BACKGROUND: The novel coronavirus disease 2019 (COVID-19) constitutes a public health emergency globally. The number of infected people and deaths are proliferating every day, which is putting tremendous pressure on our social and healthcare system. Rapid detection of COVID-19 cases is a significant step to fight against this virus as well as release pressure off the healthcare system. OBJECTIVE: One of the critical factors behind the rapid spread of COVID-19 pandemic is a lengthy clinical testing time. The imaging tool, such as Chest X-ray (CXR), can speed up the identification process. Therefore, our objective is to develop an automated CAD system for the detection of COVID-19 samples from healthy and pneumonia cases using CXR images. METHODS: Due to the scarcity of the COVID-19 benchmark dataset, we have employed deep transfer learning techniques, where we examined 15 different pre-trained CNN models to find the most suitable one for this task. RESULTS: A total of 860 images (260 COVID-19 cases, 300 healthy and 300 pneumonia cases) have been employed to investigate the performance of the proposed algorithm, where 70% images of each class are accepted for training, 15% is used for validation, and rest is for testing. It is observed that the VGG19 obtains the highest classification accuracy of 89.3% with an average precision, recall, and F1 score of 0.90, 0.89, 0.90, respectively. CONCLUSION: This study demonstrates the effectiveness of deep transfer learning techniques for the identification of COVID-19 cases using CXR images.

Partial inactivation of PLK-1 in the embryo leads to the formation of two nuclei containing either maternal or paternal chromosomes. This is due to a defect in forming a nuclear envelope gap at the interface of the maternal and paternal pronuclei. Moreover, this gap formation is linked to proper chromosome alignment during the first mitosis.

O-linked-β-N-acetylglucosamine (O-GlcNAc) modification is a regulatory, nuclear and cytoplasmic post-translational glycosylation of proteins associated with age-related diseases such as Alzheimer's, Parkinson's, and type II diabetes. Global elevation of O-GlcNAc levels on intracellular proteins can induce insulin resistance, the hallmark of type II diabetes, in mammalian systems. In C. elegans, attenuation of the insulin-like signal transduction pathway increases adult lifespan of the nematode. We demonstrate that the O-GlcNAc cycling enzymes OGT and OGA, which add and remove O-GlcNAc respectively, modulate lifespan in C. elegans. Median adult lifespan is increased in an oga-1 deletion strain while median adult life span is decreased upon ogt-1 deletion. The O-GlcNAc-mediated effect on nematode lifespan is dependent on the FoxO transcription factor DAF-16. DAF-16 is a key factor in the insulin-like signal transduction pathway to regulate reproductive development, lifespan, stress tolerance, and dauer formation in C. elegans. Our data indicates that O-GlcNAc cycling selectively influences only a subset of DAF-16 mediated phenotypes, including lifespan and oxidative stress resistance. We performed an affinity purification of O-GlcNAc-modified proteins and observed that a high percentage of these proteins are regulated by insulin signaling and/or impact insulin pathway functional outcomes, suggesting that the O-GlcNAc modification may control downstream effectors to modulate insulin pathway mediated cellular processes.

Summary Here we describe an in vitro primary culture system for C. elegans germline stem cells. This culture system was used to identify a bacterial folate as a positive regulator of germ cell proliferation. Folates are a family of B-complex vitamins that function in one-carbon metabolism to allow the de novo synthesis of amino acids and nucleosides. We show that germ cell proliferation is stimulated by the folate 10-formyl-tetrahydrofolate-Glun both in vitro and in animals. Other folates that can act as vitamins to rescue folate deficiency lack this germ cell stimulatory activity. The bacterial folate precursor dihydropteroate also promotes germ cell proliferation in vitro and in vivo, despite its inability to promote one-carbon metabolism. The folate receptor homolog FOLR-1 is required for the stimulation of germ cells by 10-formyl-tetrahydrofolate-Glun and dihydropteroate. This work defines a folate and folate-related compound as exogenous signals to modulate germ cell proliferation.