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T Ishikawa

Publications and source records attributed to T Ishikawa.

At least 19 recordsLinked to original sources
PubMed2002

Deterministic retrieval of surface waviness by means of topography with coherent X-rays.

A surface profile retrieval technique from multiple X-ray total reflection images taken at various distances with full coherent illumination is demonstrated. An experiment was performed using the 1 km-long BL29XU beamline at the SPring-8 facility, Japan. Obtained results are compared with results from the optical metrology technique (Fizeau's interferometer). Good agreement between X-ray and optical methods proves the validity of the current approach. Meanwhile, the sensitivity of the X-ray technique is several times higher than that of the standard one. This technique is well suited to the needs of characterizing grazing optics for new-generation X-ray sources.

Journal Article↗
PubMed2002

Measurement of x-ray pulse widths by intensity interferometry.

The pulse width of hard undulator radiation (32 ps width, energy 14 keV) was determined by intensity interferometry. The method, in combination with various x-ray monochromators, enables measurements to be taken over a wide range of time frames, from ns to fs. The applicable target includes measurements of ultrafast x-ray pulse widths from fourth generation synchrotron light sources.

Calibration↗
PubMed2002

X-ray interferometry with multicrystal components using intensity correlation.

A theoretical relation between intensity correlation and interference was experimentally verified for the case of a large-separation skew-symmetric bicrystal interferometer. The intensity correlation was enhanced in the angular range where the interference fringes were clearly observed. An application investigating the interference condition of the interferometer is presented using the intensity-correlation technique.

Journal Article↗
PubMed2002

Non-Fermi-liquid spin dynamics in CeCoGe3-xSi(x) for x = 1.2 and 1.5.

Muon spin relaxation has been measured in CeCoGe3-xSi(x) at the magnetic/nonmagnetic boundary compositions of x = 1.2 and x = 1.5. Both the alloys are found to exhibit an ordered region and a disordered region. At x = 1.2, short-range magnetic ordering is observed below 0.86 K in the ordered region. The disordered region is paramagnetic and the muon spin-lattice relaxation rate lambda2 in this region displays non-Fermi-liquid (NFL) spin dynamics, i.e., the power law lambda2 proportional to T0.72 which shows the formation of Griffiths phase. lambda2 in the x = 1.5 alloy displays logarithmic (NFL) scaling below 1 K, in agreement with the theory of a T = 0 K magnetic transition.

Journal Article↗
PubMed2002

Analysis of the entire genomes of thirteen TT virus variants classifiable into the fourth and fifth genetic groups, isolated from viremic infants.

TT virus (TTV) DNA in serum samples obtained from 24 TTV-infected infants was amplified by polymerase chain reaction (PCR) with inverse primers derived from the untranslated region. The amplified PCR products were molecularly cloned; six clones each were analyzed. Seventy-six (53%) of the 144 TTV clones were classified into group 4 (YONBAN isolates), and 22 (15%) into a novel genetic group (group 5). The TTV clones in group 4 were classified into 9 types, and those in group 5 into 4 types. The entire nucleotide sequence of one representative clone each from the 13 types were determined; they comprised 3570-3770 nucleotides, and had poor homology to TTVs of groups 1-3 (TA278, PMV and SANBAN isolates). A phylogenetic tree based on the entire nucleotide sequence of open reading frame 1 confirmed the presence of five distinct clusters separated by a bootstrap value of 100%. Analysis of 13 TTV variants demonstrated preservation of the genomic organization and transcription profile in all TTV groups. TTV group 4 was detected in 54% or 72% of 7-to-12-month-old infants in Japan and China, respectively, which is comparable with that among adults in the respective country, indicating early and frequent acquisition of this TTV group in infancy.

Adult↗
PubMed2002

Ubiquitin-proteasome inhibitor enhances tumour necrosis factor-alpha-induced apoptosis in rat gastric epithelial cells.

