RESUMO
Cellular processes require precise and specific gene regulation, in which continuous mRNA degradation is a major element. The mRNA degradation mechanisms should be able to degrade a wide range of different RNA substrates with high efficiency, but should at the same time be limited, to avoid killing the cell by elimination of all cellular RNA. RNase Y is a major endoribonuclease found in most Firmicutes, including Bacillus subtilis and Staphylococcus aureus. However, the molecular interactions that direct RNase Y to cleave the correct RNA molecules at the correct position remain unknown. In this work we have identified transcripts that are homologs in S. aureus and B. subtilis, and are RNase Y targets in both bacteria. Two such transcript pairs were used as models to show a functional overlap between the S. aureus and the B. subtilis RNase Y, which highlighted the importance of the nucleotide sequence of the RNA molecule itself in the RNase Y targeting process. Cleavage efficiency is driven by the primary nucleotide sequence immediately downstream of the cleavage site and base-pairing in a secondary structure a few nucleotides downstream. Cleavage positioning is roughly localised by the downstream secondary structure and fine-tuned by the nucleotide immediately upstream of the cleavage. The identified elements were sufficient for RNase Y-dependent cleavage, since the sequence elements from one of the model transcripts were able to convert an exogenous non-target transcript into a target for RNase Y.
Assuntos
Bacillus subtilis , Regulação Bacteriana da Expressão Gênica , Clivagem do RNA , Estabilidade de RNA , RNA Bacteriano , Staphylococcus aureus , Staphylococcus aureus/genética , Staphylococcus aureus/enzimologia , Bacillus subtilis/genética , Bacillus subtilis/enzimologia , Bacillus subtilis/metabolismo , RNA Bacteriano/metabolismo , RNA Bacteriano/genética , Estabilidade de RNA/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Endorribonucleases/metabolismo , Endorribonucleases/genética , Conformação de Ácido Nucleico , Sequência de BasesRESUMO
sRNAs are a taxonomically-restricted but transcriptomically-abundant class of post-transcriptional regulators. While of major importance for adaption to the environment, we currently lack global-scale methodology enabling target identification, especially in species without known RNA hub proteins (e.g. Hfq). Using psoralen RNA cross-linking and Illumina-sequencing we identify RNA-RNA interacting pairs in vivo in Bacillus subtilis, resolving previously well-described interactants. Although sRNA-sRNA pairings are rare (compared with sRNA-mRNA), we identify a robust example involving the conserved sRNA RoxS and an unstudied sRNA RosA (Regulator of sRNA A). We show RosA to be the first confirmed RNA sponge described in a Gram-positive bacterium. RosA interacts with at least two sRNAs, RoxS and FsrA. The RosA/RoxS interaction not only affects the levels of RoxS but also its processing and regulatory activity. We also found that the transcription of RosA is repressed by CcpA, the key regulator of carbon-metabolism in B. subtilis. Since RoxS is already known to be transcriptionally controlled by malate via the transcriptional repressor Rex, its post-transcriptional regulation by CcpA via RosA places RoxS in a key position to control central metabolism in response to varying carbon sources.
