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T Tada

Publications and source records attributed to T Tada.

At least 253 records · Page 14Linked to original sources
PubMed1991

Post-translational attainment of allelic exclusion of the T cell receptor alpha chain in a T cell clone.

Two in-frame rearranged mouse TCR alpha chain genes from a single CD4+ T cell clone, MS202, specific for self-class II MHC antigen were transfected into a TCR-negative T cell hybridoma together with a beta chain gene derived from the same T cell clone. Both alpha chain genes were efficiently transcribed and translated in the cytoplasm of host cells, but only one alpha chain (V alpha 5) was expressed on the cell surface in association with the partner beta chain (V beta 4). The other alpha chain gene (V alpha 4) was translated into a mature form of the alpha chain but was unable to make a pair with the beta chain, being prohibited from the surface expression. The supertransfection of the CD4 gene into the alpha beta transfectants did not alter the transcription and expression of both combinations of TCR alpha and beta genes. The original self-class II reactivity was, however, reconstituted only in the cells expressing V alpha 5 and V beta 4 genes supertransfected with CD4. These results indicate that the allelic exclusion of MS202 was achieved by a post-translational mechanism where the product of an in-frame rearranged alpha chain was unable to be expressed on the cell surface, allowing further rearrangement and expression of the other alpha chain gene. The self-class II reactivity of TCR was dependent on the co-expression of CD4 molecules.

Alleles↗
PubMed1991

Human complement component factor B rescues HIV-1-infected leukemic T cells from cytopathic death.

The addition of 5-10% of fresh normal human serum (NHS) from normal individuals into a culture of primarily HIV-1-infected CD4+ leukemic T-cell lines CEM and MT4 was found to rescue the infected cells from cytopathic death, enabling the cells to achieve growth within 10 days. The HIV-1-infected cells cultured in ordinary medium with fetal calf serum (FCS) all died within 10 days. The effect of NHS was ascribed to human complement component factor B and one or more factor B-dependent heat-labile co-factors. The cells which survived in the presence of NHS rapidly lost surface expression of CD4 and became completely resistant to rechallenge by HIV-1. Viral genomes were dramatically reduced in surviving cells within 30 days, and one cell-line CEM completely expelled them during this period. The results suggest that factor B has protective and potential therapeutic significance in HIV-1 infection.

CD4 Antigens↗
PubMed1991

Dynamic properties of self-retaining retractors under load.

Dynamic properties of seven kinds of self-retaining retractors were examined by analyzing the stress-strain curve of the flexible arm under load. The stress that generated a remaining strain of 1 mm was about 80% of the maximum stress of the fixed flexible arm, and was a suitable indicator of the ability of a retractor under load. It had good correlation with the fixing torque of the flexible arm and was also influenced by the diameter of the arch of the fixed flexible arm. For all three commercially available retractors, the strongest resistance was obtained when the flexible arm was arranged in a semicircular shape with a diameter of 20 cm, regardless of the length of the arm. The retractor made of titanium alloy was superior to the retractor of the same shape made of stainless steel for vertical load, regardless of different arm-fixing torques. The tapered flexible arm of the Mizuho titanium retractor showed greater resistance to loading than a nontapered one at stronger arm-fixing torques. The Aesculap Leyla retractor had different dynamic properties from the Mizuho stainless retractors, despite their similarity in shape. The Leyla retractor was weaker than the Mizuho stainless retractors for vertical loading but stronger for horizontal loading. These experimental observations may be helpful when applying a self-retaining retractor during surgery.

Equipment Design↗
PubMed1991

Immunohistochemical localization of Zn-alpha 2-glycoprotein in normal human tissues.

The Zn-alpha 2-glycoprotein (Zn-alpha 2-GP) is present at a high concentration in the seminal plasma and at significant levels in other human body fluids. Its precise localization, however, has remained unclear, as well as its physiological and pathological significance. The present study reports the immunohistochemical localization of this protein in normal adult human tissues. Localization of the reactive product to anti-human plasma Zn-alpha 2-GP antibody was demonstrated in the following cells: luminal and basal cells of the prostate gland, luminal epithelial cells of the acini and of some ducts of the mammary glands, luminal cells of the secretory portion of the eccrine and apocrine sweat glands, serous cells of the salivary, tracheal, and bronchial glands, acinar cells of the esophageal glands, exocrine acinar cells of the pancreas, hepatocytes of the liver, and epithelial cells of the proximal and distal tubules in the kidney. The present results suggest that Zn-alpha 2-GP exerts some unknown but fairly widespread exocrine function and may be produced in the various epithelial cells tested. Hepatocytes are also suggested to be a source of the protein in the blood plasma.

Adult↗
PubMed1991

[Study on digestibility and energy availability of daily food intake (Part 4. Shiitake mushroom)].

