THE EFFECT OF HIGH CONCENTRATIONS OF HISTIDINE ON THE LEVEL OF OTHER AMINO ACIDS IN PLASMA AND BRAIN OF THE MATURE RAT

—Changes in plasma and brain amino acids have been observed in adult rats 1 h after intraperitoneal injections of histidine and in others maintained on high histidine diets for 8 days. In the injection studies the compounds most consistently affected were the aromatic and branched chain amino acids and methionine. Reductions in their concentrations in the brain were explained by a competition with histidine for uptake into the tissue. There was little change in plasma amino acid levels. In the animals fed the highest concentration of histidine there was a generalized increase in brain, and a reduction in plasma, amino acid concentrations. A decrease in protein synthesis is postulated to explain this effect in brain.     

P物质在脊髓水平对心血管活动的影响

为阐明起源于延髓,下行达脊髓侧角的P物质(SP)纤维在心血管活动中的作用,我们在乌拉坦麻醉的大鼠上进行了以下实验:(1)在完整大鼠脊髓蛛网膜下腔注射(ith)SP(15nmol/10μl),观察到内脏交感神经放电、心率及平均动脉血压均有明显升高。(2)在颈_1(C_1)横断脊髓的大鼠,ith 相同剂量相同体积的SP 却引起内脏交感神经放电及平均动脉血压轻度下降,心率稍有增加。(3)C_1 横断脊髓的大鼠静脉注射相同剂量的SP 则引起平均动脉血压急速降低及内脏交感神经放电增加,提示SP 在脊髓水平的直接作用系通过抑制交感传出放电而引起血压降低。(4)用ith PS 的1/10剂量、1/5体积给完整大鼠脑池注射(ici),观察到血压及内脏交感神经放电增加,但心率没有变化。 上述结果表明,(1)SP 作用于脑和脊髓,对心血管功能可能有不同的作用。(2)ith SP对完整大鼠心血管功能的作用是多途径的。     

间断低氧对大鼠下丘脑超微结构及前增食欲素水平的影响

目的探讨睡眠中间断低氧对大鼠下丘脑前增食欲素及受体水平的影响以及下丘脑超微结构的变化。方法大鼠分成对照组、间断低氧组和持续低氧组,分别给予吸入空气,持续低氧和间断低氧气体,并在实验开始后1d、3d、1w和4w应用RT-PCR方法测定大鼠下丘脑前增食欲素及受体水平,分析其间的变化关系,电镜观察下丘脑的超微结构变化。结果与对照组和持续低氧组比较,间断低氧4w后大鼠下丘脑前增食欲素mRNA水平明显降低,受体水平升高,但在持续低氧和对照组之间无明显差异。在低氧后1d、3d、7d后大鼠下丘脑前增食欲素mRNA降低,受体水平升高,在4w后,持续低氧组则接近正常。急性持续低氧大鼠超微结构变化更严重,而慢性间断低氧变化更持久。结论慢性间断低氧可以引起下丘脑前增食欲素下降及受体水平升高,急性持续低氧也可引起上述变化,而慢性持续低氧未引起增食欲素改变;慢性间断低氧大鼠下丘脑超微结构表现为严重而持久的变化。     

THE EFFECT OF LOW LEVEL CONTINUOUS 2.45 GHz WAVES ON ENZYMES OF DEVELOPING RAT BRAIN

The present work describes the effect of low level continuous microwaves (2.45 GHz) on developing rat brain. Some 35-day-old Wistar rats were used for this study. The animals were exposed 2 hr/day for 35 days at a power density of 0.34 mW/cm² [specific absorption rate (SAR), 0.1 W/kg] in a specially made anechoic chamber. After the exposure, the rats were sacrificed and the brain tissue was dissected out and used for various biochemical assays. A significant increase in calcium ion efflux and ornithine decarboxylase (ODC) activity was observed in the exposed group as compared to the control. Correspondingly, a significant decrease in the calcium-dependent protein kinase activity was observed. These results indicate that this type of radiation affects the membrane bound enzymes, which are associated with cell proliferation and differentiation, thereby pointing out its possible role as a tumor promoter.     

