Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 50
Filtrar
1.
Cell ; 159(3): 597-607, 2014 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-25417110

RESUMO

During eukaryotic translation initiation, initiator tRNA does not insert fully into the P decoding site on the 40S ribosomal subunit. This conformation (POUT) is compatible with scanning mRNA for the AUG start codon. Base pairing with AUG is thought to promote isomerization to a more stable conformation (PIN) that arrests scanning and promotes dissociation of eIF1 from the 40S subunit. Here, we present a cryoEM reconstruction of a yeast preinitiation complex at 4.0 Å resolution with initiator tRNA in the PIN state, prior to eIF1 release. The structure reveals stabilization of the codon-anticodon duplex by the N-terminal tail of eIF1A, changes in the structure of eIF1 likely instrumental in its subsequent release, and changes in the conformation of eIF2. The mRNA traverses the entire mRNA cleft and makes connections to the regulatory domain of eIF2?, eIF1A, and ribosomal elements that allow recognition of context nucleotides surrounding the AUG codon.


Assuntos
Fatores de Iniciação em Eucariotos/metabolismo , Kluyveromyces/metabolismo , Iniciação Traducional da Cadeia Peptídica , Saccharomyces cerevisiae/metabolismo , Sequência de Bases , Códon de Iniciação , Microscopia Crioeletrônica , Modelos Moleculares , Dados de Sequência Molecular , RNA de Transferência/metabolismo , Ribossomos/metabolismo , Alinhamento de Sequência
2.
Curr Microbiol ; 80(7): 236, 2023 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-37286880

RESUMO

Clostridioides difficile is a human pathogen that is ubiquitous in soil. Despite increasing infection rates and evidence of foodborne transmission, there is limited data on prevalence in soil or which factors influence persistence. The aim of this study was to investigate the prevalence of these bacteria in soil from three different spinach fields and to examine the chemical composition (carbon, organic carbon, nitrogen, organic matter, minerals and pH) and microbiota to gain insight into the factors that may promote/inhibit C. difficile. The overall C. difficile prevalence (10%) was lower than expected (based on international studies) and a significantly (P < 0.05) higher prevalence was obtained in Field 3 (20%) as compared to Fields 1 and 2 (5% each). Analysis of the soil suggested that the pH as well as organic matter, calcium and phosphorus content directly and indirectly (via the microbiota) influenced the prevalence of C. difficile in adjacent fields, where other factors (eg. climate) are similar. Although further studies are required to validate our findings, the data provides the first step in developing potential soil based control strategies.


Assuntos
Clostridioides difficile , Solo , Humanos , Solo/química , Clostridioides , Spinacia oleracea , Prevalência , Carbono
3.
Food Microbiol ; 112: 104215, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36906315

RESUMO

The increased detection of clinical cases of Clostridioides difficile coupled with the persistence of clostridial spores at various stages along the food chain suggest that this pathogen may be foodborne. This study examined C. difficile (ribotypes 078 and 126) spore viability in chicken breast, beef steak, spinach leaves and cottage cheese during refrigerated (4 °C) and frozen (-20 °C) storage with and without a subsequent sous vide mild cooking (60 °C, 1 h). Spore inactivation at 80 °C in phosphate buffer solution, beef and chicken were also investigated to provide D80°C values and determine if PBS was a suitable model system for real food matrices. There was no decrease in spore concentration after chilled or frozen storage and/or sous vide cooking at 60 °C. Non-log-linear thermal inactivation was observed for both C. difficile ribotypes at 80 °C in phosphate buffer solution (PBS), beef and chicken. The predicted PBS D80°C values of 5.72±[2.90, 8.55] min and 7.50±[6.61, 8.39] min for RT078 and RT126, respectively, were in agreement with the food matrices D80°C values of 5.65 min (95% CI range from 4.29 to 8.89 min) for RT078 and 7.35 min (95% CI range from 6.81 to 7.01 min) for RT126. It was concluded that C. difficile spores survive chilled and frozen storage and mild cooking at 60 °C but may be inactivated at 80 °C. Moreover thermal inactivation in PBS was representative of that observed in real food matrices (beef and chicken).


