Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 35
Filtrar
Más filtros

Tipo del documento
Intervalo de año de publicación
1.
Pediatr Res ; 95(2): 566-572, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38057577

RESUMEN

BACKGROUND: Studies examining the association between in utero Zika virus (ZIKV) exposure and child neurodevelopmental outcomes have produced varied results. METHODS: We aimed to assess neurodevelopmental outcomes among normocephalic children born from pregnant people enrolled in the Zika in Pregnancy in Honduras (ZIPH) cohort study, July-December 2016. Enrollment occurred during the first prenatal visit. Exposure was defined as prenatal ZIKV IgM and/or ZIKV RNA result at enrollment. Normocephalic children, >6 months old, were selected for longitudinal follow-up using the Bayley Scales of Infant and Toddler Development (BSID-III) and the Ages & Stages Questionnaires: Social-Emotional (ASQ:SE-2). RESULTS: One hundred fifty-two children were assessed; after exclusion, 60 were exposed and 72 were unexposed to ZIKV during pregnancy. Twenty children in the exposed group and 21 children in the unexposed group had a composite score <85 in any of the BSID-III domains. Although exposed children had lower cognitive and language scores, differences were not statistically significant. For ASQ:SE-2 assessment, there were not statistically significant differences between groups. CONCLUSIONS: This study found no statistically significant differences in the neurodevelopment of normocephalic children between in utero ZIKV exposed and unexposed. Nevertheless, long-term monitoring of children with in utero ZIKV exposure is warranted. IMPACT: This study found no statistically significant differences in the neurodevelopment in normocephalic children with in utero Zika virus exposure compared to unexposed children, although the exposed group showed lower cognitive and language scores that persisted after adjustment by maternal age and education and after excluding children born preterm and low birth weight from the analysis. Children with prenatal Zika virus exposure, including those normocephalic and have no evidence of abnormalities at birth, should be monitored for neurodevelopmental delays. Follow-up is important to be able to detect developmental abnormalities that might not be detected earlier in life.


Asunto(s)
Craneosinostosis , Complicaciones Infecciosas del Embarazo , Efectos Tardíos de la Exposición Prenatal , Infección por el Virus Zika , Virus Zika , Embarazo , Lactante , Recién Nacido , Femenino , Humanos , Estudios de Cohortes , Infección por el Virus Zika/diagnóstico , Desarrollo Infantil
2.
BMC Public Health ; 24(1): 386, 2024 02 05.
Artículo en Inglés | MEDLINE | ID: mdl-38317103

RESUMEN

BACKGROUND: Chile has become a destination country for immigrants from Latin America, including youth. Guaranteeing access and use of sexual and reproductive health services for young migrants is crucial because of their overlapping experiences of transitioning to a new country and to adulthood. However, the existing evidence shows barriers to accessing sexual and reproductive healthcare among young migrant populations. In this context, the main objective of this article is to identify the barriers and facilitators that young migrants experience to access sexual and reproductive healthcare in the Tarapacá region of Chile. METHODS: A qualitative study was conducted in the Tarapacá region of Chile. Semi-structured interviews with 25 young migrants from Venezuela, Colombia, and Ecuador, as well as 10 health workers, were carried out. The interviews were transcribed and thematically analysed. The study was approved by the Ethics Committee of the Universidad del Desarrollo (#2019-22). RESULTS: Young migrants face barriers linked to structural shortcomings within the healthcare system, which may be similar to those faced by the local population. Barriers are also derived from reductionist sexual and reproductive health approaches, which prioritise the prevention of pregnancy, sexually transmitted infections, and HIV, with a predominantly heteronormative focus. The prevailing narratives from the health system are those of risk and lack of control and self-care among young people, and they are exacerbated in the case of migrants. Young migrants, especially from the Caribbean, are stereotyped as over-sexualised and liberal in comparison to the local population and believed to be engaging in riskier sexual behaviours that should be kept under check. This may translate into experiences of discrimination and mistreatment when receiving care. Facilitators include good-quality information and community-level interventions. CONCLUSIONS: This study shows a limited approach to the sexual and reproductive health of young migrants in Chile, severely hampering their reproductive and sexual rights. Policies and initiatives must work towards removing structural barriers, changing narratives, and empowering young migrants regarding their sexual and reproductive health.


