Effect of the shear rate and residence time on the lysis of AC16 human cardiomyocyte cells via surface acoustic waves.

The efficient breakage of one cell or a concentration of cells for releasing intracellular material such as DNA, without damaging it, is the first step for several diagnostics or treatment processes. As the cell membrane is easy to bend but resistant to stretching, the exposure of the cell to a shear rate during a short period of time can be sufficient to damage the membrane and facilitate the extraction of DNA. However, how to induce high shear stresses on cells in small microliter volumes samples has remained an elusive problem. Surface acoustic waves operating at high frequencies can induce acoustic streaming leading to shear rates sufficient to cell lysis. Lysis induced by acoustic streaming in sessile droplets has been investigated in the past from the lysis efficiency point of view. However, the effects of the velocity field and shear rate induced by acoustic streaming on the lysis process remain unexplored. Here, we study the lysis of AC16 human cardiomyocytes in microliter droplets under the effect of the shear rate induced by acoustic streaming. It is identified that for a given shear rate, the extracted DNA is also affected by the actuation period which can be attributed to a cycling process that leads to an accumulation of damage on the cell membrane.

In-droplet cell lysis of AC16 human cardiomyocyte cells via surface acoustic waves.

Although several lysis methods are available, biomedical applications are pushing the demand for miniaturised systems and thus for new ways to lyse cells in small volumes. In this work, we demonstrate in-droplet cell lysis of AC16 human cardiomyocyte cells in 20 µL droplets using high frequency surface acoustic waves. The acoustic streaming leads to high shear flow creating porous or breaking the cell membrane and releasing intracellular material. Contrary to previous work where the lysis efficiency is measured by a cell-permeant dye that can be used to determine cell viability, here we propose to quantify the DNA extracted from the cells as a measure of the lysis efficiency. This reagent-free method provides a valuable cell lysis alternative for many biological and biomedical applications, particularly for the development of point-of-care platforms.

Infección por bartonella henselae en pacientes pediátricos. Lesión pseudotumoral de calota. Reporte de caso

Los tumores de calota en pacientes pediátricos poseen múltiples etiologías. Dentro de las causas pseudotumorales, las infecciones juegan un rol importante, siendo la osteomielitis por Bartonella henselae (Enfermedad por Arañazo de Gato) una posibilidad diagnóstica rara, pero que debe ser estudiada y descartada. Se presenta el caso de una lactante de 1 año, con lesión expansiva de calota, a nivel frontal derecho, hipervascularizada e infiltrativa. Se realizó estudio con ultrasonido, tomografía cerebral y cintigrama óseo. Se realizó resección quirúrgica completa de la lesión, con preservación de la duramadre y zona fontanelar, además de un cuidadoso trato con el seno sagital superior. Evolucionó sin complicaciones perioperatorias. El resultado de la biopsia fue compatible con proceso inflamatorio crónico, osteomielitis supurada. Tinción de Warthin Starry positiva sugerente de Bartonella henselae. Se descartó etiología tuberculosa y fúngica. Serología positiva para Bartonella henselae. La paciente completó antibioticoterapia, azitromicina y cotrimoxazol, con evolución clínica favorable.

Calvarial tumors in pediatric patients have multiple etiologies. Among the pseudotumoral causes, infections play an important role, being Bartonella henselae osteomyelitis (Cat Scratch Disease) a rare diagnostic possibility, but it should be studied and ruled out. We present the case of a 1 year old infant, with an expansive lesion of the calvaria, at right frontal level, hypervascularized and infiltrative. Ultrasound, brain tomography and bone scintigram were performed. Complete surgical resection of the lesion was performed, with preservation of the dura mater and fontanel area, in addition to a careful treatment with the superior sagittal sinus. The patient evolved without perioperative complications. The biopsy result was compatible with a chronic inflammatory process, suppurative osteomyelitis. Positive Warthin Starry stain suggestive of Bartonella henselae. Tuberculous and fungal etiology was ruled out. Positive serology for Bartonella henselae. The patient completed antibiotic therapy, azithromycin and cotrimoxazole, with favorable clinical evolution.

Evaluation of the anorectal motor response after percutaneous stimulation of the posterior tibial nerve in patients with fecal incontinence.

