Thyroxine: convesion to triiodothyronine by isolated perfused rat heart

Thyroxine labeled with carbon-14 and iodine-125 was perfused through surviving rat hearts. Only when unlabeled triiodothyronine was added as a carrier could the newly formed doubly labeled triiodothyronine be isolated. The fact that this triiodothyronine was labeled with the correct ratio of carbon-14 to iodine-125 indicated that it originated from thyroxine. Approximately 5 percent of the initial carbon-14 radioactivity was found in the recovered triiodothyronine.     

Conversion of thyroxine to triiodothyronine in normal human subjects

The conversion of thyroxine to triiodothyronine, previously demonstrated in athyreotic human subjects, has been investigated in normal subjects who were given intravenous injections of purified thyroxine labeled with carbon-14 in ring A and in the alanine side chain. Evidence for the conversion of T4 to T3 was provided by the finding of carbon-14 in the T3 fraction isolated from serums. It is estimated that an appreciable fraction of T4 may be transformed to T3 in normal man.     

Prostaglandins stimulate thyroid function in pregnant women

Intravaginal or intravenous administration of prostaglandin F(2alpha) to pregnant women produced significant elevations of plasma triiodothyronine and thyroxine concentrations, but no rise of thyrotropin. These observations are consistent with those of previous in vitro studies indicating that prostaglandins can act directly on the thyroid gland to stimulate thyroid hormone synthesis or release, or both.     

Pyrazole-induced thyroid necrosis: a distinct organ lesion

One oral dose of pyrazole caused necrosis of rat thyroid follicular epithelial cells but spared the parafollicular (C) cells and the parathyroid glands. Serum thyroxine (T4) and triiodothyronine (T3) were significantly decreased on day 3 after pyrazole administration and were immeasurable on day 5. At day 5 the thyroid was enlarged and the concentration of thyroid-stimulating hormone in the serum was increased, indicating an appropriate pituitary response to a primary lesion in the thyroid. Doses of pyrazole which produced no morphologic change in the thyroids also significantly depressed the concentrations of T4 and T3 in the serum.     

Sulfhydryl groups and the monodeiodination of thyroxine to triiodothyronine

Sulfhydryl reagents exert a profound influence on the monodeiodination of thyroxine to triiodothyronine by rat and sheep tissues in vitro. A marked dithiothreitol-induced increase in the monodeiodination by fetal sheep liver homogenates suggests that the characteristically low conversion in fetal tissues is related more to the status of sulfhydryl groups than to a deficiency of the monodeiodinating enzyme.     

不同月龄香猪血清甲状腺激素水平的比较

用放射免疫测定法测定了５组不同月龄香猪血清总甲状腺激素（ＴｈｙｒｏｘｉｎｅＴ３ＴｒｉｉｏｄｏｔｈｙｒｏｎｉｎｅＴ４）含量．研究结果表明，不同月龄香猪血清Ｔ３和Ｔ４均在２月龄处于最高水中，１和３月龄处于中等水平，４和９月龄处于较低水平．同一月龄内Ｔ３和Ｔ４含量雌雄差异不显著（Ｐ＞０．０５），不同月龄间Ｆ检验Ｔ３和Ｔ４含量差异均极显著（Ｐ＜０．０１）．相对生长速度在２月龄最高，３月龄最低，４和９月龄居中．     

鸭血浆激素和脂质与瘦肉率和脂肪率关系的研究

本文研究了 Z-1系、Z-1×Z-2杂交一代和肖家河鸭3、7、8周龄血浆睾酮、甲状腺素(T_4)、三碘甲腺原氨酸(T_3)、总甘油三酯和总胆固醇(T-C)含量以及三个周龄中采血测定的各项指标平均值(Mean)与8周龄(市售周龄)屠宰时胴体瘦肉率和脂肪率以及其它胴体性状的相关关系。7周龄血浆睾酮含量(Z-1系和杂交鸭)以及 Mean睾酮含量(Z-1系)与瘦肉率间呈显著正相关;3周龄以及 Mean 甘油三酯含量(杂交鸭)与瘦肉率呈显著负相关;7周龄血浆 T-C 以及 Mean T-C 与瘦肉率呈显著正相关。3、7周龄血浆睾酮含量与脂肪率呈显著负相关;7、8周龄以及 Mean 甘油三酯含量与脂肪率间呈显著正相关;8周龄和 Mean T-C 与脂肪率呈显著负相关。本试验说明血浆激素和生化物质含量与瘦肉率和脂肪率的相关系数较低而且不稳定;血浆甘油三酯含量有可能做为预测瘦肉率和脂肪率的指标。     

