Chemical synthesis and optical, structural, and surface characterization of InP-In2O3 quantum dots.

InP-In2O3 colloidal quantum dots (QDs) synthesized by a single-step chemical method without injection of hot precursors (one-pot) were investigated. Specifically, the effect of the tris(trimethylsilyl)phosphine, P(TMS)3, precursor concentration on the QDs properties was studied to effectively control the size and shape of the samples with a minimum size dispersion. The effect of the P(TMS)3 precursor concentration on the optical, structural, chemical surface, and electronic properties of InP-In2O3 QDs is discussed. The absorption spectra of InP-In2O3 colloids, obtained by both UV-Vis spectrophotometry and photoacoustic spectroscopy, showed a red-shift in the high-energy regime as the concentration of the P(TMS)3 increased. In addition, these results were used to determine the band-gap energy of the InP-In2O3 nanoparticles, which changed between 2.0 and 2.9 eV. This was confirmed by Photoluminescence spectroscopy, where a broad-band emission displayed from 2.0 to 2.9 eV is associated with the excitonic transition of the InP and In2O3 QDs. In2O3 and InP QDs with diameters ranging approximately from 8 to 10 nm and 6 to 9 nm were respectively found by HR-TEM. The formation of the InP and In2O3 phases was confirmed by X-ray Photoelectron Spectroscopy.

Comparative study of different carbon-supported Fe2O3-Pt catalysts for oxygen reduction reaction.

One of the challenges in electrocatalysis is the adequate dispersion of the catalyst on an appropriate porous support matrix, being up to now the most commonly used the carbon-based supports. To overcome this challenge, carbon supports must first be functionalized to guide the catalyst's nucleation, thereby, improving the dispersion and allowing the use of smaller amount of the catalyst material to achieve a higher electrochemically active surface area. This study present the effect of functionalized Vulcan carbon XC72 (FVC) and functionalized Black Pearl carbon (FBPC) as supports on the catalytic activity of decorated Fe2O3 with Pt. Both carbons were functionalized with HNO3 and subsequently treated with ethanolamine. Fe2O3 nanoparticles were synthesized by chemical reduction and decorated with platinum by epitaxial growth. Pt and Fe2O3 structural phases were identified by XRD and XPS; the Pt content was measured by XPS, and results showed to a high Pt content in Fe2O3-Pt/FBPC. TEM micrographs reveal nanoparticles with an average size of 2 nm in both supported catalysts. The Fe2O3-Pt/FVC catalyst presents the highest specific activity and mass activity, 0.21 mA cm-2Pt and 140 mA mgPt-1, respectively, associated to the appropriate distribution of platinum on the Fe2O3 nanoparticles.

Validation of a HPLC method for simultaneous determination of five sunscreens in lotion preparation.

The aim of this research was to develop and validate a high-performance liquid chromatographic (HPLC) method for simultaneous determination of five sunscreens, namely benzophenone-3 (B-3), butyl methoxydibenzoylmethane (BM), octyl methoxycinnamate (OM), octyl salicylate (OS) and homosalate (HS). The separation and quantitative determination was made by HPLC at 40 +/-1 degrees C with a gradient elution from 10% to 100% mobile phase B in mobile phase A. The gradient liquid chromatographic system constituted of mobile phase A [acetonitrile : water (10 : 90 v/v)] and mobile phase B [acetonitrile : water (90 : 10 v/v)], at a flow rate of 1.0 mL min(-1) and ultraviolet detection at 310 nm. The separation was obtained with two Waters reversed phase columns: Novapack C-18 and Symmetry((R)) C-18 connected in series. All sunscreens were efficiently separated within 17 min. The coefficient of correlation and average recovery for B-3, BM, OM, OS and HS were 0.9798 and 98.5%, 0.9672 and 98.8%, 0.9922 and 99.1%, 0.9961 and 98.9% and 0.9909 and 99.4% respectively. The relative standard deviations obtained were between 1.07% and 2.44%. The excipients did not interfere in the analysis. The results showed that the proposed method could be used for rapid and simultaneous determination of B-3, BM, OM, OS and HS in sunscreen lotions with precision, accuracy and specificity.

