Solution Radioactivated by Hadron Radiation Can Increase Sister Chromatid Exchanges

When energetic particles irradiate matter, it becomes activated by nuclear reactions. Radioactivation induced cellular effects are not clearly understood, but it could be a part of bystander effects. This investigation is aimed at understanding the biological effects from radioactivation in solution induced by hadron radiation. Water or phosphate buffered saline was activated by being exposed to hadron radiation including protons, carbon- and iron-ions. 1 mL of radioactivated solution was transferred to flasks with Chinese hamster ovary (CHO) cells cultured in 5 mL of complete media. The induction of sister chromatid exchanges (SCE) was used to observe any increase in DNA damage responses. The energy spectrum and the half-lives of the radioactivation were analyzed by NaI scintillation detector in order to identify generated radionuclides. In the radioactivated solution, 511 keV gamma-rays were observed, and their half-lives were approximately 2 min, 10 min, and 20 min. They respectively correspond to the beta+ decay of ¹⁵O, ¹³N, and ¹¹C. The SCE frequencies in CHO cells increased depending on the amount of radioactivation in the solution. These were suppressed with a 2-hour delayed solution transfer or pretreatment with dimethyl sulfoxide (DMSO). Our results suggest that the SCE induction by radioactivated solution was mediated by free radicals produced by the annihilated gamma-rays. Since the SCE induction and DMSO modulation are also reported in radiation-induced bystander effects, our results imply that radioactivation of the solution may have some contribution to the bystander effects from hadron radiation. Further investigations are required to assess if radioactivation effects would attribute an additional level of cancer risk of the hadron radiation therapy itself.     

Isolation and partial characterization of a 39 kDa major outer membrane protein of Actinobacillus actinomycetemcomitans Y4

The outer membrane fractions of Actinobacillus actinomycetemcomitans, which were extracted from whole cells with cetyl trimethyl ammonium bromide and CaCl2, contained four major outer membrane proteins (MOMP) of 39, 37, 36 and 30 kDa. The 39 kDa MOMP of A. actinomycetemcomitans was sequentially purified by extraction with Zwittergent 3-14 detergent, anion-exchange chromatography and gel filtration chromatography. Analysis of amino acid composition and N-terminal amino acid sequence of 20 residues of purified 39 kDa MOMP was performed. Although some of the periodontitis patient sera reacted strongly with 39 kDa and 30 kDa MOMP in crude outer membrane fractions, purified 39 kDa MOMP showed decreased immunoreactivity with the human sera.     

Human hand impedance characteristics during maintained posture

Received: 23 June 1993 / Accepted in revised form: 15 September 1994     

Indoor environmental study and post occupancy evaluation in an office environment

1. 1. The objective of this paper is to investigate the indoor environment from the viewpoint of interaction between physical environment and the human responses. The field survey has been conducted over 1 year.

2. 2. A continuous measurement has been carried out for 1 week and distribution of variables have been measured for 1 day.

3. 3. The attitude of workers was investigated by a questionnaire.

4. 4. As the result, average luminance represented more than 1000 lx in the new building, in contrast with less tha 300 lx in the existing building.

5. 5. There was a significant difference of the occupants' response to the light environment between the two buildings.

6. 6. Measured thermal conditions are on the edge of the ASHRAE comfort envelope in summer, and in the neighborhood of the lower dry limit of the envelope in spring.

7. 7. The occupants' evaluations were remarkably changed before and after the moving. The office environment is better than that of the factory.

Purification and characterization of macrolide 2''-phosphotransferase type II from a strain of Escherichia coli highly resistant to macrolide antibiotics

Hyperimmune and high-titered polyclonal pneumococcal antisera, specific for cross-reactive types within groups, were produced in adult rabbits. Purified capsular polysaccharide was injected intravenously into adult rabbits. One week later, these rabbits were given multiple intravenous injections of formalin-inactivated pneumococci of the cross-reactive type by an established method. Each of the resultant antisera were specific for the cross-reactive type indicating that the previous injection of the polysaccharide had induced epitope-specific tolerance. This method was successful for production of antisera against pneumococcal types 6A, 6B, 9N, 9V, 19F and 19A. Polyclonal rabbit pneumococcal antisera have some advantages over murine monoclonal antibodies for serologic studies and this method should be applicable for producing type-specific antibodies to cross-reactive polysaccharides of clinical interest. Further, this method is simpler and generally produces higher titered monovalent (factor) reagents than absorbed antisera.     

