Iron deficiency in astrocytes alters cellular status and impacts on oligodendrocyte differentiation.

Iron deficiency (ID) has been shown to affect central nervous system (CNS) development and induce hypomyelination. Previous work from our laboratory in a gestational ID model showed that both oligodendrocyte (OLG) and astrocyte (AST) maturation was impaired. To explore the contribution of AST iron to the myelination process, we generated an in vitro ID model by silencing divalent metal transporter 1 (DMT1) in AST (siDMT1 AST) or treating AST with Fe3+ chelator deferoxamine (DFX; DFX AST). siDMT1 AST showed no changes in proliferation but remained immature. Co-cultures of oligodendrocyte precursors cells (OPC) with siDMT1 AST and OPC cultures incubated with siDMT1 AST-conditioned media (ACM) rendered a reduction in OPC maturation. These findings correlated with a decrease in the expression of AST-secreted factors IGF-1, NRG-1, and LIF, known to promote OPC differentiation. siDMT1 AST also displayed increased mitochondrial number and reduced mitochondrial size as compared to control cells. DFX AST also remained immature and DFX AST-conditioned media also hampered OPC maturation in culture, in keeping with a decrease in the expression of AST-secreted growth factors IGF-1, NRG-1, LIF, and CNTF. DFX AST mitochondrial morphology and number showed results similar to those observed in siDMT1 AST. In sum, our results show that ID, induced through two different methods, impacts AST maturation and mitochondrial functioning, which in turn hampers OPC differentiation.

Identification of free-living amoebas and amoeba-resistant bacteria accumulated in Dreissena polymorpha.

To identify the free-living amoeba (FLA) and amoeba-resistant bacteria (ARB) accumulated in zebra mussels and in the water in which they are found, mussels were collected at two locations in the Ebro river basin (North East Spain). FLAs and bacteria were isolated from mussel extracts and from natural water. PCR techniques were used to identify the FLAs and endosymbiont bacteria (Legionella, Mycobacterium, Pseudomonas and cyanobacteria), and to detect Giardia and Cryptosporidium. The most frequently found FLAs were Naegleria spp. The presence of Legionella, Mycobacterium and Pseudomonas inside the FLA was demonstrated, and in some cases both Legionella and Pseudomonas were found together. Differences between FLAs and ARB identified inside the mussels and in the water were detected. In addition, Escherichia coli, Clostridium perfringens, Salmonella spp. and Enterococcus spp. were accumulated in mussels in concentrations unconnected with those found in water. The results show the ability of the zebra mussel to act as a reservoir of potentially pathogenic FLAs, which are associated with potentially pathogenic ARB, although the lack of association between microorganisms inside the mussels and in the water suggests that they are not useful for monitoring microbiological contamination at a specific time.

Seeking the reuse of effluents and sludge from conventional wastewater treatment plants: Analysis of the presence of intestinal protozoa and nematode eggs.

Some of the microorganisms present in urban wastewater, which include intestinal protozoa and nematodes, can be pathogenic. Their (oo)cyst and egg transmissible stages are very resistant to environmental stresses and disinfectants and they are therefore difficult to remove. Thus, they can constitute a health risk if water or sludge obtained in the purification of wastewater is reused for agricultural purposes. In this context, the presence of intestinal protozoa and nematodes were studied in influents, effluents and sludge from five wastewater treatment plants (WWTPs) in the north of Spain by optical microscopy and PCR techniques. The removal efficiency of different wastewater treatments was also compared. The presence of protozoa has increased among the population discharging waste to WWTPs in recent years. Cryptosporidium spp., Giardia duodenalis, Entamoeba spp. and nematodes were detected in all of the WWTPs. Indeed, this is the first report of Entamoeba histolytica and Entamoeba moshkovskii in Spanish WWTPs. The water treatments studied showed different removal efficiencies for each species of intestinal protozoa, with the aerated lagoons providing the best results. (Oo)cysts were also detected in sludge even after aerobic digestion and dehydration. To avoid risks, (oo)cyst viability should be analysed whenever the sludge is to be used as a fertilizer. This study reinforces the necessity of establishing legal limits on the presence of protozoa in WWTP effluents and sludges, especially if reuse is planned. Further studies are necessary for a better understanding of the presence and behaviour of intestinal parasites.

