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1.
Medicina (Kaunas) ; 58(10)2022 Sep 26.
Artículo en Inglés | MEDLINE | ID: mdl-36295509

RESUMEN

Background and Objectives: We developed a predictive statistical model to identify donor-recipient characteristics related to kidney graft survival in the Chilean population. Given the large number of potential predictors relative to the sample size, we implemented an automated variable selection mechanism that could be revised in future studies as more national data is collected. Materials and Methods: A retrospective multicenter study was conducted to analyze data from 822 adult kidney transplant recipients from adult donors between 1998 and 2018. To the best of our knowledge, this is the largest kidney transplant database to date in Chile. A procedure based on a cross-validated regularized Cox regression using the Elastic Net penalty was applied to objectively identify predictors of death-censored graft failure. Hazard ratios were estimated by adjusting a multivariate Cox regression with the selected predictors. Results: Seven variables were associated with the risk of death-censored graft failure; four from the donor: age (HR = 1.02, 95% CI: 1.00-1.03), male sex (HR = 0.64, 95% CI: 0.46-0.90), history of hypertension (HR = 1.49, 95% CI: 0.98-2.28), and history of diabetes (HR = 2.04, 95% CI: 0.97-4.29); two from the recipient: years on dialysis log-transformation (HR = 1.29, 95% CI: 0.99-1.67) and history of previous solid organ transplantation (HR = 2.02, 95% CI: 1.18-3.47); and one from the transplant: number of HLA mismatches (HR = 1.13, 95% CI: 0.99-1.28). Only the latter is considered for patient prioritization in deceased kidney allocation in Chile. Conclusions: A risk model for kidney graft failure was developed and trained for the Chilean population, providing objective criteria which can be used to improve efficiency in deceased kidney allocation.


Asunto(s)
Supervivencia de Injerto , Trasplante de Riñón , Adulto , Masculino , Humanos , Chile/epidemiología , Diálisis Renal , Trasplante de Riñón/métodos , Riñón , Estudios Retrospectivos , Rechazo de Injerto , Factores de Riesgo
2.
Nano Lett ; 20(1): 306-313, 2020 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-31809058

RESUMEN

The compensated magnetic order and characteristic terahertz frequencies of antiferromagnetic materials make them promising candidates to develop a new class of robust, ultrafast spintronic devices. The manipulation of antiferromagnetic spin-waves in thin films is anticipated to lead to new exotic phenomena such as spin-superfluidity, requiring an efficient propagation of spin-waves in thin films. However, the reported decay length in thin films has so far been limited to a few nanometers. In this work, we achieve efficient spin-wave propagation over micrometer distances in thin films of the insulating antiferromagnet hematite with large magnetic domains while evidencing much shorter attenuation lengths in multidomain thin films. Through transport and magnetic imaging, we determine the role of the magnetic domain structure and spin-wave scattering at domain walls to govern the transport. We manipulate the spin transport by tailoring the domain configuration through field cycle training. For the appropriate crystalline orientation, zero-field spin transport is achieved across micrometers, as required for device integration.

3.
Phys Rev Lett ; 123(16): 167203, 2019 Oct 18.
Artículo en Inglés | MEDLINE | ID: mdl-31702374

RESUMEN

Electrons and holes residing on the opposing sides of an insulating barrier and experiencing an attractive Coulomb interaction can spontaneously form a coherent state known as an indirect exciton condensate. We study a trilayer system where the barrier is an antiferromagnetic insulator. The electrons and holes here additionally interact via interfacial coupling to the antiferromagnetic magnons. We show that by employing magnetically uncompensated interfaces, we can design the magnon-mediated interaction to be attractive or repulsive by varying the thickness of the antiferromagnetic insulator by a single atomic layer. We derive an analytical expression for the critical temperature T_{c} of the indirect exciton condensation. Within our model, anisotropy is found to be crucial for achieving a finite T_{c}, which increases with the strength of the exchange interaction in the antiferromagnetic bulk. For realistic material parameters, we estimate T_{c} to be around 7 K, the same order of magnitude as the current experimentally achievable exciton condensation where the attraction is solely due to the Coulomb interaction. The magnon-mediated interaction is expected to cooperate with the Coulomb interaction for condensation of indirect excitons, thereby providing a means to significantly increase the exciton condensation temperature range.

