1,720,998 research outputs found
Components of the cytosolic and released virtosomes from stimulated and non-stimulated human lymphocytes
No full textThis work intends to analyse the structure and the composition of virtosomes and their role. Background: Virtosomes are newly synthesized DNA-RNA-lipoprotein complexes released from living cells in a regulated and energy-dependent manner. Methods: Virtosome fractions were isolated by ultracentrifugation from human lymphocytes cytoplasm and from culture medium before and after stimulation with phitoemoagglutinin (PHA). The composition in DNA, RNA, protein and lipids was determined. The virtosomes present in the culture medium were put in contact with lymphocytes. Results: Virtosome fractions released from non-stimulated lymphocytes are shown to reduce replication of stimulated lymphocytes and those from stimulated lymphocytes to increase multiplication of non-stimulated lymphocytes. Biochemical analyses of the virtosomal complexes have shown that those from stimulated lymphocytes have five proteins that are absent from non-stimulated virtosome fractions. A comparison of the cytosolic versus released virtosome fractions from non-stimulated lymphocytes indicated that there is a greater percentage of phospholipids in the released virtosomes with a corresponding decrease in the percentage of protein. Conclusion: Although there is a presence of cholesterol in the virtosomes, the low levels of phosphatidylcholine and cholesterol, together with the low ratios of cholesterol: phospholipids leads to a confirmation of the apparent lack of a limiting membrane around the virtosomes. General significance: Virtosomes are structural particles formed in the cytoplasm, released from the cells and capable to be transferred in other cells influencing their behaviour
A possible role of cholesterol-sphingomyelin/phosphatidylcholine in nuclear matrix during rat liver regeneration
No full textPhospholipids and cholesterol in chromatin have been previously demonstrated. The lipid fraction changes during cell proliferation in relation to activation of enzymes of phospholipid metabolism. The aim of the present work is to clarify if chromatin lipids may derive or not from nuclear matrix and if they have different roles
Nuclear Phosphatidylcholine and Sphingomyelin Metabolism of Thyroid Cells Changes during Stratospheric Balloon Flight
Full text linkNuclear sphingomyelin and phosphatidylcholine metabolism is involved in the response to ultraviolet radiation treatment in different ways related to the physiological state of cells. To evaluate the effects of low levels of radiation from the stratosphere on thyroid cells, proliferating and quiescent FRTL-5 cells were flown in a stratospheric balloon (BIRBA mission). After recovery, the activity of neutral sphingomyelinase, phosphatidylcholine-specific phospholipase C, sphingomyelin synthase, and reverse sphingomyelin synthase was assayed in purified nuclei and the nuclei-free fraction. In proliferating FRTL-5, space radiation stimulate nuclear neutral sphingomyelinase and reverse sphingomyelin synthase activity, whereas phosphatidylcholine-specific phospholipase C and sphingomyelin synthase were inhibited, thus inducing sphingomyelin degradation and phosphatidylcholine synthesis. This effect was lower in quiescent cells. The possible role of nuclear lipid metabolism in the thyroid damage induced by space radiations is discusse
Plasmalogens in rat liver chromatin: New molecules involved in cell proliferation
No full textA minor component of chromatin, the phospholipid fraction, changes during cell cycle as result of the activation of intranuclear lipid metabolism enzymes including phosphatidylcholine-dependent phospholipase C activity. It is known that this enzyme maybe activated by phosphatidylcholine plasmalogen (Plg). Until now, there has been little evidences for the presence of Plgs inside the nucleus. The aim of our study is to ascertain if they are present in the nucleus and are responsible of the activation of phosphatidylcholine-dependent phospholipase C during cell proliferation and apoptosis. Therefore, we have analysed the Plg composition of the whole homogenate, cytosol, nuclei and chromatin of hepatocytes. The phosphatidylcholine-dependent phospholipase C activity was assayed using both phosphatidylcholine and plasmalogenyl-phosphatidylcholine as substrates. Our results show, for the first time, that Plgs are present in chromatin and the plasmalogenyl-phosphatidylcholine stimulates the phosphatidylcholine-dependent phospholipase C activity more than phosphatidylcholine. Finally, in order to verify the possible role of these molecules during cell proliferation and apoptosis, we used liver of rats fed with ciprofibrate which stimulates hepatocytes proliferation during the treatment and, after withdrawal, apoptosis. After 3 days of ciprofibrate treatment, the chromatin plasmalogenyl-phosphatidylcholine increases as well as the phosphatidylcholine-dependent phospholipase C activity. After drug withdrawal, when the hepatocytes undergo to apoptosis, the plasmalogenyl-phosphaticlylcholine content together with phosphatidylcholine-dependent phospholipase C activity decreases. Therefore, it can be concluded that plamalogens are present in the chromatin, and probably may have a function both in regulating phosphatidylcholine dependent phospholipase C and cell cycle. (C) 2004 Wiley-Liss, lnc
Is toll like receptor 4 involved in the mechanism which regulate expression and/or turnover of alpha-synuclein?
