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Biomedical subjects

Masao Suzuki

Publications and source records attributed to Masao Suzuki.

At least 19 recordsLinked to original sources
PubMed2005

Immortalization of human small airway epithelial cells by ectopic expression of telomerase.

Two immortalized human airway epithelial cell lines were established by the ectopic expression of human telomerase reverse transcriptase (hTERT). These cell lines have been continuously cultured for >200 population doublings (PDs). They are characterized by an overexpression of hTERT mRNA, elongated telomere length and higher telomerase activity. Early passage of these cells (<20 PDs) expressed the p16 protein at a level comparable to their parental cells. In later passages (>150 PDs), p16 protein was decreased but recovered to the early passage level upon treatment with a methylation inhibitor, 5-Aza-CdR. Chromosome analysis showed a near-diploid karyotype albeit with a gain or loss of certain chromosomes and a few stable translocations in both cell lines. No p53 gene alterations were found in these cell lines. They remained anchorage dependent in growth and were non-tumorigenic in nude mice. These two cell lines are the first reported immortalized human airway epithelial cell lines by hTERT expression without incorporation of virus or other genes, which may serve as a useful model system for studies on bronchial carcinogenesis.

Animals↗
PubMed2004

Genotoxicity in the eyes of bystander cells.

The controversial use of a linear, no threshold extrapolation model for low dose risk assessment has become even more so in light of the recent reports on the bystander phenomenon. The answer to the question as to which of the two phenomena, bystander versus adaptive response, is more important has practical implication in terms of low dose radiation risk assessment. In this review, genotoxicity is used as an endpoint to introduce the two phenomena, provide some insight into the mechanisms of bystander effect and to bridge the two low dose phenomena which operate in opposite directions: the bystander effect tends to exaggerate the effect at low doses, by communicating damage from hit to non-hit cells whereas the adaptive response confers resistance to a subsequent challenging dose by an initial low priming dose.

Alpha Particles↗
PubMed2004

Screening cost for abdominal aortic aneurysms: Japan-based estimates.

PURPOSE: The aim of this study was to evaluate the screening procedures in Japan economically focusing on the screening costs and the hospital costs for abdominal aortic aneurysm (AAA) surgery. METHODS: A total of 10,057 residents, 60 years of age or older, including 4 247 men and 5 810 women, participated in the screening test for AAA using ultrasound. RESULTS: Aneurysms were detected in 34 participants, including 32 men and 2 women. The detection rate of AAA was 0.8% in men, 0.03% in women, and 0.3% in total. It cost 8 US dollars to screen each participant, and the cost to detect each aneurysm was thus estimated at 1,250 dollars in men, 23,240 dollars in women, and 2,366 dollars in total. The difference in the mean hospital cost between ruptured and nonruptured AAA was 21,833 dollars in our recent cases. Obesity, male sex, and smoking habits were all significant risk factors for AAA. CONCLUSION: Screening for AAA using ultrasound is useful not only for the early detection of AAA but also for a reduction in the overall medical cost.

Aged↗
PubMed2004

Solid-liquid phase behavior of binary fatty acid mixtures. 1. Oleic acid/stearic acid and oleic acid/behenic acid mixtures.

Solid-liquid phase behavior of binary fatty acid mixtures was investigated by means of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) for the mixture composed of oleic acid (OA) and stearic acid (SA) and that composed of OA and behenic acid (BA). The DSC results provided a monotectic type T-X phase diagram for these mixtures, from which it was suggested that the two fatty acid species are completely immiscible in a solid phase regardless of the two polymorphs of OA, i.e., alpha-form or gamma-form. The solid phase immiscibility was confirmed by the FT-IR observation that the spectra obtained for the mixtures correspond to the superposition of the two spectra for respective components. Thermodynamic analysis of liquidus line demonstrated that OA and SA form an ideal mixture in a liquid phase, whereas the mixing of OA and BA in a liquid phase is slightly non-ideal.

Calorimetry, Differential Scanning↗
PubMed2004

Solid-liquid phase behavior of binary fatty acid mixtures. 2. Mixtures of oleic acid with lauric acid, myristic acid, and palmitic acid.

