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The EphB4-ephrinB2 signaling axis has been heavily implicated in metastasis across numerous cancer types. Our emerging understanding of the dichotomous roles that EphB4 and ephrinB2 play in head and neck squamous cell carcinoma (HNSCC) poses a significant challenge to rational drug design. We find that EphB4 knockdown in cancer cells enhances metastasis in preclinical HNSCC models by augmenting immunosuppressive cells like T regulatory cells (Tregs) within the tumor microenvironment. EphB4 inhibition in cancer cells also amplifies their ability to metastasize through increased expression of genes associated with epithelial mesenchymal transition and hallmark pathways of metastasis. In contrast, vascular ephrinB2 knockout coupled with radiation therapy (RT) enhances anti-tumor immunity, reduces Treg accumulation into the tumor, and decreases metastasis. Notably, targeting the EphB4-ephrinB2 signaling axis with the engineered EphB4 ligands EFNB2-Fc-His and Fc-TNYL-RAW-GS reduces local tumor growth and distant metastasis in a preclinical model of HNSCC. Our data suggest that targeted inhibition of vascular ephrinB2 while avoiding inhibition of EphB4 in cancer cells could be a promising strategy to mitigate HNSCC metastasis.
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PURPOSE: To determine whether dropless, injection-based cataract surgery prophylaxis with intracameral antibiotic and subconjunctival steroid may reduce healthcare system costs and patient out-of-pocket costs compared to topical medication regimens. SETTING: United States national medical expenditures database. DESIGN: Retrospective cost analysis. METHODS: Costs were analyzed for topical ophthalmics from the 2020 Medical Expenditure Panel Survey (MEPS) and for dropless medications from pharmaceutical invoices/catalogs. Main outcomes included system costs, from insurance and patient payments, and out-of-pocket costs for cataract surgery topical and dropless, injection-based prophylactic medication regimens, per eye and nationally. System costs for individual topical medications and same-class dropless, injection-based medications were compared using two-sided, one-sample t-tests. RESULTS: There were 583 prophylactic topical ophthalmic purchases in MEPS. Mean system costs per eye were $76.20 ± SD 39.07 for the lowest cost topical steroid (prednisolone) compared to $4.01 for the lowest cost subconjunctival steroid (triamcinolone acetonide) (p < 0.001). Per eye, the lowest cost dropless, injection-based regimen, at $15.91, results in an $87.99 (84.7%) reduction in overall healthcare costs and a $43.64 (100%) reduction in patient out-of-pocket costs relative to the lowest cost topical regimen ($103.90 ± 43.14 mean system cost and $43.64 ± 37.32 mean out-of-pocket cost per eye). Use of intracameral moxifloxacin and subconjunctival triamcinolone acetonide can reduce annual national healthcare system and out-of-pocket costs up to $450,000,000 and $225,000,000, respectively. CONCLUSIONS: An evidence-based cataract surgery prophylactic medication regimen of intracameral moxifloxacin and subconjunctival triamcinolone acetonide can reduce healthcare system and patient out-of-pocket costs in comparison to various topical regimens.
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The specific nature of CRISPR-Cas12a makes it a desirable RNA-guided endonuclease for biotechnology and therapeutic applications. To understand how R-loop formation within the compact Cas12a enables target recognition and nuclease activation, we used cryo-electron microscopy to capture wild-type Acidaminococcus sp. Cas12a R-loop intermediates and DNA delivery into the RuvC active site. Stages of Cas12a R-loop formation-starting from a 5-bp seed-are marked by distinct REC domain arrangements. Dramatic domain flexibility limits contacts until nearly complete R-loop formation, when the non-target strand is pulled across the RuvC nuclease and coordinated domain docking promotes efficient cleavage. Next, substantial domain movements enable target strand repositioning into the RuvC active site. Between cleavage events, the RuvC lid conformationally resets to occlude the active site, requiring re-activation. These snapshots build a structural model depicting Cas12a DNA targeting that rationalizes observed specificity and highlights mechanistic comparisons to other class 2 effectors.
