Investigations on the Degradation Behavior of Processed FeMnSi-xCu Shape Memory Alloys.

A new functional Fe-30Mn-5Si-xCu (x = 1.5 and 2 wt%) biomaterial was obtained from the levitation induction melting process and evaluated as a biodegradable material. The degradation characteristics were assessed in vitro using immersion tests in simulated body fluid (SBF) at 37 ± 1 °C, evaluating mass loss, pH variation that occurred in the solution, open circuit potential (OCP), linear and cyclic potentiometry (LP and CP), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and nano-FTIR. To obtain plates as samples, the cast materials were thermo-mechanically processed by hot rolling. Dynamic mechanical analysis (DMA) was employed to evaluate the thermal properties of the smart material. Atomic force microscopy (AFM) was used to show the nanometric and microstructural changes during the hot rolling process and DMA solicitations. The type of corrosion identified was generalized corrosion, and over the first 3-5 days, an increase in mass was observed, caused by the compounds formed at the metal-solution interface. The formed compounds were identified mainly as oxides that passed into the immersion liquid. The degradation rate (DR) was obtained as a function of mass loss, sample surface area and immersion duration. The dynamic mechanical behavior and dimensions of the sample were evaluated after 14 days of immersion. The nanocompounds found on the surface after atmospheric corrosion and immersion in SBF were investigated with the Neaspec system using the nano-FTIR technique.

Influence of Dynamic Strain Sweep on the Degradation Behavior of FeMnSi-Ag Shape Memory Alloys.

Iron-based SMAs can be used in the medical field for both their shape memory effect (SME) and biodegradability after a specific period, solving complicated chirurgical problems that are partially now addressed with shape-memory polymers or biodegradable polymers. Iron-based materials with (28-32 wt %) Mn and (4-6 wt %) Si with the addition of 1 and 2 wt % Ag were obtained using levitation induction melting equipment. Addition of silver to the FeMnSi alloy was proposed in order to enhance its antiseptic property. Structural and chemical composition analyses of the newly obtained alloys were performed by X-ray diffraction (confirming the presence of ε phase), scanning electron microscopy (SEM) and energy-dispersive spectroscopy. The corrosion resistance was evaluated through immersion tests and electrolyte pH solution variation. Dynamic mechanical solicitations were performed with amplitude sweep performed on the FeMnSi-1Ag and FeMnSi-2Ag samples, including five deformation cycles at 40 °C, with a frequency of 1 Hz, 5 Hz and 20 Hz. These experiments were meant to simulate the usual behavior of some metallic implants subjected to repetitive mechanical loading. Atomic force microscopy was used to analyze the surface roughness before and after the dynamic mechanical analysis test followed by the characterization of the surface profile change by varying dynamic mechanical stress. Differential scanning calorimetry was performed in order to analyze the thermal behavior of the material in the range of -50-+200 °C. X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) along with Neaspec nano-FTIR experiments were performed to identify and confirm the corrosion compounds (oxides, hydroxides or carbonates) formed on the surface.

Analysis of Degradation Products of Biodegradable ZnMgY Alloy.

Biodegradable metallic materials are increasingly gaining ground in medical applications. Zn-based alloys show a degradation rate between those recorded for Mg-based materials with the fastest degradation rate and Fe-based materials with the slowest degradation rate. From the perspective of medical complications, it is essential to understand the size and nature of the degradation products developed from biodegradable materials, as well as the stage at which these residues are eliminated from the body. This paper presents investigations conducted on the corrosion/degradation products of an experimental material (ZnMgY alloy in cast and homogenized state) after immersion tests in three physiological solutions (Dulbecco's, Ringer's and simulated body fluid (SBF)). Scanning electron microscopy (SEM) was used to highlight the macroscopic and microscopic aspects of corrosion products and their effects on the surface. An X-ray energy dispersive detector (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) provided general information about the compounds based on their non-metallic character. The pH of the electrolyte solution was recorded for 72 h during immersion. The pH variation of the solution confirmed the main reactions proposed for the corrosion of ZnMg. The agglomerations of corrosion products were on the micrometer scale, mainly oxides, hydroxides and carbonates or phosphates. The corrosion effects on the surface were homogeneously spread, with a tendency to connect and form cracks or larger corrosion zones, transforming the pitting corrosion pattern into a generalized one. It was noticed that the alloy's microstructure strongly influences the corrosion characteristics.

