Milne, ¿una obra para niños?

Tras una introducción por la literatura para niños en los paises del norte de Europa la autora nos lleva a través de la vida y obra de Alan Alexander Milne para centrarse en su obra más conocida y que tiene como protagonista al oso Winnie-the-Pooh.

La piedra filosofal : las razones de Harry Potter.

El autor hace un análisis de la serie de libros que tiene como protagonista al niño Harry Potter reconociendo, por un lado, sus coincidencias con varios tópicos de la literatura infantil, y por otra lado, su utilidad para aficionar a la lectura a los niños ya que se trata de un libro infantil pero con formato de libro de adultos (sin ilustraciones).

Un modelo de reforma educativa : los Institutos-Escuelas (1918-1936).

Este artículo realiza un análisis de la reforma educativa habida en España desde finales del siglo XIX en lo referente a la enseñanza secundaria y que culmina con la creación en 1918 del primer Instituto-Escuela, al que seguiran algunos otros y cuya trayectoria se vería interrumpida por la Guerra Civil Española. Se pretende mostrar: primero, cómo la creación y organización de estos Institutos-Escuela fue resultado de un previo convencimiento, entre los hombres de la ILE (Institución Libre de Enseñanza), de la inviabilidad de las reformas educativas emprendidas; segundo, cómo dicha creación fue la tercera fase de tres estrategías diferentes con un mismo objetivo: la reforma de la segunda enseñanza; tercera, la viabilidad y eficacia de un modelo de reforma a largo plazo, basado en la formación de los profesores que la iban a llevar a cabo; cuarta, cómo el fracaso de dicha reforma se debió a un hecho externo, la Guerra Civil Española.

Gumersindo de Azcárate y el proyecto educativo de la Institución Libre de Enseñanza.

Este artículo nos muestra la trayectoria profesional de Don Gumersindo de Azcárate desde sus comienzos como estudiante en la Universidad Central, situándose dentro del grupo que seguirá la corriente krausista que desembocará, más tarde, en la creación de la Institución Libre de Enseñanza en la que toma parte desde sus comienzos, consolidándose como profesor de enseñanza superior y conferenciante, asumiendo también funciones de gestión y administración. Se destaca también su labor de defensa y difusión del proyecto educativo de la Institución Libre de Enseñanza en la sociedad española de la época.

Spermiogenesis particularities of a sperm storage species: Helicolenus dactylopterus (Teleostei: Scorpaenidae)

A study of the spermiogenesis and spermatozoa of Helicolenus dactylopterus was conducted. Females of this species have the capacity to store sperm within their ovaries, and male gametes have a considerable cytoplasmic mass surrounding their heads to survive the long period of intraovarian sperm storage. Our observations show that early spermatids are round-shaped cells and have a spherical nucleus with diffuse chromatin. The nuclear volume decreases as a result of progressive chromatin condensation during spermiogenesis, causing the nucleus to take on a U-shape. Flagellar insertion is not central to the nucleus but consistently occurs at an oblique angle towards one side of it. The flagellum is inserted into the nuclear fossa, without subsequent nuclear rotation. In mature spermatozoa, the flagellum is adjacent to the nucleus. A comparison of the spermatozoa in the testicular lobules and those in the intraovarian storage structures suggests that the increase in volume of the cytoplasmic mass may occur in the posterior region of the testis, in the testicular duct. Spermatozoa enter the ovary in groups that reach the ovarian lumen and are surrounded by the ovarian epithelium for storage in sperm storage crypts

Anàlisi microscòpica de l'esperma ejaculada i de la maduració epididimària dels espermatozoides de Sus domesticus

