A collagen-poly(lactic acid-co-ɛ-caprolactone) hybrid scaffold for bladder tissue regeneration.

Scaffold materials should favor cell attachment and proliferation, and provide designable 3D structures with appropriate mechanical strength. Collagen matrices have proven to be beneficial scaffolds for tissue regeneration. However, apart from small intestinal submucosa, they offer a limited mechanical strength even if crosslinking can enhance their mechanical properties. A more cell-friendly way to increase material strength is to combine synthetic polymer meshes with plastic compressed collagen gels. This work describes the potential of plastic compressed collagen-poly(lactic acid-co-ɛ-caprolactone) (PLAC) hybrids as scaffolds for bladder tissue regeneration. Human bladder smooth muscle and urothelial cells were cultured on and inside collagen-PLAC hybrids in vitro. Scaffolds were analyzed by electron microscopy, histology, immunohistochemistry, and AlamarBlue assay. Both cell types proliferated in and on the hybrid, forming dense cell layers on top after two weeks. Furthermore, hybrids were implanted subcutaneously in the backs of nude mice. Host cell infiltration, scaffold degradation, and the presence of the seeded bladder cells were analyzed. Hybrids showed a lower inflammatory reaction in vivo than PLAC meshes alone, and first signs of polymer degradation were visible at six months. Collagen-PLAC hybrids have potential for bladder tissue regeneration, as they show efficient cell seeding, proliferation, and good mechanical properties.

The meiosis-specific recombinase hDmc1 forms ring structures and interacts with hRad51.

Eukaryotic cells encode two homologs of Escherichia coli RecA protein, Rad51 and Dmc1, which are required for meiotic recombination. Rad51, like E.coli RecA, forms helical nucleoprotein filaments that promote joint molecule and heteroduplex DNA formation. Electron microscopy reveals that the human meiosis-specific recombinase Dmc1 forms ring structures that bind single-stranded (ss) and double-stranded (ds) DNA. The protein binds preferentially to ssDNA tails and gaps in duplex DNA. hDmc1-ssDNA complexes exhibit an irregular, often compacted structure, and promote strand-transfer reactions with homologous duplex DNA. hDmc1 binds duplex DNA with reduced affinity to form nucleoprotein complexes. In contrast to helical RecA/Rad51 filaments, however, Dmc1 filaments are composed of a linear array of stacked protein rings. Consistent with the requirement for two recombinases in meiotic recombination, hDmc1 interacts directly with hRad51.

Fission yeast rad51 and dmc1, two efficient DNA recombinases forming helical nucleoprotein filaments.

Homologous recombination is important for the repair of double-strand breaks during meiosis. Eukaryotic cells require two homologs of Escherichia coli RecA protein, Rad51 and Dmc1, for meiotic recombination. To date, it is not clear, at the biochemical level, why two homologs of RecA are necessary during meiosis. To gain insight into this, we purified Schizosaccharomyces pombe Rad51 and Dmc1 to homogeneity. Purified Rad51 and Dmc1 form homo-oligomers, bind single-stranded DNA preferentially, and exhibit DNA-stimulated ATPase activity. Both Rad51 and Dmc1 promote the renaturation of complementary single-stranded DNA. Importantly, Rad51 and Dmc1 proteins catalyze ATP-dependent strand exchange reactions with homologous duplex DNA. Electron microscopy reveals that both S. pombe Rad51 and Dmc1 form nucleoprotein filaments. Rad51 formed helical nucleoprotein filaments on single-stranded DNA, whereas Dmc1 was found in two forms, as helical filaments and also as stacked rings. These results demonstrate that Rad51 and Dmc1 are both efficient recombinases in lower eukaryotes and reveal closer functional and structural similarities between the meiotic recombinase Dmc1 and Rad51. The DNA strand exchange activity of both Rad51 and Dmc1 is most likely critical for proper meiotic DNA double-strand break repair in lower eukaryotes.

