Asthma ◽  
Ciliated Cells ◽  
Cell Nuclei ◽  
Tissue Remodelling ◽  
Similar Time ◽  
Airway Epithelia ◽  
Epithelial Integrity ◽  
Motile Cilia ◽  
Tgf Β1

AbstractTGF-β1 is a major mediator of airway tissue remodelling during atopic asthma and affects tight junctions (TJs) of airway epithelia. However, its impact on TJs of ciliated epithelia is sparsely investigated. Herein we elaborated effects of TGF-β1 on TJs of primary human bronchial epithelial cells. We demonstrate that TGF-β1 activates TGF-β1 receptors TGFBR1 and TGFBR2 resulting in ALK5-mediated phosphorylation of SMAD2. We observed that TGFBR1 and -R2 localize specifically on motile cilia. TGF-β1 activated accumulation of phosphorylated SMAD2 (pSMAD2-C) at centrioles of motile cilia and at cell nuclei. This triggered an increase in paracellular permeability via cellular redistribution of claudin 3 (CLDN3) from TJs into cell nuclei followed by disruption of epithelial integrity and formation of epithelial lesions. Only ciliated cells express TGF-β1 receptors; however, nuclear accumulations of pSMAD2-C and CLDN3 redistribution were observed with similar time course in ciliated and non-ciliated cells. In summary, we demonstrate a role of motile cilia in TGF-β1 sensing and showed that TGF-β1 disturbs TJ permeability of conductive airway epithelia by redistributing CLDN3 from TJs into cell nuclei. We conclude that the observed effects contribute to loss of epithelial integrity during atopic asthma.

scholarly journals Pseudo-streaming potentials in Necturus gallbladder epithelium. II. The mechanism is a junctional diffusion potential.

1992 ◽  
Vol 99 (3) ◽  
pp. 317-338 ◽  
Author(s):  
L Reuss ◽  
B Simon ◽  
C U Cotton
Keyword(s):  
Time Course ◽  
Bathing Solution ◽  
Intercellular Spaces ◽  
Similar Time ◽  
Streaming Potentials ◽  
Osmotic Water ◽  
Lateral Intercellular Spaces ◽  
Transepithelial Voltage ◽  
Time Courses ◽  
Good Agreement

The mechanisms of apparent streaming potentials elicited across Necturus gallbladder epithelium by addition or removal of sucrose from the apical bathing solution were studied by assessing the time courses of: (a) the change in transepithelial voltage (Vms). (b) the change in osmolality at the cell surface (estimated with a tetrabutylammonium [TBA+]-selective microelectrode, using TBA+ as a tracer for sucrose), and (c) the change in cell impermeant solute concentration ([TMA+]i, measured with an intracellular double-barrel TMA(+)-selective microelectrode after loading the cells with TMA+ by transient permeabilization with nystatin). For both sucrose addition and removal, the time courses of Vms were the same as the time courses of the voltage signals produced by [TMA+]i, while the time courses of the voltage signals produced by [TBA+]o were much faster. These results suggest that the apparent streaming potentials are caused by changes of [NaCl] in the lateral intercellular spaces, whose time course reflects the changes in cell water volume (and osmolality) elicited by the alterations in apical solution osmolality. Changes in cell osmolality are slow relative to those of the apical solution osmolality, whereas lateral space osmolality follows cell osmolality rapidly, due to the large surface area of lateral membranes and the small volume of the spaces. Analysis of a simple mathematical model of the epithelium yields an apical membrane Lp in good agreement with previous measurements and suggests that elevations of the apical solution osmolality elicit rapid reductions in junctional ionic selectivity, also in good agreement with experimental determinations. Elevations in apical solution [NaCl] cause biphasic transepithelial voltage changes: a rapid negative Vms change of similar time course to that of a Na+/TBA+ bi-ionic potential and a slow positive Vms change of similar time course to that of the sucrose-induced apparent streaming potential. We conclude that the Vms changes elicited by addition of impermeant solute to the apical bathing solution are pseudo-streaming potentials, i.e., junctional diffusion potentials caused by salt concentration changes in the lateral intercellular spaces secondary to osmotic water flow from the cells to the apical bathing solution and from the lateral intercellular spaces to the cells. Our results do not support the notion of junctional solute-solvent coupling during transepithelial osmotic water flow.

