Global properties of spacelike curves in Minkowski 3-space

We study global properties of closed spacelike curves in Minkowski 3-space

Genomic dissection of the Vibrio cholerae O-serogroup global reference strains: reassessing our view of diversity and plasticity between two chromosomes

Approximately 200 O-serogroups of Vibrio cholerae have already been identified; however, only 2 serogroups, O1 and O139, are strongly related to pandemic cholera. The study of non-O1 and non-O139 strains has hitherto been limited. Nevertheless, there are other clinically and epidemiologically important serogroups causing outbreaks with cholera-like disease. Here, we report a comprehensive genome analysis of the whole set of V. cholerae O-serogroup reference strains to provide an overview of this important bacterial pathogen. It revealed structural diversity of the O-antigen biosynthesis gene clusters located at specific loci on chromosome 1 and 16 pairs of strains with almost identical O-antigen biosynthetic gene clusters but differing in serological patterns. This might be due to the presence of O-antigen biosynthesis-related genes at secondary loci on chromosome 2

Evaluation of MC3T3-E1 Cell Osteogenesis in Different Cell Culture Media

Many biomaterials have been evaluated using cultured cells. In particular, osteoblast-like cells are often used to evaluate the osteocompatibility, hard-tissue-regeneration, osteoconductive, and osteoinductive characteristics of biomaterials. However, the evaluation of biomaterial osteogenesis-inducing capacity using osteoblast-like cells is not standardized; instead, it is performed under laboratory-specific culture conditions with different culture media. However, the effect of different media conditions on bone formation has not been investigated. Here, we aimed to evaluate the osteogenesis of MC3T3-E1 cells, one of the most commonly used osteoblast-like cell lines for osteogenesis evaluation, and assayed cell proliferation, alkaline phosphatase activity, expression of osteoblast markers, and calcification under varying culture media conditions. Furthermore, the various media conditions were tested in uncoated plates and plates coated with collagen type I and poly-L-lysine, highly biocompatible molecules commonly used as pseudobiomaterials. We found that the type of base medium, the presence or absence of vitamin C, and the freshness of the medium may affect biomaterial regeneration. We posit that an in vitro model that recapitulates in vivo bone formation should be established before evaluating biomaterials.ArticleInternational Journal of Molecular Sciences. 22(14):7752 (2021)journal articl

Cellular Responses of Human Lymphatic Endothelial Cells to Carbon Nanomaterials

One of the greatest challenges to overcome in the pursuit of the medical application of carbon nanomaterials (CNMs) is safety. Particularly, when considering the use of CNMs in drug delivery systems (DDSs), evaluation of safety at the accumulation site is an essential step. In this study, we evaluated the toxicity of carbon nanohorns (CNHs), which are potential DDSs, using human lymph node endothelial cells that have been reported to accumulate CNMs, as a comparison to fibrous, multi-walled carbon nanotubes (MWCNTs) and particulate carbon black (CB). The effect of different surface characteristics was also evaluated using two types of CNHs (untreated and oxidized). In the fibrous MWCNT, cell growth suppression, as well as expression of inflammatory cytokine genes was observed, as in previous reports. In contrast, no significant toxicity was observed for particulate CB and CNHs, which was different from the report of CB cytotoxicity in vascular endothelial cells. These results show that (1) lymph endothelial cells need to be tested separately from other endothelial cells for safety evaluation of nanomaterials, and (2) the potential of CNHs as DDSs.ArticleNANOMATERIALS. 10(7):1374 (2020)journal articl

Global properties of spacelike curves in Minkowski 3-space

We study global properties of closed spacelike curves in Minkowski 3-space

Epidemiologic and genomic investigations of an unusual increase in Salmonella enterica serovar Paratyphi A infection among travelers returning from Myanmar in 2015