Assuntos
Clostridioides difficile , Animais , Bovinos , Clostridioides , Esporos Bacterianos/fisiologia , Culinária , Fosfatos
4.
Curr Genet ; 68(5-6): 619-644, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35994100

RESUMO

An extensive mutational analysis of RPL33A, encoding the yeast ribosomal protein L33A (eL33) allowed us to identify several novel rpl33a mutants with different translational phenotypes. Most of the rpl33a mutants are defective in the processing of 35S and 27S pre-rRNA precursors and the production of mature rRNAs, exhibiting reductions in the amounts of ribosomal subunits and altered polysome profiles. Some of the rpl33a mutants exhibit a Gcd- phenotype of constitutive derepression of GCN4 translation and strong slow growth phenotypes at several temperatures. Interestingly, some of the later mutants also show a detectable increase in the UUG/AUG translation initiation ratio that can be suppressed by eIF1 overexpression, suggesting a requirement for eL33 and a correct 60S/40S subunit ratio for the proper recognition of the AUG start codon. In addition to producing differential reductions in the rates of pre-rRNA maturation and perhaps in r-protein assembly, most of the point rpl33a mutations alter specific molecular interactions of eL33 with the rRNAs and other r-proteins in the 60S structure. Thus, rpl33a mutations cause distinctive effects on the abundance and/or functionality of 60S subunits, leading to more or less pronounced defects in the rates and fidelity of mRNA translation.


Assuntos
Proteínas Ribossômicas , Proteínas de Saccharomyces cerevisiae , Fatores de Transcrição de Zíper de Leucina Básica/genética , Ribossomos/genética , Ribossomos/metabolismo , Precursores de RNA/genética , RNA Ribossômico/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/metabolismo
5.
Food Microbiol ; 98: 103781, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33875209

RESUMO

An increasing proportion of Clostridioides difficile infections (CDI) are community acquired. This study tested farm, abattoir and retail food samples for C. difficile, using peer reviewed culture and molecular methods. The contamination rate on beef, sheep and broiler farms ranged from 2/30 (7%) to 25/30 (83%) in faeces, soil and water samples, while concentrations ranged from 2.9 log10 cfu/ml to 8.4 log10 cfu/g. The prevalence and associated counts were much lower in abattoir samples. Although 26/60 were C. difficile positive by enrichment and PCR, only 6 samples yielded counts by direct plating (1.1 log10 cfu/cm2 to 5.1 log10 cfu/g). At retail, 9/240 samples were C. difficile positive, including corned beef (1), spinach leaves (2), iceberg lettuce, little gem lettuce, wild rocket, coleslaw, whole milk yogurt and cottage cheese (1 sample each), with counts of up to 6.8 log10 cfu/g. The tcdA, tcdB, cdtA, cdtB, tcdC and tcdR genes were detected in 41%, 99.2%, 33.6%, 32%, 46.7% and 31.1%, respectively, of the 122 C. difficile isolates obtained. It was concluded that although the prevalence of C. difficile decreased along the food chain, retail foods were still heavily contaminated. This pathogen may therefore be foodborne, perhaps necessitating dietary advice for potentially vulnerable patients.


Assuntos
Clostridioides difficile/isolamento & purificação , Infecções por Clostridium/veterinária , Contaminação de Alimentos/estatística & dados numéricos , Carne/microbiologia , Verduras/microbiologia , Matadouros/estatística & dados numéricos , Animais , Bovinos , Galinhas , Clostridioides difficile/classificação , Clostridioides difficile/genética , Clostridioides difficile/crescimento & desenvolvimento , Infecções por Clostridium/epidemiologia , Infecções por Clostridium/microbiologia , Qualidade de Produtos para o Consumidor , Fazendas/estatística & dados numéricos , Fezes/microbiologia , Contaminação de Alimentos/análise , Contaminação de Alimentos/economia , Humanos , Irlanda/epidemiologia , Carne/economia , Ovinos , Verduras/economia
6.
Molecules ; 26(19)2021 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-34641471