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Bacillus subtilis/genética , RNA Bacteriano/metabolismo , Pequeno RNA não Traduzido/metabolismo , Bacillus subtilis/metabolismo , Proteínas de Bactérias/metabolismo , Carbono/metabolismo , Aptidão Genética , Proteoma , Processamento Pós-Transcricional do RNA , Estabilidade de RNA , Pequeno RNA não Traduzido/biossíntese , Pequeno RNA não Traduzido/genética , Pequeno RNA não Traduzido/fisiologia , Transcrição GênicaRESUMO
BACKGROUND: In the general population, sport activity is associated with better health and better self-esteem. Among people living with HIV (PLHIV), sport activity could also be associated with better self-esteem. The main objective of our study was to assess the association between sport activity and self-esteem among people living with HIV. The secondary objectives were to evaluate the associations between sport activity with fatigue as well as with pain. METHODS: We performed a cross-sectional observational study among PLHIV in our region (Pays de la Loire in France). Each adult seen in routine HIV care was invited to participate in the study. Participants were invited to fill out self-questionnaires about sport activity, self-esteem, fatigue, and pain. The 2 groups of participants with and without sport activity were compared with a T Student test for self-esteem, fatigue, and pain scales. RESULTS: Among the 1160 people included in the study, 47% performed sport activity. The self-esteem score was better in the "sporting group" compared with the "non sporting group" (Rosenberg mean scale 32.7 ± 5.1/40 vs 31.9 ± 5 p = 0.01). The Functional Assessment of Chronic Illness Therapy Fatigue scale showed a lower fatigue in the sporting group than in the non-sporting group (mean total score 125 ± 22 vs 118 ± 24 p < 0.0001). The sporting group had a lower mean pain score (1.1 ± 1.8) than the non sporting group (1.4 ± 1.9 p = 0.004). CONCLUSIONS: Among PLHIV in our region, sport activity was associated with better self-esteem, lower fatigue and lower pain. Sport activity should be included in patient care for people living with HIV.
Assuntos
Infecções por HIV , Autoimagem , Adulto , Humanos , Estudos Transversais , Fadiga/etiologia , Infecções por HIV/epidemiologia , DorRESUMO
BACKGROUND: Chronic Kidney Disease (CKD) is associated with reduced muscular strength resulting in profound fatigue. The physiopathology of these changes, their prevalence and evolution are still debated. Moreover, we have little data on elderly CKD patients. The present study protocol aims to 1) quantify the prevalence of low muscle strength (dynapenia) in a cohort of elderly patients with advanced CKD and to 2) characterize their force production coupled with electromyographic features and the symptoms of fatigue compared to a matched control group. METHODS: This is a case-control, prospective, interventional study. INCLUSION CRITERIA: age ≥ 60 years; CKD Stage 3b-5; clinical stability (i.e. no hospitalization and ≤ 25% in creatinine increase in the previous 3 months). Controls with normal kidney function will be matched in terms of age, gender and diabetes mellitus (requisite: estimated glomerular filtration rate ≥ 60 ml/min/1.73m2 available in the last 6 months). Exclusion criteria for cases and controls: neuromuscular disease, life expectancy < 3 months. The handgrip strength protocol is an intermittent test consisting in 6 series of 9 repetitions of 3-s sub-maximum contractions at 40% of the maximum voluntary contraction (MVC) and 2 s of resting time between contractions. Each series is separated by one fast sub-maximum contraction and one MVC. Strength is assessed with a high-frequency handgrip dynamometer paired with surface electromyography. Symptoms of fatigue are assessed using MFI-20 and FACIT-F questionnaires. In order to reach a statistical power of 96%, we plan to enroll 110 subjects in each group. DISCUSSION: The novelty of this study resides in the application of an already validated set of tests in a population in which this combination (dynamometer, electromyography and questionnaires) has not previously been explored. We expect a high prevalence of dynapenia and a higher fatigability in CKD patients. A positive correlation is expected between reported fatigue and fatigability. Better appreciation of the prevalence and the relationship between fatigability and a sensation of fatigue can help us target interventions in CKD patients to improve quality of life and survival. TRIAL REGISTRATION: The study was approved by Ethical Committee EST III n°20.03.01 and was recorded as a Clinical Trial (NCT04330807) on April 2, 2020.
