Functional consequences of sphingomyelinase-induced changes in erythrocyte membrane structure.

Inflammation enhances the secretion of sphingomyelinases (SMases). SMases catalyze the hydrolysis of sphingomyelin into phosphocholine and ceramide. In erythrocytes, ceramide formation leads to exposure of the removal signal phosphatidylserine (PS), creating a potential link between SMase activity and anemia of inflammation. Therefore, we studied the effects of SMase on various pathophysiologically relevant parameters of erythrocyte homeostasis. Time-lapse confocal microscopy revealed a SMase-induced transition from the discoid to a spherical shape, followed by PS exposure, and finally loss of cytoplasmic content. Also, SMase treatment resulted in ceramide-associated alterations in membrane-cytoskeleton interactions and membrane organization, including microdomain formation. Furthermore, we observed increases in membrane fragility, vesiculation and invagination, and large protein clusters. These changes were associated with enhanced erythrocyte retention in a spleen-mimicking model. Erythrocyte storage under blood bank conditions and during physiological aging increased the sensitivity to SMase. A low SMase activity already induced morphological and structural changes, demonstrating the potential of SMase to disturb erythrocyte homeostasis. Our analyses provide a comprehensive picture in which ceramide-induced changes in membrane microdomain organization disrupt the membrane-cytoskeleton interaction and membrane integrity, leading to vesiculation, reduced deformability, and finally loss of erythrocyte content. Understanding these processes is highly relevant for understanding anemia during chronic inflammation, especially in critically ill patients receiving blood transfusions

New approaches to predicting the risk of sudden death.

In this review article, we will explore some of the contemporary methods for predicting sudden cardiac death (SCD). These include experimental methods yet to be adopted in the clinical setting, and methods that have been extrapolated from observational data in those with a history of SCD. We will discuss how these relate to the different aetiologies and disease processes. We will also explore how these may be used in the clinical setting to decide on management

Effective extraction and filtering of frequency components in physiological signals using sum-of-sinusoids modelling

In biological signal processing, modelling and extraction of specific frequency components constitute an important procedure for filtering signal components of interest as well as artefact removal. Under some interference scenarios, a satisfactory elimination of artefacts from the signal must be even performed by subtraction of an artefact waveform model or template, rather than the use of linear band-pass filters. That is the case of the gradient artefact induced in the EEG within the fMRI scanner, which cannot be characterized by a specific bandwidth or spectral content. This paper presents a simple and accurate approach based upon sum-of-sinusoids modelling for signal and artefact frequency components representation in physiological signals. According to the proposed method, each signal frequency component is approximated as a sinusoid, whose amplitude and phase parameters are estimated by making use of the Discrete Fourier Transform (DFT). The proposed approach reveals to perform an effective modelling and extraction of ECG signal components as well as underlying gradient artefacts in the EEG signal

Systematic review of effects of current transtibial prosthetic socket designs—Part 1: Qualitative outcomes

This review is an attempt to untangle the complexity of transtibial prosthetic socket fit, determine the most important characteristic for a successful fitting, and perhaps find some indication of whether a particular prosthetic socket type might be best for a given situation. Further, it is intended to provide directions for future research. We followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and used medical subject headings and standard key words to search for articles in relevant databases. No restrictions were made on study design or type of outcome measure. From the obtained search results (n = 1,863), 35 articles were included. The relevant data were entered into a predefined data form that incorporated the Downs and Black risk of bias assessment checklist. Results for the qualitative outcomes (n = 19 articles) are synthesized. Total surface bearing sockets lead to greater activity levels and satisfaction in active persons with amputation, those with a traumatic cause of amputation, and younger persons with amputation than patellar tendon bearing sockets. Evidence on vacuum-assisted suction and hydrostatic sockets is inadequate, and further studies are much needed. To improve the scientific basis for prescription, comparison of and correlation between mechanical properties of interface material, socket designs, user characteristics, and outcome measures should be conducted and reported in future studies

Systematic review of effects of current transtibial prosthetic socket designs—Part 2: Quantitative outcomes

This review is an attempt to untangle the complexity of transtibial prosthetic socket fit and perhaps find some indication of whether a particular prosthetic socket type might be best for a given situation. In addition, we identified knowledge gaps, thus providing direction for possible future research. We followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, using medical subject headings and standard key words to search for articles in relevant databases. No restrictions were made on study design and type of outcome measure used. From the obtained search results (n = 1,863), 35 articles were included. The relevant data were entered into a predefined data form that included the Downs and Black risk of bias assessment checklist. This article presents the results from the systematic review of the quantitative outcomes (n = 27 articles). Trends indicate that vacuum-assisted suction sockets improve gait symmetry, volume control, and residual limb health more than other socket designs. Hydrostatic sockets seem to create less inconsistent socket fittings, reducing a problem that greatly influences outcome measures. Knowledge gaps exist in the understanding of clinically meaningful changes in socket fit and its effect on biomechanical outcomes. Further, safe and comfortable pressure thresholds under various conditions should be determined through a systematic approach

Event-related desynchronization related to the anticipation of a stimulus providing knowledge of results

In the present paper, event-related desynchronization (ERD) in the alpha and beta frequency bands is quantified in order to investigate the processes related to the anticipation of a knowledge of results (KR) stimulus. In a time estimation task, 10 subjects were instructed to press a button 4 s after the presentation of an auditory stimulus. Two seconds after the response they received auditory or visual feedback on the timing of their response. Preceding the button press, a centrally maximal ERD is found. Preceding the visual KR stimulus, an ERD is present that has an occipital maximum. Contrary to expectation, preceding the auditory KR stimulus there are no signs of a modalityspecific ERD. Results are related to a thalamo-cortical gating model which predicts a correspondence between negative slow potentials and ERD during motor preparation and stimulus anticipation