Polycaprolactone- and polycaprolactone/ceramic-based 3D-bioplotted porous scaffolds for bone regeneration: A comparative study.

One of the critical challenges that scaffolding faces in the organ and tissue regeneration field lies in mimicking the structure, and the chemical and biological properties of natural tissue. A high-level control over the architecture, mechanical properties and composition of the materials in contact with cells is essential to overcome such challenge. Therefore, definition of the method, materials and parameters for the production of scaffolds during the fabrication stage is critical. With the recent emergence of rapid prototyping (RP), it is now possible to create three-dimensional (3D) scaffolds with the essential characteristics for the proliferation and regeneration of tissues, such as porosity, mechanical strength, pore size and pore interconnectivity, and biocompatibility. In this study, we employed 3D bioplotting, a RP technology, to fabricate scaffolds made from (i) pure polycaprolactone (PCL) and (ii) a composite based on PCL and ceramic micro-powder. The ceramics used for the composite were bovine bone filling Nukbone® (NKB), and hydroxyapatite (HA) with 5%, 10% or 20% wt. CONTENT: The scaffolds were fabricated in a cellular lattice structure (i.e. meshing mode) using a 0/90° lay down pattern with a continuous contour filament in order to achieve interconnected porous reticular structures. We varied the temperature, as well as injection speed and pressure during the bioplotting process to achieve scaffolds with pore size ranging between 200 and 400µm and adequate mechanical stability. The resulting scaffolds had an average pore size of 323µm and an average porosity of 32%. Characterization through ATR-FTIR revealed the presence of the characteristic bands of hydroxyapatite in the PCL matrix, and presented an increase of the intensity of the phosphate and carbonyl bands as the ceramic content increased. The bioplotted 3D scaffolds have a Young's modulus (E) in the range between 0.121 and 0.171GPa, which is compatible with the modulus of natural bone. PCL/NKB scaffolds, particularly 10NKBP (10% NKB wt.) exhibited the highest proliferation optical density, demonstrating an evident osteoconductive effect when cultured in Dulbecco's Modified Eagle Medium (DMEM). Scanning electron microscopy (SEM) confirmed osteoblast anchorage to all composite scaffolds, but a low adhesion to the all-PCL scaffold, as well as cell proliferation. The results from this study demonstrate the potential of PCL/NKB 3D bioplotted scaffolds as viable platforms to enable osseous tissue formation, which can be used in several tissue engineering applications, including improvement of bone tissue regeneration.

Sonochemical assisted synthesis of SrFe12O19 nanoparticles.

We present the synthesis of M-type strontium hexaferrite by sonochemistry and annealing. The effects of the sonication time and thermal energy on the crystal structure and magnetic properties of the obtained powders are presented. Strontium hexagonal ferrite (SrFe12O19) was successfully prepared by the ultrasonic cavitation (sonochemistry) of a complexed polyol solution of metallic acetates and diethylene glycol. The obtained materials were subsequently annealed at temperatures from 300 to 900 °C. X-ray diffraction analysis shows that the sonochemical process yields an amorphous phase containing Fe(3+), Fe(2+) and Sr(2+) ions. This amorphous phase transforms into an intermediate phase of maghemite (γ-Fe2O3) at 300 °C. At 500 °C, the intermediate species is converted to hematite (α-Fe2O3) by a topotactic transition. The final product of strontium hexaferrite (SrFe12O19) is generated at 800 °C. The obtained strontium hexaferrite shows a magnetization of 62.3 emu/g, which is consistent with pure hexaferrite obtained by other methods, and a coercivity of 6.25 kOe, which is higher than expected for this hexaferrite. The powder morphology is composed of aggregates of rounded particles with an average particle size of 60 nm.

