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Biomedical subjects

S Ban

Publications and source records attributed to S Ban.

At least 19 recordsLinked to original sources
PubMed2006

Competitive coexistence of superconductivity with antiferromagnetism in CeRhIn5.

We carried out ac magnetic susceptibility measurements under pressures P on the heavy fermion antiferromagnet CeRhIn5. We report bulk superconductivity (SC) at ambient pressure with a transition temperature Tc approximately or equal to 90 mK. The degraded SC in a powdered or polished sample was restored by annealing, showing that the SC state is sensitive to inhomogeneity. In a coexistence region of the SC with antiferromagnetism (AF), we find that Tc(P)(n)TN(P)(1-n) = const where TN indicates a Néel temperature and n denotes a ratio of electronic specific heat coefficients below and above TN, indicating the competition of the SC and the AF for states at the Fermi surface.

Journal Article↗
PubMed2005

Venepuncture is preferable to heel lance for blood sampling in term neonates.

BACKGROUND: The analgesic effect of oral sucrose in newborn infants undergoing painful procedures is generally accepted. For blood sampling, some studies have shown that venepuncture (VP) is less painful than heel lance (HL). OBJECTIVE: To determine the least painful and most effective method among blood sampling by VP or HL with or without sucrose. DESIGN: Randomised, double blind, placebo controlled trial. SUBJECTS: A total of 100 healthy, full term newborn infants being screened for inborn errors of metabolism were randomly allocated to one of four experimental groups (25 infants in each). Intervention and OUTCOME MEASURE: Seven specially trained nurses took turns to carry out blood sampling two minutes after administration of oral sucrose or water. Neonatal pain was assessed by the neonatal facial coding system (NFCS), as well as by crying. RESULTS: Without sucrose, the NFCS score was higher in the HL group than the VP group during blood sampling (median 58 v 23, p<0.001). Oral sucrose significantly reduced the score of the HL group (58 v 47, p<0.01) and also tended to reduce the score of the VP group (23 v 2, p<0.1). However, the HL with sucrose group still had a higher score than the VP without sucrose group (47 v 23, p<0.01). Crying and the total procedure time showed the same trends as the NFCS score. CONCLUSIONS: VP is less painful and more effective than HL for blood sampling in newborn infants. Although oral sucrose may have an additive analgesic effect, it is not necessarily required if VP is used for blood sampling.

Analgesics, Non-Narcotic↗
PubMed2005

Arrangement of high-energy neutron irradiation field and shielding experiment using 4 m concrete at KENS.

An irradiation field of high-energy neutrons produced in the forward direction from a thick tungsten target bombarded by 500 MeV protons was arranged at the KENS spallation neutron source facility. In this facility, shielding experiment was performed with an ordinary concrete shield of 4 m thickness assembled in the irradiation room, 2.5 m downstream from the target centre. Activation detectors of bismuth, aluminium, indium and gold were inserted into eight slots inside the shield and attenuations of neutron reaction rates were obtained by measurements of gamma-rays from the activation detectors. A MARS14 Monte Carlo simulation was also performed down to thermal energy, and comparisons between the calculations and measurements show agreements within a factor of 3. This neutron field is useful for studies of shielding, activation and radiation damage of materials for high-energy neutrons, and experimental data are useful to check the accuracies of the transmission and activation calculation codes.

Computer Simulation↗
PubMed2003

Expression of cyclooxygenase-2 in human hyperplastic gastric polyps.

Cyclooxygenase (COX)-2, an inducible isoform of prostaglandin synthetase, has been reported to be a key molecular target of colon cancer prevention by nonsteroidal anti-inflammatory drugs. Recently, it has been shown that Helicobacter pylori (H. pylori) could induce COX-2 together with inflammatory cytokines. Although human hyperplastic gastric polyps disappeared or decreased in number and size after eradication of H. pylori, the mechanisms in this step, especially the roles of COX-2, have not been yet elucidated. The aims of the present study were to examine the expression and localization of COX-2 in human hyperplastic gastric polyps immunohistochemically. Twelve specimens of human hyperplastic gastric polyps were obtained from endoscopic polypectomy. The expression of the COX-2 protein was immunohistochemically examined on formalin-fixed and paraffin-embedded tissue sections using an anti-COX-2 antibody and an avidin-biotin complex method. Cells expressing COX-2 were further immunohistochemically identified using a specific antibody against macrophages (CD68), and myofibroblasts (alpha-smooth muscle actin). Immunoreactive COX-2 was predominantly and strongly expressed in interstitial cells in the sub-epithelial layer of 10 hyperplastic polyps. Semi-quantitative analysis revealed a significant increase in COX-2 expression in interstitial cells. The staining pattern of macrophages and myofibroblasts partly corresponded to that observed for COX-2 in hyperplastic gastric polyps. These results suggest that COX-2 in mesenchymal cells induced by H. pylori may play an important role in the tumorigenesis of human hyperplastic gastric polyps.

