Circadian rhythm in pineal tyrosine hydroxylase

Tyrosine hydroxylase is the rate-limiting enzyme in catecholamine synthesis. The rat pineal gland is richly innervated by sympathetic nerves from the superior cervical ganglia. The activity of tyrosine hydroxylase was measured in rat pineal gland at 4-hour intervals over a daily cycle of 12 hours of light (7 a.m. to 7 p.m.) and 12 hours of darkness. The results indicate a circadian rhythm with the maximum activity, at 11 p.m. to 3 a.m., about triple the low values observed at 3 p.m. The pattern is similar in phase to that previously reported for melatonin and hydroxyindole-O-methyl transferase activity.     

Daily light sensitivity rhythm in a rodent

Single 10-minute light periods can cause a phase shift in the rhythm of the daily locomotor activity of flying squirrels otherwise maintained in constant darkness. A daily rhythm of sensitivity to these standard light periods was found.     

Daily variation in concentration of cortisol in plasma in intact and hypophysectomized gulf killifish

A daily variation in concentration of cortisol in plasma is synchronized by a 12-hour daily photoperiod in intact as well as in hypophysectomized fish. The daily rhythm in concentration of the adrenal steroid does not depend on a daily rhythm in the concentration of pituitary adrenocorticotropic hormone.     

Brain catechol synthesis: control by train tyrosine concentration

Brain catechol synthesis was estimated by measuring the rate at which brain dopa levels rose following decarboxylase inhibition. Dopa accumulation was accelerated by tyrosine administration, and decreased by treatments that lowered brain tyrosine concentrations (for example, intraperitoneal tryptophan, leucine, or parachlorophenylalanine). A low dose of phenylalanine elevated brain tyrosine without accelerating dopa synthesis. Our findings raise the possibility that nutritional and endocrine factors might influence brain catecholamine synthesis by controlling the availability of tyrosine.     

Feeding schedule alteration of daily rhythm in tyrosine alpha-ketoglutarate transaminase of rat liver

Liver tyrosine alpha-ketoglutarate transaminase has a daily rhythm such that in rats fed on an unrestricted basis the activity is highest at approximately 11:00 p.m. In contrast, rats fed only from 8:00 a.m. to noon show a markedly different rhythm in the enzyme, with maximum activity at 11:00 a.m. Controlling the time of food intake seems to be a useful means of studying the mechanism of the daily changes in this enzyme.     

Circadian changes in enzyme concentration account for rhythm of enzyme activity in gonyaulax

A circadian rhythm in the activity of luciferase is partly responsible for rhythmic bioluminescence in the dinoflagellate alga Gonyaulax polyedra. The cyclic activity of this enzyme can be attributed to a corresponding rhythm in the concentration of immunologically reactive luciferase protein. Hence protein turnover (synthesis or degradation or both) is used by the endogenous clock to control the daily rhythm of bioluminescence.     

低蛋白日粮添加酪氨酸对育肥猪生长性能和氮代谢的影响

试验选取30头平均体重为(60±0.20)kg杜×长×大三元杂交育肥猪,随机分为3个日粮处理:正常蛋白日粮(对照组,14.52%蛋白),低蛋白日粮添加0.49%丙氨酸(负对照组,12.52%蛋白),低蛋白日粮添加1.0%酪氨酸(试验组,12.52%蛋白)。每组10个重复,每个重复1头猪,试验期为6周。试验结果表明,①饲喂低蛋白日粮对育肥猪平均日增重、平均日采食量和料重比无显著影响(P>0.05)。②与对照组相比,负对照组和试验组摄入氮均显著降低(P<0.05),尿氮排放量和总氮排放量均显著下降(P<0.05),粪氮排放量无显著差异(P>0.05),但在低蛋白日粮中添加酪氨酸可显著提高蛋白质表观生物学价值和净蛋白利用率(P<0.05)。③与对照组相比,负对照组和试验组血清尿素氮含量均显著下降(P<0.05),其余血液生化指标各组间差异不显著(P>0.05)。④与对照组相比,降低日粮蛋白水平对育肥猪胴体重、屠宰率、背膘厚、胴体直长和胴体斜长均无显著影响(P>0.05)。⑤饲喂低蛋白日粮对育肥猪背肌pH45min、pH24h、蒸煮损失和滴水损失与对照组相比均无显著差异(P>0.05),但低蛋白日粮中添加酪氨酸可显著提高肉色红度值(P<0.05)。⑥与对照组相比,饲喂低蛋白日粮对育肥猪血浆激素水平无显著影响(P>0.05)。综上所述,饲喂低蛋白日粮不影响育肥猪生长性能并减少氮排放,补充酪氨酸可提高育肥猪表观生物学价值和净蛋白利用率并改善肉色。试验填补酪氨酸在低蛋白日粮中研究空白,为相关研究提供新思路。     

