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Biomedical subjects

H Shimada

Publications and source records attributed to H Shimada.

At least 307 records · Page 17Linked to original sources
PubMed1998

Lack of mutagenicity of levofloxacin in lacZ transgenic mice.

The mutagenic effects of levofloxacin in lacZ transgenic mice (Muta Mouse) have been investigated. Male Muta-Mouse mice were administered levofloxacin i.p. at a dose of 300 or 600 mg/kg. The higher dose corresponded to half the LD50 of the compound in ddY strain mice. The mutant frequencies in the bone marrow, liver (day 10 only), testis and sperm were examined by the positive selection method for lacZ mutations on days 1 and 10 after treatment. Levofloxacin did not induce any statistically significant increase in mutant frequency in any of the examined tissues at either dose level or at either sampling time. The mutant frequency increases over the spontaneous values in the bone marrow, liver, testis and sperm were 1.0- to 1.2-fold, 0.9-fold, 0.5- to 1.0-fold and 0.9- to 1.3-fold respectively. N-Ethyl-N-nitrosourea (100 mg/kg as a positive control), on the other hand, induced significant increases in mutant frequencies in both somatic cells (bone marrow and liver) and germ cells (testis and sperm) on day 10 after treatment. The mutagenic potency for ENU was bone marrow >> liver approximately testis approximately sperm (50.1-fold, 3.4-fold, 2.9-fold and 2.3-fold respectively over the spontaneous values). Levofloxacin was not mutagenic in the lacZ transgenic mice under the present experimental conditions.

Animals↗
PubMed1998

Growth, pigmentation, and expression of the puf and puc operons in a light-responding-repressor (SPB)-disrupted Rhodobacter sphaeroides.

We previously cloned a trans-repressor, SPB, for the puf operon of Rhodobacter sphaeroides (Shimada et al. 1996) and revealed that SPB was a putative genetic counterpart to HvrA in Rhodobacter capsulatus, a trans-activator for the puf and puh operons (Mizoguchi et al. 1997). In this study we constructed a spb-disrupted R. sphaeroides, strain L-7, to elucidate the function of SPB. This disruption of the spb gene increased the photosynthetic growth rate and the cellular levels of photopigments under low-intensity light conditions. The disruption also derepressed the expression of the puf and puc operons under high-intensity light conditions. In strain L-7, however, strong illumination still reduced the cellular levels of photopigments as it did in the wild strain, suggesting that SPB did not directly affect the formation of photopigments. These results support our previous suggestion that SPB functions as a high-light repressor for puf operon in R. sphaeroides in striking contrast to HvrA, which is a low-light activator for puf and puh operons in R. capsulatus, even though SPB and HvrA are highly homologous. Disruption of spb gene had no effect on the oxygen-mediated regulation of the pigmentation or the expression of puf and puc operons.

Bacterial Proteins↗
PubMed1998

Detection of brain tumor invasion and micrometastasis in vivo by expression of enhanced green fluorescent protein.

OBJECTIVE: To determine whether fluorescence from human brain tumor cells transfected with the enhanced green fluorescent protein (EGFP) gene in vitro and xenotransplanted into the brain of nude mice would permit the detection of brain tumor invasion and metastasis in vivo. METHODS: Daoy medulloblastoma cells were transfected with a long terminal repeat-based retroviral vector containing the EGFP gene. Stable EGFP-expressing clones were isolated and stereotactically injected into the frontal cortex of nude mice. Four weeks later, whole brain sections were examined using fluorescence microscopy, immunohistochemistry, and routine hematoxylin and eosin staining for the visualization and detection of tumor cell invasion and metastasis. RESULTS: We demonstrate that EGFP-transduced Daoy cells maintain stable high-level EGFP expression in the central nervous system during their growth in vivo. EGFP fluorescence clearly demarcated the primary tumor margins and readily allowed for the visualization of distant micrometastases and local invasion on the single-cell level. Small metastatic and locally invasive foci, including those immediately adjacent to the tumor's leading invasive edge, were virtually undetectable by routine hematoxylin and eosin staining and immunohistochemistry. EGFP expression also persisted in vitro after cell reculture from brain tissue extracts. CONCLUSION: We show, for the first time, that EGFP-transduced human brain tumor cells can be visualized by fluorescence microscopy after intracerebral implantation. This method is superior to routine hematoxylin and eosin staining and immunohistochemistry for the detection and study of physiologically relevant patterns of brain tumor invasion and metastasis in vivo.

