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T Kitagawa

Publications and source records attributed to T Kitagawa.

At least 127 records · Page 7Linked to original sources
PubMed1998

Time-resolved resonance Raman investigation of oxygen reduction mechanism of bovine cytochrome c oxidase.

Six oxygen-associated resonance Raman bands were identified for intermediates in the reaction of bovine cytochrome c oxidase with O2 at room temperature. The primary intermediate, corresponding to Compound A of cryogenic measurements, is an O2 adduct of heme a3 and its isotope frequency shifts for 16O18O have established that the binding is of an end-on type. This is followed by two oxoheme intermediates, and the final intermediate appearing around 3 ms is the Fe-OH heme. The reaction rate between the two oxoheme intermediates is significantly slower in D2O than in H2O, suggesting that the electron transfer is regulated by proton translocations at this step. It is noted that the reaction intermediates of oxidized enzyme with hydrogen peroxide yield the same three sets of oxygen isotope-sensitive bands as those of oxoheme intermediates seen for O2 reduction and that the O-O bond has already been cleaved in the so-called peroxy form (or 607 nm form).

Animals↗
PubMed1998

Endothelin-1 stimulates sodium-dependent calcium efflux from bovine adrenal chromaffin cells in culture.

1. The effect of endothelin (ET)-1 on Ca2+ efflux from cultured bovine adrenal chromaffin cells was examined. ET-1 (10(-7) M) significantly increased intracellular free Ca2+ level ([Ca2+]i), 45Ca2+ uptake and catecholamine secretion in the cells. 2. ET-1 stimulated the efflux of 45Ca2+ from the cells preloaded with 45Ca2+ in a concentration-dependent manner (10(-9)-10(-7) M). This stimulatory effect was inhibited by ET(B) receptor antagonist BQ788, but not by ET(A) receptor antagonist BQ123. Selective ET(B) receptor agonists Suc-[Glu9, Ala11.5]-ET-1 and sarafotoxin S6c (SRTX) also stimulated 45Ca2+ efflux from the cells. 3. ET-1, Suc-[Glu9 Ala11.15]-ET-1 and SRTX increased the level of cyclic GMP in the adrenal chromaffin cells. ET-1 induced an increase in the nitric oxide (NO) level in the cells. The stimulatory effects by which ET- increases NO level and 45Ca2+ efflux were inhibited by NG-monomethyl-L-arginine acetate (L-NMMA), a competitive inhibitor of NO synthase. 4. The 45Ca2+ efflux stimulated by ET-1 was inhibited by deprivation of extracellular Na+, but not by deprivation of Ca2+. 5. These results suggest that ET-1 stimulates an extracellular Na+-dependent Ca2+ efflux through the activation of NO synthase in cultured bovine adrenal chromaffin cells.

Adrenal Glands↗
PubMed1998

Effect of amiloride on ischaemia and reperfusion injury in isolated, perfused rat hearts.

The effect of amiloride, a potent inhibitor of Na+/H+ exchange, on ischaemic reperfused rat hearts was studied in order to investigate whether Na+/H+ exchange or Na+/Ca2+ exchange is involved in ischaemia-reperfusion injury, When hearts were pre-ischaemically loaded with 100 microM amiloride, recovery of left ventricular developed pressure was significantly better than in control hearts, whereas recovery of heart rate at 30-min reperfusion was unaffected. Amiloride pretreatment also decreased creatine phosphokinase activity in the coronary effluent and completely abolished occurrence of ventricular arrhythmias during reperfusion. It also inhibited intracellular Na+ accumulation early in reperfusion (within 5 min), whereas in the late stage (from 5 to 30 min), Ca2+ overload was inhibited. The findings suggest that Na+/H+ exchange participates mainly in the early stage of reperfusion injury and the Na+/Ca2+ exchange system, secondary to Na+/H+ exchange, in the late stage. The reduction in post-ischaemic cardiac dysfunction induced by amiloride pretreatment may be attributable to inhibition of the resultant Ca2+ accumulation during reperfusion.

Amiloride↗
PubMed1998

Preparation of monoclonal antibodies against N-(gamma-maleimidobutyryloxy)succinimide (GMBS)-conjugated acetylspermine, and development of an enzyme-linked immunosorbent assay (ELISA) for N1,N12-diacetylspermine.