Influencia de la serología de la hepatitis viral crónica sobre los niveles de eritropoyetina endógena en los pacientes en hemodiálisis / Influence of serology of the chronic viral hepatitis on the levels of endogenous erythropoietin in the patients in hemodialysis

Nos propusimos conocer si la hepatitis viral crónica afecta la concentración sérica de la eritropoyetina endógena en los pacientes con insuficiencia renal crónica terminal sometidos a tratamiento hemodialítico. Estudiamos a 40 pacientes pertenecientes a la Unidad de Hemodiálisis Fresenius Medical Care de Venezuela, con edades entre los 22 a 77 años, sin haber presentado sangramiento activo, ni haber recibido eritropoyetina humana recombinante ni transfusiones de sangre en los últimos tres meses. El análisis de eritropoyetina se efectuó por quimioluminiscencia. Los valores se expresaron en media aritmética ± DE, como sigue: Core: 8,8 ± 2,03 mU/mL; hepatitis B antígeno de superficie positivo y core positivo: 12,45 ± 1,85 mU/mL; hepatitis C: 15,33 ± 2,91 mU/mL; hepatitis B más hepatitis C: 12,55 ± 3,06m U/mL. El grupo control: 12 ± 2,47 mU/mL (no estadísticamente significativo). Concluimos que en los pacientes con insuficiencia renal crónica terminal en tratamiento hemodialítico crónico, la hepatitis crónica por VHB o VHC, no produce modificaciones de los niveles séricos de eritropoyetina endógena

Efecto de la hidralazina sobre la vasoconstricción pulmonar hipóxica en la arteria pulmonar principal de rata / Effect of the hydralazine on the hypoxia lung vaso constriction in the main lung artery of rat

Estudiamos la vasoconstricción inducida por hipoxia (VPH) en la arteria pulmonar (AP) de la rata, así como el efecto que tienen sobre esta el verapamil (VE) y la hidralazina (HZ). Se montaron anillos de AP de ratas Sprague-Dawley adultas, de 3 mm de longitud, en un baño con solución de Kreb's-Henseleit, a 37º C, pH= 7,3-7,4 y burbujeada con 95 por ciento O2 5 por ciento CO2. Se aplicaron 2 gramos de tensión basal. Luego de estabilización se indujo contracción de la preparación con norepinefrina (NE), 3X10 M. Durante la meseta se cambió el burbujeo por 95 por ciento N2, 5 por ciento CO2 y se obtuvo la VPH sobrepuesta. Luego de relajar la preparación en normoxia, se añadió HZ (5 X 10 M) y media hora después se contrajo nuevamente con NE y se indujo VPH. Esta respuesta disminuyó significativamente en presencia de HZ, pero no en presencia de verapamil (1 X 10 M), cuando se añadió en un protocolo similar. Conclusión: la VPH no es alterada por VE pero se reduce significativamente en presencia de HZ

Normalización de la medición de la actividad de la Na+/K+-ATPasa en glóbulos rojos humanos / Normalization of the measurement activity of the Na+/K+-ATPase in human erythrocytes

Los fantasmas de glóbulos rojos (FGR) humanos obtenidos de sujetos sanos muestran actividad de la Na+/K+-ATpasa de 1,68 ñ 0,08 nmoles Pi/mg proteína x min (n=65; edad: 30 a 60 años). No hubo diferencias entre sexos, tampoco entre muestras obtenidas en ayuno o postprandiales. Comprobamos que la sangre debe mantenerse en frío (0ºC) si no es procesada de inmediato. Obtenidos los FGR a 0ºC, la actividad enzimática no varía entre el momento de la toma y las 4 h; pero si varía significativamente a las 24 y 48 h. Los FGR conservados a -40ºC, mantienen la actividad por 48 h. En dos voluntarios sanos tratados con digoxina por una semana observamos una disminución en la actividad enzimática el primer día (17 por ciento y 22 por ciento de control, respectivamente). Los niveles de digoxina en suero no mostraron paralelismo con la actividad enzimática y fueron siempre menores de 0,7 ng/ml. Conclusión: Se dan las pautas metodológicas para obtener muestras útiles en clínica

