RESUMO
Changes in the gut microbiome have pivotal roles in the pathogenesis of acute graft-versus-host disease (aGVHD) after allogenic haematopoietic cell transplantation (allo-HCT)1-6. However, effective methods for safely resolving gut dysbiosis have not yet been established. An expansion of the pathogen Enterococcus faecalis in the intestine, associated with dysbiosis, has been shown to be a risk factor for aGVHD7-10. Here we analyse the intestinal microbiome of patients with allo-HCT, and find that E. faecalis escapes elimination and proliferates in the intestine by forming biofilms, rather than by acquiring drug-resistance genes. We isolated cytolysin-positive highly pathogenic E. faecalis from faecal samples and identified an anti-E. faecalis enzyme derived from E. faecalis-specific bacteriophages by analysing bacterial whole-genome sequencing data. The antibacterial enzyme had lytic activity against the biofilm of E. faecalis in vitro and in vivo. Furthermore, in aGVHD-induced gnotobiotic mice that were colonized with E. faecalis or with patient faecal samples characterized by the domination of Enterococcus, levels of intestinal cytolysin-positive E. faecalis were decreased and survival was significantly increased in the group that was treated with the E. faecalis-specific enzyme, compared with controls. Thus, administration of a phage-derived antibacterial enzyme that is specific to biofilm-forming pathogenic E. faecalis-which is difficult to eliminate with existing antibiotics-might provide an approach to protect against aGVHD.
Assuntos
Bacteriófagos , Enterococcus faecalis , Microbioma Gastrointestinal , Doença Enxerto-Hospedeiro , Adulto , Idoso , Animais , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Adulto Jovem , Bacteriófagos/enzimologia , Bacteriófagos/genética , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Disbiose/complicações , Disbiose/microbiologia , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/genética , Enterococcus faecalis/crescimento & desenvolvimento , Enterococcus faecalis/metabolismo , Enterococcus faecalis/virologia , Fezes/microbiologia , Vida Livre de Germes , Doença Enxerto-Hospedeiro/complicações , Doença Enxerto-Hospedeiro/microbiologia , Doença Enxerto-Hospedeiro/prevenção & controle , Doença Enxerto-Hospedeiro/terapia , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Técnicas In Vitro , Intestinos/efeitos dos fármacos , Intestinos/microbiologia , Perforina/metabolismo , Fatores de Risco , Transplante Homólogo/efeitos adversos , Sequenciamento Completo do Genoma , Farmacorresistência Bacteriana/efeitos dos fármacos , Antibacterianos/farmacologiaRESUMO
OBJECTIVES: Impaired B-cell reconstitution after allogeneic hematopoietic cell transplantation (allo-HCT) contributes to the pathogenesis of chronic graft-versus-host disease (cGVHD). Therefore, methods to consistently achieve effective B cell lymphogenesis are required. We assessed the long-term effects of posttransplantation cyclophosphamide (PTCy) use on immune reconstitution in clinical settings, an emerging strategy to suppress allogeneic immunological inflammation early after allo-HCT and prevent subsequent GVHD. METHODS: We comprehensively analyzed peripheral immune cell subsets and measured serum immunoglobulin G (IgG) or cytokine levels in 39 patients who survived for >1 year after allo-HCT. RESULTS: The absolute counts of B1 and IgM memory B cells were significantly lower in patients with severe cGVHD than in those without. The absolute count and percentage (among total CD19+ B cells) of switched memory B cells and serum IgG levels were significantly higher in patients transplanted with PTCy than in those transplanted with conventional GVHD prophylaxis. Interestingly, increased percentages of switched memory B cells and serum IgG levels were observed only in patients transplanted with PTCy and not in those transplanted with umbilical cord blood. CONCLUSIONS: PTCy administration can mediate favorable memory B-cell reconstitution long after allo-HCT and may therefore suppress cGVHD.