Assuntos
Fadiga/epidemiologia , Força da Mão , Contração Muscular , Fadiga Muscular , Debilidade Muscular/epidemiologia , Insuficiência Renal Crônica/epidemiologia , Idoso , Estudos de Casos e Controles , Estudos de Coortes , Eletromiografia , Fadiga/fisiopatologia , Humanos , Falência Renal Crônica/epidemiologia , Pessoa de Meia-Idade , Força Muscular , Dinamômetro de Força Muscular , Debilidade Muscular/fisiopatologia , Prevalência , Estudos ProspectivosRESUMO
We previously showed that ribosomes initiating translation of the B. subtilis hbs mRNA at a strong Shine-Dalgarno sequence block the 5' exoribonuclease RNase J1 from degrading into the coding sequence. Here, we identify new and previously unsuspected features of this mRNA. First, we identify RNase Y as the endoribonuclease that cleaves the highly structured 5'-UTR to give access to RNase J1. Cleavage by RNase Y at this site is modulated by a 14-bp long-range interaction between the 5'- and 3-UTRs that partially overlaps the cleavage site. In addition to this maturation/degradation pathway, we discovered a new and ultimately more important RNase Y cleavage site in the very early coding sequence, masked by the initiating ribosome. Thus, two independent pathways compete with ribosomes to tightly link hbs mRNA stability to translation initiation; in one case the initiating ribosome competes directly with RNase J1 and in the other with RNase Y. This is in contrast to prevailing models in Escherichia coli where ribosome traffic over the ORF is the main source of protection from RNases. Indeed, a second RNase Y cleavage site later in the hbs ORF plays no role in its turnover, confirming that for this mRNA at least, initiation is key.
Assuntos
Bacillus subtilis/metabolismo , Proteínas de Bactérias/metabolismo , Ribonucleases/metabolismo , Ribossomos/metabolismo , Regiões 3' não Traduzidas/genética , Regiões 5' não Traduzidas/genética , Bacillus subtilis/genética , Proteínas de Bactérias/genética , Sequência de Bases , Modelos Genéticos , Biossíntese de Proteínas/genética , Clivagem do RNA , Estabilidade de RNA/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ribonucleases/genética , Ribossomos/genéticaRESUMO
Benthic cyanobacteria strains from Guadeloupe have been investigated for the first time by combining phylogenetic, chemical and biological studies in order to better understand the taxonomic and chemical diversity as well as the biological activities of these cyanobacteria through the effect of their specialized metabolites. Therefore, in addition to the construction of the phylogenetic tree, indicating the presence of 12 potentially new species, an LC-MS/MS data analysis workflow was applied to provide an overview on chemical diversity of 20 cyanobacterial extracts, which was linked to antimicrobial activities evaluation against human pathogenic and ichtyopathogenic environmental strains.
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Produtos Biológicos/farmacologia , Cianobactérias/química , Cianobactérias/genética , Bactérias Gram-Negativas/efeitos dos fármacos , Filogenia , Antibacterianos , Anti-Infecciosos , Guadalupe , Áreas AlagadasRESUMO
This article presents the design and implementation of an event-triggered control approach, applied to the leader-following consensus and formation of a group of autonomous micro-aircraft with capabilities of vertical take-off and landing (VTOL-UAVs). The control strategy is based on an inner-outer loop control approach. The inner control law stabilizes the attitude and position of one agent, whereas the outer control follows a virtual leader to achieve position consensus cooperatively through an event-triggered policy. The communication topology uses undirected and connected graphs. With such an event-triggered control, the closed-loop trajectories converge to a compact sphere, centered in the origin of the error space. Furthermore, the minimal inter-sampling time is proven to be below bounded avoiding the Zeno behavior. The formation problem addresses the group of agents to fly in a given shape configuration. The simulation and experimental results highlight the performance of the proposed control strategy.
