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Biomedical subjects

S Hidaka

Publications and source records attributed to S Hidaka.

At least 91 records · Page 5Linked to original sources
PubMed1997

Competitive enzyme immunoassay for bovine growth hormone.

We developed an enzyme immunoassay (EIA) for bovine GH (bGH) which is based on indirect competitive immunoassay in culture medium from a bovine pituitary cell culture. 40 microliters cell culture samples (or bGH standard) and bGH antibody (rabbit anti-bGH) were added to the 96 well microplate coated with secondary antibody (Goat anti-rabbit IgG), and incubated for 24 h at 37 degrees C. Biotin-label bGH was added and incubated further for 24 h at 37 degrees C, and biotinylated bGH was linked with streptoavidin-peroxidase. Substrates for peroxidase were added to the plate and incubated for 1 h at 4 degrees C. The enzyme reaction was stopped with 4N H2SO4, and the absorbency at 450 nm was measured with an ELISA Reader. The coefficients of intra-assay and inter-assay variations were 4.13 approximately 7.59% and 3.71 approximately 8.27%, respectively. The regression equation and correlation coefficients with the radioimmunoassay (RIA) were y(RIA) = 1.9986 x (EIA) - 1.3921 and 0.9701 (n = 27), respectively. Collectively, the present assay provides a reliable alternative to RIA and offers the major advantage of eliminating radioactive reagents and counting equipment.

Animals↗
PubMed1997

Effect of mesenteric venous volatile fatty acids (VFA) infusion on GH secretion in sheep.

The effects of mesenteric venous infusion of acetate, propionate and butyrate mixture (20.3, 40.5 and 81.0 micromol kg[-1] min[-1] over 4 h) on the secretion of GH was examined to investigate the effects of an increase in portal volatile fatty acids (VFA) on GH secretion in relation to inhibition of GH secretion after feeding in sheep. The mesenteric venous infusion at the rate of 40.5 micromol kg(-1) min(-1) increased the portal plasma VFA concentration within the approximate physiological range after feeding. Plasma GH was noticeably suppressed only at the infusion rate of 81.0 micromol kg(-1) min(-1) and the change in the mean concentration from the base line was significantly less than in the control. Although GRF injection rapidly increased plasma GH, the change in the mean concentration from the base line tended to suppress only at the infusion rate of 81.0 micromol kg(-1) min(-1). Plasma FFA was suppressed in a dose-dependent manner after VFA infusion. The change in the mean concentration from the base line was significantly suppressed only at the infusion rate of 81.0 micromol kg(-1) min(-1) relative to the control infusion, but plasma glucose was unchanged by VFA infusion. It is concluded that because the increase in the portal plasma VFA concentration within the range of feeding did not suppress GH secretion, VFA absorbed by the digestive tract may not play a significant role in suppressing GH secretion after feeding in sheep.

Animals↗
PubMed1997

Effects of muscarinic and adrenergic blockade on growth hormone secretion induced by growth hormone-releasing peptide-2 (GHRP-2) in ovariectomized ewes.

This study was performed to investigate whether the blockade of cholinergic muscarinic and adrenergic pathways was involved in the GH-releasing effect of GH-releasing peptide-2 (GHRP-2) in ovariectomized ewes. Cholinergic muscarinic antagonist, atropine (0.2 mg/kg, i.v., 15 min before GHRP-2 administration) blunted the GH secretion caused by GHRP-2 (12.5 microg/kgBW). alpha-Adrenergic antagonist phentolamine (15 microg/kgBW x min, infusion from -15 to 30 min) did not affect the GH response to GHRP-2, and beta-adrenergic antagonist propranolol (0.25 mg/kgBW, i.v., 15 min before GHRP-2 administration) did not suppress the GHRP-2-induced GH release. These results showed that cholinergic muscarinic antagonist agent, atropine, exerts an inhibitory effect on GHRP-2-induced GH secretion in ovariectomized ewes.

Adrenergic Antagonists↗
PubMed1997

Mechanisms of action of growth hormone-releasing peptide-2 in bovine pituitary cells.