BACKGROUND: The effect of posterior tibial nerve stimulation (PTNS) on the mechanisms of anal continence has not been fully demonstrated. The aim of this study was to assess the anal manometric response after percutaneous PTNS in patients with fecal incontinence (FI). METHODS: This was a prospective study in patients with FI undergoing 1 weekly session of percutaneous PTNS for 8 weeks. A clinical assessment (Wexner scale) and a complete study of up to 22 manometric parameters were carried out prior to treatment and 2-4 weeks after the end of treatment. RESULTS: A total of 32 patients were evaluated. After therapy, there was a decrease in the average Wexner score [12.6 (± 5.2) to 9.5 (± 5.2) (P < 0.005)] and an increase in the "anal canal length at rest" [4.55 (± 0.60) to 4.95 (± 0.21) P = 0.004], without observing variations in other manometric parameters. The decrease in the Wexner score was significantly correlated with an increase in the "pressure at 5 cm at rest" after therapy (r = 0.464 P = 0.030). CONCLUSIONS: In our study, PTNS was associated with a significant decrease in the Wexner score and with an increase in the functional length of the anal canal at rest. The improvement in the Wexner scale was correlated with an increase in pressure at rest in the theoretical area of the anorectal junction.

Physicochemical conditions for ZnO films deposited by microwave chemical bath deposition.

Physicochemical analysis was carried out to obtain the species distribution diagrams (SDDs) for the deposition of ZnO films as a function of OH- ion concentration ([OH-]) in the reaction solution. The study of SDDs predicts nucleation and ZnO film growth by means of the dominant species at a given pH value. To confirm this, a series of experiments were made varying the [OH-] in the reaction solution and keeping the others parameters constant. Structured zinc oxide (ZnO) films were obtained on glass substrates by microwave chemical bath deposition (MWCBD). Structural, optical and morphological ZnO film properties were investigated as a function of [OH-]. X-Ray diffraction technique (XRD) measurements show multiple diffraction peaks, indicating the polycrystalline nature of ZnO films. Scanning Electron Microscopy (SEM) images of ZnO structures showed morphological changes with the variation of [OH-]. The stoichiometry of the structures changed as the [OH-] was varied in solution. From Raman spectra, it was observed that the [OH-] of the reaction mixture strongly affects the crystal quality of ZnO structures. A reaction pathway for the synthesis of ZnO structures based on our results is proposed. Experimental results are consistent with the physical-chemical analysis.

Selective in situ functionalization of biosensors on LOC devices using laminar co-flow.

Many applications involving lab-on-a-chip (LOC) devices are prevented from entering the market because of difficulties to achieve mass production and impart suitable properties allowing long-term storage. To integrate biosensors on these microfluidic chips, one of the main restrictions is the fabrication and stability of the molecular modifications that must be performed on the surfaces of the sensors for a given application. The complexity of the problem increases exponentially when the LOC integrates several of these sensors. Here we present a system based on laminar co-flow to perform an on-chip selective surface bio-functionalization of LOC-integrated sensors. This method has the advantage that the surface modification protocols are performed in situ before analyte detection. This approach reduces the burdens during LOC fabrication, keeping the required reagents stored outside of the detection structure in suitable wet conditions. The proof of concept is demonstrated through an optical characterization followed by electronic detection based on a novel differential impedance measurement setup. The system can be easily scaled to incorporate several sensors with distinct biosensing targets in a single chip.

Use of a prosthetic mesh to prevent parastomal hernia during laparoscopic abdominoperineal resection: a randomized controlled trial.

PURPOSE: Prevention of parastomal hernia represents an important aim when a permanent stoma is necessary. The objective of this work is to assess whether implantation of a prophylactic prosthetic mesh during laparoscopic abdominoperineal resection contributed to reduce the incidence of parastomal hernia. METHODS: Rectal cancer patients undergoing elective laparoscopic abdominoperineal resection with permanent colostomy were randomized to placement of a large-pore lightweight mesh in the intraperitoneal/onlay position by the laparoscopic approach (study group) or to the control group (no mesh). Parastomal hernia was defined radiologically by a CT scan performed after 12 months of surgery. The usefulness of subcutaneous fat thickness measured by CT to discriminate patients at risk of parastomal hernia was assessed by ROC curve analysis. RESULTS: Thirty-six patients were randomized, 19 to the mesh group and 17 to the control group. Parastomal hernia was detected in 50 % of patients in the mesh group and in 93.8 % of patients in the control group (P = 0.008). The AUC for thickness of the subcutaneous abdominal was 0.819 (P = 0.004) and the optimal threshold 23 mm. Subcutaneous fat thickness ≥23 mm was a significant predictor of parastomal hernia (odds ratio 15.7, P = 0.010), whereas insertion of a mesh was a protective factor (odds ratio 0.06, P = 0.031). CONCLUSIONS: Use of prophylactic large-pore lightweight mesh in the intraperitoneal/onlay position by a purely laparoscopic approach reduced the incidence of parastomal hernia formation. Subcutaneous fat thickness ≥23 mm measured by CT was an independent predictor of parastomal hernia.