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BACKGROUND: Within the genus Escherichia, several monophyletic clades other than the traditionally defined species have been identified. Of these, cryptic clade I (C-I) appears to represent a subspecies of E. coli, but due to the difficulty in distinguishing it from E. coli sensu stricto, the population structure and virulence potential of C-I are unclear. RESULTS: We defined a set of true C-I strains (n = 465), including a Shiga toxin 2a (Stx2a)-producing isolate from a patient with bloody diarrhoea identified by the retrospective analyses using a C-I-specific detection system. Through genomic analysis of 804 isolates from the cryptic clades, including these C-I strains, we revealed their global population structures and the marked accumulation of virulence genes and antimicrobial resistance genes in C-I. In particular, half of the C-I strains contained hallmark virulence genes of Stx-producing E. coli (STEC) and/or enterotoxigenic E. coli (ETEC). We also found the host-specific distributions of virulence genes, which suggests bovines as the potential source of human infections caused by STEC- and STEC/ETEC hybrid-type C-I strains, as is known in STEC. CONCLUSIONS: Our findings demonstrate the emergence of human intestinal pathogens in C-I lineage. To better understand the features of C-I strains and their infections, extensive surveillance and larger population studies of C-I strains are needed. The C-I-specific detection system developed in this study will be a powerful tool for screening and identifying C-I strains.
Assuntos
Escherichia coli Enterotoxigênica , Infecções por Escherichia coli , Proteínas de Escherichia coli , Escherichia coli Shiga Toxigênica , Humanos , Animais , Bovinos , Escherichia coli Shiga Toxigênica/genética , Escherichia , Estudos Retrospectivos , Virulência/genética , Proteínas de Escherichia coli/genéticaRESUMO
Heart rate variability analyses using Poincaré plots can be useful for evaluating the autonomic nervous system function. However, the interpretation of the quantitative indicators of Poincaré plots remains controversial. Thus, few studies have verified the effectiveness of the quantitative indicators in veterinary medicine. This study aimed to verify the reliability of Poincaré plot indicators using pharmacological models in dogs. Four healthy beagles were used in this study. Each dog was treated with propranolol, atropine, and propranolol-atropine to block the sympathetic, parasympathetic, and sympathetic-parasympathetic functions, respectively. The quantitative indicators of the Poincaré plots were calculated based on data from 300 electrocardiogram beats collected before and after the administration of each drug and statistically analysed. The quantitative indicators of the Poincaré plots, such as the standard deviation perpendicular to the major axis (SD1), standard deviation along the major axis (SD2), and SD1 × SD2, significantly decreased after the drug administration in both the parasympathetic and sympathetic-parasympathetic blockade models. However, no significant differences were observed in SD1/SD2 between the groups. The Poincaré plots reflected the changes in the autonomic nervous system of dogs. In dogs, SD1, SD2, and SD1 × SD2 can detect a state in which parasympathetic nerve activity is suppressed.
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Bacteriophages (or phages) play major roles in the evolution of bacterial pathogens via horizontal gene transfer. Multiple phages are often integrated in a host chromosome as prophages, not only carrying various novel virulence-related genetic determinants into host bacteria but also providing various possibilities for prophage-prophage interactions in bacterial cells. In particular, Escherichia coli strains such as Shiga toxin (Stx)-producing E. coli (STEC) and enteropathogenic E. coli (EPEC) strains have acquired more than 10 prophages (up to 21 prophages), many of which encode type III secretion system (T3SS) effector gene clusters. In these strains, some prophages are present at a single locus in tandem, which is usually interpreted as the integration of phages that use the same attachment (att) sequence. Here, we present phages integrating into T3SS effector gene cluster-associated loci in prophages, which are widely distributed in STEC and EPEC. Some of the phages integrated into prophages are Stx-encoding phages (Stx phages) and have induced the duplication of Stx phages in a single cell. The identified attB sequences in prophage genomes are apparently derived from host chromosomes. In addition, two or three different attB sequences are present in some prophages, which results in the generation of prophage clusters in various complex configurations. These phages integrating into prophages represent a medically and biologically important type of inter-phage interaction that promotes the accumulation of T3SS effector genes in STEC and EPEC, the duplication of Stx phages in STEC, and the conversion of EPEC to STEC and that may be distributed in other types of E. coli strains as well as other prophage-rich bacterial species.
