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1.
Microbiol Spectr ; : e0086124, 2024 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-39373496

RESUMO

Understanding factors influencing the composition and maintenance of beneficial host-associated microbial communities is central to understanding their ecological, evolutionary, and health consequences for hosts. Host immunity is often implicated as a regulator of these microbiota, but immunity may also play a disruptive role, with responses to infection perturbing beneficial communities. Such effects may be more prominent from innate immune responses, with more rapid-acting and often non-specific components, compared to adaptive responses. We investigated how upregulation of antibacterial immunity in the bumble bee Bombus impatiens affects its core gut microbiota, testing the hypothesis that immunity-induced perturbation impacts the microbiota structure. Freshly emerged adult bees were fed a microbiota inoculum before receiving a non-pathogenic immune stimulation injection. We quantified microbial communities using 16S rRNA amplicon sequencing and targeted quantitative PCR. Coarse community membership shows apparent robustness, but we find that immune stimulation alters the abundance of two core community members, Gilliamella and Snodgrassella. Moreover, a positive association in communities between these bacteria is perturbed following a Gram-negative challenge. The observed changes in the gut microbial community are suggestive of immune response-induced dysbiosis, linking ecological interactions across levels between hosts, their pathogens, and their beneficial gut microbiota. The potential for collateral perturbation of the natural gut microbiota following an innate immune response may contribute to immune costs, shaping the evolutionary optimization of immune investment depending on the ecological context. IMPORTANCE: Our work demonstrates how innate immunity may influence the host-associated microbiota. While previous work has demonstrated the role of adaptive immunity in regulating the microbiota, we show that stimulation of an innate immune response in bumble bees may disrupt the native gut microbial community by shifting individual abundances of some members and pairwise associations. This work builds upon previous work in bumble bees demonstrating factors determining microbe colonization of hosts and microbiota membership, implicating immune response-induced changes as a factor shaping these important gut communities. While some microbiota members appear unaffected, changes in others and the community overall suggests that collateral perturbation of the native gut microbiota upon an innate immune response may serve as an additional selective pressure that shapes the evolution of host innate immunity.

2.
Sci Transl Med ; 16(768): eado3022, 2024 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-39383244

RESUMO

Increased plasma creatine concentrations are associated with the risk of type 2 diabetes, but whether this alteration is associated with or causal for impairments in metabolism remains unexplored. Because skeletal muscle is the main disposal site of both creatine and glucose, we investigated the role of intramuscular creatine metabolism in the pathophysiology of insulin resistance in type 2 diabetes. In men with type 2 diabetes, plasma creatine concentrations were increased, and intramuscular phosphocreatine content was reduced. These alterations were coupled to reduced expression of sarcomeric mitochondrial creatine kinase 2 (CKMT2). In C57BL/6 mice fed a high-fat diet, neither supplementation with creatine for 2 weeks nor treatment with the creatine analog ß-GPA for 1 week induced changes in glucose tolerance, suggesting that increased circulating creatine was associated with insulin resistance rather than causing it. In C2C12 myotubes, silencing Ckmt2 using small interfering RNA reduced mitochondrial respiration, membrane potential, and glucose oxidation. Electroporation-mediated overexpression of Ckmt2 in skeletal muscle of high-fat diet-fed male mice increased mitochondrial respiration, independent of creatine availability. Given that overexpression of Ckmt2 improved mitochondrial function, we explored whether exercise regulates CKMT2 expression. Analysis of public data revealed that CKMT2 content was up-regulated by exercise training in both humans and mice. We reveal a previously underappreciated role of CKMT2 in mitochondrial homeostasis beyond its function for creatine phosphorylation, independent of insulin action. Collectively, our data provide functional evidence for how CKMT2 mediates mitochondrial dysfunction associated with type 2 diabetes.


