Biomedical subjects

S Yoshida

Publications and source records attributed to S Yoshida.

At least 829 records · Page 46Linked to original sources

PubMed1996

Slow beta-migrating lipoprotein: an atherogenic subclass of low density lipoproteins.

OBJECTIVE: To clarify the possibility that midband Lp in LDL fractions might act as an atherogenic lipoprotein in their interaction with macrophages. DESIGN AND METHODS: Low density lipoproteins (LDL) isolated by zonal ultracentrifugation from midband lipoprotein-positive serum in type lib hyperlipidemics were subjected to polyacrylamide gel disc electrophoresis. RESULTS: A part of midband lipoprotein was observed between pre beta-and beta-band, in addition to the main beta-band. We named this midband lipoprotein "slow beta-migrating Lp (slow beta-Lp)." The larger LDL subfraction from midband-lipoprotein positive serum on Sepharose 2B column chromatography contained much slow beta-Lp, named slow beta-Lp-rich LDL. The smaller LDL subfraction contained a little slow beta-Lp, named slow beta-Lp-poor LDL. Slow beta-Lp-rich LDL had similar composition to the control LDL except for apolipoprotein E. The uptake of [3H]cholesteryl linoleate-labeled slow beta-Lp-rich LDL by J774 macrophages was higher than that of control LDL. The cholesterol ester content of J774 macrophages incubated with slow beta-Lp-rich LDL increased significantly compared with slow beta-Lp-poor LDL, beta-VLDL, and control LDL. CONCLUSION: These results suggest that slow beta-Lp in type llb might generate foam cells from macrophages in atherosclerotic lesions.

Animals↗

PubMed1996

Property of receptor for vasoactive intestinal contractor (VIC) expressed in Xenopus oocytes injected with mRNA from rat intestine.

Property of receptor for vasoactive intestinal contractor (VIC), a peptide related to the endothelin family, expressed in Xenopus oocytes by injecting mRNA obtained from the intestine of rat, were studied using the voltage-clamp method. Inward-current responses to VIC (1 nM-100 nM) were evoked in a concentration-dependent manner in mRNA-injected oocytes. Non-injected and water-injected oocytes failed to respond to VIC. The reversal potential for the VIC response was around -20 mV and the depolarizing shift was approximately 18 mV, when the external concentration of Cl-was halved, in agreement with the Nernst equation. The response to VIC was suppressed either by the external application to BAPTA/AM (10 microM) or by pertussis toxin 0.5 microgram/ml). These results indicate that the receptor for VIC, functionally expressed in Xenopus oocytes injected with rat intestinal mRNA, is coupled to pertussis toxin-sensitive G-protein and its activation leads to mobilization of intracellular Ca2+.

Animals↗

PubMed1996

The dual expression of minor and major bcr/abl chimeric mRNA in blast crisis of chronic myelogenous leukemia.

The hypothesis that minor bcr/abl fusion mRNA is produced in blast crisis of chronic myelogenous leukemia (CML) is examined. The RNA transcripts encoding the minor and major bcr/abl fused protein were detected by polymerase chain reaction (PCR) using RNA from peripheral blood or bone marrow cells of eight patients with blast crisis or accelerated phase of CML. The mRNA encoding for major bcr/abl was detected in all eight cases. In four patients, however, transcripts encoding for minor bcr/abl mRNA were detected, as well as major bcr/abl mRNA. The presence of minor bcr/abl mRNA was verified with the hybridization with a junction-specific probe and DNA sequencing analysis of PCR products. The appearance of minor bcr/abl fusion mRNA was associated with the lymphoblastic immunophenotype of the blast cells. In two of these four patients, samples of initial diagnosis of chronic phase of CML were available, which did not show minor bcr/abl transcript. We conclude that the appearance of minor bcr/abl mRNA transcript is associated with the terminal evolution of CML in lymphoblastic crisis.

Adolescent↗

PubMed1996

Analysis of neuronal death in the central nervous system using a new apoptosis model.