Adelantamiento rotuliano tipo Bandi versus limpieza articular artroscópica para el manejo de la artrosis patelofemoral: Seguimiento a un año / Bandi tibial tubercule osteotomy vs artrhroscopy lavage in patelo femoral arthritis: 1 year follow-up

Introducción: La osteoartritis (OA) es una artropatía degenerativa que modifica las propiedades mecánicas y biológicas, del cartílago articular y del hueso subcondral, su tratamiento va encaminado hacia el alivio del dolor, mantener la función articular y reducir la progresión de la enfermedad. El objetivo de este trabajo es comparar los resultados quirúrgicos de la limpieza articular artroscópica y adelantamiento rotuliano utilizando la escala WOMAC. Metodología: Estudio transversal en el que se compara el resultado funcional del tratamiento de la OA patelofemoral en pacientes operados por limpieza articular artroscópica y pacientes operados por adelantamiento rotuliano con técnica de Bandi. Las variables fueron, género, edad, lado afectado, técnica quirúrgica e índice de WOMAC prequirúrgico y a los 12 meses de seguimiento. Utilizamos estadística descriptiva así como t de Student para la diferencia de promedios de WOMAC entre ambos grupos de pacientes. Resultados: n = 37 pacientes, la edad promedio fue 53.48 años (28-82), ± 12.55, el género 11 (29.7%) hombres y 26 (70.3%) mujeres, el lado afectado: 19 (51.35%) derecho y 18 (48.65%) izquierdo. Técnica quirúrgica: 45.9% artroscópico y 54.1% con técnica de Bandi. Los pacientes operados mediante Bandi y adelantamiento rotuliano tuvieron mejoría del dolor, rigidez articular y de la función física (p = 0.00); la comparación del puntaje global de WOMAC para ambas técnicas al año no mostró diferencias estadísticamente significativas (p = 0.78). Conclusión: Ambas técnicas (Bandi y limpieza artroscópica) ofrecen buenos resultados a los 365 días de operados, sin embargo, los pacientes manejados por limpieza artroscópica presentan menor dolor comparados con los de adelantamiento rotuliano tipo Bandi.

Introduction: Osteoarthritis is a degenerative joint disease that modifies the mechanical and biological properties of articular cartilage and subchondral bone, treatment is aimed at relieving pain, maintain joint and reduce disease progression function. The aim of this paper is to compare the surgical outcomes of the arthroscopic articular cleaning and Bandi procedure by using the WOMAC scale. Methods: Cross-sectional study, functional outcome of treatment of patellofemoral ostheoarthritis by arthroscopic articular cleaning and Bandi procedure are compared. Variables were gender, age, affected side, surgical technique and preoperative and 12 months follow up WOMAC evaluation. We used descriptive statistics and t-test for mean difference in WOMAC between both groups of patients. Results: n = 37 patients, the mean age was 53.48 (28-82), ± 12.55 years; 11 (29.7%) males and 26 (70.3%) women, the affected side: 19 (51.35%) right and 18 (48.65%) left. Surgical technique: 45.9% arthroscopic articular cleaning and 54.1% Bandi procedure. Patients operated by both technics: Bandi and arthroscopic articular cleaning had improvement in pain, stiffness and physical function (p = 0.00); comparison of global WOMAC score for both techniques a year after showed no statistically significant differences (p = 0.78). Conclusion: Both techniques (Bandi and arthroscopic articular cleaning) offer good results at 365 days of surgery, however patients managed by arthroscopic articular cleaning have less pain compared with Bandi procedure.

Estudio del nivel de concordancia entre los diagnósticos prequirúrgico y artroscópico de lesiones meniscales asociadas a lesiones del ligamento cruzado anterior / Concordance between preoperatory diagnosis and arthroscopy findings of meniscal lesions associated to anterior cruciate ligament injury

