Purification and characterization of the carbonic anhydrase enzyme from Black Sea trout (Salmo trutta Labrax Coruhensis) kidney and inhibition effects of some metal ions on enzyme activity

In this study, the carbonic anhydrase (CA) enzyme was purified from Black Sea trout (Salmo trutta Labrax Coruhensis) kidney with a specific activity of 603.77 EU/mg and a yield of 35.5% using Sepharose-4B-l-tyrosine- sulphanilamide affinity column chromatography. For determining the enzyme purity and subunit molecular mass, sodiumdodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was performed and single band was observed. The molecular mass of subunit was found approximately 29.71 kDa. The optimum temperature, activation energy (E_a), activation enthalpy (ΔH) and Q₁₀ values were obtained from Arrhenius plot. K_m and V_max values for p-nitrophenyl acetate of the purified enzyme were calculated from Lineweaver-Burk graphs. In addition, the inhibitory effects of different heavy metal ions (Fe²⁺, Pb²⁺, Co²⁺, Ag⁺ and Cu²⁺) on Black Sea trout kidney tissue CA enzyme activities were investigated by using esterase method under in vitro conditions. The heavy metal concentrations inhibiting 50% of enzyme activity (IC₅₀) were obtained. Finally K_i values and inhibition types were calculated from Lineweaver-Burk graphs.     

A modality-specific somatosensory evoked potential test protocol for clinical evaluation: A feasibility study

ObjectiveWe aimed to establish an objective neurophysiological test protocol that can be used to assess the somatosensory nervous system.MethodsIn order to assess most fiber subtypes of the somatosensory nervous system, repetitive stimuli of seven different modalities (touch, vibration, pinprick, cold, contact heat, laser, and warmth) were synchronized with the electroencephalogram (EEG) and applied on the cheek and dorsum of the hand and dorsum of the foot in 21 healthy subjects and three polyneuropathy (PNP) patients. Latencies and amplitudes of the modalities were assessed and compared. Patients received quantitative sensory testing (QST) as reference.ResultsWe found reproducible evoked potentials recordings for touch, vibration, pinprick, contact-heat, and laser stimuli. The recording of warm-evoked potentials was challenging in young healthy subjects and not applicable in patients. Latencies were shortest within Aβ-fiber-mediated signals and longest within C-fibers. The test protocol detected function loss within the Aβ-fiber and Aδ-fiber-range in PNP patients. This function loss corresponded with QST findings.ConclusionIn this pilot study, we developed a neurophysiological test protocol that can specifically assess most of the somatosensory modalities. Despite technical challenges, initial patient data appear promising regarding a possible future clinical application.SignificanceEstablished and custom-made stimulators were combined to assess different fiber subtypes of the somatosensory nervous system using modality-specific evoked potentials.     

含有黄嘌呤衍生物的N-杂环卡宾金属配合物的生物活性研究进展

N-杂环卡宾(NHC)是一类多功能的配体,能够与过渡金属形成稳定的配位化合物,在催化、药学和材料科学等领域有着广泛的应用。黄嘌呤衍生物具有抗肿瘤转移和抗血管生成等生物活性,且结构易于修饰。将黄嘌呤衍生的NHC配体与过渡金属相结合有望得到具有全新生物活性的金属配合物。综述黄嘌呤衍生物的生物活性,以及黄嘌呤衍生的NHC金属配合物的结构特点和生物活性,并对黄嘌呤NHC金属配合物的研究进行了总结和展望,以期为进一步的研究提供参考。     

几种常用金属对大肠埃希菌杀灭作用观察

采用悬液定量浸泡杀菌试验和电镜技术,在实验室进行了常用金属对细菌的杀灭作用及其作用机理观察。结果,将不同金属置于含菌悬液内浸泡作用不同时间,金属铜对大肠埃希菌作用 30min,平均杀灭率为 97%;金属银和金作用 30min,平均杀灭率分别为 35. 6%和 30. 3%;不锈钢,金属铝、铁和锡等对细菌作用很弱。透射电镜观察发现,经金属铜作用 30min的大肠埃希菌,其细胞壁出现凹凸不平,局部细胞膜有分离现象,细胞质明显减少甚至消失,细胞核质浓缩呈块状。结论,常用金属中以金属铜、银对细菌作用明显,作用后的细胞结构有改变,其他常用金属对细菌作用不明显。     

Development of a Device for Removing a Partial Denture in a Patient with Scleroderma

Scleroderma is a chronic disease that has been associated with immune dysfunction. One of the oral manifestations is microsomia, a result of collagen deposition in the perioral tissues. The complexity of treating these patients includes limited mouth opening ability, and difficulty inserting and removing dentures due to finger deformity. This article will describe an appliance specially designed especially for scleroderma patients, which facilitates treatment of the patient with removable partial dentures (RPD).     

