Biomedical subjects

I Nishimura

Publications and source records attributed to I Nishimura.

At least 37 records · Page 2Linked to original sources

PubMed1999

Synthesis and biological activities of NB-506 analogues: Effects of the positions of two hydroxyl groups at the indole rings.

In the course of a study of 6-N-amino-substituted analogues of NB-506 (1), a more potent anticancer drug, J-109,404 (2), in which the formyl group of NB-506 was replaced with a 1,3-dihydroxypropane group, was reported. A study of further modification in the positions of two hydroxyl groups at the indole rings of 2 resulted in the discovery of a 2,10-dihydroxy analogue, J-107,088 (3), which is a promising anticancer agent with a broader therapeutic window than J-109,404.

Animals↗

PubMed1999

Activation of neuronal caspase-3 by intracellular accumulation of wild-type Alzheimer amyloid precursor protein.

Forced overexpression of wild-type Alzheimer amyloid precursor protein (APP) causes postmitotic neurons to degenerate. Caspase-3 (CPP32) is a principal cell death protease involved in neuronal apoptosis during physiological development and under pathological conditions. Here, we investigated whether APP overexpression activates caspase-3 in human postmitotic neurons using adenovirus-mediated gene transfer. When a recombinant adenovirus vector expressing human wild-type APP695 was infected in vitro into neurally differentiated embryonal carcinoma NT2 cells, only postmitotic neurons underwent severe degeneration. Before neurodegeneration, full-length APP- and Abeta-immunoreactive peptides were accumulated in infected neurons, and caspase-3-like protease activity was markedly elevated. Western blot analysis revealed that activated caspase-3 subunits were generated in APP-accumulating neurons. Such neuronal caspase-3 activation was undetectable in NT2 neurons infected with beta-galactosidase-expressing adenovirus. Addition of the caspase-3 inhibitor acetyl-Asp-Glu-Val-Asp-aldehyde to the culture medium significantly reduced the severity of degeneration exhibited by APP-overexpressing neurons. Immunocytochemical analyses revealed that some APP-accumulating neurons contained activated caspase-3 subunits and exhibited the characteristics of apoptosis, such as chromatin condensation and DNA fragmentation. Activation of caspase-3 was also observed in vivo in rat hippocampal neurons infected with the APP-expressing adenovirus. These results suggest that wild-type APP is an intrinsic activator of caspase-3-mediated death machinery in postmitotic neurons.

Adenoviridae↗

PubMed1999

Structural variation of type XII collagen at its carboxyl-terminal NC1 domain generated by tissue-specific alternative splicing.

This paper reports the identification of two structural variations in the NC1 domain of rat and mouse type XII collagen. The long NC1 domain encoding 74 amino acids showed homology to chicken type XII and XIV collagens. The short NC1 domain was composed of 19 amino acids. Through genomic DNA analyses, two alternative exons were identified, each of which contained the variable NC1 sequence. With the amino-terminal NC3 splicing alternatives, we propose here a new descriptive nomenclature: types XIIA-1 and XIIB-1 which include a long NC1 sequence encoded by exon 1 (from the 3'-end), and types XIIA-2 and XIIB-2 which include a short NC1 sequence encoded by exon 2. Types XIIA-1 and XIIB-1, the predominant transcripts in 15-day old mouse embryos, showed decreased expression in 17-day old embryos when type XIIB-2 expression was sustained at constant levels. In adult mice, type XIIB-1 associates with ligament and tendon, whereas type XIIB-2 is expressed in various other tissues. The long NC1 domain contains an extended acidic region (pI = 3.4) followed by a terminal basic region (pI = 13.8). Because the short NC1 domain lacks these features, structural variations in the type XII collagen NC1 domain suggests different functional roles in a tissue-specific fashion.

Alternative Splicing↗

PubMed1999

Synthesis and biological activities of topoisomerase I inhibitors, 6-N-amino analogues of NB-506.

6-N-Amino analogues of NB-506 [6-N-formylamino-12,13-dihydro-1,11-dihydroxy-13-(beta-D-glucopyranosyl) -5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione] (3b) were synthesized and tested with respect to topoisomerase inhibition, cytotoxicity and anticancer effects. Among them, a 1,3-dihydroxypropane analogue (J-109,404, 5t) showed more than ten times more potent anticancer activity in MKN-45 human stomach cancer cells implanted in mice than NB-506.

Animals↗

PubMed1999

A short isoform of Col9a1 supports alveolar bone repair.

