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Previous studies have suggested a negative impact of steroids on the efficacy of immune checkpoint inhibitors (ICI), but how this effect is modulated by the dosage and time of administration is yet to be clarified. We have performed a retrospective analysis of 475 patients with advanced solid tumors treated with ICI as monotherapy from 2015 to 2022. Data regarding immune-related adverse events (irAEs) and clinical outcomes were collected. For each patient, the daily steroid dose (in mg/kg of prednisone) was registered until disease progression or death. The impact of cumulative doses on response rates and survival outcomes was analyzed within different periods. The objective response rate (ORR) was significantly lower among patients exposed to steroids within 30 days before the first cycle of ICI (C1) (20.3% vs. 36.7%, p < 0.01) and within the first 90 days of treatment (25.7% vs. 37.7%, p = 0.01). This negative association was confirmed by multivariable analysis. Higher mean steroid doses were observed among non-responders, and cumulative doses were inversely correlated with the disease control rate (DCR) around ICI initiation. Remarkably, poorer outcomes were observed even in patients belonging to the lowest dose quartile compared to the steroid-naïve population. The exposure to steroids after 6 months of ICI was not associated with worse survival outcomes. Our results suggest that the potential impact of steroids on ICI efficacy may be time-dependent, prevailing around ICI initiation, and dose-dependent, with modulation of neutrophil-to-lymphocyte ratio as a possible underlying mechanism.
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Inhibidores de Puntos de Control Inmunológico , Neoplasias , Humanos , Masculino , Femenino , Neoplasias/tratamiento farmacológico , Neoplasias/inmunología , Neoplasias/mortalidad , Persona de Mediana Edad , Estudios Retrospectivos , Anciano , Inhibidores de Puntos de Control Inmunológico/uso terapéutico , Inhibidores de Puntos de Control Inmunológico/efectos adversos , Inmunoterapia/métodos , Adulto , Esteroides/uso terapéutico , Esteroides/administración & dosificación , Relación Dosis-Respuesta a Droga , Anciano de 80 o más Años , Factores de TiempoRESUMEN
Background: A circadian rhythm of myocardial infarction has been described but there is little data on its relation with seasons and months. Methods: From June 2013 to June 2018, we analyzed the alerts for acute ST-segment elevation myocardial infarction (STEMI) in a Spanish region with 6.64 million inhabitants, universal health coverage, and an organized STEMI reperfusion network. We selected those patients which an identifiable culprit plaque. Results: We recruited 6765 cases of STEMI due to type I acute myocardial infarction (type-I AMI), with mean age of 63.2 years (range 17-101, standard deviation [SD] 13.7), 5238 were males (77.4%) and 2801 (41.9%) were 65 years or older. The hourly distribution followed a fixed pattern in all months, with most of the events occurring between 6:00 AM and 4:00 PM, a peak at approximately 01:00 PM and a valley between 10:00 PM and 06:00 AM. No significant difference was found when comparing the mean time to first medical contact between July (the month with more daylight hours) and December (the month with shortest days). No significant differences were found between male and female patients, or between patients aged 65 years or older and younger patients. There was a close correlation between the number of events per month and the number of events occurring during the day (6 AM to 6 PM, r = 0.988, p = 0.001) and during the night (6 PM to 6 AM, r = 0.944, p < 0.001), with different slopes of the regression lines (t-test, p < 0.001), so that the difference between day-night occurrences increased with the total incidence. Conclusions: There is a circadian pattern in the presentation of STEMI that is not influenced by sex and age. The different incidence of STEMI at different times of the year does not affect the circadian pattern in terms of the shape of the curve or the mean time of presentation, although diurnal events increase more than nocturnal events, suggesting that triggers are most likely to act during vulnerable periods as determined by a circadian-based rhythm.
