Avian hepatic T-3 production by two pathways of 5'-monodeiodination: effects of fasting and patterns during development.
Avian hepatic T-3 production by two pathways of 5'-monodeiodination: effects of fasting and patterns during development.
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禽类肝脏 T-3 通过 5-单碘化的两种途径产生：禁食和发育过程模式的影响。
DOI：
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
F. McNabb
中科院分区：
文献类型：
--
作者：
T. Hughes;F. McNabb
本文研究了成体和发育期鹌鹑肝脏匀浆中5‘-脱碘酶(5’-D)的两种形态。此外，还观察了成年禁食和胚胎用皮质酮治疗对5‘-D的影响。在大量底物(T4)和辅因子(二硫苏糖醇；DTT)存在的情况下，测定肝脏匀浆的5‘-D活性。在37摄氏度下孵育15分钟时，通过基于乙醇的RIA评估T3的生成。在成人中，肝脏匀浆中既存在I型(丙基硫氧嘧啶(PTU)抑制活性的部分)，也存在推测的II型(PTU不敏感部分)。第二类活动通常占总活动的30%左右。孵化期为16.5d，孵化期为第15天，孵化时I型酶活性增加20倍，至21日龄时达到成虫水平，随后逐渐下降。II型活动存在于所有发育阶段，并在围产期最高。体内皮质酮治疗在发育第13天诱导肝脏匀浆中的I型和II型活性在治疗后24小时和48小时都增加。这项研究表明，在禽类肝脏中存在一种推测的II型5‘-D活性(通常被认为是哺乳动物肝脏中缺乏的)，并且在禁食期间维持组织中最低浓度的组织T3方面可能是重要的。两种类型的5‘-D对血清T_3浓度的发育模式都有贡献。在胚胎生命后期，II型占总活动量的很大比例；I型在围产期开始时占主导地位。
Two forms of iodothyronine 5'-monodeiodinase (5'-D) were studied in liver homogenates from adult and developing quail. The influence of fasting in adults and corticosterone treatment in embryonic quail on 5'-D also were examined. Liver homogenates were assayed for 5'-D activity in the presence of abundant substrate (T4) and cofactor (dithiothreitol; DTT). Generation of T3 during a 15 min incubation at 37 degrees C was assessed by an ethanol-based RIA. In adults, both Type I [the fraction of activity inhibited by propylthiouracil (PTU)] and a putative Type II (the PTU-insensitive fraction) were present in liver homogenates. Type II activity typically comprised about 30% of Total activity. Type I activity first appeared on day 15 of the 16.5 day incubation period, increased 20-fold to peak at hatching, then gradually declined to reach adult levels by 21 days of age. Type II activity was present at all developmental stages and was highest during the perinatal period. Corticosterone treatment in vivo on day 13 of development induced increases in both Type I and Type II activities in liver homogenates 24- and 48-h after treatment. This study demonstrates that in avian liver a putative Type II 5'-D activity (generally considered to be lacking in mammalian liver) is present and may be important in the maintenance of minimal concentrations of tissue T3 during fasting. Both types of 5'-D contribute to the developmental pattern of serum T3 concentrations. Type II comprises a large proportion of total activity during late embryonic life; Type I becomes predominant at the beginning of the perinatal period.(ABSTRACT TRUNCATED AT 250 WORDS)
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影响因子：
4.8
作者：
Borges,M;Eisenstein,Z;Burger,AG;Ingbar,SH
通讯作者：
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DOI：
10.1172/jci111313
发表时间：
1984
期刊：
The Journal of clinical investigation
影响因子：
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作者：
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影响因子：
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作者：
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影响因子：
4.8
作者：
Silva,JE;Matthews,P
通讯作者：
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影响因子：
4.8
作者：
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通讯作者：
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