Manejo del síndrome de transfusión feto fetal en pandemia COVID-19: reporte de caso

El síndrome de transfusión feto-fetal (STFF) es una complicación propia de los embarazos gemelares monocoriales, con mortalidad perinatal del 80 a 100%. Ocurre por un desequilibrio en el flujo sanguíneo placentario entre ambos gemelos. El diagnóstico se basa en la discordancia del líquido amniótico y luego se clasifica en estadios según los criterios de Quintero. El tratamiento principal es la fetoscopia y fotoablación con energía láser (FFL) de las anastomosis placentarias. Presentamos un caso de gestación gemelar monocorial biamniótica tratado con FFL en plena cuarentena e inmovilización de la pandemia COVID-19 en Perú, que incluyó diagnóstico oportuno y referencia rápida para recibir el tratamiento especializado.

The twin-to-twin transfusion syndrome (TTTS) is a potentially lethal complication that can occur in monochorionic twin pregnancies due to an imbalance in placental blood flow. Diagnosis is based on amniotic fluid discordance and classified using the Quintero staging system. The primary treatment is fetoscopic laser photocoagulation (FLP) of placental anastomoses. A successful case of FLP treatment in a monochorionic diamniotic twin pregnancy with TTTS during COVID-19 pandemic in Peru is presented.

Dynamic Nanocellulose Networks for Thermoset-like yet Recyclable Plastics with a High Melt Stiffness and Creep Resistance.

Many polymers, including polyethylene, feature a relatively low melting point and hence must be cross-linked to make them viable for applications that demand a high stiffness and creep resistance at elevated temperatures. The resulting thermoset plastics cannot be recycled, and therefore alternative materials with a reconfigurable internal network structure are in high demand. Here, we establish that such a thermoset-like yet recyclable material can be realized through the addition of a nanocellulose reinforcing agent. A network consisting of cellulose nanocrystals, nano- or microfibrils imparts many of the characteristics that are usually achieved through chemical cross-linking. For instance, the addition of only 7.5 wt % of either nanocellulose material significantly enhances the melt stiffness of an otherwise molten ethylene-acrylate copolymer by at least 1 order of magnitude. At the same time, the nanocellulose network reduces the melt creep elongation to less than 10%, whereas the neat molten matrix would rupture. At high shear rates, however, the molten composites do not display a significantly higher viscosity than the copolymer matrix, and therefore retain the processability of a thermoplastic material. Repeated re-extrusion at 140 °C does not compromise the thermomechanical properties, which indicates a high degree of recyclability. The versatility of dynamic nanocellulose networks is illustrated by 3D printing of a cellulose composite, where the high melt stiffness improves the printability of the resin.

Tratamiento con presión positiva de la Apnea Obstructiva del Sueño. Posición de la Asociación Argentina de Medicina Respiratoria / Treatment of Obstructive Sleep Apnea with Positive Pressure. Position of the Argentinian Association of Respiratory Medicine

La Sección de Sueño, Oxigenoterapia y Otros Tratamientos Crónicos Domiciliarios, de la Asociación Argentina de Medicina Respiratoria (AAMR) se planteó desarrollar en nuestro país un documento formal que exponga la base científica y costo económica de la cobertura del tratamiento del síndrome de apneas e hipopneas obstructivas durante el sueño (SAHOS). Esta iniciativa se basó en la necesidad de analizar la visión de expertos locales que se desempeñan en la realidad coyuntural cotidiana de nuestro país, para elaborar un documento informativo para miembros del equipo de salud. A su vez, exhorta a los diferentes actores del sistema a determinar pautas claras que sirvan de referencia para la generación de políticas públicas. La agenda se inició en septiembre de 2018 en un grupo de redacción. Luego, revisores de cinco provincias argentinas efectuaron una extensa valoración de la evidencia publicada. Para la edición final se realizó una reunión presencial de discusión y generación de consenso. Se plantearon como objetivos; actualizar la base científica que define al SAHOS como problema de salud de proporciones epidémicas con consecuencias demostrables en la salud, analizar los datos de costo-efectividad del tratamiento con CPAP para las formas moderadas a severas y leves con síntomas y unificar conceptos en relación con la calidad mínima necesaria en los tratamientos que se ofrecen. Finalmente, se analiza la situación en la Argentina sobre la base a datos publicados y se presenta una propuesta de mejora en tres niveles: social y económico, logístico-administrativo y clínico