Objectives: An unusual increase in Salmonella enterica serovar Paratyphi A infection rate in Japanese travelers returning from Myanmar was observed in 2015. Methods: We analyzed epidemiologic data of returned travelers with enteric fever from 2005-2019. We also analyzed 193 Salmonella Paratyphi A isolates, including 121 isolates with published genomes. Results: Annual notification trends showed a rapid increase in Salmonella Paratyphi A infection in travelers returning from Myanmar in 2015: 2-4 cases/100,000 travelers in 2012-2014 and 13 cases/100,000 travelers in 2015 (P <0.001). The genomic analyses revealed that 11 Myanmar-related isolates in 2015 formed a tight cluster in clade 3 with a single nucleotide variant (SNV) distance of 0-11 (primarily 0-7), yielding a wider SNV range than outbreak-associated isolates from Cambodia in 2013 (0-6 SNVs) or China in 2010 (0-5 SNVs). Although all Cambodia-related isolates in 2013 harbored the wild-type gyrA sequence, all Myanmar-related isolates in 2015 had a single, identical mutation (Ser83Phe) in the gyrA gene. Conclusion: The epidemiologic and molecular investigations suggested an increase in the infection rate with genetically closely related Salmonella Paratyphi A in travelers returning from Myanmar in 2015. Careful monitoring of the infection in Myanmar as an endemic country is warranted, considering the resumption of cross-border travel during the COVID-19 pandemic

Biocompatibility Evaluation of Carbon Nanohorns in Bone Tissues

With the advent of nanotechnology, the use of nanoparticles as drug delivery system (DDS) has attracted great interest. We aimed to apply carbon nanohorns (CNHs) as DDS in the development of new treatments for bone diseases. We evaluated the in vitro and in vivo cellular responses of CNHs in bone-related cells compared with carbon blacks (CBs), which are similar in particle size but differ in surface and structural morphologies. Although in vitro experiments revealed that both CNHs and CBs were incorporated into the lysosomes of RAW264-induced osteoclast-like cells (OCs) and MC3T3-E1 osteoblast-like cells (OBs), no severe cytotoxicity was observed. CNHs reduced the tartrate-resistant acid phosphatase activity and expression of the differentiation marker genes in OCs at noncytotoxic concentrations, whereas the alkaline phosphatase activity and differentiation of OBs increased. Under calcification of OBs, CNHs increased the number of calcified nodules and were intra- and extracellularly incorporated into calcified vesicles to form crystal nuclei. The in vivo experiments showed significant promotion of bone regeneration in the CNH group alone, with localized CNHs being found in the bone matrix and lacunae. The suppression of OCs and promotion of OBs suggested that CNHs may be effective against bone diseases and could be applied as DDS

Whole-Genome Analysis of Salmonella enterica Serovar Typhimurium T000240 Reveals the Acquisition of a Genomic Island Involved in Multidrug Resistance via IS1 Derivatives on the Chromosome ▿ †

Salmonella enterica serovar Typhimurium is frequently associated with life-threatening systemic infections, and the recent global emergence of multidrug resistance in S. enterica isolates from agricultural and clinical settings has raised concerns. In this study, we determined the whole-genome sequence of fluoroquinolone-resistant S. enterica serovar Typhimurium T000240 strain (DT12) isolated from human gastroenteritis in 2000. Comparative genome analysis revealed that T000240 displays high sequence similarity to strain LT2, which was originally isolated in 1940, indicating that progeny of LT2 might be reemerging. T000240 possesses a unique 82-kb genomic island, designated as GI-DT12, which is composed of multidrug resistance determinants, including a Tn2670-like composite transposon (class 1 integron [intI1, blaoxa-30, aadA1, qacEΔ1, and sul1], mercury resistance proteins, and chloramphenicol acetyltransferase), a Tn10-like tetracycline resistance protein (tetA), the aerobactin iron-acquisition siderophore system (lutA and lucABC), and an iron transporter (sitABCD). Since GI-DT12 is flanked by IS1 derivatives, IS1-mediated recombination likely played a role in the acquisition of this genomic island through horizontal gene transfer. The aminoglycoside-(3)-N-acetyltransferase (aac(3)) gene and a class 1 integron harboring the dfrA1 gene cassette responsible for gentamicin and trimethoprim resistance, respectively, were identified on plasmid pSTMDT12_L and appeared to have been acquired through homologous recombination with IS26. This study represents the first characterization of the unique genomic island GI-DT12 that appears to be associated with possible IS1-mediated recombination in S. enterica serovar Typhimurium. It is expected that future whole-genome studies will aid in the characterization of the horizontal gene transfer events for the emerging S. enterica serovar Typhimurium strains