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Y Yamada

Publications and source records attributed to Y Yamada.

At least 109 records · Page 6Linked to original sources
PubMed2002

Experimental and numerical study of the colour appearance of tattoo models.

The colour of tattooed skin has been predicted by a Monte Carlo method based on the optical coefficient spectra of the skin and tattoo dyes. Slices of pig skin, a tattoo phantom and skin phantoms with different thickness were prepared, and their reflectance and transmittance spectra were measured using an integrating sphere at wavelengths varying from 400nm to 700nm. The absorption and scattering coefficient spectra of skin phantoms, pig skins and the tattoo phantom were each calculated using the inverse Monte Carlo method. The skin phantoms and pig skins were overlaid on the tattoo phantom, and the reflectance spectra of the two-layered structures were measured. The reflectance spectra of the two-layered structures were calculated from the optical coefficient spectra using the Monte Carlo method. They agreed well with the measured spectra. The colour differences between the calculated and measured spectra were also evaluated by the L*a*b* colour space distances and showed good agreement, with 3.49 for the skin phantoms and 8.27 for the pig skins.

Animals↗
PubMed2002

Possible involvement of C-C chemokines in functional augmentation of adhesion molecules in asthmatic patients.

Adhesion molecules and C-C chemokines play an important role in the accumulation of eosinophils in allergic inflammation. In the present study, the expression and function of adhesion molecules on eosinophils from asthmatic patients and involvement of RANTES and eotaxin were examined. Eosinophils isolated by the CD16 negative selection method were stimulated with or without RANTES or eotaxin. Expression of b integrins on eosinophils and the functional adherence to recombinant soluble intercellular adhesion molecule-1 (r-sICAM-1)-coated plates were examined. Compared with normal subjects, eosinophils from asthmatic patients showed increased expression of b2 integrins and functional adherence to r-sICAM-1-coated plates. RANTES and eotaxin augmented the functional adherence of eosinophils without a significant upregulation of b2 integrins. Anti-b2 integrin antibody inhibited the augmentative effect on eosinophil adherence of RANTES and eotaxin. Pertussis toxin, wortmannin, and genistein inhibited chemokine-induced adherence. RANTES and eotaxin are closely related to eosinophil accumulation not only as chemotactic agents but also as augmentative agents for eosinophil adherence through involvement in functional eosinophil adherence to ICAM-1 by a possible qualitative change of b2 integrins. Pertussis toxin-sensitive G proteins, PI3 kinase, and tyrosine kinase are involved in signal transduction leading to activation of b2 integrins on eosinophil following stimulation with RANTES and eotaxin.

Adult↗
PubMed2002

Changes in cortical and cerebellar bcl-2 mRNA levels in the developing hydrocephalic rat (LEW-HYR) as measured by a real time quantified RT-PCR.

In order to evaluate the appearance of brain bcl-2 during development of the hydrocephalus, we measured levels of bcl-2 mRNA in the cortex and cerebellum of congenital hydrocephalic rats (LEW-HYR) at 1 and 2 weeks after birth using the quantified reverse transcriptase-polymerase chain reaction (RT-PCR) with TaqMan fluorogenic detection system. Normal and hydrocephalic siblings were killed 7 and 14 days after birth, and their cortices and cerebella were homogenized with the Isogen-chloroform mixtured solution. By means of the RT-PCR with genetic analyzer, the sequence of bcl-2 mRNA detected in the LEW-HYR was identified to be the same as that of the registered rat brain (L14680). During the development of normal siblings of LEW-HYR, the levels of bcl-2 mRNA detected in the cortex and cerebellum 7 days after birth were significantly higher than those seen on day 14 after birth. In the hydrocephalic rats, however, these levels were not significantly different during development. On days 7 and 14 after birth, the cortical levels of bcl-2 mRNA detected in the hydrocephalic rats were significantly higher than those in normal rats. In the cerebellum, these levels in the hydrocephalic rats were higher, but not significantly, than those of normal rats. These results indicate that the significant appearance of bcl-2 mRNA in the developing normal rat brain is related to sprouting and to the diminished number of neurons, whereas the significant increase of bcl-2 levels seen in the developing hydrocephalic rats is indicative of an excess activity of glutamate neurons in cerebral cortex and the protection of neurons from cell death induced by cerebral ventricular dilatation in the cortex after bcl-2 levels.

