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1.
Cell ; 176(5): 1174-1189.e16, 2019 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-30686580

RESUMO

The specific patterns and functional properties of electrical synapses of a nervous system are defined by the neuron-specific complement of electrical synapse constituents. We systematically examined the molecular composition of the electrical connectome of the nematode C. elegans through a genome- and nervous-system-wide analysis of the expression patterns of the invertebrate electrical synapse constituents, the innexins. We observe highly complex combinatorial expression patterns throughout the nervous system and found that these patterns change in a strikingly neuron-type-specific manner throughout the nervous system when animals enter an insulin-controlled diapause arrest stage under harsh environmental conditions, the dauer stage. By analyzing several individual synapses, we demonstrate that dauer-specific electrical synapse remodeling is responsible for specific aspects of the altered locomotory and chemosensory behavior of dauers. We describe an intersectional gene regulatory mechanism involving terminal selector and FoxO transcription factors mediating dynamic innexin expression plasticity in a neuron-type- and environment-specific manner.


Assuntos
Caenorhabditis elegans/fisiologia , Sinapses Elétricas/metabolismo , Plasticidade Neuronal/fisiologia , Animais , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Conectoma/métodos , Regulação da Expressão Gênica no Desenvolvimento/genética , Larva/metabolismo , Neurônios/metabolismo , Transdução de Sinais , Sinapses/metabolismo , Fatores de Transcrição/metabolismo
2.
Cell ; 147(4): 881-92, 2011 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-22078884

RESUMO

Spatial and temporal expression of specific basic-helix-loop-helix (bHLH) transcription factors defines many types of cellular differentiation. We find that a distinct mechanism regulates the much broader expression of the heterodimer partners of these specific factors and impinges on differentiation. In Drosophila, a cross-interacting regulatory network links expression of the E protein Daughterless (Da), which heterodimerizes with bHLH proteins to activate them, with expression of the Id protein Extramacrochaetae (Emc), which antagonizes bHLH proteins. Coupled transcriptional feedback loops maintain the widespread Emc expression that restrains Da expression, opposing bHLH-dependent differentiation while enhancing growth and cell survival. Where extracellular signals repress emc, Da expression can increase. This defines regions of proneural ectoderm independently from the proneural bHLH genes. Similar regulation is found in multiple Drosophila tissues and in mammalian cells and therefore is likely to be a conserved general feature of developmental regulation by HLH proteins.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Redes Reguladoras de Genes , Animais , Linhagem Celular , Drosophila melanogaster/metabolismo , Olho/embriologia , Humanos , Proteína 1 Inibidora de Diferenciação/metabolismo , Neurogênese , Proteínas Repressoras/metabolismo , Transdução de Sinais , Fator 3 de Transcrição/metabolismo , Transcrição Gênica
3.
PLoS Genet ; 18(12): e1010407, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36508468

RESUMO

During meiosis, recombination between homologous chromosomes (homologs) generates crossovers that promote proper segregation at the first meiotic division. Recombination is initiated by Spo11-catalyzed DNA double strand breaks (DSBs). 5' end resection of the DSBs creates 3' single strand tails that two recombinases, Rad51 and Dmc1, bind to form presynaptic filaments that search for homology, mediate strand invasion and generate displacement loops (D-loops). D-loop processing then forms crossover and non-crossover recombinants. Meiotic recombination occurs in two temporally distinct phases. During Phase 1, Rad51 is inhibited and Dmc1 mediates the interhomolog recombination that promotes homolog synapsis. In Phase 2, Rad51 becomes active and functions with Rad54 to repair residual DSBs, making increasing use of sister chromatids. The transition from Phase 1 to Phase 2 is controlled by the meiotic recombination checkpoint through the meiosis-specific effector kinase Mek1. This work shows that constitutive activation of Rad51 in Phase 1 results in a subset of DSBs being repaired by a Rad51-mediated interhomolog recombination pathway that is distinct from that of Dmc1. Strand invasion intermediates generated by Rad51 require more time to be processed into recombinants, resulting in a meiotic recombination checkpoint delay in prophase I. Without the checkpoint, Rad51-generated intermediates are more likely to involve a sister chromatid, thereby increasing Meiosis I chromosome nondisjunction. This Rad51 interhomolog recombination pathway is specifically promoted by the conserved 5'-3' helicase PIF1 and its paralog, RRM3 and requires Pif1 helicase activity and its interaction with PCNA. This work demonstrates that (1) inhibition of Rad51 during Phase 1 is important to prevent competition with Dmc1 for DSB repair, (2) Rad51-mediated meiotic recombination intermediates are initially processed differently than those made by Dmc1, and (3) the meiotic recombination checkpoint provides time during prophase 1 for processing of Rad51-generated recombination intermediates.


