Pure spastic paraparesis associated with a novel presenilin 1 R278K mutation.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
R Borghi
Publications and source records attributed to R Borghi.
Increase of cdk5 is related to neurofibrillary pathology in progressive supranuclear palsy.
BACKGROUND: Progressive supranuclear palsy (PSP) is characterized by a pure neurofibrillary tau pathology involving mainly basal ganglia and brainstem nuclei. In addition to a haplotype of the tau gene potentially favoring tau aggregation, lipoperoxidation has been shown to be associated with PSP tau pathology. OBJECTIVE: To analyze cdk5/p35 complex, a kinase that regulates neurite outgrowth, as a potential cellular mechanism underlying tau phosphorylation in brain tissues from PSP and control cases and comparatively in cerebral cortex from subjects with AD. METHODS: Cdk5/p35 protein levels and distribution were evaluated by immunoblotting and immunocytochemistry in brain regions from seven PSP, six AD, and seven control cases, with similar postmortem intervals. RESULTS: Total cdk5 protein levels were significantly increased by more than threefold in PSP tissue and were augmented in PSP neurons, codistributed with tau immunoreactivity. P35, the regulatory subunit of cdk5, was degraded by postmortem proteolysis to the same extent in PSP, AD, and control tissues. CONCLUSIONS: The proteolysis in vivo of p35, the regulatory subunit of the kinase, is not ascertainable because it is masked by its postmortem degradation. The study, however, indicates that in PSP, the alteration of cdk5 is different from that described in AD and suggests that the absence of amyloid beta protein deposition may account for the different pathways responsible for the same kinase activation.
Aged↗
Relationship between elegant Laguerre-Gauss and Bessel-Gauss beams.
We show that the elegant Laguerre-Gauss light beams of high radial order n are asymptotically equal to Bessel-Gauss light beams. The Bessel-Gauss beam equivalent to each elegant Laguerre-Gauss beam is found and shown to have almost identical propagation factors M2. In the limit n-->infinity, elegant Laguerre-Gauss beams can be identified with Durnin's Bessel beam. Our results suggest a new experimental procedure for generating light beams with nondiffractinglike properties directly from the output of a stable resonator.
Journal Article↗
Gaussian Schell-model beams propagating through polarization gratings.
The effects of polarization gratings on partially coherent beams are investigated by studying a Gaussian Schell-model beam impinging on a linear polarizer whose transmission axis varies periodically along one transverse direction. Analytical expressions for the beam polarization-coherence matrix after the grating are obtained. In particular, the evolution of the degree of polarization upon propagation is analyzed. Different behaviors of the output beam, depending on the beam parameters and on the period of the grating, are exhibited. In particular, it is shown that, by suitably choosing the latter quantities, it is possible to obtain not only any desirable value of the degree of polarization of the output beam but also particular distributions of such parameters across the transverse sections of the beam.
Journal Article↗
Nonparaxial Bessel-Gauss beams.
We study the nonparaxial propagation of Bessel-Gauss beams of any order. Closed-form expressions of all corrections to be added to the solution that is pertinent to the corresponding paraxial problem are found. Such corrections are expressed in terms of two families of polynomials, defined through recurrence rules, that encompass the Laguerre-Gauss polynomials for the particular case of a fundamental Gaussian beam. Numerical examples are shown.
Journal Article↗
Elegant Laguerre-Gauss beams as a new tool for describing axisymmetric flattened Gaussian beams.
A new superposition scheme for representing flattened Gaussian (FG) beams is proposed. Such a representation, unlike the original proposed by Gori [Opt. Commun. 107, 335 (1994)], is based on an expansion in terms of the so-called elegant Laguerre-Gaussian beams. This new representation allows us to obtain the closed-form expression of a FG beam of any order propagating through a paraxial ABCD optical system by means of a simple recurrence rule, which turns out to be particularly stable even when it is applied to FG beams of very high orders (> 10(4)).
Journal Article↗
Full length alpha-synuclein is present in cerebrospinal fluid from Parkinson's disease and normal subjects.
Several clues suggest that alpha-synuclein, a presynaptic protein, plays a central role in the pathogenesis of idiopathic Parkinson's disease (PD). To search a peripheral marker of PD, we analyzed presence and amount of alpha-synuclein in CSF from 12 PD patients and 10 neurologically normal subjects. The protein was extracted from CSF samples through immunoprecipitation and immunoblotting with different specific anti-alpha-synuclein antibodies. We identified a 19 kDa band that corresponds to monomeric alpha-synuclein, given its comigration with homologue human recombinant peptide as well as with the protein extracted from cerebral cortex of normal subjects. The amount of CSF 19 kDa alpha-synuclein did not significantly vary in PD and normal cases. These findings have two implications: (a) full length alpha-synuclein is released by neurons in the extracellular space; (b) alpha-synuclein does not appear a peripheral marker of PD pathology.
Biomarkers↗
Oxidative stress induces increase in intracellular amyloid beta-protein production and selective activation of betaI and betaII PKCs in NT2 cells.
Amyloid beta-protein (Abeta) aggregation produces an oxidative stress in neuronal cells that, in turn, may induce an amyloidogenic shift of neuronal metabolism. To investigate this hypothesis, we analyzed intra- and extracellular Abeta content in NT2 differentiated cells incubated with 4-hydroxy-2,3-nonenal (HNE), a major product of lipid peroxidation. In parallel, we evaluated protein kinase C (PKC) isoenzymes activity, a signaling system suspected to modulate amyloid precursor protein (APP) processing. Low HNE concentrations (0.1-1 microM) induced a 2-6 fold increase of intracellular Abeta production that was concomitant with selective activation of betaI and betaII PKC isoforms, without affecting either cell viability or APP full-length expression. Selective activation of the same PKC isoforms was observed following NT2 differentiation. Our findings suggest that PKC beta isoenzymes are part of cellular mechanisms that regulate production of the intracellular Abeta pool. Moreover, they indicate that lipid peroxidation fosters intracellular Abeta accumulation, creating a vicious neurodegenerative loop.
Amyloid beta-Peptides↗
Few-optical-cycle bessel-gauss pulsed beams in free space
We introduce a new family of nonseparable, pulselike and beamlike solutions of the wave equation in the paraxial approximation with pseudonondiffracting behavior. They are the pulsed versions of the Bessel-Gauss beams by Gori et al., and encompass as particular cases the diffraction-free Bessel-X pulses, isodiffracting pulses, and, in the many-cycle limit, Bessel and Gaussian beams. Unlike Bessel-X waves, these solutions carry finite energy but retain nondiffracting behavior over a finite propagation distance, and could be physically produced with mode-locked toroidal resonators.
Journal Article↗
Diffractive variable beam splitter: optimal design.
The analytical expression of the phase profile of the optimum diffractive beam splitter with an arbitrary power ratio between the two output beams is derived. The phase function is obtained by an analytical optimization procedure such that the diffraction efficiency of the resulting optical element is the highest for an actual device. Comparisons are presented with the efficiency of a diffractive beam splitter specified by a sawtooth phase function and with the pertinent theoretical upper bound for this type of element.
Equipment Design↗