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Biomedical subjects

M Sawada

Publications and source records attributed to M Sawada.

At least 145 records · Page 8Linked to original sources
PubMed1998

Measurement of mutation frequency at the HPRT locus in peripheral lymphocytes. Is this a good method to evaluate a cancer risk in pediatric patients?

Validity of measurement of somatic cell mutation frequency (Mf) at the hprt locus for evaluating cancer risk of the given individual was determined in pediatric patients. Peripheral lymphocytes (PL) from patients with various diseases, including acute lymphoblastic leukemia (ALL) and Hodgkin's disease (HD), DNA repair deficient syndromes or short stature receiving growth hormone (GH), were isolated through Ficoll-Hypaque sedimentation with informed consent. Mf at the hprt locus of PL was determined by limiting dilution assay using 6-thioguanine (6-TG). Results were as follows. (1) ALL patients after chemotherapy had higher Mf than that of age-matched controls. (2) Patients with HD tended to have higher Mf after chemotherapy. (3) Among DNA-repair deficient syndromes, diseases which are susceptible to cancer (Xeroderma pigmentosum, Ataxia telangiectasia) have high Mf, but those without any cancer disposition (Cockayne syndrome, Rothmund-Thomson syndrome) have normal Mf. (4) GH-receiving patients have normal Mf, regardless of total doses of GH. Measurement of Mf at HPRT locus may be useful for evaluating cancer risk of pediatric patients.

Adolescent↗
PubMed1998

Comparison of the signal transduction pathways activated by gastrin in enterochromaffin-like and parietal cells.

BACKGROUND & AIMS: Gastrin stimulates acid secretion from parietal cells and histamine release from enterochromaffin-like (ECL) cells through identical gastrin receptors. However, gastrin has been shown to have a trophic effect only on ECL cells. The aim of this study was to compare gastrin-induced signal transduction pathways in the ECL and parietal cells of Mastomys natalensis, an African rodent. METHODS: Both ECL and parietal cells were isolated from the gastric mucosa of M. natalensis, and intracellular signal transduction events in response to gastrin were investigated. RESULTS: Gastrin elicited histamine release from ECL cells and acid secretion from parietal cells in association with enhanced inositol phospholipid turnover. Although gastrin increased [3H]thymidine incorporation into ECL cells, it had no effect on parietal cells. Moreover, tyrosine phosphorylation and activation of mitogen-activated protein (MAP) kinase as well as c-fos and c-jun gene expression were augmented only in ECL cells. In addition, gastrin increased the formation of guanosine triphosphate-Ras with a simultaneous decrease in guanosine diphosphate-Ras levels in ECL but not in parietal cells. CONCLUSIONS: Although gastrin receptors are present in both ECL and parietal cells, they activate the Ras-MAP kinase pathway only in ECL cells.

Animals↗
PubMed1998

Insulin-like growth factor-I analogue prevents apoptosis mediated through an interleukin-1 beta converting enzyme (caspase-1)-like protease of cerebellar external granular layer neurons: developmental stage-specific mechanisms of neuronal cell death.

Using an organotypic slice culture system of neonatal rat cerebellum, we examined developmental stage-specific mechanisms of cell death of granule neurons. This culture system allows a serial process of granule neuron development including their proliferation during the early culture period and the proceeding migration from the external granular layer to the internal granular layer in the presence of a supraphysiological concentration (5 micrograms/ml) of insulin. Insulin deprivation induced apoptosis of granule neurons in external granular layer but not in internal granular layer. A truncated analogue of insulin-like growth factor-I (des (1-3) insulin-like growth factor-I) prevented this apoptosis at a concentration of 65-650 ng/ml. Some apoptotic granule neurons expressed proliferating cell nuclear antigen but not TAG-1, a marker protein of the postmitotic and premigratory granule neurons. Thus, this apoptosis occurred at a specific stage in granule neuron development: at the stage before TAG-1 expression and at least partly at the proliferative state. Ac-YVAD-CHO, an inhibitor of interleukin-1 beta converting enzyme (caspase-1)-like proteases, had a protective effect on this apoptosis. Interleukin-1 beta converting enzyme (caspase-1)-like protease activity increased under the apoptosis-induced condition. High concentration of K+, which is known to prevent granule neuron apoptosis in dissociated cultures, had a partial protective effect on this apoptosis. These findings suggest that (i) cerebellar granule neurons fall into apoptosis at the specific developmental stage unless stimulated by insulin-like growth factor-I (analogue), (ii) this apoptosis is mediated through an interleukin-1 beta converting enzyme-like protease, and (iii) this apoptosis consists of K(+)-sensitive and K(+)-insensitive components.

