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1.
J Gen Virol ; 105(5)2024 05.
Artigo em Inglês | MEDLINE | ID: mdl-38757942

RESUMO

Since its discovery in 1965, our understanding of the hepatitis B virus (HBV) replication cycle and host immune responses has increased markedly. In contrast, our knowledge of the molecular biology of hepatitis delta virus (HDV), which is associated with more severe liver disease, is less well understood. Despite the progress made, critical gaps remain in our knowledge of HBV and HDV replication and the mechanisms underlying viral persistence and evasion of host immunity. The International HBV Meeting is the leading annual scientific meeting for presenting the latest advances in HBV and HDV molecular virology, immunology, and epidemiology. In 2023, the annual scientific meeting was held in Kobe, Japan and this review summarises some of the advances presented at the Meeting and lists gaps in our knowledge that may facilitate the development of new therapies.


Assuntos
Vírus da Hepatite B , Hepatite B , Vírus Delta da Hepatite , Replicação Viral , Vírus da Hepatite B/genética , Vírus da Hepatite B/fisiologia , Vírus da Hepatite B/imunologia , Humanos , Vírus Delta da Hepatite/genética , Vírus Delta da Hepatite/fisiologia , Hepatite B/virologia , Hepatite B/imunologia , Biologia Molecular , Japão , Hepatite D/virologia , Interações Hospedeiro-Patógeno/imunologia , Interações Hospedeiro-Patógeno/genética
2.
Res Sq ; 2024 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-38746248

RESUMO

The expression of a synthetic chimeric antigen receptor (CAR) to redirect antigen specificity of T cells is transforming the treatment of hematological malignancies and autoimmune diseases [1-7]. In cancer, durable efficacy is frequently limited by the escape of tumors that express low levels or lack the target antigen [8-12]. These clinical results emphasize the need for immune receptors that combine high sensitivity and multispecificity to improve outcomes. Current mono- and bispecific CARs do not faithfully recapitulate T cell receptor (TCR) function and require high antigen levels on tumor cells for recognition [13-17]. Here, we describe a novel synthetic chimeric TCR (ChTCR) that exhibits superior antigen sensitivity and is readily adapted for bispecific targeting. Bispecific ChTCRs mimic TCR structure, form classical immune synapses, and exhibit TCR-like proximal signaling. T cells expressing Bi-ChTCRs more effectively eliminated tumors with heterogeneous antigen expression in vivo compared to T cells expressing optimized bispecific CARs. The Bi-ChTCR architecture is resilient and can be designed to target multiple B cell lineage and multiple myeloma antigens. Our findings identify a broadly applicable approach for engineering T cells to target hematologic malignancies with heterogeneous antigen expression, thereby overcoming the most frequent mechanism of relapse after current CAR T therapies.

3.
Proc Natl Acad Sci U S A ; 121(21): e2321410121, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38748575

RESUMO

Here, we describe a group of basal forebrain (BF) neurons expressing neuronal Per-Arnt-Sim (PAS) domain 1 (Npas1), a developmental transcription factor linked to neuropsychiatric disorders. Immunohistochemical staining in Npas1-cre-2A-TdTomato mice revealed BF Npas1+ neurons are distinct from well-studied parvalbumin or cholinergic neurons. Npas1 staining in GAD67-GFP knock-in mice confirmed that the vast majority of Npas1+ neurons are GABAergic, with minimal colocalization with glutamatergic neurons in vGlut1-cre-tdTomato or vGlut2-cre-tdTomato mice. The density of Npas1+ neurons was high, five to six times that of neighboring cholinergic, parvalbumin, or glutamatergic neurons. Anterograde tracing identified prominent projections of BF Npas1+ neurons to brain regions involved in sleep-wake control, motivated behaviors, and olfaction such as the lateral hypothalamus, lateral habenula, nucleus accumbens shell, ventral tegmental area, and olfactory bulb. Chemogenetic activation of BF Npas1+ neurons in the light period increased the amount of wakefulness and the latency to sleep for 2 to 3 h, due to an increase in long wake bouts and short NREM sleep bouts. NREM slow-wave and sigma power, as well as sleep spindle density, amplitude, and duration, were reduced, reminiscent of findings in several neuropsychiatric disorders. Together with previous findings implicating BF Npas1+ neurons in stress responsiveness, the anatomical projections of BF Npas1+ neurons and the effect of activating them suggest a possible role for BF Npas1+ neurons in motivationally driven wakefulness and stress-induced insomnia. Identification of this major subpopulation of BF GABAergic neurons will facilitate studies of their role in sleep disorders, dementia, and other neuropsychiatric conditions involving BF.