Decreased concentration of phenacetin in plasma of cigarette smokers

The amount of phenacetin in plasma was determined in nine control subjects (nonsmokers) and nine subjects who smoked at least 15 cigarettes per day. The mean plasma concentration of phenacetin at 1, 2, 3(1/2), and 5 hours after its administration was markedly lower in cigarette smokers than in nonsmokers. At 2 hours after the oral administration of 900 milligrams of phenacetin, the plasma concentration (+/- standard error) of unchanged drug was 2.24 +/- 0.73 micrograms per milliliter in the controls and 0.48 +/- 0.28 micrograms per milliliter in the smokers. The rate of excretion in urine of the major metabolite of phenacetin, N-acetyl-p-aminophenol, was the same in both groups. These results indicate for the first time decreased concentrations of a drug in plasma of persons who smoke cigarettes, and the results suggest that the decrease in the amount of Phenacetin in plasma may result from increased metabolism of phenacetin in cigarette smokers.     

血浆VLDL浓度双向选择对蛋鸡生产性能的影响

以雅发褐壳蛋鸡为供试材料 ,在零世代和一世代双向选择的基础上 ,应用血浆极低密度脂蛋白(VLDL)浓度对体腹脂性状继续进行双向选择 ,比较了高低脂系的生产性能 ,并研究了二世代母鸡中后期血浆VLDL浓度与上述性状的相关程度 ,进一步探讨了血浆VLDL浓度的双向选择效应。研究结果表明 ,二世代前期(19～ 4 3周 )产蛋量高脂系较高 (P <0 .0 5 ) ,在中后期 (44～ 6 2周 )低脂系产蛋量较高 (P <0 .0 5 ) ,全期 (19～ 6 2周 )产蛋量高、低脂系间差异不显著 (P >0 .0 5 ) ;二世代母鸡血浆VLDL与前期 (19～ 4 3周 )产蛋量呈显著的正表型相关 (P <0 .0 5 )和中等程度的正遗传相关 ,与中后期 (44～ 6 2周 )产蛋量呈显著的负表型相关 (P <0 .0 5 )和中等程度的负遗传相关 ,与全期产蛋量呈极低的正表型相关 (P >0 .0 5 )和正遗传相关。二世代母鸡蛋重低脂系较高 ,但两系间差异不显著 (P >0 .0 5 )。血浆VLDL浓度与蛋重呈较低的负表型相关和中等程度的负遗传相关 ,表明对血浆VLDL浓度的低向选择有可能使中后期蛋重提高。     

热应激对奶牛血液流变学指标及血清无机离子浓度和酶活性的影响

将40头健康娟荷奶牛和荷斯坦奶牛分为2组,分别于冬季12月份(牛舍日平均气温10.35℃,温湿度指数为47.24)和次年夏季7月份(牛舍日平均气温31.07℃,温湿度指数为82.61)测定热应激对奶牛血液流变学指标及血清无机离子浓度和酶活性的影响.结果表明:除血沉外,全血比黏度、血浆比黏度、红细胞压积,荷斯坦奶牛、娟荷奶牛夏季都明显升高,与冬季间差异均极显著(P<0.01),但在夏季或冬季2个品种间差异不显著(P>0.05);血清K+浓度,娟荷奶牛冬季与夏季间差异显著(P<0.05),荷斯坦奶牛冬季与夏季间以及2个品种间差异不显著(P>0.05);热应激极显著降低血清Na+、Ca2+浓度(P<0.01),但夏季或冬季2个品种间差异不显著(P>0.05);血清C l-浓度,2个品种间及2个季节间差异均不显著(P>0.05);热应激显著升高谷丙转氨酶、碱性磷酸酶活性(P<0.05),但夏季或冬季2个品种间差异不显著(P>0.05);谷草转氨酶活性,冬季2个品种间差异显著(P<0.05),夏季2个品种间差异不显著(P>0.05).可见,全血比黏度,血浆比黏度,红细胞压积,血清Na+、Ca2+浓度和谷丙转氨酶、碱性磷酸酶活性与奶牛品种无关,与热应激程度关系密切.     

