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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
591

Avaliação de proteção celular a isquemia de retalhos musculares com soluções preservadoras de tecidos em modelo de ratos / Avaliação de proteção celular à isquemia de retalhos musculares com soluções preservadoras de tecidos em modelo de ratos

Ramiro Hesiquio Silva 08 June 2009 (has links)
A transferência de retalhos livres e o reimplante de tecidos têm em comum a exposição dos tecidos à isquemia e tempos de reperfusão variáveis, que são importantes na determinação dos danos celulares estruturais e ultraestruturais, às vezes irreversíveis. O tempo de isquemia dificilmente pode ser controlado no período pré ou transoperatório, mas pode-se tentar prevenir ou diminuir as alterações celulares com soluções preservadoras, como, por exemplo, a da Universidade de Wisconsin, amplamente utilizada na prática clínica dos transplantes de tecidos. Porém a disponibilidade e o custo alto destas soluções dificultam seu uso rotineiro nos centros cirúrgicos. O presente trabalho propõe a utilização de solução de preservação (Solução Plástica-USP) que pode ser facilmente preparada com medicamentos accessíveis e baixo custo; a eficiência desta solução foi comparada com a da solução de Wisconsin. Os resultados demonstraram que não existe diferencia significativa entre a solução Plástica-USP, comparável à solução de Wisconsin; conferindo, ambas, um maior nível de proteção celular sobre os controles; beneficiando significativamente os resultados, e diminuindo assim os riscos de perdas do transplante a baixo custo / The free flaps transfer and reimplantation of tissue has in common the exposure of the tissue to ischemia and different time of reperfusion which are important for the determination of the extent of the cellular injury, being sometimes irreversible. In the pre and trans-surgical procedure the control of the ischemic period is difficult. Although efforts are made to prevent and decrease cellular changes using preservative solution, such as University of Wisconsin (UW) used in routine transplant of organs. The availability and high cost of this solution some time is one problem. The present study was made in a rat model that we have been reported in others works, we proposed the utilization of a preservation solution that we called Plastic Surgery-USP solution (PS-USP); witch can be easily prepared with accessible and low cost drugs. The efficiency of this PS-USP solution was compared to UW; our result showed that there is not significative difference in the protective effects of the PS-USP and UW solutions; both solutions were efficient considering cellular protection to ischemia/reperfusion injury, decreasing the risks of flap lost, with low cost and easy disposition
592

O papel do azul de metileno na prevenção da lesão de isquemia-reperfusão em transplante pulmonar de ratos: estudo experimental / The role of methylene blue in the prevention of ischemia-reperfusion injury in rat lung transplantation: an experimental study