In-Vitro Analysis of FeMn-Si Smart Biodegradable Alloy.

Special materials are required in many applications to fulfill specific medical or industrial necessities. Biodegradable metallic materials present many attractive properties, especially mechanical ones correlated with good biocompatibility with vivant bodies. A biodegradable iron-based material was realized through electric arc-melting and induction furnace homogenization. The new chemical composition obtained presented a special property named SME (shape memory effect) based on the martensite transformation. Preliminary results about this special biodegradable material with a new chemical composition were realized for the chemical composition and structural and thermal characterization. Corrosion resistance was evaluated in Ringer's solution through immersion tests for 1, 3, and 7 days, the solution pH was measured in time for 3 days with values for each minute, and electro-corrosion was measured using a potentiostat and a three electrode cell. The mass loss of the samples during immersion and electro-corrosion was evaluated and the surface condition was studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). SME was highlighted with differential scanning calorimetry (DSC). The results confirm the possibility of a memory effect of the materials in the wrought case and a generalized corrosion (Tafel and cyclic potentiometry and EIS) with the formation of iron oxides and a corrosion rate favorable for applications that require a longer implantation period.

Pain Assessment and Management in Pediatric Intensive Care Units Around the World, an International, Multicenter Study.

The adequate assessment and management of pain remains a challenging task in the Pediatric Intensive Care Unit (PICU). Our goal is to describe how pain is assessed and managed in PICUs around the world and to examine how human and material resources impact achievement of this goal. An international multicenter cross-sectional observational study was designed with the participation of 34 PICUs located in urban, suburban, and rural areas of 18 countries. We evaluated how PICUs around the world assessed and managed pain according to the Initiative for Pediatric Palliative Care recommendations, and how human and material resources impacted achievement of this goal. Data was collected for this study from 2016 to 2018 using questionnaires completed by medical doctors and nurses. In this paper, we focus on the indicators related to how pain is managed and assessed. The average achievement of the goal of pain relief across all centers was 72.2% (SD: 21.1). We found a statistically significant trend of more effective pain management scores, routine assessment, proper documentation, and involvement of pain management experts by increasing country income. While there are efforts being made worldwide to improve the knowledge in pain assessment and management, there is a lack of resources to do so appropriately in low-middle-income countries. There is a mismatch between the existing guidelines and policies, which are mainly designed in high income countries, and the resources available in lower resourced environments.

New Zn3Mg-xY Alloys: Characteristics, Microstructural Evolution and Corrosion Behavior.

Zinc biodegradable alloys attracted an increased interest in the last few years in the medical field among Mg and Fe-based materials. Knowing that the Mg element has a strengthening influence on Zn alloys, we analyze the effect of the third element, namely, Y with expected results in mechanical properties improvement. Ternary ZnMgY samples were obtained through induction melting in Argon atmosphere from high purity (Zn, Mg, and Y) materials and MgY (70/30 wt%) master alloys with different percentages of Y and keeping the same percentage of Mg (3 wt%). The corrosion resistance and microhardness of ZnMgY alloys were compared with those of pure Zn and ZnMg binary alloy. Materials were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), linear and cyclic potentiometry, and immersion tests. All samples present generalized corrosion after immersion and electro-corrosion experiments in Dulbecco solution. The experimental results show an increase in microhardness and indentation Young Modulus following the addition of Y. The formation of YZn12 intermetallic phase elements with a more noble potential than pure Zinc is established. A correlation is obtained between the appearance of new Y phases and aggressive galvanic corrosion.

