1,721,108 research outputs found
Importanza dell'evoluzione delle sostanze polifenoliche nei vini rossi di qualità durante l'invecchiamento
No full textMorphological evaluation of liposomal iron carriers
No full textIron is one of the most important elements for human, because it plays an essential role in many metabolic processes. However, it is also recognized to be dangerous for its detrimental effect inside human cells, where, in the absence of homeostatic balance, it can induce free radicals formation. Moreover, an excessive accumulation of iron in tissues can produce iron overload, a condition incompatible with life. The use of liposomes as carriers can represent an interesting iron therapy to improve iron bioavailability and reduce its negative effects, in particular during pregnancy. In this study, a morphological analysis has been performed on commercial liposome vesicles at various drying times, both in saline solution and in distilled water. Furthermore, to highlight their possible interaction or internalization in cells, liposomes have been administered to human hemopoietic U937 cells. Ultrastructural analyses confirm that vesicle morphology and size are comparable with classical liposomal structures. Products are stable during specimen preparation and drying. Additionally, they have a good ability to penetrate into cells, interacting with cytoplasmic organelles, without inducing, at least apparently, any ultrastructural damage
Optimal detection of apoptosis by flow cytometry depends on cell morphology.
No full textFlow cytometry has recently become a choice technique for the quantitative
analysis of apoptosis. Monoparametric DNA analysis usually allows identification
of apoptotic cells as a "subdiploid" peak. Progression through apoptosis leads to
chromatin condensation, nuclear fragmentation and eventually to cell disruption.
Thus, a major problem for the flow cytometric analysis of apoptotic populations
is discrimination between debris and apoptotic cells. Here we demonstrate that
the best parameter on which to make such a distinction is the DNA content, no
matter what type of cell is studied. In contrast, discrimination between
apoptotic, non-apoptotic cells, and debris is possible on the basis of scattering
signals only in few selected cases, depending on the morphology of the intact
cells
Supravital exposure to propidium iodide identifies apoptotic cells in the absenceof nucleosomal DNA fragmentation
No full textBy flow cytometry, we have quantitatively evaluated HL-60, MOLT-4, and P815
apoptotic cells induced with camptothecin, staurosporine, and hyperthermia,
respectively. Apoptosis was measured by two different flow cytometry techniques,
using propidium iodide (PI) uptake in permeabilized and nonpermeabilized cells.
Apoptosis also has been analyzed by electron microscopy and DNA cleavage by in
situ nick translation and DNA gel electrophoresis. We demonstrate that supravital
exposure to propidium iodide without prior permeabilization identifies apoptotic
cells, and clearly distinguishes them from necrotic cells in all the cases
examined. This capability is independent of the nucleosomal (180-200 bp)
fragmentation of DNA (which does not take place in MOLT-4 cells), which is the
basis for detection of apoptosis both as a "ladder" by DNA gel electrophoresis
and as a hypodiploid peak by flow cytometry. Therefore, alterations in membrane
permeability, on which PI uptake in living cells is based, allow distinction of
apoptotic cells from necrotic and living cells independently of the heterogeneous
biochemical patterns involved in programmed cell death, which may or may not lead
to DNA oligonucleosomal fragmentation
Holotomographic microscopy: A new approach to detect apoptotic cell features
No full textHolotomographic (HT) microscopy, combines two techniques, holography and tomography, and, in this way, it allows to quantitatively and noninvasively investigate cells and thin tissue slices, by obtaining three-dimensional (3D) images and by monitoring inner morphological changes. HT has indeed two significant advantages: it is label-free and low-energy light passes through the specimen with minimal perturbation. Using quantitative phase imaging with optical diffraction tomography, it can produce 3D images by measuring the refraction index (RI). Therefore, based on RI values, HT can provide structural and chemical cell information, such as dry mass values, morphological changes, or cellular membrane dynamics. In this study, suspended and adherent culture cells have been processed for HT analyses. Some of them have been treated with known apoptotic drugs or pro-oxidant agents and cell response has been investigated both by conventional microscopic approaches and by HT. The ultrastructural and fluorescence images have been compared to those obtained by HT and their congruence has been discussed, with particular attention to apoptotic cell death and on correlated plasma membrane changes. HT appears a valid approach to further characterize well-known apoptotic features such as cell blebbing, chromatin condensation, micronuclei, and apoptotic bodies. Taken together, our data demonstrate that HT appears suitable to highlight suspended or adherent cell behavior under different conditions. In particular, this technique appears an important new tool to distinguish healthy cells from the apoptotic ones, as well as to monitor outer and inner cell changes in a rapid way and with a noninvasive, label-free, approach
MEASUREMENTS, ZYMOGRAPHIC ANALYSIS, AND CHARACTERIZATION OF MATRIX METALLOPROTEINASE-2 AND -9 IN HEALTHY HUMAN UMBILICAL CORD BLOOD
No full textDifferential kinetics of propidium iodide uptake in apoptotic and necrotic thymocytes.
