RESUMEN

The aim of this study was to analyze the equilibrium and dynamic periods for mass transfer during the antioxidant solid-liquid extraction of dry roselle flower (Hibiscus sabdariffa). Extraction kinetics for total phenolic compounds (TPC), total flavonoids (TFL) and total antioxidant capacity (TAC) were obtained at different temperatures (50, 60, 70 or 80 °C) and solvent-to-product mass ratios (100:1, 200:1 or 300:1 g/g) under stirring (220-230 rpm). An analytical solution for unsteady-state mass transfer based on Fick's second law of diffusion was used to mathematically describe solid-liquid extraction curves and for the simultaneous estimation of diffusion coefficients and the final amount of extracted bioactive compounds, which were further related to experimental conditions by a second order model. The amount of extracted bioactive compounds at equilibrium were in the ranges of 30.8-89.8 g GAE/kg d.m. for TPC (0.154-0.373 g GAE/L extract), 40.0-131.6 g catechin/kg d.m. for TFC (0.269-0.559 g catechin/L extract) and 37.5-227.0 g trolox/kg d.m. for TAC (0.346-0.865 g trolox/L extract). On the other hand, diffusion coefficients for TPC, TFC and TAC were in the ranges of 0.72-2.66 × 10-11, 0.25-2.37 × 10-11 and 1.19-5.79 × 10-11 m2/s, respectively.

RESUMEN

The aim of this research was to evaluate the storage stability (5 °C), and microbial modeling, of Rubi red grapefruit (Citrus × paradisi) juice treated with ultraviolet-C (UV-C) light (0, 10 and 20 min), alone or in combination with trans-cinnamaldehyde (trans-CAH) (0, 25 and 50 µg/mL). A 32 factorial design was used and data modeled with the Weibull, Modified Gompertz and Logistic models. A response surface model was used to evaluate the effect of modeling parameters for suggesting the optimum treatment conditions. Treated and some untreated juice lasted up to 9 days without physicochemical and microbial changes. At the higher combination of UV-C light and trans-CAH, the microbial load of grapefruit juice was maintained below 100 CFU/mL up to 15 days. For mesophiles, the three predictive models indicated that the parameters n and Nmax decreased and the parameters λ and tc increased as the combination of UV-C light and trans-CAH increased. The response surface modeling of the parameters obtained by the predictive models showed acceptable correlation for mesophiles (R2 = 0.815-0.977) but not for yeasts (R2 = 0.618-0.815). The three predictive models showed that, the concentration of trans-CAH had more effect on stopping the microbial growth than the UV-C light treatment.

Asunto(s)

RESUMEN

This study compared the stability of extracts of H. sabdariffa calyces microencapsulated with different concentrations of mesquite gum during storage. Dry Roselle calyces were mixed with 50:50 (v/v) ethanol:water solution to obtain 18°Bx concentrate. This Roselle extract concentrate was mixed with purified mesquite gum (100:1-100:5 v/w). The Roselle extract concentrate-gum (RECG) was spray dried at inlet and outlet temperatures of 180 ± 2 and 104 ± 2.3 °C, respectively, at an air flow rate of 38 m3/h. Encapsulated Roselle powders (ERP) were analyzed for moisture content, total monomeric anthocyanins (differential pH), phenolic compounds (Folin and Ciocalteu method), antioxidant capacity (ABTS), and color parameters ([Formula: see text], and [Formula: see text]) after 5 weeks and 1 year of storage. Sorption properties (isotherms) and micrographs of powders were also obtained. The average yield of RECG powders was 15.27 ± 0.81 g/100 mL. During storage, ERP showed average values of phenolic compounds, antioxidant capacity, and anthocyanins of 3.43 ± 0.25 g gallic acid equivalents/100 g, 9.34 ± 1.4 g Trolox equivalents/100 g, and 318.7 ± 20.6 mg cyanidin-O-glycoside/100 g, respectively. Color parameters remained constant along the storage time.

