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Biomedical subjects

A Nishikawa

Publications and source records attributed to A Nishikawa.

At least 37 records · Page 2Linked to original sources
PubMed2001

Promotion of chemically induced rat esophageal tumorigenesis with post-initiation ethanol modification.

Post-initiation ethanol modification on N-nitrosomethylbenzylamine (NMBA)-induced rat esophageal carcinogenesis model was investigated in male, 6-week-old, F344 rats that received s.c. injections, 3 times per week, of 0.5 mg/kg NMBA for the first 5 weeks and then were treated with 0% (Group 1), 3.3% (Group 2), and 10% (Group 3) ethanol in the drinking water for up to 20 weeks. Group 4 received 10% ethanol without NMBA administration and Group 5 was maintained without any chemical treatment. There were no statistical differences in the incidence and multiplicity of esophageal tumors among Groups 1 to 3. However, the multiplicity of hyperplasias was statistically greater in Group 3 than in Groups 1 or 2. Esophageal epithelia of all rats in Groups 4 and 5 demonstrated a normal histology. BrdU labelling indices of tumors and hyperplasias in NMBA-treated groups were essentially similar, although cycline D1 was overexpressed to a greater extent in tumors and also hyperplasias of Group 3 than in Groups 1 or 2. The results indicated ethanol to exert weak promotion effects through cycline D1 overexpression on rat esophageal tumorigenesis initiated with NMBA.

Animals↗
PubMed2001

Invasion of human respiratory epithelial cells by Bordetella pertussis: possible role for a filamentous hemagglutinin Arg-Gly-Asp sequence and alpha5beta1 integrin.

Bordetella pertussis, the agent of whooping cough, is capable of invading human respiratory epithelial cells. In this study, we investigated the mechanisms by which B. pertussis invades the human lung epithelial cell line A549 and normal human bronchial epithelial (NHBE) cells. In vitro adhesion and invasion assays using both cell types with a virulent B. pertussis strain and its isogenic mutants revealed profound defects in a mutant deficient in filamentous hemagglutinin (FHA) expression. In addition, a mutant in which an FHA Arg-Gly-Asp (RGD) site had been changed to Arg-Ala-Asp had significantly diminished invasiveness, although its adhesiveness was comparable to that of the parental strain. Furthermore, a synthetic RGD-containing hexapeptide inhibited invasion of both cell types by the virulent strain. These results demonstrate that an RGD sequence of FHA is involved in B. pertussis invasion of epithelial cells in vitro. Monoclonal antibodies directed against human alpha5beta1 integrin, but not other integrins, blocked invasion, indicating that this integrin is involved in B. pertussis invasion. Taken together, these findings suggest that B. pertussis FHA may promote invasion of human respiratory epithelial cells through the interaction of its RGD sequence with host cell alpha5beta1 integrin.

Adhesins, Bacterial↗
PubMed2001

A repeated 28-day oral dose toxicity study of methoxychlor in rats, based on the 'enhanced OECD test guideline 407' for screening endocrine-disrupting chemicals.

In association with the international validation project to establish an OECD Enhanced Test Guideline 407, we performed a 28-day repeated-dose toxicity study of methoxychlor, a chlorinated hydrocarbon pesticide with pro-estrogenic and anti-androgenic activities. Attention was paid to the sensitivity of certain additional parameters for detecting endocrine related effects of endocrine disrupting chemicals based on the existing TG 407. Seven-week-old Crj:CD(SD)IGS rats were allocated to one of four groups, each consisting often males and ten females, and methoxychlor was administered once daily by gavage at doses of 0 (control), 20, 100 or 500 mg/kg body weight per day. Male rats were killed on the day after the 28th administration. Female rats were killed on the day of the diestrus stage during 4 days after the 28th administration. Male rats receiving methoxychlor showed mainly atrophy of mammary acinus in the 20 mg/ kg and higher groups, together with decreases in prostate and seminal vesicle weights, and atrophy of epididymis, prostate, seminal vesicle and coagulating gland in the 100 and 500 mg/kg groups. In addition, decrease in serum testosterone level, increase in follicle-stimulating hormone level, decrease in testis and epididymis weights, atrophy of semiferous tubules and Leydig cells, decrease in the number of sperm in the caudal epididymis and their motility were observed in the 500 mg/kg group. Female rats receiving methoxychlor showed mainly abnormal estrous cycles, decrease in serum luteinizing hormone level, decrease in ovary weight, proliferation of mammary acinus, atrophy of ovary due to decrease in follicles and corpus luteum in histopathology, hypertrophy of endometrial epithelium of uterus and vagina epithelium in the 100 and 500 mg/kg groups. Among the parameters tested in the present experimental system, effects of methoxychlor on endocrine-related organs were detected with regard to serum hormone, organ weights, histopathological examination in both sexes, estrus cycle in females and sperm examination in males. Based on these results, a no-observed-adverse-effect level (NOAEL) in the present study was estimated to be below 20 mg/kg per day. In particular, the adverse effects were effectively detected in organ weights of accessory sex organs and histopathological examination.