Assuntos
DNA Helicases , Meiose , Rad51 Recombinase , Recombinação Genética , Proteínas de Saccharomyces cerevisiae , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , DNA Helicases/genética , DNA Helicases/metabolismo , Reparo do DNA/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Meiose/genética , Rad51 Recombinase/genética , Rad51 Recombinase/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Recombinação Genética/genética
4.
PLoS Genet ; 18(9): e1010372, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36178933

RESUMO

Homeobox genes are prominent regulators of neuronal identity, but the extent to which their function has been probed in animal nervous systems remains limited. In the nematode Caenorhabditis elegans, each individual neuron class is defined by the expression of unique combinations of homeobox genes, prompting the question of whether each neuron class indeed requires a homeobox gene for its proper identity specification. We present here progress in addressing this question by extending previous mutant analysis of homeobox gene family members and describing multiple examples of homeobox gene function in different parts of the C. elegans nervous system. To probe homeobox function, we make use of a number of reporter gene tools, including a novel multicolor reporter transgene, NeuroPAL, which permits simultaneous monitoring of the execution of multiple differentiation programs throughout the entire nervous system. Using these tools, we add to the previous characterization of homeobox gene function by identifying neuronal differentiation defects for 14 homeobox genes in 24 distinct neuron classes that are mostly unrelated by location, function and lineage history. 12 of these 24 neuron classes had no homeobox gene function ascribed to them before, while in the other 12 neuron classes, we extend the combinatorial code of transcription factors required for specifying terminal differentiation programs. Furthermore, we demonstrate that in a particular lineage, homeotic identity transformations occur upon loss of a homeobox gene and we show that these transformations are the result of changes in homeobox codes. Combining the present with past analyses, 113 of the 118 neuron classes of C. elegans are now known to require a homeobox gene for proper execution of terminal differentiation programs. Such broad deployment indicates that homeobox function in neuronal identity specification may be an ancestral feature of animal nervous systems.


Assuntos
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Diferenciação Celular/genética , Proteínas de Ligação a DNA/genética , Emprego , Regulação da Expressão Gênica no Desenvolvimento , Genes Homeobox/genética , Neurônios/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
5.
PLoS Biol ; 19(4): e3001204, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33891586

RESUMO

Many cell types display the remarkable ability to alter their cellular phenotype in response to specific external or internal signals. Such phenotypic plasticity is apparent in the nematode Caenorhabditis elegans when adverse environmental conditions trigger entry into the dauer diapause stage. This entry is accompanied by structural, molecular, and functional remodeling of a number of distinct tissue types of the animal, including its nervous system. The transcription factor (TF) effectors of 3 different hormonal signaling systems, the insulin-responsive DAF-16/FoxO TF, the TGFß-responsive DAF-3/SMAD TF, and the steroid nuclear hormone receptor, DAF-12/VDR, a homolog of the vitamin D receptor (VDR), were previously shown to be required for entering the dauer arrest stage, but their cellular and temporal focus of action for the underlying cellular remodeling processes remained incompletely understood. Through the generation of conditional alleles that allowed us to spatially and temporally control gene activity, we show here that all 3 TFs are not only required to initiate tissue remodeling upon entry into the dauer stage, as shown before, but are also continuously required to maintain the remodeled state. We show that DAF-3/SMAD is required in sensory neurons to promote and then maintain animal-wide tissue remodeling events. In contrast, DAF-16/FoxO or DAF-12/VDR act cell-autonomously to control anatomical, molecular, and behavioral remodeling events in specific cell types. Intriguingly, we also uncover non-cell autonomous function of DAF-16/FoxO and DAF-12/VDR in nervous system remodeling, indicating the presence of several insulin-dependent interorgan signaling axes. Our findings provide novel perspectives into how hormonal systems control tissue remodeling.


