Physiological and pathological human ocular perfusion characteristics

There were three principle aims to this thesis. Firstly, the acquisition protocols of clinical blood flow apparatus were investigated in order to optimise them for both cross-sectional and longitudinal application. Secondly, the effects of physiological factors including age and systematic circulation on ocular blood flow were investigated. Finally, the ocular perfusion characteristics of patients diagnosed with ocular diseases considered to be of a vascular origin were investigated. The principle findings of this work are:- 1) Optimisation of clinical investigationsPhotodiode sensitivity of the scanning laser Doppler flowmeter should be kept within a range of 70-150 DC when acquiring images of the retina and optic nerve head in order to optimise the reproducibility of capillary blood flow measures. Account of the physiological spatial variation in retinal blood flow measures can be made using standard analysis protocols of the scanning laser Doppler flowmeter combined with a local search strategy. Measurements of pulsatile ocular blood flow using the ocular blood flow analyser are reproducible, however this reproducibility can be improved when consecutive intraocular pressure pulses are used to calculate pulsatile ocular blood flow. Spectral analysis of the intraocular pressure pulse-wave is viable and identifies the first four harmonic components of the waveform. 2) Physiological variation in ocular perfusionAge results in a significant reduction in perfusion of the retinal microcirculation, which is not evident in larger vessel beds such as the choroid. Despite known asymmetry in the systemic vasculature, no evidence of interocular asymmetry in ocular perfusion is apparent. 3) Pathological variation in ocular perfusionIn primary open angle glaucoma, perfusion is reduced in the retinal microcirculation of patients classified as having early to moderate visual field defects. However, ocular pulsatility defects are masked when patients and subjects are matched for systemic variables (pulse rate and mean arterial pressure); differentiation is facilitated by the application of waveform analysis to the continuos intraocular pressure curve even in the early stages of disease. Diabetic patients with adequate glycaemic control, exhibit maintenance of macular blood flow, macular topography and visual function following phacoemulsification.

The effect of innate compliance on the performance of a counterpulsation device

Cardiovascular disease (CVD) continues to be one of the top causes of mortality in the world. World Heart Organization (WHO) reported that in 2004, CVD contributed to almost 30% of death from estimated worldwide death figures of 58 million[1]. Heart failure treatment varies from lifestyle adjustment to heart transplantation; its aims are to reduce HF symptoms, prolong patient survival and minimize risk [2]. One alternative available in the market for HF treatment is Left Ventricular Assist Device (LVAD). Chronic Intermittent Mechanical Support (CIMS) device is a novel (LVAD) heart failure treatment using counterpulsation similar to Intra Aortic Balloon Pumps (IABP). However, the implantation site of the CIMS balloon is in the ascending aorta just distal to aortic valve contrasted with IABP in the descending aorta. Counterpulsation coupled with implantation close to the aortic valve enables comparable flow augmentation with reduced balloon volume. Two prototypes of the CIMS balloon were constructed using rapid prototyping: the straight-body model is a cylindrical tube with a silicone membrane lining with zero expansive compliance. The compliant-body model had a bulging structure that allowed the membrane to expand under native systolic pressure increasing the device’s static compliance to 1.5 mL/mmHg. This study examined the effect of device compliance and vascular compliance on counterpulsating flow augmentation. Both prototypes were tested on a two-element Windkessel model human mock circulatory loop (MCL). The devices were placed just distal to aortic valve and left coronary artery. The MCL mimicked HF with cardiac output of 3 L/min, left ventricular pressure of 85/15 mmHg, aortic pressure of 70/50 mmHg and left coronary artery flow rate of 66 mL/min. The mean arterial pressure (MAP) was calculated to be 57 mmHg. Arterial compliance was set to be1.25 mL/mmHg and 2.5 mL/mmHg. Inflation of the balloon was triggered at the dicrotic notch while deflation was at minimum aortic pressure prior to systole. Important haemodynamics parameters such as left ventricular pressure (LVP), aortic pressure (AoP), cardiac output (CO), left coronary artery flowrate (QcorMean), and dP (Peak aortic diastolic augmentation pressure – AoPmax ) were simultaneously recorded for both non-assisted mode and assisted mode. ANOVA was used to analyse the effect of both factors (balloon and arterial compliance) to flow augmentation. The results showed that for cardiac output and left coronary artery flowrate, there were significant difference between balloon and arterial compliance at p < 0.001. Cardiac output recorded maximum output at 18% for compliant body and stiff arterial compliance. Left coronary artery flowrate also recorded around 20% increase due to compliant body and stiffer arterial compliance. Resistance to blood ejection recorded highest difference for combination of straight body and stiffer arterial compliance. From these results it is clear that both balloon and arterial compliance are statistically significant factors for flow augmentation on peripheral artery and reduction of resistance. Although the result for resistance reduction was different from flow augmentation, these results serves as an important aspect which will influence the future design of the CIMS balloon and its control strategy. References: 1. Mathers C, Boerma T, Fat DM. The Global Burden of disease:2004 update. Geneva: World Heatlh Organization; 2008. 2. Jessup M, Brozena S. Heart Failure. N Engl J Med 2003;348:2007-18.

