Short Axis In-Plane Ultrasound-Guided Technique for Internal Jugular Vein Cannulation.

BACKGROUND: Real-time ultrasound (US)-guided venipuncture has become the standard of care due to its reduced complications and higher success rate. There are various techniques for US-guided cannulation of the internal jugular vein (IJV); the transversal and longitudinal views are the most widely used. There is a less commonly used technique that combines the benefits of both methods. DISCUSSION: Two main techniques for central line US-guided cannulation of the IJV are based on the location of the probe relative to the vessel and are known as the transversal view and the longitudinal view. The transversal view may make it difficult to identify the tip of the needle as it enters the vein, and the longitudinal view may not allow for visualization of surrounding structures. A third and less commonly used technique, the short axis in-plan view, aims to combine the benefits of both previous methods. In this technique, the entire needle can be tracked in real time as it enters the IJV, while also providing visualization of surrounding structures. CONCLUSIONS: The short axis in-plane view technique for central venous line placements allows for real-time US-guided needle venipuncture with simultaneous visualization of surrounding structures.

Cerebral circulatory arrest diagnosed with transoral Doppler ultrasonography.

We describe the case of a patient with malignant stroke in whom brain death was diagnosed by evaluating the neck vessels by transoral ultrasonography.

Effects of nanoscale dispersion in the dielectric properties of poly(vinyl alcohol)-bentonite nanocomposites.

We investigate the effects of clay proportion and nanoscale dispersion in the dielectric response of poly(vinyl alcohol)-bentonite nanocomposites. The dielectric study was performed using the thermally stimulated depolarization current technique, covering the temperature range of the secondary and high-temperature relaxation processes. Important changes in the secondary relaxations are observed at low clay contents in comparison with neat poly(vinyl alcohol) (PVA). The high-temperature processes show a complex peak, which is a combination of the glass-rubber transition and the space-charge relaxations. The analysis of these processes shows the existence of two segmental relaxations for the nanocomposites. Dielectric results were complemented by calorimetric experiments using differential scanning calorimetry. Morphologic characterization was performed by x-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM and XRD results show a mixture of intercalated and exfoliated clay dispersion in a trend that promotes the exfoliated phase as the bentonite content diminishes. Dielectric and morphological results indicate the existence of polymer-clay interactions through the formation of hydrogen bounds and promoted by the exfoliated dispersion of the clay. These interactions affect not only the segmental dynamics, but also the secondary local dynamics of PVA.

In vitro deposition of hydroxyapatite on cortical bone collagen stimulated by deformation-induced piezoelectricity.

In the present work, we have studied the effect of the piezoelectricity of elastically deformed cortical bone collagen on surface using a biomimetic approach. The mineralization process induced as a consequence of the piezoelectricity effect was evaluated using scanning electron microscopy (SEM), thermally stimulated depolarization current (TSDC), and differential scanning calorimetry (DSC). SEM micrographs showed that mineralization occurred predominantly over the compressed side of bone collagen, due to the effect of piezoelectricity, when the sample was immersed in the simulated body fluid (SBF) in a cell-free system. The TSDC method was used to examine the complex collagen dielectric response. The dielectric spectra of deformed and undeformed collagen samples with different hydration levels were compared and correlated with the mineralization process followed by SEM. The dielectric measurements showed that the mineralization induced significant changes in the dielectric spectra of the deformed sample. DSC and TSDC results demonstrated a reduction of the collagen glass transition as the mineralization process advanced. The combined use of SEM, TSDC, and DSC showed that, even without osteoblasts present, the piezoelectric dipoles produced by deformed collagen can produce the precipitation of hydroxyapatite by electrochemical means, without a catalytic converter as occurs in classical biomimetic deposition.

[Study of the hydrolytic degradation of a biodegradable copolymer]. / Estudio de la degradación hidrolítica de un copolímero biodegradable.

The hydrolytic degradation of bioabsorbable Poliglactin 910 was studied in a phosphate buffer solution, pH = 7.4, at 37 degrees C. The degradation was evaluated by analyzing the changes in weight loss, pH, DSC, mechanical properties and morphological changes. After 10 weeks, the weight loss and pH changes suggested diffusion of low molecular weight chain segments into the reaction medium as a consequence of the breaking of ester bonds in the material. Breaking stress and Young Modulus decrease, indicating that chain scission proceeded in two steps: the first occurring in the amorphous regions within the intermicrofibrillar space; the second in the crystalline regions. Surface morphological changes suggest a heterogeneous degradation mechanism by layers.

