Search PubMed⌕ Search

Biomedical subjects

M Homma

Publications and source records attributed to M Homma.

At least 235 records · Page 13Linked to original sources
PubMed1987

Identification of the M-ring protein of the flagellar motor of Salmonella typhimurium.

The M ring is a substructure of the flagellar basal body of bacteria, which lies in the cytoplasmic membrane and is therefore close to the site where the energy of the transmembrane proton potential is converted into mechanical work of rotation of the motor. The protein from which this ring is constructed has not been identified. Flagellar hook-basal body complexes from Salmonella typhimurium were used as the immunogen for the preparation of monoclonal antibodies. An antibody obtained was directed against a major basal-body component, a 65-kDa protein that from mutant studies has been assigned as the product of the flaAII.1 gene. By immunoelectron microscopy, the antibody was observed to bind the innermost feature of the basal body: the cytoplasmic-facing surface of the M ring. We conclude that the 65-kDa protein is a component--probably the main component--of this important substructure of the flagellar motor.

Antibodies↗
PubMed1987

Single amino acid substitution of Sendai virus at the cleavage site of the fusion protein confers trypsin resistance.

Amino acid sequences of fusion (F) proteins of two trypsin-resistant mutants of Sendai virus, TR-2 and TR-5, were deduced from nucleotide analysis of cDNA encoding the F gene and were compared with that of the trypsin-sensitive wild-type Sendai virus. In both mutants, amino acid substitutions were found at residues 116 (Arg----Ile), the cleavage site of the F protein, and 109 (Asn----Asp). Two trypsin-sensitive revertants, TSrev-52 and TSrev-58, derived from TR-5 were both activated by trypsin similarly to the wild-type virus and had a single amino acid reversion from Ile to Arg at residue 116, leaving Asp as before at residue 109. These results indicate that the trypsin sensitivity of Sendai virus can be changed by a single amino acid substitution at the cleavage site of the F protein and a mutation from Arg to Ile is responsible for the acquisition of resistance to trypsin.

Amino Acid Sequence↗
PubMed1987

Distribution of the antibody to influenza C virus in dogs and pigs in Yamagata Prefecture, Japan.

The distribution of the antibody to influenza C virus in the dogs and pigs in Yamagata prefecture, Japan was investigated by using three different serological methods: hemagglutination-inhibition (HI), radioimmunoprecipitation (RIP), and immunoblotting. The antibody against influenza C virus glycoprotein (gp88) was detected in 5 out of 112 sera collected from mongrel dogs, three by RIP test and two by any of the three methods, suggesting that the virus can cause natural infection in dogs. Significant levels of HI activity were found in 58 out of 269 sera collected from domestic pigs, but none of them showed positive reaction in the more sensitive method, RIP, which suggests that the inhibitors against the hemagglutination by influenza C virus rather than the antibody to gp88 are responsible for the observed HI activity. It appears, therefore, that at least in the Yamagata area, pigs do not play significant roles in the spread of influenza C virus in humans.

Animals↗
PubMed1987

Follow-up study of type C influenza outbreak in a children's home.

A follow-up study of type C influenza in a children's home was made where the first outbreak of type C influenza occurred in March, 1981. During the survey period of 2 years, 2 additional outbreaks occurred in April and October, 1982 and 4 cases of the secondary and 2 cases of the tertiary infections were serologically confirmed. All of the children exposed to the outbreaks, except 2 particular cases who were suffering from German measles, showed similar mild respiratory symptoms characterized by fever and long-lasting nasal discharge, irrespective of primary, secondary, and tertiary infections. No case of inapparent infection was observed. Incubation period was estimated to be not longer than 5 days and the period of virus shedding, to be longer than 22 days. Antibody response in the sera of patients to type C influenza virus was equally good after every infection, although it was not efficient to prevent the succeeding infection. Factors involved in the repeated infections of type C influenza were discussed.

Adult↗
PubMed1987

Regions of Salmonella typhimurium flagellin essential for its polymerization and excretion.