Asunto(s)
Servicios de Salud Reproductiva , Migrantes , Embarazo , Femenino , Adolescente , Humanos , Chile , Conducta Sexual , Investigación Cualitativa , Salud Reproductiva , Accesibilidad a los Servicios de Salud
3.
Phys Chem Chem Phys ; 25(29): 19706-19712, 2023 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-37436820

RESUMEN

The design of additives for perovskite-based solar cells seeks to improve the balance between stability and power conversion efficiency. Organic molecules such as theophylline, theobromine and caffeine (xanthines) have proved to be a good engineering solution. As an alternative, we present a first-principles study of the use of organic cations as additives. These cations are obtained when the free nitrogen of the imidazole unit of the aforementioned molecules is quaternized. We have found that the interaction between the organic cations and the MAPbI3 perovskite surface is stronger compared to the organic molecules. The Pb-O and I-H bonds of the interface dominated these interactions. In addition, organic cations showed higher charge transfer through the interface and shallow states that are harmless and could improve the charge carrier mobility. These characteristics show that quaternized xanthines should be a promising additive for perovskite materials in photovoltaic applications.

4.
Nano Lett ; 22(6): 2578-2585, 2022 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-35143727

RESUMEN

Using four-dimensional scanning transmission electron microscopy, we demonstrate a method to visualize grains and grain boundaries in WSe2 grown by metal organic chemical vapor deposition (MOCVD) directly onto silicon dioxide. Despite the chemical purity and uniform thickness and texture of the MOCVD-grown WSe2, we observe a high density of small grains that corresponds with the overall selenium deficiency we measure through ion beam analysis. Moreover, reconstruction of grain information permits the creation of orientation maps that demonstrate the nucleation mechanism for new layers-triangular domains with the same orientation as the layer underneath induces a tensile strain increasing the lattice parameter at these sites.

5.
Small ; 16(49): e2005447, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33205629

RESUMEN

A new microwave-enhanced synthesis method for the production of tellurium nanostructures is reported-with control over products from the 1D regime (sub-5 nm diameter nanowires), to nanoribbons, to the 2D tellurene regime-along with a new methodology for local statistical quantification of the crystallographic parameters of these materials at the nanometer scale. Using a direct electron detector and image-corrected microscope, large and robust 4D scanning transmission electron microscopy datasets for accurate structural analysis are obtained. These datasets allow the adaptation of quantitative techniques originally developed for X-ray diffraction (XRD) refinement analyses to transmission electron microscopy, enabling the first demonstration of sub-picometer accuracy lattice parameter extraction while also obtaining both the size of the coherent crystallite domains and the nanostrain, which is observed to decrease as nanowires transition to tellurene. This new local analysis is commensurate with global powder XRD results, indicating the robustness of both the new synthesis approach and new structural analysis methodology for future scalable production of 2D tellurene and characterization of nanomaterials.

