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Biomedical subjects

T Masuda

Publications and source records attributed to T Masuda.

At least 613 records · Page 34Linked to original sources
PubMed1986

Murine IgA binding factors (IgA-BF) suppressing IgA production: characterization and target specificity of IgA-BF.

Chemical and functional properties of IgA binding factor(s) (IgA-BF) from both murine Con A-activated spleen cells and Fc gamma R+, Fc alpha R+ T hybridoma cells (T2D4) were studied. IgA-BF produced from the cells after preculture with IgA were purified with IgA-Sepharose. Purified IgA-BF inhibited the binding of IgA to Fc alpha R+ L5178Y T lymphoma cells, and class-specifically suppressed in vitro IgA synthesis of the pokeweed mitogen (PWM)-stimulated murine spleen cells. Both IgA-specific suppressive activity and IgA binding activity of the factor(s) were co-fractionated between BSA and OVA in gel filtration analysis. SDS-PAGE analysis of IgA-BF biosynthetically labeled with [35S]methionine showed a specific band on 56,000. Suppressive activity of IgA-BF was absorbed with lentil-lectin-Sepharose and was eluted with 0.2 M alpha-methyl-D-mannoside. The suppressive activity obtained from T2D4 cells (H-2k) and BALB/c Con A blasts (H-2d) was absorbed with the corresponding anti-H-2 and anti-I-A column and recovered in the acid-eluate. The activity was not absorbed with the unrelated anti-H-2 column. Despite the presence of MHC products, IgA-BF from both cell sources equally suppressed IgA-specific responses of BALB/c (H-2d), C3H/He (H-2k), and C57BL/10 (H-2b) spleen cells. They also suppressed IgA production as well as IgA synthesis of PWM-stimulated culture of human peripheral blood lymphocytes without affecting IgM and IgG responses. Suppression of murine and human IgA responses both in mouse and human were mediated by the molecules having the same Ia products, suggesting that there is no MHC, as well as species restriction, for the interaction between IgA-BF and their target cells. IgA-specific suppressive activity was absorbed with human B blastoid cells bearing surface IgA (Dakiki) but not with those bearing surface IgG (CESS) or murine and human T cell line cells (BW5147, L5178Y, HPB-ALL, and MOLT4), indicating that IgA-BF interact with B cells bearing IgA to suppress their differentiation.

Animals↗
PubMed1986

Histopathological changes, mucin production and cellular DNA content in rectal mucosa of patients with ulcerative colitis: a comparison between findings in adults and adolescents.

Histopathological examination, specific mucin staining and analysis of cellular DNA content of rectal mucosa were carried out in twenty-eight tissue specimens biopsied from ten adult and eight adolescent patients with ulcerative colitis. There was an increase in proliferative activity in the rectal mucosa in both groups with active colitis, but, there were no significant differences in the potential for malignant transformation of rectal mucosa in these groups.

Adolescent↗
PubMed1986

Secretory carcinoma of the breast in a Japanese woman.

We report a case of secretory carcinoma of the breast in a 33 year old woman. Secretory carcinoma is a rare tumor and has distinctive pathological characteristics. This tumor usually occurs in children or adolescents. Modified radical mastectomy was carried out and the patient is doing well with no evidence of recurrence at 25 months later. Negative findings were obtained in the assay of estrogen and progesterone receptor.

Adult↗
PubMed1986

The propagation of single motor unit action potentials detected by a surface electrode array.

Propagation of single motor unit action potentials (MUAPs) was detected by surface electromyography. Sixteen EMG signals were simultaneously recorded by a linear bipolar electrode array placed along the longitudinal axis of the biceps brachii. EMGs were obtained from 8 healthy adults at 10-40% of the maximum contraction. Single MUAPs were extracted by superimposing and averaging the EMG signals at the timing of potential peaks. Most MUAPs were triphasic and propagated symmetrically in opposite directions from the middle length of the muscle to the tendons. Some MUAPs showed more than 5 phases and asymmetrical wave forms on the proximal and distal recording sites. The asymmetrical wave forms were assumed to be caused by the scatter of myoneural junctions and by the time delay of the excitation at the junctions. The position of the myoneural junctions on muscle fibers was estimated from the source of propagation. The innervation zone of individual motor unit was found to spread up to 14 mm in the muscle fiber directions.

Action Potentials↗
PubMed1986

Nicardipine increases cerebral blood flow but does not improve neurologic recovery in a canine model of complete cerebral ischemia.

