Copper-Triggered Aggregation of Ubiquitin

Neurodegenerative disorders share common features comprising aggregation of misfolded proteins, failure of the ubiquitin-proteasome system, and increased levels of metal ions in the brain. Protein aggregates within affected cells often contain ubiquitin, however no report has focused on the aggregation propensity of this protein. Recently it was shown that copper, differently from zinc, nickel, aluminum, or cadmium, compromises ubiquitin stability and binds to the N-terminus with 0.1 micromolar affinity. This paper addresses the role of copper upon ubiquitin aggregation. In water, incubation with Cu(II) leads to formation of spherical particles that can progress from dimers to larger conglomerates. These spherical oligomers are SDS-resistant and are destroyed upon Cu(II) chelation or reduction to Cu(I). In water/trifluoroethanol (80∶20, v/v), a mimic of the local decrease in dielectric constant experienced in proximity to a membrane surface, ubiquitin incubation with Cu(II) causes time-dependent changes in circular dichroism and Fourier-transform infrared spectra, indicative of increasing β-sheet content. Analysis by atomic force and transmission electron microscopy reveals, in the given order, formation of spherical particles consistent with the size of early oligomers detected by gel electrophoresis, clustering of these particles in straight and curved chains, formation of ring structures, growth of trigonal branches from the rings, coalescence of the trigonal branched structures in a network. Notably, none of these ubiquitin aggregates was positive to tests for amyloid and Cu(II) chelation or reduction produced aggregate disassembly. The early formed Cu(II)-stabilized spherical oligomers, when reconstituted in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes and in POPC planar bilayers, form annular and pore-like structures, respectively, which are common to several neurodegenerative disorders including Parkinson's, Alzheimer's, amyotrophic lateral sclerosis, and prion diseases, and have been proposed to be the primary toxic species. Susceptibility to aggregation of ubiquitin, as it emerges from the present study, may represent a potential risk factor for disease onset or progression while cells attempt to tag and process toxic substrates

GabaA Receptors of Cerebellar Granule Cells in Culture: Explanation of Overall Insensitivity to Ethanol.

GABA-activated chloride currents were studied in cerebellar granule cells put in culture from neonatal rats. As previously described, 10 \ub5M GABA perfusion of these cells recorded by whole cell patch-clamp elicits chloride currents displaying a peak and a steady-state component. The two components were studied in the presence of 1 mM furosemide,1 \ub5M Zn2+ and a combination of the two in order to evaluate the contribution of the different types of GABAA receptors. Furosemide inhibits \u3b16 containing receptors whereas low levels of Zn2+ specifically block incomplete GABAA receptors made up of \u3b1 and \u3b2 subunits only. The results show that the peak component involves the following receptors: \u3b1x \u3b2y, 25%; \u3b11 \u3b2y \u3b32, 45%; \u3b16 \u3b2y \u3b32 plus \u3b11 \u3b16 \u3b2y \u3b32, 30%. The steady state component is made up by \u3b1x \u3b2y, 38%; \u3b11 \u3b2y \u3b4, 62%. Ethanol at relatively high concentration, 100 mM, slows further down the desensitization of \u3b11 \u3b2y \u3b4 receptors. The results indicate that the relative insensitivity to ethanol of GABAA receptors of neonatal cerebellar granule cells in culture is due to the absence of mature \u3b16 \u3b2y \u3b4 receptors, a major receptor brand involved in tonic inhibition

Only High Concentrations Of Ethanol Affect Gabaa Receptors Of Rat Cerebellum Granule Cells In Culture

In the experiments described in the present report, we evaluated the effects of ethanol on the activity of GABA(A) receptors of cerebellar granule cells in culture. Only very high ethanol concentrations (100-300 mM) showed a clear and significant stimulatory effect on the activity of such receptors. This result was unexpected. In fact, previous reports from other groups would have suggested high ethanol sensitivity of at least one population of GABA(A) receptors expressed by granule cells