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PURPOSE: The aim of this study was to evaluate the 3-year clinical results of Bowman layer with stromal inclusion (Bowman layer) transplantation using femtosecond laser for patients with advanced keratoconus. METHODS: This single-center retrospective study included 7 eyes of 7 patients diagnosed with progressive keratoconus who underwent Bowman layer transplantation with stromal inclusion between 2018 and 2020. Follow-up was carried out from the date of surgery until 36 months later. Bowman layer grafts were positioned into a mid-stromal pocket performed by a femtosecond laser and patients were evaluated up to 3 years after surgery. RESULTS: Corneal flattening of 5.49 D (P = 0.0020) in Kmax was observed, increased in corneal pachymetry, and an improvement best-corrected visual acuity measured in logarithm of minimum angle of resolution (LogMAR) from 0.89 to 0.60 and tolerance to contact lens from 42% of the patients to 100% of them. Stabilization of the cornea was achieved in 100% with no further progression of the keratoconus; all surgical procedures were uneventful, and no complications were observed during the 3 years of follow-up. CONCLUSIONS: Bowman layer transplantation with stromal inclusion flattened the cornea improving best-corrected visual acuity and contact lens tolerance and stabilized keratoconus in 100% of the patients during 3 years of follow-up and may be a feasible option in patients with advanced and progressive KC to delay or avoid the need for PK or DALK.
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Lignocellulosic material is a leading carbon source for economically viable biotechnological processes; however, compounds such furfural and acetic acid exhibit toxicity to yeasts. Nonetheless, research about the molecular mechanism of furfural and acetic acid toxicity is still scarce in yeasts like Scheffersomyces stipitis. Thus, this study aims to elucidate the impact of furfural and acetic acid on S. stipitis regarding bioenergetic and fermentation parameters. Here, we provide evidence that furfural and acetic acid induce a delay in cell growth and extend the lag phase. The mitochondrial membrane potential decreased in all treatments with no significant differences between inhibitors or concentrations. Interestingly, reactive oxygen species increased when the inhibitor concentrations were from 0.1 to 0.3 % (v/v). The glycolytic flux was not significantly (p > 0.05) altered by acetic acid, but furfural caused different effects. Ethanol production decreased significantly (4.32 g·L-1 in furfural and 5.06 g·L-1 in acetic acid) compared to the control (26.3 g·L-1). In contrast, biomass levels were not significantly different in most treatments compared to the control. This study enhances our understanding of the effects of furfural and acetic acid at the mitochondrial level in a pentose-fermenting yeast like S. stipitis.
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Rhodosporidium toruloides has emerged as an excellent option for microbial lipid production due to its ability to accumulate up to 70â¯% of lipids per cell dry weight, consume multiple substrates such as glucose and xylose, and tolerate toxic compounds. Despite the potential of Rhodosporidium toruloides for high lipid yields, achieving these remains is a significant hurdle. A comprehensive review is essential to thoroughly evaluate the advancements in processes and technologies to enhance lipid production in R. toruloides. The review covers various strategies for enhancing lipid production like co-culture, adaptive evolution, carbon flux analysis, as well as different modes of fermentation. This review will help researchers to better understand the recent developments in technologies for sustainable and scalable lipid production from R. toruloides and simultaneously emphasize the need for developing an efficient and sustainable bioprocess.
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The integration of artificial intelligence (AI) with healthcare has opened new avenues for diagnosing, treating, and managing medical conditions with remarkable precision. Uveitis, a diverse group of rare eye conditions characterized by inflammation of the uveal tract, exemplifies the complexities in ophthalmology due to its varied causes, clinical presentations, and responses to treatments. Uveitis, if not managed promptly and effectively, can lead to significant visual impairment. However, its management requires specialized knowledge, which is often lacking, particularly in regions with limited access to health services. AI's capabilities in pattern recognition, data analysis, and predictive modelling offer significant potential to revolutionize uveitis management. AI can classify disease etiologies, analyze multimodal imaging data, predict outcomes, and identify new therapeutic targets. However, transforming these AI models into clinical applications and meeting patient expectations involves overcoming challenges like acquiring extensive, annotated datasets, ensuring algorithmic transparency, and validating these models in real-world settings. This review delves into the complexities of uveitis and the current AI landscape, discussing the development, opportunities, and challenges of AI from theoretical models to bedside application. It also examines the epidemiology of uveitis, the global shortage of uveitis specialists, and the disease's socioeconomic impacts, underlining the critical need for AI-driven approaches. Furthermore, it explores the integration of AI in diagnostic imaging and future directions in ophthalmology, aiming to highlight emerging trends that could transform management of a patient with uveitis and suggesting collaborative efforts to enhance AI applications in clinical practice.