RESUMO
RsaE is the only known trans-acting small regulatory RNA (sRNA) besides the ubiquitous 6S RNA that is conserved between the human pathogen Staphylococcus aureus and the soil-dwelling Firmicute Bacillus subtilis. Although a number of RsaE targets are known in S. aureus, neither the environmental signals that lead to its expression nor its physiological role are known. Here we show that expression of the B. subtilis homolog of RsaE is regulated by the presence of nitric oxide (NO) in the cellular milieu. Control of expression by NO is dependent on the ResDE two-component system in B. subtilis and we determined that the same is true in S. aureus. Transcriptome and proteome analyses revealed that many genes with functions related to oxidative stress and oxidation-reduction reactions were up-regulated in a B. subtilis strain lacking this sRNA. We have thus renamed it RoxS. The prediction of RoxS-dependent mRNA targets also suggested a significant enrichment for mRNAs related to respiration and electron transfer. Among the potential direct mRNA targets, we have validated the ppnKB mRNA, encoding an NAD+/NADH kinase, both in vivo and in vitro. RoxS controls both translation initiation and the stability of this transcript, in the latter case via two independent pathways implicating RNase Y and RNase III. Furthermore, RNase Y intervenes at an additional level by processing the 5' end of the RoxS sRNA removing about 20 nucleotides. Processing of RoxS allows it to interact more efficiently with a second target, the sucCD mRNA, encoding succinyl-CoA synthase, thus expanding the repertoire of targets recognized by this sRNA.
Assuntos
Óxido Nítrico/metabolismo , RNA Bacteriano/genética , RNA não Traduzido/genética , Infecções Estafilocócicas/genética , Transcrição Gênica , Bacillus subtilis/genética , Regulação Bacteriana da Expressão Gênica , Homeostase/genética , Óxido Nítrico/genética , Oxirredução , RNA Bacteriano/biossíntese , RNA Mensageiro/genética , RNA não Traduzido/biossíntese , Ribonuclease III/genética , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/patologia , Staphylococcus aureus/genéticaRESUMO
Messenger RNA decay in Bacillus subtilis is accomplished by a combination of exoribonucleases and endoribonucleases. Intermediates in the decay process have not been readily detectable, and previous studies on mRNA decay have used a handful of highly expressed transcripts as models. Here, we use RNA-Seq analysis to probe mRNA turnover globally. A significant fraction of messages showed differential accumulation of RNA fragments that mapped near the 5' or 3' end of the coding sequence, consistent with initiation of decay from either the 5' end or from an internal cleavage site. Patterns of mRNA decay in the wild type were compared with patterns in a mutant strain lacking polynucleotide phosphorylase (PNPase), which is considered the major 3' exonuclease activity in mRNA decay and which is one of four known 3' exonucleases in B. subtilis. The results showed a striking dependence on PNPase for mRNA turnover in many cases, suggesting specificity in the ability of 3' exonucleases to degrade from 3'-hydroxyl termini. RNA-Seq data demonstrated a sharp decrease in expression of Sigma D in the PNPase-deletion strain. Reduction in sigD regulon expression explained the chain growth phenotype of the PNPase mutant and also predicted a defect in swarming motility.
Assuntos
Bacillus subtilis/enzimologia , Bacillus subtilis/genética , Proteínas de Bactérias/genética , Polirribonucleotídeo Nucleotidiltransferase/genética , RNA Bacteriano/metabolismo , Bacillus subtilis/metabolismo , Proteínas de Bactérias/metabolismo , Deleção de Genes , Polirribonucleotídeo Nucleotidiltransferase/deficiência , Estabilidade de RNA , RNA Bacteriano/genéticaRESUMO
RNase III-related enzymes play key roles in cleaving double-stranded RNA in many biological systems. Among the best-known are RNase III itself, involved in ribosomal RNA maturation and mRNA turnover in bacteria, and Drosha and Dicer, which play critical roles in the production of micro (mi)-RNAs and small interfering (si)-RNAs in eukaryotes. Although RNase III has important cellular functions in bacteria, its gene is generally not essential, with the remarkable exception of that of Bacillus subtilis. Here we show that the essential role of RNase III in this organism is to protect it from the expression of toxin genes borne by two prophages, Skin and SPß, through antisense RNA. Thus, while a growing number of organisms that use RNase III or its homologs as part of a viral defense mechanism, B. subtilis requires RNase III for viral accommodation to the point where the presence of the enzyme is essential for cell survival. We identify txpA and yonT as the two toxin-encoding mRNAs of Skin and SPß that are sensitive to RNase III. We further explore the mechanism of RNase III-mediated decay of the txpA mRNA when paired to its antisense RNA RatA, both in vivo and in vitro.
