[Aortic debris in cerebrovascular ischemic disease]. / Debris aórtico en la enfermedad cerebrovascular isquémica.

BACKGROUND: The aortic atherosclerotic debris is considered a high risk embolic source, being an independent predictor for cerebrovascular ischemia. The incidence is higher in the elderly and in patients with coronary artery disease. Transesophageal echocardiogram (TEE) is an important diagnostic tool that allows its detection. OBJECTIVE: To describe characteristics of patients with ischemic stroke and echocardiographic diagnosis of aortic debris. PATIENTS AND METHODS: We analyzed the group of patients with debris diagnosis in 209 TEE performed between 01/01/99 and 31/05/02, in 835 consecutive ischemic events. The information was collected from the Stroke Database of the Neurology Department of Policlinica Bancaria. RESULTS: TEE was accomplished in 25% of all assisted events. The mean age was 66.56 years (SD 11.22). In 30 studies (14%) aortic debris was detected. In this group of patients, 26 men and 4 women, was also found: plaques grade IV 60%, left atrial dilatation 40% and spontaneous echo contrast 20%. The most frequent risk factors were hypertension, dislipemia and smoking, with no significative difference compared to the group without debris. 40% had a prior cerebrovascular event. They presented with clinical subtype LACI 53%, PACI 27%, POCI 17%. 63% of patients had lacunar infarct (53% anterior and 10% posterior). CONCLUSION: The contribution of TTE for detection of embolic sources is relevant. A high percentage of the population with echocardiographic diagnosis of aortic debris, had a lacunar infarct, defined radiologically and by clinical features.

[Ischemic stroke: transesophageal echocardiographic findings]. / Accidente cerebrovascular isquémico: hallazgos en ecocardiograma transesofágico.

INTRODUCTION: Since its initial application in 1976, the transesophageal echocardiogram (TEE) has improved the detection of cardiovascular emboligenic sources. Even though its indication in patients with stroke is still controversial, its use has contributed to the identification of potential embolic stroke sources. OBJECTIVE: To describe the transesophageal echocardiographic findings in ischemic stroke patients. PATIENTS AND METHODS: We analyzed case series of 162 TEE performed on a total of 576 ischemic events dated between 01/01/99 to 01/05/01. The required information was collected prospectively in the Stroke Data Bank of the Neurology Department at Policl nico Bancario in Buenos Aires. RESULTS: TEE was carried out in 162 (28.1%) cases. Of theses cases 13% belonged to the clinical subtype TACI, 37% to PACI, 17% to POCI, and 37% to LACI subtype. Pathologic findings corresponded to cardiac level: spontaneous contrast in 29% of the cases, and to aortic level: plaques grade IV in 34% and debris in 13% of the cases. According to the etiology of ischemic stroke, 67 patients had been registered under the diagnosis of lacunar infarct (60 in the anterior region and 7 in the posterior region), 93 had been diagnosed medium and grand artery infarct (73 in the anterior region and 29 in the posterior region), and 2 had remained unclassified. Emboligenic sources were found in 69.5% of TACI, 65% of PACI, 52% of POCI, and 53% of LACI. CONCLUSIONS: A high percentage of aortic artheroembolic pathology was detected in the population under study. However, spontaneous contrast was the echocardiographic phenomenon more frequently reported. It is to be pointed out the presence of potential cardiac and/or aortic emboligenic sources in 48% of the population with lacunar infarct

Follitropin binding to receptors in testis: studies on the reversibility and thermodynamics of the reaction.

Studies were designed to assess the extent to which binding of follitropin (FSH) to its receptor is a reversible process. [125I]hFSH was allowed to interact with membrane receptors from calf testis for 2 h at various temperatures by which time significant specific binding of [125I]hFSH had taken place in all instances. Unlabeled FSH was then added (delayed addition) and the amount of [125I]hFSH remaining bound was monitored as a function of time. In order to assess reversibility, [125I]hFSH binding in the latter samples was compared to that occurring when unlabeled FSH had not been added or when unlabeled FSH was present from the start of the incubation. Binding was essentially fully reversible at 4 degrees C, but reversibility decreased with increasing temperature. Reversibility of FSH binding decreased markedly at temperatures greater than 26 degrees C and was considered irreversible at temperatures above 30 degrees C. At 4 degrees C essentially full reversibility (greater than 90%) was observed when the unlabeled hormone was added after 7 h of incubation, but decreased when added after 12 h. At warmer temperatures (22 or 30 degrees C) 'there was a progressive decrease in reversibility as the time of delay before addition of unlabeled hormone was lengthened. By determining the affinity constant (in separate experiments) at various temperatures, a thermodynamic analysis was possible. This analysis was restricted to the temperature range 4-26 degrees C in order to minimize complications arising from irreversible binding. The reaction was endothermal at low temperatures (T less than 12.5 degrees C) and exothermal at higher temperatures (T greater than 12.5 degrees C) and was associated with a decrease in heat capacity of 1800 cal [mol deg]-1 at 25 degrees C. The results are consistent with the concept that the hydrophobic effect plays an important role in FSH binding, but that the reaction is complex and may be composed of more than one step.