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H Nakazawa

Publications and source records attributed to H Nakazawa.

At least 19 recordsLinked to original sources
PubMed1992

Inhibitory effects of pectic substances on activated hyaluronidase and histamine release from mast cells.

In this paper, we report the effect of pectic substances and D-galacturonic acid, the main constituent of pectic substances, on activated hyaluronidase and histamine release from mast cells. Although D-galacturonic acid itself showed no inhibition, IC50 values of hyaluronidase inhibition were correlated with the D-galacturonic-acid content of pectic substances. It was thought that the polymerization of D-galacturonic acid was necessary for inhibition of activated hyaluronidase. This type of inhibition was suggested to be non-competitive by the Lineweaver-Burk plot. Furthermore, pectic substances, including those purified from Gymnema sylvestre, inhibited histamine release from isolated rat peritoneal mast cells, which had been induced by the antigen. These results suggest that pectic substances may have anti-allergic activities.

Animals↗
PubMed1992

Determination of nitroxynil in cow milk by reversed-phase high-performance liquid chromatography with dual-electrode coulometric detection.

A sensitive and specific method is described for the determination of nitroxynil (fasciolicide) residues in cow milk. The milk samples were extracted with acetone and acetonitrile, following clean-up using a simple liquid-liquid extraction step. Nitroxynil was separated from the matrix peaks by reversed-phase high-performance liquid chromatography and detected using dual-electrode coulometric detection. The mobile phase was a mixture (20:80, v/v) of acetonitrile and 0.05 M potassium dihydrogenphosphate with the pH adjusted to 4.0. The flow-rate was 1 ml/min at 40 degrees C. The applied potentials of detectors 1 and 2 were maintained at -0.7 and +0.2 V, respectively. Average recoveries (n = 5) of nitroxynil from milk samples spiked at concentrations of 0.01 and 0.1 micrograms/ml were found to be 92.0% and 97.0% with coefficients of variation of 6.2% and 2.2%, respectively. The detection limit of nitroxynil in milk was 0.7 ng/ml. During the analysis of 30 raw cow milk and 140 market milk samples, nitroxynil was detected at a level of 4 ng/ml in one raw cow milk sample.

Animals↗
PubMed1992

High-performance liquid chromatography of histamine and 1-methylhistamine with on-column fluorescence derivatization.

An on-column fluorometric derivatization method was developed for the determination of histamine and 1-methylhistamine (HMs) by high-performance liquid chromatography. The system for the derivatization consisted only of a commercially available single-plunger pump and a reversed-phase C18 column supported on synthetic polymer with a mobile phase of acetonitrile and alkaline borate buffer solution containing o-phthalaldehyde as a derivatization reagent. It required no additional reaction system as for a post-column derivatization method. Injected HMs might be derivatized to a fluorophore on the inlet site of the high-performance liquid chromatographic column, followed by chromatography on the same column. Optimization of the on-column reaction conditions resulted in a simple and sensitive analytical method for the determination of HMs with excellent reproducibility and linearity of 0.05-5 micrograms/ml of both HMs. Application of this method to the determination of HMs in food samples resulted in a limit of quantification of 0.05 mg/100 g and in a greater than 95% overall mean recovery at a fortification of 0.1 mg/g of both HMs. This method was furthermore applicable to the determination of histamine released from rat peritoneal mast cells.

Animals↗
PubMed1992

Role of activator protein-1 and methylation function in 12-O-tetradecanoylphorbol-13-acetate--mediated inhibition of differentiation of Friend erythroleukemia cells.

Friend erythroleukemia cells (FELCs) differentiate after hexamethylene-bis-acetamide treatment. This differentiation is characterized by an increase in beta-globin gene expression that is followed by appearance of the hemoglobin. Phorbol-ester tumor promoters, such as 12-O-tetradecanoylphorbol-13-acetate (TPA), inhibit differentiation of TPA-sensitive cells but not TPA-resistant cells. We have shown that the increase in beta-globin expression is inhibited by TPA in a TPA-sensitive clone but not in a TPA-resistant clone. To study the molecular mechanisms of regulation of gene expression by TPA, we examined the possible involvement of gene methylation and the TPA-responsive element (TRE). Both clones showed similar patterns of methylation around the beta-globin gene. Moreover, TPA-induced TRE binding and TRE enhancer activity were similar in both variants. These results suggest that the TPA inhibition of induced differentiation may not be explained by regulation of the methylation state. The activator protein-1 also does not play a crucial role in the sensitivity of FELCs to TPA.

Animals↗
PubMed1992

Time course of superoxide generation by leukocytes--the MCLA chemiluminescence system.