To examine in detail neural apoptosis in the central nervous system (CNS) for the establishment of new therapies, we have developed an experimental in vitro model of neuronal death and analyzed the mechanism of apoptosis. Septal nuclei were dissected from embryonic brains (E16) of Wistar rats and cultured in chemically defined medium. Highly enriched neurons were obtained from the cultures at 4 days. Exposure to heat shock (43.0 degrees C, 60 min) between 24 and 36 h later, resulted in the death of approximately 70% of cells. Morphologically, dying neurons showed disruption of neurites, nuclear condensation, multiple nuclear fragments, condensation of cytoplasm and multiple cellular fragmentation. Agarose electrophoresis of chromosomal DNA revealed a typical ladder-pattern of fragmentation. Following heat treatment, incubation at 37 degrees C was necessary to detect DNA fragmentation. Quantitative analysis by in situ terminal deoxynucleotidyl transferase assay, revealed that the percentage of apoptotic cells markedly increased 8 h after heat treatment, and continued to gradually increase up until 30 h. Neuronal death and DNA fragmentation were prevented by inhibiting RNA and protein synthesis. Cell death and the DNA cleavage were also inhibited by cultivation in calcium-free medium. The addition of homogenous basic fibroblast growth factor to the medium markedly enhanced cell survival under these pathogenic conditions. These results suggest that neural cell death after mild heat treatment has apoptotic characteristics and may be useful for analyzing the mechanism of apoptosis. The clinical application of drugs acting against molecular components and as well as neurotrophic factors, may in the future prevent apoptosis in neural disease.

Animals↗

PubMed1996

Regression of increased left ventricular masses in elderly hypertensive patients on lisinopril as assessed by magnetic resonance imaging.

RATIONALE AND OBJECTIVES: We investigated, using magnetic resonance imaging, whether the addition of lisinopril could reduce increased left ventricular (LV) masses in hypertensive patients whose blood pressure was well controlled with nifedipine. METHODS: Fourteen hypertensive patients being treated with nifedipine and having an interventricular septum thickness of more than 12 mm were studied. Half of them were given 5 mg lisinopril, and the others were not. Short-axis images of the left ventricle from the base to the apex were obtained by a standard spin-echo pulse sequence. The entire LV mass was calculated from the area of short-axis slices of the left ventricle multiplied by slice thickness. RESULTS: Blood pressure fell slightly and almost equally in both groups. The LV mass and LV mass index showed a significant decrease in the lisinopril-treated group but not in the control group. CONCLUSION: Results demonstrate the effectiveness of lisinopril in reducing increased LV masses, at least in combination with nifedipine.

Aged↗

PubMed1996

Biologic responses of the pulp to single-tooth dento-osseous osteotomy.

OBJECTIVE: This study was conducted to investigate biologic responses of the pulp to single-tooth dento-osseous osteotomy and to explore an appropriate level of transverse bone resection for maintaining biologic activity of the pulp in monkeys. STUDY DESIGN: The levels of transverse bone resection were designed at approximately 10 mm (10 mm group) and 5 mm (5 mm group) above the apices. Histologic and histomorphometric changes were evaluated microscopically, and changes in blood flow in the pulp were also measured in terms of vascular responses to a vasoconstrictor (noradrenaline, NA). RESULTS: Vacuolar degeneration in the pulp chamber associated with less number of the pulp cells were more prominent in the 5 mm group, and the response of blood flow to NA was maintained better in the 10-mm group. CONCLUSION: It is shown in this 8-week experiment that biologic activity of the pulp is much better preserved in the 10-mm group than in the 5-mm group, whereas the pulpal response may become similar if observed for a longer period.

Alveolar Process↗

PubMed1996

Elevation of serum soluble tumour necrosis factor (TNF) receptor and IL-1 receptor antagonist levels in bronchial asthma.

