Building sensory receptors on the tongue

Neurotrophins, neurotrophin receptors and sensory neurons are required for the development of lingual sense organs. For example, neurotrophin 3 sustains lingual somatosensory neurons. In the traditional view, sensory axons will terminate where neurotrophin expression is most pronounced. Yet, lingual somatosensory axons characteristically terminate in each filiform papilla and in each somatosensory prominence within a cluster of cells expressing the p75 neurotrophin receptor (p75NTR), rather than terminating among the adjacent cells that secrete neurotrophin 3. The p75NTR on special specialized clusters of epithelial cells may promote axonal arborization in vivo since its over-expression by fibroblasts enhances neurite outgrowth from overlying somatosensory neurons in vitro . Two classical observations have implicated gustatory neurons in the development and maintenance of mammalian taste buds—the early arrival times of embryonic innervation and the loss of taste buds after their denervation in adults. In the modern era more than a dozen experimental studies have used early denervation or neurotrophin gene mutations to evaluate mammalian gustatory organ development. Necessary for taste organ development, brain-derived neurotrophic factor sustains developing gustatory neurons. The cardinal conclusion is readily summarized: taste buds in the palate and tongue are induced by innervation. Taste buds are unstable: the death and birth of taste receptor cells relentlessly remodels synaptic connections. As receptor cells turn over, the sensory code for taste quality is probably stabilized by selective synapse formation between each type of gustatory axon and its matching taste receptor cell. We anticipate important new discoveries of molecular interactions among the epithelium, the underlying mesenchyme and gustatory innervation that build the gustatory papillae, their specialized epithelial cells, and the resulting taste buds.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47466/1/11068_2005_Article_3332.pd

MnO2nanomaterials functionalized with Ag and SnO2: An XPS study

The present study is devoted to the characterization of MnO2-Ag and MnO2-SnO2 nanocomposites of technological interest as gas sensors for food quality control and security applications. In particular, MnO2 nanomaterials were deposited on polycrystalline alumina substrates by plasma enhanced-chemical vapor deposition and functionalized with either Ag or SnO2 nanoparticles by means of radio frequency-sputtering. The target materials were investigated by a multitechnique approach, evidencing the successful formation of nanocomposites with tailored morphology, featuring an intimate contact of their components. Herein, the attention is dedicated to the characterization of system surface composition by x-ray photoelectron spectroscopy. Besides wide scan spectra, data obtained by the analysis of the C 1s, O 1s, Mn 2p, Mn 3s, Ag 3d, Sn 3d, and silver Auger signal spectral features are presented and critically discussed. The results highlight the occurrence of phase-pure MnO2 and SnO2 free from other Mn and Sn oxidation states and of appreciable silver surface oxidation in the target nanomaterials

Fe2O3-WO3 and Fe2O3-CuO nanoheterostructures by XPS

The detrimental effects of gaseous nitrogen oxides (NOx, with x = 1 and 2) on both human health and the environment have triggered efforts aimed at the development of solar-activated photocatalysts for their efficient removal. In this regard, Fe2O3-WO3 and Fe2O3-CuO nanoheterostructures were prepared by a two-step vapor phase route. In particular, chemical vapor deposition (CVD) of β-Fe2O3, a scarcely investigated iron(III) oxide polymorph, was followed by radio frequency-sputtering of WO3 or CuO under mild conditions. The adopted strategy enabled the obtainment of nanoheterostructures with a peculiar pyramidal morphology and a uniform dispersion of CuO or WO3 onto the pristine iron(III) oxide. In this work, the chemical composition of the target systems was investigated by means of x-ray photoelectron and x-ray excited-Auger electron spectroscopies. In addition to the identification of elemental chemical states, the reported results confirmed the formation of pure and O-deficient systems, in which the direct interplay between the single components opens the door to air purification using the developed systems as photocatalysts

The effects of the general anesthetic sevoflurane on neurotransmission: an experimental and computational study

The brain functions can be reversibly modulated by the action of general anesthetics. Despite a wide number of pharmacological studies, an extensive analysis of the cellular determinants of anesthesia at the microcircuits level is still missing. Here, by combining patch-clamp recordings and mathematical modeling, we examined the impact of sevoflurane, a general anesthetic widely employed in the clinical practice, on neuronal communication. The cerebellar microcircuit was used as a benchmark to analyze the action mechanisms of sevoflurane while a biologically realistic mathematical model was employed to explore at fine grain the molecular targets of anesthetic analyzing its impact on neuronal activity. The sevoflurane altered neurotransmission by strongly increasing GABAergic inhibition while decreasing glutamatergic NMDA activity. These changes caused a notable reduction of spike discharge in cerebellar granule cells (GrCs) following repetitive activation by excitatory mossy fibers (mfs). Unexpectedly, sevoflurane altered GrCs intrinsic excitability promoting action potential generation. Computational modelling revealed that this effect was triggered by an acceleration of persistent sodium current kinetics and by an increase in voltage dependent potassium current conductance. The overall effect was a reduced variability of GrCs responses elicited by mfs supporting the idea that sevoflurane shapes neuronal communication without silencing neural circuits

Fisiologia: Un approccio integrato, 2° ediz.

