Falsas penumbras isquémicas en la TC de perfusión en pacientes con estenosis carotídea y cambios después de la angioplastia y stenting / False ischaemic penumbras in CT perfusion in patients with carotid artery stenosis and changes following angioplasty and stenting

INTRODUCCIÓN: La estenosis carotídea tiene una influencia en la TC de perfusión (TCP), que en ocasiones se manifiesta como una falsa penumbra isquémica (FPI). El objetivo de nuestro estudio es estimar la incidencia de FPI en pacientes con estenosis carotídea, establecer su relación con el grado de estenosis y medir los cambios cuantitativos y cualitativos de la TCP después de la angioplastia carotídea y stenting (ACS). MÉTODOS: Entre octubre del 2013 y junio del 2015 se seleccionó prospectivamente a 26 pacientes con estenosis carotídea que fueron sometidos a una ACS, realizándose un TCP 2-10 días antes y después de la ACS. RESULTADOS: Dieciséis pacientes tenían una estenosis unilateral (11 en el subgrupo de < 90% de estenosis y 5 en el de ≥ 90%) y 10 pacientes una estenosis bilateral. La incidencia de FPI en pacientes con estenosis carotídea es del 38,5%. El riesgo de FPI aumenta en relación directa con el grado de estenosis, con un riesgo relativo de 11 en el grupo de ≥ 90% respecto al grupo de < 90% (IC del 95%: 1,7-71,3; p = 0,0005). Existen cambios estadísticamente significativos en los parámetros CBF, TTP, MTT y Tmáx de la TCP que revierten tras la ACS. No hay cambios significativos en CBV. CONCLUSIONES: La estenosis carotídea implica cambios en los parámetros de la TCP, condicionando un alto riesgo de FPI en estenosis ≥ 90% y, por tanto, una posible interpretación equivocada de estos estudios. Estos cambios se revierten tras la ACS

INTRODUCTION: Carotid artery stenosis influences CT perfusion (CTP) studies, sometimes manifesting as a false ischaemic penumbra (FIP). This study aims to estimate the incidence of FIP in patients with carotid artery stenosis, establish their relationship with the degree of stenosis, and measure quantitative and qualitative changes in CTP after carotid angioplasty and stenting (CAS). METHODS: Between October 2013 and June 2015, we prospectively selected 26 patients with carotid stenosis who underwent CAS, with CTP being performed 2-10 days before and after CAS. RESULTS: Sixteen patients had unilateral stenosis (11 in the subgroup displaying < 90% stenosis and 5 in the subgroup with ≥ 90% stenosis) and 10 patients had bilateral stenosis. The incidence of FIP in patients with carotid artery stenosis was 38.5%. Risk of FIP increased in direct relation to degree of stenosis, with a relative risk of 11 in the subgroup with ≥ 90% stenosis with respect to the subgroup displaying < 90% stenosis (95% CI, 1.7-71.3; P=.0005). There were statistically significant changes in the parameters CBF, TTP, MTT, and Tmax CTP, which reverted after angioplasty. No significant changes were found in CBV. CONCLUSIONS: Carotid artery stenosis involves changes in CTP parameters. Patients with ≥ 90% stenosis carry a high risk of FIP; CTP studies may therefore be misinterpreted in these cases. Changes in CTP parameters are reverted after CAS

False ischaemic penumbras in CT perfusion in patients with carotid artery stenosis and changes following angioplasty and stenting. / Falsas penumbras isquémicas en la TC de perfusión en pacientes con estenosis carotídea y cambios después de la angioplastia y stenting.

INTRODUCTION: Carotid artery stenosis influences CT perfusion (CTP) studies, sometimes manifesting as a false ischaemic penumbra (FIP). This study aims to estimate the incidence of FIP in patients with carotid artery stenosis, establish their relationship with the degree of stenosis, and measure quantitative and qualitative changes in CTP after carotid angioplasty and stenting (CAS). METHODS: Between October 2013 and June 2015, we prospectively selected 26 patients with carotid stenosis who underwent CAS, with CTP being performed 2-10 days before and after CAS. RESULTS: Sixteen patients had unilateral stenosis (11 in the subgroup displaying < 90% stenosis and 5 in the subgroup with ≥ 90% stenosis) and 10 patients had bilateral stenosis. The incidence of FIP in patients with carotid artery stenosis was 38.5%. Risk of FIP increased in direct relation to degree of stenosis, with a relative risk of 11 in the subgroup with ≥ 90% stenosis with respect to the subgroup displaying < 90% stenosis (95% CI, 1.7-71.3; P=.0005). There were statistically significant changes in the parameters CBF, TTP, MTT, and Tmax CTP, which reverted after angioplasty. No significant changes were found in CBV. CONCLUSIONS: Carotid artery stenosis involves changes in CTP parameters. Patients with ≥ 90% stenosis carry a high risk of FIP; CTP studies may therefore be misinterpreted in these cases. Changes in CTP parameters are reverted after CAS.

