PubMed Health⌕ Search

Biomedical subjects

K Kitamura

Publications and source records attributed to K Kitamura.

At least 469 records · Page 26Linked to original sources
PubMed1996

Potentiation by apamin of histamine-stimulated catecholamine biosynthesis and tyrosine hydroxylase phosphorylation in cultured bovine adrenal chromaffin cells.

The effects of small-conductance Ca2(+)-activated K+ channel (SK channel) blocker, apamin, on histamine-stimulated catecholamine biosynthesis and tyrosine hydroxylase phosphorylation in cultured bovine adrenal chromaffin cells were investigated. Histamine (10(-10)-10(-6) M) stimulated [14C]catecholamine biosynthesis from [14C]tyrosine (but not from [14C]DOPA). Apamin (10(-6) M) enhanced the histamine-stimulated catecholamine biosynthesis, which was abolished by omission of extracellular Ca2+. Histamine increased the intracellular free Ca2+ concentration ([Ca2+]i), and this increased [Ca2+]i was potentiated by the presence of apamin. The increase in histamine-stimulated catecholamine biosynthesis with apamin was sensitive to the inhibitors of protein kinase C and Ca2+/calmodulin dependent protein kinase. Apamin increased the histamine-induced phosphorylation of tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis. These results suggest that in cultured bovine adrenal chromaffin cells the inhibition of SK channel results in potentiation of catecholamine biosynthesis and tyrosine hydroxylase phosphorylation induced by histamine and that these stimulatory effects may result from the activation of protein kinase C and Ca2+/calmodulin-dependent protein kinase through an increase in [Ca2+]i.

Animals↗
PubMed1996

[Clinical study on a concomitant therapy with fluconazole and human recombinant granulocyte colony stimulating factor in the treatment of systemic fungal infections with hematological disorders].

The clinical efficacy and the safety of concomitant therapy with fluconazole and recombinant human granulocyte colony stimulating factor (rhG-CSF) was compared with fluconazole monotherapy in neutropenic patients with hematological disorders. The clinical efficacy rate was 73.5% (25/34) in the combination therapy and 48.1% (37/77) in monotherapy. The difference between the two is statistically significant. Side effects were not observed in the combination group, but laboratory abnormalities were found in 6 patients with an incident rate of 11%. The combination therapy with fluconazole and rhG-CSF may be selected as empiric therapy for systemic fungal infection associated with hematological disorders, since this combination therapy showed high efficacy and low incident of side effects. Some patients, however, did not show increased neutrophil counts in spite of rhG-CSF administration.

Adolescent↗
PubMed1996

Antibody production to heat shock proteins with Mr 65 kD (HSP65) in cutaneous inflammation: a possible relation to focal infection.

In order to correlate the immunomodulatory roles of homologous heat shock proteins with Mr 65 kD (HSP65) to skin diseases, antibody level to recombinant-HSP65 of Mycobacterium leprae was quantified with enzyme-linked immunosorbent assay (ELISA) in the sera of patients. In psoriasis, an insignificant increase was observed in anti-HSP65 IgG (0.111 +/- 0.053, mean +/- SD in 0D492 nm, n = 22), compared with a normal group (0.080 +/- 0.032, n = 9). However, psoriasis of acute guttate-type (PGA), which is often induced after tonsillar infection, showed a significant increase (0.178 +/- 0.032 n = 4, p <0.001), but psoriasis vulgaris did not (PV) (0.101 +/- 0.053, n = 12), nor generalized psoriasis pustulosa (PP) (0.087 +/- 0.025, n = 6). Similarly, patients with palmoplantar pustulosis (PPP) with tonsillar or periodontal infection showed significantly high anti-H5P65 IgG (0.230 +/- 0.065, n = 7, p <0.0001), compared with only a mild increase in PPP without suspected infectious foci (0.139 +/- 0.066, n = 13, p <0.05). Possible staphylococcal infection in the oral cavity was suggested by an additional ELISA assay to staphylococcal antigen: anti-staphylokinase IgG showed a significant increase in PPP with infectious foci (0.110 +/- 0.028 n = 3, p <0.01) compared with the normal group (0.039 +/- 0.014), while PPP without them showed only a mild change (0.060 +/- 0.017, n = 6, p <0.05). We assume that immunoreaction to H5P65 may be involved in psoriatic skin inflammation associated with focal infection.

Antibody Formation↗
PubMed1996

Adrenomedullin: a new hypotensive peptide.

