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S Ohta

Publications and source records attributed to S Ohta.

At least 469 records · Page 26Linked to original sources
PubMed1994

C-type natriuretic peptide stimulates secretion of growth hormone from rat-pituitary-derived GH3 cells via a cyclic-GMP-mediated pathway.

Although C-type natriuretic peptide (CNP) has been shown to exist at the highest concentration in the anterior pituitary in rat tissues, its physiological role(s) there is (are) not clear. In this study, we report a novel function of CNP examined with anterior pituitary-derived cell lines, GH3 and AtT20/D16v-F2. Both CNP and atrial natriuretic peptide (ANP) increased cellular cGMP levels in both cell lines in dose-dependent manners. CNP, but not ANP, stimulated growth hormone (GH) release from GH3 cells. In contrast, neither ANP nor CNP had any significant effect on the corticotropin release from AtT20/D16v-F2 cells. An activator for cGMP-dependent protein kinase (cGK), dibutyryl cGMP, mimicked the stimulation of GH release from GH3 cells by CNP. Constitutive GH release from GH3 cells was greatly diminished in the presence of inhibitors for cAMP-dependent protein kinase, while stimulative GH release by CNP was not affected. However, inhibitors which can block cGK almost completely diminished the stimulative effect of CNP. An inhibitor for protein kinase C did not show any effect on either constitutive or CNP-stimulative GH release. Our observations indicate that the stimulation of GH release from GH3 cells by CNP is mediated mainly by the cGK signal-transduction pathway, not by cAMP-dependent protein kinase or protein kinase C, through a CNP-specific receptor (possibly ANP-B receptor). Thus, CNP may act as a local modulator in the anterior pituitary.

Animals↗
PubMed1994

Expression cloning of a novel alpha 1,3-fucosyltransferase that is involved in biosynthesis of the sialyl Lewis x carbohydrate determinants in leukocytes.

The sialyl Lewis x (NeuAc alpha 2-3Gal beta 1-4(Fuc alpha 1-3)Glc-NAc) determinants serve as ligands in the selectin-mediated adhesion of leukocytes to activated endothelium or platelets. In our efforts to identify glycosyltransferases involved in the biosynthesis of those ligands, we achieved expression cloning of a novel human alpha 1,3-fucosyltransferase termed Fuc-TVII from a THP-1 cDNA library by enrichment of the Namalwa cells highly expressing that determinant with a fluorescence-activated cell sorter. Expression of the COOH-terminal catalytic domain of Fuc-TVII showed an alpha 1,3-fucosyltransferase activity for a type II oligosaccharide with a terminal alpha 2,3-linked sialic acid among various acceptors, consistent with that in vivo acceptor specificity. Alignment of the primary sequences of five alpha 1,3-fucosyltransferases and assignment of the chromosomal location of Fuc-TVII gene, together with that acceptor specificity, indicate that Fuc-TVII consists of a unique class of the alpha 1,3-fucosyltransferase family. Determination of the expression levels of these alpha 1,3-fucosyltransferases in various cells revealed that both Fuc-TVII and a myeloid fucosyltransferase Fuc-TIV were significantly expressed in myeloid lineage cells. Fuc-TVII-transfected Namalwa cells exhibited significant binding to E-selectin in contrast to little binding of the Fuc-TIV-transfected cells. These results suggest that Fuc-TVII may participate in the biosynthesis of the selectin ligands.

Antibodies, Monoclonal↗
PubMed1994

Ouabain-resistant non-small-cell lung-cancer cell line shows collateral sensitivity to cis-diamminedichloroplatinum(II) (CDDP).

