Microfluidic Fabrication of Gadolinium-Doped Hydroxyapatite for Theragnostic Applications.

Among the several possible uses of nanoparticulated systems in biomedicine, their potential as theragnostic agents has received significant interest in recent times. In this work, we have taken advantage of the medical applications of Gadolinium as a contrast agent with the versatility and huge array of possibilities that microfluidics can help to create doped Hydroxyapatite nanoparticles with magnetic properties in an efficient and functional way. First, with the help of Computational Fluid Dynamics (CFD), we performed a complete and precise study of all the elements and phases of our device to guarantee that our microfluidic system worked in the laminar regime and was not affected by the presence of nanoparticles through the flow requisite that is essential to guarantee homogeneous diffusion between the elements or phases in play. Then the obtained biomaterials were physiochemically characterized by means of XRD, FE-SEM, EDX, confocal Raman microscopy, and FT-IR, confirming the successful incorporation of the lanthanide element Gadolinium in part of the Ca (II) binding sites. Finally, the magnetic characterization confirmed the paramagnetic behaviour of the nanoparticles, demonstrating that, with a simple and automatized system, it is possible to obtain advanced nanomaterials that can offer a promising and innovative solution in theragnostic applications.

Semiconductor Quantum Dots as Target Analytes: Properties, Surface Chemistry and Detection.

Since the discovery of Quantum Dots (QDs) by Alexey I. Ekimov in 1981, the interest of researchers in that particular type of nanomaterials (NMs) with unique optical and electrical properties has been increasing year by year. Thus, since 2009, the number of scientific articles published on this topic has not been less than a thousand a year. The increasing use of QDs due to their biomedical, pharmaceutical, biological, photovoltaics or computing applications, as well as many other high-tech uses such as for displays and solid-state lighting (SSL), has given rise to a considerable number of studies about its potential toxicity. However, there are a really low number of reported studies on the detection and quantification of QDs, and these include ICP-MS and electrochemical analysis, which are the most common quantification techniques employed for this purpose. The knowledge of chemical phenomena occurring on the surface of QDs is crucial for understanding the interactions of QDs with species dissolved in the dispersion medium, while it paves the way for a widespread use of chemosensors to facilitate its detection. Keeping in mind both human health and environmental risks of QDs as well as the scarcity of analytical techniques and methodological approaches for their detection, the adaptation of existing techniques and methods used with other NMs appears necessary. In order to provide a multidisciplinary perspective on QD detection, this review focused on three interrelated key aspects of QDs: properties, surface chemistry and detection.

Unraveling the Compositional and Molecular Features Involved in Lysozyme-Benzothiazole Derivative Interactions.

In this work we present a computational analysis together with experimental studies, focusing on the interaction between a benzothiazole (BTS) and lysozyme. Results obtained from isothermal titration calorimetry, UV-vis, and fluorescence were contrasted and complemented with molecular docking and machine learning techniques. The free energy values obtained both experimentally and theoretically showed excellent similarity. Calorimetry, UV-vis, and 3D/2D-lig-plot analysis revealed that the most relevant interactions between BTS and lysozyme are based on a predominance of aromatic, hydrophobic Van der Waals interactions, mainly aromatic edge-to-face (T-shaped) π-π stacking interactions between the benzene ring belonging to the 2-(methylthio)-benzothiazole moiety of BTS and the aromatic amino acid residue TRP108 of the lysozyme receptor. Next, conventional hydrogen bonding interactions contribute to the stability of the BTS-lysozyme coupling complex. In addition, mechanistic approaches performed using elastic network models revealed that the BTS ligand theoretically induces propagation of allosteric signals, suggesting non-physiological conformational flexing in large blocks of lysozyme affecting α-helices. Likewise, the BTS ligand interacts directly with allosteric residues, inducing perturbations in the conformational dynamics expressed as a moderate conformational softening in the α-helices H1, H2, and their corresponding ß-loop in the lysozyme receptor, in contrast to the unbound state of lysozyme.

Application of High Resolution-Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS): determination of trace elements in tea and tisanes.