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INTRODUCTION: cancer and its treatments have been associated with poor nutritional status in children and adolescents. OBJECTIVE: to establish the nutritional risk of pediatric patients and the degree of food and nutritional insecurity in the homes of children and adolescents with cancer who have been hospitalized in a high complexity pediatric oncology center. METHODS: a prospective observational study conducted at the Fundación Hospital Pediátrico la Misericordia - HOMI. It included a sample of 41 children and adolescents aged 0 to 17 years and 11 months with a diagnosis of childhood cancer during the study period. The participants recruited during hospitalization had the application of the SCAN nutritional screening tool for childhood cancer, Spanish version, validated in HOMI and the Latin American and Caribbean Scale of Food and Nutritional Security - ELCSA, adapted and validated in Colombia. RESULTS: 76 % (n = 31) of the patients were classified as "At risk of malnutrition" using the SCAN-SP nutritional screening tool. It was observed that 56 % of all households had a proportion of food insecurity, of which the classification of food (in)security was mild in 29 %, moderate in 20 % and severe in 7 % of households with children under 18 years of age. CONCLUSION: in the framework of the nutritional care process, it is important to take into account factors that include a complete nutritional risk assessment and evaluation that includes the measurement of food security.
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BACKGROUND: Penetrating thoracic injuries have a significant risk of morbi-mortality. Despite the advancements in damage control methods, a subset of patients with severe pulmonary vascular lesions and bronchial injuries persists. In some of these cases, post-traumatic pneumonectomy is required, and perioperative extracorporeal membrane oxygenation (ECMO) support may be required due to right ventricular failure and respiratory failure. CASE DESCRIPTION: A male was brought to the emergency department (ED) with a penetrating thoracic injury, presenting with massive right hemothorax and active bleeding that required ligation of the right pulmonary hilum to control the bleeding. Subsequently, he developed right ventricular dysfunction and ARDS, necessitating a dynamic hybrid ECMO configuration to support his condition and facilitate recovery. CONCLUSIONS: Penetrating thoracic injuries with severe pulmonary vascular lesions may need pneumonectomy to control bleeding. ECMO support reduces the associated mortality by decreasing the complications rate. A multidisciplinary team is essential to achieve good outcomes in severe compromised patients.
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Oxigenación por Membrana Extracorpórea , Neumonectomía , Humanos , Oxigenación por Membrana Extracorpórea/métodos , Masculino , Lesión Pulmonar/cirugía , Lesión Pulmonar/etiología , Adulto , Traumatismos Torácicos/cirugía , Traumatismos Torácicos/complicaciones , Heridas Penetrantes/cirugía , Hemotórax/etiología , Hemotórax/cirugía , Cuidados Posoperatorios/métodosRESUMEN
CLINICAL RELEVANCE: Glaucoma encompasses a group of eye diseases that progressively damage the optic nerve, leading to vision loss and blindness. Understanding the incidence and demographic distribution is vital for public health planning and patient care. BACKGROUND: Previous small-scale studies in Colombia have reported the prevalence of glaucoma in individuals over 40 years between 1.1% and 5.29%. These data may not fully capture the true extent of the disease. Furthermore, with the ageing population, the incidence of glaucoma is likely to increase, highlighting the need for up-to-date incidence data to guide healthcare planning. METHODS: Data were obtained from the Social Protection Information System, the primary health record repository of Colombia, using the International Classification of Disease 10 for glaucoma. Crude incidence rates were calculated and adjusted for sex, age, and gender. The 2020 incidence was compared with estimated rates from previous years to assess the impact of the coronavirus disease 2019 lockdown. A standardised morbidity map was created to show regional variations. RESULTS: The average incidence of glaucoma in Colombia was 17.36 per 1,000 inhabitants, increasing from 12.29 in 2015 to 24.22 in 2019. Of the 212,700 reported cases, 60.75% were females. Primary open-angle glaucoma was the most prevalent type, with significant incidence in the elderly over 70 years of age, irrespective of sex. Bogotá, Antioquia, and Valle del Cauca had the highest numbers of new cases. CONCLUSION: The increasing incidence of glaucoma and its demographic and geographical variations necessitate the awareness of ophthalmologists and optometrists. This study emphasises the need for continuous monitoring, effective interventions, and developing healthcare strategies to address the escalating challenge of glaucoma in Colombia.