We have developed three mouse monoclonal antibodies (mAb) of types IgG1 and IgG2b, i.e. anti-acetylspermine (Ac-Spm)-1 and 2 (ACSPM-1 and 2), and anti-acetylspermine (Ac-Spm)-3 (ACSPM-3), respectively, against Ac-Spm conjugated to bovine serum albumin via a heterobifunctional cross-linker, N-(gamma-maleimidobutyryloxy)succinimide (GMBS). Among these mAbs, ACSPM-2 was the most useful for the development of an enzyme-linked immunosorbent assay (ELISA) for acetylpolyamines (Ac-PAs) with glutaraldehyde (GA)-conjugated N1,N12-diacetylspermine (2Ac-Spm) or acetylspermine (Ac-Spm) as the solid phase antigen. However, GMBS-conjugated Ac-Spm did not behave as a solid phase antigen in the competitive ELISA. The ELISA is based on the principle of competition between an analyte and the conjugated antigen for the mAb, followed by immunoreaction with biotinylated anti-mouse immunoglobulin and horseradish peroxidase-streptavidin. The ACSPM-2 mAb reacted with 2Ac-Spm to the highest degree, followed by Ac-Spm, N1-acetylspermidine (N1-Ac-Spd), N8,N8-diacetylspermidine (2Ac-Spd), and spermine (Spm), the EC50 values being 0.06, 0.25, 7.0, 10, and 60 microM, respectively, but exhibited almost no cross-reaction with other polyamine-related compounds or amino acids. The method was used to determine the urinary Ac-PA levels in healthy subjects, the average value of 0.36 microg of 2Ac-Spm/g creatinine (n = 16) being obtained. The ACSPM-2 ELISA for 2Ac-Spm, which was the PA most relevant to the analysis of human urine among the five PA analogs mentioned above, might have potential for elucidation of the correlation of urinary 2Ac-Spm levels in cancers.

Animals↗
PubMed1998

Reduction of caveolin-1 expression in tumorigenic human cell hybrids.

Studies on human cell hybrids of a cervical carcinoma cell line, HeLa, and normal fibroblasts have indicated that the tumorigenicity of these cells is under the control of a putative tumor suppressor on chromosome 11, although the nature of this suppressor remains unknown. We examined the expression of caveolin-1, a protein component of caveolae of the plasma membrane in these cell hybrids. The non-tumorigenic cell hybrid, CGL1, and normal fibroblast WI38 cells expressed 21-24 kDa caveolin-1, whereas in tumorigenic hybrid CGL4 as well as in the parental HeLa cells, the level of caveolin-1 was markedly reduced. Caveolin-1 expression was also reduced in gamma-ray-induced tumorigenic clones (GIMs) isolated from CGL1 cells, whereas non-tumorigenic irradiated cells expressed the same level of caveolin-1 as CGL1 cells. In accordance with these changes, the cellular level of caveolin-1 mRNA was reduced in the tumorigenic CGL4 cells and GIMs without any detectable changes in the caveolin-1 gene. However, the in vivo tumor growth of CGL4 cells was not altered when caveolin-1 was stably overexpressed through the transfection of a human caveolin-1 cDNA. These results suggest that reduction of caveolin-1 expression is necessary but not sufficient for emergence of the tumorigenic phenotypes of HeLa cell hybrids. Possible roles of the putative tumor suppressor in the control of gene expression are also discussed.

Blotting, Northern↗
PubMed1998

Pathological characteristics of gastric carcinomas in the very old.

A total of 69 gastric carcinomas of very old people (aged > or = 85) were collected and pathologically analyzed in comparison with those of young to middle-aged (30-39) and elderly (65-69) people, with special attention to their phase. In the very old, almost all (34/35) carcinomas in the early phase belonged to well-differentiated categories. In the advanced phase, half of them (17/34) were classified into poorly differentiated categories when determined from the predominant pattern, but a well-differentiated pattern almost always coexisted in the superficial site. Thus, the gastric carcinomas in the very old may principally develop as well-differentiated carcinomas which then progress to poorly differentiated carcinomas with time, in contrast to those of the young to middle-aged, most of which emerged from the very early phase as poorly differentiated lesions. The gross features of the carcinomas were also in line with these histological observations. The carcinomas of the elderly showed distinct similarity to those of the very old. The results suggest that poorly differentiated carcinomas of the young to middle-aged and the old may be better classified and analyzed separately in view of the generally recognized etiological (e.g., specifically close causal relationship with environmental factors of the intestinal-type carcinoma of the old) and biological (e.g., practically no tendency for hematogenous metastasis of the diffuse-type carcinoma of the young to middle-aged) differences, although in the General Rules for Gastric Cancer Study of Japan, both are placed in the same category, por (por2).

