Low intensity sonosynthesis of iron carbide@iron oxide core-shell nanoparticles.

Here we demonstrate a simple method for the organic sonosynthesis of stable Iron Carbide@Iron Oxide core-shell nanoparticles (ICIONPs) stabilized by oleic acid surface modification. This robust synthesis route is based on the sonochemistry reaction of organometallic precursor like Fe(CO)5 in octanol using low intensity ultrasonic bath. As obtained, nanoparticles diameter sizes were measured around 6.38 nm ±â€¯1.34 with a hydrodynamic diameter around 25 nm and an estimated polydispersity of 0.27. Core-Shell structure of nanoparticles was confirmed using HR-TEM and XPS characterization tools in which a core made up of iron carbide (Fe3C) and a shell of magnetite (γ-Fe2O3) was found. The overall nanoparticle presented ferromagnetic behavior at 4 K by SQUID. With these characteristics, the ICIONPs can be potentially used in various applications such as theranostic agent due to their properties obtained from the iron oxides and iron carbide phases.

Effect of freeze-thawing conditions for preparation of chitosan-poly (vinyl alcohol) hydrogels and drug release studies.

The freezing-thawing is an advantageous method to produce hydrogels without crosslinking agents. In this study chitosan-poly(vinyl alcohol) (CS-PVA) hydrogels were prepared by varying the freezing conditions and composition, which affect the final characteristics of the products. The swelling degree, morphology, porosity, and diflunisal drug loading, as well as the drug release profiles were evaluated. The hydrogel swelling ratio was found to be mainly affected by the CS content, the number of freezing cycles and the temperature. SEM micrographs and porosity data confirm that pore size increases with the chitosan content. However, the use of either lower temperatures or longer freezing times, results in higher porosity and smaller pores. The drug release times of the CS-PVA hydrogels were as long as 30 h, and according to the mathematical fitting, a simple diffusion mechanism dominates the process. Moreover, a mathematical model predicting the hydrogels physical and structural behavior is proposed.

Development and characterization of nanocapsules comprising dodecyltrimethylammonium chloride and κ-carrageenan.

The aim of this work was to develop and characterize a new type of nanocapsules. To this end, a nanoemulsion bearing an oily core (Miglyol 812) was obtained by spontaneous emulsification and stabilized by dodecyl-trimethylammonium chloride (DTAC), a commercial cationic surfactant; this nanoemulsion was coated with proportionally very small amounts of κ-carrageenan (at molar charge ratios of Z ≤ 0.0045) that interact predominantly by an electrostatic mechanism with the positively charged sites at the polar heads of DTAC at the nanoemulsion's surface to harness nanocapsules of average size ~250-330 nm and zeta potential (ζ) ranging from ~+80 to +7 mV. The potential application of the new type of developed nanosystems as drug delivery vehicles has yet to be investigated and fully realized.

Clinical and genetic analysis of a distinct autosomal dominant spinocerebellar ataxia.

OBJECTIVE: To characterize a distinct form of spinocerebellar ataxia (SCA) clinically and genetically. BACKGROUND: The SCAs are a genetically heterogeneous group of neurodegenerative disorders affecting the cerebellum and its connections. The mutations for SCA1, 2, 3, 6, and 7 have been identified and shown to be due to expansion of a CAG repeat in the coding region of these genes. Two additional SCA loci on chromosomes 16 and 11 have been designated SCA4 and SCA5. However, up to 20% of individuals with autosomal dominant forms of ataxias cannot be assigned any of these genotypes, implying the presence of other unidentified genes that may be involved in the development of ataxia. METHODS: We ascertained and clinically characterized a six-generation pedigree segregating an autosomal dominant trait for SCA. We performed direct mutation analysis and linkage analysis for all known SCA loci. RESULTS: The mutation analysis excludes SCA1, 2, 3, 6, and 7, and genetic linkage analysis excludes SCA4 and SCA5 (multipoint location scores < -2 across the candidate region). Clinical analysis of individuals in this family shows that all affected members have dysarthria, gait and limb ataxia, and nystagmus. No individuals have major brainstem or long-tract findings. Analysis of age at disease onset through multiple generations suggests anticipation. CONCLUSION: This pedigree represents a genetically distinct form of SCA with a phenotype characterized by predominantly cerebellar symptoms and signs.

[Distraction as a stimulus of bone formation]. / La distracción como estímulo de formación ósea.

In orthopaedics limb length discrepancy and bone lost from infection are more frequent and difficult to resolve at the moment G. Ilizarov showed new bone formation with slow distraction stimulation in a well vascularization an rigidly fixed bone. Good patient selection, surgical technique, complete post-operative care and patient collaboration are necessary to get excellent or good results. This paper involves 50 patients, 39 with limb lengthening and 11 with infection and bone loss. We obtained excellent and good results in 37 cases of lengthening and 10 in the second one. At the moment the complications with external fixators may be used and we advised their use.

Neuropsychological and behavioral abnormalities in an adolescent with frontal lobe seizures.

A 13-year-old girl had a reversible frontal syndrome secondary to partial complex seizures. She developed sudden and dramatic behavioral changes including sexual disinhibition, loss of concern for personal hygiene, physical and verbal aggression, and pressured and tangential speech. Although the basic neurologic examination was normal, neuropsychological testing revealed selective impairment on tasks sensitive to frontal dysfunction with relatively normal performance on other tests. This case demonstrates that a frontal syndrome can be caused by partial complex seizures and that behavior comparable to that observed in adults with frontal dysfunction may occur in young adolescents.

Community-oriented medical education: comparison of tracks in Mexico and New Mexico.

Most major innovations in medical education have occurred in a small number of new schools. Attempts to create change in traditional schools are far more complex. Relevant models for such change are few and there is an urgent need for institutions pioneering such changes to learn from each other's experiences. Two conventional medical schools described in this paper have attempted to create community-oriented institutional change by establishing experimental undergraduate curricular tracks. One is in a developing country, Mexico, the other in a technically developed country, the United States. These new tracks in medical education evolved independently of one another, yet they have many similarities and have experienced common problems. A formal exchange between the two schools has led to new insights in medical education and improvements to both programmes. Exchange agreements like the one reported here would be valuable for other medical schools in both developing and technically developed countries.