Animals↗
PubMed1998

Second malignancy following treatment of acute lymphoblastic leukemia in children.

Second malignancy is one of the serious late effects among long-term survivors of acute lymphoblastic leukemia (ALL) in children. Of 83 newly diagnosed pediatric ALL patients at our hospital between January 1980 and December 1995, four patients were found to have second malignancies. These included MDS/AML after B-ALL, rhabdomyosarcoma after early pre-B ALL, ependymoma after B-ALL, and astrocytoma after early pre-B ALL. The mean duration from initial ALL to second malignancy was 5.2 years. The possible causes of second malignancy in these patients are discussed in this report, along with a review of recent literature.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Inhibitors of acyl-CoA:cholesterol O-acyltransferase (ACAT). Part 1: identification and structure-activity relationships of a novel series of substituted N-alkyl-N-biphenylylmethyl-N'-arylureas.

A series of N-alkyl-N-biphenylylmethyl-N'-arylurea and related derivatives represented by 1 have been prepared and evaluated for their ability to inhibit acyl-CoA:cholesterol O-acyltransferase in vitro and to lower plasma cholesterol levels in cholesterol-fed rats in vivo. Linking of two phenyl groups via oxygen and introduction of fluorine at appropriate positions on the biphenyl moiety improved in vitro and in vivo activity. From this series of analogs, compound 40 (FR179254), which had potent in vitro potency (rabbit intestinal microsomes IC50 = 25 nM), showed excellent plasma cholesterol-lowering activity when administered via the diet (ED50 = 0.045 mg/kg). However, the hypocholesterolemic effect of this compound was moderate when dosed by oral gavage in PEG400 as a vehicle (ED50 = 5.3 mg/kg). Modification of the N'-aryl moiety led to the identification of compound 50 (FR182980) which was efficacious in both dosing models (ED50 = 0.034 mg/kg and 0.11 mg/kg, respectively).

Anilides↗
PubMed1998

Genetically engineered cells stably expressing cytochrome P450 and their application to mutagen assays.

Genetically engineered cells transiently and stably expressing cytochrome P450 (P450), a key enzyme for biotransformation of a wide variety of compounds, have provided new tools for investigation of P450 functions such as P450-mediated metabolic activation of chemicals. This review will focus on the development of mammalian cell lines stably expressing P450s and application to toxicology testings. Stable expression systems have an advantage over transient ones in that a series of the process from metabolic activation of test compounds to the appearance of toxicological consequences occurs entirely in the same intact cells. Indeed, many cell lines stably expressing a single form of mammalian P450 have been established so far and applied to cytotoxic or genotoxic assays, the endpoints of which contained mutations at hprt and other gene loci, chromosomal aberrations, sister chromatid exchanges, micronuclei, morphological transformation, and 32P-postlabeling. Analyses of metabolites of toxic substances have also been carried out, using the intact cells or microsomal fractions prepared from the cells. The stable expression systems clearly indicate the form of P450 enzyme capable of activating a certain chemical. More recently, coexpression of P450 together with other components of microsomal electron transfer systems such as NADPH-cytochrome P450 reductase has been successfully performed to increase the metabolic capacity of the heterologously expressed P450. In addition, to reconstruct the entire metabolic activation system for certain heterocyclic amines, cell lines which simultaneously express a form of human P450 and a phase II enzyme, N-acetyltransferase, were established. These cells were highly sensitive to some carcinogenic heterocyclic amines. In genetic toxicology, such a coexpression system for two or more enzymes will provide useful materials which mimic in vivo activation systems.