Adenocarcinoma↗
PubMed1998

Association of loss of heterozygosity at the p53 locus with chemoresistance in osteosarcomas.

Although the osteosarcoma is considered to be among the most chemosensitive malignancies and preoperative chemotherapy is commonly applied, an appreciable proportion of cases are in fact quite sensitive. Predictive markers for chemosensitivity are therefore desirable in order to develop effective treatment strategies. Thirty-two cases of conventional osteosarcomas treated at the Cancer Institute Hospital, Tokyo, were analyzed. The sensitivity to preoperative chemotherapy was investigated with reference to loss of heterozygosity (LOH) at the 17p13 (p53) and 13q14 (Rb) loci and expression of the cell-cycle associated proteins, p53, Rb, p21/Waf-1, mdm-2 and Ki-67, as detected immunohistochemically. LOH was detected by analyzing polymerase chain reaction products at marker microsatellite loci. The efficacy of chemotherapy was evaluated both radiologically and histologically. LOH at p53 or Rb loci was seen in 54% (13/24) and 58% (14/24) of cases, respectively. Only 15% of osteosarcomas with LOH at the p53 locus were sensitive to preoperative chemotherapy, as compared to 64% of tumors without such loss (P < 0.05). A similar but much less distinct tendency was observed with LOH at the Rb locus. No relationship was evident between chemosensitivity and immunohistochemical staining patterns for p53, Rb, p21/Waf-1, mdm-2 or Ki-67. The results suggest that p53 gene deletion, but not the other parameters investigated, may be useful for predicting chemoresistance of osteosarcomas.

Adolescent↗
PubMed1998

Experiments on steady and oscillatory flows at moderate Reynolds numbers in a quasi-two-dimensional channel with a throat.

The study of steady and unsteady oscillatory static fluid pressures acting on the internal wall of a collapsible tube is essential for investigation of the complicated behavior observed when a flow is conveyed inside a tube. To examine the validity of two one-dimensional nonsteady theoretical flow models, this paper presents basic experimental observations of flow separation and reattachment and measured data on the static pressure distributions of the flow in a quasi-two-dimensional channel with a throat, together with information on the corresponding shape of the wall deflection and motion. For combinations of moderate Reynolds numbers and angles of the divergent segment of the channel, a smooth flow is separated from the wall downstream of the minimum cross section and reattached to the wall farther downstream. The measured data are compared with numerical results calculated by the two flow models.

Elasticity↗
PubMed1998

Increased incidence of non-insulin dependent diabetes mellitus among Japanese schoolchildren correlates with an increased intake of animal protein and fat.

Non-insulin dependent diabetes (NIDDM) was diagnosed in 188 of more than 7 million Tokyo schoolchildren tested between 1974 and 1994 for glycosuria followed by oral glucose tolerance testing. The incidence rate of NIDDM in youth has continued to increase since 1976. While the daily energy intake has not changed significantly, the consumption of animal protein and fat by the Japanese population has greatly increased during the past two decades, and this change in diet, with low levels of physical activity, may exacerbate insulin resistance and glucose intolerance.

Adolescent↗
PubMed1998

Treatment of NIDDM in youth.

This study presents the characteristics of 20 children (17 female) with NIDDM who required oral hypoglycemic agent (OHA) therapy. A family history of NIDDM was present in 55%. None had islet cell antibodies (ICA) or glutamic acid decarboxylase (GAD) antibodies. Tolbutamide was the drug of choice; glibenclamide was introduced if glycemic control was not obtained after 2 to 3 months of tolbutamide therapy. Seven of the patients eventually required insulin therapy.

Adolescent↗
PubMed1998

Immunoelectron microscopic study for polyamines.

