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T Itoh

Publications and source records attributed to T Itoh.

At least 19 recordsLinked to original sources
PubMed1992

Phosphorescence and optically detected magnetic resonance measurements of the 2'AMP and 2'GMP complexes of a mutant ribonuclease T1 (Y45W) in solution: correlation with X-ray crystal structures.

Phosphorescence and ODMR measurements have been made on ribonuclease T1 (RNase T1), the mutated enzyme RNase T1 (Y45W), and their complexes with 2'GMP and 2'AMP. It is not possible to observe the phosphorescence of Trp45 in RNase T1 (Y45W). Only that of the naturally occurring Trp59 is seen. The binding of 2'GMP to wild-type RNase T1 produces only a minor red shift in the phosphorescence and no change in the ODMR spectrum of Trp59. However, a new tryptophan 0,0-band is found 8.2 nm to the red of the Trp59 0,0-band in the 2'GMP complex of the mutated RNase T1 (Y45W). Wavelength-selected ODMR measurements reveal that the red-shifted emission induced by 2'GMP binding, assigned to Trp45, occurs from a residue with significantly different zero-field splittings than those of Trp59, a buried residue subject to local polar interactions. The phosphorescence red shift and the zero-field splitting parameters demonstrate that Trp45 is located in a polarizable environment in the 2'GMP complex. In contrast with 2'GMP, binding of 2'AMP to RNase T1 (Y45W) induces no observable phosphorescence emission from Trp45, but leads only to a minor red shift in the phosphorescence origin of Trp59 in both the mutated and wild-type enzyme. The lack of resolved phosphorescence emission from Trp45 in RNase T1 (Y45W) implies that the emission of this residue is quenched in the uncomplexed enzyme. We conclude that local conformational changes that occur upon binding 2'GMP remove quenching residues from the vicinity of Trp45, restoring its luminescence.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Monophosphate↗
PubMed1992

Three-dimensional structure of a mutant ribonuclease T1 (Y45W) complexed with non-cognizable ribonucleotide, 2'AMP, and its comparison with a specific complex with 2'GMP.

The crystal structure of a mutant ribonuclease T1 (Y45W) complexed with a non-cognizable ribonucleotide, 2'AMP, has been determined and refined to an R-factor of 0.159 using X-ray diffraction data at 1.7 A resolution. A specific complex of the enzyme with 2'GMP was also determined and refined to an R-factor of 0.173 at 1.9 A resolution. The adenine base of 2'AMP was found at a base-binding site that is far apart from the guanine recognition site, where the guanine base of 2'GMP binds. The binding of the adenine base is mediated by a single hydrogen bond and stacking interaction of the base with the imidazole ring of His92. The mode of stacking of the adenine base with His92 is similar to the stacking of the guanine base observed in complexes of ribonuclease T1 with guanylyl-2',5'-guanosine, reported by Koepke et al., and two guanosine bases, reported by Lenz et al., and in the complex of barnase with d(GpC), reported by Baudet & Janin. These observations suggest that the site is non-specific for base binding. The phosphate group of 2'AMP is tightly locked at the catalytic site with seven hydrogen bonds to the enzyme in a similar manner to that of 2'GMP. In addition, two hydrogen bonds are formed between the sugar moiety of 2'AMP and the enzyme. The 2'AMP molecule adopts the anti conformation of the glycosidic bond and C-3'-exo sugar pucker, whereas 2'GMP is in the syn conformation with C-3'-endo-C'-2'-exo pucker. The mutation enhances the binding of 2'GMP with conformational changes of the sugar ring and displacement of the phosphate group towards the interior of the catalytic site from the corresponding position in the wild-type enzyme complex. Comparison of two crystal structures obtained provides a solution to the problem that non-cognizable nucleotides exhibit unexpectedly strong binding to the enzyme, compared with high specificity in nucleolytic activity. The results indicate that the discrimination of the guanine base from the other nucleotide bases at the guanine recognition site is more effective than that estimated from nucleotide-binding experiments so far.

Adenosine Monophosphate↗
PubMed1992

Long-lasting enhancement of metabotropic excitatory amino acid receptor-mediated polyphosphoinositide hydrolysis in the amygdala/pyriform cortex of deep prepiriform cortical kindled rats.

