The Effects of Retesting on the Mechanical Properties of the Brain Tissue

2013 ◽  
Author(s):  
Asghar Rezaei ◽  
Ghodrat Karami ◽  
Fardad Azarmi ◽  
Mehdi Salimi Jazi ◽  
Mariusz Ziejewski
Keyword(s):  
Mechanical Properties ◽  
Brain Tissue ◽  
Relaxation Times ◽  
Stress Relaxation Test ◽  
Preparation Time ◽  
Relaxation Functions ◽  
Before And After ◽  
Short And Long Term ◽  
The Brain

This research is intended to examine the amount of changes that can happen in material characteristics after retesting. Stress relaxation test is conducted on the same samples of the swine brain tissue for several times in small and large deformations. The mechanical properties of the substance are calculated before and after retest and the constants of the tissue, as mechanical characteristics, are determined and compared. Short- and long-term moduli, relaxation times and relaxation functions are of those data that are calculated and compared to understand how much they decay after repeating the experiments. The results show that applying different tests on one sample slightly changes the mechanical properties of the tissue and, as a result, it is partly possible to perform more than one test on the same sample resulting in less sample preparation, time and effort.

The Effects of Retesting on the Mechanical Properties of Brain Tissue

2013 ◽  
Author(s):  
A. Rezaei ◽  
M. Salimi Jazi ◽  
G. Karami ◽  
M. Ziejewski
Keyword(s):  
Mechanical Properties ◽  
Brain Tissue ◽  
Relaxation Times ◽  
Human Brain Tissue ◽  
Relaxation Functions ◽  
Before And After ◽  
Short And Long Term ◽  
Tissue Characteristics ◽  
Testing Protocols

Traumatic brain injury (TBI) is one of the most important problems in biomechanical engineering, and there have been many experiments conducted in order to characterize the mechanical properties of brain tissue. However, obtaining fresh human brain tissue is difficult, if not impossible. Also, the sample preparation and testing protocols must be carried out with great delicacy because brain tissue is very soft and vulnerable to being deformed under a very small amount of load. Most importantly, according to several researchers, each sample must be tested only one time as the tissue may be damaged and its characteristics subsequently changed. This paper is intended to examine the amount of decay that can happen in material characteristics due to retesting. A stress relaxation test is conducted on the same samples of the swine brain tissue multiple times in small and large deformations. The mechanical properties of the substance are calculated before and after retesting, and the constants of the tissue, as mechanical characteristics, are determined and compared. Short- and long-term moduli, relaxation times and relaxation functions are calculated and compared to understand how much they decay after repeating the experiments. The results show that retesting does not significantly change the elastic part of the tissue characteristics, but the viscous behavior shows a relatively sizeable change. The ability to account for the material decay of the samples due to repetition of the experiments results in the need for fewer samples and less preparation time and effort.

scholarly journals Predicting the cumulative medical load of COVID-19 outbreaks after the peak in daily fatalities

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0247272
Author(s):  
Claudius Gros ◽  
Roser Valenti ◽  
Lukas Schneider ◽  
Benedikt Gutsche ◽  
Dimitrije Marković
Keyword(s):  
Phase Space ◽  
Sir Model ◽  
Reaction Model ◽  
Space Representation ◽  
Cumulative Number ◽  
Short Term ◽  
Before And After ◽  
The Status ◽  
Short And Long Term

The distinct ways the COVID-19 pandemic has been unfolding in different countries and regions suggest that local societal and governmental structures play an important role not only for the baseline infection rate, but also for short and long-term reactions to the outbreak. We propose to investigate the question of how societies as a whole, and governments in particular, modulate the dynamics of a novel epidemic using a generalization of the SIR model, the reactive SIR (short-term and long-term reaction) model. We posit that containment measures are equivalent to a feedback between the status of the outbreak and the reproduction factor. Short-term reaction to an outbreak corresponds in this framework to the reaction of governments and individuals to daily cases and fatalities. The reaction to the cumulative number of cases or deaths, and not to daily numbers, is captured in contrast by long-term reaction. We present the exact phase space solution of the controlled SIR model and use it to quantify containment policies for a large number of countries in terms of short and long-term control parameters. We find increased contributions of long-term control for countries and regions in which the outbreak was suppressed substantially together with a strong correlation between the strength of societal and governmental policies and the time needed to contain COVID-19 outbreaks. Furthermore, for numerous countries and regions we identified a predictive relation between the number of fatalities within a fixed period before and after the peak of daily fatality counts, which allows to gauge the cumulative medical load of COVID-19 outbreaks that should be expected after the peak. These results suggest that the proposed model is applicable not only for understanding the outbreak dynamics, but also for predicting future cases and fatalities once the effectiveness of outbreak suppression policies is established with sufficient certainty. Finally, we provide a web app (https://itp.uni-frankfurt.de/covid-19/) with tools for visualising the phase space representation of real-world COVID-19 data and for exporting the preprocessed data for further analysis.