THE EFFECT OF DIFFERENT DIETARY LEVELS OF ESSENTIAL FATTY ACIDS ON LIPIDS OF RAT CEREBRUM DURING MATURATION1

Abstract— Three dietary levels of essential fatty acids, 30, 0-75 and 007 calorie-%, with a linoleic: linolenic acid ratio of 4:1, were fed to rats for two generations. In the third generation the weight of the cerebrum and the concentration of its lipids and the fatty acid composition of phosphoglycerides were determined from term to 120 days of age. The cerebral weights and the concentrations of phospholipids, cholesterol and cerebrosides differed only slightly between the three dietary groups. The accretion of fatty acids of the linoleic acid series was independent of the dietary essential fatty acid level while the accretion of fatty acids of the linolenic acid series was markedly reduced in the groups with low essential fatty acid supply. The sum of the total polyunsaturated fatty acids in ethanolamine phosphoglycerides differed only slightly between the groups. The proportion of the major polyunsaturated fatty acid of the linoleic acid series was equal between the groups while that of 22:6 (n-3) was much lower in the groups fed 007 calorie % essential fatty acids. In these latter groups the relative concentrations of 22:5 (n-6), 20:3 (n-9) and 22:3 (n-9) were increased. The differences in the fatty acid composition were dependent on the age of the rats. They were largest in newborn rats and diminished with age after weaning.     

THE EFFECT OF ENUCLEATION ON THE DPN LEVEL OF AMEBA

1. Amebae contain DPN at levels of from 1 to 4 x 10^–13 moles per cell. 2. Following enucleation, nucleate and enucleate halves continue to have equal DPN contents over the six day period studied. Similarly, starving whole amebae maintain their DPN level over this period. 3. No reduced DPN could be detected in these aerobic animals. This remained true for whole amebae and for nucleate and enucleate halves over 5 days of starvation. 4. A method is described for the preparation and rapid separation of nucleate and enucleate ameba halves, based on a response of amebae to light.     

饲料中不同淀粉水平对中华绒螯蟹幼蟹生长、饲料利用的影响

实验配制7种等氮(粗蛋白35%)、等脂(粗脂肪6%)的不同淀粉水平(4%、10%、16%、22%、28%、34%、40%)的饲料,投喂中华绒螯蟹(Eriocheir sinensis)幼蟹[初始均重(6.2±0.1)g]8周,通过生长和生理指标评价中华绒螯蟹幼蟹对饲料碳水化合物的利用能力。为避免互相残杀,河蟹采用静水单个养殖,每种饲料40只河蟹。玉米淀粉作为实验饲料碳水化合物主要来源。实验结果表明:饲料中34%—40%淀粉组的摄食率显著低于4%—16%组(P0.05)。随饲料中淀粉含量提高幼蟹的体重和壳长特定生长率也相应提高,34%淀粉组体重特定生长率显著高于4%淀粉组(P0.05),22%淀粉组的壳长特定生长率显著高于4%淀粉组(P0.05);饲料中淀粉含量的增加显著提高了饲料效率,且在40%淀粉组最高。饲料高淀粉可提高蛋白储积率,蟹的肝体比在16%淀粉组最低,而蜕壳率和成活率在该组最高。蟹体干物质、粗蛋白、粗脂肪和灰分在高饲料淀粉组较高。幼蟹胰蛋白酶活力在16%淀粉组最高(P0.05);肝糖原含量随饲料淀粉水平升高呈线性(y=0.2268x+17.256,R2=0.9453,n=7,P0.05)上升。通过二次多项式回归可以得出河蟹获得最大特定生长率时饲料淀粉的含量为25.6%。     