6.
BMC Womens Health ; 20(1): 199, 2020 09 12.
Artículo en Inglés | MEDLINE | ID: mdl-32919474

RESUMEN

BACKGROUND: Zika virus (ZIKV) infection during pregnancy has severe consequences on the new-born. The World Health Organization declared the Zika outbreak to be a Public Health Emergency of International Concern (PHEIC) in 2016. Health facilities in the regions most affected by Zika lacked the capacity to respond to the increased demand for contraception. The objectives were to explore healthcare users' perceptions regarding contraception, Zika prevention during pregnancy and post-abortion care (PAC) services in the context of a Zika outbreak in Tegucigalpa, Honduras, and to follow these services over time. METHODS: This study was part of a broader implementation research study. We used qualitative research consistent with grounded theory approach. Semi-structured interviews and focus groups were performed with women and their partners who used contraceptive services or received PAC services. Data were collected in two stages from December 2017 to July 2018. Themes explored included contraception, Zika and PAC services. RESULTS: Participants had positive attitude towards the use of contraceptive methods and demanded more information on safety, efficacy and on side effects. Health care services were inconsistent in the provision of information on Zika and contraception services. ZIKV vector transmission was known but fewer participants were aware of risk of sexual transmission of Zika. Barriers to access healthcare services included contraceptive and PAC services included distance to healthcare facilities, disorganized admission process, long waiting times and out-of-pocket expenditure to purchase medicines. Furthermore, poor quality, mistreatment and abuse of women seeking PAC was prevalent. Some positive changes were noted over time, such as improvements in infrastructure including improved privacy and cleanliness, removal of fees, requisite to bring clean water to hospital. CONCLUSIONS: Our results highlight the challenges and areas for improvement in policy and practice related to contraceptive services and PAC in the context of ZIKV infection. Public policies to prevent epidemics should focus more on providing proper sanitation; removing barriers to access and use of effective contraception as human rights priority. Zika epidemic has highlighted weaknesses in health systems that obstruct access to and use of sexual and reproductive health services. The study results call for increased efforts to improve access, especially for women of low socio-economic status and intervene at different levels to eradicate discrimination and improve equity in the provision of health care. Qualitative methods can capture the community perspectives and can provide useful information to develop interventions to improve services.


Asunto(s)
Aborto Inducido , Cuidados Posteriores , Anticoncepción/estadística & datos numéricos , Servicios de Planificación Familiar/organización & administración , Servicios de Salud Reproductiva/organización & administración , Infección por el Virus Zika/epidemiología , Virus Zika , Epidemias , Femenino , Honduras/epidemiología , Humanos , Masculino , Embarazo , Investigación Cualitativa
7.
Langmuir ; 32(30): 7572-81, 2016 08 02.
Artículo en Inglés | MEDLINE | ID: mdl-27385583

RESUMEN

The synthesis of Au@AgAu yolk-shell cuboctahedra nanoparticles formed by galvanic replacement in a seed-mediated method is described. Initially, single-crystal Au seeds are used for the formation of Au@Ag core-shell nanocubes, which serve as the template material for the deposition of an external Au layer. The well-controlled synthesis yields the formation of cuboctahedra nanoparticles with smooth inner and outer Au/Ag surfaces. The deposition/oxidation process is described to understand the formation of cuboctahedra and octahedra nanoparticles. The Au core maintains the initial morphology of the seed and remains static at the center of the yolk-shell because of residual Ag. Structural analysis of the shell indicates intrinsic stacking faults (SFs) near the surface. Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) compositional analysis show an Au-Ag nonordered alloy forming the shell. The three-dimensional structure of the nanoparticles presented open facets on the [111] as observed by electron tomography SIRT reconstruction over a stack of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images. The geometrical model was validated by analyzing the direction of streaks in coherent nanobeam diffraction (NBD). The catalytic activity was evaluated using a model reaction based on the reduction of 4-nitrophenol (4-NTP) by NaBH4 in the presence of Au@AgAu yolk-shell nanoparticles.


Asunto(s)
Oro/química , Nanopartículas del Metal/química , Plata/química , Borohidruros/química , Catálisis , Nanopartículas del Metal/ultraestructura , Microscopía Electrónica de Transmisión , Nitrofenoles/química , Oxidación-Reducción , Tamaño de la Partícula
8.
Medwave ; 24(7): e2931, 2024 Aug 27.
Artículo en Inglés, Español | MEDLINE | ID: mdl-39190918

RESUMEN

The presence of children and adolescents in migratory flows is growing in Latin America and the Caribbean. Little is known about migration's effects on these groups' health. This article aims to investigate the evidence available on the access and use of healthcare services by migrant children and adolescents in Latin America and the Caribbean. We seek to explore the role of social determinants of health at different levels in the health conditions of these groups. Also, to identify potential recommendations for healthcare systems and public policy to address them. For this purpose, a narrative review of 52 publications was carried out based on a search of scientific literature in the Web of Science and Google Scholar databases. Five relevant topics were identified: use of emergency care associated with lack of healthcare access, preventive services, and other social determinants of health; exposure to preventable infectious diseases; mental health; sexual and reproductive health; and vaccinations and dental health. We conclude that the evidence shows the need to address the inequities and disadvantages faced by migrant children from a perspective of social determinants of health and policies that consider health as a human right regardless of the migratory status of children and adolescents, as well as that of their parents or primary caregivers.