Le travail des sans-emploi : analyse sociologique de l'assignation à un programme d'emploi temporaire

RESUMECette recherche empirique porte sur les emplois temporaires subventionnés (ETS) instaurés dans le cadre du chômage et de l'aide sociale en Suisse depuis une dizaine d'années. La mise en place de politiques d'activation dans le cadre de la protection sociale met l'accent sur les liens explicites, souvent réglementaires, qu'entretiennent actuellement la protection sociale, les politiques de l'emploi et le marché du travail dans les pays industrialisés. Ces transformations ont largement contribué au développement d'activités exercées en marge du marché de l'emploi. Dans le cadre du chômage, comme dans celui de l'aide sociale, une mise au travail peut être exigée en contrepartie du versement des indemnités ; en Suisse, on nomme ce procédé l'assignation au travail. L'assignation est le processus par lequel un-e conseiller?ère en placement peut contraindre, sous peine de sanction (suppression des indemnités pour un temps déterminé) une personne au chômage (inscrit-e auprès d'un office régional de placement) à souscrire à une mesure du marché du travail (MMT), particulièrement les ETS.Cette recherche propose une analyse de l'assignation à un programme d'emploi temporaire sous l'éclairage de la sociologie du travail. Elle adopte une perspective compréhensive attentive aux tensions que vivent les individus pris dans une situation de travail hybride et inédite qui les place aux frontières des différentes catégories administratives de chômage, d'inactivité et de population occupée. Partant d'une étude empirique auprès de personnes assignées, cette recherche mène une analyse qualitative des conditions et de l'organisation du travail en ETS, des modalités contractuelles et statutaires des personnes assignées à une activité de travail contrainte et matériellement non reconnue, puisque non salariée. Elle s'attache également à cerner le vécu de l'assignation au travail, ainsi que le sens que les personnes lui attribuent dans leur trajectoire biographique et professionnelle.SUMMARYThis research investigates a specific and new form of labor, namely «temporary subsidized jobs» {emplois temporaires subventionnés, ETS) that have been developed since the late 1990s in Switzerland in the context of unemployment and social assistance benefits. Although ETS are specific to Switzerland, they echo similar «workfare» measures imposed on unemployed and welfare recipients introduced in recent years in almost all industrialized countries. Indeed, the evolution of public policies and the generalization of «active labour-market policies» {politiques d'activation) have become central to social protection in the majority of Western countries and have emerged in parallel to the expansion of work activities situated at the margins of traditional wage- labor.My analysis of the ETS phenomenon is informed by labor sociology and discusses the pertinence of a classical approach in grasping this hybrid and new work situation, which sets individual persons at the border between various administrative categories such as «unemployed», «inactive» and «at work». I investigate in particular the issue of contractual and statutory modalities imposed on persons who have been assigned to a form of activity that is both constraining as well as materially non-recognized (as it remains outside of traditional wage-labor forms). In order to understand ETS conditions and labor organization, my fieldwork consist of interviews of persons who have been assigned to it and observations. I investigate their personal experience, as well as the meaning that these individuals attribute to the ETS experience in the context of their biographical and professional trajectory.

Equivalence of paper and pencil vs internet forms of the ZKPQ-50-CC in Spanish and French samples

This study was designed to check for the equivalence of the ZKPQ-50-CC (Spanish and French versions) through Internet on-line (OL) and paper and pencil (PP) answer format. Differences in means and devia- tions were significant in some scales, but effect sizes are minimal except for Sociability in the Spanish sample. Alpha reliabilities are also very similar in both versions with no significant differences between formats. A robust factorial structure was found for the two formats and the average congruency coefficients were 0.98. The goodness-of-fit indexes obtained by confirmatory factorial analysis are very similar to those obtained in the ZKPQ-50-CC validation study and they do not differ between the two formats. The multi-group analysis confirms the equivalence among the OL-PP formats in both countries. These results in general support the validity and reliability of the Internet as a method in investigations using the ZKPQ-50-CC.

Regulation of nonphosphorylated and phosphorylated forms of neurofilament proteins in the prefrontal cortex of human opioid addicts.