Assuntos
Proteínas de Caenorhabditis elegans/fisiologia , Comunicação Celular/genética , Plasticidade Celular/genética , Fatores de Transcrição Forkhead/fisiologia , Receptores Citoplasmáticos e Nucleares/fisiologia , Animais , Animais Geneticamente Modificados , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Fatores de Transcrição Forkhead/genética , Regulação da Expressão Gênica no Desenvolvimento , Sistema Nervoso/crescimento & desenvolvimento , Sistema Nervoso/metabolismo , Especificidade de Órgãos/genética , Organogênese/genética , Comunicação Parácrina/genética , Receptores de Calcitriol/genética , Receptores de Calcitriol/fisiologia , Receptores Citoplasmáticos e Nucleares/genética , Células Receptoras Sensoriais/metabolismo , Células Receptoras Sensoriais/fisiologia , Transdução de Sinais/genética
6.
Med Teach ; 45(9): 1038-1046, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-36745733

RESUMO

BACKGROUND: Remote consulting has become part of the medical student clinical experience in primary care, but little research exists regarding the impact on learning. AIM: To describe the experiences of General Practitioner (GP) educators and medical students in using student-led remote consultations as an educational tool. METHOD: A qualitative, explorative study conducted at four UK medical schools. GP educators and medical students were purposively sampled and interviewed. RESULTS: Nine themes arose: practical application, autonomy, heuristics, safety, triage of undifferentiated patients, clinical reasoning, patient inclusion in student education, student-patient interaction, and student-doctor interaction. DISCUSSION: Remote consulting has become part of the clinical placement experience. This has been found to expose students to a wider variety of clinical presentations. Verbal communication, history-taking, triage, and clinical reasoning skills were practised through remote consulting, but examination skills development was lacking. Students found building rapport more challenging, although this was mitigated by having more time with patients. Greater clinical risk was perceived in remote consulting, which had potential to negatively impact students' psychological safety. Frequent debriefs could ameliorate this risk and positively impact student-doctor relationships. Student autonomy and independence increased due to greater participation and responsibility. Pre-selection of patients could be helpful but had potential to expose students to lower complexity patients.[Box: see text].


Assuntos
Educação de Graduação em Medicina , Estudantes de Medicina , Humanos , Aprendizagem , Pesquisa Qualitativa , Competência Clínica , Estudantes de Medicina/psicologia , Encaminhamento e Consulta
7.
Molecules ; 27(10)2022 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-35630684

RESUMO

Spent sulfite liquor (SSL) from softwood processing is rich in hemicellulose (acetyl galactoglucomannan, AcGGM), lignin, and lignin-derived compounds. We investigated the effect of sequential AcGGM purification on the enzymatic bioconversion of AcGGM. SSL was processed through three consecutive purification steps (membrane filtration, precipitation, and adsorption) to obtain AcGGM with increasing purity. Significant reduction (~99%) in lignin content and modest loss (~18%) of polysaccharides was observed during purification from the least pure preparation (UFR), obtained by membrane filtration, compared to the purest preparation (AD), obtained by adsorption. AcGGM (~14.5 kDa) was the major polysaccharide in the preparations; its enzymatic hydrolysis was assessed by reducing sugar and high-performance anion-exchange chromatography analysis. The hydrolysis of the UFR preparation with Viscozyme L or Trichoderma reesei ß-mannanase TrMan5A (1 mg/mL) resulted in less than ~50% bioconversion of AcGGM. The AcGGM in the AD preparation was hydrolyzed to a higher degree (~67% with TrMan5A and 80% with Viscozyme L) and showed the highest conversion rate. This indicates that SSL contains enzyme-inhibitory compounds (e.g., lignin and lignin-derived compounds such as lignosulfonates) which were successfully removed.


Assuntos
Lignina , Polissacarídeos , Hidrólise , Lignina/química , Sulfitos
8.
J Biol Chem ; 294(23): 9100-9117, 2019 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-31000630

