Scorpion envenoming in two regions of Colombia: clinical, epidemiological and therapeutic aspects.

To determine clinical and epidemiological features of scorpion stings in two departments of Colombia, a descriptive study was performed in the hospitals of 10 towns from Antioquia (2 256 071 inhabitants) and five from Tolima (630 424 inhabitants). One hundred and twenty-nine cases were admitted during one year, 51 in Antioquia, 78 in Tolima and 41 were children less than 15 years old. Most stings (70.5%) occurred inside the house; 27.9% were on the hands and 26.4% on the feet. The scorpion species involved were Tityus pachyurus (51), Centruroides gracilis (31), T. fuehrmanni (29), T. asthenes (7) and Chactas spp. (1). In 10 cases the scorpion involved was not identified. Systemic envenoming signs (e.g. vomiting, tachypnea) were significantly more frequent in children than in adults (P < 0.05). Four children had hypertension, but none developed pulmonary oedema. One 3-year-old girl, stung by T. asthenes, had acute oedematous pancreatitis. Ninety-eight patients had mild envenoming. Moderate (27 patients) and severe (four patients) envenoming was significantly more frequent in children than in adults (P = 0.003; relative risk = 2.97). A pepsin-digested anti-Centruroides spp. antivenom was administered to 19 of 31 patients presenting systemic envenoming signs. No adverse reactions to antivenom were observed.

Blood thrombogenicity in type 2 diabetes mellitus patients is associated with glycemic control.

OBJECTIVES: This study was designed to determine whether blood thrombogenicity is related to chronic glycemic control in type 2 diabetes mellitus (T2DM). BACKGROUND: Type 2 diabetes mellitus is associated with accelerated atherosclerosis and a high rate of arterial thrombotic complications. Whether increased blood thrombogenicity is associated with glycemic control has not been properly tested. METHODS: Forty patients with T2DM with hemoglobin A1c (HbA1c) > or =7.5% were selected. Maintaining their current hypoglycemic therapies, patients were randomized into a conservative (diet modification plus placebo) or intensive (diet modification plus troglitazone) hypoglycemic regimen for three months. Blood thrombogenicity was measured at baseline and after three months with the Badimon ex vivo perfusion chamber and assessed as platelet-thrombus formation. The repeated measurements allowed every patient to be his/her own control. RESULTS: Patients in both groups (48% and 74% of the conservative and intensive groups, respectively) improved glucose control (HbA1c reduction > or =0.5%), showing a significant decrease in blood thrombogenicity. A significant positive correlation was observed between the reduction in thrombus formation and the reduction in HbA1c (r = 0.47, p < 0.01). The reduction in HbA1c achieved by both treatments was comparable. Patients without glycemic improvement showed no change in blood thrombogenicity. Improved glycemic control was the only significant predictor of a decrease in blood thrombogenicity. CONCLUSIONS: In T2DM, there is an association between improved glycemic control and blood thrombogenicity reduction. The effect of glycemic control on the thrombotic complications of T2DM patients deserves further investigation.

Cardiac gated breath-hold black blood MRI of the coronary artery wall: an in vivo and ex vivo comparison.

BACKGROUND: High resolution magnetic resonance (MR) imaging of the coronary artery wall in vivo has been limited by the cardiac and respiratory motion, flow artifacts as well as the relatively small size of the coronary arteries. We sought to validate in vivo black blood MR imaging of the coronary artery wall using a double inversion recovery fast spin echo MR imaging sequence with limited breath-holding and cardiac gating for suppression of motion artifacts by comparison with ex vivo MR imaging. METHODS: Yorkshire albino swine (n = 6) were used in this study and coronary lesions were induced with balloon angioplasty. Four weeks after balloon injury of the coronary arteries MR imaging of the coronary artery lesions was performed. High resolution in vivo and ex vivo images of the coronary artery wall and lesions were obtained using a double inversion recovery fast spin echo sequence in a 1.5 T MR system. There was a statistically significant agreement (p < 0.0001) between measurements of vessel wall area (r = 0.87, slope = 0.87) and maximal wall thickness (r = 0.84, slope = 0.88) from in vivo and ex vivo MR images of the coronary arteries. The mean differences between in vivo and ex vivo measurements were 0.56 +/- 1.98 mm2 for vessel wall area and 0.02 +/- 0.36 mm for maximal wall thickness. CONCLUSIONS: Using breathholding and cardiac gating, it is possible to perform high resolution MR imaging of the coronary artery wall in vivo with good suppression of motion artifacts with a double inversion recovery fast spin echo black blood imaging sequence.