Estudio de la degradación hidrolítica de un copolímero biodegradale / Study of the hydrolytic degradation of a biodegradable copolymer

Se estudió la degradación hidrolítica in vitro de suturas de Poliglactin 910 utilizando un buffer de fosfato , pH= 7,4, a 37 °C. La degradación fue evaluada a través de la perdida en peso, cambio en las propiedades térmicas, morfología y propiedades mecánicas de las suturas sometidas a hidrólisis. Después de 10 semanas, los resultados obtenidos de la pérdida en peso y pH sugieren la difusión de especies de bajo peso molecular al medio de reacción como consecuencia del ataque hidrolítico a los grupos éster en el polímero. La disminución de las propiedades mecánicas, tanto el esfuerzo de ruptura como el modulo, junto con los resultados anteriores sugieren que el proceso de escisión de cadenas procede en dos etapas: la primera ocurre en las zonas amorfas y la segunda en las zonas cristalinas. El estudio de la morfología correspondiente a la superf icie de las sutura revela un mecanismo de degradación heterogéneo por capas.

The hydrolytic degradation of bioabsorbable Poliglactin 910 was studied in a phosphate buffer solution, pH= 7,4, at 37 °C. The degradation was evaluated by analyzing the changes in weight loss, pH, DSC, mechanical properties and morphological changes. After 10 weeks, the weight loss and pH changes suggested diffusion of low molecular weight chain segments into the reaction medium as a consequence of the breaking of ester bonds in the material. Breaking stress and Young Modulus decrease, indicating that chain scission proceeded in two steps: the first ocurring in the amorphous regions within the intermicrofibrillar space; the second in the crystalline regions. Surface morphological changes suggest a heterogeneous degradation mechanism by layers.

Hallazgos audiológicos en la población de postulantes a soldados voluntarios / Auditory findings in a population of postulants to voluntary soldiers

Para el ingrso como Soldado Voluntario en el Ejército Argentino es un requisito obligatorio el examen otoscópico y la audiometría. utilizamos los estudios realizados por el ingreso como base para elaborar el presente trabajo. ...En este trabajo se intenta presentar una muestra de la otoscopía y audiometría de los jóvenes argentinos de fines del milenio

Hallazgos audiológicos en la población de postulantes a soldados voluntarios / Auditory findings in a population of postulants to voluntary soldiers

Para el ingrso como Soldado Voluntario en el Ejército Argentino es un requisito obligatorio el examen otoscópico y la audiometría. utilizamos los estudios realizados por el ingreso como base para elaborar el presente trabajo. ...En este trabajo se intenta presentar una muestra de la otoscopía y audiometría de los jóvenes argentinos de fines del milenio

Análisis factorial de un cuestionario de hábitos de sueño / Factorial analysis of a questionnaire on sleeping habits

Los cuestionarios sobre el sueño son instrumentos que han mostrado ser de utilidad para estudiar el sueño y sus alteraciones, si bien su utilidad aún no ha sido suficientemente definida. En este trabajo se presenta el análisis factorial de un cuestionario sobre el sueño, aplicado a 602 pacientes de preconsulta del Hospital General "Dr. Manuel Gea González", de la Ciudad de México, D. F. El estudio descriptivo de este cuestionario ya se publicó. El análisis factorial que se describe permitió obtener 16 factores y no produjo una estructura clara. Los 16 factores representan el 58 por ciento de la varianza; los dos factores más importantes se relacionan con la experiencia global del sueño y con la calidad del sueño, de lo que se deduce que estos factores son los dos aspectos subjetivos más importantes del fenómeno. Se concluye que la evaluación de estos dos factores permitirá hacer consideraciones confiables acerca del sueño, sin necesidad de recurrir al cuestionario extenso. Estos resultados concuerdan con los de los estudios anteriores, pero se necesita analizar otras poblaciones para poder comparar los que se obtengan con estos resultados