International survey of acute stroke imaging used to make revascularization treatment decisions.

BACKGROUND: To assess the differences across continental regions in terms of stroke imaging obtained for making acute revascularization therapy decisions, and to identify obstacles to participating in randomized trials involving multimodal imaging. METHODS: STroke Imaging Repository (STIR) and Virtual International Stroke Trials Archive (VISTA)-Imaging circulated an online survey through its website, through the websites of national professional societies from multiple countries as well as through email distribution lists from STIR and the above mentioned societies. RESULTS: We received responses from 223 centers (2 from Africa, 38 from Asia, 10 from Australia, 101 from Europe, 4 from Middle East, 55 from North America, 13 from South America). In combination, the sites surveyed administered acute revascularization therapy to a total of 25,326 acute stroke patients in 2012. Seventy-three percent of these patients received intravenous (i.v.) tissue plasminogen activator (tPA), and 27%, endovascular therapy. Vascular imaging was routinely obtained in 79% (152/193) of sites for endovascular therapy decisions, and also as part of standard IV tPA treatment decisions at 46% (92/198) of sites. Modality, availability and use of acute vascular and perfusion imaging before revascularization varied substantially between geographical areas. The main obstacles to participate in randomized trials involving multimodal imaging included: mainly insufficient research support and staff (50%, 79/158) and infrequent use of multimodal imaging (27%, 43/158) . CONCLUSION: There were significant variations among sites and geographical areas in terms of stroke imaging work-up used tomake decisions both for intravenous and endovascular revascularization. Clinical trials using advanced imaging as a selection tool for acute revascularization therapy should address the need for additional resources and technical support, and take into consideration the lack of routine use of such techniques in trial planning.

Pilot study about the effect of rt-PA administration on the excitotoxicity mediated brain damage and its repercussion on the functional prognosis of patients with ischaemic stroke: research protocol

Fibrinolytic therapy with Recombinant Tissue-Plasminogen Activator (rt-PA) is currently the only effective treatment for ischaemic stroke in its acute phase. Even though its use generally improves the prognosis of those patients likely to receive it, rt-PA administration is associated to several risks, such as haemorrhagic transformation ofthe ischaemic lesion and activation of excitotoxic mechanisms that may contribute to an increase in mortality or to a poor outcome in certain occasions, specially when arterial recanalization is not achieved or the rt-PA is lately administrated. Since in the last few years the role of glutamate in the neurotoxicity associated toischaemia has been widely studied and it is known that high plasma glutamate levels are predictors of ischaemic lesion growth and poor neurological outcome, it is necessary to find out which factors can contribute to glutamate release in the brain. The aim of this study is to determine if rt-PA administration is related to an increase in plasma glutamate levels, as well as to define if higher plasma glutamate levels at admission are related to different evolution and prognosis of our patients, both in those in which recanalisation is achieved and not. A series of cases of patients with hemispheric cerebral infarction admitted in our hospital during a year will be studied, and the data obtained from them will be compared to the data obtained from a control group, the samples of wich were takenyears ago, before rt-PA was routinely used

Cloning, expression and purification of recombinant streptokinase: partial characterization of the protein expressed in Escherichia coli

We cloned the streptokinase (STK) gene of Streptococcus equisimilis in an expression vector of Escherichia coli to overexpress the profibrinolytic protein under the control of a tac promoter. Almost all the recombinant STK was exported to the periplasmic space and recovered after gentle lysozyme digestion of induced cells. The periplasmic fraction was chromatographed on DEAE Sepharose followed by chromatography on phenyl-agarose. Active proteins eluted between 4.5 and 0% ammonium sulfate, when a linear gradient was applied. Three major STK derivatives of 47.5 kDa, 45 kDa and 32 kDa were detected by Western blot analysis with a polyclonal antibody. The 32-kDa protein formed a complex with human plasminogen but did not exhibit Glu-plasminogen activator activity, as revealed by a zymographic assay, whereas the 45-kDa protein showed a Km = 0.70 µM and kcat = 0.82 s-1, when assayed with a chromogen-coupled substrate. These results suggest that these proteins are putative fragments of STK, possibly derived from partial degradation during the export pathway or the purification steps. The 47.5-kDa band corresponded to the native STK, as revealed by peptide sequencing