The polyamines (PAs) are ubiquitous polycationic metabolites in eukaryotic and prokaryotic cells and are believed to be intimately involved in the regulation of DNA, RNA, and protein biosynthesis, the exact function of which remains unclear, mainly because of a lack of knowledge of PA subcellular localization. In this study, using immunoelectron microscopy, we have demonstrated that PAs are predominantly located on free and attached ribosomes of the rough endoplasmic reticulum in the neurons of the lateral reticular nucleus of rat medulla oblongata. The nuclei, axons, and nerve endings were devoid of PA. This suggests that PAs are one of the components of biologically active ribosomes, being closely involved in the translation processes of protein biosynthesis.

Animals↗
PubMed1998

Enzyme immunoassay for a characteristic protein in the animal crude drug lumbricus.

A new method was developed to measure the content of a Lumbricus component in a traditional Chinese medicine (TCM). An antiserum specific to Lumbricus was elicited in a rabbit following immunization with a suspension of Lumbricus fragments. A characteristic antigen protein, 70 kDa, was found in Lumbricus and was purified almost to singleness using a column chromatography series of gel filtration and DEAE-Sepharose. A selected antibody enzyme immunoassay (SAEIA) was developed using the antiserum and the purified 70 kDa protein as a solid-phase antigen. The SAEIA was specific to Lumbricus species, and showed no cross-reaction with any crude drugs other than Lumbricus. This SAEIA detected 70 kDa protein in the amount of 10 ng/ml with excellent reproducibility (coefficient of variation=3.0%) and an EC50 of 0.24 microg/ml. Using this assay, Lumbricus levels were easily determined in a Lumbricus-based TCM Kazecoll, but not in the control Kazecoll (Kakkonto) prepared without Lumbricus. The SAEIA for 70 kDa protein was simple, accurate, reproducible and may provide a general analytical method for the quality control of Lumbricus-based TCMs.

Animals↗
PubMed1998

Changes in plasma free and sulfoconjugated catecholamines during the perioperative period of cardiac surgery: effect of continuous infusion of dopamine.

In order to elucidate the pharmacological properties of the formation of sulfoconjugated catecholamines (CAs) in human plasma, we investigated the changes in the plasma levels of free and sulfoconjugated CA during the continuous infusion of dopamine (DA; 4-6 microg/kg/min for 24 h, followed by 3-4 microg/kg/min for 48 h) in patients who had undergone cardiac surgery. The plasma level of free DA increased immediately after the start of the infusion and reached a plateau within 1 h at a level of about 2000 times the basal value. In the control patients who had received non-cardiac surgery without DA infusion, plasma-free DA increased only 5-fold after their operation. The plasma level of DA sulfate increased linearly for 24 h, to 48-fold of the basal value by DA infusion, whereas it showed only a 2-fold increase in the control patients. After 24 h, due to reduction of the infused DA dose, the level of free DA gradually decreased, whereas the level of DA sulfate remained elevated. The plasma levels of free adrenaline (Ad) and noradrenaline (NA) also increased during the DA infusion, but their levels reached a plateau within 1-2 h. Sulfoconjugated Ad and NA increased progressively until the tapering off of DA infusion. In the control patients, both free and conjugated Ad and NA showed transient increases over 12 h after surgery. These results suggest that sulfoconjugation plays a role in regulating the plasma levels of excess free CA, thereby modifying the cardiovascular effects of circulating CA. Measurement of the increase in plasma conjugated CA may be useful as an index of the increase in free CA in plasma due to the administration of an exogenous form or release of endogenous CA from the tissues.

Adult↗
PubMed1998

Diverse relaxation responses of canine large and small conductive coronary arteries to glyceryl trinitrate and nitric oxide on the one hand and to 8-bromoguanosine 3':5' cyclic monophosphate on the other.

Glyceryl trinitrate (GTN) and nitric oxide (NO) preferentially relaxed the large (2 mm in diameter) conductive coronary artery (CCA) of the dog, while 8-bromoguanosine 3':5' cyclic monophosphate preferentially relaxed the small one (0.6 mm in diameter). Neither L-cysteine nor L-acetylcysteine affected GTN-induced relaxation in small- and large-CCA. These results indicate that not different biotransformation of GTN to NO, but a process or processes operative between activation of guanylate cyclase and that of cyclic GMP-dependent protein kinase seems to be responsible for the preferential dilatation of large-CCA.