This study was performed to examine the pattern of superoxide (O2-.) generation from leukocytes using the O2-. specific chemiluminescence (CL) method. Cypridina luciferin analog, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo [1,2-alpha]pyrazin-3-one (MCLA) was used as a CL probe. The appropriate conditions of the MCLA method was first determined for the evaluation of the time course of O2-. generation by leukocytes. The time course of O2-. generation obtained by the MCLA-CL system was compared with that by the luminol-dependent CL, electron spin resonance (ESR)/spin trapping, and cytochrome c systems. Following stimulation by three different stimulants (PMA, OZ, FMLP), leukocytes continuously generated O2-. for up to 5 h in the MCLA-CL system, irrespective of the kind of stimulation. The curves obtained by generation ceased more rapidly in the luminol-CL, ESR/spin trapping, and cytochrome c systems. A 50% activity of the initial value was observed at 70 min in the MCLA-CL system, but 30, 10 and 35 min in the other systems, respectively. The CL or O2-. generation value decreased to less than 1% (possible termination) at 300, 90, 120 and 180 min, respectively. With the exception of ESR studies with OZ, the cell viability was not significantly affected in any of the trials. These results indicate that leukocytes can generate O2-. much longer than previously estimated and that the MCLA-CL-system is the most suitable system for the measurement of the O2-. generation by leukocytes.

Cell Separation↗
PubMed1992

The failure of radical scavengers to attenuate the incidence of reperfusion arrhythmias despite improvement of cardiac function.

We studied the concomitant effects of scavengers of reactive oxygen species (ROS) on both cardiac function and the incidence of arrhythmias. Isolated rat heart was perfused with a working mode paced at 300 beats/min. The left coronary artery was occluded for 5, 7, 15, or 60 min and reperfused thereafter for 30 min. Superoxide dismutase and catalase were infused from 5 min prior to reperfusion to the end of reperfusion in the scavenger treatment group. In the 60-min ischemia group with scavenger treatment, the cardiac output was significantly higher than that in the untreated group at both 10 and 30 min of reperfusion (P less than 0.01). In the 15-min ischemia group with scavenger treatment, the cardiac output showed a tendency toward a higher value than that in the untreated group. The incidence of reperfusion arrhythmias occurring after a short ischemic time (5, 7, or 15 min) were similar in the scavenger treated and untreated groups; but, with a preceding ischemia of 60 min, the incidence of ventricular tachycardia was higher in the scavenger treated group than in the untreated group (P less than 0.02). In conclusion, scavengers improved contractile dysfunction but did not attenuate the incidence of arrhythmias.

Animals↗
PubMed1992

Interaction and distinction of genotoxic and non-genotoxic events in carcinogenesis.

Multistage carcinogenesis involves genotoxic as well as non-genotoxic mechanisms. The importance of genotoxic events in human carcinogenesis is apparent from the analysis of tumours: for example, five to six genetic alterations can be found in most malignant colorectal tumours. While such measurable "footprints" (e.g. ras, p53 mutations) can be left in tumours by genotoxic events, non-genotoxic events cannot directly generate them. Thus, the lack of specific indicators of non-genotoxic events in carcinogenesis makes the identification of non-genotoxic carcinogens difficult. It is also important to emphasize that apparent "genotoxic" endpoints (mutations, chromosome aberrations) could be induced by "non-genotoxic" agents through indirect mechanisms (e.g. induced cell proliferation and/or genomic instability, oxidative damage, deamination of 5-methyl cytosine). This emphasizes the need for differentiating "events" from the actual "activities" of chemicals and the difficulty of classification of carcinogens into genotoxic and non-genotoxic. One of the best models for the study of interaction of genotoxic and non-genotoxic mechanisms during carcinogenesis is a two-stage carcinogenesis system using mouse skin, rat liver or cultured cells. Molecular analysis of tumours produced on mouse skin by the classical initiation-promotion protocol indicates that the mutation spectra of oncogenes, e.g. Ha-ras, are determined by initiating (genotoxic) and not by promoting (non-genotoxic) agents. However, since usually no tumours appear without the application of tumour-promoting agents, the manifestation of genotoxic events (Ha-ras mutation) is dependent on the action of non-genotoxic agents. Using a BALB c 3T3 two-stage cell transformation system, we have now succeeded in confirming this and have quantitated the initiation and promotion events. These studies may help us not only in understanding mechanisms of carcinogenesis but also in developing molecular quantitative risk assessment in terms of multistage carcinogenesis.