Immunological methods were used to examine the flagellin production of Salmonella typhimurium strains that carried a mutation in one of the two possible genes for flagellin (H1 or H2) and also were incapable of expressing the other gene. Some mutants produced flagellin that was excreted into the culture medium; others accumulated flagellin intracellularly. These two phenotypes were detected in both H1 and H2 mutants. The mutation sites were mapped on the corresponding deletion map (consisting of 21 segments in the case of H1 and 31 segments in the case of H2). H1 and H2 mutations causing excretion of flagellin were clustered mainly in segment 12 and segment 6 from the proximal end, respectively, suggesting that the corresponding segments of the flagellins play a role in polymerization. Mutations causing accumulation in the cytoplasm were clustered in segments 19 to 21 of the H1 map and in segments 25 to 29 of the H2 map, suggesting that an essential region for flagellin transport exists toward the C terminus of flagellin.

Bacterial Proteins↗
PubMed1987

Localization and stoichiometry of hook-associated proteins within Salmonella typhimurium flagella.

The localization of hook-associated proteins (HAP1, HAP2, and HAP3) in Salmonella typhimurium flagella was studied by using specific antibodies together with a second antibody conjugated with colloidal gold. HAP1 and HAP3 were localized at the hook-filament junction, as has been suggested previously. HAP2, however, was localized at the filament tip. This finding supports the idea that HAP2 acts to induce polymerization of endogenous flagellin at the filament tip, and HAP1 and HAP3 are junction proteins to connect hook with filament. Analysis of the protein composition of short flagella from a mutant indicated that a single flagellum contains about 10 to 20 HAP1, 10 to 20 HAP2, and 10 to 40 HAP3 molecules.

Antibodies↗
PubMed1987

Formation of flagella lacking outer rings by flaM, flaU, and flaY mutants of Escherichia coli.

Among flagellar mutants of Escherichia coli, flaM or flaU mutants form basal bodies lacking the outer P and L rings, whereas flaY mutants predominantly form basal bodies lacking the L ring. In these mutants, hooks and filaments are occasionally assembled onto these incomplete basal bodies. When the hook protein gene, flaFV, of Salmonella typhimurium was cloned on the multicopy plasmid pBR322 and introduced into these mutants, the efficiency with which cells assembled hooks and filaments onto the incomplete basal bodies increased significantly. Such cells formed characteristic dotted swarms on semisolid plates, indicating that cells carrying flagella without the outer rings are weakly motile because of poor function of their flagella, a low flagellar number per cell, or both of these defects. FlaV mutants also produced incomplete basal bodies lacking the outer rings, but assembly of hooks and filaments did not occur in these mutants even after introduction of the plasmid carrying flaFV of S. typhimurium. The failure in the case of flaV mutants was attributed to their inability to modify the rod tip to the structure competent for assembly of hook protein.

Bacterial Proteins↗
PubMed1987

Identification of proteins of the outer (L and P) rings of the flagellar basal body of Escherichia coli.

Synthesis of the Salmonella typhimurium hook protein from the gene cloned on a multicopy plasmid results in partial suppression of the flagellar assembly defects of certain classes of Escherichia coli mutants (K. Ohnishi, M. Homma, K. Kutsukake, and T. Iino, J. Bacteriol, 169:1485-1488, 1987). This phenomenon allowed hook-basal body complexes from such mutants to be purified and analyzed by electron microscopy and gel electrophoresis. The absence of the P and L rings in such structures was found to correlate with the absence of proteins of apparent molecular weight 39,000 and 26,000, respectively. Gene-polypeptide correlations from other studies enabled us to complete gene-polypeptide-structure correspondences for these two proteins as flaM----39-kilodalton protein----P ring and flaY----26-kilodalton protein----L ring.