Enhanced diabetes care to patients of south Asian ethnic origin (the United Kingdom Asian Diabetes Study):a cluster randomised controlled trial

Background - Delivery of high-quality, evidence-based health care to deprived sectors of the community is a major goal for society. We investigated the effectiveness of a culturally sensitive, enhanced care package in UK general practices for improvement of cardiovascular risk factors in patients of south Asian origin with type 2 diabetes. Methods - In this cluster randomised controlled trial, 21 inner-city practices in the UK were assigned by simple randomisation to intervention (enhanced care including additional time with practice nurse and support from a link worker and diabetes-specialist nurse [nine practices; n=868]) or control (standard care [12 practices; n=618]) groups. All adult patients of south Asian origin with type 2 diabetes were eligible. Prescribing algorithms with clearly defined targets were provided for all practices. Primary outcomes were changes in blood pressure, total cholesterol, and glycaemic control (haemoglobin A1c) after 2 years. Analysis was by intention to treat. This trial is registered, number ISRCTN 38297969. Findings - We recorded significant differences between treatment groups in diastolic blood pressure (1·91 [95% CI -2·88 to -0·94] mm?Hg, p=0·0001) and mean arterial pressure (1·36 [-2·49 to -0·23] mm?Hg, p=0·0180), after adjustment for confounders and clustering. We noted no significant differences between groups for total cholesterol (0·03 [-0·04 to 0·11] mmol/L), systolic blood pressure (-0·33 [-2·41 to 1·75] mm?Hg), or HbA1c (-0·15% [-0·33 to 0·03]). Economic analysis suggests that the nurse-led intervention was not cost effective (incremental cost-effectiveness ratio £28?933 per QALY gained). Across the whole study population over the 2 years of the trial, systolic blood pressure, diastolic blood pressure, and cholesterol decreased significantly by 4·9 (95% CI 4·0–5·9) mm?Hg, 3·8 (3·2–4·4) mm?Hg, and 0·45 (0·40–0·51) mmol/L, respectively, and we recorded a small and non-significant increase for haemoglobin A1c (0·04% [-0·04 to 0·13]), p=0·290). Interpretation - We recorded additional, although small, benefits from our culturally tailored care package that were greater than the secular changes achieved in the UK in recent years. Stricter targets in general practice and further measures to motivate patients are needed to achieve best possible health-care outcomes in south Asian patients with diabetes. Funding - Pfizer, Sanofi-Aventis, Servier Laboratories UK, Merck Sharp & Dohme/Schering-Plough, Takeda UK, Roche, Merck Pharma, Daiichi-Sankyo UK, Boehringer Ingelheim, Eli Lilly, Novo Nordisk, Bristol-Myers Squibb, Solvay Health Care, and Assurance Medical Society UK.

The hypotensive effect of acute and chronic AMP-activated protein kinase activation in normal and hyperlipidemic mice

AMP-activated protein kinase (AMPK) is present in the arterial wall and is activated in response to cellular stressors that raise AMP relative to ADP/ATP. Activation of AMPK in vivo lowers blood pressure but the influence of hyperlipidemia on this response has not been studied. ApoE-/- mice on high fat diet for 6 weeks and age-matched controls were treated with the AMPK activator, AICAR daily for two weeks. Under anesthesia, the carotid artery was cannulated for blood pressure measurements. Aortic tissue was removed for in vitro functional experiments and AMPK activity was measured in artery homogenates by Western blotting. ApoE-/- mice had significantly raised mean arterial pressure; chronic AICAR treatment normalized this but had no effect in normolipidemic mice, whereas acute administration of AICAR lowered mean arterial pressure in both groups. Chronic AICAR treatment increased phosphorylation of AMPK and its downstream target acetyl-CoA carboxylase in normolipidemic but not ApoE-/- mice. In aortic rings, AMPK activation induced vasodilation and an anticontractile effect, which was attenuated in ApoE-/- mice. This study demonstrates that hyperlipidemia dysregulates the AMPK pathway in the arterial wall but this effect can be reversed by AMPK activation, possibly through improving vessel compliance.