No full textApoptosis and necrosis represent two different mechanisms by which cells die. The
dynamics of cellular lesions in these two processes differ. In particular we
demonstrate that plasma membrane damage, occurring as a primary event during
necrosis represents, on the contrary, a delayed but massive phenomenon during
apoptosis. In consequence there are different kinetics of propidium iodide
incorporation by necrotic and apoptotic thymocytes. This represents the basis for
the flow cytometric identification of different cellular subsets. Analysis of
these subsets after sorting showed that clearly apoptotic cells, which are not
able to exclude propidium iodide for long incubation periods, do not show any
morphologically detectable membrane damage. The kinetics of propidium iodide
incorporation in vivo in isolated rat thymocytes can therefore be used in flow
cytometric analysis. This technique can be used instead of DNA staining of
ethanol-treated cells or nick translation to recognize apoptotic cells, and
distinguish apoptosis from necrosis, without killing the cell
Polyalbumin receptors on hepatitis B virus and on 22 nm hepatitis B surface antigen (HBsAg)2 particles.
No full textReceptors for polymerized human serum albumin ( pHSA ) were studied by solid-phase radioimmunoassay on different hepatitis B surface antigen (HBsAg) particles subpopulations prepared both from hepatitis B e antigen (HBeAg) and from anti-HBe-positive sera. HBsAg particles in HBeAg-positive serum showed higher expression of the receptor compared with HBsAg particles from anti-HBe-positive serum. Analysis of different morphological forms of virus particles was performed after separation by density-gradient ultracentrifugation. Maximum receptor expression was detected in HBV particles containing fractions while the 22-nm HBsAg particles had significantly lower receptor activity. These observations support the hypothesis of a pathogenetic role of the pHSA receptor in mediating virus access to hepatocytes. Indeed, the higher pHSA binding activity on HBV particles could allow selective attachment of the infectious virion to liver cells that bear similar albumin receptors on their surface
Inositol lipid phosphorylation and breakdown in rat liver nuclei is affected by hydrocortisone blood levels
No full textThe possibility that inositol lipid metabolism is related to nuclear events accompanying steroid hormone action has been investigated by comparing lipid phosphorylation and breakdown in normal rat liver nuclei and in hypo‐ and hypercortisolemic conditions. Lipid phosphorylation in vitro showed the presence of diacylglycerol (DAG)‐, phosphatidylinositol (PI)‐ and phosphatidylinositol‐4‐phosphate (PIP)‐kinase activity, with differences between total tissue homogenates and isolated nuclei, relevant to the treatment in vivo. Administration of hydrocortisone (HC) produced a marked decrease in the phosphorylated nuclear products without influencing the homogenate kinase activity. Under conditions which were optimal for the kinase activities, nuclear PIP‐kinase was strongly increased in presence of a high blood level of HC whereas PI‐kinase activity was reduced. From these observations it appears that the observed differences were due to specific modulation of kinase activities rather than to changes in the availability of substrates. The phosphoinositide‐specific phospholipase C (PLC) activity was also investigated. In the presence of a high HC blood level, the phosphodiesteratic cleavage of PIP strongly increased, while that of phosphatidylinositol bisphosphate (PIP2) was similar in normal and hypercortisolemic conditions. Nuclear phosphoinositide hydrolysis was affected by PLC, β and γ isoforms, which were equally represented in all the conditions investigated, indicating that the observed changes of activity were due to a modulation rather than to a change in the amount of enzyme. These results suggest that inositol lipid metabolism plays a role in the nuclear modifications accompanying steroid hormone induction of transcriptional activity. Copyright © 1994 John Wiley & Sons Ltd
Ultrastructural features of apoptosis
No full textApoptosis is a gene-directed physiological and programmed process of cell
deletion aimed at the regulation of tissue and organ development. It affects
different cell types and is triggered by a variety of stimuli all inducing
closely comparable structural changes. Despite the deeply different morphology
and metabolism of the cell models and the various inducers and their initial
effects., a convergence seems to take place in a common metabolic pathway that., in
most cases., involves the activation of a Ca2+ dependent endonuclease. A growing
body of data is now available on the molecular events that lead to DNA damage.
DNA cleavage in nucleosomic or oligonucleosomic fragments is related to the
appearance of unusual and very characteristic ultrastructural changes. The
nucleus is especially affected., and shows chromatin rearrangements consisting of
cup-shaped marginations., sharply separated from diffuse chromatin areas. Nuclear
fragmentation subsequently appears., finally followed by the formation of numerous
micronuclei. Cytoplasmic damage appears at a very late stage and the process
takes place despite good preservation of plasma membrane and cytoplasm
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