The Use of Quinacrine in Nitroimidazole-resistant Giardia Duodenalis: An Old Drug for an Emerging Problem.

Background: There is little evidence regarding the management of refractory giardiasis after treatment with nitroimidazoles. This study estimates the proportion of persistent giardiasis in 3 hospitals in Barcelona, describes associated risk factors and genotype, and evaluates the efficacy rate of quinacrine in those with persistent giardiasis. Methods: A clinical, prospective, observational study was conducted in patients with giardiasis treated with nitroimidazoles. Those with persistent giardiasis were provided quinacrine. Molecular characterization of Giardia isolates was performed by polymerase chain reaction amplification of a fragment of tpi and bg genes. Results: Seventy-seven patients were recruited and treated with nitroimidazoles, and in 14 of 71 (20%) of patients followed up, Giardia persisted. Refractory giardiasis was associated with malaise (P = .007) and anorexia (P = .02), with previous giardiasis (P = .03), and with previous antibiotic (P = .02) or antiparasitic(P = .04) use. Quinacrine had an effectiveness rate of 100% in refractory giardiasis (n = 13; 95% confidence interval = 75-100). Molecular characterization showed that 17 (25%) Giardia isolates belonged to assemblage A, and 31 (43%) belonged to assemblage B. In refractory giardiasis, assemblage A and B were found responsible in 4 and 6 cases, respectively. Conclusions: Almost 20% of patients presented persistent giardiasis, belonging to both assemblages A and B, after nitroimidazole. Short course of quinacrine was effective in treating refractory cases. Further controlled studies should evaluate its efficacy and safety.

Cryptosporidiosis outbreak in a child day-care center caused by an unusual Cryptosporidium hominis subtype.

INTRODUCTION: This work describes the genetic characterization of Cryptosporidium and Giardia involved in an outbreak in a nursery school in Granada, Spain, that affected seven children under the age of 4. METHODS: Nucleic acids were extracted from the seven stool samples positive to Cryptosporidium or Giardia by microscopy and/or immunochromatography. The species and subtypes of Cryptosporidium were identified by PCR-RFLP and PCR of the SSUrRNA and gp60 genes, respectively. The assemblages of Giardia duodenalis isolates were characterized by PCR of the tpi gene. PCR products were sequenced and analyzed. RESULTS: All of the isolates were positive for Cryptosporidium hominis. Five of them belonged to subtype IaA11R2, one to subtype IbA10G2R2, and the other could not be identified. Three of these samples were positive for G. duodenalis by PCR, two belonging to the assemblage A, and the other one to assemblage B. DISCUSSION: This is the first report of Cryptosporidium hominis subtype IaA11R2 as a cause of an outbreak in Europe where subtype IbA10G2R2 is the most frequently identified. In the case of Giardia, an outbreak could not be confirmed because of the low number of positive samples and the low genetic variability of the amplified fragments for assemblage A of tpi gene. CONCLUSIONS: A new subtype, of Cryptosporidium hominis named IaA11R2, has been described as a cause of an outbreak in a nursery school in Granada, Spain. However an outbreak of giardiasis could not be confirmed.

Identifying endosymbiont bacteria associated with free-living amoebae.

The association between free-living amoebae and pathogenic bacteria is an issue that has gained great importance due to the environmental and health consequences that it implies. In this paper, we analyse the techniques to follow an epidemiological study to identify associations between genera, species, genotypes and subgenotypes of amoebae with pathogenic bacteria, analysing their evolution and considering their usefulness. In this sense, we highlight the combination of microscopic and molecular techniques as the most appropriate way to obtain fully reliable results as well as the need to achieve the standardization of these techniques to allow the comparison of both environmental and clinical results.