Marcus da Matta Abreu 28 June 2013 (has links)
Introdução: O transplante de pulmão é uma opção terapêutica bem estabelecida para o tratamento de pneumopatias em estágio final. Uma complicação frequente relacionada aos transplantes é a lesão de isquemia e reperfusão (IR), estando o estresse oxidativo envolvido no processo. O azul de metileno (AM) é um inibidor da produção de espécies reativas de oxigênio, atuando como receptor alternativo de elétrons da xantina oxidase. Objetivo: Avaliar a eficácia do AM como inibidor da lesão de IR em transplante pulmonar de ratos. Métodos: Quarenta ratos fêmea Sprague Dawley (300g - 350g) foram divididas em quatro grupos de dez animais. Os animais foram submetidos a transplante pulmonar unilateral esquerdo. Os enxertos foram expostos a 3 ou 6 horas de isquemia fria seguido de 2 horas de reperfusão. Nos animais do grupo controle, 2 mL de solução salina foram injetados na cavidade peritoneal e, nos animais do grupo experimento, 2 mL de AM a 1% foram injetados da mesma forma. Resultados: A dosagem da PaO2 foi significativamente superior no grupo AM entre os animais submetidos a isquemia de 3 horas (AM = 150,2 ± 50,1 vs Salina = 102,6 ± 40,4 mmHg; p = 0,028), assim como a dosagem do óxido nítrico exalado foi significativamente inferior no mesmo grupo (AM = 3,2 ± 2,0 vs Salina = 5,2 ± 2,3 ppb; p = 0,05). O infiltrado neutrofílico foi menor nos animais do grupo AM submetidos a 6 horas de isquemia no lavado broncoalveolar (LBA); (AM = 11,8 ± 7,4 vs Salina = 30 ± 19,2 X 104/mL; p = 0,023). A análise histopatológica mostrou menor formação de edema perivascular no grupo AM submetido a 6 horas de isquemia (AM = 35,2 ± 7,65 vs Salina = 44,8 ± 6,39%; p = 0,001) e perialveolar no grupo AM submetido a 3 horas de isquemia (AM = 18,4 ± 14,2 vs Salina = 28,1 ± 18,2%; p = 0,041) e menor infiltrado neutrofílico perialveolar na comparação entre os grupos submetidos a 6 horas de isquemia (AM = 2,8 ± 2,2 vs Salina = 5,1 ± 3,1%; p = 0,046). Os níveis de IL-6 no LBA foram inferiores no grupo AM em ambos os tempos de isquemia (3 h - AM = 122,4 ± 24,9 vs Salina = 175.6 ± 50.3 pg/mL; p = 0.008; 6 h - AM = 142 ± 38,7 vs Salina = 351,3 ± 80,7 pg/mL; p = 0,002); Os níveis de TNF-? foram menores no grupo AM submetido a 6 horas de isquemia (AM = 189,5 ± 93,3 vs Salina = 342,9 ± 130,4 pg/mL, p = 0.007). A dosagem do ácido úrico foi significativamente maior no grupo AM em ambos os tempos de isquemia (3 h - AM = 4,7 ± 0,9 vs Salina = 2,7 ± 0,7 mg/dL; p = 0,003; 6 h - AM = 5,3 ± 2,4 vs Salina = 2,3 ± 0,9 mg/dL; p < 0,001). Não houve diferença entre os grupos em relação a apoptose. Conclusão: O AM demonstrou ser uma droga eficaz na prevenção da lesão de isquemia e reperfusão no transplante pulmonar de ratos / Introduction: Lung transplantation (LTx) has become an established therapeutic option for end-stage pulmonary disease. Ischemia reperfusion injury (IR) is a major cause of organ dysfunction after LTx and oxidative stress is involved in this process. Methylene blue (MB) is an inhibitor of reactive oxygen species production. Objective:To investigate the effects of MB on the IR in a rodent model of LTx. Methods: Forty female Sprague Dawley rats (300g - 350g) were divided into four groups (n = 10) according to treatment (saline solution or MB) and graft cold ischemic time (3 or 6 hours). Animals underwent a left-sided unilateral lung transplantation. Recipients received 2mL of intraperitoneal saline or MB 1%. After 2 hours of reperfusion, animals were killed and blood gas, exhaled nitric oxide, cell count and cytokines leves in bronchoalveolar lavage (BAL) as well as histopathology, serum uric acid and apoptosis were evaluated. Results: PaO2 was significantly higher in MB group undergoing 3 hour ischemic time (MB =150.2 ± 50.1 vs Saline = 102.6 ± 40.4 mmHg; p = 0.028). Exhaled nitric oxide values showed differences only between groups with 3 hour of ischemia (MB = 3.2 ± 2.0 vs Saline = 5.2 ± 2.3 ppb; p = 0.05). Neutrophils in BAL were different between groups subjected to 6 hours of ischemia (MB = 11.8 ± 7.4 vs Saline = 30.0 ± 19.2 x 104/mL; p = 0.023). IL-6 levels in BAL were lower in MB group in both ischemic time (3 h - MB = 122.4 ± 24.9 vs Saline = 175.6 ± 50.3 pg/mL; p = 0.008; 6 h - MB = 142 ± 38.7 vs Saline = 351.3 ± 80.7 pg/mL; p = 0.002); TNF-? levels were also lower in MB group undergoing 6 hour of ischemia (MB = 189.5 ± 93.3 vs Saline = 342.9 ± 130.4 pg/mL; p = 0.007). The number of neutrophils in lung parenchyma were reduced in MB group (6 h - MB = 2.8 ± 2.2 vs Saline = 5.1 ± 3.1%; p = 0.046) and also decreased edema in perivascular (6 h - MB = 35.2 ± 7.65 vs Saline = 44.8 ± 6.39%, p = 0.001) and perialveolar tissues (3 h - MB = 18.4 ± 14.2 vs Saline = 28.1 ± 18.2% p = 0,041) were observed. Uric acid levels were higher in MB group in both ischemic time (3 h - MB = 4.7 ± 0.9 vs Saline = 2.7 ± 0.7 mg/dL; p = 0.003; 6 h - MB = 5.3 ± 2.4 vs Saline = 2.3 ± 0.9 mg/dL; p < 0.001).There were no difference in the expression of apoptosis. Conclusion: MB was able to prevent ischemia-reperfusion injury in this lung transplantation model and represent a new option for further studies
593

