Effect of a SiO2 coating on the magnetic properties of Fe3O4 nanoparticles

In this work the effect of a SiO2 coating on the magnetic properties of Fe3O4 nanoparticles obtained by the sol-gel method is analyzed. Two sets of samples were prepared: Fe3O4 nanoparticles and Fe3O4@SiO2 core-shell composites. The samples display the characteristic spinel structure associated with the magnetite Fe3O4 phase, with the majority of grain sizes around 5-10 nm. At room temperature the nanoparticles show the characteristic superparamagnetic behavior with mean blocking temperatures around 160 and 120 K for Fe3O4 and Fe3O4@SiO2, respectively. The main effect of the SiO2 coating is reflected in the temperature dependence of the high field magnetization (μ(0)H = 6 T), i.e. deviations from the Bloch law at low temperatures (T < 20 K). Such deviations, enhanced by the introduction of the SiO2 coating, are associated with the occurrence of surface spin disordered effects. The induction heating effects (magnetic hyperthermia) are analyzed under the application of an AC magnetic field. Maximum specific absorption rate (SAR) values around 1.5 W g(-1) were achieved for the Fe3O4 nanoparticles. A significant decrease (around 26%) is found in the SAR values of the SiO2 coated nanocomposite. The different heating response is analyzed in terms of the decrease of the effective nanoparticle magnetization in the Fe3O4@SiO2 core-shell composites at room temperature.

Heavy metals, salts and organic residues in old solid urban waste landfills and surface waters in their discharge areas: determinants for restoring their impact

This study was designed to determine the state of polluted soils in the main landfills of the Community of Madrid (central Spain), as part of a continuous assessment of the impacts of urban solid waste (USW) landfills that were capped with a layer of soil 20 years ago. Our analysis of this problem has been highly conditioned by the constant re-use of many of the USW landfills, since they have never been the target of any specific restoration plan. Our periodical analysis of cover soils and soils from discharge areas of the landfills indicates soil pollution has worsened over the years. Here, we examined heavy metal, salts, and organic compounds in soil and surface water samples taken from 15 landfills in the Madrid region. Impacts of the landfill soil covers on nematode and plant diversity were also evaluated. These analyses continue to reveal the presence of heavy metals (Zn, Cu, Cr, Ni, Pb, Cd) in soils, and salts (sulphates, chlorides and nitrates) in soils and surface waters. In addition, non-agricultural organic compounds, mainly aromatic and aliphatic hydrocarbons, often appeared in very high concentrations, and high levels of insecticides such as gamma-HCH (lindane) were also detected in soils. Around 50% of the water samples collected showed chemical demand of oxygen (CDO) values in excess of 150 mg/l. Traces of phenolic compounds were detected in some landfills, some of which exhibited high levels of 2-chlorophenol and pentachlorophenol. All these factors are conditioning both the revegetation of the landfill systems and the remediation of their slopes and terrestrial ecosystems arising in their discharge areas. This work updates the current situation and discusses risks for the health of the ecosystems, humans, domestic animals and wildlife living close to these landfills.

Ecotoxicological diagnosis of a sealed municipal landfill

Assessing the environmental impact of a soil-topped landfill requires an accurate ecotoxicological diagnosis. This paper describes various diagnostic protocols for this purpose and their application to a real case: the urban solid waste (USW) municipal landfill of Getafe (Madrid, Spain). After their initial sealing with soil from the surroundings about 20 years ago, most USW landfills in the autonomous community of Madrid have continued to receive waste. This has hindered precise assessment of their impact on their environment and affected ecosystems. The procedure proposed here overcomes this problem by assessing the situation in edaphic, aquatic and ecological terms. The present study focused on the most influential soil variables (viz. salinity due largely to the presence of anions, and heavy metals and organic compounds). These variables were also determined in surface waters of the wetland most strongly affected by leachates running down landfill slopes. Determinations included the characterization of plant communities and microbial biodiversity. The study was supplemented with a bioassay under controlled conditions in pots containing soil contaminated with variable concentrations of Zn (as ZnCl(2)) intended to assess ecochemical actions in a population of Bromus rubens, which grows profusely in the landfill.

