Search results

Filter

Filetype

Your search for "*" yielded 532993 hits

A cortical microvascular structure in vascular dementia, Alzheimer's disease, frontotemporal lobar degeneration and nondemented controls : a sign of angiogenesis due to brain ischaemia?

Aims: We observed a microvascular structure in the cerebral cortex that has not, to our knowledge, been previously described. We have termed the structure a ‘raspberry’, referring to its appearance under a bright-field microscope. We hypothesized that raspberries form through angiogenesis due to some form of brain ischaemia or hypoperfusion. The aims of this study were to quantify raspberry freque

Kommentar från fyra doktorander vid Lunds universitet : Comments from four doctoral students at Lund University

In an earlier article, Inger Enkvist argues that the working conditions for the doctoral students in Sweden are too good since they are employed. We question her arguments and her conclusion. We show that there have not been a decline in the number of doctoral students since the universities started to employ doctoral students. Moreover, we argue that the new policy has improved the doctoral stude

Relative peripheral blood volume changes induced by premature ectopic beats and their role in hemodialysis

Hemodialysis patients often suffer from cardiovascular disorders and uremic neuropathy, increasing the propensity to homeostatic imbalance that, in turn, may result in intradialytic complications like cramp, nausea, and, worse, hypotension. Ectopic beats, being abundant in such patients, may lead to imbalance through repeated, sudden drops in blood pressure. By exploring the properties of postecto

Non-invasive evaluation of the effect of metoprolol on the atrioventricular node during permanent atrial fibrillation

The aim of this study was to evaluate changes in AV nodal properties during administration of metoprolol, using a novel ECG-based method for parameter estimation. The AV nodal parameters account for the probability of an impulse not passing through the fast pathway, the absolute refractory periods of the slow and fast pathways (aRPs and aRPf), representing the functional refractory period, and rel

A noise-adaptive method for detection of brief episodes of paroxysmal atrial fibrillation

The aim of this work is to develop a method for detection of brief episode paroxysmal atrial fibrillation (PAF). The proposed method utilizes four different features: RR interval irregularity, absence of P waves, presence of f-waves and noise level. The obtained features are applied to the Mamdani-type fuzzy inference method for decisionmaking. The performance was evaluated on one hundred 90 s lon

Prediction of intradialytic hypotension using PPG and ECG

Intradialytic hypotension (IDH) is the most common complication during hemodialysis; early prediction and prevention of IDH would dramatically improve the living conditions for patients with end stage renal disease. A recently published study suggests that a decrease in the envelope of the photoplethysmograpy (PPG) signal can be used for predicting acute symptomatic IDH. In the present study, the

Electrocardiogram derived respiration from QRS slopes : Evaluation with stress testing recordings

A method for respiratory rate estimation from electrocardiogram (ECG), based on variations in QRS complexes slopes, is evaluated over stress testing recordings. Besides the 12 standard, and the 3 vectorcardiogram (VCG), 2 additional leads derived from the VCG are analyzed. A total of 34 slope series were studied, 2 for each lead: slopes between the peaks of the Q and R waves, and between the peaks

Statistical modeling of the atrioventricular node during atrial fibrillation : Data length and estimator performance

The atrioventricular (AV) node plays a central role during atrial fibrillation (AF). We have recently proposed a statistical AV node model defined by parameters characterizing the arrival rate of atrial impulses, the probability of an impulse choosing either one of the dual AV nodal pathways, the refractory periods of the pathways, and the prolongation of refractory periods. All model parameters a

Seven-day analysis of atrial fibrillation and circadian rhythms

In the present work, f-wave morphology is characterized by principal component analysis and a novel temporal parameter defined by the cumulative normalized variance of the 3 largest principal components (r3). The 7-day behavior of persistent atrial fibrillation (AF) was studied in 9 patients using r3, AF frequency, and sample entropy (SampEn). Detection of circadian rhythms depended on the paramet

Reservoir computing for extraction of low amplitude atrial activity in atrial fibrillation

