Ceftriaxone-associated Pseudolithiasis in Elderly People: Frequency and Risk Factors.

Objective Ceftriaxone (CTRX) is a widely used antibiotic because of its long plasma half-life and good tissue transmission. Many of the reported studies on CTRX-associated pseudolithiasis were performed in children. Although some studies have been published in adults, there are no studies limited to elderly people. The present study investigated CTRX-associated pseudolithiasis and explored its risk factors in the elderly. Methods We retrospectively reviewed 133 elderly patients (≥65 years old) treated with CTRX. Pseudolithiasis was defined as stones or sludge newly appearing in the gallbladder, as detected by computed tomography after the administration of CTRX. We evaluated the risk factors for pseudolithiasis using multivariate regression and inverse probability of treatment weighting analyses. Results Among the 133 patients, 24 (18%) developed CTRX-associated pseudolithiasis. In a multivariate analysis, the CTRX dose [odds ratio (OR) 4.54, 95% confidence interval (CI) 1.36-15.07, p=0.012] and CTRX treatment duration (OR 2.80, 95% CI 1.06-8.04, p=0.043) were significantly associated with pseudolithiasis formation. The cut-off value of the total CTRX dose associated with pseudolithiasis formation was 19 g. A propensity analysis determined that the frequency of pseudolithiasis was increased in patients treated with >19 g total CTRX compared with those who received ≤19 g in total (OR 4.06, 95% CI 1.45-11.32, p=0.008). Conclusion The incidence rate of CTRX-induced pseudolithiasis is high in elderly people, and the CTRX dose and CTRX treatment duration are significant risk factors for pseudolithiasis. A total dose of >19 g increases the likelihood of pseudolithiasis formation in elderly people treated with CTRX.

A histone-like protein of mycobacteria possesses ferritin superfamily protein-like activity and protects against DNA damage by Fenton reaction.

Iron is an essential metal for living organisms but its level must be strictly controlled in cells, because ferrous ion induces toxicity by generating highly active reactive oxygen, hydroxyl radicals, through the Fenton reaction. In addition, ferric ion shows low solubility under physiological conditions. To overcome these obstacles living organisms possess Ferritin superfamily proteins that are distributed in all three domains of life: bacteria, archaea, and eukaryotes. These proteins minimize hydroxyl radical formation by ferroxidase activity that converts Fe(2+) into Fe(3+) and sequesters iron by storing it as a mineral inside a protein cage. In this study, we discovered that mycobacterial DNA-binding protein 1 (MDP1), a histone-like protein, has similar activity to ferritin superfamily proteins. MDP1 prevented the Fenton reaction and protects DNA by the ferroxidase activity. The K(m) values of the ferroxidase activity by MDP1 of Mycobacterium bovis bacillus Calmette-Guérin (BCG-3007c), Mycobacterium tuberculosis (Rv2986c), and Mycobacterium leprae (ML1683; ML-LBP) were 0.292, 0.252, and 0.129 mM, respectively. Furthermore, one MDP1 molecule directly captured 81.4±19.1 iron atoms, suggesting the role of this protein in iron storage. This study describes for the first time a ferroxidase-iron storage protein outside of the ferritin superfamily proteins and the protective role of this bacterial protein from DNA damage.

Two cases of hepatocellular adenomatosis treated with transcatheter arterial embolization.

Hepatocellular adenoma is a rare benign tumor of the liver. However, some complications, such as hemorrhage, rupture, and malignant transformation, have been reported previously. Surgical resection is considered to be the best choice of treatment, when adenomas are increasing in size, while resection is difficult to perform when multiple adenomas develop throughout the liver. Here, we report two cases of multiple hepatocellular adenomatosis. One patient had a history of aplastic anemia and the other had glycogen storage disease. We treated them with transcatheter arterial embolization (TAE) to prevent hemorrhage and rupture. After TAE, most parts of the adenomas showed necrotic change. These cases suggest that TAE is an effective treatment of hepatocellular adenomatosis.

Control of cell wall assembly by a histone-like protein in Mycobacteria.

Bacteria coordinate assembly of the cell wall as well as synthesis of cellular components depending on the growth state. The mycobacterial cell wall is dominated by mycolic acids covalently linked to sugars, such as trehalose and arabinose, and is critical for pathogenesis of mycobacteria. Transfer of mycolic acids to sugars is necessary for cell wall biogenesis and is mediated by mycolyltransferases, which have been previously identified as three antigen 85 (Ag85) complex proteins. However, the regulation mechanism which links cell wall biogenesis and the growth state has not been elucidated. Here we found that a histone-like protein has a dual concentration-dependent regulatory effect on mycolyltransferase functions of the Ag85 complex through direct binding to both the Ag85 complex and the substrate, trehalose-6-monomycolate, in the cell wall. A histone-like protein-deficient Mycobacterium smegmatis strain has an unusual crenellated cell wall structure and exhibits impaired cessation of glycolipid biosynthesis in the growth-retarded phase. Furthermore, we found that artificial alteration of the amount of the extracellular histone-like protein and the Ag85 complex changes the growth rate of mycobacteria, perhaps due to impaired down-regulation of glycolipid biosynthesis. Our results demonstrate novel regulation of cell wall assembly which has an impact on bacterial growth.