The digestibilities of nutrients and energy in Shiitke mushrooms (Lentinus edodes) was measured in healthy adult males. A test diet was given for 5 days after 5 days on a basal diet which supplied 40g/day of protein and 45kcal/kg/day of energy. The test diet was identical with the basal diet except that shiitake was incorporated. Digestibility was calculated by the difference of fecal output between the test period and the basal period. The results obtained were follows: 1. Shiitake 60g/day intake level Digestibility of protein was 69.3 +/- 11.2%. Digestibility of fat was 66.6 +/- 24.9%. Digestibility of carbohydrate was 55.7 +/- 10.5%. The ratio of the total available energy to intake energy (Net Energy Availability) was 55.4 +/- 15.4%. 2. Shiitake 40g/day intake level Digestibility of protein was 85.5 +/- 23.8%. Digestibility of fat was 70.0 +/- 90.1%. Digestibility of carbohydrate was 65.8 +/- 13.1%. The ratio of the total available energy to intake energy (Net Energy Availability) was 67.4 +/- 25.9%.

Adult↗
PubMed1991

Absence of atrial contraction and exercise in patients with isolated atrial fibrillation.

The aim of the study was to assess the effect of absence of atrial contraction during exercise. During the incremental ergometer exercise tests, heart rate, oxygen uptake, and oxygen pulse in patients with isolated atrial fibrillation were compared with those in control subjects at rest, at the exercise level of gas exchange anaerobic threshold, and at peak exercise. The study population consisted of 51 subjects aged 40 years or more: 12 patients with isolated atrial fibrillation and 39 control subjects with normal sinus rhythm. Heart rate in control subjects was lower than that in patients with isolated atrial fibrillation, at rest, anaerobic threshold, and peak exercise (74 +/- 12 vs 85 +/- 8 beats/min at rest, 108 +/- 16 vs 134 +/- 18 beats/min at anaerobic threshold, and 151 +/- 16 vs 173 +/- 22 beats/min at peak exercise, all p less than 0.01). During exercise, oxygen uptake in patients with isolated atrial fibrillation was not significantly different from that in control subjects. Oxygen pulse in patients with isolated atrial fibrillation was lower than that in control subjects during exercise (6.45 +/- 2.04 vs 7.84 +/- 1.63 ml/beat at anaerobic threshold, 7.79 +/- 2.28 vs 9.16 +/- 1.79 ml/beat at peak exercise, both p less than 0.05). In patients with isolated atrial fibrillation, the oxygen pulse might be reduced due to the lack of atrial contraction during exercise. However, the oxygen uptake that represents the exercise capacity would be preserved with the increase in heart rate.

Adult↗
PubMed1991

[Sequential changes in content of excitatory amino acids in the epileptic focus during seizure].

Recently much attention has been paid to excitatory amino acids in seizure susceptibility and induction. In order to examine the relationship between epilepsy, especially seizure induction, and excitatory amino acids, we examined sequential change in content of excitatory amino acids in the epileptic focus by microdialysis system in a cat amygdaloid kindling model. Fifteen crossbred adult cats divided into three groups: a sham operation group (Sh) as the control, just after stage 4 group (S4), and just after stage 6 seizure group (S6). Under halothane anesthesia, Microdialysis probe was inserted to the kindled focus, the right amygdala, and glutamate and aspartate contents of extracellular fluid were measured from 15 minutes prior to 30 minutes after seizure by high performance liquid chromatography (HPLC). The probe was perfused with artificial cerebrospinal fluid at a flow rate of 2 microliters/min for 5 minutes. Before seizure, glutamate and aspartate concentration showed no significant changes in the S4 and S6 group compared with the Sh group. But after seizure, glutamate concentration was significantly higher in the S4 and S6 group temporally, while aspartate concentration was higher only in the S6 group temporally. Based on the results that the release of glutamate and aspartate do not change in seizure susceptibility, that glutamate is released in partial seizure, and that glutamate and aspartate are released in generalized seizure from the epileptic focus, excitatory amino acids are involved in seizure induction in a cat amygdaloid kindling.

Amino Acids↗
PubMed1991

[A clinicopathological study of 17 cases recovered from acute tubular necrosis].

Renal biopsy specimens of 17 cases recovered from clinical acute renal failure (ARF) and subsequent pathological acute tubular necrosis (ATN) were analyzed clinicopathologically. The cases were divided into two groups: 11 patients who underwent hemodialysis (HD group) and 6 patients who did not need hemodialysis (non-HD group). The varied histopathological findings were assessed by scoring as parameters and were compared between the two groups and with severity of the clinical conditions as well. Among the histopathological parameters, tubulorrhexis and cell infiltration, mainly composed of lymphocytes, in the interstitium as well as in the tubules were significantly marked in the HD group, while other parameters such as necrosis, flattening, vacuolization and regeneration of the tubular epithelial cells and presence of casts were not necessarily significant. Tubulorrhexis were supposed to reflect the severity of the attack factors on the kidney which had caused ARF and subsequent ATN, and to have caused in turn prolongation of the recovery of the impaired renal function. Cell infiltration, which was divided into 4 types according to the corresponding conditions, might probably have affected the prolonged recovery in the HD group. In 8 cases which could be followed up for 2 years, non showed aggravation of the renal function.

