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Biomedical subjects

S Toyoshima

Publications and source records attributed to S Toyoshima.

At least 73 records · Page 4Linked to original sources
PubMed1996

Extensive soft-tissue involvement of dermatomyositis detected by whole-body scintigraphy with 99mTc-MDP and 201TL-chloride.

The authors present a case of extensive soft-tissue radioactivity visualized on both 99mTc-MDP and 201Tl-chloride scintigrams in a patient with dermatomyositis and colon cancer. Incidentally, diffuse and intense uptake of 99mTc-MDP was observed in the shoulder girdles, anterior chest wall, psoas muscles, both proximal thighs and right lower limb, corresponding to the sites of symptomatic muscles, even though skin lesions were limited and no calcification was detected on radiographs. Moreover, 201Tl-chloride was also intensely accumulated in nearly the same sites as the symptomatic muscles as shown on the 99mTc-MDP bone scintigrams. Whole-body scintigraphy with 99mTc-MDP and 201Tl-chloride is a useful tool to detect occult muscle lesions with dystrophic calcification and hyperemia in dermatomyositis.

Calcinosis↗
PubMed1996

Immunochemical distribution and immunohistochemical localization of 20beta-hydroxysteroid dehydrogenase in neonatal pig tissues.

Immunochemical distribution of 20beta-hydroxysteroid dehydrogenase (HSD) in neonatal pig tissues was investigated by Western blot analysis of the proteins reacting with anti-20beta-HSD antibody. 20beta-HSD was present in all organs investigated: brain, lung, thymus, submandibular gland, heart, liver, kidney, spleen, adrenal gland, testis, epididymis, prostate, vas deferens and seminal vesicle. In particular, high concentrations of 20beta-HSD were detected in the testis, followed by the kidney and liver, by the [125I]-protein A binding method. Immunohistochemical localization of the enzyme was achieved in paraffin sections of the testis, kidney, liver, epididymis, and vas deferens by the streptoavidin-biotin complex method. In the testis, very strong immunostaining was found only in interstitial Leydig cells, whereas the cells in seminiferous tubules, such as Sertoli cells and spermatogenic cells, were entirely negative. In the kidney, strong immunostaining was detected in epithelial cells of Henle's loop. The immunoreactive proteins were also localized in the hepatic lobules of the liver, tall columnar cells of the ductus epididymidis of the epididymis, and mucosal epithelium cells and muscularis of the vas deferens. These observations indicate that tissue distribution of 20beta-HSD is similar to that of carbonyl reductase in the human and rat. However, the specific and abundant expression of 20beta-HSD in testicular Leydig cells of the neonatal pig, which are concerned with the synthesis of androgens, suggests that 20beta-HSD has a very important physiological role in testicular function during the neonatal stage.

Animals↗
PubMed1996

Accumulation of methylmalonic acid caused by vitamin B12-deficiency disrupts normal cellular metabolism in rat liver.

To clarify the relationship between intracellular concentrations of methylmalonic acid and metabolic and growth inhibition in vitamin B12-deficient rats, hepatic methylmalonic acid levels were assayed and inhibition of glucose and glutamic acid metabolism by methylmalonic acid was studied in isolated hepatocytes. Vitamin B12-deficient rats (14 weeks old) excreted more urinary methylmalonic acid and had lower body weights than the control rats. Hepatic methylmalonic acid levels (3.6(SD 1.30)-5.3 (SD 0.51) mumol/g tissue; 7.9 (SD 2.90)-11.8 (SD 1.14) mM) were increased and correlated with the extent of the growth retardation during vitamin B12-deficiency. Isolated hepatocytes and mitochondria from normally fed rats were labelled with [14C(U)]glucose and [14C(U)]glutamic acid respectively, in the presence or absence of 5 mM-methylmalonic acid. Although methylmalonic acid did not affect the incorporation of 14C into protein and organic acid fractions in the hepatocytes, it inhibited 14CO2 formation (an index of glucose oxidation by the Krebs cycle) by 25% and incorporation of 14C into the amino acid fraction by 30%. In the mitochondria, methylmalonic acid inhibited 14CO2 formation (indicating glutamic acid oxidation by the Krebs cycle) by 70%, but not the incorporation of 14C into the protein fraction. The incorporation of 14C into the organic acid fraction was significantly stimulated by the addition of methylmalonic acid. These results indicate that the unusual accumulation of methylmalonic acid caused by vitamin B12-deficiency disrupts normal glucose and glutamic acid metabolism in rat liver, probably by inhibiting the Krebs cycle.