Efeitos do treino de marcha em esteira com adição de carga ao membro inferior não parético de indivíduos com acidente vascular cerebral: ensaio clínico controlado e randomizado

Introduction: Gait after stroke is characterized by a significant asymmetry between the lower limbs, with predominant use of the non-paretic lower limb (NPLL) over using the paretic lower limb. Accordingly, it has been suggested that adding load/weight to the NPLL as a form of restricting the movement of this limb may favor the use of the paretic limb, reducing interlimb asymmetry. However, few studies have been conducted up to this moment, which only investigated the immediate effects of this practice. Objectives: 1) Investigating whether there is an influence of adding load to the NPLL during treadmill training on cardiovascular parameters and on gait performance of individuals with stroke, compared to treadmill training without load addition; 2) Analyzing the effects of treadmill training with and without load added to the NPLL on kinematic parameters of each lower limb during gait; 3) Analyzing the effects of treadmill training with and without load added to the NPLL on measurements of functional mobility and postural balance of these patients. Materials and Methods: This is a randomized single blinded clinical trial involving 38 subjects, with a mean age of 56.5 years, at the subacute post-stroke phase (with mean time since stroke of 4.5 months). Participants were randomly assigned into an experimental group (EG) or control group (CG). EG (n= 19) was submitted to gait training on a treadmill with the addition of load to the NPLL by ankle weights equivalent to 5% of body weight. CG (n= 19) was only submitted to gait training on a treadmill. Behavioral strategies which included home exercises were also applied to both groups. The interventions occurred daily for two consecutive weeks (Day 1 to Day 9), being of 30 minutes duration each. Outcome measures: postural balance (Berg Functional Balance Scale – BBS), functional mobility (Timed Up and Go – TUG; kinematic variables of 180° turning) and kinematic gait variables were assessed at baseline (Day 0), after four training sessions (Day 4), after nine training sessions (Day 9), and 40 days after completion of training (Follow-up). Cardiovascular parameters (mean arterial pressure and heart rate) were evaluated at four moments within each training session. Analysis of variance (ANOVA) was used to compare outcomes between EG and CG in the course of the study (Day 0, Day 4, Day 9 and Follow-up). Unpaired t-tests allowed for intergroup comparison at each training session. 5% significance was used for all tests. Results: 1) Cardiovascular parameters (systemic arterial pressure, heart rate and derivated variables) did not change after the interventions and there were no differences between groups within each training session. There was an improvement in gait performance, with increased speed and distance covered, with no statistically significant difference between groups. 2) After the interventions, patients had increased paretic and non-paretic step lengths, in addition to exhibiting greater hip and knee joint excursion on both lower limbs. The gains were observed in the EG and CG, with no statistical difference between the groups and (mostly) maintained at follow-up. 3) After the interventions, patients showed better postural balance (higher scores on BBS) and functional mobility (reduced time spent on the TUG test and better performance on the 180° turning). All gains were observed in the EG and CG, with no statistically significant difference between groups and were maintained at follow-up. Conclusions: The addition of load to the NPLL did not affect cardiovascular parameters in patients with subacute stroke, similar to treadmill training without load, thus seemingly a safe training to be applied to these patients. However, the use of the load did not bring any additional benefits to gait training. The gait training program (nine training sessions on a treadmill + strategies and exercises for paretic limb stimulation) was useful for improving gait performance and kinematics, functional mobility and postural balance, and its use is suggested to promote the optimization of these outcomes in the subacute phase after stroke.

Genetic Abrogation of Adenosine A3 Receptor Prevents Uninephrectomy and High Salt-Induced Hypertension.

