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Biomedical subjects

Y Maeda

Publications and source records attributed to Y Maeda.

At least 991 records · Page 55Linked to original sources
PubMed1983

[Immunological evaluation of splenectomy in tumor-bearing mice].

The effect of splenectomy upon neoplastic outgrowth was examined after inoculation of methylcholanthrene-induced C3H/He murine tumors. Three days or 20 days after tumor inoculation, splenectomy resulted in significant retardation of tumor growth when compared with sham operation, while splenectomy 6, 9, 15 days after tumor inoculation did not alter the tumor outgrowth. These results suggest that spleen might have immunologically negative element in early or late stage of tumor burden. In fact, spleen cells from mice bearing MCA-F tumors for 3 days or 30 days nonspecifically facilitated the tumor outgrowth in Winn assay. The non-specific tumor-enhancing cells were radioresistant (700 rads), capable of phagocytizing carbonyl-iron and adherent to plastic dish suggesting those were tumor enhancing macrophages. On the other hand, spleen cells from tumor-bearing mice for 9 to 15 days specifically reduced the tumor growth in Winn assay, and those cytotoxic cells were radio-sensitive (700 rads) T cell population.

Animals↗
PubMed1983

[Role of the spleen in OK-432 immunotherapy and characterization of effector cells].

The mechanism of anti-tumor effect of OK-432 was examined in C3H/He mice transplanted with methylcholanthrene induced fibrosarcomas. Tumor growth was significantly reduced in mice treated with OK-432 daily for 7 days after tumor inoculation. Tumor growth was significantly reduced in Sham-operated mice treated with OK-432 when compared to untreated controls. On the other hand, splenectomized mice failed to respond to OK-432 immunotherapy, suggesting the spleen is an essential organ in host responsiveness to this immunostimulant. Further dissection of the mechanism of OK-432 immunotherapy was achieved by Winn assay with spleen cells taken from mice inoculated with MCA-F (1 X 10(5) cells) and OK-432 for 7 days. Spleen cells from tumor-bearing mice which had been treated with OK-432 further reduced the tumor growth compared with spleen cells from tumor-bearer and such cytotoxic activity was reduced by the spleen cells with treatment of anti-Thy 1. 2 serum plus complement or by 700 rads irradiation before Winn assay, suggesting that OK-432 generated cytotoxic T cell population in vivo.

Animals↗
PubMed1983

Characterization of a unique nuclear estrogen-binding component in an estrogen-responsive mouse Leydig cell tumor.

An estrogen-responsive mouse Leydig cell tumor line (Tumor 124958) has been shown to contain only a low-affinity binder for estradiol in the cytosol fraction. This differed from the putative estrogen receptor in terms of its hormone-binding specificity as well as affinity. In addition, the possibility that an estrogen receptor-like molecule exists in the nuclei even without hormonal stimuli was examined using purified nuclei. Scatchard plot analyses showed that these nuclei possessed a large amount of estrogen binder having a high affinity for estradiol and diethylstilbestrol. The content of this nuclear binding component was not diminished by using molybdate, a potent inhibitor for receptor activation, and in vitro incubation of collagenase-dispersed cells with estradiol did not cause significant increase in the number of nuclear binding sites when compared with the values obtained by direct incubation of isolated nuclei with estradiol. These results support the view that this nuclear estrogen binder is not due to artificial migration of the cytosol receptor into nuclei during homogenization. The characterization of this nuclear binding component under cell-free conditions revealed that its affinity for estradiol in Mg2+-containing buffer was temperature dependent (Kd 3 nM at 30 degrees and 12 nM at 0 degrees) without significant alteration in the number of maximum binding sites. Introduction of a chelating agent (ethylenediaminetetraacetate) into the buffer system abolished the temperature effect on the affinity, resulting in high affinity for estradiol at both low and high temperatures. These Mg2+ and temperature effects were reversible. In addition, when compared with putative nuclear estrogen receptors, this nuclear binding was observed to be relatively resistant to high salt or micrococcal nuclease treatments in relation to solubilization from nuclei. However, trypsin digestion was found to result in a marked decrease in the nuclear binding sites, indicating that this unique nuclear binding component contains a protein unit(s). These results suggest the possibility that this tumor line contains a unique unoccupied nuclear estrogen binder which might be able to transmit estrogen signals to tumor cell nuclei with regard to tumor growth.

Animals↗
PubMed1983

Steroid receptor forms and their interaction with cytoplasmic modulators.

The cytoplasmic modulator affecting steroid receptor functions was studied. The diminution in the concentration of the low molecular weight substances in the cytosol caused the increased interaction of hormone-receptor complexes with nuclei (a step termed activation). Furthermore, dialysis of rat uterine cytosol in the absence of estrogens subsequently followed by incubation with isolated nuclei resulted in the demonstration of an appearance of unoccupied nuclear receptor which was found to be 4S form. The addition of the dialyzable compound into rat uterine estrogen receptor system caused the suppression of temperature-dependent activation while the already-activated estrogen receptor was not affected by the small molecules in relation to its nuclear binding ability. These results may indicate that this small molecule, so-called the low molecular weight inhibitor, is capable of interacting with nonactivated receptor. In one of the estrogen-independent Leydig cell tumor lines, unique low-affinity estrogen binder with a mol. wt approximately 36,000 was identified. This binder did not show appreciable nuclear binding ability even after conventional heat activation. However, removal of the small molecules from this cytosol resulted in a marked increase in affinity for estrogens with a concomittant alteration of the mol. wt to approximately 70,000. These changes also paralleled a dramatic enhancement of nuclear binding ability. This small molecule might be different from the low molecular weight inhibitor suppressing receptor activation, since this tumor cytosol containing unique estrogen binder had much less inhibitory activity against receptor activation when compared with those in the other cytosol containing usual estrogen receptor systems. In adult rat urine cytosol, a new modulator was identified to recognize only activated estrogen receptor but not glucocorticoid receptor and to induce receptor aggregation with a concomittant loss of its nuclear binding ability. These reactions were accelerated by the presence of physiological or higher KCl concentration and exposure to a relatively high temperature (20-30 degrees C). Interestingly, this factor was not identified in the immature rat uteri or liver.