The Sleep, Oxygen Therapy and Other Home Chronic Treatments Section of the Argentinian Association of Respiratory Medicine (AAMR, for its acronym in Spanish) proposed the development in our country of a formal document exposing the scientific and cost-economical foundation of the coverage for the treatment of obstructive sleep apnea and hypopnea syndrome (OSAHS). This initiative was based on the need to analyze the vision of local experts who work in the daily current reality of our country, in order to create an informative document for the members of the medical staff. In turn, it encourages the different members of the system to determine clear guidelines that could be used as reference for generating public policies. The agenda began in September, 2018 within a writing staff. Then, editors from five Argentinian provinces made a thorough assessment of published evidence. For the final edition, a face-to-face meeting was arranged to discuss and reach a consensus. The suggested objectives were: to update the scientific base that defines the OSAHS as a health problem of epidemic proportions with health consequences; to analyze cost-efficacy data of CPAP treatment for moderate to severe and mild-with-symptoms forms of the disease and to unify concepts in relation to the minimum necessary quality of treatments to be offered. Finally, the situation in Argentina is analyzed basing on published data, and a proposal is presented for improvement in three levels: social and economic, logistic-administrative and clinical.

Lignin-Retaining Transparent Wood.

Optically transparent wood, combining optical and mechanical performance, is an emerging new material for light-transmitting structures in buildings with the aim of reducing energy consumption. One of the main obstacles for transparent wood fabrication is delignification, where around 30 wt % of wood tissue is removed to reduce light absorption and refractive index mismatch. This step is time consuming and not environmentally benign. Moreover, lignin removal weakens the wood structure, limiting the fabrication of large structures. A green and industrially feasible method has now been developed to prepare transparent wood. Up to 80 wt % of lignin is preserved, leading to a stronger wood template compared to the delignified alternative. After polymer infiltration, a high-lignin-content transparent wood with transmittance of 83 %, haze of 75 %, thermal conductivity of 0.23 W mK-1 , and work-tofracture of 1.2 MJ m-3 (a magnitude higher than glass) was obtained. This transparent wood preparation method is efficient and applicable to various wood species. The transparent wood obtained shows potential for application in energy-saving buildings.

Strain-induced stiffening of nanocellulose-reinforced poly(vinyl alcohol) hydrogels mimicking collagenous soft tissues.

Soft tissues possess remarkable mechanical strength for their high water content, which is hard to mimic in synthetic materials. Here, we demonstrate how strain-induced stiffening in hydrogels plays a major role in mimicking the mechanical properties of collagenous soft tissues. In particular, nanocellulose reinforced polyvinyl alcohol (PVA) hydrogels of exceptionally high water content (90-93 wt%) are shown to exhibit collagen-like mechanical behavior typical for soft tissues. High water content and co-existence of both soft and rigid domains in the gel network are the main factors responsible for strain-induced stiffening. This observed effect due to the alignment of rigid components of the hydrogel is simulated through modeling and visualized through strain-induced birefringence experiments. Design parameters such as nanocellulose aspect ratio and solvent composition are also shown to be important to control the mechanical properties. In addition, owing to their transparency (90-95% at 550 nm) and hyperelastic properties (250-350% strain), the described hydrogels are promising materials for biomedical applications, especially in ophthalmology.

Poly(vinyl alcohol) Hydrogels Reinforced with Nanocellulose for Ophthalmic Applications: General Characteristics and Optical Properties.

Globally, uncorrected refractive errors are one of the main causes of visual impairment, and contact lenses form an important part of modern day eye care and culture. Several hydrogels with varying physicochemical properties are in use to manufacture soft contact lenses. Hydrogels are generally too soft and reinforcement with appropriate materials is desirable to achieve high water content without compromising mechanical properties. In this study, we have developed a highly transparent macroporous hydrogel with water content >90%, by combining poly(vinyl alcohol) with nanocellulose. Furthermore, the results show that the composite hydrogel has refractive index close to that of water and very good UV-blocking properties.