BACKGROUND: Early-life reduction in nephron number (uninephrectomy [UNX]) and chronic high salt (HS) intake increase the risk of hypertension and chronic kidney disease. Adenosine signaling via its different receptors has been implicated in modulating renal, cardiovascular, and metabolic functions as well as inflammatory processes; however, the specific role of the A3 receptor in cardiovascular diseases is not clear. In this study, gene-modified mice were used to investigate the hypothesis that lack of A3 signaling prevents the development of hypertension and attenuates renal and cardiovascular injuries following UNX in combination with HS (UNX-HS) in mice. METHODS AND RESULTS: Wild-type (A3 (+/+)) mice subjected to UNX-HS developed hypertension compared with controls (mean arterial pressure 106±3 versus 82±3 mm Hg; P<0.05) and displayed an impaired metabolic phenotype (eg, increased adiposity, reduced glucose tolerance, hyperinsulinemia). These changes were associated with both cardiac hypertrophy and fibrosis together with renal injuries and proteinuria. All of these pathological hallmarks were significantly attenuated in the A3 (-/-) mice. Mechanistically, absence of A3 receptors protected from UNX-HS-associated increase in renal NADPH oxidase activity and Nox2 expression. In addition, circulating cytokines including interleukins 1β, 6, 12, and 10 were increased in A3 (+/+) following UNX-HS, but these cytokines were already elevated in naïve A3 (-/-) mice and did not change following UNX-HS. CONCLUSIONS: Reduction in nephron number combined with chronic HS intake is associated with oxidative stress, chronic inflammation, and development of hypertension in mice. Absence of adenosine A3 receptor signaling was strongly protective in this novel mouse model of renal and cardiovascular disease.

Effet préventif de la milrinone inhalée chez les patients avec hypertension pulmonaire subissant une chirurgie cardiaque sous circulation extracorporelle : une approche pharmacométrique

La circulation extracorporelle (CEC) est une technique utilisée en chirurgie cardiaque effectuée des milliers de fois chaque jour à travers le monde. L’instabilité hémodynamique associée au sevrage de la CEC difficile constitue la principale cause de mortalité en chirurgie cardiaque et l’hypertension pulmonaire (HP) a été identifiée comme un des facteurs de risque les plus importants. Récemment, une hypothèse a été émise suggérant que l'administration prophylactique (avant la CEC) de la milrinone par inhalation puisse avoir un effet préventif et faciliter le sevrage de la CEC chez les patients atteints d’HP. Toutefois, cette indication et voie d'administration pour la milrinone n'ont pas encore été approuvées par les organismes réglementaires. Jusqu'à présent, la recherche clinique sur la milrinone inhalée s’est principalement concentrée sur l’efficacité hémodynamique et l'innocuité chez les patients cardiaques, bien qu’aucun biomarqueur n’ait encore été établi. La dose la plus appropriée pour l’administration par nébulisation n'a pas été déterminée, de même que la caractérisation des profils pharmacocinétiques (PK) et pharmacodynamiques (PD) suite à l'inhalation. L'objectif de notre recherche consistait à caractériser la relation exposition-réponse de la milrinone inhalée administrée chez les patients subissant une chirurgie cardiaque sous CEC. Une méthode analytique par chromatographie liquide à haute performance couplée à un détecteur ultraviolet (HPLC-UV) a été optimisée et validée pour le dosage de la milrinone plasmatique suite à l’inhalation et s’est avérée sensible et précise. La limite de quantification (LLOQ) était de 1.25 ng/ml avec des valeurs de précision intra- et inter-dosage moyennes (CV%) <8%. Des patients souffrant d’HP pour lesquels une chirurgie cardiaque sous CEC était prévue ont d’abord été recrutés pour une étude pilote (n=12) et, par la suite, pour une étude à plus grande échelle (n=28) où la milrinone (5 mg) était administrée par inhalation pré-CEC. Dans l'étude pilote, nous avons comparé l'exposition systémique de la milrinone peu après son administration avec un nébuliseur pneumatique ou un nébuliseur à tamis vibrant. L’efficacité des nébuliseurs en termes de dose émise et dose inhalée a également été déterminée in vitro. Dans l'étude à plus grande échelle conduite en utilisant exclusivement le nébuliseur à tamis vibrant, la dose inhalée in vivo a été estimée et le profil pharmacocinétique de la milrinone inhalée a été pleinement caractérisé aux niveaux plasmatique et urinaire. Le ratio de la pression artérielle moyenne sur la pression artérielle pulmonaire moyenne (PAm/PAPm) a été choisi comme biomarqueur PD. La relation exposition-réponse de la milrinone a été caractérisée pendant la période d'inhalation en étudiant la relation entre l'aire sous la courbe de l’effet (ASCE) et l’aire sous la courbe des concentrations plasmatiques (ASC) de chacun des patients. Enfin, le ratio PAm/PAPm a été exploré comme un prédicteur potentiel de sortie de CEC difficile dans un modèle de régression logistique. Les expériences in vitro ont démontré que les doses émises étaient similaires pour les nébuliseurs pneumatique (64%) et à tamis vibrant (68%). Cependant, la dose inhalée était 2-3 fois supérieure (46% vs 17%) avec le nébuliseur à tamis vibrant, et ce, en accord avec les concentrations plasmatiques. Chez les patients, en raison des variations au niveau des facteurs liés au circuit et au ventilateur causant une plus grande dose expirée, la dose inhalée a été estimée inférieure (30%) et cela a été confirmé après récupération de la dose de milrinone dans l'urine 24 h (26%). Les concentrations plasmatiques maximales (Cmax: 41-189 ng/ml) et l'ampleur de la réponse maximale ΔRmax-R0 (0-65%) ont été observées à la fin de l'inhalation (10-30 min). Les données obtenues suite aux analyses PK sont en accord avec les données publiées pour la milrinone intraveineuse. Après la période d'inhalation, les ASCE individuelles étaient directement reliées aux ASC (P=0.045). Enfin, notre biomarqueur PD ainsi que la durée de CEC ont été identifiés comme des prédicteurs significatifs de la sortie de CEC difficile. La comparaison des ASC et ASCE correspondantes a fourni des données préliminaires supportant une preuve de concept pour l'utilisation du ratio PAm/PAPm comme biomarqueur PD prometteur et justifie de futures études PK/PD. Nous avons pu démontrer que la variation du ratio PAm/PAPm en réponse à la milrinone inhalée contribue à la prévention de la sortie de CEC difficile.

