Search PubMed⌕ Search

Biomedical subjects

S Hirose

Publications and source records attributed to S Hirose.

At least 73 records · Page 4Linked to original sources
PubMed2000

Cryptosporidium parvum: functional complementation of a parasite transcriptional coactivator CpMBF1 in yeast.

We report here the identification of a novel multiprotein bridging factor type 1 from the apicomplexan Cryptosporidium parvum (CpMBF1), one of the opportunistic pathogens in AIDS patients. In slime molds, insects, and humans, MBF1-regulated systems have been associated with cell differentiation, which indicates that CpMBF1 could be responsible for the activation of similar systems in C. parvum during its complex life cycle. Because of the difficulties and high cost in obtaining sufficient and purified C. parvum material for molecular and biochemical analyses, well-characterized yeast genetic systems may be useful for investigating the functions of C. parvum genes. In this study, the function of CpMBF1 as an interconnecting element between a DNA-binding regulator and TATA-box-binding protein (TBP) was confirmed using a yeast complementation assay. Under conditions of histidine starvation, an MBF1-deficient strain of Saccharomyces cerevisiae was unable to activate the HIS3 gene, which encodes imidazoleglycerol-phosphate dehydratase (IGPDH), and thus became sensitive to 3-amino triazole, an inhibitor of this enzyme. Upon introduction of parasite CpMBF1 into S. cerevisiae, 3-amino triazole resistance of the MBF1-deficient strain was restored to wild-type levels, and Northern blot analysis revealed that CpMBF1 was able to activate HIS3 transcription in response to histidine starvation.

Amino Acid Sequence↗
PubMed2000

Treatment of lupus in NZB/W F1 mice with monoclonal antibody against Fas ligand.

Since Fas ligand (FasL) can induce apoptosis of Fas-bearing cells, Fas/FasL interactions can play a critical role in maintaining self-tolerance. Fas/FasL interactions in lupus-like autoimmune disease have been well characterized in studies using either Fas or FasL mutant mice. However, the effect of the defective FasL-mediated signaling on the establishment of lupus in other mouse strains, such as NZB/W (B/W) F1, remains uncertain. In the present study, we examined the effect of anti-FasL monoclonal antibody (mAb) on the development of lupus. Treatment of B/W F1 mice with anti-FasL mAb augmented IgG1- and IgG2a-type anti-dsDNA Ab production. However, treatment of B/W F1 mice with anti-FasL mAb also significantly prevented the development of lupus nephritis. These results indicate that Fas/FasL interactions not only regulate IgG-type autoantibody production, but also influence the development of lupus nephritis in B/W F1 mice.

Animals↗
PubMed2000

Changes of CD4/CD8 ratio and interleukin-16 in systemic lupus erythematosus.

The authors investigated changes in the ratio of CD4+ to CD8+ T cells (CD4/CD8 ratio) and T-cell activation, indicated by human leukocyte antigen (HLA)-DR expression, in patients with systemic lupus erythematosus (SLE) following treatment. An increase was observed in the CD4/CD8 ratio as well as a decrease in the expression of HLA-DR on T cells with the improvement of clinical manifestations on treatment with steroids or cyclosporine (CSA). In addition, steroid treatment suppressed whereas CSA treatment exerted no perceptible influence on the serum interleukin (IL)-16 level, concurrent with changes in T-cell phenotypes. This indicated that the mechanism of the change in the CD4/CD8 ratio differed depending on the drug, and CD8+ T cells could play an important role in reducing this ratio. The CD4/CD8 ratio and HLA-DR expression may be good indicators of therapeutic efficacy in some SLE patients.

Adrenal Cortex Hormones↗
PubMed2000

Polymorphisms in IgG Fc receptor IIB regulatory regions associated with autoimmune susceptibility.

Autoimmune diseases involve multiple genes. While functions of these genes are largely unknown, some may be related to an intrinsic hyperresponsiveness of B cells. B-cell responses are controlled by signaling thresholds through the B-cell antigen receptor (BCR) complex. The B1 isoform of type II IgG Fc receptors (FcgammaRIIB1) is exclusively expressed on B cells and serves as a negative regulator for inhibiting BCR-elicited activation. Thus, its allelic variants associated with functional deficits could be examined for possible associations with susceptibility to autoimmune diseases. We found that there are three types of polymorphisms in the reported FcgammaRIIB transcription regulatory regions in mouse strains. Compared to normal healthy mouse strains (group III), autoimmune disease-prone strains (group I) share three deletion sites: two in the promoter region and one in the third intron. Strains (group II) that per se are not autoimmune-prone, but have potentials to accelerate autoimmune diseases share two deletion sites in the third intron: one identical to that in group I and the other unique to group II. These polymorphisms correlated well with extents of down-regulation of FcgammaRIIB1 expression in germinal-center B cells upon stimulation with antigens and up-regulation of IgG antibody responses. Our data imply that these FcgammaRIIB polymorphisms are selected evolutionarily for natural defense against pathogens, and that such polymorphisms may, in turn, form the basis of one aspect of autoimmune susceptibility.

