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result(s) for
"Millar, Jonathan"
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The inflammatory response to extracorporeal membrane oxygenation (ECMO): a review of the pathophysiology
by
McAuley, Daniel F.
,
McDonald, Charles I.
,
Fanning, Jonathon P.
in
Blood oxygenation, Extracorporeal
,
Critical care
,
Critical Care Medicine
2016
Extracorporeal membrane oxygenation (ECMO) is a technology capable of providing short-term mechanical support to the heart, lungs or both. Over the last decade, the number of centres offering ECMO has grown rapidly. At the same time, the indications for its use have also been broadened. In part, this trend has been supported by advances in circuit design and in cannulation techniques. Despite the widespread adoption of extracorporeal life support techniques, the use of ECMO remains associated with significant morbidity and mortality. A complication witnessed during ECMO is the inflammatory response to extracorporeal circulation. This reaction shares similarities with the systemic inflammatory response syndrome (SIRS) and has been well-documented in relation to cardiopulmonary bypass. The exposure of a patient’s blood to the non-endothelialised surface of the ECMO circuit results in the widespread activation of the innate immune system; if unchecked this may result in inflammation and organ injury. Here, we review the pathophysiology of the inflammatory response to ECMO, highlighting the complex interactions between arms of the innate immune response, the endothelium and coagulation. An understanding of the processes involved may guide the design of therapies and strategies aimed at ameliorating inflammation during ECMO. Likewise, an appreciation of the potentially deleterious inflammatory effects of ECMO may assist those weighing the risks and benefits of therapy.
Journal Article
Monopolin Subunit Csm1 Associates with MIND Complex to Establish Monopolar Attachment of Sister Kinetochores at Meiosis I
by
Newnham, Louise
,
Sarkar, Sourav
,
Hoffmann, Eva
in
Biology
,
Casein Kinase I - genetics
,
Casein Kinase I - metabolism
2013
Sexually reproducing organisms halve their cellular ploidy during gametogenesis by undergoing a specialized form of cell division known as meiosis. During meiosis, a single round of DNA replication is followed by two rounds of nuclear divisions (referred to as meiosis I and II). While sister kinetochores bind to microtubules emanating from opposite spindle poles during mitosis, they bind to microtubules originating from the same spindle pole during meiosis I. This phenomenon is referred to as mono-orientation and is essential for setting up the reductional mode of chromosome segregation during meiosis I. In budding yeast, mono-orientation depends on a four component protein complex referred to as monopolin which consists of two nucleolar proteins Csm1 and Lrs4, meiosis-specific protein Mam1 of unknown function and casein kinase Hrr25. Monopolin complex binds to kinetochores during meiosis I and prevents bipolar attachments. Although monopolin associates with kinetochores during meiosis I, its binding site(s) on the kinetochore is not known and its mechanism of action has not been established. By carrying out an imaging-based screen we have found that the MIND complex, a component of the central kinetochore, is required for monopolin association with kinetochores during meiosis. Furthermore, we demonstrate that interaction of monopolin subunit Csm1 with the N-terminal domain of MIND complex subunit Dsn1, is essential for both the association of monopolin with kinetochores and for monopolar attachment of sister kinetochores during meiosis I. As such this provides the first functional evidence for a monopolin-binding site at the kinetochore.
Journal Article
Dynamic data-driven meta-analysis for prioritisation of host genes implicated in COVID-19
by
Russell, Clark D.
,
Baillie, J. Kenneth
,
Head Fourman, Max
in
631/208/248
,
631/250
,
631/250/255
2020
The increasing body of literature describing the role of host factors in COVID-19 pathogenesis demonstrates the need to combine diverse, multi-omic data to evaluate and substantiate the most robust evidence and inform development of therapies. Here we present a dynamic ranking of host genes implicated in human betacoronavirus infection (SARS-CoV-2, SARS-CoV, MERS-CoV, seasonal coronaviruses). We conducted an extensive systematic review of experiments identifying potential host factors. Gene lists from diverse sources were integrated using Meta-Analysis by Information Content (MAIC). This previously described algorithm uses data-driven gene list weightings to produce a comprehensive ranked list of implicated host genes. From 32 datasets, the top ranked gene was PPIA, encoding cyclophilin A, a druggable target using cyclosporine. Other highly-ranked genes included proposed prognostic factors (
CXCL10
,
CD4
,
CD3E
) and investigational therapeutic targets (
IL1A
) for COVID-19. Gene rankings also inform the interpretation of COVID-19 GWAS results, implicating
FYCO1
over other nearby genes in a disease-associated locus on chromosome 3. Researchers can search and review the gene rankings and the contribution of different experimental methods to gene rank at
https://baillielab.net/maic/covid19
. As new data are published we will regularly update the list of genes as a resource to inform and prioritise future studies.
