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Biomedical subjects

Y Ohba

Publications and source records attributed to Y Ohba.

At least 199 records · Page 11Linked to original sources
PubMed1989

Hb Miyano or alpha 41(C6)Thr----Ser: a new high oxygen affinity alpha chain variant found in an erythremic blood donor.

An abnormal hemoglobin found in an erythremic blood donor was separable only by isoelectrofocusing, where it was located at the cathodic edge of Hb A. Cation exchange high performance liquid chromatography of a tryptic digest from the total alpha chain revealed splitting of the alpha T-6 peak, although our routine procedures failed to uncover the abnormality. This enabled the chemical characterization and quantitation of the abnormal hemoglobin as alpha 41(C6)Thr----Ser comprising about 30% of the total hemoglobin. The purified hemoglobin showed increased oxygen affinity, decreased subunit cooperativity and effect of organic phosphates, and normal Bohr effect.

Amino Acid Sequence↗
PubMed1989

Characterization of beta-thalassemia mutations among the Japanese.

Characterization of beta-thalassemia mutations were attempted for 29 Japanese families clinically diagnosed as having beta-thalassemia. Following the identification of a mutation by cloning and sequencing, all families were screened for this particular mutation, using biotinylated allele-specific oligonucleotide probes. Seven different mutations were detected in 17 families: Six families had the frameshift mutation at codons 41/42, resulting from a 4 nucleotide deletion (TTCTTT----TT); four had the deletion at codons 127/128 (CAGGCT----CCT); and three had the TATA box mutation at nucleotide -31 (A----G). Four additional families had mutations at codon 24 (GGT----GGA), codon 26 (GAG----AAG), IVS-II-654 (C----T) and codon 110 (GTG----CCG), respectively. The newly discovered deletion mutation at codons 127/128, and mutations at nucleotide -31, and at codon 110 are peculiar to Japanese, and have not been found in any other ethnic group. The haplotypes of the beta-globin gene cluster were also determined. Some of the haplotypes and beta-thalassemia mutations are identical to those reported in the Chinese population. However, it is noteworthy that nearly half of the beta-thalassemia mutations were unique to Japanese.

Alleles↗
PubMed1989

Hb Moriguchi or alpha 2 beta 2(97) (FG4)His---Tyr substitution at the alpha 1-beta 2 interface.

An abnormal profile of cation exchange high performance liquid chromatography for the determination of Hb A1c led to the discovery of a new hemoglobin variant with a His----Tyr substitution at position 97(FG4) of the beta chain. The variant comprised about equal proportion to normal Hb A. It showed an increased oxygen affinity, normal n value and slightly reduced alkaline Bohr effect. However, the magnitude of the functional deviation is less than that of other variants with substitutions at the same position, and the heterozygous carrier was not erythremic.

Adult↗
PubMed1989

Determination of ABO blood groups from saliva and saliva stains by an indirect enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies.

The detection of A, B and H blood group substances (ABH-BGS) in saliva and in saliva stains has been investigated quantitatively by an indirect ELISA using a horseradish peroxidase conjugate in combination with the use of monoclonal antibodies. Through this method, the reaction specificity to BGS in the saliva was very high and its detection sensitivity was found to be approximately 1,000 times greater than has been achieved in a hemagglutination-inhibition test. The monoclonal anti-A and anti-B reagents reacting with both secretor and non-secretor saliva in a hemagglutination-inhibition test and in this ELISA method were selected from among commercial monoclonal antibodies. However, no monoclonal anti-H reagent was found to react with non-secretor saliva. The BGS level was determined by the use of calibration curves of A, B and H standard BGS from human gastric mucosa and was expressed in units, based on the inhibition titer of the standard BGS. In 230 saliva samples, ABH-BGS were detectable, except for H BGS in non-secretor saliva. The BGS levels in saliva stains experimentally prepared were found to be approximately proportional to the levels in the original saliva. As for actual and aged stains, it was possible to detect BGS in most cigarette butts and in aged stains, however, such detection proved impossible in saliva samples from postage stamp.

ABO Blood-Group System↗
PubMed1989

Phosphorylation of the tumor suppressor gene RB protein by M-phase specific histone H1 kinase.