Administration, Oral↗
PubMed2001

Cyclic changes in expression of mRNA of vascular endothelial growth factor, its receptors Flt-1 and KDR/Flk-1, and Ets-1 in human corpora lutea.

OBJECTIVE: To evaluate the expression of mRNA of vascular endothelial growth factor (VEGF), its receptors Flt-1 and KDR/Flk-1, and Ets-1 in human corpora lutea. DESIGN: Prospective laboratory study. SETTING: University hospital in Japan. PATIENT(S): Women with regular menstrual cycles who underwent hysterectomy. INTERVENTION(S): Fifteen corpora lutea were obtained during hysterectomy (5 in the early luteal phase, 5 in the mid-luteal phase, and 5 in the late luteal phase). MAIN OUTCOME MEASURE(S): Expression of VEGF, Flt-1, KDR/Flk-1, and Ets-1 in human corpora lutea on northern blot analysis or immunohistochemistry. RESULT(S): Human corpora lutea in early luteal phase and mid-luteal phase had high VEGF mRNA expression. Expression of VEGF mRNA was significantly reduced in the late luteal phase. Immunohistochemistry showed that VEGF protein was expressed mainly in granulosa lutein cells and faintly in thecal lutein cells. Staining of VEGF protein was decreased in human corpora lutea in the late luteal phase. Expression of Flt-1 and KDR/Flk-1 mRNA was increased in the early luteal phase and mid-luteal phase and decreased in the late luteal phase. Immunohistochemistry showed that Flt-1 and KDR/Flk-1 proteins were expressed mainly in granulosa lutein cells and faintly in thecal lutein cells and endothelial cells in the early luteal phase and mid-luteal phase; their protein staining was reduced in the late luteal phase. Expression of Ets-1 mRNA changed similarly to VEGF and its receptor mRNA in human corpora lutea during the luteal phase. CONCLUSION(S): Levels of mRNA of VEGF and its receptors Flt-1 and KDR/Flk-1 in human luteal cells may be related to luteal function.

Blotting, Northern↗
PubMed2001

Oral toxicity of a tocotrienol preparation in rats.

Tocotrienols are added as antioxidants to food. As there have been no reports of toxicological evaluation, a 13-week oral toxicity study was performed in Fischer 344 rats of both sexes at dose levels of 0 (group 1), 0.19 (group 2), 0.75 (group 3) and 3% (group 4) of a preparation in powdered diet. Suppression of body weight gain was observed in group 4 males. On hematological examination, significant decrease in mean corpuscular volume (MCV) was observed in all treated males. Platelets were significantly reduced in group 3 and 4 males. Hemoglobin concentration, MCV, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration were significantly decreased in group 3 and 4 females and hematocrit in group 4 females. On serum biochemical examination, increase in the albumin/globulin ratio (A/G) and alkaline phosphatase in all treated males, elevated alanine transaminase in group 4 of both sexes and increases in asparagine transaminase and gamma-glutamyl transaminase in group 4 females were observed. With regard to relative organ weights, liver weights in group 4 of both sexes and adrenal weights in all treated males demonstrated an increase, and ovary and uterus weights in group 4 females were reduced. Histopathologically, slight hepatocellular hypertrophy in group 3 and 4 males, and reduction of cytoplasmic vacuolation in the adrenal cortical region in group 4 males were observed. Because of pathological changes in male liver and hematological changes in females, the no-observed-adverse-effect level (NOAEL) was concluded to be 0.19% in the diet (120 mg/kg body weight/day for male rats and 130 mg/kg body weight/day for female rats). As a decrease in MCV, an increase in the A/G, elevation of alkaline phosphatase and increase in adrenal weight were observed in all treated males, a no-observed-effect level (NOEL) could not be determined in this examination.

