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The rise of antibiotic resistance and declining discovery of new antibiotics has created a global health crisis. Of particular concern, no new antibiotic classes have been approved for treating Gram-negative pathogens in decades. Here, we characterize a compound, SCH-79797, that kills both Gram-negative and Gram-positive bacteria through a unique dual-targeting mechanism of action (MoA) with undetectably low resistance frequencies. To characterize its MoA, we combined quantitative imaging, proteomic, genetic, metabolomic, and cell-based assays. This pipeline demonstrates that SCH-79797 has two independent cellular targets, folate metabolism and bacterial membrane integrity, and outperforms combination treatments in killing methicillin-resistant Staphylococcus aureus (MRSA) persisters. Building on the molecular core of SCH-79797, we developed a derivative, Irresistin-16, with increased potency and showed its efficacy against Neisseria gonorrhoeae in a mouse vaginal infection model. This promising antibiotic lead suggests that combining multiple MoAs onto a single chemical scaffold may be an underappreciated approach to targeting challenging bacterial pathogens.
Assuntos
Bactérias Gram-Negativas/efeitos dos fármacos , Pirróis/metabolismo , Pirróis/farmacologia , Quinazolinas/metabolismo , Quinazolinas/farmacologia , Animais , Antibacterianos/farmacologia , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Feminino , Ácido Fólico/metabolismo , Bactérias Gram-Positivas/efeitos dos fármacos , Células HEK293 , Humanos , Masculino , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Ovariectomia , Proteômica , Pseudomonas aeruginosa/efeitos dos fármacosRESUMO
The epithelial-mesenchymal transition (EMT) has been associated with the acquisition of motility, invasiveness, and self-renewal traits. During both normal development and tumor pathogenesis, this change in cell phenotype is induced by contextual signals that epithelial cells receive from their microenvironment. The signals that are responsible for inducing an EMT and maintaining the resulting cellular state have been unclear. We describe three signaling pathways, involving transforming growth factor (TGF)-ß and canonical and noncanonical Wnt signaling, that collaborate to induce activation of the EMT program and thereafter function in an autocrine fashion to maintain the resulting mesenchymal state. Downregulation of endogenously synthesized inhibitors of autocrine signals in epithelial cells enables the induction of the EMT program. Conversely, disruption of autocrine signaling by added inhibitors of these pathways inhibits migration and self-renewal in primary mammary epithelial cells and reduces tumorigenicity and metastasis by their transformed derivatives.
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Comunicação Autócrina , Neoplasias da Mama/metabolismo , Mama/citologia , Células-Tronco Neoplásicas/metabolismo , Comunicação Parácrina , Células-Tronco/metabolismo , Animais , Proteínas Morfogenéticas Ósseas/metabolismo , Mama/metabolismo , Mama/patologia , Neoplasias da Mama/patologia , Movimento Celular , Células Epiteliais/metabolismo , Transição Epitelial-Mesenquimal , Feminino , Humanos , Glândulas Mamárias Animais/citologia , Glândulas Mamárias Animais/efeitos dos fármacos , Mesoderma/metabolismo , Camundongos , Transdução de Sinais , Fator de Crescimento Transformador beta/metabolismo , Proteínas Wnt/metabolismoRESUMO
Autism spectrum disorder (ASD) is a major neurodevelopmental disorder affecting 1 in 36 children in the United States. While neurons have been the focus of understanding ASD, an altered neuro-immune response in the brain may be closely associated with ASD, and a neuro-immune interaction could play a role in the disease progression. As the resident immune cells of the brain, microglia regulate brain development and homeostasis via core functions including phagocytosis of synapses. While ASD has been traditionally considered a polygenic disorder, recent large-scale human genetic studies have identified SCN2A deficiency as a leading monogenic cause of ASD and intellectual disability. We generated a Scn2a-deficient mouse model, which displays major behavioral and neuronal phenotypes. However, the role of microglia in this disease model is unknown. Here, we reported that Scn2a-deficient mice have impaired learning and memory, accompanied by reduced synaptic transmission and lower spine density in neurons of the hippocampus. Microglia in Scn2a-deficient mice are partially activated, exerting excessive phagocytic pruning of post-synapses related to the complement C3 cascades during selective developmental stages. The ablation of microglia using PLX3397 partially restores synaptic transmission and spine density. To extend our findings from rodents to human cells, we established a microglia-incorporated human cerebral organoid model carrying an SCN2A protein-truncating mutation identified in children with ASD. We found that human microglia display increased elimination of post-synapse in cerebral organoids carrying the SCN2A mutation. Our study establishes a key role of microglia in multi-species autism-associated models of SCN2A deficiency from mouse to human cells.
