Biomedical subjects

K Sekikawa

Publications and source records attributed to K Sekikawa.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Clinical experience of intermittent administration of 5-FU and CDDP to patients with advanced and recurrent gastric cancer].

We administered 5-FU and CDDP (FP) intermittently to four patients with advanced and recurrent gastric cancer. A minor response (MR) and partial response (PR) were achieved in two of four patients who had evaluable lesions for this treatment, and few side effects were observed. Only one patient among six showed grade 2 leucocytopenia after 15 administrations of this chemotherapy, when she had attained a partial response in a lung metastasis. The other patients had no side effects such as bone marrow suppression or digestive symptoms. This intermittent FP treatment may be an effective and promising therapy with few side effects even for the patients with serious conditions.

Aged↗

PubMed2001

[Intermittent administration of 5-FU and isovorin to patients with advanced and recurrent colon cancer].

We attempted a new regimen of intermittent administration of 5-FU and low-dose Isovorin (F.I) to four patients with advanced and recurrent colon cancer. A partial response (PR) was achieved in two of four patients who had evaluable lesions for this treatment. We observed few side effects among these patients. Only one patient among four showed grade 1 neuropathy after two administrations of this chemotherapy. However, after a two-week pause in administration, the neuropathy disappeared and we could continue the therapy. This patient with multiple liver metastases achieved a partial response. Other patients had no side effects such as bone marrow suppression or digestive symptoms. This intermittent F.I treatment might be an effective and promising therapy with few side effects even for patients with poorer conditions.

Aged↗

PubMed2000

Neurobehavioral alterations in mice with a targeted deletion of the tumor necrosis factor-alpha gene: implications for emotional behavior.

Tumor necrosis factor-alpha (TNF-alpha) is emerging as an important modulator of the function of the central nervous system. In the present study, we investigated a role of endogenous TNF-alpha in cognitive and emotional function using mice with targeted deletions of the TNF-alpha gene. TNF-alpha-(-/-) mice showed normal diurnal rhythms of spontaneous locomotor activity and cognitive functions. Emotional behavior in the mutant mice, however, was significantly altered, which manifested in the performance in the open-field, elevated plus maze, and forced swimming tests. The altered performance in the elevated plus maze test was significantly alleviated by treatment with diazepam. Postmortem brain analysis of TNF-alpha-(-/-) mice revealed a significant increase in serotonin metabolism in the brain. These findings suggest a role for endogenous TNF-alpha in emotional behavior, which may possibly be related to alterations of serotonine metabolism.

Animals↗

PubMed2000

Indispensable role for TNF-alpha and IFN-gamma at the effector phase of liver injury mediated by Th1 cells specific to hepatitis B virus surface antigen.

We report the development and characterization of a novel model of severe hepatitis induced against hepatitis B virus surface Ag (HBsAg). HBsAg was successfully targeted into the liver in soluble form. Using this unique property of HBsAg, we established a liver injury model induced by HBsAg-specific Th1 cells. Severe liver injury was induced in C57BL/6 mice by injection of HBsAg together with HBsAg-specific Th1 cells. Histochemical examination demonstrated extensive necroinflammatory hepatic lesions in these animals. Application of this liver injury model to mutant or gene knockout mice enabled us to define the effector mechanisms of Th1 cells in fulminant hepatitis. When Fas-deficient lpr mice were used as recipients, a similar degree of liver injury was induced as in wild-type mice. Moreover, HBsAg-specific Th1 cells obtained from perforin-/- mice could induce severe liver injury in both wild-type and lpr mice. These results indicated that neither Fas ligand nor perforin are essential for Th1-mediated liver injury in this model. Pretreatment with anti-TNF-alpha mAb prevented liver injury, whereas severe liver injury was induced in TNF-alpha-/- mice. Moreover, IFN-gamma receptor-deficient mice were resistant to Th1-mediated liver injury. Therefore, TNF-alpha and IFN-gamma, which were produced by HBsAg-specific Th1 cells during the effector phase, appeared to be indispensable in the pathogenesis of fulminant hepatitis.