Animals↗
PubMed1998

Analysis of mutations at the DNA repair genes in acute childhood leukaemia.

Deficiency in DNA repair capability is considered to be responsible for oncogenesis. Hereditary and sporadic cancers in various tissues have been reported to have mutations at the DNA repair genes. In this study we analysed two excision repair genes (ERCC1 and XPCC) and two mismatch repair genes (hMSH2 and hMTH1) in the leukaemic blasts of newly diagnosed paediatric patients by use of reverse transcriptase (RT)-polymerase chain reaction (PCR). Analysis of the leukaemic blasts from 15 patients demonstrated no alterations at the XPCC, hMSH2 or hMTH1 genes. Blasts from one patient with acute mixed lineage leukaemia revealed an abnormally migrated product of the ERCC1 gene by RT-PCR. His leukaemic blasts showed a reduced expression of ERCC1 protein by Western blotting. Since bone marrow cells at remission showed only normally migrated product, the ERCC1 gene mutation was considered to be specific for the leukaemic blasts. This is the first report describing a mutation at the ERCC1 gene in acute childhood leukaemia.

Acute Disease↗
PubMed1998

Microglial NO induces delayed neuronal death following acute injury in the striatum.

We have established a novel injury model in the central nervous system by a stereotaxic injection of ethanol into rat striatum to induce necrosis. With this model, we clarify a function of inducible nitric oxide synthase (iNOS) in a healing mechanism around a necrotic lesion. A semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) revealed that the iNOS mRNA arose at 6 h, peaked at 24 h, and declined to a lower level 48 h after an intrastriatal 5-microL ethanol injection. From in situ hybridization, this iNOS mRNA was expressed in the area surrounding the injury. By immunohistochemistry, mononuclear cells at this boundary area of necrosis were stained with anti-iNOS antibody on the first day after the injury. These cells turned out to be reactive microglia from the positive staining of GSA-I-B4, ED-1 and OX-42. Haematoxylin-eosin (HE) staining showed that neurons in this boundary area gradually disappear up to 5 days after the injury with an increment of microglial cells, and this area became cavernous. Nuclei of neurons in this area were stained positive by the terminal deoxynucleotidyl-transferase-mediated dUTP-biotin nick end-labelling (TUNEL) assay on the first day after the injury. These TUNEL-positive neurons gradually disappeared toward the third day, while microglial cells increased. L-Ng-nitro-arginine methylester (L-NAME), a competitive NOS inhibitor, administration diminished the elimination of neurons by microglia in this boundary area surrounding necrosis. Microglial NO may act as a neurotoxic agent to eliminate damaged neurons near the necrosis in the form of delayed neuronal death, and may reintegrate the neuronal circuits with functionally intact neurons.

Animals↗
PubMed1998

Effect of acidic fibroblast growth factor (aFGF) on phagocytosis in mouse peritoneal macrophages.

The effects of acidic fibroblast growth factor (aFGF) on phagocytosis in peritoneal macrophages from thioglycollate-elicited mice were examined using flow cytometry. aFGF enhanced phagocytosis of fluorescein isothiocyanate-labeled latex particles in a dose-dependent manner. Basic fibroblast growth factor (bFGF) also enhanced phagocytosis. This study suggests that aFGF can modulate an important activity of macrophages.

Animals↗
PubMed1998

Antitumor effect of irinotecan hydrochloride (CPT-11) on human renal tumors heterotransplanted in nude mice.

