Search Results (7)

Background/Objectives: The traditional classification of astrocytes was based on morphological differences between astrocytes and their location in brain tissue. Astrocytes stained by impregnation techniques were divided into protoplasmic and fibrous astrocytes. We still use this classification, often supplemented by GFAP immunostaining. However, protoplasmic astrocytes have been found in the human cerebral cortex as GFAP-negative cells. Methods: In this study, astrocytes were identified using Cajal’s gold sublimation method and GFAP immunostaining. Biopsy samples of normal brain tissue (n = 25) were obtained from adult patients diagnosed with traumatic brain injury, stroke, gliomas and brain metastases. Results: In all samples, GFAP-positive fibrous astrocytes were found in the subpial region (layer I-I) and in the white matter. GFAP-positive protoplasmic astrocytes were absent or occurred only rarely in the cortical gray matter (layer III–VI) in samples from patients diagnosed with a tumor. Similar staining was also observed using the Cajal method. However, in samples from patients with traumatic brain injury accompanied by high intracranial pressure, GFAP-positive areas with numerous astrocytic processes and cells with a morphology similar to protoplasmic astrocytes were found. Conclusions: We can conclude that protoplasmic astrocytes are GFAP-negative cells that respond to brain injury by GFAP expression. We consider this finding to be a sign of protoplasmic astrocyte differentiation. On the other hand, fibrous astrocytes are GFAP-positive and respond to brain injury with increased GFAP expression. These results raise questions regarding the classification of astrocytes and, in particular, the histological visualization of the neuro-glial-vascular unit. Full article

Background: Although the definition of dietary fibre is complex and constantly evolving, today we can identify it as “carbohydrate polymers with at least 10 monomeric units, which are not hydrolysed in the small intestine of humans”. In addition to the numerous and well-known benefits of dietary fibre for human health, our attention is drawn to its antioxidant properties, achieved through polyphenolic compounds linked to polysaccharide complexes. This study investigated the antioxidant effects of an extract from the fruit of Punica granatum (PUN), particularly rich in polyphenols, fibre, flavonoids, vitamins, organic acids, minerals, amino acids, and alkaloids. Furthermore, these effects were evaluated in two human nervous system cell lines under oxidative stress induced by hydrogen peroxide. Methodology: After examining the fibre composition, some polyphenols present in the extract were identified and quantified by HPLC. Furthermore, the antioxidant power of PUN was measured using the DPPH method, the chelating activity assay, the reducing power test, the ORAC method, the measurement of reactive oxygen species accumulation, the quantification of lipid peroxidation, and the detection of mitochondrial superoxide in cell cultures. Results: The results were consistent, and PUN demonstrated a strong antioxidant potential, justified not only by the high content of easily extractable polyphenols (EPPs) but also by a further addition of these more difficult to identify compounds (NEPPs), indicated as “hidden polyphenols”; therefore, the total polyphenol content in the extract resulted from the sum of EPPs + NEPPs (71 ± 7.9 + 55 ± 6.4 mg = 126 ± 14.3 mg gallic acid equivalent (GAE)/g dry weight). The fraction of hidden polyphenols could therefore explain a mechanism by which the fibre exerts an antioxidant effect. Another important result was achieved by the cell lines used, both of which were significantly protected by PUN following oxidative damage generated by a pro-oxidant treatment. However, astrocytes were found to be more responsive and sensitive than were human neurons. At the same time, PUN mitigated the effects of oxidative damage, and it could be hypothesised that this extract could be used to extinguish the A1 phenotype. Conclusions: We can conclude that the fibrous component of pomegranate is related to the antioxidant property exerted, and the neurodegeneration caused by oxidative stress could be slowed following the intake of Punica granatum. It is possible to identify the pomegranate as a “superfood” or “functional food”, with excellent nutritional characteristics and chemical composition. Full article

In the mammalian isocortex, CD44, a cell surface receptor for extracellular matrix molecules, is present in pial-based and fibrous astrocytes of white matter but not in protoplasmic astrocytes. In the hominid isocortex, CD44+ astrocytes comprise the subpial “interlaminar” astrocytes, sending long processes into the cortex. The hippocampus also contains similar astrocytes. We have examined all levels of the human central nervous system and found CD44+ astrocytes in every region. Astrocytes in white matter and astrocytes that interact with large blood vessels but not with capillaries in gray matter are CD44+, the latter extending long processes into the parenchyma. Motor neurons in the brainstem and spinal cord, such as oculomotor, facial, hypoglossal, and in the anterior horn of the spinal cord, are surrounded by CD44+ processes, contrasting with neurons in the cortex, basal ganglia, and thalamus. We found CD44+ processes that intercalate between ependymal cells to reach the ventricle. We also found CD44+ astrocytes in the molecular layer of the cerebellar cortex. Protoplasmic astrocytes, which do not normally contain CD44, acquire it in pathologies like hypoxia and seizures. The pervasive and inducible expression of CD44 in astrocytes is a novel finding that lays the foundations for functional studies into the significance of CD44 in health and disease. Full article