En Latinoamérica y El Caribe la presencia de niños, niñas y adolescentes en los flujos migratorios internacionales es creciente. Los efectos que la migración genera sobre la salud de estos grupos han sido poco estudiados. El objetivo de este artículo es indagar en las principales evidencias reportadas respecto al acceso y uso de servicios de salud por parte de niños, niñas y adolescentes migrantes en América Latina y El Caribe. Esto, con la finalidad de reflexionar sobre el rol que cumplen los determinantes sociales de la salud de diverso nivel, en las condiciones de salud de estos grupos. También se busca identificar recomendaciones para su abordaje desde los sistemas de salud y la política pública. Para ello se realizó una revisión narrativa de 52 publicaciones sobre la base de un proceso de búsqueda de literatura científica de la base de datos y Google Académico. Se identificaron cinco temas relevantes: uso de urgencias asociado a falta de acceso a salud, a servicios preventivos y a otros determinantes sociales de la salud; exposición a enfermedades infecciosas prevenibles; salud mental; salud sexual y reproductiva; y vacunaciones y salud dental. Concluimos que la evidencia muestra la necesidad de abordar las inequidades y desventajas que están acumulando estos grupos, desde una óptica de determinantes sociales de la salud y de políticas que consideren la salud como derecho humano independiente de la situación migratoria de los niños, niñas y adolescentes, así como la de sus padres o cuidadores principales.


Asunto(s)
Accesibilidad a los Servicios de Salud , Determinantes Sociales de la Salud , Migrantes , Humanos , Adolescente , América Latina , Niño , Región del Caribe , Política de Salud , Atención a la Salud/organización & administración , Estado de Salud , Salud Infantil
9.
J Am Heart Assoc ; 13(10): e033998, 2024 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-38726925

RESUMEN

BACKGROUND: The vasoconstrictor effects of angiotensin II via type 1 angiotensin II receptors in vascular smooth muscle cells are well established, but the direct effects of angiotensin II on vascular endothelial cells (VECs) in vivo and the mechanisms how VECs may mitigate angiotensin II-mediated vasoconstriction are not fully understood. The present study aimed to explore the molecular mechanisms and pathophysiological relevance of the direct actions of angiotensin II on VECs in kidney and brain microvessels in vivo. METHODS AND RESULTS: Changes in VEC intracellular calcium ([Ca2+]i) and nitric oxide (NO) production were visualized by intravital multiphoton microscopy of cadherin 5-Salsa6f mice or the endothelial uptake of NO-sensitive dye 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate, respectively. Kidney fibrosis by unilateral ureteral obstruction and Ready-to-use adeno-associated virus expressing Mouse Renin 1 gene (Ren1-AAV) hypertension were used as disease models. Acute systemic angiotensin II injections triggered >4-fold increases in VEC [Ca2+]i in brain and kidney resistance arterioles and capillaries that were blocked by pretreatment with the type 1 angiotensin II receptor inhibitor losartan, but not by the type 2 angiotensin II receptor inhibitor PD123319. VEC responded to acute angiotensin II by increased NO production as indicated by >1.5-fold increase in 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate fluorescence intensity. In mice with kidney fibrosis or hypertension, the angiotensin II-induced VEC [Ca2+]i and NO responses were significantly reduced, which was associated with more robust vasoconstrictions, VEC shedding, and microthrombi formation. CONCLUSIONS: The present study directly visualized angiotensin II-induced increases in VEC [Ca2+]i and NO production that serve to counterbalance agonist-induced vasoconstriction and maintain residual organ blood flow. These direct and endothelium-specific angiotensin II effects were blunted in disease conditions and linked to endothelial dysfunction and the development of vascular pathologies.