BACKGROUND: There has been a paucity of antitumor drugs that are active against renal tumors. Irinotecan hydrochloride (CPT-11), a DNA topoisomerase type 1 inhibitor, has demonstrated antitumor activity against human tumors, however, no antitumor effect of CPT-11 on renal tumors has been reported. The antitumor effect of CPT-11 was investigated on 2 human renal tumors (OUR-10 and OUR-20) heterotransplanted into nude mice. METHODS: Tumor-bearing nude mice were given daily intraperitoneal injections of multiple anticancer drugs suspended in 0.2 mL of phosphate-buffered saline (PBS) 3 times at 3-day intervals. Control mice were injected with 0.2 mL of PBS. The antitumor effects were evaluated by calculating the T/C ratio (treated tumors/controls) of the tumor volume. RESULTS: Among the 10 anticancer drugs tested, 50 mg/kg of CPT-11 showed an active antitumor effect on OUR-20 (T/C ratio 34). However, all drugs tested on OUR-10 failed to show antitumor activity. CONCLUSION: Since CPT-11 was effective in 1 of 2 renal tumors examined without severe toxicity, this drug could be a candidate for chemotherapy of renal cell carcinoma.

Animals↗
PubMed1998

Distal posterior cerebral artery aneurysm associated with multiple aneurysms.

True congenital peripheral aneurysms of the cerebral arteries are rare and may constitute a special entity. We report a rare case of nonmycotic peripheral aneurysm of the posterior cerebral artery (PCA) found in association with aneurysms of distal middle cerebral artery (MCA), junction between basilar artery (BA) and superior cerebellar artery (SCA) and MCA trunk. Our present case was a 37-year-old man with a history of abrupt loss of consciousness. Cerebral angiography revealed a right PCA aneurysm originating at the junction between the trunk of the PCA and the posterior temporal branch, and also aneurysms of the right distal MCA, at the right BA-SCA junction and at the trunk of right MCA just distal to the anterior temporal artery. Distal PCA aneurysm causing subarachnoid hemorrhage was successfully clipped and all the other aneurysms were treated in a one-stage procedure. Pathological examination of the surgically excised distal PCA aneurysmal sac demonstrated no infectious etiology. There have not been any similar cases showing an association of vascular anomalies with distal PCA aneurysm. This is the only reported case with the association of nonmycotic peripheral aneurysms involving the MCA and PCA.

Adult↗
PubMed1998

Effects of a neutrophil elastase inhibitor (ONO-5046) on acute pulmonary injury induced by tumor necrosis factor alpha (TNFalpha) and activated neutrophils in isolated perfused rabbit lungs.

The aim of this study was to examine the effect of ONO-5046, a neutrophil elastase (NE) inhibitor, on a model of acute lung injury induced by tumor necrosis factor alpha (TNFalpha) and phorbol myristate acetate (PMA)-activated neutrophils in isolated perfused rabbit lungs. 120 min after TNFalpha (4,000 JRU/ml) was injected into the pulmonary artery (PA), 5 x 10(7) PMA-stimulated neutrophils were infused into the PA together with 1251-rabbit serum albumin (RSA). In the ONO-5046-treated group (ONO), ONO-5046 (20 mg/kg/h) was continuously infused during the experimental period from 30 min prior to neutrophil administration. Saline, the ONO-5046 vehicle, was infused instead of ONO-5046 in the positive control group (ALD) and nonactivated neutrophils were infused without TNFalpha in the negative control group (Cont). PA pressure was monitored over a 240 min period, and bronchoalveolar lavage (BAL) was performed at the end of the experiment. Lung tissues were examined immunohistochemically for the expression of thrombomodulin (TM). The levels of TM in the perfusate were also measured by ELISA and the radioactivities in the BAL fluid, lung tissue and perfusate were determined to calculate the permeability index (PI) as an indicator of alveolar septal or vascular endothelial damage. The rabbit lungs infused with ONO-5046 showed slower and less increases in PA pressure compared with ALD group. The PI was significantly higher in ALD group (PI[BAL] = 0.028 +/- 0.014, PI[LUNG] = 0.04 +/- 0.003) than Cont (PI[BAL] = 0.002 +/- 0.001, PI[LUNG] = 0.015 +/- 0.003) and ONO group (PI[BAL] = 0.004 +/- 0.003, PI[LUNG] = 0.028 +/- 0.003 (p < 0.05). ALD group had higher TM levels in the perfusate and showed decreased expression of TM on the vascular endothelium compared to Cont and ONO group, suggesting that there was shedding of TM on endothelium and ONO-5046 attenuated a shedding of TM. In conclusion, ONO-5046 attenuated acute lung injury by inhibiting the alveolar epithelial and vascular endothelial injury triggered by activated neutrophils. NE appears to play an important role in the neutrophil-induced increase of pulmonary epithelial and microvascular permeability observed in acute lung injury.