Administration, Oral↗
PubMed2001

Purification and characterization of pyruvate kinase from lamprey (Entosphenus japonicus) muscle.

Pyruvate kinase from skeletal muscle of lamprey (Entosphenus japonicus), which is one of the most primitive living vertebrates, has been purified by approxImately 110-fold. The isolation procedure includes chromatography on Phosphocellulose, Phenyl-5PW, and Sephacryl S-300. Sodium dodecyl sulfate gel electrophoresis shows 59000 as the deduced subunit molecular weight and gel filtration shows 232000 as the tetramer of the subunits. The apparent Km for phosphoenolpyruvate and ADP are 0.41 mM and 0.31 mM at pH 7.4, respectively, when the purified enzyme is saturated with the second substrate. When the enzyme is activated in the presence of fructose-1,6-diphosphate, the Km for PEP changes to 0.087 mM, and the Hill coefficient changes from 1.3 to 0.98.

Acrylic Resins↗
PubMed2001

Structural studies of a cell wall polysaccharide of Trichosporon asahii containing antigen II.

The structure of a cell-wall polysaccharide containing antigen II from Trichosporon asahii was investigated. A purified glucuronoxylomannan (GXM) antigen was found to contain O-acetyl groups that contribute to the serological reactivity. The structure of GXM was analyzed by partial acid hydrolysis, methylation analysis, controlled Smith degradation, NMR studies, and fluorophore-assisted carbohydrate electrophoresis. GXM has an alpha-(1-->3)-D-mannan backbone with a beta-D-glucopyranosyluronic acid residue bound to O-2 of a mannopyranosyl residue and the same number of beta-D-xylopyranosyl residues as mannose. Side chains of beta-D-xylopyranosyl-D-xylopyranose, forming a nonreducing terminus, and beta-D-xylopyranosyl residues were attached to O-2, O-4, and O-6 of the mannose residues.

Antigens, Surface↗
PubMed2001

Lipopolysaccharide of Haemophilus influenzae induces interleukin-5 mRNA expression in human peripheral blood mononuclear cells.

Haemophilus influenzae is the bacterial species most often isolated from sputum of patients with chronic obstructive pulmonary disease (COPD). In this study, we examined the induction of interleukin-5 (IL-5) mRNA expression in human peripheral blood mononuclear cells (PBMC) stimulated with lipopolysaccharide (LPS) from H. influenzae to try to predict the effect of H. influenzae infection on the eosinophilic inflammation in COPD. Detection of IL-5 mRNA by RT-PCR showed that LPS from H. influenzae induced IL-5 mRNA expression in PBMC at a concentration of 1 microg/ml. Furthermore, the level of expression of IL-5 mRNA induced by LPS correlated with the amount of IL-5 protein in the culture supernatant. Inhibition of LPS-induced IL-5 mRNA expression by anti-CD14 antibody and diminution of this in a CD3(+) -cell-depleted fraction of PBMC, respectively, suggested that CD14 molecules were required for the increase in IL-5 mRNA and that T lymphocytes were the principal source of IL-5 mRNA expression in PBMC. Briefly, the IL-5 mRNA expression induced by LPS would be based on LPS-activated monocytes interacting with T lymphocytes to produce IL-5. These results may explain the role that colonization with H. influenzae plays in eosinophilic inflammation in patients with COPD.

Base Sequence↗
PubMed2001

Lysyl oxidase and MMP-2 expression in dehydroepiandrosterone-induced polycystic ovary in rats.