Neuritis óptica recurrente posterior a encefalomielitis diseminada aguda en pediatría. Reporte de un caso / Recurrent optic neuritis after acute disseminated encephalomyelitis in pediatrics. A case report

Abstract: Optic Neuritis (ON) is a condition caused by the inflammation of the optic nerve, causing diminished visual acuity and ocular pain. It is tightly related to Multiple Sclerosis (MS), often being the first demyelinating event. There is a 31% risk of recurrence during the first 10 years after the diagnosis, and 48% of the patients end up being diagnosed with Multiple Sclerosis1. Imaging studies like brain MRI (Magnetic Resonance Imaging) have a critical role in the diagnosis and prognosis of ON, as well as in the recognition of MS.2 The patient is a 11-year-old girl with recurrent ON and past medical history of Acute Disseminated Encephalomyelitis (ADEM) when she was 5 years old. ON diagnosis was based on clinical findings as well as on ophtalmologic, electrophysiologic and imaging studies. The recurrent episodes of ON improved after the use of high dose steroids. Recurrences were observed after titration of the dose, but remission was achieved after adjustment of treatment. During one of the recurrent episodes, blood work was performed to evaluate possible underlying infectious, demyelinating or autoinmmune process. Anti-MOG antibodies were found positive. The patient at the moment is not presenting with any other criteria suggesting MS or Optic Neuromyelitis, but long term follow up is adviced. Key words: Optic neuritis (ON), multiple sclerosis (MS), acute disseminated encephalomyelitis (ADEM), magnetic resonance imaging (MRI), cerebrospinal fluid (CSF), right eye (RE); visual acuity (VA), optic neuromyelitis (ONM)

Manejo del síndrome de transfusión feto fetal en gestaciones gemelares monocoriales / Management of Fetal Fetus Transfusion Syndrome in Monochorionic Twin Gestations

El síndrome de transfusión feto fetal es una complicación grave de las gestaciones gemelares monocoriales. Su etiología se debe a la transfusión crónica de sangre del feto donante, al feto receptor, a través de las anastomosis vasculares entre los territorios placentarios de ambos. El cuadro clínico característico se evidencia en ambos fetos, receptor y donante, lo cual es consecuencia directa de las alteraciones en la volemia que padece cada uno. En el feto receptor se observa un polihidramnios relacionado con la poliuria derivada de un estado de hipervolemia constante, que acaba evolucionando hacia una insuficiencia cardiaca congestiva. En el feto donante el cuadro es inverso, caracterizado por oligoamnios, oliguria, crecimiento intrauterino retardado e hipovolemia, con tasas de mortalidad sin tratamiento de entre el 80-100% de los casos, que varían en función del grado de transfusión. El diagnóstico se basa en el estudio ecográfico exhaustivo de ambos fetos, procurando un diagnóstico precoz y un estadiaje correcto, ya que el pronóstico se verá muy influenciado por la actuación temprana. El tratamiento de elección es la coagulación láser de las anastomosis vasculares por fetoscopia, que se realiza idealmente entre la semana 18 y 26 de embarazo. El pronóstico es variable, en función de la disponibilidad de terapia fetal y de la edad gestacional en el momento del diagnóstico, siendo, en general, de muy mal pronóstico sin tratamiento efectivo(AU)

Twin-twin transfusion syndrome (TTTS) is one of the most serious complications of monochorionic multiple gestations. The etiology is due to a chronic blood transfusion from de donor twin to the recipient twin trough vascular anastomoses between both placenta territories. Main clinical presentation is present in both donor and recipient fetuses, as a direct consequence of a blood volume alteration in each one. The recipient twin shows polyhydramnios related to polyuria resulting from a state of constant fluid overload, finally evolving into congestive heart failure. In the donor twin, the clinical presentation is opposite and shows oligoamnios, oliguria, intrauterine retarded growth and hypovolemia. Untreated mortality rates are between 80-100 % of all cases, which may vary depending on the severity of the transfusion. Diagnoses is based on exhausting ultrasound examination of both fetuses, securing early diagnosis and correct staging, since prognosis will be greatly influenced by early actions. Fetoscopic laser ablation is generally the definitive treatment between 16 and 26 weeks of gestation. The prognosis is variable, depending on the availability of fetal therapy and gestational age at diagnosis. It is generally very poor prognosis without effective treatment(AU)

