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4,981 results on '"Dong Zhi"'

59. Prenatal diagnosis of oral teratoma by ultrasound

Author

Yan-Lin Li, Li Zhen, and Dong-Zhi Li

Subjects
airway obstruction, fetal teratoma, oral mass, polyhydramnios, prenatal diagnosis, Medical technology, R855-855.5
Abstract

A pregnant woman had a normal second-trimester anatomic survey at 22 weeks gestation. She was revealed to have a fetal oral mass with polyhydramnios and invisible stomach bubble by ultrasound at 28 weeks. A 50 mm × 36 mm × 42 mm, solid mass was found in the fetal mouth, filling the entire oral cavity. Fetal magnetic resonance imaging showed a homogeneous solid mass in the oral cavity compressing the hypopharynx. At 33 weeks, preterm labor occurred because of the continuation of increased amniotic fluid volume, and a female infant was vaginally delivered. The infant died shortly after tracheal intubation attempt failed. Autopsy confirmed the prenatal sonographic finding. The final pathologic diagnosis was oral immature teratoma. Our study indicates that although oral teratomas are rare, they are readily apparent at prenatal sonographic examinations. Respiratory compromise is the frequent complication of oral teratomas, which is associated with high perinatal mortality.

Published
2024
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95. Unravelling and engineering an operon involved in the side-chain degradation of sterols in Mycolicibacterium neoaurum for the production of steroid synthons

Author

Yun-Qiu Zhao, Yong-Jun Liu, Lu Song, Dingyan Yu, Kun Liu, Ke Liu, Bei Gao, Xin-Yi Tao, Liang-Bin Xiong, Feng-Qing Wang, and Dong-Zhi Wei

Subjects
Mycolicibacteria, HBC sub-pathway, atf1, HBC operon, C-22 steroid, 4-HBC, Biotechnology, TP248.13-248.65, Fuel, TP315-360
Abstract

Abstract Background Harnessing engineered Mycolicibacteria to convert cheap phytosterols into valuable steroid synthons is a basic way in the industry for the production of steroid hormones. Thus, C-19 and C-22 steroids are the two main types of commercial synthons and the products of C17 side chain degradation of phytosterols. During the conversion process of sterols, C-19 and C-22 steroids are often produced together, although one may be the main product and the other a minor byproduct. This is a major drawback of the engineered Mycolicibacteria for industrial application, which could be attributed to the co-existence of androstene-4-ene-3,17-dione (AD) and 22-hydroxy-23,24-bisnorchol-4-ene-3-one (HBC) sub-pathways in the degradation of the sterol C17 side chain. Since the key mechanism underlying the HBC sub-pathway has not yet been clarified, the above shortcoming has not been resolved so far. Results The key gene involved in the putative HBC sub-pathway was excavated from the genome of M. neoaurum by comparative genomic analysis. Interestingly, an aldolase- encoding gene, atf1, was identified to be responsible for the first reaction of the HBC sub-pathway, and it exists as a conserved operon along with a DUF35-type gene chsH4, a reductase gene chsE6, and a transcriptional regulation gene kstR3 in the genome. Subsequently, atf1 and chsH4 were identified as the key genes involved in the HBC sub-pathway. Therefore, an updated strategy was proposed to develop engineered C-19 or C-22 steroid-producing strains by simultaneously modifying the AD and HBC sub-pathways. Taking the development of 4-HBC and 9-OHAD-producing strains as examples, the improved 4-HBC-producing strain achieved a 20.7 g/L production titer with a 92.5% molar yield and a 56.4% reduction in byproducts, and the improved 9-OHAD producing strain achieved a 19.87 g/L production titer with a 94.6% molar yield and a 43.7% reduction in byproduct production. Conclusions The excellent performances of these strains demonstrated that the primary operon involved in the HBC sub-pathway improves the industrial strains in the conversion of phytosterols to steroid synthons.

Published
2023
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