Animals↗
PubMed1996

Breast lesions: correlation of contrast medium enhancement patterns on MR images with histopathologic findings and tumor angiogenesis.

PURPOSE: To compare qualitative and quantitative magnetic resonance (MR) mammographic features of breast lesions with histopathologic findings, especially tumor angiogenesis. MATERIALS AND METHODS: Seventy-three patients (72 women, one man; aged 30-78 years; mean age, 51.0 years) with suspicious breast lesions underwent MR imaging. Noncontrast medium-enhanced localization imaging and then gadolinium-enhanced dynamic fast spoiled gradient-recalled-echo (SPGR) imaging were performed in all patients. In selected patients, subtraction fast SPGR images were obtained. The Pearson and Spearman correlation tests were used to determine the strength of the relationships between enhancement parameters and microvessel determinations. RESULTS: Time intensity curve type correlated with microvessel density grade (Spearman rank correlation test: r = .90, P < .001). The steepest slope of contrast medium uptake correlated with microvessel counts (Pearson correlation test; r = .83, P < .001). Peripheral enhancement in invasive carcinomas (n = 9) correlated with high peripheral and low central microvessel densities, which were associated with desmoplasia and/or necrosis. Internal septations (n = 2) were seen only in fibroadenomas. CONCLUSION: The density and distribution of microvessels may play major roles in the determination of the initial rate of contrast medium uptake and the heterogeneity of tumor enhancement.

Adult↗
PubMed1996

Antioxidative effect of sesamol and related compounds on lipid peroxidation.

The effect of sesamol and 20 related compounds on the lipid peroxidation of liposomes induced by Fe(2)+, on the lipid peroxidation of rat liver microsomes induced by CCl(4) or NADPH and on the lipid peroxidation of mitochondria induced by ascorbate/Fe(2)+ were demonstrated. Consequently, sesamol and related compounds, such as 3-methoxy-4-hydroxyquinone, isosafrol, isoeugenol, eugenol, 3,4-methylenedioxyaniline, catechol, hydroxy-hydroquinone, 3,4-dimethoxyaniline and caffeic acid, exhibited powerful inhibitory effects on the lipid peroxidation system investigated. In particular, isoeugenol was the most powerful inhibitor among all the sesamol-related compounds tested on the lipid peroxidation system. In addition, 1,2-methylenedioxybenzene, ferulic acid, and 3,4-methylenedioxynitrobenzene were also effective on the lipid peroxidation system of liposomes induced by Fe(2)+. The correlation between the structures of sesamol-related compounds and their inhibitory effect is discussed.

Animals↗
PubMed1995

Molecular cloning of a novel actin-binding protein, p57, with a WD repeat and a leucine zipper motif.

A 57 kDa protein (p57) was obtained during the study on phosphatidylinositol-specific phospholipase C. Its cDNA was isolated from calf spleen and human leukemia cell line HL60 libraries and cloned. In the primary structures of p57, they have two unique amino acid sequence motifs, a WD repeat and a leucine zipper motif. Furthermore, p57 shared sequence similarity (40%) with coronin, an actin-binding protein responsible for chemotaxis, cell motility, and cytokinesis of Dictyostelium discoideum, which has only the WD repeat. p57 also showed an actin-binding activity and was mainly expressed in immune tissues. From these results, we conclude that p57 is a coronin-like novel actin-binding protein in mammalian cells but may also have a different function from coronin.

Actins↗
PubMed1995

Methylmalonic acid inhibits respiration in rat liver mitochondria.

