Biomedical subjects

N Ikeda

Publications and source records attributed to N Ikeda.

At least 37 records · Page 2Linked to original sources

PubMed2001

"Devil's staircase"-type phase transition in NaV2O5 under high pressure.

The "devil's staircase"-type phase transition in the quarter-filled spin-ladder compound NaV2O5 has been discovered at low temperature and high pressure by synchrotron radiation x-ray diffraction. A large number of transitions are found to successively take place among higher-order commensurate phases with 2a x 2b x zc type superstructures. The observed temperature and pressure dependence of modulation wave number q(c), defined by 1/z, is well reproduced by the axial next nearest neighbor Ising model. The q(c) is suggested to reflect atomic displacements presumably coupled with charge ordering in this system.

Journal Article↗

PubMed2001

The association of K-ras gene mutation and vascular endothelial growth factor gene expression in pancreatic carcinoma.

BACKGROUND: Previously, the authors reported the role of the vascular endothelial growth factor (VEGF) as an angiogenic factor in 40 patients with pancreatic carcinoma. In this study, they investigated the mechanism underlying the regulation of VEGF gene expression and evaluated VEGF expression and K-ras gene status in 48 patients with pancreatic carcinoma. METHODS: The authors used quantitative reverse transcriptase-polymerase chain reaction analysis and direct sequencing techniques for a retrospective study of VEGF gene expression and K-ras gene status in tumor tissue samples from 48 patients with pancreatic carcinoma. Immunohistochemistry also was used to investigate VEGF protein expression. RESULTS: Thirty-one tumors (64.6%) were evaluated with high VEGF expression, and 17 tumors (35.4%) were evaluated with low VEGF expression. Of the 48 primary pancreatic tumors studied, 33 tumors (68.8%) contained mutations of the K-ras gene. There was a significant correlation between VEGF expression and K-ras status. Twenty-five of 33 tumors (75.8%) with mutant K-ras genes showed high VEGF expression, whereas only 6 of 15 tumors with the wild type K-ras (40.0%) showed high VEGF expression (P = 0.038). The mean (+/- standard error) VEGF conservation rate for the 33 tumors with mutant K-ras was 1.839 +/- 1.241, and that for the 15 tumors with wild type K-ras was 1.057 +/- 0.983 (P = 0.037). Furthermore, the median survival for patients with mutant K-ras was shorter than for those with wild type K-ras (10.6 months vs. 27.6 months, respectively; P = 0.026), whereas the median survival for patients with high VEGF expression was shorter compared with that for patients with low VEGF expression (9.5 months vs. 26.4 months, respectively; P = 0.002). Cox regression model analysis indicated that only the VEGF status was a significant factor for prognosis (P = 0.024). Other variables, i.e., K-ras status, histopathologic tumor grade, tumor status, lymph node status, metastatic status, gender, and age at surgery, were not significant. CONCLUSIONS: The results of this study suggest that K-ras oncogene mutation may be associated with VEGF expression and that patients with pancreatic carcinoma who have high VEGF expression are associated with a poor prognosis.

Biomarkers, Tumor↗

PubMed2001

Sensitive and simple determination of mannitol in human brain tissues by gas chromatography-mass spectrometry.

A simple, reliable and sensitive gas chromatographic-mass spectrometric method was devised to determine the level of mannitol in various human brain tissues obtained at autopsy. Mannitol was extracted with 10% trichloroacetic acid solution which effectively precipitated brain tissues. The supernatant was washed with tert.-butyl methyl ether to remove other organic compounds and to neutralize the aqueous solution. Mannitol was then derivatized with 1-butaneboronic acid and subjected to GC-MS. Erythritol was used as an internal standard. For quantitation, selected ion monitoring with m/z 127 and 253 for mannitol and m/z 127 for internal standard were used. Calibration curves were linear in concentration range from 0.2 to 20 microg/0.1 g and correlation coefficients exceeded 0.99. The lower detection limit of mannitol in distilled water was 1 ng/0.1 g. Mannitol was detected in control brain tissues, as a biological compound, at a level of 50 ng/0.1 g. The precision of this method was examined with use of two different concentrations, 2 and 20 microg/0.1 g, and the relative standard deviation ranged from 0.8 to 8.3%. We used this method to determine mannitol in brain tissues from an autopsied individual who had been clinically diagnosed as being brain dead. Cardiac arrest occurred 4 days later.

Autopsy↗

PubMed2001

Confined band gap in an air-bridge type of two-dimensional AlGaAs photonic crystal.