RESUMEN

Recent studies have demonstrated that three membrane-permeant A(1) receptor antagonists reduced infarct size in a model of ischemia followed by brief reperfusion. However, it was not determined whether cardioprotection was mediated by nonspecific intracellular effects of these highly lipophilic drugs and whether the antagonists only delayed myocardial necrosis without affecting the ultimate infarct size. In the present study, closed-chest dogs were subjected to 90 min of left anterior descending coronary artery occlusion and 72 h of reperfusion and received either a nonmembrane-permeant adenosine receptor blocker that is devoid of direct intracellular effects and is 6-fold selective for the A(1) receptor [1, 3-dipropyl-8-p-sulfophenylxanthine (DPSPX); n = 11] or vehicle (n = 12). DPSPX was administered as three 200-mg boluses 60 min before and 30 and 120 min after reperfusion. The area of necrosis was determined histologically and expressed as a percentage of the area at risk. Baseline predictors of infarct size were similar in the two groups. The ratio of the area of necrosis to the area at risk was less in the DPSPX group (17.8 +/- 4.3% versus 35.0 +/- 1.9%; P =. 012), and DPSPX improved regional ventricular function. Under both basal and stimulated (formyl-Met-Leu-Phe) conditions, suspensions of human neutrophils generated extracellular adenosine levels (approximately 50 nM) sufficient to activate A(1) receptors. Moreover, both DPSPX and 1,3-dipropyl-8-cyclopentylxanthine, a selective A(1) receptor antagonist, significantly reduced the chemoattractant response of neutrophils to formyl-Met-Leu-Phe. We conclude that blockade of A(1) adenosine receptors attenuates myocardial ischemic/reperfusion injury, possibly in part by decreasing the chemoattractant response of neutrophils.

Asunto(s)

RESUMEN

The authors report 7 cases of gangrenous ergotism (six women and one man) secondary to an overdose of ergotamine ingested in order to relieve migraine crisis. In all cases, patients presented symptoms and signs of severe arterial constriction confirmed by echography and angiography. Hallucinations were absent. Ergotamine ingestion was discontinued and treatment was based on vasodilators and sympathectomy. After treatment, all seven patients showed clinical improvement with disappearance of the vasospastic symptoms and signs, and an increase in the plethysmographic index of blood perfusion, measured by Doppler echography. These changes were observed even in a patient who lost two toes of the right foot. Although, none of the patients presented hallucinations, the authors made reference to the historical first use of the ergot in magic and religious rites that took place in Eleusis, at the time of classic Greece, as well as the more recent mystic use of ergot in Salem, New England, in 1692. Migraine is indeed a serious disease, frequently causing despair to the patient, who attempts to alleviate the migraneous crisis with an overdose of ergotamine. Accordingly, physicians must be aware of prophylactic vasodilating drugs, reducing the risk of ergotism.

Asunto(s)

RESUMEN

Beside the immediate success of surgery and of embolization of angiodysplasias, certain number of patients return to medical consultation, because recanalization of the arteriovenous fistulae after their resection or obturation. From the presentation of two clinical cases of thoracic angiodysplasia: one of them slender, and threatening the other, the authors point out the complications and recurrence after surgical resection or arterial embolization. The recurrence takes place even when only one artery remains permeable after resection or embolization of the fistula. There are cases where the affected limb has to be amputated. However, angiodysplasia shows itself in the stump of the amputee limb. Uncontrolled angio-genesis is the natural history or postoperatory evolution of angiodysplasias, probably originated by an erroneous genetic program, which persist in spite of resection of the vascular malformation, causing a therapeutic failure.

Asunto(s)

RESUMEN

This study attempted to define the role of endothelin (ET) in preconditioning. We previously showed that ET Is produced during myocardial ischemia and reperfusion. Because both preconditioning and ET act through protein kinase C, ET could play a role in preconditioning. Dogs were randomized to three groups subjected to 40 minutes of ischemia, with (groups A and B) or without (group C) preconditioning, followed by 4 hours of reperfusion. Groups A and C received saline infusions; group B received continuous infusions of the ETA-selective antagonist FR139317. Both preconditioned groups had smaller infarct sizes (group A, 7.9% +/- 2.5%; group B, 8.4% +/- 2.6%) than the nonpreconditioned group (group C, 16.2% +/- 3.3%). Administration of the ETA antagonist FR139317 did not alter infarct size. This study demonstrated that ETA-receptor blockade did not alter infarct size in preconditioned animals and suggests that endothelin does not play a significant role in this process.