Assuntos
Infecções por Escherichia coli/microbiologia , Transferência Genética Horizontal/genética , Prófagos/genética , Toxina Shiga II/farmacologia , Toxina Shiga/genética , Bacteriófagos/genética , Escherichia coli/metabolismo , Transferência Genética Horizontal/imunologia , Prófagos/patogenicidade , Toxina Shiga II/genética , Virulência/imunologia , Fatores de Virulência/genéticaRESUMO
We quantitatively discussed the effect of core-dependent loss (CDL) on the crosstalk (XT) of multicore fibers (MCFs). In practical ranges of XT and CDL, CDL has no significant effect on power coupling coefficients and XT between cores. Therefore, taking into account the CDL-induced signal attenuation difference among cores is sufficient when considering the signal-to-XT ratio in an MCF with CDL. We also analytically investigated the effect of CDL on XT measurements, and found that the effects of the CDLs induced in an MCF as a measurement target and a measurement setup (including input/output devices) can be canceled in the geometric mean of linear values (or the arithmetic mean of decibel values) of the XT by switching the source core and destination core of the XT.
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We propose a method for shape sensing that employs Rayleigh-signature domain multiplexing to simultaneously probe the fibers or cores of a shape sensing setup with a single optical frequency-domain reflectometry scan. The technique enables incrementing the measurement speed by a factor equal to the number of multiplexed fibers at the expense of an increased noise floor in accordance with the Cramér-Rao lower bound. Nonetheless, we verify that the shape reconstruction performance of the proposed method is in very good agreement with that of conventional sequential core interrogation.
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In floral thermogenesis, sugars play an important role not only as energy providers but also as growth and development facilitators. Yet, the mechanisms underlying sugar translocation and transport in thermogenic plants remain to be studied. Asian skunk cabbage (Symplocarpus renifolius) is a species that can produce durable and intense heat in its reproductive organ, the spadix. Significant morphological and developmental changes in the stamen are well-characterized in this plant. In this study, we focused on the sugar transporters (STPs), SrSTP1 and SrSTP14, whose genes were identified by RNA-seq as the upregulated STPs during thermogenesis. Real-time PCR confirmed that mRNA expression of both STP genes was increased from the pre-thermogenic to the thermogenic stage in the spadix, where it is predominantly expressed in the stamen. SrSTP1 and SrSTP14 complemented the growth defects of a hexose transporter-deficient yeast strain, EBY4000, on media containing 0.02, 0.2, and 2% (w/v) glucose and galactose. Using a recently developed transient expression system in skunk cabbage leaf protoplasts, we revealed that SrSTP1 and SrSTP14-GFP fusion proteins were mainly localized to the plasma membrane. To dig further into the functional analysis of SrSTPs, tissue-specific localization of SrSTPs was investigated by in situ hybridization. Using probes for SrSTP14, mRNA expression was observed in the microspores within the developing anther at the thermogenic female stage. These results indicate that SrSTP1 and SrSTP14 transport hexoses (e.g., glucose and galactose) at the plasma membrane and suggest that SrSTP14 may play a role in pollen development through the uptake of hexoses into pollen precursor cells.
