222 research outputs found
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Hyperspectral analysis applied to micro-Brillouin maps of amyloid-beta plaques in Alzheimer’s disease brains
A recent investigation on the architecture and chemical composition of amyloid-β (Aβ) plaques in ex vivo
histological sections of an Aβ-overexpressing transgenic mouse hippocampus has shed light on the infrared
light signature of cell-activation related biomarkers of Alzheimer’s disease. A correlation was highlighted
between the biomechanical properties detected by Brillouin microscopy and the molecular make-up of Aβ
plaques provided by FTIR spectroscopic imaging and Raman microscopy (with correlative immunofluorescence
imaging) in this animal model of the disease. In the Brillouin spectra of heterogeneous materials such
as biomedical samples, peaks are likely the result of multiple contributions, more or less overlaid on a spatial
and spectral scale. The ability to disentangle these contributions is very important as it may give access to
discrete components that would otherwise be buried within the Brillouin peak envelope. Here, we applied
an unsupervised non-negative matrix factorization method to analyse the spontaneous Brillouin microscopy
maps of Aβ plaques in transgenic mouse hippocampal sections. The method has already been proven successful
in decomposing chemical images and is applied here for the first time to acoustic maps acquired
with a Fabry–Perot Brillouin microscope. We extracted and visualised a decrease in tissue rigidity from the
core through to the periphery of the plaque, with spatially distinct components that we assigned to specific
entities. This work demonstrates that it is possible to reveal the structure and mechanical properties of Aβ
plaques, with details visualized by the projection of the mechanical contrast into a few relevant channels
10 khz shifted-excitation Raman difference spectroscopy with charge-shifting charge-coupled device read-out for effective mitigation of dynamic interfering backgrounds
In this work we demonstrate an advanced concept of a charge-shifting charge-coupled device (CCD) read-out combined with shifted excitation Raman difference spectroscopy (SERDS) capable of operating at up to 10 kHz acquisition rates for the effective mitigation of fast-evolving interfering backgrounds in Raman spectroscopy. This rate is 10-fold faster than that achievable with an instrument we described previously and is overall 1000-fold faster than possible with conventional spectroscopic CCDs capable of operating at up to ∼10 Hz rates. The speed enhancement was realized by incorporating a periodic mask at the internal slit of an imaging spectrometer permitting a smaller shift of the charge on the CCD (8 pixels) to be required during the cyclic shifting process compared with the earlier design which employed an 80-pixel shift. The higher acquisition speed enables the more accurate sampling of the two SERDS spectral channels, enabling it to effectively tackle highly challenging situations with rapidly evolving interfering fluorescence backgrounds. The performance of the instrument is evaluated for heterogeneous fluorescent samples which are moved rapidly in front of the detection system aiming at the differentiation of chemical species and their quantification. The performance of the system is compared with that of the earlier 1 kHz design and a conventional CCD operated at its maximum rate of 5.4 Hz as previously. In all situations tested, the newly developed 10 kHz system outperformed the earlier variants. The 10 kHz instrument can benefit a number of prospective applications including: disease diagnosis where high sensitivity mapping of complex biological matrices in the presence of natural fluorescence bleaching restricts achievable limits of detection; accurate data acquisition from moving heterogeneous samples (or moving a handheld instrument in front of the sample during data acquisition) or data acquisition under varying ambient light conditions (e.g., due to casting shadows, sample or instrument movement). Other beneficial scenarios include monitoring rapidly evolving Raman signals in the presence of largely static background signals such as in situations where a heterogeneous sample is moving rapidly in front of a detection system (e.g., a conveyor belt) in the presence of static ambient light
Towards nZEBs : experiences in Italy