PROPERTIES OF ADRENOMEDULLIN: We have identified a novel hypotensive peptide, adrenomedullin, in human pheochromocytoma extract. It has potent and long-lasting vasodilatory effects in several vascular systems. In addition to adrenomedullin, another hypotensive peptide, proadrenomedullin-derived peptide (PAMP), was also found to be processed from the adrenomedullin precursor. PAMP inhibits neural transmission at peripheral sympathetic nerve endings, although adrenomedullin directly dilates vascular smooth muscle. POSSIBLE INVOLVEMENT IN PATHOGENESIS: Although initially isolated from human pheochromocytoma tissue, adrenomedullin messenger RNA is highly expressed in several peripheral organs, including cardiovascular tissues. Adrenomedullin and PAMP are both synthesized and secreted from vascular smooth muscle and endothelial cells, and they participate in circulation control through different mechanisms. Taken together with the presence of adrenomedullin-specific receptors on vascular smooth muscle cells and the significant increase in plasma immunoreactive adrenomedullin levels in patients with hypertension, renal failure and congestive heart failure, adrenomedullin may be involved in the pathogenesis of these diseases.

Adrenomedullin↗
PubMed1995

Adrenomedullin-immunoreactive neurons in the paraventricular and supraoptic nuclei of the rat.

The existence of adrenomedullin (AM) in the rat hypothalamus was examined by immunohistochemistry. AM-immunoreactive neurons were found in the supraoptic nucleus (SON) and in the magnocellular parts of the paraventricular nucleus (PVN). The co-existence of AM-, oxytocin- and/or vasopressin-immunoreactivity was identified in the same neurons in the hypothalamus. The results suggest that the AM may play a role in neurotransmission or in cardiovascular control with neurohypophyseal hormones.

Adrenomedullin↗
PubMed1995

Differential regulation of Ca2+ release-activated Ca2+ influx by heterotrimeric G proteins.

The least understood aspect of the agonist-induced Ca2+ signal is the activation and regulation of the Ca2+ release-activated Ca2+ influx (CRAC) across the plasma membrane. To explore the possible role of heterotrimeric G proteins in the various regulatory mechanisms of CRAC, continuous renal epithelial cell lines stably expressing alpha 13 and the constitutively active alpha qQ209L were isolated and used to measure CRAC activity by the Mn2+ quench technique. Release of intracellular Ca2+ by agonist stimulation or thapsigargin was required for activation of CRAC in all cells. Although the size of the internal stores was similar in all cells, CRAC was 2-3-fold higher in alpha 13- and alpha qQ209L-expressing cells. However, the channel was differentially regulated in the two cell types. Incubation at low [Ca2+]i, inhibition of the NOS pathway, or inhibition of tyrosine kinase inhibited CRAC activity in alpha 13 but not alpha qQ209L cells. Treatment with okadaic acid prevented inhibition of the channel by low [Ca2+]i and the protein kinase inhibitors in alpha 13 cells. These results suggest that expression of alpha qQ209L dominantly activates CRAC by stabilizing a phosphorylated state, whereas expression of alpha 13 makes CRAC activation completely dependent on phosphorylation by several kinases. G proteins may also modulate CRAC activity independently of the phosphorylation/dephosphorylation state of the pathway to increase maximal CRAC activity. Furthermore, our results suggest a general mechanism for regulation of CRAC that depends on coupling of receptors to specific G proteins.

Animals↗
PubMed1995

Increased plasma levels of adrenomedullin in patients with heart failure.

