No abstract

No abstract

Background Methylphenidate, a stimulant used to treat attention deficit hyperactivity disorder, has the potential to be used nonmedically, such as for studying and recreation. In an era when many people actively use social networking services, experience with the nonmedical use or side effects of methylphenidate might be shared on Twitter. Objective The purpose of this study was to analyze tweets about the nonmedical use and side effects of methylphenidate using a machine learning approach. Methods A total of 34,293 tweets mentioning methylphenidate from August 2018 to July 2019 were collected using searches for “methylphenidate” and its brand names. Tweets in a randomly selected training dataset (6860/34,293, 20.00%) were annotated as positive or negative for two dependent variables: nonmedical use and side effects. Features such as personal noun, nonmedical use terms, medical use terms, side effect terms, sentiment scores, and the presence of a URL were generated for supervised learning. Using the labeled training dataset and features, support vector machine (SVM) classifiers were built and the performance was evaluated using F1 scores. The classifiers were applied to the test dataset to determine the number of tweets about nonmedical use and side effects. Results Of the 6860 tweets in the training dataset, 5.19% (356/6860) and 5.52% (379/6860) were about nonmedical use and side effects, respectively. Performance of SVM classifiers for nonmedical use and side effects, expressed as F1 scores, were 0.547 (precision: 0.926, recall: 0.388, and accuracy: 0.967) and 0.733 (precision: 0.920, recall: 0.609, and accuracy: 0.976), respectively. In the test dataset, the SVM classifiers identified 361 tweets (1.32%) about nonmedical use and 519 tweets (1.89%) about side effects. The proportion of tweets about nonmedical use was highest in May 2019 (46/2624, 1.75%) and December 2018 (36/2041, 1.76%). Conclusions The SVM classifiers that were built in this study were highly precise and accurate and will help to automatically identify the nonmedical use and side effects of methylphenidate using Twitter.

Chlorpyrifos (CP) residues are absorbed from soil and often found in Korean cabbages that are being used to make kimchi. Lactobacillus sakei WCP904, harboring the organophosphorus (OP) hydrolase gene opdD, was isolated from CP-impregnated mulkimchi. The cloned gene opdD from strain CP904 comprises 825 base-pair nucleotides that encode 274 amino acids. The recombinant Escherichia coli harboring the opdD gene depleted 73% of CP after 6 days in M9 medium. In fact, the OpdD protein is a novel member of the GHSQG family of esterolytic enzymes or lactic acid bacterial Opd groups. The molecular weight of the OpdD protein was estimated to be 31 kDa using SDS-PAGE. Broad-spectrum activities of the OpdD protein were obtained against OP insecticides containing both P-O and P-S bonds. The OpdD protein exhibits maximum activity at 30°C with pH 6. No enzyme activities of the mutated OpdD (Ser116 ? Ala116) protein toward q-nitrophenyl butyrate and CP substrates were observed. These results suggested that the strain WCP904 scavenges insecticide residues from mulkimchi vegetables, thus abolishing health hazards by secreting OP hydrolase during fermentation.

PurposeA few studies have focused on factors predisposing to retear after arthroscopic revision rotator cuff repair (ARRCR). This study aimed to retrospectively evaluate (1) the structural and clinical outcomes of ARRCR and (2) pre‐ and intraoperative factors affecting the integrity of the rotator cuff (RC) tendon by focusing on preoperative RC tendon integrity, tear size, muscle hypotrophy and fatty infiltration. MethodsPatients who underwent ARRCR between 2006 and 2016 were reviewed. Preoperative variables included demographic data, RC tendon integrity, tear size, and muscle hypotrophy and fatty infiltration on preoperative magnetic resonance imaging (MRI). Intraoperative variables included repair technique and completeness of repair. The visual analog scale for pain (PVAS), functional VAS (FVAS), American Shoulder and Elbow Surgeons scores, and shoulder range of motion (ROM) were assessed. Postoperative tendon integrity was evaluated using over 6‐month follow‐up MRI. Patients were classified into groups A (healed) and B (retear), and their variables were compared. ResultsOverall 65 patients with a mean follow‐up of 49.5 ± 30.2 (range, 24.0–148.9) months were analyzed. Fifty‐six of 65 (86.2%) patients underwent MRI at 9.1 ± 9.7 (range, 4.4–40.2) months after ARRCR, and 20 of 56 (35.7%) patients (group B) exhibited retear. Group A (36/56, 64.3%) showed higher functional scores and ROMs than group B at the final follow‐up, with significant differences in the FVAS scores (Group A versus B: FVAS, 7.6 ± 1.8 versus 6.4 ± 1.9, p = 0.036). Intraoperative variables, including preoperative tendon integrity (p = 0.021), tear size (p = 0.007), supraspinatus and infraspinatus muscle hypotrophy and fatty infiltration (p < 0.001 and p = 0.046), and completeness of repair (p = 0.030), differed significantly between the groups. Multivariate analysis revealed that preoperative supraspinatus muscle hypotrophy and fatty infiltration were independent predisposing factors for retear after ARRCR [odds ratio = 7.5, 95% confidence interval (CI) 1.1–55.8, p = 0.048]. ConclusionThe retear was found in 20/56 patients (35.7%) after ARRCR for less than massive rotator cuff tears in this limited study population. Preoperative tendon integrity, tear size, supraspinatus and infraspinatus muscle hypotrophy and fatty infiltration, and completeness of repair was revealed to be associated with tendon integrity following ARRCR. Among them, preoperative supraspinatus muscle atrophy and fatty infiltration were the independent factors for retear after ARRCR, although generalization is limited. Level of evidenceIV.