Aging↗
PubMed2002

ZD0473 pharmacokinetics in Japanese patients: a Phase I dose-escalation study.

ZD0473 is new platinum agent that was rationally designed to circumvent platinum resistance and reduce the potential for nephro-and neurotoxicity. This Phase I dose-escalating study investigated the pharmacokinetics, tolerability and efficacy of ZD0473 in Japanese patients with solid, refractory tumours. ZD0473 was administered as a 1-h intravenous infusion every 3 weeks. Nine patients received a total of 16 cycles of ZD0473 (median 1 cycle/patient), with 3 patients treated at each of 3 doses (60, 90, 120 mg/m2). The maximum plasma concentration (C(max)) and the area under the concentration-time curve to infinity (AUC(0-infinity)) increased with dose in a linear fashion for both total platinum and ZD0473 in plasma ultrafiltrate, suggesting that the pharmacokinetics of ZD0473 are linear. Haematological and non-haematological toxicities such as nausea and vomiting were mild (grade 1 or 2) and transient. No clinically significant nephro-, oto- or neurotoxicity was observed. Dose-limiting toxicity (DLT) was not observed and the maximum tolerated dose (MTD) was not identified. ZD0473 treatment showed evidence of disease stabilisation in 3 patients (33%). In conclusion, ZD0473 appears to have linear pharmacokinetics, and an acceptable tolerability profile at doses up to 120 mg/m2 in Japanese patients with refractory solid malignancies. Following evaluation of the data from all the Western trials, the ZD0473 development programme changed and this Japanese trial was stopped.

Adult↗
PubMed2002

Processing and mechanical properties of autogenous titanium implant materials.

Pure titanium and some of its alloys are currently considered as the most attractive metallic materials for biomedical applications due to their excellent mechanical properties, corrosion resistance, and biocompatibility. It has been demonstrated that titanium and titanium alloys are well accepted by human tissues as compared to other metals such as SUS316L stainless steel and Co-Cr-Mo type alloy. In the present study, highly porous titanium foams with porosities <or=80% are produced by using a novel powder metallurgical process, which includes the adding of the selected spacers into the starting powders. The optimal process parameters are investigated. The porous titanium foams are characterized by using optical microscopy and scanning electron microscopy. The distribution of the pore size is measured by quantitative image analyses. The mechanical properties are investigated by compressive tests. This open-cellular titanium foams, with the pore size of 200-500 microm are expected to be a very promising biomaterial candidates for bone implants because its porous structure permits the ingrowths of new-bone tissues and the transport of body fluids.

Journal Article↗
PubMed2002

Transient hematopoietic stem cell rescue using umbilical cord blood for a lethally irradiated nuclear accident victim.

We performed stem cell rescue and allogeneic skin transplantation on a lethally neutron-irradiated nuclear accident victim. HLA-DRB1 mismatched unrelated umbilical cord blood cells (2.08 x 10(7)/kg recipient body weight) were transplanted to an 8-10 Gy equivalent neutron-irradiated patient because of a lack of a suitable bone marrow or peripheral blood donor. Pre-transplant conditioning consisted of anti-thymocyte gamma-globulin alone, and GVHD prophylaxis was a combination of cyclosporine (CYA) and methylprednisolone (mPSL). Granulocyte colony-stimulating factor (G-CSF), erythropoietin (EPO), and thrombopoietin (TPO) were concurrently administered after transplantation. The absolute neutrophil count reached 0.5 x 10(9)/l on day 15, the reticulocyte count rose above 1% on day 23, and the platelet count was over 50 x 10(9)/l on day 27, respectively. Cytogenetic studies of blood and marrow showed donor/recipient mixed chimerism. Rapid autologous hematopoietic recovery was recognized after withdrawal of CYA and mPSL. Repeated pathological examinations of the skin revealed no evidence of acute GVHD. Eighty-two days after the irradiation, skin transplantation was performed to treat radiation burns. Almost 90% of the transplanted skin engrafted. Immunological examination after autologous hematopoietic recovery revealed an almost normal T cell count. However, immune functions were severely impaired. The patient died from infectious complication 210 days after the accident.