scholarly journals Correlation between Charge Movement and Ionic Current during Slow Inactivation in Shaker K+ Channels

1997 ◽  
Vol 110 (5) ◽  
pp. 579-589 ◽  
Author(s):  
Riccardo Olcese ◽  
Ramón Latorre ◽  
Ligia Toro ◽  
Francisco Bezanilla ◽  
Enrico Stefani
Keyword(s):  
Time Course ◽  
Voltage Dependence ◽  
Ionic Current ◽  
K Channel ◽  
Charge Movement ◽  
Slow Inactivation ◽  
Gating Currents ◽  
Similar Time ◽  
K Channels ◽  
Recovery From Inactivation

Prolonged depolarization induces a slow inactivation process in some K+ channels. We have studied ionic and gating currents during long depolarizations in the mutant Shaker H4-Δ(6–46) K+ channel and in the nonconducting mutant (Shaker H4-Δ(6–46)-W434F). These channels lack the amino terminus that confers the fast (N-type) inactivation (Hoshi, T., W.N. Zagotta, and R.W. Aldrich. 1991. Neuron. 7:547–556). Channels were expressed in oocytes and currents were measured with the cut-open-oocyte and patch-clamp techniques. In both clones, the curves describing the voltage dependence of the charge movement were shifted toward more negative potentials when the holding potential was maintained at depolarized potentials. The evidences that this new voltage dependence of the charge movement in the depolarized condition is associated with the process of slow inactivation are the following: (a) the installation of both the slow inactivation of the ionic current and the inactivation of the charge in response to a sustained 1-min depolarization to 0 mV followed the same time course; and (b) the recovery from inactivation of both ionic and gating currents (induced by repolarizations to −90 mV after a 1-min inactivating pulse at 0 mV) also followed a similar time course. Although prolonged depolarizations induce inactivation of the majority of the channels, a small fraction remains non–slow inactivated. The voltage dependence of this fraction of channels remained unaltered, suggesting that their activation pathway was unmodified by prolonged depolarization. The data could be fitted to a sequential model for Shaker K+ channels (Bezanilla, F., E. Perozo, and E. Stefani. 1994. Biophys. J. 66:1011–1021), with the addition of a series of parallel nonconducting (inactivated) states that become populated during prolonged depolarization. The data suggest that prolonged depolarization modifies the conformation of the voltage sensor and that this change can be associated with the process of slow inactivation.

scholarly journals Calcium metabolism in rat hepatocytes

1978 ◽  
Vol 170 (3) ◽  
pp. 615-625 ◽  
Author(s):  
S Foden ◽  
P J Randle
Keyword(s):  
Cyclic Amp ◽  
Time Course ◽  
Rat Hepatocytes ◽  
Ionophore A23187 ◽  
Total Calcium ◽  
Free Medium ◽  
Adrenergic Agonists ◽  
Calcium Efflux ◽  
Similar Time ◽  
Carbonyl Cyanide

1. The total calcium concentration in rat hepatocytes was 7.9 microgram-atoms/g dry wt.; 77% of this was mitochondrial. Approx. 20% of cell calcium exchanged with 45Ca within 2 min. Thereafter incorporation proceeded at a low rate to reach 28% of total calcium after 60 min. Incorporation into mitochondria showed a similar time course and accounted for 20% of mitochondrial total calcium after 60 min. 2. The alpha-adrenergic agonists phenylephrine and adrenaline + propranolol stimulated incorporation of 45Ca into hepatocytes. Phenylephrine was shown to increase total calcium in hepatocytes. Phenylephrine inhibited efflux fo 45Ca from hepatocytes perifused with calcium-free medium. 3. Glucagon, dibutryl cyclic AMP and beta-adrenergic agonists adrenaline and 3-isobutyl-1-methyl-xanthine stimulated calcium efflux from hepatocytes perifused with calcium-free medium. The effect of glucagon was blocked by insulin. Insulin itself had no effect on calcium efflux and it did not affect the response to dibutyryl cyclic AMP. 4. Incorporation of 45Ca into mitochondria in hepatocytes was stimulated by phenylephrine and inhibited by glucagon and by carbonyl cyanide p-trifluoromethoxyphenylhydrazone. The effect of glucagon was blocked by insulin. 5. Ionophore A23187 stimulated hepatocyte uptake of 45Ca, uptake of 45Ca into mitochondria in hepatocytes and efflux of 45Ca into a calcium-free medium.

