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Yasuo Takeuchi

Publications and source records attributed to Yasuo Takeuchi.

33 records · Page 2Linked to original sources
PubMed2004

[Molecular cloning of fungal allergens and clinical applications of recombinant allergens in fungal allergy].

A large number of fungi are associated with allergic disorders. There are many problems in using non-standardized fungal extracts for diagnosis of fungal allergy. These problems can be solved by using genetically engineered recombinant allergens. At present, more than 70 fungal allergens have been cloned and sequenced, and the recombinant forms of several of these are commercially available. Measurement of IgE antibodies to these commercially available recombinant allergens could provide the tools useful for characterizing the differential sensitization pattern in relation to a particular disease and the allergenic cross-reactivity among fungi. Only a limited number of recombinant allergens are available at present, thus further studies on the molecular biology of fungal allergens are needed so that more recombinant allergens can be used in the clinical field.

Allergens↗
PubMed2003

Local irradiation enhances congenic donor pluripotent hematopoietic stem cell engraftment similarly in irradiated and nonirradiated sites.

Long-term multilineage chimerism is achieved in CD45 congenic mice receiving high bone marrow doses with or without mediastinal irradiation (MI). Increased donor chimerism results in MI-treated compared with nonirradiated animals, suggesting that MI makes "space" for engraftment of donor pluripotent hematopoietic stem cells (PHSCs). We have now examined whether space is systemic or whether increased engraftment of donor marrow in locally irradiated mice is confined to the irradiated bones. While increased donor chimerism was observed in irradiated bones compared with nonirradiated bones of MI-treated animals 4 weeks following bone marrow transplantation (BMT), these differences were minimal by 40 weeks. MI-treated chimeras contained more adoptively transferable donor PHSCs in the marrow of both irradiated and distant bones compared with non-MI-treated chimeras. Similar proportions of donor PHSCs were present in irradiated and nonirradiated bones of locally irradiated mice at both 4 and 40 weeks. Irradiated bones contained more donor short-term repopulating cells than distant bones at 4 weeks, but not 40 weeks, after BMT. Our study suggests that local proliferation of donor PHSCs in mice receiving local irradiation rapidly leads to a systemic increase in donor PHSC engraftment.

Adoptive Transfer↗
PubMed2003

Long-term results after Starr-Edwards mitral valve replacement in children aged 5 years or younger.

BACKGROUND: Mitral valve replacement with prosthetic valves in infants and children requires consideration of multiple variables. When we examined our late follow-up, the effect of the growth of the patient relative to the size of the prosthesis placed was the most important variable predicting late successful results. We reviewed our experience with mitral valve replacement using the Starr-Edwards ball valve in children aged 5 years or younger, focusing on the effect of valve prosthesis-patient mismatch on the long-term results in the growing patient. METHODS: From August 1974 to June 1986, 8 patients aged 5 years or younger underwent mitral valve replacements using the Starr-Edwards prosthesis size OM in 3 patients and 1M in 5 patients. Model 6320 was used in 1 patient and Model 6120 in the remaining 7 patients. RESULTS: Follow-up was 100% from 15 to 27 years (mean, 20 years). No valve-related complications of thromboembolism, anticoagulant-related hemorrhage, or prosthetic valve endocarditis were seen. All patients normally developed to adult size. The range of the valve area index of the 3 patients who received the smaller Starr-Edwards valve (size OM) was 0.97 to 1.24 cm2/m2. Although this size valve was adequate for patient growth to adolescence, in each case valve replacement with a larger valve was required. CONCLUSIONS: Our long-term review of Starr-Edwards ball valve mitral valve replacement in children aged 5 years or younger shows that the Starr-Edwards ball valve (Models 6320 [1 patient] and 6120 [7 patients]) showed excellent durability, no thromboembolism, and no anticoagulant-related complications. Size OM valves required replacement for hemodynamic reasons because of patient growth; larger size 1M valves remained hemodynamically satisfactory in spite of patient growth.