Rosuvastatin and vascular dysfunction markers in pulmonary arterial hypertension: a placebo-controlled study

We investigated whether chronic rosuvastatin administration could improve the abnormalities of the circulating levels of vascular dysfunction markers in pulmonary arterial hypertension (PAH). Sixty patients, aged 13 to 60 years, with idiopathic (N = 14) or congenital heart disease-associated PAH (N = 46) were equally but randomly assigned to rosuvastatin treatment (10 mg a day, orally) or placebo for 6 months in a blind fashion. Plasma levels of P-selectin, tissue-plasminogen activator and its inhibitor as well as von Willebrand factor antigen were measured by enzyme-linked immunoassay before and after 1, 3, and 6 months of treatment. Baseline levels of biomarkers were elevated (68, 16, 45 and 46% increase relative to controls, for P-selectin, von Willebrand factor antigen, tissue-plasminogen activator and its inhibitor, respectively; P < 0.001). P-selectin values at baseline, 1, 3, and 6 months were 39.9 ± 18.5, 37.6 ± 14.6, 34.8 ± 14.6, and 35.4 ± 13.9 ng/mL, respectively, for the rosuvastatin group and 45.7 ± 26.8, 48.0 ± 26.9, 48.1 ± 25.7, and 45.7 ± 25.6 ng/mL for the placebo group. The P-selectin level was lower in the rosuvastatin group compared with placebo throughout treatment (P = 0.037, general linear model). A trend was observed towards a decrease in tissue-plasminogen activator in the statin group (16% reduction, P = 0.094), with no significant changes in the other markers. Since P-selectin is crucial in inflammation and thrombosis, its reduction by rosuvastatin is potentially relevant in the pathophysiological scenario of PAH.

Texture analysis of computed tomography images of acute ischemic stroke patients

Computed tomography (CT) images are routinely used to assess ischemic brain stroke in the acute phase. They can provide important clues about whether to treat the patient by thrombolysis with tissue plasminogen activator. However, in the acute phase, the lesions may be difficult to detect in the images using standard visual analysis. The objective of the present study was to determine if texture analysis techniques applied to CT images of stroke patients could differentiate between normal tissue and affected areas that usually go unperceived under visual analysis. We performed a pilot study in which texture analysis, based on the gray level co-occurrence matrix, was applied to the CT brain images of 5 patients and of 5 control subjects and the results were compared by discriminant analysis. Thirteen regions of interest, regarding areas that may be potentially affected by ischemic stroke, were selected for calculation of texture parameters. All regions of interest for all subjects were classified as lesional or non-lesional tissue by an expert neuroradiologist. Visual assessment of the discriminant analysis graphs showed differences in the values of texture parameters between patients and controls, and also between texture parameters for lesional and non-lesional tissue of the patients. This suggests that texture analysis can indeed be a useful tool to help neurologists in the early assessment of ischemic stroke and quantification of the extent of the affected areas.

The effect of thyroid hormones on the white adipose tissue gene expression of PAI-1 and its serum concentration

Metabolic syndrome is associated with an increased risk of developing cardiovascular diseases and Plasminogen activator inhibitor 1 (PAI-1) overexpression may play a significant role in this process. A positive correlation between adipose tissue gene expression of PAI-1 and its serum concentration has been reported. Furthermore, high serum levels of thyroid hormones (T3 and T4) and PAI-1 have been observed in obese children. The present study evaluates the impact of thyroid hormone treatment on white adipose tissue PAI-1 gene expression and its serum concentration. Male Wistar rats (60 days old) were treated for three weeks with T4 (50 µg/day, Hyper) or with saline (control). Additionally, 3T3-L1 adipocytes were treated for 24 h with T4 (100 nM) or T3 (100 nM). PAI-1 gene expression was determined by real-time PCR, while the serum concentration of PAI-1 was measured by ELISA using a commercial kit (Innovative Research, USA). Both the serum concentration of PAI-1 and mRNA levels were similar between groups in retroperitoneal and epididymal white adipose tissue. Using 3T3-L1 adipocytes, in vitro treatment with T4 and T3 increased the gene expression of PAI-1, suggesting non-genomic and genomic effects, respectively. These results demonstrate that thyroid hormones have different effects in vitro and in vivo on PAI-1 gene expression in adipocytes.