肉鸡血浆激素含量与T淋巴细胞活性关系的研究

本试验以ＡＡ肉鸡父母代和商品代为材料,对其血浆中生长激素（ＧＨ）、甲状腺素（Ｔ４）、三碘甲腺原氨酸（Ｔ３）和皮质酮进行了测定,并对部分鸡进行马立克强毒接种,以探讨血浆激素与Ｔ淋巴细胞活性间的关系。结果表明,７周龄不同基因型鸡间血浆激素含量存在明显差异。血液Ｔ淋巴细胞活性在商品代明显高于父母代。马立克强毒接种后血浆高、低皮质酮水平间Ｔ淋巴细胞活性有明显差异。相关估计结果表明,血浆激素含量大多与Ｔ淋巴细胞呈低正相关,而皮质酮与Ｔ淋巴细胞呈负相关（Ｐ＜０．０５）。本研究结果指出,激素受环境因素影响较大,应用于抗病育种仍需进一步研究。     

Induction of autoimmune thyroiditis in chickens by dietary iodine

Clinical studies have suggested that excess dietary iodine promotes autoimmune thyroiditis; however, the lack of a suitable animal model has hampered investigation of the phenomenon. In this study, different amounts of potassium iodide were added to the diets of chicken strains known to be genetically susceptible to autoimmune thyroiditis. Administration of iodine during the first 10 weeks of life increased the incidence of the disease, as determined by histology and the measurement of autoantibodies to triiodothyronine, thyroxine, and thyroglobulin. Further support for the relation between iodine and autoimmune thyroiditis was provided by an experiment in which iodine-deficient regimens decreased the incidence of thyroid autoantibodies in a highly susceptible strain. These results suggest that excessive consumption of iodine in the United States may be responsible for the increased incidence of autoimmune thyroiditis.     

Modeling the relations of thyroid hormones in rats

The relations between the concentration of thyroxine, triiodothyronine, and thyrotropic hormone in the peripheral blood of white rats are studied in an experiment with the administration of a thyrostatic drug (merkazolil) in an optimally allowable daily dose. A high reliability of the mathematical model developed for reproducing the level of the content of hormones of the hypophysial-thyroid system is established.     

中药饲料添加剂对断奶仔猪生长性能和内分泌功能的影响

选取胎次相近、日龄相同的杜—长—大哺乳仔猪16窝,随机分为4组,中药Ⅰ、Ⅱ组和抗生素组在相同的基础日粮中分别添加中药饲料添加剂Ⅰ(4 kg.t-1)、中药饲料添加剂Ⅱ(4 kg.t-1)和金霉素(70 g.t-1)+杆菌肽锌(30 g.t-1),对照组仔猪只饲喂基础日粮.于仔猪断奶前3 d,断奶后1、4、7、14、28 d采血,对血液部分激素指标进行分析,研究中药饲料添加剂对断奶仔猪生长性能和内分泌功能的影响.结果表明:(1)2个中药组仔猪日增重提高,料重比和腹泻率降低.(2)断奶后1 d,各组仔猪血清皮质醇含量与断奶前相比升高,而三碘甲腺原氨酸(T3)和甲状腺素(T4)含量较断奶前降低;整个试验期间,2个中药组血清皮质醇含量始终较抗生素组和对照组低,T3、T4含量始终高于抗生素和对照组.可见,中药饲料添加剂能有效地防止早期断奶仔猪发生腹泻,降低仔猪血清皮质醇含量,提高T3、T4的含量,缓解仔猪应激,改善仔猪的生长性能.     