RESUMO

The galactomannan utilization locus (BoManPUL) of the human gut bacterium Bacteroides ovatus encodes BoMan26B, a cell-surface-exposed endomannanase whose functional and structural features have been unclear. Our study now places BoMan26B in context with related enzymes and reveals the structural basis for its specificity. BoMan26B prefers longer substrates and is less restricted by galactose side-groups than the mannanase BoMan26A of the same locus. Using galactomannan, BoMan26B generated a mixture of (galactosyl) manno-oligosaccharides shorter than mannohexaose. Three defined manno-oligosaccharides had affinity for the SusD-like surface-exposed glycan-binding protein, predicted to be implicated in saccharide transport. Co-incubation of BoMan26B and the periplasmic α-galactosidase BoGal36A increased the rate of galactose release by about 10-fold compared with the rate without BoMan26B. The results suggested that BoMan26B performs the initial attack on galactomannan, generating oligosaccharides that after transport to the periplasm are processed by BoGal36A. A crystal structure of BoMan26B with galactosyl-mannotetraose bound in subsites -5 to -2 revealed an open and long active-site cleft with Trp-112 in subsite -5 concluded to be involved in mannosyl interaction. Moreover, Lys-149 in the -4 subsite interacted with the galactosyl side-group of the ligand. A phylogenetic tree consisting of GH26 enzymes revealed four strictly conserved GH26 residues and disclosed that BoMan26A and BoMan26B reside on two distinct phylogenetic branches (A and B). The three other branches contain lichenases, xylanases, or enzymes with unknown activities. Lys-149 is conserved in a narrow part of branch B, and Trp-112 is conserved in a wider group within branch B.


Assuntos
Proteínas de Bactérias/química , Bacteroides/metabolismo , beta-Manosidase/química , Proteínas de Bactérias/classificação , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Cálcio/metabolismo , Domínio Catalítico , Cristalografia por Raios X , Galactose/análogos & derivados , Cinética , Mananas/metabolismo , Simulação de Dinâmica Molecular , Mutagênese Sítio-Dirigida , Filogenia , Estabilidade Proteica , Especificidade por Substrato , beta-Manosidase/classificação , beta-Manosidase/genética , beta-Manosidase/metabolismo
9.
Dev Biol ; 431(2): 309-320, 2017 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-28919436

RESUMO

Notch regulates both neurogenesis and cell cycle activity to coordinate precursor cell generation in the differentiating Drosophila eye. Mosaic analysis with mitotic clones mutant for Notch components was used to identify the pathway of Notch signaling that regulates the cell cycle in the Second Mitotic Wave. Although S phase entry depends on Notch signaling and on the transcription factor Su(H), the transcriptional co-activator Mam and the bHLH repressor genes of the E(spl)-Complex were not essential, although these are Su(H) coactivators and targets during the regulation of neurogenesis. The Second Mitotic Wave showed little dependence on ubiquitin ligases neuralized or mindbomb, and although the ligand Delta is required non-autonomously, partial cell cycle activity occurred in the absence of known Notch ligands. We found that myc was not essential for the Second Mitotic Wave. The Second Mitotic Wave did not require the HLH protein Extra macrochaetae, and the bHLH protein Daughterless was required only cell-nonautonomously. Similar cell cycle phenotypes for Daughterless and Atonal were consistent with requirement for neuronal differentiation to stimulate Delta expression, affecting Notch activity in the Second Mitotic Wave indirectly. Therefore Notch signaling acts to regulate the Second Mitotic Wave without activating bHLH gene targets.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Mitose , Receptores Notch/metabolismo , Transdução de Sinais , Animais , Modelos Biológicos
10.
Development ; 141(2): 422-35, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24353061

RESUMO

Transcription factors that drive neuron type-specific terminal differentiation programs in the developing nervous system are often expressed in several distinct neuronal cell types, but to what extent they have similar or distinct activities in individual neuronal cell types is generally not well explored. We investigate this problem using, as a starting point, the C. elegans LIM homeodomain transcription factor ttx-3, which acts as a terminal selector to drive the terminal differentiation program of the cholinergic AIY interneuron class. Using a panel of different terminal differentiation markers, including neurotransmitter synthesizing enzymes, neurotransmitter receptors and neuropeptides, we show that ttx-3 also controls the terminal differentiation program of two additional, distinct neuron types, namely the cholinergic AIA interneurons and the serotonergic NSM neurons. We show that the type of differentiation program that is controlled by ttx-3 in different neuron types is specified by a distinct set of collaborating transcription factors. One of the collaborating transcription factors is the POU homeobox gene unc-86, which collaborates with ttx-3 to determine the identity of the serotonergic NSM neurons. unc-86 in turn operates independently of ttx-3 in the anterior ganglion where it collaborates with the ARID-type transcription factor cfi-1 to determine the cholinergic identity of the IL2 sensory and URA motor neurons. In conclusion, transcription factors operate as terminal selectors in distinct combinations in different neuron types, defining neuron type-specific identity features.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Proteínas de Homeodomínio/genética , Neurônios/citologia , Neurônios/metabolismo , Neuropeptídeos/genética , Fatores do Domínio POU/genética , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/crescimento & desenvolvimento , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Diferenciação Celular/genética , Neurônios Colinérgicos/citologia , Neurônios Colinérgicos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Genes de Helmintos , Proteínas de Homeodomínio/metabolismo , Interneurônios/citologia , Interneurônios/metabolismo , Larva/citologia , Larva/crescimento & desenvolvimento , Larva/metabolismo , Neurogênese/genética , Neurônios/classificação , Neuropeptídeos/metabolismo , Fatores do Domínio POU/metabolismo , Neurônios Serotoninérgicos/citologia , Neurônios Serotoninérgicos/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
11.
Cochrane Database Syst Rev ; 7: CD011119, 2016 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-27409972

