Ionspray ionization-mass spectrometric separation and determination of heptafluorobutyryl derivatives of polyamines

It has been reported that glutamate-induced neurotoxicity is related to an increase in nitric oxide (NO) concentration. An NO-sensitive electrode has been developed to measure NO concentration directly. Using this electrode, we examined NO concentration and neuronal survival after glutamate application in rat cultured cortical neurons. We also examined the effects of NMDA receptor antagonists, MK-801 and ketamine, and the NO synthetase inhibitor, L-NMMA on NO production and neuronal death. After 7 days in culture, application of glutamate (1 mM) or L-arginine (0.3 mM) to the cultured medium increased NO concentration, and decreased the number of anti-microtubule-associated protein 2 positive neurons. Both pretreatment with MK-801 (300 microns) and ketamine (300 microns) prevented glutamate-, but not L-arginine-induced increase in NO concentration and neuronal death. L-NMMA prevented both glutamate- and L-arginine-induced NO production and neuronal death. The nitric oxide donor, S-nitroso-N-acetyl-D,L-penicillamine (SNAP) also caused neuronal death, and MK-801, ketamine and L-NMMA did not prevent SNAP-induced toxicity. We have demonstrated excitatory amino acid-induced changes of NO concentration and the parallel relationship between changes of NO concentration and neuronal death. In conclusion, an increase in NO concentration does induce neuronal death, and the inhibition of the production of NO prevents glutamate-induced neuronal death.     

Regioselective introduction of β-galactoside branches into chitosan and chitin

β-d-Galactoside branches have been introduced into chitosan and chitin regioselectively through a series of controlled modification reactions based on N-phthaloyl-chitosan. The glycosylation reaction between a chitosan derivative having a reactive group only at C-6 and an orthoester of d-galactose proceeded efficiently to give a protected product with a degree of substitution up to about 0.5. Deprotection gave a branched chitosan, and the subsequent N-acetylation afforded a branched chitin. Unlike chitosan and chitin, the resulting nonnatural branched polysaccharides were characterized by high affinity for solvents and readily soluble in neutral water. Furthermore, branched chitin was easily degraded by lysozyme. Received: 31 July 1997/Revised: 2 September 1997/Accepted: 19 September 1997     

Reference sample for the evaluation of SEM image resolution at a high magnification--nanometer-scale Au particles on an HOPG substrate

A new sample preparation technique is proposed for evaluating image resolution in a high magnification range of SEM. The proposed reference samples are uniformly distributed nanometer-scale Au particles on HOPG substrate. The samples are fabricated using the conventional ion sputter coater. The grain size and granularity are controlled by reducing the sputter-induced damage in the top layers of HOPG. The sample heating prior to SEM imaging is essential to suppress beam induced contamination. The heating time and temperature are selected to inhibit large increases in the grain sizes of Au particles. The sputter coated Au particles on the freshly cleaved HOPG substrate are superior in the deviations of particle sizes to the vacuum evaporated Au particles on the plasma etched substrates. The granularity and homogeneous distribution of Au particles on HOPG are demonstrated at a magnification range of x180k to x800k. The average grain size of 3.2 nm and the standard deviation of 1.3 nm are obtained under the condition of an annealing temperature of 180 degrees C for 7 min after sputter coating an average thickness of 0.7 nm.     

Nontrivial polarization shaping of femtosecond pulses by reference to the results of dual-channel spectral interferometry

Adaptive shaping of time-dependent polarization pulses is performed by reference to the analyzed results of dual-channel spectral interferometry. The desired pulses can be generated only by use of such a polarization-characterization technique. We demonstrate the generation of shaped femtosecond pulses whose ellipticity increases at a constant rate. The relative error between the shaped pulse and the target pulse is less than 6% over the main part of the pulse. Shaped time-dependent polarization pulses have many potential applications.     