3T3 Cells↗
PubMed1992

Foreign gene expression by a baculovirus vector with an expanded host range.

A nuclear polyhedrosis virus (NPV) (Baculoviridae)-based gene expression system was improved by DNA recombination. The BmN cell line established from Bombyx mori and the Sf21 cell line established from Spodoptera frugiperda are non-permissive for Autographa californica multicapsid NPV (AcMNPV) and B. mori NPV (BmNPV) replication, respectively. After cotransfection of AcMNPV DNA and BamHI-digested BmNPV DNA into Sf21 cells, progeny viruses were isolated by plaque purification on BmN cell monolayers and the host specificity of one viral isolate was analysed. The virus had a wider host range, and replicated and produced polyhedra in Sf21 cells, BmN cells and larvae of the silkworm, B. mori. DNA restriction endonuclease analysis showed that the isolate was a hybrid of AcMNPV and BmNPV. Using the AcMNPV transfer vector pAcYM1 a portion of the polyhedrin gene of the hybrid virus was replaced with the coding region of the firefly luciferase gene, producing a recombinant virus. The latter expressed firefly luciferase in both cell lines and in silkworm larvae under the control of the polyhedrin promoter.

Baculoviridae↗
PubMed1992

The presence of immunoreactive parathyroid hormone-related protein in parathyroid adenoma cells.

Parathyroid hormone-related protein (PTHrP) was first identified in human malignant tumors associated with humoral hypercalcemia of malignancy. We immunohistochemically examined the distribution of PTHrP both in 7 normal parathyroid glands and in a 20 parathyroid adenomas. Sixty-five percent of parathyroid adenomas (13 cases) were positive for PTHrP, whereas only one normal parathyroid gland was positive for PTHrP in the area of transitional oxyphil cells. Many parathyroid adenomas (12 cases) were composed of both PTHrP-positive cells and--negative cells, and these two different type of cells showed a tendency to form nodules respectively in parathyroid adenoma. Although both chief cells and oxyphil or transitional oxyphil cells were positive for PTHrP in parathyroid adenoma, oxyphil or transitional oxyphil cells were more responsible for PTHrP production than chief cells. Chief cells are thought to produce parathyroid hormone mainly in parathyroid adenoma. On the other hand, little is known concerning the function and role of oxyphil or transitional oxyphil cells. Our results suggest that oxyphil or transitional oxyphil cells in parathyroid adenoma may have some functional roles different from those of chief cells through the production of PTHrP.

Adenoma↗
PubMed1992

Reversal of hyperdynamic response to continuous endotoxin administration by inhibition of NO synthesis.

Septic shock is characterized by an increase in cardiac output and a fall in systemic vascular resistance index and mean arterial pressure. Endotoxin alters the smooth muscle function of blood vessels, probably by means of an increased production of the potent vasodilator nitric oxide (NO). The present study was accomplished to determine how the inhibition of NO synthesis influences cardiovascular performance in an ovine model of hyperdynamic endotoxemia. Endotoxemia was induced in five range ewes (41 +/- 2 kg) by continuous infusion of Escherichia coli endotoxin (LPS, 10 ng.kg-1.min-1) over the entire study period. After 24 h of LPS infusion, cardiac output increased from 5.2 +/- 0.3 to 7.9 +/- 0.6 (SE) 1/min (P less than 0.05) and mean arterial pressure and systemic vascular resistance index fell from 92 +/- 5 to 79 +/- 6 mmHg (P = 0.08) and from 1,473 +/- 173 to 824 +/- 108 dyn.s.cm-5.m2 (P less than 0.05), respectively. The pulmonary shunt fraction increased from 0.23 +/- 0.03 to 0.32 +/- 0.03 (P less than 0.05). The intravenous administration of the NO synthase inhibitor N omega-nitro-L-arginine methyl ester (25 mg/kg) 24 h after the start of the LPS infusion changed these values to approximately baseline levels over the subsequent 4 h. Although N omega-nitro-L-arginine methyl ester increased pulmonary arterial pressure and pulmonary vascular resistance (P less than 0.05), right and left ventricular stroke volume index showed no significant changes. It is concluded that NO has a major function in cardiovascular performance in endotoxemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Reperfusion after a two-hour period of pulmonary artery occlusion causes pulmonary necrosis.