Assuntos
Creatina Quinase Mitocondrial , Diabetes Mellitus Tipo 2 , Insulina , Músculo Esquelético , Animais , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Creatina/metabolismo , Creatina Quinase Mitocondrial/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Dieta Hiperlipídica , Glucose/metabolismo , Insulina/metabolismo , Resistência à Insulina , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo
3.
J Surg Orthop Adv ; 33(3): 162-167, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39475801

RESUMO

The purpose of this study was to determine if implementation of an enhanced recovery pathway (ERP) for elective spine surgery reduced opioid use and pain scores in elective spine surgery. A historical cohort study of 171 patients undergoing elective spine procedures between 2017 and 2021 was performed. The primary outcomes were opioid use and average daily pain scores. A group of 92 patients received the novel ERP (2019 - 2021) in comparison to a historical control group of 79 patients without the ERP (2017 - 2019). On postoperative days 1 to 3, the ERP group received 36% (p < 0.001), 36% (p < 0.001), and 37% (p = 0.005) less milligram morphine equivalents, respectively. On postoperative days 1 to 3, the ERP group pain scores were 1.5 (p < 0.001), 1.0 (p = 0.003), and 1.1 (p = 0.004) points lower, respectively. Length of stay was similar (4.3 vs. 4.5 days, p = 0.693). Adoption of this ERP protocol was associated with clinically significant reduced opioid consumption and pain scores in elective spine surgery. (Journal of Surgical Orthopaedic Advances 33(3):162-167, 2024).


Assuntos
Analgésicos Opioides , Procedimentos Cirúrgicos Eletivos , Recuperação Pós-Cirúrgica Melhorada , Medição da Dor , Dor Pós-Operatória , Humanos , Analgésicos Opioides/uso terapêutico , Dor Pós-Operatória/tratamento farmacológico , Feminino , Masculino , Pessoa de Meia-Idade , Idoso , Tempo de Internação/estatística & dados numéricos , Coluna Vertebral/cirurgia , Adulto , Estudos Retrospectivos , Estudos de Coortes
4.
Can Vet J ; 65(10): 1071-1075, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39355703

RESUMO

A 9-year-old castrated male German shepherd dog was presented because of a 2-day history of lethargy and anorexia. Abdominal distention and free peritoneal fluid were noted on physical examination, which prompted radiographs revealing a large, soft tissue and stippled gas opaque structure in the right cranial abdomen. Computed tomography was used to further describe the structure and assess for comorbidities in the dog. Both CT and abdominal radiographs supported a diagnosis of emphysematous splenic torsion. The enlarged spleen was surgically extracted, along with sections of necrotic omentum. Four days after the procedure, the dog developed a portal vein thrombus and secondary abdominal effusion, which ultimately led to the decision for humane euthanasia. Veterinarians should know the different imaging modalities used to diagnose splenic torsion and the possible postoperative complications following treatment.


Torsion splénique emphysémateuse chez un berger allemandUn berger allemand mâle castré de 9 ans a été présenté en raison d'une léthargie et d'une anorexie depuis 2 jours. Une distension abdominale et du liquide péritonéal libre ont été notés lors de l'examen physique, ce qui a donné lieu à des radiographies révélant une grosse structure opaque de tissus mous et de gaz dans l'abdomen crânial droit. Un examen par tomodensitométrie a été utilisée pour décrire plus en détail la structure et évaluer les comorbidités chez le chien. La tomodensitométrie et les radiographies abdominales ont toutes deux confirmé un diagnostic de torsion splénique emphysémateuse. La rate hypertrophiée a été extraite chirurgicalement, ainsi que des sections d'épiploon nécrotique. Quatre jours après l'intervention, le chien a développé un thrombus de la veine porte et un épanchement abdominal secondaire, ce qui a finalement conduit à la décision d'une euthanasie. Les vétérinaires doivent connaître les différentes modalités d'imagerie utilisées pour diagnostiquer la torsion splénique et les complications postopératoires possibles après le traitement.(Traduit par Dr Serge Messier).


Assuntos
Doenças do Cão , Esplenopatias , Anormalidade Torcional , Animais , Cães , Masculino , Doenças do Cão/cirurgia , Doenças do Cão/diagnóstico , Doenças do Cão/diagnóstico por imagem , Anormalidade Torcional/veterinária , Anormalidade Torcional/cirurgia , Esplenopatias/veterinária , Esplenopatias/cirurgia , Esplenopatias/diagnóstico por imagem , Enfisema/veterinária , Tomografia Computadorizada por Raios X/veterinária
5.
Proc Natl Acad Sci U S A ; 121(45): e2412293121, 2024 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-39475637

