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Molecular simulations enable the prediction of physicochemical properties of mixtures based on pair-interaction models of the pure components and combining rules to describe the unlike interactions. However, if no adjustment to experimental data is made, the existing combining rules often do not yield sufficiently accurate predictions of mixture data. To address this problem, adjustable binary parameters ξij describing the pair interactions in mixtures (i + j) are used. In this work, we present the first method for predicting ξij for unstudied mixtures based on a matrix completion method (MCM) from machine learning (ML). Considering molecular simulations of Henry's law constants as an example, we demonstrate that ξij for unstudied mixtures can be predicted with high accuracy. Using the predicted ξij significantly increases the accuracy of the Henry's law constant predictions compared to using the default ξij = 1. Our approach is generic and can be transferred to molecular simulations of other mixture properties and even to combining rules in equations of state, granting predictive access to the description of unlike intermolecular interactions.
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Highly efficient, biocompatible, and fast nucleic acid delivery methods are essential for biomedical applications and research. At present, two main strategies are used to this end. In non-viral transfection liposome- or polymer-based formulations are used to transfer cargo into cells via endocytosis, whereas viral carriers enable direct nucleic acid delivery into the cell cytoplasm. Here, we introduce a new generation of liposomes for nucleic acid delivery, which immediately fuse with the cellular plasma membrane upon contact to transfer the functional nucleic acid directly into the cell cytoplasm. For maximum fusion efficiency combined with high cargo transfer, nucleic acids had to be complexed and partially neutralized before incorporation into fusogenic liposomes. Among the various neutralization agents tested, small, linear, and positively charged polymers yielded the best complex properties. Systematic variation of liposomal composition and nucleic acid complexation identified surface charge as well as particle size as essential parameters for cargo-liposome interaction and subsequent fusion induction. Optimized protocols were tested for the efficient transfer of different kinds of nucleic acids like plasmid DNA, messenger RNA, and short-interfering RNA into various mammalian cells in culture and into primary tissues.
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Liposomas/química , Transfección/métodos , Animales , Células CHO , Cricetinae , Cricetulus , Fusión de Membrana , Ácidos Nucleicos/química , Ácidos Nucleicos/genética , Electricidad Estática , Transfección/normasRESUMEN
Adoptive cell therapies are showing very promising results in the fight against cancer. However, these therapies are expensive and technically challenging in part due to the need of a large number of specific T cells, which must be activated and expanded in vitro. Here we describe a method to activate primary human T cells using a combination of nanostructured surfaces functionalized with the stimulating anti-CD3 antibody and the peptidic sequence arginine-glycine-aspartic acid, as well as costimulatory agents (anti-CD28 antibody and a cocktail of phorbol 12-myristate 13-acetate, ionomycin, and protein transport inhibitors). Thus, we propose a method that combines nanotechnology with cell biology procedures to efficiently produce T cells in the laboratory, challenging the current state-of-the-art expansion methodologies.
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Materiales Biocompatibles Revestidos/química , Activación de Linfocitos , Nanoestructuras/química , Linfocitos T/inmunología , Anticuerpos Inmovilizados/química , Anticuerpos Inmovilizados/inmunología , Antígenos CD28/inmunología , Complejo CD3/inmunología , Adhesión Celular , Células Cultivadas , Oro/química , Humanos , Inmunoterapia Adoptiva , Ionomicina/química , Ionomicina/inmunología , Nanoestructuras/ultraestructura , Oligopéptidos/química , Oligopéptidos/inmunología , Propiedades de Superficie , Linfocitos T/citología , Acetato de Tetradecanoilforbol/química , Acetato de Tetradecanoilforbol/inmunología , Titanio/químicaRESUMEN
Pharmacogenetic variants of the steroid hormone-metabolizing enzyme cytochrome P450 2B6 (CYP2B6) were reported to be associated with breast cancer (BC) risk and prognosis. CYP2B6 expression is inducible by estradiol (E2) but induction was demonstrated only under steroid hormone-deprived medium conditions. Physiological conditions, however, even under endocrinological BC treatment, do not correspond to complete steroid hormone depletion. The aim of this study was to investigate the E2-mediated CYP2B6 and CYP1B1 regulation under various steroid hormone conditions, including physiological concentrations, in human oestrogen receptor positive (T47D, MCF-7) and negative (MDA-MB-231) BC cell lines. We confirm that steroid-deprived pre-cultivation led to CYP2B6 upregulation in T47D, but not in MCF-7. However, when pre-cultivated with steroid-containing medium CYP2B6 was downregulated in T47D and MCF-7, while the addition of physiological E2 concentrations to steroid-deprived medium resulted in a downregulation in T47D. In contrast, CYP1B1 was never downregulated in any culture condition. Thus, we show that E2-mediated CYP2B6 regulation in BC cells depends on steroid hormone exposure in a cell line-specific manner. Our data indicates the importance of being careful with conclusions drawn from CYP2B6 induction findings in vitro, as we demonstrate potential influences of hormonal changes on CYP2B6 expression, which could impact steroid hormone homeostasis and, consequently, BC risk.