Vi sono oggi opportunità straordinarie per un proficuo studio delle funzioni del corpo umano. Questo dipende dal fatto che non solo beneficiamo di secoli di studi compiuti da fisiologi che hanno costruito un corpus di conoscenze sulle funzioni dell'organismo umano, ma anche dal fatto che negli anni '70 vi sono stati progressi nel campo della biologia cellulare e molecolare così spettacolari che gli studenti talvolta guardano alla fisiologia come a una materia 'morta', in cui non resta più nulla da scoprire. In effetti, un tempo si pensava che decodificando l'intero genoma umano avremmo avuto la chiave del segreto della vita. Tuttavia, questa visione riduzionista della biologia ha i suoi limiti. Gli organismi viventi sono molto più di una semplice somma di parti, e scoprire le sequenze di geni e proteine in un laboratorio di biologia molecolare non sempre ci chiarisce il loro significato biologico in vivo. Ora, alle soglie del XXI secolo, i biologi molecolari chiedono aiuto ai fisiologi per la comprensione della funzione delle molecole nell'organismo in toto. L'integrazione della funzione a tutti i livelli, dalla molecola all'organismo vivente, è compito precipuo dei fisiologi

Fisiologia: Un approccio integrato, 3° ediz.

Negli anni trascorsi dalla precedente edizione, la fisiologia e la medicina hanno continuato la loro rapida evoluzione. Man mano che gli scienziati acquisiscono nuove conoscenze dei processi biologici fondamentali, le loro scoperte sono tradotte in nuovi trattamenti medici e in suggerimenti pe mantenerre lo stato di salute. In questa edizione abbiamo continuato ad aggiornare e a focalizzare i temi di base e i concetti di fisiologia per aiutare gli studenti a stabilire un modello mentale su come funziona il corpo umano

KCNK channels in taste cells: possible new chemical sensors?

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FISH analysis in cell touch preparations and cytological specimens from formalin-fixed fetal autopsies.

Postmortem studies on still-borns and miscarriages are important to define the sex and eventually the morphologic anomalies correlated to chromosomal aberrations. When the conditions for carrying out a cytogenetic study do not exist, these chromosomal alterations can be investigated by nucleic acid fluorescent in situ hybridization (FISH), which can be performed on interphase nuclei, usually on formalin-fixed paraffin embedded tissues or on fresh cytological specimens. The objective of the present study is to prove whether this technique can be successfully applied to formalin-fixed cell touch preparations and cytological specimens obtained from foetal autopsies. The study was carried out 12 abortions some of which were spontaneous and some of which were therapeutic. The materials were formalin-fixed. Cell touch preparations and cytological specimens were obtained. The FISH was performed using X/Y probes (Vysis) and the Aneuvysion Kit (05J38-030, Vysis), the probes being for chromosomes 13/21 and X/Y/18. To verify the reliability of the technique, the same reactions were also performed on fresh analogous materials. The slides were evaluable, and the probes hybridized to interphase nuclei showed distinct signals. All the samples were adequate for FISH analysis without any notable difference in the results. Moreover, it is technically possible to perform this analysis not only on fresh but particularly on formalin-fixed cytological specimens. On the other hand, the use of this type of cytological samples, as compared to formalin-fixed and paraffin embedded tissue sections, has the advantage of presenting intact, noncut nuclei with preserved cytomorphology, avoiding the problems of overlapping nuclei and making the identification of the real chromosomal arrangement easier

Plasma\u2010assisted chemical vapor deposition of F\u2010doped MnO2 nanostructures on single crystal substrates

MnO2 nanostructures were fabricated by plasma assisted\u2010chemical vapor deposition (PA\u2010 CVD) using a fluorinated diketonate diamine manganese complex, acting as single\u2010source precursor for both Mn and F. The syntheses were performed from Ar/O2 plasmas on MgAl2O4(100), YAlO3(010), and Y3Al5O12(100) single crystals at a growth temperature of 300 \ub0C, in order to investigate the substrate influence on material chemico\u2010physical properties. A detailed characterization through complementary analytical techniques highlighted the formation of highly pure and oriented F\u2010doped systems, comprising the sole \u3b2\u2010MnO2 polymorph and exhibiting an inherent oxygen deficiency. Optical absorption spectroscopy revealed the presence of an appreciable Vis\u2010light harvesting, of interest in view of possible photocatalytic applications in pollutant degradation and hydrogen production. The used substrates directly affected the system structural features, as well as the resulting magnetic characteristics. In particular, magnetic force microscopy (MFM) measurements, sensitive to the out\u2010of\u2010plane magnetization component, highlighted the formation of spin domains and long\u2010range magnetic ordering in the developed materials, with features dependent on the system morphology. These results open the door to future engineering of the present nanostructures as possible magnetic media for integration in data storage devices

Quasi-1D MnO2 nanocomposites as gas sensors for hazardous chemicals

Quasi-1D MnO2 nanocomposite materials (A/MnO2 with A = CuO, SnO2) were developed by a two-step plasma-assisted process, involving the plasma enhanced-chemical vapor deposition (PE-CVD) of MnO2 nanomaterials and their functionalization with copper or tin oxides by radio frequency (RF)-sputtering. A thorough characterization by means of specific surface analytical techniques highlighted the formation of high purity nanocomposites, endowed with a controlled morphology and a tailored spatial dispersion of the functionalizing agents. The target materials were tested as gas sensors for the recognition of hazardous gases [H2 and di(propyleneglycol) monomethyl ether (DPGME) / dimethyl methyl phosphonate (DMMP), the latter used as simulants for chemical warfare agents]. Functional data evidenced the obtainment of low detection limits and promising gas responses, whose improvement with respect to the pristine MnO2 was traced back to the formation of built-in p-n and n-n junctions for CuO/MnO2 and SnO2/MnO2 systems, respectively. The possibility of discriminating between the target analytes depending on the functionalizing species already at moderate working temperatures demonstrates the potential of the developed materials for eventual gas sensing applications under real-world conditions