Antigenic material: persistence in hypersensitive cells

Radioactivity derived from injections of tritiated tetanus toxin was observed in lymphocytes and macrophages for as long as 9 months after injection into immunized mice. These labeled cells became highly vacuolated and attracted eosinophils and lymphocytes when the animals were reinjected with specific antigen.     

Amphetamine in human plasma: a sensitive and specific enzymatic assay

A sensitive and specific enzymatic-isotopic method of determining plasma amphetamine concentrations in man is described. The assay is based on the transfer of the tritiated methyl group of S-adenosyl-L-[methyl-(3)H]methionine to amphetamine in the presence of a partially purified N-methyltransferase from rabbit lung. With this assay as little as 10 nanograms of amphetamine per milliliter of plasma can be accurately determined. The concentrations of d- and 1-amphetamine in the plasma after 20 to 30 milligrams of the drug had been ingested by human subjects are reported.     

Plasminogen: purification from human plasma by affinity chromatography

Plasminogen was prepared from human plasma by affinity chromatography on L-lysine-substituted Sepharose. Thirty milligrams of plasminogen, with a specific activity of 100 caseinolytic units (Committee on Thrombolytic Agents) per milligram of nitrogen, were obtained from 340 milliliters of plasma. This corresponds to over 200-fold purification from plasma. Disc-gel electrophoresis at pH 8.3 indicated seven distinct bands, all of which contained activity.     

Surface area of human erythrocyte lipids: reinvestigation of experiments on plasma membrane

Ratios of the lipid monolayer area to the erythrocyte surface area are 2:1 at low surface pressures and approach 1: 1 at collapse pressures. Un saturated phospholipids in cholesterol-phospholipid complexes of membrane ex tracts resemble their saturated derivatives at collapse pressures. Area ratio and phospholipid area data are related by an equation that tests hypothetical values for molecular areas used in membrane models.     

HPLC法测定小型猪血浆中阿替美唑含量的研究

为利用高效液相色谱法(HPLC)—荧光检测器法测定催醒过程中小型猪血浆中的阿替美唑浓度方法,试验以Symmetry C18(4.6 mm×250 mm,5μm)为固定相,乙腈与去离子水(0.05 mol·L-1磷酸盐缓冲液)30 70(V/V)为流动相,流速0.8 mL·min-1等色谱条件进行测定.结果表明,该法回收率理想,最低检测限为100 pg· mL-1,阿替美唑分离效果良好.说明此法专属性强,准确度高,方法可靠,满足催醒过程中小型猪血浆中阿替美唑含量的测定及临床药代动力学研究要求.     

Pineal gland: 24-hour rhythm in norepinephrine turnover

There is a 24-hour rhythm in the turnover of norepinephrine in sympathetic nerves innervating the pineal gland. This rhythm persists in blinded animals but is suppressed in normnal rats by light. The rhythm in norepinephrine turnover generates the rhythums in pineal indoleamines and N-acetyltransferase.     

小鼠血浆中黏杆菌素浓度UPLC/MS/MS检测方法的建立

试验将血浆样品经乙腈盐酸水溶液提取,离心后经C18萃取柱净化,在XevoTM TQ-S串联四极杆质谱仪多反映监测(MRM)下测定,黏杆菌素的保留时间为1.55 min.测得黏杆菌素在血浆中的检测限为0.05μg·mL-1.在0.1、1、5μg·mL-1添加水平下,黏杆菌素A和黏杆菌素B的加标回收率在94.4%~98.2%和91.6%~101%,相对标准偏差(RSD)均小于10%;黏杆菌素在0.1μg·mL-1到10μg·mL-1浓度范围内线性良好.     

Australia antigen: distribution during Cohn ethanol fractionation of human plasma

When plasma containing a hepatitis-associated antigen (Au/SH) is fractionated, the antigen is localized in fractions III and IV with none in fraction II and only small amounts in fractions I and V. The amount of antigen found in each of these fractions is probably not predictive of clinical infectivity of Cohn ethanol fractions from normnal pooled plasna.