4.
Phys Rev Lett ; 123(11): 117203, 2019 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-31573230

RESUMEN

Magnons in ferromagnets behave as a viscous fluid over a length scale, the momentum-relaxation length, below which momentum-conserving scattering processes dominate. We show theoretically that in this hydrodynamic regime viscous effects lead to a sign change in the magnon chemical potential, which can be detected as a sign change in the nonlocal resistance measured in spin transport experiments. This sign change is observable when the injector-detector distance becomes comparable to the momentum-relaxation length. Taking into account momentum- and spin-relaxation processes, we consider the quasiconservation laws for momentum and spin in a magnon fluid. The resulting equations are solved for nonlocal spin transport devices in which spin is injected and detected via metallic leads. Because of the finite viscosity we also find a backflow of magnons close to the injector lead. Our work shows that nonlocal magnon spin transport devices are an attractive platform to develop and study magnon-fluid dynamics.

5.
PLoS Med ; 15(5): e1002572, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29799874

RESUMEN

BACKGROUND: Anti-human leukocyte antigen donor-specific antibodies (anti-HLA DSAs) are recognized as a major barrier to patients' access to organ transplantation and the major cause of graft failure. The capacity of circulating anti-HLA DSAs to activate complement has been suggested as a potential biomarker for optimizing graft allocation and improving the rate of successful transplantations. METHODS AND FINDINGS: To address the clinical relevance of complement-activating anti-HLA DSAs across all solid organ transplant patients, we performed a meta-analysis of their association with transplant outcome through a systematic review, from inception to January 31, 2018. The primary outcome was allograft loss, and the secondary outcome was allograft rejection. A comprehensive search strategy was conducted through several databases (Medline, Embase, Cochrane, and Scopus). A total of 5,861 eligible citations were identified. A total of 37 studies were included in the meta-analysis. Studies reported on 7,936 patients, including kidney (n = 5,991), liver (n = 1,459), heart (n = 370), and lung recipients (n = 116). Solid organ transplant recipients with circulating complement-activating anti-HLA DSAs experienced an increased risk of allograft loss (pooled HR 3.09; 95% CI 2.55-3.74, P = 0.001; I2 = 29.3%), and allograft rejection (pooled HR 3.75; 95% CI: 2.05-6.87, P = 0.001; I2 = 69.8%) compared to patients without complement-activating anti-HLA DSAs. The association between circulating complement-activating anti-HLA DSAs and allograft failure was consistent across all subgroups and sensitivity analyses. Limitations of the study are the observational and retrospective design of almost all included studies, the higher proportion of kidney recipients compared to other solid organ transplant recipients, and the inclusion of fewer studies investigating allograft rejection. CONCLUSIONS: In this study, we found that circulating complement-activating anti-HLA DSAs had a significant deleterious impact on solid organ transplant survival and risk of rejection. The detection of complement-activating anti-HLA DSAs may add value at an individual patient level for noninvasive biomarker-guided risk stratification. TRIAL REGISTRATION: National Clinical Trial protocol ID: NCT03438058.


Asunto(s)
Anticuerpos/inmunología , Activación de Complemento/inmunología , Supervivencia de Injerto/inmunología , Antígenos HLA/inmunología , Inmunología del Trasplante/inmunología , Rechazo de Injerto/inmunología , Humanos
7.
Phys Rev Lett ; 120(17): 177202, 2018 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-29756816

RESUMEN

Motivated by recent experimental work, we consider spin transport between a normal metal and a gapped quantum paramagnet. We model the latter as the magnonic Mott-insulating phase of an easy-plane ferromagnetic insulator. We evaluate the spin current mediated by the interface exchange coupling between the ferromagnet and the adjacent normal metal. For the strongly interacting magnons that we consider, this spin current gives rise to a spin Hall magnetoresistance that strongly depends on the magnitude of the magnetic field, rather than its direction. This Letter may motivate electrical detection of the phases of quantum magnets and the incorporation of such materials into spintronic devices.