Adrenalectomy↗
PubMed1982

Caerulein and cholecystokinin suppress beta-endorphin-induced analgesia in the rat.

The analgesic action of beta-endorphin, as observed in the hot plate test with rats, was effectively suppressed by intracerebroventricular (i.c.v.) injection of caerulein and cholecystokinin octapeptide (CCK-8). The effect of caerulein was particularly striking; this peptide in doses of more than 0.09 nM lessened or abolished the analgesic effect of beta-endorphin in a dose of 0.7 nM. On the other hand, non sulfated CCK-8 had no significant effect on beta-endorphin-induced analgesia.

Analgesia↗
PubMed1982

Identification of storage-protein messenger RNA of the fleshfly Sarcophaga peregrina.

Storage-protein mRNA was found to be abundant in poly(A)-containing RNA extracted from the fat-body of third-instar larvae of Sarcophaga peregrina (fleshfly). This RNA sedimented at the position of 19S on sucrose-density-gradient centrifugation and the product of its translation in vitro was 75K protein (protein of mol.wt. 75 000), which was precipitated specifically with antibody against storage protein. This product was suggested to contain a signal sequence that is missing in mature storage protein. The poly(A)-containing RNA was also found to contain much of another mRNA coding for 25K protein (protein of mol.wt. 25 000), but the function of this protein is unknown.

Animals↗
PubMed1982

Stability of hemoglobin gene frequency in randombred chicken and quail populations.

The stability of hemoglobin polymorphism in a randombred chicken and a randombred Coturnix quail population was studied by comparing the frequencies of known hemoglobin mutant genes after several generations of maintaining nonselected randombred populations. The current gene frequency of .053 in the chicken population was similar to the .060 gene frequency determined 13 generations ago. A gene frequency of .069 was observed for the mutant hemoglobulin in the quail population compared to a .042 frequency 15 generations ago.

Animals↗
PubMed1982

[Problems on recurrence after removal of teratoma in pineal region--an experience of recurrence of pineal teratoma 4 years after tumor removal].

A case of teratoma in the pineal region which recurred 4 years after the first tumor removal was reported in this paper. When the patient was 5 years old, she, complained of headache and vomiting, and visited our hospital. As a heterogeneous mass with no enhancement effect was found in the pineal region by CT scan, she was admitted on November 9, 1976. There was no abnormalities on physical examination but neurological examination revealed slight disturbance of conjugate upward gaze (Parinaud's sign). Left vertebral angiogram demonstrated posterior superior displacement of posterior choroidal artery and downward displacement of Rosenthal vein, but early venous filling and tumor stain were not seen. Under preoperative diagnosis of a teratoma in the pineal region, the first operation (left occipital craniotomy and total removal of the tumor) was performed on November 24, 1975. Microscopic examinations revealed that the removed tumor was a mature teratoma in the pineal region. Postoperative course was uneventful and discharged on December 20, 1975. The follow-up study was continued at outside clinic after discharge. There was no signs of recurrence until 3 years after the first operation, but on January, 1981 (4 years after the first operation), she suffered from severe headache and vomiting again and re-admitted to our hospital on February 3, 1981. There was no remarkable neurological deficits except for the mild intracranial hypertensive sign and no changes of findings on angiogram. But CT findings were markedly characteristic. It revealed a heterogenous mass with remarkable enhancement effect in the pineal region and ventricular enlargement. Because a mixed type (teratomatous and germinomatous) of pineal tumors was suspected from the CT findings, irradiation was done after V-P shunt. The tumor was reduced to half size after the first course of 2000 rads irradiation, but there is no more reduction of the size of the tumor following the second course of 2000 rads (total 4000 rads) irradiation. Against the residual tumor, tumor removal was performed on June 2, 1981. Microscopically, the most part of the resected tumor showed fibrous changes caused by irradiation and partially teratomatous compartment. From this result (radiosensitivity and histology) the authors assumed that the recurred tumor could be a mixed type (germinoma and teratoma) of pineal tumor. Postoperative course was uneventful except for a transient disturbance of conjugate upward gaze and she was discharged on June 25, 1981. And now, there is no signs of recurrence 12 months after the second operation. Conclusively, it will be stressed that we should continue follow-up study the case even after total removal of teratoma, especially in the pineal region. Moreover, it was considered that there is a possibility of the changes of the histological features on recurrence of the pineal teratoma. When germinomatous compartment is suspected, irradiation is the first choice and then microsurgical operation should be done against residual tumor.

Brain Neoplasms↗