Generation of H2O2 in Brain Mitochondria

Generation of H2O2 by rat brain mitochondria using succinate and glycerol-1-phosphate as substrates has been demonstrated. Earlier workers were unable to detect this activity in sucrose-Tris buffer. We found that this was due to a lag in the expression of activity in sucrose medium. Using phosphate buffer (50 mM), good rates are now obtained. Generation of H2O2 by rat brain mitochondria required the presence of antimycin A and was dependent on the substrates succinate and glycerol-1-phosphate. Low rates were obtained with NAD+-linked substrates and none with choline, glutamate, and NADH. The Km and Vmax values for H2O2 generation were considerably lower than the corresponding values for the respective dehydrogenase activity, measured by dye reduction. Oxygen-radical scavengers inhibited H2O2 generation, suggesting oxygen radical involvement. Depletion of ubiquinone from mitochondria resulted in loss of H2O2 generation. Reconstitution of such depleted particles with ubiquinone restored the capacity to generate H2O2 in a concentration-dependent manner. Levels of H2O2 production were found to be maximal in cerebellum. Brain mitochondria from rabbit, hamster, mouse, and guinea pig also have the capacity to generate H2O2 on oxidation of glycerol-1-phosphate.     

Manganese deficiency impairs ribonucleotide reduction but not DNA replication in Arthrobacter species

Manganese deficiency induced unbalanced growth, filamentous morphology and a decrease of viability in Arthrobacter citreus ATCC 11624, A. globiformis ATCC 8010 and A. oxydans DSM 420. Under these conditions whole cells showed an inhibition of DNA formation but not of RNA synthesis. However, DNA replication still functioned when manganese-deficient cells were made permeable to and supplied with all four deoxyribonucleotides. The inhibition of DNA formation in-vivo could be traced back to impairment of DNA precursor biosynthesis as ribonucleotide reductase activity was distinctly reduced upon starvation of manganese. Both DNA formation in-vivo and ribonucleotide reductase activity were restored in the starved cultures by addition of Mn²⁺ but not of other divalent cations. In these manganese-reactivated cultures both processes were stimulated above the levels of the manganese-sufficient controls. Rifampicin or chloramphenicol (both 100 g/ml) could not suppress the rapid manganese-reactivation of cultures starved of this cation. This suggests the presence of an inactive metal-deficient ribonucleotide reductase apoenzyme in manganese-deficient cells. The presence of a manganese-dependent ribonucleotide reduction in the genus Arthrobacter besides of Brevibacterium ammoniagenes and Micrococcus luteus indicates a broad distribution of this new type of metal catalysis for DNA precursor biosynthesis in the high GC% branch of the Gram-positive bacteria.Abbreviations HU hydroxyurea - TCA trichloroacetic acid     

树鼩应激镇痛的研究

用辐射热和电刺激两种方法测定了应激状态下树鼩(Tupaia belangeri chinensis)的痛反应值。结果表明,在应激状态下,树鼩的痛反应值在1—7分钟内下降了100—200％。上述结果提示,树鼩的痛反应降低与应激镇痛有关。     

Dynamics of herbaceous vegetation recovery on Mount St. Helens,Washington, USA,after a volcanic eruption

Recovery of herbaceous vegetation on Mount St. Helens was studied annually after the massive lateral eruption of May 18, 1980. Measures such as species richness, cover, and diversity were combined with detrended correspondence analysis to describe vegetation recovery rates under different combinations of initial impact intensity and degree of isolation from recolonization sources. A major key to recovery is whether any plants survived the devastation. Survival of even a few individuals markedly accelerated recovery. Where no plants survived, the degree of isolation becomes paramount. New, barren substrates, a few meters from undisturbed sites, have begun to develop some vegetation, while more isolated sites have scarcely any subalpine plants present. On any site, plant-mediated processes that improve conditions for growth and the invasion of other species predominate in the early stages, but as vegetation develops, biotic inhibition and establishment of seedlings from adults already in the habitat gain importance. The rate at which this conversion occurs is a function of the size and intensity of the initial impact.Abbreviations DCA Detrended correspondence analysis     

LH-RH antagonist inhibits gonadal steroid secretion in vitro

This investigation was aimed at studying the direct action of LH-RH derivatives on gonadal function. Modulation by LH-RH antagonist (Ac-[D-beta-Nal1, D-p-Cl-Phe2, D-Trp3, D-Arg6, D-Ala10]-LH-RH) and agonist of LH-RH (D-Ser(TBU)6, AzaGly10-LH-RH) and native LH-RH of HCG-stimulated steroidogenesis in testicular Leydig cells and luteal cells was studied in vitro. The LH-RH antagonist (3.2 X 10(-8) M) was found to change ED50 of HCG from 2 X 10(-11) M to 5.5 X 10(-11) M in the Leydig cell culture system. In addition, the antagonist was noted to override the stimulatory action of native LH-RH in Leydig cells. Furthermore, the agonist was found to augment HCG-provoked testosterone secretion. Similarly, the LH-RH antagonist at 10(-9) M blunted HCG-stimulated progesterone secretion in the luteal cell culture system and increased the ED50 of HCG from 8.7 X 10(-13) to 7.7 X 10(-12) M. In contrast to the Leydig cell culture system native LH-RH (10(-8) M) and the agonist (10(-8) M) increased the ED50 of HCG in luteal cells from 8.7 X 10(-13) M to 3 X 10(-12) M and 2.3 X 10(-12) M, respectively. Present data combine to suggest that LH-RH antagonists act at least partially at the gonadal level and may be clinically useful to inhibit Leydig cell and ovarian function.     