Animals↗
PubMed1998

Preservation of pancreatic islets in rodent models.

Islet-cell transplantation has some advantages over vascularized pancreas transplantation, but data from clinical islet cells transplantation have shown that some serious problems need to be overcome. One of them is the storage of islet cells. We investigated methods of preserving islet cells using culture-preservation and cryopreservation. Cryopreservation is thought to be effective for long-term preservation of large quantities of islet cells, because they can be cryopreserved without loss of their physiologic activity using a relatively rapid cooling rate of 25 degrees C/min. Moreover, in the allogenic transplantation models of cryopreservation of dissociated islet cells, there was a significant prolongation of survival time. These results suggest that cryopreservation of islet cells involves not only variable preservation methods but may also lead to a modification of graft immunogenicity.

Animals↗
PubMed1998

Uterine cervical dysplasia and cancer: identification of c-myc status by quantitative polymerase chain reaction.

The c-myc oncogene status was determined in patients with nondysplasia (ND; 9 patients), low-grade squamous intraepithelial lesion (LGSIL; 12 patients), high-grade squamous intraepithelial lesion (HGSIL; 21 patients) and invasive squamous cell carcinoma (ISCC; 20 patients) of uterine cervix using fluorescent quantitative polymerase chain reaction (PCR). In the same paraffin-embedded specimens, other potential risk factors were also screened: human papillomavirus (HPV) infection, Ha-ras codon 12 mutation, DNA aneuploidy. Gene amplification, identified as c-myc copy numbers greater than the mean value +2 SD of patients with ND, was seen in 44% patients with LGSIL, 76% patients with HGSIL, and 67% patients with ISCC. These data indicate that c-myc amplification is one of the critical early events in the progression of uterine cervical lesions. HPV infection of various subtypes was identified in 0% patients with ND, 55% patients with LGSIL, 95% patients with HGSIL, and 84% patients with ISCC. No codon 12 mutation of the Ha-ras gene was found in this series. Aneuploid DNA pattern was seen in 0% patients with ND, 58% patients with LGSIL, 90% patients with HGSIL, and 80% patients with ISCC. There was a significant correlation between HPV infection and DNA aneuploidy. However, no relationship was seen between c-myc status and other factors in this series. Patients with HGSIL and ISCC almost always (95%) had multiple risk factors, whereas more than half of the patients with LGSIL had no or only one risk factor (P = 0.0001).

Aneuploidy↗
PubMed1998

Anisakidosis: a cause of intestinal obstruction from eating sushi.

We report a case of strangulating small bowel obstruction in a 60-yr-old Japanese woman caused by anisakidosis (previously known as anisakiasis). With the increasing popularity of Japanese cuisine such as sushi in the United States, the incidence of anisakidosis is expected to increase. Intestinal anisakidosis can now be treated temporarily, but this condition may cause a serious obstruction afterwards, as evidenced by this particular case. Over 13,500 cases were reviewed in both the Japanese and English literature, and we discuss the prevention of anisakidosis without negatively altering the taste of the raw fish.

Animals↗
PubMed1998

Stereoselective disposition of sulbenicillin in humans.

Stereoselective disposition of sulbenicillin (SBPC) epimers in healthy human volunteers was studied in order to clarify the differences in pharmacokinetic behavior between the epimers. Stereospecific high-performance liquid chromatography was used for the determination of SBPC epimers. Plasma protein binding was measured in vitro with an ultrafiltration method. The binding was stereoselective, with the unbound fraction (fu) of the R-epimer being approximately 1.3-fold greater than that of the S-epimer. SBPC was administered intravenously to human volunteers, and concentrations of SBPC in plasma and urinary excretion rates were measured. Renal clearance (CLR) for the unbound drug (approximately 400 ml/min) was greater than the glomerular filtration rate (GFR) (approximately 109 ml/min) for both epimers, suggesting that both epimers are secreted at the renal tubules. Renal tubular secretion appeared to be greater for the S-epimer. When probenecid was coadministered, the CLR values of both epimers were significantly reduced and were approximately equal to the GFR values. CLR was greater for the S-epimer (37.5 and 49.8 ml/min for R-SBPC and S-SBPC, respectively), which was simply due to the greater fu of the S-epimer in plasma. In contrast, total body clearance was greater for the R-epimer (67.8 and 56.3 ml/min for R-SBPC and S-SBPC, respectively) because of the stereoselective degradation of the R-epimer in plasma. It was revealed that stereoselective degradation in the body had significant influence on the disposition of SBPC epimers.