8.
Vaccines (Basel) ; 11(5)2023 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-37243116

RESUMEN

Chronic kidney disease (CKD) patients have an increased risk of morbidity and mortality following SARS-CoV-2 infection. Vaccination in these patients is prioritized, and monitoring of the immune response is paramount to define further vaccination strategies. This prospective study included a cohort of 100 adult CKD patients: 48 with kidney transplant (KT) and 52 on hemodialysis without prior COVID-19. The patients were assessed for humoral and cellular immune responses after four months of an anti-SARS-CoV-2 primary two-dose vaccination scheme (CoronaVac or BNT162b2) and one month after a booster third dose of BNT162b2 vaccine. We identified poor cellular and humoral immune responses in the CKD patients after a primary vaccination scheme, and these responses were improved by a booster. Robust polyfunctional CD4+ T cell responses were observed in the KT patients after a booster, and this could be attributed to a higher proportion of the patients having been vaccinated with homologous BNT162b2 schemes. However, even after the booster, the KT patients exhibited lower neutralizing antibodies, attributable to specific immunosuppressive treatments. Four patients suffered severe COVID-19 despite three-dose vaccination, and all had low polyfunctional T-cell responses, underscoring the importance of this functional subset in viral protection. In conclusion, a booster dose of SARS-CoV-2 mRNA vaccine in CKD patients improves the impaired humoral and cellular immune responses observed after a primary vaccination scheme.

9.
Artículo en Inglés | MEDLINE | ID: mdl-35886240

RESUMEN

Currently, researchers are focused on the study of cytokines as predictive biomarkers of peri-implantitis (PI) in order to obtain an early diagnosis and prognosis, and for treatment of the disease. The aim of the study was to characterize the peri-implant soft and hard tissues in patients with a peri-implantitis diagnosis. A descriptive observational study was conducted. Fifteen soft tissue (ST) samples and six peri-implant bone tissue (BT) samples were obtained from 13 patients who were diagnosed with peri-implantitis. All the samples were processed and embedded in paraffin for histological and immunohistochemical analyses. A descriptive and quantitative analysis of mast cells and osteocytes, A proliferation-inducing ligand (APRIL), B-cell activating factor (BAFF), osteonectin (ON), and ∝-smooth muscle actin (∝-SMA) was performed. We observed the presence of mast cells in peri-implant soft tissue in all samples (mean 9.21 number of mast cells) and osteocytes in peri-implant hard tissue in all samples (mean 37.17 number of osteocytes). The expression of APRIL-ST was 32.17% ± 6.39%, and that of APRIL-BT was 7.09% ± 5.94%. The BAFF-ST expression was 17.26 ± 12.90%, and the BAFF-BT was 12.16% ± 6.30%. The mean percentage of ON was 7.93% ± 3.79%, and ∝-SMA was 1.78% ± 3.79%. It was concluded that the expression of APRIL and BAFF suggests their involvement in the bone resorption observed in peri-implantitis. The lower expression of osteonectin in the peri-implant bone tissue can also be associated with a deficiency in the regulation of bone remodeling and the consequent peri-implant bone loss.


Asunto(s)
Resorción Ósea , Periimplantitis , Biomarcadores , Citocinas , Humanos , Osteonectina
10.
Lancet Digit Health ; 3(12): e795-e805, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34756569