Solid-liquid phase behavior was investigated for binary fatty acid mixtures composed of oleic acid (OA; cis-9-octadecenoic acid) and saturated fatty acids, lauric acid (LA; dodecanoic acid), myristic acid (MA; tetradecanoic acid), and palmitic acid (PA; hexadecanoic acid), by means of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). When the mixture was heated immediately after the solidification from the melt, the heat effect due to the gamma-to-alpha transformation of OA varied depending on the composition of the mixture. However, the mixture subjected to an annealing at the temperature slightly below the melting temperature provided the transformation at constant temperature which corresponds to the gamma-to-alpha transformation temperature of pure OA. This suggests that a solid phase formed by cooling of the melt of the mixture is not in an equilibrium state, but it relaxes to a stable solid during the annealing process. The T-X phase diagrams of these mixtures constructed from the DSC measurements demonstrate that the two fatty acid species are completely immiscible in a solid phase regardless of the type of polymorphs of OA, alpha- or gamma-form. According to a thermodynamic analysis of liquidus line basing on the regular solution model for the melt, the non-ideality of mixing tends to increase with the decrease in the acyl chain length of the saturated fatty acid, although the mixing is rather close to ideal.

Calorimetry, Differential Scanning↗
PubMed2004

Solid-liquid phase behavior of binary fatty acid mixtures 3. Mixtures of oleic acid with capric acid (decanoic acid) and caprylic acid (octanoic acid).

Solid-liquid phase behavior of binary mixtures of oleic acid (OA)/capric acid (C10A) and OA/caprylic acid (C8A) were investigated by means of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction. The phase diagram of OA/C10A mixture constructed from the DSC results suggested that a molecular compound with the composition of OA:C10A = 3:2 is formed in a solid phase, and OA and the molecular compound are miscible, while C10A and the molecular compound are completely immiscible. The formation of the molecular compound was supported by the IR spectroscopic observation, and a possible model of the structure was proposed on the basis of X-ray diffraction spectrum in small angle region. This compound formation is characteristic of the OA/C10A mixture, and may be attributed to the similarity of the acyl chain length of C10A to the lengths of Delta- and omega-chains of OA (i.e., the chain segments divided by cis-double bond). The mixture of OA and C8A, whose chain length is close to but shorter than the two chain segments of OA, provided a eutectic-type phase diagram showing a partial mixing of the two components in OA-rich region. Thermodynamic analysis of the liquidus line in the phase diagram exhibits a systematic trend for the non-ideality parameter of mixing with the variation of the chain length difference between OA and saturated fatty acid species.

Calorimetry, Differential Scanning↗
PubMed2004

Structural study on polymorphism of long-chain dicarboxylic acids using oblique transmission method for micro FT-IR spectrometers.

Polymorphism and higher-order structures of even-number dicarboxylic acids from hexadecanedioic acid to eicosanedioic acid have been studied by micro-FTIR spectroscopy and microscopic observation. In order to obtain the three-dimensional structural information, the oblique transmission method was incorporated into a micro-FTIR spectrometer equipped with a couple of Cassegrain lenses. The IR spectra showed that the solid states of dicarboxylic acid bore a marked structural similarity to those of n-saturated fatty acids. It was found that a solution-grown single crystal of dicarboxylic acids was an aggregate of lamellae whose thickness exceeded by far their molecular length. The surfaces of lamellae were covered with hydrocarbon segments taking a hairpin structure, and the linkage of hydrogen-bonded dicarboxylic acids formed a folded chain structure. The result of oblique transmission measurements showed that the stacking mode of lamellae varied depending on crystallization conditions.

Biophysical Phenomena↗
PubMed2004

Frequency measuring system using mirror gap stabilized Fabry-Perot interferometer.