Bone wound created in intramembranous alveolar bone heals without the formation of cartilage precursor tissue. However, the expression of cartilage collagen mRNAs has been suggested. In this report, we examined the expression and the potential role of type IX collagen in bone restoration and remodeling. The sequence specific polymerase chain reaction demonstrated the exclusive expression of short transcriptional isoform of alpha1(IX) collagen (Col9a1) in alveolar bone wound healing, while the long isoform of Col9a1 transcript was absent. Type IX collagen was immunolocalized in the preliminary matrix organized in granulation tissue before trabecular bone formation in tooth extraction socket. In Col9a1-null mutant mice, there were considerable variations in alveolar bone wound healing with the absence of or abnormally organized trabecular bone. Occasionally, unusual apposition of cortical-bone-like layers in bone marrow space was observed. The Col9a1-null mice indicated no growth retardation, and their facial and long bones maintained the normal size and shape. However, the primary spongiosa region of adult Col9a1 mutant mice showed an abnormal trabecular bone structure associated with abnormal immunostaining with the hypertrophic cartilage specific type X collagen antibody. These data suggest that type IX collagen short transcriptional variant is involved in the restoration and remodeling processes of trabecular bone.

Alveolar Process↗

PubMed1999

Maintenance of regional histodifferentiation patterns and a spatially restricted expression of type X collagen in rat Meckel's cartilage explants in vitro.

The major, central portion of Meckel's cartilage undergoes fibrous transformation and contributes to the sphenomandibular ligament, whereas its distal end undergoes endochondral ossification ultimately giving rise to inner-ear ossicles. This regional histodifferentiation of Meckel's cartilage is known to be associated with the spatially restricted expression of type X collagen. The objective of this study was to determine if this unique histodifferentiation is regulated by local environmental factors or by a preprogrammed genetic mechanism. Meckel's cartilage, and condylar cartilage used for comparison, were isolated from 17-day-old rat embryos and from newborn rats, respectively. The cartilage explants were maintained in vitro for 50 days with or without supplementation with 10% fetal bovine serum. When the explants were cultured under serum-free conditions, well-regulated cartilage development was observed. Expression of type X collagen, a differentiation marker for hypertrophic cartilage, was restricted to the distal end of Meckel's cartilage, whereas type II and IX collagens were found uniformly along the entire explant. Matrix calcification was examined histochemically using alizarin red S staining and found to be restricted to the distal end of Meckel's cartilage. Both Meckel's and condylar cartilage cultured with 10% fetal bovine serum developed unregulated dysmorphogenesis. These data suggest that, although Meckel's cartilage has an intrinsic potential to differentiate to its terminal stage, external regulatory factors can significantly influence its normal development at the molecular level.

Animals↗

PubMed1999

Linearly and circularly polarized, 50 Hz magnetic fields did not alter intracellular calcium in rat immune cells.

This study was conducted to determine if exposure to 50 Hz magnetic field (MF) affects intracellular calcium ([Ca2+]i). We employed flow cytometry for real-time detection of possible changes in [Ca2+]i in a large number of cells. A solenoid coil for vertical MF exposure and a multiple-loop square-coil for horizontal MF were utilized. In the laboratory, background 50 Hz MF was less than 0.08 microT when all necessary equipment was powered. Rat thymocytes were exposed to 0.1 mT horizontal or vertical field, or to 0.14 mT circularly polarized field for 30 min; the effects of consecutive exposures to vertical and horizontal MFs, or vice versa, for 20 min each also were examined. In addition, intact thymocytes or lectin-activated thymocytes, splenocytes and peripheral blood lymphocytes were exposed to the 5 mT vertical field for 30 min. In all these experiments, no alteration in [Ca2+]i was evident. As a positive control, a calcium ionophore always was added to the medium following MF exposure to verify that the cells were capable of increasing [Ca2+]i and the system would record the response. The data indicate that MF exposure had no effect on [Ca2+]i under any of the conditions examined.

Animals↗

PubMed1998

Degeneration in vivo of rat hippocampal neurons by wild-type Alzheimer amyloid precursor protein overexpressed by adenovirus-mediated gene transfer.

In an attempt to elucidate the pathological implications of intracellular accumulation of the amyloid precursor protein (APP) in postmitotic neurons in vivo, we transferred APP695 cDNA into rat hippocampal neurons by using a replication-defective adenovirus vector. We first improved the efficiency of adenovirus-mediated gene transfer into neurons in vivo by using hypertonic mannitol. When a beta-galactosidase-expressing recombinant adenovirus suspended in 1 M mannitol was injected into a dorsal hippocampal region, a number of neurons in remote areas were positively stained, presumably owing to increased retrograde transport of the virus. When an APP695-expressing adenovirus was injected into the same site, part of the infected neurons in the hippocampal formation underwent severe degeneration in a few days, whereas astrocytes near the injection site showed no apparent degeneration. These degenerating neurons accumulated different epitopes of APP, and beta/A4 protein (Abeta)-immunoreactive materials were undetected in the extracellular space. A small number of degenerating neurons showed nuclear DNA fragmentation. Electron microscopic examinations demonstrated that degenerating neurons had shrunken perikarya along with synaptic abnormalities. Microglial cells/macrophages were often found in close proximity to degenerating neurons, and in some cases they phagocytosed these neurons. These results suggest that intracellular accumulation of wild-type APP695 causes a specific type of neuronal degeneration in vivo in the absence of extracellular Abeta deposition.

Adenoviridae↗

PubMed1998

Current perspectives in residual ridge remodeling and its clinical implications: a review.

PURPOSE: This article reviews the current understanding of the biology of tooth extraction wound healing and residual ridge remodeling. METHODS: The review of the biology of tooth extraction wound healing involves a discussion of the different cells populating the tooth extraction wound, the matrix formation, and the control of the repair process in the short-term. Defects in socket matrix formation or cellular activity will lead to stalled healing. The review of residual ridge remodeling describes the long-term result of tooth extraction and formation of residual ridges, in which the quantity of bone tissue continuously decreases. This may suggest that any potential regulatory factors of residual ridge resorption should have an adverse effect either on the increased catabolic activity by osteoclasts or on the decreased anabolic activity by osteoblasts. Both short-term tooth extraction healing and long-term residual ridge remodeling processes are interdependent. Furthermore, any potential genetic and environmental regulatory factors can affect the quality and quantity of bone by altering the gene expression events taking place in bone cells. RESULTS: The intent of this article was to review the current progresses of biologic research on residual ridge remodeling and to relate the changes at molecular, cellular, and tissue levels. The understanding of residual ridge remodeling may provide a sound scientific basis for improved restorative and therapeutic treatments of the edentulous population.

Alveolar Process↗

PubMed1998

Oxidative refolding of bovine pancreatic RNases A and B promoted by Asn-glycans.

It was previously revealed [Yamaguchi, H. and Uchida, M. (1996) J. Biochem. 120, 474-477] that both intra- and extramolecular high-mannose type Asn-glycans promote the renaturation of reductively denatured bovine pancreatic RNases A and B under oxidation conditions. To characterize the conformational changes of the polypeptides during the renaturation promoted by the intramolecular Asn-glycans, RNase B was compared with its nonglycosylated form, RNase A, as to the features of the regeneration from their reductively denatured species under Cu2+-catalyzed oxidation conditions. The refolding intermediates of RNase B, as compared with those of RNase A, seemed to contain much less impaired disulfide linkages. In agreement with this finding, the proper refolding of RNase B was much faster than that of RNase A, as revealed by the intrinsic fluorescence and 1-anilino-8-naphthalenesulfonate binding of the refolding intermediates. Such a promoting effect was also observed for extramolecular Asn-glycans of the complex as well as of the high-mannose type. In contrast, common mono-, oligo-, and polysaccharides, but not yeast mannan, exhibited much lower stimulatory effects on the oxidative refolding of RNase A.

Anilino Naphthalenesulfonates↗

PubMed1998

The expression of collagen I and XII mRNAs in Porphyromonas gingivalis-induced periodontitis in rats: the effect of doxycycline and chemically modified tetracycline.

Tissue remodeling is a dynamic state in which a balance is achieved between the proteolytic breakdown and synthesis of the extracellular matrix. Type I collagen is a major component of the gingival connective tissue (GCT) and the periodontal ligament (PDL) throughout development, while type XII collagen has been found in the mature forms of these tissues. The purpose of this study was to investigate the effects of periodontitis on the expression of type I and XII collagen and subsequently to investigate the effects of doxycycline (DOXY) and chemically modified non-antimicrobial tetracycline (CMT-1) on the expression of these molecules in this model. Adult barrier-raised male Sprague-Dawley rats were inoculated with Porphyromonas gingivalis obtained from humans to create the experimental periodontitis. The animals with the P. gingivalis-induced periodontitis were then split into the following groups: Group A served as infected untreated controls (PGI group); group B was treated with doxycycline (DOXY group); and group C was treated with chemically modified tetracycline-1 (CMT-1 group). Group D contained uninfected animals that served as uninfected controls (NIC group). The expression of type I and XII collagen mRNAs was examined by in situ hybridization in each group, with the co-expression of these molecules representing mature and functional gingival connective tissue. In the NIC group, cells hybridized with digoxygenine-labeled cDNA probes encoding rat alpha2(I) or alpha1(XII) collagens were found distributed uniformly throughout the periodontal connective tissue. The PGI group showed little hybridization in the areas of infection, while both the DOXY and CMT-1 groups showed co-expression of the alpha2(I) and alpha1(XII) probes in the GCT and coronal part of the PDL. This study demonstrates that doxycycline and CMT-1 moderate or reduce the inhibitory effects of periodontal infection on the expression of type I and type XII collagen mRNAs. These results suggest that doxycycline and a form of non-antimicrobial tetracycline, chemically modified tetracycline-1, can reduce periodontal destruction by reversing the inhibitory effect of periodontal infection on collagen synthesis.