RESUMO

BACKGROUND: Routine outcome monitoring of common mental health disorders (CMHDs), using patient reported outcome measures (PROMs), has been promoted across primary care, psychological therapy and multidisciplinary mental health care settings, but is likely to be costly, given the high prevalence of CMHDs. There has been no systematic review of the use of PROMs in routine outcome monitoring of CMHDs across these three settings. OBJECTIVES: To assess the effects of routine measurement and feedback of the results of PROMs during the management of CMHDs in 1) improving the outcome of CMHDs; and 2) in changing the management of CMHDs. SEARCH METHODS: We searched the Cochrane Depression Anxiety and Neurosis group specialised controlled trials register (CCDANCTR-Studies and CCDANCTR-References), the Oxford University PROMS Bibliography (2002-5), Ovid PsycINFO, Web of Science, The Cochrane Library, and International trial registries, initially to 30 May 2014, and updated to 18 May 2015. SELECTION CRITERIA: We selected cluster and individually randomised controlled trials (RCTs) including participants with CMHDs aged 18 years and over, in which the results of PROMs were fed back to treating clinicians, or both clinicians and patients. We excluded RCTs in child and adolescent treatment settings, and those in which more than 10% of participants had diagnoses of eating disorders, psychoses, substance use disorders, learning disorders or dementia. DATA COLLECTION AND ANALYSIS: At least two authors independently identified eligible trials, assessed trial quality, and extracted data. We conducted meta-analysis across studies, pooling outcome measures which were sufficiently similar to each other to justify pooling. MAIN RESULTS: We included 17 studies involving 8787 participants: nine in multidisciplinary mental health care, six in psychological therapy settings, and two in primary care. Pooling of outcome data to provide a summary estimate of effect across studies was possible only for those studies using the compound Outcome Questionnaire (OQ-45) or Outcome Rating System (ORS) PROMs, which were all conducted in multidisciplinary mental health care or psychological therapy settings, because both primary care studies identified used single symptom outcome measures, which were not directly comparable to the OQ-45 or ORS.Meta-analysis of 12 studies including 3696 participants using these PROMs found no evidence of a difference in outcome in terms of symptoms, between feedback and no-feedback groups (standardised mean difference (SMD) -0.07, 95% confidence interval (CI) -0.16 to 0.01; P value = 0.10). The evidence for this comparison was graded as low quality however, as all included studies were considered at high risk of bias, in most cases due to inadequate blinding of assessors and significant attrition at follow-up.Quality of life was reported in only two studies, social functioning in one, and costs in none. Information on adverse events (thoughts of self-harm or suicide) was collected in one study, but differences between arms were not reported.It was not possible to pool data on changes in drug treatment or referrals as only two studies reported these. Meta-analysis of seven studies including 2608 participants found no evidence of a difference in management of CMHDs between feedback and no-feedback groups, in terms of the number of treatment sessions received (mean difference (MD) -0.02 sessions, 95% CI -0.42 to 0.39; P value = 0.93). However, the evidence for this comparison was also graded as low quality. AUTHORS' CONCLUSIONS: We found insufficient evidence to support the use of routine outcome monitoring using PROMs in the treatment of CMHDs, in terms of improving patient outcomes or in improving management. The findings are subject to considerable uncertainty however, due to the high risk of bias in the large majority of trials meeting the inclusion criteria, which means further research is very likely to have an important impact on the estimate of effect and is likely to change the estimate. More research of better quality is therefore required, particularly in primary care where most CMHDs are treated.Future research should address issues of blinding of assessors and attrition, and measure a range of relevant symptom outcomes, as well as possible harmful effects of monitoring, health-related quality of life, social functioning, and costs. Studies should include people treated with drugs as well as psychological therapies, and should follow them up for longer than six months.