The effects of the calcium entry blocker nicardipine on CBF, CMRO2, and neurologic outcome following 10 min of complete cerebral ischemia were examined in dogs. In CBF and CMRO2 studies, the CBF in the untreated group (seven dogs) and the nicardipine group (seven dogs; 20 micrograms kg-1 at 30 min postischemia and a subsequent infusion of 2 micrograms kg-1 min-1 for 90 min) initially increased to 300-400% and then returned to preischemic values at 30 min postischemia. Thereafter the CBF in the untreated group significantly decreased to 50% of preischemic values for the following 90-min period (hypoperfusion), while the CBF in the nicardipine group did not differ from preischemic values. The CMRO2 in both groups decreased to approximately 50-80% of preischemic values after 15 min postischemia and did not differ between the groups throughout the study. In neurologic outcome studies, 18 dogs were divided into three groups (of six dogs each): untreated; saline infusion only, posttreated; nicardipine as in CBF and CMRO2 studies, pretreated; nicardipine 20 micrograms kg-1 at 2 min preischemia and a subsequent infusion of 2 micrograms kg-1 min-1 from immediately postischemia to 120 min postischemia. Nicardipine treatment initiated either before or after ischemia failed to improve neurologic outcome at 48 h postischemia. Thus, the increase of postischemic global CBF by nicardipine is not accompanied by neurologic recovery in a canine model of complete cerebral ischemia.

Animals↗
PubMed1986

Mechanism of radiosensitizing effect of chloride ion on E. coli.

Cells of E. coli capable of repairing DNA damage are sensitized to radiation in the presence of NaCl. However, the enhanced radiolethality was suppressed by the addition of compounds such as an amino acid to the irradiation buffer. The protective efficiencies of these compounds depend on their reactivities with Cl-.2 or OH.. ATP synthesis in the cells irradiated in the presence of NaCl was severely inhibited depending on the dose of irradiation. This reduced rate of ATP synthesis can account for the inhibition of protein, RNA and DNA synthesis in the irradiated cells with NaCl.

Adenosine Triphosphate↗
PubMed1986

Animal model of silent myocarditis in athymic mice.

To clarify the role of the immune system in the development of myocarditis, BALB/c-nu/nu mice (group 1), BALB/c-nu/+ mice (group 2), BALB/c-nu/nu mice injected with 5 X 10(7) spleen cells from BALB/c-nu/+ mice (group 3), and BALB/c-nu/nu mice injected with 5 X 10(7) spleen cells from BALB/c-nu/+ mice treated with rat anti-Thy-1.2 monoclonal antibody with complement (group 4) were inoculated with encephalomyocarditis virus. There were no significant differences in the incidence of myocarditis among the four groups. Virus titrations of the heart and serum neutralising antibody titres in the four groups did not show any significant differences. Fifty two per cent (26/50) of group 2 and 43% (20/46) of group 3 died on days 9-15, when congestive heart failure developed. Only 9% (5/54) of group 1 and 8% (1/12) of group 4, however, died on days 9-15. Pathological examination confirmed congestive heart failure in groups 2 and 3 but not in groups 1 and 4. Dilatation of the ventricular cavities, pleural effusion, ascites, and congestion of the lungs and liver were present in groups 2 and 3 but not in groups 1 and 4. Cellular infiltration and myocardial necrosis were severe in groups 2 and 3 but minimal in groups 1 and 4. Thus the severity of myocarditis may be regulated by T cells. So-called silent myocarditis seen in clinical settings may be similar to myocarditis in BALB/c-nu/nu mice.

Animals↗
PubMed1986

Synthesis and characterization of human prorenin in Escherichia coli.

DNA sequences encoding Ile-Glu-Gly-Arg and human prorenin were joined and placed under the transcriptional control of the Escherichia coli trp promoter-operator in the expression vector pTR501. E. coli cells transformed with pTR501 expressed high levels (30% of total cell protein) of prorenin as part of a hybrid protein with the trp E gene product. The chimeric protein, accumulated in a sedimentable form, was dissolved in 6 M guanidine X HCl, purified to near homogeneity, and renatured by dialysis. The complete prorenin sequence was then excised from the renatured hybrid protein using blood coagulation factor Xa, a proteinase which is highly specific for the tetrapeptide insert Ile-Glu-Gly-Arg introduced between the 9 amino-terminal residues of the trp E gene product and the first amino acid (Thr 1) of prorenin. Human prorenin thus obtained was readily activatable with trypsin and showed close similarities to naturally occurring prorenin in its biochemical and immunochemical properties.

Base Sequence↗
PubMed1986

Effect of inspired nitrous oxide concentration on the rate of fall of alveolar concentration: reversed concentration effect.

The effect of inspired nitrous oxide concentration on the rate of fall of alveolar nitrous oxide concentration was studied in six patients ranging in age from 25 to 46 years. After equilibrium was reached with nitrous oxide, nitrous oxide administration was stopped and replaced by the same concentration of nitrogen. The decrease in alveolar concentration of nitrous oxide (FE/FE0) was measured continuously, where FE = measured end-tidal concentration of nitrous oxide, and FE0 = the end-tidal concentration immediately preceding the cessation of nitrous oxide administration. The rate of decrease in FE/FE0 was more rapid when 70% nitrous oxide was inspired (Part I) than when 30% nitrous oxide was inspired (Part II). One minute after the cessation of nitrous oxide administration, FE/FE0 was 0.30 +/- 0.03 (mean +/- s.d.) in Part I and 0.36 +/- 0.02 in Part II (P less than 0.05). Mean expired tidal volume increased from 515 +/- 43 ml to 552 +/- 48 ml in Part I and from 510 +/- 48 ml to 526 +/- 39 ml in Part II (P less than 0.05). The authers conclude that the more rapid decrease in alveolar concentration of nitrous oxide (FE/FE0) at higher concentrations of nitrous oxide results from augmentation of expired ventilation. We have called this phenomenon the "reversed concentration effect".

Adult↗
PubMed1986

Feedback regulation of antibody formation by suppressive B cell factor: preferential suppression of high-affinity antibody production by memory B lymphocytes.

Cloned TS4.44 cells, which were hybridized HAT-sensitive 3T3-4E cells with B cells stimulated by immune complexes produce a lymphokine, biochemical and biological characteristics of which are identical with those of conventional suppressive B cell factor (SBF) synthesized by Fc receptor bearing B cells stimulated with immune complexes. This factor is known to suppress B cell responses to antigen/mitogen. The present studies were carried out by using this hybridoma-derived SBF to characterize the large proportion of B cells sensitive to SBF and the small proportion of B cells resistant to it in terms of affinities of antibodies which these cells are able to produce. The treatment of normal spleen cells with SBF resulted in a 50-70% decrease in anti-dinitrophenyl (DNP) antibody production when the cells were transferred into X-ray-irradiated mice along with alum-precipitated dinitrophenyl-conjugated keyhole limpet hemocyanin (DNP-KLH). The affinity of anti-DNP antibody molecules produced in these mice was significantly lower than that of the controls, even if immunization was repeated. The target cells for SBF were B, and not helper T cells which might be involved in the process of affinity maturation. A single treatment of spleen cells in vitro with SBF was sufficient to abrogate the precursors committed to mediate high-affinity anti-DNP antibody responses, since the retreatment with SBF in vitro and transfer into the second irradiated recipients along with antigens of spleen cells of mice to which SBF-treated spleen cells were transferred 3 weeks before resulted in almost the same level of plaque-forming-cell-responses as in mice which received medium-treated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

The size and number of Langerhans islets correlated with their endocrine function: a morphometry on immunostained serial sections of adult human pancreases.

Surgical and autopsy specimens of normal pancreas from three human adults were submitted to morphometry of Langerhans islets and so-called extra insular islet cells, by measuring the islet radii on serial sections immunostained for either insulin or glucagon. All the islets contained in a test volume were measured including single cells, and the distribution of their radial sizes was studied. It was found that the distribution of islets was strongly skewed and continuous, with the majority of islets having radial values near to the minimum. From the fact that only one peak was found in the distribution curve, it is concluded that in spite of the distinction previously made between islets of Langerhans and so-called extra-islet cells, they are in fact both part of a continuous distribution. Moreover, the Weibull function, assumed as the theoretical distribution, fit well with the empirical histograms, giving support for the contention of continuous distribution with a single peak. Although the small islets account for a majority of the number of islets, they account for only a very small percentage of the islet volume. This is thought to indicate that the bulk of the endocrine functions of the pancreas are carried out by large islets, whereas the so-called extra-islet cells are likely to be their precursors. With regard to the cellular structure of the islets, it was found that the smaller the islet, the smaller the percentage of islets containing A cells, with the vast majority of cells in the smallest islets (often single cells) being B cells.

Adult↗
PubMed1986

Significant regression of the tumor combined with the high level of plasma cortisol by low-dose administration of O, p'-DDD in a case with Cushing's syndrome caused by adrenocortical carcinoma.

The effect of o, p'-DDD on a functioning adrenocortical carcinoma is described. A 52-year-old woman, who had a huge adrenocortical carcinoma and pulmonary metastasis, was treated by a low-dose administration of o, p'-DDD, which reduced the tumor size. The excretion of urinary 17-OHCS was decreased, whereas plasma cortisol was not decreased but rather increased. This was considered to be caused that o, p'-DDD functioned as a cytotoxic factor which did not improve the states of hyperkalemia, hyperglycemia and hypertension. This suggested that monitoring to measure multiple steroids in addition to plasma cortisol and urinary 17-OHCS was useful for recognizing the general conditions of patients with adrenocortical carcinoma receiving o, p'-DDD therapy.

Adrenal Cortex Neoplasms↗