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1.
Pediatr Blood Cancer ; 71(9): e31182, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38961598

RESUMO

BACKGROUND: Spinal cord compression is a rare presentation of non-Hodgkin lymphoma (NHL) in children. We aimed to describe the prevalence, histological subtypes, clinical presentation, therapy, and outcome of those children in a population-based cohort. The chemotherapy regimen remained comparable over time. METHODS: We retrospectively identified all children and adolescents with paresis as initial manifestations of the NHL between January 1990 and December 2020 from the NHL-BFM database. Characteristics, therapy, and outcome data were gathered from the database and patient files. RESULTS: Fifty-seven of 4779 children (1.2%) presented with initial paresis due to spinal cord compression. The median age was 10.3 years (range, 3.1-18.0 years), and 33% were female. Initial symptoms were paresis/weakness (n = 50, 88%), back pain (n = 33, 58%), paresthesia (n = 23, 40%), and bladder dysfunction and/or constipation (n = 22, 39%), persisting for a median of 14 days before diagnosis. Subtype distribution was mature B-NHL (n = 41, 72%), precursor B-lymphoblastic lymphoma (LBL) (n = 12, 21%), anaplastic large cell lymphoma (ALCL) (n = 3, 5%), and T-LBL (n = 1, 2%). Initial emergency therapy included surgery (70%) and/or chemotherapy/steroids (63%). Five-year event-free survival and overall survival (80% ± 5% and 82% ± 5%, respectively) were comparable with all other NHL patients. Neurological symptoms persisted in approximately one-third of surviving patients at the last follow-up. CONCLUSION: 1.2% of pediatric NHL patients presented with paresis from spinal cord compression mainly due to B-cell lymphomas. Neurological sequelae were observed in one-third of surviving patients.


Assuntos
Linfoma não Hodgkin , Compressão da Medula Espinal , Humanos , Feminino , Masculino , Criança , Adolescente , Estudos Retrospectivos , Pré-Escolar , Compressão da Medula Espinal/etiologia , Linfoma não Hodgkin/complicações , Linfoma não Hodgkin/patologia , Linfoma não Hodgkin/epidemiologia , Taxa de Sobrevida , Prognóstico , Seguimentos
2.
Nucleic Acids Res ; 50(6): 3001-3017, 2022 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-34522950

RESUMO

The DNAs of bacterial viruses are known to contain diverse, chemically complex modifications to thymidine that protect them from the endonuclease-based defenses of their cellular hosts, but whose biosynthetic origins are enigmatic. Up to half of thymidines in the Pseudomonas phage M6, the Salmonella phage ViI, and others, contain exotic chemical moieties synthesized through the post-replicative modification of 5-hydroxymethyluridine (5-hmdU). We have determined that these thymidine hypermodifications are derived from free amino acids enzymatically installed on 5-hmdU. These appended amino acids are further sculpted by various enzyme classes such as radical SAM isomerases, PLP-dependent decarboxylases, flavin-dependent lyases and acetyltransferases. The combinatorial permutations of thymidine hypermodification genes found in viral metagenomes from geographically widespread sources suggests an untapped reservoir of chemical diversity in DNA hypermodifications.


Assuntos
Bacteriófagos , Liases , Aminoácidos/metabolismo , Bacteriófagos/genética , DNA/metabolismo , Timidina/metabolismo
3.
Acta Paediatr ; 112(7): 1413-1421, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-36947098

RESUMO

AIM: To determine the relationship between medical staff's response time (RT) to oxygen saturation (SpO2 ) below 80% and the associated time from tactile intervention until SpO2 normalisation (CT). METHODS: Time-lapse video and continuous SpO2 were recorded for six consecutive 24 h periods. Regression analyses of RT and SpO2 in association with postmenstrual age (PMA), weight, infant sex and frequency of intermittent hypoxemia (IH). RESULTS: Five hundred and twelve hypoxemia episodes received tactile intervention in 20 extremely preterm infants (gestational age ≤28 weeks, birthweight <1500 g). Median RT was 20.5 s (IQR 16.63-25.50). RT increased with increased IH frequency (p = 0.023) independently of PMA and weight. SpO2 decreased by 3.7% with every 10 s RT (p = 0.039). Time until SpO2 normalisation was strongly associated with RT (ß = 0.58, p = 0.042). The association was amplified by lower PMA (p = 0.043). Female preterm infants experienced longer RT than males (p = 0.027). Because the total length of an IH is the sum of RT and CT, preterm infants with low PMA can reach a critical hypoxemia duration of >60 s, even with short RT. CONCLUSION: The RT is a critical factor that affects the overall time of IH treatments and the depth of desaturation. The consequences of a prolonged RT are worse for more immature preterm infants.