Assuntos
Transtornos Mentais/terapia , Avaliação de Resultados da Assistência ao Paciente , Adulto , Idoso , Antipsicóticos/uso terapêutico , Retroalimentação , Feminino , Humanos , Masculino , Transtornos Mentais/psicologia , Pessoa de Meia-Idade , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Ideação Suicida
12.
Biotechnol Lett ; 37(6): 1117-29, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25656474

RESUMO

The complex structure of lignocellulose requires the involvement of a suite of lignocellulolytic enzymes for bringing about an effective de-polymerization. Cellulases and hemicellulases from both fungi and bacteria have been studied extensively. This review illustrates the mechanism of action of different cellulolytic and hemi-cellulolytic enzymes and their distinctive roles during hydrolysis. It also examines how different approaches can be used to improve the synergistic interaction between fungal and bacterial glycosyl hydrolases with a focus on fungal cellulases and bacterial hemicellulases. The approach entails the role of cellulosomes and their improvement through incorporation of novel enzymes and evaluates the recent break-through in the construction of designer cellulosomes and their extension towards improving fungal and bacterial synergy. The proposed approach also advocates the incorporation and cell surface display of designer cellulosomes on non-cellulolytic solventogenic strains along with the innovative application of combined cross-linked enzyme aggregates (combi-CLEAs) as an economically feasible and versatile tool for improving the synergistic interaction through one-pot cascade reactions.


Assuntos
Bactérias/enzimologia , Biocombustíveis , Celulases/metabolismo , Etanol/metabolismo , Fungos/enzimologia , Glicosídeo Hidrolases/metabolismo , Bactérias/metabolismo , Biotecnologia/métodos , Celulase/metabolismo , Fungos/metabolismo , Hidrólise , Polissacarídeos/metabolismo
13.
Photochem Photobiol Sci ; 13(12): 1719-29, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25314902

RESUMO

Moderate intensity SMF have been shown to act as a controller of the protic potential in the coherent milieu of the thylakoid membranes. SMF of the order of 60-500 mT induces memory-like effect in photosystem I (PSI, P723) emission with a correlated oscillation of photosystem II (PSII, P689) fluorescence emission at a temperature of 77 K. The observed magnetic perturbation that affects the thylakoid photon capture circuitry was also found to be associated with the bio-energetic machinery of the thylakoid membranes. At normal pH, SMF causes an enhancement of PSI fluorescence emission intensity (P723/P689 > 1), followed by a slow relaxation on the removal of SMF. The enhancement of the PSI fluorescence intensity also occurs under no-field condition, if either the pH of the medium is lowered, or protonophores, such as carbonyl cyanide chlorophenylhydrazine or nigericin are added (P723/P689≥ 2). If SMF was applied under such a low pH condition or in the presence of protonophore, a reverse effect, particularly, a reduction of the enhanced PSI emission was observed. Because SMF is essentially equivalent to a spin perturbation, the observed effects can be explained in terms of spin re-organization, illustrating a memory effect via membrane re-alignment and assembly. The mimicry of conventional uncouplers by SMF is also notable; the essential difference being the reversibility and manoeuvrability of the latter (SMF). Finally, the effect implies numerous possibilities of externally regulating the photon capture and proton circulation in the thylakoid membranes using controlled SMF.


Assuntos
Campos Magnéticos , Complexo de Proteína do Fotossistema I/química , Complexo de Proteína do Fotossistema II/química , Arachis , Fluorescência , Concentração de Íons de Hidrogênio , Cinética , Nigericina/química , Permeabilidade , Prótons , Análise Espectral , Temperatura , Tilacoides/química
14.
Appl Biochem Biotechnol ; 195(4): 2196-2215, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36129596

RESUMO

The current ongoing trend of dimension detection of medical images is one of the challenging areas which facilitates several improvements in accurate measuring of clinical imaging based on fractal dimension detection methodologies. For medical diagnosis of any infection, detection of dimension is one of the major challenges due to the fractal shape of the medical object. Significantly improved outcome indicates that the performance of fractal dimension detection techniques is better than that of other state-of-the-art methods to extract diagnostically significant information from clinical image. Among the fractal dimension detection methodologies, fractal geometry has developed an efficient tool in medical image investigation. In this paper, a novel methodology of fractal dimension detection of medical images is proposed based on the concept of box counting technique to evaluate the fractal dimension. The proposed method has been evaluated and compared to other state-of-the-art approaches, and the results of the proposed algorithm graphically justify the mathematical derivation of the box counting approach in terms of Hurst exponent.


