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Biomedical subjects

Y Kitajima

Publications and source records attributed to Y Kitajima.

At least 163 records · Page 9Linked to original sources
PubMed1990

Partial amino acid sequence of an amyloid fibril protein from nodular primary cutaneous amyloidosis showing homology to lambda immunoglobulin light chain of variable subgroup III (a lambda III).

An amyloid fibril protein (MA) was purified as a 17,000-dalton protein from a case of nodular primary cutaneous amyloidosis, and its partial amino acid sequence (22 residues from N-terminal) was determined. A sequence closely homologous to that of the lambda III subgroup of the immunoglobulin light chain was detected. This is the third case of nodular primary cutaneous amyloidosis which has been studied at the level of sequence analysis of purified amyloid fibril proteins, and the first case of nodular primary cutaneous amyloidosis in which a lambda III amyloid protein has been shown to be present by sequence analysis.

Amino Acid Sequence↗
PubMed1990

Synthesis and biological property of alpha-human atrial natriuretic peptide analogs with a constrained or stereochemically modified cyclic moiety.

Conformationally restricted analogs of alpha-human atrial natriuretic peptide (alpha-hANP) containing L- or D-penicillamine, or D-cysteine in place of cysteine residues at positions 7 and 23 were synthesized by the liquid phase procedure. Their biological properties in the assays of receptor binding and cyclic guanosine monophosphate (cGMP) accumulation employing rat vascular smooth muscle cells (VSMC), vasorelaxant activity using rat isolated aorta were evaluated. We found that the constrained and/or stereochemically altered ring moiety generally did not influence the receptor binding activity, however, cGMP accumulation and vasorelaxant activities were quite sensitive to conformational perturbation. Furthermore, a lack of correlation between cGMP accumulation activity and vasorelaxant activity was observed. Dissociation between these activities was typical in the case of [DPen7,23]-alpha-hANP(7-28), which showed quite weak vasorelaxant activity in spite of its full cGMP accumulation and receptor binding potencies. This result suggests that cGMP accumulation alone is not sufficient to promote ANP-induced vasorelaxation, and that the other second messenger(s) may mediate this activity.

Amino Acid Sequence↗
PubMed1990

Pressor effect of NG-monomethyl-L-arginine in SHRSP.

Pressor effects of NG-monomethyl-L-arginine (L-NMMA), a selective inhibitor of nitric oxide production from L-arginine, on mean blood pressure (MBP) were investigated in conscious Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP). L-NMMA (0.1-10 mg/kg, i.v.) elicited a dose-dependent increase in the MBP of WKY and SHRSP. The pressor response to L-NMMA was more marked in SHRSP than in WKY. These results suggest that nitric oxide may play an important role in the blood pressure regulation in the conscious SHRSP.

Animals↗
PubMed1990

Structural studies on aldolase isozymes through protein engineering.

Enzymatic studies on aldolase isozymes have been carried out by techniques of protein engineering. Site-directed mutagenesis helps us to verify the roles of amino acid residues in catalytic reactions. Chimeric fusion proteins give us information about the regions which specify the characteristics of the isozymes. The results are: (1) In aldolase A, COOH terminal Tyr and Lys-107 residues play important roles in catalysis, especially in binding of FDP. (2) Aspartic acid at the 128th residue in aldolase A is essential to thermostability; no other residue such as glutamic acid can substitute for it. (3) Studies on chimeric fusion proteins indicate that the C-terminal region (including C-terminus Tyr) or aldolase A is responsible for its substrate specificity, which is not seen in aldolase B. (4) A region near NH2 terminus in aldolase B determines its specific structure. (5) The region including His-107, Asp-128, and Tyr-137 (B-A junction of BA137) is located in a turn which is exposed outward (a model architecture by Sygusch et al [1987]). In BA137, this region would be constrained, and play a significant role in catalysis, thermostability, etc. (6) Tertiary structure of aldolase B seems to be dissimilar to that of aldolase A.

Amino Acid Sequence↗
PubMed1990

[Immunohistological localization of human aldolase A in human neoplastic and non-neoplastic tissues].