Effet préventif de la milrinone inhalée chez les patients avec hypertension pulmonaire subissant une chirurgie cardiaque sous circulation extracorporelle : une approche pharmacométrique

La circulation extracorporelle (CEC) est une technique utilisée en chirurgie cardiaque effectuée des milliers de fois chaque jour à travers le monde. L’instabilité hémodynamique associée au sevrage de la CEC difficile constitue la principale cause de mortalité en chirurgie cardiaque et l’hypertension pulmonaire (HP) a été identifiée comme un des facteurs de risque les plus importants. Récemment, une hypothèse a été émise suggérant que l'administration prophylactique (avant la CEC) de la milrinone par inhalation puisse avoir un effet préventif et faciliter le sevrage de la CEC chez les patients atteints d’HP. Toutefois, cette indication et voie d'administration pour la milrinone n'ont pas encore été approuvées par les organismes réglementaires. Jusqu'à présent, la recherche clinique sur la milrinone inhalée s’est principalement concentrée sur l’efficacité hémodynamique et l'innocuité chez les patients cardiaques, bien qu’aucun biomarqueur n’ait encore été établi. La dose la plus appropriée pour l’administration par nébulisation n'a pas été déterminée, de même que la caractérisation des profils pharmacocinétiques (PK) et pharmacodynamiques (PD) suite à l'inhalation. L'objectif de notre recherche consistait à caractériser la relation exposition-réponse de la milrinone inhalée administrée chez les patients subissant une chirurgie cardiaque sous CEC. Une méthode analytique par chromatographie liquide à haute performance couplée à un détecteur ultraviolet (HPLC-UV) a été optimisée et validée pour le dosage de la milrinone plasmatique suite à l’inhalation et s’est avérée sensible et précise. La limite de quantification (LLOQ) était de 1.25 ng/ml avec des valeurs de précision intra- et inter-dosage moyennes (CV%) <8%. Des patients souffrant d’HP pour lesquels une chirurgie cardiaque sous CEC était prévue ont d’abord été recrutés pour une étude pilote (n=12) et, par la suite, pour une étude à plus grande échelle (n=28) où la milrinone (5 mg) était administrée par inhalation pré-CEC. Dans l'étude pilote, nous avons comparé l'exposition systémique de la milrinone peu après son administration avec un nébuliseur pneumatique ou un nébuliseur à tamis vibrant. L’efficacité des nébuliseurs en termes de dose émise et dose inhalée a également été déterminée in vitro. Dans l'étude à plus grande échelle conduite en utilisant exclusivement le nébuliseur à tamis vibrant, la dose inhalée in vivo a été estimée et le profil pharmacocinétique de la milrinone inhalée a été pleinement caractérisé aux niveaux plasmatique et urinaire. Le ratio de la pression artérielle moyenne sur la pression artérielle pulmonaire moyenne (PAm/PAPm) a été choisi comme biomarqueur PD. La relation exposition-réponse de la milrinone a été caractérisée pendant la période d'inhalation en étudiant la relation entre l'aire sous la courbe de l’effet (ASCE) et l’aire sous la courbe des concentrations plasmatiques (ASC) de chacun des patients. Enfin, le ratio PAm/PAPm a été exploré comme un prédicteur potentiel de sortie de CEC difficile