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Biomedical subjects

R Suzuki

Publications and source records attributed to R Suzuki.

At least 145 records · Page 8Linked to original sources
PubMed2000

Enlargement of the receptive field size to low intensity mechanical stimulation in the rat spinal nerve ligation model of neuropathy.

One characteristic of plasticity after peripheral tissue or nerve damage is receptive field reorganization, and enlargement of receptive field size has been suggested to occur in certain models of neuropathic pain. The aim of the present study was to explore whether enlargement of neuronal receptive fields could contribute to the mechanical allodynia found on the ipsilateral paw in the spinal nerve ligation model of neuropathy. After ligation of L(5)-L(6) spinal nerves, all rats developed behavioral signs of mechanical allodynia, while the sham-operated control group displayed no such changes. The characteristics of the evoked responses of the neurones recorded in the dorsal horn of the rats were similar between the spinal nerve ligation, the sham operated control group, and the nonoperated control group, except for spontaneous activity, which was significantly increased in the spinal nerve ligation group. The mean size of the receptive field on the ipsilateral hindpaw, mapped using low-intensity stimulation with 9-g von Frey hair, was significantly increased in the spinal nerve ligation group, as compared to the sham-operated group. No significant difference was seen with 15- or 75-g von Frey hairs. The distribution of the receptive fields over the plantar surface of the paw was similar between the study groups. The enlargement of receptive field for non-noxious touch could be an indication of central sensitization in this model.

Animals↗
PubMed2000

Twisted plywood structure of an alternating lamellar pattern in cellular cementum of human teeth.

Human cellular cementum was examined by scanning electron microscopy to elucidate the manner of the alternate lamellar pattern forming the cellular cementum. Specimens were demineralized, trimmed with a freezing microtome, and treated by NaOH-maceration. This procedure was chosen to avoid artifacts in the fibril arrangement, and to study the fibrous architecture in detail. For comparison, non-demineralized, polished and HCl-etched specimens were also prepared. In the NaOH-macerated specimens, the lamellar pattern of the cellular cementum conformed to the twisted plywood principle of bone lamellation with a periodic rotation of matrix fibrils resulting in an alternating lamellar pattern. In contrast, matrix fibrils were irregularly arranged without indication of rotation of matrix fibrils in the polished and etched specimens. Our results suggest that polishing and etching procedures cause damage to fibrils and fibril arrangement.

Bone Demineralization Technique↗
PubMed2000

p21 and parathyroid hormone-related peptide in the growth plate.

It is essential for terminal chondrocytes to die before the conversion of calcified cartilage to bone. We have previously demonstrated that apoptosis occurred in the terminal hypertrophic chondrocyte of the growth plate. However, the essential mechanism by which the differentiation of chondrocytes is regulated has not yet been characterized. The purpose of this study was to investigate the mechanism for regulating chondrocyte differentiation. We focused on PTHrP and p21 which regulated the differentiation of chondrocytes and investigated how these factors interacted with each other in chondrocyte differentiation in the growth plate. PTHrP was strongly positive on immunostaining at the interface between the proliferating and the upper zone of the hypertrophic chondrocytes, whereas p21 was negative. On the other hand, p21 was positive in the lower zone of hypertrophic chondrocytes. Furthermore, PTHrP up-regulated the cell proliferation and down-regulated the expression of the p21 messengers in SW-1353 chondrosarcoma cells. These findings indicated that PTHrP might be a negative regulator for p21 in the differentiation of chondrocytes.

Animals↗
PubMed2000

Loss of regulation of circulating 1,25-dihydroxyvitamin D with paradoxically decreased serum phosphate levels in individuals with recurrent kidney stones.

A low serum phosphate concentration is characteristic in individuals in whom kidney stones form, this being related to serum 1,25-dihydroxyvitamin D, parathyroid hormone and urinary phosphate excretion. In order to determine whether these parameters are related to recurrence of stone formation, they were analyzed in single and recurrent stone formers as well as controls. An inverse correlation between serum levels of phosphate and 1,25-dihydroxyvitamin D was observed in control subjects, indicating that a drop in serum phosphate results in upregulated circulating 1,25-dihydroxyvitamin D level in controls. While the circulating low phosphate level upregulated the 1,25-dihydroxyvitamin D level in single stone formers, the elevation was less than expected from the drop in serum phosphate in recurrent stone formers. The results thus suggest that loss of upregulation of 1,25-dihydroxyvitamin D by serum levels of phosphate might be important for stone formation. The possibility of deregulation of 1,25-dihydroxyvitamin D to maintain physiological requirements in stone formers and prevent further nephrolithiasis therefore warrants attention.

Adult↗
PubMed2000

A new method for quantitative analysis of the mouse T-cell receptor V region repertoires: comparison of repertoires among strains.