El present treball analitza la morfologia espermàtica de l'ejaculat de Sus domesticus, la histologia del conducte epididimari i la qualitat de l'esperma epididimari. El material d'estudi prové de mascles reproductors porcins de les races Landrace i Pietrain, sans i sexualment madurs. La metodologia emprada es basa en l'examen al microscopi òptic (camp dar, contrast de fases i contrast interferencial) i al microscopi electrònic (de rastreig i de transmissió). Per a l'anàlisi estadística de les dades s'ha utilitzat el test de la X2 de Pearson (p<0,01). L'estudi de la morfologia espermàtica de l'ejaculat permet distingir diversos tipus de gàmetes que s'han classificat en tres grups: espermatozoides madurs, espermatozoides immadurs i espermatozoides aberrants, així com algunes cèI.lules somàtiques. L'espermatozoide madur de Sus domesticus és un gàmeta típic de mamífer (format per tres parts: cap, peça de connexió i cua) en que destaquen: la forma oval i plana del cap, el desenvolupament d'una protuberància acrosòmica apical en una de les cares del cap i la presencia dels cossos laminars en la peça de connexió. L'espermatozoide immadur es caracteritza per la presencia de la gota citoplasmàtica, el major desenvolupament de la protuberància acrosòmica apical i per la flexibilitat del cap. Els espermatozoides aberrants es descriuen i classifiquen segons la morfologia externa i la morfologia interna, distingint-se una amplia gama de malformacions que afecten les diverses parts de l'espermatozoide. Les cèl·lules somàtiques presents en l'ejaculat ofereixen les característiques pròpies d'un macròfag i se les ha observat englobant espermatozoides immadurs. L'estudi de l'estructura i la ultraestructura de les tres regions anatòmiques de l'epidídim (caput, corpus i cauda) revela que: a) l'epiteli epididimari és pseudoestratificat amb esterocilis, b) cada regió epididimària presenta uns valors característics en relació al diàmetre intern del conducte, a l'alçada de l'epiteli, a la longitud dels esterocilis i al nombre de cèl·lules somàtiques luminals, i c) l'epiteli epididimari esta format per cinc tipus cel·lulars: les cèl·lules principals, les cèl·lules basals, les cèl·lules dares, les cèl·lules estretes i les cèl·lules basòfiles. Dels resultats obtinguts es pot deduir que: a) aquests cinc tipus cel·lulars es distribueixen al llarg del conducte epididimari de forma no homogènia, b) les cèl·lules basals, les cèl·lules principals, les cèI.Iules dares i les cèl·lules estretes són diversos estadis del desenvolupament d'un mateix tipus cel·lular especialitzat en la secreció i reabsorció cel·lular, i c) les cèl·lules basòfiles són les precursores de les cèl·lules somàtiques luminals. La qualitat de l'esperma procedent de les tres regions de l'epidídim ha estat analitzada a partir dels següents paràmetres espermàtics: vitalitat, resistència osmòtica dels acrosomes, estabilitat cefàlica, morfologia, malformacions i aglutinació. La vitalitat espermàtica disminueix progressivament al llarg del conducte epididimari. La resistència osmòtica dels acrosomes s'assoleix en la regió corporal de l'epidídim. L'estabilitat cefàlica dels espermatozoides és més elevada en les dues primeres regions de l'epidídim que en la regió caudal. Cada regió de l'epidídim es caracteritza per una morfologia espermàtica específica: a) el caput es caracteritza per l'elevat percentatge d'espermatozoides immadurs amb gota citoplasmàtica proximal, b) el corpus es caracteritza per l'elevat percentatge d'espermatozoides immadurs amb gota citoplasmàtica distal, i c) el cauda es caracteritza per l'elevat percentatge d'espermatozoides madurs. S'han estudiat les següents malformacions d'origen epididimari: espermatozoides de cua doblegada per l'anell de Jensen (origen en el cauda), espermatozoides de cua enrotllada i espermatozoides de cues fusionades (origen en el corpus). Els espermatozoides perden la capacitat de doblegar la cua per la peça intermèdia a mesura que avancen pel conducte epididimari. L'aglutinació espermàtica tendeix a augmentar progressivament al llarg del conducte epididimari, si bé, no s'han observat variacions significatives en els diversos tipus d'aglutinació. La maduració epididimaria dels espermatozoides de Sus domesticus és un procés lent i complex, i la qualitat de l'ejaculat depèn de que aquesta maduració hagi estat completa. La presencia en l'esperma ejaculat de formes gamètiques pròpies de l'esperma epididimari és un signe d'una incompleta maduració dels espermatozoides; i, pot considerar-se com un paràmetre indicador d'estrés del mascle reproductor, tant més quant més s'assembli a la morfologia espermàtica de la regió cefàlica de l'epidídim.

