Analysis of K-ras and p53 mutations in mesotheliomas from humans and rats exposed to asbestos

Malignant mesothelioma is known to be associated with asbestos exposure. However, the mechanism of mesothelial carcinogenesis in relation to the activation of proto-oncogenes or inactivation of tumor suppressor genes remains unclear. In this study, the PCR-Primer Introduced Restriction Site (PCR-PIRS) assay was employed to examine mutations in the K-ras proto-oncogene in mesothelioma tissues from workers exposed to asbestos and from rats treated with asbestos. Mutations in exons 5-8 of the p53 tumor suppressor gene were determined by direct DNA sequence analysis. Results of the PCR-PIRS analysis revealed no mutations in codons 12, 13 or 61 of the K-ras gene in any of the 17 human or 22 rat mesothelioma tissue samples. These results were confirmed by direct DNA sequence analysis. No mutations were found in exons 5-8 of the p53 gene in any of the mesothelioma tissue samples analyzed. These results and the results reported by others indicate that the K-ras proto-oncogene and p53 tumor suppressor gene may not play a critical role in the induction of mesothelioma by asbestos either in humans or in rats.     

Is dipalmitoylphosphatidylcholine a substrate for convertase?

Convertase has homology with carboxylesterases, but its substrate(s) is not known. Accordingly, we determined whether dipalmitoylphosphatidylcholine (DPPC), the major phospholipid in surfactant, was a substrate for convertase. We measured [(3)H]choline release during cycling of the heavy subtype containing [(3)H]choline-labeled DPPC with convertase, phospholipases A(2), B, C, and D, liver esterase, and elastase. Cycling with liver esterase or peanut or cabbage phospholipase D produced the characteristic profile of heavy and light peaks observed on cycling with convertase. In contrast, phospholipases A(2), B, and C and yeast phospholipase D produced a broad band of radioactivity across the gradient without distinct peaks. [(3)H]choline was released when natural surfactant containing [(3)H]choline-labeled DPPC was cycled with yeast phospholipase D but not with convertase or peanut and cabbage phospholipases D. Similarly, yeast phospholipase D hydrolyzed [(3)H]choline from [(3)H]choline-labeled DPPC after incubation in vitro, whereas convertase, liver esterase, or peanut and cabbage phospholipases D did not. Thus convertase, liver esterase, and plant phospholipases D did not hydrolyze choline from DPPC either on cycling or during incubation with enzyme in vitro. In conclusion, conversion of heavy to light subtype of surfactant by convertase may require a phospholipase D type hydrolysis of phospholipids, but the substrate in this reaction is not DPPC.     

31P and19F NMR studies of glycophorin-reconstituted membranes: Preferential interaction of glycophorin with phosphatidylserine

Summary Glycophorin A, a major glycoprotein of the erythrocyte membrane, has been incorporated into small unilamellar vesicles composed of a variety of pure and mixed phospholipids. Nuclear spin labels including³¹P and¹⁹F have been used at natural abundance or have been synthetically incorporated in lipids to act as probes of lipid-protein interaction. Interactions produce broadening of resonances in several cases and it can be used to demonstrate preferential interaction of certain lipids with glycophorin.³¹P and¹⁹F probes show a strong preferential interaction of glycophorin with phosphatidylserine over phosphatidylcholine. There is some evidence that interactions are more pronounced at the inner surface of the bilayer and these results are rationalized in terms of the asymmetric distribution of protein and lipid.     

日立835─50型氨基酸分析仪故障排除六例

给出日立８３５－５０型氨基酸分析仪使用过程中出现的六种故障现象及判断排除方法     

Modulation of apolipoprotein B antigenic determinants in human low density lipoprotein subclasses

To investigate the effect of low density lipoprotein (LDL) heterogeneity on the conformation of LDL apolipoprotein B (apo-B), the immunoreactivities of 6 monoclonal antibodies against LDL apo-B were measured in 3 LDL subfractions isolated by equilibrium density gradient ultracentrifugation. To ensure a broad range of LDL particles, the LDL subfractions were prepared from normal subjects and patients with hyperapobetalipoproteinemia. With 3 of the antibodies, 1D1, 5E11, and 3A10, LDL fractions 1 (the most buoyant), 2 (the intermediate), and 3 (the densest) were equally immunoreactive and competed similarly with reference whole LDL. In contrast, with 3 other antibodies, 2D8, 3F5, and 4G3, fraction 1 was significantly more reactive than fraction 3; that is for each in turn, 290, 250, and 150% more of the densest LDL protein was required to achieve the same displacement as with fraction 1. Further, the immunoreactivities of the 3 LDL fractions with antibodies 2D8, 3F5, and 4G3 were negatively correlated with their LDL cholesterol to LDL protein ratio with r values of 0.727, 0.898, and 0.870, respectively, suggesting that as LDL particle size decreases, the conformation of the LDL apo-B changes progressively. It is of interest that the antigenic determinants recognized by 3F5 and 4G3 are close to the LDL receptor recognition site on LDL apo-B. Therefore, it is possible that the reduced immunoreactivity of these determinants in dense LDL may be the in vitro correlate of the reduced fractional catabolics rate of dense LDL compared to buoyant LDL previously observed in vivo.     