We have noted the presence of the consensus amino acid sequence for phosphorylation by M-phase specific histone H1 kinase in six sites of the tumor suppressor gene retinoblastoma (RB) protein and determined whether or not RB protein is, in fact, phosphorylated by this kinase. Highly purified enzyme was used for this purpose. Human cell extracts immunoprecipitated with anti-RB antiserum as well as RB proteins expressed in Escherichia coli cells were shown to be phosphorylated by this kinase in vitro. Synthetic peptides for the six expected sites were also phosphorylated. These results suggest the possibility that the function of RB protein is regulated by CDC2 kinase. We also noted the presence of putative phosphorylation sites by H1 kinase in a homologous region between the RB gene and L1 family repetitive sequences.

Amino Acid Sequence↗
PubMed1988

Effects of transforming growth factor-beta on deoxyribonucleic acid synthesis and iodine metabolism in porcine thyroid cells in culture.

The effect of transforming growth factor (TGF)-beta on DNA synthesis and iodine metabolism was studied in cultured porcine thyroid cells. TGF-beta dose-dependently inhibited DNA synthesis stimulated by both insulin-like growth factor I and epidermal growth factor but did not affect the number or affinity of receptors for the two growth factors, suggesting that TGF-beta inhibits postreceptor events responsible for initiation of DNA synthesis. TGF-beta was a potent inhibitor of iodine metabolism. When porcine thyroid cells were cultured with TSH for 3 days in the presence of TGF-beta, TSH-induced iodide uptake and organification were reduced at rates that were dependent on the TGF-beta concentrations. The inhibition was detectable at TGF-beta concentrations as low as 50 pg/ml, and complete suppression was seen at 1 ng/ml. Only 6 h of exposure to TGF-beta resulted in a significant inhibition of TSH-induced iodine metabolism. Treatment of thyroid cells with TGF-beta for 3 days did not reduce cAMP production stimulated by TSH. Moreover, the intracellular cAMP level of thyroid cells cultured with TSH plus TGF-beta did not differ from that of cells cultured with TSH alone. TGF-beta decreased iodide uptake stimulated by forskolin or 8-bromo-cAMP. These results strongly suggest that TGF-beta inhibits TSH-stimulated iodine metabolism, at least in part, by affecting events subsequent to cAMP production. The physiological role of TGF-beta remains to be determined, but it may be involved in the regulation of thyroid cell growth and function.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1988

Treatment of acromegaly with long acting somatostatin analogue SMS 201-995.

Ten acromegalic patients were treated with the somatostatin analogue SMS 201-995 (SMS) for 3-38 weeks in various doses and by different administration routines (thrice daily or multiple sc injection). Plasma GH daily profiles, plasma IGF-I, urinary GH, serum TSH, IRI and fasting blood glucose (FBG) concentrations were measured before and during SMS treatment. Plasma GH rapidly decreased within one hour in all patients and was suppressed for at least 4 h after a 50 micrograms sc injection of SMS in 8 patients. Multiple injections of 300-600 micrograms/day SMS (25-50 micrograms X 12) suppressed GH throughout the day. Plasma IGF-I was completely normalized in 4 patients, and, in all but one of the others, decreased markedly. Urinary GH decreased within the first week of treatment in all patients and normalization was obtained in 3 patients. Shrinkage of the pituitary tumor, as determined by CT or MRI, was observed in 7 of 9 patients. Other clinical improvements, such as diminution or complete disappearance of swelling of soft tissues, excessive perspiration, and headache, were observed in 7 of 8 patients. Changes in serum TSH, IRI and FBG were seen in 3-4 patients, but without any apparent clinical problems. In conclusion, SMS is a useful clinical tool for treatment of acromegaly, and a multiple sc injection method seems to be preferable.

Acromegaly↗
PubMed1988

The inhibitory effect of iodide on growth of rat thyroid (FRTL-5) cells.

The effect of iodide on growth of rat thyroid cells (FRTL-5) was studied. TSH-stimulated cell growth was inhibited by iodide in a concentration-dependent manner, and an effect of iodide was detected at 10(-6) mol/l. KClO4 or 1-methylimidazole-2-thiol blocked the effect of iodide, suggesting that iodide uptake and its organification are required to produce the inhibitory effect of iodide on cell growth. Iodide not only decreased TSH-stimulated cAMP production in FRTL-5 cells but also cell growth induced by cAMP. These observations suggest that iodide inhibits TSH-stimulated growth of the cells by attenuating cAMP production and also by acting on the step(s) distal to cAMP generation. The inhibitory effect of iodide was also seen in growth stimulated by insulin, insulin-like growth factor-I or 12-O-tetradecanoyl phorbol 13-acetate, suggesting multiple sites of action of iodide in the process of growth of FRTL-5 cells.

