A need for exogenous nucleotides may be expected when the body is growing rapidly or encounters immune challenge.

但机体在快速生长或受到免疫挑战时，需要外源添加核苷酸。

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Two trials were conducted to study Glucagon-like peptide 2 secretion in postweaning piglets and the effect of immune challenge on gut development and GLP-2 level.

通过2个试验研究了断奶仔猪胰高血糖素-2（GLP-2）的分泌规律和免疫应激对断奶仔猪肠道发育及GLP-2分泌的影响。

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A major challenge in treating pancreatic tumors is overcoming their ability to force immune cells to tolerate and even support their growth.

治疗胰腺肿瘤一项重要的挑战是如何来克服这些肿瘤使免疫细胞耐受甚至支持肿瘤生长的能力。

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What is more, such decisions are immune to challenge in the normal legislative process.

ECONOMIST: Letters

Recent discoveries have led to advances in how to unleash the immune system, though one challenge has been to jump-start the body's defenses without injury to healthy, normal cells.

WSJ: New Cancer Drugs Use Body's Own Defenses