Asunto(s)

RESUMEN

BACKGROUND: Dobutamine stress echocardiography (DSE) and myocardial contrast echocardiography (MCE) can predict recovery of left ventricular function after myocardial infarction. DSE also has been shown to predict left ventricular functional recovery after revascularization in chronic ischemic heart disease, whereas MCE has not been evaluated in such patients. This study was performed to compare DSE and MCE in the prediction of left ventricular functional recovery after revascularization in patients with chronic ischemic heart disease. METHODS AND RESULTS: MCE and DSE were performed in 35 patients with chronic coronary artery disease and significant wall motion abnormalities (mean ejection fraction, 0.36 +/- 0.09). Regional wall motion was scored by use of a 16-segment model wherein 1 = normal or hyperkinetic, 2 = hypokinetic, 3 = akinetic, and 4 = dyskinetic. Each segment was evaluated for contractile reserve by DSE and perfusion by MCE. Revascularization (coronary artery bypass graft [n = 13] and percutaneous transluminal coronary angioplasty [n = 10]) was successful in 23 patients. Follow-up echocardiograms were done to assess wall motion 30 to 60 days later. In 238 segments with resting wall motion abnormalities, perfusion was more likely to present than contractile reserve (97% versus 91%, P < .02). Revascularization resulted in functional recovery in 77 of 95 hypokinetic segments (81%) but only 18 of 57 akinetic segments (32%, P < .0001). DSE and MCE were not significantly different in predicting functional recovery of hypokinetic segments. In akinetic segments, DSE and MCE had similar sensitivities (89% versus 94%, respectively) and negative predictive values (93% and 97%, respectively) in predicting functional recovery. However, DSE had a higher specificity (92% versus 67%, P < .02) and positive predictive value (85% versus 55%, P < .02) than MCE in predicting functional recovery. CONCLUSIONS: Both contractile reserve by DSE and perfusion by MCE are predictive of functional recovery in hypokinetic segments after coronary revascularization in patients with chronic coronary revascularization in patients with chronic coronary artery disease. In akinetic segments, myocardial perfusion by MCE may exist in segments that do not recover contractile function after revascularization. Thus, contractile reserve during low-dose dobutamine infusion is a better predictor of functional recovery after revascularization in akinetic segments than perfusion.

Asunto(s)

RESUMEN

OBJECTIVES: This study assessed the accuracy of 2% dodecafluoropentane (EchoGen), an intravenous echocardiographic contrast agent, in identifying myocardial area at risk and infarct size in the canine model of myocardial ischemia. BACKGROUND: Myocardial contrast echocardiography allows determination of myocardial area at risk and infarct size but requires intracoronary injection in humans. The development of agents that can be delivered by peripheral intravenous injection could enable bedside myocardial contrast echocardiographic assessment of risk area, infarct size and reperfusion. METHODS: Two protocols were used. Protocol 1 assessed the accuracy of myocardial contrast echocardiography using intravenous dodecafluoropentane in defining myocardial area at risk and infarct size in the canine model of regional myocardial ischemia versus gross pathologic specimens stained with monastral blue to determine area at risk and triphenyltetrazolium chloride to determine the area of necrosis. Protocol 2 assessed the effects of repeated injections of dodecafluoropentane (0.5 ml/kg body weight, four doses 30 min apart or eight doses 10 min apart) on myocardial blood flow and hemodynamic variables. RESULTS: Myocardial contrast echocardiography accurately defined area at risk and infarct size (r = 0.96 vs. triphenyltetrazolium chloride). Myocardial blood flow remained stable after multiple serial injections of dodecafluoropentane. However, a significant increase in pulmonary artery pressure and pulmonary vascular resistance, along with a decrease in arterial oxygen saturation and cardiac output, was seen in dogs that received eight injections at 10-min intervals. CONCLUSIONS: Myocardial contrast echocardiography using intravenous dodecafluoropentane accurately defined myocardial area at risk and infarct size. Hemodynamic variables and regional myocardial blood flows remained stable when dodecafluoropentane was injected at 30-min intervals for up to four doses; more frequent administration led to cardiopulmonary deterioration. Dodecafluoropentane offers the potential for reliable, noninvasive assessment of reperfusion after therapeutic interventions.