Animals↗
PubMed2000

Localization of porcine trappin-2 (SKALP/elafin) in trachea and large intestine by in situ hybridization and immunohistochemistry.

Trappin-2 (SKALP/elafin), an elastase inhibitor, belongs to a unique family of proteinase inhibitors that are covalently anchored at the site of action through their transglutaminase substrate domain and are collectively called trappins. The transglutaminase substrate domain is therefore called "cementoin moiety". Currently, human, porcine, and bovine trappin-2 (SKALP/elafin) have been characterized. Previously, we showed that porcine trappin-2 (SKALP/elafin) occurs mainly in the trachea and large intestine. To determine the localization of trappin-2 (SKALP/elafin) at the cellular level, we carried out in situ hybridization and immunohistochemistry using the porcine trachea and large intestine and found that trappin-2 (SKALP/elafin) is produced in the goblet cells of the tracheal epithelium and of the large intestinal crypts. These locations suggest that trappin-2 (SKALP/elafin) is secreted onto the luminal surface of the trachea and crypts of Lieberkuhn and plays a protective role against destructive bacterial proteinases.

Animals↗
PubMed2000

Are some idiopathic epilepsies disorders of ion channels?: A working hypothesis.

Epilepsy is a common neurological disease and encompasses a variety of disorders with paroxysms. Although there is a genetic component in the pathogenesis of epilepsy, the molecular mechanisms of this syndrome remains poorly understood. Linkage analysis and positional cloning have not been sufficient tools for determining the pathogenic mechanisms of common idiopathic epilepsies, and hence, novel approaches, based on the etiology of epilepsy, are necessary. Recently, many paroxysmal disorders, including, epilepsy, have been considered to be due to ion channel abnormalities or channelopathies. Results of recent studies employing gene analysis in animal models of epilepsy and human familial epilepsies support the hypothesis that at least some of the so called idiopathic epilepsies, i.e. epilepsies currently, classified as idiopathic could be considered as a channelopathy. This hypothesis is consistent with the putative prerequisites for genes responsible for the majority of idiopathic epilepsies that can adequately explain the following characteristics of epilepsy. Neuronal hyperexcitability, dominant inheritance with various penetrance, pharmacological role of some conventional antiepileptic drugs, age dependency in the onset of epilepsy, and the involvement of genetic factors in the pathogenesis of post-traumatic epilepsy. Search for mutations in ion channels expressed in the central nervous system may help in finding defects underlying some of idiopathic epilepsies, thereby enhancing, our understanding of the molecular pathogenesis of epilepsy. A working hypothesis to view certain idiopathic epilepsies as disorders of ion channels should provide a new insight to our understanding of epilepsy and allow the design of novel therapies.

Animals↗
PubMed2000

CD8(+) T cell-mediated skin disease in mice lacking IRF-2, the transcriptional attenuator of interferon-alpha/beta signaling.

The balanced action of cytokines is known to be critical for the maintenance of homeostatic immune responses. Here, we report the development of an inflammatory skin disease involving CD8(+) T cells, in mice lacking the transcription factor, interferon regulatory factor-2 (IRF-2). CD8(+) T cells exhibit in vitro hyper-responsiveness to antigen stimulation, accompanied with a notable upregulation of the expression of genes induced by interferon-alpha/beta (IFN-alpha/beta). Furthermore, both disease development and CD8(+) T cell abnormality are suppressed by the introduction of nullizygosity to the genes that positively regulate the IFN-alpha/beta signaling pathway. IRF-2 may represent a unique negative regulator, attenuating IFN-alpha/beta-induced gene transcription, which is necessary for balancing the beneficial and harmful effects of IFN-alpha/beta signaling in the immune system.

Animals↗
PubMed2000

Elafin is induced in epidermis in skin disorders with dermal neutrophilic infiltration: interleukin-1 beta and tumour necrosis factor-alpha stimulate its secretion in vitro.