Asunto(s)
Angiotensina II , Encéfalo , Calcio , Hipertensión , Riñón , Microvasos , Óxido Nítrico , Vasoconstricción , Animales , Ratones , Angiotensina II/farmacología , Encéfalo/metabolismo , Encéfalo/irrigación sanguínea , Calcio/metabolismo , Señalización del Calcio/efectos de los fármacos , Modelos Animales de Enfermedad , Células Endoteliales/metabolismo , Células Endoteliales/efectos de los fármacos , Hipertensión/metabolismo , Hipertensión/fisiopatología , Hipertensión/tratamiento farmacológico , Riñón/irrigación sanguínea , Riñón/metabolismo , Ratones Endogámicos C57BL , Microvasos/metabolismo , Microvasos/efectos de los fármacos , Microvasos/patología , Óxido Nítrico/metabolismo , Vasoconstricción/efectos de los fármacos
10.
J Clin Invest ; 134(11)2024 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-38598837

RESUMEN

Tissue regeneration is limited in several organs, including the kidney, contributing to the high prevalence of kidney disease globally. However, evolutionary and physiological adaptive responses and the presence of renal progenitor cells suggest an existing remodeling capacity. This study uncovered endogenous tissue remodeling mechanisms in the kidney that were activated by the loss of body fluid and salt and regulated by a unique niche of a minority renal cell type called the macula densa (MD). Here, we identified neuronal differentiation features of MD cells that sense the local and systemic environment and secrete angiogenic, growth, and extracellular matrix remodeling factors, cytokines and chemokines, and control resident progenitor cells. Serial intravital imaging, MD nerve growth factor receptor and Wnt mouse models, and transcriptome analysis revealed cellular and molecular mechanisms of these MD functions. Human and therapeutic translation studies illustrated the clinical potential of MD factors, including CCN1, as a urinary biomarker and therapeutic target in chronic kidney disease. The concept that a neuronally differentiated key sensory and regulatory cell type responding to organ-specific physiological inputs controls local progenitors to remodel or repair tissues may be applicable to other organs and diverse tissue-regenerative therapeutic strategies.


Asunto(s)
Diferenciación Celular , Regeneración , Animales , Ratones , Humanos , Riñón/metabolismo , Neuronas/metabolismo , Neuronas/patología , Insuficiencia Renal Crónica/patología , Insuficiencia Renal Crónica/metabolismo , Insuficiencia Renal Crónica/fisiopatología , Insuficiencia Renal Crónica/genética , Masculino
11.
Cureus ; 15(12): e50432, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38222180

RESUMEN

Platelet storage deficiencies are a heterogeneous group of bleeding disorders of variable severity caused by decreased number or content of platelet granules. We present the case of a 10-year-old patient with no personal history of previous bleeding who was admitted to the emergency department due to menorrhagia and mucocutaneous pallor. Common disorders of primary and secondary hemostasis were ruled out. Subsequently, a study of electron microscopy of platelets was performed, which reported the presence of alpha granules with a decreased number of dense granules. Currently, the patient receives treatment with tranexamic acid during menstrual periods, supplementation with ferrous sulfate, and oral contraceptives, achieving control of bleeding episodes.

12.
Cureus ; 15(2): e34549, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36879711

RESUMEN

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare but aggressive malignancy with high mortality involving the skin and hematopoietic system. Clinical suspicion is difficult, and management of skin lesions is challenging due to their indolent course prior to dissemination. We describe a patient with isolated skin involvement who progressed to CD4+/CD56+ and CD123+ acute leukemia.