Adult↗
PubMed1998

Production of the carotenoids lycopene, beta-carotene, and astaxanthin in the food yeast Candida utilis.

The food-grade yeast Candida utilis has been engineered to confer a novel biosynthetic pathway for the production of carotenoids such as lycopene, beta-carotene, and astaxanthin. The exogenous carotenoid biosynthesis genes were derived from the epiphytic bacterium Erwinia uredovora and the marine bacterium Agrobacterium aurantiacum. The carotenoid biosynthesis genes were individually modified based on the codon usage of the C. utilis glyceraldehyde 3-phosphate dehydrogenase gene and expressed in C. utilis under the control of the constitutive promotes and terminators derived from C. utilis. The resultant yeast strains accumulated lycopene, beta-carotene, and astaxanthin in the cells at 1.1, 0.4, and 0.4 mg per g (dry weight) of cells, respectively. This was considered to be a result of the carbon flow into ergosterol biosynthesis being partially redirected to the nonendogenous pathway for carotenoid production.

Biotechnology↗
PubMed1998

Increased carotenoid production by the food yeast Candida utilis through metabolic engineering of the isoprenoid pathway.

The yeast Candida utilis does not possess an endogenous biochemical pathway for the synthesis of carotenoids. The central isoprenoid pathway concerned with the synthesis of prenyl lipids is present in C. utilis and active in the biosynthesis of ergosterol. In our previous study, we showed that the introduction of exogenous carotenoid genes, crtE, crtB, and crtI, responsible for the formation of lycopene from the precursor farnesyl pyrophosphate, results in the C. utilis strain that yields lycopene at 1.1 mg per g (dry weight) of cells (Y. Miura, K. Kondo, T. Saito, H. Shimada, P. D. Fraser, and N. Misawa, Appl. Environ. Microbiol. 64:1226-1229, 1998). Through metabolic engineering of the isoprenoid pathway, a sevenfold increase in the yield of lycopene has been achieved. The influential steps in the pathway that were manipulated were 3-hydroxy methylglutaryl coenzyme A (HMG-CoA) reductase, encoded by the HMG gene, and squalene synthase, encoded by the ERG9 gene. Strains overexpressing the C. utilis HMG-CoA reductase yielded lycopene at 2.1 mg/g (dry weight) of cells. Expression of the HMG-CoA catalytic domain alone gave 4.3 mg/g (dry weight) of cells; disruption of the ERG9 gene had no significant effect, but a combination of ERG9 gene disruption and the overexpression of the HMG catalytic domain yielded lycopene at 7.8 mg/g (dry weight) of cells. The findings of this study illustrate how modifications in related biochemical pathways can be utilized to enhance the production of commercially desirable compounds such as carotenoids.

Candida↗
PubMed1998

Indomethacin interferes with EGF-induced activation of ornithine decarboxylase in gastric cancer cells.

BACKGROUND/AIMS: Epidermal growth factor (EGF) has a wide variety of biological activities in the protection of gastric mucosa against acute injury and the healing of gastric ulcer. However, the molecular basis of the EGF action remains unknown. EGF-induced activation of ornithine decarboxylase (ODC) was examined, because ODC is a key enzyme for the cell proliferation. METHODS: The effects of epidermal growth factor (EGF) and indomethacin on ornithine decarboxylase (ODC) mRNA and enzyme activity were examined in gastric cancer derived KATO-III cells. RESULTS: EGF induced both ODC mRNA expression and enzyme activation in a biphasic manner with the peaks at 0.5 and 3 h for mRNA and at 5 and 9 h for enzyme activity, respectively. Indomethacin pretreatment significantly reduced EGF-induced ODC activation and was completely abolished for the first 5 h. CONCLUSION: Since it has been reported that both EGF and ODC are involved in cell migration and proliferation, two actions of EGF for gastric mucosal healing may be through, at least in part, this biphasic activation of ODC. Indomethacin suppresses and changes the response of ODC induced by EGF.