Influence of xenobiotic contaminants on landfill soil microbial activity and diversity

Landfills are often the final recipient of a range of environmentally important contaminants such as hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). In this study the influence of these contaminants on microbial activity and diversity was assessed in a municipal solid waste (MSW) landfill placed in Torrejón de Ardoz (Madrid, Spain). Soil samples were collected from four selected areas (T2, T2B, T8 and T9) in which the amount of total hydrocarbons, PAHs and PCBs were measured. Soil biomass, substrate induced respiration (SIR) and physiological profiles of soil samples were also determined and used as indicators of total microbial activity. Highest concentration of total hydrocarbons was detected in T2 and T9 samples, with both PCBs and benzopyrene being detected in T9 sample. Results corresponding to microbial estimation (viable bacteria and fungi, and SIR) and microbiological enzyme activities showed that highest values corresponded to areas with the lowest concentration of hydrocarbons (T2B and T8). It is noticeable that in such areas was detected the lowest concentration of the pollutants PAHs and PCBs. A negative significant correlation between soil hydrocarbons concentration and SIR, total bacteria and fungi counts and most of the enzyme activities determined was established. DGGE analysis was also carried out to determine the microbial communities' structure in the soil samples, establishing different profiles of Bacteria and Archaea communities in each analysed area. Through the statistical analysis a significant negative correlation was only found for Bacteria domain when Shannon index and hydrocarbon concentration were correlated. In addition, a bacterial 16S rRNA gene based clone library was prepared from each soil. From the clones analysed in the samples, the majority corresponded to Proteobacteria, followed by Acidobacteria and Actinobacteria. It is important to remark that the most polluted sample (T9) showed the lowest microbial diversity only formed by six phyla being Proteobacteria and Acidobacteria the most representative.

[Deep brain stimulation for refractory epilepsy: extrathalamic targets]

Epilepsy is a neurological disorder that affects 1-2% of the population. The majority of epileptic patients achieve a good seizure control with the current available treatments. However, there is a subgroup of patients that remain severely disable despite the variety of anti-epileptic drugs, the possibility of surgery for resection of the epileptogenic foci in selected patients, and vagal nerve stimulation; various lines of research are being carried out to look for new treatment alternatives. Deep brain stimulation (DBS) of the thalamus has emerged as a therapeutic alternative for patients who remain in-capacitated; the efficacy of this new therapy is subject of several studies, and its effectiveness and safety has not been established yet. There are other targets for deep brain stimulation that may be useful for drug-resistant epilepsy. Experiments with animal models and preliminary human studies have shown encouraging results with DBS on cerebellum, subthalamic nucleus, substantia nigra, hippocampus and cerebral cortex, among others. The purpose of this review is to revisit the studies that have been carried out on these brain nuclei, as targets for DBS for drug-resistant epilepsy. Studies have shown varying degrees of effectiveness, and there is a need for controlled trials to draw any definite conclusions.

[Changes in nutritional state, metabolic control and treatment of type 1 diabetes in the last 20 years]

OBJECTIVE

The aim of this study is to describe changes in anthropometric characteristics, metabolic control, treatment and prevalence of overweight in diabetic children (DM1) from 2007 compared with another similar group from 1986.

PATIENTS AND METHODS

Observational retrospective study of two groups of diabetic children (n=90). The collection of variables has been made at two cross-sections, 1986 and 2007. The studied variables were: age, years of DM1, sex, weight, height, BMI (and their Z values), HbA(1c) and treatment with insulin (type, number of doses, IU/day and IU/kg/day).

RESULTS

In 2007 group there is a significant increase in Z-weight and Z-BMI (P=.001) when compared with the 1986 group. There was a negative relationship between the years with DM1 and Z-height (P=.05) in the 1986 group. The value of HbA(1c) was lower in the 2007 group (P=.001), but the dose of insulin (IU/day and IU/kg/day) was similar in both groups. The number of daily doses of insulin was higher in the 2007 group (P<.001), the use of insulin analogues dominated overall. A statistically significant relationship between HbA(1c) and treatment with insulin (dose injections, insulin type) was not found. The prevalence of overweight (14.6% vs 2.4%) was significantly higher in the 2007 Group (P=.001).