Adult↗
PubMed1991

Calpain and kininogen mediated inflammation.

On the basis of previous findings that N-acetyl nonapeptide from the human calpain I large subunit has chemotactic activity for neutrophils, more than 30N-acetyl and unmodified peptides which have N-terminal amino acid sequences of the large and small subunits of calpains I and II were synthesized and their chemotactic activity was estimated. In addition to the above N-acetyl nonapeptide from the calpain I large subunit, an unmodified nonapeptide from the calpain II large subunit and several N-acetyl peptides of different lengths from the small subunit showed chemotactic activity. Furthermore, when calpain was incubated with either high molecular weight or low molecular weight kininogen, kinin liberation occurred with simultaneous inhibition of calpain by kininogen. These data suggest that chemical mediators generated from the calpain-kininogen system may participate in migration and accumulation of neutrophils to the inflammatory locus.

Amino Acid Sequence↗
PubMed1990

CD8+ suppressor T cell clone capable of inhibiting the antigen- and anti-T cell receptor-induced proliferation of Th clones without cytolytic activity.

A CD8+ Ts clone 13G2 was established from lymph node cells of bovine alpha s1-casein-primed C57BL/6 mice by in vitro antigenic stimulation followed by maintenance with IL-2-containing medium. The clone suppressed the Ag-induced proliferative responses of CD4+ Th cell clones without detectable cytotoxicity for both APC and responding T cells. The clone was able to suppress the in vitro proliferative response and antibody formation of Ag-primed lymph node cells. The suppression was Ag-nonspecific and not restricted to the MHC. The clone was able to suppress the proliferation of Th clones induced by an immobilized anti-TCR antibody in which APC was absent. The clone was, however, unable to suppress the proliferation of Th clones induced by anti-CD3 or IL-2. Thus, the mechanism of suppression by 13G2 was found to be due to a direct action on Th by inhibiting a consequence of signal transduction initiated through the TCR.

Animals↗
PubMed1990

Enhanced production of IL-6 in tumor-bearing mice and determination of cells responsible for its augmented production.

IL-6 is a cytokine secreted in normal individuals by monocytes, fibroblasts, and endothelial cells. We have found increased levels of IL-6 in the sera from MH134 hepatoma- and CSA1M fibrosarcoma-bearing mice. Concerning the capacity of these tumor cells themselves to produce IL-6 in vitro, they exhibited the distinct contrast, i.e., the MH134 tumor cells produced high levels of IL-6 whereas the CSA1M generated a marginal level of IL-6. It was, however, demonstrated that appreciably enhanced IL-6 production was observed in spleen cell culture supernatants from both types of tumor-bearing mice when compared to those obtained from normal mice. More importantly, in contrast to the production of IL-6 by non-T cell compartment of normal spleen cells, enhanced IL-6 production of spleen cells from tumor-bearing mice was ascribed to T cell compartment. Analysis of T cell phenotype has revealed that enhanced IL-6 production was mediated predominantly by Lyt-2+ but not by L3T4+ T cell subset. Thus, these results indicate that increased circulating IL-6 is elicited in the tumor-bearing state and that irrespective of the potential of tumor cells themselves to produce IL-6, T cells, especially Lyt-2+ T cells from tumor-bearing mice are responsible for such a high level of IL-6 production.

Animals↗
PubMed1990

Growth autonomy and tumorigenicity of interleukin 6-dependent B cells transfected with interleukin 6 cDNA.

We introduced an IL-6 cDNA expression vector into a murine B cell line, the growth of which definitely required the presence of exogenous IL-6. The transfected cells secreted substantial amounts of IL-6, to which they themselves responded by proliferating without further requirement of exogenous IL-6. The proliferation was a direct function of cell density and was inhibitable by antibodies to IL-6, indicating the autocrine nature of the growth. The IL-6 cDNA-transfected cells displayed greatly enhanced tumorigenicity when inoculated into syngeneic and nude mice. Our data suggest that an IL-6 autocrine self stimulation confers on B cells a selective growth advantage and results in the induction of progression of the malignant state of B cells.

Animals↗
PubMed1990

Immune dysfunction expressed selectively on L3T4+ T cells in the tumor-bearing state.