RESUMEN

BACKGROUND: Kidney allograft failure is a common cause of end-stage renal disease. We aimed to develop a dynamic artificial intelligence approach to enhance risk stratification for kidney transplant recipients by generating continuously refined predictions of survival using updates of clinical data. METHODS: In this observational study, we used data from adult recipients of kidney transplants from 18 academic transplant centres in Europe, the USA, and South America, and a cohort of patients from six randomised controlled trials. The development cohort comprised patients from four centres in France, with all other patients included in external validation cohorts. To build deeply phenotyped cohorts of transplant recipients, the following data were collected in the development cohort: clinical, histological, immunological variables, and repeated measurements of estimated glomerular filtration rate (eGFR) and proteinuria (measured using the proteinuria to creatininuria ratio). To develop a dynamic prediction system based on these clinical assessments and repeated measurements, we used a Bayesian joint models-an artificial intelligence approach. The prediction performances of the model were assessed via discrimination, through calculation of the area under the receiver operator curve (AUC), and calibration. This study is registered with ClinicalTrials.gov, NCT04258891. FINDINGS: 13 608 patients were included (3774 in the development cohort and 9834 in the external validation cohorts) and contributed 89 328 patient-years of data, and 416 510 eGFR and proteinuria measurements. Bayesian joint models showed that recipient immunological profile, allograft interstitial fibrosis and tubular atrophy, allograft inflammation, and repeated measurements of eGFR and proteinuria were independent risk factors for allograft survival. The final model showed accurate calibration and very high discrimination in the development cohort (overall dynamic AUC 0·857 [95% CI 0·847-0·866]) with a persistent improvement in AUCs for each new repeated measurement (from 0·780 [0·768-0·794] to 0·926 [0·917-0·932]; p<0·0001). The predictive performance was confirmed in the external validation cohorts from Europe (overall AUC 0·845 [0·837-0·854]), the USA (overall AUC 0·820 [0·808-0·831]), South America (overall AUC 0·868 [0·856-0·880]), and the cohort of patients from randomised controlled trials (overall AUC 0·857 [0·840-0·875]). INTERPRETATION: Because of its dynamic design, this model can be continuously updated and holds value as a bedside tool that could refine the prognostic judgements of clinicians in everyday practice, hence enhancing precision medicine in the transplant setting. FUNDING: MSD Avenir, French National Institute for Health and Medical Research, and Bettencourt Schueller Foundation.


Asunto(s)
Aloinjertos , Inteligencia Artificial , Trasplante de Riñón , Riñón/cirugía , Modelos Biológicos , Complicaciones Posoperatorias , Insuficiencia Renal/diagnóstico , Adulto , Área Bajo la Curva , Teorema de Bayes , Femenino , Tasa de Filtración Glomerular , Humanos , Masculino , Persona de Mediana Edad , Pronóstico , Proteinuria , Insuficiencia Renal/cirugía , Reproducibilidad de los Resultados , Medición de Riesgo , Receptores de Trasplantes
11.
Lancet Public Health ; 6(10): e709-e719, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34474014

RESUMEN

BACKGROUND: Preliminary data suggest that COVID-19 has reduced access to solid organ transplantation. However, the global consequences of the COVID-19 pandemic on transplantation rates and the effect on waitlisted patients have not been reported. We aimed to assess the effect of the COVID-19 pandemic on transplantation and investigate if the pandemic was associated with heterogeneous adaptation in terms of organ transplantation, with ensuing consequences for waitlisted patients. METHODS: In this population-based, observational, before-and-after study, we collected and validated nationwide cohorts of consecutive kidney, liver, lung, and heart transplants from 22 countries. Data were collected from Jan 1 to Dec 31, 2020, along with data from the same period in 2019. The analysis was done from the onset of the 100th cumulative COVID-19 case through to Dec 31, 2020. We assessed the effect of the pandemic on the worldwide organ transplantation rate and the disparity in transplant numbers within each country. We estimated the number of waitlisted patient life-years lost due to the negative effects of the pandemic. The study is registered with ClinicalTrials.gov, NCT04416256. FINDINGS: Transplant activity in all countries studied showed an overall decrease during the pandemic. Kidney transplantation was the most affected, followed by lung, liver, and heart. We identified three organ transplant rate patterns, as follows: countries with a sharp decrease in transplantation rate with a low COVID-19-related death rate; countries with a moderate decrease in transplantation rate with a moderate COVID-19-related death rate; and countries with a slight decrease in transplantation rate despite a high COVID-19-related death rate. Temporal trends revealed a marked worldwide reduction in transplant activity during the first 3 months of the pandemic, with losses stabilising after June, 2020, but decreasing again from October to December, 2020. The overall reduction in transplants during the observation time period translated to 48 239 waitlisted patient life-years lost. INTERPRETATION: We quantified the impact of the COVID-19 pandemic on worldwide organ transplantation activity and revealed heterogeneous adaptation in terms of organ transplantation, both at national levels and within countries, with detrimental consequences for waitlisted patients. Understanding how different countries and health-care systems responded to COVID-19-related challenges could facilitate improved pandemic preparedness, notably, how to safely maintain transplant programmes, both with immediate and non-immediate life-saving potential, to prevent loss of patient life-years. FUNDING: French national research agency (INSERM) ATIP Avenir and Fondation Bettencourt Schueller.