RESUMO

How can a single protein domain encode a conformational landscape with multiple stably folded states, and how do those states interconvert? Here, we use real-time and relaxation-dispersion NMR to characterize the conformational landscape of the circadian rhythm protein KaiB from Rhodobacter sphaeroides. Unique among known natural metamorphic proteins, this KaiB variant spontaneously interconverts between two monomeric states: the "Ground" and "Fold-switched" (FS) states. KaiB in its FS state interacts with multiple binding partners, including the central KaiC protein, to regulate circadian rhythms. We find that KaiB itself takes hours to interconvert between the Ground and FS state, underscoring the ability of a single-sequence to encode the slow process needed for function. We reveal the rate-limiting step between the Ground and FS state is the cis-trans isomerization of three prolines in the fold-switching region by demonstrating interconversion acceleration by the prolyl isomerase Cyclophilin A. The interconversion proceeds through a "partially disordered" (PD) state, where the C-terminal half becomes disordered while the N-terminal half remains stably folded. We found two additional properties of KaiB's landscape. First, the Ground state experiences cold denaturation: At 4 °C, the PD state becomes the majorly populated state. Second, the Ground state exchanges with a fourth state, the "Enigma" state, on the millisecond-timescale. We combine AlphaFold2-based predictions and NMR chemical shift predictions to predict this Enigma state is a beta-strand register shift that relieves buried charged residues, and support this structure experimentally. These results provide mechanistic insight into how evolution can design a single-sequence that achieves specific timing needed for its function.


Assuntos
Proteínas de Bactérias , Ritmo Circadiano , Conformação Proteica , Dobramento de Proteína , Rhodobacter sphaeroides , Rhodobacter sphaeroides/metabolismo , Rhodobacter sphaeroides/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Ritmo Circadiano/fisiologia , Peptídeos e Proteínas de Sinalização do Ritmo Circadiano/metabolismo , Peptídeos e Proteínas de Sinalização do Ritmo Circadiano/química , Peptídeos e Proteínas de Sinalização do Ritmo Circadiano/genética , Modelos Moleculares , Espectroscopia de Ressonância Magnética
6.
ACS Chem Neurosci ; 2024 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-39316465

RESUMO

Herein, we report structure-activity relationship (SAR) studies to develop novel tricyclic M4 PAM scaffolds with improved pharmacological properties. This endeavor involved a "tie-back" strategy to replace a 5-amino-2,4-dimethylthieno[2,3-d]pyrimidine-6-carboxamide core, which led to the discovery of two novel tricyclic cores. While both tricyclic cores displayed low nanomolar potency against both human and rat M4 and were highly brain-penetrant, the 2,4-dimethylpyrido[4',3':4,5]thieno[2,3-d]pyrimidine tricycle core provided lead compound, VU6016235, with an overall superior pharmacological and drug metabolism and pharmacokinetics (DMPK) profile, as well as efficacy in a preclinical antipsychotic animal model.

7.
Nat Commun ; 15(1): 7769, 2024 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-39237515

RESUMO

Histone H3-mutant gliomas are deadly brain tumors characterized by a dysregulated epigenome and stalled differentiation. In contrast to the extensive datasets available on tumor cells, limited information exists on their tumor microenvironment (TME), particularly the immune infiltrate. Here, we characterize the immune TME of H3.3K27M and G34R/V-mutant gliomas, and multiple H3.3K27M mouse models, using transcriptomic, proteomic and spatial single-cell approaches. Resolution of immune lineages indicates high infiltration of H3-mutant gliomas with diverse myeloid populations, high-level expression of immune checkpoint markers, and scarce lymphoid cells, findings uniformly reproduced in all H3.3K27M mouse models tested. We show these myeloid populations communicate with H3-mutant cells, mediating immunosuppression and sustaining tumor formation and maintenance. Dual inhibition of myeloid cells and immune checkpoint pathways show significant therapeutic benefits in pre-clinical syngeneic mouse models. Our findings provide a valuable characterization of the TME of oncohistone-mutant gliomas, and insight into the means for modulating the myeloid infiltrate for the benefit of patients.