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Araceae , Galactose/metabolismo , Pólen/genética , Pólen/metabolismo , Glucose/metabolismo , Termogênese , RNA Mensageiro/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
Many Rickettsia species of the spotted fever group (SFG) cause tick-borne diseases known as "spotted fever." One of the candidate SFG Rickettsia species is "Candidatus Rickettsia kotlanii," which was first detected in Haemaphysalis concinna in Hungary in 2006. However, its precise phylogenetic position in the SFG is not clear because only single-gene sequence-based phylogenetic analyses were performed using very limited genes. Here, we present the complete genome sequences of two Japanese "Ca. R. kotlanii" isolates, which differed only by a 135 bp insertion/deletion (InDel). Using these genomes and publicly available whole genome sequences of other Rickettsia species, the precise phylogenetic position of "Ca. R. kotlanii" in Rickettsia was determined to be in a clade of the SFG. The phylogenetic relationships and average nucleotide identity of "Ca. R. kotlanii" relative to the other species indicated that "Ca. R. kotlanii" is an independent taxon in the SFG. Notably, although the genomes of the two isolates were almost identical, the isolates were obtained from different tick species in different regions and years, suggesting extremely low genomic diversity in "Ca. R. kotlanii." While the genome of "Ca. R. kotlanii" is the smallest in the transitional group and SFG Rickettsia sequenced to date, we identified genes uniquely present or absent in "Ca. R. kotlanii," but most were apparently degraded. Therefore, analyses of differences at the sequence (single nucleotide polymorphisms and small InDels) or gene expression level will be required to understand the functional or physiological features unique to "Ca. R. kotlanii."
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Rickettsia , Rickettsiose do Grupo da Febre Maculosa , Animais , Genômica , Filogenia , Rickettsia/genética , Rickettsiose do Grupo da Febre Maculosa/genética , Rickettsiose do Grupo da Febre Maculosa/microbiologiaRESUMO
OBJECTIVE: Elizabethkingia anophelis causes meningitis, bloodstream infections, and respiratory infections in immunocompromised individuals. We examined two E. anophelis strains isolated from the first life-threatening cases caused by this species in Japan to determine the phylogenetic origin and genomic features of them. METHODS: We performed whole genome-based analysis to clarify the genetic relationship for the two strains (EK0004 and EK0079) and Elizabethkingia sp. strains isolated from worldwide and to characterize the genomic features such as the prevalence of virulence- and antimicrobial resistance (AMR)-related genes. PATIENTS: A 29-year-old man with hepatosplenic T-cell lymphoma and a 52-year-old man with systemic lupus erythematosus developed fatal bacteremia and meningitis due to E. anophelis, respectively. RESULTS: Two strains, EK0004 and EK0079, were genetically different but most closely related to the strains isolated from the largest outbreak in Wisconsin, USA from 2015 to 2016, and the strain isolated from cerebrospinal fluid of a patient in Florida, USA in 1982, respectively. The two strains contained AMR-related genes such as those encoding for an extended-spectrum ß-lactamase and multiple metallo-ß-lactamases and several virulence-related genes such as capsular polysaccharide synthesis gene clusters. CONCLUSIONS: Although further functional analyses are required to understand the virulence of these clones, these finding suggests that enough caution of E. anophelis infection in immunocompromised patients is required since the number of infections by this species is increasing outside Japan.
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Infecções por Flavobacteriaceae , Genoma Bacteriano , Masculino , Humanos , Adulto , Pessoa de Meia-Idade , Genoma Bacteriano/genética , Filogenia , Japão , Infecções por Flavobacteriaceae/epidemiologia , Infecções por Flavobacteriaceae/genética , GenômicaRESUMO
De novo metagenome assembly is effective in assembling multiple draft genomes, including those of uncultured organisms. However, heterogeneity in the metagenome hinders assembly and introduces interspecies misassembly deleterious for downstream analysis. For this purpose, we developed a hybrid metagenome assembler, MetaPlatanus. First, as a characteristic function, it assembles the basic contigs from accurate short reads and then iteratively utilizes long-range sequence links, species-specific sequence compositions, and coverage depth. The binning information was also used to improve contiguity. Benchmarking using mock datasets consisting of known bacteria with long reads or mate pairs revealed the high contiguity MetaPlatanus with a few interspecies misassemblies. For published human gut data with nanopore reads from potable sequencers, MetaPlatanus assembled many biologically important elements, such as coding genes, gene clusters, viral sequences, and over-half bacterial genomes. In the benchmark with published human saliva data with high-throughput nanopore reads, the superiority of MetaPlatanus was considerably more evident. We found that some high-abundance bacterial genomes were assembled only by MetaPlatanus as near-complete. Furthermore, MetaPlatanus can circumvent the limitations of highly fragmented assemblies and frequent interspecies misassembles obtained by the other tools. Overall, the study demonstrates that MetaPlatanus could be an effective approach for exploring large-scale structures in metagenomes.
