Mössbauer cell for low-temperature studies of catalysts under reaction conditions.

Mössbauer spectroscopy is an essential tool to investigate the structure of Fe supported catalysts and their changes, when they are used in the Fischer-Tropsch synthesis. A cell, that allows keeping the samples in the same atmosphere of the reduction treatment, was designed in order to characterize the Fe species without changing the working atmosphere avoiding the oxidation. It allows to measure at low temperatures in a helium closed-cycle refrigerator. Besides, this cell is useful to perform Mössbauer measurements on the used catalysts, preserving the oxidation of its species, using an inert atmosphere. In this work, we describe the details of this new cell and, as an example of its utility, we present the results obtained with a system of 12 nm iron oxide nanoparticles supported on a mesoporous silica matrix.

Alternative low-cost approach to the synthesis of magnetic iron oxide nanoparticles by thermal decomposition of organic precursors.

A new approach to thermal decomposition of organic iron precursors is reported, which results in a simpler and more economical method to produce well crystallized γ-Fe2O3 nanoparticles (NPs) with average sizes within the 3-17 nm range. The NPs were characterized by TEM, SAED, XRD, DLS-QELS, Mössbauer spectroscopy at different temperatures, FT-IR and magnetic measurements. The obtained γ-Fe2O3 NPs are coated with oleic acid and, in a lower quantity, with oleylamine (about 1.5 nm in thickness). It was shown that changing operative variables allows us to tune the average particle diameters and obtain a very narrow or monodisperse distribution of sizes. The γ-Fe2O3 NPs behave superparamagnetically at room temperature and their magnetization saturation is reduced by about 34% in comparison with bulk maghemite. The results indicate that the distance between two neighbour NPs, generated by the coating, of about 3 nm is insufficient to inhibit interparticle magnetic interactions when the average diameter is 8.8 nm. The good quality of the NPs, obtained through the present low-cost and easy-handling process, open a new perspective for future technological applications.

Germline mosaicism in keratitis-ichthyosis-deafness syndrome: pre-natal diagnosis in a familial lethal form.

Keratitis-ichthyosis-deafness (KID) syndrome is an autosomal dominant congenital ectodermal defect characterized by the association of skin lesions, hearing loss and keratitis. Most of the cases appear to be sporadic. KID syndrome is mostly related to mutations of GJB2 gene encoding connexin-26. Recently, a lethal form of the disease during the first year of life has been reported in two unrelated Caucasian patients. This rare lethal form is caused by the G45E mutation of GJB2 gene. We here report the first pre-natal molecular genetic diagnosis of the lethal form of KID syndrome relating to a G45E mutation. In the same family, the occurrence of this condition in three other siblings born to African non-consanguineous healthy parents lead to perform pre-natal diagnosis for this last pregnancy. Molecular analysis confirms the diagnosis of the lethal form of KID for the fetus. These results establish the role of germline mosaicism in KID syndrome and warrant careful genetic counseling. Furthermore, analysis of our cases and the literature allowed us to define a characteristic severe neonatal phenotype including facial dysmorphy, severe cornification with massive focal hyperkeratosis of the skin with erythroderma, dystrophic nails, complete atrichia and absence of foreskin.

Los programas de alimentación suplementaria y de enriquecimiento de alimentos en América Latina aspectos puntuales / Food suplementation and food fortification programs in Latin America

La suplementación alimentaria se define como la donación de uno o varios alimentos, preparados o crudos, a una colectividad necesitada de atención. Los programas de alimentación suplementaria deben ir acompañados de algún elemento educativo. Los programas de alimentación suplementaria en América Latina han sido una de las actividades más frecuentemente utilizadas en las políticas de nutrición, aunque pocas veces han sido ejecutadas con arreglo a los principios que deben regir los programas en las comunidades pobres. Durante las últimas décadas, con motivo de las medidas de ajuste adoptadas por los gobiernos, e influenciadas por Agencias Internacionales, se organizaron programas de distribución de alimentos, de forma un tanto irregular. Ante la crisis generalizada que afecta hoy, a comienzos del siglo XXI, a la mayor parte de los países latino-americanos es posible que sea necesario fortalecer de nuevo los programas de alimentación suplementaria (AU)

Food transitions in the 20th-21st century.