Introducción: Las lesiones ligamentarias de la rodilla son comunes durante la segunda y tercera décadas de vida, su diagnóstico clínico es difícil ya que puede diferir con el diagnóstico definitivo. El objetivo es determinar la concordancia entre el diagnóstico preoperatorio-diagnóstico postoperatorio y entre la lesión meniscal sospechada-lesión meniscal encontrada, en pacientes con lesión del ligamento cruzado anterior. Material y métodos: Estudio transversal. En 29 pacientes con lesión del ligamento cruzado anterior a los cuales se realizó artroscopía. Las variables fueron edad, género, lado afectado, diagnóstico preoperatorio, diagnóstico postoperatorio, lesión meniscal sospechada, lesión meniscal encontrada. La estadística utilizada fue descriptiva, para la concordancia se usó índice de Kappa de Cohen. Resultados: Fueron 29 pacientes, 23 (79.3%) hombres y 6 (20.7%) mujeres, la edad promedio: 39.04 (15-50) ± 13.19 años, lado afectado derecho 69% e izquierdo 31%; el diagnóstico preoperatorio en 22 (75%) pacientes fue LLCA aislada, LLCA + menisco medial 6 (20.7%), LLCA + menisco lateral 1 (3.4%) y el diagnóstico artroscópico fue en 20 (68.96%) sin lesión meniscal, 7 (24.1%) lesión en menisco medial, 2 (6.9%) en menisco lateral, con una concordancia baja (Kappa 0.2), la concordancia diagnóstica preoperatoria intraobservador fue perfecta (Kappa 1.0); y la concordancia entre el diagnóstico de la lesión meniscal preoperatoria y de la lesión meniscal artroscópica fue baja (Kappa 0.2). Conclusiones: La concordancia entre el diagnóstico clínico-radiológico y el diagnóstico artroscópico en lesiones del LCA con asociación de lesión meniscal es baja, lo cual se tiene que tener en cuenta en la realización del diagnóstico inicial y en el tratamiento artroscópico de los pacientes.

Introduction: Ligament injuries of the knee joint are common during the second and third decades of life, clinical and radiological diagnosis presents difficulties since the surgical findings may differ significantly. The objective is to determine correlation between clinical-radiologic and arthroscopic diagnosis in patients with injury of the anterior cruciate ligament (ACL) and meniscal lesions. Material and methods: Cross-sectional study held in 29 patients with ACL injury associated to meniscal lesions treated arthroscopically. Variables were age, gender, affected side, preoperative and postoperative diagnosis, type and location of meniscal injury; descriptive statistics and Cohen Kappa for concordance were used. Results: There were 29 patients, 23 (79.3%) men and 6 (20.7%) women, mean age 39.04 (15-50) ± 13.19 years; right side was affected in 69% and left in 31%; 19% had not meniscal lesion, 17.2% had injury in anterior horn, 10.3% in posterior horn and 6.9% in the body. The concordance between preoperative and artroscopic diagnosis was: Kappa 0.2; intraboservador was Kappa 1.0; between suspected meniscal injury and arthroscopic findings was: Kappa 0.2. Conclusions: The concordance between the clinical-radiological and arthroscopic diagnosis in patients with ACL injuries and meniscal injury associated is low, which has to be considered in the initial review and the arthroscopic treatment of patients.

On-chip lysis of mammalian cells through a handheld corona device.

On-chip lysis is required in many lab-on-chip applications involving cell studies. In these applications, the complete disruption of the cellular membrane and a high lysis yield is essential. Here, we present a novel approach to lyse cells on-chip through the application of electric discharges from a corona handheld device. The method only requires a microfluidic chip and a low-cost corona device. We demonstrate the effective lysis of BHK and eGFP HCT 116 cells in the sub-second time range using an embedded microelectrode. We also show cell lysis of non-adherent K562 leukemia cells without the use of an electrode in the chip. Cell lysis has been assessed through the use of bright-field microscopy, high-speed imaging and cell-viability fluorescence probes. The experimental results show effective cell lysis without any bubble formation or significant heating. Due to the simplicity of both the components involved and the lysis procedure, this technique offers an inexpensive lysis option with the potential for integration into lab-on-a-chip devices.

[Bandi tibial tubercule osteotomy vs. artrhroscopy lavage in patelo femoral arthritis. 1 year follow-up]. / Adelantamiento rotuliano tipo Bandi versus limpieza articular artroscópica para el manejo de la artrosis patelofemoral. Seguimiento a un año.