Avaliação do efeito da manutenção da perfusão e ventilação dos pulmões durante a circulação extracorpórea sobre a resposta inflamatória: estudo experimental / Pulmonary inflammatory response following extracorporeal circulation with lung perfusion and ventilation

Cláudia Regina da Costa Freitas 13 May 2013 (has links)
INTRODUÇÃO: A isquemia-reperfusão pulmonar e o uso do oxigenador de membranas são considerados fatores importantes na resposta inflamatória após a cirurgia cardíaca (CC) com utilização da circulação extracorpórea (CEC). Estudos anteriores que utilizaram os próprios pulmões dos pacientes como oxigenador em uma circulação extracorpórea biventricular (CECBV) em comparação à CEC convencional (CECC) mostraram efeitos benéficos na mecânica pulmonar e na reação inflamatória sistêmica. No entanto, a inflamação pulmonar ainda não foi totalmente esclarecida neste cenário. Os objetivos deste estudo foram observar o impacto da exclusão do oxigenador de membranas e da manutenção da ventilação e perfusão pulmonar na inflamação regional em porcos submetidos à CEC. MÉTODOS: Vinte e sete porcos ventilados mecanicamente foram submetidos à toracotomia e alocados randomicamente nos grupos: Controle (n=8), CECC (n=9) e CECBV (n=10). Os animais dos grupos CECC e CECBV foram submetidos respectivamente a uma CEC convencional ou a uma CEC biventricular com ventilação e perfusão pulmonar sem oxigenador de membranas por 90 minutos. As interleucinas (ILs) séricas foram avaliadas nos momentos: basal, após a CEC e 90 minutos após a CEC, e em momentos equivalentes no grupo Controle. As ILs do lavado broncoalveolar (LBA) foram medidas nos momentos basal e 90 minutos após a CEC. Amostras de tecido pulmonar foram coletadas da região ventral e dorsal do lobo pulmonar esquerdo para avaliação do número de polimorfonucleares (PMN) e quantificação do edema pela área de parênquima. Os dados foram avaliados através de ANOVA, considerando-se estatisticamente significante p<0,05. RESULTADOS: O grupo CECC apresentou uma maior inflamação, com um aumento no número de PMN, comparado ao grupo Controle (p < 0,001) nas regiões: ventral (2,8 x10-6± 0,7 x10-6 vs. 1,6 x10-6 ± 0,5 x10-6 , respectivamente) e dorsal (3,3 x10-6 ± 1,0 x10-6 vs. 1,9 x10- 6 ± 0,5 x10-6, respectivamente) e ao grupo CECBV (p = 0,006) nas regiões: ventral (2,3 x10-6 ± 0,7 x10-7) e dorsal (2,1 x10-6 ± 0,7 x10-6). Edema foi maior no grupo CECC comparado ao Controle nas regiões ventral e dorsal (2,4 x10-2 ± 3,5 x10-2 vs. 8,2 x10-4 ± 0,2 x10-4 e 5,7 x10 -2 ± 4,3 x10-2 vs. 0,3 x10-2 ± 1,0 x10-2, respectivamente, p = 0,016) e mais intenso na região dorsal em todos os grupos (p = 0,004). As IL 10 e IL6 do LBA foram maiores nos grupos submetidos à CECC (41,9 ± 12,2, p = 0,010 e 239,4 ± 45,2, p < 0,001, respectivamente) e à CECBV (40,7 ± 12,0, p = 0,016 e 174,8 ± 61,2, p = 0,004, respectivamente) comparadas ao Controle (21,0 ± 6,9 e 71,8 ± 29,8, respectivamente). As ILs séricas não diferiram entre os grupos (p > 0,05). O Grupo CECC, comparado ao grupo CECBV, mostrou um aumento maior com o tempo na IL6 do LBA (239,4 ± 45,2 vs. 174,8 ± 61,2, p = 0,027, respectivamente) e na IL8 sérica (193,1 ± 