Morphological analysis of the Hippocampal region of aged rats, role of Clasmatodendrosis

Clasmatodendrosis is a phenomenon first described by Alzheimer in 1910, which was observed in aged nervous system and in the course of neurodegenerative diseases. It consists in the loss of astrocytic distal processes. The occurrence of clasmatodendrosis is frequently associated with an increase of autofluorescent aggregates in different cell types of nervous tissue. In this study we designed a calibrated excitation/emission method of spectral unmixing aimed to discriminate the fluorescence emitted by commercial fluorochrome-conjugated antibodies from the autofluorescent signal, by using confocal microscopy and multiphoton fluorescence lifetime imaging techniques. By this method, the immunolabeled GFAP localization in the CA1 Hippocampal region of aged rats was analyzed. Autofluorescent debris showed a strong positivity to GFAP labeling, suggesting that the detached fragments of clasmatodendrotic astrocytes might take part in the generation of these structures. By 3D confocal analysis we found that these aggregates, were located on neuronal cell surfaces, as well as inside the soma and that, in addition, the presence of autofluorescent aggregates seemed to be related with increased adhesion phenomena among neurons. These data were compared with those obtained in control adult rats and in rats infused with lipopolysaccharide (LPS) in the 4th ventricle to induce a chronic inflammatory state. The presence of autofluorescent aggregates was detected in LPS rats and also in control rats, even if they appeared smaller and with a lesser intensity as compared with the aged rats. These findings suggest that clasmatodendrosis is a process involving the interaction of neurons and astrocytes in a prolonged timespan of life. Its severity increases with aging or under inflammatory and/or neurodegenerative diseases. In conclusion, our results seem to suggest that clasmatodendrosis can affect neuron functionality not only due to a decreased astrocyte activity, but also by direct interaction of the detached astrocytic fragments with neuron somata

Three-dimensional mapping of the orientation of collagen corneal lamellae in healthy and keratoconic human corneas using SHG microscopy

SHG image acquired with sagittal optical sectioning (A) of a healthy cornea and (B) of a keratoconic cornea. Scale bars: 30 μm. Keratoconus is an eye disorder that causes the cornea to take an abnormal conical shape, thus impairing its refractive functions and causing blindness. The late diagnosis of keratoconus is among the principal reasons for corneal surgical transplantation. This pathology is characterized by a reduced corneal stiffness in the region immediately below Bowman's membrane, probably due to a different lamellar organization, as suggested by previous studies. Here, the lamellar organization in this corneal region is characterized in three dimensions by means of second-harmonic generation (SHG) microscopy. In particular, a method based on a three-dimensional correlation analysis allows to probe the orientation of sutural lamellae close to the Bowman's membrane, finding statistical differences between healthy and keratoconic samples. This method is demonstrated also in combination with an epi-detection scheme, paving the way for a potential clinical ophthalmic application of SHG microscopy for the early diagnosis of keratoconus

Comparative study of different functionalized graphene-nanoplatelet aqueous nanofluids for solar energy applications

The optical properties of nanofluids are peculiar and interesting for a variety of applications. Among them, the high light extinction coefficient of nanofluids can be useful in linear parabolic concentrating solar systems, while their properties under high light irradiation intensities can be exploited for direct solar steam generation. The optical characterization of colloids, including the study of non-linear optical properties, is thus a needed step to design the use of such novel materials for solar energy exploitation. In this work, we analysed two different types of nanofluids, consisting of polycarboxylate chemically modified graphene nanoplatelets (P-GnP) and sulfonic acid-functionalized graphene nanoplatelets (S-GnP) dispersed in water, at three concentrations from 0.005 wt% to 0.05 wt%. Moderately stable nanofluids were achieved with favourable light extinction properties, as well as a non-linear optical behaviour under high input solar intensities

The conformational state of hERG1 channels determines integrin association, downstream signaling, and cancer progression

Ion channels regulate cell proliferation, differentiation, and migration in normal and neoplastic cells through cell-cell and cell-extracellular matrix (ECM) transmembrane receptors called integrins. K+ flux through the human ether-\ue0-gogo- related gene 1 (hERG1) channel shapes action potential firing in excitable cells such as cardiomyocytes. Its abundance is often aberrantly high in tumors, where it modulates integrin-mediated signaling. We found that hERG1 interacted with the \u3b21 integrin subunit at the plasma membrane of human cancer cells. This interaction was not detected in cardiomyocytes because of the presence of the hERG1 auxiliary subunit KCNE1 (potassium voltage-gated channel subfamily E regulatory subunit 1), which blocked the \u3b21 integrin-hERG1 interaction. Although open hERG1 channels did not interact as strongly with \u3b21 integrins as did closed channels, current flow through hERG1 channelswas necessary to activate the integrin-dependent phosphorylation of Tyr397 in focal adhesion kinase (FAK) in both normal and cancer cells. In immunodeficient mice, proliferation was inhibited in breast cancer cells expressing forms of hERG1 with impaired K+ flow, whereas metastasis of breast cancer cells was reduced when the hERG1/\u3b21 integrin interaction was disrupted. We conclude that the interaction of \u3b21 integrins with hERG1 channels in cancer cells stimulated distinct signaling pathways that depended on the conformational state of hERG1 and affected different aspects of tumor progression

A comprehensive physical profile for aqueous dispersions of carbon derivatives as solar working fluids

The application of nanofluids in direct solar absorption, heat transfer or direct solar steam generation entails carrying out a comprehensive study taking into account several physical quantities. Long-term stability, rheological, thermophysical and optical properties of dispersions must be known to assess their potential for envisaged applications. Two low-concentration nanofluids, 0.005 and 0.05 wt%, of sulfonic acid-functionalized and polycarboxylate chemically modified graphene nanoplatelets in water were considered in this work. Elemental analyses of the nanopowders and pH evaluations of the colloids were carried out. The rheological behaviour of dispersions at different temperatures was studied by rotational rheometry. Thermal conductivities were measured by the transient hot wire method and densities by the oscillating U-tube technique. Additionally, a brief report of the optical properties was included to provide a comprehensive physical analysis.Ministerio de Economía, Industria y Competitividad (España) | Ref. ENE2017-86425-C2-1-REuropean Commissio