How well does shear wave elastography predict elevated filling pressures? a comparison to the current guideline algorithm

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): University Hospitals (Uz) Leuven

Background

 

The assessment of left ventricular diastolic function is complex, as there is no single invasive parameter that provides a direct measurement of myocardial compliance, myocardial relaxation, or – as a surrogate - LV filling pressure. A combination of several parameters is therefore used to estimate the diastolic function.

Shear wave (SW) elastography is a novel method based on high frame rate echocardiography. SWs occur after mechanical excitation of the myocardium, e.g. after mitral valve closure (MVC), and their propagation velocity is directly related to myocardial stiffness (MS). The propagation velocity of SWs is directly related to myocardial stiffness and could be used for estimating left ventricular diastolic pressures.

Purpose

The aim of this study was to investigate if the MS at mid-diastole or end-diastole and the velocities of natural shear waves are related and, thus, could be used to estimate left ventricular end-diastolic pressures (LVEDP) as marker of diastolic function.

Methods

We prospectively enrolled 70 patients with a wide range of diastolic function, scheduled for heart catheterization so that LV mid diastolic filling pressures (LVMDP) and enddiastolic filling pressures (LVEDP) could be invasively measured (Panel B). Patients with dysfunction in the anteroseptal wall or regional myocardial abnormalities, as well as severe aortic stenosis, and a more than moderate mitral regurgitation were excluded.

Echocardiography was performed immediately after catheterization. SW elastography in parasternal long axis views of the left ventricle (LV) was performed using an experimental scanner (HD-PULSE) at 1050 ± 220 frames per second. Tissue acceleration maps were extracted from an anatomical M-mode line along the midline of the LV septum. The SW propagation velocity at MVC was measured as the slope on the M-mode acceleration map (Panel A). Standard echocardiographic parameters of diastolic function were obtained with a high end ultrasound machine. The Algorithm for evaluating diastolic dysfunction as recommended by the European Association of Cardiovascular Imaging Guidelines 2016 was used for estimating LVMDP.

Results

SW Velocity correlated better with LVMDP (AUC = 0.8, Sensitivity = 0.84, Specificity= 0.80;  =0.26; Panels C,E) than the Guideline approach (AUC = 0.67, Sensitivity = 0.33, Specificity = 1.00, Panel G). SWV showed the best results in predicting LVEDP (AUC = 0.94, Sensitivity = 0.92, Specificity = 0.89 and =0.56 (Panels D,F)).

Conclusions

Shear wave velocities, detected by high frame rate elastography, have a strong correlation with the end-diastolic filling pressure and allowed significantly better to differentiate normal from elevated filling pressure that current guideline recommended algorithms. This suggests a potential clinical value of the new method for the non-invasive assessment of diastolic function. Abstract Figure.  Abstract Figure.

Peri-operative COVID-19 infection in urgent elective surgery during a pandemic surge period: a retrospective observational cohort study

Maintaining safe elective surgical activity during the global coronavirus disease 2019 (COVID-19) pandemic is challenging and it is not clear how COVID-19 may impact peri-operative morbidity and mortality in this population. Therefore, adaptations to normal care pathways are required. Here, we establish if implementation of a bespoke peri-operative care bundle for urgent elective surgery during a pandemic surge period can deliver a low COVID-19-associated complication profile. We present a single-centre retrospective cohort study from a tertiary care hospital of patients planned for urgent elective surgery during the initial COVID-19 surge in the UK between 29 March and 12 June 2020. Patients asymptomatic for COVID-19 were screened by oronasal swab and chest imaging (chest X-ray or computed tomography if aged ≥ 18 years), proceeding to surgery if negative. COVID-19 positive patients at screening were delayed. Postoperatively, patients transitioning to COVID-19 positive status by reverse transcriptase polymerase chain reaction testing were identified by an in-house tracking system and monitored for complications and death within 30 days of surgery. Out of 557 patients referred for surgery (230 (41.3%) women; median (IQR [range]) age 61 (48-72 [1-89])), 535 patients (96%) had COVID-19 screening, of which 13 were positive (2.4%, 95%CI 1.4-4.1%). Out of 512 patients subsequently undergoing surgery, 7 (1.4%) developed COVID-19 positive status (1.4%, 95%CI 0.7-2.8%) with one COVID-19-related death (0.2%, 95%CI 0.0-1.1%) within 30 days. Out of these seven patients, four developed pneumonia, of which two required invasive ventilation including one patient with acute respiratory distress syndrome. Low rates of COVID-19 infection and mortality in the elective surgical population can be achieved within a targeted care bundle. This should provide reassurance that elective surgery can continue, where possible, despite high community rates of COVID-19.

Quantitative prediction of human pharmacokinetic responses to drugs via fluidically coupled vascularized organ chips

Analyses of drug pharmacokinetics (PKs) and pharmacodynamics (PDs) performed in animals are often not predictive of drug PKs and PDs in humans, and in vitro PK and PD modelling does not provide quantitative PK parameters. Here, we show that physiological PK modelling of first-pass drug absorption, metabolism and excretion in humans-using computationally scaled data from multiple fluidically linked two-channel organ chips-predicts PK parameters for orally administered nicotine (using gut, liver and kidney chips) and for intravenously injected cisplatin (using coupled bone marrow, liver and kidney chips). The chips are linked through sequential robotic liquid transfers of a common blood substitute by their endothelium-lined channels (as reported by Novak et al. in an associated Article) and share an arteriovenous fluid-mixing reservoir. We also show that predictions of cisplatin PDs match previously reported patient data. The quantitative in-vitro-to-in-vivo translation of PK and PD parameters and the prediction of drug absorption, distribution, metabolism, excretion and toxicity through fluidically coupled organ chips may improve the design of drug-administration regimens for phase-I clinical trials.

Robotic fluidic coupling and interrogation of multiple vascularized organ chips

Organ chips can recapitulate organ-level (patho)physiology, yet pharmacokinetic and pharmacodynamic analyses require multi-organ systems linked by vascular perfusion. Here, we describe an 'interrogator' that employs liquid-handling robotics, custom software and an integrated mobile microscope for the automated culture, perfusion, medium addition, fluidic linking, sample collection and in situ microscopy imaging of up to ten organ chips inside a standard tissue-culture incubator. The robotic interrogator maintained the viability and organ-specific functions of eight vascularized, two-channel organ chips (intestine, liver, kidney, heart, lung, skin, blood-brain barrier and brain) for 3 weeks in culture when intermittently fluidically coupled via a common blood substitute through their reservoirs of medium and endothelium-lined vascular channels. We used the robotic interrogator and a physiological multicompartmental reduced-order model of the experimental system to quantitatively predict the distribution of an inulin tracer perfused through the multi-organ human-body-on-chips. The automated culture system enables the imaging of cells in the organ chips and the repeated sampling of both the vascular and interstitial compartments without compromising fluidic coupling.

Succinate dehydrogenase mutations: paraganglioma imaging and at-risk population screening

Paragangliomas are rare vascular tumours of the autonomic nervous system. They can be classified as sympathetic or parasympathetic. Sympathetic paragangliomas, which include phaeochromocytomas, tend to be functional and symptomatic. Parasympathetic paragangliomas are usually non-functional and may present with mass effect. Forty percent of paragangliomas are linked to genetic syndromes, most commonly due to mutations of the succinate dehydrogenase (SDH) enzyme complex and are collectively known as paraganglioma syndromes, of which five are described. Genetic testing is recommended for all patients, and their first-degree relatives, diagnosed with paragangliomas. When SDH mutations are discovered, biochemical screening and imaging surveillance is indicated. There is currently no consensus on imaging surveillance protocols. Most advocate full-body imaging, but the choice of technique and frequency varies. If paragangliomas are demonstrated, functional imaging to look for synchronous tumours or metastases is indicated. 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron-emission tomography (PET)-computed tomography (CT) is the technique of choice for metastatic evaluation, but [¹²³I]-metaiodobenzylguanidine or [¹¹¹In]-DTPA-octreotide scintigraphy are also utilised. Current research into emerging positron-emitting radiolabelled somatostatin analogues have yielded promising results, which is likely to be reflected in future guidelines. As genetic testing becomes increasingly prevalent, the need to answer the remaining questions regarding surveillance imaging is paramount.