Contents and its change during storage of alpha-solanine and alpha-chaconine in potatoes

Contents of alpha-solanine and alpha-chaconine in native species of potato (May Queen, Danshaku and Waseshiro), and in species (Jagakids Red '90 (Red) and Jagakids Purple '90 (Purple)) on the market, and their change during storage at room temparature were investigated. alpha-Solanine and alpha-chaconine were extracted from potatoes with methanol, cleaned up by using a Sep-Pak Plus C18 cartridge, and then subjected to HPLC. The recoveries of alpha-solanine and alpha-chaconine from potatoes were both more than 96%, and the quantitation limits were both 2 microg/g. alpha-Solanine and alpha-chaconine were detected in periderm in all samples at the levels of 260-320 microg/g in May Queen,190-240 microg/g in Danshaku, 43-63 microg/g in Waseshiro, 140-200 microg/g in Red and 84-130 microg/g in Purple, respectively. alpha-Solanine and alpha-chaconine were detected in the cortex in all samples of May Queen and Danshaku at the levels of 2.7-12 microg/g and 5.8-31 microg/g, respectively. Contents of alpha-solanine and alpha-chaconine in the cortex of May Queen and Danshaku were less than 10% of those in the periderm. When potatoes were stored for 90 days at room temparature in a dark place, no marked change in the contents of alpha-solanine and alpha-chaconine was observed in any of the potato samples.     

Adaptor polymerase chain reaction for single molecule amplification

The adaptor polymerase chain reaction (PCR) permits the amplification of DNA fragments with arbitrary sequences. In this paper, we describe the successful amplification of plasmid-derived single molecule DNAs digested by a restriction enzyme. By using adaptors made of short and long oligonucleotides, nonspecific interactions during PCR were suppressed. The method will be applicable to the detection of single molecule DNA fragments even if their sequence is unknown.     

Development of flexible joint for 500 kV Al-sheathed OF cable

The authors have developed a flexible dimensionally flush joint for 500 kV aluminum-sheathed oil-filled cables with handling characteristics similar to the cable itself so that it may be readily drawn into ducts in the same way as the cable without suffering damage. The process and characteristics are outlined. This joint is intended for use at intermediate points on long bridges or tunnels where local assembly and installation of conventional joints would be difficult. In developing the joint, various novel techniques have been used, including the flexible flush jointing of segmental conductors, the flexible jointing of paper insulation by a combination of wrapping-back and stepping methods, and on-site aluminum sheath corrugating and sealing methods     

Anion exchange membranes prepared from chloromethylstyrene and 2-methyl-5-vinylpyridine

Strongly basic anion exchange membranes were prepared by the radical copolymerization of chloromethylstyrene and 2-methyl-5-vinylpyridine. The formation of a three-dimensional structure and the presence of the quarternary pyridinium group were confirmed by infrared spectrum analysis and its strongly basic anion exchange properties. Their electrochemical properties and morphology were compared with those of the anion exchange membranes prepared from chloromethylstyrene-divinylbenzene and 2-methyl-5-vinylpyridine-divinylbenzene. The chloromethylstyrene-2-methyl-5-vinylpyridine membranes were proved to have larger anion exchange capacity, smaller electric resistance, larger water content, and higher permeability than the chloromethylstyrene-divinylbenzene and 2-methyl-5-vinylpyridine-divinylbenzene membranes. Also, the membranes have heterogeneity in the cross-linking structure.     

Morphology and albumin secretion of adult rat hepatocytes cultured on a hydrophobic porous expanded polytetrafluoroethylene membrane

Repeated addition of insulin, together with an initial addition of the reduced form of glutathione (GSH) and a chelator, aurintricarboxylic acid (ATA), was proposed as a strategy for the dynamic control of apoptosis in serum-free culture of Chinese hamster ovary (CHO) cells. Insulin suppressed cell death in serum-free culture by means of lowering intracellular reactive oxygen species levels via an increase in the specific glucose consumption rate. This effect of insulin addition was found not only at 0 h but also at 48 h during serum-free cultivation. In consideration of the reduction of insulin by GSH, insulin was again added at 24 h following the initial addition during the serum-free cultivation. The repeated addition of insulin decreased cell death and increased the production of tissue plasminogen activator compared with the single addition at 0 h.