Adolescent↗
PubMed2003

Amelioration of diabetic nephropathy in SPARC-null mice.

SPARC (Secreted Protein, Acidic and Rich in Cysteine) is a matricellular protein that inhibits mesangial cell proliferation and also affects production of extracellular matrix (ECM) by regulating transforming growth factor-beta1 (TGF-beta1) and type I collagen in mesangial cells. This study is an investigation of the role of SPARC in streptozotocin (STZ)-induced diabetic nephropathy (DN) of 6-mo duration in wild type (WT) and SPARC-null mice. SPARC expression was evaluated by immunohistochemistry (IHC) and by in situ hybridization (ISH). Deposition of type I and IV collagen and laminin was evaluated by IHC, and TGF-beta 1 mRNA was assessed by ISH. Renal function studies revealed no significant difference in BUN between diabetic SPARC-null mice and diabetic WT mice, whereas a significant increase in albumin excretion was detected in diabetic WT relative to diabetic SPARC-null mice. Diabetic WT animals exhibited increased levels of SPARC mRNA and protein in glomerular epithelial cells and in interstitial cells, in comparison with nondiabetic WT mice. Neither SPARC mRNA nor protein was detected in SPARC-null mice. Morphometry revealed a significant increase in the percentage of the glomerular tufts occupied by ECM in diabetic WT compared with nondiabetic WT mice, although there was no difference in the mean glomerular tuft area among groups. In contrast, diabetic SPARC-null mice did not show a significant difference in the percentage of the glomerular tufts occupied by ECM relative to nondiabetic null mice. Tubulointerstitial fibrosis was ameliorated in diabetic SPARC-null mice compared with diabetic WT animals. Further characterization of diabetic SPARC-null mice revealed diminished glomerular deposition of type IV collagen and laminin, and diminished interstitial deposition of type I and type IV collagen correlated with decreases in TGF-beta 1 mRNA compared with WT diabetic mice. These observations suggest that SPARC contributes to glomerulosclerosis and tubulointerstitial damage in response to hyperglycemia through increasing TGF-beta 1 expression in this model of chronic DN.

Animals↗
PubMed2003

Application of terminal RFLP analysis to characterize oral bacterial flora in saliva of healthy subjects and patients with periodontitis.

Terminal restriction fragment-length polymorphism (T-RFLP) analysis was applied to characterize oral bacterial flora in saliva from 18 healthy subjects and 18 patients with periodontitis. The 16S rRNA genes (rDNAs) of oral bacteria and spirochaetes in saliva were amplified by PCR with a 6'carboxy-fluorescein (6-FAM)-labelled universal forward primer (27F) and a universal reverse primer (1492R) or the Spirochaeta-selective reverse primer. The 16S rDNAs were digested with restriction enzymes with 4 bp recognition sites (HhaI or MspI) and analysed by using an automated DNA sequencer. T-RFLP patterns were numerically analysed using a computer program. From analysis of the oral bacterial community, patterns derived from periodontally healthy subjects and patients with periodontitis were grouped into different clusters, though with some uncertainty. Samples from patients with periodontitis tended to cluster into their respective types (aggressive and chronic periodontitis), although this was not very clear. Analysis of spirochaetal community using T-RFLP showed that the patterns derived from patients with periodontitis were grouped more as compared with the analysis of the oral bacterial community. These results suggest that samples from patients with periodontitis contain an unexpected diversity. T-RFLP patterns of 16S rDNAs from saliva samples of two periodontally healthy subjects over a 5-week period showed host-specific relatively stable oral bacterial flora. Our study indicates that T-RFLP analysis is useful for the assessment of diversity of oral bacterial flora and rapid comparison of the community structure between subjects with and without periodontitis.

Adult↗
PubMed2003

High prevalence of Helicobacter pylori detected by PCR in the oral cavities of periodontitis patients.