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Acidaminococcus , Proteínas Bacterianas , Proteínas Asociadas a CRISPR , Sistemas CRISPR-Cas , Dominio Catalítico , Microscopía por Crioelectrón , Proteínas Asociadas a CRISPR/metabolismo , Proteínas Asociadas a CRISPR/química , Proteínas Asociadas a CRISPR/genética , Acidaminococcus/enzimología , Acidaminococcus/genética , Acidaminococcus/metabolismo , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/química , Estructuras R-Loop/genética , Endodesoxirribonucleasas/metabolismo , Endodesoxirribonucleasas/genética , Endodesoxirribonucleasas/química , ARN Guía de Sistemas CRISPR-Cas/metabolismo , ARN Guía de Sistemas CRISPR-Cas/genética , Modelos Moleculares , Dominios Proteicos , Relación Estructura-Actividad , Unión ProteicaRESUMEN
INTRODUCTION: Sarcomas, a group of neoplasms comprising both tissue and bone soft tissue tumors, has an increasing prevalence in recent years. Prognosis significantly hinges on early detection, and if not detected early, may consequently metastasize. This review will be the first systematic review and meta-analysis characterizing the presentation and progression of brain metastases from bone and soft tissue cancers. METHODS: The PubMed, Scopus, and Web of Science databases were queried to identify studies reporting the incidence of intracranial brain metastases from primary sarcoma to the present. Abstract and full-text screening of 1822 initial articles returned by preliminary search yielded 28 studies for inclusion and data extraction. Qualitative assessment of the studies was conducted in accordance with the Newcastle-Ottawa Scale criteria. Meta-analyses were applied to assess risk factors on outcomes. RESULTS: The average age within the cohort was 27.9 years with a male and female prevalence of 59.1% and 40.9%, respectively. The odds ratio for living status (dead/alive) was calculated for several risk factors - male/female [OR 1.14, 95% CI 0.62, 2.07], single/multiple metastases [OR 0.67, 95% CI 0.35, 1.28], lung metastases/not [OR 1.63, 95% CI 0.85, 3.13], surgery/no surgery [OR 0.49, 95% CI 0.20, 1.21]. The standardized mean differences for duration from diagnoses to metastases were likewise analyzed - male/female [SMD 0.13, 95% CI -0.15, 0.42], single/multiple metastases [SMD 0.11, 95% CI -0.20, 0.42], lung metastases/not [SMD -0.03, 95% CI -0.38, 0.32], surgery/no surgery [SMD 0.45, 95% CI -0.18, 1.09]. The standardized mean differences for duration from metastases to death were analyzed - lung metastases/not [SMD 0.43, 95% CI -0.08, 0.95]. CONCLUSIONS: Our study observed no statistically significant differences in mortality rate among several patient risk factors. Consequentially, there lacks a clear answer as to whether or not an association between mortality rates exists with these patient factors. As such, it is important to continue research in brain-metastasizing sarcomas despite their relative rarity.
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Neoplasias Encefálicas , Sarcoma , Femenino , Humanos , Masculino , Neoplasias Óseas/epidemiología , Neoplasias Óseas/patología , Neoplasias Encefálicas/secundario , Neoplasias Encefálicas/epidemiología , Factores de Riesgo , Sarcoma/secundario , Sarcoma/epidemiologíaRESUMEN
The intrinsic pathways that control membrane organization in immune cells and the impact of such pathways on cellular function are not well defined. Here we report that the non-vesicular cholesterol transporter Aster-A links plasma membrane (PM) cholesterol availability in T cells to immune signaling and systemic metabolism. Aster-A is recruited to the PM during T-cell receptor (TCR) activation, where it facilitates the removal of newly generated "accessible" membrane cholesterol. Loss of Aster-A leads to excess PM cholesterol accumulation, resulting in enhanced TCR nano-clustering and signaling, and Th17 cytokine production. Finally, we show that the mucosal Th17 response is restrained by PM cholesterol remodeling. Ablation of Aster-A in T cells leads to enhanced IL-22 production, reduced intestinal fatty acid absorption, and resistance to diet-induced obesity. These findings delineate a multi-tiered regulatory scheme linking immune cell lipid flux to nutrient absorption and systemic physiology.