Efecto de distintas maniobras inotrópicas sobre la potenciación post-reposo en aurícula izquierda aislada de ratas / Effect of differrent inotrophics manoeuvre on the post-rest in isolation left atrium of rats

Se estudió la potenciación post-reposo (PPR) en aurículas izquierdas de rata, en un baño con solución de tyrode, a 35ºC, burbujeadas con 95 por ciento 02: 5 por ciento CO2. La estimulación basal (1Hz) se interrumpió por períodos de 2,4,8,64,128 segundos y se obtuvo una curva de potenciación de la contracción en función del intervalo de reposo (IR). En condiciones control la contracción fue aumentando con IR hasta los 32 S y luego se mantuvo estable. Un aumento de [Ca2+]e de 1,7 a 3,4mM, no cambió esta cinética. La disminución de [Ca2+]e a 0,85 mM disminuyó la contracción basal (CB) pero se mantuvo la PPR. La disminución de [Na+]e, de 145 a 55mM, aumentó la CB e inhibió la PPR. El cd2+ (0,02mM) y Ni2+ (0,2mM) disminuyeron CB sin variar la PPR. El añadir Mn2+ (0,2mM) fue la única maniobra inotrópica que cambió la cinética de la PPR, ya que no fue incrementado hasta los 128s de intervalo de reposo sin llegar a estabilizarse. Conclusiones: la PPR depende del Ca2+ contenido en el SER. Su cinética varió cuando se añadió Mn al baño, lo que sugiere que este bloqueante puede alterar el movimiento del Ca2+ dentro del RS

Cuantificación de los niveles de eritropoyetina (EPO) endógena y su relación con variables epidemiológicas en un grupo de pacientes en hemodiálisis / Quantification of the endogenous erythropoie (EPO) levels and its relation with epidemiological varible in a group of patients in hemodialysis

Investigamos los valores de la eritropoyetina (EPO) endógena en pacientes con insuficiencia renal crónica terminal en tratamiento hemodialítico. Este estudio se llevó a cabo en 33 pacientes pertenecientes a la Unidad de Hemodiálisis Fresenius Medical Care de Venezuela, con edades compredidas entre los 22 a 77 años, 40 por ciento de raza caucásica, 22 por ciento de raza negra y 38 por ciento mestizos. Los criterios de inclusión fueron: no haber presentado en los últimos tres meses sangramiento activo, ni haber recibido EPO humana recombinante ni transfusiones de sangre en el mismo período de tiempo. Todos los pacientes recibieron tres sesiones de hemodiálisis por semana. Las muestras de sangre se obtuvieron antes de la primera y antes de la última sesión de hemodiálisis de la semana. El análisis de EPO se efectuó por quimioluminiscencia (Nichols Diagnostics Institute, USA). Los valores se expresaron en media aritmética ñ ES. Los valores de EPO endógena fueron de 10,43 ñ 1,35 mU/mL antes de la primera diálisis de la semana, y de 11,36 ñ 0,31 mU/mL antes de la última diálisis de la semana; los valores fueron menores a los descritos en la literatura para otros países. Los valores de EPO relacionados con la raza fueron 12,59 ñ 1,56 mU/mL para las caucásicos, 7,61 ñ 1,07 mU/mL para los negros y 11,09 ñ 1,62 mU/mL para los mestizos. No hubo diferencia en los valores de EPO en relación al día de la diálisis en que se tomó la muestra, ni en relación con la edad, el sexo y la patología de base, pero el tiempo en diálisis juega con 1 a 30 meses en diálisis con los pacientes que tienen de 1 a 60 meses en tratamiento

[Measurement of serum amiodarone by protein precipitation followed by high performance liquid chromatography with ultraviolet detection]. / Cuantificación de amiodarona en suero mediante precipitación de proteínas seguida de cromatografía liquida de alta resolución con detección ultravioleta.