We conducted this study to investigate the mechanisms of action of growth hormone-releasing peptide-2 (D-Ala-D-beta Nal-Ala-Trp-D-Phe-Lys-NH2; GHRP-2) in bovine anterior pituitary primary cell culture. Doses of GHRP-2 from 10(-13) to 10(-7) M) increased (P < .05) GH secretion. The GHRP-2 (10(-7) M) and GH-releasing factor (GRF; 10(-7) M) administered together had an additive effect on the release of GH (P < .05). Somatostatin (1 microM) decreased GH secretion in response to GHRP-2 and(or) GRF (P < .05). Secretion of GH in response to GHRP-2 was blocked (P < .01) by a GRF receptor antagonist (.1 microM). Nifedipine (10 microM), a voltage-dependent Ca2+ channel blocker, inhibited (P < .01) GHRP-2-stimulated GH release. The GH release in response to GHRP-2 and 4 beta-phorbol-12-myristate-13-acetate (10(-7) M), a protein kinase C activator, was additive (P < .01). Forskolin (30 microM), a cAMP elevating agent, further stimulated (P < .01) the GH release in response to GHRP-2. Bovine GH concentrations in culture media were assayed by indirect competitive enzyme immunoassay. These results showed that GHRP-2 1) stimulates GH secretion from bovine pituitary cells, 2) may partially act via GRF receptor, 3) has GH secretion activity caused by Ca2+ influx via Ca2+ channels, and 4) may increase GH secretion via protein kinase C and cAMP pathways.

Animals↗
PubMed1997

No desensitization of the growth hormone (GH) response between GH-releasing peptide-2 and GH-releasing factor in calves.

We investigated the desensitization caused by growth hormone (GH)-releasing peptide-2 (D-Ala-D-beta Nal-Ala-Trp-D-Phe-Lys-NH2; GHRP-2) in vivo using calves. The GHRP-2 (12.5 micrograms.kgBW-1.h-1) or GH-releasing factor (GRF; .125 microgram.kgBW-1.h-1) were infused for 180 min into four calves, each followed by either GHRP-2 (12.5 micrograms/kg BW) or GRF (.125 microgram/kg BW) injection after 60 min. All treatments were given to all of the calves. The continuous infusion of GHRP-2 did not attenuate the GH secretion caused by a GRF bolus, and vice versa. Continuous exposure to GHRP-2 attenuated the GH secretion caused by a GHRP-2 bolus. In an additional experiment, two repetitive injections of GHRP-2 (12.5 micrograms/kg BW) at 1-, 2-, 3-, or 4-h intervals were administered. Attenuation of the GH response caused by GHRP-2 was maintained until 4 h. These results suggest that GHRP-2 is not cross-desensitized with GRF and that the mechanisms by which they cause GH release may be different in calves.

Animals↗
PubMed1997

Vesnarinone exhibits antitumor effect against myeloid leukemia cells via apoptosis.

Vesnarinone is a positive inotropic agent used for treating congestive heart failure. We evaluated its ex vivo effects on myeloid leukemia cell lines and primary acute myelogenous leukemia cells. Vesnarinone inhibited the incorporation of radiolabeled thymidine by a myeloid cell line, HL60, in a dose-dependent manner at concentrations ranging from 0.1 to 30 microg/mL. A maximum 40% suppression was seen at a concentration of 10 microg/mL. Determination of viable cell counts by trypan blue dye exclusion method demonstrated vesnarinone to be cytocidal for HL60 cells. Vesnarinone induced DNA fragmentation as detected by electrophresis in HL60 cells after 72-hour culture; this effect was not inhibited by G-CSF. The apoptosis induced by vesnarinone was also detected by the in situ end-labeling method. Northern blot analysis showed a reduction of c-myc mRNA expression in HL60 cells by vesnarinone. However, immunostaining assay showed no change in the expression of Fas and Bcl-2 proteins. We next examined the effect of vesnarinone on primary myeloid leukemia cells derived from 10 patients: 3 cases of M1, 2 of M2, 3 of M3, 1 of M4, and 1 of M6, by the French-American-British classification. Vesnarinone inhibited the incorporation of thymidine in all cells, with a mean suppression of 58.1%. DNA electrophoresis showed induction of DNA fragmentation in cultured cells with vesnarinone for 72 hours in 8 of the 10 patients with primary leukemia. However, bone marrow mononuclear cells from healthy controls showed no growth suppression or DNA fragmentation in response to vesnarinone. These results suggest that vesnarinone may be useful in treating myeloid leukemia.

Adult↗
PubMed1997

Human T lymphotropic virus-type I Tax induction of CD21/Epstein-Barr virus receptor expression on T cells and its significance in leukemogenesis of adult T cell leukemia.