Aged↗
PubMed2002

Chromosomal instability and radiosensitivity in myelodysplastic syndrome cells.

Myelodysplastic syndrome (MDS) is a clonal disorder of hematopoietic stem cells. To investigate whether chromosomal instability and/or DNA repair defects are involved in the development of MDS, we measured the micronucleus (MN) frequency in peripheral blood lymphocytes exposed to various doses of X-rays, using a cytokinesis-block micronucleus assay. The spontaneous MN frequencies in RAEB and RAEB-T patients were significantly higher than those in normal individuals (P = 0.0224, P = 0.008, respectively). Also, the X-ray-induced MN frequencies in RA/RARS, RAEB, and RAEB-T patients were significantly higher than those in normal individuals (P = 0.007, P = 0.003, P = 0.003, respectively, at 2 Gy). In order to elucidate the cause of unusual radiosensitivity, we measured the expression levels of nucleotide excision repair (NER) genes in peripheral blood mononuclear cells using a RT-PCR method. Reduction of NER gene expression was found in only one of 10 patients with low risk MDS, but in four of 11 patients with high risk MDS. Our data suggest that chromosomal instability and DNA repair defects may be involved in the pathophysiology of disease progression of MDS.

Adult↗
PubMed2002

Response of GafChromic MD-55 radiochromic film to synchrotron radiation.

Synchrotron radiation has been increasingly and extensively used for materials science, biology and medical research. For measurement of high dose from the low energy photons, tissue-equivalent dosemeters having linearity in the Gy region are required. In this study, energy and dose responses of double-layer Gafchromic film MD-55 were measured using 10-40 keV monoenergetic photons from synchrotron radiation. The result showed that the energy responses normalised at 60Co gamma rays were 0.58-0.59 at 10-20 keV, 0.66 at 30 keV and 0.72 at 40 keV in air. The linearity was confirmed to extend from 2 Gy to 100 Gy.

Gamma Rays↗
PubMed2002

Change in cytoskeletal phenotype and extracellular matrix production of muscularis mucosae during early invasive colorectal adenocarcinoma.

Bundles of eosinophilic spindle cells are often found in histological preparations of the stroma of invasive colorectal adenocarcinomas. To clarify their significance, especially during the early invasive phase, we histologically and immunohistochemically studied 33 submucosally invasive colorectal adenocarcinomas in terms of their relationship with the muscularis mucosa, their cytoskeletal phenotype, and their production of extracellular matrix (ECM). Histological continuity between bundles of eosinophilic spindle cells and the muscularis mucosa was identified in 19 out of 33 adenocarcinomas (57.6%). With respect to their cytoskeletal phenotypes, the expression of alpha-smooth muscle actin (alpha-SMA) did not differ between the muscularis mucosa and the eosinophilic spindle cells, whereas the expression of desmin and high molecular weight caldesmon (h-CD) of the eosinophilic spindle cells was decreased compared with that of the muscularis mucosa (p<0.05). Definitive type I procollagen (procollagen I) expression was identified, at least in part, in 16 out of 20 (80%) areas of the eosinophilic spindle cells that were continuous with the muscularis mucosa, and in 26 out of 29 (89.7%) areas of the eosinophilic spindle cells that were not. These findings suggest that the muscularis mucosa is the origin of the eosinophilic spindle cells, that they undergo phenotypic changes separately from the smooth muscle, that is, myofibroblastic changes, and that they contribute to carcinomatous stroma formation through production of an ECM component. These findings should be taken into consideration when determining the level of submucosal invasion by colorectal adenocarcinomas.

Actins↗
PubMed2001

Chromosomal instability in BRCA1- or BRCA2-defective human cancer cells detected by spontaneous micronucleus assay.

