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101.
Karl E. Andersson George S. Drummond Umberto Freddara Mohinder K. Sardana Shigeru Sassa 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,676(3):289-299
The effects of single large doses of the porphyrin-heme precursor ?d-aminolevulinic acid on tissue porphyrins and on δ-aminolevulinate synthase and heme oxygenase, the rate-living enzymes of liver heme synthesis and degradation respectively, were studied in the chick embryo in ovo, in the mouse and in the rat. δ-Aminolevulinic acid treatment produced a distinctive pattern characterized by extensive tissue porphyrin accumulation and alterations in these rate-limiting enzymes in the liver. Repression of basal or allylisopropylacetamide-induced liver δ-aminolevulinate synthase was observed and, in the mouse and the rat, induction of liver heme oxygenase after δ-aminolevulinic acid treatment, in a manner similar to the known effects of hemin on these enzymes. In the chick embryo liver in ovo heme oxygenase was substantially higher than in rat and mouse liver, and was not significantly induced by δ-aminolevulinic acid or other compounds, including hemin, CS2 and CoCl2. Levulinic acid, an analogue of δ-aminolevulinic acid, did not induce heme oxygenase in mouse liver. δ-Aminolevunilic acid treatment did not impair ferrochelatase activity but was associated with slight and variable decreases in liver cytochrome P-450. Treatment of chick embryos with a small ‘priming’ dose of 1,4-dihydro-3,5-dicarbethoxycollidine, which impairs liver ferrochelatase activity, accentuated porphyrin accumulation after δ-aminolevulinic acid in the liver. These observations indicate that exogenous δ-aminolevulinic acid is metabolized to porphyrins in a number of tissues and, at least in the liver, to a physiologically significant amount of heme, thereby producing an increase in the size of one or more of the heme pools that regulate both heme systhesis and degradation. It is also possible than when δ-aminolevulinic acid is markedly overproduced in vivo it may be transported to many tissues and re-enter the heme pathway and alter porphyrin-heme metabolism in cells and tissues other than those in which its overproduction primarily occurs. 相似文献
102.
Cognitive functions are stored in the connectome, the wiring diagram of the brain, which exhibits non-random features, so-called motifs. In this work, we focus on bidirectional, symmetric motifs, i.e. two neurons that project to each other via connections of equal strength, and unidirectional, non-symmetric motifs, i.e. within a pair of neurons only one neuron projects to the other. We hypothesise that such motifs have been shaped via activity dependent synaptic plasticity processes. As a consequence, learning moves the distribution of the synaptic connections away from randomness. Our aim is to provide a global, macroscopic, single parameter characterisation of the statistical occurrence of bidirectional and unidirectional motifs. To this end we define a symmetry measure that does not require any a priori thresholding of the weights or knowledge of their maximal value. We calculate its mean and variance for random uniform or Gaussian distributions, which allows us to introduce a confidence measure of how significantly symmetric or asymmetric a specific configuration is, i.e. how likely it is that the configuration is the result of chance. We demonstrate the discriminatory power of our symmetry measure by inspecting the eigenvalues of different types of connectivity matrices. We show that a Gaussian weight distribution biases the connectivity motifs to more symmetric configurations than a uniform distribution and that introducing a random synaptic pruning, mimicking developmental regulation in synaptogenesis, biases the connectivity motifs to more asymmetric configurations, regardless of the distribution. We expect that our work will benefit the computational modelling community, by providing a systematic way to characterise symmetry and asymmetry in network structures. Further, our symmetry measure will be of use to electrophysiologists that investigate symmetry of network connectivity. 相似文献
103.
A. M. Berghella Patrizia Pellegrini Tiziana Del Beato Matteo Marini Ennio Tomei Domenico Adorno Carlo Umberto Casciani 《Cancer immunology, immunotherapy : CII》1997,45(5):241-249
Current research has still not clarified the biological role of soluble interleukin(IL)-2 receptor (sIL-2R) and the significance
of its increase in the serum of colon cancer patients compared to healthy subjects. To address these questions at the immunological
level in a group of patients and healthy subjects, we determined the sIL-2R level in the serum and its release from peripheral
blood mononuclear cells (PBMC) as a function of tumour necrosis factor (TNF) α, IL-1α, IL-1β, IL-2, interferon (IFN) γ, IL-4,
IL-6 and IL-10 levels in the serum and PBMC production; and PBMC proliferative responses to IL-2, IL-4 and anti-CD3 monoclonal
antibody (CD3), variously combined. The level of sIL-2R in patients’ serum was higher than in healthy subjects and correlated
with the stage of advancement. Moreover, while in healthy subjects the serum level of sIL-2R was not significantly correlated
with other parameters, in patients it was positively related to IL-4, IL-6 and IL-10 serum levels, PBMC IL-4 production and
to the PBMC proliferative response to CD3 and CD3+IL-2; it was negatively correlated to IL-2 serum level and IL-1β PBMC release.
A negative connection between IFNγ serum level and the PBMC production of sIL-2R was also found. This suggests that the increase
of sIL-2R in the serum of patients, compared to healthy subjects, is involved in the inappropriate expansion of the T helper
(TH2) suppressive immune response, which we previously reported. The multivariate statistical method supported the above suggestions
and we also found that, in healthy subjects, the up- and down-regulation of sIL-2R in the serum within the physiological ranges
seems to have a regulating role in the relationships between TNFα, IFNγ and IL-4, IL-6, contributing to the operation of the
cytokine network between TH1 and TH2 cells. However, in patients compared to healthy subjects the increased sIL-2R serum level
seems to direct the immune response towards a suppressive type, which may be due to an alteration in the above-mentioned physiological
regulating role.
