Changes in two of the elements of myocardial subcellular organelles relating to cardiac energetics, ventricular myosin isozymes and mitochondrial DNA mutations, were examined using left ventricular tissue samples obtained at autopsy from patients with ischemic heart disease. Myosin isozymes were examined in tissues from nine patients with ischemic heart disease and 12 control patients with cancer but no heart disease. Extracted myosin was separated by pyrophosphate gel electrophoresis. The relative concentration of each component was determined by densitometry. Mitochondrial DNA mutations were evaluated in tissues from ten patients with myocardial infarction and 11 control patients with cancer but no heart disease. DNA was extracted and mitochondrial DNA mutations were detected by the polymerase chain reaction. Two bands were revealed by pyrophosphate gel electrophoresis. These contained VM-A, which exhibited faster electrophoretic mobility and was present in lower concentrations, and VM-B, which had a lower mobility and a higher concentration, respectively. SDS polyacrylamide gel electrophoresis showed that these two components contained the heavy chain and light chains 1 and 2 of myosin. VM-A concentrations tended to be higher in patients with ischemic heart disease than in controls. A 7.4-kb deletion was detected between the D-loop and the ATPase 6 genes of mitochondrial DNA from the myocardium of 6 out of 10 patients with myocardial infarction. The relative amounts of the two myosin isozymes could be altered by ischemic heart disease, although the functional significance of these components is unclear. The changes in the two myosin isozymes might be an adaptive change to disordered energy metabolism, but this change was small. The myocardial mitochondrial DNA deletions in patients with myocardial infarction were thought to result from ischemic damage.

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SummaryThis study aimed to investigate how the COVID‐19 pandemic since 2020 has affected the homeostasis model assessment of insulin resistance (HOMA‐IR), body mass index (BMI) and degree of obesity among Japanese children. HOMA‐IR, BMI and degree of obesity were calculated for 378 children 14–15 years old (boys/girls, 208/170) who underwent checkups during 2015–2021. Changes in these parameters over time and correlations between parameters were assessed, and the proportions of participants with IR (HOMA‐IR ≥2.5) were compared. HOMA‐IR values increased significantly over the study period (p < 0.001), with a significantly large proportion of participants with IR in 2020–2021 (p < 0.001). Conversely, BMI and degree of obesity did not change significantly. HOMA‐IR did not correlate with BMI or degree of obesity during 2020–2021. In conclusion, the COVID‐19 pandemic may have had an impact on the increase in the proportion of children with IR, regardless of BMI or degree of obesity.

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