OBJECTIVES: To investigate the role of adrenomedullin in the pathophysiology of heart failure, we measured plasma levels of adrenomedullin in patients with heart failure. BACKGROUND: Adrenomedullin is a potent hypotensive peptide newly discovered in pheochromocytoma tissue by monitoring its elevating activity on platelet adenosine 3',5'-cyclic monophosphate (cAMP). A significant level of adrenomedullin has been identified in human plasma. These findings suggest the possibility of adrenomedullin as a new circulating hormone that participates in the regulation of the cardiovascular system. METHODS: Venous blood samples at rest were obtained from patients with heart failure in New York Heart Association functional classes I (n = 15), II (n = 25), III (n = 16) and i.v. (n = 10) and from normal subjects (n = 27). Plasma adrenomedullin levels were determined by our newly developed radioimmunoassay. Other humoral factor levels measured simultaneously included norepinephrine, atrial natriuretic peptide, brain natriuretic peptide, plasma renin activity, aldosterone and cAMP. Left ventricular ejection fraction was measured by echocardiography. In eight patients with severe heart failure, plasma adrenomedullin levels were measured before and after treatment. RESULTS: The mean (+/- SD) plasma level of adrenomedullin in control subjects was 2.52 +/- 0.75 pmol/liter. Plasma levels of adrenomedullin in patients with heart failure were unaffected in those in functional class I (2.85 +/- 0.62 pmol/liter) but tended to be increased in those in class II (3.54 +/- 0.82 pmol/liter) and were significantly increased in those in classes III and i.v. (4.78 +/- 1.218 and 8.74 +/- 3.43 pmol/liter, respectively). There was a significant correlation between plasma levels of adrenomedullin and norepinephrine (r = 0.618, p < 0.001), atrial natriuretic peptide (r = 0.696, p < 0.001) and brain natriuretic peptide (r = 0.692, p < 0.001). Left ventricular ejection fraction inversely correlated with plasma adrenomedullin levels (r = 0.485, p < 0.001). Plasma adrenomedullin levels significantly decreased after treatment (from 7.40 +/- 3.40 to 3.98 +/- 1.00 pmol/liter, p < 0.05). CONCLUSIONS: These results suggest that plasma level of adrenomedullin are elevated in heart failure and that an increased plasma volume and an activated sympathetic nervous system in this condition may be related to its synthesis or secretion. Given that adrenomedullin exerts potent cardiovascular effects, increased adrenomedullin may be involved in the defense mechanism against further peripheral vascular resistance elevation in heart failure.

Adrenomedullin↗
PubMed1995

Protective immune responses induced by secretion of a chimeric soluble protein from a recombinant Mycobacterium bovis bacillus Calmette-Guérin vector candidate vaccine for human immunodeficiency virus type 1 in small animals.

A recombinant Mycobacterium bovis bacillus Calmette-Guérin (BCG) vector-based vaccine that secretes the V3 principal neutralizing epitope of human immunodeficiency virus (HIV) could induce immune response to the epitope and prevent the viral infection. By using the Japanese consensus sequence of HIV-1, we successfully constructed chimeric protein secretion vectors by selecting an appropriate insertion site of a carrier protein and established the principal neutralizing determinant (PND)-peptide secretion system in BCG. The recombinant BCG (rBCG)-inoculated guinea pigs were initially screened by delayed-type hypersensitivity (DTH) skin reactions to the PND peptide, followed by passive transfer of the DTH by the systemic route. Further, immunization of mice with the rBCG resulted in induction of cytotoxic T lymphocytes. The guinea pig immune antisera showed elevated titers to the PND peptide and neutralized HIVMN, and administration of serum IgG from the vaccinated guinea pigs was effective in completely blocking the HIV infection in thymus/liver transplanted severe combined immunodeficiency (SCID)/hu or SCID/PBL mice. In addition, the immune serum IgG was shown to neutralize primary field isolates of HIV that match the neutralizing sequence motif by a peripheral blood mononuclear cell-based virus neutralization assay. The data support the idea that the antigen-secreting rBCG system can be used as a tool for development of HIV vaccines.

AIDS Vaccines↗
PubMed1995

Inhibition of catecholamine synthesis by proadrenomedullin N-terminal 20 peptide in cultured bovine adrenal medullary cells.

In cultured bovine adrenal medullary cells, proadrenomedullin N-terminal 20 peptide (PAMP), at concentrations > or = 3 microM, inhibited carbachol-induced [14C]catecholamine synthesis from [14C]tyrosine. Carbachol-induced activation of tyrosine hydroxylase was also attenuated by PAMP. These results suggest that PAMP is a novel endogenous peptide that regulates catecholamine synthesis via the suppression of its rate-limiting enzyme in adrenal medullary cells.

Adrenal Medulla↗
PubMed1995

Structural study of the glycosylated and unglycosylated forms of a genetic variant of human serum albumin (63 Asp-->Asn).