We have reported that the cellular uptake of cis-diamminedichloroplatinum(II) (CDDP) was inhibited by an Na+,K(+)-adenosine triphosphatase (ATPase) inhibitor, ouabain, in a human non-small-cell lung-cancer cell line, PC-14, but not in its CDDP-resistant cell line, PC-14/CDDP. [3H]Ouabain binding of PC-14/CDDP was about 50% lower than that of PC-14. Accordingly, we speculated that a decrease in Na+,K(+)-ATPase activity in PC-14/CDDP might contribute to the decrease in cellular CDDP accumulation. To clarify the relationship between the activity or expression of Na+,K(+)-ATPase and cellular CDDP accumulation, we established an ouabain-resistant non-small-cell lung-cancer cell line (PC-14/OB300), which showed 1.9-fold resistance to the cytotoxicity of ouabain. Interestingly, this cell line was 4.2-fold more sensitive to CDDP than PC-14. The accumulation of CDDP in PC-14/OB300 was increased to 2.7-fold that in PC-14. This elevation of CDDP accumulation was not considered to be caused by increased passive diffusion, because the accumulation of CDDP in PC-14/OB300 was also inhibited by ouabain compared to PC-14. As one of the indices of Na+,K(+)-ATPase activity, we determined cellular 86Rb+ influx rates. The 86Rb+ influx rate was 1.5-fold higher in PC-14/OB300 and fell to 0.7-fold in PC-14/CDDP compared with PC-14. The mRNA expression of Na+,K(+)-ATPase was increased in PC-14/OB300 and decreased in PC-14/CDDP. There was no difference in cellular [3H]ouabain binding between PC-14/OB300 and PC-14. It is possible that Na+,K(+)-ATPase of PC-14/OB300 has a different affinity for ouabain from that of PC-14. Our results suggest that the enzyme activity or the level of expression of Na+,K(+)-ATPase may contribute to the cellular uptake of CDDP and determine the sensitivity to CDDP.

Adenocarcinoma↗
PubMed1994

Nuclear but not mitochondrial genome involvement in human age-related mitochondrial dysfunction. Functional integrity of mitochondrial DNA from aged subjects.

The role of mtDNA and nuclear genome in human aging was examined by their intercellular transfer using skin fibroblasts and mtDNA-less HeLa cells (rho o-HeLa cells). We found in vivo age-related reductions in the activity of cytochrome c oxidase in human skin fibroblasts obtained from 16 donors of various ages (0-97 years). The abnormality in mitochondria of the aged donors was not attributable to either decrease in the copy number of mtDNA molecules or increase in the copy number of deletion mutant mtDNA molecules, but to significant decrease in overall polypeptide synthesis in the mitochondria. However, intercellular mtDNA transfer experiments showed that fibroblast mtDNA from elderly donors is functionally intact. By contrast, intercellular transfer of HeLa nuclei to fibroblasts from aged donors restored cytochrome c oxidase activity, suggesting that the age-related phenotype was nuclear recessive. However, during subsequent cultivation of these hybrids, the activity gradually reduced again, associated with gradual chromosome loss. These observations support the idea that accumulation of nuclear recessive somatic mutations, but not mtDNA mutations, is responsible for the in vivo age-related mitochondrial dysfunction observed in human skin fibroblasts.

Aged↗
PubMed1994

Immunoglobulin class switch of anti-ganglioside monoclonal antibody from IgM to IgG.

Ganglioside GM2, which is one of the major gangliosides expressed on cell surface of neuroectodermal-origin human tumors, has been focused on as a target molecule for passive immunotherapy. One of the problems in this area was that monoclonal antibodies (mAbs) raised against GM2 were of IgM class even if donors of B cells were varied in mouse, rat or human. We stimulated two kinds of mice hybridomas having membrane-bound anti-GM2 IgM on their surface with GM2 incorporated in synthetic liposomes in the presence of the mouse thymocytes to accelerate the class switch of immunoglobulins (Igs). After the stimulation, protein A-reactive clones were sorted out using a cell sorter. We finally isolated two class switch variants generating mouse IgG3, designated KM796 and KM750, from original hybridomas producing mouse IgM anti-GM2 mAbs, KM696 and KM697, respectively after over 20-time repetitions of the sorting. ELISA with 11 common gangliosides revealed that one of the variant, KM750, retained the same binding specificity to N-acetyl GM2 as that of the parental IgM, KM697. By ELISA using panel of anti-idiotype (Id) mAbs to anti-GM2 mAbs, KM750 was shown to retain the parental KM697 Id. Another variant KM796 almost lost its activity in purification process in acidic condition and changes in Id were suggested. In immunofluorescence assay, KM750 was confirmed to bind to GM2-expressing tumor cell lines. The class switch hybridoma has been stably cultured with the production of the IgG3-class mAb for more than 22 months.

Animals↗
PubMed1994

Transmission of maternal blood cells to the fetus during pregnancy: detection in mouse neonatal spleen by immunofluorescence flow cytometry and polymerase chain reaction.

Mouse embryos were transferred to allogeneic pseudopregnant foster mothers and the cells of the resultant neonates were analyzed for the expression of maternal major histocompatibility complex (MHC) antigens to elucidate maternal cell transmission to the fetus during pregnancy. Expression of maternal-type MHC antigens was detected in the spleen but not in the liver or thymus of the neonates in analyses by immunofluorescence flow cytometry and polymerase chain reaction. These findings provide evidence, on the molecular basis, that maternal blood cells are transmitted to the fetus through the placenta.