Cannabis and Its Different Strains

2021 ◽  
pp. 1-10
Author(s):  
Anna Muro ◽  
Ramon Cladellas ◽  
Judit Castellà
Keyword(s):  
Control Group ◽  
Temporal Perception ◽  
Self Medication ◽  
Therapeutic Uses ◽  
Before And After ◽  
Cannabis Consumption ◽  
Short And Long Term ◽  
Different Strains ◽  
Main Effects

Abstract. Previous studies show how time perception can be altered by cannabis consumption, but it is not clear yet whether cannabis produces temporal underproductions or overproductions after acute cannabis intoxication. The present study aimed to analyze a sample of 50 regular cannabis users controlling for cannabis strain (sativa, indica, and hybrid) and to compare their scores in a temporal production task before and after consuming cannabis with a control group of 49 nonusers. Results showed that cannabis intake leads to overproductions, suggesting that regular users’ internal tempo slows down after acute intoxication. However, the analyses of main effects showed that indica users, both at baseline levels and after consuming, reported significant underproductions compared to controls, sativa, and hybrid users, and the cannabis-induced effects had a higher magnitude after smoking in the indica-strain group. Results highlight the relevance of including the type of strain consumed in cannabis studies, and they are discussed in terms of short- and long-term alterations in temporal perception under the light of the self-medication theory and the therapeutic uses of cannabis.

The Banco de Avío

2021 ◽  
pp. 442-464
Author(s):  
Eric Van Young
Keyword(s):  
Development Strategy ◽  
Textile Industry ◽  
The State ◽  
Development Bank ◽  
Long Term Effects ◽  
Before And After ◽  
Silver Mining ◽  
Short And Long Term ◽  
Textile Sector

At Alamán’s initiative a law of 1830 established the Banco de Avío, a government-funded development bank for the spurring of industrialization, especially in the textile sector, with which his name has forever been associated. His views of industrialization as a development strategy as opposed to a renewed reliance upon silver mining are discussed, as well as the short- and long-term effects of loans made to textile entrepreneurs and the cronyism employed by Alamán both in organizing the Banco itself and in allotting its capital as loans to industrialists. The state of the textile industry in Mexico before and after the Banco is described.

scholarly journals Ellenőrző lista hatása a légútbiztosítás korai szövődményeire felnőttekben

2019 ◽  
Vol 160 (26) ◽  
pp. 1025-1035 ◽  
Author(s):  
Zoltán Pál Szűcs ◽  
János Farkas ◽  
Péter Schimert ◽  
Zsolt Baranyai ◽  
Elek Dinya
Keyword(s):  
Airway Management ◽  
Primary Endpoint ◽  
Soft Tissues ◽  
Controlled Study ◽  
Data Collection Sheet ◽  
Before And After ◽  
Secondary Endpoints ◽  
Short And Long Term ◽  
Prospective Controlled Study

Abstract: Introduction: Airway management is an integral part of general anaesthesia, which may lead to severe short- and long-term complications. Aim: We assessed whether the application of a checklist for the steps of airway management reduces the number of complications in our institute. Method: In our observational, prospective, controlled study we made a checklist and a data collection sheet. Each airway management was performed for one month without the checklist and then for one month in the possession of the checklist. We evaluated the outcome of airway maneuvers and the occurrence of related early complications before and after the introduction of the checklist. The primary endpoint was the incidence of unexpected difficult airway. The secondary endpoints were difficult intubation, successful first intubation, aspiration, cardiac arrest, post-induction hypotension and desaturation, soft tissues/teeth injuries. Our results were also corrected for factors that affect the risk of complications (urgency of interventions, medical experience). Results: We did not find any difference in the frequency of acute complications before the introduction of the checklist (n = 439) and during the subsequent period (n = 423). At the primary endpoint (7.29% and 6.14%), there was no substantive difference (1.15%, 95% CI: –2.26%–4.56%, p = 0.5). No differences were found regarding the secondary and other endpoints. Following the correction of risk factors, there was no impact of the checklist on the incidence of complications. Conclusion: The introduction of the checklist in itself did not result in a significant change in the risk of short-term complications of airway management in our institution. Orv Hetil. 2019; 160(26): 1025–1035.