Assuntos
Bacillus subtilis , Prófagos , RNA de Cadeia Dupla/genética , Ribonuclease III/genética , Bacillus subtilis/genética , Bacillus subtilis/virologia , Regulação Bacteriana da Expressão Gênica , Prófagos/genética , Prófagos/patogenicidade , Estabilidade de RNA/genética , RNA AntissensoRESUMO
Bacillus subtilis possesses three essential enzymes thought to be involved in mRNA decay to varying degrees, namely RNase Y, RNase J1, and RNase III. Using recently developed high-resolution tiling arrays, we examined the effect of depletion of each of these enzymes on RNA abundance over the whole genome. The data are consistent with a model in which the degradation of a significant number of transcripts is dependent on endonucleolytic cleavage by RNase Y, followed by degradation of the downstream fragment by the 5'-3' exoribonuclease RNase J1. However, many full-size transcripts also accumulate under conditions of RNase J1 insufficiency, compatible with a model whereby RNase J1 degrades transcripts either directly from the 5' end or very close to it. Although the abundance of a large number of transcripts was altered by depletion of RNase III, this appears to result primarily from indirect transcriptional effects. Lastly, RNase depletion led to the stabilization of many low-abundance potential regulatory RNAs, both in intergenic regions and in the antisense orientation to known transcripts.
Assuntos
Bacillus subtilis , Regulação Bacteriana da Expressão Gênica , Estabilidade de RNA/genética , RNA Mensageiro , Ribonuclease III/genética , Bacillus subtilis/enzimologia , Genes Bacterianos , Genoma Bacteriano , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ribonuclease III/antagonistas & inibidoresRESUMO
The bacteriophage T4-encoded RegB endoribonuclease is produced during the early stage of phage development and targets mostly (but not exclusively) the Shine-Dalgarno sequences of early genes. In this work, we show that the degradation of RegB-cleaved mRNAs depends on a functional T4 polynucleotide kinase/phosphatase (PNK). The 5'-OH produced by RegB cleavage is phosphorylated by the kinase activity of PNK. This modification allows host RNases G and E, with activity that is strongly stimulated by 5'-monophosphate termini, to attack mRNAs from the 5'-end, causing their destabilization. The PNK-dependent pathway of degradation becomes effective 5 min postinfection, consistent with our finding that several minutes are required for PNK to accumulate after infection. Our work emphasizes the importance of the nature of the 5' terminus for mRNA stability and depicts a pathway of mRNA degradation with 5'- to 3'-polarity in cells devoid of 5'-3' exonucleases. It also ascribes a role for T4 PNK during normal phage development.
Assuntos
Bacteriófago T4/metabolismo , Polinucleotídeo 5'-Hidroxiquinase/metabolismo , RNA Mensageiro/metabolismo , RNA Viral/metabolismo , Bacteriófago T4/genética , Bacteriófago T4/crescimento & desenvolvimento , Sequência de Bases , Endorribonucleases/antagonistas & inibidores , Endorribonucleases/metabolismo , Proteínas de Escherichia coli/antagonistas & inibidores , Proteínas de Escherichia coli/metabolismo , Genes Virais , Interações Hospedeiro-Patógeno , Dados de Sequência Molecular , Polinucleotídeo 5'-Hidroxiquinase/antagonistas & inibidores , Estabilidade de RNA , RNA Mensageiro/genética , RNA Viral/genética , Proteínas Virais/genética , Proteínas Virais/metabolismoRESUMO
This study aimed to evaluate energy expenditure (EE) and heart rate (HR) response in kart pilots to successive driving bouts during a 24-hour team race. Eight adult male pilots (22.8 ± 4.1 years) participated to a team 24-hour speedway kart race in Le Mans (France). They alternatively piloted a 390 cm kart. Each relay was 45 minutes long and each pilot performed 4 relays. For each pilot, mean speeds were calculated from lap-to-lap duration recordings using a telemetric infrared timing device. Heart rate values were recorded continuously on 5-second intervals using a portable cardiometric device. Total energy expenditure (EET) and physical activity ratio (PAR) were determined by accelerometry. To pilot a kart during 45 minutes at a mean speed around 62 km·h induces a 300-kcal EET, corresponding to a 5.6-Mets PAR. This effort is responsive for a 73 b·min increase in HR, from 84.1 ± 7.6 to 157.4 ± 11.0 b·min (82% maximal heart rate intensity). However, during this relay period, HR values seemed independent to mean speed performance and bioenergetical values. Thus, in the context of the 24-hour team race, the variability in effort made during each relay and relay succession did not alter bioenergetical adaptation of pilots to kart driving. The high EE and HR values would be better explained by both emotional stress and environmental constraints such as speedway configuration and vibrations. The way how these factors specifically influence bioenergetical demand, and their relative importance, has to be specified to optimize training procedure and recommendations.