Our aim was to develop a quantitative method for serum amiodarone measurement using high performance liquid chromatography with ultraviolet photometric detection. We studied previous reports in the literature in order to obtain a simpler method to be used routinely in our TDM unit. Sample preparation was based on protein precipitation adding 2 parts of acetonitrile to 1 part of serum, followed by vortex-agitation for 45 s, incubation at 24 degrees C for 5 min, and centrifugation at 6000 x g for 2 min. Twenty microliters of the supernatant was directly injected into the chromatographic system. A microBondapak CN RP column (3.9 x 150 mm) at 45 degrees C, with a mobile phase consisting of KH2PO4 10 mM/methanol/acetonitrile (40:37:23 v/v/v), pH 3.5, were used. Eluting with a flow rate of 0.6 mL/mm the retention time of amiodarone was approximately 4.9 min. Detection was performed at 242 nm and the quantification was made by peak height comparison with external standards. The mass/response ratio is linear (r2 > 0.99) within a mass range of 2.96 to 18,930 ng of injected amiodarone, which exceeds the requirements for the monitoring of serum levels (0.3 to 6.0 micrograms/mL). Sample storage should be done with acetonitrile-extracted sera at -16 degrees C to avoid degradation. The method is very efficient, linear, sensitive and specific but it also simpler and cheaper than others reported in the literature.

[Effect of amiloride and its derivative dichlorobenzamil on guinea pig atria: interaction with other inotropic mechanisms]. / Efecto de la amilorida y su derivado diclorobenzamil sobre la auricula aislada del acure (Cavia porcellus): interaccion con otras maniobras inotropicas.

The inotropic and chronotropic effects of Amiloride (AMI) and Dichloro-benzamil Amiloride (DBC-AMI) were studied on the guinea pig isolated atria, also, the interaction between these drugs and Beta-methyl-Digoxin (BM-DIGO), epinephrine and low extracellular potassium (1 mM). AMI (10(-3) M) has a negative chronotropic and positive inotropic effects, not dependent on the autonomic system. DCB-AMI has a bimodal effect on the contractile force: increases it at low concentrations but causes a decrease at concentrations higher than 10(-6) M. The effect of AMI on the sinus frequency is unchanged by BM-DIGO. AMI (10(-3) M) decreases the inotropic effect of BM-DIGO and increases the toxic concentration of this drug on isolated tissues. The dose-response curve to epinephrine was not changed by AMI. Similar results were obtained using DCB-AMI (2 x 10(-7) M). The positive inotropic effect obtained by low extracellular potassium (1 mM) was not altered by AMI. The activity of the Mg(++)-dependent, Na+/K+ ATPase measured in the microsomal fraction obtained from guinea pig heart was diminished (10%) by AMI (10(-3) M). The drug did not affect the inhibition of the enzyme induced by ouabain. In conclusion, our experiments show multiple effects of AMI and DCB-AMI on the guinea pig heart. The inhibition of the Na+/Ca++ exchange explains them only partially. A slow channel blocking effect appears fundamental to interpret our results.