Identification of free-living amoebae and amoeba-associated bacteria from reservoirs and water treatment plants by molecular techniques.

The occurrence of free-living amoebae (FLA) was investigated in 83 water samples from reservoirs and water treatment plants, with culture positive in 64 of them (77.1%). Polymerase chain reaction (PCR) of partial 18S rRNA gene and ITS region was performed in order to identify amoeba isolates, and the presence of Legionella pneumophila , Mycobacterium spp., Pseudomonas spp., and Microcystis aeruginosa was investigated in 43 isolates of amoebae by multiplex PCR. Of the isolated amoebae, 31 were Acanthamoeba spp., 21 were Hartmannella vermiformis, 13 were Naegleria spp., and one was Vanella spp. T2, T4, and T5 genotypes of Acanthamoeba have been identified, and T4 isolates were grouped into five subgenotypes and graphically represented with a Weblog application. Inside amoebae, L. pneumophila was detected in 13.9% (6/43) of the isolates, and Pseudomonas spp. and Mycobacterium spp. were detected in 32.6% (14/43) and 41.9% (18/43), respectively. No statistical correlation was demonstrated between FLA isolation and seasonality, but the presence of intracellular bacteria was associated with warm water temperatures, and also the intracellular presence of Mycobacterium spp. and Pseudomonas spp. were associated. These results highlight the importance of amoebae in natural waters as reservoirs of potential pathogens and its possible role in the spread of bacterial genera with interest in public and environmental health.

MALDI-TOF MS as a tick identification tool in a tertiary hospital in Spain.

In Spain, as in other countries, the spectrum of tick-borne diseases and their number have increased in recent years. The tick identification, at species level, can be challenging outside research centers although this information is very usufull for decisions making. The performance of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in tick identification of specimens collected from patients have been seldomly reported. The aim of the present study was to desing a protein-extraction protocol and build a tick-legs reference spectra. This protocol was then validated using specimens from both patients and non-patient sources. Nine species of ticks that usually bites humans in Spain were included: Dermacentor marginatus, Dermacentor reticulatus, Haemaphysalis punctata, Hyalomma lusitanicum, Hyalomma marginatum, Ixodes ricinus, Rhipicephalus bursa, Rhipicephalus pusillus and Rhipicephalus sanguineus sensu lato. Other less-frequent biting species were also included: Haemaphysalis inermis, Haemaphysalis concinna, Hyalomma scupense, Ixodes frontalis, Ixodes hexagonus, and Argas sp. specimens were identified by PCR and sequencing of a fragment of the 16S rRNA gene of ticks. In the tests performed with non-patient collected specimens, a 100% correlation was observed between molecular methods and MS, while in the tests performed with ticks collected from patients a 92.59% correlation was observed. Misidentification was observed only in two of I. ricinus nymphs (identified as Ctenocephalides felis). Therefore, mass- spectrometry can be confidently used as a tick identification tool in a hospital setting for the rapid identification of tick vectors.

Two cases of zoonotic cryptosporidiosis in Spain by the unusual species Cryptosporidium ubiquitum and Cryptosporidium felis.

INTRODUCTION: Two cases of infection by zoonotic transmission of unusual species of Cryptosporidium were detected in 2010-2011 in Spain (León and Zaragoza). MATERIALS AND METHODS: Cryptosporidium spp. was detected by microscopic examination of modified Ziehl-Neelsen stained fecal smears. PCR-RFLP of the SSUrDNA gene and sequencing of the amplified fragment confirmed the species. RESULTS: C. ubiquitum and C. felis were identified in samples from an immunocompetent child and from a HIV-positive adult, respectively. CONCLUSIONS: This is the first report of human infection by C. ubiquitum (cervine) and autochthonous C. felis, identified in Spain.

Contribution to optimization and standardization of antibacterial assays with silver nanoparticles: the culture medium and their aggregation.