RESUMO

Orange peel by-products generated in the food industry are an important source of value-added compounds that can be potentially reused. In the current research, the effect of oven-drying (50-70 °C) and freeze-drying on the bioactive compounds and antioxidant potential from Navelina, Salustriana, and Sanguina peel waste was investigated using pressurized extraction (ASE). Sixty volatile components were identified by ASE-GC-MS. The levels of terpene derivatives (sesquitenenes, alcohols, aldehydes, hydrocarbons, and esters) remained practically unaffected among fresh and freeze-dried orange peels, whereas drying at 70 °C caused significative decreases in Navelina, Salustriana, and Sanguina peels. Hesperidin and narirutin were the main flavonoids quantified by HPLC-MS. Freeze-dried Sanguina peels showed the highest levels of total-polyphenols (113.3 mg GAE·g-1), total flavonoids (39.0 mg QE·g-1), outstanding values of hesperedin (187.6 µg·g-1), phenol acids (16.54 mg·g-1 DW), and the greatest antioxidant values (DPPH•, FRAP, and ABTS•+ assays) in comparison with oven-dried samples and the other varieties. Nanotechnology approaches allowed the formulation of antioxidant-loaded nanoemulsions, stabilized with lecithin, starting from orange peel extracts. Those provided 70-80% of protection against oxidative UV-radiation, also decreasing the ROS levels into the Caco-2 cells. Overall, pressurized extracts from freeze-drying orange peel can be considered a good source of natural antioxidants that could be exploited in food applications for the development of new products of commercial interest.


Assuntos
Antioxidantes/isolamento & purificação , Citrus sinensis/química , Flavonoides/análise , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais/farmacologia , Polifenóis/análise , Antioxidantes/farmacologia , Células CACO-2 , Sobrevivência Celular , Emulsões , Temperatura Alta , Humanos , Extratos Vegetais/isolamento & purificação , Pressão
7.
J Food Sci Technol ; 58(10): 4034-4044, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34471327

RESUMO

The objective of this study was to use accelerated-solvent-extraction to achieve antioxidant extracts from chia seeds oils, enriched in tocopherols and tocotrienols, namely tocochromanols. Nanotechnology applications have been also incorporated to develop an innovative formulation of chia seeds oil nanoemulsion that preserve its antioxidant potential after conditions of oxidative stress. Chia seeds oils proved to be a valuable source of tocochromanols, from 568.84 to 855.98 µg g-1, depending on the geographical provenance. Quantitative data obtained by LC-DAD-ESI-MS/MS showed outstanding levels of γ-Tocopherol, over 83%, followed far behind by Tocopherols-(α, ß, δ) and Tocotrienols-(α, ß, δ, γ)-tocotrienols. The characteristic tocochromanols fingerprint of chia seeds oils was positively correlated with the FRAP and DPPH antioxidant activity of the extracts (between 18.81 and 138.48 mg Trolox/g). Formulation of the Chia seeds oils as nanoemulsions did not compromised the antioxidant properties of fresh extracts. Interestingly, nanoemulsions retained about the 80% of the initial antioxidant capacity after UV-induced stress, where the non-emulsified oils displayed a remarkable reduction (50-60%) on its antioxidant capacity under the same conditions. These antioxidant chia seeds formulations can constitute a promising strategy to vectorizing vitamin E isomers, in order to be used for food fortification, natural additives and to increase the self-life of food products during packing.

8.
RNA ; 20(2): 150-67, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24335188

RESUMO

In the current model of translation initiation by the scanning mechanism, eIF1 promotes an open conformation of the 40S subunit competent for rapidly loading the eIF2·GTP·Met-tRNAi ternary complex (TC) in a metastable conformation (POUT) capable of sampling triplets entering the P site while blocking accommodation of Met-tRNAi in the PIN state and preventing completion of GTP hydrolysis (Pi release) by the TC. All of these functions should be reversed by eIF1 dissociation from the preinitiation complex (PIC) on AUG recognition. We tested this model by selecting eIF1 Ssu(-) mutations that suppress the elevated UUG initiation and reduced rate of TC loading in vivo conferred by an eIF1 (Sui(-)) substitution that eliminates a direct contact of eIF1 with the 40S subunit. Importantly, several Ssu(-) substitutions increase eIF1 affinity for 40S subunits in vitro, and the strongest-binding variant (D61G), predicted to eliminate ionic repulsion with 18S rRNA, both reduces the rate of eIF1 dissociation and destabilizes the PIN state of TC binding in reconstituted PICs harboring Sui(-) variants of eIF5 or eIF2. These findings establish that eIF1 dissociation from the 40S subunit is required for the PIN mode of TC binding and AUG recognition and that increasing eIF1 affinity for the 40S subunit increases initiation accuracy in vivo. Our results further demonstrate that the GTPase-activating protein eIF5 and ß-subunit of eIF2 promote accuracy by controlling eIF1 dissociation and the stability of TC binding to the PIC, beyond their roles in regulating GTP hydrolysis by eIF2.


