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Biomedical subjects

T Tada

Publications and source records attributed to T Tada.

At least 289 records · Page 16Linked to original sources
PubMed1989

Modulation of immune response against tumor cells by the in vivo administration of an autoreactive Th clone.

The immunization of C3H mice with irradiated syngeneic MM48 tumor cells induced specific tumor-neutralizing cells (TNC). The TNC activity was mediated by the L3T4+, Ly-2- T cell population, and the generation of TNC coincided with the appearance of delayed-type hypersensitivity response against MM48 antigen. The administration of an auto-I-Ak reactive T helper cell clone MS202 to normal C3H mice resulted in the facilitation of growth of MM48 tumor due to the induction of T suppressor (Ts) cells. Splenic T cells from animals given this T cell clone inhibited the TNC activity of immunized mice resulting in the escape of MM48 from the TNC effect. The surface phenotype of the Ts cells was L3T4+, Ly-2-. The Ts cells induced by the clone MS202 were totally antigen-nonspecific, and were able to suppress both the effector and inductive processes of TNC. The results suggest the presence of a physiological MHC-restricted T cell circuit that regulates immune responses against the growing tumors.

Animals↗
PubMed1989

Thymic atrophy characteristic in transgenic mice that harbor pX genes of human T-cell leukemia virus type I.

The human T-cell leukemia viruses (HTLV) are associated with T-cell malignancies in humans. The malignant transformation occurs after a long latency in some carriers, and its mechanism appears to be distinct from that of other classes of retroviruses which induce transformation through viral or cellular oncogenes. A widely postulated explanation is that the products of novel pX genes transactivate endogenous cellular genes which lead to tumor development in T cells. To directly examine the pathological effects of pX genes in vivo, we produced transgenic mice harboring the HTLV type I pX genes under several regulatory units: HTLV type I long terminal repeat, immunoglobulin enhancer-simian virus 40 promoter, and mouse mammary tumor virus long terminal repeat. Atrophy of the thymus was characteristic in these mice no matter which regulatory unit directed the expression of the genes.

Animals↗
PubMed1989

I-J and mechanism of immunosuppression.

I-J has been found to be an inducible isomorphic molecule expressed on class II-restricted T cells. It undergoes a systematic adaptive change in radiation bone marrow chimeras according to the environmental major histocompatibility complex (MHC). Recent biochemical studies demonstrated that I-J is a homodimer of MW 84,000-90,000 composed of 42,000-46,000 MW glycopeptide subunits. The molecule is different from class II-restricted T-cell receptor, class II antigens or putative mouse CD28. The ligation of I-J molecules with anti-I-J results in the suppression of T-cell responses by the inhibition of early signal transduction through antigen recognition.

Animals↗
PubMed1989

[MR measurement of normal brainstem cerebellum and corpus callosum on midsagittal section].

The dimensions of the brainstem, cerebellum and corpus callosum were measured on magnetic resonance (MR) images with sagittal spin-echo sequence. Eighty-two normal adults (average 49.6 years old) were measured. The mesencephalic, pontine or cerebellar diameters and lengths could be measured more accurately and reproducibly than medullary diameter and length. The anterio-posterior diameter of the pons and the cerebellum was 23.2 +/- 1.4 mm and 26.4 +/- 2.5 mm respectively. The length of the pons and the cerebellum was 27.8 +/- 2 mm and 45.8 +/- 3.5 mm respectively. We have observed focal thinning at the body of corpus callosum in 73%. This narrowing is almost unquestionably a normal variant.

Adolescent↗
PubMed1989

[Time course of blood velocity changes and clinical symptoms related to cerebral vasospasm and prognosis after aneurysmal surgery].