Assuntos
Adaptação Fisiológica , Metabolismo Energético/fisiologia , Frequência Cardíaca/fisiologia , Esportes/fisiologia , Adolescente , Humanos , Masculino , Adulto JovemRESUMO
OBJECTIVES: Endothelial function can be assessed by acetylcholine (ACh) iontophoresis with single current application. The effect of inter-electrode distance as well as electrical cutaneous resistance (ECR) on ACh dependent vasodilation has never been studied using single current application. The aims of this study are (i) to compare ACh-peak and ECR measured at different inter-electrode distances, (ii) to assess the relationship between ACh-peak and ECR, (iii) and to study the reproducibility of the ECR values. METHODS: Fourteen healthy subjects were included. Using laser speckle contrast imaging, ACh-iontophoreses (0.1 mA, 30s) were performed on the forearm at a 7-day interval with an inter-electrode distance set at 5 cm. Two other inter-electrode distances were also evaluated: 10 cm and 15 cm. ECR was measured during each ACh-iontophoresis as well as the ACh-peak. RESULTS: No statistical difference was found between the ACh-peak values obtained at 5 cm, 10 cm and 15 cm. ECRs were also not statistically different. An inverse relationship (r=-0.60) was found between the ACh-peak and ECR (p<0.05). The coefficient of variation of the inter-day reproducibility of the ECR values was 9.1% [6.5%-15.1%] with an intra-class-correlation coefficient of 0.93 [0.81-0.98]. CONCLUSION: Inter-electrode distance ranging from 5 cm to 15 cm changes neither the ACh-peak value nor the ECR value. ECR impacts ACh-peak values.
Assuntos
Acetilcolina/administração & dosagem , Endotélio Vascular/efeitos dos fármacos , Pele/irrigação sanguínea , Vasodilatação/efeitos dos fármacos , Vasodilatadores/administração & dosagem , Administração Cutânea , Adulto , Impedância Elétrica , Endotélio Vascular/fisiologia , Feminino , Voluntários Saudáveis , Humanos , Iontoforese , Masculino , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Adulto JovemRESUMO
The literature offers limited information on the effect of obesity on the rate of force development (RFD), a critical parameter for mobility in older adults. The objectives of this study were to explore the influence of obesity on the RFD in older adults and to examine the association between this neuromuscular parameter and walking speed. The participants (42 older adults) were classified into two groups: the control group (CG, n = 22; mean age = 81.13 ± 4.02 years; body mass index (BMI) = 25.13 ± 3.35 kg/m2), and the obese group (OG, n = 20; mean age = 77.71 ± 2.95 years; BMI = 34.46 ± 3.25 kg/m2). Walking speed (m/s) was measured using the 10 m walking test. Neuromuscular parameters of the plantar flexors were evaluated during a maximal voluntary contraction test using a dynamometer. The RFD was calculated from the linear slop of the force-time curve in the following two phases: from the onset of the contraction to 50 ms (RFD0-50) and from 100 to 200 ms (RFD100-200). The gait speed was lower in the OG compared to the CG (p < 0.001). The RFD50/100 and RFD100/200 were lower in the OG compared to the CG (p < 0.001). The RFD50/100 was found to be the predominant influencer on gait speed in the OG. In conclusion, obesity negatively impacts the RFD in older adults and RFD stands out as the primary factor among the studied parameters influencing gait speed.