The role of reperfusion injury in the progression to necrosis in pulmonary embolism was evaluated. To simulate this condition, we used a technique that enables occlusion and reopening of the pulmonary arterial branch supplying the right upper lobe in conscious rats. The rats were divided into five groups: the occlusion group (n = 12), in which the pulmonary artery (PA) branch was occluded without reperfusion; the reperfusion group (n = 12), in which the PA branch was reopened after a 2-h period of occlusion; and the reperfusion-SOD (n = 9), reperfusion-IM (n = 8), or reperfusion-IA-SOD (n = 6) groups, in which superoxide dismutase (SOD), indomethacin (IM), or inactivated SOD (IA-SOD), respectively, was administered during reperfusion. The lungs were removed 24 h after the PA occlusion, and histologic examination was performed. In the occlusion group, the alveolar structure of the right upper lobe was well preserved, and there was no erythrocyte or leukocyte accumulation. The only significant changes compared with the control lobe was the appearance of wavy internal elastic lamina of the PA and slight neutrophil adherence to the endothelial cells. In contrast, the right upper lobe of the reperfusion group disclosed numerous foci of hemorrhagic necrosis, with disrupted alveoli and leukocyte accumulation in all cases. With SOD treatment, the changes compatible with hemorrhagic necrosis were attenuated to the level of the control lobes. However, neither IM nor IA-SOD decreased these changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Disseminated cryptococcosis presenting with adrenal insufficiency and meningitis: resistant to prolonged antifungal therapy but responding to bilateral adrenalectomy.

A case of disseminated cryptococcosis with features of primary adrenal insufficiency and meningitis in an immunocompetent host is presented. Despite antifungal chemotherapy, neither meningitis nor bilateral adrenal gland enlargement was improved. Aspiration biopsy of the adrenal gland revealed necrotic tissue with numerous fungi, suggesting that the adrenal glands were the focus of the persistent fungemia. Removal of bilateral adrenal glands led to improvement by making the patient more sensitive to antifungal chemotherapy.

Adrenal Gland Diseases↗
PubMed1992

[Optimal dose of cyclosporin in living related kidney transplantation].

We performed in total 528 kidney transplantations from Feb. 1983 to Dec. 1988 in Kidney Center of Tokyo Women's Medical College. Of the 528 kidney transplantations, 450 were living related kidney transplantations. The living related renal transplant recipients treated with CYA were divided into 3 groups: high dose CYA double drug therapy group (group 1), high dose CYA triple drug therapy group (group 2) and low dose CYA triple drug therapy group (group 3). Group 1 (n = 263) was treated with CYA (initial dose 12 mg/kg) and methylprednisolone (MP). Group 2 (n = 106) was treated with CYA (initial dose 10 mg/kg), MP and azathioprine (AZ) (1 mg/kg). Immunosuppression of group 3 (n = 81) consisted of CYA (initial dose 6 mg/kg), MP and AZ (2 mg/kg) (or mizoribine (MZ) (3-5 mg/kg). CYA serum trough level (polyclonal) was lowered according to the initial dose of CYA, and in particular trough level in group 3 was controlled at a low level (50-150 ng/ml in induction phase) to reduce CYA nephrotoxicity. However, even if strict control of serum trough level was accomplished, we could not get improvement of renal function in Group 3. Group 3 had more frequent and severe accelerated acute rejections (AAR) than the other groups. These data showed that inadequate immunosuppression in group 3 caused more frequent and severe rejection episodes. Also, renal biopsy revealed CYA nephrotoxicity even in group 3 and this nephrotoxicity may have been caused by ischemic damage by severe rejections.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Successfully treated locally advanced breast cancer by intra-arterial infusion chemotherapy: a case report].

A 40-year-old female was admitted to our hospital with a large right breast tumor that was over 15 cm in diameter. We treated this locally advanced breast cancer by intra-arterial infusion chemotherapy. Through a catheter placed in the right subclavian artery, doses of 20-30 mg of ADM were injected intermittently with MMC and 5-FU. When a total of 120 mg of ADM had been infused, leukopenia developed, but this was immediately improved by G-CSF. With this treatment, her breast tumor and lung metastases were almost completely disappeared. Thus, an intra-arterial infusion chemotherapy was considered to be an effective treatment for locally advanced breast cancer.

Adult↗
PubMed1992

Identification and quantification of a carcinogen-induced molecular initiation event in cell transformation.