Inflammation, edema and poor outcome are associated with hyperthermia in hypertensive intracerebral hemorrhages.

BACKGROUND AND PURPOSE: The deleterious effect of hyperthermia on intracerebral hemorrhage (ICH) has been studied. However, the results are not conclusive and new studies are needed to elucidate clinical factors that influence the poor outcome. The aim of this study was to identify the clinical factors (including ICH etiology) that influence the poor outcome associated with hyperthermia and ICH. We also tried to identify potential mechanisms involved in hyperthermia during ICH. METHODS: We conducted a retrospective study enrolling patients with non-traumatic ICH from a prospective registry. We used logistic regression models to analyze the influence of hyperthermia in relation to different inflammatory and endothelial dysfunction markers, hematoma growth and edema volume in hypertensive and non-hypertensive patients with ICH. RESULTS: We included 887 patients with ICH (433 hypertensive, 50 amyloid, 117 by anticoagulants and 287 with other causes). Patients with hypertensive ICH showed the highest body temperature (37.5 ± 0.8°C) as well as the maximum increase in temperature (0.9 ± 0.1°C) within the first 24 h. Patients with ICH of hypertensive etiologic origin, who presented hyperthermia, showed a 5.3-fold higher risk of a poor outcome at 3 months. We found a positive relationship (r = 0.717, P < 0.0001) between edema volume and hyperthermia during the first 24 h but only in patients with ICH of hypertensive etiologic origin. This relationship seems to be mediated by inflammatory markers. CONCLUSION: Our data suggest that hyperthermia, together with inflammation and edema, is associated with poor outcome only in ICH of hypertensive etiology.

The association between subclinical mastitis around calving and reproductive performance in grazing dairy cows.

The objective of this study was to evaluate the effect of subclinical mastitis (SCM) on calving-to-first-service interval (CFS), calving-to-conception interval (CC), and on the number of services per conception (S/C) in grazing Holstein and Normande cows. Primiparous (n=43) and multiparous (n=165) cows were selected from five dairy herds. Two composite milk samples were aseptically collected from each cow at drying-off, and then every week during the first postpartum month. One sample was used for somatic cell count (SCC), and the other one for bacteriological analysis. Cows were followed up to 300 d after calving. Non-parametric and parametric survival models, and negative binomial regression were used to assess the association between SCM, evaluated by SCC and milk culture, and reproductive indices. Staphylococcus aureus, CNS, and Streptococcus uberis were the most frequent isolated pathogens. Subclinical mastitis in the first month of lactation was not associated with CFS; however, the CC interval was longer in cows with SCM compared to healthy cows, the former also had a higher number of S/C.

Analog isolated electronic dynamometer based on a magnetoresistive current sensor.

In this work, an electronic system is presented to measure the force applied by a solenoid. The originality of the work is focused on the use of a magnetoresistive current sensor to provide the isolation barrier needed in the actual industrial plant where the solenoids are working. The design of the electronic system is presented as well as experimental measurements as a result of a calibration process showing a negligible hysteresis with that specific sensor. The magnetoresistive current sensor is used to develop transmission functions rather than playing its usual sensing roles.

Epidemiology and mortality of candidemia both related and unrelated to the central venous catheter: a retrospective cohort study.