Asunto(s)

RESUMEN

The role of endothelin, a potent long-acting vasoconstrictor peptide, in the pathogenesis of the "no-reflow" phenomenon was investigated in nine closed-chest mongrel dogs undergoing 90 minutes of proximal left anterior descending artery occlusion and 3.5 hours of reperfusion. Endothelin levels were measured serially from the coronary sinus (CS) and aorta (Ao) by radioimmunoassay and correlated with regional myocardial blood perfusion. Prolonged anesthesia, surgery, and vascular instrumentation did not change endothelin levels in four sham animals. A progressive and parallel increase in CS and Ao endothelin levels occurred during coronary occlusion. A further increase in CS levels was observed during the reperfusion period, resulting in significantly higher values of the peptide at 30 and 60 minutes (30 minutes: CS 22.1 +/- 3.5 vs Ao 15.1 +/- 5.1 pg/ml; 60 minutes: CS 21.1 +/- 4.5 vs Ao 15.0 +/- 3.6 pg/ml; p < 0.05 by analysis of variance). Microvascular perfusion determined semiquantitatively with fluorescent beads was significantly reduced in the central ischemic zone (CIZ) compared with that in the nonischemic zone (NIZ) (CIZ endocardium 1.14 +/- 0.4 beads/m2, CIZ midmyocardium 1.19 +/- 0.3 beads/m2, NIZ 3.8 +/- 0.6 beads/m2; p < 0.05). A significant correlation was noted between mean reperfusion levels of endothelin in the CS and endocardial flow in the CIZ (r = -0.88; p = 0.009). This study demonstrates that reperfusion per se enhanced the spillover of endothelin from the cardiac interstitium. Local release of endothelin may contribute to the progressive decrease in microvascular flow in the reperfused bed.

Asunto(s)

RESUMEN

OBJECTIVE: Intravenous adenosine decreases infarct size in experimental models of myocardial ischaemia/reperfusion. Ischaemia/reperfusion is associated with a significant increase in cardiac release of endothelin. The effect of cardioprotective doses of adenosine on endothelin release was explored in dogs undergoing 90 min coronary occlusion and 210 min reperfusion. METHODS: Dogs were assigned to intravenous adenosine in a dose of 0.15 mg.kg-1.min-1 (n = 12) or control (n = 11) during the first 150 min reperfusion. Serial endothelin levels were obtained from the coronary sinus and aortic blood and measured by radioimmunoassay. RESULTS: Adenosine significantly reduced infarct size expressed as a percent of the risk region (28.8 6% v 14.4 2%; p = 0.03). A similar increase in aortic and coronary sinus blood endothelin was observed in both groups during temporary occlusion. A significant transcardiac increase in endothelin levels was present in the control group 60 min after reperfusion whereas no increase occurred in the adenosine treated group [control 5.6(SEM 1.9) v adenosine -0.2(1.4) pg.ml-1; p = 0.02]. Similarly, intravenous adenosine tended to prevent the increase in myocardial endothelin production seen in control animals during the early reperfusion period [control 280(146) v adenosine -57(55) pg.min-1; p = 0.05]. Endocardial blood flow in the ischaemic zone 210 min after reperfusion was significantly higher in the adenosine group, at 0.60(0.02) v 0.38(0.02) ml.min-1.g-1; p < 0.05. A significant correlation between endothelin levels, endocardial flow and infarct size was observed in the control group 3 h after reperfusion: r = 0.73, p = 0.02; r = 0.62, p = 0.03 respectively. This relationship was absent in animals treated with adenosine. CONCLUSIONS: Intravenous adenosine suppresses the release of endothelin from the previously ischaemic myocardium during the early reperfusion period. This effect may in part contribute to the improvement by adenosine in postischaemic microcirculatory flow resulting in attenuation of the "no reflow" phenomenon.

