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Biomedical subjects

M Tokuda

Publications and source records attributed to M Tokuda.

At least 109 records · Page 6Linked to original sources
PubMed1996

Role of Porphyromonas gingivalis protease activity in colonization of oral surfaces.

Cysteine proteases, including Arg-gingipain of Porphyromonas gingivalis, have been implicated as important virulence factors in periodontal diseases. These enzymes are also involved in the hemagglutinating activity of the organisms. In order to determine the role of proteases in the colonization of the gingival margin, we have compared the attachment properties of P. gingivalis 381 with those of its Arg-gingipain-defective mutant, G-102. Interactions with gram-positive bacteria, human oral epithelial cells, extracellular matrix proteins, and type I collagen were evaluated. In all cases, mutant G-102 was deficient in attachment relative to the parental strain. The mutant's defects could be explained, in part, by the weak autoaggregation displayed by the mutant, which appeared to result from altered fimbrial expression. Both Western blot (immunoblot) and Northern (RNA) blot analyses indicated reduced expression of the major 43-kDa fimbrillin subunit in the mutant. These results suggest that Arg-gingipain may play both direct and indirect roles in the colonization of the gingival margin. In addition, fimbriae may play a direct role in interacting with some host surfaces.

Bacterial Adhesion↗
PubMed1996

Direct evidence of the production of IgA by tonsillar lymphocytes and the binding of IgA to the glomerular mesangium of IgA nephropathy patients.

Tonsils were obtained by tonsillectomy from a 33-year-old woman with IgA nephropathy. Hetero-hybridoma cells of human tonsillar B-lymphocytes with mouse myeloma cells (NS-1) were made, and cultured in HAT medium supplemented with 10% fetus bovine serum and hybridoma cloning factor. The culture medium was analyzed by Western blot analysis using anti-human IgA antibody, and both IgA1 and IgA2 were demonstrated to be produced. The specimens of the biopsied kidney tissue of IgA nephropathy were washed with 0.02 M citrate buffer (pH 3.2) to remove deposited IgA from glomerulus. The specimens were then incubated with the culture media of hybridoma cells, and immuno-fluorescence analysis using FITC-conjugated anti-human IgA antibody was performed. IgA deposit was efficiently removed by washing with citrate buffer and was recovered after incubation with the culture medium of hybridoma cells. Direct evidence of binding of IgA produced by tonsillar B-lymphocytes to the glomerular mesangium of IgA nephropathy was demonstrated.

Adult↗
PubMed1995

Developmental changes of cyclin dependent kinase 5 subcellular localization in the rat cerebellum.

Cyclin dependent kinase 5 (Cdk5) phosphorylates tau protein, a microtubule-associated protein, at pathological sites in vitro as well as in Alzheimer's disease brain. The enzyme is therefore regarded as an important candidate responsible for the progression of Alzheimer's disease. We and others have suggested that the enzyme has physiological roles in brain development and maturation. In this study, we investigated the exact distribution and developmental changes of the enzyme in cerebellum by immunohistochemistry and non-radioactive in situ hybridization. Immunohistochemistry demonstrated that Cdk5 was consistently expressed in the cerebellum at all developing stages. However, the subcellular localization of Cdk5 dramatically changed during maturation of the cerebellum. In the early neonatal stage, Cdk5 was strongly expressed in the cell bodies of neurones. With neuronal maturation Cdk5 immunoreactivity changed its subcellular localization from the cell body to axon. In terminally differentiated neurons, the immunoreactivity was only detected in the axon. These results suggest that subcellular localization of Cdk5 is strictly regulated and may play an important role in neuronal maturation.

Alzheimer Disease↗
PubMed1995

pp60c-src expression in rat spermatogenesis.

A fractionation of the membrane extract of rat testes revealed the existence of pp60c-src kinase activity. The expression of pp60c-src was examined in the developing rat testes. The immunecomplex kinase assay using a monoclonal antibody specific to pp60c-src (mAb327) showed that the expression of pp60c-src kinase activity increased during the development of rat testes and declined in the adult. The increase in pp60c-src kinase activity observed during the development of rat testes was accompanied with an increase in the amount of pp60c-src protein. The peak period in the increase of pp60c-src kinase activity well coincided with the timing, when the spermatogenesis by meiosis just began. The immunohistochemical staining of pp60c-src in rat testes demonstrated that pp60c-src is most abundantly expressed in the spermatids which are the spermatogenic cells in the post-meiotic phase of the spermatogenesis. These findings strongly suggest that pp60c-src is a developmentally regulated gene product which is involved in rat spermatogenesis.

Amino Acid Sequence↗
PubMed1995

Developmental alteration and neuron-specific expression of bone morphogenetic protein-6 (BMP-6) mRNA in rodent brain.

Bone morphogenetic proteins (BMPs) are a group of proteins which induce bone formation from mesenchymal cells. The existence of BMPs in the nervous system as well as in bone tissue has recently been reported. In this study, we show that BMP-6 is neuron-specific, and describe the temporal and spatial expression patterns of BMP-6 mRNA in the developing rat and gerbil brain. Northern blot analysis showed that the BMP-6 transcript level was specifically high from newborn to 3 weeks after birth compared with those in fetal and adult rats. In situ hybridization showed that most of the neurons possessed high levels of BMP-6 mRNA in the neonatal brain, while in the adult brain, BMP-6 mRNA level was significantly decreased in most of the neurons except those in hippocampus which retained high levels. Furthermore, to show that the BMP-6 expression was specific to neurons, we induced delayed neuronal cell death and compensative glial cell proliferation in the gerbil hippocampus by transient ischemia. Our findings collectively suggest that BMP-6 is neuron-specific and may play important roles in neuronal maturation and synapse formation.

Animals↗
PubMed1995

Morphological changes in the hippocampus in amygdaloid kindled mouse.

To clarify the origin and maintenance of epileptogenesis, morphological changes in the hippocampus of amygdaloid-kindled mice were analyzed at different stages of kindling. The granule cell size in dentate gyrus and the pyramidal cell size in CA1 were clearly decreased depending on seizure stage. The cell size in CA2 was increased and density in dentate gyrus and CA2 was reduced, significantly. The morphological changes in hippocampus associated with kindling must be closely related to the acquisition and the maintenance of epileptogenesis. The results support the hypothesis that seizure-induced damage of neurons may lead to formation of new synaptic connections that produce abnormal hyperexitability and result in seizures.

Amygdala↗
PubMed1995

Involvement of annexin-I in glucose-induced insulin secretion in rat pancreatic islets.

Annexin-I was demonstrated to specifically present in islets and not in exocrine tissues of the rat pancreas and to have a diffuse and homogeneous distribution in all islet cells in our previous study. In the present report, to clarify the functions of annexin-I in rat pancreatic islets, especially in beta-cells, we investigated the role of annexin-I in insulin secretion. Immunoelectron microscopic analysis of pancreatic beta-cells demonstrated that immunogold particles reactive to annexin-I were almost exclusively observed on most of the insulin-containing granules (approximately 90%) and less frequently located in cytosol and other organelles, such as the endoplasmic reticulum and mitochondria. The number of annexin-I gold particles located on insulin granules after oral glucose administration was significantly increased compared with that observed in fasted rats. Moreover, when the isolated islets were stimulated by a high concentration of glucose (20 mM), the phosphorylation of annexin-I was markedly enhanced, and it was synchronized to insulin secretion. This phosphorylation mainly occurred on serine residues. H-7 (100 microM), a potent inhibitor of protein kinase-C, inhibited the phosphorylation to about 90%. These findings suggest that annexin-I might be involved in the regulatory mechanism of glucose-induced insulin secretion in rat pancreatic islets via phosphorylation-dephosphorylation processes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

[A case of Felty's syndrome with marked thrombocytopenia and severe hypocomplementemia].

Felty's syndrome is diagnosed when a patient shows both splenomegaly and leukocytopenia of various degree during the course of rheumatoid arthritis (RA). The accompanying immunologic abnormalities (e.g., antinuclear antibody, antiplatelet antibody, and hypocomplementemia) also characterize Felty's syndrome, but some authors may regard these abnormalities as a transitional form into overlap syndrome [RA + systemic lupus erythematosus (SLE)]. Here we reported a female case of Felty's syndrome who showed marked thrombocytopenia and severe hypocomplementemia. Thrombocytopenia had been refractory against several forms of therapies including high-dose methylprednisolone. Simultaneously, she had various autoantibodies (i.e., antiplatelet antibody, positive Coombs' test, antithyroglobulin antibody, antimicrosome antibody and anti-RNP antibody). Although she did not fulfill the ARA diagnostic criteria for SLE, the degree of thrombocytopenia as well as that of hypocomplementemia argued in favor of the overlap of SLE in this patient. Low-dose cyclosporin A (CsA) combined with small dose of prednisolone could increase both platelet count and level of complement. Notably, the titers of several autoantibodies dropped after CsA was started. These findings might suggest that CsA could normalize the underlying immunologic abnormalities in this patient. However, the disease activity of RA could not be decreased without a help of low-dose methotrexate.

Antirheumatic Agents↗
PubMed1995

Effects of excess doses of alpha-tocopherol on the lipids and function of rainbow trout liver.

Rainbow trout (Oncorhynchus mykiss) were kept on diets containing three different alpha-tocopherol levels (0, 10, and 1,000 mg/100 g diet) to investigate the effects of excess doses of alpha-tocopherol on the liver lipids and liver functions. Both the content of the lipids except alpha-tocopherol in the liver and the triglyceride ratio in total lipids were significantly increased by the diets containing 1,000 mg of alpha-tocopherol per 100 g of diet. Many lipid droplets, 5-20 microns in the diameter, were observed in the liver. The TBARS per milligrams of liver lipids was decreased by 1,000-mg doses of alpha-tocopherol. GOT and GPT activity in serum were in the normal range regardless of the dose of alpha-tocopherol. From these data, it is considered that excess alpha-tocopherol promotes lipid accumulation enough to form droplets in the liver tissue, although liver function is not impaired.

Alanine Transaminase↗
PubMed1995

[Detection of anti small nuclear ribonucleoprotein antibody in patients with collagen disease--a comparison of sensitivities of four methods].

OBJECTIVE: To compare the sensitivity of four techniques that can detect the presence of anti small nuclear ribonucleoprotein (snRNP) antibodies. MATERIAL AND METHOD: Sera from eighty three patients with connective tissue disease were positive for antinuclear antibody by indirect immunofluorescence test. Patients consisted of 30 cases of systemic lupus erythematosus, 19 of rheumatoid arthritis, 9 of mixed connective tissue disease, 8 of systemic sclerosis, 3 of polymyositis, 13 of Sjögren syndrome, 1 of unclassified connective tissue disease. Four methods including double immunodiffusion (DID), enzyme linked immunosorbent assay (EIA), immunoprecipitation (IP) and immunoblotting (IB) were compared concerning their sensitivities of detecting anti-Sm and anti-RNP antibodies in these sera. RESULTS: Overall sensitivities for detecting the presence of each antibody were similar among four methods (DID: 32/83, EIA: 43/83, IP: 44/83, IB: 35/83). Concordance ratio of positive patterns between DID and EIA was 63/83 (81.9%). However, both EIA and IP could detect anti-U1 RNP antibody with higher sensitivity than DID. Although EIA seemed to detect anti-Sm antibody most sensitively in all methods, a coincidental decrease of specificity might be considered. IB could not classify anti-snRNP antibodies into anti-Sm and/or anti-RNP antibody because these antibodies might share some antigenic peptides of snRNP. Analysis of RNA in immunoprecipitate could not discriminate anti-RNP antibodies from anti-Sm antibodies because of shared RNA epitopes (e.g., U1-RNA, U1U2-RNA). CONCLUSION: These results suggested that EIA might be the most suitable method for detecting anti-RNP antibody and that several methods should be combined for detecting anti-Sm antibody.

Antibodies, Antinuclear↗
PubMed1995

[Multiple colonic ulcers in a patient with Sjögren's syndrome].

A 25-year-old female with Sjögren's syndrome was admitted to our hospital because of fever and abdominal pain. Multiple colonic ulcers were demonstrated by gastrographin enema and colonoscopy. Histological examination revealed the presence of necrotizing vasculitis in the submucosal region. Large dose of prednisolone (60 mg/day) brought a prompt relief of her symptoms and an improvement of positive inflammatory signs. Pseudoaneurysm in the arteria colica media, which had been demonstrated by abdominal selective angiography at the time of diagnosis, became extinct after the steroid treatment. Healing of ulcers were also noted by colonoscopy. A variety of extraglandular symptoms has been reported in Sjögren's syndrome. Multiple colonic ulcers due to vasculitis are rarely complicated but may have a great impact on the prognosis of the disease.

Adult↗
PubMed1994

In situ localization of rat testis-specific calcineurin B subunit isoform beta 1 in the developing rat testis.

In situ localization and developmental changes in expression of testis-specific calcineurin B subunit isoform beta 1 was examined in rat testis. Two different sizes of mRNA signal, 4.0 kb and 0.9 kb, were detected by Northern blot hybridization. Both signals were expressed synchronously with the start of meiosis at 3 weeks after birth, and increased depending on the maturation of spermatogenesis. In situ hybridization using non-radioactive riboprobes showed that the beta 1 mRNA was specifically localized to spermatocytes where meiosis occurs but none or very little was observed in spermatogonia, spermatids, Sertoli or Leydig cells.

Animals↗
PubMed1994

Immunosuppressants and calcineurin inhibitors, cyclosporin A and FK506, reversibly inhibit epileptogenesis in amygdaloid kindled rat.

Calcineurin (CaN) immunoreactivity and content increased markedly in kindled rat brain, and this increment was due to CaN in the membrane fraction. Investigation of the effects of cyclosporin A and FK506 (immunosuppressants which inhibit CaN activity in T lymphocytes) in the kindling phenomena showed that the kindling stage progression was reversibly blocked by these drugs. These findings suggest that calcineurin may play an essential role in acquiring epileptogenesis in kindling.

Amygdala↗
PubMed1994

Mutual interaction between host and graft tissues in embryonic neural transplantation.

The differentiation of AChE-positive cells in embryonic neural grafts from various brain regions into the hippocampus after fimbria-fornix transection was investigated. Rat fetal cell suspensions of basal forebrain, hippocampus, mesencephalon or cortex were prepared from fetuses of either embryonic day 14 (E14) or day 19 (E19) gestational age, and these were transplanted into the rat brain after unilateral fimbria-fornix transection. Dense acetylcholinesterase (AChE) positive fibres were observed in both E14 and E19 basal forebrain grafts. These fibres were also found in E14 hippocampal grafts. However E19 hippocampal grafts did not have any AChE-positive fibres. These results suggest that E14 hippocampal grafts might be affected by the host brain tissues and differentiate into cholinergic neurones.

Acetylcholinesterase↗
PubMed1994

Effect of low-dose cyclosporin A on systemic lupus erythematosus disease activity.

OBJECTIVE: To determine the effect of low-dose cyclosporin A (CSA) treatment on disease activity in systemic lupus erythematosus (SLE). METHODS: All patients in the study had active disease as defined by at least the presence of a low CH50 level. Patients were initially given 3 mg/kg/day of CSA. Dosages were adjusted individually at every visit, according to both clinical and laboratory data. RESULTS: Eleven women with SLE were enrolled in the study; 10 were evaluable. After 20 weeks of CSA treatment, the mean score for disease activity on the SLE Disease Activity Index decreased significantly, from 10.6 to 3.8 (P = 0.02). The titer of antinuclear antibodies decreased in 8 patients and the level of anti-DNA antibodies decreased in 5. Side effects included hypertension (40%), hypertrichosis (30%), gingival hypertrophy (10%), and a rise in the blood urea nitrogen level. Serum creatinine levels remained unchanged. CONCLUSION: The favorable responses observed in our patients strongly suggest that low-dose CSA can reduce the disease activity of SLE.

Adult↗
PubMed1994

A new method of quantitating serum and urinary levels of 1,5-anhydroglucitol in insulin-dependent diabetes mellitus.

A new method was developed for quantitating the serum and urinary levels of 1,5-anhydroglucitol (AG), a sensitive and informative marker of glycemic control. This method utilized a combination of ODS and pyranose oxidase-immobilized columns for HPLC, and monitored hydrogen peroxide production with an electrochemical detector. We applied this method to determine the serum and urinary AG levels in 15 patients with insulin-dependent diabetes mellitus (IDDM) as well as in control subjects. Baseline separation of AG from other sugars such as glucose and myoinositol was achieved. Quantitation of AG was achieved over the range from 0.2 ng to 0.3 micrograms based upon peak heights. The serum and urinary AG levels in the IDDM patients were 4.4 +/- 8.3 mg/l and 5.1 +/- 4.3 mg/day, respectively. We found that the urinary AG to serum AG ratio showed a linear correlation with the urinary glucose level in the IDDM patients (urinary glucose (y) vs. urinary AG to serum AG ratio (x): y = 9.071x-0.991; r = 0.968, P < 0.001). This method proved efficient and reliable for quantitating urinary AG. Since determination of both the AG and glucose levels in urine gives equivalent clinical information to the serum AG level, urinary monitoring could provide a valuable addition to the available methods for assessing the glycemic status of IDDM patients.

Adolescent↗
PubMed1994

Changes in annexin I and II levels during the postnatal development of rat pancreatic islets.

The expression patterns and the dynamic changes in content of both annexin I and annexin II in the rat pancreatic islets during postnatal development were investigated by both western blot analysis and immunohistochemistry. Immunohistochemical methods clearly demonstrated the presence of annexins I and II exclusively in pancreatic islets, while exocrine tissues were not stained by anti-annexin antibodies. Pancreatic islets were diffusely stained with no specific differences in distribution between different cell types. The expression of annexin I in pancreatic islets gradually increased with postnatal development. A developmental study of annexins I and II by western blot analysis essentially supported the results obtained by immunohistochemistry. In addition, the increasing expression of two protein tyrosine kinases, epidermal growth factor-receptor/kinase and pp60src, which phosphorylate annexin I and annexin II, respectively, and of protein kinase C, which phosphorylates both proteins, was also shown during postnatal development in rat pancreatic islets. Thus, a relationship between the expression of annexins I and II and the maturation of islet cell function is suggested.

Actins↗