The BRCA1 and BRCA2 gene products are believed to play an important part in the onset and/or development of many sporadic mammary cancers. Recently, it has been reported that these two proteins contribute to a centrosome function which is believed to help maintain the integrity of the chromosome segregation process. This may mean a reduced level of the BRCA1 or BRCA2 protein in mammary cells will occasionally lead to nondisjunctional chromosomal loss or gain. We now report that spontaneous micronuclei arising from chromosome(s) which fail to be incorporated into the relevant daughter nuclei during mitosis tend to occur more frequently in BRCA1- or BRCA2-defective human cancer cells than in BRCA-positive cancer cells. Some cases of mammary carcinogenesis may therefore stem from the loss of integrity of chromosome segregation in cells which have a reduced capacity to express either BRCA1 or BRCA2.

BRCA2 Protein↗
PubMed2001

X-ray diffraction study on ordered, disordered and reconstituted intercellular lipid lamellar structure in stratum corneum.

From small angle X-ray diffraction for the stratum corneum of hairless mouse, it was obtained that in the normal stratum corneum, the 1st, 2nd and 3rd order diffraction peaks for the intercellular lipid lamellar structure appear at 13.8, 6.87 and 4.59 nm, respectively and also a broad hump for the 4th order reflection appears as observed by the previous researchers. In the damaged stratum corneum prepared by the treatment of sodium dodecyl sulfate, these small-angle diffraction peaks disappear and only the broad maxima remain around the 1st, 2nd and 3rd order diffraction peaks. These facts indicate that in the normal stratum the lamellar structure is ordered and in the damaged stratum corneum the lamellar structure is disordered. Furthermore, in the reconstituted lamellar structure obtained by immersing into the dilute suspension of the mixture of ceramide 3, cholesterol and stearic acid, the 1st, 2nd and 3rd order diffraction peaks reappear at 13.3, 6.67 and 4.44 nm, respectively. This fact indicates that the reorganization of the ordered lamellar structure takes place by adding the mixture to the damaged stratum corneum.

Animals↗
PubMed2001

Optimum treatment strategy for superficial esophageal cancer: endoscopic mucosal resection versus radical esophagectomy.

This study was designed to determine the optimum treatment for a superficial esophageal cancer involving the mucosal or submucosal layer of the esophagus. The subjects were 150 patients with a superficial esophageal cancer who underwent endoscopic mucosal resection (EMR) or esophagectomy in Kurume University Hospital from 1981 to 1997. The mortality and morbidity rates, survival rate, and recurrence rate were retrospectively compared for (1) 35 patients who underwent EMR and 37 patients who underwent esophagectomy for a mucosal esophageal cancer and (2) 45 patients who underwent extended radical esophagectomy and 33 patients who underwent less radical esophagectomy for a submucosal esophageal cancer. Among the 72 patients with a mucosal cancer, lymph node metastasis/recurrence was observed in only one (1%); whereas of 78 patients with a submucosal cancer it was observed in 30 (38%). Among patients with a mucosal cancer the mortality and morbidity rates after EMR were lower than for those after esophagectomy. The survival rate after EMR was the same as that after esophagectomy. No recurrence was observed after either treatment modality. Among the patients with a submucosal cancer, the survival rate was higher and the recurrence rate lower after extended radical esophagectomy; than after less radical esophagectomy; the mortality and morbidity rates after extended radical esophagectomy were the same as those after less radical esophagectomy. Multivariate analysis demonstrated that the treatment modality (EMR versus esophagectomy) did not influence the survival of patients with a mucosal esophageal cancer, whereas it strongly influenced the survival of patients with a submucosal esophageal cancer. We concluded that EMR was the mainstay of treatment for a mucosal esophageal cancer, and extended radical esophagectomy was the mainstay of treatment for a submucosal esophageal cancer.

Aged↗
PubMed2001

Establishment of a testicular carcinoma cell line producing alpha-fetoprotein.