Animals↗

PubMed2000

Lipopolysaccharide-induced HIV-1 expression in transgenic mice is mediated by tumor necrosis factor-alpha and interleukin-1, but not by interferon-gamma nor interleukin-6.

BACKGROUND: As serum HIV-1 load correlates well with the prognosis of the disease, it is suggested that the viral load is one of the major determinants of the disease progression of AIDS. Accordingly, HIV-1 activation mechanisms were extensively studied in vitro, and involvement of cytokines including tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, IL-6 and interferon (IFN)-gamma has been suggested in this process. However, so far the roles of these cytokines in the HIV-1 expression in vivo have not been well elucidated because of the lack of appropriate animal disease models. OBJECTIVE: To elucidate the roles of cytokines in HIV-1 activation in vivo. DESIGN AND METHODS: Transgenic mice carrying a defective HIV-1 genome were used as a model for HIV-1 carriers. In order to examine the possible involvement of cytokines in HIV-1 expression, TNF-alpha-, IL-1-, IL-6- and IFN-gamma-deficient HIV-1 transgenic mice, were produced and HIV-1 expression was analyzed after activation with bacterial lipopolysaccharides (LPS). RESULTS: HIV-1 expression in the transgenic mouse spleen was activated 10- to 20-fold by LPS, and the serum p24 Gag protein levels reached 400 pg/ml, which is nearly equal to the levels that occur in AIDS patients. However, this augmentation was suppressed by 60% in TNF-alpha-deficient mice and by 40% in IL-1alpha/beta-deficient mice. In contrast, no suppression was observed in either IL-6-, IFN-gamma-, IL-1alpha, or IL-1beta-deficient mice. CONCLUSIONS: Results suggest that TNF-alpha and IL-1 play important roles in HIV-1 gene activation and selective suppression of these cytokines could improve clinical prognosis and potentially slow progression of the disease.

Animals↗

PubMed2000

Involvement of decidual Valpha14 NKT cells in abortion.

The immunological mechanisms that regulate abortion are largely unknown. Here, we found that a distinct subset of lymphocytes, Valpha14 NKT cells expressing an invariant antigen receptor encoded by Valpha14/Jalpha281 and Vbeta7 segments, accumulated in the decidua during pregnancy and provoked abortion upon stimulation with alpha-galactosylceramide (alpha-GalCer), a specific ligand for Valpha14 NKT cells. The alpha-GalCer-mediated abortion was not observed in Valpha14 NKT-, IFN-gamma-, tumor necrosis factor alpha-, or perforin-knock-out mice and appeared to be due to the degeneration of embryonic trophoblasts mediated by the activated Valpha14 NKT cells whose perforin-dependent killing and production of IFN-gamma and tumor necrosis factor alpha were essential. The possible role of the decidual Valpha14 NKT cells in the pathogenesis of abortion is discussed.

Abortion, Induced↗

PubMed2000

Quantitative trait loci that modify the sootiness of yellow pigmentation in KK-A(y)/a mice.

Compared with C57BL/6J-A(y)/a, KK-A(y)/a mice have yellow fur that is markedly darker. Furthermore, there is a considerable variation in the tone of color with a continuous range in F(2) progeny produced from C57BL/6J females and KK-A(y)/a males. The aims of this study are to reveal the phenotypic differences between the two A(y) congenic strains and to elucidate the genetic factors responsible for the sooty yellow pigmentation in the KK background. On the basis of a chemical analysis, the sootiness in KK-A(y)/a was the result of increased eumelanin (PTCA) and decreased pheomelanin (AHP). A statistically significant QTL was identified on Chromosome (Chr) 15, responsible for the AHP content. No significant loci responsible for PTCA were identified. On the other hand, on the basis of an optical analysis for color difference and overall sootiness, significant evidence of linkage was identified on the proximal part of Chr 15, in the region similar to AHP QTL. The overall sootiness is thus controlled solely by the locus on Chr 15 in F(2) progeny; however, the KK allele at this locus significantly increased the AHP content.