Animals↗
PubMed1998

[Apoptosis and microglia].

Microglia, macrophage-like cells in the central nervous system (CNS), are multi-functional cells; they play an important role in removal of dead cells or their remnants by phagocytosis in the CNS degeneration and are one of important cells in the CNS cytokine network to produce and respond to a variety of cytokines. Although little is known about microglia in the normal CNS, it is obvious that they are quickly activated in all acute pathological events including apoptosis, neurodegeneration and inflammation. Activation of microglia in apoptosis is a double-edged response; under severe apoptotic conditions microglia act as scavengers removing tissue debris and inducing apoptosis in damaged cells, whereas in more subtle injury they exert a surveillance function and might play a protective role. The transformation of resting microglia into full blown phagocytes is strictly regulated. To understand molecular basis of controlling mechanisms of microglia in apoptosis, the study will need in vivo models. For such purpose, we developed the brain-targeting gene delivery system using immortalized microglia, which can facilitate investigation into the roles of particular microglial genes in apoptosis and gene therapy of several brain disorders.

Animals↗
PubMed1998

Serological survey of antibody to Neospora caninum in Japanese dogs.

Prevalence of antibody to Neospora caninum (NC) in Japanese dogs were examined. The antibody was positive in 15 of 48 dogs (31.3%) reared in the dairy farms that had case of the abortions due to NC infection or had the cattle seropositive to NC, whereas the prevalence was 7.1% (14 of 198 dogs) among the dogs kept in urban areas. In one dog breeder, all 17 Shetland sheepdogs older than 7 months were seropositive, and one pup was diagnosed as neosporosis 2 months before the first serological examination. The antibody titers of the dogs kept at this breeder were almost unchanged for 1.5 years. Serological evidence of the dogs in the dairy farms and urban areas indicates the transmission of NC between dogs and cattle. Also serological results of the dogs in one breeder may suggest the potential horizontal transmission among dogs.

Abortion, Veterinary↗
PubMed1998

Pulmonary pseudallescherioma associated with systemic lupus erythematosus.

We report a case of fungus ball due to Pseudallescheria boydii (pseudallescherioma) associated with systemic lupus erythematosus. Direct microscopical examination revealed a fungus with broad septate hyphae resembling Aspergillus and the fungus was identified as P. boydii on culture. Surgical resection was required to control episodes of hemoptysis. Cases of pulmonary pseudallescheriasis are rare, especially in Japan. However, some cases previously diagnosed as pulmonary aspergillosis may have been found to be caused by P. boydii, if adequate culture studies had been conducted. Unlike Aspergillus, P. boydii is resistant to amphotericin B. Therefore, we emphasize the importance of a correct diagnosis based on culture examination.

Adult↗
PubMed1998

Propentofylline inhibits production of TNFalpha and infection of LP-BM5 murine leukemia virus in glial cells.

We examined the effects of a xanthine derivative, propentofylline, on TNFalpha production by glial cells and on infection ofglial cells with a murine leukemia virus, LP-BM5, which induces murine AIDS in susceptible mice. Propentofylline suppressed TNFalpha production in glial cells and also effectively suppressed infection ofglial cells with LP-BM5 in vitro. Addition ofTNFalpha, but not IL-1 or IL-6, abolished the suppressive effects ofpropentofylline. Anti-TNFalpha antibody also suppressed infection of LP-BM5 in these cells. These findings suggest that propentofylline suppressed LP-BM5 infection in glial cells by suppressing TNFalpha production by these cells. Because propentofylline reportedly passes through the blood-brain barrier, it may be useful in the treatment of central nervous system involvement by HIV infection or neurological diseases in which TNFalpha plays a causative role, such as multiple sclerosis.

Animals↗