Search PubMed⌕ Search

Biomedical subjects

T Kitayama

Publications and source records attributed to T Kitayama.

At least 37 records · Page 2Linked to original sources
PubMed1999

Sunyaev-Zeldovich Fluctuations from Spatial Correlations between Clusters of Galaxies.

We present angular power spectra of the cosmic microwave background radiation anisotropy due to fluctuations of the Sunyaev-Zeldovich (SZ) effect through clusters of galaxies. A contribution from the correlation among clusters, which has been neglected in previous analyses, is especially focused on. Employing the evolving linear bias factor based on the Press-Schechter formalism, we find that the clustering contribution amounts to 20%-30% of the Poissonian contribution at degree angular scales. If we exclude clusters in the local universe, it even exceeds the Poissonian noise and makes the dominant contribution to the angular power spectrum. As a concrete example, we demonstrate the subtraction of the ROSAT X-ray and Planck SZ flux-limited cluster samples. It indicates that we should include the clustering effect in the analysis of the SZ fluctuations. We further find that the degree scale spectra essentially depend upon the normalization of the density fluctuations, i.e., sigma8, and the gas mass fraction of the cluster, rather than the density parameter of the universe and details of cluster evolution models. Our results show that the SZ fluctuations at the degree scale will provide a possible measure of sigma8, while the arcminute spectra will provide a probe of the cluster evolution. In addition, the clustering spectrum will give us valuable information on the bias at high redshift, if we can detect it by removing X-ray or SZ luminous clusters.

Journal Article↗
PubMed1999

Sensitization by prolonged glutathione depletion of kainic acid to potentiate DNA binding of the nuclear transcription factor activator protein-1 in murine hippocampus.

In four of four mice intracerebroventricularly injected with the inhibitor of glutathione synthesis L-buthionine-[S,R]-sulfoximine (BSO) 2 days before, an intraperitoneal injection of kainic acid (KA) invariably led to marked potentiation of DNA binding activity of the nuclear transcription factor activator protein-I (AP1) in the hippocampus at a dose which was ineffective in animals previously injected with vehicle alone. However, KA failed to potentiate binding in animals injected with BSO 1 day before. The intracerebroventricular injection of BSO induced marked and prolonged depletion of a total glutathione content in murine hippocampus for 1-2 days after administration. These results suggest that prolonged depletion of endogenous glutathione for a period longer than 1 day may lead to sensitization of KA signals to potentiate AP1 DNA binding in cell nuclei and thereby modulate de novo synthesis of particular proteins at the level of gene transcription in murine hippocampus.

Animals↗
PubMed1999

Differential inhibition by ferrous ions of [3H]MK-801 binding to native N-methyl-D-aspartate channel in neonatal and adult rat brains.

In vitro addition or pretreatment with >/=1 microM ferrous chloride markedly inhibited in a concentration-dependent manner [3H]dizocilpine (MK-801) binding to an open ion channel associated with the N-methyl-D-aspartate (NMDA) receptor in rat brain synaptic membranes. The addition of NMDA agonists invariably attenuated the inhibition of [3H]MK-801 binding in hippocampal synaptic membranes previously treated with ferrous chloride, without significantly affecting that in cerebellar synaptic membranes. In the absence of spermidine, ferrous chloride was more potent in inhibiting binding in the cerebral cortex and hippocampus in adult rats than in those in rats at 3 days after birth, while in the striatum [3H]MK-801 binding was 10 times more sensitive to inhibition by added ferrous chloride in neonatal rats than in adult rats. Addition of spermidine significantly attenuated the potency of ferrous chloride to inhibit binding in the cerebral cortex of adult rats, with facilitation of the inhibition in newborn rats. Moreover, spermidine significantly reduced the inhibitory potency of ferrous chloride in neonatal rat striatum, without markedly affecting that in adult rat striatum. These results suggest that ferrous ions may interfere with opening processes of the native NMDA channel through molecular mechanisms peculiar to neuronal development in a manner associated with the polyamine recognition domain.

Animals↗
PubMed1999

Sustained potentiation of AP1 DNA binding is not always associated with neuronal death following systemic administration of kainic acid in murine hippocampus.