Assuntos
Lactente Extremamente Prematuro , Oxigênio , Lactente , Masculino , Recém-Nascido , Humanos , Feminino , Tempo de Reação , Oximetria , Hipóxia/complicações , Idade Gestacional , Recém-Nascido de muito Baixo Peso
4.
Blood ; 135(14): 1124-1132, 2020 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-31961927

RESUMO

Children with refractory or relapsed Burkitt lymphoma (BL) or Burkitt leukemia (B-AL) have a poor chance to survive. We describe characteristics, outcome, reinduction, and transplantation approaches and evaluate risk factors among children with progression of a BL/B-AL included in Non-Hodgkin's Lymphoma-Berlin-Frankfurt-Münster studies between 1986 and 2016. Treatment recommendation was reinduction including rituximab from the early 2000s followed by blood stem cell transplantation. The 3-year survival of the 157 children was 18.5 ± 3%. Survival significantly improved from 11 ± 3% before to 27 ± 5% after 2000 (P < .001), allowing for risk factor analyses among the latter 75 patients. Survival of 14 patients with relapse after initial therapy for low-risk disease (R1/R2) was 50 ± 13% compared with 21 ± 5% for 61 patients progressing after R3/R4 therapy (P < .02). A total of 25 of 28 patients with progression during first-line therapy, 31 of 32 with progression during reinduction, 15 of 16 not reaching a complete remission (CR) before transplantation, 9 of 10 treated with rituximab front-line, and all 13 patients not receiving rituximab during reinduction died. Forty-six patients received stem cell transplantation (20 autologous, 26 allogeneic). Survival after a regimen combining rituximab with continuous-infusion chemotherapy followed by allogeneic transplantation was 67 ± 12% compared with 18 ± 5% for all other regimen and transplantations (P = .003). Patients with relapsed BL/B-AL have a poor chance to survive after current effective front-line therapies. Progression during initial or reinduction chemotherapy and initial high-risk disease are risk factors in relapse. Time-condensed continuous-infusion reinduction followed by stem cell transplantation forms the basis for testing new drugs.


Assuntos
Antineoplásicos Imunológicos/uso terapêutico , Linfoma de Burkitt/terapia , Transplante de Células-Tronco Hematopoéticas , Recidiva Local de Neoplasia/terapia , Rituximab/uso terapêutico , Adolescente , Linfoma de Burkitt/epidemiologia , Criança , Progressão da Doença , Feminino , Humanos , Masculino , Recidiva Local de Neoplasia/epidemiologia , Análise de Sobrevida , Transplante Homólogo , Resultado do Tratamento
5.
Proc Natl Acad Sci U S A ; 116(5): 1585-1590, 2019 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-30651310

RESUMO

A common design principle of heteromeric signaling proteins is the use of shared subunits. This allows encoding of complex messages while maintaining evolutionary flexibility. How cells regulate and control assembly of such composite signaling proteins remains an important open question. An example of particular complexity and biological relevance is the interleukin 12 (IL-12) family. Four functionally distinct αß heterodimers are assembled from only five subunits to regulate immune cell function and development. In addition, some subunits act as independent signaling molecules. Here we unveil key molecular mechanisms governing IL-27 biogenesis, an IL-12 family member that limits infections and autoimmunity. In mice, the IL-27α subunit is secreted as a cytokine, whereas in humans only heterodimeric IL-27 is present. Surprisingly, we find that differences in a single amino acid determine if IL-27α can be secreted autonomously, acting as a signaling molecule, or if it depends on heterodimerization for secretion. By combining computer simulations with biochemical experiments, we dissect the underlying structural determinants: a protein folding switch coupled to disulfide bond formation regulates chaperone-mediated retention versus secretion. Using these insights, we rationally change folding and assembly control for this protein. This provides the basis for a more human-like IL-27 system in mice and establishes a secretion-competent human IL-27α that signals on its own and can regulate immune cell function. Taken together, our data reveal a close link between protein folding and immunoregulation. Insights into the underlying mechanisms can be used to engineer immune modulators.


