Publications by authors named "Marcus Hock"

4 Publications

  • Page 1 of 1

Quantitative analysis of mitochondrial ATP synthesis.

Math Biosci 2021 Jun 17:108646. Epub 2021 Jun 17.

Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, 48109, MI, USA. Electronic address:

We present a computational framework for analyzing and simulating mitochondrial ATP synthesis using basic thermodynamic and kinetic principles. The framework invokes detailed descriptions of the thermodynamic driving forces associated with the processes of the electron transport chain, mitochondrial ATP synthetase, and phosphate and adenine nucleotide transporters. Assembling models of these discrete processes into an integrated model of mitochondrial ATP synthesis, we illustrate how to analyze and simulate in vitro respirometry experiments and how models identified from in vitro experimental data effectively explain cardiac respiratory control in vivo. Computer codes for these analyses are embedded as Python scripts in a Jupyter Book to facilitate easy adoption and modification of the concepts developed here. This accessible framework may also prove useful in supporting educational applications. All source codes are available on at https://beards-lab.github.io/QAMAS_book/.
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http://dx.doi.org/10.1016/j.mbs.2021.108646DOI Listing
June 2021

Platelet inhibition to target reperfusion injury trial: Rationale and study design.

Clin Cardiol 2019 Jan 17;42(1):5-12. Epub 2018 Dec 17.

The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, London, UK.

Background: In ST-segment elevation myocardial infarction (STEMI) patients treated with primary percutaneous coronary intervention (PPCI), current oral P2Y12 platelet inhibitors do not provide maximal platelet inhibition at the time of reperfusion. Furthermore, administration of cangrelor prior to reperfusion has been shown in pre-clinical studies to reduce myocardial infarct (MI) size. Therefore, we hypothesize that cangrelor administered prior to reperfusion in STEMI patients will reduce the incidence of microvascular obstruction (MVO) and limit MI size in STEMI patients treated with PPCI.

Methods: The platelet inhibition to target reperfusion injury (PITRI) trial, is a phase 2A, multi-center, double-blinded, randomized controlled trial, in which 210 STEMI patients will be randomized to receive either an intravenous (IV) bolus of cangrelor (30 μg/kg) followed by a 120-minute infusion (4 μg/kg/min) or matching saline placebo, initiated prior to reperfusion (NCT03102723).

Results: The study started in October 2017 and the anticipated end date would be July 2020. The primary end-point will be MI size quantified by cardiovascular magnetic resonance (CMR) on day 3 post-PPCI. Secondary endpoints will include markers of reperfusion, incidence of MVO, MI size, and adverse left ventricular remodeling at 6 months, and major adverse cardiac and cerebrovascular events.

Summary: The aim of the PITRI trial is to assess whether cangrelor administered prior to reperfusion would reduce acute MI size and MVO, as assessed by CMR.
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http://dx.doi.org/10.1002/clc.23110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6436500PMC
January 2019

Data-Driven Approach to Defining the Emergency Department Frequent Attender Using a Cohort of 10 Years.

J Acute Med 2018 Mar;8(1):6-16

Singapore General Hospital Department of Emergency Medicine Singapore.

Aims: To identify, based on the measure of resource utilization, the number of visits per calendar year that defines the emergency department (ED) frequent attender; and examine for significant trends in patient characteristics and outcomes which may support the use of our definition.

Materials And Methods: We conducted a retrospective observational study of electronic clinical records of all ED visits over a 10-year period from January 2005 to December 2014 to an urban tertiary general hospital. We defined the ED frequent attender based on the number of ED attendances per calendar year which would yield a patient group representing more than 20% of all patient visits. Chi-square tests were conducted on each categorical factor individually to assess if they were independent of time, and the Student's t-test was used to assess continuous variables on their association with being a frequent attender.

Results: 1.381 million attendance records were analyzed. Patients who attended three or more times per year accounted for about 22.1% of all attendances and were defined as frequent attenders. They were associated with higher triage acuity, complex chronic illnesses, greater 30-day mortality for patients with three to six visits, and increased markers of resource utilization, such as ambulance use (15.5% vs. 11.6%), time to disposition (180 vs. 155 minutes), admissions rate (47.4% vs. 30.7%) and inpatient length of stay (6 days vs. 4 days). All values were statistically significant ( < 0.001).

Conclusion: We have demonstrated a data-driven approach to defining an ED frequent attender. Frequent attenders are associated with increased resource utilization, more complex illness and may be associated with greater 30-day mortality rates.
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http://dx.doi.org/10.6705/j.jacme.201803_8(1).0002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7517909PMC
March 2018

A randomized controlled trial comparing the hair apposition technique with tissue glue to standard suturing in scalp lacerations (HAT study).

Ann Emerg Med 2002 Jul;40(1):19-26

Department of Emergency Medicine, Singapore General Hospital, Singapore.

Study Objective: We evaluate a new technique of treating scalp lacerations, the hair apposition technique (HAT). After standard cleaning procedures, hair on both sides of a laceration is apposed with a single twist. This is then held with tissue adhesives. HAT was compared with standard suturing in a multicenter, randomized, prospective trial.

Methods: All linear lacerations of the scalp less than 10 cm long were included. Severely contaminated wounds, actively bleeding wounds, patients with hair strand length less than 3 cm, and hemodynamically unstable patients were excluded. Patients were randomized to receive either HAT or standard suturing, and the time to complete the wound repair was measured. All wounds were evaluated 7 days later in a nonblinded manner for satisfactory wound healing, scarring, and complications.

Results: There were 96 and 93 patients in the study and control groups, respectively. Wound healing trended toward being judged more satisfactory in the HAT group than standard suturing (100% versus 95.7%; P =.057; effect size 4.3%; 95% confidence interval 0.1% to 8.5%). Patients who underwent HAT had less scarring (6.3% versus 20.4%; P =.005), fewer overall complications (7.3% versus 21.5%; P =.005), significantly lower pain scores (median 2 versus 4; P <.001), and shorter procedure times (median 5 versus 15 minutes; P <.001). There was a trend toward less wound breakdown in the HAT group (0% versus 4.3%; P =.057). When patients were asked whether they were willing to have HAT performed in the future, 84% responded yes, 1% responded no, and 15% were unsure.

Conclusion: HAT is equally acceptable and perhaps superior to standard suturing for closing suitable scalp lacerations. Advantages include fewer complications, a shorter procedure time, less pain, no need for shaving or removal of stitches, similar or superior wound healing, and high patient acceptance. HAT has become our technique of choice for suitable scalp lacerations.[Ong Eng Hock M, Ooi SBS, Saw SM, Lim SH. A randomized controlled trial comparing the hair apposition technique with tissue glue to standard suturing in scalp lacerations (HAT study).
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http://dx.doi.org/10.1067/mem.2002.125928DOI Listing
July 2002
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