BACKGROUND: Helicobacter pylori has been associated with the development of peptic ulcers and gastric cancer. Although it may be transmitted through the oral cavity, it is unknown whether the oral cavity acts as a permanent reservoir for this bacterium. The purpose of this study was to use nested polymerase chain reaction (PCR) to clarify whether the oral cavity acts as a reservoir for H. pylori. METHODS: The existence of H. pylori in the oral cavity was determined by nested PCR in 57 subjects and by culture method in 18 subjects. The presence of periodontopathic bacteria was also determined by 16S rRNA-based PCR method. RESULTS: Although H. pylori was rarely detected in the oral cavity by culture technique, it was frequently detected (35.1%) by nested PCR in the oral cavity, especially among periodontitis patients who had the bacterium in the gastrointestinal tract (46.4%). Among the subjects who harbored H. pylori in the stomach or duodenum, 41.2% of patients with periodontal pockets > or = 4 mm and 9.1% of subjects without pockets showed H. pylori in dental plaque, although a statistically significant difference was not observed. One patient who had periodontal pockets retained H. pylori in the oral cavity even after eradication of the bacterium from the stomach and duodenum. Most (8/10) of the patients who had H. pylori in dental plaque harbored Bacteroides forsythus in their oral cavities. CONCLUSION: Close attention should be given to periodontitis patients who harbor H. pylori in the oral cavity.

Aggregatibacter actinomycetemcomitans↗
PubMed2003

Prevalence of periodontopathic bacteria in aggressive periodontitis patients in a Japanese population.

BACKGROUND: Actinobacillus actinomycetemcomitans is considered a major etiologic agent of aggressive periodontitis. Other periodontopathic bacteria such as Porphyromonas gingivalis are also suspected of participating in aggressive periodontitis, although the evidence is controversial. The aim of the present study was to investigate the prevalence of periodontopathic bacteria and to clarify the microbiological features of aggressive periodontitis in Japanese patients. METHODS: Subgingival plaque was collected from 50 aggressive periodontitis (AgP) patients (localized 10, generalized 40). Samples from 35 generalized chronic periodontitis (CP) patients and 18 healthy subjects were examined as controls. Plaque samples were examined using culture and polymerase chain reaction (PCR) method. RESULTS: The prevalence of A. actinomycetemcomitans was relatively low in the localized (20%) and generalized (17.5%) AgP patients, with no significant difference observed in detection frequencies between AgP and the control groups (CP 8.6%, healthy 0%). On the other hand, Tannerella forsythensis (formerly Bacteroides forsythus), Campylobacter rectus, P. gingivalis, and Treponema denticola were frequently detected in localized as well as generalized aggressive periodontitis patients. The prevalence and proportion of P. gingivalis correlated with severity of clinical attachment loss in both localized and generalized aggressive periodontitis. CONCLUSIONS: T. forsythensis, C. rectus, P. gingivalis, and T. denticola were the predominant periodontopathic bacteria of aggressive periodontitis patients in Japan. Although A. actinomycetem- comitans was also detected in AgP patients, the prevalence of this bacterium was much lower than that of P. gingivalis.

Adolescent↗
PubMed2002

Rescue of beta-cell exhaustion by diazoxide after the development of diabetes mellitus in rats with streptozotocin-induced diabetes.

