Otoferlin acts as a Ca2+ sensor for vesicle fusion and vesicle pool replenishment at auditory hair cell ribbon synapses

Hearing relies on rapid, temporally precise, and sustained neurotransmitter release at the ribbon synapses of sensory cells, the inner hair cells (IHCs). This process requires otoferlin, a six C2-domain, Ca2+-binding transmembrane protein of synaptic vesicles. To decipher the role of otoferlin in the synaptic vesicle cycle, we produced knock-in mice (Otof Ala515,Ala517/Ala515,Ala517) with lower Ca2+-binding affinity of the C2C domain. The IHC ribbon synapse structure, synaptic Ca2+ currents, and otoferlin distribution were unaffected in these mutant mice, but auditory brainstem response wave-I amplitude was reduced. Lower Ca2+ sensitivity and delay of the fast and sustained components of synaptic exocytosis were revealed by membrane capacitance measurement upon modulations of intracellular Ca2+ concentration, by varying Ca2+ influx through voltage-gated Ca2+-channels or Ca2+ uncaging. Otoferlin thus functions as a Ca2+ sensor, setting the rates of primed vesicle fusion with the presynaptic plasma membrane and synaptic vesicle pool replenishment in the IHC active zone

Electroactive biofilms: new means for electrochemistry

This work demonstrates that electrochemical reactions can be catalysed by the natural biofilms that form on electrode surfaces dipping into drinking water or compost. In drinking water, oxygen reduction was monitored with stainless steel ultra-microelectrodes under constant potential electrolysis at )0.30 V/SCE for 13 days. 16 independent experiments were conducted in drinking water, either pure or with the addition of acetate or dextrose. In most cases, the current increased and reached 1.5–9.5 times the initial current. The current increase was attributed to biofilm forming on the electrode in a similar way to that has been observed in seawater. Epifluorescence microscopy showed that the bacteria size and the biofilm morphology depended on the nutrients added, but no quantitative correlation between biofilm morphology and current was established. In compost, the oxidation process was investigated using a titanium based electrode under constant polarisation in the range 0.10–0.70 V/SCE. It was demonstrated that the indigenous micro-organisms were responsible for the current increase observed after a few days, up to 60 mA m)2. Adding 10 mM acetate to the compost amplified the current density to 145 mA m)2 at 0.50 V/SCE. The study suggests that many natural environments, other than marine sediments, waste waters and seawaters that have been predominantly investigated until now, may be able to produce electrochemically active biofilm

Back disorders and lumbar load in nursing staff in geriatric care: a comparison of home-based care and nursing homes

<p>Abstract</p> <p>Background</p> <p>Back pain is one of the most frequent complaints in the nursing profession. Thus, the 12-month prevalence of pain in the lumbar spine in nursing staff is as high as 76%. Only a few representative studies have assessed the prevalence rates of back pain and its risk factors among nursing staff in nursing homes in comparison to staff in home-based care facilities. The present study accordingly investigates the prevalence in the lumbar and cervical spine and determines the physical workload to lifting and caring in geriatric care.</p> <p>Methods</p> <p>1390 health care workers in nursing homes and home care participated in this cross sectional survey. The nursing staff members were examined by occupational physicians according to the principals of the multistep diagnosis of musculoskeletal disorders. Occupational exposure to daily care activities with patient transfers was measured by a standardised questionnaire. The lumbar load was calculated with the Mainz-Dortmund dose model. Information on ergonomic conditions were recorded from the management of the nursing homes. Comparisons of all outcome variables were made between both care settings.</p> <p>Results</p> <p>Complete documentation, including the findings from the occupational physicians and the questionnaire, was available for 41%. Staff in nursing homes had more often positive orthopaedic findings than staff in home care. At the same time the values calculated for lumbar load were found to be significant higher in staff in nursing homes than in home-based care: 45% vs. 6% were above the reference value. Nursing homes were well equipped with technical lifting aids, though their provision with assistive advices is unsatisfactory. Situation in home care seems worse, especially as the staff often has to get by without assistance.</p> <p>Conclusions</p> <p>Future interventions should focus on counteracting work-related lumbar load among staff in nursing homes. Equipment and training in handling of assistive devices should be improved especially for staff working in home care.</p

De l’apprentissage des archives pour une ethnologue (1974-2003)

De l’apprentissage des archives pour une ethnologue (1974-2003). L’auteur raconte dans quel contexte elle a participé, dans les Baronnies, à l’une des grandes enquêtes pluridisciplinaires menées en France, dans les années 1960-1970. À cette occasion, elle découvre à la fois le travail dans les archives et l’enquête de terrain. Au travers de l’étude de quelques cas, elle analyse et revisite en même temps les méthodes de travail qu’elle a progressivement mises au point. Elle insiste en particulier sur l’importance du travail en archives, qui nécessite un long apprentissage, mais permet de donner aux observations de terrain une profondeur historique et donc, d’enrichir la réflexion ethnologique.An ethnologist’s archival training (1974-2003). The author recounts the context in which she participated in one of the most important multidisciplinary surveys to be carried out in France, in the Baronnies region in the 1960s and 1970s. It was at this time that she learnt about both archive work and field investigations. Using several case studies, she analyses and at the same time looks again at the working methods she gradually perfected. In particular, she stresses the importance of archival work, which requires much training, but which gives field observations historical depth, thus enriching ethnological reflection

