Phytanic acid α-hydroxylation by bacterial cytochrome P450

Fatty acid α-hydroxylase, a cytochrome P450 enzyme, from Sphingomonas paucimobilis, utilizes various straight-chain fatty acids as substrates. We investigated whether a recombinant fatty acid α-hydroxylase is able to metabolize phytanic acid, a methyl-branched fatty acid. When phytanic acid was incubated with the recombinant enzyme in the presence of H₂O₂, a reaction product was detected by gas chromatography, whereas a reaction product was not detected in the absence of H₂O₂. When a heat-inactivated enzyme was used, a reaction product was not detected with any concentration of H₂O₂. Analysis of the methylated product by gas chromatography-mass spectrometry revealed a fragmentation pattern of 2-hydroxyphytanic acid methyl ester. By single-ion monitoring, the mass ion and the characteristic fragmentation ions of 2-hydroxyphytanic acid methyl ester were detected at the retention time corresponding to the time of the product observed on the gas chromatogram. The K _m value for phytanic acid was approximately 50 μM, which was similar to that for myristic acid, although the calculated V _max for phytanic acid was about 15-fold lower than that for myristic acid. These results indicate that a bacterial cytochrome P450 is able to oxidize phytanic acid to form 2-hydroxyphytanic acid.     

Polyethyleneimine/chitosan hexamer-mediated gene transfection into intestinal epithelial cell cultured in serum-containing medium

In search of an efficient nonviral vector, polyethyleneimine (PEI)-based vectors were examined. In general, the transfection efficiency of nonviral vectors is suppressed by serum. Here we show that PEI based vectors, particularly, the chitosan hexamer-PEI vector, could perform efficient gene transfection into intestinal epithelial cells (IEC-6) in the presence of serum. The conjugation order of the two polymers with a plasmid (first, chitosan hexamer; second, PEI) was found to be an important factor in enhancing transfection efficiency.     

AC Drive System for Tension Reel Control

Recently, adjustable-speed ac drive systems have been employed successfully for blowers, pumps, table rollers, etc., in steel plants instead of the more conventional dc drives. In processing lines many drives require speed and tension control. To confirm the suitability of an ac drive for tension control, the tension reel of an existing pilot processing line has been equipped with an adjustable-speed ac drive. An ac drive system for tension reel control, its characteristics, and performance are described and compared with a dc tension control.     

Computational Ability of Cells based on Cell Dynamics and Adaptability

Learning how biological systems solve problems could help to design new methods of computation. Information processing in simple cellular organisms is interesting, as they have survived for almost 1 billion years using a simple system of information processing. Here we discuss a well-studied model system: the large amoeboid Physarum plasmodium. This amoeba can find approximate solutions for combinatorial optimization problems, such as solving a maze or a shortest network problem. In this report, we describe problem solving by the amoeba, and the computational methods that can be extracted from biological behaviors. The algorithm designed based on Physarum is both simple and useful. Tutorial series of three invited papers

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Formation of layer-like voids in irradiated polytrioxane

The formation of voids and defects is investigated by X-ray diffraction methods, by weight loss measurement and by electron microscopy, for an irradiated polytrioxane (PTOX) obtained by the-ray-induced polymerization of trioxane in the solid state. The main reasons for the formation of the layer-like voids are transverse decomposition at a selective point accessible to the radiation in the micro-fibrils, and the subsequent extensible depolymerization which may occur from the unstable chain end with increase of the radiation dose. The analysis of the SAXS curve for the irradiated PTOX, according to Tsvankin's method gives reasonable results for the void structure, where the reduction of the sub-crystal fraction and also the weight loss of the sample by irradiation are taken into account.     

Changes in the drift and the settlement of the freshwater mussel Limnoperna fortunei along a headrace channel

The nuisance species Limnoperna fortunei is a freshwater mussel whose infestations have harmed water intake facilities, such as water supply systems. We investigated the changes in the drift and the settlement of L. fortunei along a headrace channel. The densities of the drift and the settlement both decreased dramatically with the downstream distance from the L. fortunei source (a reservoir). In comparison with larval densities in the reservoir, drift densities decreased by 10 to 25% at 0.5 km downstream from the reservoir, and were less than 2% at sites more than 4.8 km downstream. Although larval densities at midnight (0:00-2:00) were approximately 1.5 times higher than those at noon (12:00-14:00) in a shallow layer (3 m depth) of the reservoir, we found no diurnal variation of drift densities in the headrace channel. Settlement densities at the site nearest the intake gate were much higher than those of the other sites further downstream in the headrace channel. The L. fortunei adult population in the channel could reduce drift individuals by attracting the larva. The attraction probably induces the massive aggregation at the location of the channel immediately below the drift source, resulting in biofouling.     