The mirror gap of a Fabry-Perot interferometer was stabilized with two laser diodes; one locked to the line frequency 385,243,555.14445 MHz of the F=3<--1 in 5D(3/2)<--5S(1/2) (87Rb) and the other to the 385,284,566.3663 MHz of the F=4<--2 in 5D(5/2)<--5S(1/2) (87Rb) [Opt. Commun. 102 (1993) 432]. The length of the mirror gap was adjusted to generate the zero-cross points simultaneously at both of the two line positions. The fringe signals obtained from an interferometer thus stabilized can be used as frequency markers having accuracies of the order of 10(10) depending on the finesse of the interferometer used. Based on measurement using Cs D1 hyperfine lines reported by Udem et al. [Phys. Rev. Lett. 82 (1999) 3568], the uncertainty of markers in the region 50 THz apart from the reference lines is +/- 5 MHz.

Data Interpretation, Statistical↗
PubMed2004

[The problems of multiple-chemical sensitivity patients in using medicinal drugs].

Multiple-chemical sensitivity (MCS) patients are presumed to be compelled to lead inconvenient and difficult lives, because unpleasant and multiorgan symptoms are caused by very small amounts of various chemicals in the living environment. Therefore we conducted a questionnaire survey of MCS patients who are members of support groups to elucidate the problems of MCS patients in using medicinal drugs. In this report, we selected 205 persons who stated that they had been "diagnosed with MCS by a physician" or "a physician suspected a diagnosis of MCS" on the questionnaire as the reason they judged themselves to have MCS. The questionnaire results showed that about 60% of MCS patients have difficulty in using medicinal drugs and that the difficulties are more likely to occur in women, in people 40-59 years old, and in patients who developed MCS in reaction to pesticides or medicinal drugs. The prescribed drugs and OTC drugs noted as usable or unusable by patients in the questionnaire were analyzed from the viewpoint of their medicinal constituents. The results indicated that lidocaine is likely to be unusable by MCS patients. In addition, caffeine, aspirin, chlorphenylamine maleate, minocycline hydrochloride, levofloxacin, etc. were also likely to be unusable by MCS patients. Many patients who recorded drugs containing the above-mentioned remedies as unusable had a past history of allergy, suggesting that allergy is involved in the difficulties of MCS patients in using medicinal drugs.

Adult↗
PubMed2004

Effect of medium on chromatin damage in bystander mammalian cells.

In the present study, we examined the potential contribution of irradiated medium to the bystander effect using custom-made double-Mylar stainless steel rings. Exponentially growing human-hamster hybrid (A(L)) cells were plated on either one or both sides of double-Mylar dishes 2-4 days before irradiation. One side (with or without cells) was irradiated with alpha particles using the track segment mode of a 4 MeV Van de Graaff accelerator at the Radiological Research Accelerator Facility of Columbia University. Since alpha particles can traverse only a very limited distance (around 23 microm in water), cells plated on the other side of a medium-filled Mylar dish will not be irradiated by the alpha particles. The results of the cytogenetic assay of unirradiated target cells that were attached to the top Mylar layer indicate that the number of chromatid-type aberrations was higher when there was a bottom layer of cells in the medium-filled chambers than with just medium alone. Furthermore, when the medium was transferred from these cell-irradiated dishes to fresh A(L) cell cultures, chromatid-type aberrations were produced in the unirradiated fresh cells. In contrast, medium irradiated in the absence of cells had no effect on chromatid aberrations. These results suggest that certain unidentified modulating factors secreted from the irradiated cells on the bottom Mylar layer into the medium induce chromatin damage in the unirradiated bystander cells.

Animals↗
PubMed2003

Protective effect of supplementation of fish oil with high n-3 polyunsaturated fatty acids against oxidative stress-induced DNA damage of rat liver in vivo.

