Pustular‐type drug‐induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms due to carbamazepine with systemic muscle involvement

Drug‐induced hypersensitivity syndrome (DIHS)/drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe reaction usually associated with maculopapular eruptions and systemic involvement. Here we report the first case, to our knowledge, of DIHS/DRESS due to carbamazepine with acute generalized pustular bacterid‐like (AGPB‐like) eruptions and skeletal muscle involvement. Reviewing our case and the published work, we discuss pustular‐type DIHS/DRESS which, in most cases, involves acute generalized exanthematous pustulosis (AGEP)‐like skin eruptions in response to carbamazepine. Pustular eruptions may appear in relatively few cases of DIHS/DRESS, in particular, when the causative drug is carbamazepine and, even in cases of intractable pustular bacterid‐like eruptions, a reaction to a drug should be suspected. Skeletal muscle involvement may be associated with DIHS/DRESS as one of its systemic manifestations.     

Pore formation of thermostable direct hemolysin secreted from Vibrio parahaemolyticus in lipid bilayers

Vibrio parahaemolyticus secretes thermostable direct hemolysin (TDH), a major virulence factor. Earlier studies report that TDH is a pore-forming toxin. However, the characteristics of pores formed by TDH in the lipid bilayer, which is permeable to small ions, remain to be elucidated. Ion channel-like activities were observed in lipid bilayers containing TDH. Three types of conductance were identified. All the channels displayed relatively low ion selectivity, and similar ion permeability. The Cl- channel inhibitors, DIDS, glybenclamide, and NPPB, did not affect the channel activity of pores formed by TDH. R7, a mutant toxin of TDH, also forms pores with channel-like activity in lipid bilayers. The ion permeability of these channels is similar to that of TDH. R7 binds cultured cells and liposomes to a lower extent, compared to TDH. R7 does not display significant hemolytic activity and cell cytotoxicity, possibly owing to the difficulty of insertion into lipid membranes. Once R7 is assembled within lipid membranes, it may assume the same structure as TDH. The authors propose that the single glycine at position 62, substituted with serine in the R7 mutant toxin, plays an important role in TDH insertion into the lipid bilayer.     

Angiotensin II-induced insulin resistance is enhanced in adrenomedullin-deficient mice

Insulin resistance and hypertension are common disorders that are closely related. Among several factors, oxidative stress has been reported to be intimately related to these diseases. To elucidate the involvement of oxidative stress in the development of insulin resistance in a hypertensive model, we administered angiotensin II (Ang II), which raises blood pressure and induces reactive oxygen radicals, to adrenomedullin (AM)-knockout heterozygous mice and examined the resulting changes in blood pressure and insulin resistance. Ang II was administered ip at a dosage of 640 ng/kg.min for 4 wk. The systolic blood pressure was significantly elevated in both AM-knockout heterozygous and wild-type mice to the same extent. On the other hand, Ang II attenuated insulin sensitivity more strongly in AM-knockout heterozygous mice than in wild-type mice, when measured using 2- deoxyglucose uptakes in the soleus muscle. Ang II also induced a higher urinary excretion of isoprostane, a marker of oxidative stress. Furthermore, the production of oxidative stress in the soleus muscles of angiotensin-treated mice, measured using electronic spin resonance, was significantly higher than that in AM-knockout heterozygous mice. Moreover, 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, a superoxide scavenger mimetic, normalized the insulin resistance induced by Ang II without affecting the blood pressure in both groups. The present results suggest that, in an Ang II-treated mouse model, insulin resistance is induced by oxidative stress through a mechanism that is independent of blood pressure, and that AM can act as a protective peptide against insulin resistance via its intrinsic antioxidant effect.     