Animals↗
PubMed1994

Widespread tissue distribution of multiple mitochondrial DNA deletions in familial mitochondrial myopathy.

We used Southern blot analysis and the polymerase chain reaction to analyze the tissue distribution of multiple mitochondrial DNA (mtDNA) deletions in a 45-year-old man with familial mitochondrial myopathy-Southern blots showed two major types of abnormal mtDNA with approximately 4- and 8-kilobase deletions in the skeletal and extraocular muscles. The amount of muscle mtDNA with deletions correlated approximately with the severity of muscle involvement. The polymerase chain reaction showed multiple mtDNA deletions even in clinically asymptomatic tissues, the pattern of which differed with the type of tissue. Nucleotide sequences of several mtDNAs with deletions showed that the deletions were flanked by direct repeats consisting of 3 to 12 nucleotides. Leukocytes from the patient's affected sister and his mother exhibited the same mtDNA deletion pattern. Most of the same deletions were present in leukocytes obtained from the patient's father.

Adolescent↗
PubMed1994

Reduced secretion of IgA to skin surface of patients with atopic dermatitis.

To investigate whether the secretory form of immunoglobulin A (sIgA) was reduced on the skin surface in atopic dermatitis, the amount of sIgA present in sweat was measured in 40 patients with atopic dermatitis and in 50 healthy volunteers by attaching a cellulose membrane disk (10 x 10 mm) to the inner aspect of the upper arm skin for 24 hours. The secretory form of IgA, which was absorbed to the membrane and accumulated during the period of application, was revealed as dots by an enzyme immunoassay in which antibodies for IgA and for the secretory component were used. The density and number of dots (per mm2/day), which corresponded to the openings of eccrine excretory ducts, were determined with a densitometer. The mean amount of sIgA secreted by those patients was 3.86 +/- 0.71 pg/mm2/day (range, 0 to 21.17 pg/mm2/day), whereas that of the control subjects was significantly higher (p < 0.001), 16.79 +/- 2.80 pg/mm2/day (range, 0.79 to 133.77 pg/mm2/day). This may be related to the high incidence of bacterial and viral skin infections seen in patients with atopic dermatitis, and in addition, to the development of eczematous lesions through a defect in ridding the skin of allergens and/or microorganisms.

Adolescent↗
PubMed1994

Inhibition of type A monoamine oxidase by 2(N)-methyl-6,7-dihydroxyisoquinolinium ions.

In the human brain, monoamine-derived 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines and 1,2,3,4-tetrahydroisoquinolines have been identified and their enzymatic methylation into N(2)-methylisoquinolines has been also confirmed. N-methylated 6,7-dihydroxyisoquinolines were found to be oxidized into 6,7-dihydroxy-N-methylisoquinolinium ions. The effects of the isoquinolinium ions on type A and B monoamine oxidase were examined, using enzyme samples isolated from human brain synaptosomal mitochondria. 1,2-Dimethyl-6,7-dihydroxyisoquinolinium ion (N-methylsalsolinium ion) and 2-methyl-6,7-dihydroxyisoquinolinium ion (N-methylnorsalsolinium ion), were found to be potent inhibitors of type A monoamine oxidase. The inhibition was competitive to the substrate, while the isoquinolinium ions were much weaker inhibitors of type B and the inhibition was non-competitive to the substrate. Isoquinolinium ions without catechol structure, N(2)-methylisoquinolinium ion and 1,2-dimethylisoquinolinium ion also inhibited both type A and B monoamine oxidase. 1,2-Dimethylisoquinolinium was the most potent inhibitor among examined isoquinolines, followed by the N-methylsalsolinium ion. The activity-structure relationship of the isoquinolines with and without catechol structure was examined in terms of potency and selectivity of inhibition to type A and B monoamine oxidase. Catechol structure was found to increase the selectivity of inhibition to type A, as shown by comparison of N-methylsalsolinium ion with 1,2-dimethylisoquinolinium ion. N-Methylsalsolinium ion inhibited type A MAO more selectively than 1,2-dimethylisoquinolinium ion, which inhibited type A and type B with almost the sam values of the inhibitor constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1994

Risk factors for infection and immunoglobulin replacement therapy in adult nephrotic syndrome.