BACKGROUND: Tumour necrosis factor (TNF-alpha) is a candidate factor for involvement in inflammation-mediated gastric mucosal injury. However, the effect of this cytokine on gastric epithelial cells has been poorly investigated. In the present study, we examined whether gastric epithelial cells are resistant to TNF-alpha-induced apoptosis, and whether this resistance is related to ubiquitin-proteasome-associated nuclear factor-kappaB (NF-kappaB) activation. METHODS: The rat gastric mucosal cell line RGM-1 was grown in DMEM/F12 medium supplemented with 10% FCS. Confluent monolayers of cells were pretreated or not for 60 min with PSI, a peptide aldehyde known to specifically inhibit the chymotrypsin-like activity of 26S proteasome. Cells were subsequently stimulated with recombinant rat TNF-alpha and their viability was determined by WST-1 assay. Apoptosis was confirmed by fluorescence microscopy after staining with Hoechst 33342 and propidium iodide, and DNA fragmentation was determined by flow cytometry using an APO-BRDU kit. IkappaB-alpha and the p65 binding subunit of NF-kappaB were detected by Western blots. RESULTS: Twenty-four-hour incubation with TNF-alpha alone or PSI alone did not affect the cell viability of RGM-1 cells. Pretreatment with PSI significantly enhanced the level of apoptosis induced by TNF-alpha. In RGM-1 cells treated with TNF-alpha, cytoplasmic IkappaB-alpha decreased and p65 in nuclear extracts increased markedly 30 min after cytokine stimulation. Pretreatment with PSI at 12.5 micromol/L blocked these TNF-alpha-induced changes. CONCLUSION: PSI enhances TNF-alpha-induced apoptosis through inhibition of NF-kappaB activation in RGM-1 cells.

Animals↗
PubMed2002

Undetectable levels of CSF hypocretin-1 (orexin-A) in two prepubertal boys with narcolepsy.

We report on two prepubertal narcoleptic boys with undetectable levels of hypocretin-1 (orexin-A) in their cerebrospinal fluid (CSF). The disease onset times were 6 and 8 years, and CSF was collected 8 and 20 months after the onset, respectively. The initial symptoms were excessive daytime sleepiness, cataplexy and disrupted nocturnal sleep. Both subjects are DRB1*1501 and DQB1*0602 positive. The measurement of CSF hypocretin-1 is valuable for the decisive diagnosis of narcolepsy and for selecting the type of treatment in prepubertal children. Our results suggest that a significant degree of hypocretin deficiency is already present at the disease onset.

Age Factors↗
PubMed2002

Intercomparison of whole-body counters by using a subject who had incorporated 137Cs into the body.

During the years 1996-2000, eight whole-body counting facilities (WBC) from Finland, Germany, Japan and Russia took part in an intercomparison using a resident of the Russian town of Novozybkov who had been seriously contaminated as a result of the Chernobyl accident. The subject R (adult male, height 172 cm average body mass 64 kg; and 137Cs body burden within the range of 1-15 kBq) was investigated in the participating institutions during his business trips. The experimentally obtained data for his 137Cs body burden were compared with the predicted values, which had been deduced from the measurements of subject R using the reference WBC (St Petersburg Institute of Radiation Hygiene) and from his effective half-time of 137Cs in the body (68 days). The obtained results did not deviate more than 20% from reference activities. Four facilities were able to quantity the 40K in the subject's body. The differences between reported values of potassium did not exceed 10%. For subject R, the average annual effective dose from radiocaesium was 0.25 mSv and it was 0.18 mSv from 40K in the years 1996/97. The reliability of using a subject with naturally incorporated artificial radionuclides ('walking standard') instead of an anthropomorphous phantom for calibration and intercomparison of whole-body counters in a large-scale nuclear accident is discussed.

Accidents↗
PubMed2002

New in-vivo calibration phantoms and their performance.

New in-vivo calibration phantoms (anthropometric phantoms) were developed to meet the needs for Japanese standard phantoms. Two important characteristics of these phantoms were that (1) they were designed using Japanese body size survey data, and (2) they were designed so that they can be adapted to various positions or geometries. The performance of these phantoms was tested with respect to body size, activity distribution along the axis, and counting efficiency. The actual dimensions of the anthropometric phantoms were compared with the survey data. Most items (31 of 47) indicated good agreement between the actual values and the survey data for the adult anthropometric phantom. The activity distribution for the anthropometric phantoms was compared with that for block phantoms that simulate a uniform activity distribution. The anthropometric phantoms have some gaps in their joints. The measurement results, however, indicated that these gaps did not significantly affect the overall accuracy of the measurements. Differences in counting efficiency between the block phantoms and the anthropometric phantoms for the same age were no more than 6%.

Adult↗
PubMed2002

Effects of N-alpha-methyl-histamine on human H(2) receptors expressed in CHO cells.