Atherosclerotic aortic component quantification by noninvasive magnetic resonance imaging: an in vivo study in rabbits.

OBJECTIVES: We sought to demonstrate the ability that noninvasive in vivo magnetic resonance imaging (MRI) has to quantify the different components within atherosclerotic plaque. BACKGROUND: Atherosclerotic plaque composition plays a critical role in both lesion stability and subsequent thrombogenicity. Noninvasive MRI is a promising tool for the characterization of plaque composition. METHOD: Thoracic and abdominal aortic atherosclerotic lesions were induced in rabbits (n = 5). Nine months later, MRI was performed in a 1.5T system. Fast spin-echo sequences (proton density-weighted and T2-weighted [T2W] images) were obtained (in-plane resolution: 350 x 350 microns, slice thickness: 3 mm). Magnetic resonance images were correlated with matched histopathological sections (n = 108). RESULTS: A significant correlation (p < 0.001) was observed for mean wall thickness and vessel wall area between MRI and histopathology (r = 0.87 and r = 0.85, respectively). The correlation was also present on subanalysis of the thoracic and upper part of the abdominal aorta, susceptible to respiratory motion artifacts. There was a significant correlation for plaque composition (p < 0.05) between MRI and histopathology for the analysis of lipidic (low signal on T2W, r = 0.81) and fibrous (high signal on T2W, r = 0.86) areas with Oil Red O staining. T2-weighted images showed greater contrast than proton density-weighted between these different components of the plaques as assessed by signal intensity ratio analysis with the mean difference in signal ratios of 0.47 (S.E. 0.012, adjusted for clustering of observations within lesions) being significantly different from 0 (t1 = 39.1, p = 0.016). CONCLUSIONS: In vivo noninvasive high resolution MRI accurately quantifies fibrotic and lipidic components of atherosclerosis in this model. This may permit the serial analysis of therapeutic strategies on atherosclerotic plaque stabilization.

Acute antithrombotic effect of a front-loaded regimen of clopidogrel in patients with atherosclerosis on aspirin.

There is a need for a rapid antithrombotic effect after the administration of antiplatelet drugs in the setting of acute coronary syndromes and percutaneous interventions. Clopidogrel, a new thienopyridine derivative, is an efficient antiplatelet agent. However, the standard regimen of clopidogrel (75 mg/d) requires 2 to 3 days before significant antithrombotic effects. Patients with stable arterial disease on chronic aspirin therapy (n=20) were treated with clopidogrel either with a front-loaded regimen, 300 mg the first day and 75 mg/d the next 7 days, or with a standard regimen, 75 mg/d for 8 days. Blood thrombogenicity was assessed by quantification of platelet-thrombus formation in an ex vivo perfusion chamber, by ADP-induced platelet aggregation, and by ADP-induced fibrinogen binding. At 2 hours, mean total thrombus area with the standard regimen was not significantly reduced. In contrast, at 2 hours, the mean total thrombus area with the front-loaded regimen was significantly decreased by 23.1+/-8.5% versus baseline (P<0.05). ADP-induced platelet aggregation (with 5 and 10 micromol/L) was also significantly (P<0.05) reduced with the front-loaded regimen at 2 hours, with the mean platelet aggregation being 82.2+/-4.4% and 81.8+/-4.5%, respectively, versus baseline. Similarly, flow cytometry demonstrated a significant decrease (P<0. 05) in the ADP-induced fibrinogen binding (with 0.12 and 0.6 micromol/L) at 2 hours in this front-loaded regimen group (36.1+/-2. 0% and 53.2+/-9.3%). With the standard regimen, platelet activity was not significantly reduced at 2 hours. Our data suggest that a front-loaded regimen of clopidogrel added to aspirin achieves a significant antithrombotic effect at 2 hours in patients with known atherosclerotic disease on chronic aspirin therapy. This provides a rationale for using front-loaded clopidogrel in combination with aspirin in percutaneous coronary interventions.