Gabor\u2019s hologram in a modern perspective

We review Dennis Gabor\u2019s early results in light of more than fifty years of technological achievements, including the advent of CCD cameras and fast computers. By applying digital reading to one of the first holograms, we demonstrate the continuity between the classical technique and the digital implementation. This experiment can be used as a demonstration without needing the instrumentation of an optics laboratory

Un contributo alla consapevolezza nelle scelte alimentari, nell'ottica dell'educazione alla salute

Viene descritto un progetto di tirocinio realizzato all\u2019interno della SSIS per la formazione degli insegnanti. Il tema scelto riguarda l\u2019alimentazione, la cui educazione \ue8 indispensabile per i giovanissimi sempre pi\uf9 soggetti a mode importate e dannose per la salute. Vengono anche descritti esempi di lavoro in classe

Cogan syndrome

To lead ophthalmologists to consider Cogan syndrome when managing a patient presenting with keratitis or other ocular inflammation accompanied by sensorineural hearing loss. Methods. Seven patients affected by Cogan syndrome were studied: two males and five females, ranging from 27 to 65 years of age (mean age: 41 years). Subjects were evaluated for a period ranging from 22 to 46 months (mean follow up time: 29.2 months). All patients were treated with immunosuppressive drug combination therapy (IDCT). Results. Three patients were affected by classic Cogan syndrome (i.e., vestibuloauditory symptoms and later sensorineural hearing loss and interstitial keratitis). Four patients presented atypical Cogan syndrome (i.e., sensorineural hearing loss and chronic ocular inflammation such as uveitis, scleritis, conjunctivitis, retinal vasculitis, etc.). Four of these patients had a late diagnosis. Two of them were diagnosed when they already had a cochlear implant, one with bilateral deafness underwent cochlear implantation 1 year after the beginning of IDCT, one had severe bilateral hearing loss that improved during the first year of IDCT, and then rapidly worsened to total deafness in 1 month following an episode of severe systemic hypotension. Three patients who had an early diagnosis of Cogan syndrome had no worsening of vestibuloauditory dysfunction during the follow up period. Conclusion. Diagnosis of Cogan syndrome should not be overlooked by ophthalmologists in all patients with recurrent ocular inflammatory disease associated with vestibuloauditory symptoms. Early diagnosis is essential to commence the appropriate immunosuppressive therapy that may prevent permanent hearing loss and ocular dysfunctionPurpose. To lead ophthalmologists to consider Cogan syndrome when managing a patient presenting with keratitis or other ocular inflammation accompanied by sensorineural hearing loss. Methods. Seven patients affected by Cogan syndrome were studied: two males and live females, ranging from 27 to 65 years of age (mean age: 41 years). Subjects were evaluated for a period ranging from 22 to 46 months (mean follow up time: 29.2 months). All patients were treated with immunosuppressive drug combination therapy (IDCT). Results. Three patients Were affected by classic Cogan syndrome (i.e., vestibuloauditory symptoms and later sensorineural hearing loss and interstitial keratitis). Four patients presented atypical Cogan syndrome (i.e., sensorineural hearing loss and chronic ocular inflammation such as uveitis, scleritis, conjunctivitis, retinal vasculitis, etc.). Four of these patients had a late diagnosis. Two of them were diagnosed when they already had a cochlear implant, one with bilateral deafness underwent cochlear implantation I year after the beginning of IDCT, one had severe bilateral hearing loss that improved during the first year of IDCT, and then rapidly worsened to total deafness in 1 month following an episode of severe systemic hypotension. Three patients who had an early diagnosis of Cogan syndrome had no worsening of vestibuloauditory dysfunction during the follow up period. Conclusion. Diagnosis of Cogan syndrome should riot be overlooked by ophthalmologists in all patients with recurrent ocular inflammatory disease associated with vestibuloauditory symptoms. Early diagnosis is essential to commence the appropriate immunosuppressive therapy that may prevent permanent hearing loss and ocular dysfunction