In this study, we attempted to demonstrate the possibility of rescuing beta-cell exhaustion by chronic intervention with an ATP-sensitive K(+) channel opener, diazoxide, which reduces the stress of insulin secretion, using rats with streptozotocin-induced diabetes. Three groups of male Wistar rats: (i) controls (n = 7), (ii) streptozotocin (30 mg/kg i.v.)-induced diabetic rats (n = 10), and (iii) streptozotocin-induced diabetic rats treated with diazoxide 30 mg/kg for 6 weeks (n = 10), were studied. Intraperitoneal 2-g glucose tolerance testing was performed every 2 weeks, and pancreatic tissue was examined after 6 weeks of treatment with diazoxide. The insulin concentration in diabetic rats treated with diazoxide was significantly higher than in diabetic rats without diazoxide (6.6 +/- 1.6 vs. 2.4 +/- 1.0 ng/ml, P < 0.05). The islet size and its cell number were reduced in diabetic rats compared to those in normal control rats. In normal control rats, 88% of pancreatic islet cells were insulin-positive, while 50% or less were positive in diabetic rats. However, islet size and its cell size appeared to be well preserved by diazoxide treatment. The average mass of islets in diazoxide-treated rats was significantly larger than that in untreated control animals. In addition, the degree of immunostaining for insulin was obviously higher in rats treated with diazoxide than in rats without diazoxide. Pancreatic proinsulin mRNA was restored in rats treated with diazoxide. The present study demonstrated that diazoxide protected from further damage the pancreatic beta-cells both functionally and morphologically in streptozotocin-induced diabetic rats by suppression of excessive insulin secretion. Our results strongly suggest the possibility that chronic intervention with an ATP-sensitive K(+) channel opener prevents the progress of deranged beta-cell function even after the development of diabetes mellitus.

Animals↗
PubMed2002

Mechanisms of transplant tolerance induction using costimulatory blockade.

The potential use of costimulation-blocking reagents to induce transplantation tolerance has recently created considerable excitement. Recent evidence has begun to delineate the mechanisms by which these powerful effects occur. It has become increasingly clear, firstly, that T cell costimulation is mediated by a delicate network of signaling pathways and, secondly, that interference with these systems can lead to numerous different tolerance mechanisms, including immune regulation, anergy and deletion.

Abatacept↗
PubMed2002

Expression of P-glycoprotein in rat hepatocarcinogenesis by diethylnitrosamine and the modulation by anticancer drugs.

P-glycoprotein (P-GP) is known to be a multidrug resistant 1 gene product and to exhibit resistance to a broad range of drugs including anticancer drugs such as epirubicin. Its overexpression is reported in human hepatocellular carcinoma and in adenomatous hyperplasia of the liver as well. In order to clarify the evolution of P-GP expression during hepatocarcinogenesis and its modulation by anticancer drugs, we performed an immunohistochemical study in male Wistar rat livers exposed to diethylnitrosamine (DEN) for 12 weeks. Some rats were pretreated with cisplatin or epirubicin 1 week prior to the exposure, and some rats were treated with them at the 10th week after the exposure. While there was no P-GP expression in the liver of the control, cisplatin, and epirubicin (DEN-free) rats, expression was confirmed in the hepatocytes of DEN-treated rats. The immunostaining of hyperplastic nodules was significantly more intense than in well-differentiated hepatocellular carcinomas, and no staining was observed in poorly-differentiated carcinomas. Markedly intense staining was observed in the early hyperplastic nodules of cisplatin-pretreated rats, as well as in epirubicin-pretreated rats. Plasma alpha-fetoprotein levels were markedly elevated in DEN-treated rats, while tumor necrosis factor-alpha levels were not. In conclusion, the results suggest that P-GP confers a protective effect against anticancer drugs and provides a great advantage to the initiated cells. Furthermore, in addition to epirubicin, cisplatin also promotes the induction of P-GP in the initiated cell.

Journal Article↗
PubMed2002

Aryl-aryl coupling reaction using a novel and highly active palladium reagent prepared from Pd(OAc)2, 1,3-bis[diphenylphosphino]propane (DPPP), and Bu3P.

A palladium-assisted coupling reaction of aryl triflate with arene was investigated, and a novel Pd reagent prepared from equimolar Pd(OAc)2, 1,3-Bis[diphenylphosphino]propane (DPPP), and Bu3P was developed. This method is useful for intramolecular biaryl coupling reactions, not only between aryl triflate and arene (triflate-amide), but also between aryl halide and arene (halo-amide).

Cyclization↗