Search PubMed⌕ Search

Biomedical subjects

T Hara

Publications and source records attributed to T Hara.

At least 955 records · Page 53Linked to original sources
PubMed1986

Human T cell activation. III. Rapid induction of a phosphorylated 28 kD/32 kD disulfide-linked early activation antigen (EA 1) by 12-o-tetradecanoyl phorbol-13-acetate, mitogens, and antigens.

With human T cells activated by 12-o-tetradecanoyl phorbol-13-acetate (TPA) as immunogen, an IgG2a mAb, early activation antigen 1 (EA 1), was generated against a 60-kD protein with disulfide-linked 28-kD and 32-kD subunits. Both subunits were phosphorylated. The antigen, EA 1, was readily detected on approximately 60% of isolated and cryopreserved thymocytes, as determined by indirect immunofluorescence. A low level of EA 1 expression was detectable on 6-7% of blood lymphocytes. TPA-activated T cells expressed EA 1 as early as 30 min after activation. By 1 h, 85-90% of the T cells stained with mAb EA 1. By 3-4 h, the expression of EA 1 was detected in greater than 95% of the T cells. Although the percentages of EA 1+ T cells did not change, the intensity of staining increased slightly. After 18-24 h, both the percentage of EA 1+ cells and the intensity of staining decreased gradually. TPA-induced EA 1 expression was independent of monocytes. EA 1 expression was slightly delayed in T cells that were isolated without the rosette selection and treated with TPA. Nevertheless, greater than 85% of these T cells expressed EA 1 within 1 h, and the maximal number of EA 1+ T cells was also detected at 3-4 h. In T cell populations with 1-2% monocytes, about 50-90% of the PHA- or Con A-activated T cells expressed EA 1 with a slower kinetics. EA 1 expression preceded that of IL-2-R in these activation processes. Similarly, T cells activated by soluble antigens (tetanus toxoid and PPD) and alloantigens in MLR also expressed EA 1 after a longer incubation. Approximately 20% of the T cells stained for EA 1 at day 6. EA 1 expression was not limited to activated T cells. B cells activated by TPA or anti-IgM antibody plus B cell growth factor expressed EA 1. The kinetics of EA 1 expression was markedly slower and the staining was less intense. Repeated attempts to detect EA 1 on resting and TPA-activated monocytes and granulocytes have not been successful. However, the detection of EA 1 in nonlymphoid cell lines would indicate that EA 1 may have a broader cell distribution. EA 1 expression was due to de novo synthesis, as the induction of EA 1 was blocked by cycloheximide and actinomycin D.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Thermodynamic properties of oxidation-reduction reactions of bacterial, microsomal, and mitochondrial cytochromes P-450: an entropy-enthalpy compensation effect.

An optically transparent thin-layer electrode cell with a very small volume was used for determination of the formal reduction potentials of bacterial, microsomal, and mitochondrial cytochromes P-450. At an extrapolated zero concentration of dye, the bacterial cytochrome from Pseudomonas putida catalyzing the hydroxylation of camphor and the adrenal mitochondrial cytochrome catalyzing the cholesterol side-chain cleavage reaction had formal reduction potentials of -168 and -285 mV (pH 7.5 and 25 degrees C), respectively. The oxidation-reduction potentials for the rabbit liver microsomal cytochrome P-450 induced by 3-methylcholanthrene and the mitochondrial cytochrome for steroid 11 beta-hydroxylation were found as -360 and -286 mV, respectively. Potential measurements at different temperatures allowed documentation of the standard thermodynamic parameters for cytochrome P-450 reduction for the first time. All cytochromes tested were found to have a relatively large negative entropy change upon reduction. The extent of these changes is comparable to that observed for the ferric-ferrous couple of cytochrome c. An entropy-enthalpy compensation effect was observed among the four cytochromes P-450 examined although the correlation is weaker than that observed with cytochrome c isolated from various sources.

Adrenal Cortex↗
PubMed1986

Treatment of childhood acute lymphoblastic leukemia with intermediate-dose cytosine arabinoside and adriamycin.

Eight pediatric patients with acute lymphoblastic leukemia (ALL) were treated with intermediate-dose cytosine arabinoside (ID-AraC, 1 g/m2) in combination with adriamycin except one patient. Of the eight patients, four refractory to the initial induction therapy and one in bone marrow relapse gained complete remission with two to three cycles of this therapy. Four of the five patients have been in continuous remission for 4 to 24 months with the maintenance therapy of monthly administration of ID-AraC. One patient in central nervous system (CNS) relapse has continued in remission from CNS leukemia after two cycles of the therapy. Side effects of ID-AraC and adriamycin were generally mild to moderate and tolerable in all children. These results suggest that the use of ID-AraC and adriamycin might prove effective in the treatment of ALL refractory to other regimens.

