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.     

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.

A second Warburg-like effect in cancer metabolism: The metabolic shift of glutamine-derived nitrogen

Carbon and nitrogen are essential elements for life. Glucose as a carbon source and glutamine as a nitrogen source are important nutrients for cell proliferation. About 100 years ago, it was discovered that cancer cells that have acquired unlimited proliferative capacity and undergone malignant evolution in their host manifest a cancer-specific remodeling of glucose metabolism (the Warburg effect). Only recently, however, was it shown that the metabolism of glutamine-derived nitrogen is substantially shifted from glutaminolysis to nucleotide biosynthesis during malignant progression of cancer—which might be referred to as a “second” Warburg effect. In this review, address the mechanism and relevance of this metabolic shift of glutamine-derived nitrogen in human cancer. We also examine the clinical potential of anticancer therapies that modulate the metabolic pathways of glutamine-derived nitrogen. This shift may be as important as the shift in carbon metabolism, which has long been known as the Warburg effect.     

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.     

Correlation between Supercoiling and Conformational Motions of the Bacterial Flagellar Filament

The bacterial flagellar filament is a very large macromolecular assembly of a single protein, flagellin. Various supercoiled states of the filament exist, which are formed by two structurally different conformations of flagellin in different ratios. We investigated the correlation between supercoiling of the protofilaments and molecular dynamics in the flagellar filament using quasielastic and elastic incoherent neutron scattering on the picosecond and nanosecond timescales. Thermal fluctuations in the straight L- and R-type filaments were measured and compared to the resting state of the wild-type filament. Amplitudes of motion on the picosecond timescale were found to be similar in the different conformational states. Mean-square displacements and protein resilience on the 0.1 ns timescale demonstrate that the L-type state is more flexible and less resilient than the R-type, whereas the wild-type state lies in between. Our results provide strong support that supercoiling of the protofilaments in the flagellar filament is determined by the strength of molecular forces in and between the flagellin subunits.     

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.     

The structure of rooster-comb dermatan sulfate. Fragmentation of the polysaccharide chains by chondroitinase AC-II digestion,and by periodate oxidation,followed by alkali cleavage

The polysaccharide-chain fragments of rooster-comb dermatan sulfates (RC-20 and RC-30) were obtained by chondroitinase AC-II digestion and by periodate oxidation, followed by alkaline cleavage, and their structures analyzed both quantitatively and qualitatively. RC-20 having a lower d-glucuronic acid content (22.6%) is composed preponderantly of large clusters of N-acetyldermosine sulfate (M_r～17 600–41 000) at the nonreducing terminal, whereas RC-30, having a higher d-glucuronic acid content, (41.4%) is poor in this cluster. Both RC-20 and RC-30 have an N-acetyldermosine sulfate cluster (M_r 6500–7300) within the polysaccharide chains. Most N-acetylchondrosine sulfate units of RC-20 and RC-30 exist as clusters, the large clusters (M_r～17 600) being preponderant in RC-30; both RC-20 and RC-30 contain a large proportion of N-acetylchondrosine sulfate clusters (M_r 3500 and 9000) that corresponds to the uronic acid content. In RC-30, most N-acetyldermosine disulfate units (13.4%) are linked to N-acetylchondrosine sulfate units or clusters.     

Cell-cell contact promotes specific activity of pp60c-src protein kinase in human retinoblastoma cells.

Tyrosine-specific protein kinase activity of pp60c-src was examined in human Y79 retinoblastoma cells cultured in monolayers after clusters in suspension culture had been dissociated. The activity increased five- to six-fold between Days 1 and 7 in the monolayer cultures, with a concomitant increase in numbers of cellular contacts per cell. There was no effect of conditioned medium from high-density cultures in suspension on the activity of cultures with a low degree of contacts. The level of c-src protein in cell lysates was nearly constant irrespective of the degree of cellular contacts. These results suggest that the specific activity of pp60c-src is regulated by cell-cell contact.