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Metagenoma , Metagenômica/métodos , Software , Trato Gastrointestinal/microbiologia , Genoma Bacteriano , Humanos , Saliva/microbiologia , Especificidade da EspécieRESUMO
BACKGROUND & AIMS: Fecal microbiota transplantation (FMT) is an effective therapy for recurrent Clostridioides difficile infection (rCDI). However, the overall mechanisms underlying FMT success await comprehensive elucidation, and the safety of FMT has recently become a serious concern because of the occurrence of drug-resistant bacteremia transmitted by FMT. We investigated whether functional restoration of the bacteriomes and viromes by FMT could be an indicator of successful FMT. METHODS: The human intestinal bacteriomes and viromes from 9 patients with rCDI who had undergone successful FMT and their donors were analyzed. Prophage-based and CRISPR spacer-based host bacteria-phage associations in samples from recipients before and after FMT and in donor samples were examined. The gene functions of intestinal microorganisms affected by FMT were evaluated. RESULTS: Metagenomic sequencing of both the viromes and bacteriomes revealed that FMT does change the characteristics of intestinal bacteriomes and viromes in recipients after FMT compared with those before FMT. In particular, many Proteobacteria, the fecal abundance of which was high before FMT, were eliminated, and the proportion of Microviridae increased in recipients. Most temperate phages also behaved in parallel with the host bacteria that were altered by FMT. Furthermore, the identification of bacterial and viral gene functions before and after FMT revealed that some distinctive pathways, including fluorobenzoate degradation and secondary bile acid biosynthesis, were significantly represented. CONCLUSIONS: The coordinated action of phages and their host bacteria restored the recipients' intestinal flora. These findings show that the restoration of intestinal microflora functions reflects the success of FMT.
Assuntos
Enterocolite Pseudomembranosa/terapia , Transplante de Microbiota Fecal , Microbioma Gastrointestinal , Trato Gastrointestinal/microbiologia , Viroma , Adulto , Idoso , Bacteriófagos , Clostridioides difficile , Enterocolite Pseudomembranosa/microbiologia , Fezes/microbiologia , Feminino , Microbioma Gastrointestinal/genética , Trato Gastrointestinal/virologia , Humanos , Masculino , Metagenômica , Microviridae , Pessoa de Meia-Idade , Proteobactérias , Viroma/genéticaRESUMO
How pathogens evolve their virulence to humans in nature is a scientific issue of great medical and biological importance. Shiga toxin (Stx)-producing Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) are the major foodborne pathogens that can cause hemolytic uremic syndrome and infantile diarrhea, respectively. The locus of enterocyte effacement (LEE)-encoded type 3 secretion system (T3SS) is the major virulence determinant of EPEC and is also possessed by major STEC lineages. Cattle are thought to be the primary reservoir of STEC and EPEC. However, genome sequences of bovine commensal E. coli are limited, and the emerging process of STEC and EPEC is largely unknown. Here, we performed a large-scale genomic comparison of bovine commensal E. coli with human commensal and clinical strains, including EPEC and STEC, at a global level. The analyses identified two distinct lineages, in which bovine and human commensal strains are enriched, respectively, and revealed that STEC and EPEC strains have emerged in multiple sublineages of the bovine-associated lineage. In addition to the bovine-associated lineage-specific genes, including fimbriae, capsule, and nutrition utilization genes, specific virulence gene communities have been accumulated in stx- and LEE-positive strains, respectively, with notable overlaps of community members. Functional associations of these genes probably confer benefits to these E. coli strains in inhabiting and/or adapting to the bovine intestinal environment and drive their evolution to highly virulent human pathogens under the bovine-adapted genetic background. Our data highlight the importance of large-scale genome sequencing of animal strains in the studies of zoonotic pathogens.