Cerebral vasospasm is a major complication associated with subarachnoid hemorrhage. In spite of extensive research, the pathogenesis of vasospasm remains obscure, and clinical management has so far been extremely difficult. For the evaluation of the efficacy of any treatment and the timing of operation, the development and resolution of the arterial narrowing should be monitored. It is important to know the correlation between the change in flow velocity and the course of clinical symptoms. In this study, the blood flow velocity in the different arteries was measured at short intervals (at least every third day) with transcranial Doppler ultrasonography, in eighteen patients with ruptured cerebral aneurysm. Flow velocity changes began to accelerate from 3 days after surgery, and reached the maximum value between 7 and 10 days, with normalization occurring within the following 2 weeks. The changes showed a significant relationship to the severity of vasospasm, the side of the operative approach, and the administration of calcium antagonist. Based on our results, we categorized the flow velocity changes of vasospasm for clinical practice as follows. (1) A slight acceleration of up to 120 cm/s in MCA and 90 cm/s in ACA was defined as within the normal range. In this state vasospasm was never observed angiographically. (2) Flow velocity changes between 120 and 140 cm/s were a subcritical state. These changes were seen in vasospastic patients who did not develop ischemic deficits. (3) Flow velocity changes of over 140 cm/s in MCA and 100 cm/s in ACA were critical vasospasm, since all of the patients who developed ischemic symptoms were in this group. Velocity changes higher than 170 cm/s in MCA and 130 cm/s in ACA seem to indicate a critical condition with a tendency to develop into brain infarction. The comparison between the time course of the flow velocity changes and clinical status showed that in symptomatic vasospasm the increase in velocity occurred before the manifestation of clinical symptoms. The transcranial Doppler measurements help to identify those patients who have a high risk of developing neurological deficits due to vasospasm, and help to select those who would benefit from preventive treatment in asymptomatic stage.

Adult↗
PubMed1989

[A case of leiomyoblastoma of the jejunum].

Reported is a submucosal tumor of the jejunum that had developed in a 46-year-old man who manifested general fatigue and anemia. The tumor measured 3.0 x 3.0 cm and was composed of polygonal and/or round cells with a clear zone surrounding the nucleus. Five mitotic figures per 50-power fields were present. The light microscopic appearance was consistent with those of a Leiomyoblastoma. Follow-up evaluations approximately 2 years after the resection showed no evidence of metastasis or recurrence.

Humans↗
PubMed1989

[Three cases of intralobar pulmonary sequestration--demonstration of an aberrant artery by contrast CT].

Three cases of intralobar pulmonary sequestration, whose aberrant arteries could be demonstrated by contrast CT were reported. We confirmed these aberrant arteries both by selective angiography and/or surgical resection. We conclude that contrast CT may be of great use and benefit in the radiological workup of suspected cases of pulmonary sequestration proceeding to angiography.

Adult↗
PubMed1989

[A case report of quadriparesis due to compression of the medulla oblongata by the elongated left vertebral artery].

A patient, 30-year-old man, was admitted to Shinshu University Hospital with gait disturbance and numbness of both arms and legs in June 1985. General physical findings were normal except for facial asymmetry, i.e. mild right facial hemiatrophy. Blood pressure was normal and there were no signs of arteriosclerosis. Neurological examination revealed marked bilateral pyramidal tract signs, muscular weakness of all extremities predominant of the right side, spastic gait and sensory disturbance with impairment of pin prick and light touch sensation in the second and third trigeminal nerve regions and extremities of the left side, and mild loss of vibratory sense and numbness in all extremities. X-ray examination of the cervical spine and the myelogram of the spinal canal were normal. CT scan of the brain performed 3 hours after the myelography showed that the left vertebral artery extended from the left side of the medulla oblongata to the midline and distorted it by compression. MRI confirmed the findings of the CT scan. Vertebral angiography disclosed that the elongated left vertebral artery crossed the ventral aspect of the medulla oblongata. Compression of the medulla oblongata by the vertebral artery was diagnosed and neurovascular decompression was performed. About one month after the operation his spastic gait and muscular weakness were slightly improved, but these symptoms progressed thereafter. One year after operation his spastic gait was more marked than preoperatively. In many cases with dolichoectatic intracranial arteries, hypertension and arteriosclerosis have been reported to be usually associated with this condition. In other opinions dolichoectasia has been suggested to be a congenital disease, because such vessels are occasionally present in children.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Analysis of two distinct B cell activation pathways mediated by a monoclonal T helper cell. II. T helper cell secretion of interleukin 4 selectively inhibits antigen-specific B cell activation by cognate, but not noncognate, interactions with T cells.