The antimicrobial activity of silver nanoparticles is determined by their size and specific properties, as well as by the chemical composition of the exposure medium in which the nanoparticles are suspended. When the antibacterial tests are carried out in a culture medium, aggregation of the nanoparticles is produced, decreasing their effectiveness. This study proposes the addition of surfactants to the culture medium to prevent the aggregation of silver nanoparticles and optimizes the concentrations of these surfactants. The aggregation of silver nanoparticles was studied by dynamic light scattering (DLS) after dispersion in three liquid culture media (Mueller-Hinton (MH), Luria-Bertani (LB) and Brain Heart Infusion) in which four different surfactants (SDS, Triton X100, Tween 80 and CTAB) were added at concentrations of 0, 0.1, 0.5, 1, 1.5 and 2%. Results showed that, the optimal culture media to prevent aggregation of silver nanoparticles were MH and LB with higher concentrations of Tween 80 and Triton X100 surfactants; being MH + 2% of Tween 80 and MH + 1% Triton X100 the best combinations obtained because the results obtained were closest to the sizes of nanoparticles in ultrapure water. In addition, it has been verified that the optimal medium + surfactant combinations chosen did not affect the viability of Escherichia coli bacteria. Nanoparticle aggregation was not observed by single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) when nanoparticles were incubated for long incubations periods (24 h) in the optimal medium chosen.

Intestinal myiasis due to Eristalis tenax: report of a new case in Spain.

We describe a new case of accidental intestinal myiasis by Eristalis tenax in Spain. Only about 20 cases have been reported worldwide, two of them occurring in Spain. A 51-year-old patient with nonspecific abdominal pain and occasional diarrhoea expelled larvae in her stool. Macroscopic analysis of these larvae revealed morphology compatible with that of Eristalis tenax. The larva analysis showed its autofluorescence as parasitological feature described for the first time.

[Prevalence of Giardia duodenalis assemblage B in humans in Zaragoza and León, Spain]. / Prevalencia de Giardia duodenalis genotipo B en humanos en Zaragoza y León, España.

OBJECTIVES: To study Giardia duodenalis assemblages circulating in the health areas of two hospitals in Zaragoza and León (Spain). METHODS: A total of 211 stool samples with Giardia were genotyped by PCR of the tpi gene. RESULTS: Assemblage B was the most prevalent, both in Zaragoza (84,7%) and León (95,1%). The remaining isolates were identified as AII+B. CONCLUSIONS: We detected the spread of G. duodenalis assemblage B in Zaragoza and in León, with an increase in its prevalence in Zaragoza compared to previous studies.

A Rabbit Model of Acanthamoeba Keratitis: Use of Infected Soft Contact Lenses After Corneal Epithelium Debridement With a Diamond Burr.

Purpose: To develop a rabbit model of Acanthamoeba keratitis (AK) as the best method to reproduce the natural course of this disease. Methods: To induce AK, infected contact lenses (1000 amoebae/mm2, 90% trophozoites) were placed over the previously debrided corneal surface, in combination with a temporary tarsorrhaphy. Environmental and clinical strains of Acanthamoeba spp. (genotype T4) were used. Three groups (1L, n = 32; 2L-21d, n = 5; 2L-3d, n = 23) were established according to the number of contact lenses used (1L, 1 lens; 2L-21d and 2L-3d, 2 lenses) and the placement day of these (1L, day 1; 2L-21d, days 1 and 21; 2L-3d, days 1 and 3). The infection was quantified by a clinical score system and confirmed using corneal cytology and culture, polymerase chain reaction and histopathologic analysis. Results: The infection rate obtained was high (1L, 87.5%; 2L-21d, 100%; 2L-3d, 82.6%), although no clinical signs were observed in the 50% of the infected animals in group 1L. Among groups, group 2L-3d showed more cases of moderate and severe infection. Among strains, no statistically significant differences were found in the infection rate. In the control eyes, cross infection was confirmed when a sterile contact lens was placed in the previously debrided corneas but not if the eye remained intact. Conclusions: The combination of two infected contact lenses after corneal debridement seems to be an alternative model, clinically and histopathologically similar to its human counterpart, to induce the different AK stages and reproduce the course of the disease in rabbits.