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Background and objective: Hydronephrosis is essential in the diagnosis of renal colic. We automated the detection of hydronephrosis from ultrasound images to standardize the therapy and reduce the misdiagnosis of renal colic. Methods: Anonymously collected ultrasound images of human kidneys, both normal and hydronephrotic, were preprocessed for neural networks. Six "state of the art" models were trained and cross-validated for the detection of hydronephrosis, and two convolutional networks were used for kidney segmentation. In the testing phase, performance metrics included true positives, true negatives, false positives, false negatives, accuracy, and F1 score, while the evaluation of the segmentation task involved accuracy, precision, dice, jaccard, recall, and ASSD. Key findings and limitations: A total of 523 sonographic kidney images (423 nonhydronephrotic and 100 hydronephrotic) were collected from three different ultrasound devices. After training on this dataset, all models were used to evaluate 200 new ultrasound kidney images (142 nonhydronephrotic and 58 hydronephrotic kidneys). The highest validation accuracy (98.5%) was achieved by the AlexNet model (GoogLeNet 97%, AlexNet_v2 96%, ResNet50 96%, ResNet101 97.5%, and ResNet152 95%). The deeplabv3_resnet50 and deeplabv3_resnet101 reached a dice coefficient of 94.74% and 94.48%, respectively, on the task of automated kidney segmentation. The study is limited by analyzing only hydronephrosis, but this specific focus enabled high detection accuracy. Conclusions and clinical implications: We show that our automated ultrasound deep learning model can be trained and used to interpret and segmentate ultrasound images from different sources with high accuracy. This method will serve as an automated tool in the diagnostic algorithm of acute renal failure in the future. Patient summary: Hydronephrosis is crucial in the diagnosis of renal colic. Recent advances in artificial intelligence allow automated detection of hydronephrosis in ultrasound images with high accuracy. These methods will help standardize the diagnosis and treatment renal colic.
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Due to the proliferation-induced high demand of cancer cells for folic acid (FA), significant overexpression of folate receptors 1 (FR1) is detected in most cancers. To our knowledge, a detailed characterization of FR1 expression and regulation regarding therapeutic and diagnostic feasibilities in prostate cancer (PCa) has not been described. In the present study, cell cultures, as well as tissue sections, were analyzed using Western blot, qRT-PCR and immunofluorescence. In addition, we utilized FA-functionalized lipoplexes to characterize the potential of FR1-targeted delivery into PCa cells. Interestingly, we detected a high level of FR1-mRNA in healthy prostate epithelial cells and healthy prostate tissue. However, we were able to show that PCa cells in vitro and PCa tissue showed a massively enhanced FR1 membrane localization where the receptor can finally gain its function. We were able to link these changes to the overexpression of GPI-transamidase (GPI-T) by image analysis. PCa cells in vitro and PCa tissue show the strongest overexpression of GPI-T and thereby induce FR1 membrane localization. Finally, we utilized FA-functionalized lipoplexes to selectively transfer pDNA into PCa cells and demonstrate the therapeutic potential of FR1. Thus, FR1 represents a very promising candidate for targeted therapeutic transfer pathways in PCa and in combination with GPI-T, may provide predictive imaging in addition to established diagnostics.
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The use of artificial intelligence (AI) in urology can contribute to a significant improvement with regard to individualization of diagnostics and therapy as well as healthcare cost reduction. The potential applications and advantages of AI in medicine are often underestimated or incompletely understood. This makes it difficult to conceptually solve relevant medical problems using AI. With current advances in computer science, multiple, highly complex nonmedical processes have already been studied and optimized in an automated fashion. The development of AI models, if applied correctly, can lead to more effective processing and analysis of patient-related data and correspondingly optimized diagnosis and therapy of urological patients. In this review, the current status on the application of AI in medicine and its opportunities and possibilities in urology are presented from a conceptual perspective using practical examples.