Assuntos
Neoplasias Encefálicas , Glioma , Histonas , Mutação , Células Mieloides , Microambiente Tumoral , Animais , Glioma/genética , Glioma/imunologia , Glioma/patologia , Microambiente Tumoral/imunologia , Microambiente Tumoral/genética , Células Mieloides/metabolismo , Células Mieloides/imunologia , Histonas/metabolismo , Histonas/genética , Camundongos , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/imunologia , Neoplasias Encefálicas/patologia , Humanos , Linhagem Celular Tumoral , Modelos Animais de Doenças , Camundongos Endogâmicos C57BL , Regulação Neoplásica da Expressão Gênica , Análise de Célula Única
8.
Nat Chem ; 2024 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-39285206

RESUMO

Nitriles are uncommon in nature and are typically constructed from oximes through the oxidative decarboxylation of amino acid substrates or from the derivatization of carboxylic acids. Here we report a third nitrile biosynthesis strategy featuring the cyanobacterial nitrile synthase AetD. During the biosynthesis of the eagle-killing neurotoxin, aetokthonotoxin, AetD transforms the 2-aminopropionate portion of 5,7-dibromo-L-tryptophan to a nitrile. Employing a combination of structural, biochemical and biophysical techniques, we characterized AetD as a non-haem diiron enzyme that belongs to the emerging haem-oxygenase-like dimetal oxidase superfamily. High-resolution crystal structures of AetD together with the identification of catalytically relevant products provide mechanistic insights into how AetD affords this unique transformation, which we propose proceeds via an aziridine intermediate. Our work presents a unique template for nitrile biogenesis and portrays a substrate binding and metallocofactor assembly mechanism that may be shared among other haem-oxygenase-like dimetal oxidase enzymes.

9.
ACS Cent Sci ; 10(8): 1524-1536, 2024 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-39220707

RESUMO

Heme oxygenase-like domain-containing oxidases (HDOs) are a rapidly expanding enzyme family that typically use dinuclear metal cofactors instead of heme. FlcD, an HDO from the opportunistic pathogen Pseudomonas aeruginosa, catalyzes the excision of an oxime carbon in the biosynthesis of the copper-containing antibiotic fluopsin C. We show that FlcD is a dioxygenase that catalyzes a four-electron oxidation. Crystal structures of FlcD reveal a mononuclear iron in the active site, which is coordinated by two histidines, one glutamate, and the oxime of the substrate. Enzyme activity, Mössbauer spectroscopy, and electron paramagnetic resonance spectroscopy analyses support the usage of a mononuclear iron cofactor. This cofactor resembles that of mononuclear non-heme iron-dependent enzymes and breaks the paradigm of dinuclear HDO cofactors. This study begins to illuminate the catalytic mechanism of methine excision and indicates convergent evolution of different lineages of mononuclear iron-dependent enzymes.

10.
bioRxiv ; 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39211239

RESUMO

Current therapies for the epilepsies only treat the symptoms, but do not prevent epileptogenesis (the process in which epilepsy develops). Many cellular responses during epileptogenesis are also common hallmarks of cellular senescence , which halts proliferation of damaged cells. Clearing senescent cells (SCs) restores function in several age-associated and neurodegenerative disease models. It is unknown whether SC accumulation contributes to epileptogenesis and associated cognitive impairments. To address this question, we used a mouse model of temporal lobe epilepsy (TLE) and characterized the senescence phenotype throughout epileptogenesis. SCs accumulated 2 weeks after SE and were predominantly microglia. We ablated SCs and reduced (and in some cases prevented) the emergence of spontaneous seizures and normalized cognitive function in mice. Suggesting that this is a translationally-relevant target we also found SC accumulation in resected hippocampi from patients with TLE. These findings indicate that SC ablation after an epileptogenic insult is a potential anti-epileptogenic therapy.