The neurofilament (NF) proteins (NF-H, NF-M, and NF-L for high, medium, and low molecular weights) play a crucial role in the organization of neuronal shape and function. In a preliminary study, the abundance of total NF-L was shown to be decreased in brains of opioid addicts. Because of the potential relevance of NF abnormalities in opioid addiction, we quantitated nonphosphorylated and phosphorylated NF in postmortem brains from 12 well-defined opioid abusers who had died of an opiate overdose (heroin or methadone). Levels of NF were assessed by immunoblotting techniques using phospho-independent and phospho-dependent antibodies, and the relative (% changes in immunoreactivity) and absolute (changes in ng NF/microg total protein) amounts of NF were calculated. Decreased levels of nonphosphorylated NF-H (42-32%), NF-M (14-9%) and NF-L (30-29%) were found in the prefrontal cortex of opioid addicts compared with sex, age, and postmortem delay-matched controls. In contrast, increased levels of phosphorylated NF-H (58-41%) and NF-M (56-28%) were found in the same brains of opioid addicts. The ratio of phosphorylated to nonphosphorylated NF-H in opioid addicts (3.4) was greater than that in control subjects (1.6). In the same brains of opioid addicts, the levels of protein phosphatase of the type 2A were found unchanged, which indicated that the hyperphosphorylation of NF-H is not the result of a reduced dephosphorylation process. The immunodensities of GFAP (the specific glial cytoskeletol protein), alpha-internexin (a neuronal filament related to NF-L) and synaptophysin (a synapse-specific protein) were found unchanged, suggesting a lack of gross changes in glial reaction, other intermediate filaments of the neuronal cytoskeletol, and synaptic density in the prefrontal cortex of opioid addicts. These marked reductions in total NF proteins and the aberrant hyperphosphorylation of NF-H in brains of opioid addicts may play a significant role in the cellular mechanisms of opioid addiction.

Prevalence of patients' difficulties in swallowing solid oral dosage forms

Introduction Swallowing difficulties, or dysphagia, can occur in anyage group, although it is most common among elderly people. It canaffect patients' ability to take solid oral dosage forms, thus compromisingmedication adherence. Although literature is poor, availabledata show that prevalence in the general population ranges from 25 to60%. Prevalence in community pharmacies needs to be explored.Materials & Methods Community pharmacies were recruited from arandom selection in three Swiss states: Basel-Stadt (BS), Basel-Landschaft (BL) and Lausanne (LA). Patients' ability to swallowsolid oral medications was enquired with a semi-structured interview;the interviewer spent 4 h in each included pharmacy. Each consecutivepatient (18 years and older) entering the pharmacy with aprescription for at least 3 different solid oral forms was enrolled.Study was approved by the Lausanne ethics committee.Results Sixty pharmacies took part in the study (20 in BS, 10 in BL,30 in LA) between March and May 2010. Patient inclusion rate was77.8% (410/527). Prevalence of swallowing disorders was 22.4% (92/410). Patients with swallowing disorders were older (mean age: 67.5± 16 years vs. 63.0 ± 14 years, range 19-96; p = 0.03) and moreoften women (69.6% vs. 59.1%; Chi2 = 3.3, p = 0.04) than patientswithout swallowing disorders. They had on average 4.6 ± 2.7 drugswith a mean number of 5.5 ± 3.3 tablets or capsules to take daily,which didn't differ from the number of drugs taken by patientswithout swallowing difficulties (4.9 ± 2.5 drugs and 5.9 ± 3.5 tablets;n.s.). The difficulty was mainly related to the big size (63%) orthe quality of pill coating (rough, sticky, 14%). Twenty-one patients(37.5%) stated that their swallowing disorders resulted in nonadherence, rated as rarely (12 patients), sometimes (6 patients), veryoften (1 patient) or always (2 patients). According to patients, nopharmacist and only 2 physicians enquired about patients' swallowingissue.Discussion & Conclusion Swallowing difficulties are frequent amongpatients in community pharmacies in Switzerland with an estimatedprevalence of 22%. The problem resulted in non adherence or partialadherence in at least 35% of these patients. However, pharmacists andphysicians did not routinely inquire about the disorder. Guidelinesshould be developed for promoting systematic approaches of patientsin community pharmacies.

Clinal variation in a brown lemur (Eulemur spp.) hybrid zone: Combining morphological, genetic and climatic data to examine stability.