Our objective was to compare mortality, epidemiology, and morbidity in hospitalized patients with candidemia which was both related and unrelated to the central venous catheter (CVC). This was a monocentric, retrospective cohort study of candidemia. The sample consisted of 103 patients with laboratory-confirmed nosocomial candidemia hospitalized between 2006 and 2013 in a tertiary care public hospital. We included 65 (63.1 %) patients (24 in the CVC-positive group, 41 in the CVC-negative group). Demographic data and risk factors were recorded using a structured case report form. In the group of candidemia associated to the CVC, survival at day 50 was 58.6 ± 11.9 %, compared to 26.5 ± 8.9 % for the CVC-negative group (p-value = 0.012); the hazard ratio of death was 0.38 (95 % confidence interval 0.17-0.85, p-value = 0.019). Compared with the CVC-positive patients, CVC-negative patients were often colonized with yeast (41.5 % vs. 16.7 %, p-value = 0.041), had a shorter previous in-hospital stay (20 days vs. 34 days, p-value = 0.023), and were more severely ill (severe sepsis 85.4 % vs. 58.3 %, p-value = 0.016). In this study, when the origin of candidemia was not the CVC, patients were more seriously ill, had a higher mortality rate, and the removal of the catheter seemed to lead to disappointing results. It would be useful to explore the impact of retention of the CVC on survival in the CVC-negative patients, where the CVCs are essential to treating these patients.

Chronic periodontitis is associated with lacunar infarct: a case-control study.

BACKGROUND AND PURPOSE: Chronic periodontitis (ChP) and lacunar infarct (LI) are two common diseases amongst the elderly. Although several studies have shown an association between ischaemic stroke and ChP, little is known about the relationship between ChP and LI. The study aims to investigate whether ChP is associated with the presence of lacunar stroke. METHODS: An age- and gender-matched case-control study of 62 cases (subjects diagnosed with LI) and 60 controls is reported. Clinical periodontal measures (probing pocket depth, recession, clinical attachment level, full mouth plaque score and full mouth gingival bleeding on probing score) were assessed, and associated risk factors for periodontitis and lacunar stroke were ascertained by means of a structured questionnaire. RESULTS: Chronic periodontitis showed a strong association with LI after adjusting for common vascular risk factors (odds ratio 4.20; 95% confidence interval 1.81-10.20; P = 0.001). Likewise, severe ChP and LI also tended to be significantly associated, independent of other vascular covariates (odds ratio 3.53; 95% confidence interval 1.07-12.77; P = 0.04). CONCLUSIONS: Chronic periodontitis was independently associated with the presence of LI after adjusting for well-known vascular risk factors for lacunar stroke. Further observational studies are necessary to investigate the pathophysiological mechanisms that can explain this relationship.

Efectividad de la administración oral versus intramuscular de vitamina B12 en pacientes con deficiencia: revisión sistemática / Efectiviness of the oral administration versus intramuscular of B12 vitamin in patients with deficiency: systematic review

La deficiencia de la vitamina B12 o cobalamina es una condición muy común y es una de las causas más importantes de la anemia. Puede ser tratada con un tratamiento oral o intramuscular. Se realizó una síntesis de la evidencia a través de una revisión sistemática de ensayos clínicos aleatorizados que hayan comparado ambos tratamientos para el manejo de estos pacientes. La estrategia de búsqueda incluyó ensayos clínicos aleatorizados (ECA); las bases de datos usadas fueron: Medline, Cochrane Central, Lilacs y Cinahl. Además se realizó una búsqueda electrónica en Google Scholar. Los resultados obtenidos fueron de tres artículos que cumplían con nuestros criterios de elegibilidad. El objetivo de esta revisión fue determinar si existe evidencia científica que avale la efectividad de la administración oral versus intramuscular de la vitamina B12 para el tratamiento de su deficiencia. Se concluyó que existe moderada evidencia que la administración de la vitamina B12 oral es más efectiva que la administración intramuscular a mediano plazo en el volumen sérico de cobalamina en pacientes con déficit de vitamina B12.

Vitamin B12 or cobalamin deficiency is a very common condition and is one of the most important causes of anemia. It can be treated with oral or intramuscular treatment. A summary of the evidence will be made through a systematic review of rando-mized clinical trials that have compared both treatments for the management of these patients. The objective of this review was to determine whether there is scientific evidence supporting the effectiveness of oral versus intramuscular vitamin B12 treatment ofits deficiency. The search strategy included randomized clinical trials (RCTs); databases used were: Medline, Cochrane Central, Lilacs and CINAHL. Also an electronic search in Google Scho-lar was performed. The results were three articles that met our eligibility criteria. We conclude that there is moderate evidence that the administration of oral vitamin B12 is most effective in the medium term increment serum cobalamin volume in patients with vitamin B12 deficiency.

Role of the Endobronchial Landmarks Guiding TBNA and EBUS-TBNA in Lung Cancer Staging.