11.
NPJ Syst Biol Appl ; 10(1): 91, 2024 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-39155294

RESUMO

Glioblastoma is the most common and deadliest brain tumour in adults, with a median survival of 15 months under the current standard of care. Immunotherapies like immune checkpoint inhibitors and oncolytic viruses have been extensively studied to improve this endpoint. However, most thus far have failed. To improve the efficacy of immunotherapies to treat glioblastoma, new single-cell imaging modalities like imaging mass cytometry can be leveraged and integrated with computational models. This enables a better understanding of the tumour microenvironment and its role in treatment success or failure in this hard-to-treat tumour. Here, we implemented an agent-based model that allows for spatial predictions of combination chemotherapy, oncolytic virus, and immune checkpoint inhibitors against glioblastoma. We initialised our model with patient imaging mass cytometry data to predict patient-specific responses and found that oncolytic viruses drive combination treatment responses determined by intratumoral cell density. We found that tumours with higher tumour cell density responded better to treatment. When fixing the number of cancer cells, treatment efficacy was shown to be a function of CD4 + T cell and, to a lesser extent, of macrophage counts. Critically, our simulations show that care must be put into the integration of spatial data and agent-based models to effectively capture intratumoral dynamics. Together, this study emphasizes the use of predictive spatial modelling to better understand cancer immunotherapy treatment dynamics, while highlighting key factors to consider during model design and implementation.


Assuntos
Neoplasias Encefálicas , Simulação por Computador , Glioblastoma , Imunoterapia , Microambiente Tumoral , Glioblastoma/terapia , Glioblastoma/imunologia , Humanos , Microambiente Tumoral/imunologia , Imunoterapia/métodos , Neoplasias Encefálicas/terapia , Neoplasias Encefálicas/imunologia , Terapia Viral Oncolítica/métodos , Vírus Oncolíticos/imunologia , Inibidores de Checkpoint Imunológico/uso terapêutico , Inibidores de Checkpoint Imunológico/farmacologia
12.
J Bone Oncol ; 47: 100625, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-39183755

RESUMO

The establishment and progression of bone metastatic breast cancer is supported by immunosuppressive myeloid populations that enable tumor growth by dampening the innate and adaptive immune response. Much work remains to understand how to target these tumor-myeloid interactions to improve treatment outcomes. Noncanonical Hedgehog signaling is an essential component of bone metastatic tumor progression, and prior literature suggests a potential role for Hedgehog signaling and its downstream effector Gli2 in modulating immune responses. In this work, we sought to identify if inhibition of noncanonical Hedgehog signaling alters the cytokine profile of osteolytic breast cancer cells and the subsequent communication between the tumor cells and myeloid cells. Examination of large patient databases revealed significant relationships between Gli2 expression and expression of markers of myeloid maturation and activation as well as cytokine expression. We found that treatment with HPI-1 reduced tumor cell expression of numerous cytokine genes, including CSF1, CSF2, and CSF3, as well as CCL2 and IL6. Secreted CSF-1 (M-CSF) was also reduced by treatment. Changes in tumor-secreted factors resulted in polarization of THP-1 monocytes toward a proinflammatory phenotype, characterized by increased CD14 and CD40 surface marker expression. We therefore propose M-CSF as a novel target of Hedgehog inhibition with potential future applications in altering the immune microenvironment in addition to its known roles in reducing tumor-induced bone disease.

13.
Artigo em Inglês | MEDLINE | ID: mdl-39103087

RESUMO

BACKGROUND: Elbow stiffness is 1 of the most common complications after operative fixation of distal humerus fractures; however, there is relatively limited literature assessing which factors are associated with this problem. The purpose of this study is to identify risk factors associated with dysfunctional elbow stiffness in distal humerus fractures after operative fixation. METHODS: A retrospective review of all distal humerus fractures that underwent operative fixation (AO/OTA 13A-C) at a single level 1 trauma center from November 2014 to October 2021. A minimum 6-month follow-up was required for inclusion or the outcome of interest. Dysfunctional elbow stiffness was defined as a flexion-extension arc of less than 100° at latest follow-up or any patient requiring surgical treatment for limited elbow range of motion. RESULTS: A total of 110 patients with distal humerus fractures were included in the study: 54 patients comprised the elbow stiffness group and 56 patients were in the control group. Average follow-up of 343 (59 to 2079) days. Multiple logistic regression showed that orthogonal plate configuration (adjusted odds ratio [aOR]: 5.70, 95% confidence interval [CI]: 1.91-16.99, P = .002), and longer operative time (aOR: 1.86, 95% CI: 1.11-3.10, P = .017) were independently associated with an increased odds of elbow stiffness. OTA/AO 13A type fractures were significantly associated with a decreased odds of stiffness (aOR: 0.16, 95% CI: 0.03-0.80, P = .026). Among 13C fractures, olecranon osteotomy (aOR: 5.48, 95% CI: 1.08-27.73, P = .040) was also associated with an increased odds of elbow stiffness. There were no significant differences in injury mechanism, Gustilo-Anderson classification, reduction quality, days to surgery from admission, type of fixation, as well as rates of ipsilateral upper extremity fracture, neurovascular injury, nonunion, or infection between the 2 groups. CONCLUSION: Dysfunctional elbow stiffness was observed in 49.1% of patients who underwent operative fixation of distal humerus fractures in the present study. Orthogonal plate configuration, olecranon osteotomy, and longer operative time were associated with increased odds of dysfunctional elbow stiffness; however, 13A type fractures were associated with decreased odds of stiffness. Patients with these injuries should be counseled on their risk of stiffness following surgery and modifiable risk factors like plate positioning and performing an olecranon osteotomy should be considered by surgeons.