A new application of HR-CS FAAS (High Resolution-Continuum Source Flame Atomic Absorption Spectrometry) has been developed for the determination of several trace elements (Ca, Co, Cu, Fe, Mn, Ni, Na and Zn) in infusions made from tea, rooibos and tea with seaweed samples. The proposed methods are fast, inexpensive and show good performances: the mean analytical recovery was approximately 100%. The mean limit of detection was 29.4 µg/l, and the mean limit of quantification was 98.0 µg/l (both limits refer to the brewed samples). Due to the matrix effect observed, the standard addition method had to be applied. Preliminary classification (based on metal contents) using chemometric techniques such as PCA (Principal Component Analysis) and CA (Cluster Analysis), was successful for infusions made from rooibos and tea with seaweed, but inconclusive for black and green teas.

Creutzfeldt-Jakob disease surveillance in Argentina, 1997-2008.

BACKGROUND: Epidemiological data on Creutzfeldt-Jakob disease (CJD) from Latin America are limited. We present a comprehensive epidemiological survey on CJD patients in Argentina based on systematic surveillance between 1997 and 2008. METHODS: A CJD Surveillance Referral Center (SRC) was established in Argentina in 1997; previously a Neuropathology Referral Center was used from 1983 to 1996. All suspected cases referred to the SRC were classified using established criteria on the basis of information derived from the following: clinical data form, EEG, MRI (both for central review), cerebrospinal fluid (CSF) for protein 14-3-3 Western blot (WB), autopsy or biopsy material for neuropathology, prion protein (PrP) immunohistochemistry and PrP WB, as well as blood for DNA studies (when brain tissue was not available). RESULTS: Of the 517 patients referred to the SRC between 1997 and 2008, 211 (40.8%) had CJD or other transmissible spongiform encephalopathies (TSEs) (definite or probable). Possible cases totaled 14.5%, while cases with no WHO criteria accounted for 16.4%. Non-CJD cases excluded by biopsy/autopsy or during follow-up corresponded to 28.2% of the 517 referrals. Main differential diagnoses included neurodegenerative diseases such as Alzheimer's disease, frontotemporal dementia, vascular, metabolic or viral encephalopathy, and Hashimoto's disease. Five percent of referred patients ultimately recovered. Eighty-three percent of TSE cases were sporadic CJD; 17% were genetic, mainly E200K (15.6%); the remaining 1.4% included an octarepeat insertion and two Gerstmann-Sträussler-Scheinker cases (P102L). Seventy-four of 100 definite cases had frozen tissue available for molecular subtyping (PrP(Sc)/codon 129). CSF protein 14-3-3 WB sensitivity was 72.3% and specificity was 92.1%. Clinical diagnostic criteria for probable CJD when compared to definite diagnosis by neuropathology showed 71.3% sensitivity, 86.2% specificity, 94.4% positive predictive value and 48% negative predictive value. Country incidence increased over time and reached 0.85 cases per million in 2008, with the highest rate detected in the city of Buenos Aires (1.8). Districts with 6% of the total population have never reported suspected cases. CONCLUSION: In spite of an increase in incidence observed over time, the difference between Buenos Aires city, where the incidence is comparable to that of smaller European countries with higher population density, and the incidence observed in the rest of the country suggests underreporting in nonmetropolitan areas, probably due to a lack of access to specialized medical facilities. CSF WB sensitivity results for protein 14-3-3 were probably linked to the fact that testing was not routinely repeated during the course of the disease, when earlier test results had been negative. The spectrum of molecular CJD subtypes observed did not differ from other countries in Europe. No iatrogenic or variant CJD cases were identified. The sensitivity and negative predictive value of clinical diagnostic criteria for probable CJD (which includes EEG and/or CSF protein 14-3-3 levels) may have been resulted from confirmed cases not meeting probable criteria before autopsy, due to a lack of ancillary tests such as EEG and/or CSF 14-3-3 WB, or because negative tests were not repeated during follow-up.

Epidemiological survey of epilepsy in the special school population in the city of Buenos Aires. A comparison with mainstream schools.

