Hepatic microsomal NADPH-cytochrome P-450 reductase from little skate, Raja erinacea. Comparison of thermolability and other molecular properties with a mammalian enzyme

Components of little skate (an elasmobranch) and rabbit hepatic microsomal cytochrome P-450 dependent monooxygenase systems were examined for differences which might explain the decreasing xenobiotic-metabolizing activity of little skate microsomes assayed at temperatures above 30 degrees C. The proportion of saturated fatty acids in microsomal lipids and the habitat temperature are both lower in skate as compared to rabbit, which is consistent with the known adaptive pattern. The more thermolabile enzyme of the skate system in microsomal preparations is NADPH-cytochrome P-450 reductase. The optimal assay temperature for purified skate reductase (30 degrees C) is 10 degrees C lower than that for the purified rabbit reductase. The purified skate reductase differs from rabbit reductase in monomeric molecular weight, in peptides produced by partial proteolysis, in immunochemical properties, but not in flavin content.     

Synthesis and cytotoxic activity of metallic complexes of lawsone

In the present study, a series of metallic complexes of the 1,4-naphthoquinone lawsone (2–6) were synthesized and evaluated for potential cytotoxicity in a mouse leukemic macrophagic RAW 264.7 cell line. Cell viability was determined by the MTT assay. Significant growth inhibition was observed for the copper complex (4) with an IC₅₀ value of 2.5 μM. This compound was selected for further evaluation of cytotoxic activity on several human cancer cells including HT-29 (human colorectal adenocarcinoma), HepG2 (human hepatocellular carcinoma) and HeLa, (human cervical adenocarcinoma cells). Significant cell viability decrease was also observed in HepG2 cells. The apoptotic potential of this complex was evaluated in these cells. Compound 4 induced apoptosis by a mechanism that involves the activation of caspases 3, 8 and 9 and modulation of apoptotic-related proteins such as Bax, Bad, and p53. These results indicate that metal complexes of lawsone derivatives, in particular compound 4, might be used for the design of new antitumoral agents.     

Metallothioneins and trace elements in digestive gland,gills, kidney and gonads of Octopus vulgaris

Metallothionein-like proteins (MT) and V, Cr, Co, Ni, Zn, Cu, As and Cd were determined in digestive gland, gills, kidney and gonads of Octopus vulgaris, from the Portuguese coast. To our knowledge these are the first data on MT in octopus. High concentrations (µg g^− 1, dry mass) of Zn (48050) and Cd (555) were found in digestive gland, and MT reached levels one order of magnitude above the ones registered in wild bivalves. Significantly higher levels of MT in digestive gland and gills of specimens from A and B were in line with elevated Cd concentrations. Principal component analyses (PCA) point to MT-Cd and MT-Cr associations in digestive gland and gills. Despite the high levels of Zn in specimens from B, association with Zn was not obtained. Due to the affinity of MT to various elements, it should not be excluded the possibility of Cd replacing Zn in Zn-MT. Kidney presented higher levels of Cd, Co, Ni and As than gills and gonads, and in the case of As surpassing the levels in digestive gland, but PCA showed no relation with MT. Likewise the MT levels in gonads had no correspondence to the metal concentration variation.     

Anticancer Metal Complexes: Synthesis and Cytotoxicity Evaluation by the MTT Assay

Titanium (IV) and vanadium (V) complexes are highly potent anticancer agents. A challenge in their synthesis refers to their hydrolytic instability; therefore their preparation should be conducted under an inert atmosphere. Evaluation of the anticancer activity of these complexes can be achieved by the MTT assay.The MTT assay is a colorimetric viability assay based on enzymatic reduction of the MTT molecule to formazan when it is exposed to viable cells. The outcome of the reduction is a color change of the MTT molecule. Absorbance measurements relative to a control determine the percentage of remaining viable cancer cells following their treatment with varying concentrations of a tested compound, which is translated to the compound anticancer activity and its IC₅₀ values. The MTT assay is widely common in cytotoxicity studies due to its accuracy, rapidity, and relative simplicity.Herein we present a detailed protocol for the synthesis of air sensitive metal based drugs and cell viability measurements, including preparation of the cell plates, incubation of the compounds with the cells, viability measurements using the MTT assay, and determination of IC₅₀ values.     

Autotrophic denitrification using hydrogen generated from metallic iron corrosion

Hydrogenotrophic denitrification was demonstrated using hydrogen generated from anoxic corrosion of metallic iron. For this purpose, a mixture of hydrogenated water and nitrate solution was used as reactor feed. A semi-batch reactor with nitrate loading of 2000 mg m⁻³ d⁻¹ and hydraulic retention time (HRT) of 50 days produced effluent with nitrate concentration of 0.27 mg N L⁻¹ (99% nitrate removal). A continuous flow reactor with nitrate loading of 28.9 mg m⁻³ d⁻¹ and HRT of 15.6 days produced effluent with nitrate concentration of ∼0.025 mg N L⁻¹ (95% nitrate removal). In both cases, the concentration of nitrate degradation by-products, viz., ammonia and nitrite, were below detection limits. The rate of denitrification in the reactors was controlled by hydrogen availability, and hence to operate such reactors at higher nitrate loading rates and/or lower HRT than reported in the present study, hydrogen concentration in the hydrogenated water must be significantly increased.     