Assuntos
Prosencéfalo Basal , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Neurônios GABAérgicos , Vigília , Animais , Neurônios GABAérgicos/metabolismo , Neurônios GABAérgicos/fisiologia , Prosencéfalo Basal/metabolismo , Prosencéfalo Basal/fisiologia , Camundongos , Vigília/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Camundongos Transgênicos , Masculino , Sono/fisiologia
4.
NAR Cancer ; 6(2): zcae021, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38774470

RESUMO

Glioblastoma (GBM) is the most common and aggressive brain tumor in adults. To identify genes differentially required for the viability of GBM stem-like cells (GSCs), we performed functional genomic lethality screens comparing GSCs and control human neural stem cells. Among top-scoring hits in a subset of GBM cells was the F-box-containing gene FBXO42, which was also predicted to be essential in ∼15% of cell lines derived from a broad range of cancers. Mechanistic studies revealed that, in sensitive cells, FBXO42 activity prevents chromosome alignment defects, mitotic cell cycle arrest and cell death. The cell cycle arrest, but not the cell death, triggered by FBXO42 inactivation could be suppressed by brief exposure to a chemical inhibitor of Mps1, a key spindle assembly checkpoint (SAC) kinase. FBXO42's cancer-essential function requires its F-box and Kelch domains, which are necessary for FBXO42's substrate recognition and targeting by SCF (SKP1-CUL1-F-box protein) ubiquitin ligase complex. However, none of FBXO42's previously proposed targets, including ING4, p53 and RBPJ, were responsible for the observed phenotypes. Instead, our results suggest that FBOX42 alters the activity of one or more proteins that perturb chromosome-microtubule dynamics in cancer cells, which in turn leads to induction of the SAC and cell death.

5.
ACS Macro Lett ; : 658-663, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38747245

RESUMO

Nucleophilic and non-nucleophilic bases have been employed in anionic oligomerization of unsaturated δ-valerolactone (3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one) (1). Compared to the seminal findings with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), the unsaturated lactone reacts with guanidines, disilazanes, and phosphazenes both in bulk and in solution with higher productivities and activities, reaching full conversion with turnover frequencies up to 382 h-1. Additionally, reactions using phosphazenes and NaHMDS were active at 1 mol % catalyst loadings both in solvent and in bulk monomer at room temperature. Characterization of the reaction products by 1H, 13C, FTIR, MALDI-MS, tandem mass spectrometry (MS/MS), and ion mobility mass spectrometry (IM-MS) revealed microstructural differences dependent on the nucleophilicity of the organocatalytic base and reaction conditions. The products from phosphazene-catalyzed reactions are consistent with selective vinylogous 1,4-conjugate addition, whereas both conjugate addition and ring-opening mechanisms are observed in TBD. DSC reveals that these microstructures can be tuned to have a Tg range between -18 and 80 °C, while SEC and MALDI-MS reveal that only low molar mass oligomers are formed (748-5949 g/mol). From these results, an approach for selectively favoring the vinylogous 1,4-conjugate addition pathway is obtained over ring-opening reactivity.

6.
Nat Rev Drug Discov ; 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38773351

RESUMO

Secondary pharmacology screening of investigational small-molecule drugs for potentially adverse off-target activities has become standard practice in pharmaceutical research and development, and regulatory agencies are increasingly requesting data on activity against targets with recognized adverse effect relationships. However, the screening strategies and target panels used by pharmaceutical companies may vary substantially. To help identify commonalities and differences, as well as to highlight opportunities for further optimization of secondary pharmacology assessment, we conducted a broad-ranging survey across 18 companies under the auspices of the DruSafe leadership group of the International Consortium for Innovation and Quality in Pharmaceutical Development. Based on our analysis of this survey and discussions and additional research within the group, we present here an overview of the current state of the art in secondary pharmacology screening. We discuss best practices, including additional safety-associated targets not covered by most current screening panels, and present approaches for interpreting and reporting off-target activities. We also provide an assessment of the safety impact of secondary pharmacology screening, and a perspective on opportunities and challenges in this rapidly developing field.

