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Biomedical subjects

T Amagai

Publications and source records attributed to T Amagai.

At least 55 records · Page 3Linked to original sources
PubMed1985

[Transurethral laser surgery of the treatment of bladder tumor].

One hundred and eighteen patients with 169 bladder tumors were treated transurethrally by Nd:YAG laser surgery. In relation to the tumor staging, 79 of 103 patients of T1 (77%) underwent laser operation only, but most of the T2 cases (87%) required laser therapy with electroresection. With regard to the tumor size, 93 of the 97 small tumors (96%) were treated with laser irradiation alone, and 25 of 44 middle-sized tumors (57%) were eradicated by laser therapy, During and after the operation we never experience severe complications such as perforation of either the bladder or the intestine. Uncontrollable bleeding did appear in four cases. Tumor recurrence occurred in 25% for one year and 50% for three years. Therefore, laser surgery was limited to T1 tumor. But the indication of laser surgery would be magnified with the progress of the instrument and the technique.

Fiber Optic Technology↗
PubMed1985

Two subpopulations of stem cells for T cell lineage.

An assay system for the stem cell that colonizes the thymus and differentiates into T cells was developed, and by using this assay system the existence of two subpopulations of stem cells for T cell lineage was clarified. Part-body-shielded and 900-R-irradiated C57BL/6 (H-2b, Thy-1.2) recipient mice, which do not require the transfer of pluripotent stem cells for their survival, were transferred with cells from B10 X Thy-1.1 (H-2b, Thy-1.1) donor mice. The reconstitution of the recipient's thymus lymphocytes was accomplished by stem cells in the donor cells and those spared in the shielded portion of the recipient that competitively colonize the thymus. Thus, the stem cell activity of donor cells can be evaluated by determining the proportion of donor-type (Thy-1.1+) cells in the recipient's thymus. Bone marrow cells were the most potent source of stem cells, the generation of donor-derived T cells being observed in two out of 14 recipients transferred with as few as 1.5 X 10(4) cells. The stem cell activity of spleen cells was estimated to be about 1% of that of bone marrow cells, and no activity was found in thymus cells. By contrast, when the stem cell activity was compared between spleen and bone marrow cells of whole-body-irradiated (800 R) C57BL/6 mice reconstituted with B10 X Thy-1.1 bone marrow cells by assaying in part-body-shielded and irradiated C57BL/6 mice, the activity of these two organs showed quite a different time course of development. Spleen cells showed a markedly high level of activity 7 days after the reconstitution, followed by a decline, whereas the activity of bone marrow cells was very low on day 7 and increased crosswise. The results strongly suggest that the stem cells for T cell lineage in the bone marrow comprise at least two subpopulations, spleen-seeking and bone marrow-seeking cells. Such patterns of compartmentalization of stem cells in the spleen and bone marrow of irradiated recipients completely conform to the general scheme of the relationship between restricted stem cells and less mature stem cells, including pluripotent stem cells, which became evident in other systems such as in the differentiation of spleen colony-forming cells or of stem cells for B cell lineage.

Animals↗
PubMed1983

Mode of protection of mice against herpes simplex virus type 2 infection by Propionibacterium.

We compared various strains of Propionibacterium with regard to protection of young adult mice against lethal infection with herpes simplex virus type 2 (HSV-2). Propionibacterium acnes, P. granulosum, and P. avidum were protective, while P. acidi-propionici and P. lymphophilum were ineffective. The protective effect proved to be in the cell wall fraction. Attempts were made to elucidate possible mechanisms of the protection using both effective and ineffective strains. The results strongly suggest that induction of interferon rather than activation of macrophages and natural killer cells by Propionibacterium pretreatment plays a crucial role, directly or indirectly, in protection against infection by herpes simplex virus. Propionibacterium only moderately protected newborn mice against HSV-2 infection.

Adjuvants, Immunologic↗
PubMed1983

[Clinical effect of new alpha-adrenergic blocker on micturition disturbance of neurogenic bladder and lower urinary tract obstruction].

E-643, a newly developed alpha 1-adrenergic blocker with a postsynaptic action, was tried on 17 subjects, 10 patients with neurogenic bladder and 7 patients with lower urethral obstruction. The results of treatment were excellent in 5, good in 7, and poor in 5 of them, the rate of effectiveness therefore being 70.6%. The inhibitory effect of E-643 on the contractility of the detrusor was no stronger than that of other alpha-blockers. The rate of effectiveness for neurogenic bladders was as high as 80% whereas that for lower urethral obstruction was much lower: 57%. Concerning benign prostatic hyperplasia (B.P.H.) alone, this agent was markedly beneficial. In the case of B.P.H the urethra pressure in the prostatic urethra tends to drop and urination is facilitated even without a change in maximum urethral closure pressure, which reduces the amount of residual urine, this sequence of events taking place on condition that the contractility of the detrusor is adequate. According to urodynamic criteria, the underlying causes of the so-called bladder neck contracture can be classified into organic and functional obstruction, but it is mistaken to use this term for functional disturbance of the bladder neck. It seems worthwhile to determine the clinical effect of alpha-blockers on functional urethral obstruction. E-643 produced few if any appreciable signs or symptoms of side effects either subjectively or objectively.

Adrenergic alpha-Antagonists↗
PubMed1983

Augmentation of natural killer activity of human peripheral blood lymphocytes by human leukocyte interferon: characterization of the augmented activity.