13.
Artículo en Inglés | MEDLINE | ID: mdl-36767326

RESUMEN

The COVID-19 pandemic has further deepened socioeconomic and health inequities worldwide, especially among populations experiencing social vulnerability, such as international migrants. Sustained lockdowns and social distancing have raised challenges to conducting public health research with hard-to-reach populations. This study aims at exploring strategies to recruit "hard-to-reach" international migrants for qualitative public health research during the pandemic in Chile, based on the authors' experience. A retrospective qualitative evaluation process was carried out on the recruitment processes of three qualitative research projects focused on international migrants in Chile. All projects were implemented during the COVID-19 pandemic, demanding complementary and flexible strategies: (i) social media; (ii) snowball sampling; (iii) referrals from social workers and pro-migrant and migrant-led organizations; (iv) vaccination centers and healthcare centers; and (v) community-based recruitment. The strategies are qualitatively evaluated around seven emerging qualitative categories: (i) feasibility during lockdown periods; (ii) speed of recruitment; (iii) geographical coverage; (iv) sample diversity; (v) proportion of successful interviews; (vi) ethical considerations; and (vii) cost. Engaging hard-to-reach international migrants in public health research during the pandemic required constantly adapting recruitment strategies. Furthermore, relying on strategies that were not only Internet-based promoted the participation of populations with limited access to the Internet and low-digital literacy.


Asunto(s)
COVID-19 , Migrantes , Humanos , COVID-19/epidemiología , Pandemias , Salud Pública , Chile/epidemiología , Estudios Retrospectivos , Control de Enfermedades Transmisibles , Investigación Cualitativa
14.
Cureus ; 15(11): e48394, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-38074010

RESUMEN

BACKGROUND: Germ cell tumors (GCTs) represent a diverse group of rare neoplasms that vary in location, histology, and clinical presentation. This study focuses on the clinical outcomes and survival rates of children and adolescents treated with the bleomycin, etoposide, and cisplatin (BEP) protocol. METHODS: This observational study evaluated children under 18 years diagnosed with testicular germ cell tumors and treated with the BEP protocol from January 2008 to December 2018. We employed descriptive analysis and used the Kaplan-Meier method to calculate event-free survival (EFS) and overall survival rates. RESULTS: The study included 32 patients with an average age of 9.8 years (SD ± 6.7). The primary reason for consultation was a testicular mass. The classification of patients was E-I for 14 patients (44%) and E-III and E-IV for nine patients (28%). Endodermal sinus tumors and mixed germ cell tumors were the most commonly identified histological types. With a median follow-up of 7.8 years (95% confidence interval {CI}: 5.9-9.6), the event-free survival was 63.7%. The overall survival at a median follow-up of 9.1 years (95% CI: 7.5-10.7) was 76.1%. CONCLUSION: The BEP chemotherapy regimen offers promising results for treating testicular germ cell tumors in children and adolescents, characterized by its low toxicity and minimal late side effects. However, patients older than 11 years displayed more adverse histological indicators, advanced disease stages, and higher relapse and mortality rates.

15.
Artículo en Inglés | MEDLINE | ID: mdl-36429892

RESUMEN

In parallel to the COVID-19 pandemic, Chile has experienced a significant influx of international migrants, many of whom are Venezuelan women who have entered the country through unauthorized crossing points. In this context, gender and migration intersect as the social determinants of health, leading to their experiencing a range of adverse events. This poses important challenges in terms of short- and long-term health outcomes, the social determinants of health, and access to healthcare. This study aims at describing Venezuelan women's perceptions of their health needs as they migrate to Chile via an unauthorized crossing point, with a focus on adverse events throughout the migration cycle, self-reported health needs, and responses. A qualitative case study was carried out with 22 participants in the Antofagasta region of Chile, including Venezuelan migrant women, healthcare professionals, and social workers from the public healthcare system, stakeholders from non-governmental and international organizations, and local government officials. The semi-structured, individual interviews were analyzed thematically. The results show that Venezuelan women face a range of adverse events throughout the migration cycle. The perceived health needs that are reported are sometimes linked to these adverse events or existed prior to migration and were exacerbated throughout the migratory cycle. Addressing these physical and mental health needs is essential for short- and long-term individual and public health; however, despite substantial efforts to ameliorate the situation, persisting gaps in access to care are reported.