Assuntos
Citocinas/metabolismo , Interleucinas/metabolismo , Subunidades Proteicas/metabolismo , Animais , Autoimunidade/imunologia , Linhagem Celular , Células HEK293 , Humanos , Camundongos , Dobramento de Proteína , Transdução de Sinais/fisiologia
6.
Genomics ; 113(4): 1802-1815, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33862184

RESUMO

Despite decades of research and advancements in diagnostics and treatment, tuberculosis remains a major public health concern. New computational methods are needed to interrogate the intersection of host- and bacterial genomes. Paired host genotype datum and infecting bacterial isolate information were analysed for associations using a multinomial logistic regression framework implemented in SNPTest. A cohort of 853 admixed South African participants and a Ghanaian cohort of 1359 participants were included. Two directly genotyped variants, namely rs529920 and rs41472447, were identified in the Ghanaian cohort as being statistically significantly associated with risk for infection with strains of different members of the MTBC. Thus, a multinomial logistic regression using paired host-pathogen data may prove valuable for investigating the complex relationships driving infectious disease.


Assuntos
Mycobacterium tuberculosis , Tuberculose , Estudo de Associação Genômica Ampla , Genótipo , Gana/epidemiologia , Humanos , Fenótipo , África do Sul , Tuberculose/genética , Tuberculose/microbiologia
7.
Proc Natl Acad Sci U S A ; 115(14): E3116-E3125, 2018 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-29555775

RESUMO

Certain viruses of bacteria (bacteriophages) enzymatically hypermodify their DNA to protect their genetic material from host restriction endonuclease-mediated cleavage. Historically, it has been known that virion DNAs from the Delftia phage ΦW-14 and the Bacillus phage SP10 contain the hypermodified pyrimidines α-putrescinylthymidine and α-glutamylthymidine, respectively. These bases derive from the modification of 5-hydroxymethyl-2'-deoxyuridine (5-hmdU) in newly replicated phage DNA via a pyrophosphorylated intermediate. Like ΦW-14 and SP10, the Pseudomonas phage M6 and the Salmonella phage ViI encode kinase homologs predicted to phosphorylate 5-hmdU DNA but have uncharacterized nucleotide content [Iyer et al. (2013) Nucleic Acids Res 41:7635-7655]. We report here the discovery and characterization of two bases, 5-(2-aminoethoxy)methyluridine (5-NeOmdU) and 5-(2-aminoethyl)uridine (5-NedU), in the virion DNA of ViI and M6 phages, respectively. Furthermore, we show that recombinant expression of five gene products encoded by phage ViI is sufficient to reconstitute the formation of 5-NeOmdU in vitro. These findings point to an unexplored diversity of DNA modifications and the underlying biochemistry of their formation.


Assuntos
Bactérias/metabolismo , Infecções Bacterianas/microbiologia , Proteínas de Bactérias/metabolismo , Bacteriófagos/genética , DNA Viral/biossíntese , Timidina/química , Uridina/química , Bacteriófagos/crescimento & desenvolvimento , Bacteriófagos/metabolismo , Genoma Viral
8.
Mod Pathol ; 33(2): 303-311, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31537897

RESUMO

V-domain Ig-containing suppressor of T-cell activation (VISTA) is an immune checkpoint gene that inhibits anti-tumor immune responses. Since most malignant pleural mesotheliomas do not respond to anti-programmed cell death(-ligand)1 (PD-(L)1)/cytotoxic T-lymphocyte-associated protein 4 (CTLA4) therapy and given the recent finding of The Cancer Genome Atlas Study that pleural mesothelioma displays the highest expression of VISTA among all cancers studied, we examined VISTA expression in a large pleural mesothelioma cohort. VISTA and PD-L1 immunohistochemistry were performed on tissue microarray of immunotherapy-naive pleural mesotheliomas (254 epithelioid, 24 biphasic and 41 sarcomatoid) and ten whole-tissue sections of benign pleura (VISTA only). Percentages of tumor and inflammatory cells with positive staining were assessed. Optimal prognostic cutoff percentages were determined using maximally selected rank statistics. Overall survival was evaluated using Kaplan-Meier methods and Cox proportional hazard analysis. All benign mesothelium expressed VISTA. Eighty-five percent of 319 and 38% of 304 mesotheliomas expressed VISTA and PD-L1 (88% and 33% of epithelioid, 90% and 43% of biphasic, and 42% and 75% of sarcomatoid), respectively. Median VISTA score was significantly higher in epithelioid (50%) (vs. biphasic [20%] and sarcomatoid [0]) (p < 0.001), while median PD-L1 score was significantly higher in sarcomatoid tumors (20%) (vs. biphasic and epithelioid [both 0%]) (p < 0.001). VISTA and PD-L1 were expressed in inflammatory cells in 94% (n = 317) and 24% (n = 303) of mesothelioma, respectively. Optimal prognostic cutoffs for VISTA and PD-L1 were 40% and 30%, respectively. On multivariable analysis, VISTA and PD-L1 expression in mesothelioma were associated with better and worse overall survival (p = 0.001 and p = 0.002), respectively, independent of histology. In a large cohort of mesothelioma, we report frequent expression of VISTA and infrequent expression of PD-L1 with favorable and unfavorable survival correlations, respectively. These findings may explain poor responses to anti-PD-(L)1 immunotherapy and suggest VISTA as a potential novel target in pleural mesothelioma.