Adolescent↗
PubMed1986

Selective in vitro and in vivo growth inhibition against human yolk sac tumor cell lines by purified antibody against human alpha-fetoprotein conjugated with mitomycin C via human serum albumin.

The anticancer drug mitomycin C (MMC) was conjugated with an affinity-purified horse antibody to human alpha-fetoprotein (aAFP) with human serum albumin (HSA) as the intermediate drug carrier. The conjugate (aAFP:HSA:MMC molar ratio, 1:1:30) retained full antibody binding activity as determined by a competitive binding radioimmunoassay. In a cytotoxicity test in which the AFP-producing human yolk sac tumor TG-1 cells were preincubated with test materials for 2 h followed by an additional 48-h culture in fresh medium, the conjugate was 20-fold more cytotoxic than free MMC at an equivalent MMC concentration of 100 ng/ml. The in vivo antitumor effect of the conjugate was tested against the human yolk sac tumor JOG-9 growing in athymic nude mice. When the tumor-bearing mice were treated with a total of 6 injections given on 2 consecutive days and then every other day starting 8 days after SC tumor inoculation [2 (equivalent MMC) microgram/head per injection], the conjugate retarded tumor growth more effectively than free MMC and normal horse immunoglobulin conjugate.

Adolescent↗
PubMed1986

Preferential accumulation of 11C in human brain tumors after intravenous injection of 11C-1-pyruvate.

Regional cerebral turnover of 11C following intravenous injection of 11C-1-pyruvate was investigated in 12 patients with brain tumors. The positron emission tomography (PET) image taken at 10-15 min after the injection always demonstrated a high concentration of 11C in tumor, and thus visualized precise tumor contours. This phenomenon was not influenced qualitatively by the variation of blood flow in the tumor. Brain edema associated with the tumor was not visualized. We conclude that the localization of brain tumors would be well determined by the PET scan, using 11C-1-pyruvate.

Adult↗
PubMed1986

Difference of 14C turnovers in brain and in transplanted glioma after intravenous injection of 14C-1-pyruvate into rats.

Carbon 14 from 14C-1-pyruvate injected intravenously into glioma-transplanted rats was incorporated into various compounds in the brain and in the tumor. In the brain the majority of activity was found in CO2 (60%), and minor activities were found in alanine, lactate (15%), glutamate, and aspartate, with decreasing order, 5 min after injection. In the tumor, at 5 min, the largest activity was in lactate (56%), and lower activities were found in CO2 (24%), alanine, glutamate, and aspartate. The total 14C concentration in the tumor was twice that in the brain at 5 min and 15 min. The result was in accordance with the prediction that in brain, where the mitochondrial function is active, 14C-1-pyruvate will be oxidized completely into 14CO2, and that in tumor, where the mitochondrial function is insufficient, 14C-1-pyruvate will be converted only into 14C-lactate and prevent further degradation. It may be assumed that this difference in the turnover of 14C of 14C-1-pyruvate between brain and tumor could constitute a basis for the 'hot' visualization of human brain tumor using cyclotron-produced 11C-1-pyruvate and positron-emission tomography.

Animals↗
PubMed1986

Brain ischemia and infarction positively visualized by pyruvate-1-11C using positron-emission tomography.

We describe positron-emission tomography (PET) scintigraphic findings obtained using pyruvate-1-11C in eight patients with cerebral ischemic hypoxia or infarction. The extraction of 11C by brain tissue from blood after an i.v. injection of 11C-pyruvate was very rapid, being almost complete after a single circulatory passage. Most ischemic lesions were found to be more or less deficient with regard to 11C-extraction capacity. With time, however, the ratio of 11C in ischemic tissue to that in normal tissue was inverted, and the ischemic lesion appeared as a 'hot' area in the scintigram. Very old infarcts did not exhibit this phenomenon. These observations indicate the usefulness of an 11C-pyruvate PET scan for the diagnosis of therapeutically restorable brain damage.

Adult↗
PubMed1986

The role of adenosinergic, GABAergic and benzodiazepine systems in hyperemotionality and ulcer formation in stressed rats.