Polycystic ovary syndrome (PCOS) is characterized by cystogenesis; however, the cause of this cystogenesis is unknown. At ovulation, preovulatory collagenolytic activities in the ovarian follicles increase and various proteinases are needed to degrade the tissues surrounding the follicles. To clarify the roles of enzymes in collagen degradation of the follicular wall of polycystic ovary (PCO) in relation to the cystogenesis, we examined expression of lysyl oxidase (LOX), which initiates cross-link formation of the collagen and elastin in the extracellular matrix, and expression of matrix metalloproteinases (MMPs) in ovaries of model rats with PCO induced by dehydroepiandrosterone (DHEA) compared with MMP expression in control rats. DHEA treatment increased LOX mRNA expression to more than three times the control value (P: < 0.01). MMP-2 mRNA expression in control rats was threefold greater than that in the DHEA-induced group (P: < 0.05). Expression of both latent and active forms of MMP-2 in controls was more than twice that in the DHEA-induced group (P: < 0.05) as shown by Western blotting, and expression of the active form of MMP-2 was also twice as high in the controls as in the DHEA-treated group (P: < 0.05) as shown by zymography. Our results suggest that depression of MMP-2 activity and increased LOX expression may be one of the causes of the cystogenesis of PCO.

Androstenedione↗
PubMed2001

Involvement of lipid peroxidation in spontaneous pancreatitis in WBN/Kob rats.

To cast light on the mechanisms underlying development of spontaneous pancreatitis lesions, tissues from WBN/Kob rats at various ages were histopathologically and immunohistochemically investigated with special reference to the existence of the lipid peroxidation products 4-hydroxy-2-nonenal (HNE), 4-hydroxy-2-hexenal (HHE), and malondialdehyde (MDA). Male 4-20-week-old WBN/Kob rats were killed to allow sampling of pancreatic tissues, which were fixed in cold acetone and 10% neutral-buffered formalin. and then processed for routine histopathology as well as immunohistochemistry for proteins modified by HNE, HHE, and MDA. Although no remarkable histologic changes were noted in younger animals, edema, hemorrhage, inflammatory cell infiltration, fibrosis, vacuolation of acinar cells, and ductular proliferation were observed in exocrine pancreatic tissue from animals at 10-15 weeks of age. In animals aged 20 weeks, the lesions had progressed remarkably and deposits of hemosiderin were apparent with fibrosis. Immunohistochemical examination for lipid peroxidation product-modified proteins showed HNE and MDA to be negative in all pancreatic tissues, but HHE was positive in the areas involving atrophy of acinar cells and fibrosis in the islets. The results of the present study thus provide support for the conclusion that lipid peroxidation during spontaneous pancreatitis in WBN/Kob rats may possibly be involved in the development of diabetes in this model.

Aging↗
PubMed2001

Lack of effect of soy isoflavone on thyroid hyperplasia in rats receiving an iodine-deficient diet.

We have reported a dramatic synergism between soy intake and iodine deficiency regarding induction of thyroid hyperplasia in rats. Because isoflavones are active constituents of soybeans, in the present study, their possible contribution was examined. Female F344 rats were divided into 8 groups, exposed to diet containing a 0.2% soy isoflavone mixture (SI), 0.2% SI + iodine deficiency (ID), 0.04% SI, 0.04% SI + ID, 20% defatted soybean (DS) alone, 20% DS + ID, ID alone or basal diet alone for 5 weeks. Thyroid weight was not influenced by SI, but was increased by the ID and DS diets with a further significant increment in the DS + ID group (P < 0.01). Compared to the control value, serum T(4) was significantly (P < 0.01) increased by 20% DS alone and decreased in all groups given the ID treatment (P < 0.001). Serum thyroid stimulating hormone (TSH) level was increased by ID, and further enhanced by DS (P < 0.01) but not SI. Histopathologically, diffuse hypertrophy and / or hyperplasia of thyroid follicles were observed in the ID-treated groups, the severity being enhanced by DS but not SI. Proliferating cell nuclear antigen labeling indices (%) were elevated in the ID diet groups and again enhanced by DS, but not SI. These results thus suggest that isoflavones may not be involved in the mechanisms underlying the synergistic goitrogenic effect of soybean with iodine deficiency.