Asunto(s)

Asunto(s)

RESUMEN

To explore the contribution of reperfusion injury to final infarct size after a short duration of ischemia, closed-chest dogs underwent 40 minutes of proximal left anterior descending artery occlusion followed by 3 days of reperfusion. Animals randomly received intracoronary adenosine (n = 8) at 3.75 mg/min during the first hour of reperfusion or no therapy (control, n = 9). Infarct size was measured histologically. Regional ventricular function was determined with contrast ventriculography. The risk region was similar and collateral blood flow in the inner two thirds of the ischemic zone was markedly reduced in both groups (adenosine: 0.05 +/- 0.07 ml/min/gm; control: 0.02 +/- 0.07 ml/min/gm; p = NS). Infarct size as a percent of the area at risk was significantly reduced in the adenosine group (5.0 +/- 1.3% versus 13.5 +/- 3.2%; p = 0.03), associated with a trend for improved recovery of regional ventricular function. Relative endothelial preservation was seen in the adenosine group. These results suggest that reperfusion injury contributes to final myocardial cell necrosis in the closed-chest canine model subjected to 40 minutes of regional ischemia.

Asunto(s)

RESUMEN

Adenosine is an endogenous nucleoside produced from the breakdown of adenosine triphosphate (ATP) that possesses a number of complex cellular and metabolic effects that could ameliorate postischemic contractile dysfunction (myocardial stunning). Potential mechanisms include the repletion of high-energy phosphate stores, reduced myocardial oxygen consumption, a decrease in oxygen-derived free radicals, restoration of calcium homeostasis, and an increase in regional myocardial blood flow. Experimental studies have shown that adenosine can reduce myocardial stunning with or without a concomitant increase in the total myocardial ATP stores. Adenosine may be a useful pharmacologic strategy in the prevention and treatment of ventricular dysfunction following episodes of regional or global ischemia, although further studies are needed to clarify the precise cellular mechanisms involved.

Asunto(s)

RESUMEN

The effect of semiemergent percutaneous transluminal coronary angioplasty on clinical and electrocardiographic (ECG) variables was assessed in 76 patients with unstable angina secondary to an isolated severe proximal left anterior descending coronary artery stenosis. All patients manifested symmetric T wave inversion in two or more anterior ECG leads. Wall motion abnormalities were present in 37 patients on ventriculography before dilation. Angioplasty was successful in 70 patients (92%), resulting in a reduction in luminal diameter stenosis from 91 +/- 8% to 21 +/- 6%, with no major acute procedure-related complications observed. The other six patients underwent semiurgent (less than 48 h) coronary artery bypass surgery and three patients experienced a myocardial infarction (before bypass surgery in two). Serial ECGs revealed complete resolution of ST-T wave changes in 51% of patients at 14 weeks and in 90% at 28 weeks. In contrast, prolongation of the corrected QT interval, which was present in 16 patients (8%), normalized within 48 h of successful angioplasty. Twelve of these 16 patients with a prolonged QT interval had nonocclusive thrombus formation and poor collateral circulation on angiography. Patients were followed up for 6 to 43 months (mean 23 +/- 10). Angiographic evidence of restenosis was present in 34% of patients, all of whom underwent a successful second or third procedure. One death occurred at 8 months after successful angioplasty. Wall motion abnormalities had completely resolved in 13 of 15 patients who underwent repeat ventriculography, at which time 10 had a normal ECG. This study demonstrates that ECG changes may persist for up to 7 months in patients who undergo successful angioplasty for severe left anterior descending coronary artery disease and unstable angina. Semiemergent angioplasty was associated with a high initial success rate and excellent long-term outcome.

Asunto(s)

RESUMEN

Fifty-four patients with previous myocardial infarction and sustained ventricular tachycardia on fibrillation underwent two electrophysiologic studies in the drug-free state within 72 hours. Although the concordance of overall ventricular tachycardia induction over the 2 days was good (87% of patients), there was variability in the number of extrastimuli needed to induce sustained ventricular tachycardia on each day in 60% of patients. Of those in whom ventricular tachycardia was inducible on both days, 40% required additional extrastimuli and 20% required fewer extrastimuli. A change by two or more extrastimuli was found in 12% of patients. There was no correlation between the variability observed and multiple clinical and laboratory parameters (including the aggressiveness of the stimulation protocol); however, the direction of the variability (easier or harder to induce) correlated with changes in ventricular refractoriness. Inherent day-to-day variability may affect the reproducibility of electrophysiologic studies and influence the results of serial drug testing.

Asunto(s)