Background. Lung cancer is the leading cause of malignancy related mortality in the United States. Accurate staging of NSCLC influences therapeutic decisions. Transbronchial needle aspiration (TBNA) and endobronchial ultrasound-guided TBNA (EBUS-TBNA) has been accepted as a procedure for the diagnosis and staging of lung cancer. The aim of this study is to evaluate the efficacy and adequacy of TBNA and EBUS-TBNA for sampling of mediastinal adenopathy using the Wang's eleven lymph node map stations. Methods. We retrospectively reviewed 99 consecutive cases diagnosed with malignancy by EBUS-TBNA and a series 74 patients evaluated for mediastinal adenopathy or a pulmonary lesion using conventional transbronchial needle aspiration. The IASLC lymph node map was correlated with Wang's map. Results. A total of 182 lymph node stations were sampled using EBUS-TBNA. 96 were positive for nodal metastasis. A total of four cases of samples taken from station 2R showed malignant cells. From the 74 cases series using cTBNA 167 nodes were sampled in 222 passes. Lymphoid or malignant tissue was obtained in 67 (91.8%) cases; 55.1% of the nodes were 1 cm or less. Conclusions. The use of the eleven stations described in Wang's map to guide TBNA of the mediastinal nodes allows sampling of radiologically considered nonpathological nodes. These data suggest that Wang's map covers the most frequent IASLC nodal stations compromised with metastasis.

Note: A non-invasive electronic measurement technique to measure the embedded four resistive elements in a Wheatstone bridge sensor.

The work shows a measurement technique to obtain the correct value of the four elements in a resistive Wheatstone bridge without the need to separate the physical connections existing between them. Two electronic solutions are presented, based on a source-and-measure unit and using discrete electronic components. The proposed technique brings the possibility to know the mismatching or the tolerance between the bridge resistive elements and then to pass or reject it in terms of its related common-mode rejection. Experimental results were taken in various Wheatstone resistive bridges (discrete and magnetoresistive integrated bridges) validating the proposed measurement technique specially when the bridge is micro-fabricated and there is no physical way to separate one resistive element from the others.

Factores predictivos del estado del ganglio centinela / Predictors of Sentinel Lymph Node Status

No disponible

Long- and short-term CDK5 knockdown prevents spatial memory dysfunction and tau pathology of triple transgenic Alzheimer's mice.

CDK5 is a member of the cyclin-dependent kinase family with diverse functions in both the developing and mature nervous system. The inappropriate activation of CDK5 due to the proteolytic release of the activator fragment p25 from the membrane contributes to the formation of neurofibrillary tangles and chronic neurodegeneration. At 18 months of age 3xTg-AD mice were sacrificed after 1 year (long term) or 3 weeks (short term) of CDK5 knockdown. In long-term animals CDK5 knockdown prevented insoluble Tau formation in the hippocampi and prevented spatial memory impairment. In short-term animals, CDK5 knockdown showed reduction of CDK5, reversed Tau aggregation, and improved spatial memory compared to scrambled treated old 3xTg-AD mice. Neither long-term nor short-term CDK5 knock-down had an effect on old littermates. These findings further validate CDK5 as a target for Alzheimer's disease both as a preventive measure and after the onset of symptoms.

Cyclin-dependent kinase 5, a node protein in diminished tauopathy: a systems biology approach.

Alzheimer's disease (AD) is the most common cause of dementia worldwide. One of the main pathological changes that occurs in AD is the intracellular accumulation of hyperphosphorylated Tau protein in neurons. Cyclin-dependent kinase 5 (CDK5) is one of the major kinases involved in Tau phosphorylation, directly phosphorylating various residues and simultaneously regulating various substrates such as kinases and phosphatases that influence Tau phosphorylation in a synergistic and antagonistic way. It remains unknown how the interaction between CDK5 and its substrates promotes Tau phosphorylation, and systemic approaches are needed that allow an analysis of all the proteins involved. In this review, the role of the CDK5 signaling pathway in Tau hyperphosphorylation is described, an in silico model of the CDK5 signaling pathway is presented. The relationship among these theoretical and computational models shows that the regulation of Tau phosphorylation by PP2A and glycogen synthase kinase 3ß (GSK3ß) is essential under basal conditions and also describes the leading role of CDK5 under excitotoxic conditions, where silencing of CDK5 can generate changes in these enzymes to reverse a pathological condition that simulates AD.