The transmittance spectrum for an air-bridge type of AlGaAs photonic crystal (PC) slabs successfully fabricated was measured. It is found that the observed spectrum is consistent with both the theoretical band structure and the calculated one. Moreover, the transmittance due to the modes below the light line is found to be almost 100%, indicating that the guided modes should exist. The respective stop bands are observed in the gamma-M direction for TM-like and TE-like modes, implying that a photonic band gap should exist for the TE-like guided modes. The present PC is very suited for controlling the radiation field.

Journal Article↗

PubMed2001

XANES study of charge ordering on the spin-Peierls phase transition of alpha'-NAV2O5.

alpha'-NaV2O5 transforms at Tc = 34K, and the origin of the phase transition seems to be caused by the charge order and spin-Peierls mechanism. However the experiments which reveal the existence of charge order are very little. We measured XANES of V atoms which relates to the valence of V. It was found that the valences of V atoms in NaV2O5 were V4.5+ in the high temperature phase by comparing pre-edge and XANES of NaV2O5 with that of LiV2O5 CaV2O5 and V2O5. The analysis of EXAFS also shows the environment of the V4.5+ state.

Journal Article↗

PubMed2001

Blood concentrations of tetracaine and its metabolite following spinal anesthesia.

Blood concentrations of tetracaine and its metabolite, p-butylaminobenzoic acid, were measured after spinal anesthesia with tetracaine which had been administered to patients under going orthopedic surgery. Tetracaine, an ester anesthetic, was given to 10 patients, the dose was 8-14mg, and blood samples were collected 1, 2 and 6h after the injection of tetracaine. We used gas chromatography/mass spectrometry for purposes of analysis. Tetracaine was not detected in any blood sample, but the metabolite was detected in each sample with the mean concentrations of 126.5, 97.9 and 43.3ng/ml at 1, 2 and 6h, respectively. This data will be useful in determination of the cause of death after spinal anesthesia with tetracaine.

4-Aminobenzoic Acid↗

PubMed2001

Frequency of BRCA1 and BRCA2 germline mutations in Japanese breast cancer families.

The purpose of this investigation is to study the frequency of BRCA1 and BRCA2 germline mutations in Japanese breast cancer families. Mutation analysis of BRCA1 and BRCA2 by SSCP was conducted on the 113 breast cancer patients (probands) with at least 1 breast cancer (site-specific breast cancer families, n = 101) or 1 ovarian cancer (breast/ovarian cancer families, n = 12) patient in their first-degree relatives. Fifteen deleterious mutations (13.3%), including 8 nonsense and 7 frameshift mutations, were identified in BRCA1, and 21 deleterious mutations (18.6%), including 8 nonsense, 12 frameshift and 1 splice-site mutations, were identified in BRCA2. In site-specific breast cancer families, mutation frequency of BRCA1 or BRCA2 was high in families with 3 or more breast cancer patients (36%, 9/25), early onset (40 < or = years old) breast cancer patients (38%, 19/50) or bilateral breast cancer patients (40%, 6/15). In breast/ovarian cancer families, mutations of BRCA1 (58.3%, n = 7), but not BRCA2 (0%, n = 0), were observed. BRCA1 codon 63 (TTA to TAA) nonsense mutation and BRCA2 frameshift mutation (5802 del AATT) were observed in 4 and 7 independent families, respectively. Haplotype analysis has suggested that carriers of each of these mutations have common ancestors. These results demonstrate that family profiles are important determinants of risk for carrying a BRCA1 or BRCA2 mutation and that cumulative frequency of BRCA1 and BRCA2 mutations in Japanese breast cancer families (31.9%) is within the range observed in Caucasian breast cancer families. Presence of Japanese founder mutations has also been suggested.

Adult↗

PubMed2001

Detection of breast cancer micrometastases in peripheral blood using immunomagnetic separation and immunocytochemistry.

BACKGROUND: Although there have been many reports on the immunocytochemical detection of bone marrow micrometastases in breast cancer patients, peripheral blood micrometastases (PBM) have rarely been studied by immunocytochemistry (ICC). METHODS: PBM in operable and metastatic breast cancer patients were studied using immunomagnetic separation of tumor cells followed by immunocytochemistry (IMS-ICC). RESULTS: PBM were not detected in any peripheral blood samples from 21 healthy women, six patients with benign disease, or in a 21 patients with primary operable breast cancer, of which there were 7 stage I (n=7), 9 stage II, 2 stage III, and 3 inflammatory tumors. On the other hand, PBM were detected in 8 of 29 patients with metastatic breast cancers (27.6%). The number of tumor cells per patient varied from 2 to 90 cancer cells (median: 8 cells). Positivity of PBM was not significantly associated with the first site of recurrence, number of involved organs, tumor marker status, performance status, or disease-free interval, but it was significantly (p<0.01) associated with progesterone receptor negativity. CONCLUSION: PBM are very rare in primary operable breast cancer patients but can be observed in a considerable number of metastatic breast cancer patients. The clinical significance of PBM still remains to be established.

