The Effect of Levothyroxine Treatment on Resting Energy Expenditure of Hypothyroid Dogs

Thirty adult, client-owned dogs were diagnosed with hypothyroidism based on history, physical examination findings, hematologic and biochemical abnormalities, thyrotropin (TSH) response testing, endogenous canine thyrotropin (cTSH) concentration, or both, and total serum thryoxine concentration. All dogs received levothyroxine (L-thyroxine) at an initial dose of 22 μg/kg PO sid in either a tablet (13 dogs) or chewable form (17 dogs). Energy expenditure of each dog during apparent rest was estimated with an open-flow indirect calorimetry system by determining the rates of carbon dioxide production and oxygen consumption. Energy expenditure of apparent rest (EE) was lower in untreated hypothyroid dogs compared with reference values for EE. After treatment with L-thyroxine, EE of the hypothyroid dogs was significantly ( P < .05) higher than pretreatment values.     

几种抑制木薯采后生理性变质发生方法的比较

比较了热激、酸化和隔绝氧气3种处理对木薯采后生理性变质的影响，结果显示，热激和酸化都能在一定程度上延缓木薯PPD的发生，隔绝氧气是最为理想的抑制木薯PPD发生的方法。因此，通过过量表达或者干扰某些基因表达，降低以至于去除伤口处的氧气的方法将是防治木薯采后生理性变质的有效途径。     

Effects of 5‐aminolevulinic acid on water uptake,ionic toxicity,and antioxidant capacity of Swiss chard (Beta vulgaris L.) under sodic‐alkaline conditions

Sodic‐alkalinity may be more deleterious to plant growth than salinity. The objectives of this study were to determine whether 5‐aminolevulinic acid (ALA: an essential precursor for chlorophyll biosynthesis) foliar application could improve the sodic‐alkaline resistance of Swiss chard (Beta vulgaris L. subsp. cicla ) by regulating water uptake, ionic homeostasis, photosynthetic capacity, and antioxidant metabolism. Eight‐week‐old uniform plants were grown in nutrient medium without and with a sodic‐alkaline regime generated by a mixture of NaHCO₃ and Na₂CO₃ (NaHCO₃ : Na₂CO₃ = 9:1 molar ratio) for 12 d, and leaves were sprayed daily with water or ALA. The Na⁺ and ALA concentrations were gradually increased to 60 mM and 120 μM, respectively. ALA foliar application alleviated the physiological damage from sodic‐alkalinity, as reflected by the increases in plant dry weight, relative growth rate, chlorophyll, Mg²⁺ concentration, and the decrease in Na⁺ concentration. However, ALA foliar application did not change the water uptake capacity or the concentration of K⁺, Fe³⁺, and endogenous ALA in leaf tissues under sodic‐alkaline conditions. ALA foliar application effectively mitigated damage from sodic‐alkalinity because of the increased activity of antioxidant enzymes (catalase and guaiacol peroxidase), particularly superoxide dismutase activity, which was maintained at the same level as for control plants. These results suggest that ALA foliar application alleviated sodic‐alkaline stress mainly owing to its antioxidant capacity, and superoxide dismutase has the main responsibility for reducing oxidative stress in Swiss chard.     

Splenectomy enhances sensitivity of islets to STZ in mice

AIM: To explore the protective role of spleen in damage of islet beta cells induced by streptozotocin (STZ).METHODS: Splenectomy in mice was performed by surgery. Sixty splenectomy mice were divided into 3 groups as the mice were intraperitoneally injected with STZ at doses of 80 mg/kg or 160 mg/kg, and saline, respectively. Sixty normal mice (without splenectomy) were also grouped and treated as above for controls. One week later, fasting blood glucose and serum insulin were monitored,and beta cell mass and the apoptosis of islet cells were analyzed by the methods of immunohistochemistry and ELISA, respectively. The content of reactive oxygen species was determined by the method of luminol-enhanced chemiluminescence.RESULTS: Compared to the normal control mice, the concentrations of fasting blood glucose significantly increased, and serum insulin reduced in splenectomy mice treated with STZ at the dose of 80 mg/kg. Moreover, beta cell mass decreased, enrichment factor of nucleosomes of islet apoptotic cells and reactive oxygen species produced in pancreas tissues significantly increased in splenectomy mice treated with STZ at the dose of 80 mg/kg.CONCLUSION: Splenectomy increases the sensitivity of islets to STZ in mice by increasing the production of reactive oxygen species in pancreas.     