Implantation of cranial base metallic markers in nonhuman primates.

Cranial base metallic markers are useful in growth and developmental research on the nonhuman primate model. Metallic implants aid in superimposing serial cephalometric roentgenograms in the study of craniofacial changes. They also enable measurement of linear and angular changes in the cranial base. The design of a special implant gun is described in detail. A suggested technique for placement of tantalum markers in the cranial base of nonhuman primates is discussed.     

膜上相互作用对平板双分子层脂膜电性质的影响

以平板双分子层脂膜作为生物膜的简单模型,建立用平板双分子层脂膜电性质研究药物－生物膜相互作用的方法。研究以具有典型特征的物质－表面活性剂、自由基、金属手性配合物与平板膜的相互作用引起膜电性质的规律性改变;重组人Ｂ型血红细胞膜与溶液中抗Ｂ单克隆抗体发生特异相互作用时,膜电阻快速下降,下降的速率与加入的抗体量成正相关。在研究发生在平板膜上的典型反应的基础上,通过对膜电性质的监测和分析,从而确认平板双分     

Root fungal endophytes: identity,phylogeny and roles in plant tolerance to metal stress

Metal trace elements accumulate in soils mainly because of anthropic activities, leading living organisms to develop strategies to handle metal toxicity. Plants often associate with root endophytic fungi, including nonmycorrhizal fungi, and some of these organisms are associated with metal tolerance. The lack of synthetic analyses of plant-endophyte-metal tripartite systems and the scant consideration for taxonomy led to this review aiming (1) to inventory non-mycorrhizal root fungal endophytes described with respect to their taxonomic diversity and (2) to determine the mutualistic roles of these plant-fungus associations under metal stress. More than 1500 species in 100 orders (mainly Hypocreales and Pleosporales) were reported from a wide variety of environments and hosts. Most reported endophytes had a positive effect on their host under metal stress, but with various effects on metal uptake or translocation and no clear taxonomic consistency. Future research considering the functional patterns and dynamics of these associations is thus encouraged.     

Multi-Scale Modification of Metallic Implants With Pore Gradients,Polyelectrolytes and Their Indirect Monitoring In vivo

Metallic implants, especially titanium implants, are widely used in clinical applications. Tissue in-growth and integration to these implants in the tissues are important parameters for successful clinical outcomes. In order to improve tissue integration, porous metallic implants have being developed. Open porosity of metallic foams is very advantageous, since the pore areas can be functionalized without compromising the mechanical properties of the whole structure. Here we describe such modifications using porous titanium implants based on titanium microbeads. By using inherent physical properties such as hydrophobicity of titanium, it is possible to obtain hydrophobic pore gradients within microbead based metallic implants and at the same time to have a basement membrane mimic based on hydrophilic, natural polymers. 3D pore gradients are formed by synthetic polymers such as Poly-L-lactic acid (PLLA) by freeze-extraction method. 2D nanofibrillar surfaces are formed by using collagen/alginate followed by a crosslinking step with a natural crosslinker (genipin). This nanofibrillar film was built up by layer by layer (LbL) deposition method of the two oppositely charged molecules, collagen and alginate. Finally, an implant where different areas can accommodate different cell types, as this is necessary for many multicellular tissues, can be obtained. By, this way cellular movement in different directions by different cell types can be controlled. Such a system is described for the specific case of trachea regeneration, but it can be modified for other target organs. Analysis of cell migration and the possible methods for creating different pore gradients are elaborated. The next step in the analysis of such implants is their characterization after implantation. However, histological analysis of metallic implants is a long and cumbersome process, thus for monitoring host reaction to metallic implants in vivo an alternative method based on monitoring CGA and different blood proteins is also described. These methods can be used for developing in vitro custom-made migration and colonization tests and also be used for analysis of functionalized metallic implants in vivo without histology.     

西南岩溶地区黄荆叶片碳酸酐酶的稳定性

研究表明西南岩溶地区几种植物叶片中含有明显活性的碳酸酐酶(carbonic anhydrase,CA),从黄荆(Vitex negundo)叶片提取碳酸酐酶,该酶具有良好的热稳定性.阴离子及岩溶环境主要金属离子对碳酸酐酶活性有一定的影响,Ca2 、Mg2 低于10 mmol·L-1,Mn2 、Zn2 低于0.01 mmol·L-1,Co2 、Cu2 低于0.001 mmol·L-1,NO3-、C1-、Br-、I-、NO2-低于0.01 mmol·L-1时,酶活性较稳定.0.001～0.01 mmol·L-1的Ca2 、Mg2 对该酶有激活作用.研究结果表明,该酶比较适应岩溶土壤水体的离子环境从而保持酶活性的相对稳定.