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Inteligencia Artificial , Urología , HumanosRESUMEN
Urothelial carcinoma of the upper urinary tract (upper tract urothelial carcinoma, UTUC) is less common than bladder carcinoma with nearly identical risk factors and has a poorer prognosis. The standard diagnostic procedure is imaging of the upper urinary tract by computed tomography urography. In cases of diagnostic uncertainty, a diagnostic ureterorenoscopy with biopsy sampling can be performed in addition to urine cytology. Treatment depends primarily on the stage and grading of the tumor. Depending on the extent and localization, organ-preserving treatment or radical nephroureterectomy is indicated. Perioperative systemic treatment in high-risk UTUC can be performed in both neoadjuvant and adjuvant settings, although the current data on neoadjuvant chemo- and immunotherapy do not yet allow standard application. For metastatic disease, a multimodal treatment approach consisting of cisplatin-based or carboplatin-based chemotherapy, immunotherapy, and treatment with enfortumab vedotin can be considered. Salvage surgery, radiotherapy and metastasectomy are available for rare individual cases.
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Carcinoma de Células Transicionales , Neoplasias de la Vejiga Urinaria , Sistema Urinario , Humanos , Neoplasias de la Vejiga Urinaria/cirugía , Carcinoma de Células Transicionales/diagnóstico , Nefroureterectomía , Sistema Urinario/patología , Terapia CombinadaRESUMEN
The efficient and biocompatible transfer of nucleic acids into mammalian cells for research applications or medical purposes is a long-standing, challenging task. Viral transduction is the most efficient transfer system, but often entails high safety levels for research and potential health impairments for patients in medical applications. Lipo- or polyplexes are commonly used transfer systems but result in comparably low transfer efficiencies. Moreover, inflammatory responses caused by cytotoxic side effects were reported for these transfer methods. Often accountable for these effects are various recognition mechanisms for transferred nucleic acids. Using commercially available fusogenic liposomes (Fuse-It-mRNA), we established highly efficient and fully biocompatible transfer of RNA molecules for in vitro as well as in vivo applications. We demonstrated bypassing of endosomal uptake routes and, therefore, of pattern recognition receptors that recognize nucleic acids with high efficiency. This may underlie the observed almost complete abolishment of inflammatory cytokine responses. RNA transfer experiments into zebrafish embryos and adult animals fully confirmed the functional mechanism and the wide range of applications from single cells to organisms.
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Prostate and breast carcinomas are amongst the most common new diseases in men and women, with steadily rising incidences. In addition to the significant health consequences, both diseases also lead to a significantly reduced quality of life due to their influence on sexual function. The aim of this work is to identify scientific approaches and research priorities that in the future might lead to synergies in both disciplines by specifically considering the similarities and differences between the two diseases. For this purpose, clinically relevant aspects such as risk factors, treatment options, as well as scientific similarities and differences that offer direct joint research approaches in the areas of cultivation and modeling of both tumor entities were analyzed. Through this approach, we were able to demonstrate that due to the comparable biology of the two diseases and the underlying mechanisms, scientific synergies may certainly lead to targeted research. Clinical similarities also indicate that close collaboration between the two disciplines could lead to improved treatment of our patients. Evidence deficiencies in both diseases (e.g. the metastasis mechanisms of both tumor entities) and controversially discussed aspects such as risk factors clearly show that further scientific projects for a more detailed understanding of both diseases are necessary to ensure future success in the treatment of our patients.
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Neoplasias de la Mama , Neoplasias de la Mama/diagnóstico , Femenino , Humanos , Incidencia , Masculino , Próstata/patología , Calidad de VidaRESUMEN
Efficient and reliable transfer of nucleic acids for therapy applications is a major challenge. Stabilization of lipo- and polyplexes has already been successfully achieved by PEGylation. This modification reduces the interaction with serum proteins and thus prevents the lipoplexes from being cleared by the reticuloendothelial system. Problematically, this stabilization of lipoplexes simultaneously leads to reduced transfer efficiencies compared to non-PEGylated complexes. However, this reduction in transfer efficiency can be used to advantage since additional modification of PEGylated lipoplexes with functional groups enables improved selective transfer into target cells. Cancer cells overexpress folate receptors because of a significantly increased need of folate due to high cell proliferation rates. Thus, additional folate functionalization of PEGylated lipoplexes improves uptake into cancer cells. We demonstrate herein that NHS coupling chemistries can be used to modify two commercially available transfection reagents (Fuse-It-DNA and Lipofectamine® 3000) with NHS-PEG-folate for increased uptake of nucleic acids into cancer cells. Lipoplex characterization and functional analysis in cultures of cancer- and healthy cells clearly demonstrate that functionalization of PEGylated lipoplexes offers a promising method to generate efficient, stable and selective nucleic acid transfer systems.