We have previously demonstrated that ibotenate (IBO)-stimulated polyphosphoinositide (PPI) hydrolysis is increased for a long period in the amygdala/pyriform cortex (AM/PC) of amygdala (AM)- and hippocampal (HIPP)-kindled rats. This finding indicates that enhanced function of the PPI-coupled excitatory amino acid (EAA) receptor may be associated with the long-lasting seizure susceptibility of kindling. The present study further examined PPI hydrolysis induced by trans-ACPD, a selective agonist of the metabotropic EAA receptor, as well as by IBO in brain slices of rats kindled from the deep prepiriform cortex (DPC). IBO-stimulated accumulation of [3H]inositol monophosphate ([3H]InsP) was significantly increased in the AM/PC by 162 (P less than 0.0001), 130 (P less than 0.005) and 81% (P less than 0.03) at 24 h, 7 days and 28 days, respectively, after the last kindled seizure, whereas it was increased significantly only at 24 h after the last seizure in the HIPP and did not change at any time in the limbic forebrain (LFB). The IBO-stimulated accumulation of [3H]InsP was significantly increased by 55% (P less than 0.01) in the AM/PC of partially kindled rats reaching an average stage of 3.7, but not in the AM/PC of those remaining at stage 1, 7 days after the last kindled seizure. Trans-ACPD-stimulated PPI hydrolysis was significantly increased in the AM/PC of DPC-kindled rats by 65 (P less than 0.05) and 45% (P less than 0.005) at 7 and 28 days, respectively, after the last kindled seizure. Cis-ACPD-stimulated PPI hydrolysis was also significantly increased in the AM/PC of DPC-kindled rats by 45 (P less than 0.03) and 30% (P less than 0.04) at 7 and 28 days, respectively, after the last seizure. There was no increase in trans-ACPD- or cis-ACPD-stimulated PPI hydrolysis in the HIPP or LFB. These results further confirm our previous studies showing that the metabotropic EAA receptor-stimulated PPI hydrolysis exhibited a long-lasting increase in the AM/PC irrespective of the primary stimulation site for kindling.

Amygdala↗
PubMed1992

Tumour angiogenesis in prostatic carcinoma with and without bone marrow metastasis: a morphometric study.

One hundred and one cases of clinical prostatic carcinoma (PCa), primary site, were analysed to define the interrelationship between tumour angiogenesis, histological grade, and bone marrow metastasis. Tumour angiogenesis was determined by the blood capillary density ratio (BCDR; a/b), defined as the ratio between the area of the blood capillaries (a) and the area of the tumour (b). The BCDR was evaluated by a colour image analysis system employing a computerized morphometrical method. A total of 43 cases of PCa with bone marrow metastasis (stage D2) and 58 cases of PCa without metastasis (stage B, C) were utilized. The prostatic carcinomas were classified into three groups (low, intermediate, and high) using Gleason's grading system. The BCDR of the primary PCa with bone marrow metastasis was similar in each of the three histologically graded scores. On the other hand, in the cases of PCa without metastasis, the BCDR of high score PCa was higher than those of the low and intermediate score PCa (U-test; P < 0.001). The BCDR of the high score PCa without metastasis was similar to that of the PCa with bone marrow metastasis. The BCDR may provide help in predicting tumour progression with regard to bone marrow metastasis of PCa with low and intermediate Gleason's scores.

Bone Marrow↗
PubMed1992

Acinar cell carcinoma of the pancreas with elevated serum alpha-fetoprotein levels: a case report and a review of 28 cases reported in Japan.

A 60-year-old male with elevated serum AFP levels is reported. Other tumor markers apart from AFP were normal. Serum AFP did not bind to Con A or Lentil-lectin by affinity chromatography. Abdominal ultrasonography, computed tomography and endoscopic retrograded cholangiopancreatography demonstrated a tumor extending from the body to the tail of the pancreas. The tumor was strongly suggested to be an acinar cell carcinoma of the pancreas, based on the histological findings of the resected specimen. The peroxidase-antiperoxidase method showed cancer cells to be positive for AFP. In Japan, only 27 cases of pancreatic cancer with elevated serum AFP level have been reported. This is the first Japanese case of pancreatic cancer in which the binding of serum AFP to lectins was investigated.

Carcinoma↗
PubMed1992

One-stage operation for synchronous primary cancers of the lung and the trachea.

A rare combination of synchronous primary adenocarcinoma of the right upper lobe of the lung and adenoid cystic carcinoma of the subglottic trachea was simultaneously managed by lobectomy with lymph node dissection and sleeve resection of the upper trachea through median sternotomy and cervical collar incisions. This combined approach should be a perfectly acceptable one for synchronous tumors of the proximal trachea and of the right upper and middle lobes and left upper lobe of the lung.