The specific inhibitor for TNF-alpha activity, soluble form of the 55-kD TNF receptor (sTNF-RI) and soluble form of the 75-kD receptor (sTNF-RII), and the specific inhibitor for IL-1 activity, IL-1 receptor antagonist (IL-1Ra), have been identified. It has been shown that the levels of these inhibitors are elevated in plasma/serum and biological fluids in several diseases, and the protective and inhibitory effect of these inhibitors exist in several inflammatory diseases. In the present study, we measured serum levels of sTNF-RI, STNF-RII and IL-1Ra by ELISA in 36 patients with bronchial asthma (16 atopic and 20 non-atopic) during asthma attacks and in stable conditions in order to assess the state of these inhibitors in allergic inflammation. The levels of sTNF-RI, sTNF-RII and IL-1Ra in sera obtained during bronchial asthma attacks were higher than those in sera obtained in stable conditions. These findings were obtained regardless of atopic status. These results suggest that higher levels of serum sTNF-RI, sTNF-RII and IL-1Ra may reflect up-regulation of TNF-R expression and IL-1Ra production in allergic inflammation, and sTNF-RI, sTNF-RII and IL-1Ra may contribute to regulating TNF-alpha- and IL-1-mediated production and development of allergic inflammation.

Adult↗

PubMed1996

Characteristics of the pituitary gland in elderly subjects from magnetic resonance images: relationship to pituitary hormone secretion.

OBJECTIVE: Physiological changes in the pituitary gland with age have not been fully evaluated. The aim of this study was to clarify the morphological characteristics of the pituitary gland by magnetic resonance imaging(MRI) in elderly subjects and to relate them to pituitary hormone secretion. DESIGN AND PATIENTS: We investigated the pituitary MRI in 59 elderly (15 males, 44 females; median 82 years) and 41 young (13 males, 28 females; median 34 years) healthy subjects. RESULTS: Pituitary height, width and volume in the elderly subjects were less than those in the young subjects. Empty sella was more frequently observed in the elderly subjects (19%), especially women, than in the young ones. However, no relation was observed between the pituitary size or volume and basal levels of anterior pituitary hormones. Posterior pituitary bright signal(PBS) on T1-weighted MRI, which is thought to reflect its storage of the neurophysin-peptide complex, was not detected in 29% of the elderly subjects while it could be detected in all the young subjects. None of the elderly subjects showed clinical signs or symptoms of diabetes insipidus. Fasting plasma osmolarity and AVP in the elderly subjects were significantly higher than in the young subjects. Moreover, plasma AVP was significantly higher in the elderly subjects without the PBS than in those with the PBS. CONCLUSIONS: It is suggested that the excessive release of AVP from the posterior pituitary as a result of persistently raised plasma osmolality in the elderly subjects may lead to depletion of the neurosecretory granules in the posterior pituitary gland and may result in disappearance of the posterior pituitary bright signal on T1-weighted MRI. As these morphological changes might relate to the normal physiological occurrence of ageing, we should be cautious in evaluating MRI of the pituitary gland in elderly subjects.

Adrenocorticotropic Hormone↗

PubMed1996

Primary low cerebrospinal fluid pressure syndrome with galactorrhea: findings at MR imaging.

A case of primary low cerebrospinal fluid (CSF) pressure syndrome with galactorrhea is reported. Magnetic resonance imaging demonstrated diffusely enhanced meninges, edematous brain, and enlarged pituitary gland. Coincidental enlargement of pituitary gland and edematous brain due to low CSF pressure compressed the pituitary portal system. The low-perfused anterior lobe of pituitary gland would be the mechanism of galactorrhea.

Adult↗

PubMed1996

Tetrahydrobiopterin biosynthesis enhanced by lipopolysaccharide stimulation in murine neuroblastoma cell line N1E-115.

We investigated for the first time the effect of lipopolysaccharide and the signal transduction pathway on the biosynthesis of tetrahydrobiopterin [(6R-L-erythro-1',2'-dihydroxypropyl) -2-amino-4-hydroxy-5,6,7,8-tetrahydropteridine], the cofactor for the enzymatic hydroxylation of the aromatic amino acids, in the murine neuroblastoma cell line N1E-115, which synthesizes tetrahydrobiopterin constitutively. Activation of N1E-115 cells with 1 microgram/ml lipopolysaccharide resulted in statistically significant increases in both intracellular tetrahydrobiopterin contents and the activity (Vmax) of GTP cyclohydrolase I, a rate-limiting enzyme in tetrahydrobiopterin de novo biosynthesis. Following simultaneous addition of the inhibitors of protein tyrosine kinases and GTP-binding proteins into serum-free culture media with lipopolysaccharide, we analyzed the transduction pathway of lipopolysaccharide signal toward the tetrahydrobiopterin biosynthetic system in N1E-115 cells. Our data indicate the following conclusions: (a) Protein tyrosine kinase systems are involved in mediating lipopoly-saccharide signal to tetrahydrobiopterin production, and (b) there may be a cross-talk between GTP-binding protein and the protein tyrosine kinase system in mediating lipopolysaccharide signal. These observations suggest that a neuronal cell such as N1E-115, which barely expresses CD14 on its cell surface, responds to lipopolysaccharide like macrophages and monocytes in the absence of soluble CD14.

