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M Odawara

Publications and source records attributed to M Odawara.

At least 73 records · Page 4Linked to original sources
PubMed1993

Stable positively charged liposome during long-term storage.

The effect of taurine, as an isotonic solute, and of benzalkonium chloride (BZC), as a positive membrane component, on the long-term stability of liposomal suspensions was investigated by measuring surface potential. The surface potential, which introduced electrostatic repulsion to liposomes against aggregation, increased dose-dependently with the addition of BZC, which gave a positive charge. However, a further addition of BZC caused unexpected aggregation during storage, so the optimum addition of BZC was defined. On the other hand, taurine, which forms a zwitter ion in an aqueous solution, did not reduce the surface potential, suggesting that taurine is of possible utility as an isotonic solute. As the result of stability testing, the liposomal system using taurine and BZC was stable against aggregation during 6 months at 40 degrees C. We were successful in developing a stable, positively charged liposomal system during long-term storage, and our liposomal system is believed to be of wide utility as a drug carrier for therapeutic drugs applied topically to negatively charged mucosal tissues. We applied the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to estimate the colloidal stability of liposomes. As a result of stability testing, positively charged liposomes had a good correlation between maximum total repulsive energy (VT(max)/kT) between two liposome particles and colloidal stability, suggesting that the VT(max)/kT value is useful for estimating stability and for designing liposomal preparations containing some ionic substances.

Benzalkonium Compounds↗
PubMed1992

Detection of mutations in the insulin receptor gene in patients with insulin resistance by analysis of single-stranded conformational polymorphisms.

We analyzed single-stranded conformational polymorphisms to screen for mutations and polymorphisms in the insulin receptor gene in subjects with or without insulin resistance. Using this new technique, we demonstrated the existence of mutations in the insulin receptor gene which we had identified previously. In addition, a new mutation was found in exon 20 of the insulin receptor gene in a patient with moderate insulin resistance associated with morbid obesity, acanthosis nigricans, and polycystic ovary syndrome. The patient was heterozygous for a mutation substituting Leu (CTG) for Pro (CCG) at codon 1178. Pro1178 is a part of a characteristic sequence motif (D1150 F1151 G1152---A1177 P1178 E1179) common to many protein kinases. Analysis of single-stranded conformational polymorphisms was also used to estimate the frequency of a polymorphism at codon 1058. The two codons CAC (1058 His) and CAT (1058 His) both had a prevalence of 50% in 30 Japanese subjects. These data demonstrate that analysis of single-stranded conformational polymorphisms is a simple and sensitive screening method for mutations and polymorphisms in the insulin receptor gene in subjects with or without insulin resistance. Identification of a mutation in the insulin receptor gene in a patient with a moderate degree of insulin resistance associated with morbid obesity suggests that insulin receptor mutations may exist in patients with Type 2 (non-insulin-dependent) diabetes mellitus associated with a moderate degree of insulin resistance.

Amino Acid Sequence↗
PubMed1990

Phosphorylation state and biological function of a mutant human insulin receptor Val996.

Chinese hamster ovary (CHO) cell transfectants that expressed human insulin receptors whose glycine 996 was substituted by valine were studied. Receptor processing and insulin binding were unaffected by this mutation; however, this mutant insulin receptor had little or no tyrosine kinase activity. Nevertheless, the Val996 mutant exhibited seryl and threonyl phosphorylation in both the basal and insulin-stimulated state in intact cells. This is in contrast to the Lys----Ala1018 tyrosine kinase deficient mutant (Russell, D. S., Gherzi, R., Johnson, E. L., Chou, C-K., and Rosen, O. M. (1987) J. Biol. Chem. 262, 11833-11840). Cells expressing the normal human receptor were 10-fold more sensitive to insulin than the untransfected CHO cells with respect to phosphorylation of a cellular substrate (pp 185) on tyrosyl residues, glucose incorporation into glycogen, thymidine incorporation into DNA, and phosphorylation of ribosomal protein S6. Cells expressing the mutant receptor exhibited the same insulin sensitivity as the untransfected CHO cells. Insulin was rapidly internalized in cells expressing the normal human receptor and the number of receptors expressed on the cell surface was decreased in response to exposure to insulin. However, little insulin was internalized in cells expressing the mutant receptor, and the number of receptors on the cell surface was not significantly diminished in response to exposure to insulin. It is concluded that despite the occurrence of seryl and threonyl phosphorylations, post-receptor effects of insulin described above are not mediated by the tyrosine kinase-deficient receptor, Val996.