Assuntos
Fator de Iniciação 1 em Eucariotos/metabolismo , Subunidades Ribossômicas Menores de Eucariotos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Iniciação da Transcrição Genética , Sequência de Aminoácidos , Códon de Iniciação , Fator de Iniciação 1 em Eucariotos/química , Fator de Iniciação 1 em Eucariotos/genética , Fator de Iniciação 2 em Eucariotos/genética , Fator de Iniciação 2 em Eucariotos/metabolismo , Fator de Iniciação 5 em Eucariotos/química , Fator de Iniciação 5 em Eucariotos/metabolismo , Técnicas de Inativação de Genes , Guanosina Trifosfato/química , Guanosina Trifosfato/metabolismo , Hidrólise , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Ligação Proteica , Estabilidade Proteica , Subunidades Ribossômicas Menores de Eucariotos/química , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética
9.
Nucleic Acids Res ; 42(15): 9623-40, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25114053

RESUMO

eIF5 is the GTPase activating protein (GAP) for the eIF2 · GTP · Met-tRNAi (Met) ternary complex with a critical role in initiation codon selection. Previous work suggested that the eIF5 mutation G31R/SUI5 elevates initiation at UUG codons by increasing GAP function. Subsequent work implicated eIF5 in rearrangement of the preinitiation complex (PIC) from an open, scanning conformation to a closed state at AUG codons, from which Pi is released from eIF2 · GDP · Pi. To identify eIF5 functions crucial for accurate initiation, we investigated the consequences of G31R on GTP hydrolysis and Pi release, and the effects of intragenic G31R suppressors on these reactions, and on the partitioning of PICs between open and closed states. eIF5-G31R altered regulation of Pi release, accelerating it at UUG while decreasing it at AUG codons, consistent with its ability to stabilize the closed complex at UUG. Suppressor G62S mitigates both defects of G31R, accounting for its efficient suppression of UUG initiation in G31R,G62S cells; however suppressor M18V impairs GTP hydrolysis with little effect on PIC conformation. The strong defect in GTP hydrolysis conferred by M18V likely explains its broad suppression of Sui(-) mutations in numerous factors. We conclude that both of eIF5's functions, regulating Pi release and stabilizing the closed PIC conformation, contribute to stringent AUG selection in vivo.


Assuntos
Códon de Iniciação , Fator de Iniciação 5 em Eucariotos/metabolismo , Guanosina Trifosfato/metabolismo , Iniciação Traducional da Cadeia Peptídica , Fator de Iniciação 1 em Eucariotos/genética , Fator de Iniciação 2 em Eucariotos/genética , Fator de Iniciação 5 em Eucariotos/química , Fator de Iniciação 5 em Eucariotos/genética , Mutação , Fosfatos/metabolismo , Supressão Genética
10.
J Biol Chem ; 288(38): 27546-27562, 2013 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-23893413

RESUMO

Recognition of the translation initiation codon is thought to require dissociation of eIF1 from the 40 S ribosomal subunit, enabling irreversible GTP hydrolysis (Pi release) by the eIF2·GTP·Met-tRNAi ternary complex (TC), rearrangement of the 40 S subunit to a closed conformation incompatible with scanning, and stable binding of Met-tRNAi to the P site. The crystal structure of a Tetrahymena 40 S·eIF1 complex revealed several basic amino acids in eIF1 contacting 18 S rRNA, and we tested the prediction that their counterparts in yeast eIF1 are required to prevent premature eIF1 dissociation from scanning ribosomes at non-AUG triplets. Supporting this idea, substituting Lys-60 in helix α1, or either Lys-37 or Arg-33 in ß-hairpin loop-1, impairs binding of yeast eIF1 to 40 S·eIF1A complexes in vitro, and it confers increased initiation at UUG codons (Sui(-) phenotype) or lethality, in a manner suppressed by overexpressing the mutant proteins or by an eIF1A mutation (17-21) known to impede eIF1 dissociation in vitro. The eIF1 Sui(-) mutations also derepress translation of GCN4 mRNA, indicating impaired ternary complex loading, and this Gcd(-) phenotype is likewise suppressed by eIF1 overexpression or the 17-21 mutation. These findings indicate that direct contacts of eIF1 with 18 S rRNA seen in the Tetrahymena 40 S·eIF1 complex are crucial in yeast to stabilize the open conformation of the 40 S subunit and are required for rapid TC loading and ribosomal scanning and to impede rearrangement to the closed complex at non-AUG codons. Finally, we implicate the unstructured N-terminal tail of eIF1 in blocking rearrangement to the closed conformation in the scanning preinitiation complex.


