Self-supervised pre-training for joint optic disc and cup segmentation via attention-aware network.

Image segmentation is a fundamental task in deep learning, which is able to analyse the essence of the images for further development. However, for the supervised learning segmentation method, collecting pixel-level labels is very time-consuming and labour-intensive. In the medical image processing area for optic disc and cup segmentation, we consider there are two challenging problems that remain unsolved. One is how to design an efficient network to capture the global field of the medical image and execute fast in real applications. The other is how to train the deep segmentation network using a few training data due to some medical privacy issues. In this paper, to conquer such issues, we first design a novel attention-aware segmentation model equipped with the multi-scale attention module in the pyramid structure-like encoder-decoder network, which can efficiently learn the global semantics and the long-range dependencies of the input images. Furthermore, we also inject the prior knowledge that the optic cup lies inside the optic disc by a novel loss function. Then, we propose a self-supervised contrastive learning method for optic disc and cup segmentation. The unsupervised feature representation is learned by matching an encoded query to a dictionary of encoded keys using a contrastive technique. Finetuning the pre-trained model using the proposed loss function can help achieve good performance for the task. To validate the effectiveness of the proposed method, extensive systemic evaluations on different public challenging optic disc and cup benchmarks, including DRISHTI-GS and REFUGE datasets demonstrate the superiority of the proposed method, which can achieve new state-of-the-art performance approaching 0.9801 and 0.9087 F1 score respectively while gaining 0.9657 D C disc and 0.8976 D C cup . The code will be made publicly available.

α-Pyrones with glucose uptake-stimulatory activity from the twigs of Cryptocarya wrayi.

Five new α-pyrones, cryptowratones A-E (1-5), and five known congeners (6-10), together with four other known compounds 11-14 were isolated from the twigs of Cryptocarya wrayi. The structures of the new compounds were elucidated on the basis of extensive spectroscopic data analysis and ECD calculations. All α-pyrones except 6 were evaluated for their stimulatory effects on glucose uptake in vitro with CHO-K1/GLUT4 cells. The positive control insulin displayed an approximate 42 ± 0.14% promotion on glucose uptake at 25 µM, compared with the CHO-K1/GLUT4 group. Compounds 1a/2a, 2, 3, and 10 showed a more significant stimulation of glucose uptake than insulin (25 µM) by 36 ± 0.08%, 27 ± 0.12%, 28 ± 0.12%, and 25 ± 0.12% at 1.5 µM, respectively. Immunofluorescence assays indicated the glucose uptake-stimulatory activity of α-pyrones might be correlated with increased GLUT4 translocation.

Two new isoquinoline alkaloids from Cryptocarya wrayi and their biological activities.

Two new isoquinoline alkaloids, cryptowrayines A (1) and B (2), along with one known pavine alkaloid (-)-12-hydroxyeschscholtzidine (3), were isolated from the twigs of Cryptocarya wrayi. The structures of new compounds were elucidated by extensive spectroscopic data analysis and electronic circular dichroism (ECD) calculations. Both compounds 1 and 2 exhibited moderate quinone reductase inducing activity in Hepa 1c1c7 cells.

Tyrosinase inhibitors from the leaves of Eucalyptus globulus.

A new isoiphionane sesquiterpene, named (3S, 5S, 7S, 10R)-3, 11-dihydroxyisoiphion-4-one (1), two new phloroglucinol glycosides, named eucalglobuside A (2) and eucalglobuside B (3), along with 15 known compounds were isolated from the leaves of Eucalyptus globulus. Their structures were elucidated based on extensive spectroscopic analysis and in comparison with literature data. The absolute configuration of compound 1 was determined by ECD calculation. All isolates were evaluated their inhibitory activities against the mushroom tyrosinase. As a result, three sesquiterpenoids, 1, 5ß, 11-dihydroxy-iphionan-4-one (5), and (-)-globulol (8), exhibited the most potent activities with IC50 values of 14.17 µM, 10.08 µM and 9.79 µM, respectively.