High resolution ex vivo magnetic resonance imaging of in situ coronary and aortic atherosclerotic plaque in a porcine model.

Atherosclerotic plaque composition is central to the pathogenesis of plaque disruption and acute thrombosis. Thus, there is a need for accurate imaging and characterization of atherosclerotic lesions. Even though there is no ideal animal model of atherosclerosis, the porcine model is considered to most closely resemble human atherosclerosis. We report the feasibility of MR imaging and characterizing of atherosclerotic lesions from in situ coronary arteries and aortas in an ex vivo setting and validate this with histopathology. Coronary and aortic atherosclerosis was induced in Yucatan mini-swine (n=4) by a combination of atherogenic diet (6 months) and balloon injury. All coronary arteries were imaged ex vivo on the intact heart, preserving the curvature of their course. The aorta also underwent MR imaging. The MR images were correlated with the matched histopathology sections for both the coronary arteries (n=54) and the aortas (n=43). MR imaging accurately characterized complex atherosclerotic lesions, including calcified, lipid rich, fibrocellular and hemorrhagic regions. Mean wall thickness for the coronary arteries (r=0.94, slope: 0.81) and aortas (r=0.94, slope: 0.81) as well as aortic plaque area (r=0.97, slope: 0.90) was accurately determined by MR imaging (P<0.0001). Coronary artery MR imaging is not limited by the curvature of the coronary arteries in the heart. MR imaging accurately quantifies and characterizes coronary and aortic atherosclerotic lesions, including the vessel wall, in this experimental porcine model of complex atherosclerosis. This model may be useful for future study of MR imaging of atherosclerosis in vivo.

Noninvasive in vivo magnetic resonance imaging of experimental coronary artery lesions in a porcine model.

BACKGROUND: The ability to characterize and quantify coronary artery atherosclerotic lesions accurately, reproducibly, and noninvasively may allow the stratification of risk for future acute coronary syndromes and help direct therapeutic management. MRI has been shown to accurately characterize and quantify atherosclerosis; however, because of the combination of cardiac and respiratory motion artifacts, nonlinear course, and relatively small size of the coronary arteries, these techniques have not been able to be translated to the coronary system in vivo. METHODS AND RESULTS: Coronary lesions were induced in Yorkshire albino swine (n=6) with balloon angioplasty, and 4 weeks later MRI of the coronary artery lesions was performed. High-resolution in vivo images of the coronary artery wall and lesions were obtained with a double-inversion-recovery fast-spin-echo sequence in a 1.5-T MR system. There was good agreement between measurements of vessel wall thickness and area from MR images of the coronary arteries and the matched histopathology sections (n=43). The mean difference (MRI minus histopathology +/- SD) for mean wall thickness was 0.26+/-0.18 mm, and for vessel wall area, 5.65+/-3.51 mm(2). MRI was also able to visualize intralesion hematoma (sensitivity 82%, specificity 84%). CONCLUSIONS: Using a clinical MR system, we were able to image coronary artery lesions in vivo in an experimental porcine model. Further studies are needed to assess the ability of MRI to characterize coronary atherosclerotic lesions in vivo.