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Gene duplication events can drive evolution by providing genetic material for new gene functions, and they create opportunities for diverse developmental strategies to emerge between species. To study the contribution of duplicated genes to human early development, we examined the evolution and function of NANOGP1, a tandem duplicate of the transcription factor NANOG. We found that NANOGP1 and NANOG have overlapping but distinct expression profiles, with high NANOGP1 expression restricted to early epiblast cells and naïve-state pluripotent stem cells. Sequence analysis and epitope-tagging revealed that NANOGP1 is protein coding with an intact homeobox domain. The duplication that created NANOGP1 occurred earlier in primate evolution than previously thought and has been retained only in great apes, whereas Old World monkeys have disabled the gene in different ways, including homeodomain point mutations. NANOGP1 is a strong inducer of naïve pluripotency; however, unlike NANOG, it is not required to maintain the undifferentiated status of human naïve pluripotent cells. By retaining expression, sequence and partial functional conservation with its ancestral copy, NANOGP1 exemplifies how gene duplication and subfunctionalisation can contribute to transcription factor activity in human pluripotency and development.
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Genes Homeobox , Células Madre Pluripotentes , Animales , Humanos , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Proteína Homeótica Nanog/genética , Proteína Homeótica Nanog/metabolismo , Células Madre Pluripotentes/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
BACKGROUND: Human tear protein biomarkers are useful for detecting ocular and systemic diseases. Unfortunately, existing tear film sampling methods (Schirmer strip; SS and microcapillary tube; MCT) have significant drawbacks, such as pain, risk of injury, sampling difficulty, and proteomic disparities between methods. Here, we present an alternative tear protein sampling method using soft contact lenses (SCLs). RESULTS: We optimized the SCL protein sampling in vitro and performed in vivo studies in 6 subjects. Using Etafilcon A SCLs and 4M guanidine-HCl for protein removal, we sampled an average of 60 ± 31 µg of protein per eye. We also performed objective and subjective assessments of all sampling methods. Signs of irritation post-sampling were observed with SS but not with MCT and SCLs. Proteomic analysis by mass spectrometry (MS) revealed that all sampling methods resulted in the detection of abundant tear proteins. However, smaller subsets of unique and shared proteins were identified, particularly for SS and MCT. Additionally, there was no significant intrasubject variation between MCT and SCL sampling. CONCLUSIONS: These experiments demonstrate that SCLs are an accessible tear-sampling method with the potential to surpass current methods in sampling basal tears.
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BACKGROUND: Venous thromboembolism (VTE) is a frequent occurrence during treatment for adults with sarcoma. The incidence and underlying risk factors of postsurgical VTE in children and adolescents undergoing resection of sarcoma are unknown. METHODS: Using International Classification of Disease revision-9 diagnostic and procedure codes, the Pediatric Health Information System database was queried for patients aged 18 years and younger, discharged from 2004 to 2015 with a diagnosis of lower extremity malignant neoplasm who had a tumor resection or amputation performed during the encounter. Malignant neoplasms of the pelvic bones and soft tissues were categorized as "pelvis tumors", whereas malignant neoplasms of bone and soft tissues of the lower limbs were categorized as "lower limb tumors". Hospitalizations were evaluated for the occurrence of VTE. Demographic characteristics (age at admission, sex, race, and race/ethnicity) and incidence of VTE were reported. RESULTS: There were 2400 patients identified. Of these, 19 experienced VTE (0.79%) during their surgical hospitalization encounter. By anatomic group, the rate of VTE was 1.4% (CI: 0.5%-3.2%) for tumors in the pelvis and 0.6% (CI: 0.3%-1.0%) in lower limb tumors. Categorizing by age, the incidence of VTE was 1.2% in patients aged zero to 5, 0.3% in patients 6 to 13, and 1.2% in patients 14 to 18 years old. (Table 1). The extremely low rate of VTE occurrence precluded further analysis of risk factors. CONCLUSIONS: In this analysis, postsurgical VTE during hospitalization after pelvic and lower extremity sarcoma resection was an uncommon event in children and adolescents. There seemed to be an increased incidence of postsurgical VTE in pelvic tumors when compared with lower limb tumors, however, the rarity of all events precluded formal statistical analysis. A more robust data set would be required to determine if there are subsets of children and adolescents with sarcoma at higher risk of VTE that could benefit from thromboprophylaxis in the postoperative setting. LEVEL OF EVIDENCE: Level II.