Guidelines for the prevention of ventilator-associated pneumonia and their implementation. The Spanish "Zero-VAP" bundle

"BACKGROUND: ""Zero-VAP"" is a proposal for the implementation of a simultaneous multimodal intervention in Spanish intensive care units (ICU) consisting of a bundle of ventilator-associated pneumonia (VAP) prevention measures. METHODS/DESIGN: An initiative of the Spanish Societies of Intensive Care Medicine and of Intensive Care Nurses, the project is supported by the Spanish Ministry of Health, and participation is voluntary. In addition to guidelines for VAP prevention, the ""Zero-VAP"" Project incorporates an integral patient safety program and continuous online validation of the application of the bundle. For the latter, VAP episodes and participation indices are entered into the web-based Spanish ICU Infection Surveillance Program ""ENVIN-HELICS"" database, which provides continuous information about local, regional and national VAP incidence rates. Implementation of the guidelines aims at the reduction of VAP to less than 9 episodes per 1000 days of mechanical ventilation. A total of 35 preventive measures were initially selected. A task force of experts used the Grading of Recommendations, Assessment, Development and Evaluation Working Group methodology to generate a list of 7 basic ""mandatory"" recommendations (education and training in airway management, strict hand hygiene for airway management, cuff pressure control, oral hygiene with chlorhexidine, semi-recumbent positioning, promoting measures that safely avoid or reduce time on ventilator, and discouraging scheduled changes of ventilator circuits, humidifiers and endotracheal tubes) and 3 additional ""highly recommended"" measures (selective decontamination of the digestive tract, aspiration of subglottic secretions, and a short course of iv antibiotic). DISCUSSION: We present the Spanish VAP prevention guidelines and describe the methodology used for the selection and implementation of the recommendations and the organizational structure of the project. Compared to conventional guideline documents, the associated safety assurance program, the online data recording and compliance control systems, as well as the existence of a pre-defined objective are the distinct features of ""Zero VAP"""

Guidelines for the prevention of ventilator-associated pneumonia and their implementation. The Spanish ‘‘Zero-VAP’’ bundle

BACKGROUND: ''Zero-VAP'' is a proposal for the implementation of a simultaneous multimodal intervention in Spanish intensive care units (ICU) consisting of a bundle of ventilator-associated pneumonia (VAP) prevention measures. Methods/DESIGN: An initiative of the Spanish Societies of Intensive Care Medicine and of Intensive Care Nurses, the project is supported by the Spanish Ministry of Health, and participation is voluntary. In addition to guidelines for VAP prevention, the ''Zero-VAP'' Project incorporates an integral patient safety program and continuous online validation of the application of the bundle. For the latter, VAP episodes and participation indices are entered into the web-based Spanish ICU Infection Surveillance Program ''ENVIN-HELICS'' database, which provides continuous information about local, regional and national VAP incidence rates. Implementation of the guidelines aims at the reduction of VAP to less than 9 episodes per 1000 days of mechanical ventilation. A total of 35 preventive measures were initially selected. A task force of experts used the Grading of Recommendations, Assessment, Development and Evaluation Working Group methodology to generate a list of 7 basic "mandatory" recommendations (education and training in airway management, strict hand hygiene for airway management, cuff pressure control, oral hygiene with chlorhexidine, semi-recumbent positioning, promoting measures that safely avoid or reduce time on ventilator, and discouraging scheduled changes of ventilator circuits, humidifiers and endotracheal tubes) and 3 additional "highly recommended" measures (selective decontamination of the digestive tract, aspiration of subglottic secretions, and a short course of IV antibiotic). Discussion: We present the Spanish VAP prevention guidelines and describe the methodology used for the selection and implementation of the recommendations and the organizational structure of the project. Compared to conventional guideline documents, the associated safety assurance program, the online data recording and compliance control systems, as well as the existence of a pre-defined objective are the distinct features of "Zero VAP"