dans un modèle de régression logistique. Les expériences in vitro ont démontré que les doses émises étaient similaires pour les nébuliseurs pneumatique (64%) et à tamis vibrant (68%). Cependant, la dose inhalée était 2-3 fois supérieure (46% vs 17%) avec le nébuliseur à tamis vibrant, et ce, en accord avec les concentrations plasmatiques. Chez les patients, en raison des variations au niveau des facteurs liés au circuit et au ventilateur causant une plus grande dose expirée, la dose inhalée a été estimée inférieure (30%) et cela a été confirmé après récupération de la dose de milrinone dans l'urine 24 h (26%). Les concentrations plasmatiques maximales (Cmax: 41-189 ng/ml) et l'ampleur de la réponse maximale ΔRmax-R0 (0-65%) ont été observées à la fin de l'inhalation (10-30 min). Les données obtenues suite aux analyses PK sont en accord avec les données publiées pour la milrinone intraveineuse. Après la période d'inhalation, les ASCE individuelles étaient directement reliées aux ASC (P=0.045). Enfin, notre biomarqueur PD ainsi que la durée de CEC ont été identifiés comme des prédicteurs significatifs de la sortie de CEC difficile. La comparaison des ASC et ASCE correspondantes a fourni des données préliminaires supportant une preuve de concept pour l'utilisation du ratio PAm/PAPm comme biomarqueur PD prometteur et justifie de futures études PK/PD. Nous avons pu démontrer que la variation du ratio PAm/PAPm en réponse à la milrinone inhalée contribue à la prévention de la sortie de CEC difficile.

Despertar anestésico con remifentanilo versus sin remifentanilo en los pacientes del Hospital Vicente Corral Moscoso. Cuenca, 2013

OBJETIVO: Comparar el despertar anestésico con remifentanilo y sin remifentanilo en los pacientes sometidos a anestesia general. MATERIAL Y MÉTODOS: Se trata de un estudio clínico aleatorizado simple ciego de 140 pacientes sometidos a anestesia general balanceada. Se dividieron en dos grupos iguales, al grupo A (n=70) se le retiró el remifentanilo 10 minutos antes y el grupo B (n=70) recibió remifentanilo en infusión continua a dosis de 0.05 ug/kg/min hasta la extubación. RESULTADOS: Las variables edad, peso, talla, presión arterial media y frecuencia cardíaca basales entre ambos grupos no tuvieron diferencias estadísticamente significativas, con una p>0.05. En el grupo “A” durante el despertar anestésico, la presión arterial media en la extubación y 5 minutos después fueron mayores con respecto al grupo “B”, con una diferencia estadísticamente significativa (p=0.009 y p=0.01). La náusea fue el efecto adverso que presentó diferencia significativa en el grupo que recibió remifentanilo, con una p=0.023. El grupo que presentó con más frecuencia y más intensidad la tos fue el grupo “A”, con una p=0.047 y p=0.005 respectivamente. En cuanto a la frecuencia cardíaca y al tiempo del despertar no tuvieron diferencia en los grupos. CONCLUSIONES: El grupo que recibió remifentanilo tuvo una menor presión arterial media, frecuencia e intensidad de la tos, que el grupo que no recibió remifentanilo, con igual tiempo en el despertar y escasos efectos adversos

Renal and vascular effects of the natriuretic peptide isolated from Crotalus durissus cascavella venom