7.
Neuron ; 112(10): 1611-1625, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38754373

RESUMO

Consciousness can be conceptualized as varying along at least two dimensions: the global state of consciousness and the content of conscious experience. Here, we highlight the cellular and systems-level contributions of the thalamus to conscious state and then argue for thalamic contributions to conscious content, including the integrated, segregated, and continuous nature of our experience. We underscore vital, yet distinct roles for core- and matrix-type thalamic neurons. Through reciprocal interactions with deep-layer cortical neurons, matrix neurons support wakefulness and determine perceptual thresholds, whereas the cortical interactions of core neurons maintain content and enable perceptual constancy. We further propose that conscious integration, segregation, and continuity depend on the convergent nature of corticothalamic projections enabling dimensionality reduction, a thalamic reticular nucleus-mediated divisive normalization-like process, and sustained coherent activity in thalamocortical loops, respectively. Overall, we conclude that the thalamus plays a central topological role in brain structures controlling conscious experience.


Assuntos
Estado de Consciência , Tálamo , Tálamo/fisiologia , Estado de Consciência/fisiologia , Humanos , Animais , Vias Neurais/fisiologia , Neurônios/fisiologia , Córtex Cerebral/fisiologia , Vigília/fisiologia
8.
Int J Part Ther ; 11: 100014, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38757084

RESUMO

Purpose: To identify the characteristics, indications, and toxicities among patients receiving proton beam therapy (PBT) in the final year of life at an academic medical center. Materials and Methods: A retrospective review of patients who received PBT within the final 12 months of life was performed. Electronic medical records were reviewed for patient and treatment details from 2010 to 2019. Patients were followed from the start of PBT until death or last follow-up. Acute (3 months) toxicities were graded using the Common Terminology Criteria for Adverse Events v5.0. Imaging response was assessed using the Response Evaluation Criteria in Solid Tumors v1.1. The χ2 test was used to evaluate factors associated with palliative treatment. Simple logistic regression was used to evaluate factors associated with toxicity. Results: Bet299 patients were treated at the end of life (EOL) out of 5802 total patients treated with PBT (5.2%). Median age was 68 years (19-94 years), 58% male. The most common cancer was nonsmall cell lung cancer (27%). Patients were treated for symptom palliation alone (11%), durable control (57%), curative intent (16%), local recurrence (14%), or oligometastatic disease (2%). Forty-five percent received reirradiation. Median treatment time was 32 days (1-189 days). Acute toxicity was noted in 85% of the patients (31% G1, 53% G2, 15% G3). Thirteen patients (4%) experienced chronic toxicity. Breast and hematologic malignancy were associated with palliative intent χ2 (1, N = 14) = 17, P = .013; (χ2 (1, N = 14) = 18, P = .009). Conclusion: The number of patients treated with PBT at the EOL was low compared to all comers. Many of these patients received treatment with definitive doses and concurrent systemic therapy. Some patients spent a large portion of their remaining days on treatment. A prognostic indicator may better optimize patient selection for PBT at the EOL.

9.
Artigo em Inglês | MEDLINE | ID: mdl-38722709

RESUMO

Background: Patient perception of medication onset of effect is important for adherence. Although the Onset of Effect Questionnaire (OEQ) has been validated in patients with asthma, it has not been evaluated in patients with chronic obstructive pulmonary disease (COPD). This study evaluated the COPD-OEQ in patients with COPD. Methods: Two analyses (qualitative and quantitative) were conducted to assess the content validity and psychometric properties of the COPD-OEQ in participants with COPD. In the qualitative analysis, interviews assessed content validity by concept elicitation (CE) and cognitive interviewing (CI). CE included questions to understand patient experience related to onset of medication effect. CI included completion of the COPD-OEQ and assessment of the COPD-OEQ items, response options, and instructions. During the 2-week quantitative analysis, 2 versions of the COPD-OEQ (Weekly and Daily) were administered to assess test-retest reliability, construct validity, and known-groups validity. Results: The qualitative analysis demonstrated that 3 of the 5 COPD-OEQ items were relevant and understood as intended. Qualitative findings demonstrated inconsistent evidence that the COPD-OEQ Weekly and Daily were reliable and valid measures in participants with COPD. Test-retest reliability was observed for the COPD-OEQ Weekly and Daily; however, construct validitywas weak and demonstrated inconsistent correlations among COPD-OEQ items. Overall, known-groups validity was not demonstrated. Conclusion: The weak evidence from the quantitative analysis of the COPD-OEQ Weekly and Daily tools does not support use of the OEQ in general COPD. The study supports the content validity for the assessment of perceived onset of effect in patients with COPD.