Alleles↗

PubMed2000

The effects of microgravity on ligase activity in the repair of DNA double-strand breaks.

PURPOSE: In recent years, contradictory data have been reported about the effects of microgravity on radiation-induced biological responses in space experiments. The aim of the present study was to clarify whether enzymatic repair of DNA double-strand breaks is affected by microgravity using an in vitro enzymatic reaction system. MATERIALS AND METHODS: The DNA repair activity of T4 DNA ligase (EC 6.5.1.1) was measured in vitro for a DNA substrate damaged by restriction enzyme digestion during a US Space Shuttle mission (Discovery; STS-91). After the flight, the amount of ligated DNA molecules was measured using an electrophoresis method. RESULTS: Ligated products (closed circular DNA, open circular DNA and multimeric ligated products) were produced by T4 DNA ligase treatment of linear DNA containing double-strand breaks, and they increased with increasing T4 DNA ligase concentration (0-3 units per microg of plasmid DNA). Almost no difference in T4 DNA ligase activity was detected between the space experiments and the control ground experiments. CONCLUSIONS: No significant effect of microgravity on ligation of damaged DNA was found during space flight. Therefore, other mechanisms must account for the synergism between radiation and microgravity, if it exists.

DNA Damage↗

PubMed2000

Suppression of neurocognitive damage in LP-BM5-infected mice with a targeted deletion of the TNF-alpha gene.

Brain levels of TNF-alpha increase in many inflammatory conditions, including HIV-1 infection, and may contribute to neurodegenerative processes. The paucity of agents that can selectively and potently block TNF-alpha processing or its receptors has led us to investigate the role of TNF-alpha in chronic neurodegeneration associated with retroviral infection using mice with targeted deletions of the TNF-alpha gene. Infection of wild-type C57BL/6 mice with the LP-BM5 murine leukemia retrovirus mixture leads to the development of a severe immunodeficiency as well as cognitive deficits and neuronal damage. TNF-alpha-(-/-) mice infected with LP-BM5 developed a systemic immunopathology indistinguishable in severity from that observed in contemporaneously infected wild-type mice. In contrast, the performance of infected TNF-alpha-(-/-) mice in the Y-maze and Morris water maze was not different from that of uninfected TNF-alpha-(-/-) mice. The extent of glial activation in the striatum, as indicated by the increase in density of peripheral benzodiazepine receptors, was equivalent in both groups of LP-BM5-infected mice. However, the decrease in striatal MAP-2 expression, a marker of neurodegeneration observed in infected wild-type mice, was not found in infected TNF-alpha-(-/-) mice. While the loss of TNF-alpha appeared to have no effect on the course or severity of the central or peripheral immunopathology resulting from LP-BM5 infection, the behavioral and biochemical manifestations were substantially curtailed in the TNF-alpha-(-/-) mice. These findings directly support a role for TNF-alpha in the neurodegenerative processes associated with viral infections such as HIV-1.

Animals↗

PubMed2000

Roles of endogenous cytokines in liver apoptosis of mice in lethal Listeria monocytogenes infection.

Various bacterial pathogens have been identified as mediators of apoptosis. Apoptosis reportedly shows both detrimental and beneficial effects on biological functions. We studied the role of liver apoptosis in lethal Listeria monocytogenes infection and the regulation of apoptosis by endogenous cytokines during infection. Apoptosis was observed in the spleen but not in the liver of infected mice, whereas the induction of liver necrosis was evident by rising levels of serum aminotransferases in these animals. Apoptosis was detected in the liver of L. monocytogenes-infected mice which had been treated with monoclonal antibody (mAb) against tumor necrosis factor-alpha (TNF-alpha) or interleukin-6 (IL-6), or in TNF-alpha(-/-) mice, but not in gamma- interferon (IFN-gamma)(-/-) mice or mice which had been treated with mAb against IL-4 or IL-10. Augmentation of liver apoptosis in mice treated with mAb against TNF-alpha or IL-6 or in TNF-alpha(-/-) mice correlated with the increase in bacterial numbers in the organ, while no augmentation of apoptosis was observed in the liver of IFN-gamma(-/-) mice irrespective of the marked increase in bacterial numbers in the organs, indicating that augmentation of liver apoptosis may not be merely due to the increase in bacterial growth in the organs. These results suggest that TNF-alpha and IL-6 may play an important role in protecting the liver from apoptosis in lethal L. monocytogenes infection.