108,8 vs. 147,0 ± 59,4, p = 0,040, respectivamente). CONCLUSÕES: Em modelo experimental de circulação extracorpórea em porcos, a manutenção da perfusão e ventilação dos pulmões na CEC biventricular atenua a inflamação pulmonar em comparação à CEC convencional / BACKGROUND: Lung ischemia-reperfusion injury and the membrane oxygenator are considered important factors in the inflammatory response after cardiac surgery and cardiopulmonary bypass (CPB). Previous studies using the own lung as the oxygenator with a biventricular bypass demonstrated the beneficial effects of this technique. However, lung inflammation was not fully evaluated in this scenario. The aim of this study was to observe the impact of the exclusion of the membrane oxygenator and maintenance of lung perfusion on regional lung inflammation in pigs undergoing cardiopulmonary bypass. METHODS: Twenty-seven mechanically ventilated pigs were subjected to a thoracotomy and randomly allocated into Control (n=8), CPB (n=9) or Lung Perfusion (n=10) groups. Animals from the CPB group and Lung Perfusion group were subjected respectively to a conventional CPB or to a biventricular bypass with pulmonary ventilation and perfusion without a membrane oxygenator for 90 minutes. The systemic interleukins (ILs) were determined at baseline, after bypass and 90 min after bypass or at equivalent times in the Control group. ILs from bronchoalveolar lavage fluid (BAL) were evaluated at baseline and 90 min after bypass. Tissue samples were collected from the dorsal and ventral regions of the left lung for assessment of the number of polymorphonuclear leukocytes (PMN) per parenchyma area and edema. Data were evaluated using ANOVA and p< 0.05 was considered significant. RESULTS: The CPB group showed increased lung inflammation, with an increased PMN count compared to the Control (p<0,001) at ventral (2.8 x10-6± 0.7 x10-6 vs. 1.6 x10-6± 0.5 x10-6 , respectively) and dorsal regions (3.3 x10-6 ± 1.0 x10-6 vs. 1.9 x10-6 ± 0.5 x10-6, respectively) and to Lung Perfusion Group (p = 0.006) at ventral (2.3 x10-6 ± 0.7 x10-7) e dorsal regions (2.1 x10-6 ± 0.7 x10-6). Edema was higher in the CPB group compared to the Control at ventral and dorsal regions (2.4 x10-2± 3.5 x10-2 vs. 8.2 x10 -4± 0.2 x10-4 and 5.7 x10 -2 ± 4.3 x10-2 vs. 0.3 x10-2 ± 1.0 x10-2, respectively, p = 0.016) and increased in the dorsal region in all groups (p = 0.004). BAL IL10 and IL6 were higher in groups subjected to CPB group (41.9 ± 12.2, p = 0.010 e 239.4 ± 45.2, p<0.001, respectively) and to Lung Perfusion group (40.7 ± 12.0, p = 0.016 e 174.8 ± 61.2, p = 0.004, respectively) compared to Control group (21.0 ± 6.9 e 71.8 ± 29.8). Systemic interleukins did not differ between groups (p > 0.05). The CPB group compared to Lung Perfusion group showed a higher increase in BAL IL6 (239,4 ± 45,2 vs. 174,8 ± 61,2, p = 0,027, respectively) and in serum IL8 over time (193,1 ± 108,8 vs. 147,0 ± 59,4, p = 0,040, respectively). CONCLUSIONS: In a pig model of extracorporeal circulation, maintenance of lung perfusion and ventilation with biventricular bypass attenuates the pulmonary inflammation as compared to conventional CPB
594