Artopithecins A-D, Prenylated 2-Arylbenzofurans from the Twigs of Artocarpus pithecogallus and Their Tyrosinase Inhibitory Activities.

Four new prenylated 2-arylbenzofurans, namely artopithecins A-D (1-4), together with five known compounds (5-9) were isolated from the twigs of Artocarpus pithecogallus for the first time. Their structures were elucidated based on extensive spectroscopic analysis and in comparison with literature data. All isolates were evaluated for their inhibitory activities against mushroom tyrosinase. Compounds 3 and 4 displayed significant tyrosinase inhibitory activities with IC50 values of 37.09±0.33 and 38.14±0.21 µM, respectively.

Prenylflavonoids from the Twigs of Artocarpus nigrifolius.

Two new prenylated flavones, artocarnin A (2) and carpachromenol (12), together with 13 known prenylflavonoids (1, 3-11, 13-15) were isolated from the twigs of Artocarpus nigrifolius for the first time. Their structures were elucidated by high resolution-electrospray ionization (HR-ESI)-MS, NMR spectroscopic analysis, and in comparison with the reported data. Compounds 1-15 were evaluated for their antiproliferative effects against SiHa and SGC-7901 human cancer cell lines in vitro. The most active compound, eleocharin A (10), showed significant cytotoxicity on SiHa cells (IC50=0.7±0.1 µM) and inhibitory activity against SGC-7901 cells (IC50=8.3±0.2 µM) and could be considered as potential lead compound for further development of novel anti-tumor agents.

Rifamycin S and its geometric isomer produced by a newly found actinomycete, Micromonospora rifamycinica.

Strain AM105 was separated from mangrove sediment in the South China Sea in this research. The morphological and genomic data showed that the strain merits description as a novel species, proposed as Micromonospora rifamycinica. From the acetate ethyl extract of its fermentation broth, two antibiotics against Gram-positive bacteria (including MRSA), rifamycin S and its geometric isomer were isolated. Their structures were elucidated on the basis of spectroscopic analyzes. (1)H and (13)C NMR data of the isomer of rifamycin S were first described in this paper.

Antimicrobial diterpenes from Trigonostemon chinensis.

Five new diterpenes, trigonochinenes A-E (1-5), and two known ones, 3,4- seco-sonderianol (6) and 3,4- seco-sonderianic acid (7), were isolated from the aerial part of Trigonostemon chinensis. Compounds 1-4 possess a rare 3,4-seco-cleistanthanic skeleton, and compound 5 is a highly aromatized tetranorditerpene. Structures of these compounds were elucidated by spectroscopic analysis. The antimicrobial activities of compounds 1-7 were evaluated against a panel of bacteria and fungi.

Sesquiterpenoids from Hedyosmum orientale.

Five new guaiane-type sesquiterpenoids, hedyosumins A-E (1-5), together with five known ones (6-10), were isolated from the aerial parts of Hedyosmum orientale. Two known sesquiterpenoids, 10alpha-hydroxy-1,5alpha H-guaia-3,7(11)-dien-8alpha,12-olide and 9alpha-hydroxyasterolide, were obtained as natural products for the first time. Their structures were elucidated on the basis of spectroscopic methods. 9alpha-Hydroxyasterolide (7) showed moderate activities against A-549 and HL-60 tumor cell lines with the IC 50 values of 3.1 and 8.8 microM, respectively.

Walsucochins A and B with an unprecedented skeleton isolated from Walsura cochinchinensis.

Walsucochins A (1) and B (2) with an unprecedented skeleton were isolated from Walsura cochinchinensis. Their structures including absolute configuration were elucidated by spectral methods. A biosynthetic pathway of 1 and 2 was postulated. Both 1 and 2 exhibited significant cell protecting activities against H2O2-induced PC12 cell damage.