INTRODUCTION: Osteoarthritis is a degenerative joint disease that modifies the mechanical and biological properties of articular cartilage and subchondral bone, treatment is aimed at relieving pain, maintain joint and reduce disease progression function. The aim of this paper is to compare the surgical outcomes of the arthroscopic articular cleaning and Bandi procedure by using the WOMAC scale. METHODS: Cross-sectional study, functional outcome of treatment of patellofemoral ostheoarthritis by arthroscopic articular cleaning and Bandi procedure are compared. Variables were gender, age, affected side, surgical technique and preoperative and 12 months follow up WOMAC evaluation. We used descriptive statistics and t-test for mean difference in WOMAC between both groups of patients. RESULTS: n = 37 patients, the mean age was 53.48 (28-82), ± 12.55 years; 11 (29.7%) males and 26 (70.3%) women, the affected side: 19 (51.35%) right and 18 (48.65%) left. SURGICAL TECHNIQUE: 45.9% arthroscopic articular cleaning and 54.1% Bandi procedure. Patients operated by both technics: Bandi and arthroscopic articular cleaning had improvement in pain, stiffness and physical function (p = 0.00); comparison of global WOMAC score for both techniques a year after showed no statistically significant differences (p = 0.78). CONCLUSION: Both techniques (Bandi and arthroscopic articular cleaning) offer good results at 365 days of surgery, however patients managed by arthroscopic articular cleaning have less pain compared with Bandi procedure.

INTRODUCCIÓN: La osteoartritis (OA) es una artropatía degenerativa que modifica las propiedades mecánicas y biológicas, del cartílago articular y del hueso subcondral, su tratamiento va encaminado hacia el alivio del dolor, mantener la función articular y reducir la progresión de la enfermedad. El objetivo de este trabajo es comparar los resultados quirúrgicos de la limpieza articular artroscópica y adelantamiento rotuliano utilizando la escala WOMAC. METODOLOGÍA: Estudio transversal en el que se compara el resultado funcional del tratamiento de la OA patelofemoral en pacientes operados por limpieza articular artroscópica y pacientes operados por adelantamiento rotuliano con técnica de Bandi. Las variables fueron, género, edad, lado afectado, técnica quirúrgica e índice de WOMAC prequirúrgico y a los 12 meses de seguimiento. Utilizamos estadística descriptiva así como t de Student para la diferencia de promedios de WOMAC entre ambos grupos de pacientes. RESULTADOS: n = 37 pacientes, la edad promedio fue 53.48 años (28-82), ± 12.55, el género 11 (29.7%) hombres y 26 (70.3%) mujeres, el lado afectado: 19 (51.35%) derecho y 18 (48.65%) izquierdo. Técnica quirúrgica: 45.9% artroscópico y 54.1% con técnica de Bandi. Los pacientes operados mediante Bandi y adelantamiento rotuliano tuvieron mejoría del dolor, rigidez articular y de la función física (p = 0.00); la comparación del puntaje global de WOMAC para ambas técnicas al año no mostró diferencias estadísticamente significativas (p = 0.78). CONCLUSIÓN: Ambas técnicas (Bandi y limpieza artroscópica) ofrecen buenos resultados a los 365 días de operados, sin embargo, los pacientes manejados por limpieza artroscópica presentan menor dolor comparados con los de adelantamiento rotuliano tipo Bandi.

[Concordance between preoperatory diagnosis and arthroscopy findings of meniscal lesions associated to anterior cruciate ligament injury]. / Estudio del nivel de concordancia entre los diagnósticos prequirúrgico y artroscópico de lesiones meniscales asociadas a lesiones del ligamento cruzado anterior.

INTRODUCTION: Ligament injuries of the knee joint are common during the second and third decades of life, clinical and radiological diagnosis presents difficulties since the surgical findings may differ significantly. The objective is to determine correlation between clinical-radiologic and arthroscopic diagnosis in patients with injury of the anterior cruciate ligament (ACL) and meniscal lesions. MATERIAL AND METHODS: Cross-sectional study held in 29 patients with ACL injury associated to meniscal lesions treated arthroscopically. Variables were age, gender, affected side, preoperative and postoperative diagnosis, type and location of meniscal injury; descriptive statistics and Cohen Kappa for concordance were used. RESULTS: There were 29 patients, 23 (79.3%) men and 6 (20.7%) women, mean age 39.04 (15-50) ± 13.19 years; right side was affected in 69% and left in 31%; 19% had not meniscal lesion, 17.2% had injury in anterior horn, 10.3% in posterior horn and 6.9% in the body. The concordance between preoperative and artroscopic diagnosis was: Kappa 0.2; intraboservador was Kappa 1.0; between suspected meniscal injury and arthroscopic findings was: Kappa 0.2. CONCLUSIONS: The concordance between the clinical-radiological and arthroscopic diagnosis in patients with ACL injuries and meniscal injury associated is low, which has to be considered in the initial review and the arthroscopic treatment of patients.