RESUMO
The histories of African crops remain poorly understood despite their contemporary importance. Integration of crops from western, eastern and northern Africa probably first occurred in the Great Lakes Region of eastern Africa; however, little is known about when and how these agricultural systems coalesced. This article presents archaeobotanical analyses from an approximately 9000-year archaeological sequence at Kakapel Rockshelter in western Kenya, comprising the largest and most extensively dated archaeobotanical record from the interior of equatorial eastern Africa. Direct radiocarbon dates on carbonized seeds document the presence of the West African crop cowpea (Vigna unguiculata (L.) Walp) approximately 2300 years ago, synchronic with the earliest date for domesticated cattle (Bos taurus). Peas (Pisum sativum L. or Pisum abyssinicum A. Braun) and sorghum (Sorghum bicolor (L.) Moench) from the northeast and eastern African finger millet (Eleusine coracana (L.) Gaertn.) are incorporated later, by at least 1000 years ago. Combined with ancient DNA evidence from Kakapel and the surrounding region, these data support a scenario in which the use of diverse domesticated species in eastern Africa changed over time rather than arriving and being maintained as a single package. Findings highlight the importance of local heterogeneity in shaping the spread of food production in sub-Saharan Africa.
Assuntos
Agricultura , Arqueologia , Produtos Agrícolas , Quênia , Animais , Datação Radiométrica , África OrientalRESUMO
Folates enable the activation and transfer of one-carbon units for the biosynthesis of purines, thymidine and methionine. Antifolates are important immunosuppressive and anticancer agents. In proliferating lymphocytes and human cancers, mitochondrial folate enzymes are particularly strongly upregulated. This in part reflects the need for mitochondria to generate one-carbon units and export them to the cytosol for anabolic metabolism. The full range of uses of folate-bound one-carbon units in the mitochondrial compartment itself, however, has not been thoroughly explored. Here we show that loss of the catalytic activity of the mitochondrial folate enzyme serine hydroxymethyltransferase 2 (SHMT2), but not of other folate enzymes, leads to defective oxidative phosphorylation in human cells due to impaired mitochondrial translation. We find that SHMT2, presumably by generating mitochondrial 5,10-methylenetetrahydrofolate, provides methyl donors to produce the taurinomethyluridine base at the wobble position of select mitochondrial tRNAs. Mitochondrial ribosome profiling in SHMT2-knockout human cells reveals that the lack of this modified base causes defective translation, with preferential mitochondrial ribosome stalling at certain lysine (AAG) and leucine (UUG) codons. This results in the impaired expression of respiratory chain enzymes. Stalling at these specific codons also occurs in certain inborn errors of mitochondrial metabolism. Disruption of whole-cell folate metabolism, by either folate deficiency or antifolate treatment, also impairs the respiratory chain. In summary, mammalian mitochondria use folate-bound one-carbon units to methylate tRNA, and this modification is required for mitochondrial translation and thus oxidative phosphorylation.