Laminin- and fibronectin-like molecules produced by periodontal ligament fibroblasts under serum-free culture are potent chemoattractants for gingival epithelial cells

Previously, we revealed that hepatocyte growth factor (HGF) or an HGF-like factor secreted by periodontal ligament fibroblasts (PLF) and gingival fibroblasts cultured in the presence of serum was a major chemoattractant for gingival epithelial cells, and suggested that it might play a role in epithelial invasion. However, our recent study showed that serum-free culture of PLF and gingival fibroblasts produced potent chemoattractants other than HGF for gingival epithelial cells. To identify these chemoattractants, PLF-conditioned medium (PLF-CM) from serum-free cultures was obtained, concentrated, and separated by gel filtration column chromatography, and the chemotactic activity for gingival epithelial cells of each eluted fraction was monitored by a modified Boyden chamber assay. The chemoattractant activity was eluted at a molecular mass of around 600 kDa, which would include laminin and fibronectin, but not HGF, determined by ELISA. The chemotactic activity was reduced by treatment with antilaminin and/or antifibronectin polyclonal antibodies. Western blots using both antibodies revealed that the PLF-CM contained laminin- and fibronectin-like molecules. Along with HGF, these large glycoprotein molecules produced by PLF may be involved in the pathogenesis and progression of periodontitis by inducing the apical migration of epithelial cells.     

Development and characterization of a model of liver metastasis using human colon cancer HCT-116 cells

In order to develop a model of liver metastasis of human gastrointestinal cancer cells, we examined the potential of 10 human colon and stomach cancer cell lines (HT-29, WiDr, HCT-116, HCT-15, HCC-2998, MKN7, MKN28, MKN45, MKN74 and St-4) to form liver metastases in nude mice. Among the cell lines, HCT-116 cells consistently formed gross liver metastases when injected into the spleens of nude mice. In contrast, other human colon and stomach cancer cells produced little or no liver metastasis. In order to analyze the high metastatic potential of HCT-116 cells, the adhesion potential was compared between HCT-116 cells and the other colon cancer cell lines. HCT-116 cells showed more efficient adhesion to fibronectin (FN) than other cells. Furthermore, FN enhanced haptotaxis of HCT-116 cells, but not of other colon cancer cells. The high adhesion potential to FN and enhanced haptotaxis may contribute, at least in part, to the high metastatic potential of HCT-116. To assess the value of this newly developed model of liver metastasis, we compared the ability of four anticancer drugs (fluorouracil, doxifluridine, paclitaxel and irinotecan) to inhibit the formation of liver metastases. Paclitaxel and irinotecan showed strong inhibition of liver metastasis but fluorouracil and doxifluridine showed only slight inhibition. Therefore, this model of metastasis may be useful for screening anti-liver metastatic reagents. These results indicate that the HCT-116 liver-metastasis model should be useful for analyzing the molecular mechanism of liver metastasis and for evaluating new anti-liver metastatic drugs.     

Opposite regulation of epithelial-to-mesenchymal transition and cell invasiveness by periostin between prostate and bladder cancer cells

We previously showed that periostin expression is downregulated in human bladder cancer tissues and that ectopic expression of periostin suppresses the invasiveness of bladder cancer cells. However, in most other human cancers studied, the expression of periostin promotes cell invasiveness. In the present study, we investigated the regulation of the epithelial-to-mesenchymal transition (EMT) and cell invasiveness by periostin in bladder and prostate cancer cell lines, and found opposite regulation of EMT and cell invasiveness by periostin. Periostin upregulated E-cadherin expression in bladder cancer cells but downregulated it in prostate cancer cells. Periostin suppressed cell invasiveness in bladder cancer cells but promoted it in prostate cancer cells. Snail, a negative regulator of E-cadherin, was upregulated by periostin in prostate cancer cells, while Twist, another negative regulator of E-cadherin, was downregulated in bladder cancer cells. The C-terminal region of periostin was sufficient for these functions in bladder cancer cells but not in prostate cancer cells. Knockdown of endogenous Snail by siRNA suppressed cell invasiveness in prostate cancer cells expressing periostin. Periostin also suppressed Akt phosphorylation in bladder cancer cells but enhanced it in prostate cancer cells. Treatment with Akt inhibitor increased E-cadherin expression and suppressed both Twist expression and cell invasiveness of bladder cancer cells. These results indicate that Akt signaling plays a role in the cell-type-dependent regulation of E-cadherin expression and cell invasiveness by periostin via Snail and Twist.