Stroke thrombolysis on equal terms? : implementation and ADL outcome

Stecksén, Anna January 2017 (has links)
Stroke thrombolysis is a method for restoring cerebral blood flow after ischemic stroke, with high priority in the Swedish national guidelines. implementation of stroke thrombolysis in Swedish routine stroke care has shown marked differences between demographic groups, hospital types, and regions. The general aim of this thesis were to examine the implementation of ischemic stroke thrombolysis in Swedish routine stroke care with an equity perspective; to gain more insight into the factors that influence implementation, how the treatment has reached patient groups, and differences in long-term outcomes between women and men. Analysis of data from research interviews with clinicians working within stroke care displayed that the facilitators of and barriers to the implementation of stroke thrombolysis could broadly be categorized into those related to individuals, to social interactions and context, and to organizational and resource issues. Key facilitating factors expressed in interviews were work pride and motivation, good leadership, involvement of all staff members in the implementation process, and quality assurance. Major barriers concerned lack of competence and experience, outdated attitudes regarding stroke management, counterproductive power structures, lack of continuity, and insufficient human resources. National quality register data displayed that stroke thrombolysis treatment expanded to reach more patients with mild deficits. Groups with higher education were more likely to receive treatment, compared to groups with lower educational level. These education group differences have, however, decreased over time in relative terms, but not in absolute terms. Further, there were considerable between-hospitals differences in treatment rates for patients with milder deficits, associated with hospital’s overall stroke thrombolysis rates. Moreover, larger non-university hospitals displayed treatment rate differences between educational groups that were not attributable to patient characteristics. Among thrombolysis-treated women and men, that was independent in ADL before their stroke and survived the first year post-stroke, women experienced higher probability to be dependent in ADL at both 3 and 12 months post-stroke, compared to men. This difference remained significant despite comprehensive adjustments for individual characteristics, symptom severity, and acute effects from stroke thrombolysis. This thesis displays that clinicians face barriers and facilitators at several levels, suggesting implementation interventions could be targeted towards both the individual-, the social interactions and context-, and also the organisation and available resources level. Assurance of clinicians’ individual competence, peer support, and clinical leadership seem to be important areas to intervene. Stroke thrombolysis rates have expanded over time, and an increase in stroke thrombolysis delivery to patients with mild stroke symptoms has contributed to this increase. However, it seems considerable differences between hospitals inhibit equity of care delivery. Further, socioeconomically disadvantaged groups receive less often stroke thrombolysis. Type of hospital seems to play a role, yet the reasons for this difference are not fully understood. This thesis also display that stroke thrombolysis-treated women that survive 1 year after stroke, appears to face higher risk for dependency in ADL, compared to men. / <p>Incorrect ISBN in print version 978-91-760-711-1. Correct ISBN should be 978-91-7601-711-1.</p>
595

Potential neuroprotective effects of fermented rooibos herbal tea in a rat model of ischemic brain injury

Akinrinmade, Olusiji Alex January 2015 (has links)
Magister Scientiae (Medical Bioscience) - MSc(MBS) / Stroke is the third leading cause of death in South Africa, killing about 240 people a day and leaving survivors with residual disabilities. There is no clinically approved neuroprotective agent for stroke at the moment but the consumption of plant polyphenols has been suggested to offer neuroprotection against stroke and other neurodegenerative diseases. In this study, we investigated the effects of long term consumption of fermented rooibos herbal tea (FRHT) on ischemia reperfusion brain injury (I-RBI) in rats. Male adult Wistar rats were fed FRHT ad libitum for 7 weeks prior to the induction of ischemic injury by the transient bilateral occlusion of the common carotid arteries (BCCAO) for 20 minutes followed by 24 hours, 4 and 7 days of reperfusion respectively. Rats were then evaluated for neurologic deficits before sacrifice and brains harvested for assessment of brain oedema, blood-brain-barrier (BBB) integrity through Evans blue extravasation (EBE), immunohistochemical studies of apoptosis and lipid peroxidation. Oxygen radical antioxidant capacity and ferric reducing antioxidant power assays were also conducted to assess total antioxidant capacity after ischemia-reperfusion injury. Notably, the long term consumption of fermented rooibos herbal tea prevented brain oedema by reducing cerebral swelling induced by I-RBI. We also observed that fermented rooibos herbal tea offered neuroprotection against damage to the BBB and delayed neuronal death associated with BCCAO as fewer apoptotic cells were identified 7 days post BCCAO reperfusion. Significantly reduced levels of lipid peroxidation and increased levels of total antioxidant capacity were also observed in brain specimens of rats treated with FRHT. Rats treated with FRHT also showed improved neurologic outcomes when compared with the untreated animals. Our results show that FRHT has potent antioxidant and anti-inflammatory properties which can provide neuroprotective effects against neuronal cell loss, cerebral swelling, BBB disruption, lipid peroxidation and neurologic deficits following I-RBI. The use of FRHT is therefore highly recommended for patients with conditions that predispose them to stroke.
596