CONCLUSIONS

The metabolic control (HbA(1c)) had improved and the use of multiple daily doses of insulin has been become the standard, but the prevalence of overweight has increased. We must monitor the emergence of insulin resistance and cardiovascular risk factors in this sensitive population to prevent early cardiovascular disease.

Aggregation and disaggregation dynamics of sedimented and charged superparamagnetic micro-particles in water suspension

This article presents results on the aggregation and disaggregation kinetics on a 1 μm diameter charged superparamagnetic particles dispersed in water under a constant uniaxial magnetic field in experiments with salt (KCl) added to the suspension in order to observe the behaviour of the system when the electrical properties of the particles have been screened. These particles have an electric charge and are confined between two separated 100 μm thick quartz windows, and sediment near the charged bottom wall. The electrostatic interactions that take place in this experimental setup may affect the micro-structure and colloidal stability of the suspension and thus, the dynamics of aggregation and disaggregation.

New insights on culture and calcium signalling in neurons and astrocytes from epileptic patients

Primary brain cell cultures are a useful tool for understanding the physiopathology of epilepsy and for searching new potential antiepileptic drugs. These cell types are usually prepared from murine species and few human models have been described. The main goal of this study is the establishment of experimental conditions to isolate and culture neurons and astrocytes from human brain and to test its functionality. The tissues came from antiepileptic drug-resistant epileptic patients undergoing surgery. Human neurons and astrocytes were isolated following an enzymatic and mechanical dissociation protocol. Cultures were viable for 3-6 weeks. Cytological characterization was performed by immunocytochemistry using specific antibodies against both neuron (anti-NeuN) and astrocyte (anti-GFAP) protein markers. In order to test their viability and functionality, cells were loaded with the fluorescent calcium probe fura-2 and variations in cytosolic calcium concentrations ([Ca2+]c) were measured by cell imaging. [Ca2+]c increases were evoked upon cell stimulation with high K+ (KCl 75 mM), glutamate (500 μM) or bicuculline (100 μM). Interestingly, spontaneous [Ca2+]c transients were also observed in some neuron-like cells. A novel unreported finding in this study has been the incorporation of human serum that was critical for cell functionality. The setting of these human cultures open the opportunity to new insights on culture and calcium signalling studies on the mechanism(s) of cell resistance to antiepileptic drugs, as well as to studies on plasticity, maturation and possible neurite emission for graft studies.

[Voltage sources in mesial temporal area induced by etomidate]

INTRODUCTION

It has been recently shown that activation of the EEG by etomidate is a specific and safe technique during the evaluation of patients for epilepsy surgery.

AIM

To analyze the pathophysiological properties of interictal activity induced by etomidate and compare with the interictal spontaneous activity.

PATIENTS AND METHODS

We studied 13 patients by video-EEG with foramen ovale electrodes. Etomidate (0.1 mg/kg) was injected to activate the epileptogenic region. The activity of foramen ovale electrodes was adjusted to a monopolar voltage source.

RESULTS

Interictal activity mediated by etomidate fits well to a monopolar model, in the same way that the basal interictal activity. The voltage sources distribution recorded during the interictal activity and distribution of voltage sources recorded in presence of etomidate have similar topographical properties. The equivalent charge induced by etomidate was higher than the basal one.

CONCLUSIONS

The basal and etomidate induced activity have similar electrophysiological properties, suggesting that the same or similar structures are responsible of both. So, etomidate can be used as an specific inductor of EEG activity during presurgical evaluation.

Osteosarcoma cells as carriers to allow antitumor activity of canine oncolytic adenovirus in the presence of neutralizing antibodies

Osteosarcoma (OSA) is the most common bone tumor affecting the dog. The veterinary options for therapeutic management of OSA are limited and prognosis for such patients is poor. Oncolytic adenoviruses are attractive tools for experimental therapeutics as they can replicate and spread within tumors to directly induce tumor destruction. However, a major impediment to systemic oncolytic adenoviruses injection is the presence of pre-existing neutralizing antibodies (Nabs). In this study, we investigated the effect of a replication-selective canine adenovirus (OCCAV) to treat OSA in the presence of Nabs and the use of canine OSA cells as carrier vehicles for evading Nabs. Our systemic biodistribution data indicated that canine tumor cells could successfully reach the tumor site and deliver OCCAV to tumor cells in an immunized mice model. Furthermore, the use of carrier cells also reduced adenovirus uptake by the liver. Importantly, OCCAV alone was not effective to control tumor growth in a pre-immunized xenograft mouse model. On the contrary, systemic antitumoral activity of carrier-cell OCCAV was evident even in the presence of circulating antibodies, which is a relevant result from a clinical point of view. These findings are of direct translational relevance for the future design of canine clinical trials.