Animals↗

PubMed2000

Effect of a matrix metalloproteinase inhibitor on host resistance against Listeria monocytogenes infection.

Hydroxy acid-based matrix metalloproteinase (MMP) inhibitors have been shown to inhibit tumor infiltration and growth, endotoxin shock, and acute graft-versus-host disease. Blockade of the release of soluble tumor necrosis factor-alpha (TNF-alpha) and CD95 ligand (CD95L; FasL) from cell-associated forms is reportedly involved in the mechanism of the drug effect. We investigated the effect of a MMP inhibitor, KB-R7785, on host resistance against Listeria monocytogenes infection, in which TNF-alpha is essentially required for the defense, in mice. The administration of KB-R7785 exacerbated listeriosis, while the drug prevented lethal shock induced by lipopolysaccharide and D-galactosamine. KB-R7785 inhibited soluble TNF-alpha production in spleen cell cultures stimulated by heat-killed L. monocytogenes and the drug treatment reduced serum TNF-alpha levels in infected mice, whereas the compound was ineffective on the modulation of interferon-gamma and interleukin-10 production. The effect of KB-R7785 was considered to be dependent on TNF-alpha because the drug failed to affect L. monocytogenes infection in anti-TNF-alpha monoclonal antibody-treated mice and TNF-alpha knockout mice. Anti-CD95L monoclonal antibody was also ineffective on the infection. These results suggest that induction of infectious diseases, to which TNF-alpha is critical in host resistance, should be considered in MMP inhibitor-treated hosts.

Animals↗

PubMed2000

IL-18 and IL-12 induce intestinal inflammation and fatty liver in mice in an IFN-gamma dependent manner.

BACKGROUND: In murine models of inflammatory bowel disease, colonic inflammation is considered to be caused by an aberrant Th1-type immune response. AIM: To investigate if systemic administration of interleukin (IL)-12 and IL-18 to wild-type BALB/c mice induces liver injury and intestinal inflammation, and if pathological changes are observed, what cytokines are involved. METHODS: Mice (BALB/c-wild-type (wt), MRL-lpr/lpr, BALB/c-interferon gamma knock out (IFN-gamma KO), C57BL/6-inducible nitric oxide synthase (iNOS) KO, and BALB/c tumour necrosis factor alpha (TNF-alpha) KO) were injected intraperitoneally each day with IL-12 (20 ng/g/mouse) and/or IL-18 (200 ng/g/mouse). RESULTS: Administration of IL-12 and IL-18 to BALB/c-wt mice induced prominent intestinal mucosal inflammation and fatty liver, leading to piloerection, bloody diarrhoea, and weight loss. IL-12 and IL-18 induced striking elevations in serum levels of IFN-gamma that caused NO production, although increased NO had no exacerbating effect on mice. Moreover, iNOS KO mice, or MRL lpr/lpr mice lacking functional Fas were equally susceptible to IL-12 and IL-18. Administration of IL-12 and IL-18 did not induce TNF-alpha production in wild-type mice, and the same treatment to TNF-alpha KO mice induced intestinal mucosal inflammation. Furthermore, they had diffuse and dense infiltration of small fat droplets in their hepatocytes associated with an increase in serum levels of liver enzymes. In contrast, the same treatment in IFN-gamma KO BALB/c mice and iNOS KO mice did not induce these changes. CONCLUSIONS: Our study strongly indicates that IL-18 together with IL-12 induces intestinal mucosal inflammation in an IFN-gamma dependent but TNF-alpha, NO, and Fas ligand independent manner, and fatty liver is dependent on IFN-gamma and NO.

Animals↗

PubMed2000

[Staging laparoscopy for a patient with advanced gastric cancer whose serum CA 19-9 level decreased remarkably after 2 courses of F/P therapy].