Studies of hybrid zones can inform our understanding of reproductive isolation and speciation. Two species of brown lemur (Eulemur rufifrons and E. cinereiceps) form an apparently stable hybrid zone in the Andringitra region of south-eastern Madagascar. The aim of this study was to identify factors that contribute to this stability. We sampled animals at 11 sites along a 90-km transect through the hybrid zone and examined variation in 26 microsatellites, the D-loop region of mitochondrial DNA, six pelage and nine morphological traits; we also included samples collected in more distant allopatric sites. Clines in these traits were noncoincident, and there was no increase in either inbreeding coefficients or linkage disequilibrium at the centre of the zone. These results could suggest that the hybrid zone is maintained by weak selection against hybrids, conforming to either the tension zone or geographical selection-gradient model. However, a closer examination of clines in pelage and microsatellites indicates that these clines are not sigmoid or stepped in shape but instead plateau at their centre. Sites within the hybrid zone also occur in a distinct habitat, characterized by greater seasonality in precipitation and lower seasonality in temperature. Together, these findings suggest that the hybrid zone may follow the bounded superiority model, with exogenous selection favouring hybrids within the transitional zone. These findings are noteworthy, as examples supporting the bounded superiority model are rare and may indicate a process of ecologically driven speciation without geographical isolation.

Simultaneous Mendelian and clonal genome transmission in a sexually reproducing, all-triploid vertebrate.

Meiosis in triploids faces the seemingly insuperable difficulty of dividing an odd number of chromosome sets by two. Triploid vertebrates usually circumvent this problem through either asexuality or some forms of hybridogenesis, including meiotic hybridogenesis that involve a reproductive community of different ploidy levels and genome composition. Batura toads (Bufo baturae; 3n = 33 chromosomes), however, present an all-triploid sexual reproduction. This hybrid species has two genome copies carrying a nucleolus-organizing region (NOR+) on chromosome 6, and a third copy without it (NOR-). Males only produce haploid NOR+ sperm, while ova are diploid, containing one NOR+ and one NOR- set. Here, we conduct sibship analyses with co-dominant microsatellite markers so as (i) to confirm the purely clonal and maternal transmission of the NOR- set, and (ii) to demonstrate Mendelian segregation and recombination of the NOR+ sets in both sexes. This new reproductive mode in vertebrates ('pre-equalizing hybrid meiosis') offers an ideal opportunity to study the evolution of non-recombining genomes. Elucidating the mechanisms that allow simultaneous transmission of two genomes, one of Mendelian, the other of clonal inheritance, might shed light on the general processes that regulate meiosis in vertebrates.

Restricted gene flow at specific parts of the shrew genome in chromosomal hybrid zones.

The species and races of the shrews of the Sorex araneus group exhibit a broad range of chromosomal polymorphisms. European taxa of this group are parapatric and form contact or hybrid zones that span an extraordinary variety of situations, ranging from absolute genetic isolation to almost free gene flow. This variety seems to depend for a large part on the chromosome composition of populations, which are primarily differentiated by various Robertsonian fusions of a subset of acrocentric chromosomes. Previous studies suggested that chromosomal rearrangements play a causative role in the speciation process. In such models, gene flow should be more restricted for markers on chromosomes involved in rearrangements than on chromosomes common in both parent species. In the present study, we address the possibility of such differential gene flow in the context of two genetically very similar but karyotypically different hybrid zones between species of the S. araneus group using microsatellite loci mapped to the chromosome arm level. Interspecific genetic structure across rearranged chromosomes was in general larger than across common chromosomes. However, the difference between the two classes of chromosomes was only significant in the hybrid zone where the complexity of hybrids is expected to be larger. These differences did not distinguish populations within species. Therefore, the rearranged chromosomes appear to affect the reproductive barrier between karyotypic species, although the strength of this effect depends on the complexity of the hybrids produced.

The Escherichia coli RuvB branch migration protein forms double hexameric rings around DNA.

The RuvB protein is induced in Escherichia coli as part of the SOS response to DNA damage. It is required for genetic recombination and the postreplication repair of DNA. In vitro, the RuvB protein promotes the branch migration of Holliday junctions and has a DNA helicase activity in reactions that require ATP hydrolysis. We have used electron microscopy, image analysis, and three-dimensional reconstruction to show that the RuvB protein, in the presence of ATP, forms a dodecamer on double-stranded DNA in which two stacked hexameric rings encircle the DNA and are oriented in opposite directions with D6 symmetry. Although helicases are ubiquitous and essential for many aspects of DNA repair, replication, and transcription, three-dimensional reconstruction of a helicase has not yet been reported, to our knowledge. The structural arrangement that is seen may be common to other helicases, such as the simian virus 40 large tumor antigen.