DESIGN AND DEVELOPMENT OF NANO-ARTIFICIAL-CELL MEMBRANE BASED NOVEL BIOSENSOR : APPLICATION FOR MONITORING OF AQUEOUS STRESSES

Joint Research on Environmental Science and Technology for the Eart

Crystal-Induced Inflammation: Studies of the Mechanism of Crystal-Membrane Interactions

Studies of the interactions of monosodium urate monohydrate (MSUM) crystals and calcium Pyrophosphate dihydrate triclinic (CPPD) crystals with biomembranes have been reviewed. Crystalmembrane binding and crystal-induced membranolysis have been studied using human erythrocytes as a model membrane system. The extent of MSUM-membrane binding was determined by incorporating a hydrophobic, fluorescent probe into the membranes, centrifugation to separate free membranes from membranes with bound crystals and quantitation of free membranes by measuring the total fluorescence intensity. The ability of MSUM and CPPD to hemolyse red cells was used as a measure of the membranolytic potential of the crystals. Fluorescence polarization studies showed that MSUM-membrane binding resulted in fluidization of the membrane. Cross-linking of the membrane proteins of the erythrocyte or the presence of divalent cations in the incubation medium inhibited MSUM induced hemolysis. These findings were explained by hypothesizing a pore model mechanism for MSUM induced membranolysis as follows. Binding of crystals to membranes induces the redistribution of transmembrane proteins into clusters or aggregates leading to pore formation. The pores permit the leakage of low molecular weight soluble compounds and ions across the membrane which is followed by osmotic rupture of the membran

Scanning and Transmission Electron Microscopic Studies on the Oviducts of Pekin Ducks Fed Methyl Mercury Containing Diets

This study was undertaken to examine the effects of varying levels of methyl mercury (MeHg) on the ultrastructure of the surface epithelium of the oviduct of ducks. Accordingly, Pekin ducks were maintained on feed containing varying doses of (0.0; 0.5; 5.0; 15.0 ppm) of MeHg (Group I - control to IV) for 12 weeks and sacrificed. Tissue from the magnum and the shell gland regions of the oviduct was processed for scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the primary and secondary folds of these regions of the oviducts of the control and 0.5 ppm treatment group were densely populated with ciliated cells and that the cilia tend to cover the apical surfaces of the non-ciliated secretory cells. This unchanged ultrastructural morphology of the surface epithelium of 0.5 ppm treatment group was verified with TEM. The ciliated and nonciliated cells in surface epithelium appeared to be equal in frequency. The nuclei of ciliated cells were superficial in location compared to nonciliated secretory cells which had nuclei in the basal part of the cytoplasm. In the oviducal tissues from ducks fed 5.0 ppm MeHg isolated areas of ciliary loss, but minimal disruption of the apical plasma membrane were observed by SEM. In a few birds plasma membrane lesions, condensation of nuclear chromatin and very dilated rough endoplasmic reticulum were seen with TEM. In the oviducal tissues from ducks fed 15.0 ppm MeHg it could be seen that ciliary loss was much more extensive than hitherto observed, and disruption of the apex of cells could be seen. TEM showed degeneration of cytoplasmic organelles, more or less severely damaged ciliated cells, loss of ciliary extensions and formation of compound cilia. These observations indicate that methyl mercury at 5.0 and 15.0 ppm dose levels causes toxic injury to oviducal surface epithelium of Pekin duck that may cause reduced reproductive capability

Ultrastructural Analysis of Dynamic Cellular Processes: A Survey of Current Problems, Pitfalls and Perspectives

Dynamic phenomena in cells that can be analyzed on the ultrastructural level comprise so different aspects as ion shifts, conformational changes of macromolecules, membrane particle rearrangements, lipid phase transitions, protein--protein interactions (notably ligand-receptor interactions, including their sorting and sequestration), reversible membrane-to-membrane contacts, membrane fusions, transcellular transport phenomena, restructuring of cytoskeletal elements, ciliary and flagellar beat, cell shape changes, etc. Only some of these phenomena can be analyzed under stationary conditions, while others are unidirectional and sometimes very rapid. Therefore, the methodical approaches to be used (primary methods and follow-up procedures) might be widely different. Quite different methods are available, such as fast freezing, specific labeling, low temperature processing and/or analysis, x-ray-microanalysis, etc. Only occasionally are there alternative non-ultrastructural control methods available. This survey paper tries to analyze the degree of reliability (or uncertainty) of current methods and to pinpoint the goals and eventually also new methodical perspectives for an integrative approach to analyze dynamic cellular processes with the high temporal and spatial resolution provided by the electron microscope

ECTOPIC HORMONE PRODUCTION AND GENE EXPRESSION IN TUMORS

異所性ホルモン産生とはもともと非内分泌腺腫瘍によるホルモン産生を指していたが， 現在では正所性産生と考えられる場合も少なくないことが知られている。本腫瘍はペプチドホルモン，神経ペプチド，成長因子などを産生・分泌し，生化学的，免疫化学的ならびに形態学的研究により， 産生ホルモンの種類・分子多様性，複数ホルモン同時産生などに個々の腫瘍による特徴が見出される。最近，遺伝子組換え技術の進歩により多数のホルモンの遺伝子構造が解明され，ホルモン前駆体のアミノ酸配列も明らかにされた。今後，正常細胞と腫瘍細胞におけるホルモン遺伝子の相違の有無， 遺伝子発現機構およびホルモン前駆体のプロセシングの機構についての研究の発展が期待される。Recent progress in research into ectopic hormone production and hormone gene expression in tumors is reviewed. Biochemical, immunochemical and morphological studies have shown that differentiation between “ectopic " and “eulopic” has become difficult and that the types of peptide hormones, neural peptides and growth factors produced, their molecular heterogeneities and ability of plural hormone production are greatly different in each tumor. Recently, the gene structures of many hormones and amino acid sequences of hormone precursors have been determined by genetic recombination techniques. However, the nature of hormone genes, the mechanism of gene expression and the processing mechanisms of hormone precursors in normal and tumor cells remain to be studied