A single monoclonal T helper (Th) clone can activate B cells in two distinct pathways; a cognate pathway requiring a major histocompatibility complex (MHC)-restricted T-B cell interaction, and a noncognate pathway not requiring an MHC-restricted T-B cell interaction. The present study was undertaken to investigate whether Th cells mediating a given immune response provide further regulatory function to B cells other than helper function. It was demonstrated that conditions of high antigen concentration which activate a noncognate B cell activation pathway simultaneously inhibit IgG responses. The inhibition is shown to be mediated by the T cell factor interleukin 4, produced by activated cloned Th cells. The inhibitory effect of this factor is directed to B cells and is MHC-unrestricted, antigen-nonspecific, and IgG class-specific. In addition to being susceptible to the effects of augmenting cells and suppressor cells, cloned Th cell populations can therefore themselves function as regulatory cells to inhibit IgG responses when stimulated with high dose of specific antigen. These results indicate that Th cells function to regulate B cells both positively and negatively, depending upon the activation conditions.

Animals↗
PubMed1988

Epitopes associated with major histocompatibility complex (MHC) restriction site of T cells. IV. I-J epitopes on MHC-restricted cloned T cells.

We studied the expression of an I-Jk epitope on class II-restricted cloned L3T4+ T cells established from H-2k, H-2b, F1 and semiallogeneic radiation bone marrow chimeras by the inhibition of antigen-induced T cell proliferation and in vitro secondary antibody response, and by the direct immunofluorescence with a monoclonal anti-I-Jk. Both I-Ak- and I-Ek-restricted T cells were shown to carry the identical I-Jk epitope regardless of their genotypic origins, antigen specificity, and helper or suppressor function. None of the I-Ab-restricted clones derived from similar animals showed the I-Jk epitope. This isomorphism, regardless of the restriction specificity for I-Ak or I-Ek, contradicts the idea that I-J is an idiotypic determinant on class II-restricted T cell antigen receptor (TcR). In fact, the I-Jk epitope was not comodulated with TcR/T3 complex when incubated with an anti-T3 antibody, indicating that I-J is a new isomorphic receptor for self different from TcR alpha/beta heterodimers.

Animals↗
PubMed1988

Trochlear nerve meningioma in von Recklinghausen's disease.

A trochlear nerve meningioma in a patient with von Recklinghausen's disease is reported. The tumour appeared to have originated from the trochlear nerve itself, having no connection either with the neurinomas present in the adjacent regions, or with the tentorium. Histological examinations revealed that the tumour was a meningotheliomatous meningioma and the trochlear nerve fibres were placed in the periphery of the tumours. It was noteworthy that diplopia was not detected either before or after the resection of the trochlear nerve with the tumour.

Adult↗
PubMed1988

Selective suppression of the generation of anti-tumor L3T4+ but not of Lyt-2+ T cell-mediated immunity in the tumor-bearing state.

C3H/He mice hyperimmune against syngeneic MH134 hepatoma were prepared by intradermal (id) inoculation of viable tumor cells followed by surgical resection of the tumor and by repeated id challenges with viable tumor cells. Winn assays performed utilizing spleen cells from these mice have revealed that both Lyt-2+ and L3T4+ T cell subsets from MH134-hyperimmune mice produced complete tumor protection. The in vivo tumor-neutralizing activity was also found in spleen cells from tumor-bearing mice at various times after id implantation of MH134 tumor cells. However, in contrast to comparable tumor-neutralization by Lyt-2+ and L3T4+ T subsets from hyperimmune mice, only the Lyt-2+ T cell subset from tumor-bearing mice was capable of mediating the in vivo protective immunity. L3T4+ T cell-mediated immunity was not detectable in the tumor-bearing state irrespective of the length of the sensitization period with a primary growing tumor, but emerged in the mice which resisted the first tumor challenge after the resection of the primary tumor. These results indicate that the emergence of L3T4+ T cell-mediated anti-tumor immunity is stage-dependent and the Lyt-2+ T cells represent the main functional subset in the tumor-bearing state, although both subsets of T cells are potentially capable of effecting anti-tumor in vivo immunity. The results are discussed in relation to the selective suppression of the L3T4+ but not of Lyt-2+ T cell function in the tumor-bearing state.

Acquired Immunodeficiency Syndrome↗