Plasma von Willebrand factor as a predictor of survival in pulmonary arterial hypertension associated with congenital heart disease

Biomarkers have been identified for pulmonary arterial hypertension, but are less well defined for specific etiologies such as congenital heart disease-associated pulmonary arterial hypertension (CHDPAH). We measured plasma levels of eight microvascular dysfunction markers in CHDPAH, and tested for associations with survival. A cohort of 46 inoperable CHDPAH patients (age 15.0 to 60.2 years, median 33.5 years, female:male 29:17) was prospectively followed for 0.7 to 4.0 years (median 3.6 years). Plasma levels of von Willebrand factor antigen (VWF:Ag), tissue plasminogen activator (t-PA) and its inhibitor (PAI-1), P-selectin, reactive C-protein, tumor necrosis factor alpha, and interleukin-6 and -10 were measured at baseline, and at 30, 90, and 180 days in all subjects. Levels of six of the eight proteins were significantly increased in patients versus controls (13 to 106% increase, P < 0.003). Interleukin-10 level was 2.06 times normal (P = 0.0003; Th2 cytokine response). Increased levels of four proteins (t-PA, PAI-1, P-selectin, and interleukin-6) correlated with disease severity indices (P < 0.05). Seven patients died during follow-up. An average VWF:Ag (mean of four determinations) above the level corresponding to the 95th percentile of controls (139 U/dL) was independently associated with a high risk of death (hazard ratio = 6.56, 95%CI = 1.46 to 29.4, P = 0.014). Thus, in CHDPAH, microvascular dysfunction appears to involve Th2 inflammatory response. Of the biomarkers studied, plasma vWF:Ag was independently associated with survival.

Morphometric evaluation of nitric oxide synthase isoforms and their cytokine regulators predict pulmonary dysfunction and survival in systemic sclerosis

Because histopathological changes in the lungs of patients with systemic sclerosis (SSc) are consistent with alveolar and vessel cell damage, we presume that this interaction can be characterized by analyzing the expression of proteins regulating nitric oxide (NO) and plasminogen activator inhibitor-1 (PAI-1) synthesis. To validate the importance of alveolar-vascular interactions and to explore the quantitative relationship between these factors and other clinical data, we studied these markers in 23 cases of SSc nonspecific interstitial pneumonia (SSc-NSIP). We used immunohistochemistry and morphometry to evaluate the amount of cells in alveolar septa and vessels staining for NO synthase (NOS) and PAI-1, and the outcomes of our study were cellular and fibrotic NSIP, pulmonary function tests, and survival time until death. General linear model analysis demonstrated that staining for septal inducible NOS (iNOS) related significantly to staining of septal cells for interleukin (IL)-4 and to septal IL-13. In univariate analysis, higher levels of septal and vascular cells staining for iNOS were associated with a smaller percentage of septal and vascular cells expressing fibroblast growth factor and myofibroblast proliferation, respectively. Multivariate Cox model analysis demonstrated that, after controlling for SSc-NSIP histological patterns, just three variables were significantly associated with survival time: septal iNOS (P=0.04), septal IL-13 (P=0.03), and septal basic fibroblast growth factor (bFGF; P=0.02). Augmented NOS, IL-13, and bFGF in SSc-NSIP histological patterns suggest a possible functional role for iNOS in SSc. In addition, the extent of iNOS, PAI-1, and IL-4 staining in alveolar septa and vessels provides a possible independent diagnostic measure for the degree of pulmonary dysfunction and fibrosis with an impact on the survival of patients with SSc.

Rôle du système rénine-angiotensine intrarénal dans l’hypertension et les dommages rénaux chez les souris transgéniques diabétiques

