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Biomedical subjects

S Hirose

Publications and source records attributed to S Hirose.

At least 667 records · Page 37Linked to original sources

[The immune complex].

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Antigen-Antibody Complex↗

[A case of intussusception due to intestinal metastasis of renal carcinoma].

Adult intussusceptions due to metastatic intestinal-tumor are very rare. A 71-year-old man with an intussusception due to intestinal metastasis of renal carcinoma is reported. To our knowledge, this is the third such patient in the Japanese literature. The patient was suffered from an intestinal obstruction six months after his renal carcinoma was detected. Laparotomy was performed, revealing that he had developed a jejunojejunal intussusception due to metastasis of renal carcinoma. The early diagnosis of metastatic intestinal tumor is difficult. It is important to bear in mind that patients with malignant tumor may already have metastasis.

Adenocarcinoma↗

Canada-Cronkhite syndrome associated with systemic lupus erythematosus.

A 43-year-old woman with a history of systemic lupus erythematosus manifested severe diarrhea, generalized gastrointestinal polyposis, pigmentation, and onychodystrophy, which were typical of Canada-Cronkhite syndrome. The exacerbation of systemic lupus erythematosus, presenting with hemolytic anemia and subsequently with profound proteinuria, was seen during the course of this syndrome. The patient achieved complete symptomatic remissions of both entities for more than four years following prednisolone therapy; the resolution of the gastrointestinal polyps was confirmed histologically. This case showed that this syndrome could be completely reversible in its course and that it might have an exogenous cause, as previously suggested.

Adult↗

In vitro biosynthesis of human renin and identification of plasma inactive renin as an activation intermediate.

The biosynthesis and post-translational modifications, including proteolytic processing and core glycosylation, of the human renin precursor have been studied in vitro in a cell-free system. For this purpose, highly enriched renin mRNA was isolated from a renin-producing juxtaglomerular cell tumor and translated in rabbit reticulocyte lysate containing [35S]methionine in the presence or absence of dog pancreas microsomal membranes. Fluorographic analysis of the radioactive translation products, immunoprecipitated and then resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, revealed that the primary translation product, preprorenin (Mr = 45,000), is initially processed to glycosylated prorenin (Mr = 47,000) during or shortly after its sequestration into the lumen of the microsomal membranes. The vectorial translocation across the membrane was confirmed by the observation that the proform was resistant to digestion with trypsin while preprorenin was sensitive. Radiosequencing and the use of prorenin-specific antibodies established the cleavage points of the pre- and profragment and showed that the in vitro precursor of human renin contains a 23-residue signal peptide and a 43-residue prosegment. The post-translational modification which, despite the removal of signal peptide, resulted in an increase in apparent Mr, reflects the glycosylation as examined using Xenopus oocytes microinjected with renin mRNA in the presence of tunicamycin, an inhibitor of protein glycosylation. Four anti-peptide antibodies which specifically recognize the NH2 terminus (Pro 1), two middle parts (Pro 2A and Pro 2B), and COOH terminus (Pro 3) of the prosegment, respectively, have been raised and used to characterize plasma prorenin. Renin precursors (pre- and prorenin) synthesized in vitro or in the kidney reacted with these antibodies (anti-Pro 1, anti-Pro 2A, anti-Pro 2B, and anti-Pro 3). However, quite unexpectedly, human plasma prorenin was recognized only by anti-Pro 3, indicating that plasma prorenin is a truncated version of intact prorenin, which lacks a large portion of the NH2 terminus of the prosegment and may represent an activation intermediate. This somewhat surprising result may lead to a better understanding of the exact roles and activation mechanisms of plasma prorenin existing in a relatively large amount.

Amino Acid Sequence↗

Determination of m- and p-O-methylated products of L-3,4-dihydroxyphenylalanine using high-performance liquid chromatography and electrochemical detection.

In a study of in vitro and in vivo metabolism of L-3,4-dihydroxyphenylalanine (L-Dopa), two methods of high-performance liquid chromatography (HPLC) were used to separate the m- and p-O-methylated products. A reversed-phase column and an aqueous mobile phase by gradient elution were used; the elute was analyzed electrochemically with a single amperometric and dual coulometric electrode. The L-Dopa and its O-methylated products could be detected individually in the enzymatic methylation of rat liver homogenate and in patients with Parkinson's disease. Meta/para ratios of O-methylation are easily obtained by this method.

Animals↗

Enhanced transcription of fibroin gene in vitro on covalently closed circular templates.