Assuntos
Códon de Iniciação/metabolismo , Fator de Iniciação 1 em Eucariotos/metabolismo , Iniciação Traducional da Cadeia Peptídica/fisiologia , RNA de Transferência de Metionina/metabolismo , Subunidades Ribossômicas Menores de Eucariotos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/biossíntese , Fatores de Transcrição de Zíper de Leucina Básica/genética , Códon de Iniciação/genética , Fator de Iniciação 1 em Eucariotos/genética , Mutação , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , RNA Fúngico/genética , RNA Fúngico/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA de Transferência de Metionina/genética , Subunidades Ribossômicas Menores de Eucariotos/genética , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/biossíntese , Proteínas de Saccharomyces cerevisiae/genética , Tetrahymena thermophila/genética , Tetrahymena thermophila/metabolismo
11.
RNA ; 17(3): 439-52, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21220547

RESUMO

Translation initiation in eukaryotes involves more than a dozen protein factors. Alterations in six factors have been found to reduce the fidelity of start codon recognition by the ribosomal preinitiation complex in yeast, a phenotype referred to as Sui(-). No small molecules are known that affect the fidelity of start codon recognition. Such compounds would be useful tools for probing the molecular mechanics of translation initiation and its regulation. To find compounds with this effect, we set up a high-throughput screen using a dual luciferase assay in S. cerevisiae. Screening of over 55,000 compounds revealed two structurally related molecules that decrease the fidelity of start codon selection by approximately twofold in the dual luciferase assay. This effect was confirmed using additional in vivo assays that monitor translation from non-AUG start codons. Both compounds increase translation of a natural upstream open reading frame previously shown to initiate translation at a UUG. The compounds were also found to exacerbate increased use of UUG as a start codon (Sui(-) phenotype) conferred by haploinsufficiency of wild-type eukaryotic initiation factor (eIF) 1, or by mutation in eIF1. Furthermore, the effects of the compounds are suppressed by overexpressing eIF1, which is known to restore the fidelity of start codon selection in strains harboring Sui(-) mutations in various other initiation factors. Together, these data strongly suggest that the compounds affect the translational machinery itself to reduce the accuracy of selecting AUG as the start codon.


Assuntos
Códon de Iniciação/fisiologia , Fator de Iniciação 1 em Eucariotos/metabolismo , Compostos Heterocíclicos/farmacologia , Iniciação Traducional da Cadeia Peptídica/efeitos dos fármacos , Iniciação Traducional da Cadeia Peptídica/fisiologia , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Fator de Iniciação 1 em Eucariotos/genética , Haploinsuficiência , Luciferases/metabolismo , Mutação/genética , Fenótipo , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Subunidades Ribossômicas Menores de Eucariotos/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Bibliotecas de Moléculas Pequenas
12.
Crit Care ; 17(6): R302, 2013 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-24377481