Plusieurs expériences et études cliniques ont démontré que l’activation du système rénine-angiotensine (RAS) peut induire l’hypertension, un facteur de risque majeur pour les maladies cardiovasculaires et rénales. L’angiotensinogène (Agt) est l’unique substrat du RAS. Cependant, il n’a pas encore été démontré si l’activation du RAS intrarénal peut à elle seule induire des dommages rénaux, indépendamment de l’hypertension systémique, et ainsi jouer un rôle prépondérant dans la progression de la néphropathie diabétique. Afin d’explorer le rôle du RAS intrarénal dans les dommages rénaux, un diabète a été induit par l’injection de streptozotocin chez des souris transgéniques (Tg) surexprimant l’Agt de rat dans les cellules des tubules proximaux du rein (RPTC). Les souris Tg diabétiques ont été traitées soit avec des inhibiteurs du RAS (perindopril et losartan), de l’insuline ou une combinaison des deux pour 4 semaines avant d’être euthanasiées. Pour une autre étude, des souris Tg non-diabétiques ont été traitées soit avec des inhibiteurs du RAS, l’hydralazine (vasodilatateur) ou l’apocynine (inhibiteur de la NADPH oxydase) pour une période de 8 semaines avant l’euthanasie. Des souris non-Tg ont été utilisées comme contrôles. Des cellules immortalisées de tubule proximal de rat (IRPTC) transfectées de manière stable avec un plasmide contenant l’Agt ou un plasmide contrôle ont été employées comme modèle in vitro. Nos résultats ont démontré que les souris Tg présentaient une augmentation significative de la pression systolique, l’albuminurie, l’apoptose des RPTC et l’expression de gènes pro-apoptotiques par rapport aux souris non-Tg. Les mêmes changements ont été observés chez les souris Tg diabétiques par rapport aux souris non-Tg diabétiques. L’insuline et/ou les inhibiteurs du RAS ont permis d’atténuer ces changements, sauf l’hypertension qui n’était réduite que par les inhibiteurs du RAS. Chez les IRPTC transfectées avec l’Agt in vitro, les hautes concentrations de glucose augmentent l’apoptose et l’activité de la caspase-3 par rapport aux cellules contrôles et l’insuline et/ou les inhibiteurs du RAS empêchent ces augmentations. En plus des changements physiologiques, les RPTC des souris Tg présentent aussi une augmentation significative de la production des espèces réactive de l’oxygène (ROS) et de l’activité de la NADPH oxydase, ainsi qu’une augmentation de l’expression du facteur de croissance transformant-beta 1 (TGF-β1), de l’inhibiteur activateur du plasminogène de type 1 (PAI-1), des protéines de la matrice extracellulaire, du collagène de type IV et de la sousunité p47 de la NADPH oxydase. Le traitement des souris Tg avec l’apocynine et le perindopril a permis d’améliorer tous ces changements, sauf l’hypertension qui n’était pas corrigée par l’apocynine. D’autre part, l’hydralazine a prévenu l’hypertension, sans modifier l’albuminurie, l’apoptose des RPTC ou l’expression des gènes pro-apoptotiques. Ces résultats montrent bien que l’activation du RAS intrarénal et l’hyperglycémie agissent de concert pour induire l’albuminurie et l’apoptose des RPTC, indépendamment de l’hypertension systémique. La génération des ROS via l’activation de la NADPH oxydase induit en partie l’action du RAS intrarénal sur l’apoptose des RPTC, la fibrose tubulo-interstitielle et l’albuminurie chez les souris Tg. D’autre part, une expérience en cours a tenté d’encore mieux délimiter les effets de l’activation du RAS intrarénal, tout en éliminant la néphrotoxicité du STZ. Pour cette étude, les souris Tg surexprimant l’Agt de rat dans leurs RPTC ont été croisées aux souris Ins2Akita, un modèle spontané de diabète de type I, afin de générer des souris Akita-rAgt-Tg. Les résultats préliminaires indiquent que le RAS intrarénal est activé dans les souris Akita et que la combinaison avec l’hyperglycémie induit du stress du réticulum endoplasmique (ER) dans les RPTC in vivo. Le stress du ER contribue à l’apoptose des RPTC observée dans le diabète, à tout le moins dans le modèle Akita. Le traitement avec des inhibiteurs du RAS permet d’atténuer certains des dommanges rénaux observés dans les souris Akita-rAgt-Tg.