The present study was undertaken to know the effect of supplementation of fish oil with high n-3 polyunsaturated fatty acids (PUFA) on oxidative stress-induced DNA damage of rat liver in vivo. Male Wistar rats were fed a diet containing fish oil or safflower oil with high n-6 PUFA at 50 g/kg of diet and an equal amount of vitamin E at 59 mg/kg of diet for 6 weeks. Livers of rats fed fish oil were rich in n-3 PUFA, whereas those of rats fed safflower oil were rich in n-6 PUFA. Ferric nitrilotriacetate was intraperitoneally injected to induce oxidative stress. The degree of lipid peroxidation of the liver was assessed by the levels of phospholipid hydroperoxides and thiobarbituric acid-reactive substances (TBARS), and the degree of oxidative DNA damage was assessed by comet type characterization in alkaline single-cell gel electrophoresis and 8-hydroxy-2'-deoxyguanosine levels. The levels of TBARS of the livers of the fish oil diet group increased to a greater extent than those of the safflower oil diet group, whereas the levels of the hydroperoxides of the livers of both diet groups increased to a similar extent. The vitamin E level of livers of the fish oil diet group was remarkably decreased. The degree of DNA damage of both diet groups was increased, but the increased level of the fish oil diet group was remarkably lower than that of the safflower oil diet group. The above results indicate that fish oil supplementation does not enhance but appears to protect against oxidative stress-induced DNA damage and suggest that lipid peroxidation does not enhance but lowers the DNA damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2003

Effect of supplementation of n-3 polyunsaturated fatty acids on oxidative stress-induced DNA damage of rat hepatocytes.

The effect of supplementation of n-3 polyunsaturated fatty acids (PUFA) on oxidative stress-induced DNA damage of rat hepatocytes was examined. Male Wistar rats were fed a diet containing safflower oil (control n-6 PUFA diet) or fish oil (n-3 PUFA diet) in 50 g/kg of dried diet and an equal amount of vitamin E in 59 mg/kg of dried diet for 6 weeks. The liver of rats fed safflower oil was rich in n-6 PUFA, whereas that of rats fed fish oil was rich in n-3 PUFA. Isolated hepatocytes were treated in vitro with ADP/Fe (II) ion or hydrogen peroxide at 37 degrees C for 30 min to induce oxidative stress. The degree of lipid peroxidation was assessed by the levels of phospholipid hydroperoxides and thiobarbituric acid-reactive substances. The degree of oxidative DNA damage was assessed based on comet-type characterization in alkaline single-cell gel electrophoresis and 8-hydroxy-deoxyguanosine levels. In both ADP/Fe(II) ion and hydrogen peroxide oxidation, the degree of lipid peroxidation of hepatocytes increased in both diet groups, and the level of increase in the fish oil diet group was slightly higher than that in the safflower oil diet group. In ADP/Fe(II) ion oxidation, the degree of DNA damage increased in both diet groups, but there were no significant differences in the level of increase. In contrast, in hydrogen peroxide oxidation, the degree of DNA damage increased in both diet, and the increase in the fish oil diet group was significantly lower than that in the safflower oil diet group. It is unlikely that an n-3 PUFA-rich diet enhances oxidative stress-induced hepatocyte DNA damage as compared with the control n-6 PUFA-rich diet.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2003

Qualitative and quantitative difference in mutation induction between carbon- and neon-ion beams in normal human cells.

We investigated the difference in cell-killing effect and mutation induction between carbon- and neon-ion beams in normal human cells. Carbon- and neon-ion beams were accelerated by the Riken Ring Cyclotron (RRC) at the Institute of Physical and Chemical Research in Japan. Cell-killing effect was measured as the reproductive cell death using the colony formation assay. Mutation induction at the HPRT locus was detected to measure 6-thioguanine-resistant clones. The mutation spectrum of the deletion pattern of exons of induced mutants was analyzed using the multiplex polymerase chain reaction (PCR). Cell-killing effect was almost the same between carbon- and neon-ion beams with similar linear energy transfer (LET) values, while there observed a large difference in mutation frequency. Furthermore, in the case of neon-ion beams 60% of mutants showed total deletions and 35-40% showed partial deletions, while 95-100% of carbon-ion induced mutants showed total deletions. The results suggest that different ion species may cause qualitative and quantitative difference in mutation induction even if the LET values are similar.

Carbon↗
PubMed2003

LET and ion-species dependence for cell killing and mutation induction in normal human fibroblasts.