CD21, which is expressed on B cells, is also expressed on human T lymphotropic virus-type I (HTLV-I)-infected T cell lines. CD21 also serves as a receptor of Epstein-Barr virus (EBV). We evaluated the mechanism of CD21 induction on HTLV-I-infected T cells and its clinical significance in the leukemogenesis of adult T cell leukemia (ATL). CD21 induction was detected at very low levels in T cell lines (Jurkat and CEM cells), and in non- or low-Tax-producing HTLV-I-infected T cell lines (Oh13T, S1T, and Su9T01 cells). In contrast, marked induction of CD21 was detected in high-Tax-producing HTLV-I-infected T cell lines (K3T, F6T, and MT-2). A Jurkat T cell clone stably transfected with tax-expressing cDNA expressed a significant amount of CD21 on the cell surface. These results strongly suggest that HTLV-I Tax induces CD21 on T cells. On two-color analysis, CD21 expression was detected in CD4+ T cells of the primary ATL cells from a subset of patients, suggesting that EBV infection may be associated with the leukemogenesis of ATL, at least in part. However, no genome of EBV was detected in the genomic DNA of six HTLV-I-infected T cell lines or the primary ATL cells separated from all patients, indicating the irrelevance of EBV infection to ATL leukemogenesis.

DNA, Viral↗
PubMed1996

Relation of autonomous and interleukin-2-responsive growth of leukemic cells to survival in adult T-cell leukemia.

We examined autonomous and interleukin-2 (IL-2)-responsive growth activities of leukemic cells derived from peripheral blood, as well as several clinical manifestations, including serum lactate dehydrogenase (LDH) level, of 35 patients with adult T-cell leukemia (ATL) to determine whether these properties were related to prognosis. Growth activities were measured by [3H]-thymidine incorporation of the cells after 24 hours' culture with or without exogenous IL-2. Both autonomous and IL-2-responsive growth activities were higher in the patients than in healthy controls and were significantly correlated with each other (P < .0001, r = .956). Both higher growth activities were significantly associated with shorter survival times (P = .0042, r = .472 and P = .0117, r = .421, respectively). An increased serum LDH value was also significantly associated with shorter survival times (P = .0011, r = .530), but corrected calcium level, sex, white blood cell count, or age were not. These results strongly suggest that both growth activities of primary tumor cells, in addition to the serum LDH value, are prognostic determinants in ATL. We propose a new prognostic classification combining LDH values and autonomous growth activity into three groups: (1) high growth activity and high LDH; (2) high growth activity and low LDH, or low growth activity and high LDH; and (3) low growth activity and low LDH, which showed a significant relationship to survival time (P = .0014; the median survival time for each group was 39, 94, and 340 days, respectively).

Adult↗
PubMed1996

Effects of indium and iron ions on in vitro calcium phosphate precipitation and crystallinity.

The elution characteristics of indium and iron ions from six kinds of dental casting alloys were studied in vitro. A certain amount of indium (0.01-1.70 mg/cm2) was solubilized from the surface of only one prosthetic semiprecious brand (Miro Bright) in either 1% lactic acid or 0.05% hydrochloric acid solutions. The elution of iron was below the detection limit or < 0.01 mg/cm2. We also studied the stimulatory effects of indium and ferric ions on the calcium phosphate precipitation in the absence and presence of an inhibitor (phosvitin, a phosphoprotein purified from egg yolks). Indium and ferric ions promoted the reaction, and their stimulatory effects were stronger than the inhibitory effects of phosvitin (250 micrograms/ml). These facts suggest that indium, but not iron, could be eluted into the mouth, and that the eluted indium may stimulate the formation of oral calcium phosphate precipitates, counteracting the inhibition by saliva-derived phosphoproteins. The effects of these metal ions on calcium phosphate precipitates were also studied using both X-ray diffractometry and infrared spectrophotometry. It was shown that both indium and ferric ions decreased the grade of crystallinity of the calcium phosphate precipitates (hydroxyapatite).

Chelating Agents↗
PubMed1996

Genomic structure of the rice aldolase isozyme C-1 gene and its regulation through a Ca 2+ -mediated protein kinase-phosphatase pathway.

Complementary and genomic DNA clones coding for aldolase C-1, the fourth-type isozyme of aldolase in rice Oryza sativa L., have been characterized. The organization of the gene is quite similar to those encoding rice aldolase C-a and a maize cytoplasmic-type aldolase, in that introns are located in the same position. Amino acid sequences are highly conserved among cytoplasmic aldolases in plants. Expression of the gene in rice callus is activated by a protein phosphatase inhibitor okadaic acid, and is inhibited in the presence of thapsigargin, a reagent which increases calcium influx into the cytoplasm. The inhibition is rescued by the simultaneous addition of protein kinase inhibitor H-7. Thus, it is suggested that expression of the aldolase C-1 gene is regulated through a signal transduction pathway involving a Ca 2+ -mediated protein kinase-protein phosphatase system.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1996

Interleukin-2-mediated growth of leukemic cells in lymph nodes of patients with adult T-cell leukemia/lymphoma.