Animals↗

PubMed1996

Sphingomyelin changes in rat cerebral cortex during focal ischemia.

To better define the sphingolipid metabolism during focal brain ischemia, levels of ceramide, sphingomyelin, cerebroside and gangliosides were determined in rat cerebral cortex during focal ischemia produced by occlusion of the middle cerebral artery. Sphingomyelin began to decrease at 2 hours of ischemia and continued to decrease for 96 hours. In contrast, ceramide increased at 6 hours and increased to 4.2-fold at 96 hours after ischemia, and the fatty acid composition of ceramide was solely nonhydroxylated fatty acid similar to sphingomyelin. Hydroxylated fatty acid-linked cerebroside decreased at 6 hours of ischemia, whereas any significant decrease of nonhydroxylated fatty acid-linked cerebroside didn't occur for 96 hours of ischemia. There were no measurable changes in the levels of gangliosides. These results suggested that ceramide was produced in the cerebral cortex by the breakdown of sphingomyelin during early ischemia.

Animals↗

PubMed1996

Lysophosphatidic acid and bFGF control different modes in proliferating myoblasts.

Myogenic cells provide excellent in vitro models for studying the cell growth and differentiation. In this study we report that lysophosphatidic acid (LPA), a bioactive phospholipid contained in serum, stimulates the growth and inhibits the differentiation of mouse C2C12 myoblast cells, in a distinct manner from basic fibroblast growth factor (bFGF) whose mitotic and anti-differentiation actions have been well investigated. These actions of LPA were both blocked by pertussis toxin, suggesting the involvement of Gi class of G proteins, whereas bFGF acts through receptor tyrosine kinases. Detailed analysis revealed that LPA and bFGF act differently in regulating the myogenic basic helix-loop-helix (bHLH) proteins, the key players in myogenic differentiation process. LPA stimulates the proliferation of undifferentiated myoblasts allowing the continued expression of MyoD, but in contrast, bFGF does so with the MyoD expression suppressed at the mRNA level. Both compounds maintain the myf-5 expression, and suppress the myogenin expression. In addition, while LPA did not inhibit cell-cell contact-induced differentiation, bFGF strongly inhibited this process. Furthermore, LPA and bFGF act cooperatively in their mitogenic and anti-differentiation abilities. These findings indicate that LPA and bFGF differently stimulate intracellular signaling pathways, resulting in proliferating myoblasts each bearing a distinct expression pattern of myogenic bHLH proteins and distinct differentiation potentials in response to cell-cell contact, and illustrate the biological significance of Gi-mediated and tyrosine kinase-mediated signals.

Animals↗

PubMed1996

Effects of interferon-alpha, beta, and gamma on the function of differentiated leukemic HL-60 cells induced by 1,25-dihydroxyvitamin D3.