Infection has been recognized as an important cause of morbidity and mortality in children with nephrotic syndrome. However, the incidence and severity of infection and the mechanisms responsible for the increased susceptibility to infection are still unclear in adults. We studied 86 consecutive adult patients with nephrotic syndrome but no diabetic nephropathy. Risk factors for infection were evaluated by logistic regression analysis. Infections were found in 16 patients (19%), of whom six died of infection and two developed end-stage renal failure associated with infection. The relative risk for bacterial infection among patients with serum immunoglobulin G (IgG) levels below 600 mg/dL was 6.74 compared with that for patients with serum IgG levels over 600 mg/dL (95% confidence interval, 1.22 to 36.32; P = 0.029). In patients with serum creatinine levels over 2.0 mg/dL, the relative risk of bacterial infection was 5.31 compared with patients with serum creatinine levels below 2.0 mg/dL (95% confidence interval, 1.08 to 26.09; P = 0.040). Intravenous immunoglobulin (10 to 15 g) was administered prospectively every 4 weeks to 18 patients with serum IgG levels below 600 mg/dL until serum IgG levels increased to over 600 mg/dL. Administration of immunoglobulin resulted in a decreased rate of bacterial infections to a level equal to that in patients with endogenous levels over 600 mg/dL. These data indicate that hypogammaglobulinemia and renal insufficiency are independent risk factors for bacterial infection in adult patients with nephrotic syndrome. The effects of intravenous immunoglobulin suggest that maintenance of serum IgG levels over 600 mg/dL may reduce the risk of infection.

Adult↗
PubMed1994

Detection of urinary interleukin-8 in glomerular diseases.

To clarify the mechanism of neutrophil infiltration in glomerulonephritis, both urinary and plasma levels of a potent neutrophil chemotactic cytokine, interleukin-8 (IL-8), were measured in 40 healthy volunteers and 96 patients with various renal diseases. The plasma IL-8 levels were less than 16 pg/ml. The urinary IL-8 levels were elevated in several renal diseases including IgA nephropathy (17 of 43), acute glomerulonephritis (4 of 6), lupus nephritis (11 of 15), purpura nephritis (2 of 4), membranoproliferative glomerulonephritis (1 of 1), and cryoglobulinemia (2 of 2). IL-8 was detected immunohistochemically in diseased glomeruli, suggesting its local production. Elevated urinary IL-8 levels during the acute phase or exacerbations were found to be decreased during spontaneous or steroid pulse therapy-induced convalescence in all patients examined. The urinary IL-8 levels were higher in patients with glomerular leukocyte infiltration than in those without infiltration. Collectively, local production of IL-8 in diseased glomeruli might be involved in the pathogenesis of the glomerular diseases and measurement of IL-8 in the urine might be useful for monitoring the glomerular diseases.

Acute Disease↗
PubMed1994

Efficient transformation of rice (Oryza sativa L.) mediated by Agrobacterium and sequence analysis of the boundaries of the T-DNA.

A large number of morphologically normal, fertile, transgenic rice plants were obtained by co-cultivation of rice tissues with Agrobacterium tumefaciens. The efficiency of transformation was similar to that obtained by the methods used routinely for transformation of dicotyledons with the bacterium. Stable integration, expression and inheritance of transgenes were demonstrated by molecular and genetic analysis of transformants in the R0, R1 and R2 generations. Sequence analysis revealed that the boundaries of the T-DNA in transgenic rice plants were essentially identical to those in transgenic dicotyledons. Calli induced from scutella were very good starting materials. A strain of A. tumefaciens that carried a so-called 'super-binary' vector gave especially high frequencies of transformation of various cultivars of japonica rice that included Koshihikari, which normally shows poor responses in tissue culture.

Agrobacterium tumefaciens↗
PubMed1994

Carbohydrate-related regulation of the ethanol-induced increase in serum gamma-glutamyl transpeptidase activity in adult men.

The dietary influence on ethanol-induced increase in serum gamma-glutamyl transpeptidase (gamma-GTP) activity was studied in 2165 healthy men 18-85 y of age living in Nagano Prefecture, Japan. As ethanol consumption increased, the intake of cereals, potatoes, vegetables, milk and dairy products, oils, fruit, confections, and sugar decreased, whereas the intake of meat increased. These associations suggest that ethanol consumption led to the decrease in the intake of carbohydrate and vegetable fat. Serum gamma-GTP activity was found to be positively related to ethanol consumption and negatively related to the intake of sugar, fruit, and confections. The activity was the highest in those whose percent energy intake from carbohydrates was the lowest. Stepwise-multiple-regression analysis identified the three variables ethanol, sugar, and fruit, as the factors associated with the value of gamma-GTP activity: ethanol on the one hand increased the activity, whereas sugar and fruit on the other hand decreased the activity. Moreover, a lowered sugar intake augmented the ethanol-induced increase in the enzyme activity. These results suggest that sugar intake plays a role in the ethanol-induced increase in serum gamma-GTP activity.

