Within-breath dynamics of atelectrauma during mechanical ventilation studied by in vivo 4D microscopy in injured rabbit lung

SummaryWe examined the anticoagulant activity of two major molecules of soluble thrombomodulin purified from human urine. The apparent molecular weights of these urinary thrombomodulins (UTMs) were 72,000 and 79,000, respectively. Both UTMs showed more potent cofactor activity for protein C activation [specific activity >5,000 thrombomodulin units (TMU)/mg] than human placental thrombomodulin (2,180 TMU/mg) and rabbit lung thrombomodulin (1,980 TMU/mg). The UTMs prolonged thrombin-induced fibrinogen clotting time (>1 TMU/ml), APTT (>5 TMU/ml), TT (>5 TMU/ml) and PT (>40 TMU/ml) in a dose-dependent fashion. These effects appeared in the concentration range of soluble thrombomodulins present in human plasma and urine. In the rat DIC model induced by thromboplastin, administration of UTMs by infusion (300-3,000 TMU/kg) restored the hematological abnormalities derived from DIC in a dose-dependent fashion. These results demonstrate that UTMs exhibit potent anticoagulant and antithrombotic activities, and could play a physiologically important role in microcirculation.

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In vivo tumour imaging employing regional delivery of novel gallium radiolabelled polymer composites

Biomaterials Research ◽

10.1186/s40824-021-00210-0 ◽

2021 ◽

Vol 25 (1) ◽

Author(s):

Ross W. Stephens ◽

Gregory D. Tredwell ◽

Jessica L. Bell ◽

Karen J. Knox ◽

Lee A. Philip ◽

...

Keyword(s):

Normal Liver ◽

Ct Imaging ◽

Liver Imaging ◽

Polymer Microspheres ◽

Tumour Imaging ◽

Planar Imaging ◽

Rabbit Lung ◽

Vitro Binding

Abstract Background Understanding the regional vascular delivery of particles to tumour sites is a prerequisite for developing new diagnostic and therapeutic composites for treatment of oncology patients. We describe a novel imageable 67Ga-radiolabelled polymer composite that is biocompatible in an animal tumour model and can be used for preclinical imaging investigations of the transit of different sized particles through arterial networks of normal and tumour-bearing organs. Results Radiolabelling of polymer microspheres with 67Ga was achieved using a simple mix and wash method, with tannic acid as an immobilising agent. Final in vitro binding yields after autoclaving averaged 94.7%. In vivo stability of the composite was demonstrated in New Zealand white rabbits by intravenous administration, and intrahepatic artery instillations were made in normal and VX2 tumour implanted rabbit livers. Stability of radiolabel was sufficient for rabbit lung and liver imaging over at least 3 hours and 1 hour respectively, with lung retention of radiolabel over 91%, and retention in both normal and VX2 implanted livers of over 95%. SPECT-CT imaging of anaesthetised animals and planar imaging of excised livers showed visible accumulation of radiolabel in tumours. Importantly, microsphere administration and complete liver dispersal was more easily achieved with 8 μm diameter MS than with 30 μm MS, and the smaller microspheres provided more distinct and localised tumour imaging. Conclusion This method of producing 67Ga-radiolabelled polymer microspheres is suitable for SPECT-CT imaging of the regional vascular delivery of microspheres to tumour sites in animal models. Sharper distinction of model tumours from normal liver was obtained with smaller MS, and tumour resolution may be further improved by the use of 68Ga instead of 67Ga, to enable PET imaging.

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Further pharmacological evaluation of a novel synthetic peptide bradykinin B2 receptor agonist

Biological Chemistry ◽

10.1515/hsz-2012-0295 ◽

2013 ◽

Vol 394 (3) ◽

pp. 353-360 ◽

Cited By ~ 9

Author(s):

Martin Savard ◽

Julie Labonté ◽

Céléna Dubuc ◽

Witold Neugebauer ◽

Pedro D’Orléans-Juste ◽

...

Keyword(s):

Knockout Mice ◽

Synthetic Peptide ◽

Receptor Agonist ◽

Rabbit Lung ◽

Hypotensive Action ◽

Duration Of Action ◽

Selective Agonist ◽

Comparable Magnitude

Abstract We recently identified a novel human B2 receptor (B2R) agonist [Hyp3,Thi5,NChg7,Thi8]-bradykinin (NG291) with greater in vitro and in vivo potency and duration of action than natural bradykinin (BK). Here, we further examined its stability and selectivity toward B2R. The hypotensive, antithrombotic, and profibrinolytic functions of NG291 relative to BK and its analogue ([Hyp3,Thi5,(4-Me)Tyr8(ΨCH2NH)Arg9]-BK) (RMP-7) were also tested. Contraction assays using isolated mouse stomachs (containing kinin B1R, B2R, and kininase I- and II-like activities) showed that NG291 is a more potent contractant than BK and is inhibited by HOE-140 (B2R antagonist) but unaffected by R954 (B1R antagonist), whereas both decreased the potency of BK. In stomach tissues from B2R knockout mice, BK maintained its activity via B1R, whereas NG291 had no contractile effect, indicating that it was selective for B2R. Unlike BK, NG291 was not degraded by rabbit lung ACE. Comparing intravenously administered BK and NG291 revealed that NG291 exhibited more potent and prolonged hypotensive action and greater antithrombotic and profibrinolytic activities. These effects were of comparable magnitude to RMP-7 and were absent in B2R knockout mice. We concluded that NG291 is a novel biostable B2R-selective agonist that may prove suitable for investigating the (pre)clinical cardioprotective efficacy of B2R activation.

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Novel activity of angiotensin-converting enzyme. Hydrolysis of cholecystokinin and gastrin analogues with release of the amidated C-terminal dipeptide

Biochemical Journal ◽

10.1042/bj2620125 ◽

1989 ◽

Vol 262 (1) ◽

pp. 125-130 ◽

Cited By ~ 39

Author(s):

P Dubreuil ◽

P Fulcrand ◽

M Rodriguez ◽

H Fulcrand ◽

J Laur ◽

...

Keyword(s):

Angiotensin Converting Enzyme ◽

Chloride Ion ◽

Peptide Bond ◽

Major Product ◽

Enzyme Hydrolysis ◽

Ion Concentration ◽

Converting Enzyme ◽

Rabbit Lung ◽

Hydrolysis Of

ACE (angiotensin-converting enzyme; peptidyl dipeptidase A; EC 3.4.15.1), cleaves C-terminal dipeptides from active peptides containing a free C-terminus. We investigated the hydrolysis of cholecystokinin-8 [CCK-8; Asp-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2] and of various gastrin analogues by purified rabbit lung ACE. Although these peptides are amidated at their C-terminal end, they were metabolized by ACE to several peptide fragments. These fragments were analysed by h.p.l.c., isolated and identified by comparison with synthetic fragments, and by amino acid analysis. The initial and major site of hydrolysis was the penultimate peptide bond, which generated a major product, the C-terminal amidated dipeptide Asp-Phe-NH2. As a secondary cleavage, ACE subsequently released di- or tri-peptides from the C-terminal end of the remaining N-terminal fragments. The cleavage of CCK-8 and gastrin analogues was inhibited by ACE inhibitors (Captopril and EDTA), but not by other enzyme inhibitors (phosphoramidon, thiorphan, bestatin etc.). Hydrolysis of [Leu15]gastrin-(14-17)-peptide [Boc (t-butoxycarbonyl)-Trp-Leu-Asp-Phe-NH2] in the presence of ACE was found to be dependent on the chloride-ion concentration. Km values for the hydrolysis of CCK-8, [Leu15]gastrin-(11-17)-peptide and Boc-[Leu15]gastrin-(14-17)-peptide at an NaCl concentration of 300 mM were respectively 115, 420 and 3280 microM, and the catalytic constants were about 33, 115 and 885 min-1. The kcat/Km for the reactions at 37 degrees C was approx. 0.28 microM-1.min-1, which is approx. 35 times less than that reported for the cleavage of angiotensin I. These results suggest that ACE might be involved in the metabolism in vivo of CCK and gastrin short fragments.

