The NAPRESSIM trial: the use of low-dose,prophylactic naloxone infusion to prevent respiratory depression with intrathecally administered morphine in elective hepatobiliary surgery: a study protocol and statistical analysis plan for a randomised controlled trial

Background

Intrathecally administered morphine is effective as part of a postoperative analgesia regimen following major hepatopancreaticobiliary surgery. However, the potential for postoperative respiratory depression at the doses required for effective analgesia currently limits its clinical use. The use of a low-dose, prophylactic naloxone infusion following intrathecally administered morphine may significantly reduce postoperative respiratory depression. The NAPRESSIM trial aims to answer this question.

Methods/design

‘The use of low-dose, prophylactic naloxone infusion to prevent respiratory depression with intrathecally administered morphine’ trial is an investigator-led, single-centre, randomised, double-blind, placebo-controlled, double-arm comparator study. The trial will recruit 96 patients aged?>?18 years, undergoing major open hepatopancreaticobiliary resections, who are receiving intrathecally administered morphine as part of a standard anaesthetic regimen. It aims to investigate whether the prophylactic administration of naloxone via intravenous infusion compared to placebo will reduce the proportion of episodes of respiratory depression in this cohort of patients.Trial patients will receive an infusion of naloxone or placebo, commenced within 1 h of postoperative extubation continued until the first postoperative morning. The primary outcome is the rate of respiratory depression in the intervention group as compared to the placebo group. Secondary outcomes include pain scores, rates of nausea and vomiting, pruritus, sedation scores and adverse outcomes. We will also employ a novel, non-invasive, respiratory minute volume monitor (ExSpiron 1Xi, Respiratory Motion, Inc., 411 Waverley Oaks Road, Building 1, Suite 150, Waltham, MA, USA) to assess the monitor’s accuracy for detecting respiratory depression.

Discussion

The trial aims to provide a clear management plan to prevent respiratory depression after the intrathecal administration of morphine, and thereby improve patient safety.

Trial registration

ClinicalTrials.gov, ID: NCT02885948. Registered retrospectively on 4 July 2016.Protocol Version 2.0, 3 April 2017.Protocol identification (code or reference number): UCDCRC/15/006EudraCT registration number: 2015-003504-22. Registered on 5 August 2015.

     

Comparative review of human and canine osteosarcoma: morphology,epidemiology, prognosis,treatment and genetics

Osteosarcoma (OSA) is a rare cancer in people. However OSA incidence rates in dogs are 27 times higher than in people. Prognosis in both species is relatively poor, with 5 year OSA survival rates in people not having improved in decades. For dogs, 1 year survival rates are only around ~ 45%. Improved and novel treatment regimens are urgently required to improve survival in both humans and dogs with OSA. Utilising information from genetic studies could assist in this in both species, with the higher incidence rates in dogs contributing to the dog population being a good model of human disease. This review compares the clinical characteristics, gross morphology and histopathology, aetiology, epidemiology, and genetics of canine and human OSA. Finally, the current position of canine OSA genetic research is discussed and areas for additional work within the canine population are identified.     

Systemic application of the transient receptor potential vanilloid-type 4 antagonist GSK2193874 induces tail vasodilation in a mouse model of thermoregulation

In humans, skin is a primary thermoregulatory organ, with vasodilation leading to rapid body cooling, whereas in Rodentia the tail performs an analogous function. Many thermodetection mechanisms are likely to be involved including transient receptor potential vanilloid-type 4 (TRPV4), an ion channel with thermosensitive properties. Previous studies have shown that TRPV4 is a vasodilator by local action in blood vessels, so here, we investigated whether constitutive TRPV4 activity affects Mus muscularis tail vascular tone and thermoregulation. We measured tail blood flow by pressure plethysmography in lightly sedated M. muscularis (CD1 strain) at a range of ambient temperatures, with and without intraperitoneal administration of the blood–brain barrier crossing TRPV4 antagonist GSK2193874. We also measured heart rate (HR) and blood pressure. As expected for a thermoregulatory organ, we found that tail blood flow increased with temperature. However, unexpectedly, we found that GSK2193874 increased tail blood flow at all temperatures, and we observed changes in HR variability. Since local TRPV4 activation causes vasodilation that would increase tail blood flow, these data suggest that increases in tail blood flow resulting from the TRPV4 antagonist may arise from a site other than the blood vessels themselves, perhaps in central cardiovascular control centres.     