The characteristics of natural killer (NK) activity of human peripheral blood lymphocytes treated with human leukocyte interferon (HuIFN-alpha) were compared with those of the untreated original NK activity. HuIFN-alpha, at a concentration of 50 IU/ml or more, augmented the NK activity against BALL-1, Daudi, and Namalwa target cells. On the other hand, the augmentation was less evident for the activity against Raji and Molt-4 cells. Original NK activity was detected mainly in the fraction that passed through a nylon wool column. Nylon-retained cells, however, could be activated by the addition of HuIFN-alpha to express activity against BALL-1. The activity of the nylon-passed fraction was augmented by HuIFN-alpha as well as that of unfractionated cells. NK cells could be activated by HuIFN-alpha under calcium-free conditions that allow NK cells to bind but not to lyse the target cells; augmented cytotoxicity was observed when calcium was added 2 hr later. This suggests that the augmentation of NK activity by HuIFN-alpha may have resulted from an increase in the number of NK cells.

Animals↗
PubMed1983

Local administration of interferon for malignant brain tumors.

We investigated the effects of local administration of interferon (IFN) on 13 patients with recurrent brain tumors. Histologic diagnoses were glioblastoma (eight patients), medulloblastoma (one), ependymoma (one), ependymoblastoma (one), pontine glioma (one), and astrocytoma (one). When tumor recurrence was evident local administration of IFN was started through an Ommaya reservoir, which was placed during repeat craniotomy. No tumor regressions were seen in the patients given weekly injections of IFN; however, in two of six patients given daily injections, a decrease of tumor volume and augmentation of natural killer activity were seen.

Adult↗
PubMed1982

Transurethral neodymium:YAG laser surgery for bladder tumors.

Forty-five patients with 63 bladder tumors were treated with transurethral neodymium: YAG laser irradiation. The operation was performed under lumbar or local anesthesia, the bladder being irrigated with a 10 per cent urigal solution. A five-second beam of 50 watt electric power was chosen as one unit of irradiation, and 5 to 50 units of irradiation were utilized for one operation. Forty-one tumors were completely resected with laser irradiation alone. In the other 22 tumors, electroresection or partial cystectomy was undertaken after the laser irradiation. Pronounced complications did not develop in any of the patients. Perforation was not experienced in our series. The bleeding at irradiation was minimal. Laser surgery through endoscopy thus represents a promising approach for the treatment of bladder tumors.

Adult↗
PubMed1982

The effect of ribavirin and rifamycin SV on age-dependent changes of the immune system during the adult life of SJL mice.

Ribavirin and Rifamycin SV, given from birth to adult life, arrest the loss of suppressor capacity, normally occurring in older SJL mice. The two drugs differ in their effect on Th-2-type help for the indirect plaque-forming response, i.e. for help which is independent of the carrier-hapten bridge. This type of help normally increases with age. Ribavirin treatment inhibits development of Th-2-type of help; Rifamycin SV does not interfere with the development of this type of help. Neither of the two drugs had an effect on the ability of SJL mice, not treated with aggregate-freed RGG, to make a plaque-forming response to aggregated RGG.

Aging↗
PubMed1982

Mechanisms involved in age-dependent decline of immune responsiveness and apparent resistance against tolerance induction in C57BL/6 mice.

The plaque-forming antibody response of C57BL/6 mice to rabbit gamma globulin (RGG) decreases as a function of ae. RGG in tolerogenic form induces tolerance of young mice but sensitizes older animals. If antigen is administered together with lipopolysaccharide, the age-dependent decline in immune responsiveness is not observed, nor are older animals sensitized by tolerogen. The age-dependent decline in immune responsiveness is due to a loss of T helper capacity; sensitization by tolerogen is attributable to a subpopulation of B cells which becomes sensitized by the tolerogen. Older animals, treated with tolerogen, show a degree of central tolerance of T cells and a relatively slight, age-dependent diminution in colchicine- or cyclophosphamide-sensitive precursors of suppressor cells.

Aging↗
PubMed1981

Resistance of MRL/Mp-lpr/lpr mice to tolerance induction.

Mice of strain MRL/Mp-lpr/lpr develop resistance against tolerance induction with aggregate-freed rabbit gamma-globulin as early as 6 weeks of age and show very complete resistance when they are 10 weeks old; congenic mice MRL-Mp+/+ of 6 and 10 weeks can be rendered tolerant. By reconstitution experiments, it was shown that T cells from MRL/Mp-lpr/lpr are responsible for the resistance to tolerance induction. A cell which is not colchicine-sensitive contributes to tolerance of MRL/Mp-+/+, but not to MRL/Mp-lpr/lpr mice. Resistance of T cells against tolerance depends on expression of the lpr gene.

Aging↗
PubMed1981

Diversity of age-dependent changes of antibody formation and of tolerance decrease.

Age-dependent changes in immune response and in tolerance occur at different rates in inbred mice of different genetic backgrounds. The change in tolerizability is connected with the change in the balance of the suppressor helper circuit; the change in B-cells, at least in C57BL/6 mice, appears to be also due to a regulatory change. Changes in immune responsiveness and tolerance inducibility appear to vary independently of one another.

Aging↗
PubMed1981

Studies on the termination of immunological tolerance in the mouse thymus cell population after irradiation.

Immunological tolerance in the mouse thymus cell population induced by the intravenous injection of deaggregated bovine gamma globulin was terminated by whole body irradiation. After irradiation, the weight of the thymus recovered biphasically, and the termination of tolerance occurred as early as in the first phase. Both Thy-1 antigen expression and helper activity of the thymus cell population in irradiated mice recovered in parallel with the recovery of the thymus weight. Sensitivity of the regenerating thymus cell to the tolerogen was not different from that of the normal thymus cell. The first phase of thymus regeneration may be caused by the proliferation and differentiation of relatively radioresistant and tolerogen insensitive precursors residing in the thymus. Tolerogen and/or immunogen reactive thymus cells may originate from the precursor.

Animals↗