scholarly journals Cerebral Vascular Volume after Repeated Ischemic Insults in the Gerbil: Comparison with Changes in CBF and Brain Edema

1989 ◽  
Vol 9 (2) ◽  
pp. 163-170 ◽  
Author(s):  
Ryszard Pluta ◽  
Shuichi Tomida ◽  
Junichi Ikeda ◽  
Thaddeus S. Nowak ◽  
Igor Klatzo
Keyword(s):  
Blood Volume ◽  
Time Course ◽  
Brain Regions ◽  
Similar Time ◽  
Total Blood ◽  
Ischemic Brain ◽  
Vascular Volume ◽  
Postischemic Recirculation ◽  
The Status ◽  
Distribution Spaces

The time course of changes in cerebral intravascular volume was evaluated during 24 h following a series of three 5-min carotid artery occlusions spaced at 1-h intervals and compared with the changes occurring after single 5- or 15-min occlusions. Quantitative estimates of cerebral red cell volume, plasma volume, and total blood volume were obtained from the distribution spaces of 51Cr-labeled erythrocytes and 125I-albumin infused prior to killing at varied recirculation intervals. Significant reductions in vascular volume occurred in all ischemic brain regions within 1 h following a single 5-min occlusion, which recovered to control values within 6 h. A similar time course was seen after repeated occlusions. The reductions in volume remained significant at 6 h after a single 15-min occlusion, but there was no difference from control by 24 h. Thus, the time course of total vascular volume correlates well with that of CBF changes previously described, and both blood flow and blood volume are at normal levels during the time of severe edema 24 h after repeated occlusions. Calculated cerebral hematocrit was 60–70% of that obtained from the femoral artery, but was identical in all brain regions and was constant throughout the postischemic recirculation period, with the exception of a transient reduction in both peripheral and cerebral hematocrit observed at 6-h recirculation following single 15-min occlusions. These results suggest that changes in CBF and blood volume reflect primarily the status of larger vessels and that values in the normal range may be observed even under conditions of severe edema and impaired perfusion at the capillary level.

Loss of cerebral regulation during cardiac output variations in focal cerebral ischemia

1992 ◽  
Vol 77 (2) ◽  
pp. 253-259 ◽  
Author(s):  
Bruce I. Tranmer ◽  
Ted S. Keller ◽  
Glenn W. Kindt ◽  
David Archer
Keyword(s):  
Cardiac Output ◽  
Cerebral Ischemia ◽  
Blood Volume ◽  
Volume Expansion ◽  
Focal Cerebral Ischemia ◽  
Brain Regions ◽  
Ischemic Brain ◽  
Content Type ◽  
Blood Volume Expansion ◽  
Fine Print

✓ Focal cerebral ischemia was induced in anesthetized macaque monkeys by unilateral middle cerebral artery occlusion. The effect of blood volume expansion by a colloid agent and subsequent exsanguination to baseline cardiac output (CO) on local cerebral blood flow (CBF) was measured by the hydrogen clearance technique in both ischemic and nonischemic brain regions. Cardiac output was increased to maximum levels (159% ± 92%, mean ± standard error of the mean) by blood volume expansion with the colloid agent hetastarch, and was then reduced a similar amount (166% ± 82%) by exsanguination during the ischemic period. Local CBF in ischemic brain regions varied directly with CO, with a correlation coefficient of 0.89 (% change CBF/% change CO), while CBF in nonischemic brain was not affected by upward or downward manipulations of CO. The difference in these responses between ischemic and nonischemic brain was highly significant (p < 0.001). The results of this study show a profound loss of regulatory control in ischemic brain in response to alterations in CO, thereby suggesting that blood volume variations may cause significant changes in the intensity of ischemia. It is proposed that CO monitoring and manipulation may be vital for optimum care of patients with acute cerebral ischemia.

scholarly journals Time course of reversibility of accelerated fibrinogen disappearance in diabetes mellitus: association with intravascular volume shifts

Blood ◽  
1984 ◽  
Vol 63 (1) ◽  
pp. 22-30
Author(s):  
RL Jones ◽  
L Jovanovic ◽  
S Forman ◽  
CM Peterson
Keyword(s):  
Blood Glucose ◽  
Blood Volume ◽  
Volume Expansion ◽  
Time Course ◽  
Diabetic Patients ◽  
Vascular Volume ◽  
Blood Volume Expansion ◽  
Artificial Beta Cell ◽  
Acute Changes ◽  
Osmotic Effects