10.
Am J Hum Genet ; 2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38723632

RESUMO

To identify credible causal risk variants (CCVs) associated with different histotypes of epithelial ovarian cancer (EOC), we performed genome-wide association analysis for 470,825 genotyped and 10,163,797 imputed SNPs in 25,981 EOC cases and 105,724 controls of European origin. We identified five histotype-specific EOC risk regions (p value <5 × 10-8) and confirmed previously reported associations for 27 risk regions. Conditional analyses identified an additional 11 signals independent of the primary signal at six risk regions (p value <10-5). Fine mapping identified 4,008 CCVs in these regions, of which 1,452 CCVs were located in ovarian cancer-related chromatin marks with significant enrichment in active enhancers, active promoters, and active regions for CCVs from each EOC histotype. Transcriptome-wide association and colocalization analyses across histotypes using tissue-specific and cross-tissue datasets identified 86 candidate susceptibility genes in known EOC risk regions and 32 genes in 23 additional genomic regions that may represent novel EOC risk loci (false discovery rate <0.05). Finally, by integrating genome-wide HiChIP interactome analysis with transcriptome-wide association study (TWAS), variant effect predictor, transcription factor ChIP-seq, and motifbreakR data, we identified candidate gene-CCV interactions at each locus. This included risk loci where TWAS identified one or more candidate susceptibility genes (e.g., HOXD-AS2, HOXD8, and HOXD3 at 2q31) and other loci where no candidate gene was identified (e.g., MYC and PVT1 at 8q24) by TWAS. In summary, this study describes a functional framework and provides a greater understanding of the biological significance of risk alleles and candidate gene targets at EOC susceptibility loci identified by a genome-wide association study.

11.
Lancet Rheumatol ; 2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38723654

RESUMO

Lumbar spinal stenosis is the leading indication for spine surgery in older adults. Surgery is recommended in clinical guidelines if non-surgical treatments have been provided with insufficient benefit. The difficulty for clinicians is that the current number of randomised controlled trials is low, which creates uncertainty about which treatments to provide. For non-surgical clinicians this paucity of data leads to a clinical dilemma of whether to continue managing the patient or refer to a spine surgeon. This Viewpoint aims to provide an update on the assessment of lumbar spinal stenosis, treatment recommendations, indications for referral to a spine surgeon, and current clinical dilemmas facing non-surgical clinicians and spinal surgeons.

13.
Ann Plast Surg ; 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38725113

RESUMO

ABSTRACT: Posterior vault distraction osteogenesis (PVDO) has been shown to resolve acute intracranial hypertension (AIH) while carrying an acceptable perioperative morbidity profile. PVDO has been associated with symptomatic improvement and fewer surgeries in those requiring ventriculoperitoneal shunts. The authors' experience using PVDO as an acute intervention is presented, demonstrating its safety and efficacy for management of AIH. Four cases of children with craniosynostosis that underwent PVDO in the acute setting are outlined. All patients presented with papilledema and symptoms of AIH. One patient with slit ventricle syndrome (SVS) presented with a nonfunctioning shunt following multiple shunt revisions. No intraoperative complications during distractor placement or removal were reported. Distraction protocol for all patients began on postoperative day 1 at 1-2 mm per day, resulting in an average total distraction of 30.25 mm. For the 3 cases with no shunt, the average length of stay was 7 days. As part of the planned treatment course, the patient with SVS required externalization of the shunt during distraction followed by early distractor removal and planned shunt replacement. One case of surgical site infection (in an immunocompromised patient) required premature distractor removal during the consolidation period. Computed tomography (CT) in all patients indicated increased intracranial volume following distraction, and symptomatic improvement was reported. Six-month follow-up showed resolution of papilledema in all patients. The authors' experience using PVDO in the acute setting is reported, alongside a review of current literature, in order to provide supporting evidence for the efficacy of PVDO as a tool for resolving AIH.

14.
J Eukaryot Microbiol ; : e13031, 2024 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-38725295

RESUMO

The salamander, Ambystoma annulatum, is considered a "species of special concern" in the state of Arkansas, USA, due to its limited geographic range, specialized habitat requirements and low population size. Although metazoan parasites have been documented in this salamander species, neither its native protists nor microbiome have yet been evaluated. This is likely due to the elusive nature and under-sampling of the animal. Here, we initiate the cataloguing of microbial associates with the identification of a new heterlobosean species, Naegleria lustrarea n. sp. (Excavata, Discoba, Heterolobosea), isolated from feces of an adult A. annulatum.