Nowadays in the European framework the good practices for high-performing buildings realization and retrofitting are copious, but what emerges is the lack of information and data sharing about them. There are indeed no official sources for notes deriving from this kind of buildings and, moreover, there is shortage of quantitative and comparable data. In a process oriented to a large-scale diffusion of nZEBs on the market, the existing good practices of actual case studies of highperforming buildings should be kept as market benchmarks and reveal to be precious sources of information. In the light of the above, the need of a harmonized database to collect and share data deriving from different building typologies and climatic zones plays a fundamental role. Due to the weakness of the existing databases and to the necessity of having practical guidelines to design nZEBs, at Italian level, an AiCARR teamwork is targeting the development of a design guide for nZEBs in Mediterranean region, based on different national experiences. In order to reach this target the workgroup has created a detailed database, useful to collect and share information about single high-performing buildings. Its main purpose is to record nZEBs, which have been already built, with available monitored data and that represent concrete models for future designing. Because of the still scarcity of monitored nZEBs, the database is suitable not only for realized monitored buildings but also for those that are still in a design phase. Actually, three different Italian case studies are catalogued in the databas
Missense PDSS1 mutations in CoenzymeQ10 synthesis cause optic atrophy and sensorineural deafness
CoenzymeQ10 is one of the main cellular antioxidants and an essential lipid involved in numerous cell reactions, such as energy production and apoptosis modulation. A large number of enzymes are involved in CoQ10 biosynthesis. Mutations in the genes encoding for these enzymes cause a CoQ10 deficiency, characterized by neurological and systemic symptoms. Here we describe two young sisters with sensorineural deafness followed by optic atrophy, due to a novel homozygous pathogenic variant in PDSS1. The visual system seems to be mainly involved when the first steps of CoQ10 synthesis are impaired (PDSS1, PDSS2, and COQ2 deficiency)
New insights into irritable bowel syndrome pathophysiological mechanisms: contribution of epigenetics
Irritable bowel syndrome (IBS) is a complex multifactorial condition including alterations of the gut-brain axis, intestinal permeability, mucosal neuro-immune interactions, and microbiota imbalance. Recent advances proposed epigenetic factors as possible regulators of several mechanisms involved in IBS pathophysiology. These epigenetic factors include biomolecular mechanisms inducing chromosome-related and heritable changes in gene expression regardless of DNA coding sequence. Accordingly, altered gut microbiota may increase the production of metabolites such as sodium butyrate, a prominent inhibitor of histone deacetylases. Patients with IBS showed an increased amount of butyrate-producing microbial phila as well as an altered profile of methylated genes and micro-RNAs (miRNAs). Importantly, gene acetylation as well as specific miRNA profiles are involved in different IBS mechanisms and may be applied for future diagnostic purposes, especially to detect increased gut permeability and visceromotor dysfunctions. In this review, we summarize current knowledge of the role of epigenetics in IBS pathophysiology
A time-course Raman spectroscopic analysis of spontaneous in vitro microcalcifications in a breast cancer cell line
Microcalcifications are early markers of breast cancer and can provide valuable prognostic information to support clinical decision-making. Current detection of calcifications in breast tissue is based on X-ray mammography, which involves the use of ionizing radiation with potentially detrimental effects, or MRI scans, which have limited spatial resolution. Additionally, these techniques are not capable of discriminating between microcalcifications from benign and malignant lesions. Several studies show that vibrational spectroscopic techniques are capable of discriminating and classifying breast lesions, with a pathology grade based on the chemical composition of the microcalcifications. However, the occurrence of microcalcifications in the breast and the underlying mineralization process are still not fully understood. Using a previously established model of in vitro mineralization, the MDA-MB-231 human breast cancer cell line was induced using two osteogenic agents, inorganic phosphate (Pi) and β-glycerophosphate (βG), and direct monitoring of the mineralization process was conducted using Raman micro-spectroscopy. MDA-MB-231 cells cultured in a medium supplemented with Pi presented more rapid mineralization (by day 3) than cells exposed to βG (by day 11). A redshift of the phosphate stretching peak for cells supplemented with βG revealed the presence of different precursor phases (octacalcium phosphate) during apatite crystal formation. These results demonstrate that Raman micro-spectroscopy is a powerful tool for nondestructive analysis of mineral species and can provide valuable information for evaluating mineralization dynamics and any associated breast cancer progression, if utilized in pathological samples