INTRODUCCIÓN: Las lesiones ligamentarias de la rodilla son comunes durante la segunda y tercera décadas de vida, su diagnóstico clínico es difícil ya que puede diferir con el diagnóstico definitivo. El objetivo es determinar la concordancia entre el diagnóstico preoperatorio-diagnóstico postoperatorio y entre la lesión meniscal sospechada-lesión meniscal encontrada, en pacientes con lesión del ligamento cruzado anterior. MATERIAL Y MÉTODOS: Estudio transversal. En 29 pacientes con lesión del ligamento cruzado anterior a los cuales se realizó artroscopía. Las variables fueron edad, género, lado afectado, diagnóstico preoperatorio, diagnóstico postoperatorio, lesión meniscal sospechada, lesión meniscal encontrada. La estadística utilizada fue descriptiva, para la concordancia se usó índice de Kappa de Cohen. RESULTADOS: Fueron 29 pacientes, 23 (79.3%) hombres y 6 (20.7%) mujeres, la edad promedio: 39.04 (15-50) ± 13.19 años, lado afectado derecho 69% e izquierdo 31%; el diagnóstico preoperatorio en 22 (75%) pacientes fue LLCA aislada, LLCA + menisco medial 6 (20.7%), LLCA + menisco lateral 1 (3.4%) y el diagnóstico artroscópico fue en 20 (68.96%) sin lesión meniscal, 7 (24.1%) lesión en menisco medial, 2 (6.9%) en menisco lateral, con una concordancia baja (Kappa 0.2), la concordancia diagnóstica preoperatoria intraobservador fue perfecta (Kappa 1.0); y la concordancia entre el diagnóstico de la lesión meniscal preoperatoria y de la lesión meniscal artroscópica fue baja (Kappa 0.2). CONCLUSIONES: La concordancia entre el diagnóstico clínico-radiológico y el diagnóstico artroscópico en lesiones del LCA con asociación de lesión meniscal es baja, lo cual se tiene que tener en cuenta en la realización del diagnóstico inicial y en el tratamiento artroscópico de los pacientes.

Mechanical alloying of biocompatible Co-28Cr-6Mo alloy.

We report on an alternative route for the synthesis of crystalline Co-28Cr-6Mo alloy, which could be used for surgical implants. Co, Cr and Mo elemental powders, mixed in an adequate weight relation according to ISO Standard 58342-4 (ISO, 1996), were used for the mechanical alloying (MA) of nano-structured Co-alloy. The process was carried out at room temperature in a shaker mixer mill using hardened steel balls and vials as milling media, with a 1:8 ball:powder weight ratio. Crystalline structure characterization of milled powders was carried out by X-ray diffraction in order to analyze the phase transformations as a function of milling time. The aim of this work was to evaluate the alloying mechanism involved in the mechanical alloying of Co-28Cr-6Mo alloy. The evolution of the phase transformations with milling time is reported for each mixture. Results showed that the resultant alloy is a Co-alpha solid solution, successfully obtained by mechanical alloying after a total of 10 h of milling time: first Cr and Mo are mechanically prealloyed for 7 h, and then Co is mixed in for 3 h. In addition, different methods of premixing were studied. The particle size of the powders is reduced with increasing milling time, reaching about 5 mum at 10 h; a longer time promotes the formation of aggregates. The morphology and crystal structure of milled powders as a function of milling time were analyzed by scanning electron microscopy and XR diffraction.