Synthesis and characterization of PbSe nanoparticles obtained by a colloidal route using Extran as a surfactant at low temperature.

Lead selenide nanoparticles (PbSe NPs) have been obtained through an easy and low cost route using colloidal synthesis in aqueous solution. The synthesis was carried out at room temperature using Extran (Na5P3O10, NaOH and H2O) as surfactant. Hydrochloric acid (HCl) was used to eliminate the generated by-products. The size of PbSe NPs was varied by changing the Pb:Se molar concentration. The PbSe NPs were characterized by powder x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. The XRD measurements showed that the PbSe NPs have the face-centered cubic phase structure. The crystal size was found to be between 14 and 20 nm as calculated from the XRD patterns and these values were corroborated with SEM and TEM. Additionally, HRTEM micrographs showed crystalline planes at (200), (220) and (111) of the PbSe NPs, in agreement with the XRD results.

Pinning and avalanches in hydrophobic microchannels.

Rare events appear in a wide variety of phenomena such as rainfall, floods, earthquakes, and risk. We demonstrate that the stochastic behavior induced by the natural roughening present in standard microchannels is so important that the dynamics for the advancement of a water front displacing air has plenty of rare events. We observe that for low pressure differences the hydrophobic interactions of the water front with the walls of the microchannel put the front close to the pinning point. This causes a burstlike dynamics, characterized by series of pinning and avalanches, that leads to an extreme-value Gumbel distribution for the velocity fluctuations and a nonclassical time exponent for the advancement of the mean front position as low as 0.38.

Ablación por radiofrecuencia de carcinomas de mama: resultados preliminares de un ensayo clínico / Radiofrequency ablation of breast carcinomas: preliminary results of a clinical trial

Objetivo: Entre las alternativas a la cirugía conservadora del cáncer de mama, la ablación por radiofrecuencia (ARF) es la que ha alcanzado mayor difusión. Nuestro objetivo es determinar la factibilidad, seguridad y eficacia de esta técnica en nuestro medio. Material y métodos: Se realiza ARF de carcinomas de mama con anestesia local y en la sala de ecografía, tratamiento quirúrgico y comprobación histológica posterior, evaluando los efectos de la ARF sobre el tumor y los tejidos circundantes. Material y métodos: Se incluyeron 35 pacientes con edad media de 61,2±8,25 años, todas con carcinoma infiltrante confirmado percutáneamente,<2cm, alejado de la piel y la pared torácica. Tamaño tumoral medio 8,9±2,9mm. Se realizó linfadenectomía selectiva antes de la ARF. A las 2–4 semanas de ésta se llevó a cabo el tratamiento quirúrgico. Material y métodos: El grado de necrosis de coagulación y la afectación de márgenes se evaluaron con tinción de hematoxilina-eosina, y la viabilidad celular o efectividad de la ARF mediante NADH-diaforasa. Resultados: El 85,7% de pacientes no sintió molestias. El 11,4% refirió dolor ligero que pudo ser controlado. El dolor intenso obligó a detener el procedimiento en 1 paciente. No se produjeron otras complicaciones. Resultados: Se encontraron cambios de necrosis coagulativa en todos los casos, catalogada como completa en 32/35 (91,4%). La NADH-diaforasa resultó negativa en 27/32 casos en que se realizó. Una fue ligeramente positiva y 4 no valorables. Conclusión: La ARF es una técnica factible, bien tolerada, segura y eficaz en casi el 90% de los tumores infiltrantes de mama. La confirmación de su eficacia deberá hacerse mediante seguimiento prolongado de pacientes no intervenidas, con ensayos clínicos en fase III cuidadosamente diseñados y monitorizados (AU)