Assuntos
Algoritmos , Fractais , Raios X
15.
Ann Inst Stat Math ; 64(4): 687-714, 2012 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-22984295

RESUMO

This article considers a broad class of kernel mixture density models on compact metric spaces and manifolds. Following a Bayesian approach with a nonparametric prior on the location mixing distribution, sufficient conditions are obtained on the kernel, prior and the underlying space for strong posterior consistency at any continuous density. The prior is also allowed to depend on the sample size n and sufficient conditions are obtained for weak and strong consistency. These conditions are verified on compact Euclidean spaces using multivariate Gaussian kernels, on the hypersphere using a von Mises-Fisher kernel and on the planar shape space using complex Watson kernels.

16.
Microorganisms ; 10(12)2022 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-36557749

RESUMO

ß-Mannan is abundant in the human diet and in hemicellulose derived from softwood. Linear or galactose-substituted ß-mannan-oligosaccharides (MOS/GMOSs) derived from ß-mannan are considered emerging prebiotics that could stimulate health-associated gut microbiota. However, the underlying mechanisms are not yet resolved. Therefore, this study investigated the cross-feeding and metabolic interactions between Bifidobacterium adolescentis ATCC 15703, an acetate producer, and Roseburia hominis A2-183 DSMZ 16839, a butyrate producer, during utilization of MOS/GMOSs. Cocultivation studies suggest that both strains coexist due to differential MOS/GMOS utilization, along with the cross-feeding of acetate from B. adolescentis E194a to R. hominis A2-183. The data suggest that R. hominis A2-183 efficiently utilizes MOS/GMOS in mono- and cocultivation. Notably, we observed the transcriptional upregulation of certain genes within a dedicated MOS/GMOS utilization locus (RhMosUL), and an exo-oligomannosidase (RhMan113A) gene located distally in the R. hominis A2-183 genome. Significantly, biochemical analysis of ß-1,4 mannan-oligosaccharide phosphorylase (RhMOP130A), α-galactosidase (RhGal36A), and exo-oligomannosidase (RhMan113A) suggested their potential synergistic role in the initial utilization of MOS/GMOSs. Thus, our results enhance the understanding of MOS/GMOS utilization by potential health-promoting human gut microbiota and highlight the role of cross-feeding and metabolic interactions between two secondary mannan degraders inhabiting the same ecological niche in the gut.

17.
Neurosurgery ; 90(6): 758-767, 2022 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-35343469

RESUMO

BACKGROUND: Accurate specimen analysis of skull base tumors is essential for providing personalized surgical treatment strategies. Intraoperative specimen interpretation can be challenging because of the wide range of skull base pathologies and lack of intraoperative pathology resources. OBJECTIVE: To develop an independent and parallel intraoperative workflow that can provide rapid and accurate skull base tumor specimen analysis using label-free optical imaging and artificial intelligence. METHODS: We used a fiber laser-based, label-free, nonconsumptive, high-resolution microscopy method (<60 seconds per 1 × 1 mm2), called stimulated Raman histology (SRH), to image a consecutive, multicenter cohort of patients with skull base tumor. SRH images were then used to train a convolutional neural network model using 3 representation learning strategies: cross-entropy, self-supervised contrastive learning, and supervised contrastive learning. Our trained convolutional neural network models were tested on a held-out, multicenter SRH data set. RESULTS: SRH was able to image the diagnostic features of both benign and malignant skull base tumors. Of the 3 representation learning strategies, supervised contrastive learning most effectively learned the distinctive and diagnostic SRH image features for each of the skull base tumor types. In our multicenter testing set, cross-entropy achieved an overall diagnostic accuracy of 91.5%, self-supervised contrastive learning 83.9%, and supervised contrastive learning 96.6%. Our trained model was able to segment tumor-normal margins and detect regions of microscopic tumor infiltration in meningioma SRH images. CONCLUSION: SRH with trained artificial intelligence models can provide rapid and accurate intraoperative analysis of skull base tumor specimens to inform surgical decision-making.