Microphysiological system for studying contractile differences in young,active, and old,sedentary adult derived skeletal muscle cells

Microphysiological systems (MPS), also referred to as tissue chips, incorporating 3D skeletal myobundles are a novel approach for physiological and pharmacological studies to uncover new medical treatments for sarcopenia. We characterize a MPS in which engineered skeletal muscle myobundles derived from donor‐specific satellite cells that model aged phenotypes are encapsulated in a perfused tissue chip platform containing platinum electrodes. Our myobundles were derived from CD56⁺ myogenic cells obtained via percutaneous biopsy of the vastus lateralis from adults phenotyped by age and physical activity. Following 17 days differentiation including 5 days of a 3 V, 2 Hz electrical stimulation regime, the myobundles exhibited fused myotube alignment and upregulation of myogenic, myofiber assembly, signaling and contractile genes as demonstrated by gene array profiling and localization of key components of the sarcomere. Our results demonstrate that myobundles derived from the young, active (YA) group showed high intensity immunofluorescent staining of α‐actinin proteins and responded to electrical stimuli with a ~1 μm displacement magnitude compared with non‐stimulated myobundles. Myobundles derived from older sedentary group (OS) did not display a synchronous contraction response. Hypertrophic potential is increased in YA‐derived myobundles in response to stimulation as shown by upregulation of insulin growth factor (IGF‐1), α‐actinin (ACTN3, ACTA1) and fast twitch troponin protein (TNNI2) compared with OS‐derived myobundles. Our MPS mimics disease states of muscle decline and thus provides an aged system and experimental platform to investigate electrical stimulation mimicking exercise regimes and may be adapted to long duration studies of compound efficacy and toxicity for therapeutic evaluation against sarcopenia.     

Efficient purification and kinetic characterization of a bimodular derivative of the erythromycin polyketide synthase.

Modular polyketide synthases (PKSs), such as the 6-deoxyerythronolide B synthase (DEBS), are giant multienzymes that biosynthesize a number of clinically important natural products. The modular nature of PKSs suggests the possibility of a combinatorial approach to the synthesis of novel bioactive polyketides, but the efficacy of such a strategy depends critically on gaining fundamental insight into PKS structure and function, most directly through experiments with purified PKS proteins. Several recent investigations into important aspects of the activity of these enzymes have used only partially purified proteins (often 3-4% of total protein), reflecting how difficult it is to purify these multienzymes in amounts adequate for kinetic and structural analysis. We report here the steady-state kinetic analysis of a typical bimodular PKS, 6-deoxyerythronolide B synthase 1-thioesterase (DEBS 1-TE), purified from recombinant Saccharopolyspora erythraea JCB101 by a new, high-yielding procedure consisting of three steps: ammonium sulfate precipitation, hydrophobic interaction chromatography and size-exclusion chromatography. The method provides 13-fold purification with a recovery of 11% of the applied PKS activity. The essentially homogeneous synthase exhibits an intrinsic methylmalonyl-CoA hydrolase activity, which competes with polyketide chain extension. The most reliable value for the kcat for synthesis of (3S,5R)-dihydroxy-(2R,4R)-dimethyl-n-heptanoic acid-delta-lactone is 0.84 min-1, and the apparent Km for (2RS)-methylmalonyl-CoA is 17 microM. This kcat is approximately 10-fold lower than the value reported previously for a differently engineered version of the truncated PKS, DEBS 1+TE. The difference likely reflects the fact that the DEBS 1-TE contains a hybrid acyl carrier protein (ACP) domain in its second module, which lowers its catalytic efficiency.     

Talin1 regulates integrin turnover to promote embryonic epithelial morphogenesis

Talin is a cytoskeletal protein that binds to integrin β cytoplasmic tails and regulates integrin activation. Talin1 ablation in mice disrupts gastrulation and causes embryonic lethality. However, the role of talin in mammalian epithelial morphogenesis is poorly understood. Here we demonstrate that embryoid bodies (EBs) differentiated from talin1-null embryonic stem cells are defective in integrin adhesion complex assembly, epiblast elongation, and lineage differentiation. These defects are accompanied by a significant reduction in integrin β1 protein levels due to accelerated degradation through an MG-132-sensitive proteasomal pathway. Overexpression of integrin β1 or MG-132 treatment in mutant EBs largely rescues the phenotype. In addition, epiblast cells isolated from talin1-null EBs exhibit impaired cell spreading and focal adhesion formation. Transfection of the mutant cells with green fluorescent protein (GFP)-tagged wild-type but not mutant talin1 that is defective in integrin binding normalizes integrin β1 protein levels and restores focal adhesion formation. Significantly, cell adhesion and spreading are also improved by overexpression of integrin β1. All together, these results suggest that talin1 binding to integrin promotes epiblast adhesion and morphogenesis in part by preventing integrin β1 degradation.     

