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Biomedical subjects

Kenichi Kobayashi

Publications and source records attributed to Kenichi Kobayashi.

At least 19 recordsLinked to original sources
PubMed2006

Effects of perinatal exposure to bisphenol A on brain neurotransmitters in female rat offspring.

Pregnant Sprague-Dawley (CD IGS) rats were orally administered doses of bisphenol A (BPA) at 4, 40, and 400 mg/kg, from gestation days 6 to postnatal day 20. Neurotransmitters such as dopamine (DA) and serotonin (5HT) were extracted from the brains of dams and female offspring, and measured using liquid chromatography. BPA at 400 mg/kg was toxic and dosed rats died. At 3 wk after birth, brain levels of 3,4-dihydroxyphenylacetic acid (DOPAC, a DA metabolite), homovanillic acid (HVA, a DA metabolite), 5HT, 5-hydroxyindoleacetic acid (5HIAA, a 5HT metabolite) in female offspring were increased and the HVA/DA ratio was high in some brain areas of BPA-treated groups as compared with controls. At the age of 6 wk, levels of choline (Ch) in BPA-treated groups at 4 and 40 mg/kg were higher than control in all of eight brain areas. No changes were observed in acetylcholine (ACh) contents. In 9-wk-old offspring, changes in monoamines and metabolites were scattered and not great. At 3 wk after delivery, levels of 5HIAA in some brain areas of dams treated with BPA were higher than in control dams. Dose dependent increases in HVA and the HVA/DA ratio of the occipital cortex, and in the HVA/DA ratio of the frontal cortex were observed. The turnover of DA and 5HT was accelerated in 3-wk-old offspring and dams. BPA possesses very weak estrogenic activity. Changes in cerebral neurotransmitters observed in offspring and dams in this study may have been related to the estrogenic activity of BPA. However, further investigation is needed to examine the contribution of hormonal activity to such neurotransmitter changes.

Administration, Oral↗
PubMed2006

Effects of in utero and lactational exposure to di(2-ethylhexyl)phthalate on somatic and physical development in rat offspring.

Di(2-ethylhexyl)phthalate (DEHP) has been reported to act as an antiandrogen and to affect the reproductive organs and accessory genital glands. Thus, to assess the reproductive toxicity of DEHP it is important to examine both its adverse effects on the development of offspring following maternal exposure and its effects on sexual function and fertility. In the present study, we examined whether in utero and lactational exposure to DEHP affects postnatal somatic growth of offspring in the rat. Pregnant females were orally administered various doses of DEHP (0, 25, 100 or 400 mg/kg body weight/day) from gestational day (GD) 6 through postnatal day (PND) 20. There were no significant changes in body weight, body length, tail length, or the weight of individual organs between the control and DEHP-treated groups. Somatic hormonal parameters were the same for all DEHP doses. These findings suggest that in utero and lactational exposure to various concentrations of DEHP has very little effect on postnatal development or endocrine and physical status of male and female rat offspring under the experimental conditions of the present study.

Animals↗
PubMed2005

Thyroid-stimulating hormone receptor levels and binding affinity in the thyroid gland of growth-retarded mice.

Growth-retarded (grt/grt) mice are congenitally primary hypothyroid. Our previous study indicated that thyroid-stimulating hormone (TSH) responsiveness was defective in the grt/grt thyroid gland. We now report additional studies of impaired grt/grt thyroid function. Semiquantitative RT-PCR confirmed that TSH receptor (TSHR) mRNA expression in the grt/grt thyroid was significantly decreased compared with +/+ thyroids. Scatchard analysis revealed that grt/grt and +/+ mice have only one type of TSH binding site. grt/grt thyroids had fewer TSH binding sites, although this did not apparently affect the affinity of TSH for its receptor. The present data suggest that reduced TSHR levels or defects in TSHR signaling could be one of the possible defective sites in the grt/grt thyroid gland.