RESUMO

INTRODUCTION: Although the survival rates of hematological patients admitted to the ICU are improving, little is known about the long-term outcome. Our objective was to identify factors related to long-term outcome in hematological patients after ICU discharge. METHODS: A prospective, observational study was carried out in seven centers in Spain. From an initial sample of 161 hematological patients admitted to one of the participating ICUs during the study period, 62 were discharged alive and followed for a median time of 23 (1 to 54) months. Univariate and multivariate analysis were performed to identify the factors related to long term-survival. Finally, variables that influence the continuation of the scheduled therapy for the hematological disease were studied. RESULTS: Mortality after ICU discharge was 61%, with a median survival of 18 (1 to 54) months. In the multivariate analysis, an Eastern Cooperative Oncology Group score (ECOG) >2 at ICU discharge (Hazard ratio 11.15 (4.626 to 26.872)), relapse of the hematological disease (Hazard ratio 9.738 (3.804 to 24.93)) and discontinuation of the planned treatment for the hematological disease (Hazard ratio 4.349 (1.286 to 14.705)) were independently related to mortality. Absence of stem cell transplantation, high ECOG and high Acute Physiology and Chronic Health Evaluation II (APACHE II) scores decreased the probability of receiving the planned therapy for the hematological malignancy. CONCLUSIONS: Both ICU care and post-ICU management determine the long-term outcome of hematological patients who are discharged alive from the ICU.


Assuntos
Doenças Hematológicas/mortalidade , Unidades de Terapia Intensiva , Alta do Paciente , APACHE , Árvores de Decisões , Feminino , Doenças Hematológicas/complicações , Doenças Hematológicas/tratamento farmacológico , Humanos , Masculino , Adesão à Medicação , Pessoa de Meia-Idade , Insuficiência de Múltiplos Órgãos/etiologia , Neutropenia/complicações , Prognóstico , Estudos Prospectivos , Recidiva , Respiração Artificial , Fatores de Risco , Taxa de Sobrevida
13.
Nucleic Acids Res ; 39(18): 8105-21, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21724601

RESUMO

The 90S pre-ribosome, also known as the small subunit (SSU) processome, is a large multisubunit particle required for the production of the 18S rRNA from a pre-rRNA precursor. Recently, it has been shown that the formation of this particle entails the initial association of the tUTP subunit with the nascent pre-RNA and, subsequently, the binding of Rrp5/UTP-C and U3 snoRNP/UTP-B subunits in two independent assembly branches. However, the mode of assembly of other 90S pre-ribosome components remains obscure as yet. In this study, we have investigated the assembly of three proteins (Utp20, Imp4 and Bms1) previously regarded as potential nucleating factors of the 90S particle. Here, we demonstrate that the loading of those three proteins onto the pre-rRNA takes place independently of Rrp5/UTP-C and, instead, occurs downstream of the tUTP and U3/UTP-B subcomplexes. We also demonstrate that Bms1 and Utp20 are required for the recruitment of a subset of proteins to nascent pre-ribosomes. Finally, we show that proteins associated through secondary steps condition the stability of the two assembly branches in partially assembled pre-ribosomes. These results provide new information about the functional relationships among 90S particle components and the events that are required for their stepwise incorporation onto the primary pre-rRNA.


Assuntos
Proteínas de Ligação ao GTP/metabolismo , Proteínas Nucleares/metabolismo , RNA Ribossômico/metabolismo , Proteínas de Ligação a RNA/metabolismo , Ribonucleoproteínas Nucleares Pequenas/metabolismo , Proteínas Ribossômicas/metabolismo , Ribossomos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Subunidades Proteicas/metabolismo , Ribonucleoproteínas Nucleolares Pequenas/metabolismo
14.
Foods ; 12(5)2023 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-36900611

RESUMO

The recent discovery of the same Clostridioides difficile ribotypes associated with human infection in a broad range of environments, animals and foods, coupled with an ever-increasing rate of community-acquired infections, suggests this pathogen may be foodborne. The objective of this review was to examine the evidence supporting this hypothesis. A review of the literature found that forty-three different ribotypes, including six hypervirulent strains, have been detected in meat and vegetable food products, all of which carry the genes encoding pathogenesis. Of these, nine ribotypes (002, 003, 012, 014, 027, 029, 070, 078 and 126) have been isolated from patients with confirmed community-associated C. difficile infection (CDI). A meta-analysis of this data suggested there is a higher risk of exposure to all ribotypes when consuming shellfish or pork, with the latter being the main foodborne route for ribotypes 027 and 078, the hypervirulent strains that cause most human illnesses. Managing the risk of foodborne CDI is difficult as there are multiple routes of transmission from the farming and processing environment to humans. Moreover, the endospores are resistant to most physical and chemical treatments. The most effective current strategy is, therefore, to limit the use of broad-spectrum antibiotics while advising potentially vulnerable patients to avoid high-risk foods such as shellfish and pork.

