SYNTHESIS AND BIOLOGICAL ACTIVITIES OF CYCLIC ADP-CARBOCYCLIC-RIBOSE AND ITS ANALOGS

An efficient synthesis of cyclic ADP-carbocyclic-ribose (2), as a stable mimic for cyclic ADP-ribose, was achieved. Treatment of N ¹-carbocyclic-ribosyla-denosine bisphosphate derivative 10 with AgNO₃ in the presence of molecular sieves 3A in pyridine gave the desired cyclic product in 93% yield, which was deprotected to give the target cyclic ADP-carbocyclic-ribose (2).     

THE AUTODESTRUCTION OF PEPSIN IN RELATION TO ITS IONIZATION

1. Evidence is presented that pepsin is a univalent acid with a value for pK of 6.85 (or a base, with pK 7.39). 2. The autodestruction of the pepsin is shown to be dependent in part upon an instantaneous irreversible change occurring in the ionized form of the enzyme (if it be an acid) or in the unionized form (if it be a base). 3. A further progressive autodestruction of pepsin at any given hydrogen ion concentration and temperature is defined by the mass law equation for a monomolecular reaction 4. The velocity of autodestruction of pepsin is directly proportional to the hydroxyl ion concentration. It is much less in the range of hydroxyl ion concentration from pOH 9.89-7.7, than in the range greater than pOH 7.7. In both of these ranges variations in pK with pOH may be represented by straight lines.     

REGULATION OF THE HYDROGEN ION CONCENTRATION AND ITS RELATION TO METABOLISM AND RESPIRATION IN THE STARFISH

The normal reaction of the cœlomic fluid in Patiria miniata and Asterias ochraceus is pH 7.6, and of the cæca, 6.7, compared with sea water at 8.3, all without salt error correction. A medium at pH 6.7–7.0 is optimum for the cæca for ciliary survival and digestion of protein, and is maintained by carbon dioxide production. The optimum pH found for carbon dioxide production is a true one for the effect of hydrogen ion concentration on the tissue. It does not represent an elimination gradient for carbon dioxide. Because the normal excised cæca maintain a definite hydrogen ion concentration and change their internal environment toward that as an optimum during life, there exists a regulatory process which is an important vital function.     

加压素对记忆的影响及其与海马中去甲肾上腺素和多巴胺的关系

采用海马内注射方法,探讨了精氨酸加压素对大鼠穿梭箱条件回避行为的影响及其与海马中去甲肾上腺素能末梢递质的关系;用高效液相色谱-电化学检测法研究了精氨酸加压素对海马中单胺类递质及其代谢产物含量的影响。结果显示:(1)两侧海马内注射精氨酸加压素(各50pg),可延缓动物条件回避行为的消退;(2)用6-羟多巴胺(各10μg)损毁两侧海马中的去甲肾上腺素能末梢,可阻断精氨酸加压素的促记忆效应;(3)精氨酸加压素可加速海马中去甲肾上腺素和多巴胺的消失。上述结果提示,加压素对记忆的易化作用,至少部分通过海马起作用;海马内的去甲肾上腺素能末梢可能参与加压素对记忆过程的调节;加压素的作用很可能是通过加强脑内去甲肾上腺素的降解代谢来实现的。     

糖皮质激素的抗痫作用及其与γ-氨基丁酸的关系

为了探讨糖皮质激素的抗癫痫效应和作用机制, 本研究观察了糖皮质激素对戊四氮诱导的慢性点燃型癫痫大鼠的行为和脑电图的影响, 并应用免疫细胞化学双重染色技术探查了大脑皮质神经元内糖皮质激素受体（ＧＲ） 与γ－ 氨基丁酸（ＧＡＢＡ） 的共存情况。结果显示, 在慢性点燃型癫痫大鼠, 在点燃后的第３ 天或第１５ 天, 先经静脉给予地塞米松（４ｍ ｇ／ｋｇ）, 再经腹腔注射戊四氮（３０ｍ ｇ／ｋｇ） 可明显减弱或完全抑制癫痫发作。免疫细胞化学双重染色证明, ＧＲ和ＧＡＢＡ共存于大脑皮质部分神经元。以上结果提示, 糖皮质激素具有抗慢性癫痫的效应, 其作用机制可能与ＧＲ调节同一神经元内ＧＡＢＡ的合成有关。