Evaluating Angiotensin II Type 1 Receptor Changes in Post- Renal Insufficiency and in Left Anterior Descending Artery Ligation Animal Models Using [11C]Methyl-Candesartan

Mackasey, Kumiko January 2012 (has links)
Non invasive in vivo imaging will lead to better understanding of Angiotensin II Type 1 Receptor’s (AT1R) role in disease progression and may guide therapy in cardiovascular patients. Two models were used in this project: 5/6 nephrectomy and transient left anterior descending (LAD) ligation. Rats were scanned with [13N]ammonia and [11C]methyl-candesartan, both of which are Positron Emission Tomography (PET) tracers, at 8 weeks (nephrectomy) and 2 weeks (LAD ligation) after surgery. Western blot analysis was used to corroborate PET data. Nephrectomy: Renal AT1R image analysis displayed a 40% decrease in kidney AT1R in nephrectomized animals compared to sham (p<0.05) which was confirmed with Western blot and biodistribution. LAD ligation: Left Ventricle AT1R Western blot analysis exhibited a 60% increase in 20min ligation (p<0.05) with maintained myocardial blood flow. In conclusion, changes in renal AT1R were successfully imaged using [11C]methyl-candesartan in nephrectomized animals, and 20min LAD ligation/reperfusion is an appropriate model to image an increase in cardiac AT1R following ischemic injury.
597

Modifications of Myofilament Structure and Function During Global Myocardial Ischemia

Woodward, Mike K 07 November 2016 (has links)
Cardiac arrest is a prevalent condition with a poor prognosis, attributable in part to persistent myocardial dysfunction following resuscitation. The molecular basis of this dysfunction remains unclear. We induced cardiac arrest in a porcine model of acute sudden death and assessed the impact of ischemia and reperfusion on the molecular function of isolated cardiac contractile proteins. Cardiac arrest was electrically induced, left untreated for 12 min, and followed by a resuscitation protocol. With successful resuscitations, the heart was reperfused for 2 h (IR2) and the muscle harvested. In failed resuscitations, tissue samples were taken following the failed efforts (IDNR). Actin filament velocity, using myosin isolated from IR2 or IDNR cardiac tissue, was nearly identical to myosin from the control tissue in a motility assay. However, both maximal velocity (25% faster than control) and Ca2+ sensitivity (pCa50 6.57 ± 0.04 IDNR vs. 6.34 ± 0.07 control) were significantly (p < 0.05) enhanced using native thin filaments (actin, troponin, and tropomyosin) from IDNR samples, suggesting that the enhanced velocity is mediated through an alteration in muscle regulatory proteins (troponin and tropomyosin). Mass spectrometry analysis showed that only samples from the IR2 had an increase in total phosphorylation levels of troponin (Tn) and tropomyosin (Tm), but both IR2 and IDNR samples demonstrated a significant shift from mono-phosphorylated to bis-phosphorylated forms of the inhibitory subunit of Tn (TnI) compared to control. This suggests that the shift to bis-phosphorylation of TnI is associated with the enhanced function in IDNR, but this effect may be attenuated when phosphorylation of Tm is increased in tandem, as was observed for IR2. There are likely many other molecular changes induced following cardiac arrest, but to our knowledge, these data provide the first evidence that this form cardiac arrest can alter the in vitro function of the cardiac contractile proteins.
598