Comparación de la severidad y extensión de la enfermedad coronaria multivaso por Syntax Score en una poblaciòn de las Antillas Holandesas vs controles nacionales

En la Enfermedad Coronaria (EC) existen factores genéticos, socioculturales, medioambientales y raciales adicionales a los factores de riesgo cardiovascular mayores que podrían influir en su presentación. Se desconoce el impacto de la raza en la severidad de la enfermedad coronaria en los pacientes extranjeros que son enviados a nuestro Servicio. Objetivos: Comparar la severidad de la EC multivaso en una población de pacientes de las Antillas y Nacionales, pareados por la escala Framingham. Metodología: Realizamos un estudio de corte transversal, comparando pacientes colombianos contra pacientes provenientes de las Antillas holandesas con similares factores de riesgo según escala de Framingham, catalogándolos por grupos de riesgo bajo, intermedio, alto y muy alto. Todos con EC severa multivaso documentada por angiografía coronaria desde enero del 2009 hasta Junio de 2011. Se excluyeron pacientes con antecedentes de intervención percutánea o quirúrgica previa. Resultados: Ingresaron 115 pacientes internacionales y 115 pacientes nacionales. La relación hombres/mujeres 3:1. La proporción de grupos de riesgo fue de bajo riesgo 2.5%, intermedio 15%, alto 19.3%, y muy alto 63.4%. El Syntax Score en pacientes nacionales fue 14.3+/-7.4 y en internacionales 22.2+/-10.5 p: 0.002. Conclusiones: En pacientes provenientes de las Antillas Holandesas, valorados en nuestra institución, se observó una mayor severidad de la enfermedad coronaria comparada con una población nacional con factores de riesgo similares. Estos hallazgos sugieren la influencia de la raza y factores genéticos en la severidad y extensión de la EC

Causas de no trombolisis en ataque cerebrovascular

Introducción. El ataque cerebrovascular (ACV) ocupa el primer lugar en frecuencia entre todas las enfermedades neurológicas de la vida adulta, y el tercer lugar como causa más frecuente de muerte. Se aprobó para el manejo agudo, la terapia con activador del plasminógeno tisular recombinante (t-PA) en las primeras 4,5 horas después del inicio de los síntomas, demostrando mayor sobrevida y menos niveles de discapacidad. Sin embargo solo el 5-10% de pacientes reciben este manejo. Por estas razones es necesario conocer que factores se asocian con la no intervención terapéutica. Objetivo. Describir los factores asociados con la no trombolisis en pacientes con ataque cerebrovascular en un hospital de IV nivel en Bogotá, Colombia. Métodos. Estudio analítico de corte transversal, en un centro de cuarto nivel en Bogotá entre enero de 2009 y enero de 2011. Resultados. Se encontraron 178 pacientes en un promedio de edad de 65,9 años (DE± 10 años) con una relación hombre-mujer 1:1, la principal causa de no trombolisis fue la ventana mayor a 4.5 horas, 33,7% (n=60), 26,4% por cambios en imágenes diagnosticas, y 14% por puntajes leves o severos en las escala National Institute of Health Stroke Scale (NIHSS), historia quirúrgica 7.3% y laboratorios 4.5%. El tiempo promedio de atención fue 23 minutos (DE ± 21 min) para la activación del código de ACV, 39 minutos para valoración por neurología (DE ± 25 min), 46 minutos (DE ± 19,1 min) para toma de paraclínicos, 66 minutos para toma de imágenes y 97 minutos para trombolisis (DE ± 21min, DE ± 17 min, respectivamente). Se realizó trombolisis en 17 pacientes, 9,6%. No se encontró asociación significativa entre cultura de organización con trombolisis ni de tiempos de atención con trombolisis. Conclusiones. La principal razón de no trombolisis, fue la ventana mayor a 4.5 horas, no se encontró relación entre cultura de organización institucional con trombolisis. El tiempo promedio de trombolisis fue de 90 minutos. Deben instaurarse medidas para reducir el tiempo de llegada al hospital, y los tiempos de atención en urgencias. Deben realizarse nuevas evaluaciones del código ACV posterior a las estrategias de mejoría.