Objective: Among the alternatives to breast conserving surgery in breast cancer, radiofrequency ablation is the most widespread. We aimed to determine the feasibility, safety, and efficacy of this technique in our environment. Material and methods: We performed radiofrequency ablation of breast carcinomas under local anesthesia in the ultrasonography examination room. We included 35 patients (mean age = 61.2 ± 8.25 years) with invasive carcinomas measuring less than 2 cm (mean diameter = 8.9 ± 2.9mm) and located far from the skin and chest wall. Prior to radiofrequency treatment, all patients underwent core biopsy to confirm that the tumors were invasive carcinomas and selective lymphadenectomy. Carcinomas were excised 2 to 4 weeks after radiofrequency treatment and analyzed histologically to evaluate the effects of radiofrequency treatment on the tumor and surrounding tissue. The degree of coagulation necrosis and involvement of the margins was evaluated using hematoxylin and eosin staining. Cellular viability or effectiveness of the radiofrequency treatment was evaluated using NADH diaphorase. Results: In total, 85.7% of patients reported no discomfort; 11.4% reported mild, controllable pain. Intense pain required the procedure to be discontinued in one patient. No other complications occurred. Results: Signs of coagulation necrosis were observed in all cases; coagulation necrosis was classified as complete in 32/35 (91.4%). NADH diaphorase was negative in 27 of the 32 cases in which it was performed; one case was slightly positive and the other four were impossible to evaluate. Conclusion: Radiofrequency ablation of breast carcinomas is feasible, well tolerated, safe, and efficacious in nearly 90% of invasive tumors. The efficacy of the technique should be confirmed through extended follow-up of patients without subsequent surgical intervention in carefully designed and monitored phase III trials (AU)

[Radiofrequency ablation of breast carcinomas: preliminary results of a clinical trial]. / Ablación por radiofrecuencia de carcinomas de mama: resultados preliminares de un ensayo clínico.

OBJECTIVE: Among the alternatives to breast conserving surgery in breast cancer, radiofrequency ablation is the most widespread. We aimed to determine the feasibility, safety, and efficacy of this technique in our environment. MATERIAL AND METHODS: We performed radiofrequency ablation of breast carcinomas under local anesthesia in the ultrasonography examination room. We included 35 patients (mean age=61.2+/-8.25 years) with invasive carcinomas measuring less than 2cm (mean diameter=8.9+/-2.9mm) and located far from the skin and chest wall. Prior to radiofrequency treatment, all patients underwent core biopsy to confirm that the tumors were invasive carcinomas and selective lymphadenectomy. Carcinomas were excised 2 to 4 weeks after radiofrequency treatment and analyzed histologically to evaluate the effects of radiofrequency treatment on the tumor and surrounding tissue. The degree of coagulation necrosis and involvement of the margins was evaluated using hematoxylin and eosin staining. Cellular viability or effectiveness of the radiofrequency treatment was evaluated using NADH diaphorase. RESULTS: In total, 85.7% of patients reported no discomfort; 11.4% reported mild, controllable pain. Intense pain required the procedure to be discontinued in one patient. No other complications occurred. Signs of coagulation necrosis were observed in all cases; coagulation necrosis was classified as complete in 32/35 (91.4%). NADH diaphorase was negative in 27 of the 32 cases in which it was performed; one case was slightly positive and the other four were impossible to evaluate. CONCLUSION: Radiofrequency ablation of breast carcinomas is feasible, well tolerated, safe, and efficacious in nearly 90% of invasive tumors. The efficacy of the technique should be confirmed through extended follow-up of patients without subsequent surgical intervention in carefully designed and monitored phase III trials.

Assessing substitution patterns, rates and homoplasy at HVRI of Steller sea lions, Eumetopias jubatus.

Despite the widely recognized incidence of homoplasy characterizing this region, the hypervariable region I (HVRI) of the mitochondrial control region is one of the most frequently used genetic markers for population genetic and phylogeographic studies. We present an evolutionary analysis of HVRI and cytochrome b sequences from a range-wide survey of 1031 Steller sea lions, Eumetopias jubatus, to quantify homoplasy and substitution rate at HVRI. Variation in HVRI was distributed across 41 variable sites in the 238-bp segment examined. All variants at HVR1 were found to be transitions. However, our analyses suggest that a minimum of 101 changes have actually occurred within HVRI with as many as 18 substitutions occurring at a single site. By including this hidden variation into our analyses, several instances of apparent long-range dispersal were resolved to be homoplasies and 8.5-12% of observed HVRI haplotypes were found to have geographic distributions descriptive of convergent molecular evolution rather than identity by descent. We estimate the rate of substitution at HVRI in Steller sea lions to be approximately 24 times that of cytochrome b with an absolute rate of HVRI substitution estimated at 27.45% per million years. These findings have direct implications regarding the utility of HVRI data to generate a variety of evolutionary genetic hypotheses.