Assuntos
Antígenos B7/análise , Biomarcadores Tumorais/análise , Células Epitelioides/imunologia , Mesotelioma Maligno/imunologia , Neoplasias Pleurais/imunologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígeno B7-H1/análise , Células Epitelioides/patologia , Feminino , Humanos , Inibidores de Checkpoint Imunológico/uso terapêutico , Imuno-Histoquímica , Masculino , Mesotelioma Maligno/tratamento farmacológico , Mesotelioma Maligno/mortalidade , Mesotelioma Maligno/patologia , Pessoa de Meia-Idade , Neoplasias Pleurais/tratamento farmacológico , Neoplasias Pleurais/mortalidade , Neoplasias Pleurais/patologia , Prognóstico , Análise Serial de Tecidos
9.
Mod Pathol ; 29(10): 1262-77, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27363490

RESUMO

Smooth muscle tumors of the uterus are a diagnostically challenging group of tumors. Molecular surrogate markers reliably distinguishing between benign and malignant tumors are not available. Therefore, the diagnosis is based on morphologic criteria. The aim was to investigate a well-characterized group of challenging uterine smooth muscle tumors consisting of 20 leiomyomas, 13 leiomyomas with bizarre nuclei, and 14 leiomyosarcomas for copy number alterations, MED12 mutations and FH deletions to search for potential diagnostically useful surrogate markers. MED12 mutations were detected in 47, 15, and 25% of leiomyomas, leiomyomas with bizarre nuclei and leiomyosarcomas, respectively. MED12 mutations in leiomyomas with bizarre nuclei were detected outside the hotspot region. FH-deletions were seen in 27, 30.8, and 25% of leiomyomas, leiomyomas with bizarre nuclei and leiomyosarcomas, respectively. By using copy number alteration profiling a clear separation of leiomyomas, leiomyomas with bizarre nuclei and leiomyosarcomas could not be observed. Copy number alterations revealed clear genetic similarities between leiomyomas with bizarre nuclei and leiomyosarcomas. Leiomyosarcomas showed a similar pattern of gains and losses as leiomyomas with bizarre nuclei, with additional copy number alterations and more homozygous losses and high-level amplifications compared to leiomyomas with bizarre nuclei. In conclusion, this study demonstrates that known FH-deletions, a recurrent molecular change in leiomyomas, occur in morphologically challenging variants of leiomyomas, leiomyomas with bizarre nuclei and leiomyosarcomas. Although MED12 mutations are common in leiomyomas, they infrequently occur in leiomyomas with bizarre nuclei and leiomyosarcomas. The genetic similarities between leiomyomas with bizarre nuclei and leiomyosarcomas raise the intriguing possibility that uterine leiomyomas with bizarre nuclei and leiomyosarcomas are closely related and challenge the traditional concept that leiomyoma with bizarre nuclei is a tumor with just marked 'degenerative' cellular changes. These findings support the hypothesis that tumor progression within uterine smooth muscle tumors might occur.