The Evolution of White Etching Cracks (WECs) in Rolling Contact Fatigue-Tested 100Cr6 Steel

The formation of white etching cracks (WECs) in steel rolling element bearings can lead to the premature rolling contact fatigue (RCF) failure mode called white structure flaking. Driving mechanisms are still debated but are proposed to be combinations of mechanical, tribochemical and electrical effects. A number of studies have been conducted to record and map WECs in RCF-tested samples and bearings failed from the field. For the first time, this study uses serial sectioning metallography techniques on non-hydrogen charged test samples over a range of test durations to capture the evolution of WEC formation from their initiation to final flaking. Clear evidence for subsurface initiation at non-metallic inclusions was observed at the early stages of WEC formation, and with increasing test duration the propagation of these cracks from the subsurface region to the contact surface eventually causing flaking. In addition, an increase in the amount of associated microstructural changes adjacent to the cracks is observed, this being indicative of the crack being a prerequisite of the microstructural alteration.

Thermal Desorption Analysis of Hydrogen in Non-hydrogen-Charged Rolling Contact Fatigue-Tested 100Cr6 Steel

Hydrogen diffusion during rolling contact fatigue (RCF) is considered a potential root cause or accelerator of white etching cracks (WECs) in wind turbine gearbox bearing steels. Hydrogen entry into the bearing steel during operation is thought to occur either through the contact surface itself or through cracks that breach the contact surface, in both cases by the decomposition of lubricant through catalytic reactions and/or tribochemical reactions of water. Thermal desorption analysis (TDA) using two experimental set-ups has been used to measure the hydrogen concentration in non-hydrogen-charged bearings over increasing RCF test durations for the first time. TDA on both instruments revealed that hydrogen diffused into the rolling elements, increasing concentrations being measured for longer test durations, with numerous WECs having formed. On the other hand, across all test durations, negligible concentrations of hydrogen were measured in the raceways, and correspondingly no WECs formed. Evidence for a relationship between hydrogen concentration and either the formation or the acceleration of WECs is shown in the rollers, as WECs increased in number and severity with increasing test duration. It is assumed that hydrogen diffusion occurred at wear-induced nascent surfaces or areas of heterogeneous/patchy tribofilm, since most WECs did not breach the contact surface, and those that did only had very small crack volumes for entry of lubricant to have occurred.

Early activation of microglia and astrocytes in mouse models of spinocerebellar ataxia type 1

Spinocerebellar ataxia type 1 (SCA1) is an incurable, dominantly inherited neurodegenerative disease of the cerebellum caused by a polyglutamine-repeat expansion in the protein ataxin-1 (ATXN1). While analysis of human autopsy material indicates significant glial pathology in SCA1, previous research has focused on characterizing neuronal dysfunction. In this study, we characterized astrocytic and microglial response in SCA1 using a comprehensive array of mouse models. We have discovered that astrocytes and microglia are activated very early in SCA1 pathogenesis even when mutant ATXN1 expression was limited to Purkinje neurons. Glial activation occurred in the absence of neuronal death, suggesting that glial activation results from signals emanating from dysfunctional neurons. Finally, in all different models examined glial activation closely correlated with disease progression, supporting the development of glial-based biomarkers to follow disease progression.