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PURPOSE: To synthesize the evidence and generate a combined weighted measure on the frequency of ocular manifestations of mucous membrane pemphigoid (OMMP). METHODS: Systematic literature review and meta-analysis, searching PubMed, Embase, VHL, and Google Scholar. Articles reporting patients with mucous membrane pemphigoid and ocular involvement were included. At least, two reviewers independently and in parallel participated in all the following phases; preliminary screening, full-text review, risk of bias assessment by validated tools, and data extraction. Qualitative analysis and meta-analysis were conducted. This study was previously registered in PROSPERO (CRD42023451844). RESULTS: Thirty-five studies met the inclusion criteria, comprising 1,439 patients and 1,040 eyes summarized in qualitative analysis. Twenty-eight studies were included in the meta-analysis. Ages included ranged from 60.4 to 75 years. Women were reported with more frequency. The mean time for diagnosis was 55.1 months, usually with bilateral ocular disease in 90% (95% CI 78%; 96%). Trichiasis and entropion were the most frequent manifestations in up to 92%, followed by symblepharon and punctate keratitis. Ankyloblepharon, persistent epithelial defects, and visual impairment were less frequent complications. Direct immunofluorescence positivity in conjunctival biopsies was 54% (95% CI 43%; 64%). Extraocular involvement was highly frequent, being oral and skin involvement the most frequently reported. CONCLUSIONS: Our systematic review and meta-analysis evidenced that patients around 60 years of age are the most affected population with a female preponderance, usually with bilateral ocular involvement. Trichiasis and entropion were the most frequent findings; although visual impairment and persistent epithelial defects were less reported, they should not be overlooked in suspected OMMP.
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Natural Language Processing (NLP) is a subfield of artificial intelligence that focuses on the interaction between computers and human language, enabling computers to understand, generate, and derive meaning from human language. NLP's potential applications in the medical field are extensive and vary from extracting data from Electronic Health Records -one of its most well-known and frequently exploited uses- to investigating relationships among genetics, biomarkers, drugs, and diseases for the proposal of new medications. NLP can be useful for clinical decision support, patient monitoring, or medical image analysis. Despite its vast potential, the real-world application of NLP is still limited due to various challenges and constraints, meaning that its evolution predominantly continues within the research domain. However, with the increasingly widespread use of NLP, particularly with the availability of large language models, such as ChatGPT, it is crucial for medical professionals to be aware of the status, uses, and limitations of these technologies.
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OBJECTIVE: Patients with alcohol-associated hepatitis (AH) have a high mortality. Alcohol exacerbates liver damage by inducing gut dysbiosis, bacterial translocation and inflammation, which is characterised by increased numbers of circulating and hepatic neutrophils. DESIGN: In this study, we performed tandem mass tag (TMT) proteomics to analyse proteins in the faeces of controls (n=19), patients with alcohol-use disorder (AUD; n=20) and AH (n=80) from a multicentre cohort (InTeam). To identify protein groups that are disproportionately represented, we conducted over-representation analysis using Reactome pathway analysis and Gene Ontology to determine the proteins with the most significant impact. A faecal biomarker and its prognostic effect were validated by ELISA in faecal samples from patients with AH (n=70), who were recruited in a second and independent multicentre cohort (AlcHepNet). RESULT: Faecal proteomic profiles were overall significantly different between controls, patients with AUD and AH (principal component analysis p=0.001, dissimilarity index calculated by the method of Bray-Curtis). Proteins that showed notable differences across all three groups and displayed a progressive increase in accordance with the severity of alcohol-associated liver disease were predominantly those located in neutrophil granules. Over-representation and Reactome analyses confirmed that differentially regulated proteins are part of granules in neutrophils and the neutrophil degranulation pathway. Myeloperoxidase (MPO), the marker protein of neutrophil granules, correlates with disease severity and predicts 60-day mortality. Using an independent validation cohort, we confirmed that faecal MPO levels can predict short-term survival at 60 days. CONCLUSIONS: We found an increased abundance of faecal proteins linked to neutrophil degranulation in patients with AH, which is predictive of short-term survival and could serve as a prognostic non-invasive marker.