Assuntos
Leiomioma/genética , Leiomiossarcoma/genética , Neoplasias Uterinas/genética , Adulto , Idoso , Núcleo Celular/patologia , Aberrações Cromossômicas , Feminino , Humanos , Leiomioma/patologia , Leiomiossarcoma/patologia , Pessoa de Meia-Idade , Neoplasias Uterinas/patologia
10.
PLoS Pathog ; 10(4): e1004043, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24763594

RESUMO

Competence for transformation is widespread among bacterial species. In the case of Gram-negative systems, a key step to transformation is the import of DNA across the outer membrane. Although multiple factors are known to affect DNA transport, little is known about the dynamics of DNA import. Here, we characterized the spatio-temporal dynamics of DNA import into the periplasm of Neisseria gonorrhoeae. DNA was imported into the periplasm at random locations around the cell contour. Subsequently, it was recruited at the septum of diplococci at a time scale that increased with DNA length. We found using fluorescent DNA that the periplasm was saturable within minutes with ∼40 kbp DNA. The DNA-binding protein ComE quantitatively governed the carrying capacity of the periplasm in a gene-dosage-dependent fashion. As seen using a fluorescent-tagged derivative protein, ComE was homogeneously distributed in the periplasm in the absence of external DNA. Upon addition of external DNA, ComE was relocalized to form discrete foci colocalized with imported DNA. We conclude that the periplasm can act as a considerable reservoir for imported DNA with ComE governing the amount of DNA stored potentially for transport through the inner membrane.


Assuntos
Proteínas de Bactérias/metabolismo , DNA Bacteriano/metabolismo , Proteínas de Ligação a DNA/metabolismo , Neisseria gonorrhoeae/metabolismo , Periplasma/metabolismo , Transformação Bacteriana/fisiologia , Proteínas de Bactérias/genética , Transporte Biológico Ativo/fisiologia , DNA Bacteriano/genética , Proteínas de Ligação a DNA/genética , Neisseria gonorrhoeae/genética , Periplasma/genética
11.
Curr Opin Insect Sci ; 61: 101135, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37926187

RESUMO

Insect symbionts can alter their host phenotype and their effects can range from beneficial to pathogenic. Moreover, many insects exhibit co-infections, making their study more challenging. Less than 1% of insect species have high-quality referenced genomes available and fewer still also have their symbionts sequenced. Two methods are commonly used to sequence symbionts: whole-genome sequencing to concomitantly capture the host and bacterial genomes, or isolation of the symbiont's genome before sequencing. These methods are limited when dealing with rare or poorly characterized symbionts. Long-read technology is an important tool to generate high-quality genomes as they can overcome high levels of heterozygosity, repeat content, and transposable elements that confound short-read methods. Oxford Nanopore (ONT) adaptive sampling allows a sequencing instrument to select or reject sequences in real time. We describe a method based on ONT adaptive sampling (subtractive) approach that readily permitted the sequencing of the complete genomes of mitochondria, Buchnera and its plasmids (pLeu, pTrp), and Wolbachia genomes in two aphid species, Aphis glycines and Pentalonia nigronervosa. Adaptive sampling is able to retrieve organelles such as mitochondria and symbionts that have high representation in their hosts such as Buchnera and Wolbachia, but is less successful at retrieving symbionts in low concentrations.


Assuntos
Buchnera , Nanoporos , Animais , Buchnera/genética , Elementos de DNA Transponíveis , Insetos/genética
12.
Arch Pediatr ; 2024 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-39472216

RESUMO

BACKGROUND: Teledermatology has been widely deployed over the past decade in France, becoming an indispensable tool in daily practice. Pediatric dermatology is a subspecialty of dermatology limited to a small number of specialists. In 2013, the Argenteuil Hospital developed a structured store-and-forward (SAF) service that is particularly well-suited for the field of pediatric dermatology. We report on our 10-year experience using the SAF approach in pediatric dermatology, focusing on the acceptability and efficiency of the service. METHOD: All pediatric (<18 years) cases submitted to the SAF service from 2013 to 2022 were analyzed to evaluate SAF performance (refusals, response times, and information quality); patient demographics; pathologies (diagnostic certainty, types); and management. RESULTS: A total of 922 cases, from eight centers (six hospitals, two penitentiaries, and one health center) and 52 physicians, were analyzed. An increase in requests was noted over the years. No families refused to use the service. In 83 % and 94 % of cases, the quality of the photos and information was considered good or very good, respectively. The median response time was 1.5 h. The mean age of the children was 5 years (sex ratio: 1:1), with 26 % of cases involving newborns (<1 month). The median disease duration was 6 days (48 % <5 days). In 65 % of cases, the diagnosis was "certain," whereas in 34 % of cases a "diagnostic hypothesis" was made. Examinations were recommended in 35 % of cases and treatment was proposed in 62 % of cases. Dermatological follow-up was proposed in 32 % of cases. CONCLUSION: Our 10-year review of the SAF network showed that this pediatric teledermatology service has been accepted by parents and physicians. The information transmitted was of high quality, although additional clarification requests were sometimes required. The service enabled rapid responses in the majority of cases, including a wide variety of situations: one-quarter of cases involved newborns and 48 % of cases involved recently developed dermatoses (<5 days) requiring urgent management. This pediatric dermatology SAF-based tele-expertise service was therefore shown to be efficient and very well accepted, and is currently being deployed among private practitioners.