Assuntos
Neoplasias Encefálicas , Neoplasias Meníngeas , Neoplasias da Base do Crânio , Inteligência Artificial , Neoplasias Encefálicas/cirurgia , Humanos , Neoplasias Meníngeas/diagnóstico por imagem , Neoplasias Meníngeas/cirurgia , Imagem Óptica , Neoplasias da Base do Crânio/diagnóstico por imagem , Neoplasias da Base do Crânio/cirurgia
18.
Environ Sci Pollut Res Int ; 28(1): 1131-1140, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32833171

RESUMO

This study aimed to evaluate possible synergistic interactions on antimicrobial and antioxidant efficacy of clove and cinnamon oil components in combination and characterization of compounds responsible for synergistic interactions using TLC bioautography followed by checkerboard titration, isobologram analysis, and spectrometric characterization. Among the combinations tested, cinnamaldehyde from cinnamon oil and eugenol from clove oil in combination showed a synergistic antimicrobial interaction against foodborne microbes Listeria monocytogenes (fractional inhibitory concentration index (FICI): 0.31), Salmonella typhimurium (FICI: 0.41), and Aspergillus niger (FICI: 0.48), and synergistic antioxidant efficacy (combination index: 0.78) in in vitro model. Cinnamaldehyde/eugenol blend did not show any cytotoxic effect (IC50 > 1000 µg/ml) in human normal keratinocyte cell line. The results provide evidence that the cinnamaldehyde/eugenol blend may help in designing a more potent novel natural antimicrobial and antioxidant agent in food and pharmaceutical industries.


Assuntos
Anti-Infecciosos , Óleos Voláteis , Syzygium , Anti-Infecciosos/farmacologia , Antioxidantes/farmacologia , Cinnamomum zeylanicum , Humanos , Testes de Sensibilidade Microbiana , Óleos Voláteis/farmacologia
19.
Lancet Digit Health ; 3(9): e599-e611, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34446266

RESUMO

Artificial intelligence (AI) promises to change health care, with some studies showing proof of concept of a provider-level performance in various medical specialties. However, there are many barriers to implementing AI, including patient acceptance and understanding of AI. Patients' attitudes toward AI are not well understood. We systematically reviewed the literature on patient and general public attitudes toward clinical AI (either hypothetical or realised), including quantitative, qualitative, and mixed methods original research articles. We searched biomedical and computational databases from Jan 1, 2000, to Sept 28, 2020, and screened 2590 articles, 23 of which met our inclusion criteria. Studies were heterogeneous regarding the study population, study design, and the field and type of AI under study. Six (26%) studies assessed currently available or soon-to-be available AI tools, whereas 17 (74%) assessed hypothetical or broadly defined AI. The quality of the methods of these studies was mixed, with a frequent issue of selection bias. Overall, patients and the general public conveyed positive attitudes toward AI but had many reservations and preferred human supervision. We summarise our findings in six themes: AI concept, AI acceptability, AI relationship with humans, AI development and implementation, AI strengths and benefits, and AI weaknesses and risks. We suggest guidance for future studies, with the goal of supporting the safe, equitable, and patient-centred implementation of clinical AI.


Assuntos
Inteligência Artificial , Atitude Frente aos Computadores , Atitude Frente a Saúde , Pacientes/psicologia , Opinião Pública , Humanos
20.
J Agric Food Chem ; 69(12): 3617-3625, 2021 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-33724030

RESUMO

Effects of xylooligosaccharides (XOSs) as well as a mixture of XOS, inulin, oligofructose, and partially hydrolyzed guar gum (MIX) in mice fed a high-fat diet (HFD) were studied. Control groups were fed an HFD or a low-fat diet. Special attention was paid to the cecal composition of the gut microbiota and formation of short-chain fatty acids, but metabolic parameters were also documented. The XOS group had significantly higher cecum levels of acetic, propionic, and butyric acids than the HFD group, and the butyric acid content was higher in the XOS than in the MIX group. The cecum microbiota of the XOS group contained more Bifidobacteria, Lachnospiraceae, and S24-7 bacteria than the HFD group. A tendency of lower body weight gain was observed on comparing the XOS and HFD groups. In conclusion, the XOS was shown to be a promising prebiotic candidate. The fiber diversity in the MIX diet did not provide any advantages compared to the XOS diet.


Assuntos
Bifidobacterium , Dieta Hiperlipídica , Animais , Ácido Butírico , Dieta Hiperlipídica/efeitos adversos , Ácidos Graxos , Ácidos Graxos Voláteis , Glucuronatos , Camundongos , Oligossacarídeos
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