BACKGROUND: Previous studies in special schools have shown a high prevalence of epilepsy, which is strongly associated with cerebral palsy and severe mental retardation. The conditions regulating school placement have also been described in those studies. In the City of Buenos Aires, information is known only for mainstream schools. OBJECTIVE: To determine the prevalence and characteristics of epilepsy in special schools and to compare results with common primary education settings. DESIGN AND METHODS: A cross-sectional study was carried out in special schools in the City of Buenos Aires, by adopting the same definitions, diagnostic criteria and questionnaire as those used in a previous study in the common primary school population. Responses from 1,682 children, aged 6-16 years, residing in the City of Buenos Aires, with mental retardation, visual or hearing impairment, psychiatric disorders and motor disabilities were analyzed. RESULTS: A total of 121 children with epilepsy were detected. Lifetime prevalence was 71.9 per thousand and active prevalence was 64.8 per thousand (22-25 times greater than rates in mainstream schools). Prevalence was highest in girls and generalized seizures prevailed over other seizure types. Ninety-two percent of cases received antiepileptic drugs, 57.9% as a single drug treatment and 85.1% in adequate doses. Only 56% of the children with a diagnosis of epilepsy proved to be true-positive cases, and almost 40% received antiepileptic drugs for nonepileptic disorders. Malformations/degenerative disease were the most common etiology. CONCLUSIONS: Special schools contain clusters of children with epilepsy as a comorbid condition. False high frequency is due to misdiagnoses and unnecessary treatments. These schools are an important target for educational interventions.

Epidemiological survey of epilepsy in the primary school population in Buenos Aires.

BACKGROUND: Most studies carried out in Latin America have shown greater rates of epilepsy and generalized seizures than those observed in developed countries, in spite of lower numbers of patients receiving treatment. To date, studies in Argentina have been insufficient to establish true prevalence. OBJECTIVE: To determine the prevalence of epilepsy in primary school children in Buenos Aires, together with rates of different seizure types, treatments prescribed, diagnoses made and number of inadequate therapies administered, as well as the relationship between epilepsy and learning difficulties. DESIGN AND METHOD: A cross-sectional study was carried out on 10% of the entire primary school population of Buenos Aires through randomized, systematic, representative and conglomerate sampling of public and private school students. A total of 26,270 responses were received (83.1% of the population) to a specially designed questionnaire, with 96.4% sensitivity and 41.5% specificity, respectively. Interviews were conducted in all probable epilepsy cases as well as in a random sample of probable negative ones. RESULTS: Eighty-four children with epilepsy were detected (lifetime prevalence 3.2 per thousand; active prevalence 2.6 per thousand), in whom generalized seizures predominated (57.1%). Ninety-three percent of cases diagnosed were currently under, or had previously received antiepileptic drug (AED) therapy. Almost 1% of the primary school population studied had a prior diagnosis and/or received AED for dysrhythmia or epilepsy. The percentage of grade repeaters in the general population and in children with epilepsy was 8.4 and 26.2%, respectively. CONCLUSIONS: (1) The prevalence of epilepsy in primary school children in Buenos Aires is similar to that reported for developed countries; (2) a slight prevalence for generalized seizures was observed; (3) 93% of cases received AEDs; (4) misdiagnoses and unnecessary treatments exceeded correct diagnoses and adequate therapy, and (5) disease presence and/or treatment were associated with poorer school performance.

Toxoplasmosis / Toxoplasmosis

La toxoplasmosis es una antropozoonosis muy difundida en todas las latitudes, que no respeta raza ni clase social y que aumenta estadísticamente con la edad. Por lo mismo, cada vez se le otorga mayor importancia. Los equívocos y las falsas interpretaciones en torno de esta parasitosis mantenidos en épocas precedentes fueron desvaneciéndose a medida que se desarrolló el juicio crítico frente a afecciones que coinciden o se confunden hartas veces con la toxoplasmosis. Ello coincidió con un mejor conocimiento de las lesiones que es capaz de producir el Toxoplasma gondii y con la existencia de métodos diagnósticos más perfeccionados y exactos. En este libro se aclara el verdadero valor y alcance de la etiología toxoplásmica, sobre todo en el campo de la pediatría prenatal y en el de la oftalmología, y se reúnen los conocimientos dispersos en múltiples publicaciones. (AU)