Asunto(s)
COVID-19/epidemiología , Salud Global/estadística & datos numéricos , Trasplante de Órganos/estadística & datos numéricos , Pandemias , Humanos
12.
Transplantation ; 103(10): 2150-2156, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-30720681

RESUMEN

BACKGROUND: Belatacept could be the treatment of choice in renal-transplant recipients with renal dysfunction attributed to calcineurin inhibitor (CNI) nephrotoxicity. Few studies have described its use in patients with donor-specific antibody (DSA). METHODS: We retrospectively evaluated conversion from CNIs to belatacept in 29 human leukocyte antigen-immunized renal-transplant recipients. Data about acute rejection, DSA, and renal function were collected. These patients were compared with 42 nonimmunized patients treated with belatacept. RESULTS: Patients were converted from CNIs to belatacept a median of 444 days (interquartile range, 85-1200) after transplantation and were followed up after belatacept conversion, for a median of 308 days (interquartile range, 125-511). At conversion, 16 patients had DSA. Nineteen DSA were observed in these 16 patients, of which 11/19 were <1000 mean fluorescence intensity (MFI), 7/19 were between 1000 and 3000 MFI, and one was >3000 MFI. At last follow-up, preexisting DSA had decreased or stabilized. Seven patients still had DSA with a mean MFI of 1298 ± 930 at the last follow-up. No patient developed a de novo DSA in the DSA-positive group. In the nonimmunized group, one patient developed de novo DSA (A24-MFI 970; biopsy for cause did not show biopsy-proven acute rejection or microinflammation score). After belatacept conversion, one antibody-mediated rejection was diagnosed. The mean estimated glomerular filtration rate improved from 31.7 ± 14.2 mL/min/1.73 m to 40.7 ± 12.3 mL/min/1.73 m (P < 0.0001) at 12 months after conversion. We did not find any significant difference between groups in terms of renal function, proteinuria, or biopsy-proven acute rejection. CONCLUSIONS: We report on a safe conversion to belatacept in human leukocyte antigen-immunized patients with low DSA levels.


Asunto(s)
Abatacept/administración & dosificación , Inhibidores de la Calcineurina/efectos adversos , Rechazo de Injerto/tratamiento farmacológico , Isoanticuerpos/sangre , Trasplante de Riñón/efectos adversos , Insuficiencia Renal/prevención & control , Adulto , Anciano , Aloinjertos/efectos de los fármacos , Aloinjertos/inmunología , Aloinjertos/patología , Biopsia , Inhibidores de la Calcineurina/administración & dosificación , Sustitución de Medicamentos , Femenino , Tasa de Filtración Glomerular/efectos de los fármacos , Tasa de Filtración Glomerular/inmunología , Rechazo de Injerto/sangre , Rechazo de Injerto/inmunología , Rechazo de Injerto/patología , Antígenos HLA/inmunología , Humanos , Isoanticuerpos/inmunología , Isoantígenos/inmunología , Riñón/efectos de los fármacos , Riñón/inmunología , Riñón/patología , Masculino , Persona de Mediana Edad , Insuficiencia Renal/inducido químicamente , Resultado del Tratamiento
13.
J. oral res. (Impresa) ; 10(1): 1-10, feb. 24, 2021. tab
Artículo en Inglés | LILACS | ID: biblio-1178770

RESUMEN

Fluoridation has been shown to be an effective measure against caries in children. The present study evaluates the cost-benefit of the fluoridated water program for the reduction of dental caries in 12-year-old children in the Biobío Region, the only region in Chile that has not implemented this program. An economic cost-benefit evaluation was carried out, comparing two alternative interventions: non-fluoridated drinking water versus fluoridated drinking water. The prevalence of caries, direct and indirect costs of the treatments, the cost of implementing the programs and the benefits of both interventions were estimated. From this study it is concluded that the savings in oral health costs in 12-year-old children when using fluoridating drinking water in the Biobío region is significantly higher than the cost involved in implementing the water fluoridation program, resulting in total savings for the Chilean state of $129,861,645 (USD$ 152,833) as well as an estimated reduction of 15% in the history of caries in the study population.