Insuficiencia renal secundaria a litiasis urinaria en niños / Renal failure related to urolithiasis in children

Introducción. Debido a que la litiasis urinaria (LU) es endémica en Yucatán, es deseable conocer la prevalencia, cuadro clínico y alteraciones metabólicas de la insuficiencia renal (IR) secundaria a LU en niños. Material y métodos. Se registraron en forma prospectiva, pacientes con edad menor o igual a 15 años y diagnóstico de IR, ingresados de marzo de 2001 a febrero de 2006. Se seleccionaron los casos asociados a LU. Se registró la edad, sexo, condiciones de ingreso, localización de los litos, tratamiento médico y quirúrgico, complicaciones y evolución; aquéllos en los que revirtió la IR se les efectuaron pruebas metabólicas, al recuperarse la función renal. Resultados. Se captaron 104 pacientes con IR, en 13 se observó la asociación de IR con LU (8 mujeres y 5 hombres). La edad osciló entre 8 meses y 12 años; 10 pacientes fueron menores a 3 años. El signo predominante (9/13) fue anuria. Todos tuvieron litos múltiples. Diez pacientes sufrían algún grado de desnutrición. Un caso tuvo hipouricemia e hipouricosuria, 1 con hiperuricosuria (HUU) e hipercalciuria, 8 con HUU, en 3 no se pudo determinar la causa metabólica de la LU. Dos casos requirieron diálisis; 2, instalación de sondas de nefrostomía. Todos requirieron litotomía. Diez evolucionaron en forma satisfactoria, 2 con IR crónica y 1 falleció por urosepsis a pocas horas de su ingreso a urgencias. Conclusiones. La LU puede causar IR en niños y eventualmente llevar a la muerte. La HUU es la alteración metabólica predominante.

Introduction. Because urolithiasis (UL) in an endemic disease in the Yucatan peninsula, we carried out a prospective to study over a 5 year period to determine the prevalence, clinical course and metabolic disturbances of renal failure (RF) secondary to UL in children admitted to our institution. Material and methods. Patients 15 years old and younger, diagnosed with RF, and hospitalized from March 2001 to February 2006, were prospectively examined. Cases associated to UL were selected. Age, sex, hospitalization conditions, litho locus, medical and surgical treatment, complications, and evolution, were registered. Metabolic tests were performed in those in whom RF reverted, posterior to the recovery of renal function. Results. One hundred four patients with RF were detected; 13 cases (8 females and 5 males) had RF and UL. Age was between 8 months and 12 years old and 10 patients were registered to be less than 3 years old. Anuria was the principal clinical data. Every case had multiple stones. Some undernourishment degree was diagnosed in 10 patients. Hypouricemia and hypouricosuria were present in one case whereas hyperuricosuria and hypercalciuria were present in another; hyperuricosuria was found in 8 cases and the metabolic cause for UL in 3 cases could not be identified. Dialysis was required in 2 cases and nephrostomy probes were used in 2 more cases. All cases needed lithotomy. A satisfactory evolution was achieved in 10 patients and chronic RF developed in 2; one patient died due to urosepsis after few hours of been hospitalized in the emergency room. Conclusions. RF in children can be caused by UL and in some cases irreversible damage and even death can occur. Hyperuricosuria was the predominant metabolic alteration.

Hydrodynamic effects of the partial opening of a trileaflet valve.

Manufacturing process of medical grade silicon rubber trileaflet valves for VADs could propitiate important leaflet thickness variations which could result in partial opening of the valve and affect its hydrodynamic performance. The leaflets of a total of 10 valves were measured to assess its thickness variability. Two experiments were performed to asses the impact of the leaflets thickness variation under hypothetical situations. The first experiment was divided into three hypothetical cases. In each case either none, one or two leaflets of different valves were mechanically blocked, resembling possible critical working circumstances. The second experiment was intended to know how the variation on the leaflets thickness affects the hydrodynamic performance of the valves. The results demonstrated a significant variation on the leaflets thickness was found. As for the first experiment, a small variation on the hydrodynamic performance was found above 4 L/min flow rates and a slightly higher energy loss was found in one of the cases. As for the second experiment, the results showed that the variation of the leaflet thickness does not affect the general hydrodynamic performance of the valves. No relationship between the thickness variability and the hydrostatic performance of the valves was found.