15.
Ann Surg ; 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38726663

RESUMO

OBJECTIVE: To assess the performance of a lower predicted postoperative (ppo) forced expiratory volume in 1 second (FEV1) or diffusion capacity of the lung for carbon monoxide (DLCO) (ppoFEV1/ppoDLCO) threshold to predict cardiopulmonary complications after minimally invasive surgery (MIS) lobectomy. SUMMARY BACKGROUND DATA: Although MIS is associated with better postoperative outcomes than open surgery, MIS uses risk-assessment algorithms developed for open surgery. Moreover, several different definitions of cardiopulmonary complications are used for assessment. METHODS: All patients who underwent MIS lobectomy for clinical stage I-II lung cancer from 2018 to 2022 at our institution were considered. The performance of a ppoFEV1/ppoDLCO threshold of <45% was compared against that of the current guideline threshold of <60%. Three different definitions of cardiopulmonary complications were compared: Society of Thoracic Surgeons (STS), European Society of Thoracic Surgeons (ESTS), and Berry et al. RESULTS: In 946 patients, the ppoFEV1/ppoDLCO threshold of <45% was associated with a higher proportion correctly classified (79% [95% CI, 76%-81%] vs. 65% [95% CI, 62%-68%]; P<0.001). The complication with the biggest difference in incidence between ppoFEV1/ppoDLCO of 45%-60% and >60% was prolonged air leak (33 [13%] vs. 34 [6%]; P<0.001). The predicted probability curves for cardiopulmonary complications were higher for the STS definition than for the ESTS or Berry definitions across ppoFEV1 and ppoDLCO values. CONCLUSIONS: The ppoFEV1/ppoDLCO threshold of <45% more accurately classified patients for cardiopulmonary complications after MIS lobectomy, emphasizing the need for updated risk-assessment guidelines for MIS lobectomy to optimize additional cardiopulmonary function evaluation.

16.
Am J Surg Pathol ; 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38726899

RESUMO

The role of Human papillomavirus (HPV) infection in esophageal squamous cell carcinoma (ESCC) is a topic of ongoing debate. This study used two screening approaches to look for evidence of HPV infection in esophageal squamous cell carcinoma. We initially checked for HPV infection in a randomly selected group of 53 ESCC cases. We did not detect any tumors positive for high-risk HPV. However, during clinical practice, we identified an HPV-positive ESCC in the distal esophagus, which tested positive for HPV16. This index case was TP53 wild-type, as determined by next-generation DNA sequencing (NGS). Since TP53 mutations are rare in other HPV-driven cancers, we improved our screening method by limiting our screen to a subset of ESCC cases without TP53 mutations. A second screen of 95 ESCCs (from 93 patients) sequenced by NGS revealed an additional 7 ESCCs with TP53 wild-type status (7.3% of the total). Of the 7 cases, 2 cases were found to be high-risk HPV positive. Both patients also tested positive for circulating cell-free HPV DNA and had a complete response to neoadjuvant chemoradiation. The index patient had microscopic residual tumor following neoadjuvant therapy. The patient underwent adjuvant immunotherapy and remained disease free after 22 months of surveillance. This study affirms the transcriptionally active status of high-risk HPV in a minority of ESCC patients in North America.

17.
Mol Cancer Ther ; 2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38710101

RESUMO

PURPOSE: Oncolytic virotherapy or immunovirotherapy is a strategy that utilizes viruses to selectively infect and kill tumor cells while also stimulating an immune response against the tumor. Early clinical trials in both pediatric and adult patients using oncolytic herpes simplex viruses (oHSVs) have demonstrated safety and promising efficacy; however, combinatorial strategies designed to enhance oncolysis while also promoting durable T cell responses for sustaining disease remission are likely required. We hypothesized that combining the direct tumor cell killing and innate immune stimulation by oHSV with a vaccine that promotes T cell mediated immunity may lead to more durable tumor regression. EXPERIMENTAL DESIGN: To this end, we investigated the preclinical efficacy and potential synergy of combining oHSV with a self-assembling nanoparticle vaccine co-delivering peptide antigens and Toll-like receptor-7 and -8 agonists (TLR-7/8a) (referred to as SNAPvax™), that induces robust tumor specific T cell immunity. We then assessed how timing of the treatments (i.e., vaccine before or after oHSV) impacts T cell responses, viral replication, and preclinical efficacy. RESULTS: The sequence of treatments was critical, as survival was significantly enhanced when the SNAPvax™ vaccine was given prior to oHSV. Increased clinical efficacy was associated with reduced tumour volume and increases in virus replication and tumor antigen specific CD8+ T cells. CONCLUSIONS: These findings substantiate the criticality of combination immunotherapy timing and provide preclinical support for combining SNAPvax with oHSV as a promising treatment approach for both pediatric and adult tumors.