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Microglia-the brain's primary immune cells-exert a tightly regulated cascade of pro- and anti-inflammatory effects upon brain pathology, either promoting regeneration or neurodegeneration. Therefore, harnessing microglia emerges as a potential therapeutic concept in neurological research. Recent studies suggest that-besides being affected by chemokines and cytokines-various cell entities in the brain relevantly respond to the mechanical properties of their microenvironment. For example, we lately reported considerable effects of elasticity on neural stem cells, regarding quiescence and differentiation potential. However, the effects of elasticity on microglia remain to be explored.Under the hypothesis that the elasticity of the microenvironment affects key characteristics and functions of microglia, we established an in vitro model of primary rat microglia grown in a polydimethylsiloxane (PDMS) elastomer-based cell culture system. This way, we simulated the brain's physiological elasticity range and compared it to supraphysiological stiffer PDMS controls. We assessed functional parameters of microglia under "resting" conditions, as well as when polarized towards a pro-inflammatory phenotype (M1) by lipopolysaccharide (LPS), or an anti-inflammatory phenotype (M2) by interleukin-4 (IL-4). Microglia viability was unimpaired on soft substrates, but we found various significant effects with a more than two-fold increase in microglia proliferation on soft substrate elasticities mimicking the brain (relative to PDMS controls). Furthermore, soft substrates promoted the expression of the activation marker vimentin in microglia. Moreover, the M2-marker CD206 was upregulated in parallel to an increase in the secretion of Insulin-Like Growth Factor-1 (IGF-1). The upregulation of CD206 was abolished by blockage of stretch-dependent chloride channels. Our data suggest that the cultivation of microglia on substrates of brain-like elasticity promotes a basic anti-inflammatory activation state via stretch-dependent chloride channels. The results highlight the significance of the omnipresent but mostly overlooked mechanobiological effects exerted on microglia and contribute to a better understanding of the complex spatial and temporal interactions between microglia, neural stem cells, and glia, in health and disease.
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Transferring nucleic acids into mammalian cells heavily influences life science for decades. While first applications mainly dealt with DNA transfer for various purposes as e.g., plasmid encoded protein expression or generation of mutant strains, subsequent applications additionally transferred RNA molecules of mainly small lengths for specific knockdown (RNAi) or site-specific genome modification (gRNA). Significant improvements in full length mRNA generation and extension of mRNA lifetimes additionally allows their use for transient expression in latest times. For all of these types of nucleic acids the most common cell incorporation method is based on complexation and subsequent endosomal uptake. This so-called lipofection can be used theoretically for almost any mammalian cell type and a tremendous number of different product compositions exist in order to deal with drawbacks as transfer efficiency, cell type selectivity, endosomal degradation, slow uptake and cytotoxicity. In contrast, new methods transfer complexed RNA molecules directly into the cytoplasm using liposomal nano-carriers that fuse with cellular plasma membranes immediately upon contact to free functional nucleic acids directly into the cytoplasm. Here, we compare both methods in detail with special focus on robustness, short- and long-term cytotoxicity, efficiency and functionality for various types of transferred RNA. Our data clearly indicate that direct RNA incorporation via fusogenic nano-carriers circumvents most endosomal uptake-based challenges, making it to a most promising alternative for nucleic acid transfer.