Animals↗
PubMed2005

Albumin and urea production by hepatocytes cultured on extracellular matrix proteins-conjugated poly(vinyl alcohol) membranes.

Production of albumin and urea by mouse hepatocytes on poly(vinylalcohol-co-ethylamine) (PVA-EA) membranes containing immobilized extracellular matrix (ECM) proteins was investigated for 7 days. The amount of ECM proteins (collagen, vitronectin and laminin) immobilized on PVA-EA and PVA-ECM membranes was determined to range from 1.09 microg/cm2 to 1.60 microg/cm2. Hepatocytes cultured on PVA-ECM membranes in serum-free media showed higher albumin production than those cultured on PVA-EA membranes after a 7-day incubation under the conditions in this study. Urea production by hepatocytes on PVA-ECM membranes was also determined to be higher than that on PVA-EA membranes up until day 5 of incubation in serum-free media, whereas no difference of urea production by hepatocytes on different PVA-ECM membranes and PVA-EA membranes was observed at 7 days of incubation. The effect of ECM proteins in PVA-ECM membranes on hepatocyte function (such as albumin and urea production) was observed in hepatocytes cultured in serum-free media up to day 5 of incubation. The ECM proteins immobilized on the PVA-ECM membranes contributed not only to the long-term stable production of albumin and urea by hepatocytes, but also the improved surviVal (viability) of hepatocytes on PVA-ECM membranes.

Albumins↗
PubMed2005

Effects of in utero and lactational exposure to bisphenol A on thyroid status in F1 rat offspring.

Bisphenol A (BPA), a xenoestrogen, has been reported to mimic the actions of estrogen or to affect the endocrine glands in vivo and in vitro. In this study, we examined whether in utero and lactational exposure to BPA alters thyroid status in rat F1 offspring. Dams were orally administered various doses of BPA (0, 4 or 40 mg/kg body weight per day) from gestation day (GD) 6 through postnatal day (PND) 20. The BPA and control groups did not differ significantly with respect to plasma thyroxine (T4) concentration. The thyroid glands from the BPA groups had normal T4 responses to exogenous thyroid-stimulating hormone in vivo. These results suggest that in utero and lactational exposure (indirect exposure) to BPA (4-40 mg/kg/day, GD 6 - PND 20) does not affect thyroid functions in the F1 generation of male and female rats.

Animals↗
PubMed2005

[An interesting change of E-selectin in cimetidine administration during anticancer drug use].

E-selectin is an adhesion molecule developed as an important material for hematogenous metastasis of cancer cells on vascular endothelial cells. It is expected that if we can restrain a manifestation of E-selectin then hematogenous metastasis can be restrained. We divided gastric cancer and the colorectal cancer patients, who performed chemotherapy, into two groups of cimetidine administrated group and a non-administration group, and reviewed whether cimetidine inhibited an expression of E-selectin on vascular endothelial cells by measuring E-selectin in plasma. We experienced one example that showed an interesting change of E-selectin and the quantity of E-selectin in plasma fell during the cimetidine dosage. However, we report that E-selectin has risen after the cimetidine dosage was cancelled in the cimetidine administrated group.

Cimetidine↗
PubMed2004

Report of the 15th follow-up survey of primary liver cancer.

In the 15th Nationwide follow-up survey of primary liver cancer, 18,843 newly registered patients (1998-1999) and 18,405 follow-up patients from 791 hospitals in Japan were analyzed. Of the newly registered patients, approximately 95% were patients with hepatocellular carcinoma (HCC) and 3.3% had intrahepatic cholangiocarcinoma (ICC). The patients were assessed using 194 items that were related to epidemiological and clinicopathological factors, diagnosis, and treatment. Furthermore, the survival rates of all of the newly registered patients in the 10th-15th follow-up survey were calculated for each histological type, background factor(s) and treatment, respectively. In patients with hepatocellular carcinoma, the survival rates of patients who underwent hepatectomy, ethanol injection therapy, microwave coagulation therapy, or transcatheter arterial embolization were calculated by tumor size, tumor number, and clinical stage. This follow-up survey will be helpful to assess the progress of research and medical practice in the treatment of primary liver cancer.