A modified method for S1 nuclease assay has been developed to quantitate an amount of radioactive transcripts in the presence of unlabeled homologous RNA. Using this method, we have assayed in vitro transcription of fibroin gene on circular and linear templates. In a posterior silk gland cell extract, covalently closed circular (ccc) DNA forms the superhelical state and supports three to 10 times more transcription than nicked circular or linear DNA does. The efficient transcription on ccc template is also observed in a middle silk gland cell extract but never seen in a HeLa cell extract. When the posterior silk gland cell extract is first incubated with pBR322 DNA and then challenged for the fibroin gene transcription on ccc DNA, the pBR322 DNA of the ccc form, but not of the linear one, inhibits the reaction. A deletion mutant carrying only 44 base pairs of the 5'-flanking sequence reserves the preference of the ccc template, but seven single-point mutants at the TATA box and -20 region abolish it. These results suggest that some components in the silk gland extract supercoil ccc DNA and stimulate the fibroin gene transcription in the absence of the upstream enhancing sequence.

Animals↗

Solubilization and molecular weight estimation of atrial natriuretic factor receptor from bovine adrenal cortex.

Receptors for atrial natriuretic factor (ANF) have been solubilized with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate from bovine adrenal cortex and characterized. The detergent extract retained specific high-affinity binding sites for 125I-ANF. Scatchard analysis of the equilibrium binding data revealed a single class of binding site with a K-d of 1.8 nM and a maximum binding capacity of 2.5 pmol/mg of protein. The size of the 125I-ANF X receptor complexes was estimated to be 140,000 daltons by gel filtration on TSK gel G3000SW. Affinity labeling followed by electrophoresis under nonreducing conditions and autoradiography also revealed a single band of a similar size (Mr = 130,000); this band, however, migrated as a Mr = 70,000 species under reducing electrophoretic conditions. These results indicate that the ANF receptor, having a Mr of 130,000 - 140,000, is composed of disulfide-linked subunits and the ANF-binding site is located on the 70-kDa component.

Adrenal Cortex↗

Purification and mode of action of a microsomal endoribonuclease from rat liver.

An endoribonuclease has been purified nearly to homogeneity from rat liver microsomes, and its mode of action and general properties were studied. The enzyme had an apparent molecular weight of 58 000, as estimated by both gel filtration and SDS-polyacrylamide gel electrophoresis and produced oligonucleotides from poly(A), poly(U) and poly(C). No mononucleotide was obtained by the enzymatic hydrolysis of the above substrates. The enzyme made endonucleolytic cleavages which generated 5'-phosphate-terminated oligonucleotides. It was suggested that the existence of at least (Ado5'P)2 residues at both sides of the cleavage bond was necessary for the action of the endoribonuclease. Divalent cations (Mg2+ or Mn2+) were required for the enzymatic activity, while K+ inhibited the enzyme. Spermine stimulated the enzymatic activity in the presence of 1 mM Mg2+.

Animals↗

Purification and mode of action of a microsomal exoribonuclease from rat liver.

An exoribonuclease has been purified nearly to homogeneity from rat liver microsomes and its mode of action and general properties were studied. The molecular weight values for the enzyme, as estimated by gel filtration and SDS-polyacrylamide gel electrophoresis, were 88 000 and 92 000, respectively. The enzyme produced, via a processive mechanism Ado5'P as the only product from poly(A). The results of the hydrolysis of 4 S (Ado5'P)n and (Ado3'P)n by the exoribonuclease with or without alkaline phosphatase and the inhibition of the enzymatic activity by oligonucleotides having a 3'-phosphate group in the 3'-terminus suggested that the degradation proceeds in the 3' to 5' direction. These findings were confirmed by the analysis of hydrolyzed products of various oligoadenylates and Ado3'PUrdPGuo and by the comparison of the rates of hydrolysis of (Ado3'P)2Ado by the enzyme in the presence of varying amounts of (Ado3'P)3. Mg2+ was required for the enzymatic activity, and Mn2+ partially substituted for Mg2+. The activity of the enzyme was stimulated by K+ and spermine.

Alkaline Phosphatase↗

Simultaneous assay of 3,4-dihydroxyphenylalanine, catecholamines and O-methylated metabolites in human plasma using high-performance liquid chromatography.

We devised a procedure for the simultaneous determination of 3,4-dihydroxyphenylalanine, catecholamines and O-methylated metabolites using a reversed-phase liquid chromatographic system. Detection is achieved by an electrochemical detector and a fluorescence detector connected in series. Sample preparation is kept to a minimum, and involves precipitation of proteins with trichloroacetic acid and perchloric acid, and subsequent neutralization, thus omitting the commonly adopted adsorption step. Chromatographic peaks were identified on the basis of retention behaviour and the ratio of responses at several oxidation potentials. The method was applied to the quantitative determination of 3,4-dihydroxyphenylalanine, catecholamines and O-methylated metabolites in human plasma.

Catecholamines↗

Identification of plasma inactive renin as prorenin with a site-directed antibody.

A sequence-specific antibody that recognizes a portion of the prosegment of human renin precursor was raised and used to provide direct evidence that plasma inactive renin contains the prosequence of renal renin and is therefore probably prorenin rather than an inactivated form of previously active renin. The information may help not only to resolve a major controversy concerning the nature of inactive renin in human plasma but also to elucidate its exact physiological role.

Antibody Formation↗