<p>In a mouse model of ischemic stroke, infarct volume is highly variable and strain dependent, but the natural genetic determinants responsible for this difference remain unknown. To identify genetic determinants regulating ischemic neuronal damage and to dissect apart the role of individual genes and physiological mechanisms in infarction in mice, we performed forward genetic mapping analyses of surgically induced cerebral infarct volume. We have identified multiple quantitative trait loci (QTL) that modulate infarct volume, with a major locus (<italic>Civq1 </italic>) on chromosome 7 accounting for over 50% of the variation, with a combined LOD score of 21.7. Measurement of infarct volume in chromosome substitution strains (CSS) and two additional intercrosses validate that <italic>Civq1</italic> on chromosome 7 is present in multiple inbred strains. Interval-specific ancestral SNP haplotype analysis for <italic>Civq1</italic> results in 5 candidate genes. A causative gene underlying <italic>Civq1</italic> may regulate collateral artery formation and genetic variations in the gene may result in the differential outcome of cerebral infarction. Additionally, we have identified a locus of large effect, <italic>Civq4</italic>, modulating infarct volume through a mechanism different from collateral circulation. In conclusion, the extent of ischemic tissue damage after distal middle cerebral artery occlusion (MCAO) in inbred strains of mice is regulated by genetic variation mapping to at least 4 different loci. A single locus on chromosome 7 determines the majority of the observed variation in the trait in multiple mouse strains. <italic>Civq1</italic> appears to be identical to <italic>Lsq1</italic>, a locus conferring limb salvage and reperfusion in hindlimb ischemia. The identification of the genes underlying these loci may uncover novel genetic and physiological pathways that modulate cerebral infarction and provide new targets for therapeutic intervention in ischemic stroke, and possibly other human vascular occlusive diseases.</p> / Dissertation

Sickle cell anemia is a hematological disorder that is caused by a single point mutation in the beta-globin chain of hemoglobin. It results in several complications related to the small and large vessels in patients with the disease. Large vessel complications include cerebral infarcts, which are observed in children under ten years old. The mechanism behind this complication is not completely understood. It is the goal of this project to begin to understand the role sickle erythrocytes may play in causing endothelial dysfunction as a precursor to sickle related complications. The hypothesis of this work is that exposure of large vessel endothelium to sickle erythrocytes causes an increase in endothelial permeability through loosening of adherens junctions. In the first goal of this work, bovine aortic endothelial cells (BAECs) are grown on coverslips and exposed to sickle erythrocytes for 5 minutes and either immediately fixed or incubated in 30 minutes and then fixed. Immunofluorescent studies labeling VE cadherin show changes in VE cadherin dynamics, suggesting sickle erythrocytes may be involved in this observation. Next, BAECs were grown on transwell inserts and exposed to sickle erythrocytes for 5 minutes. The erythrocytes are washed off and the BAEC are incubated with 10,000 MW dextran conjugated to lucifer yellow or FITC-BSA or to determine BAEC permeability. When dextran is used as the test molecule, endothelial permeability did not show a significant change from baseline. However, when BSA is used as the test molecule, increases in endothelial permeability are observed. Explanations into the differences between the transport mechanisms of the two molecules are discussed. These experiments show changes in VE cadherin localization due to sickle erythrocyte exposure. This may cause increases in endothelial permeability and an experimental model and preliminary studies are performed. This study provides potential mechanisms to explain the changes in VE cadherin localization and provide suggestions for further studies to test the effect of sickle erythrocytes on endothelial permeability. This work provides a strong foundation for continuing studies on the effects of sickle erythrocytes on endothelial dysfunction within the confines of sickle related complications.

In this dissertation, we focus on development of algorithms for estimating the severity of air leakage and for predicting the out-of-adjustment of pushrod in an air brake system of heavy commercial vehicles. The leakage of air from the brake system causes a reduction in the steady-state pressure in the brake chamber and an increase in the lag of the braking pressure response thereby increasing the stopping distance of the vehicle. Currently a presence of leak in the system is detected for the severities of leak that cause the reservoir pressure to drop below a threshold, such as, the leakage of compressed air due to rupture of the reservoir or of the hoses carrying the compressed air. The leakage of air is also possible due to several other reasons such as, cracks in the hoses, loose couplings between the hoses etc. The severities of leak, corresponding to such situations, do not lead to the reservoir pressure drop below the threshold; therefore, their presence remains undetected. For the detection and estimation of such severities of leak, a diagnostic scheme has been given and is based on a model developed for the mass ow rate of the leakage of air from the air brake system. Out-of-adjustment of the pushrod is the extension of pushrod beyond a prede- ned value and for safety concerns, an extension beyond this value is not desired. Currently no warning system is available for monitoring the out-of-adjustment of pushrod, except, during the safety inspection. Inspection of the pushrod for outof- adjustment is the most labor-intensive and time consuming task during a typical safety inspection procedure. For efficient and continuous monitoring of the pushrod for out-of-adjustment, a diagnostic algorithm for estimating the steady-state pushrod stroke has been developed. The scheme is expected to expedite the inspection process for the out-of-adjustment of pushrod. Experimental data from the air brake test setup at Texas A and M University has been used for corroborating both the models. Also, the problem of parameter estimation of sequential hybrid systems such as the air brake system, has been addressed. The \hybrid" nature of the air brake system stems from the system being in di erent modes corresponding to di erent values of the displacement of the pushrod and is a result of di erent spring compliances associated with the pushrod in di erent ranges of its displacement. The air brake system is \sequential" in the sense that as the pressure increases, the displacement of the pushrod increases and there is a distinct sequence of modes that the system will transition through and upon a reduction in pressure, the sequence of modes is revisited in the reverse order. The mode to mode transition of the air brake system is governed by the parameters, such as, the clearance between the brake pad and the brake drum. The problem of estimation, that has been addressed, is as follows: Suppose the pressure in the air brake system were to be measured and that the motion of the pushrod is not measured. Is it possible to estimate the nal displacement of the pushrod without knowing the parameters, such as the clearance, that govern the system to transition from one mode to another?