BACKGROUND: Elafin, an elastase inhibitor produced by keratinocytes, is overexpressed in the subcorneal region of skin affected by psoriasis, a major feature of which is epidermal infiltration by neutrophil leucocytes. OBJECTIVES: We studied the expression of elafin in the epidermis in other skin disorders characterized by dermal neutrophil infiltration and in skin disorders with dermal lymphocyte infiltration. PATIENTS/METHODS: We examined biopsies from the lesional skin of patients with Behçet's syndrome, Sweet's syndrome, pyoderma gangrenosum, cutaneous allergic vasculitis and acute bacterial infection (cellulitis), and from the skin of patients with chronic prurigo, discoid lupus erythematosus and psoriasis. We performed in vitro experiments using cultured keratinocytes treated with mediators such as interleukin (IL)-1 beta, tumour necrosis factor (TNF)-alpha, IL-6, neutrophil elastase and interferon (IFN)-gamma. RESULTS: Anti-elafin antibody showed a strong reaction with the subcorneal region of the epidermis in patients with Behçet's syndrome, Sweet's syndrome, pyoderma gangrenosum, cutaneous allergic vasculitis and acute bacterial infection (cellulitis), but showed no reaction in skin from patients with dermal lymphocyte infiltration such as is seen in chronic prurigo and discoid lupus erythematosus. The in vitro experiments demonstrated that treatment with IL-1 beta and TNF-alpha resulted in 2.6-fold and 4-fold stimulation of elafin secretion, respectively, whereas IL-6, neutrophil elastase and IFN-gamma caused no significant changes in elafin release. CONCLUSIONS: These results suggest that inflammatory mediators such as IL-1 beta or TNF-alpha secreted by dermal neutrophils may be involved in overexpression of elafin in keratinocytes; this could protect the epidermis from degradation by dermal neutrophil infiltration.

Cell Culture Techniques↗
PubMed2000

The conserved nuclear receptor Ftz-F1 is required for embryogenesis, moulting and reproduction in Caenorhabditis elegans.

BACKGROUND: Nuclear receptors are essential players in the development of all metazoans. The nematode Caenorhabditis elegans possesses more than 200 putative nuclear receptor genes, several times more than the number known in any other organism. Very few of these transcription factors are conserved with components of the steroid response pathways in vertebrates and arthropods. Ftz-F1, one of the evolutionarily oldest nuclear receptor types, is required for steroidogenesis and sexual differentiation in mice and for segmentation and metamorphosis in Drosophila. RESULTS: We employed two complementary approaches, direct mutagenesis and RNA interference, to explore the role of nhr-25, a C. elegans ortholog of Ftz-F1. Deletion mutants show that nhr-25 is essential for embryogenesis. RNA interference reveals additional requirements throughout the postembryonic life, namely in moulting and differentiation of the gonad and vulva. All these defects are consistent with the nhr-25 expression pattern, determined by in situ hybridization and GFP reporter activity. CONCLUSIONS: Our data link the C. elegans Ftz-F1 ortholog with a number of developmental processes. Significantly, its role in the periodical replacement of cuticle (moulting) appears to be evolutionarily shared with insects and thus supports the monophyletic origin of moulting.

Animals↗
PubMed2000

Expression of vascular endothelial growth factor and its receptors correlates closely with formation of the plexiform lesion in human pulmonary hypertension.

The pulmonary vasculature exhibits various morphological changes in patients with pulmonary hypertension (PH). Among them, the plexiform lesion is one of the most characteristic vascular lesions, although nothing is known about the molecular mechanisms of its formation. In the present study, the expression of vascular endothelial growth factor (VEGF), an endothelial cell-specific angiogenic mitogen, and its receptors, fms-like tyrosine kinase (Flt-1) and kinase insert domain-containing receptor (KDR), in the lungs of five cases with PH, were examined. By in situ hybridization, VEGF expression was found in modified smooth muscle cells inside the plexiform lesions as well as in medial smooth muscle cells of the arteries adjacent to the lesions. The expression of Flt-1 mRNA was observed in endothelial cells of the arteries adjacent to the plexiform lesions, while KDR mRNA was expressed in the endothelial cells inside the plexiform lesions. VEGF was immunolocalized to the endothelial cells expressing its receptors as well as the modified smooth muscle cells producing VEGF. These results demonstrate that VEGF and its receptors are upregulated with a close correlation to the plexiform lesions, and suggest that VEGF expressed by smooth muscle cells may activate the endothelial cells to form the plexiform lesions.

Adolescent↗
PubMed2000

Analysis of the proliferative potential of tumor cells after stereotactic radiosurgery for recurrent astrocytic tumors.

We analyzed the effectiveness of stereotactic radiosurgery (SRS) for recurrent astrocytic tumors histologically. Five patients were followed by pathological examination after radiosurgery treatment of recurrent astrocytic tumors. Histological diagnoses at the time of the last operation before SRS were Daumas-Duport grade II in two patients and grade IV (glioblastoma) in three patients. No histological diagnoses at the time of SRS were identified in any patients. Contrast enhanced lesions enlarged gradually on magnetic resonance (MR) images after SRS, and local control by SRS was judged as progressive disease radiologically in all patients. Four of five patients received re-operation after SRS, and the other patient died without re-operation and underwent post-mortem examination. After SRS, Ki-67 labeling indices (LIs) of recurrent astrocytomas initially diagnosed as grade II were 2.6% and 1.1%. These LIs were relatively lower than those of the control group of patients with recurrent grade II astrocytomas that were not treated by SRS. Ki-67 LIs of three glioblastomas after SRS were 23.5%, 18.6%, and 17.8%. These LIs were significantly lower than those before SRS (2.3%, 4.5%, and 0.9%). In the autopsy case, there was a significant difference between the LI of tumor cells in the radiosurgically treated region (0.9%) and that in the untreated region (29.2%). These results suggest that the proliferative potential of malignant astrocytic tumors in the radiosurgically treated area is reduced after SRS, and that radiological enlargement of enhanced lesions on MR images is due to propagation of the residual tumor cells that were not covered by radiosurgical target volume or to radiation necrosis. SRS may be a useful therapeutic tool in multidisciplinary treatment of malignant gliomas.