Mice were intraperitoneally injected with kainic acid (KA), followed by dissection of frozen coronal sections and subsequent punching out of the pyramidal and granular cell layers in the hippocampus under a binocular microscope. Systemic administration of KA resulted in marked and sustained potentiation of binding of a radiolabeled double stranded oligonucleotide probe for the nuclear transcription factor activator protein-1 (AP1) in the pyramidal cell layers of the CA1 and CA3 subfields and the granule cell layers of the dentate gyrus 2-18 h later. Morphological evaluation using cresyl violet revealed marked losses of neuronal layers in the pyramidal CA1 and CA3 subfields, but not in the granular dentate gyrus, within 6 weeks after administration. Supershift analysis using antibodies against different Jun and Fos family members differentiated between AP1 DNA binding in hippocampal nuclear extracts obtained 2 and 18 h after the administration of KA. These results suggest that neuronal death may not always follow modulation of de novo synthesis of particular proteins through sustained potentiation of AP1 DNA binding which involves expression of different Jun and Fos family members in response to systemic administration of KA in murine hippocampus.

Animals↗
PubMed1999

Predominant expression of nuclear activator protein-1 complex with DNA binding activity following systemic administration of N-methyl-D-aspartate in dentate granule cells of murine hippocampus.

The systemic administration of N-methyl-D-aspartate (100 mg/kg, i.p.) resulted in preferential but transient expression of the transcription factor activator protein-1 in the granule cell layers of the dentate gyrus in the murine hippocampus by maximally 700% 1 h later, without markedly affecting that in the pyramidal cell layers of the CA1 and CA3 subfields for 4 h. The potentiation was completely prevented by prior administration of the N-methyl-D-aspartate channel blocker dizocilpine at 10 mglkg. By contrast, kainate (40 mg/kg, i.p.) potentiated activator protein-1 DNA binding in adjacent areas around the pyramidal and granule cell layers, in addition to potentiating that in neuronal cell layers of the CA1 and CA3 subfields and the dentate gyrus. Light microscopic analysis revealed that kainate, but not N-methyl-D-aspartate, induced marked losses of the pyramidal cells in the CAI and CA3 subfields, without affecting the dentate granule cells, for 14 days after administration. Limited proteolysis by V8 protease and supershift, as well as immunoblotting assays using antibodies against c-Fos and c-Jun, invariably gave support for differential expression by N-methyl-D-aspartate and kainate of the activator protein-1 complex consisting of different partner proteins. Moreover, two-dimensional electrophoresis followed by immunoblotting analysis revealed the expression of several nuclear proteins immunoreactive with the anti-c-Fos antibody at molecular weights and isoelectric points clearly different from those of c-Fos itself in response to kainate, but not N-methyl-D-aspartate, in the hippocampus. These results suggest that in vivo N-methyl-D-aspartate signals are predominantly transduced into cell nuclei to express activator protein-1 complex through molecular mechanisms different from those for kainate signals in the granule cells of the dentate gyrus in the murine hippocampus.

Animals↗
PubMed1999

Possible involvement of membrane phospholipids in inhibition by ferrous ions of [3H]MK-801 binding to the native N-methyl-D-aspartate channel in rat brain.

Prior treatment with ferrous chloride led to the marked inhibition of [3H](+)-5-methyl-10, 11-dihydro-5H-dibenzo[a, d]cyclohepten-5, 10-imine (MK-801) binding to an open ion channel associated with the N-methyl-D-aspartate (NMDA) receptor in a concentration-dependent manner at concentrations of higher than 1 microM in rat brain synaptic membranes. Both phospholipases A2 and C significantly prevented the inhibition when treated before the treatment with ferrous chloride, while neither superoxide dismutase nor alpha-tocopherol affected the inhibition even when treated simultaneously with ferrous chloride. Of various saturated and unsaturated fatty acids, moreover, both oleic and arachidonic acids exclusively decreased the potency of ferrous chloride to inhibit binding when membranes were treated with fatty acids, followed by a second treatment with ferrous chloride. These results suggest that membrane phospholipids may be, at least in part, responsible for the interference by ferrous ions in the opening processes of the native NMDA channel through molecular mechanisms associated with the release of unsaturated fatty acids in rat brain.

Animals↗
PubMed1995

[Vasodilating effects of NY-008 in ring preparation of rat aorta].