Assuntos
Ácido Fólico/metabolismo , Mitocôndrias/metabolismo , Biossíntese de Proteínas , RNA de Transferência/química , RNA de Transferência/metabolismo , Aminoidrolases/metabolismo , Biocatálise , Proteínas de Transporte/metabolismo , Códon/genética , Transporte de Elétrons , Antagonistas do Ácido Fólico/farmacologia , Proteínas de Ligação ao GTP/metabolismo , Glicina Hidroximetiltransferase/deficiência , Glicina Hidroximetiltransferase/metabolismo , Guanosina/metabolismo , Células HCT116 , Células HEK293 , Humanos , Leucina/genética , Lisina/genética , Metilação/efeitos dos fármacos , Metilenotetra-Hidrofolato Desidrogenase (NADP)/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Enzimas Multifuncionais/metabolismo , Fosforilação Oxidativa/efeitos dos fármacos , RNA de Transferência/genética , Proteínas de Ligação a RNA , Ribossomos/metabolismo , Sarcosina/metabolismo , Tetra-Hidrofolatos/metabolismo , Nucleotídeos de Timina/biossínteseRESUMO
Despite the absence of a membrane-enclosed nucleus, the bacterial DNA is typically condensed into a compact body-the nucleoid. This compaction influences the localization and dynamics of many cellular processes including transcription, translation, and cell division. Here, we develop a model that takes into account steric interactions among the components of the Escherichia coli transcriptional-translational machinery (TTM) and out-of-equilibrium effects of messenger RNA (mRNA) transcription, translation, and degradation, to explain many observed features of the nucleoid. We show that steric effects, due to the different molecular shapes of the TTM components, are sufficient to drive equilibrium phase separation of the DNA, explaining the formation and size of the nucleoid. In addition, we show that the observed positioning of the nucleoid at midcell is due to the out-of-equilibrium process of mRNA synthesis and degradation: mRNAs apply a pressure on both sides of the nucleoid, localizing it to midcell. We demonstrate that, as the cell grows, the production of these mRNAs is responsible for the nucleoid splitting into two lobes and for their well-known positioning to 1/4 and 3/4 positions on the long cell axis. Finally, our model quantitatively accounts for the observed expansion of the nucleoid when the pool of cytoplasmic mRNAs is depleted. Overall, our study suggests that steric interactions and out-of-equilibrium effects of the TTM are key drivers of the internal spatial organization of bacterial cells.
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Escherichia coli/metabolismo , Polaridade Celular , Cromossomos Bacterianos/genética , Cromossomos Bacterianos/metabolismo , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Espaço Intracelular/genética , Espaço Intracelular/metabolismo , Modelos Biológicos , Biossíntese de Proteínas , RNA Bacteriano/genética , RNA Bacteriano/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ribossomos/metabolismo , Transcrição GênicaRESUMO
How well mRNA transcript levels represent protein abundances has been a controversial issue. Particularly across different environments, correlations between mRNA and protein exhibit remarkable variability from gene to gene. Translational regulation is likely to be one of the key factors contributing to mismatches between mRNA level and protein abundance in bacteria. Here, we quantified genome-wide transcriptome and relative translation efficiency (RTE) under 12 different conditions in Escherichia coli. By quantifying the mRNA-RTE correlation both across genes and across conditions, we uncovered a diversity of gene-specific translational regulations, cooperating with transcriptional regulations, in response to carbon (C), nitrogen (N), and phosphate (P) limitations. Intriguingly, we found that many genes regulating translation are themselves subject to translational regulation, suggesting possible feedbacks. Furthermore, a random forest model suggests that codon usage partially predicts a gene's cross-condition variability in translation efficiency; such cross-condition variability tends to be an inherent quality of a gene, independent of the specific nutrient limitations. These findings broaden the understanding of translational regulation under different environments and provide novel strategies for the control of translation in synthetic biology. In addition, our data offers a resource for future multi-omics studies.
