Search PubMed⌕ Search

Biomedical subjects

K Oda

Publications and source records attributed to K Oda.

At least 541 records · Page 30Linked to original sources
PubMed1986

Effects of weakly basic amines on proteolytic processing and terminal glycosylation of secretory proteins in cultured rat hepatocytes.

We examined the effects of weakly basic amines on the secretion and post-translational modifications of secretory proteins in cultured rat hepatocytes. Weakly basic amines such as methylamine, chloroquine and NH4Cl strongly inhibited not only protein secretion, but also the proteolytic conversion of a proform of complement C3, allowing the precursor to be released into the medium. The amines, however, had no effect on the proteolytic conversion of prohaptoglobin into its subunits. Since available evidence indicates that the conversion of pro-C3 occurs at the Golgi complex while that of prohaptoglobin takes place in the endoplasmic reticulum, it is most likely that the weak bases specifically affect the proteolytic event occurring at the Golgi complex. Electron microscopic observations confirmed that the amines caused morphological changes of the Golgi complex, consisting of dilated cisternae and swollen vacuoles. When the glycosylation of alpha 1-protease inhibitor and haptoglobin was examined, it was found that the amines caused a marked accumulation in the cells of both glycoproteins corresponding to the mature secreted forms. Neuraminidase digestion demonstrated that the glycoproteins accumulating in response to the amines had acquired terminal sialic acid. The results indicate that the amines do not significantly affect terminal glycosylation, in contrast with their definite effect on proteolytic processing, despite the fact that both modifications take place in the Golgi complex.

Amines↗
PubMed1986

Regulation of renal sulfoglycolipid biosynthesis.

The in vitro activity of the renal galactolipid sulfotransferase and the level of sulfated glycolipids in the rat kidney have been correlated as a function of age. The galactolipid sulfotransferase was found to be greatly reduced in the young as compared with the adult animal. The relatively minor changes in the sulfated glycolipid content of the kidney with age suggests that an increase in sulfoglycolipid turnover occurs during growth. An inhibitory activity was detected in the homogenate supernate of the young animal capable of reducing the in vitro sulfotransferase activity of the adult. Assay of the human renal galactolipid sulfotransferase showed that this enzyme activity is deleted in samples of the blastematous form of Wilm's renal tumor. The results suggest that the rate of synthesis of renal sulfoglycolipids may prove a marker of renal development, perhaps by post translational regulation.

Aging↗
PubMed1986

Polypeptides coded for by the region pre-S and gene S of hepatitis B virus DNA with the receptor for polymerized human serum albumin: expression on hepatitis B particles produced in the HBeAg or anti-HBe phase of hepatitis B virus infection.

There are four polypeptides coded for by the region Pre-S and gene S on DNA of hepatitis B virus that carry the receptor for polymerized human serum albumin (poly-HSA), i.e., P31 and P39, as well as their glycosylated counterparts P35 and P43. With the use of monoclonal antibodies directed to Pre-S(1) sequence and Pre-S(2) sequence (bearing the receptor for poly-HSA), the content of these polypeptides, as well as their expression on the surface, was determined for hepatitis B particles of various categories. P39 and P43, carrying both Pre-S(1) and Pre-S(2) sequences, were contained abundantly in Dane and tubular particles, and to a much lesser extent in small spherical particles, all of which were purified from plasma containing hepatitis B e antigen (HBeAg). P31 and P35, carrying Pre-S(2) but not Pre-S(1) sequence, were contained comparably in these three categories of hepatitis B particles. In remarkable contrast, small spherical particles derived from plasma containing antibody to HBeAg were very low in the content of any Pre-S polypeptides. P31 and P39 showed higher activities for poly-HSA receptor than their glycosylated versions. When Dane particles were digested with trypsin, the poly-HSA receptor was deprived in parallel with the loss of antigenicity for Pre-S(2) sequence. The antigenicity for Pre-S(1) sequence was much less affected, and that for the product of gene S was virtually unchanged by the digestion.

Amino Acid Sequence↗
PubMed1986

Large hepatitis B surface antigen polypeptides of Dane particles with the receptor for polymerized human serum albumin.

Large hepatitis B surface antigen polypeptides with apparent molecular sizes of 39,000 and 43,000 daltons (P39 and P43) were liberated from a purified preparation of Dane particles of subtype adr. They were tested for reactivity with monoclonal antibodies raised against three synthetic oligopeptides representing fundamental sequences of the pre-S region in deoxyribonucleic acid of hepatitis B virus (subtype adr), as well as with monoclonal antibody against the major surface antigen polypeptide (P22) coded for by the S gene. Both P39 and its glycosylated form P43 bound to all four monoclonal antibodies, thereby indicating that they were coded for by the sequence of 1200 nucleotides, from the second ATG codon in the pre-S region to the stop codon of the S gene. Both P39 and P43 bound to polymerized human and chimpanzee albumins, but not to polymerized albumin from species without susceptibility to hepatitis B virus. Due to their presence in Dane particles and the expression of a polyalbumin receptor, the immune responses against P39 and P43 may have significance in infection with hepatitis B virus and its immunoprophylaxis.