Vasodilating effects of NY-008 were compared to those of verapamil in isolated rat aorta. NY-008 at the dose of 3 x 10(-5) M relaxed 10-70 mM potassium chloride (KCl)-induced contraction. NY-008 relaxed preparations precontracted with 60 mM KCl concentration-dependently with an IC50 of (6.17 +/- 1.75) x 10(-6) M, and those precontracted with norepinephrine (NE) (10(-6) M) concentration-dependently, maximally by 90.0 +/- 2.86%, with an IC50 of (2.06 +/- 0.38) x 10(-5) M. At 10(-8)-3 x 10(-6) M, verapamil relaxed preparations precontracted with NE (10(-6) M) concentration-dependently, maximally by 55.9 +/- 5.56%. At 3 x 10(-5) M and 10(-4) M, NY-008 relaxed (10(-6) M)-induced phasic contractions in a Ca(2+)-free 1 mM EGTA-containing buffer, by 22.4 +/- 3.69% and 35.4 +/- 5.74%, respectively. In contrast, 3 x 10(-7) M verapamil did not. NY-008 concentration-dependently decreased the maximal responses to calcium chloride (CaCl2) in 60 mM KCl-depolarized preparations, and it shifted the ED50 values of CaCl2 to the right, whereas verapamil shifted the ED50 values of CaCl2 to the right without decreasing the maximal responses to CaCl2. At 10(-5)-3 x 10(-4) M, NY-008 concentration-dependently relaxed preparations precontracted with prostaglandin F2 alpha (10(-5) M) in a Ca(2+)-free, 0.5 mM EGTA-containing buffer, whereas 10(-7)-10(-5) M verapamil did not. These results suggest that NY-008 antagonized Ca2+ and decreased the Ca(2+)-sensitivity of contractile elements or inhibited contractile proteins in rat aorta.

Animals↗
PubMed1993

[Measurement of serum insulin-like growth factor-I by enzyme-linked immunosorbent assay in uremic patients and uninephrectomized patients].

Using the enzyme-linked immunosorbent assay (ELISA), we determined the serum insulin-like growth factor-I (IGF-I) levels in the patients on hemodialysis and patients who had undergone unilateral nephrectomy. This ELISA system was able to detect IGF-I over the range of 1.6 to 50 ng/ml. The serum IGF-I levels in 45 male and 34 female dialytic patients (12.7 +/- 7.4 ng/ml and 29.0 +/- 15.9 ng/ml) were significantly low (P < 0.01) compared with 50 normal adult men and 53 normal adult women (34.9 +/- 11.4 ng/ml and 44.5 +/- 20.5 ng/ml). The serum IGF-I level tended to decrease with aging. Furthermore, we determined the IGF-I levels in 5 donors for living-related kidney transplantation and 7 patients with upper urinary tract tumor before and after unilateral nephrectomy in order to examine the endocrine effect of IGF-I. The IGF-I level in the donors decreased significantly (P < 0.05) on the fifth postoperative day and returned to the preoperative level on the 14th postoperative day. The IGF-I level in the tumor patients decreased significantly on the fifth postoperative day (P < 0.01) and remained at a low level up to the 14th postoperative day. However, the changes in the postoperative IGF-I level in the patients who had undergone surgical operations other than unilateral nephrectomy showed patterns similar to those in the kidney transplantation donors. These findings suggest that the postoperative fall in the serum IGF-I is affected by either fasting after surgery or consumption due to healing of the operative wound.

Adult↗
PubMed1993

[The efficacy and safety of priming principle with pipecuronium].

The authors evaluated the cumulative dose response of pipecuronium under isoflurane anesthesia, and the efficacy as well as safety of priming principle in 52 patients who underwent elective surgery. The ED95 of pipecuronium was 34.24 +/- 5.34 micrograms.kg-1 in 10 patients and 70 micrograms.kg-1 (not equal to ED95 x 2) was used as total dose (T). The 42 patients were divided to receive either no prime or, 5%, 10%, 15% or 20% of T as a prime followed 5 minutes later by the remaining (intubating) dose. The muscle weakness in awake patients was determined after the priming doses by examining several clinical symptoms and by evaluating the effect of intubating doses on neuromuscular blockade. The priming using 10% of T provided rapid intubating conditions. However, the priming dose caused a significant incidence of symptoms of muscle weakness. Therefore, the priming principle should be used with caution.

Adult↗
PubMed1990

[A case of secondary bladder tumor the origin (gastric cancer) of which could not be identified before autopsy].