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Clinically approved head and neck squamous cell carcinoma (HNSCC) immunotherapies manipulate the immune checkpoint blockade (ICB) axis but have had limited success outside of recurrent/metastatic disease. Interleukin-7 (IL7) has been shown to be essential for effector T-cell survival, activation, and proliferation. Here, we show that IL7 in combination with radiotherapy (RT) is effective in activating CD8 + T-cells for reducing tumor growth. Our studies were conducted using both human papillomavirus related and unrelated orthotopic HNSCC murine models. Immune populations from the tumor, draining lymph nodes, and blood were compared between treatment groups and controls using flow cytometry, proteomics, immunofluorescence staining, and RNA sequencing. Treatment with RT and IL7 (RT + IL7) resulted in significant tumor growth reduction, high CD8 T-cell tumor infiltration, and increased proliferation of T-cell progenitors in the bone marrow. IL7 also expanded a memory-like subpopulation of CD8 T-cells. These results indicate that IL7 in combination with RT can serve as an effective immunotherapy strategy outside of the conventional ICB axis to drive the antitumor activity of CD8 T-cells.
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Neoplasias de Cabeza y Cuello , Interleucina-7 , Humanos , Ratones , Animales , Carcinoma de Células Escamosas de Cabeza y Cuello/radioterapia , Células T de Memoria , Linfocitos T CD8-positivos , Neoplasias de Cabeza y Cuello/radioterapia , Microambiente TumoralRESUMEN
PURPOSE: Head and neck cancer (HNC) improvements are stagnant, even with advances in immunotherapy. Our previous clinical trial data show that altered fatty acid (FA) metabolism correlates with outcome. We hypothesized that pharmacologic and dietary modulation of FA catabolism will affect therapeutic efficacy. EXPERIMENTAL DESIGN: We performed in vivo and in vitro experiments using PPARα agonism with fenofibrate (FF) or high oleic acid diets (OAD) with radiotherapy, generating metabolomic, proteomic, stable isotope tracing, extracellular flux analysis, and flow-cytometric data to investigate these alterations. RESULTS: FF improved antitumor efficacy of high dose per fraction radiotherapy in HNC murine models, whereas the OAD reversed this effect. FF-treated mice on the control diet had evidence of increased FA catabolism. Stable isotope tracing showed less glycolytic utilization by ex vivo CD8+ T cells. Improved efficacy correlated with intratumoral alterations in eicosanoid metabolism and downregulated mTOR and CD36. CONCLUSIONS: Metabolic intervention with increased FA catabolism improves the efficacy of HNC therapy and enhances antitumoral immune response.
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Neoplasias de Cabeza y Cuello , Ácido Oléico , PPAR alfa , Animales , PPAR alfa/agonistas , Ratones , Ácido Oléico/farmacología , Humanos , Neoplasias de Cabeza y Cuello/inmunología , Fenofibrato/farmacología , Línea Celular Tumoral , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/efectos de los fármacos , Ácidos Grasos/metabolismo , Modelos Animales de EnfermedadRESUMEN
BACKGROUND: Perineural invasion (PNI) and nerve density within the tumor microenvironment (TME) have long been associated with worse outcomes in head and neck squamous cell carcinoma (HNSCC). This prompted an investigation into how nerves within the tumor microenvironment affect the adaptive immune system and tumor growth. METHODS: We used RNA sequencing analysis of human tumor tissue from a recent HNSCC clinical trial, proteomics of human nerves from HNSCC patients, and syngeneic orthotopic murine models of HPV-unrelated HNSCC to investigate how sensory nerves modulate the adaptive immune system. FINDINGS: Calcitonin gene-related peptide (CGRP) directly inhibited CD8 T cell activity in vitro, and blocking sensory nerve function surgically, pharmacologically, or genetically increased CD8 and CD4 T cell activity in vivo. CONCLUSIONS: Our data support sensory nerves playing a role in accelerating tumor growth by directly acting on the adaptive immune system to decrease Th1 CD4 T cells and activated CD8 T cells in the TME. These data support further investigation into the role of sensory nerves in the TME of HNSCC and points toward the possible treatment efficacy of blocking sensory nerve function or specifically inhibiting CGRP release or activity within the TME to improve outcomes. FUNDING: 1R01DE028282-01, 1R01DE028529-01, 1P50CA261605-01 (to S.D.K.), 1R01CA284651-01 (to S.D.K.), and F31 DE029997 (to L.B.D.).