Biomarkers, Tumor↗

PubMed2001

Forensic significance of concentrations of ethanol in brain tissues following induced acute subdural hemorrhage.

The concentrations of ethanol in peripheral blood, subdural hematomas and various regions of the brain were determined 1, 2, 4, and 6 h after the induction of a hemorrhage into a subdural space in the right temple of rabbits. The concentrations were compared to cases of intravenous administration of ethanol-free i.v. fluid. Concentrations of ethanol in the subdural hematomas gradually decreased to correspond to those in the peripheral blood. The influence of an intravenous infusion of ethanol-free i.v. fluid was not observed. Concentrations in the brain of the right temporal, parietal and frontal lobes were high and those in the right temporal lobe were maintained during the 6 h of our experiment. Therefore, to determine if a human victim was under the influence of ethanol at the time of injury, we recommend that brain concentrations of ethanol be determined. This is apparently the first study to confirm that the estimation of ethanol in the brain provides a more accurate determination of how much ethanol had been ingested.

Animals↗

PubMed2001

Location of lesions in multiple evanescent white dot syndrome and the cause of the hypofluorescent spots observed by indocyanine green angiography.

PURPOSE: To determine the location of the lesions in the retina of a patient with multiple evanescent white dot syndrome (MEWDS) and to resolve the conflict in the cause of the hypofluorescent spots observed in the late phase of indocyanine green angiography (ICGA). CASE REPORT: A 27-year-old woman presented with a unilateral enlarged blind spot and a central scotoma. Fundus examination of the left eye showed many round, indistinctly circumscribed white dots extending from the posterior pole toward the periphery. Fluorescein angiography demonstrated hyperfluorescence due to staining at the location of the white dots. Staining was also observed on the venous wall which was consistent with periphlebitis. The location of the scotomas corresponded with the hypofluorescent spots observed around the optic disc and in the macula in the late phase of ICGA. The scotomas disappeared with the resolution of the hypofluorescent spots, and the sites of other hypofluorescent spots were in accord with the sites of periphlebitis. Visual evoked cortical potentials disclosed no laterality, and the critical fusion frequency was reduced but normalized with the disappearance of the scotoma. CONCLUSION: The initial lesions of MEWDS occur in the retinal pigment epithelium and photoreceptor cells, but when MEWDS is complicated by periphlebitis, the inflammatory lesions extend to the inner layers of the retina. The inflammatory changes involve the choroid and all layers of the retina, which then block the weak background fluorescence in the later phase of ICGA and cause the hypofluorescent spots. The visual field defects are probably caused by retinal dysfunction due to the inflammatory changes.

Adult↗

PubMed2001

Immunohistochemical study of p53, c-erbB-2, and PCNA in barrett's esophagus with dysplasia and adenocarcinoma arising from experimental acid or alkaline reflux model.

PURPOSE: An immunohistochemical study of p53, c-erbB-2, and proliferating cell nuclear antigen (PCNA) in Barrett's esophagus with dysplasia and adenocarcinoma, arising from experimental acid or alkaline reflux, was performed in dogs. METHODS: Cardiectomy was performed in group A (n = 26) as an acid reflux model, and total gastrectomy was performed in group B (n = 24) as an alkaline reflux model. After surgery, the esophageal mucosa was observed and biopsied endoscopically every 3 months over a period of 6 years. Immunohistochemical staining of p53. c-erbB-2, and PCNA was performed, using biopsied specimens. RESULTS: In group A, Barrett's esophagus developed in 14 of the 26 dogs. Low-grade dysplasia occurred in 5 of the 26 dogs, and in 1 of these 5 dogs, it developed into high-grade dysplasia. In this animal, adenocarcinoma arose 63 months after the operation. In group B, Barrett's esophagus developed in 10 of the 24 dogs. Low-grade dysplasia was observed in 4 of the 24 dogs. In 1 of these 4 dogs, the dysplasia became high-grade and adenocarcinoma occurred 66 months after the operation. In group A, PCNA was positive in adenocarcinoma; the PCNA labeling index (LI) was 58. c-erbB-2 and p53 were negative in all animals in group A. In group B, PCNA was positive in Barrett's esophagus with high-grade dysplasia and adenocarcinoma; the PCNA LI was 77. p53 was positive in adenocarcinoma. c-erbB-2 was negative in adenocarcinoma. CONCLUSIONS; The results of this study provided evidence of the dysplasia-carcinoma sequence arising from alkaline reflux, as well as from acid reflux. To the best of our knowledge, this is the first report of the use of an alkaline reflux model and a 6-year study using dogs to observe the course of Barrett's esophagus.