Polyamines enhance chilling tolerance of cucumber (Cucumis sativus L.) through modulating antioxidative system

Cucumber chilling-resistant cultivar Changchun mici and -sensitive cultivar Beijing jietou were used in this study to investigate the effects of exogenous PAs on protection against chilling injury as well as on changes of physiological features, and the fluctuation of free PAs content in the leaves under chilling stress. Upon chilling treatment, free spermidine (Spd), spermine (Spm) and putrescine (Put) were remarkably induced in the leaves of cv. Changchun mici 1 day after treatment. The induction of Put declined thereafter, whereas Spd and Spm levels increased steadily. In the leaves of cv. Beijing jietou, Put content was increased only at 1 day after chilling while Spd content decreased significantly upon chilling treatment. Chilling reduced soluble protein content, and decreased the activities of antioxidant enzymes, including superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) only in Beijing jietou. However, these changes could be renovated by exogenous application of Put and Spd. It was also found that pretreatment with Put and Spd diminished the increased electrolyte leakage and malondialdehyde (MDA) content caused by chilling in the leaves of both cultivars. Pretreatment of methyglyoxal-bis-(guanylhydrazone) (MGBG), the PAs biosynthetic inhibitor cancelled the effects of PAs in most of the treatments. Moreover, histochemical staining and quantitative measurements showed that exogenous application of Put and Spd eliminated but MGBG exaggerated the hydrogen peroxide (H₂O₂) accumulation caused by chilling stress, especially in leaves of Beijing jietou. Interestingly, Changchun mici was found to contain higher endogenous free PAs contents compared to Beijing jietou. While no significant difference of SOD, POD and CAT activities was found between non-chilling Changchun mici and Beijing jietou seedlings, the former exhibited higher APX activity than the latter. These results suggest that PAs play important roles in the tolerance of cucumber against chilling stress, which is most likely achieved by acting as oxidative machinery against chilling injury.     

吡啶甲酸铬安全性研究进展

吡啶甲酸铬作为有机铬添加剂，已成为普遍使用的铬营养补充物质。但目前尚未正式发布动物最低需要量和最高耐受量的具体数据。吡啶甲酸铬的安全性仍在研究探索之中，但得到的研究结果不尽一致。为此作者就吡啶甲酸铬的安全性研究及现有可能存在的代谢途径进行综述，以便为日后吡啶甲酸铬的研究提供理论基础。     

过饱和溶氧对大菱鲆生长及消化酶的影响

探讨工程化养殖中过饱和溶氧对大菱鲆生长的影响,通过充入液态氧与空气,使试验水体的溶氧分别达到过饱和溶氧水平(12±1)mg/L和(14±1)mg/L,正常溶氧水平(7.0±0.5)mg/L.结果显示,过饱和溶氧组的大菱鲆生长速度及饵料利用率明显高于正常溶氧组(p<0.05),而在过饱和溶氧条件下与正常溶氧条件下大菱鲆的丰满度无显著差异(P>0.05).对大菱鲆胃、肠道消化酶、脂肪酶与淀粉酶的分析发现,大菱鲆胃蛋白酶活性在过饱和溶氧条件下较正常溶氧有明显提高(p<0.05),而脂肪酶与淀粉酶的酶活力未得到显著性提高(p>0.05).     

空气负氧离子对鸡胚和雏鸡生长发育的影响

将星杂288鸡种蛋960枚随机分为4组,进行3周孵化试验,各组空气负氧离子浓度分别为200000、100000、50000和40个/cm3。再取孵出的雏鸡120只随机分为4组,进行6周饲养试验,所设负氧离子浓度分别为100000、50000、25000和30个/cm3。结果表明:(1)200000和100000个/cm3负氧离子有助于胚胎的生长发育,能提高种蛋的孵化率;(2)50000个/cm3负氧离子可降低雏鸡料肉比和死亡率,并能促进雏鸡的生长发育,改善雏鸡的某些血液生理生化指标;(3)25000个/cm3以上的负氧离子对孵化和育雏的空气环境有一定净化作用。     

Research on Magnetic Activated Carbon by XPS

DIntroduction'Asonekindofimportantedbent,activatedcarbo11wasusedinlnoreandl11orefieIds.MagneticactivatedcarbonisbecoIninganinterestil1gsubjectfOrsoIvi11gseparationofactivatedcarbo11i11thisfieId.Mag11eticactivatedcarbol1wl1ichusemagneticreagentandacti-vatedcarbonasrawmateriaIl1asmal1yadva11tagesl'Isuchasgiantspecificsurface'weII-distributiOI1al1d firmly-combined1nagl1e1ism.ButtI1eadsorptivemechanismoftl1emagneticreage11tol1activatedcarbonisstiIIunknown.X-rayphotoelectronpectroscopy(X…     

活性氧和一氧化氮在植物——病原体互作反应中的作用

植物被病原体感染后，植物体内活性氧产量急剧增加，这一现象被称为氧爆。活性氧族包括如单线态氧1O2、超氧阴离子自由基O2-.、氢过氧自由基HO2·、过氧化氢H2O2、羟自由基·OH等。与ROS关系密切的一氧化氮，属于活性氮族。ROS和NO参与植物生长发育调控和对环境胁迫的应答反应，特别是在对抗外来病原体的入侵的防卫过程中发挥了重要作用。本文主要讨论ROS和NO在植物与病原体相互作用中发挥的作用。