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Péptido Relacionado con Gen de Calcitonina , Neoplasias de Cabeza y Cuello , Animales , Humanos , Ratones , Péptido Relacionado con Gen de Calcitonina/metabolismo , Linfocitos T CD4-Positivos , Linfocitos T CD8-positivos , Neoplasias de Cabeza y Cuello/metabolismo , Neoplasias de Cabeza y Cuello/patología , Carcinoma de Células Escamosas de Cabeza y Cuello , Microambiente TumoralRESUMEN
Objective: To survey the social media outlets Twitter and Instagram for public posts related to adenoidectomy surgery. This study aims to investigate the attitudes and perceptions of patients and caregivers on social media, through thematic content-analysis of social media posts regarding adenoidectomy. Study Design: Non-real world qualitative study. Setting: Twitter and Instagram social media platforms. Methods: Public posts uploaded between February, 2021 and February, 2023 using the hashtags "#adenoidectomy," and "#adenoidectomyrecovery" were searched. Posts were excluded if they were unrelated to adenoidectomy or were in a non-English language. Relevant posts were stratified demographically as patient or caregiver and pre- or postoperative, and categorized into relevant themes for analysis. Outcomes were measured as the total number of posts. Results: A total of 394 relevant posts were analyzed. A significance threshold of P < 0.05 was used. Patients posted significantly more posts regarding procedure pain (P = 0.002) and concern for appearance (P = 0.048) compared to caregivers. Caregivers posted significantly (P < 0.001) more posts regarding condition awareness and were significantly (P < 0.001) more likely to spread positivity in their posts compared to patients themselves. Posts made by female caregivers were more likely to reference fear, while those made by male caregivers were more likely to provide education (P = 0.002). Conclusion: Patients may worry about appearance and mental health while caregivers are more likely to spread information and positivity. Male and female caregivers may also use social media differently. A better understanding of patient and caregiver concerns may optimize physician interaction and involvement.
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OBJECTIVES: Compared with younger and middle-aged adults, older adults are less likely to adopt new computer technology, potentially limiting access to healthcare and many other important resources available online. This limitation could impact cognitive abilities, well-being, and mental health outcomes of older adults. The aims of the present study were to increase access to online county and healthcare resources, while also assessing the impact of technology access on cognitive functioning and multiple well-being domains. METHODS: A pilot community collaboration provided a two-month tablet training intervention, focused on increasing digital independence via tablet navigation, resources access, and fraud and scam prevention, to 20 low-income older adult participants (75% female, Mage = 70.85). Pre- and post-test phone interviews were conducted to measure any changes in digital independence, cognitive abilities, well-being, mental health, and mindset. RESULTS: Linear mixed effects models revealed no significant changes in outcome measures from pre- to post-test. However, we found effects of digital independence on several well-being measures, providing important information for the impact of technology access and training for low-income older adults. CONCLUSION: This pilot intervention offers limited but promising results, inspiring further investigations that may inform public health and policy services to address barriers to access and potentially improve psychological health.
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Cognición , Evaluación de Resultado en la Atención de Salud , Humanos , Femenino , Anciano , Persona de Mediana Edad , Masculino , ComprimidosRESUMEN
Intestinal absorption is an important contributor to systemic cholesterol homeostasis. Niemann-Pick C1 Like 1 (NPC1L1) assists in the initial step of dietary cholesterol uptake, but how cholesterol moves downstream of NPC1L1 is unknown. We show that Aster-B and Aster-C are critical for nonvesicular cholesterol movement in enterocytes. Loss of NPC1L1 diminishes accessible plasma membrane (PM) cholesterol and abolishes Aster recruitment to the intestinal brush border. Enterocytes lacking Asters accumulate PM cholesterol and show endoplasmic reticulum cholesterol depletion. Aster-deficient mice have impaired cholesterol absorption and are protected against diet-induced hypercholesterolemia. Finally, the Aster pathway can be targeted with a small-molecule inhibitor to manipulate cholesterol uptake. These findings identify the Aster pathway as a physiologically important and pharmacologically tractable node in dietary lipid absorption.
