Altered protein synthesis in rat kidney cells exposed to semiconductor materials

It is thought that the extensive industrial use of arsenic, gallium and indium, which have applications as the materials for III–V semiconductors, will increase human exposure to these compounds in the near future. We have undertaken the development of new biological indicators for assessing exposure to these elements. Element-specific alterations in protein synthesis patterns were expected to occur following exposure to arsenic compounds. We examined alterations in protein synthesis in primary cultures of rat kidney proximal tubule epithelial cells by sodium arsenite, gallium chloride and indium chloride, utilizing two-dimensional gel electrophoresis. After incubation with the chemicals for 20 h, newly synthesized proteins were labeled with [³⁵S]methionine. A protein with a molecular weight (M_r) of 30 000 was markedly induced on exposure to 10 μM arsenite or 300 μM gallium chloride, and synthesis of proteins with M_r values of 85 000, 71 000, 65 000, 51 000, 38 000 and 28 000 were also increased by exposure to arsenite and gallium chloride. No significant changes were observed upon exposure to indium. Some of these increased proteins could be heat-shock proteins.     

Hydrodynamics of viscous fluid through porous slit with linear absorption

The exact solutions for the viscous fluid through a porous slit with linear ab-sorption are obtained. The Stokes equation with non-homogeneous boundary conditions is solved to get the expressions for the velocity components, pressure distribution, wall shear stress, fractional absorption, and leakage flux. The volume flow rate and mean flow rate are found to be useful in obtaining a convenient form of the longitudinal velocity component and pressure difference. The points of the maximum velocity components for a fixed axial distance are identified. The value of the linear absorption parameter is ran-domly chosen, and the rest available data of the rat kidney to the tabulate pressure drop and fractional absorption are incorporated. The effects of the linear absorption, uniform absorption, and flow rate parameters on the flow properties are discussed by graphs. It is found that forward flow occurs only if the volume flux per unit width is greater than the absorption velocity throughout the length of the slit, otherwise back flow may occur. The leakage flux increases with the increase in the linear absorption parameter. Streamlines are drawn to help the analysis of the flow behaviors during the absorption of the fluid flow through the renal tubule and purification of blood through an artificial kidney.     

Fabrication of Ni-decorated helical ribbon composite microstructure from self-assembled lipid tubule by electroless metallization

Molecular self-assembly is a powerful approach for preparing new supermolecular architectures such as nanofibers and nanotubes[1]. Lipid molecules, due to their amphiphilic nature, can self-assemble to form a variety of microstructures, such as spherical liposome, tubules and helical ribbons[2]. Many lipid molecules can self-organize into the helical ribbon structures[3,4], for example, helical ribbons were self-assembled in a variety of multicomponent enantiomerically pure sys- tems that cont…     

Effect of dentin tubules to the mechanical properties of dentin. Part II: Experimental study

To verify the theoretical models of varying transversely isotropic stress-strain relations of dentin established in the preceding work (Part I), we perform a set of experiments. Because of the very fine tooth size, it usually seems to be difficult to directly measure the inhomogeneous and anisotropic parameters of dentin. In this paper, by the digital speckle correlation method, tensile experiments are made on the small dentin samples either parallel or perpendicular to the dentin tubules. With the theoretically predicted elastic stress-strain relations, an optimization method is proposed to fit the strain curve adapted to the experimental data. The results show that the theoretical elastic stress-strain relations coincides very well with the experimental observations. The determined Young's modulus and Poisson's ratio of dentin matrix are 29.5 GPa and 0.44, respectively, in the optimization sense. The project supported by the National Natural Science Foundation of China (19525207)     

Assay of Sodium and Potassium Activated Adenosine Triphosphatase in Submicrogram Fragments of Renal Tubules

Abstract

An improved method for measuring Na, K-ATPase in submicrogram fragments of single renal tubules approximately one millimeter long is described. The activity is determined by coupling ATP hydrolysis stoichiometrically to pyruvate kinase and the oxidation of NADH by lactic dehydrogenase. NADH oxidation is followed fluorimetrically using an instrument specially modified for increased sensitivity and stability.     