The expression of human aldolase A in tissues of cancer patients was examined immunohistologically using 4 monoclonal antibodies (1A2, 3C5, 1D1 and 4C2) to human aldolase A. In frozen sections, but not in paraffin sections, tumor cells of 22 out of 30 patients and non-neoplastic cells of 11 out of 21 patients examined reacted with 1A2 irrespective of cancer types. Positive reactions were seen mostly in the nucleus and some in the cytoplasm. Only tumor cells in a few neoplastic tissues gave positive cytoplasmic reactions with 1D1 or 4C2. No positive reaction was observed with 3C5. Antigens cross-reactive with aldolase A may be expressed more frequently in tumor cells than in non-neoplastic cells of cancer patients.

Antibodies, Monoclonal↗
PubMed1989

Linear alpha-human atrial natriuretic peptide analogs display receptor binding activity and inhibit alpha-hANP-induced cGMP accumulation.

We have synthesized a series of [Cys(R)7,23]alpha-hANP analogs, in which the two Cys residues were modified with various alkyl groups(R); i.e., R=Acm, Pe, Qe, Cam, Me, Ae, Bzl, Cm, Ocam and sulfo. The Acm-, Cam-, and Me-analogs exhibited binding activity as potent as alpha-hANP in rat vascular smooth muscle cells (VSMC). Binding activity of the analogs decreased progressively as the bulkiness of the R group increased. None of the analogs caused accumulation of cGMP in VSMC and vasorelaxant activity in rat aorta. Acm-, Cam- and Me-analogs substantially antagonized alpha-hANP-induced cGMP accumulation, but did not antagonize vasorelaxation induced by alpha-hANP in vitro.

Animals↗
PubMed1989

Enhanced biological activity of dimeric gonadotropin releasing hormone.

The biological activities of a series of dimeric analogs of des-Gly10-[D-Lys6]GnRH-NHEt cross-linked at Lys6 by malonic acid and elongated by Gly, i.e., HO-Glyn-CO-CH2-CO-Glyn-OH (n = 0, 1, 2), were analyzed in vitro and in vivo. All three dimeric analogs displayed increased activity in receptor binding and in LH release assays than the original monomer, and dimer Ib (n = 1) showed the highest potency in vitro. This compound also showed the highest activity in the in vivo postcoital assay, in which GnRH agonist potency is measured by inhibition of pregnancy. These results indicate that GnRH receptor activation is substantially enhanced by dimerization of the agonist ligand.

Animals↗
PubMed1989

Abnormal organization of keratin intermediate filaments in cultured keratinocytes of epidermolysis bullosa simplex.

Distinctive abnormality in the organization of keratin intermediate filaments (KIFs) was found for the first time in cultured epidermal keratinocytes from two patients with hereditary epidermolysis bullosa simplex (EBS), which showed cleavages above the basement membrane zone due to the fragility of basal cells. KIFs in EBS keratinocytes revealed an irregular radial arrangement composed of sparse but thick KIF bundles. Furthermore, these KIF bundles in many cells changed into numerous ball-like keratin aggregates and disappeared beyond these keratin aggregates in the peripheral cytoplasm. Electron microscopy of cultured EBS keratinocytes showed that many ball-like structures consisting of fine filaments or granules or homogeneous substances were scattered in the peripheral regions of the cell attaching to the dish, and intermediate filaments appeared to be emanating from or surrounding the structures. These ball-like keratin aggregates have never been observed in normal human keratinocytes.

Adult↗
PubMed1989

Involvement of protein kinase C in translocation of desmoplakins from cytosol to plasma membrane during desmosome formation in human squamous cell carcinoma cells grown in low to normal calcium concentration.