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Sistemas de Información en Salud , Sarcoma , Tromboembolia Venosa , Adulto , Adolescente , Humanos , Niño , Tromboembolia Venosa/epidemiología , Tromboembolia Venosa/etiología , Tromboembolia Venosa/prevención & control , Anticoagulantes/uso terapéutico , Incidencia , Complicaciones Posoperatorias/epidemiología , Complicaciones Posoperatorias/etiología , Hospitalización , Sarcoma/epidemiología , Sarcoma/cirugía , Sarcoma/complicaciones , Factores de Riesgo , Extremidad Inferior/cirugíaRESUMEN
OBJECTIVE: To assess the ability of current 3D printing technology to generate a craniofacial bony and soft tissue anatomical model for use in simulating the performance of a fronto-orbital advancement (FOA) osteotomy and then to further assess the value of the model as an educational tool. DESIGN: Anatomic models were designed with a process of serial anatomic segmentation/design, 3D printing, dissection, and device refinement. A validation study was conducted with 5 junior and 5 senior plastic surgery residents. The validation study incorporated a multiple-choice Knowledge Assessment test (KA), an Objective Structured Assessment of Technical skills (OSATs), a Global Rating Scale (GRS) and a Michigan Standard Simulation Experience Scale (MiSSES). We compared the scores of both the junior and senior residents and compared junior resident scores, before and after viewing a lecture/demonstration. RESULTS: MiSSES showed high face validity with a score of 85.1/90, signifying high satisfaction with the simulator learning experience. Simulation and the lecture/demonstration improved the junior resident average KA score from 5.6/10 to 9.6/10 (Pâ =â .02), OSATs score from 32.4/66 to 64.4/66 (Pâ <â .001) and GRS score from 13.9/35 to 27.5/35 (Pâ <â .001). The senior residents OSATs score of 56.3/66 was higher than the pre-lecture juniors (32.4/66) (Pâ <â .001), but lower than the post-lecture juniors (64.4/66) (Pâ <â .001). CONCLUSION: We have successfully fabricated a 3D printed craniofacial simulator capable of being used as an educational tool alongside traditional surgical training. Next steps would be improving soft tissue realism, inclusion of patient and disease specific anatomy and creation of models for other surgical specialties.
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The behavior of 5f electrons in soft ligand environments makes actinides, and especially transuranium chalcogenides, an intriguing class of materials for fundamental studies. Due to the affinity of actinides for oxygen, however, it is a challenge to synthesize actinide chalcogenides using non-metallic reagents. Using the boron chalcogen mixture method, we achieved the synthesis of the transuranium sulfide NaCuNpS3 starting from the oxide reagent, NpO2. Via the same synthetic route, the isostructural composition of NaCuUS3 was synthesized and the material contrasted with NaCuNpS3. Single crystals of the U-analogue, NaCuUS3, were found to undergo an unexpected reversible hydration process to form NaCuUS3·xH2O (x ≈ 1.5). A large combination of techniques was used to fully characterize the structure, hydration process, and electronic structures, specifically a combination of single crystal, powder, high temperature powder X-ray diffraction, extended X-ray absorption fine structure, infrared, and inductively coupled plasma spectroscopies, thermogravimetric analysis, and density functional theory calculations. The outcome of these analyses enabled us to determine the composition of NaCuUS3·xH2O and obtain a structural model that demonstrated the retention of the local structure within the [CuUS3]- layers throughout the hydration-dehydration process. Band structure, density of states, and Bader charge calculations for NaCuUS3, NaCuUS3·xH2O, and NaCuNpS3 along with X-ray absorption near edge structure, UV-vis-NIR, and work function measurements on ACuUS3 (A = Na, K, and Rb) and NaCuUS3·xH2O samples were carried out to demonstrate that electronic properties arise from the [CuTS3]- layers and show surprisingly little dependence on the interlayer distance.
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Mechanochemical synthesis is emerging as an environmentally friendly yet efficient approach to preparing metal-organic frameworks (MOFs). Herein, we report our systematic investigation on the mechanochemical syntheses of Group 4 element-based MOFs. The developed mechanochemistry allows us to synthesize a family of Hf4O4(OH)4(OOC)12-based MOFs. Integrating [Zr6O4(OH)4(OAc)12]2 and [Hf6O4(OH)4(OAc)12]2 under the mechanochemical conditions leads to a unique family of cluster-precise multimetallic MOFs that cannot be accessed by the conventional solvothermal synthesis. Extensive efforts have not yielded an effective pathway for preparing TiIV-derived MOFs, tentatively because of the relatively low Ti-O bond dissociation energy.
