ジュニア期スポーツにおけるサプリメント摂取の現状とその影響

近年、多種類のサプリメントが簡単に入手できる時代となり、子どもたちも自由に気軽に購入できる状況におかれている。また、スポーツ界ではアンチ・ドーピング活動が盛んとなっているが、サプリメント摂取はアスリートにとってドーピング的意味合いを持つことを忘れてはならない。そこで、我々は、まず子どものサプリメントの摂取状況を文献的に考察し、次いで全国の日本スポーツ少年団に登録する子どもを対象としたサプリメント等に関するアンケート調査を実施した結果を踏まえて、子どもたちのサプリメント摂取やドーピングに関する今後の課題を検討した。その結果、サプリメント摂取はスポーツに対する効果だけでなく、ドーピング問題も含めた教育をジュニア期から行い、専門家による早急な対応の必要性が明らかとなった

Genetic Diversity and Epidemic Types of Porcine Reproductive and Respiratory Syndrome (PRRS) Virus in Japan from 2018 to 2020

To clarify the genetic diversity of the porcine reproductive and respiratory syndrome virus (PRRSV) in Japan in recent years, we determined the nucleotide sequence of open reading frame 5 of 2482 PRRSV sequences obtained from samples collected from pigs between January 2018 and December 2020. As a result of molecular phylogenetic analysis, Cluster II represented the largest proportion (44.9–50.6%) throughout the study period, followed by Cluster IV (34.0–40.8%), Cluster III (7.8–12.1%), Cluster I (3.1–6.7%), and Cluster V (0.1–0.2%). The relative distributions between Clusters varied between geographic regions and between years: in 2018, Cluster II was the most prevalent in all regions. In 2019, Cluster II was dominant in the Hokkaido and Tohoku regions, while in other regions Cluster IV was dominant. In 2020, Cluster IV was dominant in the Kanto/Tosan and Kyushu/Okinawa regions, whilst in other regions Cluster II was predominant. Compared with a previous study, the proportions of genome sequences classified in Clusters II and IV significantly increased (p = 0.042 and 0.018, respectively) and those classified in Cluster III significantly decreased (p < 0.01). The widespread use of live attenuated vaccines using strains that belong to Cluster II might have accounted for these changes in the relative distribution between Clusters

Analysis of the clinical factors associated with anal function after intersphincteric resection for very low rectal cancer

Abstract Background Intersphincteric resection (ISR) has been used to avoid permanent colostomy in very low rectal cancer patients. This study aimed to assess the surgical safety and oncologic and functional outcomes of ISR. Methods The records of 30 consecutive very low rectal cancer patients who underwent ISR without neoadjuvant therapy were retrospectively analyzed; survival and locoregional recurrence rates were calculated by the Kaplan-Meier method. Incontinence was assessed by a functionality questionnaire and the Wexner score. Results The median distance between the distal margin of the dentate line was 10 mm. A total of 12, 4, and 14 patients underwent partial ISR, subtotal ISR, and total ISR, respectively. The mean distal resection margin was negative in all cases, and circumferential resection margin was positive in two cases. Morbidity was 33.3%: anastomotic stricture in seven patients, colonic J-pouch prolapse in two patients, and an anovaginal fistula in one patient. During the median, 56.2-month follow-up period, local, distant, and combined recurrences occurred in four, three, and two patients, respectively. The 5-year overall and disease-free survival rates were 76.5% and 68.4%, respectively. Local recurrence rates were 5.2% for the patients with Tis-T2 tumors as compared with 45.5% for those with T3 tumors (P = 0.008). The mean Wexner scores and stool frequencies, 12 months after stoma closure in 19 patients, were 11.5 and 6.6 per 24 h, respectively. Significant differences were not seen in the Wexner scores between partial ISR and subtotal/total ISR (11.8 ± 2.6 and 9.1 ± 5.6). Stool frequency (P = 0.02), urgency (P = 0.04), and fragmentation (P = 0.015) were worse in patients with anastomotic stricture than in those without; there was no symptom improvement in patients with anastomotic stricture. Conclusions The anastomotic strictures in patients undergoing ISR may have negatively affected anal function. For total ISR patients, at least, informed consent stating the possibility of a permanent colostomy is necessary.</p

Induction and persistence of cytogenetic damage in cultured peripheral blood lymphocytes following 15 Gy gamma-irradiation