The prognosis of patients with Stage IVb gastric cancer remains poor, and therapy for these patients is not easy. Recently, neoadjuvant chemotherapy is thought to be one of the better strategies for such patients. In this paper, we report a 48-year-old female patient with advanced gastric cancer whose serum CA 19-9 level decreased remarkably after 2 courses of F/P therapy. We also operated on this patient with staging laparoscopy, a new and more useful technique for the patients such as the present one. The advantages of staging laparoscopy are as follows: 1. The entire intraabdominal space can be observed from a small wound, and the clinical stage of the patient can be diagnosed more correctly. 2. It is easy to obtain cells from small amounts of ascites or tissues of small nodules in the abdominal wall and lymph node involvements. 3. Patients suffer less pain and movement of the body is not as limited after operation. 4. Administering drugs into the intra abdominal space is easy using this technique. Staging laparoscopy might therefore be one of the better surgical strategies for the patients with advanced patients when selecting a suitable therapy.

Adenocarcinoma↗

PubMed1999

Quantitative trait loci that regulate plasma lipid concentration in hereditary obese KK and KK-Ay mice.

To identify quantitative trait loci (QTLs) responsible for regulating plasma lipid concentration associated with obesity, linkage analysis was carried out on the 190 F2 progeny of a cross between C57BL/6J female and KK-Ay (Ay allele at the agouti locus congenic) male. In F2 a/a (agouti locus genotype) mice, two QTLs were identified on chromosome 1 and a QTL on chromosome 3 for total-cholesterol. A QTL for HDL-cholesterol was identified on chromosome 1 and a QTL for NEFA on chromosome 9. In F2 Ay/a mice, two QTLs for HDL-cholesterol were found on chromosome 1. Loci for other lipids with suggestive linkage were also identified. In both F2 mice, one QTL on chromosome 1 for total- and HDL-cholesterol was mapped near D1Mit150, in the vicinity of the apolipoprotein A-II (Apoa2) locus. Seven nucleotide substitutions out of 309 nucleotide apolipoprotein A-II cDNA sequences were identified between KK and C57BL/6J. The Ay allele may be an indication of the plasma lipid levels, but its influence was less apparent than in the case of weight control. The loci for lipids were not on identical chromosomes with those previously identified for obesity, suggesting that hyperlipidemia in KK does not coincidentally occur with obesity.

Alleles↗

PubMed1999

Genetic analysis of neonatal death with growth retardation in F(1) male Dh/+ mice.

Nearly all F(1) male mice with Dh/+ genotype between DDD female and DH-Dh/+ male die within a few days after birth; however, this is not observed in the reciprocal cross. The F(1) Dh/+ males usually exhibit growth retardation prior to death. To identify the putative genetic locus or loci in DDD genome that cause the abnormalities in the presence of the Dh, a linkage analysis was carried out in backcross progeny of a cross of (DDD female x DH-+/+ male) F(1) female x DH-Dh/+ male. Appearance of growth retardation was examined from the day of birth, and both growth-retarded and normally weaned Dh/+ males were genotyped for microsatellite marker loci spanning autosomes and the X Chromosome (Chr). Significant evidence for linkage was identified on the distal edge of the X Chr, near the microsatellite marker of DXMit135. Furthermore, among mice from DDD female x reciprocal F(1)Dh/+ male produced between DH-Dh/+ and progenitor strains (C57BL/6J, C3H/HeJ and BALB/cA), only the progeny from female DDD x male (female DH-Dh/+ x male C3H/HeJ) F(1) Dh/+ male did not show any lethality and/or growth retardation. Thus, the lethality in F(1) Dh/+ males accompanied by growth retardation is caused by the interactions between the Dh gene, X Chr, and Y Chr. Based on the CAG repeat sequence length polymorphism among Mus musculus musculus Sry gene, C3H/HeJ was different from C57BL/6J, BALB/cA, and DH. These data suggest that there are at least two functional types of Y Chr in Mus musculus musculus.

