The mechanism of how fluoride causes fluorosis remains unknown. Exposure to fluoride can inhibit protein synthesis, and this may also occur by agents that cause endoplasmic reticulum (ER) stress. When translated proteins fail to fold properly or become misfolded, ER stress response genes are induced that together comprise the unfolded protein response. Because ameloblasts are responsible for dental enamel formation, we used an ameloblast-derived cell line (LS8) to characterize specific responses to fluoride treatment. LS8 cells were growth-inhibited by as little as 1.9 -3.8 ppm fluoride, whereas higher doses induced ER stress and caspase-mediated DNA fragmentation. Growth arrest and DNA damage-inducible proteins (GADD153/CHOP, GADD45␣), binding protein (BiP/glucose-responsive protein 78 (GRP78), the non-secreted form of carbonic anhydrase VI (CA-VI), and active X-box-binding protein-1 (Xbp-1) were all induced significantly after exposure to 38 ppm fluoride. Unexpectedly, DNA fragmentation increased when GADD153 expression was inhibited by short interfering RNA treatment but remained unaffected by transient GADD153 overexpression. Analysis of control and GADD153 ؊/؊ embryonic fibroblasts demonstrated that caspase-3 mediated the increased DNA fragmentation observed in the GADD153 null cells. We also demonstrate that mouse incisor ameloblasts are sensitive to the toxic effects of high dose fluoride in drinking water. Activated Ire1 initiates an ER stress response pathway, and mouse ameloblasts were shown to express activated Ire1. Ire1 levels appeared induced by fluoride treatment, indicating that ER stress may play a role in dental fluorosis. Low dose fluoride, such as that present in fluoridated drinking water, did not induce ER stress.
Endoscopic necrosectomy can be an effective technique for infected WOPN and requires a relatively short treatment period. However, serious complications can arise, including death. Therefore, patients should be carefully selected, and knowledgeable, skilled, and experienced operators should perform the procedure. Further research into safer technologies is required in order to reduce the associated morbidity and mortality.
S100A4 is an intracellular calcium-binding protein expressed by osteoblastic cells. However, its roles in bone physiology are unknown. Because before matrix mineralization, its expression is markedly diminished, we hypothesized that S100A4 negatively regulates the mineralization process. In this study, we investigated the effects of the inhibition of S100A4 synthesis on osteoblast differentiation and in vitro mineralized nodule formation. Inhibition of S100A4 synthesis was achieved by an antisense approach in the mouse osteoblastic cell line MC3T3-E1. Cell clones that synthesized low levels of S100A4 (AS clones) produced markedly increased number of mineralized nodules at much earlier stages in comparison with controls as demonstrated by Alizarin red S and von Kossa staining. The expression of type I collagen (COLI) and osteopontin (OPN) increased in AS clones compared with controls. Bone sialoprotein (BSP) and osteocalcin (OCN), molecules associated with mineralization and markers for mature osteoblastic phenotype, were expressed in AS clones before their detection in controls. Because S100A4 was not localized in the nucleus of MC3T3-E1 cells and AS clones, it is unlikely that S100A4 directly regulates the expression of these genes. Moreover, the expression of Cbfa1/Osf-2 and Osx, transcription factors necessary for the expression of osteoblast-associated genes, remained unchanged in AS clones, indicating that S100A4 may be downstream to these transcription factors. These findings indicate that S100A4 is a novel negative regulator of matrix mineralization likely by modulating the process of osteoblast differentiation. (J Bone Miner Res 2003;18:493-501)
Adult ABO-incompatible liver transplantation has been known to be associated with markedly desperate outcomes. Antibody-mediated rejection (AMR) has been recognized as one of the primary causes of these desperate outcomes, but its clinical features and significance have not been well understood. Recently, some clinicians have succeeded in improving the outcome of adult ABO-incompatible liver transplantation. However, in some transplant patients undergoing these treatments, AMR has still led to graft losses. We recently encountered two patients suffering from AMR after adult ABO-incompatible liver transplantation and remedied their conditions with various therapeutic modalities including direct hepatic infusion therapy and gamma-globulin bolus infusion therapy combined with plasmapheresis. In this article, we describe the clinical features of these patients and the therapeutic strategies we applied. Furthermore, we show the histologic course of the recovery from AMR in the second patient, from whom we were able to extract serial liver biopsies.
Abstract. Matrilysin, MMP-7, is an important target for antimetastasis therapy of colorectal cancer because it is a strong proteolytic factor secreted from the cancer cell itself and it induces tumor angiogenesis. In a previous report, we showed that matrilysin accelerated human umbilical vein endothelial cell (HUVEC) proliferation in low serum conditioned medium. In the present study, we show that matrilysin stimulation decreased VE-cadherin expression, induced accumulation of beta-catenin in the nucleus of the HUVEC, and up-regulated matrilysin mRNA expression. These results compel a hypothesis that matrilysin cleaves VE-cadherin and releases beta-catenin from the VE-cadherin/catenin complex; the free beta-catenin can activate T-cell factor (Tcf) DNA binding protein, which accelerates cell proliferation and matrilysin expression.
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