Animals↗
PubMed2001

Synergistic effects of high-dose soybean intake with iodine deficiency, but not sulfadimethoxine or phenobarbital, on rat thyroid proliferation.

The specificity and dose dependence of the synergistic effects of soybean intake with iodine deficiency on the induction of thyroid proliferation were investigated in female F344 rats. In the first experiment, rats were divided into 6 groups, each consisting of 5 animals, and fed a basal diet containing 20% gluten, an iodine-deficient basal diet alone or an iodine-deficient diet containing 0.2%, 1.0%, 5.0% or 25% defatted soybean for 5 weeks. Soybean feeding synergistically induced thyroid hyperplasias with iodine deficiency only at the 25% dose. In the second experiment, rats were also divided into 6 groups, each consisting of 5 animals, and fed a basal diet, a diet containing 20% defatted soybean, 0.025% sulfadimethoxine (SDM), 20% defatted soybean + 0.025% SDM, 0.05% phenobarbital (PB) or 20% defatted soybean + 0.05% PB for 5 weeks. The SDM treatments significantly (P < 0.05 - 0.01) increased the thyroid weights, but this increase rate was less prominent in the SDM + soybean group than in the SDM alone group. The PB treatment was also associated with a tendency for increase in thyroid weight, but again this was smaller in the PB + soybean group than in the PB alone group. Although the SDM or PB treatments reduced the serum triiodothyronine and thyroxine levels and consequently increased the serum thyroid-stimulating hormone (TSH) levels, the soybean feeding did not affect or rather attenuated these changes. Our results clearly indicate that soybean feeding does not synergistically enhance the effects of SDM or PB on the rat thyroid. Thus it can be concluded that soybean intake specifically interacts with iodine deficiency in induction of thyroid proliferative lesions in rats, only at high doses.

Animals↗
PubMed2001

Molecular analysis of Malassezia microflora on the skin of atopic dermatitis patients and healthy subjects.

Members of the genus Malassezia, lipophilic yeasts, are considered to be one of the exacerbating factors in atopic dermatitis (AD). We examined variation in cutaneous colonization by Malassezia species in AD patients and compared it with variation in healthy subjects. Samples were collected by applying transparent dressings to the skin lesions of AD patients. DNA was extracted directly from the dressings and amplified in a specific nested PCR assay. Malassezia-specific DNA was detected in all samples obtained from 32 AD patients. In particular, Malassezia globosa and M. restricta were detected in approximately 90% of the AD patients and M. furfur and M. sympodialis were detected in approximately 40% of the cases. The detection rate was not dependent on the type of skin lesion. In healthy subjects, Malassezia DNA was detected in 78% of the samples, among which M. globosa, M. restricta, and M. sympodialis were detected at frequencies ranging from 44 to 61%, with M. furfur at 11%. The diversity of Malassezia species found in AD patients was greater (2.7 species detected in each individual) than that found in healthy subjects (1.8 species per individual). Our results suggest that M. furfur, M. globosa, M. restricta, and M. sympodialis are common inhabitants of the skin of both AD patients and healthy subjects, while the skin microflora of AD patients shows more diversity than that of healthy subjects. To our knowledge, this is the first report of the use of a nested PCR as an alternative to fungal culture for analysis of the distribution of cutaneous Malassezia spp.

Adult↗
PubMed2001

Genetic diversity and biochemical characteristics of Trichosporon asahii isolated from clinical specimens, houses of patients with summer-type-hypersensitivity pneumonitis, and environmental materials.

Trichosporon asahii, which is distributed in the environment, is the major causative agent of the opportunistic infection trichosporonosis, and it also causes summer-type hypersensitivity pneumonitis (SHP). Random amplification of polymorphic DNA analysis was used to determine the intraspecies diversity of 39 T. asahii isolates from clinical specimens, SHP patients' houses, and environmental materials. The three primers used revealed 46 polymorphic bands. A phenogram was generated by the unweighted pair-group method with arithmetic mean. Clinical isolates formed a cluster, characterized by a 90% matching coefficient, but they did not cluster with strains isolated from SHP patients' houses or environmental sources. In addition, the biochemical characteristics of 86 strains from three sources were examined with 31 compounds using an ID32C kit, and a phenogram was constructed. The phenogram consisted of three major clusters. Cluster I included most of the clinical SHP isolates, and cluster II included most of the environmental isolates. Cluster III contained only one strain. A remarkable difference was found in the abilities of the strains belonging to clusters I and II to utilize six compounds. These results suggest that the genetic diversity and biochemical characteristics of T. asahii seem to be related to the source of the isolate. We also found a specific DNA fragment for the clinical isolates and strains isolated from SHP patients' houses.