Acetylcysteine↗
PubMed1998

[Reproductive and developmental toxicity study of sodium N-[2-[4-(2,2-dimethylpropionyloxy) phenylsulfonylamino] benzoyl] aminoacetate tetrahydrate (ONO-5046.Na (1). Fertility study in rats].

Fertility study of sodium N-[2-[4-(2,2-dimethylpropionyloxy) phenylsulfonylamino] benzoyl] aminoacetate tetrahydrate (ONO-5046.Na), a novel neutrophil elastase inhibitor, was conducted in Sprague-Dawley (SD) rats. ONO-5046.Na was administered intravenously at doses of 18.75, 37.5 and 75 mg/kg/day to male rats from 64 prior to mating, through the mating period and until necropsy, and to female rats from 15 days prior to mating until Day 7 of gestation, in order to examine its effects on fertility and reproductive performance of males and females and the development of their fetuses. There were no changes attributable to ONO-5046.Na in general signs, body weight, food consumption or autopsy findings in males and females. No drug-related changes were observed in estrous cycles, copulation and fertility indices in males and females. Pituitary weight of dams was decreased in each of the ONO-5046.Na treated groups, but no histopathological changes were observed in the pituitary. In the cesarean section findings in dams, ONO-5046.Na had no effects on the number of corpola lutea, the number of live fetuses, the implantation ratio, the resorbed and dead fetus ratio, fetal or placental weight, or the incidences of external, skeletal or visceral anomalies of the fetuses. From these results, it is considered that the NOAEL of ONO-5046.Na is 75 mg/kg/day for general and reproductive toxicity in males and females and for developmental toxicity in their fetuses.

Animals↗
PubMed1998

Stromal cells and cytokines in the induction of recombination activating gene (RAG) expression in a human lymphoid progenitor cell.

The activation of recombination activating genes (RAGs) plays critical roles in the V(D)J gene recombination machinery and lymphocyte repertoire formation. However, the regulation of RAG gene expression in humans as well as animals is poorly understood. We show that RAG gene expression is activated in a human lymphoid progenitor cell line (FL8.2.4.4) by coculturing them on a bone marrow-derived stromal cell line (PA6) in the presence of cytokines. The RAG transcripts become detectable in 12 hours after initiation of culture, and the increased level is sustained at 24 hours. Among the cytokines, IL-3, IL-6, and IL-7, but not IL-2, IL-4, SCF, GM-CSF induces RAG activation. IL-3, IL-6, and IL-7 exert their effect synergistically on RAG activation. A cognate interaction between FL8.2.4.4 cells and PA6 stromal cells seems to be prerequisite for RAG activation. RAG transcripts are inducible in FL8.2.4.4 cells when cocultured on paraformaldehyde fixed-PA6 stromal cells in the presence of cytokines. These data indicate that two separate signals are both required for induction of RAG activation in lymphoid progenitors; one from the cell surface molecule(s) on stromal cells, and the other from recombinant cytokine(s). The expression of RAG mRNA in FL8.2.4.4 cells is concomitant with induction of recombinase activity. Thus, this system may provide a useful means for further understanding of the mechanisms controlling RAG activation and lymphocyte development in human system.

Cell Line↗
PubMed1998

Loss of imprinting of the insulin-like growth factor II gene in mouse hepatocellular carcinoma cell lines.

We investigated expression of insulin-like growth factor II (Igf2) in primary cultured hepatocytes, liver epithelial (LE) cell lines derived from normal hepatocytes, and hepatocellular carcinoma (HCC) cell lines from crosses between C3H/HeJ (C3H) and Mus musculus molossinus mice (MSM). Igf2 mRNA was detected by reverse transcriptase-polymerase chain reaction in primary cultured hepatocytes from 5 d after the start of cultivation and in all 12 LE and 16 HCC cell lines. Analysis of the untranslated region of Igf2 exon 6, which contains polymorphic CA repeats, revealed that 13 of the 16 HCC cell lines had biallelic expression, whereas monoallelic expression was retained in the primary cultured hepatocytes and all 12 LE cell lines. The Igf2 transcripts contained exons 1-3 in all the HCC cell lines but only exons 2 and 3 in cultures of hepatocytes and LE cell lines, indicating difference in promoter use. However, the biallelic HCC cell lines did not have larger amounts of Igf2 mRNA and protein than did the monoallelic lines, suggesting that loss of imprinting may not be directly related to the level of Igf2 expression.

Alleles↗