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BACKGROUND: Excessive body weight is associated with gait alterations. In none of previous studies, body fat distribution has been considered as a factor that could change gait parameters and induce different neuromuscular adaptations. OBJECTIVE: This multicenter, analytical, and cross-sectional study aimed to investigate the influence of the body mass distribution on gait parameters and ankle muscle coactivation in obese individuals. METHODS: Three distinct groups were included in the study: a non-obese control group (CG, n = 15, average age = 32.8 ± 6.5 years, BMI = 21.4 ± 2.2 kg/m2), an obese-android group characterized by a Waist to Hip Ratio (WHR) greater than 1 (OAG, n = 15, age = 32.4 ± 3.9 years, BMI = 41.4 ± 3.9 kg/m2, WHR = 1.2 ± 0.2), and an obese-gynoid group with a WHR less than 1 (OGG, n = 15, age = 35.4 ± 4.1 years, BMI = 40.0 ± 5.7 kg/m2, WHR = 0.82 ± 0.3). All participants walked on an instrumented gait analysis treadmill at their self-selected walking speed for one minute. Spatiotemporal parameters, walking cycle phases, vertical ground reaction force (GRFv) and center of pressure (CoP) velocity were sampled from the treadmill software. Electromyography (EMG) activity of the gastrocnemius medialis (GM), the soleus (SOL) and tibialis anterior (TA) were collected during walking and used to calculate coactivation indexes (CI) between ankle plantar and dorsal flexors (GM/TA and SOL/TA) for the different walking cycle phases. RESULTS: Compared to OAG, OGG walked with shorter and larger strides, lower CoP velocity and GRFv. During the single support phase, SOL/TA coactivation was higher in OAG compared to OGG (p < .05). During the propulsion phase, SOL/TA coactivation was higher in OGG compared to OAG (p < .05). CONCLUSION: Gait parameters and ankle muscle coactivation in obese individuals seem to be strongly dependent on body mass distribution. From the biomechanical point of view, body mass distribution changes gait strategies in obese individuals inducing different neuromuscular adaptations during the single support and propulsion phases.
Assuntos
Tornozelo , Marcha , Humanos , Adulto , Estudos Transversais , Marcha/fisiologia , Caminhada/fisiologia , Músculo Esquelético/fisiologia , Eletromiografia , Obesidade , Fenômenos BiomecânicosRESUMO
The genes encoding the ribonucleases RNase J1 and RNase Y have long been considered essential for Bacillus subtilis cell viability, even before there was concrete knowledge of their function as two of the most important enzymes for RNA turnover in this organism. Here we show that this characterization is incorrect and that ΔrnjA and Δrny mutants are both viable. As expected, both strains grow relatively slowly, with doubling times in the hour range in rich medium. Knockout mutants have major defects in their sporulation and competence development programs. Both mutants are hypersensitive to a wide range of antibiotics and have dramatic alterations to their cell morphologies, suggestive of cell envelope defects. Indeed, RNase Y mutants are significantly smaller in diameter than wild-type strains and have a very disordered peptidoglycan layer. Strains lacking RNase J1 form long filaments in tight spirals, reminiscent of mutants of the actin-like proteins (Mre) involved in cell shape determination. Finally, we combined the rnjA and rny mutations with mutations in other components of the degradation machinery and show that many of these strains are also viable. The implications for the two known RNA degradation pathways of B. subtilis are discussed.