Alveolitis, Extrinsic Allergic↗
PubMed2001

Flow-through chemiluminescence sensor using immobilized histamine oxidase from Arthrobacter crystallopoietes KAIT-B-007 and peroxidase for selective determination of histamine.

A flow sensor with immobilized oxidases is proposed for the determination of histamine in fish meat. Chemiluminometric measurement of histamine was based on the luminol reaction with hydrogen peroxide produced by immobilized histamine oxidase (EC 1.4.3.-.) and peroxidase (EC 1.11.1.7.) within a flow cell. Histamine oxidase was found in cells of Arthrobacter crystallopoietes KAIT-B-007 isolated from soil. The oxidase and peroxidase were coimmobilized covalently on tresylated hydrophilic vinyl polymer beads and packed into transparent PTFE; the tubing was used as the flow cell. One assay for histamine was done at intervals of 2 min without carryover. The calibration curve for histamine was linear from 0.1 microM to 50 microM. The response was reproducible within 1.25% of the relative standard deviation for 115-replicate injections of 50 microM histamine. The sensor system was applied to the determination of histamine in fish meat extracts.

Amine Oxidase (Copper-Containing)↗
PubMed2001

[Molecular analysis of malassezia microflora on the skin of atopic dermatitis patients and healthy subjects].

We compared cutaneous colonization levels of Malassezia species in patients with AD and healthy subjects using nested PCR. Malassezia-specific DNA was detected in all 32 of the patients with AD. M. globosa and M. restricta were detected in approximately 90% of these patients, with M. furfur and M. sympodialis being detected in approximately 40% of the cases. In healthy subjects, Malassezia DNA was detected in 78% of the samples, M. globosa, M. restricta and M. sympodialis were detected at frequencies ranging from 44 to 61%, and M. furfur was found in 11% of healthy subjects. Our results suggest that M. furfur, M. globosa, M. restricta and M. sympodialis are common inhabitants of the skin of both AD patients and healthy subjects, while the skin microflora of patients with AD shows more diversity than that of healthy subjects.

Dermatitis, Atopic↗
PubMed2001

Reporter gene transgenic mice as a tool for analyzing the molecular mechanisms underlying experimental carcinogenesis.

Carcinogenic compounds are classified into 2 categories, genotoxic and non-genotoxic, which are basically judged from in vitro genotoxicity data. However, it is well documented that genotoxicants do not necessarily exert in vivo carcinogenicity in rodents, partly because of a discrepancy between in vitro and in vivo mutagenicities. Recently, transgenic animal models with reporter genes such as lacI, lacZ and gpt have been developed as a tool for assessing in vivo mutagenicity as well as carcinogenicity. In this article, data using lacI transgenic mice and gpt delta mice are presented and their application is discussed. In lacI transgenic mice, dimethylnitrosamine (DMN) treatment significantly increased lacI mutant frequency (MF) in the liver, kidenys and lungs, but not in other non-target organs. Repeated dose ip administration of DMN was more effective than single dose treatment in the induction of lacI MF. The spectrum of mutant plaques induced by DMN was characterized by deletions as well as GC to AT base transitions. The remaining mice receiving DMN proved to have liver adenomas at a high frequency after 78 weeks. Meanwhile, dietary 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MelQx) significantly increased lacI and gpt MFs in the liver and colon. The characteristic spectrum of mutant plaques induced by MeIQx was a GC to TA base transversion in both the lacI and gpt mutations. Our results thus strongly suggest that these reporter gene transgenic animal models could offer a useful tool for analyzing molecular mechanisms underlying experimental carcinogenesis and for assessing the carcinogenic risk of environmental chemicals.

Animals↗