The Mitral/Aortic Flow Velocity Integral Ratio in Mitral Regurgitation.

The development of echocardiography was driven, in part, by a need to diagnose mitral regurgitation in patients undergoing finger fracture commissurotomy in the 1950s. Decades later, color Doppler became the cornerstone for noninvasive evaluation of mitral regurgitation. The authors present 2 cases of calcific mitral stenosis in which reliance on color Doppler in transthoracic echocardiography resulted in erroneous conclusions as to the severity of coexisting mitral regurgitation. The possible application of the Mitral to Aortic Flow Velocity Integral Ratio in such cases as a possible adjunct to grading mitral regurgitation is also discussed.

Labor Analgesia Onset With Dural Puncture Epidural Versus Traditional Epidural Using a 26-Gauge Whitacre Needle and 0.125% Bupivacaine Bolus: A Randomized Clinical Trial.

BACKGROUND: Lumbar epidurals (LEs) provide excellent analgesia. Combined spinal epidural and dural puncture epidural (DPE) are 2 techniques to expedite neuraxial analgesia onset. In DPE, dura is punctured but medication is not administered in the cerebrospinal fluid. Expedited analgesia onset has been demonstrated with DPE, using 0.25% bupivacaine; however, this concentration may impede an unassisted vaginal birth and is not currently used for induction and maintenance of labor analgesia. The primary goal of this study was to compare the percentage of patients who achieved adequate labor analgesia following DPE or LE with an epidural bolus of 0.125% bupivacaine. Adequate labor analgesia was defined as Visual Analog Scale (VAS) measurement ≤ 10 mm on a 100-mm scale during active contractions, measured 10 minutes after epidural bolus initiation. METHODS: Laboring patients were randomly assigned to receive LE or DPE. Immediately before epidural placement, subjects marked a VAS score during an active contraction and parturients with VAS < 50 mm were excluded. The epidural space was identified by a loss of resistance technique to saline (17G Tuohy needle [Arrow International, Inc, Redding, PA]). In the DPE group, dura was punctured with a 26G Whitacre needle (Arrow International, Inc). In all participants, a 19G epidural catheter (Arrow International, Inc) was inserted. An epidural bolus was then administered over 3 minutes (12 mL, 0.125% bupivacaine, 50 µg fentanyl) followed by infusion (0.1% bupivacaine, 2 µg/mL fentanyl). After initiation of epidural bolus (time zero), VAS measurements were collected at 2-minute intervals for up to 20 minutes. Median time to achieve adequate analgesia by treatment group was assessed by Kaplan-Meier analysis. Time to achieving adequate analgesia was evaluated using a Cox regression model. All analyses were conducted in SAS version 9.4. (SAS Institute, Cary, NC) RESULTS:: Data were analyzed from 80 participants (40 per group). Adequate analgesia at 10 minutes did not differ by neuraxial technique (DPE = 55.3% vs LE = 44.7%; P= .256). However, parturients receiving DPE had shorter median times to adequate analgesia (median [95% confidence interval], 8 minutes [6-10] vs 10 minutes [8-14]) and a 67% increase in the relative risk of achieving adequate analgesia compared to LE (relative risk = 1.67; 95% confidence interval, 1.02-2.64; P= .042). CONCLUSIONS: Although the percentage of parturients achieving adequate labor analgesia at 10 minutes after epidural bolus did not differ by technique, DPE was associated with faster time to VAS ≤ 10 mm compared with LE.

Economic and health impact modelling of a whole genome sequencing-led intervention strategy for bacterial healthcare-associated infections for England and for the USA.

