Charge-state-derivation ion detection using a super-conducting nanostructure device for mass spectrometry.

Mass spectrometry (MS) is a method of analyzing ions based on their mass/charge (m/z) ratios. The m/z peak identification requires speculation on the ionic unit-charge states. This problem can be solved by using superconducting junction devices to measure the kinetic energies of single molecules. However, the kinetic energy measurement is followed by the dead time of 1-20 µs, which is fatally slow for modern high-resolution time-of-flight (TOF) analyzers. In this paper, we demonstrate that a superconducting nano-stripline detector (SSLD) composed of a 10-nm-thick and 800-nm-wide NbN strip realizes the charge-state derivation, and furthermore satisfies the ideal MS detector specifications such as a nano-second response, a short recovery time, a wide mass range, and no noise.

NMR study on the interaction between MHC class I protein and its antigen peptide.

A major histcompatibility complex (MHC) class I protein H-2K(b) was expressed in a large scale as a fusion protein with thioredoxin and hexahistidine at the N-terminus to analyze the interaction with the antigen peptide SIYRYYGL. NMR spectra of the peptide in the mixture solution with the protein showed very broad signals, indicating the obviously clear existence of the dynamic interaction between the class I protein and the antigen peptide. The interaction of the protein and peptide was discussed as well as the surrounding atmosphere of the peptide in the complex.

Neurotoxicity of panipenem/betamipron, a new carbapenem, in rabbits: correlation to concentration in central nervous system.

The neurotoxic potential of panipenem/betamipron (PAPM/BP), a new carbapenem antibiotic, was compared with that of imipenem/cilastatin (IPM/CS). The drug concentration in cerebrospinal fluid (CSF) at the onset of epileptogenic electroencephalographic (EEG)-activity and the drug distribution into the central nervous system (CNS) were evaluated. Epileptogenic reactions correlated well with drug levels in CSF, but not with drug levels in circulating plasma. The concentration of PAPM in CSF at the onset of epileptogenic EEG-activity was almost twice that of IPM, suggesting that neurotoxic activity of PAPM is about half that of IPM. In addition, in terms of incidence percent for the epileptogenic EEG-activity, PAPM/BP was found to be less toxic than IPM/CS within the dose of 1.0-1.2 g/kg. Concentrations of PAPM in CSF and brain extracellular fluid after PAPM/BP i.v. infusion were comparable with those of IPM after IPM/CS infusion, indicating the similar characteristics of distribution into the CNS for the two antibiotics. From these results of pharmacologic effects and drug distributions, it is suggested that the neurotoxicity of PAPM/BP is less than half that of IPM/CS.

Complestatin, a potent anti-complement substance produced by Streptomyces lavendulae. I. Fermentation, isolation and biological characterization.

A new potent inhibitor of complement system, named complestatin, was isolated from the mycelium of Streptomyces lavendulae SANK 60477. Complestatin (C61H45N7O15Cl6, MW 1,325) was a peptide compound having two unusual amino acids, D-(-)-4-hydroxyphenylglycine and D-(-)-3,5-dichloro-4-hydroxyphenylglycine. This compound inhibited the hemolysis of sensitized sheep erythrocytes (EA) mediated by guinea pig and human complement 50% at concentrations of 0.4 and 0.7 micrograms/ml, respectively, but did not trypsin and alpha-chymotrypsin activities at 200 micrograms/ml. When complestatin was administered intravenously to the sensitized guinea pigs, it strongly inhibited the systemic anaphylactic shock elicited by the antigen probably by blocking generation of anaphylatoxins (C3a and C5a).