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Recent paleogenomic studies have shown that migrations of Western steppe herders (WSH) beginning in the Eneolithic (ca. 3300-2700 BCE) profoundly transformed the genes and cultures of Europe and central Asia. Compared with Europe, however, the eastern extent of this WSH expansion is not well defined. Here we present genomic and proteomic data from 22 directly dated Late Bronze Age burials putatively associated with early pastoralism in northern Mongolia (ca. 1380-975 BCE). Genome-wide analysis reveals that they are largely descended from a population represented by Early Bronze Age hunter-gatherers in the Baikal region, with only a limited contribution (â¼7%) of WSH ancestry. At the same time, however, mass spectrometry analysis of dental calculus provides direct protein evidence of bovine, sheep, and goat milk consumption in seven of nine individuals. No individuals showed molecular evidence of lactase persistence, and only one individual exhibited evidence of >10% WSH ancestry, despite the presence of WSH populations in the nearby Altai-Sayan region for more than a millennium. Unlike the spread of Neolithic farming in Europe and the expansion of Bronze Age pastoralism on the Western steppe, our results indicate that ruminant dairy pastoralism was adopted on the Eastern steppe by local hunter-gatherers through a process of cultural transmission and minimal genetic exchange with outside groups.
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Crianza de Animales Domésticos/historia , Genoma Humano , Dinámica Poblacional/historia , Animales , Arqueología , ADN Mitocondrial/genética , Europa (Continente) , Femenino , Historia Antigua , Migración Humana/historia , Humanos , Masculino , MongoliaRESUMEN
We elucidate the structural evolution of CoN4 sites during thermal activation by developing a zeolitic imidazolate framework (ZIF)-8-derived carbon host as an ideal model for Co2+ ion adsorption. Subsequent in situ X-ray absorption spectroscopy analysis can dynamically track the conversion from inactive Co-OH and Co-O species into active CoN4 sites. The critical transition occurs at 700 °C and becomes optimal at 900 °C, generating the highest intrinsic activity and four-electron selectivity for the oxygen reduction reaction (ORR). DFT calculations elucidate that the ORR is kinetically favored by the thermal-induced compressive strain of Co-N bonds in CoN4 active sites formed at 900 °C. Further, we developed a two-step (i.e., Co ion doping and adsorption) Co-N-C catalyst with increased CoN4 site density and optimized porosity for mass transport, and demonstrated its outstanding fuel cell performance and durability.
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Covalent modification of substrate proteins with ubiquitin is the end result of an intricate network of protein-protein interactions. The inherent ability of the E1, E2, and E3 proteins of the ubiquitylation cascade (the ubiquitin writers) to interact with ubiquitin facilitates this process. Importantly, contact between ubiquitin and the E2/E3 writers is required for catalysis and the assembly of chains of a given linkage. However, ubiquitin is also an activator of ubiquitin-writing enzymes, with many recent studies highlighting the ability of ubiquitin to regulate activity and substrate modification. Here, we review the interactions between ubiquitin-writing enzymes and regulatory ubiquitin molecules that promote activity, and highlight the potential of these interactions to promote processive ubiquitin transfer.
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Células Eucariotas/metabolismo , Ubiquitina-Proteína Ligasas/química , Ubiquitina/química , Sitios de Unión , Biocatálisis , Células Eucariotas/citología , Expresión Génica , Humanos , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Simulación del Acoplamiento Molecular , Unión Proteica , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Dominios y Motivos de Interacción de Proteínas , Mapeo de Interacción de Proteínas , Especificidad por Sustrato , Ubiquitina/genética , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Transition metal carbides (TMCs) have demonstrated outstanding potential for utilization in a wide range of catalytic applications because of their inherent multifunctionality and tunable composition. However, the harsh conditions required to prepare these materials have limited the scope of synthetic control over their physical properties. The development of low-temperature, carburization-free routes to prepare TMCs would unlock the versatility of this class of materials, enhance our understanding of their physical properties, and enable their cost-effective production at industrial scales. Here, we report an exceptionally mild and scalable solution-phase synthesis route to phase-pure molybdenum carbide (α-MoC1-x) nanoparticles (NPs) in a continuous flow millifluidic reactor. We exploit the thermolytic decomposition of Mo(CO)6 in the presence of a surface-stabilizing ligand and a high boiling point solvent to yield MoC1-x NPs that are colloidally stable and resistant to bulk oxidation in air. To demonstrate the utility of this synthetic route to prepare catalytically active TMC NPs, we evaluated the thermochemical CO2 hydrogenation performance of α-MoC1-x NPs dispersed on an inert carbon support. The α-MoC1-x/C catalyst exhibited a 2-fold increase in both activity on a per-site basis and selectivity to C2+ products as compared to the bulk α-MoC1-x analogue.