Methylmalonic acid (MMA), which accumulates and is excreted in urine in mammals during vitamin B-12 deficiency, has been reported to inhibit succinate dehydrogenase, an enzyme involved in the mitochondrial tricarboxylic acid (TCA) cycle in rat liver. The enzyme inhibition by MMA may lead to various metabolic disorders as well as inhibition of mitochondrial energy generation in vitamin B-12-deficient mammals. To clarify the inhibition of succinate dehydrogenase by MMA in intact rat liver mitochondria, the effect of MMA on mitochondrial respiration was studied. When 6 mmol/L MMA was added to the reaction mixture for measuring mitochondrial respiration with succinate as a substrate, MMA was taken up and accumulated by the mitochondria (34-53 mmol/L). The accumulation of mitochondrial MMA was stimulated by the addition of ADP. Methylmalonic acid competitively inhibited State 3 mitochondrial respiration, and the Ki for the acid was 4.2 +/- 0.4 mmol/L. Although the respiratory control ratio decreased with increasing MMA concentration, the acid did not affect the phosphorus/oxygen ratio. Mitochondrial MMA accumulation secondary to vitamin B-12 deficiency inhibits succinate dehydrogenase and may contribute to various metabolic disorders associated with vitamin B-12 deficiency.

Adenosine Diphosphate↗
PubMed1995

Protein kinase C phosphorylates p50 LSP1 and induces translocation of p50 LSP1 in T lymphocytes.

A lymphocyte-specific protein, p50, is phosphorylated on Ser and Thr residues in mitogen-activated T cells, suggesting that this molecule plays some role in the T cell activation cascade. p50 was identified as lymphocyte specific protein 1 (LSP1), which is a putative calcium-binding protein. In the present study, to clarify the role of p50 protein in the cascade, in vivo and in vitro phosphorylation of this molecule, and the effect of the phosphorylation on its distribution in activated T cells were examined. First, to obtain a sufficient amount of p50 as a phosphorylation substrate, p50 cDNA, which encodes a protein of 330 amino acid residues with a molecular mass of 36,728 Da, was cloned from an ICR mouse thymocyte cDNA library and expressed in Escherichia coli. When the putative coding region of p50 cDNA was expressed in E. coli, the product showed an apparent molecular mass of 50 kDa on SDS-PAGE. The recombinant p50 was phosphorylated in vitro by rabbit protein kinase C (PKC) and by murine cytosolic protein kinase, that was activated by a combination of phosphatidylserine and diacylglycerol. Furthermore, p50 was shown to be phosphorylated on the same sites in T cells upon stimulation with Con A as when phosphorylated in vitro by rabbit PKC, indicating that p50 is phosphorylated by PKC in Con A-stimulated T cells. On subcellular fractionation followed by immunoblotting analysis, membrane-bound p50 was shown to be released from the membrane following activation of PKC in T cells. These results and the recent finding that p50 binds to actin fibers raise the possibility that p50 controls the binding of actin fibers to the plasma membrane under regulation by PKC in T cells.

Amino Acid Sequence↗
PubMed1995

Lymphocyte isoforms of mouse p50 LSP1, which are phosphorylated in mitogen-activated T cells, are formed through alternative splicing and phosphorylation.

p50 is phosphorylated in mitogen-stimulated T cells, and translocated from the membrane to the cytosol after activation of protein kinase C. Sequence analysis of p50 revealed that it is identical with LSP1, a putative calcium-binding and actin-binding protein. lymphocyte form of p50 exhibits heterogeneity in the apparent molecular mass on SDS-PAGE, 50 and 52 kDa (pp50 and pp52), and each isoform exhibits heterogeneity in the isoelectric point, when examined by two-dimensional PAGE. When the two molecular mass variants of p50 were dephosphorylated with alkaline phosphatase, both isoforms showed the same apparent molecular mass of 50 kDa on SDS-PAGE, but could be distinguished by their distinct isoelectric points. Dephosphorylated pp50 (p50a) has an acidic pI compared with dephosphorylated pp52 (p50b). Comparison of the peptide maps of purified p50a and p50b on HPLC revealed that the difference was limited to one peptide peak. NH2-terminal sequence and mass spectrometric analyses of these peptides showed that the peptides derived from p50a and p50b had the same NH2-terminal amino acid sequence up to eight residues, but had distinct molecular masses, 5,533.4 and 6,318.6 Da, respectively. These data suggested that pp52 (p50b) is the product of the previously cloned cDNA and the reduction in the molecular mass of the p50a-derived peptide could be explained by deletion of six amino acid residues, EHLIRH or HLIRHQ.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1995

Recognition of consensus CHO structure in ligands for selectins by novel antibody against sialyl Lewis X.