The intracellular signal transduction mechanism leading to desmosome formation in low-calcium-grown keratinocytes after addition of calcium to the medium was studied by immunofluorescence using antibodies to desmoplakins I and II (cytoplasmic desmosomal proteins) and by electron microscopy before and after addition of calcium; protein kinase C (PKC) activators 12-O-tetradecanoylphorbol-13-acetate (TPA), phorbol-12,13-dibutyrate (PDBu), and 1,2-dioctanoylglycerol (DOG); calcium ionophore A23187; selective PKC inhibitors 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7) and staurosporine; and a Ca2+/calmodulin-dependent kinase inhibitor, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7). In previous studies using a low-calcium-grown human epidermal squamous cell carcinoma, we have shown that an increase in extracellular Ca2+ caused a four-fold increase in PKC activity and addition of TPA (10 ng/ml) induced a transient increase in membrane-bound PKC activity in association with cell-cell contact formation. The present study showed that TPA (10 ng/ml). PDBu (10 ng/ml), and DOG (1 mg/ml) induced a rapid cell-cell contact and redistribution of desmoplakins from cytoplasm to the plasma membrane with desmosome formation within 60-120 min, which was similar, although less marked, to the effect of increased Ca2+. The TPA-induced desmosome formation was inhibited by selective PKC inhibitors, H-7 (20 microM) or staurosporine (100 nM). On the other hand, calcium ionophore A23187 induced only a temporary increase in the number of desmoplakin-containing fluorescent spots in the cytoplasm and a temporary cell-cell attachment without desmosome formation. The calcium-induced desmosome formation was partially inhibited by 20-100 microM H-7 or 100 nM staurosporine; however, it was not inhibited by W-7 at a concentration of 25 microM, at which this agent selectively inhibits calmodulin-dependent protein kinase. These results suggest that PKC activation plays an important role in desmoplakin translocation from the cytoplasm to the plasma membrane as one of the processes of calcium-induced desmosome formation.

Calcimycin↗
PubMed1989

Correlation between cell-cell contact formation and activation of protein kinase C in a human squamous cell carcinoma cell line.

Formation of desmosomal cell-cell contact associated with reorganization of keratin intermediate filaments (KIFs) was observed when cultured cells of a cell line of human skin squamous cell carcinoma were transferred from low (0.07 mM) calcium to high (1.87 mM) calcium medium. At low calcium, cells were dispersed without desmosomal cell-cell contact and the KIFs were mostly concentrated around the nucleus. After 15 min of the transfer, cells contacted each other and formed small colonies and the KIFs initiated to show a radial arrangement. In addition to the cell-cell contact formation and rearrangement of KIFs, the transfer induced fourfold increase of particulate-associated protein kinase C (C-kinase) activity. When 12-O-tetradecanoyl phorbol-13-acetate (PMA), which specifically activates C-kinase, was added to the cells grown at low calcium medium, cell-cell contact formation and radial arrangement of KIF bundles almost identical to those induced by the transfer to high calcium medium were observed. These data suggest a correlation between an increase in C-kinase activity and formation of cell-cell contacts associated with rearrangements of KIFs.

Calcium↗
PubMed1989

An elevated level of autoantibodies against 48- to 50-kd keratins in the serum of patients with psoriasis.

Studies on the anti-keratin intermediate filament autoantibodies (anti-KIF-Abs) in sera from psoriasis (Pso) patients were performed by immunoblotting and enzyme-linked immunosorbent assay (ELISA). According to their reactivities against keratin subunits (50, 56.5, 58, and 63-68 kd), sera were divided into four groups. However, no significant differences in these reactive patterns were found between healthy volunteers and Pso patients. In the second experiment, anti-KIF-Abs in sera from Pso patients, pustulosis palmaris et plantaris (PPP) patients, atopic dermatitis (AD) patients, systemic lupus erythematosus (SLE) patients, and healthy volunteers were determined by ELISA, using as substrate keratins purified from normal human stratum corneum and 48- and 50-kd keratins purified from psoriatic stratum corneum. The serum titers of anti-KIF-Abs against 48- and 50-kd keratins in Pso patients were significantly higher than those in PPP patients, AD patients, SLE patients, or healthy volunteers. The elevated titers of anti-KIF-Abs against the 48- and 50-kd keratins in sera of Pso patients showed a significant decrease with improvement of psoriatic lesions. The above results suggest that anti-KIF-Abs against 48- and 50-kd keratins in sera of Pso patients have some relevance to the severity of the disease and can be used as a marker for the evaluation of the disease activity of psoriasis.