Spleen cells from normal C3H/He or BALB/c mice generate cytotoxic T-lymphocyte (CTL) responses to both trinitrophenyl (TNP)-modified syngeneic cells (TNP-self) and allogeneic cells. In contrast, cells from these strains of mice bearing a syngeneic tumor failed to induce anti-TNP-self-CTL responses, although portions of the same responding cells generated comparable anti-allo-CTL responses to those induced by normal responding cells. Although anti-allo-CTL responses were inducible from only Lyt-2+ T-cell subset of responding cells from normal or tumor-bearing mice, induction of TNP-CTL responses required the participation of L3T4+ T-cell subset as well as Lyt-2+ CTL precursors. In addition, the fact that the addition of concanavalin A-stimulated culture supernatant to cultures of responding cells from tumor-bearing mice resulted in the induction of appreciable anti-TNP-self CTL responses demonstrated the defect of L3T4+ T-cell function in the tumor-bearing state. Such a functional defect was ascribed neither to the loss of L3T4+ T cells nor to the generation of suppressor cells in spleen cells of tumor-bearing mice. It was found on one hand that in vitro stimulation of antigen-presenting cell (APC)-depleted normal responding population with TNP-self prepared from cells of normal or tumor-bearing mice produced comparable anti-TNP CTL responses. On the other hand, APC-depleted responding cells from tumor-bearing mice were unable to induce anti-TNP CTL responses under conditions in which APC-depleted normal responding cells induced an effective TNP-CTL response. These results indicate that selective impairment of L3T4+ T cell-mediated immunity is induced in the tumor-bearing state and that such an impairment is ascribed to the dysfunction of L3T4+ T cells themselves, but not of APC required for the activation of L3T4+ T-cell subset.

Animals↗
PubMed1990

Effects of midazolam on the threshold of lidocaine-induced seizures in the dog--comparison with diazepam.

The anticonvulsive effect of midazolam was compared with that of diazepam in ten dogs. Lidocaine-induced seizure waves on the electroencephalogram were used to observe the suppressive effect of the drugs. Midazolam, 0.2 mg.kg(-1), was found to possess a stronger suppressive effect against lidocaine-induced seizures than the same dose of diazepam. These two drugs showed to possess similar effects on cerebral and systemic circulations and cerebral metabolism during seizures.

Journal Article↗
PubMed1990

Synergistic T-T cell interaction present in alloreactivity: determination of 'MLR helper' T cell subsets.

CD4 and CD8 T cell subsets involved in primary allo-MLR responses were re-evaluated in the present study. The slope analysis of B6 allo-MLR responses to MHC class I-disparate bm1 and class II-disparate bm12 revealed the presence of a T-T cell interaction between CD4 and CD8 T cell subsets. The allo-MLR response of B6 CD4 T cells to bm12 was completely blocked by anti-L3T4, indicating that the function of CD4 T cells is required for allo-MLR responses to bm12. It was further demonstrated that the function of CD8 T cells in class II-disparate allo-MLR is to augment the proliferative response of CD4 T cells. On the other hand, CD8 T cells primarily responded to class I-disparate allo-MLR, and CD4 T cells function to augment the proliferative response of CD8 T cells. It was further indicated that CD4 and CD8 T cells recognize both class I and class II MHC. The CD4 T cell recognition of allo-class I and CD8 T cell recognition of allo-class II induces insufficient signals for proliferation of these T cells. Thus, the class I-reactive CD4 and class II-reactive CD8 T cell subsets function as helper cells ('MLR helper' T cells) for proliferating T cells in MLR responses.

Animals↗
PubMed1990

Cell division-associated expression of an epitope, KH17, on early developing thymocytes.

A newly established monoclonal antibody, KH17, detects a unique epitope temporarily expressed on early developing CD3-thymocytes confined to a cycling stage. KH17 is detectable on a part of CD4-CD8-,CD4-CD8+, and CD4+CD8+ cells, but not on CD4+CD8- thymocytes. By four-color flow cytometry analysis using KH17, we were able to define the heterogeneity of immature CD4-CD8- thymocytes by the expression of KH17 and IL-2R. In Thy-1-congeneic bone marrow chimeras, the appearance of KH17-IL-2R+ thymocytes preceded the increase of KH17+IL-2R- cells. The antibody could also divide CD3-CD4-CD8+ cells into two subpopulations, KH17+ and KH17-, which showed a continuum. In the fetal thymus there was a rapid and dramatic increase of KH17-CD4+CD8+ thymocytes concomitant with a decrease of KH17+CD4-CD8+ thymocytes in later gestation days. KH17 is not expressed on resting peripheral T cells, but is expressed on a large proportion of Con A-activated blastic spleen cells. The KH17 molecules precipitated from Con A-activated spleen cells were 55 and 75 kd polypeptides, but different from IL-2R subunits.

Animals↗