Animals↗
PubMed1988

Chronotropic and inotropic effects of a new angiotensin converting enzyme inhibitor, MC-838 (altiopril calcium), on the dog heart.

The effects of calcium (-)-N-[(S)-3(N-cyclohexylcarbonyl-D-alanyl)-thio]-2-methylpropion] -L- prolinate (MC-838, altiopril calcium), an inhibitor of angiotensin converting enzyme, were investigated in 9 isolated atrial preparations and 7 intact anesthetized donor dogs. In 7 intact dogs, 1-10 mg/Kg of MC-838 caused a decrease in systemic blood pressure, but no significant influence on heart rate was observed. At the same time, in isolated atria perfused with donor's blood, significant increases in developed tension and slight increases in sinus rate were observed with 3 and 10 mg/Kg of MC-838. Intraarterial MC-838 at 10-300 micrograms did not induce significant cardiac effects and MC-838 at 1-3 mg caused an increase in developed tension and a slight increase in sinus rate. The positive inotropic and chronotropic effects were not blocked by adequate doses of propranolol, which significantly blocked norepinephrine-induced positive chronotropic and inotropic effects. It is concluded that a large amount of MC-838 has slight cardiotonic properties which are not mediated via a beta-adrenergic mechanism.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

Phorbol ester pretreatment attenuates the growth hormone (GH) response to GH-releasing factor in cultured rat pituitary cells.

The effect of phorbol ester pretreatment on rat (r) GH release induced by GH-releasing factor (GRF) or 8-bromo-cyclic (c)AMP was investigated using rat pituitary cells cultured in monolayers. Pretreatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) for 3 h significantly suppressed the rGH release induced by GRF, but not that by 8-bromo-cAMP 20 h later; this suppressive effect of TPA was concentration-dependent from 8 to 160 nmol/l, and complete suppression was observed after pretreatment with 80-160 nmol TPA/l. Production of cAMP by pituitary cells stimulated with GRF was similarly attenuated in TPA-pretreated cells. The rGH responsiveness to GRF of these cells was fully recovered on prolonged culture (40 h), suggesting that the inhibitory effect of TPA is reversible. In contrast, pretreatment with GRF (5 nmol/l) resulted in suppression of the rGH response to subsequent exposure to GRF (5 nmol/l) or 8-bromo-cAMP (10 mmol/l), but not to TPA. These observations suggest that pretreatment with TPA modifies the rGH response to GRF at steps before the formation of cAMP.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1988

Characterization of abnormalities in the gamma-globin gene arrangements of Japanese newborns.

Cord blood samples from 889 healthy Japanese newborns from three districts of Honshu Island were studied with the purpose of characterizing the gamma-globin genes in the Japanese. The A gamma T gene frequency was 0.159 which is the same as that found elsewhere in Japan. The haplotype of the chromosome with the A gamma T gene was [-- ++ - + (+ or -) (+ or -)] at eight polymorphic sites. Data from analyses of DNA and the proportion of gamma chains in Hb F showed the existence of various kinds of gamma-globin gene arrangements; six genotypes were observed for individuals with high G gamma values and triple or quadruple gamma-globin gene arrangements, and seven genotypes for babies with low G gamma values and a single gamma-globin gene. The in vivo expression of the gamma-globin gene located at the third or fourth position in the multiple gene arrangement was found to be about 5% and 2.5% of the total, respectively. The haplotype for the chromosomes with a triple gamma-globin gene was [+ --(-)---- +], but that for the chromosomes with a single gamma-globin gene remains unclear. In addition, a new type of Bgl II polymorphism in the G gamma-globin gene was observed.

Fetal Blood↗
PubMed1988

Hyperunstable hemoglobin Koriyama anti-Hb Gun Hill insertion of five residues in the beta chain.

A new hyperunstable hemoglobin was found in a Japanese girl who had very severe, chronic hemolytic anemia. Her parents and siblings were hematologically normal. The abnormal hemoglobin comprised a very small proportion of the total hemoglobin, although it was produced almost at the same rate as normal hemoglobin. Sequencing of an abnormal peptide which was liberated from the beta chain by hydrolysis with a protease from Staphylococcus aureus V8 disclosed the tandem insertion of a five-residue segment which included the proximal histidine at beta 92(F8).

Amino Acid Sequence↗