Adenocarcinoma↗
PubMed1992

Synaptosomal membrane fluidity, lipid peroxidation and superoxide dismutase activity in the brain of amygdala-kindled rats.

Synaptosomal membrane fluidity, lipid peroxide (LPO) and cytosolic superoxide dismutase (SOD) activity were examined in various brain regions (amygdala, hippocampus, striatum and frontal cortex) of amygdala-kindled rats. At 24 h after the last seizure, a significant increase of membrane fluidity was observed in all the regions examined, whereas the LPO level was significantly decreased in the four regions with enhanced activity of cytosolic SOD. At 7 days after the last seizure, membrane fluidity was decreased only in the hippocampus. At 6 weeks after the last seizure, there were no changes in membrane fluidity between control and kindled rats. These results suggest that membrane fluidity and lipid peroxidation are modulated transiently by a kindled seizure, but not at a steady state of kindling with enduring seizure susceptibility.

Amygdala↗
PubMed1992

Characteristic features of noradrenaline-induced Ca2+ mobilization and tension in arterial smooth muscle of the rabbit.

1. Effects of noradrenaline (NAd) on changes in cellular Ca2+ concentration ([Ca2+]i) and tension were investigated, and these effects were compared with those evoked by 128 mM K+ or caffeine in intact smooth muscle strips or by inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) or caffeine in beta-escin-treated chemically skinned smooth muscle strips of the rabbit mesenteric artery. 2. In physiological solution containing 2.6 mM Ca2+, application of 128 mM K+ or 10 microM NAd produced a phasic, followed by a tonic increase in [Ca2+]i and tension. NAd (10 microM) produced a larger tonic tension than did 128 mM K+ but a smaller increase in [Ca2+]i. When the [Ca2+]i-tension relationship was observed in ionomycin- and 128 mM K(+)-treated muscle strips, 10 microM NAs shifted the relationship to the left and enhanced the maximum amplitude of contraction. These results suggest that NAd increases the sensitivity of contractile proteins to Ca2+ in smooth muscle of the rabbit mesenteric artery. 3. Noradrenaline (10 microM) or caffeine (10 mM), but not 128 mM K+, produced a phasic increase in both [Ca2+]i and tension in Ca(2+)-free solution containing 2 mM EGTA. When 10 mM caffeine had been applied in Ca(2+)-free solution, subsequent application of 10 microM NAd did not increase [Ca2+]i. By contrast, when 10 microM NAd had been applied in Ca(2+)-free solution, subsequent application of 10 mM caffeine still increased [Ca2+]i. Ryanodine (50 microM) abolished the increase in [Ca2+]i induced by 10 mM caffeine or 10 microM NAd in intact and in skinned smooth muscle strips. These results suggest that NAd releases Ca2+ from the ryanodine-sensitive Ca2+ storage sites. 4. Noradrenaline (10 microM) synthesized Ins(1,4,5)P3 in Ca(2+)-free solution in intact smooth muscle strips. Following application of 10 microM NAd, a relatively long time lag (around 1 s) was always observed before the initiation of the increase in [Ca2+]i whether in the presence or absence of Ca2+. The maximum rate of rise of [Ca2+]i induced by 10 mM caffeine was much larger than that induced by 10 microM NAd in Ca(2+)-containing or Ca(2+)-free solution (containing 2 mM EGTA). Both [Ca2+]i and tension reached their peak in a shorter time with caffeine (10 mM) than with 10 microM NAd. In Beta-escin-treated skinned smooth muscle strips, 20 microM Ins(1,4,5)P3 10 mM caffeine or 10 microM NAd increased Ca2+ in Ca(2+)-free solution following brief application of 0.3 microM Ca2+.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Mechanisms of vasodilation induced by NKH477, a water-soluble forskolin derivative, in smooth muscle of the porcine coronary artery.