Affinity Labels↗

PubMed1998

[Vitamin A, B1 and C status of elderly living alone].

A cross-sectional survey was performed to examine the vitamin A, B1 and C status and relating factors among the elderly aged over 65 years and living alone in the western parts of Hachioji, Tokyo. Of 159 subjects, 17 men and 81 women participated in this survey. A questionnaire and interview on the socioeconomic conditions, state of health and life-style and easting habits, and a medical examination were conducted and blood collected and analyzed. Vitamin A, B1 and C status was evaluated on the basis of serum vitamin A concentration, whole blood vitamin B1 concentration and serum vitamin C concentration, respectively. Most of the participants were those who were comparatively active in daily life. Thirty-three percent of the participants were assessed to be in poor vitamin B1 status, while 1% and 4% were assessed to be in poor vitamin A and C status, respectively. Significant correlations were found between whole blood vitamin B1 and serum vitamin A concentrations and between whole blood vitamin B1 and serum vitamin C concentrations. About 10% of the participants had blood vitamin B1 concentrations as below 35 ng/ml and at the same time, significantly lower serum vitamin A and C concentrations than others. Thus, inadequate nutrient intakes or inappropriate diet intakes were suggested as a cause. While good vitamin status was linked with use of vitamin preparations or vitamin supplements, lowered vitamin status was found to be closely associated with such dietary practices or behavior as dietary indifference to food combinations, a higher preference of rice as the staple food and having a reported difficulty in preparing meals.

Aged↗

PubMed1997

Cloning and sequencing of an alpha-glucosidase gene from Aspergillus niger and its expression in A. nidulans.

We have cloned an extracellular alpha-glucosidase gene from Aspergillus niger with oligonucleotide probes synthesized on the basis of the determined peptide sequences. The nucleotide sequence revealed an open reading frame of 985 amino acids split with three introns, and the deduced amino acid sequence was nearly identical to that of the alpha-glucosidase previously determined. The cloned gene was introduced into Aspergillus nidulans, and its expression in the transformants was shown to be regulated by the carbon sources in the medium, suggesting that a common regulatory expression system is shared by these two species as is the case of other starch-degrading enzymes of Aspergillus species.

Amino Acid Sequence↗

PubMed1997

Craniofacial abnormalities in mice carrying a dominant interference mutation in type X collagen.

Type X collagen is a short, non-fibril forming collagen restricted to hypertrophic cartilage, and has been hypothesized to play a role in endochondral ossification. The purpose of the study was to investigate the consequences resulting from the interference of type X collagen function on the growth and development of the craniofacial skeleton through analysis of transgenic mice with a dominant interference mutation for type X collagen. The craniofacial tissues of 21-day-old transgenic mice were examined by: cephalometric and radiographic densitometry analyses, conventional histology, and immunohistochemistry using antibodies specific for either endogenous mouse type X collagen or the transgene product. Genotypically positive mutant mice showed moderate but statistically significant craniofacial skeletal abnormalities, including the underdevelopment of the chondrocranium and mandible, but no cleft palate. Mean radiographic optical densities of the mutant condylar cartilage and the subchondylar areas were 32% less than the corresponding areas of normal mandibles, while mean radiographic optical density measured at the incisor tooth point remained constant. Histologically, transgene-positive mice revealed compressed hypertrophic cartilage zones and reduced trabeculae in both the mandibular condyle and the synchondroses of the chondrocranium. In the normal condyle, mouse type X collagen was localized by the monospecific antibody against a synthetic rat type X collagen NC1 peptide throughout the hypertrophic cartilage layer; in the mutant condyle, immunoreactivity to endogenous type X collagen was only seen sporadically. The truncated type X collagen transgene product, identified with the monoclonal antibody against an epitope within the chick type X collagen NC2 domain, persisted in the lower hypertrophic cartilage layer and the primary spongiosa, rather than being removed by subsequent endochondral ossification. The data suggested that the expression of the chick type X collagen transgene product was strongly associated with the craniofacial skeletal abnormalities that were distinct from other cartilage-related phenotypes.