Accelerated fibrinogen disappearance in diabetic patients is reversible with normalization of blood glucose. To define the time course of this reversal, we measured 125I-fibrinogen disappearance in 19 diabetic patients experiencing acute changes in blood glucose, as monitored and controlled by a microprocessor-controlled closed loop insulin infusion system (artificial beta cell). The data were corrected for blood volume dilutional changes and fit to a model describing two sequential exponential functions and a single exponential function. The sequential model provided the best fit for all but one patient. This indicates that there were two distinct rates of fibrinogen disappearance and suggests that the time course of reversal of accelerated fibrinogen disappearance in diabetic patients is very rapid, if not immediate. Rapid fibrinogen turnover during hyperglycemia was temporally associated with vascular volume changes, reflected as dilutional changes of 51Cr-RBC concentrations. These findings were also associated with an increase in pulse pressure during hyperglycemia, suggesting blood volume expansion due to an osmotic mechanism. The results of this study suggest a picture of vascular volume expansion and contraction, perhaps secondary to the osmotic effects of hyperglycemia. Accelerated fibrinogen turnover associated with these events may be related to increased vascular permeability and/or increased fibrin formation. These events, in concert, may contribute to the initiation and/or propagation of diabetic vascular sequelae.

scholarly journals Changes in neural activity around the time of saccades: Separate contributions of visual and non-visual signals on MEG alpha and theta band activity

2021 ◽  
Author(s):  
David Acunzo ◽  
David Melcher
Keyword(s):  
Neural Activity ◽  
Visual Processing ◽  
Time Course ◽  
Brain Regions ◽  
Visual Input ◽  
Visual Signals ◽  
Perceptual Task ◽  
Alpha Power ◽  
Similar Time ◽  
Retinal Stimulation

Visual processing mainly occurs during fixation, periods separated by saccadic eye movements, necessitating a close coordination between sensory and motor systems. It has been suggested that the intention to make a saccade can modulate neural activity, including predictive changes, suppression of peri-saccadic retinal input and trans-saccadic integration. Consistent with this idea, modulations of neural activity around the time of saccades have been reported in non-human species, showing non-visually mediated, extraretinal responses in specific brain regions. In humans, however, peri-saccadic whole-brain activity has mainly been studied in the context of a perceptual task, making it difficult to disentangle activity related to the task, visual transients from retinal stimulation and non-visual (saccade-related) responses. We measured magnetoencephalography (MEG) theta (3–7 Hz) and alpha (8–12 Hz) activity during voluntary horizontal saccade execution between two fixation points. To distinguish between visually and non-visually mediated activity, participants engaged in three tasks: voluntary saccades in near-darkness, fixation with visual input shifted to simulate the saccade, and volitional saccades in total darkness. Using correlational analyses, we found that patterns of neural activity are consistent with contributions of two separate mechanisms, one related to saccades (non-visual/extraretinal) and the other linked to the processing of visual input at the beginning of the new fixation (visual/retinal). Changes in occipital alpha power and instantaneous frequency showed a similar time course in near-dark and simulated saccade conditions, suggesting an effect of visually evoked responses. In contrast, alterations in parietal-occipital theta power and phase clustering were consistent with a non-visually-driven (extraretinal) mechanism, with similar multivariate patterns for near-dark and full-darkness conditions. Some effects, such as theta phase reset and alterations in alpha power, showed separable contributions of both the saccade and visual transient, with differing time courses. This combination of visual and non-visual mechanisms may support sensorimotor integration during active vision.

scholarly journals Time course of reversibility of accelerated fibrinogen disappearance in diabetes mellitus: association with intravascular volume shifts

Blood ◽  
1984 ◽  
Vol 63 (1) ◽  
pp. 22-30 ◽  
Author(s):  
RL Jones ◽  
L Jovanovic ◽  
S Forman ◽  
CM Peterson
Keyword(s):  
Blood Glucose ◽  
Blood Volume ◽  
Volume Expansion ◽  
Time Course ◽  
Diabetic Patients ◽  
Vascular Volume ◽  
Blood Volume Expansion ◽  
Artificial Beta Cell ◽  
Acute Changes ◽  
Osmotic Effects

Abstract Accelerated fibrinogen disappearance in diabetic patients is reversible with normalization of blood glucose. To define the time course of this reversal, we measured 125I-fibrinogen disappearance in 19 diabetic patients experiencing acute changes in blood glucose, as monitored and controlled by a microprocessor-controlled closed loop insulin infusion system (artificial beta cell). The data were corrected for blood volume dilutional changes and fit to a model describing two sequential exponential functions and a single exponential function. The sequential model provided the best fit for all but one patient. This indicates that there were two distinct rates of fibrinogen disappearance and suggests that the time course of reversal of accelerated fibrinogen disappearance in diabetic patients is very rapid, if not immediate. Rapid fibrinogen turnover during hyperglycemia was temporally associated with vascular volume changes, reflected as dilutional changes of 51Cr-RBC concentrations. These findings were also associated with an increase in pulse pressure during hyperglycemia, suggesting blood volume expansion due to an osmotic mechanism. The results of this study suggest a picture of vascular volume expansion and contraction, perhaps secondary to the osmotic effects of hyperglycemia. Accelerated fibrinogen turnover associated with these events may be related to increased vascular permeability and/or increased fibrin formation. These events, in concert, may contribute to the initiation and/or propagation of diabetic vascular sequelae.