[Effect of pamidronate infusion time on renal function in patients with multiple myeloma]

INTRODUCTION

Administration of biphosphonates in patients with renal failure requires a dosage adjustment.

OBJECTIVES

Analyse renal function evolution in multiple myeloma patients after reducing infusion time for 90 mg pamidronate by 2 h.

METHODS

In 2007, a retrospective study was carried out on all patients who presented multiple myeloma and bone metastasis treated with pamidronate administered every 4 h. Following a review of the literature, a protocol for administering pamidronate every 2 h was created in partnership with Haematology, and a specific dose reduction framework was established for patients with baseline renal failure. Additionally, a prospective follow-up study of those patients' renal function was completed to analyse its evolution after the change in infusion time.

RESULTS

A total of six patients received 90 mg pamidronate every 4 h. 33.32% of the patients (2/6) presented baseline renal insufficiency, and therefore needed to have the pamidronate dose adjusted according to the new protocol. Subsequently, all of them received the treatment every 2 h, and one patient (16.6%) experienced altered renal function after two treatment cycles.

DISCUSSION

Reducing administration time for pamidronate from four to 2 h did not lead to significant variations in patients' renal function. This therapeutic practice can improve patients' quality of life by shortening their hospital stay without aggravating their renal function.

[Changes in cerebral perfusion induced by etomidate in patients with temporal lobe epilepsy]

INTRODUCTION

Epilepsy is one of the major neurological disorders, affecting roughly 0.5-2% of the world's population and approximately 20-25% of patients are resistant to medication.

AIM

To analyze the response of cerebral perfusion (assessed by SPECT) and bioelectrical activity (measured in scalp and mesial temporal region) to etomidate.

PATIENTS AND METHODS

We studied 10 patients presurgically evaluated and studied by video-EEG with foramen ovale electrodes (EFO) and SPECT. Etomidate was administered (0.1 mg/kg), followed by (99)mTc-HmPAO during the study in the video-EEG + EFO.

RESULTS

The side-effects consisted of myoclonus (n = 7) and moderate pain (n = 2). There had been no significant respiratory or cardiovascular effects. The bioelectrical activity in the scalp consisted in a brief initial rapid activity, followed by a generalized and hypervoltaged delta pattern for several minutes. In the epileptogenic zone, there was a marked increase of interictal activity. Increased cerebral perfusion was observed in all areas studied, especially in temporal region (mesial and lateral) areas and thalamus. In the tail of the non-epileptic hippocampus, we observed the second largest increase in cerebral perfusion, the only region that is different from contralateral area.

CONCLUSIONS

Activation by etomidate induces a specific and repetitive response in the bioelectrical activity. In addition, cerebral perfusion changes directly related to the epileptogenic region may serve therefore as a diagnostic tool in the near future.

[Genetics components in patients with temporal lobe epilepsy]

INTRODUCTION

Epilepsy is one of the major neurological disorders characterized by spontaneous and recurrent seizures. Traditionally temporal lobe epilepsy (TLE) was considered as a multifactorial syndrome due to environmental factors. Advances in molecular biology have facilitated the detection of many genetic alterations that may have a pathogenic effect in ELT. Recently, many authors show evidence about the existence of genetic components as the source of some types of ELT.

DEVELOPMENT

This review aims to provide an overview of mutations and polymorphisms associated with temporal lobe epilepsy, which have been described in scientific literature and its contribution to the pathophysiology of epileptogenesis. We have reviewed the following genes; LGI1, PDYN (prodynorphin), interleucine 1beta, PRPN (prion protein), ApoE (apolipoprotein E), GABBR1, SCN1A, SCN1B, KCNA1, KCND2.

CONCLUSION

The ELT is a complex disease and its development could depend on either genetics factors or other factors. Functional studies are necessary in order to correlate its molecular basis and their development.