Dietary factors affecting the urinary mutagenicity assay system. II. The absence of mutagenic activity in human urine following consumption of red wine or grape juice

The mutagenic activity of urine samples from nonsmoking individuals before and after the consumption of either red wine or grape juice was determined. Urine samples collected from individuals on liquid or regular diets were concentrated using XAD-2 resin. No mutagenic activity of urine concentrates was detected with Salmonella tester strains TA98 or TA100 with or without microsomal activation. The addition of 1000 units of beta-glucuronidase into the agar overlay did not show any mutagenic activity. The mutagens in red wine and grape juice, however, were extracted using the XAD-2 column. Concentrates of urine samples spiked with either of the two extracts exhibited mutagenic activity.     

Proton nuclear magnetic resonance assignments of thyroid hormone and its analogues

1H NMR data of a series of thyroid hormone analogues, e.g., thyroxine (T4), 3,5,3'-triiodothyronine (T3), 3,3',5'-triiodothyronine (rT3), 3,3'-diiodothyronine (3,3'-T2), 3,5-diiodothyronine (3,5-T2), 3',5'-diiodothyronine (3',5'-T2), 3-monoidothyronine (3-T1), 3'-monoiodothyronine (3'-T1), and thyronine (TO) in dimethylsulfoxide (DMSO) have been obtained on a 300 MHz spectrometer. The chemical shift and coupling constant are determined and tabulated for each aromatic proton. The inner tyrosyl ring protons in T4, T3, and 3,5-T2 have downfield chemical shifts with respect to those of the outer phenolic ring protons. Four-bond cross-ring coupling has been observed in all the monoiodinated rings. However, this long-range coupling does not exist in T4, diiodinated on both rings, and T0, containing no iodines on the rings. There is no evidence that at 30 degrees C these iodothyronines have any motional constraint in DMSO solution. In addition to identification of the hormones, the potential use of some characteristic peaks as probes in binding studies is discussed.     

Biological kinetics evaluation of anaerobic stabilization pond treatment of palm oil mill effluent

Biological kinetic (bio-kinetic) study of the anaerobic stabilization pond treatment of palm oil mill effluent (POME) was carried out in a laboratory anaerobic bench scale reactor (ABSR). The reactor was operated at different feed flow-rates of 0.63, 0.76, 0.95, 1.27, 1.9 and 3.8 l of raw POME for a day. Chemical oxygen demand (COD) as influent substrates was selected for bio-kinetic study. The investigation showed that the growth yield (Y_G), specific biomass decay (b), maximum specific biomass growth rate (μ_max), saturation constant (K_s) and critical retention time (Θ_c) were in the range of 0.990 g VSS/g COD_removed day, 0.024 day⁻¹, 0.524 day⁻¹, 203.433 g COD l⁻¹ and 1.908 day, respectively.     

Preparation of cationic cotton with two-bath pad-bake process and its application in salt-free dyeing

Cationic cotton was prepared by a designed two-bath pad-bake process with 3-chloro-2-hydroxypropyltrimethylammonium chloride as cationizing reagent to realize recycle utilization of the reagent and continuous processing of cationization. Experiments showed that 8.0% (o.w.bath) of the reagent, 1:1 of molar ratio of sodium hydroxide to the reagent, 60 °C and 6 min of baking temperature and time were selected for cationization and the obtained cationic cotton was suitable for application in salt-free reactive dyeing. The structures of both the untreated and cationic fibers were investigated by X-ray diffraction and scanning electronic microscopy. Higher dye utilization and color yields could be realized on the cationic cotton than that on the untreated one in the conventional dyeing. Levelness dyeing and good fastness properties of the dyes on the cationic fabrics were obtained. Besides, colorimetric properties and mechanical strength of the dyed fabrics were both evaluated to show applicability of this preparation process of cationic cotton.