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Y Ichikawa

Publications and source records attributed to Y Ichikawa.

At least 793 records · Page 44Linked to original sources
PubMed1981

Absorption of protein molecules by the small intestine of the bullfrog tadpole, Rana catesbeiana.

In the tadpole of the bullfrog, Rana catesbeiana, the absorptive cells of the small intestine are characterized by the presence of invaginations of the surface plasma membrane or pinocytic vesicles in the apical cytoplasm and numerous lysosomes in the supranuclear region. These cytological features suggest that the absorptive cells may be able to ingest some macromolecules or particles. The possibility of macromolecular absorption in this animal was examined by using horseradish peroxidase (HRP) and the electron microscopic cytochemical technique. Exogenous HRP was ingested in the absorptive cells by pinocytosis and then accumulated in multivesicular bodies (MVBs) by the contribution of pinocytic vesicles to MVBs. The pinocytic vesicle changed its shape to have an inner vesicle. Some of the inner vesicles of MVBs seem to have originated from the inner vesicles of pinocytic vesicles. Almost all the MVBs in the subapical region showed HRP activity, but some of them showed no acid phosphatase (AcPase) activity; those in the supranuclear region always showed an intense AcPase activity. Therefore some of the subapical MVBs are heterophagosomes and may be joined with lysosome during the movement toward the supranuclear region. The MVBs with lysosomal enzymes in the subapical or supranuclear region are presumably important sites of intracellular digestion. The results indicate that intracellular digestion may occur in the small intestine of the bullfrog tadpole under natural conditions.

Animals↗
PubMed1981

Circular dichroic studies on the interaction between reduced nicotinamide adenine dinucleotide phosphate-adrenodoxin reductase and adrenodoxin.

Circular dichroic spectra of NADPH-adrenodoxin reductase, adrenodoxin and the complex between oxidized adrenodoxin reductase and oxidized adrenodoxin were studied. A 1 : 1 complex formation between adrenodoxin reductase and adrenodoxin resulted in the appearance of a distinct difference CD spectrum, which was obtained by subtraction of the sum of their CD spectra from the CD spectrum of the mixture of the two proteins. The difference CD spectrum showed a broad trough between 500 and 600 nm and CD extrema at 452, 383, and 350 nm. This spectrum may reflect a change in the environment of either or both of the protein chromophores. By applying the curve-fitting method to analyze the ellipticity change at 452 nm of the difference CD spectrum obtained on titration of a fixed amount of adrenodoxin reductase with various amounts of adrenodoxin, we directly obtained a value of 4.56 x 10(-7) M (S.D. 9.58 x 10(-8) M) as the dissociation constant of the oxidized complex. We also studied the change of the difference ellipticity induced by the addition of salt and obtained dissociation constants for the oxidized complex at various concentrations of NaCl. These values were larger than those obtained previously by kinetic methods, measurements of NADPH-cytochrome c reductase and NADPH-DCIP reductase activities. Further, we examined the relationship between the change of these activities on the addition of salt and the complex concentration calculated using the dissociation constant obtained in this study and found that the change of these activities could not be attributed simply to dissociation of the oxidized complex.

Adrenodoxin↗
PubMed1981

Thyrotropin (TSH) receptor and adenylate cyclase activity in human thyroid tumors: absence of high affinity receptor and loss of TSH responsiveness in undifferentiated thyroid carcinoma.

TSH receptor and adenylate cyclase activity of plasma membrane fractions of human thyroid tumors were examined. The mean (+/- SD) basal adenylate cyclase activity in normal thyroid tissues was 0.35 +/- 0.33 nmole/mg protein x 10 min. The activity rose to 280% (range, 270-310%) of basal with TSH (166 mU/ml). In adenomas, the activity rose to 600% (range, 530-650), which was significantly higher than that of normal thyroid (P < 0.005). In the differentiated carcinoma, TSH responsiveness of adenylate cyclase was heterogenous (range, 110-520), but was qualitatively similar to that of the normal thyroid. On the other hand, basal adenylate cyclase activity of undifferentiated carcinoma was significantly lower than that of normal thyroid (0.018 +/- 0.007 nmol/mg protein x 10 min; P < 0.05) and was not stimulated by TSH. LH, FSH, and ACTH did not stimulate the enzyme in either kind of carcinomas. The mean (+/- SD) of the capacity of the high affinity receptor of adenomas (0.72 +/- 0.64 pmol/mg protein) and differentiated carcinomas (0.77 +/- 0.84) was not significantly different from that of normal thyroid (0.92 +/- 0.84). The affinity constants of the receptors in these three tissues were much the same (1.6-2.4 x 10(10) M-1). On the other hand, high affinity receptor could not be detected in all of the undifferentiated thyroid carcinoma. It seems likely that the failure of adenylate cyclase to respond to TSH in undifferentiated carcinoma of the thyroid is due to an alteration at the level of the receptor site. These data suggest that growth and metabolic activity of undifferentiated carcinoma may be independent of TSH, while those of adenoma and differentiated carcinoma may be affected by TSH.