BACKGROUND: Production of N-alpha-methyl-histamine (NAMH), a histamine H(3) receptor (H3R) agonist, is reportedly promoted in Helicobacter pylori infected human gastric mucosa. NAMH was suggested to act directly on histamine H(2) receptors (H2Rs) in animals to stimulate acid secretion and to be a H2R agonist. As H2Rs and H3Rs play different roles in gastric acid secretion, it is very important to verify that NAMH is a H2R agonist. AIMS: To determine whether NAMH is a H2R agonist, as well as a H3R agonist. METHODS: We used a Chinese hamster ovary (CHO) cell line expressing human H2Rs (CHO-H2R) and control CHO cells. Expression of human H2Rs was confirmed by tiotidine binding. cAMP production in CHO-H2R and control cells in response to histamine or NAMH was measured. cAMP production in response to 10(-7) M NAMH was also measured in the presence or absence of the H2R antagonist famotidine and the H3R antagonist thioperamide. RESULTS: NAMH dose dependently stimulated cAMP productions in CHO-H2R cells. This production was inhibited by famotidine but not by thioperamide. Control CHO cells were unresponsive to either histamine or NAMH. In addition, the effect of NAMH, in terms of cAMP production in CHO-H2R cells, was more potent than that of histamine-that is, with a lower EC(50) concentration and higher maximal cAMP production. Both NAMH and histamine, but not R-alpha-methyl-histamine, effectively inhibited [(3)H] tiotidine binding to CHO-H2R cells. CONCLUSIONS: NAMH, which is produced in the gastric mucosa by H pylori, is a potent H2R agonist as well as a H3R agonist.

Animals↗
PubMed2002

[Delayed hydrothorax induced by a pericutaneous central venous catheter; report of a case].

We report herein a case of 53-year-old woman who suffered a hydrothorax induced by a central venous catheter which had been placed to facilitate total parenteral nutrition. The central venous catheter was inserted into the superior vena cava through the right subclavian vein. Chest X-ray film after insertion revealed proper position of the tip. She suddenly developed dyspnea and tachycardia due to right-sided hydrothorax 21 days after the insertion of the catheter. Chest X-ray showed massive pleural effusion in the right thorax, and the catheter tip inadvertently turned upward. The continuous mechanical force of the catheter tip against the SVC wall was considered to be the cause of this life-threatening delayed hydrothorax.

Catheterization, Central Venous↗
PubMed2001

Revisiting [3 + 3] route to 1,3-cyclohexanedione frameworks: hidden aspect of thermodynamically controlled enolates.

We have revisited the traditional consecutive Michael-Claisen [3 + 3] process (MC-[3 + 3]) promising the synthesis of a cyclohexane-1,3-dione derivatives from nonactivated simple ketones and enoates and evaluated its potential in modern organic synthesis. Twenty to thirty examples were demonstrated to be effective. The reactions exhibited remarkable regioselectivity with the Michael addition proceeding through nucleophilic attack by the more hindered site of the ketones without exception. The subsequent Claisen condensation resulted in the formation of carbon-carbon bonds between less hindered site of the ketones and acyl carbon of the enoates. The MC-[3 + 3] process described is useful for the synthesis of Taxol A-ring synthons in multigram quantities and for the synthesis of other six-membered carbocyclic compounds. A number of control experiments have been conducted to provide strong support for the mechanism of this MC-[3 + 3].

Journal Article↗
PubMed2001

Matrilysin stimulates DNA synthesis of cultured vascular endothelial cells and induces angiogenesis in vivo.

Matrilysin produced by human colon cancer cells may be involved in the progression and metastasis of cancer. In the present study, we investigated the association of matrilysin with angiogenesis. One microgram of recombinant matrilysin is confirmed to have increased [3H]-thymidine uptake in human umbilical vein endothelial cells. Then we used micro encapsulation and a mouse hemoglobin enzyme-linked immunosorbent assay system for in vivo quantitation of angiogenesis with BALB/c nu/nu athymic mice. Hundred micrograms of recombinant matrilysin induced angiogenesis to the same degree as 10 microg of basic fibroblast growth factor (bFGF). Angiogenesis was observed at the site implanted with human colon cancer WiDr cells in agarose micro beads. This was inhibited by subcutaneous injection of matrilysin-specific antisense oligonucleotide significantly by 53%. In conclusion, matrilysin may be associated with angiogenesis of human colon cancer through the direct proliferative action on endothelial cells.

Animals↗
PubMed2001

Right hepatic duct emptying into the cystic duct: report of a case.

BACKGROUND: Anomalous insertion of the right hepatic duct into the cystic duct is a rare anatomic variation. At this writing, only nine cases have been reported in the literature. In the patients presenting with this anomaly, the surgeon may accidentally transect the right hepatic duct during cholecystectomy. METHODS: We encountered a case of anomalous insertion of the right hepatic duct into the cystic duct, which was clearly demonstrated in the intraoperative cholangiography during laparoscopic cholecystectomy. RESULTS: As the half-cut point of the cystic duct happened to be on the gallbladder side of the cystic duct, cholecystectomy was accomplished laparoscopically. CONCLUSIONS: In anomalous insertion of the right hepatic duct into the cystic duct, hepatic duct transection could happen. Preoperative precise evaluation of the biliary duct, awareness of potential biliary variations, and identification of all anatomic structures before ligation and division were essential to prevent bile duct injury.

Aged↗