经皮椎间孔镜联合超前镇痛的术后疼痛的疗效分析

目的:探讨经皮椎间孔镜联合盘内注射胶原酶对于椎间盘突出症术后疼痛的疗效。方法:选取我科收治的经皮椎间孔镜手术患者110例,将其随机分为观察组以及对照组,每组55例,观察组采取椎间孔镜联合盘内注射胶原酶联合超前镇痛治疗,对照组给予相同的手术方式联合术后口服药物治疗,连续治疗1个疗程后,比较两组患者术后4、12、24、48、72 h的疼痛评分,观察两组术后曲马多的用量,比较两组患者术后出现恶心、呕吐、嗜睡、便秘、皮肤瘙痒等并发症的发生情况,比较两组术前以及术后7、14d的JOA评分情况。结果:术后4、12、24、48、72 h观察组的疼痛评分均明显低于对照组,观察两组术后曲马多的用量明显少于对照组,观察组术后并发症的发生率为7.27%(4/55),对照组为30.91%(17/55),组间比较有明显差异(x2=13.624,P0.05),术后7 d观察组JOA评分明显优于对照组,P0.05,术后14 d组间比较无明显差异,P0.05。结论:塞来昔布超前镇痛措施应用于经皮椎间孔镜联合盘内注射胶原酶治疗腰椎间盘突出症术后患者能够有效缓解术后疼痛,并减少术后阿片类药物的使用,改善术后功能,值得临床推广应用。     

Functionalized imidazolium and benzimidazolium salts as paraoxonase 1 inhibitors: Synthesis,characterization and molecular docking studies

Paraoxonase (PON) is a key enzyme in metabolism of living organisms and decreased activity of PON1 was acknowledged as a risk for atherosclerosis and organophosphate toxicity. The present study describes the synthesis, characterization, PON1 inhibitory properties and molecular docking studies of functionalized imidazolium and benzimidazolium salts (1a–5g). The structures of all compounds were elucidated by IR, NMR, elemental analysis and structures of compounds 2b and 2c were characterized by single-crystal X-ray diffraction. Compound 1c, a coumarin substituted imidazolium salt showed the best inhibitory effect on the activity of PON1 with good IC₅₀ value (6.37 μM). Kinetic investigation was evaluated for this compound and results showed that this compound is competitive inhibitor of PON1 with K_i value of 2.39 μM. Molecular docking studies were also performed for most active compound 1c and one of least active compound 2c in order to determine the probable binding model into active site of PON1 and validation of the experimental results.     

Discovery and optimization of 1,7-disubstituted-2,2-dimethyl-2,3-dihydroquinazolin-4(1H)-ones as potent and selective PKCθ inhibitors

A high-throughput screening campaign helped us to identify an initial lead compound (1) as a protein kinase C-θ (PKCθ) inhibitor. Using the docking model of compound 1 bound to PKCθ as a model, structure-based drug design was employed and two regions were identified that could be explored for further optimization, i.e., (a) a hydrophilic region around Thr442, unique to PKC family, in the inner part of the hinge region, and (b) a lipophilic region at the forefront of the ethyl moiety. Optimization of the hinge binder led us to find 1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-one as a potent and selective hinge binder, which resulted in the discovery of compound 5. Filling the lipophilic region with a suitable lipophilic substituent boosted PKCθ inhibitory activity and led to the identification of compound 10. The co-crystal structure of compound 10 bound to PKCθ confirmed that both the hydrophilic and lipophilic regions were fully utilized. Further optimization of compound 10 led us to compound 14, which demonstrated an improved pharmacokinetic profile and inhibition of IL-2 production in a mouse.     

Microdialysis of excitatory amino acids in the periaqueductal gray of the rat after unilateral peripheral inflammation

Summary This study measured the release of glutamate (Glu) and aspartate (Asp) amino acid transmitters in the ventrocaudal compartment of the rat periaqueductal gray (PAG) following exposure to unilateral peripheral inflammation. The release of endogenous Glu and Asp from the rat ventrocaudal PAG was monitored with the microdialysis technique in unanesthetized, unrestrained rats. There was significant increase (1,300%) in the basal concentrations of Glu release in the 7 days Complete Freund's Adjuvant (CFA) treated group compared to 24h mineral oil control group. Amino acid release was induced by infusing veratridine (75M, a sodium channel activator) directly through the 1 mm long dialysis probe. Perfusion of veratridine into the ventrocaudal PAG resulted in significant elevation of Glu and Asp amino acids. In the 24h and 7 days CFA treated rats, veratridine-evoked release of Glu was significantly decreased in the lateral ventrocaudal PAG compared to control rats injected with mineral oil (CFA vehicle). The peak minus baseline concentrations of Glu in 24h and 7 days CFA treated groups decreased 55.7% and 43.9%, respectively. In contrast, The basal and the peak minus baseline concentrations of Asp showed no significant change between control group and 24h and 7 days CFA treated animals. The results provide direct evidence that Glu excitatory amino acid may be involved in nociception/nociception modulation pathway in the ventrocaudal PAG.     

三丁基锡对人红细胞膜Na~＋，K~＋－ATPase活性的抑制作用

三丁基锡（ＴＢＴ）是人红细胞膜上Ｎａ~＋,Ｋ~＋－ＡＴＰａｓｅ的一种抑制剂．该化合物对Ｎａ~＋,Ｋ~＋－ＡＴＰａｓｅ有很强的抑制能力．在正常的反应体系中,ＴＢＴ浓度仅为１０μｍｏｌ／Ｌ时,该酶的活性全部丧失;其抑制Ｎａ~＋,Ｋ~＋－ＡＴＰａｓｅ的ＩＣ＿（５０）值为２．２μｍｏｌ／Ｌ．Ｋ~＋能增强ＴＢＴ的这种抑制作用,ＴＢＴ为Ｋ~＋的反竞争性抑制剂．