The effects of benzodiazepines, GABA and adenosine on distress-induced hyperemotionality and gastric lesion formation were investigated in rats. Hyperemotionality such as struggling, vocalization and defecation evoked immediately after immobilization stress were attenuated by diazepam, adenosine or adenosine plus diazepam. Conversely, pretreatment with these drugs produced rapid and potent exacerbation of gastric lesions observed after 12 h of stress. The potent adenosine A1-receptor agonist N6-cyclohexyl adenosine (CHA) markedly inhibited the distress-evoked hyperemotional behaviors and potentiated the ulceration. gamma-Aminobutyric acid (GABA), muscimol, a GABA receptor agonist, and aminooxyacetic acid (AOAA), a GABA deaminase inhibitor, attenuated both stress-induced hyperemotionality and ulceration. The inhibitory effects of diazepam and GABA on hyperemotionality were reversed, respectively, by Ro15-1788, a benzodiazepine receptor antagonist, and bicuculline, a GABA receptor antagonist. The stimulatory effect of CHA on stress ulceration was potentiated by bicuculline but was not affected by Ro15-1788 or by picrotoxin, a chloride channel inhibitor. These results suggest that the mechanism involved in gastric lesion formation induced by immobilization stress may be different from that in hyperemotional behavior, and that the activation of GABAergic neurons may act as a central modulating factor in the hyperemotionality and ulceration induced by immobilization stress.

Adenosine↗
PubMed1986

Rhodopsin and retinochrome in the retina of a marine gastropod, Conomulex luhuanus.

Photopigments in the conch retina were examined with special attention given to the photic vesicles characteristic of gastropod photoreceptors. Three different fractions of visual cell fragments were prepared from the retina: the MV-fraction containing the rhabdomal microvilli, and the PVH- and PVL-fractions containing the photic vesicles located in the visual cell body. Rhodopsin was found in the MV-fraction (lambda max = 474 nm), and yielded a photoequilibrium mixture with metarhodopsin (lambda max = 512 nm) on irradiation with blue light. Retinochrome was found in both of the PVH- and PVL-fractions (lambda max = approximately 510 nm), and was bleached into metaretinochrome by exposure to orange light, showing no marked shift of the absorption peak. Unlike the PVH-fraction, the PVL-fraction contains much aporetinochrome in addition to retinochrome, suggesting that the large mass of photic vesicles around the nucleus may serve as storage for retinal in retinochrome and for newly synthesized aporetinochrome. The total amount of retinochrome in the retina was several times higher than that of rhodopsin, distinguishing the gastropod eye from the cephalopod eye.

Animals↗
PubMed1986

Effects of acute and long-term treatments with thyrotropin-releasing hormone on locomotor activity and jumping behavior in mice.

The acute and chronic effects of thyrotropin-releasing hormone (TRH) on ambulation and, in combination with apomorphine, on jumping behavior were investigated in mice. A single administration of TRH (1-10 mg/kg SC) produced an initial hyperactivity in a dose-dependent manner. Following administration of TRH (1-10 mg/kg SC) for 21 successive days, the stimulatory effect on locomotion progressively increased. Haloperidol exerted a biphasic action on hyperlocomotion induced by acute and repeated TRH, i.e., stimulation at lower doses (0.01-0.02 mg/kg SC) and inhibition at higher doses (0.05-1 mg/kg SC). When TRH was administered in combination with low doses of apomorphine, locomotor activity was inhibited but jumping behavior occurred. The inhibitory effect of low doses of apomorphine on locomotion was shifted from doses of 0.1-0.25 mg/kg SC of apomorphine for acute TRH (10 mg/kg) to 0.25-0.35 mg/kg for repeated TRH (10 mg/kg), whereas the stimulatory effect of higher doses of apomorphine (0.5-1 mg/kg SC) on locomotion tended to decrease with repeated TRH. Jumping behavior induced by the combined treatment of TRH and apomorphine was proportional to the dose of TRH but exhibited an inverted-U response to the dose of apomorphine. Chronic TRH (10 mg/kg) in combination with apomorphine (0.1-1 mg/kg SC) also produced jumping behavior, but the dose-response curve for apomorphine was shifted to the right. The present results suggest that repeated treatment with TRH in mice produces hyperlocomotion, despite attenuation of both pre- and postsynaptic receptor activity, and that the inhibitory effect of repeated TRH on presynaptic receptors may be more potent than that on postsynaptic receptors.

Animals↗
PubMed1986

Fate of the capsular bag in endocapsular phacoemulsification and complete in-the-bag intraocular lens fixation.

We performed endocapsular phacoemulsification on 17 eyes of 15 patients between November 1984 and February 1985. Phacoemulsification was performed intracapsularly through a small incision in the anterior capsule. The inner wall of the bag was cleaned with the Cavitron handpiece. Posterior chamber intraocular lens implantation was performed completely in the bag. A clear capsular bag was present in 15 eyes with an average follow-up of six months. Central anterior lens capsule opacity occurred in two eyes. Sixteen eyes had visual acuity better than 20/40 and nine eyes had visual acuity better than 20/20. We have changed the name of this procedure from intracapsular to endocapsular phacoemulsification to prevent confusion.

Aged↗