Journal Article↗
PubMed2003

Synergistic antiviral effect of a combination of mouse interferon-alpha and interferon-gamma on mouse hepatitis virus.

Although interferon (IFN)-alpha and IFN-gamma have been reported to exhibit a synergistic antiviral effect through the different signaling pathways in vitro, their therapeutic efficacy is not well defined in vivo. The current study was carried out to investigate the combined antiviral effect in a model of mouse hepatitis virus Type 2 (MHV-2) infection, in which fulminant hepatitis is developed. MHV-2 was injected intraperitoneally into 4-week-old ICR mice, IFN or the vehicle was administered intramuscularly for 5 days, and the antiviral effect was evaluated based on survival periods, liver histology, serum alanine transaminase (ALT) levels, and MHV-2 virus titers in the liver tissues. The animals in the group treated with a combination of IFN-alpha and IFN-gamma survived for longer periods than the groups treated with IFN-alpha alone and IFN-gamma alone (IFN-alpha 10(3) (IU/mouse)/-gamma 10(3) vs. IFN-alpha 10(3), P < 0.005; IFN-alpha 10(3)/-gamma 10(3) vs. IFN-gamma 10(3), P < 0.001). This is consistent with the lower levels of hepatocellular necrosis and serum ALT and the decreased titers of MHV-2 virus in the liver tissues (48 hr, P < 0.001; 72 hr, P < 0.001). These findings indicate that a combination of IFN-alpha and IFN-gamma exhibits a synergistic antiviral effect on MHV-2 infection. The biology of MHV-2 is quite different from that of human hepatitis viruses; however, these results suggest the beneficial combined therapy of IFN-alpha and IFN-gamma for the treatment of human viral hepatitis.

Animals↗
PubMed2003

Analysis of the CD8-positive T cell response in Japanese patients with chronic hepatitis C using HLA-A*2402 peptide tetramers.

Hepatitis C virus (HCV)-specific CD8+ cytotoxic T lymphocytes (CTL) contribute to viral clearance in acute, self-limited hepatitis C as well as to liver cell injury in the more frequent cases with chronic hepatitis C. Although HLA class I-peptide tetramers have been used to detect circulating HCV epitope-specific CTL with a high sensitivity and specificity, this technique has been targeted exclusively to the most frequent HLA haplotypes in the Caucasian population and the large number of HCV-infected Asian patients, most of whom are HLA-A24 positive, have not been studied. The current study determines the frequency, phenotype, and clinical significance of HCV-specific CD8(+) T lymphocytes with five different HLA-A*2402 tetramers in 43 HCV infected Japanese patients and 32 controls. Overall, tetramer(+) cells were detected in the blood of 33 of 43 patients at frequencies of 0.064-0.75% CD8(+)CD4(-)CD14(-)CD19(-) T lymphocytes. Interestingly, although the T cell response was always targeted multispecifically against epitopes in different HCV proteins, the relative frequency of cells stained with individual tetramers differed between patients. Furthermore, tetramer(+)CD8(+) T lymphocytes were highly activated, but the phenotypes of different tetramer(+) cells varied in each patient. In conclusion, HLA-A24 restricted, HCV-specific CD8(+) T lymphocytes are found at similar frequencies in Asian patients as HLA-A2 restricted, HCV-specific CD8(+) T lymphocytes in Caucasian patients. Differences in the frequency and activation status of individual tetramer(+) cell populations suggest that CD8(+) T lymphocytes with different HCV epitope specificity may mediate differential pathogenetic effects in chronic hepatitis C.

CD8-Positive T-Lymphocytes↗
PubMed2003

Potential interaction between CCR1 and its ligand, CCL3, induced by endogenously produced interleukin-1 in human hepatomas.