Assuntos
Proteínas de Escherichia coli , Escherichia coli , Escherichia coli/metabolismo , Biossíntese de Proteínas , Proteínas de Escherichia coli/metabolismo , RNA Mensageiro/genética , ProteômicaRESUMO
PURPOSE: To compare the efficacy of conventional laser and subthreshold micropulse laser (SML) in treating diabetic macular edema in terms of functional outcomes and changes in quantitative metrics for the retinal capillary and choriocapillary vascular layers. METHODS: Fifty-two eyes from 52 patients with treatment-naive, clinically significant macular edema were randomly assigned to the conventional laser group or SML group in a 1:1 ratio. Best-corrected visual acuity, central macular thickness (CMT), and optical coherence tomography angiography scans were measured at baseline, 1, 3, and 6 months after treatment. RESULTS: The SML group showed rapid visual recovery, improving from baseline of 0.320 ± 0.31 logarithm of the minimum angle of resolution (20/42 Snellen) to 0.270 ± 0.22 logarithm of the minimum angle of resolution (20/37 Snellen) at 1 month ( P = 0.038) and had significant improvements in CMT at 6-month post-treatment (353.88-301.00 µ m, P = 0.005). Statistically significant changes were detected across all optical coherence tomography angiography metrics, including vessel density, vessel length density, vessel diameter index, and fractal dimension, at 6 months for both groups in the deep capillary plexus and choriocapillary plexus. CONCLUSION: Subthreshold micropulse laser resulted in early visual recovery and sustained macular thickness improvement in the treatment of diabetic macular edema. Microvascular perfusion parameters, including vessel density, vessel length density, and fractal dimension, improved in the deep capillary plexus and choriocapillary plexus for both treatment groups at 6 months post-treatment.
Assuntos
Diabetes Mellitus , Retinopatia Diabética , Edema Macular , Humanos , Edema Macular/diagnóstico , Edema Macular/cirurgia , Retinopatia Diabética/diagnóstico , Retinopatia Diabética/cirurgia , Tomografia de Coerência Óptica , Fotocoagulação a Laser/métodos , Retina/cirurgia , Angiografia , Lasers Semicondutores , Resultado do TratamentoRESUMO
Axial tibial rotation is a characteristic motion of the knee, but how it occurs with knee flexion is controversial. We investigated the mechanisms of tibial rotations by analyzing in vivo tibiofemoral articulations. Twenty knees of 20 living human subjects were investigated during a weightbearing flexion from full extension to maximal flexion using a dual fluoroscopic imaging system. Tibiofemoral articular contact motions on medial and lateral femoral condyles and tibial surfaces were measured at flexion intervals of 15 deg from 0 deg to 120 deg. Axial tibial rotations due to the femoral and tibial articular motions were compared. Articular contact distances were longer on femoral condyles than on tibial surfaces at all flexion intervals (p < 0.05). The articular distance on medial femoral condyle is longer than on lateral side during flexion up to 60 deg. The internal tibial rotation was 6.8 ± 4.5 deg (Mean ± SD) at the flexion interval of 0-15 deg, where 6.1 ± 2.6 deg was due to articulations on femoral condyles and 0.7 ± 5.1 deg due to articulations on tibial surfaces (p < 0.05). The axial tibial rotations due to articulations on femoral condyles are significantly larger than those on tibial surfaces until 60 deg of flexion (p < 0.05). Minimal additional axial tibial rotations were observed beyond 60 deg of flexion. The axial tibial rotations were mainly attributed to uneven articulations on medial and lateral femoral condyles. These data can provide new insights into the understanding of mechanisms of axial tibial rotations and serve as baseline knowledge for improvement of knee surgeries.
Assuntos
Articulação do Joelho , Prótese do Joelho , Humanos , Fenômenos Biomecânicos , Articulação do Joelho/fisiologia , Tíbia/fisiologia , Fêmur/fisiologia , Amplitude de Movimento Articular , Suporte de Carga/fisiologia , RotaçãoRESUMO
Dual-degree MD-PhD programs have historically lacked diversity of race, ethnicity, gender, sexual orientation, and other facets of identity. Like MD- and PhD-granting programs, MD-PhD program training environments are also marked by structural barriers that negatively impact measurable academic outcomes of underrepresented and/or marginalized students in academic medicine (racial and ethnic minority groups considered underrepresented by the National Institute of Health, sexual and gender minorities, individuals with disabilities, and individuals of low socioeconomic status). In this article, we review the existing literature on MD-PhD program disparities affecting students from these groups and provide recommendations grounded on the reviewed evidence. Our literature review identified four generalizable barriers that can impact the training outcomes of students from these marginalized and/or underrepresented groups: 1) discrimination and bias, 2) impostor syndrome and stereotype threat, 3) lack of identity-similar mentors, and 4) suboptimal institutional policies and procedures. We propose goal-oriented interventions that may begin to ameliorate the disparities present in MD-PhD program training environments that affect students from marginalized and/or underrepresented groups in academic medicine.