NONINVASIVE CHARACTERIZATION OF 3D MYOCARDIAL STRAIN IN MURINE LEFT VENTRICLES POST INFARCTION

Arvin H Soepriatna (7910957) 22 November 2019 (has links)
Coronary artery disease remains the leading cause of death in the United States with over 1 million acute coronary events predicted to take place in 2019 alone. Heart failure, a common and deadly sequela of myocardial infarction (MI), is attributed to adverse ventricular remodeling driven by cardiomyocyte death, inflammation, and mechanical factors. Despite strong evidence suggesting the importance of myocardial mechanics in driving cardiac remodeling, many <i>in vivo</i> MI studies still rely on 2D analyses to estimate global left ventricular (LV) function and approximate strain using a linear definition. These metrics, while valuable in evaluating the overall impact of ischemic injury on cardiac health, do not capture regional differences in myocardial contractility. The objective of this work is therefore to expand upon existing ultrasound studies by enabling regional analysis of 3D myocardial strain. By integrating our recently developed four-dimensional ultrasound (4DUS) imaging technique with a direct deformation estimation algorithm for 3D strain, we identified unique remodeling patterns and regional strain differences between two murine models of MI with different infarct severities. By constructing 3D strain maps of the remodeling LVs, we were able to capture strain heterogeneity and characterize a sigmoidal strain profile at infarct border zones. Finally, we demonstrated that the maximum principal component of the 3D Green-Lagrange strain tensor correlates with LV remodeling severity and is predictive of final infarct size. Taken together, the presented work provides a novel and thorough approach to quantify regional 3D strain, an important component when assessing post-MI remodeling.
599

Studium beta-adrenergní signalizace v myokardu potkana během adaptace na chronickou hypoxii / Myocardial beta-adrenergic signaling during adaptation of rats to chronic hypoxia

Hahnová, Klára January 2011 (has links)
Endogenous cardiac protection against acute ischemia/reperfusion injury can by increased by cardiac adaptation to various forms of chronic hypoxia. Chronic hypoxia induces a large variety of adaptive changes in the myocardium that could be considered as protective, but the exact mechanism of increased ischemic tolerance is unknown. Different studies suggest that catecholamine release and their effect on -adrenergic signaling after adaptation to chronic hypoxia contributes to cardioprotection. In this study we focused on characterization of -adrenergic receptors ( -ARs) in the myocardium of rats after adaptation to three different hypoxic conditions: 1. intermittent normobaric hypoxia - INH/R (23 h hypoxia, 1 h reoxygenation), 2. intermittent normobaric hypoxia - INH (8 h hypoxia, 16 h normoxia), 3. continuous normobaric hypoxia - CNH (24 h hypoxia). We compared how each hypoxic model affects the total number of -adrenergic receptors and proportion of individual subtypes ( 1-and 2-ARs) in the left and right ventricles compared control normoxic rats. The INH model had apparently no effect on -ARs in either ventricles. On the other hand, adaptation to INH/R and CNH was accompanied by a significant decrease (by about 25%) in the total number of -adrenergic receptors in the right ventricles. Our present...
600

Det akuta omhändertagandet av patienter med st-höjningsinfarkt : en litteraturöversikt för att identifiera faktorer som påverkar tidsflödet från första vårdkontakt fram till reperfusionsbehandling / The acute care of patients with st-elevation myocardial infarction : a literature review to identify factors that affect the timeflow from first medical contact to reperfusion therapy