The differentiation of HL-60, a human leukemic cell line, into monocyte-like cells (D3-HL-60 cells) is induced by 1,25-dihydroxyvitamin D3 (D3). We examined the effects of interferon (IFN) treatment of D3-HL-60 cells on the expression of cell surface antigens, the phagocytic activity for fluorescent beads, production of oxygen radicals, and intracellular growth of Legionella pneumophila. Activation of D3-HL-60 cells with IFN-gamma, Beta, and alpha for 24 h significantly increased expression of CD16, CD36, CD71, and HLA-DR antigens. IFN-gamma markedly enhanced the phagocytic activity of beads in D3-HL-60 cells. There was no significant difference in phagocytic activity between cells exposed to IFN-alpha or beta and untreated D3-HL-60 cells. IFN-alpha, beta, and gamma enhanced production of oxygen radicals, including superoxide, by D3-HL-60 cells. Superoxide production was enhanced to the greatest degree by IFN-gamma, followed by IFN-beta and then IFN-gamma. Intracellular growth of L. pneumophila in D3-HL-60 cells was inhibited by interferons (IFN-gamma > beta > gamma). Similar results were obtained in human mononuclear cells. These data indicate that interferons can act as biologic response modifiers not only in human mononuclear cells but also in differentiated leukemic cells. Our results may have implications for the development of differentiation therapy for treatment of leukemia.

Animals↗

PubMed1996

Chlamydia trachomatis antibody titres by enzyme-linked immunosorbent assay are useful in predicting severity of adnexal adhesion.

The aim of this study was to investigate the relationship between chlamydia infection and adnexal adhesion. A total of 131 infertile women who were otherwise asymptomatic underwent chlamydia antibody testing and laparoscopy. These women had additional infertility factors. Serum concentration of anti-Chlamydia trachomatis immunoglobulins G and A were determined prospectively by means of an enzyme-linked immunosorbent assay (ELISA). Results were compared with the tubal patency and severity of adnexal adhesion. Sensitivity, specificity, positive and negative predictive value, and likelihood ratios of anti-C.trachomatis antibody titres for the presence of adnexal adhesion were calculated. Patients who were positive for chlamydia antibody had a significantly higher incidence of tubal occlusion than those who were negative (47.1 versus 25.0%). Adnexal adhesion scores were significantly higher in the patients who were positive for chlamydia antibody than those in patients who were negative (17.1 versus 8.5). Adnexal adhesion scores were significantly correlated with anti-chlamydia antibody titre by ELISA [immunoglobulin (Ig) G: r = 0.60, Ig A: r = 0.61]. As the antibody titre by ELISA rose, the specificity, positive predictive value and the positive likelihood ratio all increased. In conclusion, C.trachomatis antibody testing is a simple and inexpensive means of predicting pelvic damage and laparoscopic examination may be recommended for patients with high anti-C.trachomatis antibody titres by ELISA.

Adnexal Diseases↗

PubMed1996

Interaction of ganglioside with specific peptide sequences as a mechanism for the modulation of calmodulin-dependent enzymes.

We examined the interaction between gangliosides and synthetic peptides of calmodulin (CaM)-dependent enzymes to confirm the hypothesis that interaction between gangliosides and the CaM-like site (CLS) of the enzyme is a mechanism for the modulation of the enzyme activity by gangliosides. Gangliosides, GD1b, GT1b, and GD1a, inhibited the activity of CaM-independently activated cAMP-phosphodiesterase and their inhibition was cancelled by a peptide consisting of 17 amino acid residues of a plasma membrane Ca(2+)-pump CLS, suggesting the involvement of the interaction between the peptide and the gangliosides. The peptide of an assumed CLS of phosphodiesterase also cancelled the inhibition. On the other hand, the gangliosides interacted with synthetic CaM-binding site (CBS) peptides of phosphodiesterase, calcineurin, Ca(2+)-pump, and Ca2+/calmodulin-dependent protein kinase II. Moreover, gangliosides GM3 and LM1, that activate but do not inhibit phosphodiesterase, interacted with the CBS peptides, whereas they did not bind to CLS peptides. On the basis of these new findings, we propose a revised model for the ganglioside-mediated modulation of CaM-dependent enzymes, i.e. without CaM, gangliosides bind to CBS and thus stimulate the enzyme activity, acting like CaM. At higher concentrations, they bind to CLS of the enzymes as well and inhibit the activity, acting like the CBS of the enzyme.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1996

Replication protein-A mediates the association of calf thymus DNA polymerase alpha-DNA primase complex with guanine-rich DNA sequence.