Adenocarcinoma↗

PubMed2001

Hospital outbreak of MEN-1-derived extended spectrum beta-lactamase-producing Klebsiella pneumoniae.

An outbreak of Klebsiella pneumoniae resistant to broad spectrum cephalosporins occurred in a hospital in the Kinki area in Japan. During 18 months, from February 1998 to July 1999, 23 strains were isolated from 21 patients (10 with pneumonia, 4 with urinary tract infection, 1 with sepsis, 1 with vaginosis, 1 with a wound infection, and 1 with both pneumonia and sepsis; 3 patients showed noninfective colonization with K. pneumoniae) in seven wards, including the intensive care unit. MEN-1-derived gene was detected by polymerase chain reaction from the majority of the strains. Ninety-nine strains of K. pneumoniae were isolated during this period. The isolation rate of K. pneumoniae resistant to broad spectrum cephalosporins was 21%. We distinguished three clones by pulsed-field gel electrophoresis and randomly amplified polymorphic DNA analysis, and one of them was isolated from 18 patients. The presence of an R-plasmid of more than 160 kb was confirmed by plasmid analysis, but it was not possible to obtain transconjugants from all strains. This outbreak of K. pneumoniae was immediately confirmed by genetic analysis, and it was promptly ended by the infection control procedures. This is the first hospital outbreak of MEN-1-producing K. pneumoniae in Japan.

Aged↗

PubMed2001

Epidemiological studies of tobacco smoking and dependence in Japan.

In this study, we attempted to determine the prevalence of tobacco or nicotine dependence in current smokers in Japan and to assess the relationship between alcoholism and tobacco or nicotine dependence. The subjects consisted of 246 alcohol-dependent and 1,111 non-alcohol-dependent individuals. We used a questionnaire, consisting of items obtained from the World Health Organization's The ICD-10 Classification of Mental and Behavioural Disorders: Clinical Descriptions and Diagnostic Guidelines (ICD-10) and the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) criteria for tobacco or nicotine dependence. The prevalence of tobacco dependence diagnosed according to the ICD-10 criteria was 23.9% among all subjects. The prevalence of tobacco dependence diagnosed according to the ICD-10 criteria was higher in alcohol-dependent individuals (58.1%) than in nondrinkers or social drinkers (12.8%). Alcohol-dependent subjects consumed significantly more nicotine per day than did nondrinkers or social drinkers. The prevalence of nicotine physical dependence diagnosed by using DSM-IV criteria for nicotine withdrawal was 2.4% in alcohol-dependent individuals, whereas only 0.3% of nondrinkers or social drinkers exhibited nicotine physical dependence. These results indicate to us that the potential for nicotine physical dependence is not much stronger than that reported among current smokers.

Adult↗

PubMed2001

A two-level hamming network for high performance associative memory.

This paper presents an analysis of a two-level decoupled Hamming network, which is a high performance discrete-time/discrete-state associative memory model. The two-level Hamming memory generalizes the Hamming memory by providing for local Hamming distance computations in the first level and a voting mechanism in the second level. In this paper, we study the effect of system dimension, window size, and noise on the capacity and error correction capability of the two-level Hamming memory. Simulation results are given for both random images and human face images.

Algorithms↗

PubMed2001

Repeat liver resection for hepatocellular carcinoma.

BACKGROUND: Although hepatectomy has been accepted as a therapeutic option for the primary tumor of hepatocellular carcinoma (HCC), what role the second liver resection will play in the clinical care of patients with intrahepatic recurrence of HCC after the initial resection has not been well evaluated. STUDY DESIGN: In a retrospective review of the 6-year period between January 1991 and December 1996, records were examined of 94 patients who underwent curative liver resection for HCC. Of these, 57 patients had isolated recurrent disease to the liver; 12 of the 57 patients underwent repeat surgical resection and 45 patients received nonsurgical ablative therapy. Clinical data for these patients were reviewed for operative morbidity and mortality, survival, disease-free survival, and pattern of failure. RESULTS: There were no perioperative deaths during repeat liver resections for recurrent HCC. Operative morbidity in the second resection was comparable to the initial resection. The disease-free survival rate after the second hepatectomy was 31% at 2 years, significantly lower than that after initial hepatectomy (62%) (p = 0.009). The overall survival rate after the second hepatectomy was 90% at 2 years, in contrast to 70% after nonsurgical ablative treatment for recurrent HCC (p = 0.253). CONCLUSIONS: Although the second liver resection for recurrent HCC can be performed safely and may improve survival, the disease-free survival rate after such resection therapy is low. This likelihood of further recurrences encourages studies for the selection of patients who may benefit from repeat liver resection.