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Colesterol en la Dieta , Enterocitos , Absorción Intestinal , Proteínas de Transporte de Membrana , Animales , Ratones , Transporte Biológico , Colesterol en la Dieta/metabolismo , Absorción Intestinal/efectos de los fármacos , Absorción Intestinal/fisiología , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Membrana/metabolismo , Ratones Endogámicos C57BL , Enterocitos/metabolismo , Receptores X del Hígado/metabolismo , Humanos , Yeyuno/metabolismo , Ratones NoqueadosRESUMEN
Headguard use is appropriate during some combat sports activities where the risks of injury to the face and ears are elevated. Headguards are highly effective in reducing the incidence of facial lacerations in studies of amateur boxers and are just as effective in other striking sports. They should be used in scenarios - especially sparring prior to competitions - where avoidance of laceration and subsequent exposure to potential blood-borne pathogens is important. Headguards are appropriate where avoidance of auricular injury is deemed important; limited data show a marked reduction in incidence of auricular injury in wrestlers wearing headguards.Headguards should not be relied upon to reduce the risk of concussion or other traumatic brain injury. They have not been shown to prevent these types of injuries in combat sports or other sports, and human studies on the effect of headguards on concussive injury are lacking. While biomechanical studies suggest they reduce linear and rotational acceleration of the cranium, changes in athlete behavior to more risk-taking when wearing headguards may offset any risk reduction. In the absence of high-quality studies on headguard use, the Association of Ringside Physicians recommends that further research be conducted to clarify the role of headguards in all combat sports, at all ages of participation. Furthermore, in the absence of data on gender differences, policies should be standardized for men and women.
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Intestinal cholesterol absorption is an important contributor to systemic cholesterol homeostasis. Niemann-Pick C1 Like 1 (NPC1L1), the target of the drug ezetimibe (EZ), assists in the initial step of dietary cholesterol uptake. However, how cholesterol moves downstream of NPC1L1 is unknown. Here we show that Aster-B and Aster-C are critical for non-vesicular cholesterol movement in enterocytes, bridging NPC1L1 at the plasma membrane (PM) and ACAT2 in the endoplasmic reticulum (ER). Loss of NPC1L1 diminishes accessible PM cholesterol in enterocytes and abolishes Aster recruitment to the intestinal brush border. Enterocytes lacking Asters accumulate cholesterol at the PM and display evidence of ER cholesterol depletion, including decreased cholesterol ester stores and activation of the SREBP-2 transcriptional pathway. Aster-deficient mice have impaired cholesterol absorption and are protected against diet-induced hypercholesterolemia. Finally, we show that the Aster pathway can be targeted with a small molecule inhibitor to manipulate dietary cholesterol uptake. These findings identify the Aster pathway as a physiologically important and pharmacologically tractable node in dietary lipid absorption. One-Sentence Summary: Identification of a targetable pathway for regulation of dietary cholesterol absorption.
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The present review aimed to establish an understanding of the pathophysiology of leptomeningeal disease as it relates to late-stage development among different cancer types. For our purposes, the focused metastatic malignancies include breast cancer, lung cancer, melanoma, primary central nervous system tumors, and hematologic cancers (lymphoma, leukemia, and multiple myeloma). Of note, our discussion was limited to cancer-specific leptomeningeal metastases secondary to the aforementioned primary cancers. LMD mechanisms secondary to non-cancerous pathologies, such as infection or inflammation of the leptomeningeal layer, were excluded from our scope of review. Furthermore, we intended to characterize general leptomeningeal disease, including the specific anatomical infiltration process/area, CSF dissemination, manifesting clinical symptoms in patients afflicted with the disease, detection mechanisms, imaging modalities, and treatment therapies (both preclinical and clinical). Of these parameters, leptomeningeal disease across different primary cancers shares several features. Pathophysiology regarding the development of CNS involvement within the mentioned cancer subtypes is similar in nature and progression of disease. Consequently, detection of leptomeningeal disease, regardless of cancer type, employs several of the same techniques. Cerebrospinal fluid analysis in combination with varied imaging (CT, MRI, and PET-CT) has been noted in the current literature as the gold standard in the diagnosis of leptomeningeal metastasis. Treatment options for the disease are both varied and currently in development, given the rarity of these cases. Our review details the differences in leptomeningeal disease as they pertain through the lens of several different cancer subtypes in an effort to highlight the current state of targeted therapy, the potential shortcomings in treatment, and the direction of preclinical and clinical treatments in the future. As there is a lack of comprehensive reviews that seek to characterize leptomeningeal metastasis from various solid and hematologic cancers altogether, the authors intended to highlight not only the overlapping mechanisms but also the distinct patterning of disease detection and progression as a means to uniquely treat each metastasis type. The scarcity of LMD cases poses a barrier to more robust evaluations of this pathology. However, as treatments for primary cancers have improved over time, so has the incidence of LMD. The increase in diagnosed cases only represents a small fraction of LMD-afflicted patients. More often than not, LMD is determined upon autopsy. The motivation behind this review stems from the increased capacity to study LMD in spite of scarcity or poor patient prognosis. In vitro analysis of leptomeningeal cancer cells has allowed researchers to approach this disease at the level of cancer subtypes and markers. We ultimately hope to facilitate the clinical translation of LMD research through our discourse.