Adult↗
PubMed1994

Free vascularized iliac osteomusculocutaneous flaps based on the lateral circumflex femoral system for repair of large mandibular defects.

A free vascularized iliac osteocutaneous flap based on the ascending and transverse branches of the lateral circumflex femoral system was studied by cadaveric investigation. These composite flaps were successfully used in 2 patients with both large mandibular and soft-tissue defects. The advantages of this flap are that (1) the distal portion of the flap is relatively thin, (2) the pedicle vessels are long and large, (3) the skin territory is extremely wide, (4) repositioning of the patient during the operation is unnecessary, (5) the flap can be elevated while the recipient mandibular region is resected by two teams because the donor site is far from the head and neck regions, (6) the donor scar is in an unexposed area and its location permits easy concealment, and (7) subtotal loss of the mandible can be reconstructed with the use of split crests from either side of the ilium because the external and the internal cortices are fed independently by the lateral circumflex femoral and the deep circumflex iliac systems. This appears to be a new concept for reconstruction of total mandibular loss.

Aged↗
PubMed1994

Free rectus femoris muscle transfer for one-stage reconstruction of established facial paralysis.

The free vascularized rectus femoris muscle graft with a long motor nerve was used for reconstruction of unilateral established facial paralysis in one stage. The pedicle vessels were anastomosed to the recipient vessels in the ipsilateral face, and the motor nerve of the muscle, which was led through the upper lip, was sutured to the contralateral facial nerve. The advantages of this one-stage reconstruction as compared with surgery involving second-stage reconstruction are that the reconstruction can be completed in one stage and that the period required for muscle refunctioning after surgery is short. The vascular supply of the rectus femoris muscle can emanate mainly from the lateral circumflex femoral artery. In our cadaveric study, five types of variation were found for origination of a nutrient artery of the muscle. The most common type was one in which the artery derived from the descending branch of the lateral circumflex femoral artery (39 percent). The motor nerve of the rectus femoris muscle is derived from the femoral nerve under the inguinal ligament and runs downward through the intermuscular space between the sartorius muscle and the iliopsoas muscle before entering the posteromedial part of the upper third of the rectus muscle. The advantages of using the rectus muscle are as follows: (1) safety and simplicity exist with one main large arterial supply for arterial anastomosis; (2) the length of the femoral nerve (more than 20 cm) is adequate for reaching the contralateral facial nerve for suturing; (3) a simultaneous operation by two teams is possible with the patient in the supine position; (4) the force and distance of contraction are appropriate to reanimate the face; (5) the rectus muscle can be separated as a segment with appropriate lengths, size, and power for replacing lost muscles in the face; (6) the tendinous fascia in both ends provides a reliable point for anchoring sutures, which provides firmer attachment; and (7) no loss of donor leg function occurs.

Adolescent↗
PubMed1994

An amino acid change in the non-structural NS2 protein of an influenza A virus mutant is responsible for the generation of defective interfering (DI) particles by amplifying DI RNAs and suppressing complementary RNA synthesis.

The mutated non-structural NS2 protein of an influenza A virus mutant, Wa-182, has been shown to be responsible for the production of defective interfering (DI) particles lacking the PA gene after a single cycle high-multiplicity infection. Using a subclone of Wa-182, A3/e-3, that inherited the Wa-182 phenotype but contained only a marginal amount of DI RNAs derived from the PA gene, we showed that replication of the PA genome RNA was suppressed primarily at the step of complementary RNA (cRNA) synthesis. On the other hand, the small amounts of DI RNA species present in the stock of A3/e-3 were shown to be replicated efficiently. These findings suggested that the suppression of cRNA synthesis of the PA gene was caused by preferential amplification of the DI RNAs. The suppression of PA gene cRNA synthesis subsequently resulted in suppression of both virion RNA synthesis and secondary transcription of the PA gene. Such aberrant replication of the PA gene was found to be attributable to an amino acid change in the NS2 protein at position 32, from isoleucine to threonine. These results suggest that the NS2 protein plays a role in promoting normal replication of the genomic RNAs by preventing the replication of short-length RNA species.

Cell Line↗