Modelling and analyzing density-dependent population processes: Comparison between wild and laboratory strains of the bean weevil,Callosobruchus chinensis (L.)

Three models were constructed for analyzing the population characteristics ofC. chinensis on stored beans; model A describing the whole reproductive process with a single equation, model B describing the three age-specific processes (oviposition, egg survival and larval survival) with separate equations, and model C which describes all these processes not for the whole habitat but for the individual beans comprizing it. The logit equation was employed here as a common basis to describe the density-response relationship involved. All three models showed very good fit to the experimental data obtained for both laboratory and wild strains of the weevil. The parameter values characterizing the population dynamics were, however, widely different between the two strains; the laboratory one which had been reared for some 500 generations showed significantly higher reproductive capacity, less sensitive and gentler response to crowding in both adult and egg stages, and more uniform egg distribution among individual beans, as compared with the wild strain newly introduced. Sensitivity analyses using these models suggested that these changes in population characteristics have been attained by the process of domestication or adaptation to stable laboratory conditions through a long period of time. This process seemed in effect to have optimized the population's performances in the laboratory environment. Evolutionary significance of such optimization was discussed with reference to the selection pressure which may have acted upon individuals.     

Novel GABAA receptor alpha subunit is expressed only in cerebellar granule cells

GABA (gamma-aminobutyric acid), the major inhibitory neurotransmitter in the vertebrate brain, mediates neuronal inhibition by opening a chloride channel integral to the GABAA receptor. This action is potentiated by both benzodiazepine and barbiturate drugs. Since the isolation of cDNAs encoding GABAA receptor alpha 1 and beta 1 subunits, a further eight subunits have been identified. These subunits show GABAA receptor heterogeneity, unpredicted from classical pharmacological studies. I now report the isolation of a mouse cDNA clone encoding a novel GABAA receptor alpha subunit. The striking feature of this subunit is its regional distribution in the mouse brain. Northern hybridization and in situ hybridization experiments demonstrate that the subunit mRNA is expressed only in cerebellar granule cells. This is the first demonstration of the exclusive presence of a neuroreceptor subtype in a single neuronal cell type.     

Comparative Studies on Large- and Small-Plaque-Forming Clones of Newcastle Disease Virus (Miyadera Strain)

The Miyadera strain of Newcastle disease virus (NDV) consisted predominantly of virus particles forming small plaques on monolayers of chick embryo fibroblasts (CEF), and contained small amounts of virus particles forming large plaques. These large- and small-plaque-forming clones of this virus (NDV-L and NDV-S) were isolated. The small size of the NDV-S plaques did not appear to be due to an agar inhibitor. NDV-L produced a much higher yield of infective virus particles in CEF and they were released more completely from the infected cells than were those produced by NDV-S. The yield of infective virus of NDV-L per cell from cultures of CEF was comparable to the yield from the allantoic cells. The infectivity/hemagglutinin ratio for NDV-L from CEF was as high as the ratio for virus from the allantoic cells, but the ratio for NDV-S from CEF was lower. NDV-S demonstrated an autointerference phenomenon in CEF when infected at high multiplicities, but NDV-L did not. Contrary to virus multiplication, NDV-S exhibited a more rapid and marked cytopathic effect on monolayers of CEF than NDV-L. In the allantoic cavity of eggs NDV-S produced slightly higher virus yields than NDV-L. No correlation existed between plaque size of the two viruses and the capacity to induce interferon synthesis or the susceptibility to the action of interferon. The properties of both distinctive plaque isolates were stable on egg passage.     

Amino acid alterations essential for increasing the catalytic activity of the nylon-oligomer-degradation enzyme of Flavobacterium sp

The structural genes of two homologous enzymes, 6-aminohexanoate-dimer hydrolase (EII; nylB) and its evolutionally related protein EII' (nylB') of Flavobacterium sp. KI72 have an open reading frame encoding a peptide of 392 amino acids, of which 47 are different, and conserved restriction sites. The specific activity of EII towards 6-aminohexanoate dimer is about 1000-fold that of EII'. Construction of various hybrid genes obtained by exchanging fragments flanked by conserved restriction sites of the two genes demonstrated that two amino acid replacements in the EII' enzyme, i.e. Gly181----Asp (EII type) and His266----Asn (EII type), enhanced the activity toward 6-aminohexanoate dimer 1000-fold.