We developed an adaptor ligation PCR-based microplate hybridization assay (MHA) to analyze the repertoires of mouse T-cell receptor (TCR) alpha- and beta-chain variable regions (TCRAV and TCRBV). RNA is transcribed to cDNA and an adaptor is ligated to the 5' end of the cDNA, which is then used as a template for PCR with an adaptor-specific 3' primer and a constant region-specific 5' primer. After hybridization of PCR products with TCRAV-and TCRBV-specific probes on the microplate, quantitative ELISA was carried out. The entire TCRAV or TCRBV repertoires could be analyzed using a single 96-well plate in triplicate and completed in less than 4 h. The assay results demonstrated the high level of specificity and reproducibility of this method. Furthermore, MHA results correlated well with those of fluorescence-activated cell sorting. This method may provide important information about various T-cell-associated diseases including autoimmune disease. The influence of the MHC on mouse TCR repertoires was next studied using the newly developed mouse TCRAV and TCRBV repertoire assay. The analysis in six strains showed no significant correlation between MHC haplotypes and TCRAV and TCRBV repertoires. However, large differences among strains was observed in TCRBV, but not in TCRAV repertoires. There were also large differences within same strain in TCRBV, but not in TCRAV repertoires, indicating differences in individuals independent of genetic factors. These data suggest that TCRBV repertoires are more susceptible than TCRAV repertoires not only to genetic factors but also some environmental factors.

Animals↗
PubMed2000

Variation in sic gene encoding complement-inhibiting protein of Streptococcus pyogenes serotype M1 isolates in Japan.

DNA sequencing of the gene encoding a complement-inhibiting protein of Streptococcus pyogenes (streptococcal inhibitor of complement, Sic) was carried out on 49 strains of S. pyogenes serotype M1. Those strains were obtained from patients and asymptomatic carriers in Japan from 1969 to 1997 and had various pulsed-field gel electrophoresis (PFGE) patterns. Four identical polymorphic sites were found in the strains with the same PFGE pattern (Ia), but not in those giving the pattern IIa. The other identical sites were found in the strains with the PFGE pattern IIa, but not in those with the pattern Ia. These observations suggest that each of PFGE patterns was restricted to a set of variation in the sic gene.

Alleles↗
PubMed2000

Some osteocytes released from their lacunae are embedded again in the bone and not engulfed by osteoclasts during bone remodeling.

It is generally accepted that osteocytes derive from osteoblasts that have secreted the bone around themselves. Osteocytes are cells embedded in the lacunae in the bone, and they are characteristically in contact with other cells by many slender cytoplasmic processes in canaliculi. During bone remodeling, many osteocytes in the bone are released from their lacunae by osteoclasts; however it remains unclear what happens to these released osteocytes. The cortical bone of the rat mandibular body was used in this study. Mandibles were fixed, decalcified, and then embedded in Epon 812. Specimens were sectioned in the frontal direction into serial 0.5 microm-thick semithin or 0.1 microm-thick ultrathin sections, and then examined by light or transmission electron microscopy. Cells that fitted in the osteocytic lacunae with canaliculi extending to the bone were identified as osteocytes in this study. Among many osteocytes released by osteoclasts in cutting cones, there were osteocytes half-released from their lacunae. These cells fitted in their lacunae with canaliculi extending to the bone and showed developed cell organelles in the cytoplasm. In closing cones, many osteocytes were situated in the bone away from cement lines; however, there were half-embedded osteocytes in the bone formed on cement lines. These cells fitted in their lacunae with canaliculi extending to the bone formed below cement lines and showed developed cell organelles in the cytoplasm. These results show that half-embedded osteocytes in closing cones derive from half-released osteocytes in cutting cones. Osteocytes encircled by osteoclasts were sometimes observed on one section, but serial sections showed that these osteocytes fitted in their remaining lacunae in the bone on other sections. This shows that not all osteocytes released from their lacunae are engulfed by osteoclasts. Consequently, the present results suggests that some osteocytes released from their lacunae are embedded again in the bone and not engulfed by osteoclasts during bone remodeling.

Animals↗
PubMed2000

Expression of SAG-1 of Toxoplasma gondii in transgenic mice.

We describe the expression of SAG-1 cDNA in B6C3F1 mice by microinjecting a 3.3 kbp DNA fragment, consisting of the cytomegalovirus enhancer-chicken beta-actin hybrid promoter and SAG-1 into the pronucleus of a fertilized egg at the one-cell stage. Offspring derived from this microinjection were analyzed for the integration and functional expression of the SAG-1 transgene. Steady-state expressions of both the mRNA for SAG-1 and SAG-1 protein product were detected in the brain, thymus, spleen and liver. Approximately 50% of F1 and F2 progeny inherited the SAG-1 transgene from SAG-1 transgenic mice in Mendelian fashion. These results indicated that SAG-1 transgenic lines were established. Transgenic mice harboring the SAG-1 gene will contribute a critical tool of defining the molecular mechanisms of SAG-1 in pathogenesis and host immune response.