Hepatoma cell lines can produce a massive amount of chemokines in response to various stimuli including hepatitis viruses and their products. However, it remains elusive on the types of chemokine receptor(s) expressed in the hepatoma tissues and its roles in hepatoma development. To clarify these points, we examined the chemokine receptor expression in six human hepatoma cell lines. All of the hepatoma cell lines constitutively and exclusively expressed CCR1 mRNA and its protein on their cell surface. CCR1 expression was also detected on hepatoma cells and to a lesser degree, on endothelial cells in hepatoma tissues but not in normal liver tissues. Furthermore, CCL3 expression was detected in hepatoma cells, endothelial cells, and to a lesser degree, fibroblast-like cells in hepatoma tissue, whereas only occasional vascular endothelial cells and inflammatory cells in normal liver tissues were weakly positive for CCL3. Moreover, the forskolin-mediated increases in intracellular cAMP concentrations were inhibited by the ligands for CCR1, CCL3, CCL4, and CCL5, suggesting that the expressed CCR1 was functional. Four hepatoma cell lines produced CCL3 only in response to interleukin (IL)-1 alpha and IL-1 beta. Finally, IL-1 alpha and IL-1 beta were detected abundantly in hepatoma tissues but not in normal liver tissues. Thus, IL-1 may enhance the local production of CCL3, which may interact with CCR1 expressed on hepatoma cells, in an autocrine and/or paracrine manner.

Base Sequence↗
PubMed2003

Apoptosis of murine cultured biliary epithelial cells induced by glycochenodeoxycholic acid involves Fas receptor and its ligand.

Fas-mediated apoptosis of biliary epithelial cells (BECs) is suggested as a main effector process in immune-mediated biliary diseases. Glycochenodeoxycholic acid (GCDCA), a conjugated hydrophobic bile acid, is known to cause apoptosis of hepatocytes via the direct activation of Fas receptor (FasR). In this study, we investigated the apoptotic effect of GCDCA on cultured murine intrahepatic BECs. It was found that GCDCA induced apoptosis of BECs derived from BALB/c mice in a dose- and incubation time-dependent manner. The morphology and TUNEL positivity for the apoptotic process induced by GCDCA were similar to those induced by beauvericin (BV) which is known to cause apoptosis by a direct activation of caspase-3, a member of the caspase family, at its downstream. The GCDCA-induced apoptosis of BECs was accompanied by an up-regulation of FasR, Fas ligand (FasL), and also caspase-3 expression. GCDCA did not induce the apoptosis of BECs derived from C3H.MRL-Fas(lpr) mice possessing a non-functioning FasR, supporting that the GCDCA-induced apoptosis of BECs in BALB/c involves the Fas system. Furthermore, GCDCA induced an increase in interleukin-18 (IL-18) mRNA in BECs and secretion of activated IL-18 from BECs of BALB/c, which might have led to an up-regulation of FasL mRNA and protein expression in BECs followed by FasR/FasL interaction. These results suggest that GCDCA induces apoptosis of BECs through FasR/FasL interaction via an autocrine/paracrine effect, IL-18 is responsible for the expression of FasL in BEC, and the up-regulation of caspase-3 expression is involved in this model. This model could be useful for molecular and genetic studies of Fas-mediated apoptosis of BECs.

Journal Article↗
PubMed2003

DNA alterations during multi-step development of human hepatocellular carcinomas revealed by laser capture microdissection.