Structural performance and hydrodynamic resistance of a new silicone auricular cannula tip.

Development of a new generation pneumatic of Ventricular Assist Device (VAD) required the design of cannulae to improve its optimal performance. In this case, a relevant restrictive design parameter was the material of the cannulae. Silicone was the best choice in a hemocompatible focus, but this is a material with very low stiffness. If the material is flexible, the most important parameter that affects either the structural performance or the hydrodynamic resistance is the amount of side holes on the cannulae tip, known as the effective drainage area. In order to obtain an estimation of the structural performance and of the hydrodynamic resistance, a study based on two independent analysis is needed: the structural and the in vitro drop pressure analysis. Structural analyses based on computer simulations were made in order to estimate the bending behavior of four silicone prototypes of cannulae tips. On the other hand, experiments under hydrostatic conditions were made to test and compare the pressure loss and flow rate relationship. A cannula tip with six side holes showed good hydrostatic performance, having almost the same as the one with nine side holes. Plus, it presented and a satisfactory structural behavior. This study assisted the design process of an auricular silicone cannula, recommending the use of cannulae with six side holes for a specific VAD.

Experimental and Computer-Based Performance Analysis of Two Elastomer VAD Valve Designs.

The development of a new generation pneumatic Ventricular Assist Device (VAD) required the design of valves for the optimization of its performance. Experiments and computer-based simulations under hydrostatic conditions were analyzed in order to test and compare two low-cost elastomer valve designs. The trileaflet valve design showed a superior hydrostatic performance, having almost a ratio of 1:2 hydraulic resistance than the bileaflet valve design in agreement with both, the experimental and the simulation evidences. This study will address the use of a trileaflet valve designs in the future VAD redesign.

Hemodynamic performance in-vivo of a new ventricular assist device.

Nowadays, circulatory support has become a common practice in medicine and a standard in the treatments of Cardio Vascular Disease (CVD). A new Pneumatic Ventricular Assist Device (VAD) has been developed in México City. This paper shows the first results of acute in-vivo trials, intended to verify the new system for providing physiological flows and pressures. Two VADs were implanted to as right (RVAD), left (LVAD) support in a 65 kg pig. The support time was 20 minutes with RVAD, 20 minutes with LVAD and 20 minutes with Biventricular (BiVAD). The VAD proved its capability to maintain physiological parameters during the support time. We are satisfied with the results of this trial, and we believe this study will ascertain the first step on the next phase of invivo trials.

Mild perioperative hypothermia and the risk of wound infection.

BACKGROUND: Bacterial destruction caused by free radicals, which are synthesized by neutrophils in the presence of oxygen, depends on adequate tissue perfusion. Mild perioperative hypothermia causes vasoconstriction, reducing nutrient and oxygen supply to wounds and increasing frequency of surgical wound infection. However, the causal role of hypothermia in surgical wound infection is the subject of controversy. The present work proposes the hypothesis that mild perioperative hypothermia is associated with infection of the surgical wound. METHODS: A prospective cohort of 290 surgical patients was studied in a second-level hospital; 261 (90%) of the patients concluded the follow-up. The relationship of hypothermia and of other confounding factors, such as diabetes mellitus, antibiotic treatment, and wound drains with infection outcome was evaluated. One physician, blinded to patient hypothermia, gathered the data. Surgical wound infection was defined as the surgeon's diagnosis with positive culture. RESULTS: Twenty subjects (7.6%) showed infection of surgical wound; 18 (11.5%) of 156 hypothermics and two (2%) 105 normothermics (p = 0.004). Hypothermia proved to be a significant independent risk of infection with relative risk of 6.3 (p = 0.01). CONCLUSIONS: Mild perioperative hypothermia is associated with infection of the surgical wound and its prevention is therefore justified.

Comparative in vitro activity of moxifloxacin by E-test against Streptococcus pyogenes.

