ARTICLE | doi:10.20944/preprints202305.2217.v1
Subject: Medicine And Pharmacology, Orthopedics And Sports Medicine Keywords: epidemiology; baseball injury; young baseball players; injury prevalence; early single sport specialization
Online: 31 May 2023 (10:06:25 CEST)
This study aimed to describe the injury profiles of young Korean baseball players according to position and age as the proportion and distribution of injuries based on playing position and age remains unclear. A total of 271 elite youth baseball players aged 8 to 16 years were divided into two groups: elementary school (ES) (n=135) and middle school (MS) (n=136). The participants' basic, baseball practice, and injury information were collected. Injuries in the MS group were not limited to the elbow and shoulder, and the injury prevalence varied by age group and baseball position. The most injured body region in the ES group was the elbow joint, regardless of the position. In contrast, the most injured body region in the MS group was the lower back, except for infielders whose elbows were the most injured. Additionally, the MS group was more likely to experience injuries of the lower back (OR=4.27, 95% CI=2.47–7.40), shoulder (OR=1.93, 95% CI=1.08–3.43; P=0.024), and knee (OR=2.15, 95% CI=1.17–3.94; P=0.012). Our findings indicate that excessive practice and lack of rest during MS (growth spurt period) can significantly increase the risk of lower back problems in young baseball players.
ARTICLE | doi:10.20944/preprints202303.0067.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Diarrhetic shellfish poisoning (DSP); Dinophysis norvegica; Mesodinium rubrum; Teleaulax amphioxeia; Pectenotoxin-2 (PTX2); Dinophysistoxin-1 (DTX1); Okadaic acid (OA)
Online: 3 March 2023 (09:33:50 CET)
This study is the first report of the successful cultivation of Dinophysis norvegica isolated from Japanese coastal waters (7 of 48 isolated cells were established as the clonal cultures, 14.5%) and their toxin content and production. The strains were maintained at relatively high abundance (>2,000 cells mL-1) for more than one year when fed on Mesodinium rubrum with the addition of Teleaulax amphioxeia. At the end of the one-month incubation, the total amounts of pectenotoxin-2 (PTX2), dinophysistoxin-1 (DTX1) and okadaic acid (OA) were 132.0-375.0 ng mL-1 (n = 7), 0.7-3.6 ng mL-1 (n = 3) and trace level OA (n = 1), respectively. Similarly, the cell quota of PTX2 and DTX1 were 60.6-152.4 pg cell-1 (n = 7) and 0.5-1.2 pg cell-1 (n = 3), respectively. These data indicated that toxin production varies depending on the strains in this species. In the growth experiment, D. norvegica grew, but it was very slow first 12 days. However, after that they grew exponentially with the maximum growth rate of 0.56 divisions day-1 (during Day 24-27), reaching a maximum concentration of 3,000 cells mL-1 at the end of incubation (Day 36), suggesting that they have a long lag phase. In the toxin production, OA was not at a detectable level (≤ 0.010 ng mL-1) during the 36 days of incubation except for Day 6. The concentration of DTX1 and PTX2 showed similar patterns as described for vegetative growth, but the toxin production still increased on Day 36 (1.3 ng mL-1 and 154.7 ng mL-1 in DTX1 and PTX2, respectively). The findings of this study provide novel information on the toxin content and production in D. norvegica as well as details on the culturing and maintenance of the species.