Enterococci spp. isolated from Cuba: species frequency of occurrence and antimicrobial susceptibility profile.

This study investigated the species distribution and antimicrobial resistance among 99 enterococci isolated from hospitalized patients in 12 hospitals in Cuba from October 2000 to September 2001. Species identification was performed by WIDER Automatic System (Francisco Soria Melguizo, Madrid, Spain), and the susceptibility testing was performed by disk diffusion, agar dilution, and E-test methods. Enterococcus faecalis was the most prevalent (85%) species, followed by E. faecium (10%), E. gallinarum (2%), E. casseliflavus (2%), and E. durans-hirae (1%). A higher percentage of resistance to ampicillin (50%), fosfomycin (40%), ciprofloxacin (30%), norfloxacin (20%), and tetracycline (90%) was detected in E. faecium isolates, whereas E. faecalis strains showed higher rates of resistance to erythromycin (52.4%), chloramphenicol (34.5%), rifampicin (62.5%), moxifloxacin (3%), and nitrofurantoin (2.4%). Resistance to glycopeptide was detected in E. faecalis (1.2%) and E. faecium (10%). Thirty-one E. faecalis (37%) and 3 E. faecium (30%) showed a high-level resistance to gentamicin. The results of this work will be very helpful to guide empirical antimicrobial therapy and the implementation of infection control measures in Cuban hospitals.

[Sluggish cognitive tempo: an updated review]. / Tempo cognitivo lento: una revision actualizada.

INTRODUCTION: The study of sluggish cognitive tempo (SCT) arose largely from research carried out on attention deficit hyperactivity disorder (ADHD). This construct is defined by a range of behavioural symptoms such as the appearance of drowsiness, daydreaming, physical hypoactivity, little initiative, lethargy and apathy. DEVELOPMENT: The construct of SCT is reviewed by means of recently published papers on its clinical characteristics, associated symptoms, evaluation, prevalence, aetiology, comorbidity, neuropsychological profiles and treatment. The latest studies propose that SCT should be understood as a cluster of symptoms that is distinct from ADHD. Although there is no clear consensus on the matter, the evidence is becoming increasingly more consistent and endows SCT with a high degree of external validity, associating it with internalising symptoms. CONCLUSIONS: We believe the different subtypes of ADHD must be grounded in attentional conceptual models. Hence, the attentional guidance network would be related with SCT, the vigilance or sustained attention network would be linked with the inattentive subtype of ADHD, and executive attention would be involved in the combined subtype of ADHD. The evidence obtained to date, including this review, supports the idea that SCT is an attention disorder distinct from ADHD but, like any dimensional disorder, it can overlap with it in around half the cases.

TITLE: Tempo cognitivo lento: una revision actualizada.Introduccion. El estudio del tempo cognitivo lento (TCL) surgio en gran parte de las investigaciones del trastorno por deficit de atencion/hiperactividad (TDAH). Este constructo se define con una gama de sintomas conductuales, como apariencia de somnolencia, soñar despierto, hipoactividad fisica, pobre iniciativa, letargo y apatia. Desarrollo. Se revisa el constructo de TCL a traves de articulos recientemente publicados al respecto sobre caracteristicas clinicas, sintomas asociados, evaluacion, prevalencia, etiologia, comorbilidad, perfiles neuropsicologicos y tratamiento. Los trabajos mas actuales proponen entender el TCL como un cluster de sintomas distintivo del TDAH. Aunque no hay un consenso claro, los datos son cada vez mas consistentes y dotan de gran validez externa al TCL, asociandolo con sintomas internalizantes. Conclusiones. Consideramos necesario anclar los diferentes subtipos de TDAH en modelos conceptuales atencionales. Asi, la red de orientacion atencional se relacionaria con el TCL, la red de vigilancia o atencion sostenida con el TDAH subtipo inatento, y la atencion ejecutiva seria la implicada en el TDAH subtipo combinado. La evidencia hasta la fecha, incluyendo esta revision, apoya la idea de que el TCL es un trastorno de atencion diferenciado del TDAH, pero que, como cualquier trastorno dimensional, puede solaparse con el aproximadamente en la mitad de los casos.