Received: 12 April 1997 / Accepted: 4 September 1997 相似文献
104.
Gregorio Santori Cinzia Domenicotti Antonella Bellocchio Maria A Pronzato Umberto M Marinari Damiano Cottalasso 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1997,695(2):1290
The widely used high-performance liquid chromatography (HPLC) procedure to determine glutathione in biological samples utilizing iodoacetic acid as thiol quenching agent and 1-fluoro-2,4-dinitrobenzene for derivatization has been modified regarding tissue sample processing and storage of the working solutions. The modified procedure compared with the original method reduces artifactual oxidation in rat liver glutathione measurement (1.47±0.8% vs. 2.84±0.69%, respectively). In both HPLC procedures, an increase in artifactual oxidation was found in both standard glutathione solutions and hepatic samples when N-ethylmaleimide instead of iodoacetic acid was used for thiol trapping. 相似文献
105.
The polymeric structure of the complex, [SnCl4(H2O)2]18-crown-6·2H2O, prepared by the addition of a solution of SnCl4 to 18-crown-6, has been determined by X-ray analysis. The structure has been solved by three-dimensional Patterson-Fourier synthesis to a conventional R-factor of 0.13, by using 1394 reflections with I>3σ(I). The crystals are monoclinic, with a = 15.753(3), b = 15.072(3), c = 12.209(4), β = 97.77°(1.0), z = 4, and space group P21/a. The tin atom is octahedrally coordinated to four chlorine atoms and two water molecules in cis positions. A very complex network of hydrogen bonding links together the tin coordination octahedron, the two water hydration molecules, and the two crystallographically-different half crown-ethers. 相似文献
106.
107.
Mesenchymal stromal cells from amniotic fluid are less prone to senescence compared to those obtained from bone marrow: An in vitro study 下载免费PDF全文
Nicola Alessio Caterina Pipino Domitilla Mandatori Pamela Di Tomo Angela Ferone Marco Marchiso Mariarosa A.B. Melone Gianfranco Peluso Assunta Pandolfi Umberto Galderisi 《Journal of cellular physiology》2018,233(11):8996-9006
Mesenchymal stromal cells (MSCs) are considered to be an excellent source in regenerative medicine. They contain several cell subtypes, including multipotent stem cells. MSCs are of particular interest as they are currently being tested using cell and gene therapies for a number of human diseases. They represent a rare population in tissues; for this reason, they require, before being transplanted, an in vitro amplification. This process may induce replicative senescence, thus affecting differentiation and proliferative capacities. Increasing evidence suggests that MSCs from fetal tissues are significantly more plastic and grow faster than MSCs from bone marrow. Here, we compare amniotic fluid mesenchymal stromal cells (AF‐MSCs) and bone marrow mesenchymal stromal cells (BM‐MSCs) in terms of cell proliferation, surface markers, multidifferentiation potential, senescence, and DNA repair capacity. Our study shows that AF‐MSCs are less prone to senescence with respect to BM‐MSCs. Moreover, both cell models activate the same repair system after DNA damage, but AF‐MSCs are able to return to the basal condition more efficiently with respect to BM‐MSCs. Indeed, AF‐MSCs are better able to cope with genotoxic stress that may occur either during in vitro cultivation or following transplantation in patients. Our findings suggest that AF‐MSCs may represent a valid alternative to BM‐MSCs in regenerative medicine, and, of great relevance, the investigation of the mechanisms involved in DNA repair capacity of both AF‐MSCs and BM‐MSCs may pave the way to their rational use in the medical field. 相似文献
108.
Serotonin 5‐HT7 receptor increases the density of dendritic spines and facilitates synaptogenesis in forebrain neurons 下载免费PDF全文
109.
Damiano G. Mita Nadia Diano Valentina Grano Marianna Portaccio Sergio Rossi Umberto Bencivenga Immacolata Manco Carla Nicolucci Mariangela Bianco Tiziana Grimaldi Luigi Mita Svetla Georgieva Tzonka Godjevargova 《Journal of Molecular Catalysis .B, Enzymatic》2009,58(1-4):199-207
Endocrine disruptors are chemicals able to induce adverse effects into wildlife and humans owing to their ability of interfering with the endocrine system. Bisphenol A (BPA) has been chosen as model of endocrine disruptors. To reduce the BPA pollution in waters we proposed the employment of the process of thermodialysis. Two different catalytic membranes have been prepared by covalently immobilizing laccase (from Trametes versicolor) by means of a diazotation process or tyrosinase (from mushroom) by condensation. The support was a nylon membrane. The bioremediation power of both catalytic membranes has been analysed under isothermal and non-isothermal conditions.The advantages in using non-isothermal bioreactors were discussed in terms of reduction of the bioremediation times. 相似文献
110.
Francesco Oliva Loredana Zocchi Eleonora Candi Gerry Melino Umberto Tarantino 《Biochemical and biophysical research communications》2009,379(4):887-891
The ethiopathogenesis of rotator cuff disease remains poorly understood. Many studies advocate the importance of extra cellular matrix for the homeostasis of connective tissue. Transglutaminase enzymes family has been studied in the context of connective tissue formation and stabilisation. Here, we investigated transglutaminases expression pattern in biopsies of normal and injured supraspinatus tendons of human shoulders and in the Achilles tendons of transglutaminase 2 knock-out and wild-type mice. Our results show that different transglutaminase family members are differentially expressed in human and mouse tendons, and that transglutaminase 2 is down-regulated at mRNA and protein levels upon human supraspinatus tendon ruptures. 相似文献