To study the mechanism of vasodilation induced by 6-(3-dimethylaminopropionyl) forskolin (NKH477), a water-soluble forskolin derivative, its effects on the acetylcholine (ACh)-induced contraction of muscle strips of porcine coronary artery were examined. [Ca2+]i, isometric force, and cellular concentrations of cAMP and inositol 1,4,5-trisphosphate were measured. NKH477 (0.1-1.0 microM), isoproterenol (0.01-0.1 microM), or forskolin (0.1-1.0 microM) increased cAMP and attenuated the contraction induced by 128 mM K+ or 10 microM ACh in a concentration-dependent manner. These agents, at concentrations up to 0.3 microM, did not change the amount of cGMP. NKH477 (0.1 microM) attenuated the contraction induced by 128 mM K+ without corresponding changes in the evoked [Ca2+]i responses. ACh (10 microM) produced a large phasic increase followed by a small tonic increase in [Ca2+]i and produced a sustained contraction. The ACh-induced phasic increase in [Ca2+]i, but not the tonic increase, disappeared after application of 0.1 microM ionomycin. NKH477 (0.1 microM) attenuated both the increase in [Ca2+]i and the force induced by 10 microM ACh in muscle strips that were not treated with ionomycin and inhibited the ACh-induced contraction without corresponding changes in [Ca2+]i in ionomycin-treated muscle strips. These results suggest that NKH477 inhibits ACh-induced Ca2+ mobilization through its action on ionomycin-sensitive storage sites. In ionomycin-treated and 128 mM K(+)-treated muscle strips, 0.1 microM NKH477 shifted the [Ca2+]i-force relation to the right in the presence or absence of 10 microM ACh. In beta-escin-skinned smooth muscle strips, 0.1 microM NKH477 shifted the pCa-force relation to the right but had no effects on Ca(2+)-independent contraction. We conclude that in smooth muscle of porcine coronary artery, NKH477 inhibits ACh-induced contraction by both attenuating ACh-induced Ca2+ mobilization and reducing the sensitivity of the contractile machinery to Ca2+, possibly by activating cAMP-dependent mechanisms.

Acetylcholine↗
PubMed1992

Increased interleukin-6 activity in cardiac myxoma with mediastinal lymphadenopathy.

We report a case of cardiac myxoma with mediastinal lymphadenopathy which seems to be a very rare feature. Laboratory examination revealed high level of interleukin-6 (IL-6) activity in serum. Interestingly, after removal of cardiac myxoma, mediastinal lymphadenopathy disappeared on the chest CT and the level of serum IL-6 was decreased. These findings suggest that IL-6 which was probably derived from myxoma, may have played an important role in the development of lymphadenopathy.

Female↗
PubMed1992

Enhanced expression of type 2C protein phosphatase gene during myogenic differentiation of C3H10T1/2 cells.

Type 2C phosphatase is one of the four major protein serine.threonine phosphatases (types 1, 2A, 2B and 2C). The mRNA level of the enzyme protein was 11.5 times higher in mouse skeletal muscle than in undifferentiated mesenchymal cells (C3H10T1/2). The mRNA level was enhanced 4.2-fold in accordance with the differentiation of C3H10T1/2 cells into myoblasts induced by transfection with a MyoD1 expression vector, and this high level was maintained in terminally differentiated myotubes. Furthermore, type 2C phosphatase activity in both myoblast and myotube fractions was slightly higher than in control C3H10T1/2 cells. These results indicate that the expression of type 2C phosphatase gene is enhanced during the course of myogenic differentiation.

Animals↗
PubMed1992

[Pulmonary function and exercise tolerance in patients treated with bone marrow transplantation (BMT)].

We assessed pulmonary function and exercise tolerance in 10 BMT patients. Their underlying disorders were as follows; chronic myeloid leukemia 5 cases, acute lymphoblastic leukemia 2 cases, aplastic anemia, acute myeloid leukemia and non-Hodgkin's lymphoma one case each. Their mean age was 26 +/- 9 years old. When the patients were healthy and free of serious complications and anemia, arterial blood gas examination, pulmonary function tests and incremental treadmill exercise test were examined repeatedly. Although %VC and FEV1.0% kept within normal range, PaO2 at rest, %DLCO, VO2max, VO2max/kg and O2-pulsemax remained low at one year after BMT. There were significant correlations between VO2max and O2-pulsemax [r = 0.955 (p < 0.001)], %VC [r = 0.758 (p < 0.02)], VE/VO2max [r = -0.749 (p < 0.02)] and delta SaO2/VO2/kg [r = -0.731 (p < 0.02)], suggesting that exercise intolerance in BMT patients may be based on both cardiac and gas exchange abnormalities. To evaluate cardiac dysfunction, we compared exercise parameters obtained at an exercise level of 75% predicted heart rate max in five age-matched normal subjects to those in six BMT patients who did not demonstrate desaturation during exercise. As a result, the mean values of VO2max/kg and O2-pulse/m2 in BMT patients were significantly lower than those in normal subjects, suggesting that cardiac dysfunction may be due to insufficiency of stroke volume during exercise. It is concluded that exercise intolerance in BMT patients may be mainly due to cardiac dysfunction.