The selectins (L, E, and P) play an important role in the earliest events of the inflammatory response, leading to the "rolling" phenomenon. All selectins react with sialyl Lewis X (SLex) in vitro, possibly suggesting that their ligands have a consensus structure. 2H5 is a monoclonal antibody against SLex that blocks L-selectin-mediated adhesion. 2H5 inhibited adhesion of HL-60 cells to P- and E-selectin-producing COS cells in vitro and immunoprecipitated a P-selectin glycoprotein ligand-1-like glycoprotein from HL-60 cell lysate, suggesting that it recognizes a functional consensus structure on the ligands for all selectins. 2H5 reacted not only with human but also with rat and mouse neutrophils. 2H5 is the first antibody against SLex that recognizes neutrophils of nonhuman mammals. The carbohydrate structure recognized by 2H5 was present not only on high endothelial venules of rat lymphoid organs but also on the endothelial cells of nonlymphoid organs. Furthermore, administration of the antibody markedly inhibited L- and P-selectin-mediated neutrophil rolling and adhesion in rat mesenteric venules in vivo. These results provide evidence for the presence of a consensus carbohydrate structure on the ligands for all selectins. The consensus structure thus has the potential to serve as a therapeutic target.

Animals↗
PubMed1994

Characterization of a GTP-binding protein implicated in both memory storage and interorganelle vesicle transport.

The phosphorylation state of cp20, a low molecular weight GTP-binding protein that is a high-affinity substrate for protein kinase C, was previously shown to change after associative conditioning of molluscs and mammals and to induce many of the biophysical and structural modifications that accompany memory retention. Here, cp20 was purified from squid optic lobes and biochemically characterized. A monoclonal antibody prepared against squid cp20 reacted with Hermissenda cp20 and a 20-kDa protein in rabbit hippocampus, while a polyclonal antibody also cross-reacted with Sar1p and ADP-ribosylation factor (ARF). A partial peptide sequence of squid cp20 was 50% identical (23/46 amino acids) with Sar1p, a yeast GTP-binding protein involved in vesicle transport, indicating that cp20 is probably a new member of the ARF family. This classification is consistent with our recent demonstration that cp20 affects retrograde movement of intraaxonal organelles or particles and suggests a possible role for particle traffic between intraneuronal organelles in memory acquisition.

Amino Acid Sequence↗
PubMed1994

Dual function of macrophage galactose/N-acetylgalactosamine-specific lectins: glycoprotein uptake and tumoricidal cellular recognition.

We investigated whether the interaction of peritoneal macrophages with extracellular ligands is mediated by C-type lectins specific for galactose and N-acetylgalactosamine. The carbohydrate-binding domain of mouse galactose/N-acetylgalactosamine-specific lectin was prepared in a recombinant form. The purified recombinant lectins were tested for competitive inhibition against glycoprotein uptake and against tumoricidal effect. Thioglycolate-elicited macrophages internalized galactosylated bovine serum albumin in vitro. The internalization was blocked by recombinant macrophage lectins. Activated macrophages obtained after intraperitoneal injection of a nonspecific immune potentiator, OK432, did not internalize galactosylated bovine serum albumin. These cells elicited a cytotoxic effect against P815 murine mastocytoma cells, and the effect was blocked by recombinant macrophage lectins. These results indicated that galactose/N-acetylgalactosamine-specific C-type lectins expressed on the surface of inflammatory macrophages and on activated tumoricidal macrophages mediate two distinct functions, i.e. glycoprotein uptake and tumoricidal effector mechanisms.

Acetylgalactosamine↗
PubMed1994

[Multi-center evaluation to discriminate between the strains of methicillin-resistant Staphylococcus aureus (MRSA) and those susceptible (MSSA) by Showa oxacillin and methicillin disk susceptibility tests].

