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Biomedical subjects

K Kondo

Publications and source records attributed to K Kondo.

At least 577 records · Page 32Linked to original sources
PubMed1991

Structure/activity relationship of eel calcitonin. A study using a newly devised method for designing analogs.

A series of analogs of eel calcitonin (eCT) was synthesized according to a newly devised scheme, 'the insertion-inactivation method', to clarify the structure/activity relationship of a given peptide. This method consists of two steps: the deletion of a residue of the peptide is first chosen and then a series of analogs with the residue reinserted into serial positions is synthesized and biological activities are assessed in each step. An analog lacking Lys18 (dK), selected as a deleted analog for the first step, showed marked loss of activities determined by inhibition of 125I-eCT binding, growth inhibition, and cAMP production in a porcine kidney cell line LLC-PK1. Activities of a set of 20 analogs with the reinserted lysine residue at serial positions from 12 to 32 (K12-K32) were then evaluated. The results showed the following three patterns of the expression of activities according to the position of the reinsertion: (a) analogs K12-K16 (positions 12-16) and K25 (position 25) showed lower activities than eCT in all assays; (b) K17-K24 (positions 17-24) showed slightly lower activities than eCT in the receptor binding and the growth inhibition and similar level in cAMP production; (c) K26-K32 (positions 26-32) showed considerably lower activities in the former two assays and slightly lower activity in cAMP production. Further, analogs considerably less active than eCT showed unchanged alpha-helix contents and destroyed amphiphilicity by the insertion of a lysine residue, indicating that amphiphilicity is one of important factors for expressing the activity. The results obtained here lead to a conclusion on the significance of each region of eCT molecule as follows: (a) the presence of Lys18 is necessary for the complete expression of biological activity; (b) the length of amphiphilic alpha-helix to be required for the activity is at most 10 residues ranging from position 8 to position 17; (c) the receptor binding region is located within 9 residues ranging from position 24 to position 32.

Amino Acid Sequence↗
PubMed1991

Gastrin releasing peptide-like immunoreactive substance in rat mammary glands during pregnancy.

The concentration of gastrin releasing peptide-like immunoreactive substance (GRP-IS) was measured by enzyme immunoassay (EIA) in rat mammary glands during pregnancy and after delivery. The GRP-IS concentration was high in the middle stage of pregnancy (10-14 days of gestation) and decreased in late pregnancy to reach a plateau range. By using HPLC, it was shown that GRP(20-29) and GRP(16-29) were mainly present in rat mammary glands. Immunohistochemical study revealed that epithelial cells of rat mammary glands were stained intensely with antiserum GP-6201. These results suggest that GRP-IS is produced and secreted in epithelial cells of mammary glands and takes part in the proliferation, differentiation and hypertrophy of mammary glands.

Animals↗
PubMed1991

Anemia and mast cell depletion in mutant rats that are homozygous at "white spotting (Ws)" locus.

Mice possessing two mutant alleles at the W or Sl locus are anemic and deficient in mast cells. These mouse mutants have black eyes and white hair. Because homozygous mutant rats at the newly found white spotting (Ws) locus were also black-eyed whites, the numbers of erythrocytes and mast cells were examined. Suckling Ws/Ws rats showed a severe macrocytic anemia and were deficient in mast cells. When bone marrow cells of normal (+/+) control or Ws/Ws rats were injected into C3H/He mice that had received cyclophosphamide injection and whole-body irradiation, remarkable erythropoiesis occurred in the spleen of +/+ marrow recipients but not in the spleen of Ws/Ws marrow recipients. When skin pieces of Ws/Ws embryos were grafted under the kidney capsule of nude athymic rats, mast cells did develop in the grafted skin tissues. Therefore, the anemia and mast cell deficiency of Ws/Ws rats were attributed to a defect of precursors of erythrocytes and mast cells. Because the magnitude of the anemia decreased and that of the mast cell deficiency increased in adult Ws/Ws rats, this mutant is potentially useful for investigations about differentiation and function of mast cells.

Anemia↗
PubMed1991

Characterization of Ws mutant allele of rats: a 12-base deletion in tyrosine kinase domain of c-kit gene.

Homozygous mutant rats at the newly found white spotting (Ws) locus were anemic and deficient in mast cells and melanocytes. Because the phenotype of Ws/Ws rats resembled the phenotype of mice possessing a double-gene dose of mutant alleles at the W locus and because the c-kit gene was mapped at the W locus of mice, we characterized the c-kit gene of Ws/Ws rats. The authentic sequence of the rat c-kit cDNA was determined by using a cDNA library prepared from the hippocampus of Sprague-Dawley rats. The c-kit cDNA of Ws/Ws and normal (+/+) control rats was obtained by reverse transcriptase modification of the polymerase chain reaction. When compared with the authentic sequence, a deletion of 12 bases was found in the c-kit cDNA of Ws/Ws rats. This change was shown to be a result of the deletion of the genomic DNA. Four amino acids encoded by the deleted 12 bases (ie, Val-Lys-Gly-Asn) were located at two amino acids downstream from the tyrosine autophosphorylation site in the c-kit kinase and were conserved not only in mouse and human c-kit kinases but also in mouse and human c-fms kinases (ie, receptors of colony-stimulating factor-1). Taken together, the Ws/Ws rat is the first characterized mutant of the c-kit gene in an animal species other than the mouse.