Effects of neuropathy on high-voltage-activated Ca2+ current in sensory neurones

Voltage-dependent Ca2+ channels (VDCCs) have emerged as targets to treat neuropathic pain; however, amongst VDCCs, the precise role of the CaV2.3 subtype in nociception remains unproven. Here, we investigate the effects of partial sciatic nerve ligation (PSNL) on Ca2+ currents in small/medium diameter dorsal root ganglia (DRG) neurones isolated from CaV2.3(−/−) knock-out and wild-type (WT) mice. DRG neurones from CaV2.3(−/−) mice had significantly reduced sensitivity to SNX-482 versusWTmice. DRGs from CaV2.3(−/−) mice also had increased sensitivity to the CaV2.2 VDCC blocker -conotoxin. In WT mice, PSNL caused a significant increase in -conotoxin-sensitivity and a reduction in SNX-482-sensitivity. In CaV2.3(−/−) mice, PSNL caused a significant reduction in -conotoxin-sensitivity and an increase in nifedipine sensitivity. PSNL-induced changes in Ca2+ current were not accompanied by effects on voltagedependence of activation in either CaV2.3(−/−) or WT mice. These data suggest that CaV2.3 subunits contribute, but do not fully underlie, drug-resistant (R-type) Ca2+ current in these cells. In WT mice, PSNL caused adaptive changes in CaV2.2- and CaV2.3-mediated Ca2+ currents, supporting roles for these VDCCs in nociception during neuropathy. In CaV2.3(−/−) mice, PSNL-induced changes in CaV1 and CaV2.2 Ca2+ current, consistent with alternative adaptive mechanisms occurring in the absence of CaV2.3 subunits.

The use of FT-IR as a screening technique for organic residue analysis of archaeological samples

A range of archaeological samples have been examined using FT-IR spectroscopy. These include suspected coprolite samples from the Neolithic site of Catalhoyuk in Turkey, pottery samples from the Roman site of Silchester, UK and the Bronze Age site of Gatas, Spain and unidentified black residues on pottery sherds from the Roman sites of Springhead and Cambourne, UK. For coprolite samples the aim of FT-IR analysis is identification. Identification of coprolites in the field is based on their distinct orange colour; however, such visual identifications can often be misleading due to their similarity with deposits such as ochre and clay. For pottery the aim is to screen those samples that might contain high levels of organic residues which would be suitable for GC-MS analysis. The experiments have shown coprolites to have distinctive spectra, containing strong peaks from calcite, phosphate and quartz; the presence of phosphorus may be confirmed by SEM-EDX analysis. Pottery containing organic residues of plant and animal origin has also been shown to generally display strong phosphate peaks. FT-IR has distinguished between organic resin and non-organic compositions for the black residues, with differences also being seen between organic samples that have the same physical appearance. Further analysis by CC-MS has confirmed the identification of the coprolites through the presence of coprostanol and bile acids, and shows that the majority of organic pottery residues are either fatty acids or mono- or di-acylglycerols from foodstuffs, or triterpenoid resin compounds exposed to high temperatures. One suspected resin sample was shown to contain no organic residues. and it is seen that resin samples with similar physical appearances have different chemical compositions. FT-IR is proposed as a quick and cheap method of screening archaeological samples before subjecting them to the more expensive and time-consuming method of GC-MS. This will eliminate inorganic samples such as clays and ochre from CC-MS analysis, and will screen those samples which are most likely to have a high concentration of preserved organic residues. (C) 2008 Elsevier B.V. All rights reserved.

CD40 Triggering of Heterodimeric IL-12 p70 Production by Dendritic Cells In Vivo Requires a Microbial Priming Signal

CD40 ligation triggers IL-12 production by dendritic cells (DC) in vitro. Here, we demonstrate that CD40 cross-linking alone is not sufficient to induce IL-12 production by DC in vivo. Indeed, resting DC make neither the IL-12 p35 nor IL-12 p40 subunits and express only low levels of CD40. Nevertheless, after DC activation by microbial stimuli that primarily upregulate IL-12 p40 and augment CD40 expression, CD40 ligation induces a significant increase in IL-12 p35 and IL-12 p70 heterodimer production. Similarly, IL-12 p70 is produced during T cell activation in the presence but not in the absence of microbial stimuli. Thus, production of bioactive IL-12 by DC can be amplified by T cell–derived signals but must be initiated by innate signals.