14.
JCI Insight ; 9(18)2024 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-39053472

RESUMO

Spinocerebellar ataxia type 7 (SCA7) is an autosomal dominant neurological disorder caused by deleterious CAG repeat expansion in the coding region of the ataxin 7 gene (polyQ-ataxin-7). Infantile-onset SCA7 leads to severe clinical manifestation of respiratory distress, but the exact cause of respiratory impairment remains unclear. Using the infantile-SCA7 mouse model, the SCA7266Q/5Q mouse, we examined the impact of pathological polyQ-ataxin-7 on hypoglossal (XII) and phrenic motor units. We identified the transcript profile of the medulla and cervical spinal cord and investigated the XII and phrenic nerves and the neuromuscular junctions in the diaphragm and tongue. SCA7266Q/5Q astrocytes showed significant intranuclear inclusions of ataxin-7 in the XII and putative phrenic motor nuclei. Transcriptomic analysis revealed dysregulation of genes involved in amino acid and neurotransmitter transport and myelination. Additionally, SCA7266Q/5Q mice demonstrated blunted efferent output of the XII nerve and demyelination in both XII and phrenic nerves. Finally, there was an increased number of neuromuscular junction clusters with higher expression of synaptic markers in SCA7266Q/5Q mice compared with WT controls. These preclinical findings elucidate the underlying pathophysiology responsible for impaired glial cell function and death leading to dysphagia, aspiration, and respiratory failure in infantile SCA7.


Assuntos
Modelos Animais de Doenças , Nervo Hipoglosso , Nervo Frênico , Ataxias Espinocerebelares , Animais , Camundongos , Ataxias Espinocerebelares/genética , Ataxias Espinocerebelares/patologia , Nervo Hipoglosso/patologia , Nervo Frênico/patologia , Ataxina-7 , Bulbo/patologia , Bulbo/metabolismo , Junção Neuromuscular/patologia , Junção Neuromuscular/metabolismo , Camundongos Transgênicos , Humanos , Masculino , Feminino , Diafragma/patologia , Diafragma/fisiopatologia , Astrócitos/patologia , Astrócitos/metabolismo , Língua/patologia , Medula Espinal/patologia , Medula Espinal/metabolismo , Peptídeos
15.
J Phys Condens Matter ; 36(42)2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-39008992

RESUMO

Using density functional theory (DFT) and linear response approaches, we compute the on-site Hubbard interactionUof elemental Terbium (Tb) metal in the pressure range ∼ 0-65 GPa. The resulting first-principlesUvalues with experimental crystal structures enable us to examine the magnetic properties of Tb using a DFT+U method. The lowest-energy magnetic states in our calculations for different high-pressure Tb phases-including hcp,α-Sm, and dhcp-are found to be compatible with the corresponding magnetic ordering vectors reported in experiments. The result shows that the inclusion of HubbardUsubstantially improves the accuracy and efficiency in modeling correlated rare-earth materials. Our study also provides the necessaryUinformation for other quantum many-body techniques to study Tb under extreme pressure conditions.