The effect of oligo(trimethylene carbonate) addition on the stiffness of acrylic bone cement.

With the increasing elderly population an increase in the number of bony fractures associated to age-related diseases such as osteoporosis also follows. The relatively high stiffness of the acrylic bone cements used in these patients has been suggested to give raise to a suboptimal load distribution surrounding the cement in vivo, and hence contribute to clinical complications, such as additional fractures. The aim of this study was to develop a low-modulus bone cement, based on currently used, commercially available poly(methyl methacrylate) (PMMA) cements for vertebroplasty. To this end, acrylate end-functionalized oligo(trimethylene carbonate) (oTMC) was incorporated into the cements, and the resulting compressive mechanical properties were evaluated, as well as the cytotoxic and handling properties of selected formulations. Sixteen wt%oTMC was needed in the vertebroplastic cement Osteopal V to achieve an elastic modulus of 1063 MPa (SD 74), which gave a corresponding compressive strength of 46.1 MPa (SD 1.9). Cement extracts taken at 1 and 12 hours gave a reduced MG-63 cell viability in most cases, while extracts taken at 24 hours had no significant effect on cell behavior. The modification also gave an increase in setting time, from 14.7 min (SD 1.7) to 18.0 min (SD 0.9), and a decrease in maximum polymerization temperature, from 41.5°C (SD 3.4) to 30.7°C (SD 1.4). While further evaluation of other relevant properties, such as injectability and in vivo biocompatibility, remains to be done, the results presented herein are promising in terms of approaching clinically applicable bone cements with a lower stiffness.

Parametric elastic analysis of coupled helical coils for tubular implant applications: experimental characterization and numerical analysis.

Coupled helical coils show promising mechanical behavior to be used as tubular organ constructs, e.g., in trachea or urethra. They are potentially easy to manufacture by filament winding of biocompatible and resorbable polymers, and could be tailored for suitable mechanical properties. In this study, coupled helical coils were manufactured by filament winding of melt-extruded polycaprolactone, which was reported to demonstrate desired in vivo degradation speed matching tissue regeneration rate. The tensile and bending stiffness was characterized for a set of couple helical coils with different geometric designs, with right-handed and left-handed polymer helices fused together in joints where the filaments cross. The Young's modulus of unidirectional polycaprolactone filaments was characterized, and used as input together with the structural parameters of the coupled coils in finite element simulations of tensile loading and three-point bending of the coils. A favorable comparison of the numerical and experimental results was found, which paves way for use of the proposed numerical approach in stiffness design under reversible elastic conditions of filament wound tubular constructs.

Hyaluronic acid-based hydrogel enhances neuronal survival in spinal cord slice cultures from postnatal mice.

Numerous biomaterials based on extracellular matrix-components have been developed. It was our aim to investigate whether a hyaluronic acid-based hydrogel improves neuronal survival and tissue preservation in organotypic spinal cord slice cultures. Organotypic spinal cord slice cultures were cultured for 4 days in vitro (div), either on hyaluronic acid-based hydrogel (hyaluronic acid-gel group), collagen gel (collagen group), directly on polyethylene terephthalate membrane inserts (control group), or in the presence of soluble hyaluronic acid (soluble hyaluronic acid group). Cultures were immunohistochemically stained against neuronal antigen NeuN and analyzed by confocal laser scanning microscopy. Histochemistry for choline acetyltransferance, glial fibrillary acidic protein, and Griffonia simplicifolia isolectin B4 followed by quantitative analysis was performed to assess motorneurons and different glial populations. Confocal microscopic analysis showed a 4-fold increase in the number of NeuN-positive neurons in the hyaluronic acid-gel group compared to both collagen (p < 0.001) and control groups (p < 0.001). Compared to controls, organotypic spinal cord slice cultures maintained on hyaluronic acid-based hydrogel showed 5.9-fold increased survival of choline acetyltransferance-positive motorneurons (p = 0.008), 2-fold more numerous resting microglial cells in the white matter (p = 0.031), and a 61.4% reduction in the number of activated microglial cells within the grey matter (p = 0.05). Hyaluronic acid-based hydrogel had a shear modulus (G') of ≈1200 Pascals (Pa), which was considerably higher than the ≈25 Pa measured for collagen gel. Soluble hyaluronic acid failed to improve tissue preservation. In conclusion, hyaluronic acid-based hydrogel improves neuronal and - most notably - motorneuron survival in organotypic spinal cord slice cultures and microglial activation is limited. The positive effects of hyaluronic acid-based hydrogel may at least in part be due to its mechanical properties.