Ontogeny of the insulin response to glucose in fetal and adult sheep

1989 ◽  
Vol 67 (10) ◽  
pp. 1288-1293 ◽  
Author(s):  
Pamela E. Houghton ◽  
Thomas J. McDonald ◽  
John R. G. Challis
Keyword(s):  
Time Course ◽  
Bolus Injection ◽  
Peak Plasma ◽  
Femoral Vein ◽  
Insulin Response ◽  
Similar Time ◽  
Fetal Sheep ◽  
Adult Sheep ◽  
Glucose Ratio ◽  
Insulin Response To Glucose

The purpose of the present experiments was to examine in sheep whether the fetal insulin response to glucose was present by day 110 (d110) of pregnancy and whether the magnitude of the fetal insulin response changed between d110 and d145 (term). We also compared the responses observed in fetuses to those of adult nonpregnant sheep. Basal concentrations of glucose measured in plasma collected from the fetal femoral artery rose progressively between d110 and d145 of gestation, but did not attain the plasma glucose concentrations measured in adult sheep. Peak glucose concentrations in fetuses were achieved 10 min following the bolus injection of glucose (0.8 g/kg estimated fetal body weight) into the fetal femoral vein, and peak values increased with gestational age. Significantly higher peak glucose concentrations were achieved in adult sheep. The concentration of insulin rose rapidly in fetuses at d110, and a similar time course of insulin release in plasma was seen at all gestational ages. The peak plasma insulin concentrations were achieved at 20 min and were significantly greater in older (d140–145) than younger (d125–130) fetuses (p < 0.05). Peak insulin values in fetuses were much less than in adult sheep. In adult sheep glucose and insulin concentrations remained elevated at 120 min following the injection of glucose, whereas in the fetus the concentration of insulin had returned to preinjection values by 60 min. The insulin/glucose ratio did not change in fetal lambs over the last one third of gestation and was not different from the adult sheep. We conclude that (1) the fetal insulin response to an acute glucose load is present by d110 of gestation, and (2) the ratio of insulin released per unit glucose elevation did not change in fetal sheep over the last one third of gestation, nor between fetal and adult sheep.Key words: glucose, insulin, fetal sheep.

scholarly journals Protective Role for Type 4 Metabotropic Glutamate Receptors against Ischemic Brain Damage

2010 ◽  
Vol 31 (4) ◽  
pp. 1107-1118 ◽  
Author(s):  
Slavianka G Moyanova ◽  
Federica Mastroiacovo ◽  
Lidia V Kortenska ◽  
Rumiana G Mitreva ◽  
Erminia Fardone ◽  
...  
Keyword(s):  
Brain Damage ◽  
Metabotropic Glutamate Receptors ◽  
Infarct Volume ◽  
Focal Ischemia ◽  
Protective Role ◽  
Ischemic Brain Damage ◽  
Systemic Injection ◽  
Ischemic Brain ◽  
Metabotropic Glutamate ◽  
Transient Focal Ischemia

We examined the influence of type 4 metabotropic glutamate (mGlu4) receptors on ischemic brain damage using the permanent middle cerebral artery occlusion (MCAO) model in mice and the endothelin-1 (Et-1) model of transient focal ischemia in rats. Mice lacking mGlu4 receptors showed a 25% to 30% increase in infarct volume after MCAO as compared with wild-type littermates. In normal mice, systemic injection of the selective mGlu4 receptor enhancer, N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-caboxamide (PHCCC; 10 mg/kg, subcutaneous, administered once 30 minutes before MCAO), reduced the extent of ischemic brain damage by 35% to 45%. The drug was inactive in mGlu4 receptor knockout mice. In the Et-1 model, PHCCC administered only once 20 minutes after ischemia reduced the infarct volume to a larger extent in the caudate/putamen than in the cerebral cortex. Ischemic rats treated with PHCCC showed a faster recovery of neuronal function, as shown by electrocorticographic recording and by a battery of specific tests, which assess sensorimotor deficits. These data indicate that activation of mGlu4 receptors limit the development of brain damage after permanent or transient focal ischemia. These findings are promising because selective mGlu4 receptor enhancers are under clinical development for the treatment of Parkinson's disease and other central nervous system disorders.

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