Manejo de lesiones vasculares benignas

Las lesiones vasculares benignas son básicamente hemangiomas y malformaciones vasculares. El diagnóstico preciso permite el tratamiento más adecuado a cada paciente. El conocimiento de las diferentes formas de presentación es importante para el éxito en el manejo de estas lesiones vasculares

Benign vascular lesions are mainly hemangiomas and vascular malformations. Knowing the different clinical presentations is extremely important and will allow making the right diagnosis and, in consequence, applying the proper treatment

Strong isotope effects on the charge transfer in slow collisions of He2+ with atomic hydrogen, deuterium, and tritium.

Probabilities and cross sections for charge transfer by He2+ impact on atomic hydrogen (H), deuterium (D), and tritium (T) at low collision energies are calculated. The results are obtained using an ab initio theory, which solves the time-dependent Schrödinger equation. For the H target, excellent agreement is achieved between the present and previous results. Differences by orders of magnitude are observed between the cross sections for H, D, and T. A method is introduced to separate the contributions of charge-transfer mechanisms due to radial and rotational coupling. The large differences observed for H, D, and T are attributed to isotope effects in the rotational coupling mechanism.

Impact of surgical procedure for gastric cancer on quality of life.

BACKGROUND: The aim was to assess quality of life in a group of patients who had a curative resection for gastric cancer. METHODS: The European Organization for Research and Treatment of Cancer QLQ-C30 questionnaire with a gastric cancer-specific module was used in patients who had undergone R0 gastrectomy between 1992 and 1999, and who had no disease at the last check-up. A response was obtained from 54 patients, 36 men and 18 women, of mean age 67 years. Of these, 24 patients had total gastrectomy and 26 D2 lymphadenectomy. RESULTS: Significant differences were found only in the social domain of quality of life in patients aged over 70 years (P = 0.036); there was no impact of operation type on overall quality of life. CONCLUSION: The quality of life of patients undergoing curative surgery for gastric cancer, regardless of age, was not significantly influenced by the type of gastrectomy, or whether lymphadenectomy was performed.

The value of D1 lymphadenectomy as prognostic marker in gastric cancer.

BACKGROUND/AIMS: To assess if the study on the involvement of perigastric lymph nodes, the only ones resected in D1 lymphadenectomy, is a valid prognostic marker in patients undergoing curative resection for gastric cancer. METHODOLOGY: A retrospective study was performed in 101 patients with gastric cancer, 34 women and 67 men, with a mean age of 61 years, undergoing curative resection by gastrectomy and D1 lymphadenectomy. Tumor size, the depth of tumoral invasion of the wall, nodal involvement and 5-year survival were assessed. RESULTS: Both tumor size and the depth of tumoral invasion of the wall were significantly related to metastatic involvement of perigastric lymph nodes. Similarly, tumoral involvement of the first-level lymph nodes was significantly associated with survival. CONCLUSIONS: D1 lymphadenectomy can provide adequate prognostic information in patients with gastric cancer undergoing curative resection.

Cáncer de muñón gástrico: resultados del tratamiento quirúrgico / Gastric stump cancer: results of surgical treatment

Introducción. El pronóstico de cáncer de muñón gástrico, en general, es peor que el de cáncer gástrico primario. Métodos. Un total de 33 pacientes con cáncer de muñón tratados en nuestro servicio desde 1984 a 1999, 31 varones y 2 mujeres, con una edad media de 69,6 años. La primera intervención fue por úlcera gástrica en 14 casos, y duodenal o pilórica en 19. Presentaban gastrectomía Billroth II 22 pacientes y Billroth I 11 pacientes. El intervalo medio entre la primera operación y el diagnóstico del tumor fue de 30,6 años. Resultados. Fueron operados 27 pacientes; el índice de resecabilidad fue del 66,6 por ciento. Se realizaron 16 gastrectomías totales, 6 de ellas ampliadas y 2 casi totales. Predominó el adenocarcinoma tipo intestinal (22 casos); 4 pacientes presentaban tumores precoces (early) y en 13 (72,2 por ciento) existía afección de la serosa (pT3-pT4). La supervivencia actuarial global a los 5 años es del 22 por ciento, un 41,4 por ciento en los pacientes resecados (p < 0,001). Fue significativa la supervivencia de los casos resecados según el tamaño del tumor (p < 0,05).Conclusiones. En los pacientes gastrectomizados parece aconsejable el control endoscópico a partir de los 15 años para mejorar la resecabilidad y la supervivencia mediante un diagnóstico más precoz. La supervivencia obtenida en los casos tratados con gastrectomía total justifica este tratamiento quirúrgico agresivo. Hubo diferencias significativas en la supervivencia según el tamaño del tumor (AU)