15.
Microorganisms ; 11(5)2023 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-37317270

RESUMO

The aim of this study was to characterize C. difficile isolates from the farm, abattoir, and retail outlets in Ireland in terms of ribotype and antibiotic resistance (vancomycin, erythromycin, metronidazole, moxifloxacin, clindamycin, and rifampicin) using PCR and E-test methods, respectively. The most common ribotype in all stages of the food chain (including retail foods) was 078 and a variant (RT078/4). Less commonly reported (014/0, 002/1, 049, and 205) and novel (RT530, 547, and 683) ribotypes were also detected, but at lower frequencies. Approximately 72% (26/36 tested) of the isolates tested were resistant to at least one antibiotic, with the majority of these (65%; 17/26) displaying a multi-drug (three to five antibiotics) resistant phenotype. It was concluded that ribotype 078, a hypervirulent strain commonly associated with C. difficile infection (CDI) in Ireland, was the most frequent ribotype along the food chain, resistance to clinically important antibiotics was common in C. difficile food chain isolates, and there was no relationship between ribotype and antibiotic resistance profile.

16.
Brain Imaging Behav ; 17(4): 403-413, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37024762

RESUMO

Little information is available on the magnetic resonance imaging (MRI) determination of the hippocampal formation (HF) during the perinatal period. However, this exploration is increasingly used, which requires defining visible HF landmarks on MRI images, validated through histological analysis. This study aims to provide a protocol to identify HF landmarks on MRI images, followed by histological validation through serial sections of the temporal lobe of the samples examined, to assess the longitudinal extent of the hippocampus during the perinatal period. We examined ex vivo MRI images from nine infant control brain samples. Histological validation of the hippocampal formation MRI images was obtained through serial sectioning and examination of Nissl-stained sections at 250 µm intervals along the entire length of the hippocampal formation. Up to six landmarks were identified both in MRI images and the serial histological sections. Proceeding in an anterior to posterior (rostrocaudal) direction, these were as follows: 1) the limen insulae (fronto-temporal junction); 2) the beginning of the amygdaloid complex; 3) the beginning of the lateral ventricle; 4) the caudal limit of the uncus, indicated by the start of the lateral geniculate nucleus (at the level of the gyrus intralimbicus); 5) the end of the lateral geniculate nucleus (beginning of the pulvinar); and 6) the beginning of the fornix. After histological validation of each of these landmarks, the full longitudinal length of the hippocampal formation and distances between landmarks were calculated. No statistically significant differences were found in total length or between landmarks. While the HF is anatomically organized at birth, its annotation is particularly challenging to perform. The histological validation of HF landmarks allows a better understanding of MRI images. The proposed protocol could be useful to assess MRI hippocampal quantification in children and possible variations due to different neurological diseases.


Assuntos
Hipocampo , Imageamento por Ressonância Magnética , Lactente , Criança , Recém-Nascido , Humanos , Imageamento por Ressonância Magnética/métodos , Hipocampo/diagnóstico por imagem , Hipocampo/patologia , Lobo Temporal , Encéfalo , Espectroscopia de Ressonância Magnética
17.
Crit Care ; 16(2): R44, 2012 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-22410278