Animals↗

PubMed1997

Effect of ovariectomy on the local residual ridge remodeling.

STATEMENT OF PROBLEM: Osteoporosis and edentulism are two disease processes that affect a large group of elderly people in the United States (24 and 25 million, respectively). These two diseases are independent of each other; however, they have several pathologic symptoms in common, such as reduction in bone mass. PURPOSE: The purpose of this study was to determine whether estrogen deficiency or its replacement therapy have any effect on the phenomenon of residual ridge remodeling. MATERIAL AND METHODS: Three animal groups were formed that consisted of six female Sprague-Dawley rats each. The two groups had ovariectomy and received either a vehicle solution or a daily dose (1.5 micrograms/day) of 17 beta-estradiol delivered through osmotic pumps. The control group underwent sham surgery and received a vehicle solution. Animals were pair fed throughout the experiment. Unilateral molar extraction was performed in the maxilla, which produced a suitable site for examination of histologic characteristics and molecular biologic analyses. At the 4-week postextraction period the bone remodeling activity was noted at the surface of the residual ridge in the control group. RESULTS: The ovariectomized group showed increased bone resorption activity, whereas the surface of the residual ridge alveolar bone of the ovariectomized and estrogen-treated group was covered by a layer of hyaline tissue. Poly(A)+ ribonucleic acid samples were isolated from the remodeling residual ridge tissues. Expression of alpha 2(I), alpha 1(II), alpha 1(IX), and alpha 2(X) collagens were examined by ribonucleic acid transfer dot blots. Compared with the control group, ovariectomized animals showed a reduction in bone formation with decreased expressions of type I and II collagens. In contrast, the estrogen-treatment group showed decreased formation of type I collagen with a much increased expression of type II collagen. Further examination of type II collagen formation on the ovariectomized and estrogen-treated group by means of in situ hybridization revealed the notable labeling by the type IIA collagen probe, which was associated with the surface tissue of the residual ridge alveolar bone. CONCLUSION: These findings suggest that estrogen deficiency and its replacement therapy seem to affect the activity of residual ridge bone remodeling at the molecular level.

Alveolar Process↗

PubMed1997

Clinical investigation of the ICD-10 subcategories for obsessive-compulsive disorder.

To examine the validity of ICD-10 subcategories for obsessive-compulsive disorder (OCD), the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) was applied to 53 OCD patients. The ratios of Y-BOCS compulsions subscore to obsessions subscore were calculated. The group with ratios around one consisted of patients diagnosed in three subcategories (F42.0, F42.1 and F42.2). This suggests that subjective subcategorization such as ICD-10 may be inadequate to differentiate between predominantly obsessive and compulsive patients compared with differentiation by quantitative assessment such as the Y-BOCS ratio. Thus, in selecting the appropriate therapeutic methods, we emphasize the usefulness of quantitative assessment in clinical settings.

Adolescent↗

PubMed1996

Cloning and expression of pyranose oxidase cDNA from Coriolus versicolor in Escherichia coli.

Complementary DNA encoding pyranose oxidase (PROD) was cloned and sequenced for the first time from Coriolus versicolor. The nucleotide sequence revealed an open reading frame encoding a polypeptide composed of 623 amino acid residues. Compared with the experimentally determined N-terminal sequence of the PROD from C. versicolor. 38 amino acids from the N-terminus of the protein appeared to be eliminated during protein maturation. The cDNA was successfully expressed under the control of lacUV5 promoter in Escherichia coli at 25 degrees C, which will be beneficial in industrial production.

Amino Acid Sequence↗

PubMed1996

Ceramics in dentistry: historical roots and current perspectives.

This article presents a brief history of dental ceramics and offers perspectives on recent research aimed at the further development of ceramics for clinical use, at their evaluation and selection, and very importantly, their clinical performance. Innovative ceramic materials and ceramics processing strategies that were introduced to restorative dentistry since the early 1980s are discussed. Notable research is highlighted regarding (1) wear of ceramics and opposing enamel, (2) polishability of porcelains, (3) influence of firing history on the thermal expansion of porcelains for metal ceramics, (4) machining and CAD/CAM as fabrication methods for clinical restorations, (5) fit of ceramic restorations, (6) clinical failure mechanisms of all-ceramic prostheses, (7) chemical and thermal strengthening of dental ceramics, (8) intraoral porcelain repair, and (9) criteria for selection of the various ceramics available. It is found that strong scientific and collaborative foundations exist for the continued understanding and improvement of dental ceramic systems.

Ceramics↗