We have shown that calf thymus DNA polymerase alpha-DNA primase complex (pol alpha-primase) preferentially binds to pyrimidine-rich sequences and initiates RNA primer synthesis [Suzuki, M. et al. (1993) Biochemistry 32, 12782-12792]. Here we tested the association of pol alpha-primase with a guanine-rich DNA fragment (SVG, 30-mer) containing in vivo initiation sites of simian virus 40 DNA replication. While pyrimidine-rich fragment (CTPPS 1, 30-mer), that is a preferred sequence for calf thymus DNA primase, was well co-precipitated with pol alpha-primase using anti-pol alpha antibody, SVG was hardly precipitated under the same conditions. Competition studies in either gel-retardation assay or during de novo DNA synthesis by pol alpha-primase demonstrated that the interaction of pol alpha-primase with SVG was much weaker than that with CTPPS-1. On the other hand, replication protein-A (RP-A) could bind SVG, although less efficiently than CTPPS 1. After preincubation with RP-A, SVG could bind pol alpha-primase that was immobilized on Sepharose beads. The simian virus 40 large T antigen also enhanced association of SVG to pol alpha-primase, while Escherichia coli single-stranded DNA-binding protein did not. However, pol alpha-primase, bound to SVG in the presence of RP-A, failed to synthesize RNA primers. When SVG was extended 10 nucleotides at its 5'-end, pol alpha-primase synthesized trace amounts of RNA primers, and this activity was stimulated more than 10-fold by adding RP-A. These results suggest a new role for RP-A, i.e., as a molecular tether that allows pol alpha-primase to bind guanine-rich regions of DNA in order to initiate RNA primer synthesis.

Animals↗

PubMed1996

Diagnostic utility of endoscopic ultrasonography for preoperative rectal cancer staging estimation.

The preoperative staging accuracy of endoscopic ultrasonography (EUS) was assessed in 38 rectal cancer patients who underwent rectal EUS and curative surgery from July 1992 to September 1994. We used a GF-UM20 instrument with both 12- and 7.5-MHz transducers. Compared with the histological findings, the diagnostic accuracy rate for EUS was 76% (29/38) for the invasion depth and 85% (sensitivity) and 72% (specificity) for level one lymph node metastasis, resulting in an overall preoperative staging accuracy of 74% (28/38). The diagnostic accuracy of invasion depth was poor (only 45%: 5/11) in cases shown histologically to be a1 (tumor invasion through muscularis propria into parietal fat), but ranged from 90 to 100% when the a1 cases were excluded. The diagnostic accuracy for level one lymph node metastasis was proportional to the nodal size. The size of lymph nodes that had been diagnosed as metastatic and non-metastatic (P < 0.05) differed significantly. Eighteen (86%) of the 21 metastatic nodes with histologically massive invasion were detected preoperatively by EUS. Eight of the 11 undetected metastatic nodes were either less than 4 mm in diameter or showed only slight invasion. Most (81%) of the level one metastatic nodes larger than 5 mm were found. The worst preoperative staging diagnostic accuracy was for stage II cases (63%: 5/8), and in four of the 10 misdiagnosed cases, the stage was underestimated due to slight nodal invasion or skip metastasis (2 cases each). Although it was difficult to diagnose nodal metastasis correctly in these cases, preoperative staging using EUS was considered useful for diagnosing almost 80% of our rectal cancer cases.

Humans↗

PubMed1996

An early phase II study of etoposide (VP-16) in advanced gastric cancer.

An early phase II study was conducted to evaluate the anti-tumor effects and toxicity of etoposide in patients with unresectable or relapsed advanced gastric cancer. From April 1991 to December 1992, 13 patients were enrolled into this study; one was subsequently considered ineligible. Before enrollment, all the patients had been treated with chemotherapy which did not include etoposide. Etoposide (100 mg/m2/day) was administered as an intravenous infusion over 120 min for five consecutive days and was repeated every four weeks. Seven patients received one course of this therapy and the remaining five received two. No patient showed a complete or a partial response. No change and progressive disease were observed in three and nine patients, respectively. The clinical toxicities (grade 3-4; WHO) of leukocytopenia, anemia and alopecia occurred in 50, 42, and 42% of the patients, respectively. We conclude that this dose of etoposide administered according to the present schedule is ineffective in previously treated patients with advanced gastric cancer.

Adenocarcinoma↗