Control of the pericentrosomal H2O2 level by peroxiredoxin I is critical for mitotic progression

Proteins associated with the centrosome play key roles in mitotic progression in mammalian cells. The activity of Cdk1-opposing phosphatases at the centrosome must be inhibited during early mitosis to prevent premature dephosphorylation of Cdh1—an activator of the ubiquitin ligase anaphase-promoting complex/cyclosome—and the consequent premature degradation of mitotic activators. In this paper, we show that reversible oxidative inactivation of centrosome-bound protein phosphatases such as Cdc14B by H₂O₂ is likely responsible for this inhibition. The intracellular concentration of H₂O₂ increases as the cell cycle progresses. Whereas the centrosome is shielded from H₂O₂ through its association with the H₂O₂-eliminating enzyme peroxiredoxin I (PrxI) during interphase, the centrosome-associated PrxI is selectively inactivated through phosphorylation by Cdk1 during early mitosis, thereby exposing the centrosome to H₂O₂ and facilitating inactivation of centrosome-bound phosphatases. Dephosphorylation of PrxI by okadaic acid–sensitive phosphatases during late mitosis again shields the centrosome from H₂O₂ and thereby allows the reactivation of Cdk1-opposing phosphatases at the organelle.     

ComC is required for the processing and translocation of ComGC, a pilin-like competence protein of Bacillus subtilis

ComGC is a cell surface-localized protein required for DNA binding during transformation in Bacillus subtilis. It resembles type IV prepilins in its N-terminal domain, particularly in the amino acid sequence surrounding the processing cleavage sites of these proteins. ComC is another protein required for DNA binding, which resembles the processing proteases that cleave type IV prepilins. We show here that ComGC is processed in competent cells and that this processing requires ComC. We also demonstrate that the PilD protein of Neisseria gonorrhoeae, a ComC homologue, can process ComGC in Escherichia coli, and that the ComC protein itself is the only B. subtilis protein needed to accomplish cleavage of ComGC in the latter organism. Based on NaOH-solubility studies, we have shown that in the absence of ComC, but in the presence of all other competence proteins, B. subtilis is incapable of correctly translocating ComGC to the outer face of the cell membrane. Finally, we show that ComGC can be cross-linked to yield a form with higher molecular mass, possibly a dimer, and present evidence suggesting that formation of the higher mass complex takes place in the membrane, prior to translocation. Formation of this complex does not require ComC or any of the comG products, other than ComGC itself.     

Pulmonary Toxocariasis Mimicking Invasive Aspergillosis in a Patient with Ulcerative Colitis

A 45-year-old-male who had underlying ulcerative colitis and presented with fever and dry cough. Initially, the patient was considered to have invasive aspergillosis due to a positive galactomannan assay. He was treated with amphotericin B followed by voriconazole. Nevertheless, the patient deteriorated clinically and radiographically. The lung biopsy revealed eosinophilic pneumonia, and ELISA for Toxocara antigen was positive, leading to a diagnosis of pulmonary toxocariasis. After a 10-day treatment course with albendazole and adjunctive steroids, the patient recovered completely without any sequelae. Pulmonary toxocariasis may be considered in patients with subacute or chronic pneumonia unresponsive to antibiotic agents, particularly in cases with eosinophilia.     

Heavy Hymenolepis nana Infection Possibly Through Organic Foods: Report of a Case

We encountered a patient with heavy Hymenolepis nana infection. The patient was a 44-year-old Korean man who had suffered from chronic hepatitis (type B) for 15 years. A large number of H. nana adult worms were found during colonoscopy that was performed as a part of routine health screening. The parasites were scattered throughout the colon, as well as in the terminal ileum, although the patient was immunocompetent. Based on this study, colonoscopy may be helpful for diagnosis of asymptomatic H. nana infections.     

Measurement of Shoulder Range of Motion in Patients with Adhesive Capsulitis Using a Kinect

Range of motion (ROM) measurements are essential for the evaluation for and diagnosis of adhesive capsulitis of the shoulder (AC). However, taking these measurements using a goniometer is inconvenient and sometimes unreliable. The Kinect (Microsoft, Seattle, WA, USA) is gaining attention as a new motion detecting device that is nonintrusive and easy to implement. This study aimed to apply Kinect to measure shoulder ROM in AC; we evaluated its validity by calculating the agreement of the measurements obtained using Kinect with those obtained using goniometer and assessed its utility for the diagnosis of AC. Both shoulders of 15 healthy volunteers and affected shoulders of 12 patients with AC were included in the study. The passive and active ROM of each were measured with a goniometer for flexion, abduction, and external rotation. Their active shoulder motions for each direction were again captured using Kinect and the ROM values were calculated. The agreement between the two measurements was tested with the intraclass correlation coefficient (ICC). Diagnostic performance using the Kinect ROM was evaluated with Cohen’s kappa value. The cutoff values of the limited ROM were determined in the following ways: the same as passive ROM values, reflecting the mean difference, and based on receiver operating characteristic curves. The ICC for flexion/abduction/external rotation between goniometric passive ROM and the Kinect ROM were 0.906/0.942/0.911, while those between active ROMs and the Kinect ROMs were 0.864/0.932/0.925. Cohen’s kappa values were 0.88, 0.88, and 1.0 with the cutoff values in the order above. Measurements of the shoulder ROM using Kinect show excellent agreement with those taken using a goniometer. These results indicate that the Kinect can be used to measure shoulder ROM and to diagnose AC as an alternative to goniometer.     

Hepatitis C virus represses E-cadherin expression via DNA methylation to induce epithelial to mesenchymal transition in human hepatocytes

Hepatitis C virus (HCV) core protein is known to induce promoter hypermethylation of tumor suppressor genes including E-cadherin to repress their expression when overexpressed in human hepatocytes; however, its actual role during HCV infection is still unknown. Here, we report that infection with HCV derived from pJFH-1 replicon system that mimics natural infection elevates protein levels of DNA methyltransferase 1 and 3b to enhance DNMT activity in human hepatocytes. As a consequence, HCV induced promoter hypermethylation of E-cadherin, resulting in repression of its expression. In addition down-regulation of E-cadherin by HCV led to epithelial–mesenchymal transition that is known to be a critical event during the late stage of tumorigenesis.