Alleles↗
PubMed1991

Induction of in vitro differentiation of mouse embryonal carcinoma (F9) cells by inhibitors of topoisomerases.

To investigate the possible involvement of topoisomerases in embryonal differentiation, we examined the effect of topoisomerase inhibitors on the in vitro differentiation of mouse embryonal carcinoma F9 cells. We found that camptothecin, teniposide (VM-26), or genistein, specific inhibitors of topoisomerases, induced morphological as well as biochemical changes (production of tissue plasminogen activator, synthesis of laminin, and disappearance of stage-specific embryonic antigen 1) specific to F9 cell differentiation. Since these changes were indistinguishable from those observed in F9 differentiation induced by retinoic acid (plus dibutyryl cyclic AMP), it was suggested that inhibition of cellular topoisomerase activities triggered F9 cell differentiation into parietal endoderm-like cells in the same manner as retinoic acid (plus dibutyryl cyclic AMP). Experiments using differentiation-resistant mutant F9 cell lines, however, indicated that the molecular cascade involved in topoisomerase inhibitor-induced differentiation involves different steps from those functioning in the retinoic acid-induced differentiation cascade.

Animals↗
PubMed1991

Cellular HSP90 (HSP86) mRNA level and in vitro differentiation of mouse embryonal carcinoma (F9) cells.

Treatment of mouse embryonal carcinoma (F9) cells with retinoic acid, an inducer of F9 cell differentiation, greatly increased the level of mRNA specific to one of the heat-shock proteins (HSP86). Experiments including the one employing differentiation-resistant mutant F9 cells suggested that the increase represents early molecular events associated with the embryonal differentiation. The increased HSP86 mRNA declined to the original level during further incubation. The presence of cyclic AMP, which stimulates conversion of the retinoic acid-induced primitive endoderm cells to parietal endoderm cells, prevented the decline. These results suggest that not only the elevation of HSP86 mRNA level represents early molecular events in F9 cell differentiation but also that sustaining the elevated level (by cyclic AMP) is associated with further differentiation of the embryonal cells.

Animals↗
PubMed1991

TIP 1, a cold shock-inducible gene of Saccharomyces cerevisiae.

Using differential hybridization, genes whose expression is induced at low temperatures were identified in yeast Saccharomyces cerevisiae. One of these genes that corresponds to an mRNA that is induced 6-8-fold within 2 h after shifting the culture temperature from 30 to 10 degrees C was further characterized. Surprisingly, its expression was also induced by heat shock, and thus the gene was designated TIP 1 (temperature shock-inducible protein gene). Southern hybridization analysis demonstrated that there are several genes homologous to the TIP 1 gene on the yeast genome. A TIP 1 disruption mutation exerted an observable effect neither on growth nor on viability after being exposed to freezing temperatures. The TIP 1 gene encodes a protein of 210 amino acid residues with a molecular weight of 20,727, containing 20.0% alanine and 23.3% serine. The TIP 1 protein has a typical signal peptide at the amino-terminal end and an extremely hydrophobic sequence at the carboxyl-terminal end. The TIP 1 protein is thus likely to be secreted across the membrane and anchored on the outside surface of the plasma membrane. These results indicate that the TIP 1 protein is a new type of stress inducible protein in yeast.

Amino Acid Sequence↗
PubMed1991

Molecular cloning of a ribonuclease H (RNase HI) gene from an extreme thermophile Thermus thermophilus HB8: a thermostable RNase H can functionally replace the Escherichia coli enzyme in vivo.

A DNA fragment encoding Ribonuclease H (EC 3. 1.26.4) was isolated from an extreme thermophilic bacterium, Thermus thermophilus HB8, by its ability to complement the temperature-sensitive growth of an Escherichia coli rnhA deficient mutant. The primary amino acid sequence showed 56% similarity to that of E. coli RNase HI but little or no homology to E. coli RNase HII. Enzymes derived from thermophilic organisms tend to have fewer cysteines than their bacterial counterparts. However, T. thermophilus RNase H has one more cysteine than its E. coli homologue. Stability of the RNase H in extracts of T. thermophilus to elevated temperatures was the same for the protein expressed in E. coli. T. thermophilus RNase H should, therefore, be a useful tool for editing RNA-DNA hybrid molecules at higher temperatures and may also be stable enough to be used in a cyclical process. It was suggested that regulation of expression of the RNase H may be different from that of E. coli. RNase HI.