The importance of polyamines (PAs) for the central nervous system (CNS) is well known. Less clear, however, is where PAs in the brain are derived from. Principally, there are three possibilities: (i) intake by nutrition, release into the bloodstream, and subsequent uptake from CNS capillaries, (ii) production by parenchymatous organs, such as the liver, and again uptake from CNS capillaries, and (iii) uptake of precursors, such as arginine, from the blood and subsequent local biosynthesis of PAs within the CNS. The present investigation aimed to unequivocally answer the question of whether PAs, especially the higher ones like spermidine (SPD) and spermine (SPM), can or cannot be taken up into the brain from the bloodstream. For this purpose, a biotin-labelled analogue of spermine (B-X-SPM) was synthesized, characterized, and used to visualize its uptake into brain cells following application to acute brain slices, to the intraventricular space, or to the bloodstream. In acute brain slices there is strong uptake of B-X-SPM into protoplasmic and none in fibrous-type astrocytes. It is also taken up by neurons but to a lesser degree. Under in vivo conditions, astrocyte uptake of B-X-SPM from the brain interstitial fluid is also intense after intraventricular application. In contrast, following intracardial injection, there is no uptake from the bloodstream, indicating that the brain is completely dependent on the local synthesis of polyamines. Full article

Background: Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) stress response protein that plays an important role in pancreatic functions. As both alcohol and ER stress response proteins are involved in the pathogenesis of pancreatitis, we sought to investigate the expression of MANF in chronic alcoholic pancreatitis (CAP) and chronic non-alcoholic pancreatitis (CNP). Methods: A cohort of chronic pancreatitis tissues was gathered from routine surgical pathology (n = 77) and autopsy (n = 10) cases and tissue microarrays were created. Sampled tissues were reviewed and designated as representing CAP (n = 15), CNP (n = 58), or normal pancreatic tissue (NPT) (n = 27). MANF immunohistochemistry (IHC) and digital image analysis were performed to obtain an estimation of tissue fibrosis and an optical density (OD) of MANF IHC in ducts and acini for each case. The averaged values for these variables among histologic designations were compared. Results: The amount of fibrous tissue of the combined CAP and CNP group (chronic alcoholic and non-alcoholic pancreatitis, CANP) exceeded that of the NPT group (70% vs. 34%, p < 0.0001). The MANF OD in ducts of CANP was significantly higher than that of NPT (0.19 vs. 0.10, p < 0.05). The MANF OD in ducts of CAP was significantly higher than that of CNP (0.27 vs. 0.17, p < 0.05). The MANF OD in acini of CAP was significantly lower than that in CNP (0.81 vs. 1.05, p < 0.05). Finally, there was a statistically significant positive relationship between the amount of fibrosis and MANF OD in ducts (p < 0.001). Conclusions: MANF expression was higher in ducts of CAP than CNP. In contrast, MANF expression in acini was lower in CAP than CNP and NPT. There was a positive correlation between fibrosis and MANF levels in the ducts. Full article

Based on their morphology, the most abundant cells within the nervous tissue of the central nervous system, astrocytes, can be divided into two types, protoplasmic astrocytes and fibrous astrocytes. A further analysis of the brain tissue with the preserved astrocytes from the human principal olivary nucleus, based on their morphological differences with age, is successfully performed in this paper. Moreover, the images of 294 astrocytes, 148 fibrous and 146 protoplasmic, from the principal olivary nucleus were used. Applied for the first time in astrocytes image analysis, the principal component analysis was used to find the most informative parameters among geometrical and fractal in each of the four predefined groups, i.e., categories, of the morphological measurements of astrocytes in the images. The proposed subsets representing different morphological features can be used to distinguish astrocyte subtypes and predict their changes during normal aging. The values of the adequated parameters in different subsets were compared between the fibrous and protoplasmic astrocytes and correlated with age. Significant differences (p < 0.05) between the two subtypes were found in four Euclidean and four monofractal parameters. In addition, significant correlations were found between selected parameters and the age of subjects. In the upcoming iterations of this procedure, possible refinement and upgrades are expected. Full article

In this work, we design and produce micron-sized fiber mats by blending poly(ε-caprolactone) (PCL) with small amounts of block copolymers poly(ethylene oxide)_m-block-poly(ε-caprolactone)_n (PEO_m-b-PCL_n) using electrospinning. Three different PEO_m-b-PCL_n block copolymers, with different molecular weights of PEO and PCL, were synthesized by ring opening polymerization of ε-caprolactone using PEO as initiator and stannous octoate as catalyst. The polymer blends were prepared by homogenous solvent mixing using dichloromethane for further electrospinning procedures. After electrospinning, it was found that the addition to PCL of the different block copolymers produced micron-fibers with smaller width, equal or higher hydrophilicity, lower Young modulus, and rougher surfaces, as compared with micron-fibers obtained only with PCL. Neural stem progenitor cells (NSPC), isolated from rat brains and grown as neurospheres, were cultured on the fibrous materials. Immunofluorescence assays showed that the NSPC are able to survive and even differentiate into astrocytes and neurons on the synthetic fibrous materials without any growth factor and using the fibers as guidance. Disassembling of the cells from the NSPC and acquisition of cell specific molecular markers and morphology progressed faster in the presence of the block copolymers, which suggests the role of the hydrophilic character and porous topology of the fiber mats. Full article