Aged↗

PubMed2001

Identification of reddish alcoholic beverages by GC/MS using aroma components as indicators.

A method to identify reddish alcoholic beverages used for dissolving stimulant drugs was devised using aroma components as indicators. Thirteen brands of beverages including red wines, blueberry liquors, raspberry liquors, strawberry liquor, a mixture of red wine and blueberry juice and a mixture of red wine and grape juice were examined. Aroma components in each sample were effectively concentrated with a porous polymer beads column (Porapak Q) and were analyzed by gas chromatography/mass spectrometry (GC/MS). Specific aroma components were detected in each beverage and reddish alcoholic beverages were successfully classified into five groups using five aroma components as indicators. The present method should prove to be useful in criminal investigations.

Journal Article↗

PubMed2001

Involvement of IL-10, an anti-inflammatory cytokine in murine liver injury induced by Concanavalin A.

A mechanism of liver injury such as, viral hepatitis or autoimmune hepatitis is considered to involve the impairment of hepatocytes mainly mediated by T-cell immunity, but the roles of a variety of cytokines involved in regulation remain unclarified. We investigated the involvement of various cytokines, particularly, interleukin-10 (IL-10) which is considered to be an anti-inflammatory cytokine, in a murine model of experimental liver injury induced by Concanavalin A (Con A). The model of liver injury was made by intravenous injection of Con A (0.5 &mgr;g) through the caudal vein in 6-week-old female BALB/c mice weighting 20 g. By collecting blood before and at 1, 3, 6, 12 and 24 h after the injection of Con A, alanine aminotransferase (ALT) levels were sequentially measured, and liver tissue was sampled to examine liver injury. Furthermore, TNF-alpha, IL-4 and IL-10 levels were sequentially determined by enzyme-linked immunosorbent assay (ELISA). Serum ALT significantly increased between 3 and 24 h after the Con A injection, and spotty necrosis was histologically observed, suggesting mild liver injury. TNF-alpha and IL-4 increased soon after the injection of Con A. IL-10 increased bimodally soon after and at 12 h after the Con A injection. After neutralizing antibodies (1 &mgr;g) to IL-10 were intraperitoneally injected into the same model at 6 h before Con A treatment, serum ALT levels and the histology of the liver were examined 12 h after the Con A injection. ALT was significantly higher in the group treated with anti-IL-10 antibody (130.7+/-33.5 IU per I) than in the non-treated group (56.5+/-3.5 IU per I) (P<0.05). Histological examination showed spotty necrosis in the group treated with anti-IL-10 antibody. These results suggest that IL-10 has inhibitory effect on liver injury in a murine model of Con A-induced experimental liver injury mediated by cellular immunity.

Journal Article↗

PubMed2001

Bone marrow micrometastases detected by RT-PCR for mammaglobin can be an alternative prognostic factor of breast cancer.

PURPOSE: To evaluate a new prognostic factor of breast cancer, bone marrow micrometastases which was detected by RT-PCR for mammaglobin, a sensitive molecular marker of breast cancer, was examined. MATERIALS AND METHODS: One hundred and eleven samples from stage I-III breast cancer patients were examined. Bone marrow micrometastases and clinicopathological parameters, which were age, tumor size, lymph node metastasis and status of the estrogen receptor, were evaluated for the prognostic factor by statistical analysis. RESULTS: Median follow-up time was 21.1 months. Thirty-three (29.7%) out of 111 samples were RT-PCR positive. Eight cases (24.2%) in this group showed recurrent lesions in the distant organs. Whereas six (7.7%) out of 78 RT-PCR negative patients had distant recurrences. In the premenoposal patients, and in the patients with axillary lymph node metastases, RT-PCR positive cases showed significantly higher distant recurrent rate. Bone marrow micrometastases, axillary nodal status, and estrogen receptor were independent prognostic factors for breast cancer by both univariate and multivariate analysis. CONCLUSIONS: Bone marrow micrometastases detected by RT-PCR for mammaglobin can be a useful predictive marker for early distant recurrence of breast cancer.

Adult↗