Journal Article
Evaluation of pragmatic oxygenation measurement as a proxy for Covid-19 severity
by
Baillie, J. Kenneth
,
Scott-Brown, James
,
Semple, Malcolm G.
in
692/308/174
,
692/308/2779/777
,
692/308/409
2023
Choosing optimal outcome measures maximizes statistical power, accelerates discovery and improves reliability in early-phase trials. We devised and evaluated a modification to a pragmatic measure of oxygenation function, the
S
/
F
ratio. Because of the ceiling effect in oxyhaemoglobin saturation,
S
/
F
ratio ceases to reflect pulmonary oxygenation function at high
S
p
O
2
values. We found that the correlation of
S
/
F
with the reference standard (
P
a
O
2
/
F
I
O
2
ratio) improves substantially when excluding
S
p
O
2
>
0.94
and refer to this measure as
S
/
F
94
. Using observational data from 39,765 hospitalised COVID-19 patients, we demonstrate that
S
/
F
94
is predictive of mortality, and compare the sample sizes required for trials using four different outcome measures. We show that a significant difference in outcome could be detected with the smallest sample size using
S
/
F
94
. We demonstrate that
S
/
F
94
is an effective intermediate outcome measure in COVID-19. It is a non-invasive measurement, representative of disease severity and provides greater statistical power.
There is a need for an accurate measure of pulmonary oxygenation function that can be used as an intermediate endpoint in pragmatic clinical trials, to increase statistical power and efficiency. Here, the authors show that the S/F94, a modification of the S/F ratio, is a simple, meaningful and effective intermediate outcome measure.
Journal Article
Current Understanding of Leukocyte Phenotypic and Functional Modulation During Extracorporeal Membrane Oxygenation: A Narrative Review
by
Ki, Katrina K.
,
Langguth, Daman
,
Passmore, Margaret R.
in
Antigens
,
Cell activation
,
critically ill patients
2021
A plethora of leukocyte modulations have been reported in critically ill patients. Critical illnesses such as acute respiratory distress syndrome and cardiogenic shock, which potentially require extracorporeal membrane oxygenation (ECMO) support, are associated with changes in leukocyte numbers, phenotype, and functions. The changes observed in these illnesses could be compounded by exposure of blood to the non-endothelialized surfaces and non-physiological conditions of ECMO. This can result in further leukocyte activation, increased platelet-leukocyte interplay, pro-inflammatory and pro-coagulant state, alongside features of immunosuppression. However, the effects of ECMO on leukocytes, in particular their phenotypic and functional signatures, remain largely overlooked, including whether these changes have attributable mortality and morbidity. The aim of our narrative review is to highlight the importance of studying leukocyte signatures to better understand the development of complications associated with ECMO. Increased knowledge and appreciation of their probable role in ECMO-related adverse events may assist in guiding the design and establishment of targeted preventative actions.
Journal Article
Systems-level insights into bronchopulmonary dysplasia from meta-analysis of genome-scale studies
Despite marked improvements in survival following preterm birth, the incidence of bronchopulmonary dysplasia (BPD) remains the most prevalent complication of prematurity and carries the risk of long-term morbidity. Characterising the cellular and molecular mechanisms driving disease progression is critical for informing clinical management and improving outcomes. To this end, we conducted a meta-analysis of genome-scale studies to identify molecular pathways implicated in BPD progression in both human cohorts and animal models.
Gene lists associated with BPD in humans, and in rodent models, were extracted from systematically identified genome-scale studies. These gene lists were subsequently analysed using the meta-analysis by information content (MAIC) algorithm, which integrates multiple datasets to generate a single aggregated, ranked gene list based on the cumulative strength of evidence for each gene. Comparative analyses were then performed between the human and rodent BPD datasets, as well as between the human BPD dataset and our previously generated Acute Respiratory Distress Syndrome MAIC dataset.
Across all analyses, a consistent enrichment of genes involved in leukocyte-mediated antigen presentation and lymphocyte development and activation was observed, suggesting a shift from acute innate immune injury toward a more sustained lymphoid-driven inflammatory process during BPD progression. Comparative analyses revealed limited overlap between BPD and ARDS gene sets, suggesting divergent disease mechanisms, while still highlighting shared immune activation pathways. Human-rodent comparisons showed divergence in tissue remodelling signatures, likely reflecting differences in sample sources, yet converged on key conserved signals such as CD3E and IL1R2, implicating common inflammatory regulatory mechanisms.
MAIC effectively identifies conserved molecular signatures in BPD highlighting lymphoid lineage signatures that are not readily apparent in the primary data. These signatures offer insights relevant to immune-modulatory therapeutic strategies, highlighting key processes involved in antigen presentation and modulation of T-cell activation and development during the progression of Bronchopulmonary Dysplasia.