Comparative expression pathway analysis of human and canine mammary tumors
<p>Abstract</p> <p>Background</p> <p>Spontaneous tumors in dog have been demonstrated to share many features with their human counterparts, including relevant molecular targets, histological appearance, genetics, biological behavior and response to conventional treatments. Mammary tumors in dog therefore provide an attractive alternative to more classical mouse models, such as transgenics or xenografts, where the tumour is artificially induced. To assess the extent to which dog tumors represent clinically significant human phenotypes, we performed the first genome-wide comparative analysis of transcriptional changes occurring in mammary tumors of the two species, with particular focus on the molecular pathways involved.</p> <p>Results</p> <p>We analyzed human and dog gene expression data derived from both tumor and normal mammary samples. By analyzing the expression levels of about ten thousand dog/human orthologous genes we observed a significant overlap of genes deregulated in the mammary tumor samples, as compared to their normal counterparts. Pathway analysis of gene expression data revealed a great degree of similarity in the perturbation of many cancer-related pathways, including the 'PI3K/AKT', 'KRAS', 'PTEN', 'WNT-beta catenin' and 'MAPK cascade'. Moreover, we show that the transcriptional relationships between different gene signatures observed in human breast cancer are largely maintained in the canine model, suggesting a close interspecies similarity in the network of cancer signalling circuitries.</p> <p>Conclusion</p> <p>Our data confirm and further strengthen the value of the canine mammary cancer model and open up new perspectives for the evaluation of novel cancer therapeutics and the development of prognostic and diagnostic biomarkers to be used in clinical studies.</p
The relevance of mitochondrial DNA variants fluctuation during reprogramming and neuronal differentiation of human iPSCs
The generation of inducible pluripotent stem cells (iPSCs) is a revolutionary technique allowing production of pluripotent patient-specific cell lines used for disease modeling, drug screening, and cell therapy. Integrity of nuclear DNA (nDNA) is mandatory to allow iPSCs utilization, while quality control of mitochondrial DNA (mtDNA) is rarely included in the iPSCs validation process. In this study, we performed mtDNA deep sequencing during the transition from parental fibroblasts to reprogrammed iPSC and to differentiated neuronal precursor cells (NPCs) obtained from controls and patients affected by mitochondrial disorders. At each step, mtDNA variants, including those potentially pathogenic, fluctuate between emerging and disappearing, and some having functional implications. We strongly recommend including mtDNA analysis as an unavoidable assay to obtain fully certified usable iPSCs and NPCs.Peer reviewe
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Viscoelasticity of amyloid plaques in transgenic mouse brain studied by Brillouin microspectroscopy and correlative Raman analysis
Amyloidopathy is one of the most prominent hallmarks of Alzheimer’s disease (AD), the leading cause of dementia worldwide, and is characterized by the accumulation of amyloid plaques in the brain parenchyma. The plaques consist of abnormal deposits mainly composed of an aggregation-prone protein fragment, β-amyloid 1-40/1-42, into the extracellular matrix. Brillouin microspectroscopy is an all-optical contactless technique that is based on the interaction between visible light and longitudinal acoustic waves or phonons, giving access to the viscoelasticity of a sample on a subcellular scale. Here, we describe the first application of micromechanical mapping based on Brillouin scattering spectroscopy to probe the stiffness of individual amyloid plaques in the hippocampal part of the brain of a β-amyloid overexpressing transgenic mouse. Correlative analysis based on Brillouin and Raman microspectroscopy showed that amyloid plaques have a complex structure with a rigid core of β-pleated sheet conformation (β-amyloid) protein surrounded by a softer ring-shaped region richer in lipids and other protein conformations. These preliminary results give a new insight into the plaque biophysics and biomechanics, and a valuable contrast mechanism for the study and diagnosis of amyloidopathy
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