Se ha demostrado que la fluoración es una medida efectiva contra disminución de la caries en la población infantil. La presente investigación buscó evaluar cual es el costo-beneficio del programa del agua fluorada para la disminución de caries dental en niños de 12 años de la Región del Biobío, única región de Chile que no adhiere a este programa. Se realizó una evaluación económica de costo-beneficio, comparando dos intervenciones alternativas: agua potable no fluorada versus agua potable fluorada. Para tal fin se estimó la prevalencia de caries, costos directos e indirectos de los tratamientos, el costo de implementación de los programas y el beneficio de ambas intervenciones. De este estudio se concluye que el ahorro en costos de salud bucal en niños de 12 años al fluorar el agua potable en la región del Biobío, es significativamente mayor al costo que implica la implementación del programa de fluoración de aguas, lográndose un ahorro total para el Estado de $129.861.645 (USD $152.833) así como una estimación de reducción del 15% en la historia de caries en la población de estudio.


Asunto(s)
Humanos , Niño , Fluoruración , Caries Dental/prevención & control , Agua Potable/análisis , Chile , Prevalencia , Costos de la Atención en Salud , Fluoruros/análisis
14.
Int. j. morphol ; 39(3): 683-687, jun. 2021. ilus, tab
Artículo en Inglés | LILACS | ID: biblio-1385418

RESUMEN

SUMMARY: Peri-implantitis is an inflammatory lesion of bacterial etiology characterized by inflammation of the mucosa and bone loss. Chronic inflammation is characterized by neovascularization and collagen neoformation. Mast cells have been shown to participate in the inflammatory process by releasing mediators and proteases such as chymase and tryptase, important in the collagen neoformation process. Although a higher percentage of collagen has been described in periodontal disease, the literature is scarce about the percentage of collagen in peri-implantitis. The aim of this study was to quantify the percentage of collagen fibers present in the peri- implant soft tissue of patients with peri-implantitis lesions. A descriptive observational cross-sectional study was performed. Samples of peri-implant soft tissue were collected from eleven patients with peri-implantitis and then processed by Masson's Trichrome Technique. In microscopic analysis, collagen fibers were observed in all samples, with an average percentage of 39.89 %, standard deviation of 17.02 %, with a minimum value of 8.99 % and a maximum value of 75.65 % density. From these results, it can be concluded that in human peri-implantitis lesions with bone loss greater than 50 %, there is an important percentage of collagen fibers, which is interpreted as connective tissue in a permanent process of reparative response, in the presence of inflammatory infiltrate.


RESUMEN: La periimplantitis es una lesión inflamatoria de etiología bacteriana caracterizada por inflamación de la mucosa y pérdida ósea. La inflamación crónica se caracteriza por neovascularización y neoformación de colágeno. Se ha demostrado que los mastocitos participan en el proceso inflamatorio liberando mediadores y proteasas como quimasa y triptasa, importantes en el proceso de neoformación del colágeno. Aunque se ha descrito un mayor porcentaje de colágeno en la enfermedad periodontal, la literatura sobre el porcentaje de colágeno en la periimplantitis es escasa. El objetivo de este estudio fue cuantificar el porcentaje de fibras de colágeno presentes en el tejido blando periimplantario de pacientes con lesiones de periimplantitis. Se realizó un estudio observacional descriptivo transversal. Se recogieron muestras de tejido blando periimplantario de once pacientes con periimplantitis y luego se procesaron mediante la técnica tricrómica de Masson. En el análisis microscópico, se observaron fibras de colágeno en todas las muestras, con un porcentaje promedio de 39,89 %, desviación estándar de 17,02%, con un valor mínimo de 8,99 % y un valor máximo de 75,65% de densidad. De estos resultados se puede concluir que en las lesiones de periimplantitis humana con pérdida ósea superior al 50 %, existe un porcentaje importante de fibras de colágeno, que se interpreta como tejido conectivo en un proceso permanente de respuesta reparadora, en presencia de infiltrado inflamatorio.


