Objective Accumulating evidence has demonstrated that the sub-anesthetic dose of ketamine exerts rapid and ro-bust antidepressant-like effects though its action mechanisms are not yet fully understood .The aim of this study was to investigate the role of gamma-aminobutyric acid ( GABA) in the antidepressant effects of ketamine . Methods Thirty-two male Wistar rats were e-qually randomized into four groups: saline, ketamine, GABA, and GABA+ketamine.All the animals were implanted with a guide cannula into the lateral ventricle and on the eighth day after operation subjected to a 15 min forced swimming test (FST) for the estab-lishment of a depression model .At 24 h after modeling , the rats of the saline and ketamine groups were treated intracerebroventricularly with 2μL isotonic saline solution, and those of the GABA and GABA +ketamine groups with 50μg (2μL) GABA, followed by intrap-eritoneal administration of 1 mL saline in the former two groups and 10 mg/kg (1 mL) ketamine in the latter two groups 10 min later.At 30 min after treatment , the open field test ( OFT) was carried out for crossing and rearing scores and a 6-min FST was performed to re-cord the immobility time in the last 5 minutes.The content of GABA in the prefrontal cortex of the rats was measured following behav -ioral tests. Results The immobility time was significantly decreased in the ketamine group ([107.5 ±21.2]sec) as compared with the saline, GABA, and GABA+ketamine groups ([167.2 ±22.1], [159.8 ±17.5], and [143.8 ±22.1]sec) (P<0.05), with no significant difference between the GABA and GABA +ketamine groups (P>0.05).The level of GABA in the prefrontal cortex was remarkably lower in the ketamine group ([12.4 ±3.4]ng/mg prot) than in the saline, GABA, and GABA+ketamine groups ([23.3 ± 6.3], [27.3 ±5.7], and [18.0 ±5.4]ng/mg prot) (P<0.05), but markedly higher in the GABA than in the GABA +ketamine group (P<0.05).OFT scores exhibited no significant difference in the lo-comotor activity among the four groups of rats ( P >0.05 ). Conclusion The antidepressant effects of ketamine are related to the decreased GABA level in the prefrontal cortex in rats receiving FST .

Objective To compare the diagnostic value of shear wave elastography and 18F-FDG PET/CT imaging in diagnosis of thyroid microcarcinoma.Methods Shear wave elastography and 18F-FDG PET/CT data of patients with thyroid nodules confirmed by pathology were analyzed retrospectively.The sensitivity,specificity,accuracy,positive and negative predictive value of the two methods in diagnosis of malignant thyroid micronodules were compared.Results In all of the 48 micronodules,37 were malignant,11 were benign.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of shear wave elastography and 18F-FDG PET/CT were 91.89％ (34/37),81.82％ (9/11),89.58％ (43/48),94.44％ (34/36),75.00％ (9/12) and 29.73％ (11/37),72.73％ (8/11),39.58％ (19/48),78.57％ (11/ 14),23.53％ (8/34),respectively.The sensitivity,accuracy and negative predictive value between the two methods had statistical difference (all P＜0.05),and the specificity and positive predictive value between the two methods had no statistical difference (both P＞0.05).Conclusion Compared to 18F FDG PET/CT imaging,the diagnositic value of shear wave elastography in diagnosis of thyroid microcarcinoma has obvious advantages.