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Pesquisa Biomédica , Medicina , Humanos , Masculino , Feminino , Etnicidade , Grupos Minoritários , Estudantes , Mentores , Pesquisa Biomédica/educaçãoRESUMO
PURPOSE: The purpose of the study was to describe the cases of intraocular inflammation following COVID-19 vaccination (Comirnaty mRNA vaccine and CoronaVac vaccine) in Hong Kong. METHODS: This was a retrospective case series. RESULTS: This series includes 16 eyes among 10 female patients, with a mean age of 49.4 ± 17.4 years. Eight patients (80%) received the Pfizer-BioNTech mRNA vaccination. Anterior uveitis was the most common presentation of postvaccination uveitis (50%) observed in our series, followed by intermediate uveitis (30%) and posterior uveitis (20%), respectively. A case of retinal vasculitis in the form of frosted branch angiitis, previously only reported following COVID-19 infection, was observed following COVID-19 vaccination. The median time from vaccination to uveitis onset was 15.2 days (range: 0-6 weeks). Inflammation in 11 out 16 eyes (68.75%) was completely resolved with topical steroids. CONCLUSION: Anterior uveitis was the predominant presentations of uveitis flare-ups following COVID-19 in our case series, followed by intermediate uveitis. Aligning with the current global literature concerning this issue, most of the uveitis attacks presented as anterior uveitis and were completely resolved with topical steroids. Consequently, the risk of uveitis flare-ups should not deter the public from receiving COVID-19 vaccines.
Assuntos
COVID-19 , Uveíte Anterior , Uveíte Intermediária , Uveíte , Humanos , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Vacinas contra COVID-19/efeitos adversos , Estudos Retrospectivos , COVID-19/prevenção & controle , Uveíte/diagnóstico , Uveíte/etiologia , Inflamação/etiologia , Uveíte Anterior/diagnóstico , Uveíte Anterior/etiologia , Vacinação/efeitos adversosRESUMO
BACKGROUND: Non-pharmaceutical interventions (NPIs) are recommended for COVID-19 prevention. However, the effectiveness of NPIs in preventing SARS-CoV-2 transmission remains poorly quantified. METHODS: We conducted a test-negative design case-control study enrolling cases (testing positive for SARS-CoV-2) and controls (testing negative) with molecular SARS-CoV-2 diagnostic test results reported to California Department of Public Health between 24 February-12 November, 2021. We used conditional logistic regression to estimate adjusted odds ratios (aORs) of case status among participants who reported contact with an individual known or suspected to have been infected with SARS-CoV-2 ("high-risk exposure") ≤14 days before testing. RESULTS: 751 of 1448 cases (52%) and 255 of 1443 controls (18%) reported high-risk exposures ≤14 days before testing. Adjusted odds of case status were 3.02-fold (95% confidence interval: 1.75-5.22) higher when high-risk exposures occurred with household members (vs. other contacts), 2.10-fold (1.05-4.21) higher when exposures occurred indoors (vs. outdoors only), and 2.15-fold (1.27-3.67) higher when exposures lasted ≥3 hours (vs. shorter durations) among unvaccinated and partially-vaccinated individuals; excess risk associated with such exposures was mitigated among fully-vaccinated individuals. Cases were less likely than controls to report mask usage during high-risk exposures (aOR = 0.50 [0.29-0.85]). The adjusted odds of case status was lower for fully-vaccinated (aOR = 0.25 [0.15-0.43]) participants compared to unvaccinated participants. Benefits of mask usage were greatest among unvaccinated and partially-vaccinated participants, and in interactions involving non-household contacts or interactions occurring without physical contact. CONCLUSIONS: NPIs reduced the likelihood of SARS-CoV-2 infection following high-risk exposure. Vaccine effectiveness was substantial for partially and fully vaccinated persons.