Asunto(s)
Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Anciano , Colágeno/análisis , Tejido Conectivo/patología , Periimplantitis/patología , Inmunohistoquímica , Estudios Transversales , Inflamación
15.
Artículo en Inglés | MEDLINE | ID: mdl-24730934

RESUMEN

We study the deformation of drops squeezed between the floor and ceiling of a microchannel and subjected to a hyperbolic flow. We observe that the maximum deformation of drops depends on both the drop size and the rate of strain of the external flow and can be described with power laws with exponents 2.59±0.28 and 0.91±0.05, respectively. We develop a theoretical model to describe the deformation of squeezed drops based on the Darcy approximation for shallow geometries and the use of complex potentials. The model describes the steady-state deformation of the drops as a function of a nondimensional parameter Caδ2, where Ca is the capillary number (proportional to the strain rate and the drop size) and δ is a confinement parameter equal to the drop size divided by the channel height. For small deformations, the theoretical model predicts a linear relationship between the deformation of drops and this parameter, in good agreement with the experimental observations.

18.
Rev. chil. med. intensiv ; 20(4): 210-214, 2005. tab
Artículo en Español | LILACS | ID: lil-428624

RESUMEN

La cardiopatía coronaria es la primera causa de muerte en Chile y el infarto agudo del miocardio una de las patologías con garantías explícitas recientemente implementadas, exigiendo un diagnóstico precoz (30 minutos desde el momento de la consulta). Las troponinas e isoformas mb de la creatinfosfoquinasa son marcadores tardíos de daño miocárdico. La proteína ligadora de ácidos grasos de miocito (h-FABP), proteína citosólica del citoesqueleto miocárdico, es un marcador precoz de necrosis miocárdica detectándose ya a los 30 minutos de la injuria. Objetivo: Determinar la presencia temprana de h-FABP en síndrome coronario agudo (SCA) con supradesnivel del segmento ST (SDST) y su correlación tardía con diagnóstico infarto agudo del miocardio (IM). Materiales y métodos: Se reclutó a pacientes con SCA SDST con <6 horas de inicio de sus síntomas entre el 1/8/04 al 6/9/05 en el Servicio de Urgencias del Hospital del Salvador. Con registro de antecedentes personales, clínicos, electrocardiográficos, troponinas y/o CPK mb. Se correlacionó h-FABP (test rápido inmunoensayo de anticuerpos monoclonales, cualitativo (Cardiodetect®)) con diagnóstico confirmado de IM. Se analizaron sensibilidad, especificidad, valor predictivo positivo (VPP), negativo (VPN), cociente probabilidad positivo y negativo con programa estadístico PRIMER 4,06®. Resultados: 45 pacientes con SCA SDST. El 65,9 por ciento de género masculino. Rango de edades entre 38 y 82 con promedio de 63,4±16,4 años. Se registraron como factores de riesgo: tabaquismo 68,1 por ciento, hipertensión arterial 46,7 por ciento, dislipidemia 29,3 por ciento, cardiopatía coronaria 13,8 por ciento. Características electrocardiográficas: pared anterior 43,5 por ciento, inferior 36,7 por ciento, bloqueo completo de rama izquierda 19,8 por ciento. Se obtuvo una sensibilidad de 85,7 por ciento, especificidad: 60 por ciento, valor predictivo positivo: 80,2 por ciento y valor predictivo negativo: 54,7 por ciento. Cociente de probabilidad positiva 2,41 y cociente de probabilidad negativa 0,24 Taylor. Chi cuadrado por Mantel Haenszel p=0,0007. Conclusiones: La h-FABP es un marcador precoz, de fácil implementación y rápido resultado en el infarto agudo del miocardio, potencialmente útil para el diagnóstico en IM dada su alta sensibilidad y cociente de probabilidad.


Asunto(s)
Adulto , Humanos , Persona de Mediana Edad , Ácidos Grasos/sangre , Infarto del Miocardio/diagnóstico , Infarto del Miocardio/fisiopatología , Proteínas Portadoras/sangre , Creatina Quinasa , Biomarcadores , Sensibilidad y Especificidad
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