Molecular design and evaluation of biodegradable polymers using a statistical approach.

The challenging paradigm of bioresorbable polymers, whether in drug delivery or tissue engineering, states that a fine-tuning of the interplay between polymer properties (e.g., thermal, degradation), and the degree of cell/tissue replacement and remodeling is required. In this paper we describe how changes in the molecular architecture of a series of terpolymers allow for the design of polymers with varying glass transition temperatures and degradation rates. The effect of each component in the terpolymers is quantified via design of experiment (DoE) analysis. A linear relationship between terpolymer components and resulting Tg (ranging from 34 to 86 °C) was demonstrated. These findings were further supported with mass-per-flexible-bond analysis. The effect of terpolymer composition on the in vitro degradation of these polymers revealed molecular weight loss ranging from 20 to 60 % within the first 24 h. DoE modeling further illustrated the linear (but reciprocal) relationship between structure elements and degradation for these polymers. Thus, we describe a simple technique to provide insight into the structure property relationship of degradable polymers, specifically applied using a new family of tyrosine-derived polycarbonates, allowing for optimal design of materials for specific applications.

One-stage tissue engineering of bladder wall patches for an easy-to-use approach at the surgical table.

We present a method for producing a cell-scaffold hybrid construct at the bedside. The construct is composed of plastic-compressed collagen together with a poly(ɛ-caprolactone) (PCL)-knitted mesh that yields an integrated, natural-synthetic scaffold. This construct was evaluated by seeding of minced bladder mucosa, followed by proliferation in vitro. High mechanical strength in combination with a biological environment suitable for tissue growth was achieved through the creation of a hybrid construct that showed an increased tensile strength (17.9 ± 2.6 MPa) when compared to plastic-compressed collagen (0.6 ± 0.12 MPa). Intimate contact between the collagen and the PCL fabric was required to ensure integrity without delamination of the construct. This contact was achieved by surface alkaline hydrolysis of the PCL, followed by adsorption of poly(vinyl) alcohol. The improvement in hydrophilicity of the PCL-knitted mesh was confirmed through water contact angle measurements, and penetration of the collagen into the mesh was evaluated by scanning electron microscopy (SEM). Particles of minced bladder mucosa tissue were seeded onto this scaffold, and the proliferation was followed for 6 weeks in vitro. Results obtained from phase contrast microscopy, SEM, and histological staining indicated that cells migrated from the minced tissue particles and reorganized on the scaffold. Cells were viable and proliferative, with morphological features characteristic of urothelial cells. Proliferation reached the point at which a multilayer with a resemblance to stratified urothelium was achieved. This successful method could potentially be used for in vivo applications in reconstructive urology as an engineered autologous tissue transplant without the requirement for in vitro culture before transplantation.

La salud neonatal en la agenda de los países de Latinoamérica / Neonatal helth in Latinoamerica

Al hacer una revisión somera de la información sobre la mortalidad y morbilidad neonatal se hizo evidente que a pesar de los grandes avances en reducción de la mortalidad infantil, la mortalidad neonatal no ha logrado los mismos progresos y más bien ésta presenta una tendencia al estancamiento. Esta misma tendencia se observa en la evolución de la muerteneonatal en Bolivia como puede observarse en la cuadro # 1. Esto resulta preocupante si se toma encuenta que las muertes neonatales aportan al 60% de la mortalidad infantil y las metas de los objetivos del Milenio plantean una reducción de dos tercios de la mortalidad infantil para el año 2017.