Bacterial Proteins↗
PubMed1987

The flaFIX gene product of Salmonella typhimurium is a flagellar basal body component with a signal peptide for export.

flaFIX, the structural gene for the periplasmic P ring of the flagellar basal body of Salmonella typhimurium, was cloned. Two gene products with apparent molecular weights of 38,000 and 40,000 were identified by minicell analysis. Data from pulse-chase and membrane fractionation experiments and data on the inhibitory effect of the proton ionophore carbonyl cyanide m-chlorophenylhydrazone all indicated that the 40-kilodalton protein was a precursor form which, after export across the cytoplasmic membrane accompanied by cleavage of a signal peptide, gave rise to the mature protein in the periplasm. The N-terminal amino acid sequence of the FlaFIX protein, predicted from the DNA sequence, conformed well to known signal peptide sequences. The results indicate that the P-ring protein of the basal body (unlike flagellin and possible some other external flagellar components) crosses the cytoplasmic membrane in a conventional signal peptide-dependent manner.

Amino Acid Sequence↗
PubMed1987

Identification of flagellar hook and basal body gene products (FlaFV, FlaFVI, FlaFVII and FlaFVIII) in Salmonella typhimurium.

The flagellar genes flaFV, flaFVII, and flaFVIII of Salmonella typhimurium were cloned, and their presence on a given plasmid was verified by complementation of Escherichia coli mutants defective in the homologous genes. The gene products were identified by radiolabeling in a minicell system as being proteins of the following molecular masses: FlaFV, 42 kilodaltons (kDa); FlaFVI, 32 kDa; FlaFVII, 30 kDA; and FlaFVIII, 27 kDa. These data, together with isoelectric focusing data, confirm gene product assignments of flagellar components made indirectly from mutant studies. Flagellar components are transported by either a signal peptide-dependent or a flagellar-specific pathway. Consistent with its location in the outer membrane ring of the basal body, protein FlaFVIII seems to use the signal peptide-dependent pathway, since it was synthesized in a precursor form and processed, presumably by peptide cleavage, to a mature form; the maturation process was inhibited by addition of a proton ionophore. Proteins synthesized in minicells were localized as follows: FlaFVI was localized to the soluble fraction (cytoplasm); pre-FlaFVIII and FlaFVIII were localized to the particulate fraction (membrane or high-molecular-weight aggregate); FlaFV and FlaFVII were localized to both fractions. The significance of these locations in terms of known or suspected roles in the flagellar apparatus is discussed.

Bacterial Proteins↗
PubMed1987

Autoantibodies to the Sm antigen: immunological approach to clinical aspects of systemic lupus erythematosus.

The precise antigenic peptide of Sm antigen (U small nuclear ribonucleoproteins, U snRNP) and the clinical significance of anti-Sm antibodies in systemic lupus erythematosus (SLE) detected by a sensitive radioimmunoassay were studied. By immunoblotting, anti-Sm sera reacted with B'/B peptides of U1 snRNP and D peptide of U1-U2 snRNP, while anti-U1 RNP recognized 68k, A, B'/B and C peptides. Reblotting study using the specific antibodies against each peptide eluted from the blot sheets demonstrated that B'/B and D peptides shared a common Sm antigenic epitope. We purified D peptide from U1 snRNP and established a radioimmunoassay. Anti-Sm antibodies were found in 30% of the patients with SLE using this method, which was more sensitive than the conventional assays. Anti-Sm was associated with late onset renal disease and poor prognosis when analyzed with Cox's regression model.

Autoantibodies↗
PubMed1987

A multicenter double blind controlled study of lipo-PGE1, PGE1 incorporated in lipid microspheres, in peripheral vascular disease secondary to connective tissue disorders.

Lipo-PGE1 is a drug preparation of PGE1 (prostaglandin E1) incorporated in lipid microspheres similar in properties to liposomes. A multicenter, placebo controlled, double blind test of lipo-PGE1 was carried out in patients with severe peripheral vascular disease secondary to diffuse connective tissue disorders. A total of 135 patients received a 90 min intravenous infusion of either 10 micrograms lipo-PGE1 or placebo every day for 4 weeks. A significant improvement was noted in the lipo-PGE1 group compared with the placebo group in the final overall improvement of peripheral vascular disease (p less than 0.001) and in the healing of ulcers (p less than 0.01), whereas, there was no difference in Raynaud's syndrome between the 2 groups. Side effects in the lipo-PGE1 group were few and were no different from controls. These results indicate that lipo-PGE1 at a low dose is beneficial in the treatment of peripheral vascular disease, and that lipid microspheres are useful as a drug delivery system for such purposes.