Synthesis of 1,3-dicapryloyl-2-docosahexaenoylglycerol by a combination of nonselective and <Emphasis Type="Italic">sn</Emphasis>-1,3-selective lipase reactions

A two-step consecutive synthetic method for the production of symmetrical, structured lipids by a combination of nonselective and sn-1,3 regioselective ester exchange reactions was investigated. In the first step, TAG with unspecifically substituted DHA were obtained by reacting tricapryloylglycerol (CCC) with ethyl docosahexanoate (EtDHA) using the lipase QLM (from Alcaligenes sp.), followed by removing the ethyl ester and CCC by molecular distillation. In the second step, sn-1,3 regioselective ester exchange was achieved by reacting the resulting TAG with ethyl caprylate (EtC) using the immobilized lipase Novozyme 435 (Candida antarctica lipase), followed by distillation of the ethyl ester and CCC to give sn-1,3-dicapryloyl-sn-2-docosahexaenoylglycerol (CDC). The acylglycerol composition of CDC was analyzed by GLC, which showed that the content of dicapryloyl-docosahexaenoylglycerols (2CD) in the product was 76.4%, and that the ratio of CDC to sn-1,2-dicapryloyl-sn-3-docosahexaenoylglycerol contained in 2CD was 82.7∶17.3 (%). The distillates CCC, EtDHA, and EtC could be recycled repeatedly to produce CDC as the substrate for the consecutive ester exchange reaction. In addition, separation of CCC and EtDHA was unnecessary for reuse. The present method is considered to meet the requirements for industrial utilization, in which simplicity in scaleup, high yields, compact reaction system, and minimal formation of by-products are important factors.     

Fatty acid-specific, regiospecific, and stereospecific hydroxylation by cytochrome P450 (CYP152B1) from Sphingomonas paucimobilis: Substrate structure required for α-hydroxylation

Fatty acid α-hydroxylase from Sphingomonas paucimobilis is an unusual cytochrome P450 enzyme that hydroxylates the α-carbon of fatty acids in the presence of H₂O₂. Herein, we describe our investigation concerning the utilization of various substrates and the optical configuration of the α-hydroxyl product using a recombinant form of this enzyme. This enzyme can metabolize saturated fatty acids with carbon chain lengths of more than 10. The K _m value for pentadecanoic acid (C₁₅) was the smallest among the saturated fatty acids tested (C₁₀–C₁₈) and that for myristic acid (C₁₄) showed similar enzyme kinetics to those seen for C₁₅. As shorter or longer carbon chain lengths were used, K _m values increased. The turnover numbers for fatty acids with carbon chain lengths of more than 11 were of the same order of magnitude (10³ min⁻¹), but the turnover number for undecanoic acid (C₁₁) was less. Dicarboxylic fatty acids and methyl myristate were not metabolized, but monomethyl hexadecanedioate and ω-hydroxypalmitic acid were metabolized, though with lower turnover values. Arachidonic acid was a good substrate, comparable to C₁₄ or C₁₅. The metabolite of arachidonic acid was only α-hydroxyarachidonic acid. Alkanes, fatty alcohols, and fatty aldehydes were not utilized as substrates. Analysis of the optical configurations of the α-hydroxylated products demonstrated that the products were S-enantiomers (more than 98% enantiomerically pure). These results suggested that this P450 enzyme is strictly responsible for fatty acids and catalyzes highly stereo- and regioselective hydroxylation, where structure of ω-carbon and carboxyl carbon as well as carbon chain length of fatty acids are important for substrate-enzyme interaction.     

Microstructure and elemental distribution of americium-containing uranium plutonium mixed oxide fuel under a short-term irradiation test in a fast reactor

In order to investigate the effect of americium addition in MOX fuel on the irradiation behavior, the ‘Am-1’ program is being conducted in the experimental fast reactor Joyo. The Am-1 program consists of two short-term irradiation tests of 10 min and 24 h irradiations and a steady-state irradiation test. The short-term irradiation tests were successfully completed and the post irradiation examinations (PIEs) are in progress. This paper reports on the results of PIEs for Am-containing MOX fuel irradiated for 10 min. MOX fuel pellets containing 3% or 5% Am were fabricated in a shielded air-tight hot cell using a remote handling technique. The oxygen to metal ratio (O/M) of these fuel pellets was 1.98. They were irradiated at peak linear heating rate of about 43 kW m⁻¹. Focus was being placed on migration behavior of Am during the irradiation. The ceramography results showed that structural changes such as lenticular pores and a central void occurred early, within the brief 10 min of irradiation. The results of electron probe microanalysis revealed that the concentration of Am increased in the vicinity of the central void.     

Successful treatment of bilateral deep femoral aneurysms and multiple iliac aneurysms associated with severe aortic valve disease: report of a case

We report herein the case of a patient in whom aneurysms of the bilateral deep femoral arteries (DFA) and multiple iliac aneurysms associated with severe aortic valve disease were successfully treated by a two-staged operation. The patient was a 74-year-old man who had dense calcification of the ascending aorta and aortic arch. Prior to aortic valve replacement (AVR), the aneurysms of the DFA and internal iliac arteries were resected. The terminal end of the abdominal aorta and bilateral common iliac arteries were then reconstructed with a Y graft to be used as a possible alternative arterial input route in place of the ascending aorta for extracorporeal circulation during the AVR. The inferior mesenteric artery (IMA) was well developed, and the external iliac arteries and their branches were preserved at aneurysmectomy. Postoperatively, there was no ischemia of the pelvic organs or the hip muscles. The AVR was subsequently performed 5 weeks after the first operation, and the patient was discharged after an uneventful postoperative course.