High throughput, high resolution selection of polymorphic microsatellite loci for multiplex analysis

Background Large-scale genetic profiling, mapping and genetic association studies require access to a series of well-characterised and polymorphic microsatellite markers with distinct and broad allele ranges. Selection of complementary microsatellite markers with non-overlapping allele ranges has historically proved to be a bottleneck in the development of multiplex microsatellite assays. The characterisation process for each microsatellite locus can be laborious and costly given the need for numerous, locus-specific fluorescent primers. Results Here, we describe a simple and inexpensive approach to select useful microsatellite markers. The system is based on the pooling of multiple unlabelled PCR amplicons and their subsequent ligation into a standard cloning vector. A second round of amplification utilising generic labelled primers targeting the vector and unlabelled locus-specific primers targeting the microsatellite flanking region yield allelic profiles that are representative of all individuals contained within the pool. Suitability of various DNA pool sizes was then tested for this purpose. DNA template pools containing between 8 and 96 individuals were assessed for the determination of allele ranges of individual microsatellite markers across a broad population. This helped resolve the balance between using pools that are large enough to allow the detection of many alleles against the risk of including too many individuals in a pool such that rare alleles are over-diluted and so do not appear in the pooled microsatellite profile. Pools of DNA from 12 individuals allowed the reliable detection of all alleles present in the pool. Conclusion The use of generic vector-specific fluorescent primers and unlabelled locus-specific primers provides a high resolution, rapid and inexpensive approach for the selection of highly polymorphic microsatellite loci that possess non-overlapping allele ranges for use in large-scale multiplex assays.

Velocity profiles and frictional pressure drop for shear thinning materials in lid-driven cavities with fully developed axial flow

A finite element numerical study has been carried out on the isothermal flow of power law fluids in lid-driven cavities with axial throughflow. The effects of the tangential flow Reynolds number (Re-U), axial flow Reynolds number (Re-W), cavity aspect ratio and shear thinning property of the fluids on tangential and axial velocity distributions and the frictional pressure drop are studied. Where comparison is possible, very good agreement is found between current numerical results and published asymptotic and numerical results. For shear thinning materials in long thin cavities in the tangential flow dominated flow regime, the numerical results show that the frictional pressure drop lies between two extreme conditions, namely the results for duct flow and analytical results from lubrication theory. For shear thinning materials in a lid-driven cavity, the interaction between the tangential flow and axial flow is very complex because the flow is dependent on the flow Reynolds numbers and the ratio of the average axial velocity and the lid velocity. For both Newtonian and shear thinning fluids, the axial velocity peak is shifted and the frictional pressure drop is increased with increasing tangential flow Reynolds number. The results are highly relevant to industrial devices such as screw extruders and scraped surface heat exchangers. (c) 2006 Elsevier Ltd. All rights reserved.

Reclassification of Bacteroides putredinis (Weinberg et al., 1937) in a New Genus Alistipes gen. nov., as Alistipes putredinis comb. nov., and description of Alistipes finegoldii sp nov., from human sources

During studies on the bacteriology of appendicitis in children, we often isolated from inflamed and non-inflamed tissue samples, an unusual bile-resistant pigment-producing strictly anaerobic gram-negative rod. Phenotypically this organism resembles members of Bacteroides fragilis group of species, as it is resistant to bile and exhibits a special-potency-disk pattern (resistance to vancomycin, kanamycin and colistin) typical for the B. fragilis group. However, the production of brown pigment on media containing haemolysed blood and a cellular fatty acid composition dominated by iso-C15:0, suggests that the organism most closely resembles species of the genus Porphyromonas. However, the unidentified organism differs from porphyromonads by being bile-resistant and by not producing butyrate as a metabolic end-product. Comparative 16S ribosomal RNA gene sequencing studies show the unidentified organism represents a distinct sub-line, associated with but distinct from, the miss-classified species Bacteroides putredinis. The clustering of the unidentified bacterium with Bacteroides putredinis was statistically significant, but they displayed >4% sequence divergence with each other. Chromosomal DNA-DNA pairing studies further confirmed the separateness of the unidentified bacterium and Bacteroides putredinis. Based on phenotypic and phylogenetic considerations, it is proposed that Bacteroides putredinis and the unidentified bacterium from human sources be classified in a new genus Alistipes, as Alistipes putredinis comb. nov. and Alistipes finegoldii sp. nov., respectively. The type strain of Alistipes finegoldii is CCUG 46020(T) (= AHN2437(T)).