酵母铬对热应激蛋用种公鸡精液品质的影响及作用机制研究

选用72只35周龄罗曼种公鸡随机平均分成6组,对照组饲喂基础日粮,分别在基础日粮中添加0.2、0.4、0.6、0.8、1.0 mg/kg铬量的酵母铬,作为试验I、II、III、IV、V组来探讨酵母铬对热应激蛋用种公鸡精液品质及内分泌机能的影响.结果表明:与对照组相比,日粮中添加0.4、0.6、0.8、1.0 mg/kg铬量的酵母铬均不同程度提高公鸡的精液量、精子活力和精子密度,降低公鸡精液的精子畸形率,而对精液的pH值影响不明显;试验各组公鸡血浆三碘甲腺原氨酸(T3)水平均有不同程度升高;皮质醇、甲状腺素 (T4)水平降低.上述结果表明:在热应激条件下,日粮中添加一定量的酵母铬可有效缓解热应激,显著提高夏季蛋用种公鸡的繁殖性能并影响其内分泌机能.     

二氢吡啶(Diludin)对产蛋鸡内分泌的影响

１ ０２４羽３００日龄罗曼蛋鸡随机分４组,分别饲喂二氢吡啶（Ｄｉｌｕｄｉｎ）添加量０,１００,１５０,２００ ｍｇ／ｋｇ的４种饲粮,于饲喂后第３０日和第８０日采血和屠宰,研究其对蛋鸡内分泌功能的影响。结果显 示：Ｄｉｌｕｄｉｎ均显著地提高了腺垂体和血清中ＦＳＨ,ＬＨ含量,其中垂体ＦＳＨ和ＬＨ含量随饲喂剂量提高 而增加,血清ＦＳＨ和ＬＨ含量以１５０ ｍｇ／ｋｇ组效果最佳;Ｄｉｌｕｄｉｎ提高了血清Ｔ３含量,Ｔ４差异不显著, ３０日Ｔ３随饲粮中Ｄｉｌｕｄｉｎ递增而增加,８０日１５０,２００ ｍｇ／ｋｇ组与对照组差异显著;饲粮中添加Ｄｉｌｕｄｉｎ 具有改进血清雌二醇（Ｅ２）水平,其中８０ 日 １５０,２００ ｍｇ／ｋｇ组与对照组差异显著;１５０ ｍｇ／ｋｇ Ｄｉｌｕｄｉｎ显 著提高血清中孕酮（Ｐ４）含量;饲粮中添Ｄｉｌｕｄｉｎ显著提高下丘脑和腺垂体中ｃＡＭＰ含量。     

Phase modifiers promote efficient production of hydroxymethylfurfural from fructose

Furan derivatives obtained from renewable biomass resources have the potential to serve as substitutes for the petroleum-based building blocks that are currently used in the production of plastics and fine chemicals. We developed a process for the selective dehydration of fructose to 5-hydroxymethylfurfural (HMF) that operates at high fructose concentrations (10 to 50 weight %), achieves high yields (80% HMF selectivity at 90% fructose conversion), and delivers HMF in a separation-friendly solvent. In a two-phase reactor system, fructose is dehydrated in the aqueous phase with the use of an acid catalyst (hydrochloric acid or an acidic ion-exchange resin) with dimethylsulfoxide and/or poly(1-vinyl-2-pyrrolidinone) added to suppress undesired side reactions. The HMF product is continuously extracted into an organic phase (methylisobutylketone) modified with 2-butanol to enhance partitioning from the reactive aqueous solution.     

热应激状态下阿司匹林对蛋鸡产蛋性能和蛋品质的影响

在热应激条件下,研究了不同水平阿司匹林对蛋鸡产蛋性能和蛋品质的影响,并探讨了其作用机制.结果表明:蛋鸡日粮中添加500和1 000 mg/kg阿司匹林分别能显著提高产蛋率6.60%(P<0.05)和7.46%(P<0.05),降低料蛋比6.22%(P<0.05)和7.05%(P<0.05);500、1 000和1 500 mg/kg阿司匹林均能提高蛋壳厚度(P<0.05)和蛋壳相对重(P<0.05),并降低破蛋率和异常蛋的百分率(P<0.01).研究发现,适量阿司匹林可以提高血清中总蛋白(P<0.05)和白蛋白含量(P<0.05),降低尿酸含量(P<0.05);并提高碱性磷酸酶活性(P<0.05)、血清钙(P<0.05)和磷(P<0.05)的水平.阿司匹林还具有提高促卵泡生成素(FSH)(P<0.01),降低三碘甲腺原氨酸(T3)、甲状腺素(T4)(P<0.05),提高甲状旁腺素和前列腺素(P<0.05)的作用.上述结果提示:在热应激条件下,阿司匹林通过影响神经内分泌活动,可以促进蛋白质和钙、磷的代谢,提高蛋鸡产蛋率和改进蛋壳品质.     

