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Biomedical subjects

M Homma

Publications and source records attributed to M Homma.

At least 271 records · Page 15Linked to original sources
PubMed1985

Effects of glycosylation on the conformation and antigenicity of influenza C viral glycoproteins.

The antigenicity of influenza C viral glycoprotein gp88 was compared with that of its non-glycosylated counterpart T76 by immunoprecipitation utilizing monoclonal antibodies against gp88. Of the three monoclonal antibodies tested, an antibody designated Q-5 was found to precipitate gp88 but not T76, indicating the requirement for glycosylation for the binding of Q-5 to gp88. However, the antigenic determination recognized by Q-5 did not appear to be carbohydrates since trypsin-treatment of gp88 eliminated its reactivity with this antibody. These results suggest that glycosylation is important in determining the antigenicity of gp88 presumably by influencing the folding of the glycoproteins.

Antibodies, Monoclonal↗
PubMed1985

Enhancement of dengue virus infection in cultured mouse macrophages by lipophilic derivatives of muramyl peptides.

Dengue virus multiplication in cultures of a murine myelomonocytic cell line (WEHI-3) as well as mouse peritoneal macrophages was enhanced by treatment of the cells with lipophilic derivatives of muramyl peptides for 2 or 3 days before virus inoculation, but not for 2 hr before virus inoculation or during the adsorption period. The infection-enhancing activity of the materials was dependent on their chemical structure, correlating with their immunoadjuvanticity. The infection enhancement in WEHI-3 cells was due primarily to an increase in the number of virus-infected cells which was accompanied by an increased cellular capacity to bind latex particles to their cell surfaces.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1985

Detection of antibody to M protein of measles virus in patients with subacute sclerosing panencephalitis: a comparative study on immunoprecipitation.

Consistent results have not been obtained yet on the presence of antibody to the M protein of measles virus in the sera of patients with subacute sclerosing panencephalitis (SSPE). We performed a comparative study on various immunoprecipitation systems which appeared in the literature and found that the difference in the composition of the solubilizing buffer produced a large variety of results on the immunoprecipitation. [35S]Methionine-labeled Vero cells infected with the Edmonston strain of measles virus were solubilized by 10 different buffers and reacted with hyperimmune rabbit serum to whole virus, monospecific antisera to H, NP, and M proteins of the virus, normal adults' sera, and the sera from 16 SSPE patients. The immune complex was absorbed by protein A and both solubilization and precipitation rates were compared with each viral protein. Although viral proteins were solubilized by all buffers, the solubilization rate varied considerably. M protein was solubilized and was not coprecipitated nonspecifically with any of the other viral proteins. Purified protein A conjugated to Sepharose was preferable to Staphylococcus aureus for absorption of the immune complex since the latter absorbed both viral and host proteins nonspecifically. The precipitation rates of the viral proteins also varied according to the buffers. Better solubilization of the viral proteins seemed to reduce their rate of precipitation for which the presence of SDS may be responsible, and the presence of the protease inhibitors may also affect the results of immunoprecipitation. Detection of M protein in the immunoprecipitates was largely influenced by the kind of buffer used: some buffers could detect it clearly, but others could not defect it at all. Among the solubilizing buffers tested, Saleh's buffer (Virology 93: 369-376 (1979)),, which contains 0.5% DOC and 0.5% Triton X-100, was most reliable for detection of the anti-M antibody in the rabbit serum, because it showed a high solubilization and high precipitation rates of viral proteins without nonspecific absorption by protein A or coprecipitation of M proteins with any of the other proteins. Using this buffer, we could definitely detect M proteins in the immunoprecipitates from the sera of all six healthy adults and 15 out of 16 patients with SSPE. It was found, however, that the amount of M proteins in SSPE patients was lower than that in healthy adults and varied considerably.

Adult↗
PubMed1985

Enhancement of influenza virus hemolysis by physical and serological treatments.

The mode of hemolysis by influenza A virus was compared with that of Sendai virus. The WSN strain of influenza virus grown in either eggs or MDCK cells expressed hardly any hemolytic activity by itself. Treatment of the MDCK cell-grown WSN virus with sonication or freezing and thawing moderately enhanced the hemolytic activity, but the maximum level attainable was considerably lower than that of Sendai virus. A high level of hemolytic activity comparable to that of Sendai virus was obtained only after treatment of the virus with antibody and complement. An electron microscopic study revealed that non- or low-hemolytic WSN virions were not permeable to uranyl acetate stain in contrast with the hemolytic virions obtained after treatment with antibody and complement, indicating that the hemolytic virions had sustained some injury to their envelopes. These phenomena were comparable to those found with Sendai virus, showing that damage to the envelope is also responsible for the hemolysis of influenza virus. The influenza viruses, however, remained spherical after every treatment and the stain did not penetrate into the core of the virion. These observations suggest that the envelope of influenza virus is more rigid than that of Sendai virus but that the hemolytic process of influenza virus is nevertheless mediated through envelope-membrane fusion as in the case of Sendai virus.

Animals↗
PubMed1985

An assay for the receptor-destroying activity of influenza C virus.

We have developed a convenient method for assaying the receptor-destroying enzyme (RDE) activity of influenza C virus. This method measures the ability of the RDE to destroy the hemagglutination-inhibition activity of a potent inhibitor present in rat serum. Some physico-chemical properties of the RDE of influenza C virus were investigated by using this method. The temperature optimum for maximal activity of this enzyme was found to be 45 C to 53 C. There was little difference in thermostability between the RDE and hemagglutinating activities of influenza C virus. When influenza C virions were treated with various concentrations of trypsin, the RDE activity decreased in parallel with the decrease in the amount of residual gp88 glycoprotein, suggesting association of RDE with this glycoprotein.

Animals↗
PubMed1985

Locations of hook-associated proteins in flagellar structures of Salmonella typhimurium.

Hooks of the flagella of Salmonella typhimurium were purified from an flaL mutant. Hook-associated proteins, namely HAP1, HAP2, and HAP3, were separated from them, and the antibody against each HAP was prepared. By immunoelectron microscopic observation, these three kinds of antiHAP antibodies were found to bind on the distal ends of hooks of filamentless mutants consistently with their composition of HAPs. The antiHAP2 antibody bound to the very tops of the claw-shaped ends of the hooks which contain all three HAPS. The antibodies against HAP1 and HAP3 bound to the basal areas and the middle areas, respectively, of the claw-shaped ends. The order of disassembly of the component proteins by heat treatment of the hook structure from the filamentless mutants was (HAP2, HAP3) greater than HAP1 greater than hook protein. These observations were consistent with our layered structure model: HAP1, HAP3, and HAP2 are assembled at the distal end of the hook in this sequence. All three HAPs were detected in the hook-filament complexes prepared from a flagellate strain. When the hook-filament structure was treated with antibody against HAP1 and with the anti-rabbit immunoglobulin G antibody, the antibody aggregate was observed in the region corresponding to the boundary between filament and hook. This observation strongly suggests that HAP1 is the protein connecting filament with hook. The locations of HAP2 and HAP3 in the hook-filament structure were not clarified with the same procedure.

Antibodies, Bacterial↗
PubMed1985

Structural genes for flagellar hook-associated proteins in Salmonella typhimurium.

The flaW, flaU, and flaV genes of Salmonella typhimurium LT2 were cloned into pBR322. These genes were mapped on the cloned DNA fragments by restriction endonuclease analysis and construction of the deletion derivatives. Their gene products were identified, by the minicell method, as proteins whose molecular weights were estimated to be 59,000 for the flaW product, 31,000 for the flaU product, and 48,000 for the flaV product. These values are identical to those of three species of hook-associated proteins (HAPs), namely, HAP1, HAP3, and HAP2. Furthermore, antibodies against HAP1, HAP3, and HAP2 specifically reacted with the gene products of flaW, flaU, and flaV, respectively. Therefore, we concluded that they are structural genes for HAPs. The antibodies against HAP1 and HAP3 also specifically reacted with the gene products of flaS and flaT of Escherichia coli, respectively. This indicates that these gene products are HAPs in E. coli. This result is consistent with the demonstration that flaS and flaT of E. coli are functionally homologous with flaW and flaU of S. typhimurium.

Bacterial Proteins↗
PubMed1985

Excretion of unassembled hook-associated proteins by Salmonella typhimurium.

Hook-associated proteins (HAPs) were excreted into the culture medium of the Fla+ strain as well as into the growth medium of the filamentless mutants of Salmonella typhimurium. This indicates that the bacteria synthesize HAPs excessively, beyond the amount required for construction of flagella. The extra HAPs are shed into the culture medium after a definite amount of each HAP has been assembled into the flagellar structure.

Bacterial Proteins↗
PubMed1985

Protection of mice from wild-type Sendai virus infection by a trypsin-resistant mutant, TR-2.

A trypsin-resistant mutant of Sendai virus, TR-2, which could be activated by chymotrypsin but not by trypsin or the protease present in mouse lung, was inoculated intranasally into mice after being activated in vitro. TR-2 hardly brought about clinical illness or lung lesions in mice; the protease present in the lung could not activate the progeny virus, and the infection terminated after one-step replication. Nevertheless, the immunoglobulin A antibody against wild-type Sendai virus was produced in the respiratory tracts as well as the serum immunoglobulin G antibody, and the mice were protected from the challenge of the wild-type Sendai virus. On the basis of these results, TR-2 may provide a new model of live vaccine for paramyxoviruses; its availability as a live vaccine is also discussed.

Animals↗
PubMed1985

Differences in metabolic properties among cortisol, prednisolone, and dexamethasone in liver and renal diseases: accelerated metabolism of dexamethasone in renal failure.

Since previous reports concerning the altered metabolism of various glucocorticoids in liver or renal diseases were inconsistent, this study was undertaken to reexamine the metabolism of cortisol, prednisolone, and dexamethasone in patients with these diseases. One milligram each of these glucocorticoids was given iv simultaneously to patients with chronic liver disease, patients with chronic renal failure, and normal subjects after 1 mg betamethasone was administered on the previous night to suppress endogenous cortisol secretion. Plasma steroid levels in periodically collected blood samples were assayed by respective RIA after separation by paper chromatography. Prolongation of the t1/2 of cortisol was found in both patients with liver disease and those with renal failure, and prolonged t1/2 and reduced MCR of prednisolone were found in renal failure but not in liver disease. In contrast, while prolonged t1/2 and reduced MCR of dexamethasone were found in liver disease, shortened t1/2 and increased MCR were found in renal failure. These results suggest that different glucocorticoids are metabolized differently in patients with liver disease and those with renal failure, and that these differences may be important when these agents are used for therapeutic purposes or for study of hypothalamic-pituitary-adrenocortical function in patients with liver and renal diseases.

Adult↗
PubMed1985

Blocking type antithyrotropin receptor antibody in patients with nongoitrous hypothyroidism: its incidence and characteristics of action.

The incidence, characteristics of action, and pathogenetic importance of blocking type anti-TSH receptor antibody were examined in patients with autoimmune thyroiditis. Serum immunoglobulin G (IgG) from 8 of 20 patients with nongoitrous hypothyroidism contained substantial amounts of TSH binding inhibitor immunoglobulin (TBII) activity. Newborn infants of a patient with the greatest TBII activity had neonatal transient hypothyroidism. In sera of patients with goitrous hypothyroidism and euthryoid chronic thyroiditis, only weakly positive or negative TBII activity was found. IgGs of these patients and those of nongoitrous hypothyroid patients without strongly positive TBII activity did not inhibit TSH stimulation of thyroid adenylate cyclase activity. Seven of 8 IgGs which had strongly positive TBII activity significantly inhibited cAMP generation induced by 9.1 mU/ml TSH, and the eighth IgG inhibited stimulation with 0.5 mU/ml TSH. Although the modes of TSH binding inhibition were variable, markedly close correlation was found between TSH binding- and TSH stimulation-inhibiting activities of these 8 IgGs (r = 0.90; P less than 0.01). These IgGs may exert their inhibitory effects on adenylate cyclase activity by inhibiting TSH binding to its receptor.

Adenylyl Cyclases↗
PubMed1984

Suppressor T cell function in patients with rheumatoid arthritis complicated by vasculitis.

Concanavalin A (Con A)-induced suppressor T cell activity was determined in 10 rheumatoid arthritis (RA) patients with vasculitis, 34 RA patients without vasculitis, and 10 healthy individuals. The percent Con A-induced suppression in RA patients with vasculitis was 24.6. In contrast, it was 68.4% in those RA patients without vascular lesions. Further, the proportion of T cells reactive with OKT8 monoclonal antibody was also decreased in RA patients with vasculitis. Accordingly, the reduced Con A-induced suppressor T cell activity in these RA patients resulted, in part, from the reduction in the number of cells of the suppressor T cell subset. Those patients with vascular lesions also had a higher percentage of positive antilymphocytotoxic antibodies than RA patients without vasculitis. Since the differences in Con A-induced suppressor T cell activity and frequency of positive antilymphocytotoxic antibodies were so great, we believe RA patients with vasculitis could be recognized as a disease group distinct from RA patients without vasculitis.

Adult↗
PubMed1984

Cellular mechanism of DNA-specific antibody synthesis by lymphocytes from systemic lupus erythematosus patients.

The cellular mechanism of anti-DNA antibody synthesis in patients with systemic lupus erythematosus (SLE) was studied by DNA-specific solid-phase radioimmunoassay. Anti-DNA antibody synthesis in response to DNA was T-dependent, and the experiments with reconstituted lymphocytes from identical twins discordant for SLE showed that B cells and T cells from SLE patients must cooperate to synthesize anti-DNA antibody. Anti-DNA antibody synthesis by lymphocytes from patients with inactive SLE was enhanced by T4 cells and suppressed by T8 cells in response to DNA. Although T4 cells from patients with active SLE could enhance anti-DNA antibody synthesis by autologous B cells, their T8 cells could not suppress anti-DNA antibody synthesis by autologous B cells. These results indicate that elevated anti-DNA antibody synthesis in response to DNA in patients with active SLE is due to abnormalities of both SLE B cells and SLE T cells. They further indicate that dysfunction of T8 cells from patients with active SLE may, in part, be responsible for deficient regulation of anti-DNA antibody synthesis.

Antibodies↗
PubMed1984

Magnetic microcapsules for targeted delivery of anticancer drugs.

To achieve targeted distribution of anticancer drugs with sustained activity, ferromagnetic ethylcellulose microcapsules containing an anticancer drug, mitomycin C (FM-MMC-mc), were prepared by a method based on phase separation principles. Two prototypes of FM-MMC-mc were made: one with the drug as the core and zinc ferrite on its capsular surface (outer type); the other with both the drug and zinc ferrite as the core (inner type). Both preparations provided a sustained-release property and a sensitive response to conventional magnetic force, although certain differences in the release rate of drug, magnetic responsiveness, and particle size were found between the two dosage forms. Animal studies showed that the magnetic microcapsules could be magnetically controlled in the artery and urinary bladder. VX2 tumors in the rabbit hind limb and urinary bladder were successfully treated with magnetic control of FM-MMC-mc. Pharmacokinetic study revealed that the targeting of the microcapsules markedly enhanced the drug absorption into the surrounding tissues for a prolonged period of time. The results indicate the feasibility and effectiveness of the magnetic microcapsules as a targeted drug delivery system.

Animals↗
PubMed1984

Inhibition by hydroxy-N-methyl elliptinium of precancerous mammary hyperplastic alveolar nodule formation in mice.

Daily subcutaneous injections of 5 micrograms hydroxy-N-methyl elliptinium for 4 weeks in a high mammary tumor strain of SHN virgin mice was found to decrease the number of precancerous mammary hyperplastic alveolar nodules (HAN) associated with the increase in the number of ghosts, the remnants of regressed HAN. On the other hand, the treatment had little influence on the normal mammary lobulo-alveolar system, serum prolactin level, estrous cycle and endocrine organ weights. The results have demonstrated that elliptinium can inhibit the formation of HAN and induce their regression with no modulation of endogenous conditions of mammotropic hormones.

Alkaloids↗
PubMed1984

Genetic analysis of three additional fla genes in Salmonella typhimurium.

In Salmonella typhimurium, 27 fla genes responsible for formation of flagella have been identified and assigned to three regions on the genetic map, termed fla regions I to III. By genetic analysis of 1984 non-flagellate mutants obtained from a phase-1 stable strain of S. typhimurium, SJW1103, three additional fla genes were identified; one, termed flaW, was assigned to fla region I and the other two, termed flaV and flaX, to fla region III. By intergeneric complementation tests, the flaW, flaV and flaX genes were shown to be functionally homologous with flaS, flbC and flaP of Escherichia coli, respectively. Electron microscopy showed that flaW and flaV mutants carried hook-basal body structures.

Chromosome Mapping↗