Lithium Restores Abnormal Platelet 5-HT Transport in Patients with Affective Disorders

1980 ◽  
Vol 136 (3) ◽  
pp. 235-238 ◽  
Author(s):  
Alec Coppen ◽  
Cynthia Swade ◽  
Keith Wood
Keyword(s):  
Blood Platelets ◽  
Lithium Treatment ◽  
Before And After ◽  
Short And Long Term ◽  
5 Ht Uptake ◽  
Depressive Patients ◽  
Rate Of Accumulation

SummaryKinetic analysis of the transport of 5-HT into the blood platelets of depressed patients and recovered depressive patients has shown that the rate of accumulation of 5-hydroxytryptamine (5-HT) is significantly decreased both before and after recovery from the illness. This abnormality is corrected by both short and long-term lithium treatment. As a corollary to these studies, the effect of lithium in vitro on 5-HT uptake has been studied and the results are opposite to those reported in vivo. These findings suggest that lithium acts indirectly, and possible mechanisms of its action are discussed.

Priming-Induced Shift in Synaptic Plasticity in the Rat Hippocampus

1999 ◽  
Vol 82 (4) ◽  
pp. 2024-2028 ◽  
Author(s):  
Hongyan Wang ◽  
John J. Wagner
Keyword(s):  
Synaptic Plasticity ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Crossover Point ◽  
Term Potentiation ◽  
Before And After ◽  
History Of ◽  
The Brain ◽  
Dependent Mechanism

The activity history of a given neuron has been suggested to influence its future responses to synaptic input in one prominent model of experience-dependent synaptic plasticity proposed by Bienenstock, Cooper, and Munro (BCM theory). Because plasticity of synaptic plasticity (i.e., metaplasticity) is similar in concept to aspects of the BCM proposal, we have tested the possibility that a form of metaplasticity induced by a priming stimulation protocol might exhibit BCM-like characteristics. CA1 field excitatory postsynaptic potentials (EPSPs) obtained from rat hippocampal slices were used to monitor synaptic responses before and after conditioning stimuli (3–100 Hz) of the Schaffer collateral inputs. A substantial rightward shift (>5-fold) in the frequency threshold between long-term depression (LTD) and long-term potentiation (LTP) was observed <1 h after priming. This change in the LTD/P crossover point occurred at both primed and unprimed synaptic pathways. These results provide new support for the existence of a rapid, heterosynaptic, experience-dependent mechanism that is capable of modifying the synaptic plasticity phenomena that are commonly proposed to be important for developmental and learning/memory processes in the brain.

scholarly journals Normalizing the Abnormal: Do Antipsychotic Drugs Push the Cortex Into an Unsustainable Metabolic Envelope?

2019 ◽  
Vol 46 (3) ◽  
pp. 484-495 ◽  
Author(s):  
Federico E Turkheimer ◽  
Pierluigi Selvaggi ◽  
Mitul A Mehta ◽  
Mattia Veronese ◽  
Fernando Zelaya ◽  
...  
Keyword(s):  
Psychotic Symptoms ◽  
Antipsychotic Treatment ◽  
Long Term Effects ◽  
Extrapyramidal Syndrome ◽  
Before And After ◽  
Cardiac Disorders ◽  
Positive Symptoms Of Psychosis ◽  
The Brain ◽  
Novel Model

Abstract The use of antipsychotic medication to manage psychosis, principally in those with a diagnosis of schizophrenia or bipolar disorder, is well established. Antipsychotics are effective in normalizing positive symptoms of psychosis in the short term (delusions, hallucinations and disordered thought). Their long-term use is, however, associated with side effects, including several types of movement (extrapyramidal syndrome, dyskinesia, akathisia), metabolic and cardiac disorders. Furthermore, higher lifetime antipsychotic dose-years may be associated with poorer cognitive performance and blunted affect, although the mechanisms driving the latter associations are not well understood. In this article, we propose a novel model of the long-term effects of antipsychotic administration focusing on the changes in brain metabolic homeostasis induced by the medication. We propose here that the brain metabolic normalization, that occurs in parallel to the normalization of psychotic symptoms following antipsychotic treatment, may not ultimately be sustainable by the cerebral tissue of some patients; these patients may be characterized by already reduced oxidative metabolic capacity and this may push the brain into an unsustainable metabolic envelope resulting in tissue remodeling. To support this perspective, we will review the existing data on the brain metabolic trajectories of patients with a diagnosis of schizophrenia as indexed using available neuroimaging tools before and after use of medication. We will also consider data from pre-clinical studies to provide mechanistic support for our model.

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