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Cloudy conditions at a local scale pose a significant challenge for forecasting renewable energy generation through photovoltaic panels. Consequently, having real-time knowledge of sky conditions becomes highly valuable. This information could inform decision-making processes in system operations, such as determining whether conditions are favorable for activating a standalone system requiring a minimum level of radiation or whether sky conditions might lead to higher energy consumption than generation during adverse cloudy conditions. This research leveraged convolutional neural networks (CNNs) and transfer learning (TL) classification techniques, testing various architectures from the EfficientNet family and two ResNet models for classifying sky images. Cross-validation methods were applied across different experiments, where the most favorable outcome was achieved with the EfficientNetV2-B1 and EfficientNetV2-B2 models boasting a mean Accuracy of 98.09%. This study underscores the efficacy of the architectures employed for sky image classification, while also highlighting the models yielding the best results.
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BACKGROUND: Late hemothorax is a rare complication of blunt chest trauma. The longest reported time interval between the traumatic event and the development of hemothorax is 44 days. CASE PRESENTATION: An elderly patient with right-sided rib fractures from chest trauma, managed initially with closed thoracostomy, presented with a delayed hemothorax that occurred 60 days after initial management, necessitating conservative and then surgical intervention due to the patient's frail condition and associated complications. CONCLUSIONS: This case emphasizes the clinical challenge and significance of delayed hemothorax in chest trauma, highlighting the need for vigilance and potential surgical correction in complex presentations, especially in the elderly.
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Hemotórax , Fracturas de las Costillas , Traumatismos Torácicos , Heridas no Penetrantes , Humanos , Hemotórax/etiología , Hemotórax/cirugía , Heridas no Penetrantes/complicaciones , Traumatismos Torácicos/complicaciones , Fracturas de las Costillas/complicaciones , Fracturas de las Costillas/cirugía , Masculino , Toracostomía , Factores de Tiempo , Anciano de 80 o más Años , Tomografía Computarizada por Rayos X , AncianoRESUMEN
BACKGROUND: To report a case of coinfection of Toxoplasma gondii (Tg) and Epstein Barr Virus (EBV) in a diabetic patient with rheumatoid arthritis and immunosuppressive biological therapy. CASE PRESENTATION: A 70-year-old female with a history of rheumatoid arthritis on therapy with corticosteroids, methotrexate, and abatacept presented bilateral granulomatous panuveitis associated with retinal necrosis and macular involvement. A diagnostic vitrectomy detected Tg and EBV. Treatment with clindamycin, trimethoprim-sulfamethoxazole, and acyclovir was established, achieving improvement. CONCLUSIONS: Patients undergoing immunosuppressive therapy are at risk of developing opportunistic infections, often presenting with severe and atypical clinical manifestations. In such cases, multiplex polymerase chain reaction is an invaluable diagnostic tool that helps identify the specific pathogens involved. This enables healthcare professionals to make informed treatment decisions and provide targeted therapy for each identified pathogen.