A genetic variant of human serum albumin (alloalbumin) exhibited atypical electrophoretic mobility and chromatographic behavior apparently because of the effect of a point substitution on the molecular conformation. Three forms of albumin were isolated by DEAE HPLC chromatography: normal albumin, and two variant forms V1 and V2. The point substitution (Asp-63-->Asn) generated a canonical tripeptide acceptor sequence for glycosylation with an N-linked oligosaccharide (Asn-Lys-Ser). Neuraminidase digestion followed by electrophoresis showed that the V2 variant form was glycosylated and the V1 form was not. Time-of-flight mass spectrometry yielded a molecular weight of about 2000 for the carbohydrate. Structural analysis of the carbohydrate was done by chromatographic comparison of the pyridylaminated derivatives with standards and was confirmed by proton NMR of the three pronase glycopeptides and of the pyridylaminated oligosaccharide. The oligosaccharide had a complex biantennary structure with two sialic acid residues. In normal albumin Asp-63 is exposed and is adjacent to the first disulfide bond, Cys-62-->Cys-53. The apparent effect on molecular conformation resulting in incomplete glycosylation and atypical electrophoretic mobility suggests that glycosylation may interfere with disulfide bond formation at this site.

Amino Acid Sequence↗
PubMed1995

Characterization of the interaction between CD45 and CD45-AP.

CD45, a leukocyte-specific transmembrane protein tyrosine phosphatase, is required for critical signal transduction pathways in immune responses. To elucidate the molecular interactions of CD45 with other proteins involved in CD45-mediated signal transduction pathways, we have recently cloned a 30-kDa phosphorylated protein, CD45-AP, which specifically associates with CD45. Binding analysis employing several deleted or chimeric forms of CD45-AP and CD45 demonstrated that the potential transmembrane segment of CD45-AP bound to the transmembrane portion of CD45. CD45-AP was found in particulate fractions of lymphocytes along with CD45, indicating that it is likely to be a transmembrane protein. In addition, CD45-AP was resistant to proteolysis by tosylphenylalanyl chloromethyl ketone-treated trypsin applied to intact cells. This is consistent with the most likely membrane orientation of CD45-AP predicted from the amino acid sequence, that is, only a short amino-terminal segment of CD45-AP is extracellular. We propose that CD45-AP interacts with CD45 at the plasma membrane and that the bulk of CD45-AP located in the cytoplasm act as an adapter which directs the interaction between CD45 and other molecules involved in CD45-mediated signal transduction pathways.

Animals↗
PubMed1995

Human proadrenomedullin N-terminal 20 peptide in pheochromocytoma and normal adrenal medulla.

Proadrenomedullin N-terminal 20 peptide (PAMP) is a novel hypotensive peptide found in adrenomedullin precursor. Using a radioimmunoassay for human PAMP, we purified immunoreactive PAMP (ir-PAMP) from human pheochromocytoma and determined its complete amino acid sequence. The major component of PAMP-like immunoreactivity was found to be PAMP [1-20] NH2 with an amino acid sequence identical to that of the deduced amino acid sequence by cDNA analysis. Both ir-PAMP and ir-adrenomedullin were found to be abundant in normal adrenal medulla as well as pheochromocytoma tissue arising from adrenal medulla, and there was a significantly (p < 0.05) positive correlation between ir-adrenomedullin and ir-PAMP concentrations in these tissues. However, the PAMP/adrenomedullin ratio in pheochromocytoma tissues (0.197 +/- 0.013) was significantly (p < 0.005) lower than that in adrenal medullae (0.384 +/- 0.041). The present data indicate that PAMP is biosynthesized from adrenomedullin precursor, but the biosynthesis or metabolism of PAMP in pheochromocytoma may be different from that of normal adrenal medulla.

Adrenal Gland Neoplasms↗
PubMed1995

Receptors for adrenomedullin in human vascular endothelial cells.

Accumulation of the intracellular cyclic AMP (cAMP) was measured in cultured endothelial cells of the human umbilical vein following the incubation with adrenomedullin, a newly discovered hypotensive peptide, to determine the presence of specific receptors for adrenomedullin. Adrenomedullin increased the intracellular cAMP in a dose-dependent fashion in the endothelial cells, and the EC50 value was as low as 10(-9) M. Calcitonin gene-related peptide (CGRP) that has a homology to adrenomedullin in its amino-acid sequence also increased the intracellular cAMP with an EC50 value greater than 10(-7) M. The effect of CGRP was attenuated in the presence of CGRP-(8-37), a CGRP receptor antagonist. However, CGRP-(8-37) had no effect on the cAMP accumulation by adrenomedullin. These findings indicate that the cultured endothelial cells of human umbilical vein possess specific adrenomedullin receptors coupled with the adenylate cyclase activity that may have little affinity with CGRP.

Adrenomedullin↗