Amino Acid Sequence↗
PubMed1991

Centrally administered galanin inhibits osmotically stimulated arginine vasopressin release in conscious rats.

The effect of centrally administered galanin on arginine vasopressin (AVP) release was investigated in conscious rats. Intracerebroventricular injection of porcine galanin suppressed hypertonic saline-induced increase in plasma AVP in a dose-dependent manner (12.5-100 pmol/rat) at 10 min after the injection. Pretreatment with subcutaneous injection of naloxone (1 mg/100 g b.wt.) partially blocked the galanin-induced effect on plasma AVP. These results suggest that central galanin inhibits osmotically stimulated AVP release and endogenous opioids are, at least in part, involved in the mechanism.

Animals↗
PubMed1991

Microparticle generation during in vitro platelet activation by anti-CD9 murine monoclonal antibodies.

We used flow cytometry and two anti-CD9 murine monoclonal antibodies (NNKY1-19, MALL13) to investigate the glycoprotein composition and the potential functions of microparticles (MP) released by platelets exposed to these antibodies in vitro. NNKY1-19 produced aggregation with characteristics similar to those noted in previous reports. The action of MALL13 on platelets in platelet-rich plasma (PRP), however, differs from that of other anti-CD9 antibodies. The normal fluctuation in the MALL13-induced change in optical density disappeared when complement was present. MALL13-induced effect for platelet in PRP was not inhibited by preincubation with monoclonal anti-GPIIb/IIIa antibody, but was inhibited in washed platelets (WP). Furthermore, following MALL13 stimulation in PRP platelets, the amount of buffer LDH markedly increased and electron microscopy findings showed vacuoles appearing inside the platelets. These results suggest that MALL13 has at least two effects on platelets that differ for PRP platelets and WP. The number of MP released was increased by the addition of anti-CD9 antibodies. MP surfaces were found to be rich in CD9 protein. MALL13 stimulation lead to a significant increase in the binding of C1q and C3 to platelets and caused the production of MP to occur more rapidly than it did the exposure of fibrinogen binding sites in the presence of complement. The analysis of the relationship of MP to anti-CD9 monoclonal antibody may be useful in the investigation of the relationship between platelet function and coagulation regulation.

Antibodies, Monoclonal↗
PubMed1991

Characterizations of the human parainfluenza type 2 virus gene encoding the L protein and the intergenic sequences.

We cloned and determined the nucleotide sequences of cDNAs against genomic RNA encoding the L protein of human parainfluenza type 2 virus (PIV-2). The L gene is 6904 nucleotides long including the intergenic region at the HN-L junction and putative negative strand leader RNA, almost all of which is complementary to the positive strand leader RNA of PIV-2. The deduced L protein contains 2262 amino acids with a calculated molecular weight of 256,366. The L protein of PIV-2 shows 39.9, 28.9, 27.8 and 28.3% homologies with Newcastle disease virus (NDV), Sendai virus (SV), parainfluenza type 3 virus (PIV-3) and measles virus (MV), respectively. Although sequence data on other components of transcriptive complex, NP and P, suggested a closer relationship between PIV-2 and MV, as concerns the L protein, MV is closely related to another group as SV and PIV-3. From analysis of the alignment of the five l proteins, six blocks composed of conserved amino acids were found in the L proteins. The L protein of PIV-2 was detected in purified virions and virus-infected cells using antiserum directed against an oligopeptide corresponding to the amino terminal region. Primer extension analyses showed that the intergenic regions at the NP-P, P-M, M-F, F-HN and HN-L junctions are 4, 45, 28, 8 and 42 nucleotides long, respectively, indicating that the intergenic regions exhibit no conservation of length and sequence. Furthermore, the starting and ending sequences of paramyxoviruses were summarized.

Amino Acid Sequence↗
PubMed1991

High concentration of a gastrin releasing peptide-like immunoreactive substance in pregnant human milk.

The level of a gastrin releasing peptide-like immunoreactive substance (GRP-IS) in human milk and plasma during late pregnancy and after delivery was measured. GRP-IS in milk increased during late pregnancy (1.3 nM at 39 weeks) and decreased after delivery (100 pM). GRP-IS in plasma during late pregnancy and after delivery was much lower (below 2 pM). By using HPLC and gel-filtration chromatography, two peaks of GRP-IS were purified. The one was coeluted with GRP (18-27) and the other was a prohormone. The GRP-IS in milk during pregnancy was mostly composed of proGRP. These results suggest that GRP may be produced and secreted in mammary glands.

Breast↗
PubMed1991

OPC-21268, an orally effective, nonpeptide vasopressin V1 receptor antagonist.