Efecto de la amilorida y su derivado diclorobenzamil sobre la auricula aislada del acure (Cavia porcellus): interaccion con otras maniobras inotropicas / Effect of amiloride and dichlorobenzamil derivative in the guinea pig atria: interaction with other inotropic mechanisms

Se estudiaron los efectos cronotrópico e inotrópico de la Amilorida (AMI) y la dicloro-benzamil-Amilorida (DCB-AMI) sobre las aurículas aislada del acure, así como la interacción de estas drogas con la beta-metil-digoxina (BM_DIGO), la epinefrina y la disminución del potasio extracelular (de 4 a 1 mM). La AMI (1 mM) causa un efecto inotrópico positivo y cronotrópico negativo, independientes del sistema autonómico. La DCB-AMI causa um efecto bimodal sobre la fuerza de contracción: la aumenta a bajas dosis pero la disminuye a concentraciones mayores de 10(-6) M. También disminuye levemente la frecuencia sinusal. El efecto de la AMI sobre el automatismo sinusal no es alterado por la BM-DIGO. En cambio, la AMI ((10(-3 M) disminuye el efecto inotrópico positivo de la BM-DIGO e incrementa la dosis tóxica en preparaciones aisladas. La curva dosis-respuesta a la epinefrina no varía en presencia de AMI. Resultados similares se obtuvieron con DCB-AMI (2 x 10(-7 M). El incremento de contractilidad que se observa al disminuir la concentración extracelular de potasio a 1 mM no se altera en presencia de AMI. La actividad de la Na+/K+ ATPasa dependiente de Mg++ de la fracción microsomal obtenida del corazón del acure disminuye en 10 por ciento aproximadamente en presencia de AMI (1nM). Por otra parte, el efecto inhibitorio sobre la enzima obtenido con ouabaína no varía con esta droga. En conclusión, nuestros resultados sugieren múltiples efectos de la AMI y DCB-AMI sobre el corazón del acure. La inhibición del intercambiador Na+/Ca++ explica solo parte de ellos; el bloqueo de los canales lentos parece fundamental para explicar nuestras observaciones.

[The electrocardiogram of the guinea pig. Changes induced by beta-methyl digoxin acute administration]. / El electrocardiograma del acure. Cambios inducidos por la admistración aguda de beta-metil digoxina.

In this study we describe the normal electrocardiogram of the Guinea pig (Cavia porcellus), including the correlation between cardiac frequency and the Q-T interval. We studied the acute changes induced by an intraperitoneal dose of beta-methyl digoxin (0.2 mg). The drug produced a significant decrease in cardiac frequency and a significant prolongation of the P-R interval. It did not change the QRS duration or its position on the frontal plane. The Q-T interval, corrected by cardiac frequency, showed a tendency to decrease with treatment, but this change did not reach significance. The drug caused characteristic changes in ventricular repolarization: the T wave changed its polarity and S-T segment shifted to negative potential (between 0.05 and 0.15 mV). The possible origin of these observation is discussed.

[Effect of the in vivo administration of beta-methyldigoxin on the Na, K-ATPase measured in different tissues of guinea pigs]. / Effecto de la beta-metil digoxina, administrada in vivo, sobre la actividad de la Na,K-ATPasa de diferentes tejidos de acure.

We measured the activity of the Na,K ATPase, Mg dependent and inhibited by ouabain, in microsomal fractions obtained from guinea pig myocardium and kidney, as weel as red cell ghosts. A group of animal was treated with beta-methyl digoxin (0.2 mg intraperitoneally) about one hour before obtaining the tissues. The control group received no medication. The plasma of both group, control and treated, had similar potassium concentrations (4.3 +/- 0.87 mM and 4.3 +/- 0.66 mM, respectively). The plasma digoxin concentrations from treated animals was always high (76.4 +/- 34.1 ng/ml). The Na,K-ATPase activity in the microsomal fraction from treated animals decreased by 28.7% in myocardium and by 27.7% in red cell ghosts, in comparison to the enzime activity measured in control animals. On the other hand, the Na/K activity obtained in kidney microsomal fraction did not change with treatment. We then measured the Na,K-ATPase activity in the red cell ghosts and microsomal fractions obtained from myocardium and kidney of untreated Guinea pigs. Adding digoxin in vitro (1 x 10(-9) M to 1 x 10(-3) M) we obtained, in myocardial fractions, a 50% maximal inhibition; the digoxin concentration causing half maximal effect (DI50) was 7 x 10(-5) M. In the kidney microsomal fraction we measured a 66% maximal inhibition of the enzime activity and DI50 was 2 x 10(-6) M. For red cell ghosts the maximal enzime inhibition was 34% and the DI50 was 1 x 10(-5) M. In conclusion, in the Guinea pig, the acute in vivo administration of beta-methyl digoxin causes a parallel inhibition of the Na,K-ATPase from myocardial fractions and red cell ghosts. We measured no significant change in the kidney microsomal fractions. We propose the determination of red cell Na,K-ATPase activity as possible indicator of digitalis effect on humans treated with these drugs.