Intestinal parasites in HIV-seropositive patients in the Continental Region of Equatorial Guinea: its relation with socio-demographic, health and immune systems factors.

BACKGROUND: Prevalence of intestinal parasitic infections in HIV-positive people and its association with clinical and socioeconomic factors has been investigated on the mainland of Equatorial Guinea, in order to define the precise measures for improvement of their quality of life. METHODS: In August 2010, 273 HIV-positive and 60 HIV-negative were recruited. A sample of faeces, T-CD4+ cell counts, and clinical, socioeconomic and demographic data were collected from each patient. Stool samples were analysed by microscopy and immunochromatography. Data were analysed by Pearson's χ2 test and the risk of each factor was measured by odds ratio bivariate analysis. RESULTS: Two hundred and ten (76.9%) HIV-positive participants were infected by intestinal parasites and 16 parasite species were identified; 246 (48.9%) were pathogenic helminths, 159 (22.9%) pathogenic protozoa and 142 (28.2%) opportunistic protozoa. Trichuris trichiura, Entamoeba histolytica/dispar/moshkovskii, Ascaris lumbricoides and Giardia duodenalis were the most prevalent parasites; 52 (86.7%) of HIV-negative participants were parasitized. HIV was related to co-infection by Entamoeba spp., E. nana and Blastocystis hominis. CONCLUSIONS: The high rates of parasitic infections found highlights the urgent need of environmental sanitation, health education and water distribution actions, as well as early diagnosis and treatment of intestinal parasites.

Prevalence of intestinal parasites in HIV-positive patients on the island of Bioko, Equatorial Guinea: its relation to sanitary conditions and socioeconomic factors.

The prevalence of intestinal parasitic diseases and their associated factors has been investigated in HIV populations from the Island of Bioko, Equatorial Guinea. The feces of 310 participants from the island of Bioko (260 HIV-positive and 50 HIV-negative) were analyzed by microscopic observation. Immunochromatography was also used to diagnose Giardia, Entamoeba histolytica and Cryptosporidium spp. In addition, patients were asked for sociodemographic, economic and academic status, and CD4+ T cell counts were recorded. For HIV-positive patients, the prevalence of infection by intestinal parasites was 81.5% (212/260), 83.8% (218/260) by pathogenic helminths and 55.4% (168/260) by pathogenic protozoa (E. histolytica/dispar and Giardia duodenalis). Gender association was found between the infection by Ascaris and Schistosoma, a higher proportion being found in women; and between Entamoeba and the place of residence, a higher proportion being observed in the urban belt. Strongyloides stercoralis and Chilomastix mesnili appeared only in the people of this group, all the cases of Chilomastix being in females. For HIV-negative participants, the prevalence of infection by intestinal parasites was 74.0% (37/50), 90.0% (45/50) by pathogenic helminths and 66.0% (43/50) by pathogenic protozoa. Gender, educational level and low hygiene were associated with intestinal parasitic infection. When comparing the two groups (HIV-positive and HIV-negative), statistical association between HIV co-infection and infection by Giardia and Entamoeba was found. Diarrhea was also associated with intestinal parasitic infection in the HIV-positive group. Not only do our findings reflect high rates of intestinal parasitic infections in HIV-positive people, but also in the HIV-negative group, suggesting a closer relationship between sanitary status and living conditions than with immune status, and thus they highlight the need to carry out health education policies in the population. In addition, Schistosoma intercalatum/guineensis has been detected for the first time as an autochthonous parasite on the island.

Evaluation of in vitro efficacy of combined riboflavin and ultraviolet a for Acanthamoeba isolates.