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Neoplasias de la Mama , Neoplasias Hematológicas , Carcinomatosis Meníngea , Humanos , Femenino , Tomografía Computarizada por Tomografía de Emisión de Positrones , Carcinomatosis Meníngea/terapia , Carcinomatosis Meníngea/epidemiología , Carcinomatosis Meníngea/secundario , Neoplasias de la Mama/patología , Imagen por Resonancia MagnéticaRESUMEN
In the title compound, C11H10F4N2O2, the conformation about the N-C-C-O bond is gauche [torsion angle = 61.84â (13)°]. In the crystal, N-Hâ¯O hydrogen bonds link the mol-ecules into [010] chains, which are cross-linked by C-Hâ¯F and C-Hâ¯π contacts. Hirshfeld surface analysis was conducted to aid in the visualization of these various influences on the packing. This analysis showed that the largest contribution to the surface contacts arises from Fâ¯H/Hâ¯F inter-actions (35.6%), followed by Oâ¯H/Hâ¯O (17.8%) and Hâ¯H (12.7%).
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Cells release extracellular vesicles (EVs) from their surface, but the mechanisms that govern EV release by plasma membrane budding are poorly understood. The lipid flippase TAT-5 inhibits EV release from the plasma membrane in C. elegans , but how the level of flippase activity regulates EV release was unknown. We generated point mutations in the DGET motif of TAT-5 predicted to lead to a partial or complete loss of ATPase activity. We discovered that tat-5(E246Q) mutants were sterile, while tat-5(D244T) mutants produced embryos that arrested during development. Using degron-based reporters, we found that EV release was increased in tat-5(D244T) mutant embryos and that phagocytosis was also disrupted. These data suggest that a low level of flippase activity can promote fertility, while a higher level of flippase activity is required to inhibit EV release, allow phagocytosis, and carry out embryonic development.
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(1) Introduction: Traumatic brain injury (TBI) is a leading cause of injury and mortality worldwide, carrying an estimated cost of $38 billion in the United States alone. Neutrophil to lymphocyte ratio (NLR) has been investigated as a standardized biomarker that can be used to predict outcomes of TBI. The aim of this review was to determine the prognostic utility of NLR among patients admitted for TBI. (2) Methods: A literature search was conducted in PubMed, Scopus, and Web of Science in November 2022 to retrieve articles regarding the use of neutrophil to lymphocyte ratio (NLR) as a prognostic measure in traumatic brain injury (TBI) patients. Inclusion criteria included studies reporting outcomes of TBI patients with associated NLR values. Exclusion criteria were studies reporting only non-primary data, those insufficiently disaggregated to extract NLR data, and non-English or cadaveric studies. The Newcastle-Ottawa Scale was utilized to assess for the presence of bias in included studies. (3) Results: Following the final study selection 19 articles were included for quantitative and qualitative analysis. The average age was 46.25 years. Of the 7750 patients, 73% were male. Average GCS at presentation was 10.51. There was no significant difference in the NLR between surgical vs. non-surgical cohorts (SMD 2.41 95% CI -1.82 to 6.63, p = 0.264). There was no significant difference in the NLR between bleeding vs. non-bleeding cohorts (SMD 4.84 95% CI -0.26 to 9.93, p = 0.0627). There was a significant increase in the NLR between favorable vs. non-favorable cohorts (SMD 1.31 95% CI 0.33 to 2.29, p = 0.0090). (4) Conclusions: Our study found that NLR was only significantly predictive for adverse outcomes in TBI patients and not surgical treatment or intracranial hemorrhage, making it nonetheless an affordable alternative for physicians to assess patient prognosis.
