1,721,056 research outputs found

    Chronobiology of symptomatic supraventricular paroxysmal tachycardia

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    The circadian, circaseptenal and circaannual occurrence of supraventricular paroxysmal tachycardias (SVPT) were examined in patients addressing an Emergency Department. Sixty-one patients, 22 men and 39 women aged 48.3+/-13.0 y, were eligible and investigated during a solar year. Cosinor method indicated a significant circadian SVPT variation, with an acrophase at about 6 p.m. A similar periodicity was also detected in supraventricular premature beat prevalence (acrophase at 3 h 31 min), concordant with heart rate peaking. Monday was the most frequently affected day, while the circa-annual analysis disclosed a peak in summer and autumn. Our findings provide further evidence that SVPT shows the highest occurrence during daytime, in possible connection with adrenergic influence. Moreover there are clues that cyclic stressors, e.g. the ones connected with working-activity resumption or climate influence; may partly condition SVPT appearance during the week or the year

    Seasonal variation in the incidence of deep vein thrombosis in patients with deficiency of protein C or protein S

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    An attempt was made to identify circaseptanal or seasonal variation of deep vein thrombosis (DVT) in a population with protein C or protein S deficit. Forty-four patients with DVT and protein C or protein S deficit were studied for 1 year. A significant circannual rhythm was found for the total population that peaked during winter. There was also a significant falling circaseptanal rhythm on Fridays. These observations may optimize an adequate and precise anticoagulant therapy in patients with protein C or protein S deficits

    Further evidence in support of the association between venous thrombosis and atherosclerosis: A case-control study.

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    INTRODUCTION: Whether there is an association between venous thromboembolism (VTE) and atherosclerosis is still controversial. AIMS: In a case-control study conducted on subjects older than 50, we assessed the prevalence of symptomatic or subclinical atherosclerosis in a group of unselected patients with unprovoked VTE, and compared it with that of patients with secondary VTE and of matched control individuals free from VTE disorders. METHODS: Cases and controls were enquired about the presence of previous symptomatic manifestations of atherosclerosis. Those with a negative history underwent the ultrasound assessment of carotid arteries following a standardized procedure. An intima-media thickness higher than 0.9mm or the detection of at least one carotid plaque was regarded as a subclinical manifestation of atherosclerosis. After adjusting for age, gender and risk factors for atherosclerosis, we calculated the odds ratio (OR) for symptomatic or subclinical atherosclerosis in patients with unprovoked VTE as compared to those with secondary VTE and controls. RESULTS: We recruited 100 patients with unprovoked VTE, 100 with secondary VTE and 100 control individuals. In patients with unprovoked VTE, the adjusted OR for symptomatic or subclinical atherosclerosis was 5.1 (95% CI, 2.0 to 13.1) in comparison to patients with secondary VTE, and 14.5 (95% CI, 5.8 to 36.3) in comparison to controls. The prevalence of atherosclerosis was higher in patients with secondary VTE than in controls (OR, 3.1; 95% CI, 1.6 to 6.1). CONCLUSION: The results of this study confirm the presence of a strong association between venous thrombosis and atherosclerosis

    The abnormal red-cell oxalate transport is a risk factor for idiopathic calcium nephrolithiasis: a prospective study.

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    An abnormal erythrocyte transmembrane oxalate flux was described in recurrent idiopathic calcium nephrolithiasis. To verify whether it might represent a risk marker of renal stone disease, two prospective studies were carried out. One hundred ninety patients with idiopathic calcium nephrolithiasis who were enrolled at their first episode of lithiasis during the period 1984 to 1986, form the basis of the first prospective study. The impact of erythrocyte oxalate transport anomaly, gender, familial occurrence of nephrolithiasis, hypercalciuria, hyperoxaluria, and hyperuricosuria on stone recurrence by both bivariate and multivariate analysis of frequencies was assessed. The predictive value of the erythrocyte anomaly for a patient's becoming a stone former was also assessed in five nephrolithiasis families. Recurrence occurred in 57.9% of patients; this was significantly associated with the erythrocyte anomaly, hyperoxaluria, and male gender. However, when using multivariate analysis, only gender and the erythrocyte anomaly were statistically significant and were independent predictors of recurrency. The probability of stone recurrency predicted by the logistic model ranged from 30.1% for women with normal erythrocyte oxalate transport, to 73.4% for men with the erythrocyte anomaly. The family follow-up showed that only subjects with the erythrocyte abnormality become renal stone-formers in the 8-yr survey. By showing the predictive value of the erythrocyte oxalate anomaly for recurrent calcium nephrolithiasis, our findings support the notion that this anomaly is a risk factor in renal stone disease

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed

    Endothelial dysfunction in haemophilia patients.

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    Haemophilia patients may develop cardiovascular diseases, suggesting that their clotting defect does not protect them completely from atherosclerosis and its complications. We aimed to evaluate cardiovascular risk factors and, for the first time, the presence of endothelial dysfunction in middle-aged haemophilia patients. We studied 40 patients with haemophilia A and B (24 with moderate-severe disease and 16 with mild disease), and 40 healthy controls. Flow-mediated dilation (FMD), carotid ultrasound (US) intima media thickness (IMT), arterial blood pressure, body mass index (BMI), cholesterol, triglycerides, glucose, insulin, lipoprotein(a) and homocysteine levels were measured, and PAI-1 and t-PA levels before and after venous occlusion (VO), and antibodies to HIV, HBV and HCV were assayed. At least one cardiovascular risk factor was detected in 87.5% of patients, and 2 or more in 47.5% of cases. At US exam, none of the patients had significant carotid stenosis or significant differences in IMT compared to controls. In contrast, all the patients had a significant FMD impairment, associated with a reduced t-PA release after VO in 70% of cases. PAI-1 levels significantly correlated with BMI, triglycerides and insulin values. Fifteen haemophilia patients with chronic viral hepatitis and/or HIV infection showed a significantly lower FMD than patients without active infection. We found an endothelial dysfunction with impaired FMD and t-PA release in our haemophilia patients, usually associated with cardiovascular risk factors. Other pathogenic mechanisms, such as chronic viral infections, are likely to be involved in this endothelial damage, however
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