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BACKGROUND: The VPS50 protein functions in synaptic and dense core vesicle acidification, and perturbations of VPS50 function produce behavioral changes in Caenorhabditis elegans. Patients with mutations in VPS50 show severe developmental delay and intellectual disability, characteristics that have been associated with autism spectrum disorders (ASDs). The mechanisms that link VPS50 mutations to ASD are unknown. RESULTS: To examine the role of VPS50 in mammalian brain function and behavior, we used the CRISPR/Cas9 system to generate knockouts of VPS50 in both cultured murine cortical neurons and living mice. In cultured neurons, KO of VPS50 did not affect the number of synaptic vesicles but did cause mislocalization of the V-ATPase V1 domain pump and impaired synaptic activity, likely as a consequence of defects in vesicle acidification and vesicle content. In mice, mosaic KO of VPS50 in the hippocampus altered synaptic transmission and plasticity and generated robust cognitive impairments. CONCLUSIONS: We propose that VPS50 functions as an accessory protein to aid the recruitment of the V-ATPase V1 domain to synaptic vesicles and in that way plays a crucial role in controlling synaptic vesicle acidification. Understanding the mechanisms controlling behaviors and synaptic function in ASD-associated mutations is pivotal for the development of targeted interventions, which may open new avenues for therapeutic strategies aimed at ASD and related conditions.
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Ratones Noqueados , Vesículas Sinápticas , Animales , Ratones , Conducta Animal/fisiología , Encéfalo/metabolismo , Neuronas/metabolismo , Neuronas/fisiología , Sinapsis/metabolismo , Sinapsis/fisiología , Transmisión Sináptica , Vesículas Sinápticas/metabolismo , ATPasas de Translocación de Protón Vacuolares/metabolismo , ATPasas de Translocación de Protón Vacuolares/genética , Proteínas de Transporte Vesicular/genética , Proteínas de Transporte Vesicular/metabolismoRESUMEN
BACKGROUND: The brain cortex is responsible for many higher-level cognitive functions. Disruptions during cortical development have long-lasting consequences on brain function and are associated with the etiology of brain disorders. We previously found that the protein tyrosine phosphatase receptor delta Ptprd, which is genetically associated with several human neurodevelopmental disorders, is essential to cortical brain development. Loss of Ptprd expression induced an aberrant increase of excitatory neurons in embryonic and neonatal mice by hyper-activating the pro-neurogenic receptors TrkB and PDGFRß in neural precursor cells. However, whether these alterations have long-lasting consequences in adulthood remains unknown. RESULTS: Here, we found that in Ptprd+/- or Ptprd-/- mice, the developmental increase of excitatory neurons persists through adulthood, affecting excitatory synaptic function in the medial prefrontal cortex. Likewise, heterozygosity or homozygosity for Ptprd also induced an increase of inhibitory cortical GABAergic neurons and impaired inhibitory synaptic transmission. Lastly, Ptprd+/- or Ptprd-/- mice displayed autistic-like behaviors and no learning and memory impairments or anxiety. CONCLUSIONS: These results indicate that loss of Ptprd has long-lasting effects on cortical neuron number and synaptic function that may aberrantly impact ASD-like behaviors.
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Trastorno Autístico , Neuronas , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores , Animales , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/metabolismo , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/genética , Ratones , Trastorno Autístico/genética , Trastorno Autístico/fisiopatología , Modelos Animales de Enfermedad , Masculino , Corteza Cerebral/metabolismo , Ratones Noqueados , Transmisión Sináptica/fisiología , Ratones Endogámicos C57BL , FemeninoRESUMEN
AIMS: Pannexin-1 (PANX1) is a hemichannel that releases ATP upon opening, initiating inflammation, cell proliferation, and migration. However, the role of PANX1 channels in colon cancer remains poorly understood, thus constituting the focus of this study. MAIN METHODS: PANX1 mRNA expression was analyzed using multiple cancer databases. PANX1 protein expression and distribution were evaluated by immunohistochemistry on primary tumor tissue and non-tumor colonic mucosa from colon cancer patients. PANX1 inhibitors (probenecid or 10Panx) were used to assess colon cancer cell lines viability. To study the role of PANX1 in vivo, a subcutaneous xenograft model using HCT116 cells was performed in BALB/c NOD/SCID immunodeficient mice to evaluate tumor growth under PANX1 inhibition using probenecid. KEY FINDINGS: PANX1 mRNA was upregulated in colon cancer tissue compared to non-tumor colonic mucosa. Elevated PANX1 mRNA expression in tumors correlated with worse disease-free survival. PANX1 protein abundance was increased on tumor cells compared to epithelial cells in paired samples, in a cancer stage-dependent manner. In vitro and in vivo experiments indicated that blocking PANX1 reduced cell viability and tumor growth. SIGNIFICANCE: PANX1 can be used as a biomarker of colon cancer progression and blocking PANX1 channel opening could be used as a potential therapeutic strategy against this disease.
