Simultaneous monitoring of Staphylococcus aureus growth in a multi-parametric microfluidic platform using microscopy and impedance spectroscopy.

We describe the design, construction, and characterization of a scalable microfluidic platform that allows continuous monitoring of biofilm proliferation under shear stress conditions. Compared to other previous end-point assay studies, our platform offers the advantages of integration into multiple environments allowing simultaneous optical microscopy and impedance spectroscopy measurements. In this work we report a multi-parametric sensor that can monitor the growth and activity of a biofilm. This was possible by combining two interdigitated microelectrodes (IDuEs), and punctual electrodes to measure dissolved oxygen, K+, Na+ and pH. The IDuE has been optimized to permit sensitive and reliable impedance monitoring of Staphylococcus aureus V329 growth with two- and four-electrode measurements. We distinguished structural and morphological changes on intact cellular specimens using four-electrode data modeling. We also detected antibiotic mediated effects using impedance. Results were confirmed by scanning electrode microscopy and fluorescence microscopy after live/dead cell staining. The bacitracin mediated effects detected with impedance prove that the approach described can be used for guiding the development of novel anti-biofilm agents to better address bacterial infection.

Flexible probe for in vivo quantification of corneal epithelium permeability through non-invasive tetrapolar impedance measurements.

Studies concerning the functional status of the corneal epithelium are of special interest due to its key role in preventing ocular surface disease and corneal infections. In particular, quantitative measurements of the epithelium permeability translayer electrical resistance (TER) have been proven as a sensitive in vitro test for evaluation of the corneal barrier function. In a recent work from the authors (Guimera et al. Biosens. Bioelectron. 31:55-61, 2012), a novel method to non-invasively assess the corneal epithelial permeability by using tetrapolar impedance measurements, based on the same TER theoretical principles, was presented and validated using a rigid sensing device. In this work, the usability of this method has been dramatically improved by using SU-8 photoresist as a substrate material. The flexibility of this novel sensing device makes no need to apply pressure on the cornea to ensure the electrical contact between the electrodes and the corneal surface. The feasibility of this flexible sensor has been evaluated in vivo by increasing the permeability of rabbit corneal epithelium. For that, different concentrations of benzalkonium chloride (BAC) solution were instilled on different rabbit corneas. The obtained results have been compared with measurements of the permeability to sodium fluorescein of different excised corneas, a well-known method used to evaluate the corneal barrier function, to demonstrate the feasibility of this novel flexible sensor for quantifying the corneal epithelium permeability in vivo in a non-invasive way.

A non-invasive method for an in vivo assessment of corneal epithelium permeability through tetrapolar impedance measurements.

The permeability of the cornea epithelial layer has an important role in optimal function of the cornea. To assess this property quantitatively, methods must be based on the passive electrical properties of living tissues, as they can take advantage of the fundamental role that ionic permeability plays in such properties. For such techniques, measurement of the translayer electrical resistance (TER) has been consistently used to examine the ion transport mechanisms in the corneal epithelial cells; however, this technique has been only possible in vitro. To enhance the applications of this method, in this work we present a novel sensor to perform non-invasive in vivo TER measurements. Herein, the epithelial permeability was assessed using non-invasive tetrapolar impedance measurements that were performed with four electrodes placed on the corneal surface. The geometry of these electrodes was previously optimized to maximize the sensitivity of the corneal epithelium. To evaluate the feasibility of this sensor, the permeability of a rabbit corneal epithelium was monitored by applying a solution of benzalkonium chloride (0.05% BAC). The results validate the capability of the sensor to evaluate the cornea epithelial permeability in vivo.

Non-invasive assessment of corneal endothelial permeability by means of electrical impedance measurements.

The permeability of the corneal endothelial layer has an important role in the correct function of the cornea. Since ionic permeability has a fundamental impact on the passive electrical properties of living tissues, here it is hypothesized that impedance methods can be employed for assessing the permeability of the endothelial layer in a minimally invasive fashion. Precisely, the main objective of the present study is to develop and to analyze a minimally invasive method for assessing the electrical properties of the corneal endothelium, as a possible diagnostic tool for the evaluation of patients with endothelial dysfunction. A bidimensional model consisting of the main corneal layers and a four-electrode impedance measurement setup placed on the epithelium has been implemented and analyzed by means of the finite elements method (FEM). In order to obtain a robust indicator of the permeability of the endothelium layer, the effect of the endothelium electrical properties on the measured impedance has been studied together with reasonable variations of the other model layers. Simulation results show that the impedance measurements by means of external electrodes are indeed sufficiently sensitive to the changes in the electrical properties of the endothelial layer. It is concluded that the method presented here can be employed as non-invasive method for assessing endothelial layer function.