In order to clarify early molecular events involved in liver carcinogenesis, we analyzed 53 liver-cirrhosis nodules (LCNs) from five patients and 13 micro-hepatocellular carcinoma (HCC) nodules from one patient and looked for alterations of microsatellites in genomic DNA after carefully preparing the tissue samples by laser-capture microdissection (LCM). Allelotyping was done with 20 markers corresponding to anonymous microsatellites and 13 corresponding to tumor suppressor genes (TSGs) that had shown significant alterations in HCCs. We detected both loss of heterozygosity (LOH) and microsatellite shifts (MS). Overall, 24 of 53 (47%) of LCNs showed LOH with any of the informative markers used in the study, reflecting that proportion of LCNs with clonal growth. The fractional allelic loss (FAL) index, an indication of total genomic complexity, was not significantly different between LCN and micro-HCC nodules, but their profiles of alteration were different. These profiles were classified into three groups: (1) LCN profile-allelic loss at chromosomal arms 1q and 14q, TBP and BRCA1; (2) HCC profile-LOH at 4q, 6q, 7q, 17p, NF1, IGFIIr and p53 in micro-HCC nodules; these changes in early lesions were identical to those seen in mature HCCs; (3) Common profile-LOH at NF1 and 6q, including IGFIIr, common to both LCN and HCC. No LCN showed LOH at p53 and Rb, loci that are generally altered in HCCs. However, 12 intra-tumoral nodules examined had lost p53 in all informative cases, although the loss of Rb was a late event. These results suggest that early genomic profiles confined to LCNs, and additional profiles that can be observed when liver tissue undergoes malignant transformation, support a model of multi-step development of HCC.

Journal Article↗
PubMed2003

Enhanced antitumor effects of a bicistronic adenovirus vector expressing both herpes simplex virus thymidine kinase and monocyte chemoattractant protein-1 against hepatocellular carcinoma.

The efficacy of the suicide gene therapy using the herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV) system for the treatment of cancer is limited because of the insufficient gene transfer and the low killing activity. To enhance the antitumor activity, we determined whether recombinant adenovirus vector (rAd)s expressing both HSV-tk and monocyte chemoattractant protein-1 (MCP-1) genes could potentiate the destruction of hepatocellular carcinoma (HCC). The rAd Ad-tk-MCP1 harboring HSV-tk and MCP-1 genes in sequence under the universal CAG promoter was constructed with a bicistronic unit including the encephalomyocarditis virus-internal ribosomal entry site. The levels of HSV-tk expression and GCV-sensitive tumoricidal activity of Ad-tk-MCP1 were comparable to those of rAd expressing HSV-tk alone. The growth of subcutaneous tumors in athymic nude mice was markedly suppressed when tumors were treated with Ad-tk-MCP1 as opposed to another bicistronic vector Ad-MCP1-tk, rAd expressing either HSV-tk or MCP-1, or both of these vectors. The antitumor effects of Ad-tkMCP1 may be dependent on the activation of macrophages, since the recruitment of macrophages was observed tumor necrosis factor-alpha production was enhanced in the tumor tissue. Furthermore, the enhanced antitumor effect was abolished by inactivating macrophages with carrageenan treatment. These results demonstrated that a bicistronic rAd harboring both suicide and chemokine genes in sequence exerted the enhanced, macrophage-dependent, antitumor effects in a model of HCC and support the use of this strategy for the treatment of HCC.

Adenoviridae↗
PubMed2003

Combination therapy of ecabet sodium and cimetidine compared with cimetidine alone for gastric ulcer: prospective randomized multicenter study.

BACKGROUND AND AIM: Little is known about the clinical efficacy of co-therapy of ecabet sodium, a mucoprotective agent, and a histamine H2-receptor antagonist. The aim of the present study was to assess its additive benefit in combination with cimetidine for gastric ulcer. METHODS: In this prospective randomized study, after gastric ulcer was confirmed by endoscopy, 200 patients in 47 hospitals received either ecabet sodium 1 g b.i.d and cimetidine 400 mg b.i.d. (EC), or cimetidine 400 mg b.i.d. alone (C) for 8 weeks. Healing was examined by endoscopy at 4 and 8 weeks. RESULTS: Of the intention-to-treat (ITT) population (EC, 103; C, 97), 181 patients comprised the per protocol (PP) analysis (EC, 93; C, 88). At 4 weeks, healing rates were significantly higher in the EC group (60%) than in the C group (36%) ( p < 0.01). At 8 weeks, those by the ITT and PP analyses were 82% (EC) versus 58% (C), and 90% (EC) versus 64% (C), respectively ( p < 0.01 and p < 0.001). Symptom relief rates (EC vs C) at 2, 4 and 8 weeks were 73%versus 47% ( p < 0.01), 89%versus 66% ( p < 0.001), and 97%versus 73% ( p < 0.001), respectively. Significant additive effects of ecabet sodium were observed in patients aged 60 years or older, with solitary and medium to large ulcer, and without smoking or drinking habits. No adverse effects were critical. CONCLUSION: Ecabet sodium significantly augmented gastric ulcer healing and symptom relief by cimetidine, especially in the elderly.