Crotalus durissus cascavella is a snake that is usually found in the scrublands of northeast Brazil. The components of its venom may have effects on the vascular and renal systems. Recently, a new bradykinin inhibitory peptide has been identified in the venom of the Crotalinae family. The aim of the present study was to investigate the renal and vascular effects of the natriuretic peptide isolated from the venom of Crotalus durissus cascavella (NP2_Casca). The chromatographic profile showed the fractionation of substances identified as convulxin, gyroxin, crotoxin and crotamine, as well as fractions V and VI. The electrophoretic profile of fraction V consisted of several bands ranging from approximately 6 kDa to 13 kDa, while fraction VI showed only two main electrophoretic bands with molecular weights of approximately 6 and 14 kDa. Reverse-phase chromatography showed that NP2_Casca corresponds to about 18% of fraction VI and that this fraction is the main natriuretic peptide. NP2_Casca was compared to other natriuretic peptides from other sources of snake venom. All amino acid sequences that were compared showed a consensus region of XGCFGX, XLDRIX and XSGLGCX. The group treated with NP2-Casca showed an increase in perfusion pressure, renal vascular resistance, urinary flow and glomerular filtration rate. The percent of total and proximal tubular transport of sodium was reduced significantly after administration of the peptide. The mean arterial pressure showed a dose-dependent decrease after infusion of NP2_Casca, and an increase in nitrite production. In the aortic ring assay, NP2_Casca caused a relaxant effect in endothelium-intact thoracic aortic rings precontracted with phenylephrine in the presence and absence of isatin. NP2_Casca failed to relax the aortic rings precontracted with an isosmotic potassium Krebs-Henseleit solution. In conclusion, the natriuretic peptide isolated from Crotalus durissus cascavella venom produced renal and vascular effects. NP2_Casca reduced total and proximal sodium tubular transport, leading to an increase in sodium excretion, thereby demonstrating a diuretic action. A hypotensive effect was displayed in an arterial pressure assay, with an increase in nitrite production, suggesting a possible vasoactive action. (C) 2008 Elsevier Ltd. All rights reserved.

Renal and cardiovascular effects of Bothrops marajoensis venom and phospholipase A(2)

Bothrops marajoensis is found in the savannah of Marajo Island in the State of Par S and regions of Amapa State, Brazil. The aim of the work was to study the renal and cardiovascular effects of the B. marajoensis venom and phospholipase A(2) (PLA(2)). The venom was fractionated by Protein Pack 5PW. N-terminal amino acid sequencing of sPLA(2) showed amino acid identity with other lysine K49sPLA(2)s of snake venom. B. marajoensis venom (30 mu g/mL) decreased the perfusion pressure, renal vascular resistance, urinary flow, glomerular filtration rate and sodium tubular transport. PLA(2) did not change the renal parameters. The perfusion pressure of the mesenteric bed did not change after infusion of venom. In isolated heart, the venom decreased the force of contraction and increased PP but did not change coronary flow. In the arterial pressure, the venom and PLA(2) decreased mean arterial pressure and cardiac frequency. The presence of atrial flutter and late hyperpolarisation reversed, indicating QRS complex arrhythmia and dysfunction in atrial conduction. In conclusion, B. marajoensis venom and PLA(2) induce hypotension and bradycardia while simultaneously blocking electrical conduction in the heart. Moreover, the decrease in glomerular filtration rate, urinary flow and electrolyte transport demonstrates physiological changes to the renal system. (C) 2009 Elsevier Ltd. All rights reserved.

Caracterização da variação do índice de resistência renal e o seu potencial papel como fator de diagnóstico precoce na doença renal em Felis catus

Dissertação de Mestrado Integrado em Medicina Veterinária

Persistent Truncus Arteriosus With Intact Ventricular Septum: Clinical, Hemodynamic and Short-term Surgical Outcome

Introduction: Truncus arteriosus with intact ventricular septum is a rare and unique variant of persistent truncus arteriosus (PTA) which usually presents with central cyanosis and congestive heart failure in neonate and early infancy. Associated cardiac and non-cardiac anomalies may affect morbidity and mortality of these patients. Case Presentation: We describe clinical presentation, echocardiography and angiographic features of a 7-month old boy with PTA and intact ventricular septum who underwent surgical repair of the anomaly at our institution. Operative findings, surgical procedure and short-term outcome are reported. Conclusions: While our patient had systemic pulmonary arterial pressure at the time of complete surgical repair, it was improved after surgery.