We investigated the effect of interleukin-2 (IL-2) on tumor growth of primary adult T-cell leukemia/lymphoma (ATL) cells in biopsied lymph node cells obtained from 14 patients (seven [corrected] with acute-type disease, one with chronic-type disease and six [corrected] with lymphoma-type disease). Biological activity of IL-2 in culture supernatants of the cells was detected in six out of 12 cases. The IL-2 mRNA in the lymph node cells was detected in four out of nine patients by northern blotting. However, it was detected in all nine patients examined by reverse polymerase chain reaction (PCR) method. Lymph node cells from 12 out of 14 patients showed a high or moderate proliferative response to IL-2; the remaining two patients showed a slight response. These results suggest that malignant growth of primary tumor cells in lymph nodes may be associated with the IL-2-IL-2 receptor system in patients with ATL more frequently than had been previously thought.

Adult↗
PubMed1996

Effects of a rhubarb (Rhei rhizoma) solution and its fractions on the formation of calcium phosphate precipitates.

Inhibitory effects of a rhubarb (Rhei rhizoma) solution and its fractions on the formation of calcium phosphate precipitates were studied. The rhubarb solution inhibited both the amorphous calcium phosphate (ACP) formation and the rate of hydroxyapatite (HAP) transformation, and extended the induction time. When the solution was fractionated using membrane filters, a filtrate with the molecular weight between 3 and 10 kDa (with 2/3 recovery of polyphenols) was found to be responsible for both the ACP formation and the extension of the induction time. Another filtrate with the molecular weight below 3 kDa (with 1/3 recovery of polyphenols) may be responsible for the inhibition of both the ACP formation and the rate of HAP transformation, and the extension of the induction time. When the extract of rhubarb was fractionated using a Sephadex LH-20 column chromatography, fraction IV greatly inhibited the formation of calcium phosphate precipitates, while fractions I, II and III slightly inhibited that reaction. Our finding suggests that fraction IV may contain useful substance(s) for the prevention of oral calcium phosphate precipitation (calculus formation). However, strong calcium chelating properties would limit the concentration that could be safely employed.

Analysis of Variance↗
PubMed1996

Inhibitory effects of 1-hydroxyethylidene-1,1-bisphosphonate and Chinese traditional (kampo) medicines on calcification of the heart and tongue in DBA/2NCrj mice.

The effects of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) and two Chinese traditional (Kampo) medicines, Dai-saiko-to and Saiko-ka-ryukotsu-borei-to on spontaneous soft tissue (heart and tongue) mineralization in DBA/2NCrj mice were studied. These agents were given orally for 4 weeks to DBA/2NCrj mice. After 2 weeks of administration in the heart, 0.006 and 0.03% (w/v) HEBP decreased calcium content by 90 and 30%, respectively, while 0.27 and 2.7 mg/ml Dai-saiko-to reduced calcium content by 30 and 45%, respectively. Saiko-ka-ryukotsu-borei-to (0.27 mg/ml) reduced both calcium and phosphorus content by 50 and 35%, respectively. However, their inhibitory effects on the heart were not observed after 4 weeks of administration. The compounds delayed the onset of increases of bulk calcium and phosphorus content. In the tongue, at 4 weeks, 0.006 and 0.03% (w/v) HEBP reduced calcium content by 30 and 45%, respectively, while two Kampo medicines (at both concentrations used) significantly reduced the content of calcium (by 27-79%) and phosphorus (by 24-32%). These results strongly suggest that two Kampo medicines as well as HEBP may be useful in preventing and curing soft tissue calcification.

Animals↗
PubMed1996

Characteristics of growth hormone secretion responsiveness to growth hormone-releasing peptide-2 (GHRP-2 or KP102) in calves.