Tissue engineered tumor models

Many research programs use well-characterized tumor cell lines as tumor models for in vitro studies. Because tumor cells grown as three-dimensional (3-D) structures have been shown to behave more like tumors in vivo than do cells growing in monolayer culture, a growing number of investigators now use tumor cell spheroids as models. Single cell type spheroids, however, do not model the stromal-epithelial interactions that have an important role in controlling tumor growth and development in vivo. We describe here a method for generating, reproducibly, more realistic 3-D tumor models that contain both stromal and malignant epithelial cells with an architecture that closely resembles that of tumor microlesions in vivo. Because they are so tissue-like we refer to them as tumor histoids. They can be generated reproducibly in substantial quantities. The bioreactor developed to generate histoid constructs is described and illustrated. It accommodates disposable culture chambers that have filled volumes of either 10 or 64 ml, each culture yielding on the order of 100 or 600 histoid particles, respectively. Each particle is a few tenths of a millimeter in diameter. Examples of histological sections of tumor histoids representing cancers of breast, prostate, colon, pancreas and urinary bladder are presented. Potential applications of tumor histoids include, but are not limited to, use as surrogate tumors for pre-screening anti-solid tumor pharmaceutical agents, as reference specimens for immunostaining in the surgical pathology laboratory and use in studies of invasive properties of cells or other aspects of tumor development and progression. Histoids containing nonmalignant cells also may have potential as "seeds" in tissue engineering. For drug testing, histoids probably will have to meet certain criteria of size and tumor cell content. Using a COPAS Plus flow cytometer, histoids containing fluorescent tumor cells were analyzed successfully and sorted using such criteria.

Use of thromboelastometry in the assessment of coagulation before epidural insertion after massive transfusion

A British soldier presented to the UK Field Hospital, Afghanistan with bilateral traumatic lower limb amputations. Resuscitation and surgery followed accepted damage control principles. Blood component therapy was in keeping with UK military guidelines and included platelets and cryoprecipitate. The patient's trachea was extubated following insertion of an effective epidural. Ten days later, in the UK, he developed neurological symptoms and the presence of a subdural haematoma was confirmed on magnetic resonance imaging. Conventional laboratory coagulation results in this patient were above accepted limits for epidural insertion; however, thromboelastometry before insertion was suggestive of reduced platelet function. This case highlights the risk of relying solely on platelet count as a marker of platelet function following massive transfusion. Thromboelastometry provides additional information for the assessment of coagulation and should form part of the assessment of coagulation following massive transfusion before epidural insertion.

THE INFLUENCE OF SODIUM CHLORIDE AND TEMPERATURE ON THE ENDOGENOUS RESPIRATION OF B. CEREUS

Measurements were made of the rate of consumption of oxygen by suspensions of B. cereus, in sodium chloride solutions of concentration up to 1.8 M and over a range of pH from 6.0 to 7.5. It was found: 1. That the temperature coefficient was independent of the presence of sodium chloride in concentrations between 0.2 and 1.8 M, although the rate of respiration was lowered considerably under these conditions. 2. That in the presence of concentrations of sodium chloride less than 0.2 M, the rate of respiration was increased, and so was the temperature coefficient. 3. That small changes in the temperature coefficient occurred when the pH was changed. The temperature coefficient was higher the higher the rate of respiration. These data may be more readily interpreted by the hypothesis that the temperature coefficient is controlled by some master reaction, than by that which supposes that the temperature coefficient is determined by protoplasmic viscosity.

Effect of variation in CYP11B1 and CYP11B2 on corticosteroid phenotype and hypothalamic-pituitary-adrenal axis activity in hypertensive and normotensive subjects

BACKGROUND

Aldosterone is important in the development of hypertension. We have shown that a single nucleotide polymorphism (SNP) (-344T) in the 5' regulatory region (UTR) of the gene encoding aldosterone synthase (CYP11B2) associates with aldosterone excess and hypertension as well as altered adrenal 11-hydroxylation efficiency (deoxycortisol to cortisol). This conversion is carried out by the enzyme 11beta-hydroxylase, encoded by the adjacent gene, CYP11B1. We proposed that the effects of CYP11B2 are explained by linkage disequilibrium (LD) across the CYP11B locus. We have demonstrated high LD across this locus and identified two SNPs in the 5' UTR of CYP11B1 (-1859 G/T, -1889 A/G) that associate with reduced transcription in vitro and altered 11-hydroxylation efficiency in vivo. Accordingly, we hypothesized that the reduced adrenal 11-hydroxylation may lead to chronic resetting of the pituitary-adrenal axis, with chronically increased ACTH drive resulting in aldosterone excess.

METHODS

To test this, we examined hypothalamic-pituitary-adrenal (HPA) axis activity in hypertensive and normotensive individuals stratified according to genotype at CYP11B2 (-344T/C) and CYP11B1 (-1859 G/T, -1889 A/G). Fifty-six subjects homozygous for CYP11B2 SNP (27 TT, 12 CC), and 38 homozygous for CYP11B1 SNPs (18 TTGG, 20 GGAA) were recruited. Diurnal variation and the effects of dexamethasone suppression and ACTH stimulation on plasma aldosterone, cortisol and ACTH under controlled conditions were studied.