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Infecções por Escherichia coli/microbiologia , Escherichia coli/classificação , Fatores de Virulência/genética , Sequenciamento Completo do Genoma/métodos , Animais , Bovinos , Escherichia coli Enteropatogênica/classificação , Escherichia coli Enteropatogênica/genética , Escherichia coli/genética , Escherichia coli/patogenicidade , Proteínas de Escherichia coli/genética , Evolução Molecular , Redes Reguladoras de Genes , Genoma Bacteriano , Humanos , Filogenia , Escherichia coli Shiga Toxigênica/classificação , Escherichia coli Shiga Toxigênica/genética , Escherichia coli Shiga Toxigênica/patogenicidade , SimbioseRESUMO
The molecular mechanisms that allow pathogenic bacteria to infect animals have been intensively studied. On the other hand, the molecular mechanisms by which bacteria acquire virulence functions are not fully understood. In the present study, we experimentally evaluated the evolution of a non-pathogenic strain of Escherichia coli in a silkworm infection model and obtained pathogenic mutant strains. As one cause of the high virulence properties of E. coli mutants, we identified amino acid substitutions in LptD (G580S) and LptE (T95I) constituting the lipopolysaccharide (LPS) transporter, which translocates LPS from the inner to the outer membrane and is essential for E. coli growth. The growth of the LptD and LptE mutants obtained in this study was indistinguishable from that of the parent strain. The LptD and LptE mutants exhibited increased secretion of outer membrane vesicles containing LPS and resistance against various antibiotics, antimicrobial peptides, and host complement. In vivo cross-linking studies revealed that the conformation of the LptD-LptE complex was altered in the LptD and LptE mutants. Furthermore, several clinical isolates of E. coli carried amino acid substitutions of LptD and LptE that conferred resistance against antimicrobial substances. This study demonstrated an experimental evolution of bacterial virulence properties in an animal infection model and identified functional alterations of the growth-essential LPS transporter that led to high bacterial virulence by conferring resistance against antimicrobial substances. These findings suggest that non-pathogenic bacteria can gain virulence traits by changing the functions of essential genes, and provide new insight to bacterial evolution in a host environment.
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Proteínas da Membrana Bacteriana Externa/genética , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Escherichia coli/patogenicidade , Animais , Proteínas da Membrana Bacteriana Externa/metabolismo , Transporte Biológico , Bombyx/microbiologia , Membrana Celular/metabolismo , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Lipopolissacarídeos/metabolismo , Modelos Moleculares , Ligação Proteica , Virulência/fisiologiaRESUMO
Lactose utilization is one of the general biochemical characteristics of Escherichia coli, and the lac operon is responsible for this phenotype, which can be detected on lactose-containing media, such as MacConkey agar, after 24 h of incubation. However, some Shiga toxin-producing E. coli (STEC) O121:H19 strains exhibit an unusual phenotype called delayed lactose utilization (DLU), in which lactose utilization can be detected after 48 h of cultivation but not after only 24 h of cultivation. Insertion of an insertion sequence (IS), IS600, into the lacZ gene appears to be responsible for the DLU phenotype, and exposure to lactose has been reported to be necessary to observe this phenotype, but the mechanism underlying these phenomena remains to be elucidated. Here, we performed detailed analyses of the lactose utilization abilities of a set of O121:H19 strains and their mutants and found that IS-excision enhancer (IEE)-mediated excision of IS600 reactivates the lacZ gene and that the selective proliferation of IS-cured subclones in lactose-supplemented culture medium is responsible for the expression of the DLU phenotype. In addition, we analyzed the patterns of IS insertion into the lacZ and iee genes in the global O121:H19 population and revealed that while there are O121:H19 strains or lineage/sublineages that contain the IS insertion into iee or intact lacZ and thus do not show the DLU phenotype, most currently circulating O121:H19 strains contain IS600-inserted lacZ and intact iee and thus exhibit this phenotype. IMPORTANCE Insertion sequences (ISs) can modulate gene expression by gene inactivation or activation. While phenotypic changes due to IS insertion/transposition are frequently observed, gene reactivation by precise or simple IS excision rarely occurs. In this study, we show that IS600 is excised from the lacZ gene by IS-excision enhancer (IEE) during the cultivation of Shiga toxin-producing Escherichia coli (STEC) O121:H19 strains that show an unusual phenotype called delayed lactose utilization (DLU). This excision rescued their lactose utilization defect, and the subsequent selective proliferation of IS-cured subclones in lactose-containing medium resulted in the expression of the DLU phenotype. As we also show that most currently circulating O121:H19 strains exhibit this phenotype, this study not only provides information helpful for the isolation and identification of O121:H19 STEC but also offers novel insights into the roles of IS and IEE in the generation of phenotypic variation in bacterial populations.