Inhibition of nitro-oxidative stress attenuates pulmonary and systemic injury induced by high-tidal volume mechanical ventilation

Mechanisms contributing to pulmonary and systemic injury induced by high tidal volume (VT) mechanical ventilation are not well known. We tested the hypothesis that increased peroxynitrite formation is involved in organ injury and dysfunction induced by mechanical ventilation. Male Sprague-Dawley rats were subject to low- (VT, 9 mL/kg; positive end-expiratory pressure, 5 cmH2O) or high- (VT, 25 mL/kg; positive end-expiratory pressure, 0 cmH2O) VT mechanical ventilation for 120 min, and received 1 of 3 treatments: 3-aminobenzamide (3-AB, 10 mg/kg, intravenous, a poly adenosine diphosphate ribose polymerase [PARP] inhibitor), or the metalloporphyrin manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP, 5 mg/kg intravenous, a peroxynitrite scavenger), or no treatment (control group), 30 min before starting the mechanical ventilation protocol (n = 8 per group, 6 treatment groups). We measured mean arterial pressure, peak inspiratory airway pressure, blood chemistry, and gas exchange. Oxidation (fluorescence for oxidized dihydroethidium), protein nitration (immunofluorescence and Western blot for 3-nitrotyrosine), PARP protein (Western blot) and gene expression of the nitric oxide (NO) synthase (NOS) isoforms (quantitative real-time reverse transcription polymerase chain reaction) were measured in lung and vascular tissue. Lung injury was quantified by light microscopy. High-VT mechanical ventilation was associated with hypotension, increased peak inspiratory airway pressure, worsened oxygenation; oxidation and protein nitration in lung and aortic tissue; increased PARP protein in lung; up-regulation of NOS isoforms in lung tissue; signs of diffuse alveolar damage at histological examination. Treatment with 3AB or MnTMPyP attenuated the high-VT mechanical ventilation-induced changes in pulmonary and cardiovascular function; down-regulated the expression of NOS1, NOS2, and NOS3; decreased oxidation and nitration in lung and aortic tissue; and attenuated histological changes. Increased peroxynitrite formation is involved in mechanical ventilation-induced pulmonary and vascular dysfunction.

Role of the human chymase (CMA1) in the conversion of big-endothelin-1 to endothelin-1 (1-31)

Abstract : The chymase-dependant pathway responsible for converting Big ET-1 to ET-1 was established in vitro. It has only been recently, in 2009, that our group demonstrated that the conversion of Big ET-1 to ET-1 (1-31) can occur in vivo in mice (Simard et al., 2009), knowing that ET-1 (1-31) is converted to ET-1 via NEP in vivo (Fecteau et al., 2005). In addition, our laboratory demonstrated in 2013 that mMCP-4, the murine analogue of human chymase, produces ET-1 (1-31) from the Big ET-1 precursor (Houde et al. 2013). Thus far, in the literature, there are no specific characterizations of recombinant chymases (human or murine). In fact, the group of Murakami published in 1995 a study characterizing the CMA1 (human chymase) in a chymostatin-dependent fashion, using Angiotensin I as a substrate (Murakami et al., 1995). However, chymostatin is a non-specific inhibitor of chymase. It has been shown that chymostatin can inhibit elastase, an enzyme that can convert Angiotensin I to Angiotensin II (Becari et al., 2005). Based on these observations, the proposed hypothesis in the present study suggests that recombinant as well as extracted CMA1 from LUVA (human mast cell line), in addition to soluble fractions of human aortas, convert Big ET-1 into ET-1 (1-31 ) in a TY-51469 (a chymase-specific inhibitor) sensitive manner. In a second component, we studied the enzyme kinetics of CMA1 with regard to the Big ET-1 and Ang I substrate. The affinity of CMA1 against Big ET-1 was greater compared to Ang I (KM Big ET- 1: 12.55 μM and Ang I: 37.53 μM). However, CMA1 was more effective in cleaving Ang I compared to Big ET-1 (Kcat / KM Big ET-1: 6.57 x 10-5 μM-1.s-1 and Ang I: 1.8 x 10-4 ΜM-1.s- 1). In a third component involving in vivo experiments, the pressor effects of Big ET-1, ET-1 and Ang I were tested in conscious mMCP-4 KO mice compared to wild-type mice. The increase in mean arterial pressure after administration of Big ET-1 was greater in wild-type mice compared to mMCP- 4 KO mice. This effect was not observed after administration of ET-1 and / or Ang I.