Assuntos
COVID-19 , COVID-19/epidemiologia , COVID-19/prevenção & controle , Estudos de Casos e Controles , Humanos , SARS-CoV-2RESUMO
Attention and working memory (WM) have classically been considered as two separate cognitive functions, but more recent theories have conceptualized them as operating on shared representations and being distinguished primarily by whether attention is directed internally (WM) or externally (attention, traditionally defined). Supporting this idea, a recent behavioral study documented a "WM Stroop effect," showing that maintaining a color word in WM impacts perceptual color-naming performance to the same degree as presenting the color word externally in the classic Stroop task. Here, we employed ERPs to examine the neural processes underlying this WM Stroop task compared to those in the classic Stroop and in a WM-control task. Based on the assumption that holding a color word in WM would (pre-)activate the same color representation as by externally presenting that color word, we hypothesized that the neural cascade of conflict-control processes would occur more rapidly in the WM Stroop than in the classic Stroop task. Our behavioral results replicated equivalent interference behavioral effects for the WM and classic Stroop tasks. Importantly, however, the ERP signatures of conflict detection and resolution displayed substantially shorter latencies in the WM Stroop task. Moreover, delay-period conflict in the WM Stroop task, but not in the WM control task, impacted the ERP and performance measures for the WM probe stimuli. Together, these findings provide new insights into how the brain processes conflict between internal representations and external stimuli, and they support the view of shared representations between internally held WM content and attentional processing of external stimuli.
Assuntos
Atenção , Memória de Curto Prazo , Potenciais Evocados , Humanos , Tempo de Reação , Teste de StroopRESUMO
Glycolysis plays a central role in producing ATP and biomass. Its control principles, however, remain incompletely understood. Here, we develop a method that combines 2H and 13C tracers to determine glycolytic thermodynamics. Using this method, we show that, in conditions and organisms with relatively slow fluxes, multiple steps in glycolysis are near to equilibrium, reflecting spare enzyme capacity. In Escherichia coli, nitrogen or phosphorus upshift rapidly increases the thermodynamic driving force, deploying the spare enzyme capacity to increase flux. Similarly, respiration inhibition in mammalian cells rapidly increases both glycolytic flux and the thermodynamic driving force. The thermodynamic shift allows flux to increase with only small metabolite concentration changes. Finally, we find that the cellulose-degrading anaerobe Clostridium cellulolyticum exhibits slow, near-equilibrium glycolysis due to the use of pyrophosphate rather than ATP for fructose-bisphosphate production, resulting in enhanced per-glucose ATP yield. Thus, near-equilibrium steps of glycolysis promote both rapid flux adaptation and energy efficiency.
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Metabolismo Energético/fisiologia , Glicólise , Animais , Linhagem Celular , Clostridium acetobutylicum , Clostridium cellulolyticum , Escherichia coli/classificação , Escherichia coli/metabolismo , Glucose/metabolismo , Homeostase , Camundongos , Nitrogênio , Proteína X Associada a bcl-2/genética , Proteína X Associada a bcl-2/metabolismoRESUMO
Infection is the predominant cause of mortality in early life, and immunization is the most promising biomedical intervention to reduce this burden. However, very young infants fail to respond optimally to most vaccines currently in use, especially neonates. In 2005, Stanley Plotkin proposed that new delivery systems would spur a new revolution in pediatric vaccinology, just as attenuation, inactivation, cell culture of viruses, genetic engineering, and adjuvantation had done in preceding decades. Recent advances in the field of immunoengineering, which is evolving alongside vaccinology, have begun to increasingly influence vaccine formulation design. Historically, the particulate nature of materials used in many vaccine formulations was empiric, often because of the need to stabilize antigens or reduce endotoxin levels. However, present vaccine delivery systems are rationally engineered to mimic the size, shape, and surface chemistry of pathogens, and are therefore often referred to as "pathogen-like particles". More than a decade from his original assessment, we re-assess Plotkin's prediction. In addition, we highlight how immunoengineering and advanced delivery systems may be uniquely capable of enhancing vaccine responses in vulnerable populations, such as infants. IMPACT: Immunoengineering and advanced delivery systems are leading to new developments in pediatric vaccinology. Summarizes delivery systems currently in use and development, and prospects for the future. Broad overview of immunoengineering's impact on vaccinology, catering to Pediatric Clinicians and Immunologists.