14.
BMC Med Genet ; 14: 129, 2013 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-24373500

RESUMO

BACKGROUND: Germline genetic testing for familial cancer syndromes is usually performed serially for the most likely genetic causes. In recent years the way genetic testing carried out has changed, as next generation sequencing now allows the simultaneous testing of multiple susceptibility genes at low costs. CASE PRESENTATION: Here, we present a female with bilateral breast cancer and endometrial adenocarcinoma. After simultaneous sequencing of 150 genes (890 kb) associated with hereditary cancer we identified pathogenic mutations in two high-penetrance genes, i.e. TP53 and CDH1 that would most likely not have been elucidated by serial screening of candidate genes. CONCLUSION: As the two mutated genes are located on different chromosomes and cause different cancer syndromes these findings had a tremendous impact not only on genetic counseling of the index patient and her family but also on subsequent surveillance strategies.


Assuntos
Adenocarcinoma/genética , Neoplasias da Mama/genética , Caderinas/genética , Neoplasias do Endométrio/genética , Mutação , Proteína Supressora de Tumor p53/genética , Antígenos CD , Caderinas/metabolismo , Feminino , Testes Genéticos/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , Proteína Supressora de Tumor p53/metabolismo
15.
Neurocase ; 19(4): 348-50, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22512289

RESUMO

'Crossed language dominance' is a rare form of language lateralization, characterized by a dissociation of anterior and posterior language regions. We present the case of a healthy subject whose language lateralization pattern, as assessed by functional magnetic resonance imaging, is reliably characterized as crossed language dominance based on a word generation task, but typical left-lateralized when a semantic decision task is applied. A single language task is therefore not sufficient to characterize language lateralization, at least not for subjects with rare forms of language dominance. In the pre-surgical diagnostic of language lateralization, several language tasks tapping into different aspects of language functions should be applied.


Assuntos
Córtex Cerebral/fisiologia , Lateralidade Funcional/fisiologia , Idioma , Adulto , Córtex Cerebral/irrigação sanguínea , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Oxigênio/sangue
16.
Proc Natl Acad Sci U S A ; 107(3): 1184-9, 2010 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-20080542

RESUMO

The Gram-negative gastric pathogen Helicobacter pylori depends on natural transformation for genomic plasticity, which leads to host adaptation and spread of resistances. Here, we show that H. pylori takes up covalently labeled fluorescent DNA preferentially at the cell poles and that uptake is dependent on the type IV secretion system ComB. By titration of external pH and detection of accessibility of the fluorophor by protons, we localized imported fluorescent DNA in the periplasm. Single molecule analysis revealed that outer membrane DNA transport occurred at a velocity of 1.3 kbp x s(-1) and that previously imported DNA was reversibly extracted from the bacterium at pulling forces exceeding 23 pN. Thus, transport velocities were 10-fold higher than in Bacillus subtilis, and stalling forces were substantially lower. dsDNA stained with the intercalator YOYO-1 was transiently detected in the periplasm in wild-type H. pylori but was periplasmatically trapped in a mutant lacking the B. subtilis membrane-channel homolog ComEC. We conclude that H. pylori uses a two-step DNA uptake mechanism in which ComB transports dsDNA across the outer membrane at low force and poor specificity for DNA structure. Subsequently, Hp-ComEC mediates transport into the cytoplasm, leading to the release of the noncovalently bound DNA dye. Our findings fill the gap to propose a model for composite DNA uptake machineries in competent bacteria, all comprising the conserved ComEC channel for cytoplasmic membrane transport in combination with various transporters for access of external DNA to the cytoplasmic membrane.


