How to mitigate the risk of psychological injury to COVID-19 frontline workers

Jennifer Brown and Yvonne Shell discuss the possibility of healthcare workers experiencing post-traumatic stress disorder and other similar conditions as a result of dealing with COVID-19. They write that the antidote includes clarity in chain of command, effective supplies of equipment, and good communication

Diagnosis of pancreatic disease in feline platynosomosis

Objectives: Platynosomum species are cat-specific parasitic trematodes that parasitize the biliary ducts and gall bladder. Due to the common connection to the major duodenal papilla of the pancreas and common bile ducts in addition to the periductal proximity of the pancreas, it is possible that platynosomosis could cause pancreatitis. The objective of this study was to determine whether platynosomosis, a commonly diagnosed parasitic disease in cats on St Kitts, has any association with pancreatic disease. Methods: To investigate this possibility, the pancreas of free-roaming cats with naturally acquired platynosomosis were evaluated via ultrasound, serum concentrations of feline pancreatic lipase (fPL), cobalamin, folate and feline trypsin-like immunoreactivity (fTLI) and histopathology. Twenty free-roaming, young adult, feral cats, positive for feline immunodeficiency virus, and diagnosed with Platynosomum species infection via fecal analysis were recruited. The liver, biliary system and pancreas were evaluated via ultrasonography during a short duration anesthesia. Serum concentrations of fPL, fTLI, folate and cobalamin were measured. Sections of the right limb, left limb and body of the pancreas were evaluated histopathologically using hematoxylin and eosin (H&E) stain. Results: None of the cats had sufficient criteria to fulfill the ultrasonographic diagnosis of pancreatitis. One cat had an elevated fPL concentration in the range consistent with pancreatitis. Four cats had cobalamin deficiencies and 11 had abnormal folate concentration. The fTLI concentration was equivocal for the diagnosis of exocrine pancreatic insufficiency in one cat. With a single exception, histopathology changes, when present (n = 12), were mild, non-specific and predominantly characterized by lymphocytic infiltrates and fibrosis. The exception was a cat that presented a chronic interstitial and eosinophilic pancreatitis of slightly increased severity, likely the result of platynosomosis. Conclusions and relevance: The results of this study suggest that platynosomosis rarely induces pancreatic damage in cats. With only one exception, chronic pancreatitis diagnosed in cats with fluke-induced cholangitis and cholangiohepatitis was subtle and interpreted as an incidental background lesion unrelated to platynosomosis

Defending Helen Archer – marital rape and the role of expert testimony in cases involving domestic abuse

Jennifer Brown, Jeannie Mackie and Yvonne Shell offer psychological, legal and clinical commentary on the Helen Archer (Titchener) attempted murder trial as portrayed in Radio 4’s The Archers. The complexities of the case are discussed in light of the apparent initial unwillingness of the defendant to provide full details of the domestic abuse she suffered at the hands of her husband

Lockdown: a death trap for the domestically abused?

Jennifer Brown, Terri Cole, and Yvonne Shell look at reports of increased domestic violence arising from the coronavirus lockdowns and provide some possible explanations and options

Workflow for real-time in-vivo Cherenkov-excited luminescence imaging during radiotherapy

Radiotherapy is a common method for treating tumors, however, radiosensitivity can vary between tumor types or within the tumor microenvironment. The ability to deliver oxygen is crucial for the generation of reactive oxygen species resulting in increased localized cytotoxic effects. Alternatively, hypoxic tumors are thought to indicate a poor prognosis and may benefit from more aggressive treatments, yet identifying tumor hypoxia early in the course of a multi-week fractionated dose regimen is currently impractical. Using a time-gated imaging system and oxygen-sensitive phosphorescent compound (PtG4) we are able to estimate in vivo pO2 distribution at a rate of 2.6 estimates per second, which corresponds to 50+ values during a common 2Gy dose fraction. While our previous work has reported using Cherenkov-excited luminescence to estimate in vivo pO2 during external beam radiotherapy, the dose required was often greater than a standard fraction and camera acquisition parameters required modification during treatments, resulting in interrupted workflows. The current method utilizes custom control software which cycles through camera timing parameters during acquisition. Python code using the web-based user interface JupyterLab allows for interactive analysis of the resulting image stack without the need to pay expensive licensing fees for scientific computing packages. Using open source libraries, the analysis code is able to split the image stack into respective Cherenkov excitation and phosphorescence images, which can then be further automatically segmented to find regions of interest including the subject and phosphorescent region. The intensity of the regions in the phosphorescence images are used to estimate the compound lifetime, which can then be used in the Stern-Volmer relationship to estimate pO2. This entire process does not compromise clinical workflow and is able to provide a pO2 estimate within minutes after delivering the fractionated dose, providing clinicians early feedback about trends in tumor hypoxia. The current method has been validated with both direct injection of 50mM PtG4 in Matrigel in a mouse flank, and 24hrs post IV injection of mouse with MDA-MB-231 tumor implanted in the flank. The mouse with the direct injection was imaged under anesthesia and while awake and mobile to test the ability of the automated segmentation algorithm (Figure below). While the signal from the IV injection was less intense, simultaneous imaging using the previously reported method and current method resulted in similar lifetime estimates. While oxygen-sensitive PtG4 exhibits a lifetime between 16ms under atmospheric oxygen and 47ms when deprived of oxygen, other compounds have also been investigated. Europium chelate nanoparticle (~600ms), Iridium-based small molecules (~5ms), Si nanoparticles (~60ms), and UV-sensitive tattoo inks (~15ms) have all been imaged using Cherenkov-excitation. Camera time-gating can be utilized to discriminate these compound when mixed in the same field, allowing for additional tools in the realm of contrast enhancement during radiotherapy imaging. Ongoing studies with PtG4 and other compounds are being conducted to further improve system sensitivity and refine imaging workflows so they are more clinically translatable. Please click Additional Files below to see the full abstract