No description available.

none

No description available.

<p>Varje år insjuknar mellan 25- 30 000 personer i stroke i Sverige. Cirka hälften av de som drabbas av stroke får ätsvårigheter. Svårigheter med att äta kan i sin tur leda till malnutrition. Syftet med denna studie är att belysa strokepatienters upplevelser av ätsvårigheter i samband med stroke. Studien har genomförts som en litteraturstudie, genom systematisk granskning och sammanställning av vetenskapliga artiklar skrivna mellan åren 1990-2007. I resultatet har det framkommit tre teman: problem att äta föda, känslomässiga upplevelser av ändrad ätsituation samt upplevelser av ändrad ätsituation. Detta kan bidra till att sjuksköterskan får mer kunskap om dessa patienters behov av stöd.</p>

<p>Sammanfattning</p><p>I dagens samhälle är bilkörning en viktig aktivitet för många individer. Att köra bil påverkar individens möjligheter till meningsfulla aktiviteter och självständighet. Efter att en person har fått en stroke kan personens körkort bli ifrågasatt. Ett vanligt bedömningsinstrument som arbetsterapeuter använder vid bedömning av kognitiv lämplighet inför fortsatt körkortsinnehav är Nordic Stroke Driver Screening Assessment (NorSDSA).</p><p>Syftet med denna kvantitativa studie var att jämföra parvisa NorSDSA-bedömningars resultat mellan äldre friska individer och äldre individer med stroke. Sex friska äldre individer matchades med sex äldre individer med stroke avseende ålder och kön. Resultaten visade en tendens till att äldre individer med stroke presterade ett lägre resultat på NorSDSA än äldre friska individer. Skillnaden i resultat visades främst i deltesten pricköverstrykning antal missar, riktningar och kompass. Slutresultatet på NorSDSA visade att alla äldre friska individer var godkända på testet medan en äldre individ med stroke hade ett godkänt resultat, en hade ett ovisst resultat och fyra hade ett underkänt resultat. Då urvalet var litet ska resultatet inte generaliseras, men resultatet väcker intresse att göra en större och fördjupad studie inom detta område.</p> / <p>Summary</p><p>A comparison of the results from the Nordic Stroke Driver Screening Assessment between elderly healthy individuals and elderly individuals with stroke.</p><p>In today’s society driving a car is an important activity for a lot of people. The ability to drive affects a person´s options regarding meaningful activities and independence. After a stroke, a person´s ability to continue driving might be questioned. Occupational therapists often use the Nordic Stroke Driver Screening Assessment (NorSDSA) to assess the cognitive suitability to drive a car.</p><p>The purpose with this quantitative study was a comparison of the results from the Nordic Stroke Driver Screening Assessment between elderly healthy individuals and elderly individuals with stroke. Six healthy elderly individuals were matched with six elderly individuals with stroke, with regards to ageand gender. The results showed a tendency for elderly individuals with stroke to score lower in the NorSDSA, than elderly healthy individuals. The differences in the results were particularly noticeable in the following test sections: direction tasks, compass and dot cancellation. The final results from the NorSDSA showed that all the elderly, healthy individuals passed the test while one elderly person with stroke passed, one had an uncertain result and four did not pass. Because of the small selection in this study the result should not be generalised but it raises an interest for a bigger and more in-depth study within this field.</p>

<p>Functional Magnetic Resonance Imaging, fMRI, can be used for analyzing brain activity in subjects performing language tasks. The purpose of this study was to develop aphasia-friendly information adjusted to aphasic subjects participating in fMRI studies. The objectives were to investigate if adjusted information was important for the ability to perform language tasks and if the information could be used for different types of aphasia.</p><p>Sixteen aphasic subjects participated in the study, six of these underwent fMRI. The participants varied in grade and type of aphasia. They had Swedish as their native language and were aged between 26 and 89, mean 57. Information was developed in three versions. The participants performed word generation and sentence completion language tasks.</p><p>Results showed that all the participants produced significantly more words (p < 0.05), and completed significantly more sentences (p < 0.001) in the final version. The fMRI results showed high intersession variability, therefore intra- or intersubject comparisons were difficult to make.</p><p>It was found that increased amount of time to solve the task and removal of the control task together with aphasia-friendly, concrete information improved performance. This applies to all participants, irrespective of aphasia type.</p>

Source: Masters Abstracts International, Volume: 47-06, page: 3527. Adviser: Charles E. Begley. Includes bibliographical references.