金属换热器传热过程的数学模型及应用

应用蒙特卡洛法仿真辐射式金属换热器内的辐射传热过程，建立了换热器综合传热的数学模型，利用概率论原理，把辐射能迁移过程仿真为一定累积概率分面下的随机过程，该模型能较好地反映换热器内传热过程的真实情况，可以计算出换热器内烟气、筒壁、空气的温度和壁面热流分布，以及研究烟气进口温度、换热器筒径和狭逢宽度对换热效果的影响。     

Covered metal stent for tumor obstruction of efferent loop recurrence after gastrectomy

Reports the case of a 60-year-old woman who underwent R2 total gastrectomy, and subsequent palliation of painful symptom recurrence via a membrane-covered metal stent. Received: 13 June 1996/Accepted: 31 July 1996     

Selective degeneration of CA1 pyramidal cells by chronic application of bismuth

The heavy metal bismuth induces a new type of selective neuronal degeneration that shares some common aspects with that seen following hypoxia and ischemia. Continuous application of 3 μm bismuth to organotypic cultures of rat hippocampus resulted after 2–3 weeks in selective degeneration of CA1 pyramidal cells, while CA3 pyramidal cells, dentate granule cells, and subicular neurons were resistant. With 10 μm MK-801, a noncompetitive NMDA-antagonist, during the entire culturing period failed to prevent neuronal degeneration induced by 3 μm bismuth. GABA-immunoreactive interneurons were also affected by bismuth, but were generally less sensitive than CA1 pyramidal cells. Acute application of up to 100 μm bismuth did not change the electrophysiological properties of CA1 pyramidal cells. © 1994 Wiley-Liss, Inc.     

Cobalt-dependent potentiation of net inward current density in Helix aspersa neurons.

A low concentration of transition metal ions Co2+ and Ni2+ increases the inward current density in neurons from the land snail Helix aspersa. The currents were measured using a single electrode voltage-clamp/internal perfusion method under conditions in which the external Na+ was replaced by Tris+, the predominant external current carrying cation was Ca2+, and the internal perfusate contained 120 mM Cs+/0 K+; 30 mM tetraethylammonium (TEA) was added externally to block K+ current. In the presence of Co2+ (3 mM) or Ni2+ (0.5 mM) inward Ca2+ currents were stimulated normally by voltage-dependent activation of Ca2+ channels. There was a 5-10% decrease in the rate of rise of the inward current. The principal effect of Co2+ and Ni2+ in increasing the current density seems to be a decrease in the rate at which the inward currents decline during a depolarizing voltage pulse. The results may be due to a decrease in a voltage-dependent or Ca(2+)-dependent outward current and/or an inhibition of Ca2+ channel inactivation. Outward current under these conditions (zero internal K+) was significant and most likely due to Cs+ efflux through the voltage-activated or Ca(2+)-activated nonspecific cation channels. Co2+ is an extremely effective blocker of this outward current. These results are not an artifact of internal perfusion or the special ionic conditions. Intracellular recording of unperfused neurons in normal Helix Ringer's solution showed that the Ca(2+)-dependent action potential duration was increased significantly by low concentrations of Co2+. This result is consistant with the Co(2+)-dependent increase in inward (depolarizing) current seen in voltage-clamp experiments.     

金属基底上聚合吡咯的电化学及电镜表征

用循环伏安法研究了吡咯在不同金属基底不同支持电解质中的聚合过程，对不同基底上制备的聚吡咯膜进行了电化学、扫描电镜、表面能谱等方面的研究，考察了聚吡咯膜电极对ＮＯ_３－离子的电位响应情况，结果表明，不同基底不同支持电解质在不同的吡咯浓度中表现出各异的伏安行为，经电化学处理的聚吡咯膜电极均对ＮＯ_３－呈Ｎｅｒｎｓｔ响应，扫描电镜观察表明除Ｐｔ基底外在其它基底上制备的聚吡咯膜均呈颗粒性球状堆集。