Autoantibodies↗
PubMed1989

Characterization of bullous pemphigoid antigen synthesized by cultured human squamous cell carcinoma cells.

This report concerns the characterization of bullous pemphigoid antigen (BPA) in cultured cells derived from a human squamous cell carcinoma (SCC cells) as identified by sera of 9 patients with bullous pemphigoid (BP). Immunoglobulin G from 5 of 9 BP sera bound the cell surfaces of SCC cells with a punctate staining pattern by immunofluorescence. The other four BP sera and all 12 controls sera showed no specific staining. To characterize the antigen for pemphigoid antibody, we immunoprecipitated NP-40 extracts of cells labeled with [14C] amino acids using nine BP sera and 12 controls sera. These immunoprecipitates were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and by fluorography. The five BP sera that gave positive immunofluorescence results also precipitated a protein with molecular weight (mol wt) of 110 kD, whereas the other four BP sera negative by immunofluorescence and all 12 controls sera did not precipitate this protein. These results indicate that the sera of patients with BP contain antibodies against the protein with mol wt 110 kD in the SCC cells used in this study. With use of four BP sera, two of which were positive to this mol wt 110 kD BPA and two of which were negative, immunoprecipitation was carried out in Pam cells. One 110 kD-positive serum and two 110 kD-negative sera, precipitated a BPA of mol wt 220 kD from Pam cells labeled with [35S] methionine. These results suggest that BP sera may recognize more than one antigen, in addition to possible BPA heterogeneity in different individuals.

Antigens↗
PubMed1988

Biphasic effects of 12-O-tetradecanoylphorbol-13-acetate on the cell morphology of low calcium-grown human epidermal carcinoma cells: involvement of translocation and down regulation of protein kinase C.

The present study was performed to investigate involvement of protein kinase C in the biphasic effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) on cell morphology in low calcium (0.07 mM)-grown cells of a human epidermal squamous cell carcinoma cell line. The low calcium-grown cells formed no desmosomal cell-cell contact and showed roughly circular arrangements of keratin intermediate filaments around the nucleus. Treatment with 10 ng/ml of TPA induced a rapid formation (within 15 min) of cell-cell contact and reorganization of keratin intermediate filaments from a circular organization to a radial arrangement in these low calcium-grown cells. These structural phenomena were associated with a transient increase in membrane-bound protein kinase C activity. However, the prolonged treatment longer than 24 h led to a prominent decrease in the number of cell-cell contacts, that had been once formed, and caused fibroblastic changes of cell morphology in association with a decrease in the membrane-bound protein kinase C activity. Addition of 20 microM 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride, a potential inhibitor of protein kinase C, to the medium with TPA blocked the formation of cell-cell contact. Addition of 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride alone to normal calcium-grown cell cultures exhibiting cell-cell contact resulted in a decrease in the number of cell-cell contacts and in the fibroblastic morphological changes after 24-h incubation. These results suggest that the effects of TPA are biphasic as follows: the initial stage, inducing cell-cell contact formation associated with the translocation of protein kinase C activity from the cytosol to the membrane; and the late stage, exhibiting a fibroblastic morphological change with a decrease in the number of cell-cell contacts associated with the down regulation of this enzyme activity by TPA.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1988

Speculative cell cycle in yeast-phase growth of Sporothrix schenckii: plasma membrane ultrastructure as revealed by freeze-fracture electron microscopy.

The cell cycle in yeast-phase growth of Sporothrix schenckii was investigated by light microscopy and freeze-fracture electron microscopy after a 3- to 7-day cultivation on brain heart infusion agar medium at 37 degrees C. Mother yeastlike cells were able to bear daughter yeastlike cells. They were also able to produce germ tubes that had the potential to develop into pseudohyphae and hyphae. On the other hand, hyphae or pseudohyphae born from yeastlike cells were able to bear yeastlike cells directly. These results lead us to propose a hypothetical cell cycle for yeast-phase growth involving yeastlike vegetative cells, pseudohyphae, and hyphae.

Cell Cycle↗