We have been studying LET and ion species dependence of RBE values in cell killing and mutation induction. Normal human skin fibroblasts were irradiated with heavy-ion beams such as carbon (290 Mev/u and 135 Mev/u), neon (230 Mev/u and 400 Mev/u), silicon (490 Mev/u) and iron (500 Mev/u) ion beams, generated by Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences (NIRS). Cell killing effect was detected as reproductive cell death using a colony formation assay. Mutation induction in hprt locus was detected to measure 6-thioguanine resistant colonies. The RBE-LET curves of cell killing and mutation induction were different each ion beam. So, we plotted RBE for cell killing and mutation induction as function of Z*2/beta2 instead of LET. RBE-Z*2/beta2 curves of cell killing indicated that the discrepancy of RBE-LET curves was reconciled each ion species. But RBE-Z*2/beta2 curves of mutation induction didn't corresponded between carbon- and silicon-ion beams. These results suggested that different biological endpoints may be suitable for different physical parameter, which represent the track structure of energy deposition of ion beams.

Carbon↗
PubMed2003

Induction of a bystander chromosomal damage of He-ion microbeams in mammalian cells.

We report here a bystander effect in chromosomal damage using He-ion microbeam. Human-hamster hybrid cells were irradiated with a precision He-ion microbeam generated by the Columbia microbeam system. When 20% of the cells were exposed to single He ion, the incidence of cells with chromatid-type breaks detected with the PCC technique was covered wide range from 0 to 6 breaks per cell. In contrast, the distribution showed a mixed two-peak pattern, such as non-exposed and all-cell exposed patterns, under the condition of assuming no bystander effect by treating with an effective inhibitor of cell-cell communication. These findings provide clear evidence that single He-ion irradiated cells can induce bystander chromosomal alterations in neighboring cells not directly hit by He ion.

Animals↗
PubMed2002

Effects of irradiated medium with or without cells on bystander cell responses.

Recent studies have indicated that extranuclear or extracellular targets are important in mediating the bystander genotoxic effects of alpha-particles. In the present study, human-hamster hybrid (A(L)) cells were plated on either one or both sides of double-mylar dishes 2-4 days before irradiation, depending on the density requirement of experiments. One side (with or without cells) was irradiated with alpha-particles (from 0.1 to 100 Gy) using the track segment mode of a 4 MeV Van de Graaff accelerator. After irradiation, cells were kept in the dishes for either 1 or 48 h. The non-irradiated cells were then collected and assayed for both survival and mutation. When one side with cells was irradiated by alpha-particles (1, 10 and 100 Gy), the surviving fraction among the non-irradiated cells was significantly lower than that of control after 48 h co-culture. However, such a change was not detected after 1h co-culture or when medium alone was irradiated. Furthermore, co-cultivation with irradiated cells had no significant effect on the spontaneous mutagenic yield of non-irradiated cells collected from the other half of the double-mylar dishes. These results suggested that irradiated cells released certain cytotoxic factor(s) into the culture medium that killed the non-irradiated cells. However, such factor(s) had little effect on mutation induction. Our results suggest that different bystander end points may involve different mechanisms with different cell types.

Animals↗
PubMed2002

Saturated absorption spectroscopy of Xe using a GaAs semiconductor laser.

Doppler-free absorption spectrum from 5P(5)6S to 5P(5)6P transitions of Xe in a hollow cathode discharge was measured in the wavelength region from 810 to 910 mn. The saturated dip signals detected by a frequency modulated probe beam were doubly AM-modulated by a pump beam chopped using a conventional mechanical chopper. The Doppler background was greatly reduced by detection using a second lock in amplifier synchronous to the chopping signal. The isotope shifts of even mass (136-128)Xe in natural abundance were resolved for the five transitions from the metastable states of J = 2 and 0, while in the transitions from the J = 1 states were partially resolved. The nuclear magnetic and quadrupole hyperfine coupling constants of 131Xe and 129Xe determined are listed with those reported previously. The specific mass shifts and the field shifts were estimated using the relation given by King's diagram and compared with those obtained from the changes in the mean square-radii of the nuclear charge distribution.

Arsenic↗