Soleil, tourisme et cuisine : 150 ans de restauration cannoise

Chaque restaurant diffère par sa localisation, son architecture, son service, la nature des mets servis et leur présentation afin de répondre à des clientèles spécifiques. La ville de Cannes en est une bonne illustration car au cours du temps, sa restauration s’est considérablement modifiée en fonction de clientèles bien différentes. Avant la première guerre mondiale, l’aristocratie fréquentait les palaces à la cuisine internationale ; pendant l’entre-deux-guerres, le triomphe de l’automobilisme et le développement du tourisme ont accompagné une relative démocratisation de la fréquentation et une gastronomie plus régionalisée ; enfin, la période actuelle se caractérise par un héliotropisme affirmé et une « méditerranéisation » de l’offre gastronomique. Pourtant, loin d’en profiter, la production locale est menacée par une urbanisation galopante. Pour suivre cette évolution, des études de terrain sont associées aux données fournies par les archives.Each restaurant is different from the others by its location, its architecture, its service appearence and quality of food in order to satisfy specific demands. Cannes has been choosen as an example because the town and its restaurants show clearly the impact of its different customers content since the midth of the 19th century. Before the first World War, aristocraty used to visit palaces with their international cooking; after the first and before the second World War, the triumph of automobilism and the developpement of travel for pleasure went along with a relative democratisation of the frequentation and a new interest for local food and cooking ; nowadays, we can observe the search for sunlight and the impact of mediterranean food. However, far to take advantage of these transformations, local agriculture suffers from an uncontrolled urbanization. In order to show this evolution field works are associated with local record

Membrane stains as an objective means to distinguish isolated inner and outer hair cells

The use of isolated cochlear outer and inner hair cells has become widespread. While the morphological features of these two cell types in general are sufficiently different to allow discrimination, there are situations where confusion can arise. Small outer hair cells, particularly when they are swollen or distorted, can take on an appearance suggestive of inner hair cells. We describe here two fluorescent membrane stains, 3,3'-dihexyloxacarbocyanine iodide and rhodamine B hexyl ester, as an objective means to distinguish between cochlear hair cell types. Both stains mark the subsurface cisternae of outer hair cells thereby delineating the cell outline, and the interior of the cell shows discrete structure. On the other hand, in inner hair cells, the outline of the cell is not resolved while the interior is diffusely fluorescent. Since the two probes have different excitation and emission wavelengths (fluorescein- and rhodamine-like, respectively), this staining procedure can even he used in the presence of another fluorescent marker (for example, a calcium-indicating dye) by appropriate choice of the membrane stain.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30921/1/0000591.pd

Structure and mechanics of supporting cells in the guinea pig organ of Corti.

The mechanical properties of the mammalian organ of Corti determine its sensitivity to sound frequency and intensity, and the structure of supporting cells changes progressively with frequency along the cochlea. From the apex (low frequency) to the base (high frequency) of the guinea pig cochlea inner pillar cells decrease in length incrementally from 75-55 µm whilst the number of axial microtubules increases from 1,300-2,100. The respective values for outer pillar cells are 120-65 µm and 1,500-3,000. This correlates with a progressive decrease in the length of the outer hair cells from >100 µm to 20 µm. Deiters'cell bodies vary from 60-50 µm long with relatively little change in microtubule number. Their phalangeal processes reflect the lengths of outer hair cells but their microtubule numbers do not change systematically. Correlations between cell length, microtubule number and cochlear location are poor below 1 kHz. Cell stiffness was estimated from direct mechanical measurements made previously from isolated inner and outer pillar cells. We estimate that between 200 Hz and 20 kHz axial stiffness, bending stiffness and buckling limits increase, respectively,~3, 6 and 4 fold for outer pillar cells, ~2, 3 and 2.5 fold for inner pillar cells and ~7, 20 and 24 fold for the phalangeal processes of Deiters'cells. There was little change in the Deiters'cell bodies for any parameter. Compensating for effective cell length the pillar cells are likely to be considerably stiffer than Deiters'cells with buckling limits 10-40 times greater. These data show a clear relationship between cell mechanics and frequency. However, measurements from single cells alone are insufficient and they must be combined with more accurate details of how the multicellular architecture influences the mechanical properties of the whole organ

Fertility disorders and pregnancy complications in hairdressers - a systematic review

<p>Abstract</p> <p>Background</p> <p>Hairdressers often come into contact with various chemical substances which can be found in hair care products for washing, dyeing, bleaching, styling, spraying and perming. This exposure can impair health and may be present as skin and respiratory diseases. Effects on reproduction have long been discussed in the literature.</p> <p>Method</p> <p>A systematic review has been prepared in which publications from 1990 to 2010 were considered in order to specifically investigate the effects on fertility and pregnancy. The results of the studies were summarised separately in accordance with the type of study and the examined events.</p> <p>Results</p> <p>A total of 2 reviews and 26 original studies on fertility disorders and pregnancy complications in hairdressers were found in the relevant databases, as well as through hand searches of reference lists. Nineteen different outcomes concerning fertility and pregnancy are analysed in the 26 original studies. Most studies looked into malformation (n = 7), particularly orofacial cleft. Two of them found statistically significant increased risks compared to five that did not. Small for gestational age (SGA), low birth weight (LBW) and spontaneous abortions were frequently investigated but found different results. Taken together the studies are inconsistent, so that no clear statements on an association between the exposure as a hairdresser and the effect on reproduction are possible. The different authors describe increased risks of infertility, congenital malformations, SGA, LBW, cancer in childhood, as well as effects from single substances.</p> <p>Conclusion</p> <p>On the basis of the identified epidemiological studies, fertility disorders and pregnancy complications in hairdressers cannot be excluded. Although the evidence for these risks is low, further studies on reproductive risks in hairdressers should be performed as there is a high public health interest.</p