This study was conducted to determine the effects of acute and chronic administration of GH-releasing peptide-2 (D-Ala-D-beta Nal-Ala-Trp-D-Phe-Lys-NH2, GHRP-2 or KP102) on GH responsiveness in male Holstein calves. In the dose response study of acute administration, six calves were injected iv with saline or 6.25, 12.5 and 25.0 micrograms/kg body weight (BW) of KP102. The GH AUC (area under curve, ng/ml.min, mean +/- SEM) for 60 min was significantly increased with 6.25 (676.3 +/- 125.6), 12.5 (1574.8 +/- 318.0) and 25.0 (1578.7 +/- 214.6) micrograms/kgBW of KP102 than with saline (78.6 +/- 36.1) (P < 0.01). GH responses were decreased by multiple injections of 12.5 micrograms/kgBW KP102 at every 2 h for 8 h. The GH AUC for 60 min was decreased from the first injection (1162.9 +/- 313.3) to the second injection (604.7 +/- 131.9), but the response was significantly higher for the first and second injections than the third (304.4 +/- 173.1) and fourth injections (320.7 +/- 144.2) (P < 0.05). In the chronic administration, 8 calves were implanted subcutaneously with osmotic pumps (Alzet pump). Each of the 4 calves was given with 12.5 micrograms/kgBW per hour KP102 and the other 4 calves served as the control. During the 14 day period, average daily gain was significantly increased (36.4%) over the control (P < 0.05). Food efficiency was not significant, but numerically higher (29.4%) than the control. The plasma GH concentration was not increased by chronic administration of KP102, but IGF-I appeared to increase in KP102-treated calves more than the control. These results suggest that the synthetic KP102 can be used for enhancing the growth performance in domestic animals.

Animal Husbandry↗
PubMed1996

[A patient with Goodpasture's syndrome revealed a poor prognosis regardless of receiving intensive therapy from an early stage after onset].

Goodpasture's syndrome has been reported as a disease that has a favorable prognosis when the patient receives intensive immunosuppressive drug-therapy from an early stage after onset. The present report describes a 50-year-old woman, who exhibited progressive renal failure accompanied by pulmonary hemorrhage, and an increase in serum level of antiglomerular basement membrane (GBM) antibody. Initial histological examination of a renal specimen indicated a severe fibrocellular crescentic glomerulonephritis with a linear deposition of Ig-G and C3 along the glomerular capillary wall. The patient was thus diagnosed as having Goodpasture's syndrome. Therapy with pulse treatment of steroid (corticosteroid hormone), immunosuppressive agents, or plasma-exchange for the removal of anti-GBM antibody was adopted a week after the clinical onset. However, histological amelioration of the glomeruli did not occur with this treatment in the second biopsy, while glomerular damage advanced progressively. In contrast to other patients with Goodpasture's syndrome, our case revealed an unfavorable outcome regardless of receiving intensive therapy from an early period after onset, which suggests that more intensive therapy of another approach to this patient may have been necessary.

Anti-Glomerular Basement Membrane Disease↗
PubMed1995

The promoter from the rice nuclear gene encoding chloroplast aldolase confers mesophyll-specific and light-regulated expression in transgenic tobacco.

The rice genome contains at least four separate loci that encode aldolase isozymes. Among these, the aldolase P (AldP) gene, a nuclear gene coding for chloroplast aldolase, is expressed predominantly in the leaf blade mesophyll cells in rice. To dissect promoter elements that regulate such tissue- or cell type-specific expression, we constructed various AldP promoter-beta-glucuronidase (GUS) fusion genes and transferred them into Nicotiana tabacum (tobacco) plants. Analysis of GUS activities in the transgenic tobacco revealed the presence of at least two elements within 2.0 kb AldP promoter region. One is located within the segment from position -2.0 kb to -1.2 kb and acts as a negative element. The other is a positive element located between -1.2 kb and -0.31 kb that confers developmentally regulated, mesophyll cell-specific expression. In addition, the 1.2 kb rice promoter segment flanking the transcription start site contains an element(s) that serves as target for light induction in tobacco. The results suggest that the AldP gene promoter of rice, a monocot promoter, can function in an essentially physiological manner in the dicot tobacco plant.

Blotting, Northern↗
PubMed1995

Production of waxy (amylose-free) wheats.

The Waxy (Wx) protein has been identified as granule-bound starch synthase (GBSS; EC 24.1.21), which is involved in amylose synthesis in plants. Although common wheat (Triticum aestivum L.) has three Wx proteins, "partial waxy mutants" lacking one or two of the three proteins have been found. Using such partial waxy mutants, tetra- and hexaploid waxy mutants with endosperms that are stained red-brown by iodine were produced. Both mutants showed loss of Wx protein and amylose. This is the first demonstration of genetic modification of wheat starch.

Electrophoresis, Polyacrylamide Gel↗