Molecular genetic and biochemical analyses of FGF23 mutations in familial tumoral calcinosis

Fibroblast growth factor 23 (FGF23) is a hormone required for normal renal phosphate reabsorption. FGF23 gain-of-function mutations result in autosomal dominant hypophosphatemic rickets (ADHR), and FGF23 loss-of-function mutations cause familial hyperphosphatemic tumoral calcinosis (TC). In this study, we identified a novel recessive FGF23 TC mutation, a lysine (K) substitution for glutamine (Q) (160 C>A) at residue 54 (Q54K). To understand the molecular consequences of all known FGF23-TC mutants (H41Q, S71G, M96T, S129F, and Q54K), these proteins were stably expressed in vitro. Western analyses revealed minimal amounts of secreted intact protein for all mutants, and ELISA analyses demonstrated high levels of secreted COOH-terminal FGF23 fragments but low amounts of intact protein, consistent with TC patients' FGF23 serum profiles. Mutant protein function was tested and showed residual, yet decreased, bioactivity compared with wild-type protein. In examining the role of the FGF23 COOH-terminal tail (residues 180-251) in protein processing and activity, truncated mutants revealed that the majority of the residues downstream from the known FGF23 SPC protease site ((176)RXXR(179)/S(180)) were not required for protein secretion. However, residues adjacent to the RXXR site (between residues 188 and 202) were required for full bioactivity. In summary, we report a novel TC mutation and demonstrate a common defect of reduced FGF23 stability for all known FGF23-TC mutants. Finally, the majority of the COOH-terminal tail of FGF23 is not required for protein secretion but is required for full bioactivity.     

How a Plant Builds Leaves

A leaf develops from a few cells that grow, divide, and differentiate to form a complex organ that is precisely positioned relative to its neighbors. How cells communicate to achieve such coordinated growth and development is the focus of this review. We discuss (1) how the stem cells within the shoot meristem gain competence to form organs, (2) what determines the positioning and initiation of new organs, and (3) how the new organ attains its characteristic shape and polarity. Special emphasis is given to the recent integration of mathematics and physics in the study of leaf development.     

Outcomes from international field trials with Male Aedes Sound Traps: Frequency-dependent effectiveness in capturing target species in relation to bycatch abundance

Aedes aegypti and Aedes albopictus vector dengue, chikungunya and Zika viruses. With both species expanding their global distributions at alarming rates, developing effective surveillance equipment is a continuing priority for public health researchers. Sound traps have been shown, in limited testing, to be highly species-specific when emitting a frequency corresponding to a female mosquito wingbeat. Determining male mosquito capture rates in sound traps based on lure frequencies in endemic settings is the next step for informed deployment of these surveillance tools. We field-evaluated Male Aedes Sound Traps (MASTs) set to either 450 Hz, 500 Hz, 550 Hz or 600 Hz for sampling Aedes aegypti and/or Aedes albopictus and compared catch rates to BG-Sentinel traps within Pacific (Madang, Papua New Guinea) and Latin American (Molas, Mexico and Orange Walk Town, Belize) locations. MASTs set to 450–550 Hz consistently caught male Ae. aegypti at rates comparable to BG-Sentinel traps in all locations. A peak in male Ae. albopictus captures in MASTs set at 550 Hz was observed, with the lowest mean abundance recorded in MASTs set to 450 Hz. While significantly higher abundances of male Culex were sampled in MASTs emitting lower relative frequencies in Molas, overall male Culex were captured in significantly lower abundances in the MASTs, relative to BG-Sentinel traps within all locations. Finally, significant differences in rates at which male Aedes and Culex were positively detected in trap-types per weekly collections were broadly consistent with trends in abundance data per trap-type. MASTs at 550 Hz effectively captured both male Ae. aegypti and Ae. albopictus while greatly reducing bycatch, especially male Culex, in locations where dengue transmission has occurred. This high species-specificity of the MAST not only reduces staff-time required to sort samples, but can also be exploited to develop an accurate smart-trap system—both outcomes potentially reducing public health program expenses.