ANTECEDENTES: «Neumonía Zero» es una propuesta de aplicación de una intervención multimodal simultánea en las unidades de cuidados intensivos españolas que consiste en un paquete de medidas preventivas de la neumonía asociada a la ventilación mecánica (NAVM).Métodos/DISEÑO: Se trata de una iniciativa de las sociedades españolas de Medicina Intensiva y Enfermería Intensiva. El proyecto cuenta con el apoyo del Ministerio de Sanidad y la participación es voluntaria. Además de las directrices para la prevención de la NAVM, el proyecto« Neumonía Zero» incluye un programa integral de seguridad del paciente y una validación continua« online» de la aplicación de las medidas. Para ello se introducen los episodios de NAVM y los índices de participación en la base de datos en red del programa« ENVIN-HELICS» de vigilancia de las infecciones en las unidades de cuidados intensivos españolas, que ofrece información continua acerca de las tasas de incidencia de NAVM a nivel local, autonómico y nacional. La aplicación de «Neumonía Zero»preten de reducir las NAVM a menos de 9 episodios por cada 1.000 días de ventilación mecánica. Inicialmente, se seleccionaron 35 medidas de prevención. Un grupo de expertos utilizó la metodología del Grading of Recommendations, Assessment, Developmentand Evaluation Working Group para crear una lista de 7 recomendaciones básicas «obligatorias»(formación y entrenamiento en el manejo de la vía aérea, higiene estricta de manos en el manejo de la vía aérea, control de la presión del neumotaponamiento, higiene bucal con clorhexidina, posición semiincorporada, fomento de medidas que de forma segura eviten o reduzcan la duración de la ventilación mecánica, y desaconsejar los cambios programados de tubuladuras, humidificadores y tubos endotraqueales) y 3 medidas adicionales «muy recomendables» (descontaminación selectiva del tubo digestivo, aspiración de las secreciones subglóticas y un breve curso de antibióticos intravenosos). Debate: Presentamos las directrices españolas para la prevención de la NAVM y describimos la metodología utilizada para seleccionar y aplicar las recomendaciones y la estructura organizativa del proyecto. En comparación con recomendaciones convencionales, el programa de seguridad asociado, el registro de datos «online» y los sistemas de control del cumplimiento, además de la existencia de un objetivo predefinido, son características distintivas de «Neumonía Zero»

Guidelines for the prevention of ventilator-associated pneumonia and their implementation. The Spanish "Zero-VAP" bundle.

BACKGROUND: "Zero-VAP" is a proposal for the implementation of a simultaneous multimodal intervention in Spanish intensive care units (ICU) consisting of a bundle of ventilator-associated pneumonia (VAP) prevention measures. METHODS/DESIGN: An initiative of the Spanish Societies of Intensive Care Medicine and of Intensive Care Nurses, the project is supported by the Spanish Ministry of Health, and participation is voluntary. In addition to guidelines for VAP prevention, the "Zero-VAP" Project incorporates an integral patient safety program and continuous online validation of the application of the bundle. For the latter, VAP episodes and participation indices are entered into the web-based Spanish ICU Infection Surveillance Program "ENVIN-HELICS" database, which provides continuous information about local, regional and national VAP incidence rates. Implementation of the guidelines aims at the reduction of VAP to less than 9 episodes per 1000 days of mechanical ventilation. A total of 35 preventive measures were initially selected. A task force of experts used the Grading of Recommendations, Assessment, Development and Evaluation Working Group methodology to generate a list of 7 basic "mandatory" recommendations (education and training in airway management, strict hand hygiene for airway management, cuff pressure control, oral hygiene with chlorhexidine, semi-recumbent positioning, promoting measures that safely avoid or reduce time on ventilator, and discouraging scheduled changes of ventilator circuits, humidifiers and endotracheal tubes) and 3 additional "highly recommended" measures (selective decontamination of the digestive tract, aspiration of subglottic secretions, and a short course of iv antibiotic). DISCUSSION: We present the Spanish VAP prevention guidelines and describe the methodology used for the selection and implementation of the recommendations and the organizational structure of the project. Compared to conventional guideline documents, the associated safety assurance program, the online data recording and compliance control systems, as well as the existence of a pre-defined objective are the distinct features of "Zero VAP".

El folículo piloso: una importante fuente celular en ingeniería tisular / Hair follicle: an important cellular source in tissue engineering

