No abstract

A prevalent challenge in isolating extracellular vesicles (EVs) from biological fluids is the reliable depletion of abundant contaminants-including free proteins and biomolecules, as well as nontarget vesicle subpopulations and other nanoparticulates-from the sample matrix while maximizing recovery. Sequential Filtration is a recently published approach for the size-based isolation of exosomes that is ideally suited for large-volume biofluid samples such as ascites , urine , lavage fluid, or cell-conditioned media. We describe a straightforward, three-step protocol comprising back-to-back steps of dead-end (normal) filtration, tangential-flow filtration, and track-etched membrane filtration that can be applied to yield a homogeneous population of exosome-sized extracellular vesicles. The approach is scalable and employs relatively gentle manipulation forces to fractionate and concentrate extracellular vesicles with good purity and functional integrity.

ABSTRACT

Background It is suspected that microbiome-derived trimethylamine N-oxide (TMAO) may enhance platelet responsiveness and accordingly be thrombophilic. The purpose of this prospective observational study is to evaluate TMAO in patients with subarachnoid hemorrhage (SAH) and compare it with a control group. A secondary aim was to investigate TMAO in the cerebrospinal fluid (CSF) from SAH patients. This should provide a better understanding of the role of TMAO in the pathogenesis of SAH and its thrombotic complications. Methods The study included patients with diagnosed spontaneous SAH recruited after initial treatment on admission and patients with nerve, nerve root, or plexus disorders serving as controls. Blood samples were gathered from all patients at recruitment. Additionally, sampling of SAH patients in the intensive care unit continued daily for 14 days. The CSF was collected out of existing external ventricular drains whenever possible. Results Thirty-four patients diagnosed with SAH, and 108 control patients participated in this study. Plasma TMAO levels at baseline were significantly lower in the SAH group (1.7 μmol/L) compared to the control group (2.9 μmol/L). TMAO was detectable in the CSF (0.4 μmol/L) and significantly lower than in plasma samples of the SAH group at baseline. Plasma and CSF TMAO levels correlated positively. The TMAO levels did not differ significantly during the observation period of 15 days. Conclusions Although we assumed that patients with higher TMAO levels were at higher risk for SAH a priori, plasma TMAO levels were lower in patients with SAH compared with control subjects with nerve, nerve root, or plexus disorders on admission to the hospital. A characteristic pattern of plasma TMAO levels in patients with SAH was not found.

Metabolic myopathies are heterogeneous hereditary diseases affecting skeletal muscle energy supply. Symptoms usually comprise pain, cramps, hypotonia, weakness, and myoglobinuria.We present a boy with recurrent myalgia and weakness after some minutes of exercise or during febrile infections since early infancy. First laboratory workup at the age of 9 years showed no abnormalities, apart from a slightly elevated creatine kinase. After exclusion of common structural and metabolic myopathies, next generation sequencing panel (4 years after the initial diagnostic metabolic workup) revealed two potentially pathogenic missense mutations in the CPT2 gene (c.149C > A (p.P50H) and c.1459G > A (p.E487K)).Our case underscores the clinical variability of muscle carnitine palmitoyltransferase II (CPT II) deficiency and illustrates a pitfall of diagnostic algorithms for metabolic myopathies. Myalgia following exercise of a few minutes duration would have argued for a carbohydrate and against a fatty acid metabolic defect. However, CPT II deficiency is the most common disorder of muscle fatty acid metabolism and should be considered even in atypical scenarios. Analyses of plasma acyl carnitine profile during acute metabolic crises may help to unmask biochemical markers which are often overlooked in dried-blood analyses.