OBJECTIVE: To characterize a newly established human testicular carcinoma cell line that continuously produces alpha-fetoprotein (AFP), and to investigate the effects of retinoic acid on AFP production. MATERIALS AND METHODS: A 24-year-old man underwent a radical orchidectomy for a right testicular tumour and was found to have two separate metastatic lesions in the lungs, both of which were removed surgically. The cancer cells were isolated from one of the tumours, which was composed of undifferentiated germ cells and produced AFP; the cells were cultured in a monolayer. This cell line was designated as KU-MT. RESULTS: The cell line was successfully maintained both in athymic nude mice and in culture. Histological examination showed that the xenografted tumours were composed of cells in the reticular, solid and glandular patterns of a yolk sac tumour, and of embryonal carcinoma cells. These cells immunostained positively for AFP. On electron microscopy, the extracellular deposition of a basement lamina-like substance, a typical feature of yolk sac tumour, was detected. The AFP production in mice correlated well with the tumour weight of the xenograft. The cultured KU-MT cells were oval to polygonal in morphology and grew exponentially, with a population doubling time of approximately 2 days. Chromosomal analysis showed a modal number of 57 with consistent structural abnormalities of +add(1)(p13), del(1)(q32), del(2)(q31), add(6) (q21), +add(9)(p22), add(11)(p15), and add(14)(p11). Reverse-transcription polymerase chain reaction analysis showed that the retinoic acid receptors (RAR)-alpha, RAR-gamma, and retinoid X receptor-alpha were present in the cells. The expression of AFP mRNA was up-regulated in response to all-trans-retinoic acid; treatment with this agent caused morphological changes and induced apoptosis in the cells. CONCLUSIONS: This newly established cell line provides a reproducible model system that should offer a good insight into the differentiation of testicular carcinoma.

Adult↗
PubMed2001

Renal fibroblast-like cells in Goodpasture syndrome rats.

BACKGROUND: The extent of renal fibrosis is the best predictor for functional outcomes in a variety of progressive renal diseases. Interstitial fibroblast-like cells (FbLCs) are presumably involved in the fibrotic process. However, such FbLCs have never been well characterized in the kidney. METHODS: We characterized renal FbLCs in the nephritic kidney (in which the number of FbLCs and extracellular matrix accumulation were significantly increased) with regards to their expression of phenotypic and functional markers using day 49 Goodpasture syndrome (GPS) rats. RESULTS: Within the renal cortical interstitium, there were a number of alpha-smooth muscle actin(+) (alpha-SMA(+)) FbLCs, negative for vimentin (VIM) and transforming growth factor-beta 1, and not equipped with well-developed rough endoplasmic reticulum and actin-stress fibers. All of these findings were incompatible with the typical features of granulation tissue alpha-SMA(+) myofibroblasts. On the other hand, FbLCs negative for alpha-SMA and VIM produced alpha1(I) procollagen in the nephritic kidney. CONCLUSION: A number of FbLC populations reside within the cortical interstitium of the kidney in GPS rats, each of which is likely to have developed independently in response to the local conditions of the nephritic kidney, contributing to renal fibrogenesis. Further studies are needed to clarify the key type of FbLC that orchestrates other members to produce renal fibrosis.

Actins↗
PubMed2001

Dose measurements in inhomogeneous bone/tissue and lung/tissue phantoms for angiography using synchrotron radiation.

For angiography using synchrotron radiation we measured the absorbed dose distribution in inhomogeneous phantoms with thin LiF:Mg, Cu, P, LiF:Mg, Ti thermoluminescent dosimeters (TLDs) in tissue and lung substitutes, and with Mg2SiO4:Tb TLDs in bone substitute for 33.32 keV monoenergetic photons from synchrotron radiation. The energy responses of the TLDs were measured in air for 10-40 keV monoenergetic photons. The values at 30 keV became smaller by 30% for LiF:Mg, Cu, P and larger by 22% for Mg2SiO4:Tb than the ratio of the mass energy absorption coefficients of the TLDs to that of air. These values were used to modify the calculated response of the TLDs in each phantom material. The absorbed dose distribution obtained was compared with that calculated using the Monte Carlo transport code EGS4 expanded to a low-energy region, and their agreement was confirmed taking linear polarization into account. In the bone substitute the dose increased by a factor of 3.9, while behind the bone the dose decreased drastically because of photon attenuation. In the lung substitute a slight dose difference from that in soft tissue was observed because of its different density. The LiF:Mg, Cu, P TLDs exhibited a better energy response, higher sensitivity and wider linear regions than did the other tissue-equivalent TLDs in the low-energy region.

Bone and Bones↗
PubMed2001

Radioactivity induced in a 2.5 GeV electron beam dump.

The saturation activity of residual nuclei was estimated based on measurements when 2.5 GeV electron beams were totally absorbed in thick Al, Fe, Cu and Pb. A calculation was also made for a beam dump from 0.1 to 10 GeV using the EGS4 and PICA95 Monte Carlo codes. Above 1 GeV, the activity was constant in units of MBq.W-1. The gamma ray dose rates from the targets were calculated using these data.