Antibodies, Monoclonal↗
PubMed1986

Motor innervation and acetylcholine receptor distribution of human extraocular muscle fibres.

Motor innervation and acetylcholine receptor distribution of human extraocular muscle (EOM) fibres were investigated by using combined silver and acetylcholinesterase (AChE) staining method and [125I]alpha-bungarotoxin autoradiography. Three types of motor endplates were distinguished; (A) a large compact ending on a large-diameter fibre, (B) several endings regularly spaced on an intermediate-diameter fibre, each of which consisted of small stained particles and (C) numerous small endings scattered as a chain of beads on a small-diameter fibre. Type A fibre was singly innervated, while type B and C had multiterminal (possibly polyneuronal) innervation. These results indicate that the organization of human EOM endplates is quite different from that of limb muscle endplates and may provide some implications to understand the pathophysiology of the neuromuscular diseases, for example, myasthenia gravis.

Acetylcholinesterase↗
PubMed1986

Induction of alkaline phosphatase and its transport to cell surface in primary culture of rat hepatocytes: effect of the antimicrotubular agent colchicine.

We have examined the effect of colchicine on the induction of alkaline phosphatase and its transport to the cell surface in a primary culture of rat hepatocytes. When freshly isolated hepatocytes were subjected to primary culture, alkaline phosphatase activity increased linearly starting at 6 h and reached a maximum level (about 10 times the initial activity) at 24 h after seeding. Radioimmunoassay with 125I-(anti-alkaline phosphatase)-IgG confirmed that the increase in enzyme activity was due to the increased amount of enzyme protein. The presence of colchicine in the culture medium (10-50 microM) did not cause an additive effect on the enzyme induction, in contrast to the previous results obtained in in vivo experiments (Ikehara, Y. et al. (1978) J. Biochem. 84, 1335-1338; Oda, K. & Ikehara, Y. (1981) Biochim. Biophys. Acta 640, 398-408). However, translocation of the induced enzyme to the cell surface was inhibited by colchicine in a dose-dependent manner. These results suggest that the enzyme induction by colchicine observed in vivo might not be due to its direct effect on hepatocytes, and that microtubules are involved in intracellular transport of the newly synthesized membrane protein.

Alkaline Phosphatase↗
PubMed1986

Immunoblotting analysis of plasma protein processing in the secretory pathway of rat liver: identification of proteolytic conversion sites of complement pro-C3 and prohaptoglobin.

Using an immunoblotting technique, we have studied the processing of plasma proteins in subcellular fractions of rat liver including rough and smooth microsomes and the Golgi subfractions. Each subcellular fraction was directly subjected to SDS-polyacrylamide gel electrophoresis and analyzed by immunoblotting with antibodies against alpha 1-protease inhibitor, haptoglobin, and the third component of complement (C3) in combination with 125I-protein A or 125I-rabbit anti-(goat IgG)-IgG. The results demonstrated that proteolytic processing of precursors of complement C3 and haptoglobin occurs in different compartments along the secretory pathway; conversion of prohaptoglobin takes place in the endoplasmic reticulum, while that of pro-C3 occurs in the Golgi complex. The processing in oligosaccharide chains of glycoproteins was also analyzed. The Golgi fraction was characterized by the presence of the mature 56 kDa alpha 1-protease inhibitor, which was indistinguishable from the serum alpha 1-protease inhibitor in SDS-polyacrylamide gel electrophoresis. In contrast, the immature 51 kDa form was the only form of alpha 1-protease inhibitor found in the microsomal fraction. Similar results were obtained for the beta subunit of haptoglobin; the immature 33 kDa form was detected in the microsomal fraction, while the mature 36 kDa form was found in the Golgi fraction. Taken together, these results identified the intracellular sites where these plasma proteins are modified by selective proteolysis and/or glycosylation.

Animals↗
PubMed1986

Isolation and amino acid sequence of a peptide containing an epoxide-reactive residue from the thermolysin-digest of Scytalidium lignicolum acid protease B.

Scytalidium lignicolum acid protease B, a pepstatin-insensitive acid protease, was modified by 1,2-epoxy-3-(p-nitrophenoxy)propane (EPNP) with the concomitant loss of its enzyme activity, and an EPNP-labeled peptide was isolated from the thermolysin-digest of the modified enzyme by HPLC. The amino acid sequence of the peptide was determined to be Ile-Leu-Glu-Thr-Gly, which corresponds to the sequence of residue Nos. 51-55 of the enzyme. The results of treatment of the labeled peptide with hydroxylamine suggested that the EPNP moiety is ester-linked to Glu53 of the enzyme. The amino acid sequence around Glu53 of the acid protease B showed high homology with those around the active site Asp residues of calf chymosin and porcine pepsin. These results show that it is highly possible that Glu53 of the acid protease B is one of the amino acid residues involved in its catalytic activity.

Amino Acid Sequence↗
PubMed1986

Mitogenic activity of the adenovirus type 12 E1A gene induced by hormones in rat cells.