Proteolytic Regulation of the Mitochondrial cAMP-Dependent Protein Kinase

The mitochondrial cAMP-dependent protein kinase (PKA) is activatable in a cAMP-independent fashion. The regulatory (R) subunits of the PKA holoenzyme (R2C2), but not the catalytic (C) subunits, suffer proteolysis upon exposure of bovine heart mitochondria to digitonin, Ca2+, and a myriad of electron transport inhibitors. Selective loss of both the RI- and RII-type subunits was demonstrated via western blot analysis and activation of the C subunit was revealed by phosphorylation of a validated PKA peptide substrate. Selective proteolysis transpires in a calpain-dependent fashion as demonstrated by exposure of the R and C subunits of PKA to calpain and by attenuation of R and C subunit proteolysis in the presence of calpain inhibitor I. By contrast, exposure of mitochondria to cAMP fails to promote R subunit degradation, although it does result in enhanced C subunit catalytic activity. Treatment of mitochondria with electron transport chain inhibitors rotenone, antimycin A, sodium azide, and oligomycin, as well as an uncoupler of oxidative phosphorylation, also elicits enhanced C subunit activity. These results are consistent with the notion that signals, originating from cAMP-independent sources, elicit enhanced mitochondrial PKA activity

Probes of the mitochondrial cAMP-dependent protein kinase

The development of a fluorescent assay to detect activity of the mitochondrial cAMP-dependent protein kinase (PKA) is described. A peptide-based sensor was utilized to quantify the relative amount of PKA activity present in each compartment of the mitochondria (the outer membrane, the intermembrane space, and the matrix). In the process of validating this assay, we discovered that PKA activity is regulated by the protease calpain. Upon exposure of bovine heart mitochondria to digitonin, Ca2+, and a variety of electron transport chain inhibitors, the regulatory subunits of the PKA holoenzyme (R2C2) are digested, releasing active catalytic subunits. This proteolysis is attenuated by calpain inhibitor I (ALLN)

Tunable Visible and Near-IR Photoactivation of Light-Responsive Compounds by Using Fluorophores as Light-Capturing Antennas

Although the corrin ring of vitamin B12 is unable to efficiently absorb light beyond 550 nm, it is shown that commercially available fluorophores can be used as antennas to capture long-wavelength light to promote scission of the Co-C bond at wavelengths up to 800 nm. The ability to control the molecular properties of bioactive species with long visible and near-IR light has implications for drug delivery, nanotechnology, and the spatiotemporal control of cellular behavior

Signal Intensity Analysis and Optimization for in Vivo Imaging of Cherenkov and Excited Luminescence.

During external beam radiotherapy (EBRT), in vivo Cherenkov optical emissions can be used as a dosimetry tool or to excite luminescence, termed Cherenkov-excited luminescence (CEL) with microsecond-level time-gated cameras. The goal of this work was to develop a complete theoretical foundation for the detectable signal strength, in order to provide guidance on optimization of the limits of detection and how to optimize near real time imaging. The key parameters affecting photon production, propagation and detection were considered and experimental validation with both tissue phantoms and a murine model are shown. Both the theoretical analysis and experimental data indicate that the detection level is near a single photon-per-pixel for the detection geometry and frame rates commonly used, with the strongest factor being the signal decrease with the square of distance from tissue to camera. Experimental data demonstrates how the SNR improves with increasing integration time, but only up to the point where the dominance of camera read noise is overcome by stray photon noise that cannot be suppressed. For the current camera in a fixed geometry, the signal to background ratio limits the detection of light signals, and the observed in vivo Cherenkov emission is on the order of 100×  stronger than CEL signals. As a result, imaging signals from depths  \u3c 15 mm is reasonable for Cherenkov light, and depths  \u3c 3 mm is reasonable for CEL imaging. The current investigation modeled Cherenkov and CEL imaging of two oxygen sensing phosphorescent compounds, but the modularity of the code allows for easy comparison of different agents or alternative cameras, geometries or tissues

Suborganelle Sensing of Mitochondrial cAMP-Dependent Protein Kinase Activity

A fluorescent sensor of protein kinase activity has been developed and used to characterize the compartmentalized location of cAMP-dependent protein kinase activity in mitochondria. The sensor functions via a phosphorylation-induced release of a quencher from a peptide-based substrate, producing a 150-fold enhancement in fluorescence. The quenching phenomenon transpires via interaction of the quencher with Arg residues positioned on the peptide substrate. Although the cAMP-dependent protein kinase is known to be present in mitochondria, the relative amount of enzyme positioned in the major compartments (outer membrane, intermembrane space, and the matrix) of the organelle is unclear. The fluorescent sensor developed in this study was used to reveal the relative matrix:intermembrane space:outer membrane (85:6:9) distribution of PKA in bovine heart mitochondria