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Nanoestructuras , Animales , ADN , Plásmidos , Interferencia de ARN , ARN Mensajero , ARN Interferente PequeñoRESUMEN
In the brain, neural stem cells (NSC) are tightly regulated by external signals and biophysical cues mediated by the local microenvironment or "niche." In particular, the influence of tissue elasticity, known to fundamentally affect the function of various cell types in the body, on NSC remains poorly understood. We, accordingly, aimed to characterize the effects of elastic substrates on critical NSC functions. Primary rat NSC were grown as monolayers on polydimethylsiloxane- (PDMS-) based gels. PDMS-coated cell culture plates, simulating the physiological microenvironment of the living brain, were generated in various degrees of elasticity, ranging from 1 to 50 kPa; additionally, results were compared with regular glass plates as usually used in cell culture work. Survival of NSC on the PDMS-based substrates was unimpaired. The proliferation rate on 1 kPa PDMS decreased by 45% compared with stiffer PMDS substrates of 50 kPa (p < 0.05) whereas expression of cyclin-dependent kinase inhibitor 1B/p27Kip1 increased more than two fold (p < 0.01), suggesting NSC quiescence. NSC differentiation was accelerated on softer substrates and favored the generation of neurons (42% neurons on 1 kPa PDMS vs. 25% on 50 kPa PDMS; p < 0.05). Neurons generated on 1 kPa PDMS showed 29% longer neurites compared with those on stiffer PDMS substrates (p < 0.05), suggesting optimized neuronal maturation and an accelerated generation of neuronal networks. Data show that primary NSC are significantly affected by the mechanical properties of their microenvironment. Culturing NSC on a substrate of brain-like elasticity keeps them in their physiological, quiescent state and increases their neurogenic potential.
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Fenómenos Biofísicos , Encéfalo/fisiología , Elasticidad , Células-Madre Neurales/citología , Neurogénesis , Animales , Bovinos , Diferenciación Celular , Proliferación Celular , Supervivencia Celular , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/metabolismo , Proyección Neuronal , Ratas Wistar , Regulación hacia ArribaRESUMEN
The skin's epidermis is a multilayered epithelial tissue and the first line of defense against mechanical stress. Its barrier function depends on an integrated assembly and reorganization of cell-matrix and cell-cell junctions in the basal layer and on different intercellular junctions in suprabasal layers. However, how mechanical stress is recognized and which adhesive and cytoskeletal components are involved are poorly understood. Here, we subjected keratinocytes to cyclic stress in the presence or absence of intercellular junctions. Both states not only recognized but also responded to strain by reorienting actin filaments perpendicular to the applied force. Using different keratinocyte mutant strains that altered the mechanical link of the actin cytoskeleton to either cell-matrix or cell-cell junctions, we show that not only focal adhesions but also adherens junctions function as mechanosensitive elements in response to cyclic strain. Loss of paxillin or talin impaired focal adhesion formation and only affected mechanosensitivity in the absence but not presence of intercellular junctions. Further analysis revealed the adherens junction protein α-catenin as a main mechanosensor, with greatest sensitivity conferred on binding to vinculin. Our data reveal a mechanosensitive transition from cell-matrix to cell-cell adhesions on formation of keratinocyte monolayers with vinculin and α-catenin as vital players.
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Uniones Adherentes/metabolismo , Diferenciación Celular , Células Epiteliales/citología , Células Epiteliales/metabolismo , Adhesiones Focales/metabolismo , Actinas/metabolismo , Animales , Comunicación Celular , Mecanotransducción Celular , Ratones , Paxillin/metabolismo , Unión Proteica , Fibras de Estrés/metabolismo , Estrés Mecánico , Vinculina/metabolismo , alfa Catenina/metabolismoAsunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias del Colon/tratamiento farmacológico , Queratodermia Palmoplantar/diagnóstico , Sífilis Cutánea/diagnóstico , Biopsia , Diagnóstico Diferencial , Femenino , Humanos , Queratodermia Palmoplantar/patología , Persona de Mediana Edad , Piel/patología , Sífilis Cutánea/patologíaRESUMEN
Intention of the study (EudraCT No 2009-017418-56) is a proof of aesthetic benefit of triterpene treatment in superficial wounds. In an open, prospective, controlled, randomized, blindly evaluated multicentre phase II clinical trial a triterpene ointment (OG-S10) is compared intra individually with a state-of-the-art moist wound healing dressing (Mepilex(®)) in split thickness skin graft donor sites. The graft wound areas at the upper leg were divided into two equal halves, one proximal and one distal site. Decided by randomization the one site was treated with triterpene and the other in comparison with moist dressing. Triterpene treatment went on for 14 days as covering the wound at every change of wound dressing with the ointment (100 mg/cm(2)). The comparative treatment went on as covering the site by this dressing alone. The outcome of these different treatments was evaluated by two blindly observing distant experts on the basis of photographs of the wound healing progress. Photographs were taken day 14, 3 month and 1 year after treatment. The only criterion for evaluation of the two sites was similarity of the wound area to the surrounding skin in terms of colour and texture: which of the two sites, the proximal or the distal, was aesthetically superior in normal skin appearance after 14 days at the end of treatment, after 3 month of follow up and 1 year after treatment? The descriptive comparison is demonstrating quite a remarkable advantage of the ointment versus the moist wound dressing in promoting wound healing: even having in mind the small number of 24 patients within the protocol, the superiority of aesthetic benefit by triterpene treatment after 14 days (22 out of 24 patients), after 3 month (15 out of 19 patients) and after 1 year (8 out of 10 patients) is obvious.