Mapping the fly Malpighian tubule lipidome by imaging mass spectrometry

Matrix‐assisted laser/desorption ionization imaging mass spectrometry (MALDI IMS) is an analytical technique for understanding the spatial distribution of biomolecules across a sample surface. Originally employed for mammalian tissues, this technology has been adapted to study specimens as diverse as microbes and cell cultures, food such as strawberries, and invertebrates including the vinegar fly Drosophila melanogaster. As an ideal model organism, Drosophila has brought greater understanding about conserved biological processes, organism development, and diseased states and even informed management practices of agriculturally and environmentally important species. Drosophila displays anatomically separated renal (Malpighian) tubules that are the physiological equivalent to the vertebrate nephron. Insect Malpighian tubules are also responsible for pesticide detoxification. In this article, we first describe an effective workflow and sample preparation method to study the phospholipid distribution of the Malpighian tubules that initially involves the manual microdissection of the tubules in saline buffer followed by a series of washes to remove excess salt and enhances the phospholipid signals prior to matrix deposition and IMS at 25‐μm spatial resolution. We also established a complementary methodology for lipid IMS analysis of whole‐body fly sections using a dual‐polarity data acquisition approach at the same spatial resolution after matrix deposition by sublimation. Both procedures yield rich signal profiles from the major phospholipid classes. The reproducibility and high‐quality results offered by these methodologies enable cohort studies of Drosophila through MALDI IMS.     

气体粘滞系数的测定

本文对球形液膜内气体沿细管排出过程中，球形液膜的动态特性作了理论模拟推导，并用该实验装置对常温下空气的粘滞系数进行了测定。     

Synchrotron‐radiation‐based X‐ray micro‐computed tomography reveals dental bur debris under dental composite restorations

Dental burs are used extensively in dentistry to mechanically prepare tooth structures for restorations (fillings), yet little has been reported on the bur debris left behind in the teeth, and whether it poses potential health risks to patients. Here it is aimed to image dental bur debris under dental fillings, and allude to the potential health hazards that can be caused by this debris when left in direct contact with the biological surroundings, specifically when the debris is made of a non‐biocompatible material. Non‐destructive micro‐computed tomography using the BioMedical Imaging & Therapy facility 05ID‐2 beamline at the Canadian Light Source was pursued at 50 keV and at a pixel size of 4 µm to image dental bur fragments under a composite resin dental filling. The bur's cutting edges that produced the fragment were also chemically analyzed. The technique revealed dental bur fragments of different sizes in different locations on the floor of the prepared surface of the teeth and under the filling, which places them in direct contact with the dentinal tubules and the dentinal fluid circulating within them. Dispersive X‐ray spectroscopy elemental analysis of the dental bur edges revealed that the fragments are made of tungsten carbide–cobalt, which is bio‐incompatible.     

Structure and vibrational properties of carbon tubules

The structure of multilayered carbon tubules has been investigated by electron microscopy and X-ray diffraction. The structure of tubules is characterized by disorder in the stacking of cylindrical graphene sheets. Raman scattering measurements have been carried out in tubules and compared with graphite. The observed features in the Raman spectra in tubules can be understood in terms of the influence of disorder. The additional Raman modes predicted for single layer carbon tubules have not been observed.     

MFI沸石前驱体和硅酸钠共组装制备水热稳定的管状介孔分子筛

在CTAB模板剂的作用下 ,硅酸钠、铝酸钠和含有MFI纳米簇的沸石前躯体溶液通过S+ I-路线共组装得到了高水热稳定的管状形貌介孔分子筛 .XRD结果显示样品具有类似MCM 41的规则排列六方孔道结构 .在沸水中处理 15 0h后 ,介孔特征仍然保留 ,显示出很好的水热稳定性 .综合SEM和TEM的观察结果 ,此介孔分子筛具有中空的管状形貌 ,平均管长2 .0 μm ,平均直径为 0 .3 0 μm .含有MFI纳米簇的沸石前躯体作为硅源的一部分加入体系中 ,MFI纳米簇伴随来自于硅酸钠的可溶性硅物种共同进入分子筛骨架 ,在提高水热稳定性的同时 ,没有降低六方纳米孔道的规整度 ,也没有对分子筛形貌调变带来不利影响 .MFI纳米簇中 ,硅氧四面体和铝氧四面体的紧密联结方式在进入分子筛骨架时得以保留是水热稳定性提高的主要原因 .作为硅源的另一部分加入的硅酸钠 ,使合成体系pH值足够高 (pH >13 ) ,加入H2 SO4调节体系pH值到10 ,管状形貌的介孔分子筛在逐步中和过程中形成 .通过这种特殊的共组装方法合成介孔分子筛 ,在获得中空的管状形貌的同时显著提高水热稳定性 ,为这种管状形貌介孔分子筛的应用奠定了基础 .