18.
Ecology ; : e4314, 2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38710667

RESUMO

Warming temperatures are altering communities and trophic networks across Earth's ecosystems. While the overall influence of warming on food webs is often context-dependent, increasing temperatures are predicted to change communities in two fundamental ways: (1) by reducing average body size and (2) by increasing individual metabolic rates. These warming-induced changes have the potential to influence the distribution of food web fluxes, food web stability, and the relative importance of deterministic and stochastic ecological processes shaping community assembly. Here, we quantified patterns and the relative distribution of organic matter fluxes through stream food webs spanning a broad natural temperature gradient (5-27°C). We then related these patterns to species and community trait distributions of mean body size and population biomass turnover (P:B) within and across streams. We predicted that (1) communities in warmer streams would exhibit smaller body size and higher P:B and (2) organic matter fluxes within warmer communities would increasingly skew toward smaller, higher P:B populations. Across the temperature gradient, warmer communities were characterized by smaller body size (~9% per °C) and higher P:B (~7% faster turnover per °C) populations on average. Additionally, organic matter fluxes within warmer streams were increasingly skewed toward higher P:B populations, demonstrating that warming can restructure organic matter fluxes in both an absolute and relative sense. With warming, the relative distribution of organic matter fluxes was decreasingly likely to arise through the random sorting of species, suggesting stronger selection for traits driving high turnover with increasing temperature. Our study suggests that a warming world will favor energy fluxes through "smaller and faster" populations, and that these changes may be more predictable than previously thought.

20.
PLoS One ; 19(5): e0302778, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38713687

RESUMO

INTRODUCTION: Magnetic resonance-guided focused ultrasound (MRgFUS) has been demonstrated to be able to thermally ablate tendons with the aim to non-invasively disrupt tendon contractures in the clinical setting. However, the biomechanical changes of tendons permitting this disrupting is poorly understood. We aim to obtain a dose-dependent biomechanical response of tendons following magnetic resonance-guided focused ultrasound (MRgFUS) thermal ablation. METHODS: Ex vivo porcine tendons (n = 72) were embedded in an agar phantom and randomly assigned to 12 groups based on MRgFUS treatment. The treatment time was 10, 20, or 30s, and the applied acoustic power was 25, 50, 75, or 100W. Following each MRgFUS treatment, tendons underwent biomechanical tensile testing on an Instron machine, which calculated stress-strain curves during tendon elongation. Rupture rate, maximum treatment temperature, Young's modulus and ultimate strength were analyzed for each treatment energy. RESULTS: The study revealed a dose-dependent response, with tendons rupturing in over 50% of cases when energy delivery exceeded 1000J and 100% disruption at energy levels beyond 2000J. The achieved temperatures during MRgFUS were directly proportional to energy delivery. The highest recorded temperature was 56.8°C ± 9.34 (3000J), while the lowest recorded temperate was 18.6°C ± 0.6 (control). The Young's modulus was highest in the control group (47.3 MPa ± 6.5) and lowest in the 3000J group (13.2 MPa ± 5.9). There was no statistically significant difference in ultimate strength between treatment groups. CONCLUSION: This study establishes crucial thresholds for reliable and repeatable disruption of tendons, laying the groundwork for future in vivo optimization. The findings prompt further exploration of MRgFUS as a non-invasive modality for tendon disruption, offering hope for improved outcomes in patients with musculotendinous contractures.


Assuntos
Ablação por Ultrassom Focalizado de Alta Intensidade , Tendões , Animais , Suínos , Tendões/cirurgia , Tendões/fisiologia , Tendões/diagnóstico por imagem , Fenômenos Biomecânicos , Ablação por Ultrassom Focalizado de Alta Intensidade/métodos , Imageamento por Ressonância Magnética/métodos , Resistência à Tração , Módulo de Elasticidade
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