Primary bladder tumor is the most frequent malignant tumor in the field of urology, whereas the incidence of secondary bladder tumor from a distant organ is quite rare. We report here a 21-year-old female patient with metastatic bladder tumor from gastric cancer. She came to our hospital with a complaint of only bladder irritability. Cystoscopical and cytological examinations revealed rhabdomyosarcoma of the bladder. She did not respond to radiation therapy and combined chemotherapy, consisting of actinomycin D, vincristine and cyclophosphamide, and died 91 days after admission. Autopsy revealed a primary tumor of poorly differentiated scirrhus carcinoma of the stomach. Thus this was a quite rare case of metastatic bladder carcinoma characterized by bladder irritability without gastrointestinal symptoms.

Adenocarcinoma, Scirrhous↗
PubMed1990

[A case of primary localized amyloidosis of the urinary bladder].

A case of primary localized amyloidosis is reported. The patient was a 73-year-old female who suffered from miction pain and consulted our department. There was a 1.5 x 1.5 cm slightly red, nonpapillary tumor around the right ureteral orifice in cystoscopy. The diagnosis was amyloidosis with cystitis hemorrhagica histopathologically. After the treatment with antibiotics for about one month there were no symptoms and no tumors in the urinary bladder cystoscopically. The clinical course was relatively good. The treatment varies from transurethral resection to total cystectomy with urinary diversion. This case was cured by non-operative treatment, but close follow-up of the patient is necessary because of the frequency of multiple recurrence.

Aged↗
PubMed1990

[A case of renal subcapsular hematoma caused by paravertebral muscular injection of local anesthetics].

We report a case of left renal subcapsular hematoma caused by paravertebral muscular injection of acetylcholine chloride for the treatment of lumbago in a 42-year-old man. Since the patient suffered from left lumbago after paravertebral muscular injection, he consulted us. Excretory pyelography showed a left poor visualizing kidney and computed tomography demonstrated left renal subcapsular hematoma. Conservative treatment was done. After two weeks, drip intravenous pyelogram was normal and after four months computerized tomographic scan demonstrated no renal subcapsular hematoma. The main causes of renal subcapsular hematoma are renal injury, nephritis, renal tumor and renal biopsy. Renal subcapsular hematoma caused by paravertebral muscular injection is rare and three cases of hematoma including this case have been reported in the Japanese literature.

Acetylcholine↗
PubMed1987

Spontaneous regression of an intrarenal arteriovenous malformation.

We report a case of spontaneous regression of a right intrarenal arteriovenous malformation 6 months after initial examination without surgical intervention, arterial embolization or radiotherapy. The patient presented with massive hematuria from the right kidney, which disappeared completely after spontaneous regression.

Arteriovenous Malformations↗
PubMed1987

Inhibitory effect of beauvericin on a high K+-induced tonic contraction in guinea-pig taenia coli.

An inhibitory effect of beauvericin, a cyclodepsipeptide, on a high K+-induced contraction in guinea-pig taenia coli was compared with those of verapamil, an organic Ca2+ antagonist, and monensin, an inhibitor of mitochondrial respiration. Beauvericin (10(-5) M), verapamil (5 x 10(-7) M) or monensin (10(-6) M) markedly inhibited the tonic contraction, while these drugs showed less effect on the phasic contraction. Beauvericin at a lower concentration (10(-6) M) competitively inhibited the Ca2+-induced contraction in depolarized muscle, whereas higher concentrations (3 x 10(-6) or 10(-5) M) non-competitively inhibited this contraction. Verapamil (10(-8)-5 x 10(-7) M) competitively inhibited and monensin at a low concentration (10(-7) M) non-competitively inhibited this contraction. A contraction induced by 0.5 mM Ca2+ was inhibited by beauvericin with an IC50 (concentration needed for 50% inhibition) of 2.8 x 10(-7) M, verapamil with an IC50 of 2.9 x 10(-8) M, and nifedipine with an IC50 of 1.8 x 10(-9) M. 10(-6) M CGP 28392, a Ca2+ channel facilitator, increased the IC50 of beauvericin, verapamil or nifedipine. Although the inhibitory effect of monensin (10(-7)-10(-6) M) on the high K+-induced contraction was reduced under hypoxia, the effects of beauvericin (10(-7)-10(-5) M) and verapamil (10(-8)-10(-7) M) were not modified. Beauvericin (10(-5) M) changed neither the intracellular Na+ and K+ contents of the depolarized muscle nor the Ca2+-induced contraction in the chemically skinned taenia coli.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