Adolescent↗
PubMed1992

Quantitative ultrasound diagnosis of endometrial cysts.

We measured the ultrasonic frequency dependent attenuation of ovarian cysts using the spectral difference method to find the difference in the characteristics of attenuation of the endometrial cyst and other ovarian cysts. We investigated an analytical method to measure the ultrasonic frequency dependent attenuation of ovarian cysts and we called this method the boundary echo spectrum method. The endometrial cyst had an attenuation slope of 0.67 +/- 0.27 dB/cm/MHz, and attenuation value was 1.85 +/- 1.27 dB/cm, and it had significantly higher attenuation slope and attenuation value compared with those of serous cystadenoma and mucinous cystadenoma, but no significant difference compared with those of dermoid cyst (fat component). Compared with attenuation slope and attenuation value, attenuation slope is superior because of smaller standard deviation and better linearity between water immersion and transabdominal method.

Adenoma↗
PubMed1992

[A case of small cell lung cancer with Waldenstrom's macroglobulinemia].

Waldenstrom's Macroglobulinemia is characterized by a proliferation of cells of the reticuloendothelial system associated with a monoclonal increase in serum levels of gamma globulins of immunoglobulin M class. We report a case of lung cancer with Waldenstrom's macroglobulinemia. A 68-year-old man was admitted to our hospital for abnormal mass shadow on chest X-P during chemotherapy for macroglobulinemia. Pathological diagnosis was small cell carcinoma by transbronchial lung biopsy. Right middle and lower lobectomy with mediastinal lymph nodes dissection were performed. Postoperative staging was stage II (t1n1m0). Chemotherapy for the lung cancer and plasmapheresis for hyperviscosity syndrome were carried out, after surgical treatment. This patient has been followed for three years and has no evidences of recurrence of the lung cancer.

Aged↗
PubMed1979

Isolation and characterization of twenty-three ribosomal proteins from large subunits of yeast.

The proteins of large ribosomal subunits from Saccharomyces cerevisiae were separated into 25 fractions by chromatography on columns of carboxymethylcellulose (CMC). Twenty-three proteins were then purified from the 12 CMC fractions by filtration through Sephadex G-75, Sephadex G-100, and Sephacryl S-200, and/or by phosphocellulose column chromatography. The isolated proteins are YP 1, YP 2, YP 9, YP 11, YP 13', YP 16, YP 18, YP 26, YP 39, YP 41, YP 42, YP 42', YP 44, YP 45, YP 47', YP 52a, YP 53, YP 55, YP 59, YP 62, YP 68, YP A1, and YP A2. The molecular weight and amino acid composition of these proteins are presented.

Amino Acids↗
PubMed1979

Establishment of an epithelial cell line from rat thymus.

A cell line (IT-26R21), composed only of epithelial cells, was established from normal rat thymus. Thymuses were treated with both collagenase and trypsin. Four months after the initiation of cultures, epithelial cells in packed colonies formed a monolayer and no other cells were found in cultures. Thereafter, epithelial cells have been subcultured with trypsin and EDTA, and are currently at the 30th subculture. Based upon the fine structure of the thymus in vivo, IT-26R21 cells were identified as epithelial cells from the thymus, because of their mosaic-like arrangement, desmosomes and tonofilaments. Other features also supported their origin and identity.

Animals↗
PubMed1979

Differential sensitivity of functional subsets of T cells to the cytotoxicity of natural T-lymphocytotoxic autoantibody of systemic lupus erythematosus.

A naturally occurring T-lymphocytotoxic autoantibody (Hu-NTA) in serum from a patient with systemic lupus erythematosus (SLE) showed a differential cytotoxic effect on functionally different T cell subsets as did natural thymocytotoxic autoantibody (NTA) of NZB mice. When the normal peripheral blood lymphocytes were treated, in the presence of complement, with Hu-NTA at a dilution that eliminated 25 to 30% of Hu-NTA-sensitive T cells, there was a marked reduction or a total depletion in the ability of resultant cells to show Con A-activated suppression on the proliferative response of responder cells in mixed lymphocyte reaction. The treatment of PBL in the same manner also resulted in a marked reduction in its responsiveness to Con A and PHA. However, the responder cells to allogeneic stimulator cells in MLR were found to be much more resistant to the cytotoxicity of Hu-NTA than other functional T cell subsets tested. These results suggest that Hu-NTA is responsible for the selective loss of certain functional T cell subsets including suppressor T cells in patients with SLE.

Antilymphocyte Serum↗