No full textToll-like receptors (TLRs) are identified as transmembrane proteins which can recognize a wide array of ligands, either exogenous pathogen-associated molecular patterns (PAMPs) or endogenous stress or damage-associated molecular patterns (DAMPs) and contribute to immune-relate disorders. Cumulative evidences suggest that TLRs not only have been implicated in several non-immune processes, such as neurogenesis and brain development, but can contribute to pathophysiology of several neurodegenerative conditions including alpha synucleinopathies. On the other hand, extracellular α−synuclein (α−SYN) may act as a DAMP and incite an inflammatory process via TLRs that culminate with neuronal death. Among TLRs, TLR4 seems concur, more than others, to neuronal death and inflammatory responses (1). Conversely, in a model of atypical parkinsonism, TLR4 can promote α-SYN clearance and to be associated with a neuroprotective mechanism (2). The current study aims to establish the potential role of TLR4 in acute MPTP mouse model of PD using TLR4-deficient mice (TLR4-/-) and their wild type littermates (WT). We found that MPTP intoxication induced a significant depletion of nigral TH+ neurons as well as a reduction of striatal TH mRNA and protein content in both WT and TLR4-/- mice. The MPTP-treatment also induced a significant decrease of striatal dopamine levels. Interestingly, saline-treated TLR4-/- mice exhibit in striatal and midbrain regions significantly higher mRNA and protein levels of α-SYN in comparison with WT controls. No significant changes in α-SYN occurred following MPTP treatment. Although this acute MPTP model failed to modify the levels of α-SYN, the high amount found in TLR4-/- group at baseline suggests a strong involvement of TLR4 in the mechanisms that regulate the expression and/or turnover of this protein. Further investigation needed to understand of cross-talk between TLR4 and α-SYN and the potential relationship with Parkinson's disease
How microgravity changes galectin-3 in thyroid follicles.
Full text linkAfter long-term exposure to real microgravity thyroid gland in vivo undergoes specific changes, follicles are made up of larger thyrocytes that produce more cAMP and express more thyrotropin-receptor, caveolin-1, and sphingomyelinase and sphingomyelin-synthase; parafollicular spaces lose C cells with consequent reduction of calcitonin production. Here we studied four immunohistochemical tumor markers (HBME-1, MIB-1, CK19, and Galectin-3) in thyroid of mice housed in the Mouse Drawer System and maintained for 90 days in the International Space Station. Results showed that MIB-1 proliferative index and CK19 are negative whereas HBME-1 and Galectin-3 are overexpressed. The positivity of Galectin-3 deserves attention not only for its expression but also and especially for its localization. Our results highlighted that, in microgravity conditions, Galectin-3 leaves thyrocytes and diffuses in colloid. It is possible that the gravity force contributes to the maintenance of the distribution of the molecules in both basal membrane side and apical membrane side and that the microgravity facilitates slippage of Galectin-3 in colloid probably due to membrane remodelling-microgravity induced
In vitro protective effects of Lycium barbarum berries cultivated in Umbria (Italy) on human hepatocellular carcinoma cells
No full textLycium barbarum is a famous plant in the traditional Chinese medicine. The plant is known to have health-promoting bioactive components. The properties of Lycium barbarum berries cultivated in Umbria (Italy) and their effect on human hepatocellular carcinoma cells (HepG2) have been investigated in this work. The obtained results demonstrated that the Lycium barbarum berries from Umbria region display high antioxidant properties evaluated by total phenolic content and ORAC method, on hydrophilic and lipophilic fractions. Moreover, on HepG2 cell line Lycium barbarum berries extract did not change cell viability analyzed by MTT and Trypan blue exclusion assay and did not induce genotoxic effect analyzed by comet assay. Furthermore, it was demonstrated, for the first time, that the berries extract showed a protective effect on DNA damage, expressed as antigenotoxic activity in vitro. Finally, Lycium barbarum berries extract was able to modulate the expression of genes involved in oxidative stress, proliferation, apoptosis, and cancer. In particular, downexpression of genes involved in tumor migration and invasion (CCL5), in increased risk of metastasis and antiapoptotic signal (DUSP1), and in carcinogenesis (GPx-3 and PTGS1), together with overexpression of tumor suppressor gene (MT3), suggested that Umbrian Lycium barbarum berries could play a protective role against hepatocellular carcinoma
Candidate-gene association study on an Italian cohort of patients affected by eating disorders
No full textReinterpretation of mouse thyroid changes under space conditions: the contribution of confinement to damage
No full textDuring space missions, astronauts work in a state of separation from their daily social environment and in physical confinement. It has been shown that confinement influences mood and brain cortical activity, but no data has been obtained with regard to its effect on the thyroid gland, the structure and function of which change during spaceflights. Here, we report the results of a study on the effects of confinement on mouse thyroid, which was implemented with the Mice Drawer System Facility maintained on the ground, a system used for spaceflight experiments. The results show that confinement changes the microscopic structure of the thyroid gland and that it exhibits symptoms similar to those that result from physiological and/or pathological hyperfunction. What is left unchanged, however, is the sphingomyelinase-thyrotropin receptor relationship, which is important for thyrotropin response with a consequential production of hormones that act on the metabolism of almost all tissues and reduces the production of calcitonin, a hormone involved in bone metabolism. During space missions, the overexpression of pleiotrophin, a widespread cytokine up-regulated after tissue injury that acts on bone remodeling, attenuates changes to the thyroid that are spaceflight-dependent; therefore we studied the thyroids of pleiotrophin-transgenic mice in the Mice Drawer System Facility. In confinement, pleiotrophin overexpression does not protect from the loss of calcitonin. The contribution of confinement to thyroid damage during spaceflights is discussed
Structural modifications in Mammalian Thyroids exposed to Hypogravity – Importance for Astronauts.
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