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Disparities in cancer incidence and mortality rates among racial and ethnic minorities (African Americans, Asian Americans, Pacific Islanders, American Indians, and Latinos/Hispanic Americans) in the USA are well documented. Enrollment of underrepresented populations in cancer therapeutic clinical trials, however, is very low. This is true despite federal mandates to ensure accrual rates adequate for analyses and the evidence that the effectiveness of specific therapies and medications varies across ethnic and racial groups. Consequently, cancer clinical decision-making is based on research studies where the majority of research participants are white males, despite the disproportionate cancer burden in racial and ethnic minority groups. To date, there have been multiple reviews detailing the barriers to enrollment for these populations in cancer clinical trials, but a notable lack of research on possible strategies to overcome them. The aim of this narrative review is to summarize the current evidence for effective approaches to increase enrollment of underrepresented minorities in cancer therapeutic clinical trials. These approaches include (1) cultural and linguistic adaptations of marketing materials, (2) the use of patient navigators, and (3) building ongoing community partnerships. The majority of studies reviewed employ multiple improvement strategies simultaneously. Identifying effective approaches to increase enrollment of underrepresented populations in cancer clinical trials is a critical step in reducing persistent disparities in cancer incidence and mortality among racial and ethnic populations.
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Ensayos Clínicos como Asunto/métodos , Etnicidad/estadística & datos numéricos , Grupos Minoritarios/estadística & datos numéricos , Neoplasias/terapia , Selección de Paciente , HumanosRESUMEN
To offset the environmental impact of platinum-group element (PGE) mining, recycling techniques are being explored. Porous organic polymers (POPs) have shown significant promise owing to their selectivity and ability to withstand harsh conditions. A series of pyridine-based POP nanotraps, POP-Py, POP-pNH2 -Py, and POP-oNH2 -Py, have been designed and systematically explored for the capture of palladium, one of the most utilized PGEs. All of the POP nanotraps demonstrated record uptakes and rapid capture, with the amino group shown to be vital in improving performance. Further testing on the POP nanotrap regeneration and selectivity found that POP-oNH2 -Py outperformed POP-pNH2 -Py. Single-crystal X-ray analysis indicated that POP-oNH2 -Py provided a stronger complex compared to POP-pNH2 -Py owing to the intramolecular hydrogen bonding between the amino group and coordinated chlorine molecules. These results demonstrate how slight modifications to adsorbents can maximize their performance.
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Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common monogenic hereditary disorders in humans characterized by fluid-filled cysts, primarily in the kidneys. Cux1, a cell cycle regulatory gene highly expressed during kidney development, is elevated in the cyst-lining cells of Pkd1 mutant mice, and in human ADPKD cells. However, forced expression of Cux1 is insufficient to induce cystic disease in transgenic mice or to induce rapid cyst formation after cilia disruption in the kidneys of adult mice. Here we report a double mutant mouse model that has a conditional deletion of the Pkd1 gene in the renal collecting ducts together with a targeted mutation in the Cux1 gene (Pkd1CD;Cux1tm2Ejn). While kidneys isolated from newborn Pkd1CD mice exhibit cortical and medullary cysts, kidneys isolated from newborn Pkd1CD;Cux1tm2Ejn-/- mice did not show any cysts. Because Cux1tm2Ejn-/- are perinatal lethal, we evaluated Pkd1CD mice that were heterozygote for the Cux1 mutation. Similar to the newborn Pkd1CD;Cux1tm2Ejn-/- mice, newborn Pkd1CD;Cux1tm2Ejn+/- mice did not show any cysts. Comparison of Pkd1CD and Pkd1CD;Cux1tm2Ejn+/- mice at later stages of development showed a reduction in the severity of PKD in the Pkd1CD;Cux1tm2Ejn+/- mice. Moreover, we observed an increase in expression of the cyclin kinase inhibitor p27, a target of Cux1 repression, in the rescued collecting ducts. Taken together, our results suggest that Cux1 expression in PKD is not directly involved in cystogenesis but promotes cell proliferation required for expansion of existing cysts, primarily by repression of p27.