A novel method for QRST cancellation during atrial fibrillation (AF) is introduced for use in recordings with two or more leads. The method is based on an echo state neural network (ESN) which estimates the time-varying, nonlinear transfer function between two leads, one lead with atrial activity and another lead without, for the purpose of canceling ventricular activity. The performance is evalua

Heart rate variability during hemodialysis and its relation to hypotension

Acute hypotensive episodes are common during dialysis sessions, and represent a serious problem. Spectral analysis of heart rate variability (HRV) and barorrefle x sensitivity (BRS) is performed to study the behaviour of the autonomic nervous system (ANS) during the hemodialysis. The ratio between the low frequency (LF) and high frequency (HF) power of HRV, as well as BRS in the HF band, are signi

Detection of heart rate turbulence in photoplethysmographic signals

In this study, alterations in the cardiovascular system caused by ventricular premature beats (VPBs) are investigated by analyzing the photoplethysmographic (PPG) signal. A simple algorithm for PPG-based detection of VPBs is devised and evaluated, and then employed for the analysis of heart rate turbulence (HRT), here labelled "pulse rate turbulence" (PRT). The pulse transit time is also studied a

Risk stratification in congestive heart failure patients using a model-based approach to heart rate turbulence characterization

Heart rate turbulence (HRT) is commonly assessed by two parameters: turbulence onset (TO) and turbulence slope (TS), both obtained by averaging RR tachograms following a ventricular premature beat (VPB). It has been recently shown that a model-based detection-theoretical approach results in HRT indices outperforming TO/TS in identifying the presence or absence of HRT. The aim of this work is to ev

Exercise testing for non-invasive assessment of atrial electrophysiology in patients with persistent atrial fibrillation

The abstract with its heading should not be more than 75 mm long. This is equivalent to 18 lines of text. Leave 1 line space at the bottom of the abstract before continuing with the next heading. The autonomic nervous system modulates atrial electrophysiology in atrial fibrillation (AF). The purpose of this study was (1) to non-invasively characterize the effects of exercise on atrial fibrillatory

Från evidensbaserad medicin till kliniskt kunskapsstöd

Allmänmedicin är ett brett område som spänner över många sjukdomstillstånd, med fokus på patientcentrering. Inom många områden sker en snabb kunskapsutveckling och rekommendationer för utrednings- och behandlingsstrategier uppdateras hela tiden. För en allmänläkare kan det vara svårt att hålla sig uppdaterad och tidsbrist begränsar möjligheterna att leta kunskap i det dagliga kliniska arbetet. Dig

Regulation of norepinephrine transporter and tyrosine hydroxylase mRNAs after kainic acid-induced seizures

Noradrenergic locus coeruleus (LC) efferents to the forebrain suppress seizures in several models of epilepsy. Using in situ hybridization, we demonstrate that tyrosine hydroxylase (TH) and norepinephrine transporter (NET) but not vesicular monoamine transporter 2 (VMAT2) mRNA levels are transiently elevated in LC neurons following kainic acid-induced status epilepticus. These increases of TH and

Welfare State Supporter and Civil Society Activist: Church of Sweden in the “Refugee Crisis” 2015

2015 was a year of an unprecedented migration from the Middle East to Europe. Sweden received almost 163,000 asylum applications. The civil society, including the former state church, took a notable responsibility. In a situation where the welfare systems are increasingly strained, and both the welfare state and the majority church are re-regulated, we ask: how does this play out in local contexts

Suppression of epileptogenesis by modification of N-methyl-D-aspartate receptor subunit composition

The effects of altered N-methyl-D-aspartate (NMDA) receptor subunit composition on seizure development in kindling epilepsy were assessed in transgenic mice expressing high neuronal levels of NR2D under control of the calcium/calmodulin kinase II alpha subunit (αCaMKII) promoter. The NR2D subunit is normally present at very low levels in the mature forebrain. Transgenic mice showed a marked reduct