RESULTS

Subjects with SNPs associated with reduced 11-hydroxylation efficiency (-344T CYP11B2; TTGG CYP11B1) showed reduced inhibition of ACTH after dexamethasone (P = 0.05) and an altered cortisol-ACTH relationship (decreased cortisol-ACTH ratio, P < 0.02). The same individuals also demonstrated close correlations between plasma cortisol and aldosterone (-344T CYP11B2 r = 0.508, P < 0.004; TTGG CYP11B1 r = 0.563, P < 0.003) suggesting that there was common regulation (possibly ACTH) of these hormones in genetically susceptible subjects.

CONCLUSIONS

Variation in CYP11B2 and CYP11B1 associates with chronic up-regulation of the HPA axis. These novel data support the suggestion that chronic aldosterone excess, in genetically susceptible individuals, may be a consequence of increased ACTH drive to the adrenal and identify novel molecular mechanisms that may lead to the development of hypertension within the general population.

Phenotypic consequences of variation across the aldosterone synthase and 11-beta hydroxylase locus in a hypertensive cohort: data from the MRC BRIGHT Study

BACKGROUND

Aldosterone is an important cardiovascular hormone; 15% of hypertensive subjects have alteration in aldosterone regulation, defined by a raised ratio of aldosterone to renin (ARR). Studies of the aldosterone synthase gene (CYP11B2) have focused on a single nucleotide polymorphism in the 5'promoter region (-344 C/T). In normotensive subjects, the T allele associates with raised levels of the 11-deoxysteroids, deoxycorticosterone and 11-deoxycortisol which are substrates for 11beta-hydroxylase, encoded by the adjacent and homologous gene, CYP11B1. We have speculated that this altered 11beta-hydroxylase efficiency leads to increased ACTH drive to the adrenal gland to maintain cortisol production and reported herein the association between the -344 C/T single nucleotide polymorphism (SNP) and adrenal steroid production in subjects with essential hypertension.

METHODS

The CYP11B2-344 C/T polymorphism was genotyped and urinary excretion of adrenal steroid metabolites was measured (by GCMS) in 511 unrelated hypertensives from the Medical Research Council (MRC) British Genetics of Hypertension (BRIGHT) study.

RESULTS

Thirty-five per cent of subjects were homozygous for the -344T allele whilst 16% were CC homozygotes. There was no difference in cortisol excretion rate between the two genotype groups but the index of adrenal 11beta-hydroxylation (ratio of tetrahydrodeoxycortisol/total cortisol) was significantly higher in the TT group (P < 0.005) than in the CC group. Excretion rates of the major urinary metabolite of aldosterone (tetrahydroaldosterone) correlated strongly with the ACTH-regulated steroids, cortisol (r = 0.437, P < 0.0001) and total androgen metabolites (r = 0.4, P < 0.0001) in TT but not CC subjects.

CONCLUSIONS

Hypertensives homozygous for the -344 T allele of CYP11B2 demonstrate altered 11beta-hydroxylase efficiency (CYP11B1); this is consistent with the hypothesis of a genetically determined increase in adrenal ACTH drive in these subjects. The correlation between excretion of aldosterone and cortisol metabolites and suggests that, in TT subjects, ACTH exerts an important common regulatory influence on adrenal corticosteroid production in subjects with hypertension.