16.
bioRxiv ; 2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38895306

RESUMO

How can a single protein domain encode a conformational landscape with multiple stably-folded states, and how do those states interconvert? Here, we use real-time and relaxation-dispersion NMR to characterize the conformational landscape of the circadian rhythm protein KaiB from Rhodobacter sphaeroides. Unique among known natural metamorphic proteins, this KaiB variant spontaneously interconverts between two monomeric states: the "Ground" and "Fold-switched" (FS) state. KaiB in its FS state interacts with multiple binding partners, including the central KaiC protein, to regulate circadian rhythms. We find that KaiB itself takes hours to interconvert between the Ground and FS state, underscoring the ability of a single sequence to encode the slow process needed for function. We reveal the rate-limiting step between the Ground and FS state is the cis-trans isomerization of three prolines in the fold-switching region by demonstrating interconversion acceleration by the prolyl isomerase CypA. The interconversion proceeds through a "partially disordered" (PD) state, where the C-terminal half becomes disordered while the N-terminal half remains stably folded. We discovered two additional properties of KaiB's landscape. Firstly, the Ground state experiences cold denaturation: at 4°C, the PD state becomes the majorly populated state. Secondly, the Ground state exchanges with a fourth state, the "Enigma" state, on the millisecond timescale. We combine AlphaFold2-based predictions and NMR chemical shift predictions to predict this "Enigma" state is a beta-strand register shift that eases buried charged residues, and support this structure experimentally. These results provide mechanistic insight in how evolution can design a single sequence that achieves specific timing needed for its function.

17.
Phys Rev X ; 14(1)2024.
Artigo em Inglês | MEDLINE | ID: mdl-38911939

RESUMO

The spiking activity of neocortical neurons exhibits a striking level of variability, even when these networks are driven by identical stimuli. The approximately Poisson firing of neurons has led to the hypothesis that these neural networks operate in the asynchronous state. In the asynchronous state, neurons fire independently from one another, so that the probability that a neuron experience synchronous synaptic inputs is exceedingly low. While the models of asynchronous neurons lead to observed spiking variability, it is not clear whether the asynchronous state can also account for the level of subthreshold membrane potential variability. We propose a new analytical framework to rigorously quantify the subthreshold variability of a single conductance-based neuron in response to synaptic inputs with prescribed degrees of synchrony. Technically, we leverage the theory of exchangeability to model input synchrony via jump-process-based synaptic drives; we then perform a moment analysis of the stationary response of a neuronal model with all-or-none conductances that neglects postspiking reset. As a result, we produce exact, interpretable closed forms for the first two stationary moments of the membrane voltage, with explicit dependence on the input synaptic numbers, strengths, and synchrony. For biophysically relevant parameters, we find that the asynchronous regime yields realistic subthreshold variability (voltage variance ≃4-9 mV2) only when driven by a restricted number of large synapses, compatible with strong thalamic drive. By contrast, we find that achieving realistic subthreshold variability with dense cortico-cortical inputs requires including weak but nonzero input synchrony, consistent with measured pairwise spiking correlations. We also show that, without synchrony, the neural variability averages out to zero for all scaling limits with vanishing synaptic weights, independent of any balanced state hypothesis. This result challenges the theoretical basis for mean-field theories of the asynchronous state.

18.
JMIR Hum Factors ; 11: e57239, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38861717

RESUMO

BACKGROUND: Overdose Fatality Review (OFR) is an important public health tool for shaping overdose prevention strategies in communities. However, OFR teams review only a few cases at a time, which typically represent a small fraction of the total fatalities in their jurisdiction. Such limited review could result in a partial understanding of local overdose patterns, leading to policy recommendations that do not fully address the broader community needs. OBJECTIVE: This study explored the potential to enhance conventional OFRs with a data dashboard, incorporating visualizations of touchpoints-events that precede overdoses-to highlight prevention opportunities. METHODS: We conducted 2 focus groups and a survey of OFR experts to characterize their information needs and design a real-time dashboard that tracks and measures decedents' past interactions with services in Indiana. Experts (N=27) were engaged, yielding insights on essential data features to incorporate and providing feedback to guide the development of visualizations. RESULTS: The findings highlighted the importance of showing decedents' interactions with health services (emergency medical services) and the justice system (incarcerations). Emphasis was also placed on maintaining decedent anonymity, particularly in small communities, and the need for training OFR members in data interpretation. The developed dashboard summarizes key touchpoint metrics, including prevalence, interaction frequency, and time intervals between touchpoints and overdoses, with data viewable at the county and state levels. In an initial evaluation, the dashboard was well received for its comprehensive data coverage and its potential for enhancing OFR recommendations and case selection. CONCLUSIONS: The Indiana touchpoints dashboard is the first to display real-time visualizations that link administrative and overdose mortality data across the state. This resource equips local health officials and OFRs with timely, quantitative, and spatiotemporal insights into overdose risk factors in their communities, facilitating data-driven interventions and policy changes. However, fully integrating the dashboard into OFR practices will likely require training teams in data interpretation and decision-making.