Búsqueda de selección en el polimorfismo 677C>T (c.665C>T) del gen de la metilentetrahidrofolato reductasa (MTHFR) en una población Colombiana

Se realizó un estudio genético – poblacional en dos grupos etarios de población colombiana con la finalidad de evaluar las diferencias genéticas relacionadas con el polimorfismo MTHFR 677CT en busca de eventos genéticos que soporten la persistencia de este polimorfismo en la especie humana debido que este ha sido asociado con múltiples enfermedades. De esta manera se genotipificaron los individuos, se analizaron los genotipos, frecuencias alélicas y se realizaron diferentes pruebas genéticas-poblacionales. Contrario a lo observado en poblaciones Colombianas revisadas se identificó la ausencia del Equilibrio Hardy-Weinberg en el grupo de los niños y estructuras poblacionales entre los adultos lo que sugiere diferentes historias demográficas y culturales entre estos dos grupos poblacionales al tiempo, lo que soporta la hipótesis de un evento de selección sobre el polimorfismo en nuestra población. De igual manera nuestros datos fueron analizados junto con estudios previos a nivel nacional y mundial lo cual sustenta que el posible evento selectivo es debido a que el aporte de ácido fólico se ha incrementado durante las últimas dos décadas como consecuencia de las campañas de fortificación de las harinas y suplementación a las embarazadas con ácido fólico, por lo tanto aquí se propone un modelo de selección que se ajusta a los datos encontrados en este trabajo se establece una relación entre los patrones nutricionales de la especie humana a través de la historia que explica las diferencias en frecuencias de este polimorfismo a nivel espacial y temporal.  

Evaluation of a sequential global test of improved recovery following stroke as applied to the ICTUS trial of citicoline

The International Citicoline Trial in acUte Stroke is a sequential phase III study of the use of the drug citicoline in the treatment of acute ischaemic stroke, which was initiated in 2006 in 56 treatment centres. The primary objective of the trial is to demonstrate improved recovery of patients randomized to citicoline relative to those randomized to placebo after 12 weeks of follow-up. The primary analysis will take the form of a global test combining the dichotomized results of assessments on three well-established scales: the Barthel Index, the modified Rankin scale and the National Institutes of Health Stroke Scale. This approach was previously used in the analysis of the influential National Institute of Neurological Disorders and Stroke trial of recombinant tissue plasminogen activator in stroke. The purpose of this paper is to describe how this trial was designed, and in particular how the simultaneous objectives of taking into account three assessment scales, performing a series of interim analyses and conducting treatment allocation and adjusting the analyses to account for prognostic factors, including more than 50 treatment centres, were addressed. Copyright (C) 2008 John Wiley & Sons, Ltd.

Long-term monounsaturated fatty acid diets reduce platelet aggregation in healthy young subjects

The aim of the present study was to compare the response of a range of atherogenic and thrombogenic risk markers to two dietary levels of saturated fatty acid (SFA) substitution with monounsaturated fatty acids (MUFA) in students living in a university hall of residence. Although the benefits of such diets have been reported for plasma lipoproteins in high-risk groups, more needs to be known about effects of more modest SFA-MUFA substitutions over the long term and in young healthy adults. In a parallel design over 16 weeks, fifty-one healthy young subjects were randomised to one of two diets: (1) a moderate-MUFA diet in which 16 g dietary SFA/100 g total fatty acids were substituted with MUFA (n 25); (2) a high-MUFA diet in which 33 g dietary SFA/100 g total fatty acids were substituted with MUFA (n 26). All subjects followed an 8-week run-in diet (reference diet), with a fatty acid composition close to the UK average values. There were no differences in plasma lipid responses between the two diets over 16 weeks of the study with similar reductions in total cholesterol (P<0.001) and LDL-cholesterol (P<0.01) in both groups; a small but significant reduction in HDL-cholesterol was also observed in both groups (P<0.01). Platelet responses to ADP (P<0.01) and arachidonic acid (P<0.05) differed with time on the two diets; at 16 weeks, platelet aggregatory response to ADP was significantly lower on the high-MUFA than the moderate-MUFA (P<0.01) diet; ADP responses were also significantly lower within this group at 8 (P< 0.05) and 16 (P< 0.01) weeks compared with baseline. There were no differences in fasting factor VII activity (factors VIII and VIIag), fibrinogen concentration or tissue-type plasminogen activator activity between the diets. There were no differences in postprandial factor VIII responses to a standard meal (area under the curve) between the diets after 16 weeks, but postprandial factor VIII response was lower than on the high-MUFA diet compared with baseline (P<0.01). In conclusion, a high-MUFA diet sustains potentially beneficial effects on platelet aggregation and postprandial activation of factor VII. Moderate or high substitution of MUFA for SFA achieves similar reductions in fasting blood lipids in young healthy subjects.