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Proteínas de Escherichia coli , Lactose , Escherichia coli Shiga Toxigênica , Elementos de DNA Transponíveis , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Óperon Lac , Lactose/metabolismo , Fenótipo , Toxina Shiga/genética , Escherichia coli Shiga Toxigênica/genéticaRESUMO
Use of bidirectional multi-core fiber (MCF) transmissions is attractive as it suppresses inter-core crosstalk by propagating the signals in opposite directions between nearest neighboring cores; therefore, signal quality and/or core density is improved compared with unidirectional transmissions where all the signals propagate in the same direction across the cores. In long-haul bidirectional MCF transmissions, Rayleigh backscattering is one of the major causes of inter-core crosstalk (XT). In this paper, we derive approximate expressions for Rayleigh backscattered XT and discuss the accuracy of the approximations. The derived expressions revealed that the reduction from conventional co-propagating XT to backscattered XT depends approximately only on wavelength, refractive index, effective area, the Rayleigh scattering component in propagation loss, and span loss.
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Acetaminophen (APAP)-induced liver injury (AILI) is the most common cause of acute liver failure. Although the mechanisms that trigger AILI are well known, it is less understood how to halt AILI progression and facilitate liver recovery. Therefore, it is necessary to understand the pathophysiology of APAP hepatotoxicity in patients and to examine predictive/preventive markers. In a clinical study, we had a case in which aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels increased in a patient with a low ratio of APAP glucuronide concentration (AP-G)/APAP plasma concentration. Then a reverse translational study was conducted for clarifying this clinical question. The relationship between plasma AP-G/APAP concentration ratio and the levels of AST and ALT was examined by in vivo and in vitro experiments. In in vivo experiments, 10-week-old rats showed lower UGT activity, lower AP-G/APAP concentration ratios, and higher AST and ALT levels than 5-week-old rats. This suggests an inverse correlation between the AP-G/APAP concentration ratio and the AST, ALT levels in APAP-treated rats. Furthermore, as a result of the in vitro experiment, it was confirmed that the cell viability decreased when the AP-G/APAP concentration ratio in the culture medium decreased. Since the decrease in the plasma AP-G/APAP concentration ratio appears earlier than the increase of AST and ALT levels, the ratio might be a presymptomatic marker of AILI. When APAP is used for a long time, it is recommended to perform therapeutic drug monitoring of the AP-G/APAP concentration ratio, which is a predictive/preventive marker of AILI.