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Estética , Trasplante de Piel/patología , Sitio Donante de Trasplante/patología , Triterpenos/uso terapéutico , Adulto , Anciano , Anciano de 80 o más Años , Vendajes , Femenino , Estudios de Seguimiento , Humanos , Pierna , Masculino , Persona de Mediana Edad , Pomadas , Fotograbar , Estudios Prospectivos , Repitelización/efectos de los fármacos , Método Simple Ciego , Piel/anatomía & histología , Piel/efectos de los fármacos , Neoplasias Cutáneas/cirugía , Resultado del Tratamiento , Cicatrización de Heridas/efectos de los fármacos , Adulto JovenRESUMEN
BACKGROUND: Acute meningoencephalitis (ME) from varicella zoster virus (VZV) reactivation is a rare and serious complication of herpes zoster (HZ). OBJECTIVES AND METHODS: As early diagnostic detection is mandatory to prevent long-term sequelae, any clinical indication is helpful to identify patients that are at higher risk of the development of VZV-ME. In order to find such risk factors, the clinical data of 38 patients consecutively hospitalized for the treatment of HZ over a 1-year period were analyzed. RESULTS: Four of the 38 patients with HZ developed ME. Of these, three had involvement of the trigeminal nerve branch, one including an ophthalmic affection, and one presented with disseminated HZ. All were women with an average age of 83.5 years, in comparison with patients with HZ but without ME who had an average age of 69.3 years and a female preponderance of 60%. The first clinical signs of ME were rapidly progressing somnolence and meningism. Patients with HZ-ME were treated with intravenous acyclovir, oral glucocorticosteroids, and antiseizure therapy, and recovered almost completely without major residual symptoms. CONCLUSION: Progression of HZ to ME seems to occur more often than normally believed. Female patients above 80 years of age with either ophthalmic involvement or disseminated HZ are at a potentially high risk of the development of ME. The general recommendation of starting oral glucocorticosteroids from day 1 of antiviral treatment in older patients must be questioned, as it may stimulate VZV replication and dissemination.
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Encefalitis por Varicela Zóster/complicaciones , Encefalitis por Varicela Zóster/fisiopatología , Herpes Zóster/complicaciones , Herpes Zóster/fisiopatología , Herpesvirus Humano 3 , Enfermedad Aguda , Adulto , Anciano , Anciano de 80 o más Años , Trastornos de la Conciencia/epidemiología , Trastornos de la Conciencia/virología , Progresión de la Enfermedad , Encefalitis por Varicela Zóster/epidemiología , Femenino , Herpes Zóster/epidemiología , Humanos , Masculino , Nervio Maxilar/virología , Persona de Mediana Edad , Nervio Oftálmico/virología , Factores de Riesgo , Nervios Espinales/virología , Enfermedades del Nervio Trigémino/epidemiología , Enfermedades del Nervio Trigémino/fisiopatología , Enfermedades del Nervio Trigémino/virologíaRESUMEN
Toll-like receptors (TLRs) are pathogen recognition molecules activating the innate immune system. Cell surface expressed TLRs, such as TLR2 and TLR4, have been shown to play an important role in human host defenses against viruses through sensing of viral structural proteins. In this study, we aimed to elucidate whether TLR2 and TLR4 participate in inducing antiviral immunity against hepatitis C virus (HCV) by sensing viral structural proteins. We studied TLR2 and TLR4 activation by cell culture-derived infectious virions and serum-derived virions in comparison to purified recombinant HCV structural proteins and enveloped virus-like particles. Incubation of TLR2 or TLR4 transfected cell lines with recombinant core protein resulted in activation of TLR2-dependent signaling. In contrast, neither infectious virions nor enveloped HCV-like particles triggered TLR2 and TLR4 signaling. These findings suggest that monomeric HCV core protein but not intact infectious particles are sensed by TLR2. Impairment of interaction between TLR and the core in infectious viral particles may contribute to escape from innate antiviral immune responses.