3T3 Cells↗
PubMed2000

API2-MALT1 chimeric transcripts involved in mucosa-associated lymphoid tissue type lymphoma predict heterogeneous products.

Recent progress in molecular analysis of low-grade B cell lymphoma has revealed that API2 at 11q21 and a novel gene, MALT1 at 18q21, are involved in t(11;18)(q21;q21), a characteristic chromosome aberration for mucosa-associated lymphoid tissue (MALT) type lymphoma. We describe here the establishment of a reverse transcription-polymerase chain reaction (RT-PCR) assay that we used to analyze 22 cases of MALT lymphoma. All five cases that were shown to possess t(11;18)(q21;q21) showed the specific amplification of API2-MALT1 chimeric transcripts. Of the remaining 17 cases for which cytogenetic data were not available, three cases demonstrated the presence of fusion transcripts, indicating that a significant percentage of MALT lymphoma cases of the present series appeared to possess t(11;18). A single fragment was observed in each of these cases, but the size varied from case to case. Sequencing analysis revealed that there are two breakpoints in API2 and three in MALT1, and that all of the fusion transcripts are in-frame. On the basis of these results, four kinds of chimeric proteins can be predicted for the present series. Thus, the RT-PCR assay used here should serve as an effective molecular tool for understanding molecular pathogenesis and the clinical significance of API2-MALT1 for MALT lymphomas.

Adult↗
PubMed2000

Apoptosis and mitosis of parenchymal cells in the duct-ligated rat submandibular gland.

Apoptosis and proliferation of parenchymal cells during atrophy of rat submandibular gland induced by double duct ligation were investigated using immunohistochemistry for proliferating cell nuclear antigen (PCNA), terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end labelling (TUNEL) and transmission electron microscopy (TEM). At 2 and 3 days after ligation, increased PCNA positive cells and mitoses were seen in ducts; thereafter PCNA positive cells decreased in number. At 3 and 4 days, the acinar cell population rapidly decreased, with many remaining TUNEL positive acinar cells. During this period, TEM showed typical apoptotic acinar cells that were phagocytosed by adjacent acinar cells or intraepithelial macrophages. After 7 days, most acinar cells had disappeared, leaving prominent residual ducts; a few acinar cells remained, especially at the lobule periphery. Submandibular gland duct ligation thus induced marked depletion of acinar cell by apoptosis and a concurrent short-lived cycle of duct cell proliferation.

Animals↗
PubMed2000

Modulation of lung local immune responses by oral administration of a herbal medicine Sho-saiko-to.

Sho-saiko-to (SST), a Chinese/Japanese herbal medicine (Kampo medicine) widely used to treat chronic hepatitis in Japan, is known to modulate immune responses, and thus its immunomodulating activity may be responsible for its bi-directional effects on the lungs as therapeutic efficacy in various lung diseases and involvement in development of interstitial pneumonia. We administered SST to BALB/c mice orally and examined the lung tissue levels of pro/anti-inflammatory cytokines, interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), and the effects of SST on acute lung injury induced by instillation of lipopolysaccharide (LPS) or IL-1. Although SST had no effect on lung TNF-alpha or IL-1beta level, it increased IL-6. Investigation of active fractions of SST suggested that multiple ingredients were supposed to be responsible for IL-6-inducing activity. Liquiritigenin, a metabolite of liquiritin which is one of the major ingredients in SST enhanced in vitro IL-6 production in anti-CD3 monoclonal antibody (anti-CD3 mAb)-stimulated lung mononuclear cells in a cell-type specific and dose-dependent manner. SST suppressed LPS-induced lung injury at the later phase when lung leak was evident while being ineffective on initial neutrophil sequestration to the lung in these models. These findings suggest that SST modulates lung inflammation by regulating local immune response.

Administration, Oral↗
PubMed2000

New gamma-fluoromethotrexates modified in the pteridine ring: synthesis and in vitro immunosuppressive activity.

Our continuing program to develop new antifolate drugs useful against rheumatoid arthritis led us to modify the pteridine ring of gamma-fluoromethotrexate. Pyrrolopyrimidine derivatives 1e and 1t were found to exhibit potent suppressive effects on the responses of both T and B cells to mitogens, although tetrahydropyridopyrimidine derivatives 2e and 2t and quinazoline derivatives 3e, 3t and 4e showed very weak suppressive activities. Thus, conversion of the pteridine ring of gamma-fluoromethotrexate to a pyrrolopyrimidine ring led to a new potential antirheumatic compound.