In the conventional dicentric chromosome assay (DCA), the linear-quadratic dose response equation has been established for doses less than 6 Gy. At higher doses, DCA does not provide accurate dose response relationships due to mitotic delay, poor mitotic index and a high proportion of complex chromosomal aberrations. In case of partial body exposure, however, induction and transmission of chromosomal damage at high dose irradiation should be analyzed to assess the biological effects of radiation. The objective of this work is to characterize chromosomal aberrations induced by high-dose irradiation in cultured lymphocytes. Peripheral blood samples were exposed to 15 Gy gamma-ray (60Co source, 0.51 Gy/min). Isolated lymphocytes were cultured in RPMI1640 medium supplemented with 20% fetal bovine serum, 2% phytohaemagglutinin and 30 mM bromodeoxyuridine (BrdU). Cells were harvested at 48 h, 50 h, 52 h, 54 h, 56 h, 72 h and 96 h after culture initiation. For the 72 h sample, multicolor fluorescence in situ hybridization (M-FISH) was conducted to analyze complex chromosome aberrations. The first mitotic peak appeared at 52-54 h. Interestingly, cells containing aberrant chromosomes with as many as 8-10 centromeres were observed. Average dicentric equivalent count per cell ranged from 9.0 to 9.5 in 48 h &#8211; 56 h samples. In the 72 h sample, 20% of the dividing cells were in the 2nd metaphase. It should be noted that 70% of the 2nd metaphase cells were tetraploid cells including endoreduplicated cells. The high degree of polyploidy noted in our material suggests that irradiation may exert an effect on the replication process, in addition to the structural damage. M-FISH analyses revealed that in certain cells, aberrant chromosomes were accurately replicated in the polyploidization process. In the 96 h sample, cells at the third metaphase with octaploid chromosomes were found. In conclusion, a certain population of peripheral blood lymphocytes was found to transit to the second and even third mitoses after high-dose in vitro irradiation, persisting with severe chromosome aberrations. The occurrence of polyploidization and endoreduplication following high-dose irradiation described here validated the reported fact that after high dose radiotherapy, tetrapliod cells were observed in the circulating blood of patients.14th International Comgress of Radiation Researc

Establishment of a dose-response curve of 60Co gamma-ray irradiation by dicentric chromosome analysis

Ionizing radiation exposure causes DNA strand breaks that lead to chromosome aberrations. Among radiation-induced chromosome aberrations, multicentric chromosomes, as represented by dicentric chromosomes, are considered to be sensitive and specific biomarkers for assessing the radiation dose. For more than three decades, dicentric chromosome analysis (DCA) has been the Gold Standard of biodosimetry. In DCA, a dicentric yield per cell of a radiation-exposed patient is applied to a calibration curve (dose-response curve). Many dose-response curves have been proposed thus far, but most of them have been generated respectively from one healthy donor by one in vitro experiment. According to the result of international collaborative works on inter-laboratory comparisons, it has been reported that in DCA, the significant variation of dose estimation is partly attributed to different experimental protocols including the scoring criteria of chromosome aberrations among institutions / investigators. Thus, it is necessary for a biodosimetry laboratory to have and use its own dose-response curve under its own experimental conditions.In the present study, in order to evaluate the dose estimation of patients for better medical preparedness, a dose-response curve was established by analyzing 13 occupationally non-exposed healthy volunteers by DCA using peripheral blood samples irradiated in vitro with 60Co gamma-rays at seven different doses (0, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 Gy). The result of the first-division metaphase scoring followed a linear-quadratic equation, Y=A+aD+bD2 (Y: the yield of dicentrics, D: the dose, A: the background frequency, a: the linear coefficient, b: the dose squared coefficient; IAEA Technical Reports Series No. 405 Cytogenetic Analysis for Radiation Dose Assessment, Vienna, 2001).Then, we established a practical biodosimetry protocol for radiation emergency medicine, tentatively called the NIRS DCA System (including sample collection, cell culture, chromosome preparation, automated metaphase image-capturing, chromosome aberration scoring in triage- and full estimation-modes, and a diagnostic report format), for conducting dose estimation within several days of receiving blood samples. The NIRS DCA System is now being used for actual radiation exposure accidents in Japan

Induction and Persistence of Multicentric Chromosomes in Cultured Human Peripheral Blood Lymphocytes Following High-Dose Gamma Irradiation

Among radiation-induced chromosome aberrations, multicentric chromosomes, as represented by dicentric chromosomes (dicentrics), are regarded as sensitive and specific biomarkers for assessing radiation dose in the 0 to 5 Gy range. The objective of this study was to characterize chromosome aberrations induced in vitro by a higher dose of radiation. Peripheral blood lymphocytes were exposed to 15 Gy gamma rays at a dose rate of 0.5 Gy/min and harvested at 48, 50, 52, 54, 56 and 72 h. The first mitotic peak appeared at 52-54 h, showing about a 6 h mitotic delay as compared with nonirradiated control cultures. Cell-cycle analysis of parallel and simultaneous cultures by sister-chromatid differentiation staining suggests that metaphase cells examined in 48-56 h cultures were in the first mitosis after culture initiation. The mean dicentric equivalent counts ranged from 9.0 to 9.3 in consecutively harvested cultures with no significant differences among them. At 72 h, about 20 % of dividing cells were tetraploid, persisting with faithfully replicated unstable chromosome aberrations. The nonrandom distribution of replicated chromosome pairs, deduced from multicolor fluorescence in situ hybridization analysis, led us to surmise that the predominant mechanism underlying the induction of tetraploid cells is endoreduplication. These findings suggest that a high-dose in vitro irradiation applied to peripheral blood lymphocytes may affect on the replication process, in addition to structural chromosome damage