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Engenharia Genética , Vacinação/métodos , Vacinas/administração & dosagem , Criança , Humanos , Vacinas/imunologiaRESUMO
Microbes face intense competition in the natural world, and so need to wisely allocate their resources to multiple functions, in particular to metabolism. Understanding competition among metabolic strategies that are subject to trade-offs is therefore crucial for deeper insight into the competition, cooperation, and community assembly of microorganisms. In this work, we evaluate competing metabolic strategies within an ecological context by considering not only how the environment influences cell growth, but also how microbes shape their chemical environment. Utilizing chemostat-based resource-competition models, we exhibit a set of intuitive and general procedures for assessing metabolic strategies. Using this framework, we are able to relate and unify multiple metabolic models, and to demonstrate how the fitness landscape of strategies becomes intrinsically dynamic due to species-environment feedback. Such dynamic fitness landscapes produce rich behaviors, and prove to be crucial for ecological and evolutionarily stable coexistence in all the models we examined.
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Bactérias/metabolismo , Reatores Biológicos , Modelos Biológicos , Fenômenos BioquímicosRESUMO
PURPOSE: Retinal nerve fiber/ganglion cell layer (RNFL/GCL) thickness measured using optical coherence tomography has been proposed as an ocular biomarker for children with attention-deficit/hyperactivity disorder (ADHD), but findings varied in different studies. This study aims to determine the association between RNFL/GCL thickness and ADHD in children by systematic review and meta-analysis. METHODS: We performed a literature search in Embase, PubMed, Medline, Web of Science, and PsycINFO for relevant articles published up to February 29, 2020. All studies with original data comparing RNFL/GCL thickness in ADHD and healthy children were included. The Newcastle Ottawa Scale was used to assess bias risk and quality of evidence. Pooled estimates of the differences in thickness of RNFL or GCL between ADHD and healthy subjects were generated using meta-analysis with a random-effect model due to significant inter-study heterogeneity. Sensitivity analysis was also performed. RESULTS: We identified four eligible studies involving a total of 164 ADHD and 150 control subjects. Meta-analysis revealed that ADHD in children was associated with a reduction in global RNFL thickness (SMD, - 0.23; 95% CI - 0.46, - 0.01; p = 0.04). The global GCL thickness was examined in two studies with 89 ADHD and 75 control subjects, but the pooled difference in global GCL thickness between ADHD children and controls was not statistically significant (SMD, - 0.34; 95% CI - 1.25, 0.58; p = 0.47). CONCLUSION: Existing evidence suggests a possible association between ADHD and RNFL thinning in children. In view of the limited number of reports, further studies in large cohorts should be warranted.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade , Humanos , Fibras Nervosas , Retina , Células Ganglionares da Retina , Tomografia de Coerência ÓpticaRESUMO
The enzyme serine hydroxymethyltransferse (SHMT) converts serine into glycine and a tetrahydrofolate-bound one-carbon unit. Folate one-carbon units support purine and thymidine synthesis, and thus cell growth. Mammals have both cytosolic SHMT1 and mitochondrial SHMT2, with the mitochondrial isozyme strongly up-regulated in cancer. Here we show genetically that dual SHMT1/2 knockout blocks HCT-116 colon cancer tumor xenograft formation. Building from a pyrazolopyran scaffold that inhibits plant SHMT, we identify small-molecule dual inhibitors of human SHMT1/2 (biochemical IC50 â¼ 10 nM). Metabolomics and isotope tracer studies demonstrate effective cellular target engagement. A cancer cell-line screen revealed that B-cell lines are particularly sensitive to SHMT inhibition. The one-carbon donor formate generally rescues cells from SHMT inhibition, but paradoxically increases the inhibitor's cytotoxicity in diffuse large B-cell lymphoma (DLBCL). We show that this effect is rooted in defective glycine uptake in DLBCL cell lines, rendering them uniquely dependent upon SHMT enzymatic activity to meet glycine demand. Thus, defective glycine import is a targetable metabolic deficiency of DLBCL.