Amino Acid Sequence↗
PubMed1990

Defect in tyrosine kinase activity of the insulin receptor from a patient with insulin resistance and acanthosis nigricans.

We report here a defect in tyrosine kinase activity of the insulin receptor from an insulin-resistant patient with acanthosis nigricans using cultured Ebstein-Barr virus (EBV)-transformed B-lymphocytes. As judged by affinity labeling and immunoblotting, the alpha- and beta-subunits of insulin receptors from the patient's lymphocytes exhibited the same mol wt as those from control subjects. Lectin-purified extracts from lymphocytes of the patient and the control subjects containing the same insulin-binding capacity were assayed for autophosphorylation and the ability to phosphorylate histone H2B. The degree of insulin-dependent autophosphorylation and the tyrosine kinase activity of the insulin receptor from the patient's lymphocytes were decreased to 15% and 13%, respectively, in a cell-free system. The insulin-dependent autophosphorylation of the insulin receptor was also impaired in intact EBV lymphocytes from the patient. Consistent with these results, we found that one of this patient's alleles had a mutation in which valine is substituted for Gly996, the third glycine in the conserved Gly-X-Gly-X-X-Gly motif in the kinase domain. Thus, it seems likely that the defect in tyrosine kinase activity of the insulin receptor cause the insulin resistance in this patient. The EBV lymphocyte can be a good system to detect genetically determined abnormalities in the insulin receptor.

Acanthosis Nigricans↗
PubMed1989

Human diabetes associated with a mutation in the tyrosine kinase domain of the insulin receptor.

Insulin receptor complementary DNA has been cloned from an insulin-resistant individual whose receptors have impaired tyrosine protein kinase activity. One of this individual's alleles has a mutation in which valine is substituted for Gly996, the third glycine in the conserved Gly-X-Gly-X-X-Gly motif in the putative binding site fo adenosine triphosphate. Expression of the mutant receptor by transfection into Chinese hamster ovary cells confirmed that the mutation impairs tyrosine kinase activity.

Alleles↗
PubMed1988

Glucocorticoids increase insulin binding and the amount of insulin-receptor mRNA in human cultured lymphocytes.

The effect of steroid hormones on insulin binding and the amount of insulin-receptor mRNA was examined in IM-9 lymphocytes. Cortisol and cortexolone, but not oestrogen, increased both the binding of insulin and the amount of insulin-receptor mRNA in a time- and dose-dependent manner. Cortisol was most potent, and induced a 2-fold increase in insulin binding and a 4-fold increase in mRNA. The elevation in binding was due to an increased number of insulin receptors at the cell surface. The increase in mRNA involved all four of the insulin-receptor mRNAs and could not be inhibited by cycloheximide. The cortisol-induced increase in mRNA was associated with a 3-4-fold increase in the synthesis of pro-receptor. The relative potency of the three steroids indicated that these effects were mediated by an interaction with the glucocorticoid receptor. The results of this study suggest that cortisol can increase the number of insulin receptors at the cell surface by increasing the amounts of insulin-receptor mRNA and the synthesis de novo of insulin receptors.

17-Hydroxycorticosteroids↗
PubMed1977

Carcino-fetal proteins and gastric cancer: the site of alpha-fetoprotein synthesis in gastric cancer.

Although several investigators have reported serum alpha-fetoprotein positive gastric cancer with or without metastasis to the liver, its site of production is still unclear. We studied on the site of alpha-fetoprotein synthesis in our cases which showed remarkably high level of serum alpha-fetoprotein, and clarified the presence of alpha-fetoprotein producing gastric cancer by means of direct immunofluorescent technique. However, we also knew the hepatocytes adjacent ot the metastatic lesions could also synthesize alpha-fetoprotein, although these hepatocytes were not known whether under regeneration or degeneration. Through this study, the other carcinofetal proteins such as carcino-placental alkaline phosphatase and CEA were examined using the sera or tumor tissues. Our results will support the idea that cancer is the disease of cell differentiation.

Adenocarcinoma↗