Journal Article
Low flow rate alters haemostatic parameters in an ex-vivo extracorporeal membrane oxygenation circuit
by
Ki, Katrina K.
,
Passmore, Margaret R.
,
Millar, Jonathan E.
in
Blood platelets
,
Coagulation
,
Critical Care Medicine
2019
Background
Extracorporeal membrane oxygenation (ECMO) is a life-saving modality used to manage cardiopulmonary failure refractory to conventional medical and surgical therapies. Despite advances in ECMO equipment, bleeding and thrombosis remain significant complications. While the flow rate for ECMO support is well recognized, less is known about the minimum-rate requirements and haemostasis. We investigated the relationship between different ECMO flow rates, and their effect on haemolysis and coagulation.
Methods
Ten ex-vivo ECMO circuits were tested using donated, < 24-h-old human whole blood, with two flow rates: high-flow at 4 L/min (normal adult cardiac output;
n
= 5) and low-flow at 1.5 L/min (weaning;
n
= 5). Serial blood samples were taken for analysis of haemolysis, von Willebrand factor (vWF) multimers by immunoblotting, rotational thromboelastometry, platelet aggregometry, flow cytometry and routine coagulation laboratory tests.
Results
Low-flow rates increased haemolysis after 2 h (
p
= 0.02), 4 h (
p
= 0.02) and 6 h (
p
= 0.02) and the loss of high-molecular-weight vWF multimers (
p
= 0.01), while reducing ristocetin-induced platelet aggregation (
p
= 0.0002). Additionally, clot formation times were prolonged (
p
= 0.006), with a corresponding decrease in maximum clot firmness (
p
= 0.006).
Conclusions
In an ex-vivo model of ECMO, low-flow rate (1.5 L/min) altered haemostatic parameters compared to high-flow (4 L/min). Observed differences in haemolysis, ristocetin-induced platelet aggregation, high-molecular-weight vWF multimers and clot formation time suggest an increased risk of bleeding complications. Since patients are often on ECMO for protracted periods, extended-duration studies are required to characterise long-term ECMO-induced haemostatic changes.
Journal Article
Need for systematic audit of trauma care in Northern Ireland
by
Millar, Jonathan E
,
McLaughlin, Russell
,
Lutton, Stuart
in
Emergency Medical Services - standards
,
Funding
,
Hospital Units - standards
2016
The 2016 budget gave the NHS in Northern Ireland a small amount of new funding. 1 We like many others were delighted to hear the announcement, by the chancellor and the minister of health at the Northern Ireland Assembly, of funding for a helicopter emergency medical service (HEMS).
Journal Article
Prophylactic Postoperative High Flow Nasal Oxygen Versus Conventional Oxygen Therapy in Obese Patients Undergoing Bariatric Surgery (OXYBAR Study): a Pilot Randomised Controlled Trial
by
Rapchuk, Ivan L.
,
Merza, Megan
,
Fulton, Rachel
in
Gastrointestinal surgery
,
Medicine
,
Medicine & Public Health
2021
Background
Patients with obesity are predisposed to a reduction in end-expiratory lung volume (EELV) and atelectasis after anaesthesia. High flow nasal oxygen (HFNO) may increase EELV, reducing the likelihood of postoperative pulmonary complications (PPC). We conducted a pilot randomised controlled trial (RCT) of conventional oxygen therapy versus HFNO after bariatric surgery. The aim was to investigate the feasibility of using electrical impedance tomography (EIT) as a means of assessing respiratory mechanics and to inform the design of a definitive RCT.
Methods
We performed a single-centre, parallel-group, pilot RCT. Adult patients with obesity undergoing elective bariatric surgery were eligible for inclusion. We excluded patients with a known contraindication to HFNO or with chronic lung disease.
Results
Fifty patients were randomised in equal proportions. One patient crossed over from conventional O
2
to HFNO. Delta EELI was higher at 1 hour in patients receiving HFNO (mean difference = 831 Au (95% CI − 1636–3298),
p
= 0.5). Continuous EIT beyond 1 hour was poorly tolerated. At 6 hours, there were no differences in PaO
2
/FiO
2
ratio or PaCO
2
. Only one patient developed a PPC (in the HFNO group) by 6 weeks.
Conclusions
These data suggest that a large-scale RCT of HFNO after bariatric surgery in an ‘all-comers’ population is likely infeasible. While EIT was an effective means of assessing respiratory mechanics, it was impractical over time. Similarly, the infrequency of PPC precludes its use as a primary outcome. Future studies should focus on identifying patients at the greatest risk of PPC.
Graphical abstract
Journal Article