PROPERTIES OF RAT BRAIN HISTIDINE DECARBOXYLASE

Abstract– The properties of histidine decarboxylase ( l -histidine carboxylyase EC 4.1,1.22) have been studied in a whole rat brain homogenate. Optimum pH depended upon substrate concentration; the variations of K _m and V _max were determined as a function of pH. pH values lower than 6.0 caused a loss of enzymic activity; activity was stable at pH values higher than 6.0. Enzyme activity was proportional to temperature in the range 30-45°C; temperature characteristic (μ) and Q₁₀ were determined and thermal inactivation was studied. Addition of pyridoxal 5'-phosphate increased enzyme activity. Dialysis of homogenates against phosphate buffer caused a partial loss of enzyme activity which could be restored by addition of the coenzyme to the incubation mixture. Enzyme activity was inhibited by α-methylhistidine and benzene and was unaffected by α-methyl DOPA. The properties correspond to those of a 'specific' histidine decarboxylase. However, the brain enzyme differs from the corresponding enzyme in peripheral tissues in the inability to achieve a total inhibition of activity by dialysis.     

THE EFFECT OF CORTISONE ON DNA CONTENT OF RAT HEPATOCYTES

Rats were treated with cortisone, x-radiation, and both agents in combination, and the effect noted on the DNA content of hepatocytes. Nuclei were enumerated both in whole liver homogenates and following isolation. The incorporation of P³² into DNA was also studied in relation to these agents. The following observations were made:— 1.The DNA content of nuclei fell both during cortisone administration and following x-radiation. In the former instance, the fall was progressive with continuing administration of hormone; in the latter instance, there was a return to normal 5 days after radiation. 2. Cortisone administration to x-radiated rats caused a fall in DNA/nucleus and prevented the return to normal at 5 days. 3. There was no evidence that the effects of cortisone and x-rays were additive in reducing DNA/nucleus. 4. These data indicate an alteration in DNA/nucleus, but simple changes in ploidy cannot be excluded. Either explanation requires that the agents used affect the DNA of non-regenerating nuclei. 5. Cortisone interfered with the incorporation of P³² into the DNA of regenerating liver. Only a small effect on DNA synthesis in resting liver was observed with cortisone or x-radiation. 6. DNA content of nuclei returned to normal 5 days after x-radiation and 3 days after discontinuance of cortisone. Slight increase in the incorporation of P³² by DNA was observed during recovery phases. 7. The hypothesis is proposed that the apparent losses and increases in DNA/nucleus were due to depolymerization and repolymerization of DNA. Following x-radiation and/or cortisone administration, it is proposed that some DNA is depolymerized and becomes cold acid-soluble and dissociated from organized chromatin. Later, conditions are such that this degraded DNA is repolymerized. 8. These data might be interpreted to indicate that a portion of the DNA is not essential to cell integrity; alternatively, there may be two or more species of DNA, one of which is more readily affected by the agents investigated in the present report.     

淋巴液的抗休克作用

目的和方法：应用显微电视录象设备和活体大鼠肠系膜微循环观察技术,观察胸导管淋巴液对重症失血性休克大鼠血压和微循环障碍的影响,以探讨淋巴液的抗休克作用及其机制。结果：淋巴液治疗组大鼠存活时间（７０３ｈ）显著高于白蛋白对照组（２０５ｈ）。治疗组输入胸导管淋巴液后血压显著回升,血液流态改善,有效地解除肠系膜细动、静脉和微淋巴管（ＭＬ）静态口径的病理性收缩,ＭＬ收缩分数、总收缩活性指数及淋巴管动力学指数恢复正常,而白蛋白对照组的微血管口径及三个ＭＬ收缩性指数仍处于休克时水平,且明显低于治疗组（Ｐ＜０．０１）。结论：淋巴液具有良好的抗休克作用,其机制可能与显著改善休克时的微循环障碍和提升血压有关