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PubMedDate not supplied

[Structure containing cellular mRNA in picornavirus infections].

The fate of cellular mRNA upon infection of Krebs-2 ascites carcinoma cells with encephalomyocarditis (EMC) virus was investigated. The cell mRNA was discovered in a structure with a sedimentation coefficient of about 100S and a buoyant density of 1.50--1.519 g/cm3 during active virus-specific synthesis (3.0--4.0 hr post infection). The template activity of the 100S structure in a cell-free protein-synthesizing system and of mRNA isolated from it was studied and the nature of synthesized products was analyzed. It was shown that the 100S structure seems to be translationally inactive. On the contrary, the RNA isolated from its is functionally active.

Animals↗
PubMed1991

Primary structure and cellular distribution of two fatty acid-binding proteins in adult rat kidneys.

Fatty acid-binding proteins (FABPs) were purified from the kidneys of female and male rats and characterized by primary structure and histological distribution in the kidney. Two FABPs (14 and 15.5 kDa) were found in male rat kidney cytosol whereas only 14-kDa FABP could be recognized in female rat kidneys throughout the purification steps. The amino acid sequence of the 14-kDa FABP was identical to that of rat heart FABP deduced from the cDNA sequence (Heuckeroth, R. O., Birkenmeier, E. H., Levin, M. S., and Gordon, J. I. (1987) J. Biol. Chem. 262, 9709-9717). Structural analysis of the male-specific 15.5-kDa FABP identified this second FABP as a proteolytically modified form of alpha 2u-globulin, an 18.7-kDa major urinary protein of adult male rats (Unterman, R. D., Lynch, K. R., Nakhasi, H. L., dolan, K. P., Hamilton, J. W., Cohn, D. V., and Feigelson, P. (1981) Proc. Natl. Acad. Sci. U.S.A. 78, 3478-3482) which shares a common ancestry with a number of hydrophobic ligand-binding proteins such as serum retinol-binding proteins. Immunohistochemical investigation disclosed that heart-type FABP (14-kDa FABP) is localized in the cytoplasm of the epithelia of the distal tubules in both male and female rat kidneys whereas 15.5-kDa FABP immunostaining was observed predominantly in the endosomes or lysosomes of proximal tubules in male rat kidneys. These results suggest strongly the functional divergence of two FABPs in the rat kidney.

Amino Acid Sequence↗
PubMed1989

Polyurethane support films: structure and cellular adhesion.

It is desirable to examine the cytobiology of cell adhesion to the same materials which are contemplated for use in biomedical and biotechnological devices. It is also of fundamental interest to examine adhesion to substrates with properties which are likely to influence adhesion in controlled ways. In many of these applications the materials of choice are polyurethane elastomers due to their physical properties and resistance to biodegradation. Polyurethanes have a two phase microstructure consisting of hydrophilic hard segments and hydrophobic soft segment domains. Variations of both the chemistry and the morphology of these microdomains may be produced. It is well understood that the hydrophilic/hydrophobic nature of surfaces affects cellular adhesion and the adsorption of extracellular proteins. Since polyurethane microdomains have dimensions in the range of 10-100 nm, hence the size of proteins and cell-surface receptors, polyurethane microdomain structure could influence order at the cell-material interface. Polyurethanes may be prepared as thin films with excellent properties for use as specimen supports in High Voltage transmission Electron Microscopy (HVEM) at 1 MeV. This permits the imaging of the cytoskeleton and other internal features of whole mounts of adherent cells, rather than tedious thin sectioning required for conventional TEM. Subsequently the surface morphology of these preparations may be imaged with high resolution SEM. Finally, the polyurethane itself may be stained and imaged by either HVEM or high resolution SEM in order to relate polyurethane micro-morphology to cellular features.

Biocompatible Materials↗
PubMed1986

On the ontogeny and interactions of glyceraldehyde-3-phosphate dehydrogenase.

The interaction of GAPDH with cellular structure has been studied in the major tissues of the mouse during development. Overall the data provides a clear indication that interactions between GAPDH and cellular structure are appreciable in all major tissues, at least during early stages of development, and an analysis of the isozyme status of the enzyme in both soluble and bound compartments for all tissues at all developmental stages indicates the presence of only a single GAPDH isozyme in the mouse. Possible reasons for the lack of an extensive multiplicity of this enzyme in mammalian tissues (the only tetrameric glycolytic enzyme to display this restriction) and for the large amounts of GAPDH in many cell types are discussed in relation to the large number of proteins that GAPDH interacts with in the cell.

Animals↗
PubMedDate not supplied

On the developmental properties and tissue interactions of hexokinase.

The interactions of the isozymes of hexokinase with cellular structure have been studied in the major tissues of the mouse during development. Overall, these data provide a clear indication that interactions between hexokinase and cellular structure are appreciable in all major tissues and at all stages of development, and an analysis of the isozyme status of the enzyme in both soluble and bound compartments has been effected. Further evidence in support of the already well documented interaction of hexokinase I to subcellular material in adult brain and kidney tissues is provided and extended to show that such interactions are extensive in both these tissues throughout development. In addition, evidence is provided that considerable hexokinase II activity is present in mouse foetal tissues in both the soluble and bound fractions and this isozyme is also shown to be the predominant "bound" form of the enzyme in adult skeletal muscle. By contrast, hexokinase III and IV are shown to be largely located in the cytosolic fraction of liver. The metabolic implications of these enzyme-structural interactions during development are discussed, as is the possibility of a functional linkage between hexokinase, which is bound to the mitochondria, and other enzymic components of the glycolytic sequence.

Animals↗
PubMed1986

On the developmental multiplicity and subcellular interactions of pyruvate kinase.

The interactions of the isozymes of pyruvate kinase with cellular structure have been studied in the major tissues of the mouse during development. Overall, these data provide a firm indication that the interactions between this enzyme and cellular structure are appreciable in most tissues during all stages of development, and an analysis of the isozyme status of the enzyme in both soluble and bound compartments has been effected. Evidence has been provided that the A4 form of pyruvate kinase interacts to a greater extent with subcellular structure than does the C4 form, and the C4 form in turn interacts to a greater extent to subcellular structure than does the B4 form.

Actins↗
PubMed1993

Imaging F-actin in fixed glial cells with a combined optical fluorescence/atomic force microscope.

A prototype combined optical fluorescence/atomic force microscope (OFAFM) designed for use in neurobiology and related disciplines has been constructed and used to study filamentous actin (F-actin) and other cellular structures in fixed Xenopus retinal glial cells (XR1 glial cell line). F-actin was readily observed by both fluorescence and AFM. AFM images of nuclei and other cellular structures were also obtained. The OFAFM consists of an AFM with an interferometer detection mechanism mounted on an inverted optical microscope. Integration of optical and scanned probe imaging methods provides a unique and useful approach to studying glial (and other) cell structure and function.

Actins↗
PubMed2006

Membrane interactions of cell-penetrating peptides probed by tryptophan fluorescence and dichroism techniques: correlations of structure to cellular uptake.

This work reports on the binding and conformation of a series of CPPs in the bilayer membranes of large unilamellar vesicles and the effect of the presence of cholesterol. We show a negative correlation between alpha-helical structure and uptake efficiency for penetratin peptides where the two central arginine residues of penetratin are thought to be important for breaking the secondary structure. Penetratin alpha-helicity is also reduced upon incorporation of cholesterol into the membrane. Flow linear dichroism in the far-UV region shows that the penetratin peptides adopt a preferential orientation of the alpha-helix parallel to the bilayer, and the linear dichroism (LD) spectrum in the aromatic region indicates that the tryptophan residues are preferentially oriented parallel to the membrane. The Tat analogue TatP59W and the oligoarginine R7W, which are more efficient CPPs than penetratin, bind to membranes as random coils and do not show any orientation in LD, again indicating that alpha-helicity reduces uptake efficiency. Further, we observe large variations in tryptophan quantum yields for the five CPPs in this study and discuss this in terms of the ability to cause lipid rearrangement. Binding isotherms show that cholesterol increases the affinity of the peptide for the membrane, but tryptophan fluorescence lifetimes are essentially unaltered by incorporation of as much as 40 mol % cholesterol into the membrane, suggesting the absence of specific peptide-cholesterol interactions. Fluorescence emission maxima are insensitive to cholesterol and indicate that the peptide is positioned in the headgroup region. The results on peptide-membrane interactions are discussed in terms of possible uptake mechanisms.

Animals↗
PubMedDate not supplied

[Characteristics of Debye potentials in cell structures].

The activity of the cellular system is accompanied by the changes of substrate concentrations and excreted substances in the medium. This event brings about essential changes of the medium electrical properties. For the accomplishment of stationary metabolism the following condition should be fulfilled B=--2nsquare rootA, where n=1,2...., A and B are some functions depending on the diffusion coefficient of the substrate and excrement, their molecular weights, dissociation coefficients, membrane permeabilities and other parameters of the cellular structure.

Cell Physiological Phenomena↗
PubMed1979

Experimental investigations on hypokinesis of skeletal muscles with different functions VII. Ultrastructural observations.

Ultrastructural investigations were carried out parallel with biochemical measurements on the limb muscles of rabbits immobilized by putting in plaster. The cellular structure of normal and immobilized (1--6 weeks) m. soleus and m. gastrocnemius (red tonic and white tetanic, respectively) were compared. During immobilization significant changes occurred in the cellular structure of m. soleus, while little change was observed in the white fibres of m. gastrocnemius. The fibres of m. soleus decreased in diameter and fatty infiltration set in. The myofibrils decreased in amount and their structure was damaged and disorganized but did not disappear completely. Mitochondria showed little damage, like membraneous structures in general, in number. Loss of material seems to be by way of vesicles formed by the heavily invaginated plasma membrane and by the deflation of the numerous vesicles observed. The red fibres of m. gastrocnemius behaved like the fibres of m. soleus; in the white fibres some focal disorganization was observed near the Z line. The cystae of mitochondria and the SR appear to be dilated.

Animals↗
PubMed2005

Cationic lipid-DNA complexes for non-viral gene therapy: relating supramolecular structures to cellular pathways.

Cationic liposomes (CLs) are used as nonviral vectors in worldwide human clinical trials of gene therapy. Among other advantages, lipid-DNA complexes have the ability to transfer very large genes into cells, but their efficiency is much lower than that of viruses. Recent studies combining structural and biological techniques are beginning to unravel the relationship between the distinctly structured CL-DNA complexes and their transfection efficiency. Most CL-DNA complexes form a multilayered structure with DNA sandwiched between the cationic lipids (lamellar complexes, LalphaC). On rare occasions, an inverted hexagonal structure (HIIC) is observed. An important recent insight is that the membrane charge density (sigmaM) of the CL-vector is a universal parameter governing the transfection efficiency of LalphaC (but not HIIC) complexes. This has led to a new model of the cellular uptake of LalphaC complexes through activated fusion with endosomal membranes. Surface-functionalised complexes with poly(ethylene glycol)-lipids, potentially suitable for transfection invivo, have also been investigated, and the novel aspects of these complexes are discussed.

Cations↗
PubMed1997

Association of granulocyte transmigration with structural and cellular parameters of injury in experimental radiation enteropathy.

Inflammatory cells are involved in the pathogenesis of tissue injury through release of cytokines and biologically active compounds. This study used a novel, noninvasive method to assess the association between granulocyte transmigration and structural and molecular changes in radiation enteropathy. A 4 cm loop of rat small intestine was exposed to 0, 2.8, 12, or 23 Gy localized irradiation. Feces was collected in metabolic cages before and 3, 7, 14, 28, and 42 days after irradiation. Granulocyte marker protein (GMP) was measured in buffer extracts of feces by enzyme-linked immunosorbent assay (ELISA). Irradiated and shielded intestine were procured at 2 and 26 weeks and assessed for histopathologic injury [radiation injury score (RIS)], ED-2 positive macrophages, and interleukin-1 alpha (IL-1 alpha) positive cells. Irradiated intestine exhibited characteristic histopathologic alterations and increased numbers of macrophages and IL-1 alpha positive cells. There was a highly significant dose-dependent increase in post-radiation GMP (P < 0.0001). Maximal GMP excretion occurred 3-7 days after irradiation. Six weeks after irradiation, GMP excretion had returned to normal in the 2.8 and 12 Gy groups, but was still 3.5 times higher in the 23 Gy group than in controls. The associations between early GMP excretion and RIS and fibrosis at 26 weeks were highly significant (P < 0.001 and P < 0.0001, respectively). Post-radiation granulocyte transmigration is dose-dependent and correlates with structural and molecular changes, as well as with subsequent chronic injury. The GMP assay is a sensitive, non-invasive indicator of acute intestinal radiation injury and a promising biological predictor of chronic toxicity. Our data underscore the importance of consequential mechanisms in radiation enteropathy.

Animals↗
PubMed1988

Cytoplasmic membrane is the target organelle for transition metal mediated damage induced by paraquat in Escherichia coli.

Bacterial survival indicates that copper or iron is an essential mediator in paraquat toxicity in Escherichia coli [Kohen, R., & Chevion, M. (1985) Free Radical Res. Commun. 1, 79-88; Korbashi, P., Kohen, R., Katzhendler, J., & Chevion, M. (1986) J. Biol. Chem. 261, 12472-12476]. In this study we have identified the cytoplasmic membrane as a target organelle in metal-mediated paraquat toxicity and have demonstrated the complete correlation of the membrane damage with the levels of adventitious copper (or iron). The extent of membrane damage was related by use of four parameters: (a) the level of cellular ATP, (b) the level of cellular potassium, (c) the cellular capacity to accumulate and retain radiolabeled leucine, and (d) the cellular integrity as reflected by transmission electron microscopy (TEM). Exposure of bacterial cells to a combination of paraquat and copper caused a marked decline in parameters a, b, and c. This decline was found to occur in parallel with, or even to precede, the sharp loss of survival of E. coli under the same conditions. Likewise, TEM micrographs clearly indicated alterations in cellular structure that possibly reflect sites of detachment of the cytoplasmic membrane from the bacterial capsule. In contradistinction, copper alone or paraquat alone could not bring about similar changes in cellular structure. These findings are in accord with the suggested site-specific metal-mediated Haber-Weiss mechanism for paraquat toxicity and support our notion that specific chelators of transition metals could reduce or prevent the biological deleterious effects of this herbicide.

Adenosine Triphosphate↗
PubMed2004

Caspase-dependent inactivation of proteasome function during programmed cell death in Drosophila and man.

The caspase family of cysteine proteases plays a conserved role in the coordinate demolition of cellular structures during programmed cell death from nematodes to man. Because cells undergoing programmed cell death in nematodes, flies, and mammals all share common features, this suggests that caspases target a common set of cellular structures in each of these organisms. However, although many substrates for mammalian caspases have been identified, few substrates for these proteases have been identified in invertebrates. To search for similarities between the repertoires of proteins targeted for proteolysis by caspases in flies and mammals, we have performed proteomics-based screens in Drosophila and human cell lines undergoing apoptosis. Here we show that several subunits of the proteasome undergo caspase-dependent proteolysis in both organisms and that this results in diminished activity of this multicatalytic protease complex. These data suggest that caspase-dependent proteolysis decreases protein turnover by the proteasome and that this is a conserved event in programmed cell death from Drosophila to mammals.

Animals↗
PubMed2006

Hemoglobin-vesicles as a transfusion alternative.

Phospholipid vesicles or liposomes encapsulating purified and concentrated human hemoglobin (Hb-vesicle, HbV) have been developed as a transfusion alternative. They are void of blood-type antigens and infectious viruses; they are stable and suitable for long-term storage. The cellular structure of HbV (particle diameter, ca. 250 nm) prevents direct contact of Hb with the blood components and the endothelial lining shielding cells from the side effects of Hb molecules. Microcirculatory observations show that the cellular structure of HbV is important to control reactions with endothelium-derived vasorelaxation factors. Animal studies of extreme hemodilution and resuscitation from hemorrhagic shock attest to the sufficient oxygen transporting capacity of HbV. Studies of biodistribution and metabolism reveal that HbVs are captured eventually in the reticuloendothelial system, and degraded within one week. In a joint collaboration partnership of academia, a biotech venture company and a corporation, we plan to produce HbV with good manufacturing practices, and to start preclinical and, finally, clinical trials within a few years.

Animals↗
PubMed1992

[The grading of cellular and structural atypia in cancer and related lesions using multivariate analysis].

In morphologically diagnosing cancer, pathologists' attention is focussed on the presence or absence of atypia, i.e., the form of cells and tissues deviated from the norm, and if it is present, on its grade. However, due to retarded development of techniques for the objective evaluation of its grade, separation of cancer from premalignant lesions still meets great ambiguity. Particularly, the boundaries of "dysplasia" with cancer and noncancerous lesions are not defined in clear morphological terms and are susceptible to a strong between-observers fluctuation. In this paper we outlined our recent efforts to establish in various organs a statistically most adequate, and therefore reproducible, classification of atypical lesions, resorting to morphometry and multivariate analysis. Two examples were given: atypia of the pancreatic duct epithelia as an object for the study of purely cellular abnormalities, and hepatocellular carcinoma, which required also to quantify the atypia of tissue structures, The classifications thus established proved to be the most adequate, in that, they closely reflected the grade of malignancy in a clinical as well as biological sense, as shown by the clear between-categorier differences in oncogene mutation, DNA ploidy pattern, the patients' prognoses, and so on.

Cluster Analysis↗
PubMed1981

[Changes in the structure and cellular makeup of inguinal lymph nodes of white rats after dynamic and static loading].

Applying histological and morphometric methods, construction and cell composition of the inguinal lymph nodes have been studied in 125 white rats subjected to a daily dynamic (swimming) and static (hanging on a pole) loading. It has been demonstrated that the structural and cell composition changes of the lymph nodes depend but slightly on the character of the loading (dynamic or static), but rather essentially vary in the animals differently adapted to the loading. When adaptation is satisfactory, the rats gain in weight, in their lymph nodes the areas occupied by the connective tissue elements grow smaller, while the part of the cortical substance increases, with increasing number in them of follicles having light centres. As to the cell composition in the lymph node of these animals, a characteristic feature is an increasing amount of large and middle lymphocytes, lymphoblasts, plasmic cells and mitoses, that demonstrate an accelerated activity of the organism's immunological reactions. When adaptation to the physical loading is insufficient--exophtalmus, brown rings around the eyes appear, with a successive motor excitation. These animals poorly gain in weight, the number of lymphoblasts and large lymphocytes in the light follicular centres of their lymph nodes decreases, as well as the number of plasmic cells in the myelin cords; that demonstrates unsatisfactory immune processes.

Adaptation, Physiological↗
PubMed1994

Effects of single exposures to antiproliferative agents on ocular fibroblast-mediated collagen contraction.

PURPOSE: To determine the effects of short-duration treatments with 5-fluorouracil (5FU) and mitomycin-c (MMC) on "activated" and "nonactivated" ocular fibroblasts in collagen lattices. METHODS: Activated and nonactivated ocular fibroblasts seeded in collagen lattices were exposed to single 5-minute treatments with 5FU (0.01 to 25 mg/ml) and MMC (0.01 to 1 mg/ml). The effects of these treatments on lattice contraction, cellularity, cellular viability, cellular structure, and actin distribution were investigated. RESULTS: Treatment with 5FU (0.01 to 25 mg/ml) or MMC (0.1 to 1 mg/ml) significantly inhibited (P < 0.001 and P < 0.0001, respectively) lattice contraction compared to water controls. The degree of inhibition was greater in lattices containing nonactivated cells than in those containing activated cells. Activated cell viability and cellularity, unlike their nonactivated counterparts, were not significantly affected (P > 0.0083) by treatment with 5FU at high concentrations (25 mg/ml). MMC treatment had significant effects on cell viability and cellularity (P < 0.0001). Treatment with 5FU and MMC also affected cellular structure and actin distribution compared to water controls. CONCLUSIONS: Single, short exposures to 5FU or MMC inhibit ocular fibroblast-mediated collagen contraction. MMC causes cell death and a decrease in cellularity at high concentrations. The results also indicate that collagen lattices seeded with activated and nonactivated fibroblasts are differentially affected by short-term exposures to 5FU or MMC. These findings may have important clinical implications regarding the concentrations of these agents used in the treatment of different patient groups.

Actins↗