Duodenopancretectomía subtotal en el tratamiento del carcinoma del conducto pancreatico, del coledoco distal y de la ampolla de vater

Duodenopancreatectomy or Whipple resection, is the proper surgical technique and the only difinite treatment that is potentially curative for pancreatic and duodenal carcinoma. Whipple performed thes procedure for the first time in 1935. At that time morbidity and mortality where as high as 40

Colgajo miocutaneo de pectoral mayor

Se describe la utilización del colgajo miocutáneo del pectoral mayor, en tres pacientes, para reconstruír grandes defectos que quedaron despúes de la extirpación de tumores avanzados de cabeza y cuello. Se analiza su anatomía, la técnica del tallado, complicaciones, limitaciones y ventajas. Se trata de un colgajo sumamente vascular que, por la sencillez y seguridad de su técnica, significa un aporte muy confiable dentro de la cirugía reparadora de cabeza y cuello, con el que se logra excelentes resultados.

Colgajo cutaneo frontal pediculado, técnica de Tuca

Se presenta la experiencia adquirida en una nueva técnica del colgajo frontal pediculado, para reparar los tejidos luego de resecciónes oncológicas de cabeza y cuello. Se efectúa el análisis de dos casos, la localización tumoral y los resultados. se analizan las indicaciones de la técnica, ventajas, complicaciones y se expresan las respectivas conclusiones.

Conización bajo anestesia local una buena alternativa

Se presenta un estudio que resume la experiencia obtenida en SOLCA, Quito, de conización cervical practicada con anestésico local, la misma que, en un 23 por ciento fue ejecutada por discordancia entre citología, colposcopia e histopatológico, 29 por ciento porque las biopsias no lograban definir el grado de infiltración tumoral, y 48 por ciento fueron terapéuticas. Este procedimiento reduce morbilidad y principalmente los costos y días de hospitalización.

Cirugía en nódulo tiroideo, revisión de 132 casos: en el Instituto del Cáncer Solca núcleo de Quito

Se estudia 132 pacientes que ingresaron al Instituto del Cáncer SOLCA NUCLEO DE QUITO, con el diagnóstico de Nódulo Tiroideo, que luego fueron intervenidos quirurgicamente. Los tipos anatomo patológicos han sido los siguientes: Bocio: 90 casos; Cáncer Papilar 20; Folicular 11; Anaplásicos: 6; Carcinoma de células de hurthle: 2; Medular: 1; Tiroiditis: 2 casos. Las tres cuartas partes de los pacientes con Bocio presentaron en la Gamagrafía Tiroidea, un Nódulo frio o hipocaptante, cuyo diagnóstico citológico fue efectivo en el 95 por ciento de los casos y la cirugía que se realizó con más frecuencia fue lobectomía más Itsmectomía. De los Carcinomas bien diferenciados, el papilar presentó un 70 por ciento de adenopatías cervicales clinicamente positivas y el tamaño tumoral fue de más de 5 cm. en el 40 por ciento de los papilares y en el 63 de los carcinomas foliculares; la Gamagrafía tiroidea reveló un Nódulo frio o hipocaptante en el 75 por ciento de los casos. el tratamiento quirúrgico efectuado fue la tiroidectomía total más Vaciamiento Radical Cervical.

Linfoma no Hodgkin del esofago

Background. The Hodgkin Lynphonas and not Hodgkin ones sometimes involucrate the mediastinum with some frecuency associate with sistemic disease and even so its rarely that this disorders may appear with symptoms referred to in the anatomic site. The disphagia due to the esophagus in some cases the lymphomas not Hodkin is considered the rare appears as on odd case of the illness. Method: in case of malignant lyphoma is described with presence of the esopahagus in a man 61 years old with progresive disphagia compromisig the esophagus, with 9 months of evolution thoegth the structure of esophagus. Endoscopaly and radiologicall qualyfied as peptic; left supraclaviculary limpth node, esophagus-bronchial fistula and asophagus-mediastinic. He was checked by swallowed barium and endoscopy, as well as, biopsy of ganglios disease, TAC of the torax and accepting Dawson opinion to define primary or secondary lymphoma. Results: the TAC of the torax showed a tumoral process in the 3rd. or inferior section of the esophagus and esophagus-bronchial fistula, as well as, mediastinic-esophagus. The hitopatology of biopsy of supraclavicular ganglio and lasser curvature ganglio of stomach showed: lymphama not Hodgkin of higt grade of malignity limphoblastic type but not convoluting (W.F.). Conclusions the first case of lymphoma not Hodgkin with on affection of the esophagus, primary appearance to dyshagia appears in SOLCA s Hospital in Quito.