<b><i>Background:</i></b> The differential diagnosis of pleural effusions can present a considerable challenge, and the etiology of pleural effusions varies depending on the population studied. <b><i>Objective:</i></b> This study aimed to assess the efficacy and safety of medical thoracoscopy in the diagnosis of patients with undiagnosed pleural effusions in a Chinese population. <b><i>Methods:</i></b> Between July 2005 and June 2014, medical thoracoscopy (MT) using the semirigid instrument was performed in 833 patients with pleural effusions of unknown etiology in our Institute, where diagnostic thoracocentesis or/and blind pleural biopsy had failed to yield an answer. Demographic, radiographic, procedural, and histological data were recorded and analyzed. <b><i>Results:</i></b> During this 9-year study, satisfactory pleural biopsy samples were obtained in 833 patients, and MT revealed malignant pleural effusion in 342 (41.1%) patients, benign pleural effusion in 429 (51.5%) patients, and 62 (7.4%) patients could not get definite diagnoses. The overall diagnostic efficiency of MT was 92.6% (771/833). After MT, the only severe complication was empyema, seen in 3 patients (0.4%). The most common minor complication was transient chest pain (44.1%) from the indwelling chest tube. <b><i>Conclusions:</i></b> MT is an effective and safe procedure for diagnosing pleural effusions of undetermined causes. In areas with high tuberculosis prevalence, MT should be particularly helpful in the differential diagnosis of tuberculous pleural effusion.

The role of melatonin in the regulation of fruit ripening and the mechanism involved remain largely unknown. In “Moldova” grape berries, melatonin accumulated rapidly from onset of veraison, reached the maximum at 94 days after bloom (DAB) and then exhibited low levels at late stages of berry ripening. By contrast, abscisic acid (ABA) and hydrogen peroxide (H2O2) exhibited different accumulation patterns, and ethylene was primarily produced immediately before veraison. Further experiments demonstrated that 10 and particularly 100 µM melatonin treatments increased the levels of ABA, H2O2, and ethylene production and promoted berry ripening compared with the control treatment, whereas 0.1 and 1.0 µM melatonin did not lead to clear effects. Additionally, the application of inhibitors indicated that ABA, H2O2, and ethylene participated in the regulation of berry ripening induced by melatonin, and the suppression of ethylene biosynthesis produced the greatest inhibitory effects on melatonin-induced berry ripening compared with those of ABA and H2O2. Melatonin also promoted ethylene production via ABA. In summary, 10 and particularly 100 µM melatonin treatments promoted berry ripening, which was accomplished, at least partially, via the other signaling molecules of ABA, H2O2, and particularly ethylene. This research provides insight into melatonin signaling during berry ripening and may advance the application of melatonin to accelerate berry ripening.

This study assessed the primary impacts of exogenous melatonin (MT) treatment on grape berry metabolism. Exogenous MT treatment increased the endogenous MT content and modified berry ripening. Transcriptomic analysis revealed that the processes of polyphenol metabolism, carbohydrate metabolism and ethylene biosynthesis and signaling were the three most significantly altered biological processes upon MT treatment. Further experiments verified that MT treatment increased the contents of total anthocyanins, phenols, flavonoids and proanthocyanidins in berries. Additionally, the contents of 18 of the 22 detected individual phenolic compounds were enhanced by MT treatment; particularly, the resveratrol content was largely increased concomitantly with the up-regulation of STS gene expression. Meanwhile, MT treatment enhanced the antioxidant capacity of berries. On the other hand, it was indicated that ethylene participated in the regulation of polyphenol metabolism and antioxidant capacity under MT treatment in grape berries. In summary, MT enhances the polyphenol content and antioxidant capacity of grape berries partially via ethylene signaling.

The signal molecules melatonin and ethylene play key roles in abiotic stress tolerance. The interplay between melatonin and ethylene in regulating salt tolerance and the underlying molecular mechanism of this interplay remain unclear. Here, we found that both melatonin and 1-aminocyclopropane-1-carboxylic acid (ACC, a precursor of ethylene) enhanced the tolerance of grapevine to NaCl; additionally, ethylene participated in melatonin-induced salt tolerance. Further experiments indicated that exogenous treatment and endogenous induction of melatonin increased the ACC content and ethylene production in grapevine and tobacco plants, respectively. The expression of MYB108A and ACS1, which function as a transcription factor and a key gene involved in ethylene production, respectively, was strongly induced by melatonin treatment. Additionally, MYB108A directly bound to the promoter of ACS1 and activated its transcription. MYB108A expression promoted ACC synthesis and ethylene production by activating ACS1 expression in response to melatonin treatment. The suppression of MYB108A expression partially limited the effect of melatonin on the induction of ethylene production and reduced melatonin-induced salt tolerance. Collectively, melatonin promotes ethylene biosynthesis and salt tolerance through the regulation of ACS1 by MYB108A.

Our data showed that medical thoracoscopy is a simple procedure with high diagnostic yield and excellent safety for the diagnosis of tuberculous pleural effusion.