Effects of consumption of probiotics and prebiotics on serum lipid levels in humans

The objective of this article is to review existing studies concerning the effects of probiotics and prebiotics on serum cholesterol concentrations, with particular attention on the possible mechanisms of their action. Although not without exception, results from animal and human studies suggest a moderate cholesterol-lowering action of dairy products fermented with appropriate strain(s) of lactic acid bacteria and bifidobacteria. Mechanistically, probiotic bacteria ferment food-derived indigestible carbohydrates to produce short-chain fatty acids in the gut, which can then cause a decrease in the systemic levels of blood lipids by inhibiting hepatic cholesterol synthesis and/or redistributing cholesterol from plasma to the liver. Furthermore, some bacteria may interfere with cholesterol absorption from the gut by deconjugating bile salts and therefore affecting the metabolism of cholesterol, or by directly assimilating cholesterol. For prebiotic substances, the majority of studies have been done with the fructooligosaccharides inulin and oligofructose, and although convincing lipid-lowering effects have been observed in animals, high dose levels had to be used. Reports in humans are few in number. In studies conducted in normal-lipidemic subjects, two reported no effect of inulin or oligofructose on serum lipids, whereas two others reported a significant reduction in serum triglycerides (19 and 27%, respectively) with more modest changes in serum total and LDL cholesterol. At present, data suggest that in hyperlipidemic subjects, any effects that do occur result primarily in reductions in cholesterol, whereas in normal lipidemic subjects, effects on serum triglycerides are the dominant feature.

Diet, fecal water, and colon cancer - development of a biomarker

Colorectal cancer (CRC) is a leading cause of cancer incidence worldwide. Lifestyle factors, especially dietary intake, affect the risk of CRC development. Suitable risk biomarkers are required in order to assess the effect that specific dietary components have on CRC risk. The relationship between dietary intake and indicators of fecal water activity has been assessed using cell and animal models as well as human studies. This review summarizes the literature on fecal water and dietary components with a view to establishing further the potential role of fecal water as a source of CRC risk biomarkers. The literature indicates that fecal water activity markers are affected by specific dietary components linked with CRC risk: red meat, saturated fats, bile acids, and fatty acids are associated with an increase in fecal water toxicity, while the converse appears to be true for calcium, probiotics, and prebiotics. However, it must be acknowledged that the study of fecal water is still in its infancy and a number of issues need to be addressed before its usefulness can be truly gauged.

Effect of colonic bacterial metabolites on Caco-2 cell paracellular permeability in vitro

One common effect of tumor promoters is increased tight junction (TJ) permeability. TJs are responsible for paracellular permeability and integrity of the barrier function. Occludin is one of the main proteins responsible for TJ structure. This study tested the effects of physiological levels of phenol, ammonia, primary bile acids (cholic acid, CA, and chenodeoxycholic acid, CDCA), and secondary bile acids (lithocholic acid, LCA, and deoxycholic acid, DCA) on paracellular permeability using a Caco-2 cell model. Paracellular permeability of Caco-2 monolayers was assessed by transepithelial electrical resistance (TER) and the apical to basolateral flux of [C-14]-mannitol. Secondary, but not primary, bile acids increased permeability as reflected by significantly decreased TER and increased mannitol flux. Both phenol and ammonia also increased permeability. The primary bile acid CA significantly increased occludin expression (P < 0.05), whereas CDCA had no significant effect on occludin expression as compared to the negative control. The secondary bile acids DCA and LCA significantly increased occludin expression (P < 0.05), whereas phenol had no significant effect on the protein expression as compared to the negative control. This suggests that the increased permeability observed with LCA, DCA, phenol, and ammonia was not related to an effect on occludin expression. In conclusion, phenol, ammonia, and secondary bile acids were shown to increase paracellular permeability and reduce epithelial barrier function at doses typical of levels found in fecal samples. The results contribute to the evidence these gut microflora-generated products have tumor-promoting activity.