Aluminum↗
PubMed2001

Comparison of in-phantom dose distributions for coronary angiography using an x-ray machine and synchrotron radiation.

Coronary cineangiography using synchrotron radiation is anticipated, owing to the high intensity and availability of monoenergy. To investigate allowable dose levels in clinical application, absorbed dose distribution in a tissue substitute phantom for a conventional x-ray machine was measured with thermoluminescent dosimeters at the University of Tsukuba under the practical conditions used for digital angiography. The dose rate at a 0.5-cm depth was 0.145 Gy/s, and the dose per frame was 0.725 mGy for the irradiation period of 5 ms per frame. For synchrotron radiation, the dose distribution measurement was made at a 5-GeV AR (Accumulation Ring) of the High Energy Accelerator Research Organization, in which a polymethylmethacrylate (PMMA) phantom was irradiated with the strongest beam available at the facility, which was 33.32 keV, 5.2 x 6.2 cm2 beam. Using this beam, a 1-mm-diameter coronary artery has been visualized at 1% iodine concentration at the AR. Nonhomogeneous strength distribution in the beam was observed in the vertical direction. The maximum dose rate was 0.556 Gy/s, and it attenuated to 1/3000 at a 30-cm depth in the beam center. At the deep positions, the doses were influenced by the high harmonics, which was confirmed with an EGS4 Monte Carlo calculation. Outside the beam, beam contamination on both sides of the main beam affected the doses. For comparison to the x-ray machine, the measured dose was analytically converted to that needed for a 5.2 x 16 cm2 beam that is used for clinical application. The dose rate at 0.5-cm depth was found to be 0.215 Gy/s, which is 1.48 times larger than that for x-rays. Moreover, the attenuation rate in the phantom was significantly greater than that of the x-ray machine, because of the difference of the energy spectra between the x-rays and synchrotron radiation used.

Biophysical Phenomena↗
PubMed2001

Modification of electrochemically deposited apatite using supercritical water.

Supercritical water was used as a modification method of electrochemically deposited apatite on pure titanium. The apatites were coated on a commercially pure titanium plate using a hydrothermal-electrochemical method. A constant direct current at 12.5 mA/cm2 was loaded for 1 hr at 25, 60, 100, 150 and 200 degrees C in an electrolyte containing calcium and phosphate ions. The deposited apatite on the titanium substrate was stored in supercritical water at 450 degrees C under 45 MPa for 8 hr. With this treatment, the crystallinity of the apatites increased, sharp edges of the deposited apatites were rounded off, and the bonding strength of the titanium substrate to the deposited apatites significantly increased. On the other hand, weight loss in 0.01 N HCl decreased and the weight gain rate in a simulated body fluid also decreased with this treatment. It is suggested that the modification using supercritical water improved the mechanical strength of the deposited apatite, but worsened its bioactivity.

Apatites↗
PubMed2001

HUman MicroNucleus project: international database comparison for results with the cytokinesis-block micronucleus assay in human lymphocytes: I. Effect of laboratory protocol, scoring criteria, and host factors on the frequency of micronuclei.

Micronucleus (MN) expression in peripheral blood lymphocytes is well established as a standard method for monitoring chromosome damage in human populations. The first results of an analysis of pooled data from laboratories using the cytokinesis-block micronucleus (CBMN) assay and participating in the HUMN (HUman MicroNucleus project) international collaborative study are presented. The effects of laboratory protocol, scoring criteria, and host factors on baseline micronucleated binucleate cell (MNC) frequency are evaluated, and a reference range of "normal" values against which future studies may be compared is provided. Primary data from historical records were submitted by 25 laboratories distributed in 16 countries. This resulted in a database of nearly 7000 subjects. Potentially significant differences were present in the methods used by participating laboratories, such as in the type of culture medium, the concentration of cytochalasin-B, the percentage of fetal calf serum, and in the culture method. Differences in criteria for scoring micronuclei were also evident. The overall median MNC frequency in nonexposed (i.e., normal) subjects was 6.5 per thousand and the interquartile range was between 3 and 12 per thousand. An increase in MNC frequency with age was evident in all but two laboratories. The effect of gender, although not so evident in all databases, was also present, with females having a 19% higher level of MNC frequency (95% confidence interval: 14-24%). Statistical analyses were performed using random-effects models for correlated data. Our best model, which included exposure to genotoxic factors, host factors, methods, and scoring criteria, explained 75% of the total variance, with the largest contribution attributable to laboratory methods.

Adolescent↗