Bacterial healthcare-associated infections (HAIs) are a substantial source of global morbidity and mortality. The estimated cost associated with HAIs ranges from $35 to $45 billion in the USA alone. The costs and accessibility of whole genome sequencing (WGS) of bacteria and the lack of sufficiently accurate, high-resolution, scalable and accessible analysis for strain identification are being addressed. Thus, it is timely to determine the economic viability and impact of routine diagnostic bacterial genomics. The aim of this study was to model the economic impact of a WGS surveillance system that proactively detects and directs interventions for nosocomial infections and outbreaks compared to the current standard of care, without WGS. Using a synthesis of published models, inputs from national statistics, and peer-reviewed articles, the economic impacts of conducting a WGS-led surveillance system addressing the 11 most common nosocomial pathogen groups in England and the USA were modelled. This was followed by a series of sensitivity analyses. England was used to establish the baseline model because of the greater availability of underpinning data, and this was then modified using USA-specific parameters where available. The model for the NHS in England shows bacterial HAIs currently cost the NHS around £3 billion. WGS-based surveillance delivery is predicted to cost £61.1 million associated with the prevention of 74 408 HAIs and 1257 deaths. The net cost saving was £478.3 million, of which £65.8 million were from directly incurred savings (antibiotics, consumables, etc.) and £412.5 million from opportunity cost savings due to re-allocation of hospital beds and healthcare professionals. The USA model indicates that the bacterial HAI care baseline costs are around $18.3 billion. WGS surveillance costs $169.2 million, and resulted in a net saving of ca.$3.2 billion, while preventing 169 260 HAIs and 4862 deaths. From a 'return on investment' perspective, the model predicts a return to the hospitals of £7.83 per £1 invested in diagnostic WGS in the UK, and US$18.74 per $1 in the USA. Sensitivity analyses show that substantial savings are retained when inputs to the model are varied within a wide range of upper and lower limits. Modelling a proactive WGS system addressing HAI pathogens shows significant improvement in morbidity and mortality while simultaneously achieving substantial savings to healthcare facilities that more than offset the cost of implementing diagnostic genomics surveillance.

PEGylation of a maltose biosensor promotes enhanced signal response when immobilized in a silica sol-gel.

A robust method to immobilize a maltose biosensor is described using an engineered maltose periplasmic binding protein (PBP) covalently coupled to NBDamide, an environmentally sensitive fluorophore. A mesoporous silica sol-gel derived from diglycerylsilane (DGS) was constructed to embed the maltose biosensor, and the ligand reporting fluorescence properties were measured. When sequestered in the DGS-derived silica matrix, the biosensor retained maltose-dependent fluorescence sensing capability with micromolar affinity, which is consistent with the protein free in solution. The MBP-NBD conjugate was further modified by covalent conjugation with poly(ethylene glycol)-5000 (PEG) to promote the retention of water molecules around the protein and to reduce possible steric effects between the silica matrix and protein. Bioconjugation with PEG molecules does not significantly affect the signaling response of the protein in solution. When immobilized in the DGS polymer, a consistent increase in fluorescence intensity was observed as compared to the protein not functionalized with PEG. To our knowledge, this report presents the first successful method to embed a PBP biosensor in a polymerized matrix and retain signaling response using an environmentally sensitive probe. The immobilization method presented here should be easily adaptable to all conformation-dependent biosensors.

Analysis of ligand binding to a ribose biosensor using site-directed mutagenesis and fluorescence spectroscopy.

Computational design of proteins with altered ligand specificity is an emerging method for the creation of new biosensing systems. In this work, we investigated the outcome of site-directed mutagenesis on the Escherichia coli ribose binding protein (RBP), which is frequently used as a design scaffold for computational searches. A ribose biosensor was first constructed whereby an environmentally sensitive fluorescent probe was covalently attached to RBP at position S265C. This protein conjugate displayed a 54% decrease in emission intensity upon the addition of saturating ribose concentrations and exhibited an apparent dissociation constant (K(d) ) of 3.4 microM. Site-directed mutants within the RBP binding pocket were created and examined for ribose binding ability and overall structural stability. Because as many as 12 mutations are needed to alter ligand specificity in RBP, we measured the effect of single and multiple alanine mutations on stability and signal transduction potential of the ribose biosensor. Single alanine mutations had significant impact on both stability and signaling. Mutations of N190A and F214A each produced melting temperatures >8 degrees C below those observed for the wild-type protein. Residue Q235, located in the hinge region of RBP, appeared to be a hot spot for global protein stability as well. Additional single alanine mutations demonstrated as much as 200-fold increase in apparent K(d) but retained overall protein stability. The data collected from this study may be incorporated into design algorithms to help create more stable biosensors and optimize signal transduction properties for a variety of important analytes.