Adult↗
PubMed2002

Genetic differences in ethanol metabolizing enzymes and blood pressure in Japanese alcohol consumers.

Orientals have unique genetic polymorphisms in ethanol metabolizing enzymes, such as alcohol dehydrogenase-2 (ADH2), aldehyde dehydrogenase-2 (ALDH2) and cytochrome P450-2E1 (CYP2E1). Of the three studies conducted to clarify the influence of ALDH2 genotypes on sensitivity to the pressor effects of alcohol in Japanese, only one was suggested, though indirectly, higher sensitivity in drinkers having the genotype of inactive ALDH2. This discrepancy prompted us to determine ADH2, ALDH2 and CYP2E1 genotypes in the genomic DNA extracted from white blood cells of 855 healthy middle-aged Japanese men, and to analyse the associations with the alcohol-blood pressure (BP) relationship. No marked differences were found in the relationship among the genotypes of ALDH2, although the subjects with intact ALDH2 showed a slightly higher BP than those with inactive ALDH2 probably due to under-reporting of alcohol consumption in those with intact ALDH2 who could thus drink more. No significant influence of ADH2 genotypes was observed. A higher BP was noted in large volume alcohol consumers having c2/c2 genotype of CYP2E1. Multivariate regression analysis adjusting for the effects of age, body mass index and the volume of alcohol consumed, all of which are strong determinants of BP levels, showed only a marginal effect of c2 allele of CYP2E1 on diastolic BP elevations with increases in alcohol consumption. Thus it is concluded that the genetic polymorphisms in ethanol-metabolizing enzymes do not greatly influence the alcohol-BP relationship in Japanese men.

Adult↗
PubMed2002

Chemotherapy targeting methylthioadenosine phosphorylase (MTAP) deficiency in adult T cell leukemia (ATL).

Methylthioadenosine phosphorylase (MTAP) is an important enzyme used for the salvage of adenine and methionine. Cells lacking this enzyme are expected to be sensitive to purine synthesis inhibitors and/or methionine starvation. We reported previously that the MTAP gene is deleted in adult T cell leukemia (ATL) cells. In the present study, we expanded our series and used a real-time quantitative PCR assay for accurate diagnosis of the deletion and nine of 65 primary ATL samples (13.8%) were MTAP negative. In spite of this low incidence, ATL cells showed significantly higher sensitivity to L-alanosine, an inhibitor of de novo adenosine monophosphate (AMP) synthesis, than normal lymphocytes, suggesting that the MTAP gene is inactivated not only by deletion but also by other mechanisms. Indeed, a real-time quantitative RT-PCR assay disclosed that primary ATL cells had significantly lower MTAP mRNA expression than normal lymphocytes. Since MTAP-negative ATL cell lines also showed much higher sensitivity to L-alanosine than MTAP-positive ATL cell lines, we used these cell lines to investigate whether it is possible to develop selective therapy targeting MTAP deficiency. A substrate of MTAP, methylthioadenosine (MTA) or its substitutes rescued concanavalin A (Con A)-activated normal lymphocyte proliferation from L-alanosine toxicity. All the compounds except 5'-deoxyadenosine, however, also caused the undesirable rescue of MTAP-negative ATL cell lines. 5'-Deoxyadenosine had the desired ability to rescue hematopoietic progenitor cells without rescuing ATL cell lines. These results support the rationale for a chemotherapy regimen of L-alanosine combined with 5'-deoxyadenosine rescue in MTAP-deficient ATL.

Adenosine Monophosphate↗
PubMed2002

Prognostic factors of gastric cancer tumours of less than 2 cm in diameter: rationale for limited surgery.