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Neoplasias del Colon , Conexinas , Progresión de la Enfermedad , Proteínas del Tejido Nervioso , Animales , Femenino , Humanos , Masculino , Ratones , Biomarcadores de Tumor/metabolismo , Biomarcadores de Tumor/genética , Línea Celular Tumoral , Proliferación Celular , Supervivencia Celular , Neoplasias del Colon/patología , Neoplasias del Colon/metabolismo , Neoplasias del Colon/genética , Conexinas/metabolismo , Conexinas/genética , Regulación Neoplásica de la Expresión Génica , Células HCT116 , Ratones Endogámicos BALB C , Ratones Endogámicos NOD , Ratones SCID , Proteínas del Tejido Nervioso/metabolismo , Proteínas del Tejido Nervioso/genética , Probenecid/farmacología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Recent findings in cell biology have rekindled interest in Z-DNA, the left-handed helical form of DNA. We report here that two minimally modified nucleosides, 2'F-araC and 2'F-riboG, induce the formation of the Z-form under low ionic strength. We show that oligomers entirely made of these two nucleosides exclusively produce left-handed duplexes that bind to the Zα domain of ADAR1. The effect of the two nucleotides is so dramatic that Z-form duplexes are the only species observed in 10 mM sodium phosphate buffer and neutral pH, and no B-form is observed at any temperature. Hence, in contrast to other studies reporting formation of Z/B-form equilibria by a preference for purine glycosidic angles in syn, our NMR and computational work revealed that sequential 2'F H2N and intramolecular 3'H N3' interactions stabilize the left-handed helix. The equilibrium between B- and Z- forms is slow in the 19F NMR time scale (≥ms), and each conformation exhibited unprecedented chemical shift differences in the 19F signals. This observation led to a reliable estimation of the relative population of B and Z species and enabled us to monitor B-Z transitions under different conditions. The unique features of 2'F-modified DNA should thus be a valuable addition to existing techniques for specific detection of new Z-binding proteins and ligands.
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ADN de Forma Z , Conformación de Ácido Nucleico , ADN de Forma Z/química , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/metabolismo , Halogenación , Adenosina Desaminasa/química , Adenosina Desaminasa/metabolismo , Concentración Osmolar , Resonancia Magnética Nuclear Biomolecular , ADN Forma B/química , Modelos Moleculares , ADN/química , ADN/metabolismoRESUMEN
Bioabsorbable Mg wire-reinforced poly-lactic acid (PLA) matrix composites are potential candidate for load-bearing orthopedic implants offering tailorable mechanical and degradation properties by stacking sequence, volume fraction and surface modification of Mg wires. In this study, we investigated the cytocompatibility, cell-material interaction, and bone differentiation behavior of MC3T3-E1 pre-osteoblast cells for medical-grade PLA, Mg/PLA, and PEO-Mg/PLA (having PEO surface modification on Mg wires) composites. MTT and live/dead assay showed excellent biocompatibility of both composites while cell-material interaction analysis revealed that cells were able to adhere and proliferate on the surface of composites. Cells on the longitudinal surface of composites showed a high and uniform cell density while those on transversal surfaces initially avoided Mg regions but later migrated back after the formation of the passivation layer. Bone differentiation tests showed that cells in extracts of PLA and composites were able to initiate the differentiation process as osteogenesis-related gene expressions, alkaline phosphatase protein quantity, and calcium mineralization increased after 7 and 14 days of culture. Interestingly, the bone differentiation response of PEO-Mg/PLA composite was found to be similar to medical-grade PLA, proving its superiority over Mg/PLA composite.