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Doença Hepática Crônica Induzida por Substâncias e Drogas , Doença Hepática Induzida por Substâncias e Drogas , Acetaminofen/efeitos adversos , Acetaminofen/análogos & derivados , Acetaminofen/farmacocinética , Acetaminofen/toxicidade , Alanina Transaminase , Animais , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Humanos , Fígado , RatosRESUMO
Plastids are involved in phytohormone metabolism as well as photosynthesis. However, the mechanism by which plastid retrograde signals and phytohormones cooperatively regulate plastid biogenesis remains elusive. Here, we investigated the effects of an inhibitor and a mutation that generate biogenic plastid signals on phytohormones and vice versa. Inhibition of plastid biogenesis by norflurazon (NF) treatment and the plastid protein import2 (ppi2) mutation caused a decrease in salicylic acid (SA) and jasmonic acid (JA). This effect can be attributed in part to the altered expression of genes involved in the biosynthesis and the metabolism of SA and JA. However, SA-dependent induction of the PATHOGENESIS-RELATED1 gene was virtually unaffected in NF-treated plants and the ppi2 mutant. Instead, the level of chlorophyll in these plants was partially restored by the exogenous application of SA. Consistent with this observation, the levels of some photosynthesis-associated proteins increased in the ppi2 and NF-treated plants in response to SA treatment. This regulation in true leaves seems to occur at the posttranscriptional level since SA treatment did not induce the expression of photosynthesis-associated genes. In salicylic acid induction deficient 2 and lesions simulating disease resistance 1 mutants, endogenous SA regulates the accumulation of photosynthesis-associated proteins through transcriptional and posttranscriptional mechanisms. These data indicate that SA acts antagonistically to the inhibition of plastid biogenesis by promoting the accumulation of photosynthesis-associated proteins in Arabidopsis, suggesting a possible link between SA and biogenic plastid signaling.
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Proteínas de Arabidopsis/genética , Arabidopsis/genética , Ciclopentanos/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/genética , Oxilipinas/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Ácido Salicílico/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Herbicidas/efeitos adversos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Fotossíntese , Plastídeos/metabolismo , Piridazinas/efeitos adversos , Transdução de SinaisRESUMO
BACKGROUND: A patient repeatedly developed bacteraemia despite the continuous use of antibiotics. We obtained two Klebsiella pneumoniae isolates from the patient's blood on Days 72 and 105 after hospitalization. Each of the two isolates belonged to ST45, but while the first isolate was susceptible to most antibiotics, the second one was resistant to multiple drugs including carbapenems. OBJECTIVES: To identify the genetic differences between the two isolates and uncover alterations formed by the within-host bacterial evolution leading to the antimicrobial resistance. METHODS: Whole-genome comparison of the two isolates was carried out to identify their genetic differences. We then profiled their outer membrane proteins related to membrane permeability to drugs. To characterize a ramR gene mutation found in the MDR isolate, its WT and mutant genes were cloned and expressed in the MDR isolate. RESULTS: The two isolates showed only three genomic differences, located in mdoH, ramR and upstream of ompK36. In the MDR isolate, a single nucleotide substitution in the ompK36 upstream region attenuated OmpK36 expression. A single amino acid residue insertion in RamR in the MDR isolate impaired its function, leading to the down-regulation of OmpK35 and the subsequent up-regulation of the AcrAB-TolC transporter, which may contribute to the MDR. CONCLUSIONS: We identified very limited genomic changes in the second K. pneumoniae clone during within-host evolution, but two of the three identified mutations conferred the MDR phenotype on the clone by modulating drug permeability.
Assuntos
Infecções por Klebsiella , Klebsiella pneumoniae , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Células Clonais/metabolismo , Resistência a Múltiplos Medicamentos , Farmacorresistência Bacteriana Múltipla/genética , Humanos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/metabolismo , Proteínas de Membrana Transportadoras , Testes de Sensibilidade Microbiana , Mutação , beta-Lactamases/genéticaRESUMO
We present a novel single-MCF connector without any additional or high-precision parts not found on a standard single-SMF connector. The proposed connector realizes rotational fiber alignment and ferrule floating simultaneously by employing a standard MU ferrule with a straight flange edge and a modified LC housing with a tapered hole that can make contact with the ferrule flange. Fabricated connectors achieved an average loss of 0.07â dB in a random connection test and passed the Telcordia GR-326-CORE mechanical and environmental reliability test. Furthermore, we conducted numerical simulations and confirmed these positive results were due to suppression of ferrule rotation from external forces.