Joelsson, Elin, Spiess, Maria January 2022 (has links)
En så tidig reperfusionsbehandling som möjligt hos patienter med ST-höjningsinfarkt förbättrar prognosen både gällande kardiell status och minskad dödlighet. Arbetet runt patienten måste ske skyndsamt men samtidigt med hög kompetens. Trots tydliga riktlinjer och tidsmål för reperfusionsbehandling uppfylls inte alltid dessa. Med ökad förståelse för faktorer som påverkar tidsflödet från första vårdkontakt till reperfusionsbehandling skapas förutsättningar för ett mer tidseffektivt och därmed säkrare omhändertagande av patienter som drabbade av ST-höjningsinfarkt. Syftet var att identifiera faktorer som påverkar tidsflödet från första vårdkontakt till reperfusionsbehandling vid det akuta omhändertagandet av patienter med ST-höjningsinfarkt. Metoden var en icke systematisk litteraturöversikt. Totalt inkluderades 15 artiklar både av kvantitativ- och kvalitativ ansats. Artiklarna som inkluderades i resultatet kvalitetsgranskades utifrån Sophiahemmets bedömningsunderlag för att klassificera och kvalitetsbedöma de vetenskapliga artiklarna. Artiklarna analyserades med integrerad analysmetod där likheter och olikheter mellan artiklarna identifierades, sammanställdes och delades in i underrubriker samt kategorier. I resultatet framkom fyra huvudkategorier; “Patientrelaterade faktorer”, “System-och organisatoriska faktorer”, “Vårdpersonalens inflytande” och “Kommunikation”. Resultatet från litteraturöversikten visar faktorer som hade både positiv och negativ inverkan på tidsåtgången från första vårdkontakt till reperfusionsbehandling. Faktorer som associerades med förlängd tidsåtgång var: prehospitalt långa transporttider, ospecifika symtom och otillgängligt Percutant Coronar Interventions-lab (PCI-lab). Faktorerna som associerades med tidssparande effekt var: prehospitalt EKG, när patienten transporterades direkt till PCI-lab utan att gå via akuten, prehospital notifikation, fungerande teamarbete, standardiserade arbetssätt och protokoll, organisatoriskt engagemang med regelbunden feedback till personalen samt kompetensutbildning. Slutsatsen är att faktorer som associerades med förlängd tidsåtgång var prehospitalt långa transportavstånd, ospecifika symtom och otillgängligt PCI-lab. Faktorerna som associerades med tidssparande effekt var prehospitalt EKG, direkt transport till PCI-lab utan att passera akutmottagningen, fungerande teamarbete med god kommunikation, standardiserade arbetssätt, organisatoriskt engagemang med regelbunden feedback och utvärdering samt kompetensutbildning för berörd personal. För att identifiera faktorer som är tidsvinnande och skapa nya strategier krävs engagemang och samarbete från samtliga professioner som möter patienten. / As early reperfusion therapy as possible in patients with ST-elevation infarction, the prognosis improves both in terms of cardiac status and reduced mortality. The care around the patient must be done quickly but at the same time with high knowledge precision. Despite clear guidelines and goals for reperfusion, not everyone lives up to them. With an increased understanding of factors that affect the flow of time from initial care contact to reperfusion treatment, conditions are created for more time-efficient and safer care of patients suffering from ST-elevation myocardial infarction. The aim was to identify factors that affect the time flow from first medical contact to reperfusion therapy in the acute care of patients with ST-elevation myocardial infarction. The method was a literature study with a systematic search strategy. A total of 15 articles were included which were both quantitative and qualitative. The articles that were included in the results section were read through several times by both authors and quality reviewed with assessment data for literature studies. The articles were analyzed with an integrated analysis method and divided into subheadings and categories. The results revealed four main categories; "Patient-related factors", "System and organizational factors", "Influence of care staff" and "Communication". The results from the literature review show factors that had both a positive and negative impact on the time required from first medical contact to reperfusion therapy. Factors associated with prolonged time consumption were: prehospital transport times, nonspecific symptoms, and unavailable Percutaneous Coronary Intervention-lab (PCI-lab). The factors associated with the timesaving effect were: prehospital ECG, when the patient was transported directly to the PCI-lab without going through the emergency room, prehospital notification, functioning teamwork, standardized working methods and protocols, organizational commitment with regular feedback to staff and skills training The conclusion is that factors associated with prolonged time consumption were prehospital long transport distances, nonspecific symptoms and unavailable PCI lab. The factors associated with time-saving effect were prehospital ECG, direct transport to PCI-lab without passing the emergency room, functioning teamwork with good communication, standardized working methods, organizational commitment with regular feedback and evaluation and competence training for relevant staff. Identifying factors that are time-saving and creating new strategies requires commitment and cooperation from all professionals who meet the patient.

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