El folículo piloso-sebáceo o unidad folículo-sebácea-apócrina es un órgano microscópico complejo funcional y estructuralmente. Consta de un segmento superior, estable y un segmento inferior, que se regenera en cada ciclo piloso. El folículo piloso contiene una gran diversidad de tipos celulares, entre los que se encuentran células madre. De hecho, supone el nicho más importante de células madre en la piel, con la ventaja añadida de su fácil accesibilidad. Estas células madre se localizan en una prominencia a nivel de la inserción del músculo erector del pelo, llamada "bulge" (promontorio). Son las encargadas de regenerar el folículo en cada ciclo y también intervienen en la reconstitución de las glándulas sebáceas y de la epidermis interfolicular, en caso de lesión epidérmica. El conocimiento de la estructura del folículo piloso, está haciendo posible cada vez más el empleo de los distintos tipos celulares, especialmente, las células madre, en la ingeniería tisular de la piel. Asimismo, estudios recientes han diferenciado las células madres foliculares a diferentes estirpes, como por ejemplo: células nerviosas, hematopoyéticas y vasculares. Además, se ha estudiado la construcción de folículos pilosos, con resultados satisfactorios en ratones, aunque no del todo superponibles a humanos, en los que se precisan más investigaciones. La posibilidad de generar folículos pilosos humanos, supondría una revolución en el amplio campo de las alopecias. El objetivo de esta revisión es describir la estructura anatómica e histológica del folículo piloso, enfatizando en la importancia del mismo como nicho de células madre y su potencial utilidad en el campo de la ingeniería tisular, para la construcción de diversos tipos de tejidos.

The hair follicle is a microscopic organ, functionally and structurally complex. It can be divided into two distinct segments, the upper portion, stable and the lower portion, that undergoes regeneration every hair cycle. The hair follicle contains a variety of cells types, including stem cells. It fact, it is the most important niche of stem cells in the skin, with the added advantage of its easy accessibility. These stem cells are located in a prominence at the level of the insertion of the arrector pili muscle, called bulge. They are responsible of hair follicle regeneration each hair cycle, and also can form sebaceous glands and help in repopulation of the interfollicular epidermis after injury. The knowledge of hair follicle structure is making possible the use of different types of cells, especially stem cells, in skin tissue engineering. Furthermore, recent studies have differentiated follicle stem cells into different strains, for example: nervous, hematopoietic and vascular cells. Moreover, other late studies have focused on the hair follicle construction, with satisfactory results in mice, but not completely transferable to humans, which further research is needed. The possibility of human hair follicle regeneration would suppose a revolution in the broad world of alopecia. The aim of this review is to describe the anatomical and histological structure of the hair follicle, emphasizing the importance as stem cell niche, and its potential usefulness in the field of tissue engineering for the construction of various types of tissues.

El folículo piloso: una importante fuente celular en ingeniería tisular / Hair follicle: an important cellular source in tissue engineering

El folículo piloso-sebáceo o unidad folículo-sebácea-apócrina es un órgano microscópico complejo funcional y estructuralmente. Consta de un segmento superior, estable y un segmento inferior, que se regenera en cada ciclo piloso. El folículo piloso contiene una gran diversidad de tipos celulares, entre los que se encuentran células madre. De hecho, supone el nicho más importante de células madre en la piel, con la ventaja añadida de su fácil accesibilidad. Estas células madre se localizan en una prominencia a nivel de la inserción del músculo erector del pelo, llamada "bulge" (promontorio). Son las encargadas de regenerar el folículo en cada ciclo y también intervienen en la reconstitución de las glándulas sebáceas y de la epidermis interfolicular, en caso de lesión epidérmica. El conocimiento de la estructura del folículo piloso, está haciendo posible cada vez más el empleo de los distintos tipos celulares, especialmente, las células madre, en la ingeniería tisular de la piel. Asimismo, estudios recientes han diferenciado las células madres foliculares a diferentes estirpes, como por ejemplo: células nerviosas, hematopoyéticas y vasculares. Además, se ha estudiado la construcción de folículos pilosos, con resultados satisfactorios en ratones, aunque no del todo superponibles a humanos, en los que se precisan más investigaciones. La posibilidad de generar folículos pilosos humanos, supondría una revolución en el amplio campo de las alopecias. El objetivo de esta revisión es describir la estructura anatómica e histológica del folículo piloso, enfatizando en la importancia del mismo como nicho de células madre y su potencial utilidad en el campo de la ingeniería tisular, para la construcción de diversos tipos de tejidos.(AU)

The hair follicle is a microscopic organ, functionally and structurally complex. It can be divided into two distinct segments, the upper portion, stable and the lower portion, that undergoes regeneration every hair cycle. The hair follicle contains a variety of cells types, including stem cells. It fact, it is the most important niche of stem cells in the skin, with the added advantage of its easy accessibility. These stem cells are located in a prominence at the level of the insertion of the arrector pili muscle, called bulge. They are responsible of hair follicle regeneration each hair cycle, and also can form sebaceous glands and help in repopulation of the interfollicular epidermis after injury. The knowledge of hair follicle structure is making possible the use of different types of cells, especially stem cells, in skin tissue engineering. Furthermore, recent studies have differentiated follicle stem cells into different strains, for example: nervous, hematopoietic and vascular cells. Moreover, other late studies have focused on the hair follicle construction, with satisfactory results in mice, but not completely transferable to humans, which further research is needed. The possibility of human hair follicle regeneration would suppose a revolution in the broad world of alopecia. The aim of this review is to describe the anatomical and histological structure of the hair follicle, emphasizing the importance as stem cell niche, and its potential usefulness in the field of tissue engineering for the construction of various types of tissues.(AU)

