Influence of left ventricular relaxation on the pressure half time of aortic regurgitation

BACKGROUND The severity of aortic regurgitation can be estimated using pressure half time (PHT) of the aortic regurgitation flow velocity, but the correlation between regurgitant fraction and PHT is weak. AIM To test the hypothesis that the association between PHT and regurgitant fraction is substantially influenced by left ventricular relaxation. METHODS In 63 patients with aortic regurgitation, subdivided into a group without (n = 22) and a group with (n = 41) left ventricular hypertrophy, regurgitant fraction was calculated using the difference between right and left ventricular cardiac outputs. Left ventricular relaxation was assessed using the early to late diastolic Doppler tissue velocity ratio of the mitral annulus (E/ADTI), the E/A ratio of mitral inflow (E/AM), and the E deceleration time (E-DT). Left ventricular hypertrophy was assessed using the M mode derived left ventricular mass index. RESULTS The overall correlation between regurgitant fraction and PHT was weak (r = 0.36, p < 0.005). In patients without left ventricular hypertrophy, there was a significant correlation between regurgitant fraction and PHT (r = 0.62, p < 0.005), but not in patients with left ventricular hypertrophy. In patients with a left ventricular relaxation abnormality (defined as E/ADTI< 1, E/AM< age corrected lower limit, E-DT >/= 220 ms), no associations between regurgitant fraction and PHT were found, whereas in patients without left ventricular relaxation abnormalities, the regurgitant fraction to PHT relations were significant (normal E/AM: r = 0.57, p = 0.02; E-DT< 220 ms: r = 0.50, p < 0.001; E/ADTI < 1: r = 0.57, p = 0.02). CONCLUSIONS Only normal left ventricular relaxation allows a significant decay of PHT with increasing aortic regurgitation severity. In abnormal relaxation, which is usually present in left ventricular hypertrophy, wide variation in prolonged backward left ventricular filling may cause dissociation between the regurgitant fraction and PHT. Thus the PHT method should only be used in the absence of left ventricular relaxation abnormalities.

Development of a method for fast and automatic radiocarbon measurement of aerosol samples by online coupling of an elemental analyzer with a MICADAS AMS

A fast and automatic method for radiocarbon analysis of aerosol samples is presented. This type of analysis requires high number of sample measurements of low carbon masses, but accepts precisions lower than for carbon dating analysis. The method is based on online Trapping CO2 and coupling an elemental analyzer with a MICADAS AMS by means of a gas interface. It gives similar results to a previously validated reference method for the same set of samples. This method is fast and automatic and typically provides uncertainties of 1.5–5% for representative aerosol samples. It proves to be robust and reliable and allows for overnight and unattended measurements. A constant and cross contamination correction is included, which indicates a constant contamination of 1.4 ± 0.2 μg C with 70 ± 7 pMC and a cross contamination of (0.2 ± 0.1)% from the previous sample. A Real-time online coupling version of the method was also investigated. It shows promising results for standard materials with slightly higher uncertainties than the Trapping online approach.

An Exploration Based Cognitive Bias Test for Mice: Effects of Handling Method and Stereotypic Behaviour

Behavioural tests to assess affective states are widely used in human research and have recently been extended to animals. These tests assume that affective state influences cognitive processing, and that animals in a negative affective state interpret ambiguous information as expecting a negative outcome (displaying a negative cognitive bias). Most of these tests however, require long discrimination training. The aim of the study was to validate an exploration based cognitive bias test, using two different handling methods, as previous studies have shown that standard tail handling of mice increases physiological and behavioural measures of anxiety compared to cupped handling. Therefore, we hypothesised that tail handled mice would display a negative cognitive bias. We handled 28 female CD-1 mice for 16 weeks using either tail handling or cupped handling. The mice were then trained in an eight arm radial maze, where two adjacent arms predicted a positive outcome (darkness and food), while the two opposite arms predicted a negative outcome (no food, white noise and light). After six days of training, the mice were also given access to the four previously unavailable intermediate ambiguous arms of the radial maze and tested for cognitive bias. We were unable to validate this test, as mice from both handling groups displayed a similar pattern of exploration. Furthermore, we examined whether maze exploration is affected by the expression of stereotypic behaviour in the home cage. Mice with higher levels of stereotypic behaviour spent more time in positive arms and avoided ambiguous arms, displaying a negative cognitive bias. While this test needs further validation, our results indicate that it may allow the assessment of affective state in mice with minimal training— a major confound in current cognitive bias paradigms.

Trends over time of virological and immunological characteristics in the Swiss HIV Cohort Study

The long-term outcome of antiretroviral therapy (ART) is not assessed in controlled trials. We aimed to analyse trends in the population effectiveness of ART in the Swiss HIV Cohort Study over the last decade.

Phase contrast and time-of-flight magnetic resonance angiography of the intracerebral arteries at 1.5, 3 and 7 T

Time-of-flight (ToF) and phase contrast (PC) magnetic resonance angiographies (MRAs) are noninvasive applications to depict the cerebral arteries. Both approaches can image the cerebral vasculature without the administration of intravenous contrast. Therefore, it is used in routine clinical evaluation of cerebrovascular diseases, e.g., aneurysm and arteriovenous malformations. However, subtle microvascular disease usually cannot be resolved with standard, clinical-field-strength MRA. The purpose of this study was to compare the ability of ToF and PC MRA to visualize the cerebral arteries at increasing field strengths.

Sleepiness at the time of testing impairs olfactory performance

We aimed to investigate the differential roles of hypocretin versus dopamine dysfunction versus excessive daytime sleepiness (EDS) in the development of hyposmia. Olfaction in patients with Parkinson disease, restless leg syndrome, narcolepsy with cataplexy, EDS, and healthy controls was compared.

Clinical relevance of coronary angiography at the time of percutaneous closure of a patent foramen ovale

BACKGROUND: The value of incidental coronary angiography during percutaneous shunt closure to screen for asymptomatic coronary artery disease (CAD) is unknown. METHODS: On the occasion of percutaneous closure of patent foramen ovale (PFO), incidental coronary angiography routinely offered to men >40 and women >50 years, or younger patients with particular risk patterns, was performed in 575 patients (64% men, mean age 55 +/- 10 years, mean 1.5 +/- 1.1 cardiovascular risk factors) without overt history, signs, or symptoms of CAD. RESULTS: CAD was found in 164 patients (29%); 53 (9%) had >or=50% diameter stenoses. Thirty patients (5%) had one-vessel, 13 (2%) two-vessel, and 10 (2%) three-vessel disease. Patients with CAD (n = 164) were older (60 +/- 9 vs. 53 +/- 10 years; P < 0.0001), more frequently male (76% vs. 59%; P = 0.0002), and had a higher body mass index (26.5 +/- 4.0 vs. 25.4 +/- 4.6; P = 0.006) and more cardiovascular risk factors (2.0 +/- 1.1 vs. 1.2 +/- 1.0; P < 0.0001). There were six procedural complications (1%). Two were unequivocally related to coronary angiography: one minor stroke (diplopia), and one iatrogenic dissection of the right coronary ostium requiring stenting. Furthermore, four arteriovenous fistulae at the puncture site requiring elective surgical closure were possibly related to coronary angiography. Forty-five patients (8% of total) underwent percutaneous (n = 43) or surgical (n = 2) revascularization. CONCLUSIONS: In selected asymptomatic patients referred for percutaneous PFO closure, incidental coronary angiography discloses a rather high prevalence of clinically unsuspected CAD. These findings are relevant not only for timely revascularization but also for maintenance of long-term antiplatelet therapy beyond the few months recommended after PFO closure.