Fine needle aspiration biopsy in the management of patients with deep seated metastatic and recurrent malignancies.

Fine needle aspiration (F.N.A.) is widely accepted as a safe and reliable diagnostic technique. In patients presenting with widespread metastatic disease of unknown primary origin it can play an important role in providing a rapid and accurate diagnosis and therefore allowing to institute a prompt therapeutic approach. This technique can usually be performed in an outpatient setting needing no hospitalization therefore reducing the cost both for the hospital and for the patient. When a definitive diagnosis is reached with the use of F.N.A. the patient can be spared from unnecessary surgery. A few examples are presented of patients with widespread metastatic disease in which a definitive diagnosis was reached through the use of F.N.A.

Altered response of adenylate cyclase to parathyroid hormone during compensatory renal growth.

The loss of renal mass is associated with functional adaptations in the remaining nephrons to maintain homeostasis. Although parathyroid hormone (PTH) is important in the adaptations to phosphate, the mechanisms are not completely defined. In the present studies we examined the response of the adenylate cyclase system to PTH in renal cortical membranes of rat kidneys ten days after unilateral nephrectomy. The kidneys obtained at the time of the initial nephrectomy were used as controls. Unilateral nephrectomy resulted in contralateral compensatory renal growth, as demonstrated by a 24 +/- 4.7% (P less than 0.01) increase in weight in the remaining kidney. Glomerular filtration rate (GFR) after unilateral nephrectomy was 62% of the control, while basal fractional phosphate excretion was higher in rats with unilateral nephrectomy (7.7 +/- 2.1% vs. 2.9 +/- 0.8%, P less than 0.05). PTH infusion resulted in a similar increase of fractional phosphate excretion and urinary cAMP in both groups. In the absence of added guanine nucleotides, PTH-dependent adenylate cyclase activity in cortical membranes from kidneys with compensatory growth was decreased as compared to controls (Vmax 807.5 +/- 62.7 pmol cAMP/mg protein/30 min vs. 1,384.8 +/- 116.1, respectively, P less than 0.01). The apparent affinity for PTH stimulation of adenylate cyclase (Kact) was unchanged. Magnesium-dependent adenylate cyclase activity was also decreased in the membranes from kidneys with compensatory growth. However, the kinetics of adenylate cyclase for the substrates ATP-Mg or ATP-Mn were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Presencia de colinesterasas en la membrana de las vesiculas de Cysticercus cellulosae. / Presence of cholinesterases in the vesicle membrane of Cysticercus cellulosae

En este estudio se demostro que Cysticercus cellulosae contiene seudocolineterasas y acetilcolinesterasa. Los sitios de localizacion de estas enzimas son las partes externa e interna del tegumento de la vesicula. El cisticerco completo muestra niveles menores de enzima en relacion con la cantidad obtenida en membrana. Los niveles obtenidos de acetilcolinesterasa son mayores que los de seudocolinesterasas. El escolex contiene acetilcolinesterasa en cantidades detectables, pero los niveles registrados de seudocolinesterasas son tan bajos que podrian corresponder a restos de celulas del tegumento que circundan el escolex. De lo anterior se derivan las bases establecidas para el tratamiento de la cistecercosis con substancias anticolinesterasicas, como lo es el metrifonato