Purpose: Cell-free DNA (cfDNA) has been investigated as a minimally invasive biomarker for many diseases, particularly cancer. An increase in cfDNA has been observed during exercise. Neutrophil extracellular traps (NETs) may be the origin of cfDNA in response to acute exercise, but the mechanisms of generation of cfDNA during exercise remain unclear. In this study we investigated the dynamics of serum and urinary cfDNA levels and determined the relevance of other biomarkers to serum and urinary cfDNA levels and fragment size after a full marathon. Methods: Samples were collected from 23 healthy male subjects. Blood and urine samples were collected before and immediately, two hours, and one day after the full marathon. The measurements included serum and urinary cfDNA, creatine kinase, myoglobin, creatinine, white blood cells, platelets, and lactoferrin from blood, and amylase, albumin, and creatinine from urine. Results: Serum and urinary cfDNA levels increased after a full marathon. Creatine kinase, myoglobin, and creatinine in blood, and albumin and creatinine in urine also increased significantly after a full marathon. Serum cfDNA showed peak values about 180 bp after the full marathon. Values over 1000 bp were present at two hours post-marathon. Urinary cfDNA showed peak values from 35 bp to 50 bp after the full marathon. Values over 1000 bp appeared at Immediately and two hours post marathon. Conclusion: This study revealed that both serum and urinary cfDNA levels transiently increased after a full marathon. In addition, these cfDNA fragment varied in size.

Background Catecholamine is a typical index of exercise intensity, but it is difficult to detect. Plasma metanephrine (MN) and normethanephrine (NMN) levels are more stable than those of catecholamines. This study aimed to investigate plasma MN and NMN levels during acute exercise running in amateur runners. Methods Samples were collected from eight healthy male participants. They were either sedentary or running at low or high intensity for 30 min. Blood samples were collected under these conditions. Measurements taken included plasma adrenaline, noradrenaline, MN, and NMN. Results Plasma adrenaline levels increased after high-intensity exercise compared with sedentary subjects. Plasma noradrenaline, MN, and NMN levels increased after both low- and high-intensity exercise compared with sedentary subjects. In addition, these levels were also significantly higher at high intensity than at low intensity. Plasma adrenaline and noradrenaline levels were positively correlated with plasma free MN and NMN levels after acute running, respectively. Conclusion This study revealed that plasma MN and NMN levels transiently increased depending on exercise intensity in amateur runners. In addition, plasma NMN levels are better markers than plasma MN levels because of their stronger correlation with plasma catecholamine levels.

IntroductionExercise training is beneficial for reducing obesity. In particular, exercise training can lower the catecholamine concentration in circulation. Renalase, whose expression was first confirmed in the kidneys, is a physiologically active substance that decomposes circulating catecholamines; additionally, it has been reported to be present in the skeletal muscles. The aim of this study was to clarify the expression of renalase in the skeletal muscles and kidneys after high-intensity exercise training in obese mice.Material and methodsThe mice were divided into four groups: normal diet and sedentary, normal diet and exercise training, high-fat diet and sedentary, and high-fat diet and exercise training, and the test was performed for 8 weeks.ResultsBody weight and skeletal muscle wet weight were reduced by high-fat diet intake but were rescued by training. Skeletal muscle renalase gene expression was significantly increased by exercise training. However, in the kidneys the gene expression of renalase was significantly increased by high-fat diet intake and exercise training. No significant changes were observed in the gene expression of catecholamine-degrading enzymes, catechol-O-methyltransferase and monoamine oxidase A and B.ConclusionWe demonstrated that exercise training increased the gene expression of renalase in the skeletal muscles and kidneys, thus lowering circulating catecholamine levels. This may lead to amelioration of obesity as catecholamines are lipolytic.

The aim of this study was to clarify degradation characteristics in each tissue of the knee complex of a medial meniscectomy (MMx)-induced knee osteoarthritis (KOA) animal model using classical methods and an alternative comprehensive evaluation method called contrast-enhanced X-ray micro-computed tomography (CEX-μCT), which was developed in the study. Surgical MMx was performed in the right knee joints of five male Wistar rats to induce KOA. At four weeks post-surgery, the synovitis was evaluated using quantitative polymerase chain reaction (qPCR). Degradations of the articular cartilage of the tibial plateau were evaluated using classical methods and CEX-μCT. Evaluation of the synovitis demonstrated significantly increased expression levels of inflammation-associated marker genes in MMx-treated knees compared with those in sham-treated knees. Evaluation of the articular cartilage using classical methods showed that MMx fully induced degradation of the cartilage. Evaluation using CEX-μCT showed that local areas of the medial cartilage of the tibial plateau were significantly reduced in MMx-treated knees compared with those in sham-treated knees. On the other hand, total cartilage volumes were significantly increased in MMx-treated knees. On the basis of the findings of this study, the method could be relevant to study new treatments in KOA research.

The aim of this study was to clarify degradation characteristics in each tissue of the knee complex of a medial meniscectomy (MMx)-induced knee osteoarthritis (KOA) animal model using classical methods and a new comprehensive evaluation method called contrast-enhanced X-ray micro-computed tomography (CEX-μCT), which was developed in the study. Surgical MMx was performed in the right knee joints of five male Wistar rats to induce KOA. At 4 wk post-surgery, the synovitis was evaluated using qPCR. Degradations of the articular cartilage of the tibial plateau were evaluated using classical methods and CEX-μCT. Evaluation of the synovitis demonstrated significantly increased expression levels of inflammation-associated marker genes in MMx-treated knees compared to that in sham-treated knees. Evaluation of the articular cartilage using classical methods showed that MMx fully induced degradation of the cartilage. Evaluation using CEX-μCT showed that local areas of the medial cartilage of the tibial plateau were significantly reduced in MMx-treated knees compared to that in sham-treated knees. On the other hand, total cartilage volumes were significantly increased in MMx-treated knees. Based on the findings of this study, the researchers in KOA research could be helped to select an optimal KOA model to discover new drugs.