Use of point-of-care lung ultrasonography in the critical care setting as an aid to identifying the correct diagnosis in an acutely desaturating patient with COVID-19-related acute respiratory distress syndrome.

A 64-year-old man was intubated and ventilated for COVID-19-associated acute respiratory distress syndrome. He had a background history of chronic obstructive pulmonary disease and ischaemic heart disease. His oxygen saturations dropped rapidly to 80% on day 9 of ICU admission. Chest auscultation revealed absent breath sounds over the left upper chest which raised suspicions for pneumothorax, of which a small stable left apical pneumothorax was documented on a recent CT scan of the thorax. Point-of-care ultrasonography was performed prior to attempting chest drain insertion which demonstrated sliding pleura on the left side (GE Healthcare model: Vscan Extend-display: 5 inches, 720×1280 pixels resolution, sector probe-broad bandwidth: 1.7-3.8 MHz, 24 cm penetration and linear probe-broad bandwidth: 3.3-8 MHz, 8 cm penetration). A portable chest X-ray was obtained which demonstrated left upper lobe collapse secondary to mucus plugging. The mucus plug was successfully suctioned from the patient's airway using bedside bronchoscopy subsequently improving the patient's oxygen saturation. A follow-up chest X-ray and CT scan of the thorax demonstrated interval resolution of the left upper lobe collapse. While expansion of his existing pneumothorax was first on the list of differential diagnoses, the use of ultrasonography early in the patient's assessment ensured it was ruled out prior to attempting chest drain insertion, thus prompting the acquisition of the chest X-ray which subsequently demonstrated the left upper lobe collapse as the correct diagnosis.

Precipitation and selective extraction of human serum endogenous peptides with analysis by quadrupole time-of-flight mass spectrometry reveals posttranslational modifications and low-abundance peptides.

The endogenous peptides of human serum may have regulatory functions, have been associated with physiological states, and their modifications may reveal some mechanisms of disease. In order to correlate levels of specific peptides with disease alongside internal standards, the polypeptides must first be reliably extracted and identified. Endogenous blood peptides can be effectively enriched by precipitation of the serum with organic solvents followed by selective extraction of peptides using aqueous solutions modified with organic solvents. Polypeptides on filter paper were assayed with Coomasie brilliant blue binding. The polypeptides were resolved by detergent tricine polyacrylamide electrophoresis and visualized by diamine silver staining. Peptides in the extracts were collected by C18 and analyzed by matrix-assisted laser desorption/ionization and liquid chromatography-electrospray ionization-tandem mass spectrometry (MS/MS) quadrupole time-of-flight MS/MS. Peptides were resolved as multiple isotopic peaks in MS mode with mass deviation of 0.1 Da or less and similar accuracy for fragments. The sensitivity of MS and MS/MS analysis was estimated to be in the picomolar range or less. The peptide composition of the extracts was dependent on solvent formulation. Multiple peptides from apolipoproteins, complement proteins, coagulation factors, and many others were identified by X!Tandem with high mass accuracy of peptide ions and fragments from collision-induced dissociation. Many previously unreported posttranslational modifications of peptides including phosphorylations, oxidations, glycosylations, and others were detected with high mass accuracy and may be of clinical importance. About 4,630 redundant peptides were identified with 99% confidence separately, and together some 1,251 distinct proteins were identified with 99% confidence or greater using the Paragon algorithm.

Optimization of a series of multi-isoform PI3 kinase inhibitors.

Optimization of the cellular and pharmacological activity of a novel series of PI3 kinase inhibitors targeting multiple isoforms is described.

Achieving multi-isoform PI3K inhibition in a series of substituted 3,4-dihydro-2H-benzo[1,4]oxazines.

The SAR and pharmacokinetic profiles of a series of multi-isoform PI3K inhibitors based on a 3,4-dihydro-2H-benzo[1,4]oxazine scaffold are disclosed.

AP and vacuum MALDI on a QqLIT instrument.

This article presents a comparative study of the performance, operational, and instrumental characteristics of AP and vacuum MALDI for the analysis of peptides and protein digests. Spectra generated with the two ion sources were surprisingly similar, both qualitatively and quantitatively, with vacuum MALDI generating ion count rates that were approximately a factor of 2 greater than those generated with AP MALDI on this system. Even though the peptide signals were 2X greater with vacuum MALDI, the background intensities also increased by a similar amount, leading to approximately equivalent signal/background ratios for digests and peptide mixtures. The results suggest that when AP MALDI conditions are properly optimized, the sensitivity can approach that of vacuum MALDI. However, AP MALDI performance is critically affected by source gas flows, potentials, and temperature, making it operationally more complex. In addition, evidence is provided for thermal degradation of samples stored on a target plate within a heated AP MALDI ion source. An improved interface for atmosphere to vacuum ion transfer substantially improved these characteristics.

Endogenous peptides from biophysical and biochemical fractionation of serum analyzed by matrix-assisted laser desorption/ionization and electrospray ionization hybrid quadrupole time-of-flight.

Blood peptides can be concentrated, extracted, and analyzed with strong signal-to-noise ratios by precipitation in organic solvents followed by extraction in water. Matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) hybrid quadrupole time-of-flight (Qq-TOF) were used to analyze the precipitated and extracted endogenous peptides from fetal calf serum. C18 solid-phase extraction with or without prior precipitation in ammonium sulfate, size exclusion chromatography, dealbuminization, dye affinity chromatography, ultrafiltration, and differential precipitation in organic solvents were compared. Hundreds of different ions could be observed by MALDI in the various fractions. It appeared that some peptides were freely dissolved and that not all peptides in blood were obliged to remain bound to albumin or other high-molecular-mass proteins. Mass spectra with high signal-to-noise ratios were obtained from polypeptides precipitated with organic solvents followed by extraction of the peptides from the pellet with water. The peptides extracted from organic precipitates were analyzed by nano liquid chromatography (LC)-ESI-Qq-TOF. In addition to many commonly abundant serum proteins, apparent low-abundance peptides associated with cancer biology from proteins such as insulin-like growth factor II, thymosin beta4 and beta9, plasminogen, coagulation factors, and extracellular matrix protein 1 were observed.

Abundance ratio-dependent proteomic analysis by mass spectrometry.

The goal of quantitative proteomics is to determine the identity and relative quantity of each protein present in two or more complex protein samples. Here we describe a novel approach to quantitative proteomics. It is based on a highly accurate algorithm for the automated quantification of chromatographically fractionated, isotope-coded affinity-tagged peptides and MALDI quadrupole time-of-flight tandem mass spectrometry for their identification. The method is capable of detecting and selectively identifying those proteins within a complex mixture that show a difference in relative abundance. We demonstrate the effectiveness and the versatility of this approach in the analysis of a standard protein mixture, protein expression profiling in a human prostate cancer cell line model, and identification of the specific components of the multiprotein transcriptional machinery in S. cerevisiae.