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Proliferación Celular , Proteínas de Homeodominio/metabolismo , Túbulos Renales Colectores/metabolismo , Proteínas Nucleares/metabolismo , Riñón Poliquístico Autosómico Dominante/metabolismo , Proteínas Represoras/metabolismo , Factores de Edad , Animales , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/metabolismo , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Predisposición Genética a la Enfermedad , Proteínas de Homeodominio/genética , Túbulos Renales Colectores/patología , Ratones Noqueados , Mutación , Proteínas Nucleares/deficiencia , Proteínas Nucleares/genética , Fenotipo , Riñón Poliquístico Autosómico Dominante/genética , Riñón Poliquístico Autosómico Dominante/patología , Riñón Poliquístico Autosómico Dominante/prevención & control , Proteínas Represoras/deficiencia , Proteínas Represoras/genética , Índice de Severidad de la Enfermedad , Transducción de Señal , Canales Catiónicos TRPP/genética , Canales Catiónicos TRPP/metabolismoRESUMEN
Inspired by the multielectron redox chemistry achieved using conventional organic-based redox-active ligands, we have characterized a series of iron-functionalized polyoxovanadate-alkoxide clusters in which the metal oxide scaffold functions as a three-dimensional, electron-deficient metalloligand. Four heterometallic clusters were prepared through sequential reduction, demonstrating that the metal oxide scaffold is capable of storing up to four electrons. These reduced products were characterized by cyclic voltammetry, IR, electronic absorption, and 1H NMR spectroscopies. Moreover, Mössbauer and X-ray absorption spectroscopies suggest that the redox events involve primarily the vanadium ions, while the iron atoms remained in the 3+ oxidation state throughout the redox series. In this sense, the vanadium portion of the cluster mimics a conventional organic-based redox-active ligand bound to an iron(III) ion. Magnetic coupling within the hexanuclear cluster was characterized using SQUID magnetometry. Overall, the results suggest extensive electronic delocalization between the metal centers of the cluster core. These results demonstrate the ability of electronically flexible, reducible metal oxide supports to function as redox-active reservoirs for transition-metal centers.
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Sleep and mental health complaints are prevalent in the elderly and share common risk factors. We assessed the relationship between sleep and mental health in three representative samples of elderly women while controlling for multiple risk factors common to both. We performed this cross sectional secondary data analysis in 2015 using 2013 data from the Behavioral Risk Factor Surveillance System (BRFSS) for females ages 65 years and older from California (N = 1912), Florida (N = 9120), and Pennsylvania (N = 2429). We conducted multiple logistic regression analysis to assess the relationship between sleep duration group (short, moderate/reference, or long) and mental health issues in the past 30 days (yes or no) in elderly females, while controlling for multiple covariates. About 25% of the elderly females reported mental health issues and 20% reported short or long sleep durations. In adjusted analysis, compared to the elderly females in the moderate sleep duration group (averaging 6-8 h of sleep per day), those in the short and long sleep duration groups had increased prevalence of mental health issues by 66% and 26%, respectively. Mental health was also related to physical health issues including general health status, activity limitations, and chronic health conditions. Overall, sleep was related to mental health in representative samples of elderly females even after controlling for risk factors common to both. Even though we could not determine the direction of influence, the findings indicate a need for clinicians to screen their elderly female patients for both sleep and mental health issues, especially in those with physical health comorbidities.
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Salud Mental , Sueño , Factores de Edad , Anciano , Anciano de 80 o más Años , Sistema de Vigilancia de Factor de Riesgo Conductual , California , Estudios Transversales , Femenino , Florida , Conductas Relacionadas con la Salud , Estado de Salud , Humanos , Pennsylvania , Autoinforme , Factores Sexuales , Factores SocioeconómicosRESUMEN
Following previous work predicting the electronic response of the Chevrel phase Mo6S8 upon Mg insertion (Thöle et al., Phys. Chem. Chem. Phys., 2015, 17, 22548), we provide the experimental proof, evident in X-ray absorption spectroscopy, to illustrate the charge compensation mechanism of the Chevrel phase compound during Mg insertion and de-insertion processes.