Adenocarcinoma↗
PubMed1998

Impact of preoperative serum carcinoembryonic antigen, CA 19-9 and alpha fetoprotein levels in gastric cancer patients.

The relationship between preoperative serum carcinoembryonic antigen (CEA), CA 19-9 and alpha-fetoprotein (AFP) levels and their clinicopathological features were evaluated in gastric cancer patients. The positive rates of CEA, CA 19-9 and AFP were 24.8, 27.6 and 12.7%, respectively. Gastric cancer with deeper tumor invasion was significantly more common among patients positive for these tumor markers. Patients with positive CEA or CA 19-9 values had a significantly high risk of lymph node metastases (p = 0.045 and p = 0.002, respectively). Synchronous liver metastases was more commonly found in patients with a positive CA 19-9 value. A significant difference (p < 0.001) in survival rate was found between patients with positive CA 19-9 values and those with negative values. CA 19-9 is useful for the prognosis of gastric cancer patients, whereas CEA, although unsuitable for prognosis, contributes to the prediction of cancer invasion.

Adult↗
PubMed1998

Requiring higher doses of erythropoietin suggests pregnancy in hemodialysis patients.

BACKGROUND/AIMS: Pregnancy in hemodialysis (HD) patients tends to be diagnosed late because of its infrequency and the lack of validity of urine pregnancy tests, and because these patients tend to have menstrual irregularities. The outcome is influenced by pregnancy-related anemia. We investigated the characteristics of pregnancy-related anemia and whether it is a useful diagnostic clue to pregnancy in HD patients. METHODS: We retrospectively investigated six pregnancies of 5 HD patients (mean age 30 years), including 4 patients treated with recombinant human erythropoietin (rHuEpo) and a transfusion-dependent patient with two pregnancies in the pre-rHuEpo era. RESULTS: The mean duration of HD was 6 years, the mean duration of the patients' marriages at the time of pregnancy was 6 years, and the mean gestational age at diagnosis was 11 weeks and 4 days. The progression of anemia (an 8% decrease in the hematocrit) was detected by 8 weeks of gestation in all patients. The prepregnancy hematocrit was stable in 5 pregnancies, facilitating the detection of changes, but during one of the pregnancies of the transfusion-dependent patient the hematocrit was low and was influenced by the transfusions. The amount of rHuEpo required to attain a target hematocrit of 30% increased gradually or rapidly until delivery. CONCLUSIONS: The progression of anemia or hyporesponsiveness to rHuEpo was a useful early diagnostic clue to pregnancy in HD patients. However, the prepregnancy hematocrit should be stabilized with rHuEpo, so that decreases can be easily detected. The precise mechanisms of hyporesponsiveness to rHuEpo, which progressed during pregnancy and subsided after delivery, remain to be clarified.

Adult↗
PubMed1998

Successful treatment of stage III neuroblastoma based on prospective biologic staging: a Children's Cancer Group study.

PURPOSE: To identify a biologically favorable and unfavorable subset of patients with Evans stage III neuroblastoma and to determine whether treatment stratification would improve the event-free survival (EFS) for high-risk patients and maintain excellent EFS for the lower-risk patients. PATIENTS AND METHODS: Risk stratification was performed by age, MYCN gene copy number, Shimada histopathologic classification, and serum ferritin level. Lower-risk patients were treated on the less intensive Children's Cancer Group (CCG)-3881, whereas high-risk patients were treated on CCG-3891, which included more intensive multimodality therapy and, in some cases, autologous bone marrow transplantation (ABMT). RESULTS: Of 228 Evans stage III patients entered onto the study, 92% also met the definition of International Neuroblastoma Staging System (INSS) stage 3. One hundred forty-three patients met the lower-risk criteria, which included 89 patients less than 1 year of age and 54 patients 1 year of age or greater, and favorable biology, whereas 85 patients were 1 year of age or greater and biologically unfavorable. Biologically unfavorable patients 1 year of age or greater who underwent gross surgical resection had improved survival, whereas the outcome of infants or biologically favorable older patients did not change according to resection. The EFS rate at 4 years was 100% for the patients with favorable biology of any age, 90% for those less than 1 year of age but with at least one unfavorable characteristic, and 54% for Evans stage III patients 1 year of age or greater with unfavorable biology. Age, ferritin level, MYCN copy number, Shimada histopathology, primary site, and intraspinal extension were significant univariate prognostic factors for all patients, but only MYCN copy number and age were independent factors in multivariate analyses. CONCLUSION: The excellent survival of the biologically favorable group and the historically improved EFS of the biologically unfavorable group suggest that biologic staging should be used to define the prognosis and treatment of stage III neuroblastoma.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Medicinal foodstuffs. XIV. On the bioactive constituents of moroheiya. (2): New fatty acids, corchorifatty acids A, B, C, D, E, and F, from the leaves of Corchorus olitorius L. (Tiliaceae): structures and inhibitory effect on NO production in mouse peritoneal macrophages.