Observations on Cardiac Output and ”Pulmonary Blood Volume” in Normal Man by External Recording of the Intracardiac Flow of 131I Labelled Albumin

1961 ◽  
Vol 1 (04) ◽  
pp. 353-379
Author(s):  
Jacques Lammerant ◽  
Norman Veall ◽  
Michel De Visscher
Keyword(s):  
Cardiac Output ◽  
Blood Volume ◽  
Normal Subjects ◽  
Published Data ◽  
Total Blood Volume ◽  
Total Blood ◽  
Pulmonary Blood Volume ◽  
Intracardiac Flow ◽  
Normal Man ◽  
Mean Circulation

Summary1. The technique for the measurement of cardiac output by external recording of the intracardiac flow of 131I labelled human serum albumin has been extended to provide a measure of the mean circulation time from right to left heart and hence a new approach to the estimation of the pulmonary blood volume.2. Values for the basal cardiac output in normal subjects and its variations with age are in good agreement with the previously published data of other workers.3. The pulmonary blood volume in normal man in the basal state was found to be 28.2 ± 0.6% of the total blood volume.4. There was no correlation between cardiac output and pulmonary blood volume in a series of normal subjects in the basal state.5. The increase in cardiac output during digestion was associated with a decrease in pulmonary blood volume equal to 6.3 ± 1.2% of the total blood volume, that is, about 280 ml.6. The increase in cardiac output during exercise was associated with a decrease in pulmonary blood volume equal to 4.5 ± 1.0% of the total blood volume, that is, about 200 ml.7. The increase in cardiac output attributed to alarm is not associated with a decrease in pulmonary blood volume, the latter may in fact be increased.8. The total blood volume is advocated as a standard of reference for studies of this type in normal subjects in preference to body weight or surface area.9. The significance of these results and the validity of the method are discussed.

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.

Engaging regularly with fiction influences connectivity in cortical areas for language and mentalizing

2017 ◽  
Author(s):  
Roel M. Willems ◽  
Franziska Hartung
Keyword(s):  
Functional Connectivity ◽  
Time Course ◽  
Language Skills ◽  
Brain Regions ◽  
Brain Areas ◽  
Daily Lives ◽  
Cortical Areas ◽  
Social Abilities ◽  
Behavioral Evidence ◽  
Amount Of Reading

Behavioral evidence suggests that engaging with fiction is positively correlated with social abilities. The rationale behind this link is that engaging with fictional narratives offers a ‘training modus’ for mentalizing and empathizing. We investigated the influence of the amount of reading that participants report doing in their daily lives, on connections between brain areas while they listened to literary narratives. Participants (N=57) listened to two literary narratives while brain activation was measured with fMRI. We computed time-course correlations between brain regions, and compared the correlation values from listening to narratives to listening to reversed speech. The between-region correlations were then related to the amount of fiction that participants read in their daily lives. Our results show that amount of fiction reading is related to functional connectivity in areas known to be involved in language and mentalizing. This suggests that reading fiction influences social cognition as well as language skills.

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.

scholarly journals On the Role of Bilateral Brain Hypofunction and Abnormal Lateralization of Cortical Information Flow as Neural Underpinnings of Conventional Metaphor Processing Impairment in Schizophrenia: An fMRI and EEG Study

2021 ◽  
Author(s):  
Przemysław Adamczyk ◽  
Martin Jáni ◽  
Tomasz S. Ligeza ◽  
Olga Płonka ◽  
Piotr Błądziński ◽  
...  
Keyword(s):  
Information Flow ◽  
Language Processing ◽  
Time Course ◽  
Figurative Language ◽  
Neural Circuits ◽  
Effective Connectivity ◽  
Brain Regions ◽  
Blood Oxygenation ◽  
Control Group ◽  
Metaphor Processing

AbstractFigurative language processing (e.g. metaphors) is commonly impaired in schizophrenia. In the present study, we investigated the neural activity and propagation of information within neural circuits related to the figurative speech, as a neural substrate of impaired conventional metaphor processing in schizophrenia. The study included 30 schizophrenia outpatients and 30 healthy controls, all of whom were assessed with a functional Magnetic Resonance Imaging (fMRI) and electroencephalography (EEG) punchline-based metaphor comprehension task including literal (neutral), figurative (metaphorical) and nonsense (absurd) endings. The blood oxygenation level-dependent signal was recorded with 3T MRI scanner and direction and strength of cortical information flow in the time course of task processing was estimated with a 64-channel EEG input for directed transfer function. The presented results revealed that the behavioral manifestation of impaired figurative language in schizophrenia is related to the hypofunction in the bilateral fronto-temporo-parietal brain regions (fMRI) and various differences in effective connectivity in the fronto-temporo-parietal circuit (EEG). Schizophrenia outpatients showed an abnormal pattern of connectivity during metaphor processing which was related to bilateral (but more pronounced at the left hemisphere) hypoactivation of the brain. Moreover, we found reversed lateralization patterns, i.e. a rightward-shifted pattern during metaphor processing in schizophrenia compared to the control group. In conclusion, the presented findings revealed that the impairment of the conventional metaphor processing in schizophrenia is related to the bilateral brain hypofunction, which supports the evidence on reversed lateralization of the language neural network and the existence of compensatory recruitment of alternative neural circuits in schizophrenia.

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.

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