Hormonal effects on ontogeny of swimming ability in the rat: assessment of central nervous system development

The maturation of swimming behavior and the evoked cortical response to sciatic stimulation were studied in newborn rats receiving thyroxine or cortisol. Compared to that of controls the maturation of swimming is accelerated or delayed 2 to 3 days by thyroxine or cortisol treatment, respectively, and this corresponds to ontogenetic shifts in the characteristics of the evoked potential. Front leg movement during swimming normally diminishes at about 16 days of age and is inhibited by day 22. Thyroxine also advances and cortisol delays the age at which this inhibitory mechanism becomes evident, and compresses (thyroxine) or expands (cortisol) the time interval over which it becomes functional. During early postnatal life certain circuilating hormones can affect the rate and chronology of central nervous system maturation. Swimming behavior may be a simple model to use in studies concerned with factors affecting the functional and behavioral development of the central nervouts system.     

Synthetic polypeptide antagonists of the hypothalamic luteinizing hormone releasing factor

Two analogs of the hypothalamic luteinizing hormone releasing factor modified at the histidine-2 position were tested for biological activity (secretion of luteinizing hormone) in cultures of dispersed rat anterior pituitary cells. The analog in which glycine was substituted for histidine at position 2, [Gly(2)]LRF, behaves as a partial agonist releasing less than 50 percent of the luteinizing hormone secreted at maximum concentrations of the releasing factor, while the analog in which histidine at position 2 is deleted has no significant agonist activity at any of the doses tested. When added to the cultured cells at molar ratios 10(3) to 10(4) times that of the luteinizing hormone releasing factor, both analogs decrease the amount of luteinizing hormone secreted in response to the releasing factor.     

Goblet cells in embryonic intestine: accelerated differentiation in culture

If duodenal tissue from 14-day chick embryos is cultured in chemically defined medium, more than twice as many goblet cells appear within 48 hours as in intact embryos during the same time. The increase in goblet cell number is further accelerated by 10(-9) molar thyroxine but is prevented by 10(-6) molar hydrocortisone. The results suggest that differentiation of intestinal epithelium is regulated in part by a circulating inhibitor.     

High-frequency switching of colony morphology in Candida albicans

The pathogenic yeast Candida albicans switches heritably and at high frequency between at least seven general phenotypes identified by colony morphology on agar. Spontaneous conversion from the original smooth to variant phenotypes (star, ring, irregular wrinkle, hat, stipple, and fuzzy) occurs at a combined frequency of 1.4 X 10(-4), but is increased 200 times by a low dose of ultraviolet light that kills less than 10 percent of the cells. After the initial conversion, cells switch spontaneously to other phenotypes at a combined frequency of 2 X 10(-2). Switching is therefore heritable, but also reversible at high frequency. The genetic basis of this newly discovered process and its possible role in Candida pathogenesis are considered.     

Thyroxine-binding globulin: characterization of the binding site with a fluorescent dye as a probe

The fluorescent dye 1,8-anilinonaphthalenesulfonate competed with thyroxine for binding to thyroxine-binding globulin. Fluorescence analysis indicated that the dye bound to the globulin in a molar ratio of 1:1 and with an association constant (at 23 degrees C) of 4.19 x10(6)M(-1), and that thyroxine bound to the globulin in a molar ratio of 1:1 and with an association constant (at 23 degrees C) of 2.35x10(10)M(-1). Displacement of globulin-bound dye by thyroxine was shown by fluorescence quenching, and displacement of globulin-bound thyroxine by dye was demonstrated by ultrafiltration.