BACKGROUND: A recent trend in the surgical treatment of patients with early gastric cancer in Japan has been to limit surgery to an extent that ensures complete cure and improvement in the patient's quality of life. If a gastric cancer tumour can be completely eradicated by laparoscopic surgery, the patient can be cured of cancer without major operative stress. A small gastric cancer tumour of less than 2 cm in diameter is an indication for laparoscopic surgery, but little is known about what protocol of surgical treatment is appropriate for this type of tumour. PATIENTS AND METHODS: The clinicopathological features of 150 patients with gastric cancer tumour of less than 2 cm in diameter were reviewed retrospectively from hospital records between 1985 and 1995. The results of retrospective analysis of clinicopathological data of 24 patients with advanced cancer were compared with those of 126 patients with early cancer. Univariate and multivariate analyses of patients with small gastric cancer tumours were performed to evaluate the prognostic significance of clinicopathological features. RESULTS: A significant difference was seen between the gross tumour appearances in the two groups; Borrmann type-4 tumours were more common in the advanced group. Lymph-node metastasis, lymphatic vessel invasion and vascular invasion were found more frequently in the advanced cancer group than in the early cancer group. Scirrhous type was more common in the advanced cancer group. In univariate analysis, unfavourable prognostic factors included deep cancer invasion, presence of lymph-node metastasis, lymphatic invasion and vascular invasion. Using Cox's proportional hazard regression model, only nodal involvement emerged as an independent statistically significant prognostic parameter associated with long-term survival. CONCLUSION: Laparoscopic surgery should not be performed on tumours that are Borrmann type in macroscopic appearance and scirrhous-type histologically. Lymph-node metastasis is an independent prognostic factor. We recommend laparoscopic surgery involving local resection of the stomach without lymphadenectomy for small, early gastric cancer tumours that satisfy the criteria mentioned above. However, the validity of this recommendation should be tested by a prospective randomized control trial in the future.

Aged↗
PubMed2002

Analysis of cDNAs from a mouse embryo tooth library: identification of novel genes during tooth development.

Signaling molecules, their receptors, and target genes from pathways and networks regulate the development of the tooth from initiation through cell differentiation. In order to identify genes involved in odontoblast and ameloblast differentiation, we constructed a cDNA library from E19.5 mouse molars. In this work, we report the partial cDNA sequences of 10 noncharacterized genes and we show cell expression of the transcripts on mouse embryo molars by in situ hybridization.

Animals↗
PubMed2002

Induction of micronuclei in a rat alveolar epithelial cell line by alpha particle irradiation.

Dose-response relationships for the induction of micronuclei were characterised in the rat alveolar epithelial cell line (SV40T2) exposed to either alpha particles(241Am: 3.2 MeV, 128 keV.micron-1, 0.093 Gy.min-1 at the cell-Mylar interface) or X rays (200 kVp, 1 Gy.min-1). The frequency of micronucleus formation was 1.6-3.0% for unirradiated subjects but increased for irradiated ones in a dose-dependent manner. A linear relationship between the dose and the micronucleus formation was observed until 1 Gy for alpha particles and 4 Gy for X rays. The linear slope for alpha particles was 28.5% per Gy and the relative biological effectiveness (RBE) was 4.3, as calculated from the slopes. The slope for alpha particles was dependent on the energy of the alpha particles. These results indicate that the micronucleus assay is available for biodosimetry of alpha particle irradiation in the rat alveolar epithelial cells, although consideration should be given to the range of the linearity and the LET of alpha particles.

Alpha Particles↗
PubMed2002

Biological response of chondrocytes to hydrogels.

Primary bovine chondrocytes were encapsulated in alginate and alginate combined with cartilage matrix extract, Cartrigel, for the purpose of cartilage tissue engineering. The cell constructs were incubated in vitro and gene expression of cartilage-specific extracellular matrix molecules was quantitated and localized with in situ hybridization with a decrease in expression observed in the alginate-Cartrigel constructs. Further understanding of cell response to scaffolds will allow rational design and development of hydrogels for cartilage tissue engineering.

Alginates↗
PubMed2002

Localized lymphomatoid papulosis.

A 50-year-old Japanese male visited our clinic in April 1999 with a 2-year history of self-healing, reddish papules on his right palm. On examination, there were grouped erythematous papules, 2-4 mm in size, which formed a relatively well-circumscribed erythematous plaque. A biopsy specimen showed a wedge-shaped, dense dermal infiltrate consisting of variously sized mononuclear lymphoid cells mixed with few large CD30-positive cells and inflammatory cells, suggesting the diagnosis of regional lymphomatoid papulosis (LyP). Analysis of the T cell receptor gene revealed a polyclonal pattern on lesional skin. Only 5 cases of LyP presenting in a regional distribution have been reported previously. Although the etiology of localized LyP remains unknown, considering that 2 of 5 reported patients developed widespread lesions regional LyP may be the initial presentation of typical LyP.