All transformed foci of Balb/c 3T3 clone A31-1-1 cells induced by 7,12-dimethylbenz[a]anthracene (DMBA) (42 out of 42 examined) contained an A to T transversion at codon 61 (A182 to T) of the Ki-ras gene. The transformants induced by other carcinogens tested did not contain such a mutation, except one out of nine 12-O-tetradecanoyl phorbol 13-acetate (TPA)-induced transformed foci. Thus, we hypothesized that this mutation is a specific DMBA-induced initiating event in Balb/c 3T3 cell transformation and we have measured its frequency of induction before transformation occurs, employing our recently developed method. Such mutations can be detected in the cell population as early as 3 days after exposure to DMBA. The same mutation was also detected in the Ha-ras gene. No detectable level (< 10(-6) of these mutations was induced by other carcinogens tested. The mutation frequency of the Ha-ras gene reached a plateau after 1 week's exposure, but that of the Ki-ras gene continued to increase. These results suggest that the A182 to T mutation of the Ki-ras gene, but not that of the Ha-ras gene, contributes to morphological transformation of Balb/c 3T3 cells. We have demonstrated that the level of expression of ras genes determines the rate of recruitment of cells into transformation. Quantitative analysis of the frequencies of ras gene mutations (initiation) and of transformation suggests that about 25% of those cells with the Ki-ras mutation were recruited into the full transformation process and that, in the presence of the tumor promoter TPA, about 56% of them completed morphological cell transformation.

3T3 Cells↗
PubMed1992

[Evaluation of complicated renal cyst: a comparison of CT and MR imaging].

We report 12 cases of renal cystic lesions that could not be diagnosed preoperatively. Sonography, computed tomography (CT), magnetic resonance (MR) imaging, and angiography were performed in all cases. Angiography was not helpful in evaluating cystic lesions, because all cystic lesions were hypovascular or avascular within the cystic mass. CT was useful in depicting the fine structural abnormalities, and especially bolus-contrast CT study was useful in the differentiation of cystic renal cell carcinoma from simple renal cyst. However, there were 5 false positive cases. MR imaging is superior to CT in distinguishing a hemorrhagic cyst or multiloculated cystic mass. In conclusion, CT is currently the primary imaging modality for evaluating complicated renal cysts, and surgical exploration is warranted for the undiagnosed cystic lesion by CT. However, MR imaging also has an important role in detecting the benign complicated cyst. Therefore if complicated cyst is thought to be benign by MR imaging, parenchyma-sparing surgery should be considered preoperatively.

Adult↗
PubMed1991

Investigation of the existence and biological role of L-arginine/nitric oxide pathway in human platelets by spin-trapping/EPR studies.

The aim of the present study was to apply spin trapping/EPR spectroscopy to investigate the existence and biological role of the L-arginine/nitric oxide pathway in human platelet aggregation. Three different spin traps were used: two nitroso, 3,5-dibromo-4-nitrosobenzenesulfonate (DBNBS) and 2-methyl-2-nitrosopropane (MNP), and a nitrone, 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The effect of spin-trap concentration on the collagen-induced human platelet aggregation was compared to the anti-aggregatory effect caused by L-arginine. The results show that the nitroso spin traps (DBNBS and MNP) are more effective than L-arginine in preventing platelet aggregation. DMPO has virtually no effect on the collagen-induced aggregation except at a high concentration (300 mM). Furthermore, activation of platelets with a low concentration of collagen (17 micrograms/ml) and in the presence of DBNBS or MNP yields several EPR-detectable spin adducts. Some of the observed spin adducts do not correspond to those originating from the interaction of a free radical, nitric oxide (NO.) gas, with the spin traps [Arroyo, C.M. & Kohno, M. (1991) Free Radical Res. Commun. 14, 145-155]. Only one adduct of DBNBS, with a relative intensity of 0.1, observed in the washed-platelet experiment and in the presence of superoxide dismutase, is similar to the EPR spectrum obtained following a reaction of pure NO. gas with DBNBS. This suggests that the EPR spectrum of the DBNBS adduct consisting of a triplet may originate from the production of NO. by these cells. Additional DBNBS and MNP spin adducts were generated during platelet activation in the presence of Ca2+ and of a cytosol-depleted L-arginine preparation from washed platelets to which L-arginine was subsequently added. The formation of these DBNBS and MNP spin adducts were inhibited by N omega-methyl-L-arginine (MeArg, 100 microM), suggesting that these originated from a product of NO synthase. Furthermore, the formation of DBNBS and MNP spin adducts in platelet suspensions was enhanced by the presence of superoxide dismutase; however, their formation was prevented by the endothelial-derived relaxing factor (EDRF) inhibitors methylene blue and hemoglobin. The results from the MeArg and EDRF inhibitor experiments support the existence of the L-arginine/NO pathway in platelets. In addition, the prevention of spin-adduct formation by EDRF inhibitors, suggests that the mechanisms of EDRF formation and the L-arginine/NO pathway in endothelial cells and platelets are similar.(ABSTRACT TRUNCATED AT 400 WORDS)

Arginine↗