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The conducting boundary states of topological insulators appear at an interface where the characteristic invariant â¤2 switches from 1 to 0. These states offer prospects for quantum electronics; however, a method is needed to spatially-control â¤2 to pattern conducting channels. It is shown that modifying Sb2Te3 single-crystal surfaces with an ion beam switches the topological insulator into an amorphous state exhibiting negligible bulk and surface conductivity. This is attributed to a transition from â¤2 = 1 â â¤2 = 0 at a threshold disorder strength. This observation is supported by density functional theory and model Hamiltonian calculations. Here we show that this ion-beam treatment allows for inverse lithography to pattern arrays of topological surfaces, edges and corners which are the building blocks of topological electronics.
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In cell models, changes in the 'accessible' pool of plasma membrane (PM) cholesterol are linked with the regulation of endoplasmic reticulum sterol synthesis and metabolism by the Aster family of nonvesicular transporters; however, the relevance of such nonvesicular transport mechanisms for lipid homeostasis in vivo has not been defined. Here we reveal two physiological contexts that generate accessible PM cholesterol and engage the Aster pathway in the liver: fasting and reverse cholesterol transport. During fasting, adipose-tissue-derived fatty acids activate hepatocyte sphingomyelinase to liberate sequestered PM cholesterol. Aster-dependent cholesterol transport during fasting facilitates cholesteryl ester formation, cholesterol movement into bile and very low-density lipoprotein production. During reverse cholesterol transport, high-density lipoprotein delivers excess cholesterol to the hepatocyte PM through scavenger receptor class B member 1. Loss of hepatic Asters impairs cholesterol movement into feces, raises plasma cholesterol levels and causes cholesterol accumulation in peripheral tissues. These results reveal fundamental mechanisms by which Aster cholesterol flux contributes to hepatic and systemic lipid homeostasis.
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Colesterol , Hígado , Colesterol/metabolismo , Transporte Biológico/fisiología , Hígado/metabolismo , Homeostasis , Ácidos Grasos/metabolismoRESUMEN
Integration of native bone into orthopedic devices is a key factor in long-term implant success. The material-tissue interface is generally accepted to consist of a hydroxyapatite layer so bioactive materials that can spontaneously generate this hydroxyapatite layer after implantation may improve patient outcomes. Per the ISO 22317:2014 standard, "Implants for surgery - In vitro evaluation for apatite-forming ability of implant materials," bioactivity performance statements can be assessed by soaking the material in simulated body fluid (SBF) and evaluating the surface for the formation of a hydroxyapatite layer; however, variations in test methods may alter hydroxyapatite formation and result in false-positive assessments. The goal of this study was to identify the effect of SBF formulation on bioactivity assessment. Bioglass® (45S5 and S53P4) and non-bioactive Ti-6Al-4V were exposed to SBF formulations varying in calcium ion and phosphate concentrations as well as supporting ion concentrations. Scanning electron microscopy and X-ray powder diffraction evaluation of the resulting hydroxyapatite layers revealed that SBF enriched with double or quadruple the calcium and phosphate ion concentrations increased hydroxyapatite crystal size and quantity compared to the standard formulation and can induce hydroxyapatite crystallization on surfaces traditionally considered non-bioactive. Altering concentrations of other ions, for example, bicarbonate, changed hydroxyapatite induction time, quantity, and morphology. For studies evaluating the apatite-forming ability of a material to support bioactivity performance statements, test method parameters must be adequately described and controlled. It is unclear if apatite formation after exposure to any of the SBF formulations is representative of an in vivo biological response. The ISO 23317 standard test method should be further developed to provide additional guidance on apatite characterization and interpretation of the results.