Antirheumatic Agents↗
PubMed2000

Identification of RALDH-3, a novel retinaldehyde dehydrogenase, expressed in the ventral region of the retina.

In the developing retina, a retinoic acid (RA) gradient along the dorso-ventral axis is believed to be a prerequisite for the establishment of dorso-ventral asymmetry. This RA gradient is thought to result from the asymmetrical distribution of RA-generating aldehyde dehydrogenases along the dorso-ventral axis. Here, we identified a novel aldehyde dehydrogenase specifically expressed in the chick ventral retina, using restriction landmark cDNA scanning (RLCS). Since this molecule showed enzymatic activity to produce RA from retinaldehyde, we designated it retinaldehyde dehydrogenase 3 (RALDH-3). Structural similarity suggested that RALDH-3 is the orthologue of human aldehyde dehydrogenase 6. We also isolated RALDH-1 which is expressed in the chick dorsal retina and implicated in RA formation. Raldh-3 was preferentially expressed first in the surface ectoderm overlying the ventral portion of the prospective eye region and then in the ventral retina, earlier than Raldh-1 in chick and mouse embryos. High level expression of Raldh-3 was also observed in the nasal region. In addition, we found that Pax6 mutants are devoid of Raldh-3 expression. These results suggested that Raldh-3 is the key enzyme in the formation of an RA gradient along the dorso-ventral axis during the early eye development, and also in the development of the olfactory system.

Aldehyde Oxidoreductases↗
PubMed2000

Ultrastructural study of the root dentine surface resuming resorption on human deciduous teeth.

Resorption of deciduous teeth is not continuous, but alternates with periods of repair or rest. Dentine surfaces in periods of rest or repair resume resorption by odontoclasts during physiological root resorption of the deciduous teeth. However, no observations of such dentine surfaces have been shown. The characteristic feature of the dentine surfaces resuming resorption remains unknown. Tartrate-resistant acid phosphatase activity (TRAP) was detected on human deciduous teeth. The root resorbing surfaces on these teeth were photographed with a whole-mount light microscope, and the photographed areas were serially sectioned into 0.5 micron semithin sections. Preodontoclasts and odontoclasts were three-dimensionally reconstructed. On root resorbing surfaces, areas with small scattered TRAP-positive cells were observed among areas with many TRAP-positive resorbing odontoclasts and TRAP-negative areas. The sections showed that areas with small scattered TRAP-positive cells have features similar to those of TRAP-negative areas, but there were three kinds of characteristic TRAP-positive cells: preodontoclasts, odontoclasts forming small lacunae, and preodontoclasts, and odontoclasts with cytoplasmic processes extending to the dentine surface, which is covered with cells. These results suggest that the areas with small scattered TRAP-positive cells could be at the stage of resuming resorption, and show that the presence of preodontoclasts and odontoclasts with cytoplasmic processes extending to the covered dentine surface is a characteristic feature of the dentine surface at this stage.

Acid Phosphatase↗
PubMed2000

The structure of the cemento-dentinal junction in rat molars.

The cemento-dentinal junction was observed in the acellular and cellular cementum of rat molars by light and scanning electron microscopy. Scanning electron microscopy, combined with NaOH maceration, was used to observe the fibrous architecture directly in this region. Light microscopy revealed that the cemento-dentinal junction contains fewer collagen fibrils and more proteoglycans than the cementum and dentin. Scanning electron microscopy also showed that fibril intermingling is found only in some regions of the fibril-poor junction in macerated specimens. Prolonged maceration breaks down the cemento-dentinal junction in spite of the fibril intermingling. Only macerated specimens showed detachment here. It was established that NaOH maceration removes interfibrillar substances effectively, and does not damage the fibril structure or architecture. This suggests that the adhesion of proteoglycans is more important than fibril intermingling for preserving the cemento-dentinal attachment in the rat molar.

Animals↗
PubMed2000

The fibrillar structure of cementum and dentin at the cemento-dentinal junction in rat molars.

The cemento-dentinal junction was examined in demineralized rat molars with complete roots by scanning electron microscopy combined with NaOH maceration. It is established that the NaOH maceration removes interfibrillar substances and cells from connective tissues selectively without structural damage to collagen fibrils. The cementum was detached from the dentin by the maceration. The inner cementum surface facing the dentin and the outer dentin surface facing the cementum were observed. In acellular cementum, both the outer dentin surface and the inner cementum surface had a smooth appearance. There was little indication of fibrils intermingling between dentin and cementum. In contrast, both the inner cementum surface and outer dentin surface in cellular cementum had an uneven appearance due to the irregular arrangement of collagen fibrils. Point-like protrusions of fibril bundles were observed on both surfaces. Some (not all) of these point-like protrusions appeared to correspond to places of fibrillar intermingling between dentin and cementum.

Animals↗