Method and device for bio-impedance measurement with hard-tissue applications.

Bio-impedance measurements can be used to detect and monitor several properties of living hard-tissues, some of which include bone mineral density, bone fracture healing or dental caries detection. In this paper a simple method and hardware architecture for hard tissue bio-impedance measurement is proposed. The key design aspects of such architecture are discussed and a commercial handheld ac impedance device is presented that is fully certified to international medical standards. It includes a 4-channel multiplexer and is capable of measuring impedances from 10 kOmega to 10 MOmega across a frequency range of 100 Hz to 100 kHz with a maximum error of 5%. The device incorporates several user interface methods and a Bluetooth link for bi-directional wireless data transfer. Low-power design techniques have been implemented, ensuring the device exceeds 8 h of continuous use. Finally, bench test results using dummy cells consisting of parallel connected resistors and capacitors, from 10 kOmega to 10 MOmega and from 20 pF to 100 pF, are discussed.

Varón de 85 años con esputo hemoptoico / No disponible

La hemoptisis es un motivo de consulta frecuente en Atención Primaria y su causa más común es la infecciosa. Habitualmente las bronquitis dan lugar a hemoptisis leve y las bronquiectasias a hemoptisis moderada o grave. En el mundo occidental, las neoplasias son también causa frecuente de hemoptisis moderadas, leves o de repetición. Ante todo episodio de hemoptisis es fundamental tranquilizar al paciente y los familiares, mantener la vía aérea permeable y valorar la situación clínica y la cuantía de la pérdida, ya que de ello dependerá su inmediata derivación o manejo en Atención Primaria. En general, las hemoptisis leves podrán ser controladas y estudiadas ambulatoriamente para conocer su origen

Hemoptysis is a frequent reason for a visit to Primary Health Care. Its most common cause is an infectious one. Usually, bronchitis gives rise to mild hemoptysis and bronchiectasis to moderate or severe hemoptysis. In the Western world, neoplasms are also a frequent cause of moderate, mild or repetition of hemoptysis. When there is an episode of hemoptysis, it is essential to reassure the patient and family members, maintain the airway patent and evaluate the clinical condition and amount of loss since this will indicate the patient’s immediate referral or management in Primary Care. In general, mild hemoptysis can be controlled and studied in an out-patient setting to know its origin

[Comorbidity, hospitalization, and drug use for non-exacerbated chronic disease in the elderly population]. / Comorbilidad, ingreso hospitalario y consumo de fármacos por enfermedad crónica no reagudizada en población anciana.

OBJECTIVES: To evaluate the prevalence of comorbidity among elderly hospitalized patients and its influence on discharge diagnosis and medication due to non-exacerbated chronic disease (NECD). To evaluate the impact of hospital admission on the use of drugs due to NECD since admission to the month of discharge. METHODS: A study was made of 85 patients aged 65 years or older collected during two consecutive months. The study protocol consisted of a questionnaire on comorbidity, study of drug consume, discharge diagnosis and follow-up for one month post discharge. RESULTS: Patients had a mean of 6.4 chronic diseases; significant differences were observed regarding discharge report (mean: 2.1). The number of drugs due to NECD prior to admission (mean: 2.9), at discharge (1.5) and one month after discharge (1.9) showed significant differences between those prior to admission, at discharge, and one month after discharge (p < 0.0001). Hospital admission involved a decrease (p < 0.0001) in the number of patients with polypharmacy criteria (more than four drugs), which persisted one month after discharge (p < 0.01), and in the prescription of polyvitaminic compounds, nonsteroid antiinflammatory drugs, antiaggregants, peripheral vasodilators and antacids (p < 0.03). CONCLUSIONS: A relevant under-reporting of chronic diseases in the discharge report, particularly of those without exacerbations, as well as quantitative (decrease) and qualitative changes in the prescription due to NECD, maintained by the general practitioner one month after discharge. A higher awareness regarding chronic disease is necessary, as well as chronic disease is necessary, as well as establishing communication channels between Primary and Specialized Care.