Administration, Topical↗
PubMed2002

[An adult case of Bochdalek hernia without an obvious cause; report of a case].

A 72-year-old female was transported by ambulance to our department to undergo transthoracic surgery. She had previously undergone transabdominal surgery under a diagnosis of adult Bochdalek hernia, but the restoration was believed to have been incomplete. During the transthoracic procedure, a dorsolateral defect of the diaphragm was detected and reinforcement with a Gore-Tex patch was performed. The patient's postoperative course was uneventful. Adult Bochdalek hernia is rare, but it requires immediate surgical intervention. Although transabdominal surgery is generally considered the first line treatment approach to restore Bochdalek hernia, restoration of the diaphragm is occasionally difficult. On the other hand, a transthoracic approach is thought to be effective as it allows for observation of the lung and diaphragm, and easy closure of the diaphragmatic defect. As complete restoration through early surgical intervention is important, a transthoracic approach in conjunction with transabdominal surgery should be considered whenever necessary.

Aged↗
PubMed2002

Chemoprevention of large bowel carcinogenesis; the role of control of cell proliferation and significance of beta-catenin-accumulated crypts as a new biomarker.

Control of cell proliferation is important for cancer prevention since cell proliferation has essential roles in carcinogenesis in the processes of both initiation and promotion. In large bowel carcinogenesis, carcinogens produce hyperproliferation of cells in the target sites and the cell proliferation persists even after the cessation of carcinogen exposure. Chemopreventive agents principally control the increased cell proliferation when given in the initiation as well as post-initiation phases. Aberrant crypt foci (ACF) which appear soon after carcinogen exposure in large bowel carcinogenesis in rodents have been used as a reliable biomarker for screening of potential chemopreventive agents. Recently, our group demonstrated the presence of probable premalignant lesions with frequent beta-catenin gene mutations and accumulation of the corresponding protein in the colonic epithelium of rats given a large bowel carcinogen. Such early-appearing lesions lack the morphological appearance of ACF. Expression of these beta-catenin-accumulated crypts (BCAC) is markedly suppressed by a chemopreventive cyclooxygenase-2 inhibitor, celecoxib. BCAC are suggested to be more reliable biomarkers than ACF for screening effective chemopreventive agents for colorectal cancer and for investigating the mode of action of the agents.

Animals↗
PubMed2002

Microleakage of composite resin restoration in cavities prepared by Er:YAG laser irradiation in primary teeth.

AIM: The purposes of this study were to investigate the surface morphology of cavities prepared by Er:YAG laser irradiation and to compare the microleakage degree after composite resin restoration with etched bur cavities in primary teeth, in vitro. MATERIALS AND METHODS: On the buccal (facial) and lingual (palatal) surfaces of 25 primary teeth, a round cavity was prepared with the Er:YAG laser system and with a high-speed diamond bur, respectively. Five cavities from each group were investigated by scanning electron microscopy (SEM). The remaining cavities were filled with a composite resin and subjected to a microleakage test (0.6% rodamine B solution) under thermocycling. Only bur cavities were acid-etched before filling. Statistical analysis was performed using the Mann-Whitney's U test; a value of p < 0.01 was considered significant. RESULTS: SEM observation of the laser and etched bur cavities revealed an absence of a smear layer; enamel rods and opening of dentinal tubules were recognized. No statistically significant differences were noted between microleakage of composite resin restorations of the laser and the etched bur cavities. Crosscut sections of the cavities with no microleakage showed good adhesion between the restorative material and dental hard tissues; there was also no gap at the interface. DISCUSSION: The highly irregular surface or the removal of the debris-like smear layer after laser irradiation may facilitate good adhesion of composite resin with enamel or dentine, and these surfaces might play a major role in decreasing microleakage of laser cavities. CONCLUSION: It can be concluded that cavities prepared by Er:YAG laser are capable of decreasing microleakage of composite resin restorations in primary teeth, and the efficiency is similar to etched bur cavities.

Journal Article↗