PURPOSE: To evaluate in vitro the amoebicidal effects of riboflavin and ultraviolet A (UVA) collagen cross-linking. DESIGN: Experimental study, laboratory investigation. METHODS: Two different strains of Acanthamoeba species were tested identically. Four treatment groups were considered: group 1 consisted of 0.1% riboflavin and 30-minute UVA irradiation; group 2 consisted of 0.1% riboflavin and 60-minute UVA irradiation; group 3 consisted of no riboflavin and no UVA exposure; group 4 consisted of 0.1% riboflavin and no UVA exposure. The application of UVA was performed under the parameters used for in vivo corneal collagen cross-linking. RESULTS: In all cases, cysts and trophozoites were detected 24 hours after treatment at a radial distance from the center of the seeding point more than 5 mm, indicating that the amoebae were viable. All treated and untreated groups of amoebae from the 2 strains exhibited growth (radii of 14 to 15 mm in groups 1, 3, and 4; radius of 12 mm in group 2). The final morphologic features of the 2 strains of trophozoites that received treatment were similar to those of the initial seeding group and the untreated control group. CONCLUSIONS: The results obtained in our study show that a single dose (30 or 60 minutes) of cross-linking cannot achieve eradication in the 2 different Acanthamoeba strains examined. However, in vitro results do not always indicate in vivo efficacy, so future studies should test the validity of this treatment for Acanthamoeba keratitis.

[Factorial structure of the dysexecutive questionnaire in a sample of the Spanish population with acquired brain injury and memory deficit complaints]. / Estructura factorial del cuestionario disejecutivo en una muestra de población española con daño cerebral adquirido y quejas de déficit de memoria.

INTRODUCTION AND AIMS: The dysexecutive questionnaire (DEX) has been used to study executive deficits in both clinical samples (both psychiatric and neurological) and non-clinical samples, although agreement on its factorial structure is lacking. The aim of this research is to study that structure in the self-administered version in a sample of the Spanish population with acquired brain injury and memory loss complaints, and to compare that solution with those obtained in other studies. PATIENTS AND METHODS: The questionnaire was administered to 119 subjects with acquired brain injury with different aetiologies (traumatic, vascular, tumours, multiple sclerosis, toxic-metabolic and others). RESULTS: The Cronbach's alpha coefficient was 0.88. All the items showed adequate discriminatory power, except item 15. No relation was found between the total score on the DEX and the age, gender and time elapsed since the injury. A negative correlation between total score and level of schooling was confirmed. The total score does not follow a normal distribution. The five-factor solution accounts for a higher percentage of the total variance than those of two, three and four factors (63.76%). CONCLUSIONS: The Spanish version of the DEX is an instrument that is valid for evaluating general dysexecutive symptoms in subjects with acquired brain injury. The five-factor factorial structure (planning, cognitive control, inhibition, social awareness and impulse control) offers a greater wealth of information because it measures more aspects of the dys-executive pathology and therefore appears to be more useful in the clinical setting. It is advisable to use the questionnaire in an early stage of evaluation or screening and to use it as a complement to the proxy-reported version.

[Relation between white matter and cognitive functions]. / Relación entre la sustancia blanca y las funciones cognitivas.

INTRODUCTION: After being largely neglected as a contributor to the organisation of the cognitive operations for many years, the white matter of the brain is now again the object of much research. These advances are complemented with the latest neuroimaging techniques, such as diffusion tensor imaging, which make it possible to obtain a more detailed view of the role played by the pathways of the white matter in the cognitive operations. DEVELOPMENT: The study reviews the relation between lesions in the white matter and different cognitive processes and functions such as language, attention, visuospatial and visual-constructional skills, spatial negligence, processing speed, memory and executive functions. CONCLUSIONS: Focusing attention on the white matter and its disorders promises to further our knowledge of the brain as an extraordinarily complex organ in which the connectivity and processing speed provided by the white matter are key features in cognition, emotion and consciousness itself. The white matter does not appear to be the deposit for cognitive processes and functions, but rather its role would seem to be linked to two properties that are essential for a highly complex system like the brain to be effective: speed and connectivity. Further studies must be conducted to delve deeper into these processes and perhaps begin to clarify the different roles they play in the outcome of cognitive processes.