Manejo del síndrome de transfusión feto fetal en gestaciones gemelares monocoriales / Management of twin-twin transfusion syndrome in monochorionic twin gestations

El síndrome de transfusión feto fetal es una complicación grave de las gestaciones gemelares monocoriales. Su etiología se debe a la transfusión crónica de sangre del feto donante, al feto receptor; a través de las anastomosis vasculares entre los territorios placentarios de ambos. El cuadro clínico característico se evidencia en ambos fetos: receptor y donante, lo cual es consecuencia directa de las alteraciones en la volemia que padece cada uno. En el feto receptor, se observa un polihidramnios relacionado con la poliuria derivada de un estado de hipervolemia constante, que evoluciona hacia una insuficiencia cardiaca congestiva. En el feto donante, el cuadro es inverso; caracterizado por oligoamnios, oliguria, crecimiento intrauterino retardado e hipovolemia, con tasas de mortalidad sin tratamiento de entre 80-100 por ciento de los casos, que varían en función del grado de transfusión. El diagnóstico se basa en el estudio ecográfico exhaustivo de ambos fetos, procurando un diagnóstico precoz y un estadiaje correcto, ya que el pronóstico se verá muy influenciado por la actuación temprana. El tratamiento de elección es la coagulación láser de las anastomosis vasculares por fetoscopia, idealmente entre la semana 18 y 26 de embarazo. El pronóstico es variable, en función de la disponibilidad de terapia fetal y de la edad gestacional en el momento del diagnóstico; al ser, en general, de muy mal pronóstico sin tratamiento efectivo(AU)

Twin-twin transfusion syndrome is one of the most serious complications of monochorionic multiple gestations. Its etiology is due to a chronic blood transfusion from de donor twin to the recipient twin through the vascular anastomoses between the placental territories of both fetuses. The characteristic clinical presentation appears in both donor and recipient fetuses, as a direct consequence of altered volemia in each one. Polyhydramnios related to polyuria resulting from a state of constant hypervolemia is observed in the recipient twin, finally evolving into congestive heart failure. The clinical presentation in the donor twin is reversed and characterized by oligoamnios, oliguria, retarded intrauterine growth and hypovolemia, with untreated mortality rates ranging 80-100 percent of all cases, which may vary depending on the severity of the transfusion. The diagnosis is based on exhaustive echographic examination of both fetuses to make an early diagnosis and correct staging, since the prognosis depends very much on early action. The treatment of choice is fetoscopic laser coagulation of vascular anastomoses between 18 and 26 weeks of gestation. The prognosis is variable, depending on the availability of fetal therapy and the gestational age at diagnosis, being prognosis generally very poor without an effective treatment(AU)

Oral challenge with pasteurized egg white from Gallus domesticus.

BACKGROUND: Since raw egg may cause digestive toxic infections, we assessed whether pasteurized raw egg white is as reliable as fresh raw egg white in the diagnosis of egg allergy. METHODS: Thirty-two egg-allergic children were challenged with both pasteurized and fresh raw egg white. Open challenges were carried out with increasing doses of pasteurized raw egg white and fresh raw egg white administered every 60 min. RESULTS: Eleven children (34.4%) had positive challenges with pasteurized raw egg white. Twenty-one children (65.62%) who tolerated pasteurized raw egg white also had a negative challenge with fresh raw egg white. If the challenge with pasteurized raw egg white resulted positive, the study was stopped. The protein profile and IgE-binding capacity of both pasteurized and fresh egg white were almost identical as observed by SDS-PAGE and IgE immunoblotting. In the IgE immunoblotting-inhibition and ImmunoCAP-inhibition assays, both extracts behaved in a similar way. CONCLUSIONS: We did not find any relevant allergenic differences between fresh and pasteurized egg white. This study supports the use of pasteurized egg white in the diagnosis of allergy to fresh raw egg proteins.