Assuntos
Overdose de Drogas , Grupos Focais , Design Centrado no Usuário , Humanos , Overdose de Drogas/prevenção & controle , Overdose de Drogas/epidemiologia , Indiana/epidemiologia , Inquéritos e Questionários
19.
J Equine Vet Sci ; 140: 105143, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38945460

RESUMO

Periods of limited activity during semester break may reduce performance during return to ridden work. This study evaluated fitness and muscling of horses when returning to work, following a 12-week period during which horses either continued (conditioned) or discontinued (non-conditioned) ridden work. It was hypothesized that non-conditioned horses would have a lower level of fitness, resulting in higher resting and peak heart rates and lower levels of muscling. Twelve mature, stock type horses aged 16 ± 5 years were assigned to either a conditioned group that maintained light-to-moderate riding or a non-conditioned group receiving no formal exercise. All horses had access to voluntary exercise for 12-24hr/d on grass pasture (1.5-2.5 hectares). Following the 12-week period, all horses were placed into a light-to-moderate intensity exercise program with resting heart rate, peak heart rate, body condition score, gaskin and forearm circumference, and topline muscle measurements performed on d 0, 14, and 28. Peak and resting heart rates were not different between groups (P > 0.05) but increased for both groups throughout the study (P = 0.04). Gaskin circumference of non-conditioned horses was larger (P = 0.04), although non-conditioned horses tended to be heavier (551.4 versus 491.4 ± 21.4 kg; P = 0.07). Conditioned horses had greater average topline muscling scores (P = 0.02). Horses that were conditioned over a 12-week break had greater muscling, but changes in fitness were not detected. Pasture access could contribute to maintenance of fitness during unridden periods.


Assuntos
Condicionamento Físico Animal , Animais , Cavalos/fisiologia , Condicionamento Físico Animal/fisiologia , Masculino , Feminino , Frequência Cardíaca/fisiologia
20.
Respir Physiol Neurobiol ; 326: 104282, 2024 08.
Artigo em Inglês | MEDLINE | ID: mdl-38782084

RESUMO

Duchenne muscular dystrophy (DMD) is the most common X-linked disease. DMD is caused by a lack of dystrophin, a critical structural protein in striated muscle. Dystrophin deficiency leads to inflammation, fibrosis, and muscle atrophy. Boys with DMD have progressive muscle weakness within the diaphragm that results in respiratory failure in the 2nd or 3rd decade of life. The most common DMD mouse model - the mdx mouse - is not sufficient for evaluating genetic medicines that specifically target the human DMD (hDMD) gene sequence. Therefore, a novel transgenic mouse carrying the hDMD gene with an exon 52 deletion was created (hDMDΔ52;mdx). We characterized the respiratory function and pathology in this model using whole body plethysmography, histology, and immunohistochemistry. At 6-months-old, hDMDΔ52;mdx mice have reduced maximal respiration, neuromuscular junction pathology, and fibrosis throughout the diaphragm, which worsens at 12-months-old. In conclusion, the hDMDΔ52;mdx exhibits moderate respiratory pathology, and serves as a relevant animal model to study the impact of novel genetic therapies, including gene editing, on respiratory function.


Assuntos
Modelos Animais de Doenças , Camundongos Transgênicos , Distrofia Muscular de Duchenne , Animais , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/patologia , Distrofia Muscular de Duchenne/fisiopatologia , Camundongos , Humanos , Masculino , Distrofina/genética , Distrofina/deficiência , Camundongos Endogâmicos mdx , Diafragma/fisiopatologia , Diafragma/patologia , Insuficiência Respiratória/etiologia , Junção Neuromuscular/patologia , Junção Neuromuscular/metabolismo , Camundongos Endogâmicos C57BL
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