Adolescent↗
PubMed1987

Mixed connective tissue disease with pulmonary hypertension: a clinical and pathological study.

Clinical and autopsy findings of 2 cases with mixed connective tissue disease (MCTD) associated with severe pulmonary hypertension are reported. Both cases showed marked intimal and medial thickening in small and medium sized pulmonary arteries. In one of the cases plexiform lesions, endarteritis obliterans, and fibrous intimal thickening of the pulmonary veins were recognized. In some cases with MCTD, pulmonary hypertension develops due to pulmonary vascular lesions which are similar to those of primary pulmonary hypertension.

Adult↗
PubMed1986

Inhibition of topoisomerase I by antibodies in sera from scleroderma patients.

Purified type I topoisomerase from calf thymus as well as nuclear and cytoplasmic extracts from EGF-stimulated human and mouse fibroblasts in cell culture efficiently convert supercoiled plasmid DNA to the relaxed form. The purified IgG fraction from the sera of Japanese patients with the rheumatic disease scleroderma were shown to inhibit this relaxation activity. Thus, these patients likely produce autoantibodies to topoisomerase I. In addition, the human, bovine and murine enzymes share antigenic determinants recognized by the antisera.

Animals↗
PubMed1986

DNA-daunorubicin complexes specifically suppress in vitro spontaneous anti-DNA antibody production in lymphocytes of patients with systemic lupus erythematosus.

Elevated production of anti-DNA antibody in patients with systemic lupus erythematosus (SLE) is a central problem in the pathogenesis of tissue injury. In the present study, we attempted to manipulate anti-DNA antibody production through the antigen-cytotoxic drug conjugates, DNA-daunorubicin complexes. The effect of DNA-daunorubicin complexes was determined by examining SLE lymphocytes for spontaneous in vitro production of anti-DNA antibody. These complexes, at 2 micrograms/ml, suppressed anti-DNA antibody production, but not total IgG production, which suggests that specific suppression of anti-DNA antibody production was achieved at this concentration. We believe that the DNA-daunorubicin complexes affected mainly B cells, since such suppression was obtained by treating B cells, as well as B plus T cells. Furthermore, the complexes had no effect on the proliferative responses of SLE T cells to DNA, phytohemagglutinin, or concanavalin A. These results indicate that DNA-daunorubicin complexes may have the potential for selectively suppressing anti-DNA antibody production in patients with SLE.

Antibodies, Antinuclear↗
PubMed1986

In vitro production of autoantibodies to U1 ribonucleoproteins by peripheral blood mononuclear cells from patients with connective tissue diseases.

Antibodies to U1 ribonucleoproteins produced by peripheral blood mononuclear cells from patients with connective tissue diseases were measured by a sensitive enzyme-linked immunosorbent assay and by immunoblotting. Mononuclear cells from patients with high-titer serum antibodies spontaneously started secreting IgG anti-U1 RNP antibodies on the second day after culture. The amount of anti-U1 RNP in the culture supernatants reached maximum level on day 8. The most effective production of anti-U1 RNP by B cells was observed when they were cultured in the presence of T cells and adherent cells. Mononuclear cells from patients without anti-U1 RNP antibodies or from normal subjects did not produce a measurable amount of anti-U1 RNP. Treatment of mononuclear cells by cycloheximide resulted in complete inhibition of anti-U1 RNP secretion, which indicates that antibody in the culture supernatants reflects the active biologic phenomenon in vitro. The methods described should be useful in the study of the cellular mechanisms involved in antinuclear antibody production of connective tissue diseases.

Antigens↗