Amino Acid Sequence↗

PubMed1999

Tumor necrosis factor alpha is a key mediator in the regulation of experimental Trypanosoma brucei infections.

In order to evaluate during experimental Trypanosoma brucei infections the potential role of tumor necrosis factor alpha (TNF-alpha) in the host-parasite interrelationship, C57BL/6 TNF-alpha knockout mice (TNF-alpha-/-) as well as C57BL/6 wild-type mice were infected with pleomorphic T. brucei AnTat 1.1 E parasites. In the TNF-alpha-/- mice, the peak levels of parasitemia were strongly increased compared to the peak levels recorded in wild-type mice. The increased parasite burden did not reflect differences in clearance efficacy or in production of T. brucei-specific immunoglobulin M (IgM) and IgG antibodies. Trypanosome-mediated immunopathological features, such as lymph node-associated immunosuppression and lipopolysaccharide hypersensitivity, were found to be greatly reduced in infected TNF-alpha-/- mice. These results demonstrate that, during trypanosome infections, TNF-alpha is a key mediator involved in both parasitemia control and infection-associated pathology.

Animals↗

PubMed1999

Role of tumor necrosis factor-alpha in Mycobacterium-induced granuloma formation in tumor necrosis factor-alpha-deficient mice.

To study the role of TNF-alpha in mycobacterial infection, we generated TNF-alpha-knockout (KO) mice, in which the third and fourth exons of the TNF-alpha gene were disrupted. The C57BL/6 KO mice were injected with virulent Mycobacterium tuberculosis strain Kurono or avirulent bacillus Calmette-Guérin (BCG) Pasteur (10(6) colony-forming units), through the tail veins. The major organs were removed at weekly intervals, and morphologic observation, assays of IL-1, IL-12, IFN-gamma, and inducible nitric oxide synthase mRNA expression, and colony counts in the lungs and spleen were performed. Peritoneal macrophages from BCG- and H37Rv strain-treated mice produced significant levels of nitric oxide after stimulation in vitro. Formation of abscesses was seen only in the Kurono-treated groups, and these abscesses contained large numbers of mycobacteria. The administration of recombinant TNF-alpha significantly ameliorated the mycobacterial lesions. IFN-gamma mRNA was expressed significantly in virulent H37Rv-treated groups with time, and the number of mycobacterial colonies per unit weight increased remarkably with time. Nitric oxide production was not observed in H37Rv-treated groups but was seen in BCG-treated groups. We concluded that TNF-alpha played an important role in protective immunity against virulent mycobacteria. Because avirulent mycobacteria did not induce granulomas in TNF-alpha-KO mice, TNF-alpha played an indirect role in granuloma formation.

Animals↗

PubMed1998

Genetics of obesity in KK mouse and effects of A(y) allele on quantitative regulation.

KK mouse is known as a polygenic model for noninsulin-dependent diabetes mellitus with moderate obesity. To identify the quantitative trait loci (QTLs) responsible for the body weight in KK, linkage analysis with 97 microsatellite markers was carried out into 192 F2 progeny, comprising 93 mice with a/a genotype at agouti locus and 99 mice with A(y)/a genotype, of a cross between C57BL/6J female and KK-A(y) (A(y) congenic) male, thereby the influence of A(y) allele on the quantitative regulation of body weight was also examined. In F2 a/a mice, we identified a QTL on Chromosome (Chr) 4, and two loci with suggestive linkage on Chrs 15 and 18. In F2 A(y)/a mice, a QTL was identified on Chr 6, and two loci with suggestive linkage were identified on Chrs 4 and 16. That the QTL on Chr 4 was held in common between F2 a/a and F2 A(y)/a progenies implies that this locus may be a primary component regulating body weight in KK and KK-A(y). These results suggest that the body weight in KK is controlled by multiple genes, and the different combination of loci is involved in the presence of A(y) allele. The QTL on Chr 6 seemed to determine the body weight by controlling fat deposition, because the linkage was identified on body weight and adiposity, and is suggested to be a component involved in the metabolic pathway in obesity caused by the A(y) allele.

Agouti Signaling Protein↗