Assuntos
Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Glicina Hidroximetiltransferase/antagonistas & inibidores , Glicina/metabolismo , Linfoma Difuso de Grandes Células B/tratamento farmacológico , Linfoma Difuso de Grandes Células B/metabolismo , Animais , Sítios de Ligação , Linhagem Celular Tumoral , Inibidores Enzimáticos/química , Feminino , Deleção de Genes , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Camundongos Nus , Modelos Moleculares , Estrutura Molecular , Neoplasias Experimentais/metabolismo , Conformação ProteicaRESUMO
Proteolysis associated with recombinant protein expression in Chinese Hamster Ovary (CHO) cells has hindered the development of biologics including HIV vaccines. When expressed in CHO cells, the recombinant HIV envelope protein, gp120, undergoes proteolytic clipping by a serine protease at a key epitope recognized by neutralizing antibodies. The problem is particularly acute for envelope proteins from clade B viruses that represent the major genetic subtype circulating in much of the developed world, including the US and Europe. In this paper, we have identified complement Component 1's (C1s), a serine protease from the complement cascade, as the protease responsible for the proteolysis of gp120 in CHO cells. CRISPR/Cas9 knockout of the C1s protease in a CHO cell line was shown to eliminate the proteolytic activity against the recombinantly expressed gp120. In addition, the C1s-/- MGAT1- CHO cell line, with the C1s protease and the MGAT1 glycosyltransferase knocked out, enabled the production of unclipped gp120 from a clade B isolate (BaL-rgp120) and enriched for mannose-5 glycans on gp120 that are required for the binding of multiple broadly neutralizing monoclonal antibodies (bN-mAbs). The availability of this technology will allow for the scale-up and testing of multiple vaccine concepts in regions of the world where clade B viruses are in circulation. Furthermore, the proteolysis issues caused by the C1s protease suggests a broader need for a C1s-deficient CHO cell line to express other recombinant proteins that are susceptible to serine protease activity in CHO cells. Similarly, the workflow described here to identify and knockout C1s in a CHO cell line can be applied to remedy the proteolysis of biologics by other CHO proteases.
Assuntos
Sistemas CRISPR-Cas , Complemento C1s/genética , Complemento C1s/metabolismo , Técnicas de Inativação de Genes , Proteína gp120 do Envelope de HIV/biossíntese , HIV-1 , Proteólise , Animais , Células CHO , Cricetulus , Proteína gp120 do Envelope de HIV/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genéticaRESUMO
BACKGROUND: This study aims to study prospectively specific sleep patterns and risk of ADHD after adjusting for potential confounders such as obstructive sleep apnoea (OSA) and methylphenidate use. METHODS: A population-representative sample of 514 Chinese preschool children was recruited when in kindergarten (K3). Parents reported on their socioeconomic status and children's sleep duration. The cohort was reassessed 3 years later when the children were in Grade 3 (P3). Parents reported on children's sleep patterns and ADHD symptoms. Information on OSA diagnosis and methylphenidate use was retrieved from health records. RESULTS: Among the 514 parent-child dyads (mean [SD] age, 5.52 [0.33] years), 411 were reassessed (80.0% retention; 9.35 [0.33] years) at follow-up. There were no significant baseline differences between follow-up and drop-out groups. A gradient relationship was observed between probable ADHD in P3 and sleep duration in K3. The risk of probable ADHD was 15.5 per 100 for children with <8 h of sleep in K3, whereas it was 1.1 per 100 for children with 11-12 h of sleep in K3. The adjusted risk ratio was 14.19 (p = 0.02). CONCLUSIONS: Sleep deprivation in early childhood is associated with higher risk of ADHD in middle childhood.