RESUMO

INTRODUCTION: Non-neurological complications in patients with severe traumatic brain injury (TBI) are frequent, worsening the prognosis, but the pathophysiology of systemic complications after TBI is unclear. The purpose of this study was to analyze non-neurological complications in patients with severe TBI admitted to the ICU, the impact of these complications on mortality, and their possible correlation with TBI severity. METHODS: An observational retrospective cohort study was conducted in one multidisciplinary ICU of a university hospital (35 beds); 224 consecutive adult patients with severe TBI (initial Glasgow Coma Scale (GCS) < 9) admitted to the ICU were included. Neurological and non-neurological variables were recorded. RESULTS: Sepsis occurred in 75% of patients, respiratory infections in 68%, hypotension in 44%, severe respiratory failure (arterial oxygen pressure/oxygen inspired fraction ratio (PaO2/FiO2) < 200) in 41% and acute kidney injury (AKI) in 8%. The multivariate analysis showed that Glasgow Outcome Score (GOS) at one year was independently associated with age, initial GCS 3 to 5, worst Traumatic Coma Data Bank (TCDB) first computed tomography (CT) scan and the presence of intracranial hypertension but not AKI. Hospital mortality was independently associated with initial GSC 3 to 5, worst TCDB first CT scan, the presence of intracranial hypertension and AKI. The presence of AKI regardless of GCS multiplied risk of death 6.17 times (95% confidence interval (CI): 1.37 to 27.78) (P < 0.02), while ICU hypotension increased the risk of death in patients with initial scores of 3 to 5 on the GCS 4.28 times (95% CI: 1.22 to 15.07) (P < 0.05). CONCLUSIONS: Low initial GCS, worst first CT scan, intracranial hypertension and AKI determined hospital mortality in severe TBI patients. Besides the direct effect of low GCS on mortality, this neurological condition also is associated with ICU hypotension which increases hospital mortality among patients with severe TBI. These findings add to previous studies that showed that non-neurological complications increase the length of stay and morbidity in the ICU but do not increase mortality, with the exception of AKI and hypotension in low GCS (3 to 5).


Assuntos
Lesões Encefálicas/complicações , Adulto , Lesões Encefálicas/mortalidade , Feminino , Escala de Coma de Glasgow , Mortalidade Hospitalar , Humanos , Unidades de Terapia Intensiva , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Estatísticas não Paramétricas , Tomografia Computadorizada por Raios X
19.
Curr Med Chem ; 29(23): 4026-4049, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34961454

RESUMO

Obesity leads to several metabolic disorders and, unfortunately, current pharmacological treatments for obesity are not very effective. In feeding mechanisms, the hypothalamus and some neuropeptides play an important role. Many data show that neuropeptide Y (NPY) is involved in these mechanisms. The aim of this review is to update the physiological actions mediated by the orexigenic peptide NPY, via its receptors, in the control of food intake and to review its involvement in food intake disorders. The relationships between NPY and other substances involved in food intake mechanisms, hypothalamic and extra-hypothalamic pathways involved in feeding and the potential pharmacological strategies to treat obesity will be discussed. Some research lines, focused on NPY, to be developed in the future are suggested. Neuropeptide systems are associated with redundancy and then therapies directed against a single target are generally ineffective. For this reason, other targets for the treatment of obesity are mentioned. It seems that combination therapies are the best option for successful anti-obesity treatments: new and more specific NPY receptor antagonists must be tested as anti-obesity drugs alone and in combination therapies.


Assuntos
Neuropeptídeo Y , Neuropeptídeos , Ingestão de Alimentos/fisiologia , Homeostase , Humanos , Hipotálamo/metabolismo , Neuropeptídeo Y/metabolismo , Neuropeptídeos/metabolismo , Obesidade/tratamento farmacológico , Obesidade/metabolismo , Receptores de Neuropeptídeo Y/metabolismo
20.
Pathogens ; 11(11)2022 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-36365061

RESUMO

Despite an increased incidence of Clostridioides difficile infections, data on the reservoirs and dissemination routes of this bacterium are limited. This study examined the prevalence and characteristics of C. difficile isolates in spinach fields. C. difficile was detected in 2/60 (3.3%) of spinach and 6/60 (10%) of soil samples using culture-based techniques. Whole genome sequencing (WGS) analysis identified the spinach isolates as belonging to the hypervirulent clade 5, sequence type (ST) 11, ribotypes (RT) 078 and 126 and carried the genes encoding toxins A, B and CDT. The soil isolates belonged to clade 1 with different toxigenic ST/RT (ST19/RT614, ST12/RT003, ST46/RT087, ST16/RT050, ST49/RT014/0) strains and one non-toxigenic ST79/RT511 strain. Antimicrobial resistance to erythromycin (one spinach isolate), rifampicin (two soil isolates), clindamycin (one soil isolate), both moxifloxacin and rifampicin (one soil isolate), and multi-drug resistance to erythromycin, vancomycin and rifampicin (two soil isolates) were observed using the E test, although a broader range of resistance genes were detected using WGS. Although the sample size was limited, our results demonstrate the presence of C. difficile in horticulture and provide further evidence that there are multiple sources and dissemination routes for these bacteria.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA