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PubMed1984

[Structure and cellular composition of cubital lymph nodes in the adult human].

The cubital lymph nodes obtained from 32 corpses of mature persons (16-75 years of age) have been studied. Sections 5-7 mcm thick made at the level of the hilus are stained with hematoxylin--eosin, azur II--eosin, after van Gieson and Mallory. When the comparative contents of the connective tissue, cortical and medullary substance are determined, the whole area of the node in the section is taken as 100%. With age, the connective tissue composition (capsules and trabecules) and fat tissue grow in size. During all the age periods the medullary substance predominates over the cortical substance. The amount of the lymph nodules essentially decreases with age. For each age period there is its own specific cytological profile. However, during all the age periods the amount of the small lymphocytes predominates over the contents of the large and middle lymphocytes.

Adolescent↗
PubMed1982

Toxicity of mitomycin C and anti-intoxication by fumaric acid in liver and kidney cellular fine structure.

The previous study indicated that the toxic symptoms in ICR mice given two ip injections of 4 mg/kg of mitomycin C at an interval of 48 hr were reduced by the concurrent administration of 40 mg/kg of fumaric acid. In the present study, are described the changes of subcellular components and organella in the liver and kidney at 4 days after the 2nd injection. The liver treated with mitomycin C showed perinuclear irregularity, aggregation of chromatins, and abnormal cytoplasmic organella (e.g., swelling of mitochondria and dilatation of rough endoplasmic reticulum). Focal localization of rough endoplasmic reticulum was noted. The concurrent administration of fumaric acid reduced the incidence of such deleterious changes. Increases in the number of nucleoli and normal cytoplasmic organella were evident. The kidney treated with mitomycin C showed decrease of chromatins and edematous nuclear matrix. The cytoplasmic organella were swollen. The action of fumaric acid against mitomycin C intoxication was more apparent in the kidney. Chromatins and nucleoli developed well and other subcellular organella appeared completely normal.

Animals↗
PubMed1996

[Biological role of cellular metabolites--structural analogs of platelet activating factor].

The review is concerned with cell metabolites - the platelet activating factor (PAF) and its choline-containing structural analogs. The biological activity of PAF and its analogs are considered. The influence of PAF and its analogs of membrane properties, cell receptors, transmembrane signalling (protein kinase C activation, Ca2+ release) as well as its participation in cell phospholipases A2, C and D activation are considered. The intracellular function of PAF and its analogs is discussed in terms of their influence on prostaglandin and leukotriene biosynthesis as well as with reference to the biological activity of 1-acyl-2-acetyl-sn-glycerols and lysophosphatidylcholine. The function of cell-released PAF and its analogs is considered in connection with their influence on plasma lipoproteins, inter-cell PAF synthesis and different mechanisms of PAF and PAF analog-induced cell activation including cell priming, cell desensitization and receptor-dependent effects. It is concluded that PAF is an intracellular and intercellular mediator, whereas 1-acyl-PAF is an intracellular lipid bioregulator.

Animals↗
PubMed2005

Biomechanics of cellular solids.

Materials with a cellular structure are widespread in nature and include wood, cork, plant parenchyma and trabecular bone. Natural cellular materials are often mechanically efficient: the honeycomb-like microstructure of wood, for instance, gives it an exceptionally high performance index for resisting bending and buckling. Here we review the mechanics of a wide range of natural cellular materials and examine their role in lightweight natural sandwich structures (e.g. iris leaves) and natural tubular structures (e.g. plant stems or animal quills). We also describe two examples of engineered biomaterials with a cellular structure, designed to replace or regenerate tissue in the body.

Animals↗
PubMed2005

Fluorescence microscopy with super-resolved optical sections.

The fluorescence microscope, especially its confocal variant, has become a standard tool in cell biology research for delivering 3D-images of intact cells. However, the resolution of any standard optical microscope is at least 3 times poorer along the axis of the lens that in its focal plane. Here, we review principles and applications of an emerging family of fluorescence microscopes, such as 4Pi microscopes, which improve axial resolution by a factor of seven by employing two opposing lenses. Noninvasive axial sections of 80-160 nm thickness deliver more faithful 3D-images of subcellular features, providing a new opportunity to significantly enhance our understanding of cellular structure and function.

Cellular Structures↗
PubMed1985

Ultrastructural changes in V79 hamster lung fibroblasts during hypoxic exposure.

Cells in tumors that are deprived of their blood supply become hypoxic. These stressed cells adapt to their new environments by altering their metabolic regimen which in time induces cellular structure changes. The morphologic make-up of these O2-deprived cells is the focal point of this electron microscopy study. V-79 hamster lung fibroblast cells grown as monolayer cultures were examined under controlled culture density and oxygen tensions - normal aerobia (2.1 X 10(5) ppm O2), and extreme hypoxia (less than 10 ppm O2). Electron micrographs of these cells demonstrated a loss of structural mitochondrial integrity accompanied with large increases in both mitochondrial and lipid vacuole size following exposure to extreme hypoxia. When these cells were reoxygenated, those mitochondria which had not become degenerate returned to their normal state however, lipids still continued to accumulate in vacuoles for a further 6 h. Addition of 1 mM palmitic acid to aerobic cultures evoked similar lipid and mitochondrial irregularities as were observed in hypoxic cells although, the latter were not as marked. When this saturated fatty acid was added to hypoxic cells no further structural alterations were seen. The cellular changes manifested during this study were subjected to quantitative measurements and these results have given an insight into the scope and variety of ultrastructural changes which have resulted from exposure of cultured cells to hypoxic conditions.

Animals↗
PubMed2004

Recent advances of nanodosimetry.

The early damage to genes and cells due to ionizing radiation is initiated by the overlay of the track structure of charged particles and of the structure of radiosensitive sub-cellular volumes. As a result of this overlay, a specified number of ionizations (the ionization cluster size) is formed per primary particle. Therefore, one of the aims of nanodosimetry is to determine ionization cluster-size distributions in nanometric volumes of liquid water, as a substitute to sub-cellular structures. After a short description of the main aspects of cluster-size formation by charged particles, an overview of the advanced measuring techniques that use millimetric target volumes filled with a low-pressure gas to simulate nanometric target volumes at unit density is given. Afterwards, physical principles are discussed which are applicable to convert ionization cluster-size distributions measured in gases into those for liquid water. Finally, a tentative possibility is proposed of how to relate parameters derived from cluster-size distributions in liquid water to parameters derived from radiation-induced radiobiological experiments.

Body Burden↗
PubMed1991

Erythrocyte defense against hydrogen peroxide: preeminent importance of catalase.

To investigate the relative importance of catalase and glutathione in erythrocyte oxidant defense, human and mouse (normal and acatalasemic) erythrocytes were reversibly lysed and resealed in the presence of exogenous catalase or glutathione. This resulted in an increase in intracellular catalase activity or glutathione concentration in the resealed erythrocytes while normal cellular structure, hemoglobin concentration, cell volume, cellular deformability, and adenosine triphosphate concentration were maintained. Resealing alone had no effect on oxidant sensitivity. In human cells, a threefold increase in catalase activity resulted in the maintenance of glutathione levels in response to hydrogen peroxide (H2O2) challenge. Reconstitution of congenitally acatalasemic mouse erythrocytes, which were extremely sensitive to even micromolar concentrations of H2O2 with purified catalase resulted in complete protection against H2O2. Indeed, the catalase-reconstituted acatalasemic cells were less sensitive to H2O2-mediated damage than were normal, catalase-replete mouse cells. In contrast, alteration of the glutathione status of human and mouse (normal and acatalasemic) cells had no significant effect on oxidant sensitivity. Even a five-fold increase in intracellular glutathione concentration (greater than 30 micromoles glutathione per gram of hemoglobin) in normal or catalase-deficient (azide-treated or acatalasemic) red blood cells had no protective effect against H2O2-mediated lipid peroxidation or methemoglobin generation. Similarly, depletion of glutathione by 1-chloro-2,4-dinitrobenzene also had no effect on erythrocyte H2O2 sensitivity. These results suggest an important role for catalase in protection against H2O2-mediated damage at physiologic levels and that catalase is as at least as important as glutathione in cellular defense against H2O2.

Animals↗
PubMed2006

Self-organization of microtubule bundles in anucleate fission yeast cells.

Self-organization of cellular structures is an emerging principle underlying cellular architecture. Properties of dynamic microtubules and microtubule-binding proteins contribute to the self-assembly of structures such as microtubule asters. In the fission yeast Schizosaccharomyces pombe, longitudinal arrays of cytoplasmic microtubule bundles regulate cell polarity and nuclear positioning. These bundles are thought to be organized from the nucleus at multiple interphase microtubule organizing centres (iMTOCs). Here, we find that microtubule bundles assemble even in cells that lack a nucleus. These bundles have normal organization, dynamics and orientation, and exhibit anti-parallel overlaps in the middle of the cell. The mechanisms that are responsible for formation of these microtubule bundles include cytoplasmic microtubule nucleation, microtubule release from the equatorial MTOC (eMTOC), and the dynamic fusion and splitting of microtubule bundles. Bundle formation and organization are dependent on mto1p (gamma-TUC associated protein), ase1p (PRC1), klp2p (kinesin-14) and tip1p (CLIP-170). Positioning of nuclear fragments and polarity factors by these microtubules illustrates how self-organization of these bundles contributes to establishing global spatial order.

Cell Nucleus↗
PubMed1999

Structural and functional heterogeneity of nuclear bodies.

The nuclear body is a cellular structure that appears to be involved in the pathogenesis of acute promyelocytic leukemia and viral infection. In addition, the nuclear body is a target of autoantibodies in patients with the autoimmune disease primary biliary cirrhosis. Although the precise function of the nuclear body in normal cellular biology is unknown, this structure may have a role in the regulation of gene transcription. In a previous investigation, we identified a leukocyte-specific, gamma interferon (IFN-gamma)-inducible autoantigen designated Sp140. The objectives of the present study were to investigate the cellular location of Sp140 with respect to the nuclear-body components PML and Sp100 and to examine the potential role of Sp140 in the regulation of gene transcription. We used adenovirus-mediated gene transfer to express Sp140 in human cells and observed that the protein colocalized with PML and Sp100 in resting cells and associated with structures containing PML during mitosis. In cells infected with the adenovirus expressing Sp140 and incubated with IFN-gamma, the number of PML-Sp100 nuclear bodies per cell increased but immunoreactive Sp140 was not evenly distributed among the nuclear bodies. Sp140 associated with a subset of IFN-gamma-induced PML-Sp100 nuclear bodies. To examine the potential effect of Sp140 on gene transcription, a plasmid encoding Sp140 fused to the DNA-binding domain of GAL4 was cotransfected into COS cells with a chloramphenicol acetyltransferase (CAT) reporter gene containing five GAL4-binding sites and a simian virus 40 enhancer region. The GAL4-Sp140 fusion protein increased the expression of the reporter gene. In contrast, Sp100 fused to the GAL4 DNA-binding domain inhibited CAT activity in transfected mammalian cells. The results of this study demonstrate that Sp140 associates with a subset of PML-Sp100 nuclear bodies in IFN-gamma-treated cells and that Sp140 may activate gene transcription. Taken together, these observations suggest that the nuclear bodies within a cell may be heterogeneous with respect to both composition and function.

Adenoviridae↗
PubMed2003

Nonspecific depolarization of the plasma membrane potential induces cytoskeletal modifications of bovine corneal endothelial cells in culture.

Modifications in the cell membrane potential have been suggested to affect signaling mechanisms participating in diverse cellular processes, many of which involve structural cellular alterations. In order to contribute some evidence in this respect, we explored the effects of several depolarizing procedures on the structure and monolayer organization of bovine corneal endothelial cells in culture. Visually confluent cell monolayers were incubated with or without the depolarizing agent, either in a saline solution or in culture medium for up to 30 min. Membrane potential was monitored by fluorescence microscopy using oxonol V. Fluorescent probes were employed for F-actin, microtubules, and vinculin. Depolarization of the plasma membrane, achieved via the incorporation of gramicidin D into confluent endothelial cells or by modifications of the extracellular saline composition, provoked an increment of oxonol fluorescence and changes in cell morphology, consisting mainly of modifications in the cytoskeletal organization. In some areas, noticeable intercellular spaces appear. The cytoskeleton modifications mainly consist of a marked redistribution of F-actin and microtubules, with accompanying changes in vinculin localization. The results suggest that the depolarization of the plasma membrane potential may participate in mechanisms involved in cytoskeleton organization and monolayer continuity in corneal endothelial cells in culture.

Actin Cytoskeleton↗
PubMed1975

A comparative study in the transmission electron microscope and scanning electron microscope of intracellular structures in sheep heart muscle cells.

The internal cellular structures of the sheep ventricular myocardium have been comparatively studied in the transmission electron microscope (TEM) and in the scanning electron microscope (SEM). For TEM studies the tissue was prepared according to standard methods. Thick sections (10 mum) of paraffin embedded material were, after they had been deparaffinized in toluene, critical point dried, coated with gold and examined in the SEM. The comparative TEM and SEM investigations revealed very good correspondence, and it is evident that the described preparation procedure for SEM has preserved the fine structures of myofibrils, mitochondria, T-Tubules and sarcoplasmic reticulum in an excellent life-like pattern. Of special interest was the three-dimensional demonstration of triads and circumferentially arranged T-tubules.

Animals↗