On-line coupling of size exclusion chromatography and capillary electrophoresis via solid-phase extraction and a Tee-split interface

An on-line size exclusion chromatography (SEC)-solid-phase extraction (SPE)-capillary electrophoresis (CE) system using a Tee-split interface has been developed for the analysis of peptides in biological fluids. The SEC column fractionates the sample by molecular size and the low-molecular-weight fraction, which contains the peptides, is directed to a C(18) SPE microcolumn, where the peptides are trapped and concentrated. The SPE column is desorbed with 425 nL acetonitrile and the effluent is sent to the Tee-split interface, which hydrodynamically splits (1:40) the flow and, thus, allows appropriate injection of analytes into the CE system. The performance of the system is investigated by the analysis of enkephalins in cerebrospinal fluid (CSF). It is demonstrated that the SEC step efficiently removes potentially interfering proteins, permitting reproducible SPE and CE. The total system provides efficient separations of the enkephalins with plate numbers up to 100,000. Concentration limits of detection (S/N = 3) for the peptides are about 100 ng/mL for injection of 20 microL spiked CSF samples. Plots of enkephalin peak areas versus concentration showed good linearity over the 0.25-10 microg/mL range (R2 > or = 0.985). Repeatability of migration time and peak area was within 2% and 10% R.S.D., respectively.     

Takotsubo cardiomyopathy complicated by cardiac tamponade

We describe a 76-year-old patient with takotsubo cardiomyopathy complicated by cardiac tamponade. Pericardial effusion in takotsubo cardiomyopthy is common but a cardiac tamponade is very rare. The use of anticoagulants may increase the risk of pericardial effusion and should be considered with care.     

Characterization of human placental alkaline phosphatase by activity and protein assays, capillary electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Placental alkaline phosphatase (PLAP) that had been isolated from human placenta was further purified using subsequent ion-exchange chromatography (IEC), affinity chromatography (AC) and centrifugal membrane concentration (CMC). During the process, the PLAP samples from the different stages of purification were characterized regarding purity and activity. This was accomplished by combining Lowry analysis, enzymatic activity assay, capillary zone electrophoresis (CZE), capillary gel electrophoresis (CGE) and matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF-MS). The sample obtained after IEC had a rather low specific activity (6.8 U/mg) and appeared to contain several major contaminants, among which was human serum albumin (HSA). AC followed by CMC yielded PLAP with a specific activity of 128 U/mg. The purity and identity of the protein was indicated by MALDI-TOF-MS yielding a spectrum with one major peak at m/z 58 101. Interestingly, CZE of the pure PLAP revealed a cluster of peaks, which probably reflects the presence of various glycoforms and/or oligomers. The same analytical approach was used to characterize commercially available PLAP. This sample showed a moderate specific activity (15 U/mg) and appeared to be highly impure containing various other proteins.     

Coronary computed tomographic angiography as gatekeeper for new-onset stable angina

Patients with new-onset stable angina constitute a substantial part of the population seen by cardiologists. Currently, the diagnostic workup of these patients depends on the pre-test probability of having obstructive coronary artery disease. It consists of either functional testing for myocardial ischaemia or anatomical testing by using coronary computed tomographic angiography (CCTA) or invasive coronary angiography. In case the pre-test probability is > 5%, the current guidelines for the management of chronic coronary syndromes do not state a clear preference for one of the noninvasive techniques. However, based on the recently published cost-effectiveness analysis of the PROMISE trial and considering the diagnostic yield in patients with angina and nonobstructive coronary artery disease, we argue a more prominent role for CCTA as a gatekeeper for patients with new-onset stable angina.     

Transduction of intracellular and intercellular dynamics in yeast glycolytic oscillations

Under certain well-defined conditions, a population of yeast cells exhibits glycolytic oscillations that synchronize through intercellular acetaldehyde. This implies that the dynamic phenomenon of the oscillation propagates within and between cells. We here develop a method to establish by which route dynamics propagate through a biological reaction network. Application of the method to yeast demonstrates how the oscillations and the synchronization signal can be transduced. That transduction is not so much through the backbone of glycolysis, as via the Gibbs energy and redox coenzyme couples (ATP/ADP, and NADH/NAD), and via both intra- and intercellular acetaldehyde.     

Metabolic profiling of human urine by CE-MS using a positively charged capillary coating and comparison with UPLC-MS

The potential of capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS) using capillaries coated with a triple layer of polybrene-dextran sulfate-polybrene (PB-DS-PB) was evaluated for metabolic profiling of human urine. The method covers various metabolite classes and stable metabolic profiles of urine samples were obtained with favourable migration time repeatability (RSDs <1%). The PB-DS-PB CE-TOF-MS method was used for the analysis of human urine samples from 30 males and 30 females, which had been previously analyzed by reversed-phase UPLC-TOF-MS. Multivariate data analysis of the obtained data provided clear distinction between urine samples from males and females, emphasizing gender differences in metabolic signatures. Nearly all compounds responsible for male-female classification in CE-TOF-MS were different from the classifying compounds in UPLC-TOF-MS. Almost all compounds causing classification in the CE-TOF-MS study were highly polar and did not exhibit retention in the reversed-phase UPLC system. In addition, the CE-TOF-MS classifiers had an m/z value in the range of 50-150, whereas 95% of the classifying features found with UPLC-TOF-MS had an m/z value above 150. The CE-TOF-MS method therefore appears to be highly complementary to the UPLC-TOF-MS method providing classification based on different classes of metabolites.     

The role of ECG screening in primary care; a call for collaboration between general practitioner and cardiologist

Netherlands Heart Journal -     

Retrocardiac mass causing collapse

A 78-year-old man with a history of hypertension presented to the emergency room after the sudden onset of near-collapse, dyspnoea, dizziness, and nausea. Symptoms had started while the patient was stooped over in an attempt to reach for an item underneath his bed. The patient reported upper abdominal pain, radiating to his back. Prior to his presenting symptoms he had no complaints, nor had he suffered from trauma.