Asunto(s)
COVID-19 , Migrantes , Humanos , Femenino , COVID-19/epidemiología , Chile/epidemiología , Pandemias , Personal de Salud/psicología
16.
Materials (Basel) ; 15(10)2022 May 12.
Artículo en Inglés | MEDLINE | ID: mdl-35629503

RESUMEN

This paper reports on the manufacturing of complex three-dimensional Si/C structures via a chemical vapor deposition method. The structure and properties of the grown materials were characterized using various techniques including scanning electron microscopy, aberration-corrected transmission electron microscopy, confocal Raman spectroscopy, and X-ray photoelectron spectroscopy. The spectroscopy results revealed that the grown materials were composed of micro/nanostructures with various compositions and dimensions. These included two-dimensional silicon carbide (SiC), cubic silicon, and various SiC polytypes. The coexistence of these phases at the nano-level and their interfaces can benefit several Si/C-based applications ranging from ceramics and structural applications to power electronics, aerospace, and high-temperature applications. With an average density of 7 mg/cm3, the grown materials can be considered ultralightweight, as they are three orders of magnitude lighter than bulk Si/C materials. This study aims to impact how ceramic materials are manufactured, which may lead to the design of new carbide materials or Si/C-based lightweight structures with additional functionalities and desired properties.

17.
Nanoscale ; 13(21): 9606-9614, 2021 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-34002755

RESUMEN

Robust atomic-to-meso-scale chirality is now observed in the one-dimensional form of tellurium. This enables a large and counter-intuitive circular-polarization dependent second harmonic generation response above 0.2 which is not present in two-dimensional tellurium. Orientation variations in 1D tellurium nanowires obtained by four-dimensional scanning transmission electron microscopy (4D-STEM) and their correlation with unconventional non-linear optical properties by second harmonic generation circular dichroism (SHG-CD) uncovers an unexpected circular-polarization dependent SHG response from 1D nanowire bundles - an order-of-magnitude higher than in single-crystal two-dimensional tellurium structures - suggesting the atomic- and meso-scale crystalline structure of the 1D material possesses an inherent chirality not present in its 2D form; and which is strong enough to manifest even in the aggregate non-linear optical (NLO) properties of aggregates.

18.
Am J Trop Med Hyg ; 104(5): 1737-1740, 2021 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-33724927

RESUMEN

The impact of Zika virus (ZIKV) infection on pregnancies shows regional variation emphasizing the importance of studies in different geographical areas. We conducted a prospective study in Tegucigalpa, Honduras, recruiting 668 pregnant women between July 20, 2016, and December 31, 2016. We performed Trioplex real-time reverse transcriptase-PCR (rRT-PCR) in 357 serum samples taken at the first prenatal visit. The presence of ZIKV was confirmed in seven pregnancies (7/357, 2.0%). Nine babies (1.6%) had microcephaly (head circumference more than two SDs below the mean), including two (0.3%) with severe microcephaly (head circumference [HC] more than three SDs below the mean). The mothers of both babies with severe microcephaly had evidence of ZIKV infection. A positive ZIKV Trioplex rRT-PCR was associated with a 33.3% (95% CI: 4.3-77.7%) risk of HC more than three SDs below the mean.


Asunto(s)
Microcefalia/diagnóstico , Complicaciones Infecciosas del Embarazo/diagnóstico , Infección por el Virus Zika/diagnóstico , Virus Zika/genética , Adolescente , Adulto , Femenino , Edad Gestacional , Honduras/epidemiología , Humanos , Incidencia , Microcefalia/complicaciones , Microcefalia/epidemiología , Microcefalia/virología , Embarazo , Complicaciones Infecciosas del Embarazo/epidemiología , Complicaciones Infecciosas del Embarazo/virología , Diagnóstico Prenatal/métodos , Estudios Prospectivos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Infección por el Virus Zika/complicaciones , Infección por el Virus Zika/epidemiología , Infección por el Virus Zika/virología
19.
J Neurooncol ; 98(3): 379-84, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20013146