Several lines of rat 3Y1 cells in which expression of the adenovirus type 12 E1A gene can be regulated by dexamethasone were established by introduction of recombinant vector DNA containing the adenovirus type 12 E1A gene placed downstream of the hormone-inducible promoter of mouse mammary tumor virus. These cell lines (gMA cells) produced low basal levels of the E1A transcripts and proteins in normal medium and much higher levels upon addition of dexamethasone to the medium. When dexamethasone was added to density-arrested cells, DNA synthesis was induced in 10 to 40% of the cells, the percentage depending on the cell line. DNA synthesis was increased to up to 60% of the cell population by further addition of epidermal growth factor. Indirect immunofluorescence detection of E1A proteins in gMA cells treated with dexamethasone indicated that the intensity of fluorescence in cells varied and that the proportion of cells synthesizing DNA was correlated with the proportion that exhibited strong fluorescence. These results indicate that the E1A gene has a function to trigger the synthesis of cellular DNA.

Adenovirus Early Proteins↗
PubMed1986

Responsiveness of hypophyseal-adrenocortical axis to repetitive administration of synthetic ovine corticotropin-releasing hormone in patients with isolated adrenocorticotropin deficiency.

The primary lesion site in isolated ACTH deficiency was studied in three patients by examining the responses of immunoreactive ACTH to insulin-induced hypoglycemia, lysine vasopressin, and synthetic ovine corticotropin-releasing hormone (CRH). In all patients, no significant changes in immunoreactive ACTH followed insulin-induced hypoglycemia or lysine vasopressin. Fifty micrograms (greater than or equal to 1 microgram/kg BW) of CRH administered as an iv bolus dose daily for 6 consecutive days elicited no significant increase in plasma immunoreactive ACTH, beta-lipotropin, or cortisol levels in all patients. Eight iv bolus injections of 0.63 microgram/kg BW CRH at 4-h intervals also failed to induce a significant response of immunoreactive ACTH to an iv bolus dose of 1 microgram/kg CRH at 36 h in one patient. In contrast, a single bolus dose of 50 micrograms CRH induced a response of plasma immunoreactive ACTH in a patient with Cushing's disease and a patient with Addison's disease. The present results suggest that the primary lesion of isolated ACTH deficiency is not the hypothalamus, but, rather, is located in pituitary ACTH-secreting cells.

Addison Disease↗
PubMed1986

Myasthenia gravis: antibodies to extracellularly exposed antigenic determinants of acetylcholine receptor.

We have used a simple method to detect autoantibodies that react with extracellularly exposed antigenic determinants of acetylcholine receptor (AChR) of cultured rat muscle. Immunoglobulins from 30 patients with myasthenia gravis contained antibodies to detergent-solubilized AChR and bound to extracellularly exposed AChR. The antibody titer with solubilized rat AChR did not correlate with clinical severity, but ability of antibody to bind to extracellularly exposed AChR did correlate well and was also closely related to the acceleration of AChR degradation.

Adult↗
PubMed1986

Chronic polymyositis: presence of coxsackievirus A9 antigen in muscle.

We report a case of chronic recurrent polymyositis associated with increasing antibody titers of coxsackievirus A9 in serum during clinical exacerbations. Muscle biopsy specimens showed pathologic changes consistent with chronic myositis, including perivascular mononuclear cell infiltration and hyalinization of muscle fibers with cytoplasmic vacuolations. The specific fluorescence was observed in the muscle fibers stained with antiserum for coxsackievirus A9. These findings indicate that this viral subtype as the etiologic agent in this case and virus plays a pathogenic role in some cases of chronic polymyositis.

Antigens, Viral↗
PubMed1986

Translation products of pre-S(1), pre-S(2) regions and the S gene of hepatitis B virus: susceptibility of their antigenic activities to treatment with heat, urea, formalin or pepsin.

Hepatitis B subviral particles, purified from plasma of asymptomatic carriers seropositive for hepatitis B e antigen, were treated with various conditions reported for the processing of vaccines. Thereafter, antigenic activities displayed by the translation products of pre-S(1), pre-(2) regions and the S gene were determined with monoclonal antibodies, and the reactivity for polyalbumin receptor was tested. Heating at 100 degrees C for 1.5 min and then at 65 degrees C for 10 h preserved more than 1/2 of antigenic activities representing products of pre-S(1), pre-S(2) regions and the S gene. After incubation in the presence of 8 M urea at 37 degrees C for 4 h, more than 2/3 of antigenic activities still remained. The antigenic activity of the S gene product was decreased to 2/3 and that of pre-S(2) region product to 1/3, after treatment with formalin at the final concentration of 1:4000 at 37 degrees C for 72 h, whereas the activity of pre-S(1) region product was affected drastically. Although 1/5 of the antigenic activity of the S gene product survived the digestion with pepsin for 18 h, antigenic activities of pre-S(1) and pre-S(2) region products were destroyed almost completely. Polyalbumin receptor, borne by the pre-S(2) region product, was lost by pepsin digestion also. Based on the results obtained, heating may be most appropriate for sterilizing plasma-derived hepatitis B particles for use as a vaccine, because it is reliably virucidal and would not affect the protective efficacy to an extent as the other virucidal methods would.

Epitopes↗