Assuntos
Bacillus subtilis/enzimologia , Proteínas de Bactérias/metabolismo , Ribonucleases/metabolismo , Bacillus subtilis/fisiologia , Bacillus subtilis/ultraestrutura , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Microscopia Eletrônica de Transmissão , Mutação , Ribonucleases/genéticaRESUMO
PURPOSE: Microcirculatory dysfunction plays a key role in the development of sepsis during which core temperature is often disturbed. Skin microvascular assessment using laser techniques has been suggested to evaluate microvascular dysfunction during sepsis, but skin microcirculation is also a major effector of human thermoregulation. Therefore we aimed to study the effect of skin temperature on endothelial- and non-endothelial microvascular responses. METHODS: Fifteen healthy participants were studied at different randomized ambient temperatures leading to low (28.0+/-2.0 °C), intermediate (31.6+/-2.1 °C), and high (34.1+/-1.3 °C) skin temperatures. We measured skin blood flow using laser speckle contrast imaging on the forearm in response to vasodilator microvascular tests: acetylcholine (ACh) iontophoresis, sodium nitroprussiate (SNP) iontophoresis, and post-occlusive reactive hyperemia (PORH). The results are expressed as absolute (laser speckle perfusion units, LSPU) or normalized values (cutaneous vascular conductance, CVC in LSPU/mmHg and multiple of baseline). RESULTS: Maximal vasodilation induced by these tests is modified by skin temperature. A low skin temperature induced a significant lower vasodilation for all microvascular tests when results are expressed either in absolute values or in CVC. For example, ACh peak was 57.6+/-19.6 LSPU, 66.8+/-22.2 LSPU and 88.5+/-13.0 LSPU for low, intermediate and high skin temperature respectively (p<0.05). When results are expressed in multiple of baseline, statistical difference disappeared. CONCLUSIONS: These results suggest that skin temperature has to be well controlled when performing microvascular assessments in order to avoid any bias. The effect of skin temperature can be corrected by expressing the results in multiple of baseline.
Assuntos
Endotélio/patologia , Temperatura Cutânea , Pele/patologia , Acetilcolina/química , Acetilcolina/farmacologia , Adulto , Velocidade do Fluxo Sanguíneo , Meios de Contraste/farmacologia , Feminino , Humanos , Hiperemia/metabolismo , Iontoforese/métodos , Masculino , Microcirculação , Nitroprussiato/farmacologia , Distribuição Aleatória , Temperatura , Fatores de Tempo , Adulto JovemRESUMO
This paper deals with the attitude estimation of a rigid body equipped with angular velocity sensors and reference vector sensors. A quaternion-based nonlinear observer is proposed in order to fuse all information sources and to obtain an accurate estimation of the attitude. It is shown that the observer error dynamics can be separated into two passive subsystems connected in "feedback". Then, this property is used to show that the error dynamics is input-to-state stable when the measurement disturbance is seen as an input and the error as the state. These results allow one to affirm that the observer is "robustly stable". The proposed observer is evaluated in real-time with the design and implementation of an Attitude and Heading Reference System (AHRS) based on low-cost MEMS (Micro-Electro-Mechanical Systems) Inertial Measure Unit (IMU) and magnetic sensors and a 16-bit microcontroller. The resulting estimates are compared with a high precision motion system to demonstrate its performance.
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An EPR spectrum or an EPR sinogram for imaging contains information about all the paramagnetic species that are in the analyzed sample. When only one species is present, an image of its spatial repartition can be reconstructed from the sinogram by using the well-known Filtered Back-Projection (FBP). However, in the case of several species, the FBP does not allow the reconstruction of the images of each species from a standard acquisition. One has to use for this spectral-spatial imaging whose acquisition can be very long. A new approach, based on Total Variation minimization, is proposed in order to efficiently extract the spatial repartitions of all the species present in a sample from standard imaging data and therefore drastically reduce the acquisition time. Experiments have been carried out on Tetrathiatriarylmethyl, nitroxide and DPPH.