Adenoma↗
PubMed1981

Immunobiological characteristics of germfree and specific pathogen-free cats.

The postnatal development of immune functions was investigated in kittens kept germfree from birth to 60 days of age and in the same cats after their transition to pathogen-free status until a maximum age of 1 year. The mean serum gamma-globulin level of germfree kittens was 0.5 +/- 0.1% at 10 days of age and increased to 11.5% at 1 year of age. Immunoglobulins IgG, IgA, and IgM were not detected in the serum during the first day of life. On the tenth day, IgG was the only immunoglobulin detected in the serum (mean 44 mg/dl), and all three classes of immunoglobulins were demonstrated at 60 days of age. Thereafter, immunoglobulin levels gradually increased with age. The total leukocyte count was constant, and differential counts disclosed a greater percentage of lymphocytes than that of neutrophils. There was 1-day delay in attaining a maximal incorporation of concanavalin A into lymphocytes of SPF cats as compared with conventional cats. The lymphocyte stimulation index was at least threefold greater in SPF cats than that seen in conventional cats.

Animals↗
PubMed1981

Cell-free translation of immunoglobulin G polypeptides by chicken bursal RNA.

The acquisition of messenger RNA controlling the translation of immunoglobulin G was studied in the chicken bursa of Fabricius, using the cell-free translation system of wheat germ lysate. Total cellular RNA extracted by phenol-1% sodium dodecylsulphate (pH 5.0 at 50 degrees) incorporated [3H]-leucine maximally. Sodium dodecylsulphate polyacrylamide gel electrophoresis of the immune precipitates of cell-free products with anti-chick IgG showed that polypeptides of gamma- and light chains were synthesized by bursal RNA from 20-day embryos and one-week-old chicks; in addition, a polypeptide with a molecular size of about 4 x 10(4) was synthesized. No appreciable synthesis of gamma- and light chains by bursal RNA from 12-day embryos was found.

Animals↗
PubMed1981

Clinical evaluation of 117 patients with Sjögren's syndrome.

The clinical entity of Sjögren's syndrome was limited to exocrine gland involvements in the present study, and 117 patients fulfilling this criterium were evaluated clinically to clarify the features of this syndrome. The following conclusions were obtained. (1) Frequent overlapping of this syndrome with other autoimmune diseases was observed, (2) This syndrome was demonstrated in young patients and middle-aged as well as postmenopausal patients. (3) Some of systemic manifestations demonstrated in patients with associated diseases were also observed in many patients without definite associated diseases. (4) Various hematological and serological abnormalities were demonstrated even in patients without associated diseases, and therefore, the participation of either a chronic inflammatory or immunologic process was suggested in this syndrome. (5) In patients with associated diseases, influence of the associated diseases was prominent in accordance with the patients' age, systemic manifestations and serological abnormalities. (6) The subclinical nature of sicca symptoms in young patients, as well as the delayed advancement of glandular involvement in this syndrome, were suggested. (7) Different entities were suggested in some patients with only lachrymal involvement.

Adult↗
PubMed1981

Characterization of sicca symptoms in patients with Sjögren's syndrome, and reports of six cases lacking subjective sicca features ("subclinical Sjögren's syndrome").

We evaluated seventeen ocular and oral symptoms in patients with Sjögren's syndrome (SjS) to characterize the subjective sicca symptoms of this syndrome. The following eleven symptoms were characteristic in patients with SjS compared with patients with rheumatoid arthritis (RA) or healthy adults.: (1) decreased lachrymation, (2) ocular foreign body sensation, (3) ocular filmy sensation, (4) increased mucous discharge from the eyes, (5) thirsty sensation, (6) decreased salivation, (7) increased dental caries, (8) abnormal sense of taste, (9) difficulty in chewing, (10) dryness of the oral cavity, and (11) increased fluid-intake with meals. Some of the symptoms were detectable in RA patients and healthy adults although the mean number of the positive symptoms was significantly higher in patients with SjS. The demonstration of three or more symptoms, therefore, will be sufficient in the consideration of the definite sicca features for this syndrome. The present studies also confirmed the chronological influence on the development of subjective sicca features in patients with SjS, and support our concept that patients lacking subjective sicca features are those in the early stages of this syndrome. Finally, six cases of SjS lacking subjective sicca features were described.

Adult↗