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Cerebral edema often manifests after the development of cerebrovascular disease, particularly in the case of stroke, both ischemic and hemorrhagic. Without clinical intervention, the influx of water into brain tissues leads to increased intracranial pressure, cerebral herniation, and ultimately death. Strategies to manage the development of edema constitute a major unmet therapeutic need. However, despite its major clinical significance, the mechanisms underlying cerebral water transport and edema formation remain elusive. Aquaporins (AQPs) are a class of water channel proteins which have been implicated in the regulation of water homeostasis and cerebral edema formation, and thus represent a promising target for alleviating stroke-induced cerebral edema. This review examines the significance of relevant AQPs in stroke injury and subsequently explores neuroprotective strategies aimed at modulating AQP expression, with a particular focus on AQP4, the most abundant AQP in the central nervous system.
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Acuaporinas/metabolismo , Isquemia Encefálica/tratamiento farmacológico , Hemorragia Cerebral/tratamiento farmacológico , Accidente Cerebrovascular/tratamiento farmacológico , Isquemia Encefálica/metabolismo , Isquemia Encefálica/fisiopatología , Hemorragia Cerebral/metabolismo , Hemorragia Cerebral/fisiopatología , Humanos , Accidente Cerebrovascular/metabolismo , Accidente Cerebrovascular/fisiopatologíaRESUMEN
Infantile hemangiomas are commonly encountered at all levels of medical practice. Clinicians should be aware of their typical clinical history and findings in order to expedite early diagnosis and management. It is also necessary to be aware of differential diagnoses that may mimic infantile hemangiomas but have a more concerning prognosis. The objective of this report is to describe the clinical case of one such mimic, dermatofibrosarcoma protuberans. This report highlights key clinical findings of infantile hemangiomas, while also identifying "red flags" that necessitate urgent additional investigations and referral to a multidisciplinary team. Additionally, key features in the management of both infantile hemangiomas and extremity masses are discussed.
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BACKGROUND: Exercise-induced rhinitis (EIR) is a poorly understood phenomenon that may be related to increased inspiratory airflow. Characterization of the development of EIR is important to understand contributing factors. OBJECTIVE: To characterize how different nasal morphologies respond to airflow-related variables during rapid/deep inspiratory conditions. METHODS: Subject-specific nasal airways were reconstructed from radiographic images. Unilateral airways were classified as Standard, Notched, or Elongated accord to their distinct nasal vestibule morphology. Computational fluid dynamics simulations were performed at various airflow rates. RESULTS: For all simulated flow rates, average resistance at the nasal vestibule, airflow velocity and wall sheer stress were highest in Notched. Average mucosal heat flux was highest in Standard. Notched phenotypes showed lower mean percent increases from 10 L/min to 50 L/min in all computed variables. CONCLUSION: Resistance values and airflow velocities depicted a more constricted nasal vestibule in the Notched phenotypes, while perception of nasal mucosal cooling (heat flux) favored the Standard phenotypes. Different nasal phenotypes may predispose to EIR.
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Obstrucción Nasal , Rinitis , Humanos , Simulación por Computador , Cavidad Nasal/diagnóstico por imagen , Cavidad Nasal/anatomía & histología , Mucosa Nasal , HidrodinámicaRESUMEN
Metal-organic frameworks (MOFs) show remarkable potential in a broad array of applications given their physical and chemical versatility. Classical synthesis of MOFs is performed using solution chemistry at elevated temperatures to achieve reversible metal-ligand bond formation. These harsh conditions may not be suitable for chemical species sensitive to high temperature or prone to deleterious reactions with solvents. For instance, Pd(ii) is susceptible to reduction under solvothermal conditions and is not a common metal node of MOFs. We report a generic and facile mechanochemical strategy that directly incorporates a series of Pd(ii)-based heterobimetallic clusters into MOFs as metal nodes without Pd(ii) being reduced to Pd(0). Mechanochemistry features advantages of short reaction time, minimum solvent, high reaction yield, and high degree of synthetic control. Catalytic performances of lattice-confined heterobimetallic sites are examined for nitrene transfer reactions and we demonstrate that the chemoselectivity for allylic amination versus olefin aziridination is readily tuned by the identity of the first-row metal ion in Pd(ii)-based heterobimetallic clusters.