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Individual Airway Closure Characterized In Vivo by Phase-Contrast CT Imaging in Injured Rabbit Lung*

Critical Care Medicine ◽

10.1097/ccm.0000000000003838 ◽

2019 ◽

Vol 47 (9) ◽

pp. e774-e781 ◽

Cited By ~ 10

Author(s):

Ludovic Broche ◽

Pauline Pisa ◽

Liisa Porra ◽

Loïc Degrugilliers ◽

Alberto Bravin ◽

...

Keyword(s):

Phase Contrast ◽

Ct Imaging ◽

Airway Closure ◽

Rabbit Lung ◽

Contrast Ct

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Nanoparticle delivery of microRNA-146a regulates mechanotransduction in lung macrophages and mitigates lung injury during mechanical ventilation

10.1101/796557 ◽

2019 ◽

Author(s):

Christopher Bobba ◽

Qinqin Fei ◽

Vasudha Shukla ◽

Hyunwook Lee ◽

Pragi Patel ◽

...

Keyword(s):

Mechanical Ventilation ◽

Lung Injury ◽

Therapeutic Potential ◽

Compensatory Response ◽

Nanoparticle Delivery ◽

Biophysical Forces ◽

Delivery Platform ◽

In Vitro Systems

ABSTRACTDuring mechanical ventilation, injurious biophysical forces exacerbate lung injury. These forces disrupt alveolar capillary barrier integrity, trigger proinflammatory mediator release, and differentially regulate genes and non-coding oligonucleotides such as microRNAs. In this study, we identify miR-146a as a mechanosensitive microRNA in alveolar macrophages that has therapeutic potential to mitigate lung injury during mechanical ventilation. We used humanized in-vitro systems, mouse models, and biospecimens from mechanically ventilated patients to elucidate the expression dynamics of miR-146a that might be required to decrease lung injury during mechanical ventilation. We found that the endogenous increase in miR-146a following injurious was relatively modest and not sufficient to prevent lung injury. However, when miR-146a was highly overexpressed using a nanoparticle-based delivery platform in vivo, it was sufficient to prevent lung injury. These data indicate that the endogenous increase in microRNA-146a during MV is a compensatory response that only partially limits VILI and that nanoparticle delivery approaches that significantly over-express microRNA-146a in AMs is an effective strategy for mitigating VILI.

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In vivo regional diaphragm function in dogs

Journal of Applied Physiology ◽

10.1152/jappl.1989.67.2.655 ◽

1989 ◽

Vol 67 (2) ◽

pp. 655-662 ◽

Cited By ~ 20

Author(s):

J. Sprung ◽

C. Deschamps ◽

R. D. Hubmayr ◽

B. J. Walters ◽

J. R. Rodarte

Keyword(s):

Mechanical Ventilation ◽

Chest Wall ◽

Spontaneous Breathing ◽

Considerable Variability ◽

Diaphragm Function ◽

Left Hemidiaphragm ◽

Anesthetized Dogs ◽

Abdominal Surface ◽

Crural Diaphragm

A biplane videofluorographic system was used to track the position of metallic markers affixed to the abdominal surface of the left hemidiaphragm in supine anesthetized dogs. Regional shortening was determined from intermarker distances of rows of markers placed along muscle bundles in the ventral, middle, and dorsal regions of the costal diaphragm and of one row on the crural diaphragm. Considerable variability of regional shortening was seen in a given row, which was reproducible on repeat study in individual dogs but which differed between mechanical ventilation and spontaneous breathing. There were no consistent patterns among dogs. Regional shortening obtained from the change in length of rows extending from chest wall to central tendon showed no consistent differences among dogs during spontaneous breathing. At equal tidal volumes, all regions (except the ventral costal diaphragm) shortened more during spontaneous breathing than during mechanical ventilation.

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