Assessment of Three Alternating Pressure Sequences Applied to a Dynamic Cushion to Relieve Pressure on Seating Areas / Evaluación de tres secuencias de inflado alternantes aplicadas a un cojín dinámico para la liberación de presión en el área de sentado

Pressure ulcers are injuries to the skin and/or underlying tissues caused by prolonged high pressures on supporting body areas, they affect mainly people with poor mobility that have stayed in seating position for a long time. Reducing the amount and duration of pressure has been widely accepted for minimizing the risk of formation of pressure ulcers. Recently, dynamic cushions have been developed to relieve pressure on supporting areas; nevertheless, there is no sufficient information about the adequate characteristics of alternating sequences for pressure ulcers prevention. Therefore, the aim of this work is to explore three sequences of alternating movements designed for an air cell cushion by comparing pressure redistribution on supporting areas when applied on healthy volunteers. The purpose of these sequences is to redistribute the pressure over a larger contact area. To evaluate the effect of the alternating sequences, eight healthy volunteers were asked to sit on the air cell cushion, and to try the three alternating sequences for 12 minutes, 2 minutes on static mode and 10 minutes on alternating mode. A parameter for quantitative assessment of alternating sequences was proposed in this work by determining the coefficient of variation of interface pressure. Furthermore, the percentage of relative change of coefficient of variation was computed for evaluating performance of the alternating sequences comparing to the static mode. It was found that the three proposed strategies maintained values of interface pressure lower than previous work. Additionally, the relative change allowed to differentiate the effects of alternation of each sequence showing the second strategy as the most effective. The results are encouraging for further studies in subjects who require a wheelchair for mobility.

Las úlceras por presión son lesiones en la piel y tejidos subyacentes, causadas por presiones excesivas y prolongadas en las superficies de apoyo del cuerpo. Estas lesiones afectan principalmente a personas con poca movilidad física, como aquellas que permanecen sentados por largos periodos. Para disminuir el riesgo del padecimiento de estas lesiones, se ha recomendado como punto de partida reducir la magnitud y el tiempo de acción de las presiones en las zonas de apoyo. Se han desarrollado cojines dinámicos para sillas de ruedas, los cuales generan movimientos alternantes en las diferentes zonas de apoyo, producido por la inyección de aire, con el fin de disminuir las presiones en esas zonas. Sin embargo, no se han encontrado referencias de las características adecuadas de las secuencias de movimientos alternantes para prevenir la aparición de esas lesiones. El propósito de este trabajo es evaluar tres secuencias de movimientos alternantes diseñadas para un cojín de aire. La evaluación se realizó comparando la distribución de presiones en zonas de apoyo antes y durante la aplicación de estas secuencias alternantes en personas sanas. Las secuencias propuestas se aplican para el inflado y desinflado de celdas que forman el cojín y fueron diseñadas con el objetivo de distribuir las presiones en un área mayor de apoyo. La prueba se realizó en 8 sujetos sanos, con un tiempo de estudio de 12 minutos para cada secuencia diseñada; 2 minutos en modo estático y 10 minutos en modo alternante. Se propuso determinar el coeficiente de variación para evaluar de forma cuantitativa el efecto de las secuencias alternantes sobre la presión de interfaz. Además se calculó el porcentaje de variación relativa del coeficiente de variabilidad entre los modos basal (estático) y alternante como una herramienta para evaluar el desempeño de las secuencias propuestas en relación a la presión de interfaz. Se encontró que las tres estrategias mantuvieron presiones de interfaz por debajo de los valores reportados en trabajos previos. El porcentaje de variación relativa permitió diferenciar el efecto de la alternancia de cada una de las secuencias propuestas, mostrando la segunda estrategia como la más efectiva. Los resultados obtenidos son alentadores para continuar el estudio en sujetos que requieren una silla de ruedas para su movilidad.