Food transitions in history have been fast, violent processes in some cases, while on other occasions they have taken place slowly, overlapping the traditional food culture as food items are replaced by new ones. Despite the contribution of potato and maize to avoiding famine in Europe, the exclusive crop system caused serious problems. Main food transitions are currently taking place in Asia. Emerging economies face the dilemma of improving the health and well-being of the population while avoiding excess and surplus. The challenge is twofold: on the one hand, to counteract the negative effects of food transitions and, on the other, to fight against hunger and malnutrition.

[Hemidiaphragmatic paralysis as a manifestation of familial brachial plexus neuropathy]. / Parálisis hemidiafragmática como manifestación de la plexopatía braquial familiar.

We present a patient with familial brachial plexus neuropathy (FBPN) who is in the second generation of a family found to have this disease. The patient suffered phrenic paralysis, which has only been previously described in association with FBPN in 4 similar cases, all of which also involved the left phrenic nerve. The side of phrenic paralysis's was unrelated to the side where brachial plexus lesions occurred. We believe that paralysis of the diaphragm, although rare, can be considered a sign of FBPN and that therefore this disease should be included in the differential diagnosis of such paralysis. This is particularly so whenever family or personal history suggest that the peripheral nervous system may be involved, compromising the brachial plexus, or whenever facial or digital dysmorphia is present.

[Clinical iconographic dissociation in a case of monophasic demyelinating disease]. / Disociación clinicoiconográfica en un caso de enfermedad desmielinizante monofásica.

We report a patient with monophasic inflammatory demyelinizing disease whose initial symptoms and imaging studies led to the undertaking of a cerebral biopsy for suspicion of an expansive process. The evolution of the both the CT and MR imaging studies with contrast and overall the surprising size of the lesions in MR when the patient was clinically asymptomatic support the hypothesis of residual dysfunction in the hemato-encephalic barrier as a cause of the persistence of MR images. This explanation appears more acceptable than its attribution to a gliosis secondary to previous inflammation.

Intestinal absorption of cholecalciferol and 25-hydroxycholecalciferol in patients with both Crohn's disease and intestinal resection.

We compared the intestinal absorption of cholecalciferol and 25-hydroxycholecalciferol in patients with Crohn's disease and resections of the small bowel. Patients were subgrouped into those with small (less than 100 cm), intermediate (100-300 cm), and large (greater than 300 cm) resections. [3H]cholecalciferol or [3H]25-hydroxycholecalciferol were given orally and serial blood samples were taken for measurement of plasma radiolabeled vitamin. Absorption of both forms of the vitamin decreased with extent of resection but 25-hydroxycholecalciferol absorption was always greater than that of cholecalciferol. When compared with normal control subjects, 25-hydroxycholecalciferol absorption in these patients was better maintained than that of cholecalciferol. These data indicate that vitamin D malabsorption reflects the extent of distal small-bowel resection in Crohn's disease. Treatment with oral cholecalciferol is sufficient in those with small or moderate resections but oral 25-hydroxycholecalciferol supplementation may be preferred in those with a severe short-bowel syndrome.

Dietary supplementation in elderly patients with fractured neck of the femur.

59 elderly patients (mean age 82) with femoral neck fractures were randomised into two groups. 27 patients received daily an oral nutrition supplement (250 ml, 20 g protein, 254 kcal) for a mean of 32 days; 32 patients acted as controls. On admission most patients had nutritional deficiencies. Despite being offered adequate quantities, nutritional requirements were not met during the hospital stay. Clinical outcome was significantly better in the supplemented group (56% favourable course vs 13% in controls) during the stay in the convalescent hospital. The rates of complications and deaths were also significantly lower in supplemented patients (44% vs 87%). 6 months after the fracture the rates of complications and mortality were significantly lower in supplemented patients (40% vs 74%). The median duration of hospital stay was significantly shorter in the supplemented group (24 vs 40 days). Thus the clinical outcome of elderly patients with femoral neck fracture can be improved by once daily dietary oral supplementation.

[Nutrition yesterday and today]. / Nutrición ayer y hoy.

The history of human nutrition from primitive times to actuality is briefly outlined. Many of the modern nutritional problems can be traced back to changes caused by the introduction of agriculture and, more recently, food technology. These developments have changed the composition of the diet to which the primitive hunter-gatherers had adapted themselves during millions of years. Changes in food habits and the beginning of the science of nutrition are discussed, and a brief review of nutritional recommendations is provided. The terms of nutritional goals and rules, so much used today, are of recent introduction. Nevertheless, norms, normal allowances and other similar expressions have since long ago been in use. Nutritional goals should be based on the vital habits of the population for which they are intended, and should be adapted to the ever emerging new findings in nutritional sciences.