Abietanes↗
PubMed2003

Ultrasonic analysis of anthracycline-induced myocardial damage using cyclic variation of integrated backscatter.

To test the feasibility of integrated backscatter (IB) for detecting anthracycline cardiotoxicity, we performed conventional echocardiography and IB analysis. For interindividual comparison, 32 patients with non-Hodgkin's lymphoma and 14 control subjects were selected. Of the patients, 10 had been treated with doxorubicin doses of </=200 mg/m(2) (low dose), 15 with </=400 mg/m(2) (moderate dose), and 7 with >400 mg/m(2) (high dose). In intraindividual comparison, 8 patients were examined before doxorubicin therapy and at a dose of 100 mg/m(2) and 8 were examined before and at a 300-mg/m(2) dose. Cyclic variation of IB (CV-IB) was obtained at the left ventricular posterior wall, using a modified, commercially available system in M-mode format. In interindividual comparison, CV-IB in high- and moderate-dose groups was smaller. In intraindividual comparison, CV-IB decreased after treatment with 300 mg/m(2) of doxorubicin. CV-IB was affected in some patients treated with a moderate dose of doxorubicin. IB analysis may be helpful for detecting early anthracycline cardiotoxicity.

Adult↗
PubMed2003

Detection of hepatitis B virus DNA in sera from patients with chronic hepatitis B virus infection by DNA microarray method.

We have developed a sensitive and quantitative assay using a DNA microarray for the detection of hepatitis B virus (HBV) DNA in serum. Fluorescently labeled target cDNA prepared from cloned HBV DNA or serum HBV DNA was hybridized to capture DNA on a slide. A linear relationship was obtained between the intensities of the array spot and the amount of the cloned or serum HBV DNA, indicating the quantitative accuracy of this assay system. In addition, there was a significant correlation between the number of molecules of serum HBV DNA determined by the DNA microarray and that determined by a branched-DNA assay (n = 21, r = 0.89). Given these results, we conclude that the DNA microarray assay system may be useful as a diagnostic technique in the clinical laboratory.

Branched DNA Signal Amplification Assay↗
PubMed2003

Imbalance of testosterone level in male offspring of rats perinatally exposed to bisphenol A.

The purpose of this study was to investigate whether exposure to bisphenol A (BPA) through the placenta and milk has any effect on the reproductive system in male offspring. Pregnant rats were treated with BPA at 0, 4, 40 and 400 mg/kg body weight, from gestation day 6 through lactation day 20 by gavage. Plasma testosterone concentrations in offspring at 9 weeks old were significantly high in BPA groups as compared with those of the control. At the age of 36 weeks the hormone concentrations showed an increase in a dose-dependent manner, although without statistical significance. Testosterone content in testes showed a similar tendency to that in plasma, though statistically insignificant. Little alteration in testes weight was seen in BPA-exposed offspring. There was no remarkable change in plasma concentrations of luteinizing hormone and follicle-stimulating hormone at 9 weeks old. The pathway of E2 (17beta-estradiol) formation from testosterone seemed not to be affected by BPA. The results indicate that exposure to BPA during the perinatal period has a significant effect on testosterone homeostasis in male offspring of rats.

Air Pollutants, Occupational↗