An orally effective, nonpeptide, vasopressin V1 receptor antagonist, OPC-21268, has been identified. This compound selectively antagonized binding to the V1 subtype of the vasopressin receptor in a competitive manner. In vivo, the compound acted as a specific antagonist of arginine vasopressin (AVP)-induced vasoconstriction. After oral administration in conscious rats, the compound also antagonized pressor responses to AVP. OPC-21268 can be used to study the physiological role of AVP and may be therapeutically useful in the treatment of hypertension and congestive heart failure.

Administration, Oral↗
PubMed1991

A sensitive enzyme immunoassay for human basic fibroblast growth factor.

A sensitive sandwich enzyme immunoassay for human basic fibroblast growth factor (HbFGF) was developed employing three monoclonal antibodies (MAb3H3, MAb98 and MAb52). The Fab' fragment of MAb3H3 which inhibits HbFGF biological activity was conjugated to horseradish peroxidase. A mixture of MAb52 and MAb98 was used in the solid phase. Neither human acidic fibroblast growth factor, hst-1/KS3 product nor acid denatured HbFGF was cross-reactive in this assay system. The detection limit of this assay system was 1 pg/well. Using this assay, some tumor cell lines were revealed to produce a higher level of bFGF than a normal one. Serum samples from normal volunteers were also assayed, and immuno-reactive HbFGF could be detected in 16 out of 57 samples at range 30 approximately 206 pg/ml.

Antibodies, Monoclonal↗
PubMed1991

Establishment of monoclonal antibodies against human acidic fibroblast growth factor.

Four kinds of hybridomas secreting monoclonal antibodies (MAbs) against human acidic fibroblast growth factor (haFGF) were established using recombinant haFGF as an immunogen. The recognition sites of four MAbs designated AF1-52, 81, 114 and 1C10 for the haFGF molecule were examined by binding studies with synthetic polypeptides and with amino-terminal truncated forms of haFGF. These experiments suggested that AF1-52, 114, and 1C10 MAbs recognize epitopes within the 1-5, 44-132 and 6-43 amino acid sequences, respectively. However, the epitope recognized by the AF1-81 MAb could not be determined. The sandwich EIA method constructed with these MAbs was sensitive to 1.5 pg/well of haFGF and had no cross-reactivity with human basic FGF, bovine aFGF or the hst-1 gene product.

Animals↗
PubMed1991

Aggravation of subclinical diabetes insipidus during pregnancy.

BACKGROUND: Transient polyuria and polydipsia during pregnancy are rare, and their cause is not entirely clear. Possible explanations include the exacerbation of preexisting abnormalities in the secretion or action of vasopressin and abnormally large increases in plasma vasopressinase activity. METHODS: We studied two women in whom overt polyuria and polydipsia developed during the third trimester of pregnancy and disappeared after delivery. The secretion and action of vasopressin were studied both when the women had polyuria and polydipsia and later, when their water intake and urine volume were normal. RESULTS: One patient had partial nephrogenic diabetes insipidus. She had little increase in urine osmolality in response to water deprivation, hypertonic-saline infusion, and vasopressin injection and no response to desmopressin acetate (1-deamino-8-D-arginine vasopressin) during the immediate postpartum period. Her basal and stimulated plasma vasopressin concentrations were high (16.5 to 203.4 pmol per liter) before and during hypertonic-saline infusion 30 months post partum. The other patient had partial neurogenic diabetes insipidus. She had subnormal basal plasma vasopressin concentrations, a subnormal increase in the plasma vasopressin level and a subnormal decrease in urine flow in response to the administration of vasopressin, and a normal response to desmopressin. After pregnancy, when her urine volume was normal, she had no increase in plasma vasopressin in response to hypertonic-saline infusion, but she had a normal rise in the plasma vasopressin level and a normal renal response to vasopressin administration. CONCLUSIONS: Pregnancy may unmask subclinical forms of both nephrogenic and neurogenic diabetes insipidus. This exacerbation may result from both increased vasopressinase activity and diminished renal responsiveness to vasopressin.

Adult↗
PubMed1991

Induction of in vitro differentiation of mouse erythroleukemia cells by genistein, an inhibitor of tyrosine protein kinases.

We have found that genistein, a specific inhibitor of tyrosine protein kinases, induces in vitro erythroid differentiation of mouse erythroleukemia cells. Characterization of the induction process indicated that the genistein-induced differentiation is different from that induced by conventional inducing agents such as dimethyl sulfoxide or hexamethylene-bisacetamide. This conclusion was based upon the earlier appearance of differentiated cells, insensitivity to a specific inhibitor (dexamethasone), and responsiveness of some of the differentiation-resistant cells to genistein in the genistein-induced erythroid differentiation. Possible biological significance of this finding is discussed with respect to the involvement of protein phosphorylation (or dephosphorylation) in mouse erythroleukemia cell differentiation.

Acetamides↗