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Biomedical subjects

M Imai

Publications and source records attributed to M Imai.

At least 559 records · Page 31Linked to original sources
PubMed1980

Hepatitis B e antigen polypeptides isolated from sera of individuals infected with hepatitis B virus: comparison with HBeAg polypeptide derived from Dane particles.

Hepatitis B e antigen (HBeAg) occurs in the serum of individuals infected with hepatitis B virus both free and in association with IgG. Utilizing a succession of steps involving salt precipitation, affinity chromatography, ion-exchange chromatography and isoelectrofocusing, we isolated free and IgG-bound forms of HBeAg from the sera of infected individuals with an overall gain in specific activity of 3000-fold and 540-fold, respectively. Polypeptide profiles of purified HBeAg preparations were studied by SDS-polyacrylamide gel electrophoresis in the presence of 2-mercaptoethanol. Both free and IgG-bound preparations revealed polypeptides with mol. wt. of 15500 (P15.5) and 16 500 (P16.5), and HBeAg activity was detected corresponding to their positions. The HBeAg polypeptides (P15.5/16.5) derived from sera were physicochemically different from the two polypeptides with HBeAg activity (P19 and P45) liberated from Dane particle cores by the conventional method involving incubation with Nonidet P40 and 2-mercaptoethanol. However, when core particles were prepared in the presence of a proteolytic enzyme, in addition to Nonidet P40 and 2-mercaptoethanol, they gave rise to HBeAg polypeptides with mol. wt. of 31000 (P31) and 15 500. Furthermore, P31 split into P15.5 when heated at 100 degrees C for 2 min. On the basis of these results, P15.5 may be assumed to be the essential polypeptide bearing HBeAg activity in the serum and also in Dane particles.

Hepatitis B↗
PubMed1980

Mycoplasma pulmonis arthritis in congenitally athymic (nude) mice. Histopathological features.

Histopathological examinations were performed on arthritis joints and other organs of strain BALB/cA nu/nu and nu/+ mice intravenously injected with Mycoplasma pulmonis strain m53. In both groups of mice suffering from polyarthritis, acute inflammatory lesions with infiltration of polymorphonuclear leukocytes in the synovia and periarticular tissues were observed one to two weeks after injection. In nu/nu mice, the acute inflammation appeared repeatedly up to 20 weeks after inoculation, when the experiment was terminated, and furthermore, extensive synovial and periarticular necrosis were characteristically present after the 4th week. Only a small number of lymphocytes and plasma cells were in the lesions. In nu/+ mice, after the early acute inflammation of arthritis, relapses of the infiltration of polymorphonuclear leukocytes were also observed in some mice in and after the 10th week. In addition, infiltration of lymphocytes and plasma cells were substantial after the 15th week. Focal necrosis was sometimes found in the liver of nu/nu mice. Perivascular infiltration of small lymphocytes and plasma cells was found in the lungs, liver and kidney of nu/+ mice in and after the 15th week. Repair mechanisms of injured articular tissues in nu/nu mice were histopathologically poor, while those in nu/+ mice seemed to be progressive and quite similar to those reported by many investigators for mice with the thymus intact. The histopathological differences are discussed in respect to the thymus-dependent immune responses.

Animals↗
PubMed1980

A 49,000-dalton polypeptide bearing all antigenic determinants and full immunogenicity of 22-nm hepatitis B surface antigen particles.

Spherical 22-nm hepatitis B surface antigen (HBsAg) particles with a subtype adr were purified from plasma of asymptomatic carriers of hepatitis B virus. When purified HBsAg preparation was treated with sodium dodecylsulfate in the absence of reducing agents, it yielded spherical particles with a diameter smaller than 22 nm, and in addition, a polypeptide with a molecular size of 49,000 daltons, which seemed to constitute the outer coat of HBsAg particles. The recovery of the polypeptide on the basis of optical density at 280 nm was 2%, starting from 22-nm HBsAg particles. The 49,000-dalton polypeptide apparently represented a structural unit of the surface of HBsAg particles, since it bore all common (a, Re) and subtypic (d, r) determinants with essentially the same antigenic titers as intact HBsAg particles. Furthermore, this polypeptide was equally immunogenic as 22-nm HBsAg particles in raising corresponding antibodies in mice. When the 49,000-dalton polypeptide was reduced in the presence of 2-mercaptoethanol, it cleaved into 22,000- and 27,000-dalton polypeptides with a drastic decrease in both antigenicity and immunogenicity. These results indicate the different molecular arrangements between outer coat and inner portion of HBsAg particles, and a potential application of the 49,000-dalton polypeptide as a component vaccine, owing to its strong antigenicity both in vitro and in vivo.

Animals↗
PubMed1979

The connecting tubule: a functional subdivision of the rabbit distal nephron segments.

Studies on adenylate cyclase response of the nephron fragments to hormones and drugs have suggested that there is a functionally distinct segment tentatively called the connecting tubule (CNT), which is located between the distal (DT) and the cortical collecting tubule (CCT). The functional significance of these biochemical findings was examined with isolated rabbit renal tubules perfused in vitro. The transepithelial voltage (PDt) of the DT, CNT, and CCT were, respectively, -28.7 +/- 3.24 mV (24), -27.0 +/- 2.69 mV (24), and -3.5 +/- 2.14 mV (11) in the normal rabbits. The PDt of the CCT increased to -32.2 +/- 2.02 mV (33) when rabbits were pretreated for at least 3 days with deoxycorticosterone acetate, DOCA (1 mg/kg/day, i.m.), whereas the PDt of the DT and the CNT remained unchanged. The PDt of the CCT obtained from deoxycorticosterone acetate- (DOCA) treated animals decreased after addition of antidiuretic hormone (ADH) or isoproterenol (ISO) to the bath. The PDt of the CNT also responded to these agents, but the dose required to obtain the same response was quite different: The CNT was 100-fold more sensitive to ISO as compared to the CCT, whereas the CCT was 10-fold more sensitive to ADH than was the CNT. In contrast, the PDt of the DT did not respond to any of these agents, even at a higher concentration. After addition of ADH (200 microU/ml) to the bath, the osmotic water permeability (10(-8) cm2 . sec-1 . atm-1) of the CCT increased from 1.13 +/- 0.83 to 7.46 +/- 2.36, but that of the CNT remained low (0.36 +/- 0.78 in control vs. 0.48 + 0.64 after ADH). These observations support the view that the CNT is functionally distinct from either the DT or the CCT.

Animals↗
PubMed1979

A simple method to determine adenylate cyclase activity in isolated single nephron segments by radioimmunoassay for succinyl adenosine 3',5'-cyclic monophosphate.

A simple method to determine adenylate cyclase activity in isolated single nephron segments is described. Segments of the proximal convoluted tubule or the cortical collecting tubule were isolated from rabbit kidney slices pretreated with collagenase. After the tubule membranes were made permeable by adding hypotonic medium and freezing-thawing, each sample was incubated at 30 degrees C for 30 min in a medium containing ATP and theophylline. Generated cAMP was succinylated and served for radioimmunoassay. Addition of the incubation medium did not interfere the radioimmunoassay. Recovery of added cAMP was 96%. In the proximal convoluted tubule, either 8 mM NaF or 1 U/ml parathyroid hormone (PTH) markedly stimulated adenylate cyclase activity, but 1 mU/ml arginine vasopressin (AVP) did not. By contrast, in the cortical collecting tubule, either 8 mM NaF or 1 mU/ML AVP markedly stimulated adenylate cyclase activity, but 1 U/ml PTH did not. These data imply that this method is sensitive enough to detect either specific or nonspecific response of adenylate cyclase activity in single nephron segments.

Adenylyl Cyclases↗
PubMed1979

A receptor for polymerized human and chimpanzee albumins on hepatitis B virus particles co-occurring with HBeAg.

A receptor for polymerized human serum albumin was demonstrated on Dane particles as well as on 20-nm hepatitis B surface antigen particles, isolated from asymptomatic carriers of hepatitis B virus who were positive for HBeAg. In contrast, such receptor was not born by 20-nm hepatitis B surface antigen particles obtained from carriers positive for antibody to HBeAg. Hepatitis B surface antigen particles with the receptor were heavier than those without, and when treated with pronase, they became lighter and lost the receptor. The receptor is responsible for the agglutination of erythrocytes coated with polymerized human serum albumin by the serum of patients with Type B hepatitis and asymptomatic carriers, which have been attributed to autoantibodies directed to denatured albumin molecules. When albumin fractions of chimpanzees were polymerized with glutaraldehyde, they also bound with the receptor on hepatitis B surface antigen. Polymerized albumin fractions of all the other experimental animals without susceptibility to hepatitis B virus, however, failed to bind with the receptor. These results seem to suggest a possible role of the receptor on Dane particles (presently accepted hepatitis B virions) for polymerized albumin molecules in infecting hepatocytes both in humans and chimpanzees.

Animals↗
PubMed1979

Immunological cross reaction between sera from patients with breast cancer and mouse mammary tumor virus.

Sera of Japanese women with breast cancer and without disorders of the mammary gland gave positive immunofluorescence reaction with mouse mammary tumor cells (MMT cells) producing type-A and type-B virus particles. Among these, 55.1% (49/89) of the sera from patients with breast cancer reacted with MMT cells, whereas 60% (3/5) of the sera from patients with benign mammary hyperplasia (2 of 3 mastopathies, 1 of 2 cystosarcoma phyllodes), 30% (12/40) of the patients with other than breast cancer (4 of 14 stomach cancers, 6 of 20 uterine cancers, 1 of 3 lung cancers, 1 of 3 rectum cancers), and 26.5% (18/68) of the sera from apparently healthy women showed positive reaction with MMT cells. Distribution pattern of the specific fluorescence obtained with positive human sera was similar to that resulting from the reaction with rabbit antiserum of type-A particles. Results of absorption studies and blocking tests also suggested that the reaction was due to the antigenic components common to type-A and -B particles. Furthermore, the results of membrane immunofluorescence tests suggested that some human sera also react with envelope antigen(s) of B particles. Antinuclear antibody was found in sera from 15.7% (14/89) of breast cancer patients by the indirect immunofluorescence tests, and antibody cross-reacting with mouse mammary tumor virus was not found in most of the sera from breast cancer patients who have antinuclear antibody.

Adenocarcinoma↗