Assuntos
DNA/metabolismo , Helicobacter pylori/metabolismo , Transporte Biológico , Corantes Fluorescentes , Helicobacter pylori/genética , Mutação
17.
Antibiotics (Basel) ; 12(3)2023 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-36978296

RESUMO

Antimicrobials are widely used to cure intramammary infections (IMI) in dairy cows during the dry period (DP). Nevertheless, the IMI cure is influenced by many factors and not all quarters benefit from antimicrobial dry cow treatment (DCT). To evaluate the true effect of antibiotic DCT compared to self-cure and the role of causative pathogens on the IMI cure, a retrospective cross-sectional study was performed. The analysis included 2987 quarters infected at dry-off (DO). Information on DCT, causative pathogens, somatic cell count, milk yield, amount of lactation, Body Condition Score, and season and year of DO were combined into categorical variables. A generalized linear mixed model with a random cow, farm and year effect and the binary outcome of bacteriological cure of IMI during the DP was conducted. In the final model, a significant effect (p < 0.05) on DP cure was seen for the DO season and the category of causative pathogens (categories being: Staphylococcus aureus, non-aureus staphylococci, streptococci, coliforms, 'other Gram-negative bacteria', 'other Gram positive bacteria', non-bacterial infections and mixed infections), while antibiotic DCT (vs. non-antibiotic DCT) only showed a significant effect in combination with the pathogen categories streptococci and 'other Gram-positive bacteria'.

18.
Heliyon ; 9(12): e22376, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38046155

RESUMO

Hydropower is a traditional and widespread form of renewable energy and vertical axis turbines are an emerging technology suitable for low to medium velocity water bodies such as rivers. Such devices can provide renewable power to remote communities but may also contribute to fragmenting already poorly connected riverine habitats and the impact could be particularly pronounced for migratory diadromous aquatic species such as salmonids by limiting their ability to pass the turbines. Optimising the design of such turbines is therefore essential to mitigate their impact on aquatic fauna. One easily altered property that does not impact turbine performance is blade colour. Here, juvenile rainbow trout (Oncorhynchus mykiss) free swimming within a flume were monitored in the presence of a vertical axis turbine that was either stationary or rotating, and coloured white or orange. The orange colour of the turbine affected behaviour by increasing turbine avoidance and decreasing the number of potentially harmful interactions with the turbine when it was rotating, whilst not affecting passage or mobility of the trout compared to the white turbine. Visibility is therefore a potentially useful tool in mitigating the environmental impact of hydrokinetic turbines.

19.
Sci Rep ; 13(1): 7459, 2023 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-37156821

RESUMO

Hydrokinetic turbines such as vertical axis turbines (VATs) may provide decentralised, clean, sustainable energy for remote communities that lack access to the main energy grid or renewable resources. As traditional hydropower adversely alters aquatic ecosystems, it is essential to evaluate the environmental consequences of deploying VATs in riverine ecosystems to meet current and future energy needs. This study explores the implications of VATs on fish movement by observing fish swimming behaviour under two discharges, turbine operation states, and cross-sections confinements using scaled laboratory experiments. Our findings reveal that for cross-sectional confined conditions neither discharge, turbine presence, nor device operation, prevented fish from passing around and through the turbine both in the up- and downstream directions. However, fish spent the least time near the turbine vicinity and within the turbine's turbulent, low-velocity wake, indicating avoidance behaviour. Swimming in a less confined test section further reduced the time spent within the turbine's vicinity and wake, increasing the distance fish kept away from the device. Our results contribute to an understanding of VATs as low-risk hazards for fish swimming behaviour, advancing the potential of deploying VATs in rivers, estuaries or sea as a renewable energy solution for remote communities.

20.
mBio ; 14(5): e0084123, 2023 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-37787543

RESUMO

IMPORTANCE: Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis, one of the deadliest infectious diseases worldwide. Previous studies have established that synonymous recoding to introduce rare codon pairings can attenuate viral pathogens. We hypothesized that non-optimal codon pairing could be an effective strategy for attenuating gene expression to create a live vaccine for Mtb. We instead discovered that these synonymous changes enabled the transcription of functional mRNA that initiated in the middle of the open reading frame and from which many smaller protein products were expressed. To our knowledge, this is one of the first reports that synonymous recoding of a gene in any organism can create or induce intragenic transcription start sites.


Assuntos
Mycobacterium , Mutação Silenciosa , Códon , RNA Mensageiro , Mycobacterium/genética
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