RESUMEN

Meningiomas are benign tumors, with low rate of recurrence after surgery. The most important factor predicting recurrence is the extent of surgical resection; other factors have been studied with conflicting results. Angiogenesis, an important substratum for growth and spread of neoplasic cells, and the expression of estrogen and progesterone receptors (ER, PR), could play a role in the recurrence of meningioma. We evaluated 42 patients with meningioma diagnosis (confirmed by histopathology) treated exclusively by surgery between January 1995 and December 1999, and compared the recurring and non-recurring groups after a ten-year follow-up period. Recurrence was associated with several factors including vascular density (VD), cell proliferation index (CPI), ER, PR, and cyclin E (CE) tissue expression, as evaluated by immunohistochemistry. Complete surgical resection was achieved in 41% of patients. Recurrence of meningioma was found in 17 patients (40%). Median + or - standard deviation (SD) of recurrence time was 32 + or - 5 months. When recurrence versus no recurrence was compared, mean + or - SD of VD and CPI were 9 + or - 3.6 and 607.6 + or - 233 (40x/10 fields) respectively. Tissue expression was positive for ER, PR, and CE in 28, 62 and 91% of patients, respectively. The sole significant recurrence-associated factors were extent of resection (P = 0.003) and VD (P = 0.004). ER, PR, and CE-tissue expression were not statistically significant. The most important factor associated with meningioma relapse was vascular density, independently of hormonal status and extent of surgical resection. Patients with a high risk of recurrence could benefit from additional treatment.


Asunto(s)
Neoplasias Meníngeas/metabolismo , Meningioma/metabolismo , Recurrencia Local de Neoplasia/diagnóstico , Neovascularización Patológica/etiología , Receptores de Estrógenos/metabolismo , Receptores de Progesterona/metabolismo , Adulto , Estudios de Casos y Controles , Estudios de Cohortes , Ciclina E/metabolismo , Femenino , Humanos , Masculino , Neoplasias Meníngeas/complicaciones , Neoplasias Meníngeas/patología , Meningioma/complicaciones , Meningioma/patología , Persona de Mediana Edad , Estudios Retrospectivos
20.
Cureus ; 12(9): e10651, 2020 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-33133821

RESUMEN

Background This is a retrospective case series, and the main objective is to describe the epidemiology, clinical features, and outcomes of pediatric acute respiratory distress syndrome in patients at moderate altitude. Methods Children from the Pediatric Intensive Care Unit (PICU) at the Fundación Cardioinfantil, hospitalized with acute respiratory distress syndrome, were prospectively enrolled from March 2009 to March 2014. We evaluated the demographic data, mechanical ventilation, gas exchange, hemodynamics, and multiorgan dysfunction. Results During the study period, 88 patients met the inclusion criteria. Bronchiolitis and pneumonia were the most common causes of acute respiratory distress syndrome. The overall mortality rate was 19.5%. At the beginning of the study, the average relation between blood pressure and the fraction of inspired oxygen (Pa/Fi) was 130.3 ± 52.2; tidal volume was 7.94 ± 1.7 ml/kg, the plateau pressure 25.3 ± 5.09 cmH2O, and positive end-expiratory pressure was 7.2 ± 3.2 cmH2O. After 24 hours, the mortality rate in the group with severe acute respiratory distress syndrome (Pa/Fi <100) was 46.7%, in the moderate acute respiratory distress syndrome group (Pa/Fi 100-200) it was 11.9%, and finally in the mild acute respiratory distress syndrome group (Pa/Fi 200-300) the mortality was 25%. This study found a relation between serum lactate value and positive end-expiratory pressure and mortality (p = 0.02 and 0.0013). Conclusions This study shows that pediatric acute respiratory distress syndrome patients at moderate altitudes have similar clinical behavior, including mortality rate, to those at low altitudes. However, Pa/Fi is not a good predictor of mortality for patients with mild and moderate acute respiratory distress syndrome.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA