| 1. |
- Arlock, Per, et al.
(author)
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Excitation and contraction of cardiac muscle and coronary arteries of brain-dead pigs
- 2023
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In: FASEB BioAdvances. - : Wiley. - 2573-9832. ; 5:2, s. 71-84
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Journal article (peer-reviewed)abstract
- Excitability and contraction of cardiac muscle from brain-dead donors critically influence the success of heart transplantation. Membrane physiology, Ca2+-handling, and force production of cardiac muscle and the contractile properties of coronary arteries were studied in hearts of brain-dead pigs. Cardiac muscle and vascular function after 12 h brain death (decapitation between C2 and C3) were compared with properties of fresh tissue. In both isolated cardiomyocytes (whole-cell patch clamp) and trabecular muscle (conventional microelectrodes), action potential duration was shorter in brain dead, compared to controls. Cellular shortening and Ca2+ transients were attenuated in the brain dead, and linked to lower mRNA expression of L-type calcium channels and a slightly lower ICa,L, current, as well as to a lower expression of phospholamban. The current–voltage relationship and the current above the equilibrium potential of the inward K+ (IK1) channel were altered in the brain-dead group, associated with lower mRNA expression of the Kir2.2 channel. Delayed K+ currents were detected (IKr, IKs) and were not different between groups. The transient outward K+ current (Ito) was not observed in the pig heart. Coronary arteries exhibited increased contractility and sensitivity to the thromboxane analogue (U46619), and unaltered endothelial relaxation. In conclusion, brain death involves changes in cardiac cellular excitation which might lower contractility after transplantation. Changes in the inward rectifier K+ channel can be associated with an increased risk for arrhythmia. Increased reactivity of coronary arteries may lead to increased risk of vascular spasm, although endothelial relaxant function was well preserved.
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| 2. |
- Dore, Riccardo, et al.
(author)
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Resistance to thyroid hormone induced tachycardia in RTHα syndrome
- 2023
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In: Nature Communications. - 2041-1723. ; 14:1
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Journal article (peer-reviewed)abstract
- Mutations in thyroid hormone receptor α1 (TRα1) cause Resistance to Thyroid Hormone α (RTHα), a disorder characterized by hypothyroidism in TRα1-expressing tissues including the heart. Surprisingly, we report that treatment of RTHα patients with thyroxine to overcome tissue hormone resistance does not elevate their heart rate. Cardiac telemetry in male, TRα1 mutant, mice indicates that such persistent bradycardia is caused by an intrinsic cardiac defect and not due to altered autonomic control. Transcriptomic analyses show preserved, thyroid hormone (T3)-dependent upregulation of pacemaker channels (Hcn2, Hcn4), but irreversibly reduced expression of several ion channel genes controlling heart rate. Exposure of TRα1 mutant male mice to higher maternal T3 concentrations in utero, restores altered expression and DNA methylation of ion channels, including Ryr2. Our findings indicate that target genes other than Hcn2 and Hcn4 mediate T3-induced tachycardia and suggest that treatment of RTHα patients with thyroxine in high dosage without concomitant tachycardia, is possible.
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| 3. |
- Li, Mei, et al.
(author)
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Development and prevention of ischemic contracture (“stone heart”) in the pig heart
- 2023
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In: Frontiers in Cardiovascular Medicine. - : Frontiers Media SA. - 2297-055X. ; 10
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Journal article (peer-reviewed)abstract
- Stone heart (ischemic contracture) is a rare and serious condition observed in the heart after periods of warm ischemia. The underlying mechanisms are largely unknown and treatment options are lacking. In view of the possibilities for cardiac donation after circulatory death (DCD), introducing risks for ischemic damage, we have investigated stone heart in pigs. Following cessation of ventilation, circulatory death (systolic pressure <8 mmHg) occurred within 13.1 ± 1.2 min; and a stone heart, manifested with asystole, increased left ventricular wall thickness and stiffness, established after a further 17 ± 6 min. Adenosine triphosphate and phosphocreatine levels decreased by about 50% in the stone heart. Electron microscopy showed deteriorated structure with contraction bands, Z-line streaming and swollen mitochondria. Synchrotron based small angle X-ray scattering of trabecular samples from stone hearts revealed attachment of myosin to actin, without volume changes in the sarcomeres. Ca2+ sensitivity, determined in permeabilized muscle, was increased in stone heart samples. An in vitro model for stone heart, using isolated trabecular muscle exposed to hypoxia/zero glucose, exhibited the main characteristics of stone heart in whole animals, with a fall in high-energy phosphates and development of muscle contracture. The stone heart condition in vitro was significantly attenuated by the myosin inhibitor MYK-461 (Mavacamten). In conclusion, the stone heart is a hypercontracted state associated with myosin binding to actin and increased Ca2+ sensitivity. The hypercontractile state, once developed, is poorly reversible. The myosin inhibitor MYK-461, which is clinically approved for other indications, could be a promising venue for prevention.
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| 4. |
- Rydberg, Mattias, et al.
(author)
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Patient Experiences after Open Trigger Finger Release in Patients with Type 1 and Type 2 Diabetes-A Retrospective Study Using Patient-reported Outcome Measures
- 2023
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In: Plastic and reconstructive surgery. Global open. - 2169-7574. ; 11:6
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Journal article (peer-reviewed)abstract
- UNLABELLED: Trigger finger is overrepresented among patients with diabetes mellitus (DM). Whether DM affects the outcome after open trigger finger release (OTFR) in patients with DM is not known. Our aim was thus to explore outcomes after OTFR in patients with type 1 (T1D) and type 2 DM (T2D).METHODS: Data included patient-reported outcome measures (PROMs) from all OTFRs performed between 2010 and 2020 registered in the Swedish national registry for hand surgery in individuals over 18 years cross-linked with the Swedish National Diabetes Register (NDR). PROMs included QuickDASH and HQ8, a questionnaire designed for national registry for hand surgery, preoperative and at 3 and 12 months postoperative. HQ8 included pain on load, pain on motion without load, and stiffness. Outcome was calculated using linear-mixed models and presented as means adjusted for age and stratified by sex.RESULTS: In total, 6242 OTFRs were included, whereof 496 had T1D (332, 67% women) and 869 had T2D (451, 52% women). Women with T1D reported more symptoms of stiffness (P < 0.001), and women with T2D reported more pain on load (P < 0.05), motion without load (P < 0.01), and worse overall result at 3 months. At 12 months, however, no differences were found in any of the HQ-8 PROMs among men or women. Women with T2D had slightly higher QuickDASH scores at 3 and 12 months.CONCLUSION: Patients with T1D and T2D can expect the same results after OTFR as individuals without DM, although the improvement might take longer especially among women with T2D.
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| 5. |
- Wang, Bowen, et al.
(author)
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Pharmacological and mechanical properties of isolated pig coronary veins
- 2023
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In: Frontiers in Physiology. - 1664-042X. ; 14
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Journal article (peer-reviewed)abstract
- Recent successful cardiac transplantation from pig to non-human primates and the first pig-to-human transplantation has put the focus on the properties of the pig heart. In contrast to the coronary arteries, the coronary veins are less well characterized and the aim was to examine the mechanical and pharmacological properties of coronary veins in comparison to the arteries. Vessel segments from the left anterior descending coronary artery (LAD) and the concomitant vein were isolated from pig hearts in cardioplegia and examined in vitro. The wall thickness, active tension and active stress at optimal circumference were lower in coronary veins, reflecting the lower intravascular pressure in vivo. Reverse transcription polymerase chain reaction (RT-PCR) analysis of myosin isoforms showed that the vein could be characterized as having a slower smooth muscle phenotype compared to the artery. Both vessel types contracted in response to the thromboxane agonist U46619 with EC50 values of about 20 nM. The artery contracted in response to acetylcholine. Precontracted arteries relaxed in noradrenaline and substance P. In contrast, the veins relaxed in acetylcholine, contracted in noradrenaline and were unresponsive to substance P. In conclusion, these results demonstrate significant differences between the coronary artery and vein in the smooth muscle properties and in the responses to sympathetic and parasympathetic stimuli.
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