Macrolides are currently used to treat Streptococcus pyogenes infections where allergy or resistance prevents the use of penicillin. However, growing macrolide resistance is now seen worldwide, with rates of 5%-40% being reported. In this context it is therefore important to have other therapeutic options. The aim of this study was to ascertain the potential role of moxifloxacin, a third-generation fluoroquinolone, in the treatment of infections caused by group A S. pyogenes. The antimicrobial susceptibilities of S. pyogenes isolated from 197 adult patients with pharyngotonsillitis were analyzed by the E-test. Twelve percent of the isolates were resistant to macrolides, and 5% showed diminished susceptibility toward penicillin; none of the strains were resistant to cefotaxime or to moxifloxacin (90% minimum inhibitory concentration, 0.25 microg/mL). Therefore, moxifloxacin may be a therapeutic option in the management of S. pyogenes infections when penicillin cannot be used or when macrolide resistance may be a local issue. Clinical studies of moxifloxacin in pharyngotonsillitis are warranted.

Premenstrual symptomatology: role of prior knowledge about premenstrual syndrome.

OBJECTIVE: Most women have some premenstrual symptoms that may be influenced by diverse environmental factors. The aim of this study was to determine the influence of knowledge about premenstrual syndrome (PMS) in the reports of women and their symptoms. METHOD: We studied 86 healthy Mexican women whose highest level of education was sixth grade. Participants were assigned to one of two groups. The experimental group watched a videotape describing PMS and its negative consequences in daily life. The control group watched a videotape describing the menstrual cycle. The Menstrual Distress Questionnaire was administered to all women during the first week after menstruation, after which they were shown their designated videotape, and the questionnaire was administered again after the next menstruation. RESULTS: In the control group, there were no significant differences in premenstrual symptoms reported both before and after the women watched the videotape. However, women in the experimental group reported more severe premenstrual symptoms after watching the videotape. CONCLUSIONS: These results suggest that after observing the videotape, women's expectancies of negative symptoms in the premenstrual phase increased. Thus, the symptoms reported by these women were enhanced.

[Measles in the young adult. Clinical features of 201 cases]. / Sarampión en el adulto joven. Características clínicas en 201 casos.

The clinical and laboratory characteristics of 201 cases of measles and its associations with complications were analyzed during an outbreak of this disease in Mexico City. The complications were hepatitis (45%), bacterial pneumonia (17%), oral candidiasis (13%), upper gastrointestinal tract hemorrhage (13%), epistaxis (8%), encephalitis (4%), subcutaneous emphysema (2%), and hypocalcemic tetany (1%). In a subgroup of 20 consecutive patients hypocalcemia was found in 14 cases (70%), associated with high levels of calcitonin in three cases. An increased lactate dehydrogenase (LDH) was observed in 83% of the patients, showing a significant association with the occurrence of complications (p = 0.04) especially in the patients with values of LDH above 750 IU/mL (odds ratio of 6.4). Two patients died (1% mortality). The young patients with measles can develop serious complications, and an increased level of LDH may be a prognostic indicative of these complications.

Fiebre tifoidea: diagnostico de laboratorio, fagotipos y resistencia al cloranfenicol (1972-1982).Analisis de dos mil casos comprobados bacteriologicamente. / Typhoid fever: laboratorial diagnosis, phace types and cloramphenicol resistance (1972-1982).Analysis of 2,00 cases bacteriologically confirmed

Se analizaron dos mil casos de fiebre tifoidea cuyo diagnostico se habia podido confirmar por el aislamiento de Salmonella typhi en diferentes muestras.El cultivo de medula osea es el metodo diagnostico de eleccion, ya que los resultados obtenidos son mejores que con otras muestras, y la tasa de resultados positivos no disminuye con el tiempo de evolucion de la enfermedad, como ocurre con otros cultivos. En terminos de resistencia a los antibioticos y fagotipos, se analizaron un total de 2,685 cepas aisladas en el lapso de 1972 a 1982. A excepcion del anos 1975, la resistencia al cloranfenicol ha venido declinando y, aunque ahora la mayoria de las cepas son sensibles al cloranfenicol (94.4 por ciento en 1982), el fagotipo Vi degradado es aun el predominante