Adult↗
PubMed2000

Genetic regulation of anti-erythrocyte autoantibodies and splenomegaly in autoimmune hemolytic anemia-prone new zealand black mice.

New Zealand Black (NZB) mice spontaneously produce anti-erythrocyte autoantibodies (AEA) in association with splenomegaly, thus serving as a model for autoimmune hemolytic anemia. Although these autoimmune traits are inherited as a dominant fashion, expression in F(1) hybrids of NZB and most non-New Zealand strains is suppressed due to the contribution of wild-type modifying genes present in the latter strains. Using chromosomal microsatellite markers in the (C57BL/6 x NZB)F(1) x NZB backcross progeny, we mapped C57BL/6 modifying loci for AEA production and splenomegaly. Generation of AEA was found to be down-regulated by a combined effect of two major independently segregating dominant alleles-one linked to D7MIT30 on chromosome 7 and the other linked to D10MIT42 on chromosome 10. Splenomegaly was modified mainly by a single C57BL/6 allele linked to D4MIT58 on chromosome 4. Thus, the autoimmune hemolytic anemia in the NZB strain is under multigenic control and a combined action of not only susceptibility but also modifying alleles with suppressive activities affects the outcome of disease features in the progeny. There are potentially important candidate genes which may be linked to the regulation of AEA and splenomegaly.

Anemia, Hemolytic, Autoimmune↗
PubMed2000

Concentration of mRNA for the natriuretic peptide receptor-C in hypertrophic chondrocytes of the fetal mouse tibia.

The roles of natriuretic peptides in cardiovascular homeostasis have been well characterized. A recent study revealed that mice lacking natriuretic peptide receptor-C (NPR-C) exhibit skeletal-overgrowth. We therefore, performed in situ hybridization with riboprobes to determine the localization of mRNAs for receptors for natriuretic peptides in the growth plate of the fetal mouse tibia The amount of mRNA for NPR-A was below the detectable level in the growth plate. The mRNA for NPR-B was detected predominantly in proliferating chondrocytes. By contrast, high levels of mRNA for NPR-C were found in hypertrophic chondrocytes. In other regions of the growth plate, the levels of mRNA for NPR-C were very low. The patterns of expression of mRNAs for NPR-B and NPR-C, namely, subtype switching during differentiation from proliferating chondrocytes to hypertrophic chondrocytes, suggest that these receptors might be involved in the growth and differentiation of the growth plate during fetal development in the mouse.

Animals↗
PubMed2000

Insomnia related to biperiden withdrawal in two schizophrenic patients.

It is not uncommon for patients who are receiving antipsychotic medication to be given anticholinergic agents, such as biperiden, despite the relative absence of neurological side-effects. Two cases of schizophrenia are reported in which insomnia developed after biperiden withdrawal or reduction. The insomnia continued until biperiden treatment was reinstated, despite the fact that the patients did not exhibit signs or report symptoms indicative of antipsychotic drug-induced neurological side-effects. The occurrence of insomnia following the withdrawal of biperiden or reduction in the dose has not been previously reported. One potential explanation for the insomnia is cholinergic rebound following the withdrawal of biperiden.

Adult↗
PubMed2000

Vasoactive peptide-regulated gene expression during osteoblastic differentiation.

The formation of bone occurs via a series of events that are regulated by various hormones and cytokines. We previously reported that endothelin (ET) inhibits the mineralization by osteoblastic cells and natriuretic peptide (NP) promotes osteoblastic differentiation. Therefore, we attempted to identify the genes induced by ET or NP in mouse preosteoblastic MC3T3-E1 cells using the method known as differential display-polymerase chain reaction (DD-PCR) to understand the bone metabolism further. Consequently, we found that expression levels of mRNAs for fibronectin, type XII collagen, p160 Rho-associated kinase (ROCK), caldesmon, calpain, nucleolin and a novel gene with a zinc finger motif are downregulated in osteoblasts by ET stimuli. We also found that expression levels of mRNAs for eIF-4A and a novel gene are increased by C-type natriuretic peptide (CNP) stimuli.

Animals↗