The Showa disk susceptibility test using two penicillinase-resistant penicillins, oxacillin and methicillin, was evaluated to discriminate between the strains of Staphylococcus aureus resistant to methicillin (MRSA) and those susceptible (MSSA) in the multi-center trials. The study included 651 clinical isolates of S. aureus, comprising of 329 MRSA and 322 MSSA isolates. The inhibitory zone diameters by Showa disks to oxacillin and methicillin highly correlated with minimum inhibitory concentrations (MICs) determined by standard agar dilutions with 0.961 and 0.930 correlation coefficients, respectively. Of 651 duplicate MIC determinations, 79.9% (oxacillin) and 80.3% (methicillin) were within +/- 1 log2 dilutions with each other. When Showa oxacillin and methicillin disks were incubated at 35 degrees C, sensitivity and specificity of oxacillin to detect MRSA were 95.4% and 98.1%, and those of methicillin were 94.8% and 95.2%. When tested on agar plates supplemented with 5% NaCl, sensitivity and specificity markedly improved to > 97%. Also, when incubated at 30 degrees C, sensitivity and specificity became to nearly 100%. Of 329 MRSA isolates, the interpretive criteria combined with incubation at 30 degrees C and testing onto 5% NaCl supplemented agar plates could correctly identify 324 (98.5%) and 329 (100%) isolates, respectively. In conclusion, when the Showa oxacillin and methicillin disk susceptibility tests were employed exactly according to the manufacturer's instruction, the test performances to detect MRSA were enough reliable to screen MRSA isolates in clinical microbiology laboratories.

Methicillin↗
PubMed1994

[Multi-center evaluation of Showa ceftizoxime disk susceptibility test to discriminate between the strains of methicillin-resistant Staphylococcus aureus (MRSA) and those susceptible (MSSA)].

An increasing prevalence of methicillin-resistant Staphylococcus (S.) aureus (MRSA) has a serious therapeutic problem, and accurate methods to detect such strains are needed. We studied the antimicrobial susceptibility of S. aureus to ceftizoxime, in comparison with those to four other cephems (cefazolin, cefoxitin, latamoxef and cefmenoxime), by broth microdilutions and disk susceptibility tests, and also evaluated whether the reagents, in replace of penicillinase-resistant penicillins (PRPs), could discriminate between the strains of MRSA and those susceptible to PRPs (MSSA). A total of 651 clinical isolates of S. aureus were collected from six geographically different hospitals. All the strains collected were first classified into either MRSA (n = 329) or MSSA (n = 322) according to the interpretations of MRSA screening agar, minimum inhibitory concentrations (MICs) to oxacillin and methicillin (NCCLS M7-A2), and the presence or absence of mecA gene by polymerase chain reaction. In broth microdilution tests, the MICs of MRSA to ceftizoxime ranged > or = 64 micrograms/ml, whereas all the MSSA were at the concentration of < or = 16 micrograms/ml. The results of Showa disk diffusion tests highly correlated with those of MIC determinations. The distribution of inhibitory zone diameters to ceftizoxime were clearly divided into two groups; 99.2% (sensitivity) of MRSA had inhibitory zones of < or = 20 mm and 98.9% (specificity) of MSSA produced > or = 21 mm. It was concluded that the Showa ceftizoxime disk susceptibility test was useful and enough reliable to screen MRSA isolates in clinical laboratories.

Ceftizoxime↗
PubMed1993

Two distinct signal transduction pathways for the activation of guinea-pig macrophages and neutrophils by endotoxin.

Lipopolysaccharide (LPS, endotoxin) is a major component of the outer membrane of gram-negative bacteria. Although it interacts with many types of cells and is linked to numerous events associated with sepsis and endotoxic shock, the mechanisms underlying these actions are poorly understood. We found that Ca-signaling induced by endotoxin in guinea-pig neutrophils and macrophages is caused by cross-recognition of LPS with platelet activating factor (PAF) receptors. However, the synthesis of tumor necrosis factor-alpha or the priming effect of O2- production was not affected by PAF antagonists. Thus, at least two distinct pathways are involved in the actions of LPS, one via the PAF receptor, while the other is independent of a PAF receptor and Ca-signaling.

Animals↗
PubMed1993

Regulation of c-MYC protein expression in the developing rat cerebellum by phosphoinositide turnover.

Using developing rat cerebellum, we examined the correlation between the turnover of phosphoinositide (PI) and c-myc expression. The 32P incorporation into polyphosphoinositides changed remarkably with advancing age. It reached a maximum value on PND 7, and then decreased gradually until PND 14. Immunostaining by anti-PIP2 antibody changed in parallel. The expression of c-myc mRNA was also changed developmentally, showing a peak on PND 7; whereas c-MYC protein expression showed a peak on PND 10. Together, these results suggest that c-myc expression is regulated by PI turnover during the early developing stage of rat cerebellum.

Aging↗