Following the characterization of the glycosidic constituents in a medical foodstuff "moroheiya," the leaves of Corchorus olitorius L., four higher fatty acids with a trienone function, corchorifatty acids, A, B, C, and D, an undecanoic acid, corchorifatty acid E, and a trihydroxyfatty acid, corchorifatty acid F, were isolated from the less polar fraction of "moroheiya". The structures and optical purity of corchorifatty acids were determined on the basis of chemical and physicochemical evidence. Corchorifatty acids A, B, and C showed an inhibitory effect on lipopolysaccharide-induced NO production in cultured mouse peritoneal macrophages.

Animals↗
PubMed1998

Antidiabetic principles of natural medicines. II. Aldose reductase and alpha-glucosidase inhibitors from Brazilian natural medicine, the leaves of Myrcia multiflora DC. (Myrtaceae): structures of myrciacitrins I and II and myrciaphenones A and B.

The methanolic extract and ethyl acetate-soluble portion from a Brazilian natural medicine, the leaves of Myrcia multiflora DC., which has been used as a specific medicine against diabetes, were found to show inhibitory activities on aldose reductase and alpha-glucosidase and on the increase of serum glucose level in sucrose-loaded rats and in alloxan-induced diabetic mice. From the ethyl acetate-soluble portion, new flavanone glucosides, myrciacitrins I and II, and new acetophenone glucosides, myrciaphenones A and B, were isolated together with several known compounds such as five flavonol glycosides, myricitrin, mearnsitrin, quercitrin, desmanthin-1, and guaijaverin. The structures of new compounds were determined on the basis of physicochemical and chemical evidence. The principal components of this natural medicine including new glucosides, myrciacitrin I and myrciaphenone B, were found to show potent inhibitory activities on aldose reductase and alpha-glucosidase.

Acetophenones↗
PubMed1998

Sympathetic function test of vasoconstrictor changes in foot arteries in diabetic patients.

OBJECTIVE: We studied the relationship between vasoconstrictor changes in foot arteries (pedal, metatarsal, and digital arteries) and autonomic neuropathy in diabetic patients to estimate the degrees of sympathetic dysfunction. RESEARCH DESIGN AND METHODS: Sixty-two patients and nineteen age-matched control subjects were studied. The resistance index (RI) and pulsatility index (PI) were measured as vascular hemodynamic parameters using Doppler sonography, and the increases in these hemodynamic parameters (%RI and %PI) from rest to a deep breath were measured as indexes of the degrees of sympathetic vasoconstrictor function. Cardiovascular autonomic function tests (AFTs) were performed and the score was compared to %RI and %PI values obtained. RESULTS: Of the 62 diabetic patients, 51 had various degrees of autonomic neuropathy. Both %RI and %PI in the diabetic patients were significantly less than those in the control subjects for all foot arteries tested (all P < 0.001). There were strongly inverse correlations between the %RI and %PI of foot arteries and the AFT score (r = -0.556 to -0.846, P < 0.0001). The %RI of the digital artery was the most strongly correlated with AFT score (r = -0.846, P < 0.0001) among foot arteries tested. The abnormality of sympathetic vasoconstriction was detectable in the majority of the diabetic patients with the early phase of autonomic neuropathy (%RI: 89.5%; %PI: 94.5%). CONCLUSIONS: We conclude that the %RI of the digital artery is a useful and reliable sympathetic function test of early phase in diabetic patients.

Adult↗