Safety and pharmacokinetics (PK) of AMG 706 in combination with panitumumab and gemcitabine-cisplatin in patients (pts) with advanced cancer

14057

Background: AMG 706 is an oral, investigational multikinase (MKI) inhibitor with antiangiogenic and direct antitumor activity that selectively targets VEGF, PDGF and Kit receptors. Methods: This is an ongoing phase 1b, open-label, dose-finding study of AMG 706 plus panitumumab and gemcitabine-cisplatin. Objectives are to establish the maximum tolerated dose and to assess safety, objective response and PK of AMG 706 with this regimen. Pts =18 yrs with advanced cancer, ECOG 0–1, =1 prior chemotherapy for advanced disease and no prior oral VEGFr MKIs or anti EGFR therapy, received panitumumab (9mg/kg IV day 1 of each 3-wk cycle) plus gemcitabine (1250mg/m2 IV days 1 and 8) and cisplatin (75mg/m2 IV day 1), and escalating doses of AMG 706 given continuously from day 1 of cycle 1. Assessments included dose-limiting toxicities (DLT; cycle 1), PK and tumor response (every 6–9 wks from wk 6). Results: As of Nov 2006, 36 pts (NSCLC n=19; pancreatic cancer n=4; other n=10; unknown primary n=3) were enrolled; 42% had prior chemotherapy. There was 1 DLT: pulmonary embolism, grade 5 (50mg QD). Selected treatment-related adverse events in =10% of pts are shown in the table . 39% of pts receiving AMG 706 had thromboembolic events (TE); 25% receiving study therapy without AMG 706 had TEs. There was 1 case of cholecystitis (grade 1), 1 of gallbladder pain (grade 3). Preliminary data showed that AMG 706 PK at 125 mg QD was comparable to data from monotherapy studies at the same dose level. Based on 29 pts with available response data (too early to evaluate/data unavailable n=7), objective tumor responses per RECIST were: CR n=1, 3% (breast cancer); PR n=9, 31% (NSCLC n=6; pancreatic cancer n=2; unknown primary n=1); SD n=17, 59%; PD n=1, 3%. Conclusions: In this study of pts with advanced cancer, AMG 706 was tolerable when combined with panitumumab and gemcitabine-cisplatin, with little effect on AMG 706 PK. Further studies need to determine if the observed TE rate exceeds gemcitabine-cisplatin background rates.

[Table: see text]

No significant financial relationships to disclose.

Endogenous corticosteroid biosynthesis in subjects after bilateral adrenalectomy

OBJECTIVE

Corticosteroids can be synthesized in extra-adrenal tissues but the contribution of this to circulating levels in humans is not known. Previous in vitro studies suggest that the 'hybrid' corticosteroid 18-oxocortisol (18-oxoF) is produced from cortisol by aldosterone synthase. We looked for evidence of extra-adrenal production of this and other corticosteroids in 10 subjects stable on long-term glucocorticoid replacement following bilateral adrenalectomy.

METHODS

In phase 1, patients were maintained on cortisol alone (30 mg/day), in phase 2 dexamethasone (2 mg/day), and in phase 3, both cortisol and dexamethasone. Each phase lasted 3 days.

MEASUREMENTS

On the last day of each phase, 24-h urine collection was performed for analysis of steroid metabolite excretion [using gas chromatography-mass spectrometry (GCMS)] and plasma aldosterone and renin were measured (by radioimmunoassay).

RESULTS

Cortisol metabolite excretion rate [tetrahydrocortisone (THE) + tetrahydrocortisol (THF) + allotetrahydrocortisol (aTHF)] fell from 9169 nmol/24 h in phase 1 to 22 nmol/24 h in phase 2, rising to 6843 nmol/24 h in phase 3. Tetrahydroaldosterone (THAldo) excretion was readily detectable and did not alter significantly between phases (26.5, 23.5 and 28.5 nmol/24 h, respectively; P = 0.474). 18-Hydroxycortisol (18-OHF) excretion was easily detectable in phases 1 and 3 (252.5 and 212 nmol/24 h), falling in phase 2 (12 nmol/24 h). 18-oxoF excretion rates were lower but followed a similar pattern (1.62, 0.085 and 1.785 nmol/24 h in phases 1, 2 and 3, respectively).

CONCLUSIONS

Significant levels of adrenal steroids are found in adrenalectomized subjects. We speculate that this occurs at extra-adrenal sites or in residual adrenal cortex tissue in an ACTH-independent manner. Our data suggest that aldosterone synthase, acting on cortisol, is the source of 18-oxoF and 18-OHF in these subjects. Further studies of corticosteroid production within adrenalectomized subjects, looking for evidence of adrenal regrowth or residual adrenal tissue, are justified.