scholarly journals Substrate adhesion of rat hepatocytes: a comparison of laminin and fibronectin as attachment proteins.

1981 ◽  
Vol 90 (1) ◽  
pp. 260-264 ◽  
Author(s):  
S Johansson ◽  
L Kjellén ◽  
M Höök ◽  
R Timpl
Keyword(s):  
Cell Attachment ◽  
Periodate Oxidation ◽  
Rat Hepatocytes ◽  
The Other ◽  
Present Communication ◽  
Cellular Receptors ◽  
Initial Cell ◽  
Substrate Adhesion ◽  
Basement Membrane Protein ◽  
Attachment Proteins

In previous studies rat hepatocytes have been shown to adhere to substrates composed of collagen or fibronectin. In the present communication, the basement membrane protein laminin is reported to mediated the attachment and spreading of hepatocytes. The cell attachment-mediating activity of laminin was compared with that of fibronectin. The activity of fibronectin was heat sensitive, whereas laminin retained its activity after boiling. On the other hand, reduction and alkylation or periodate oxidation of the proteins affected only the cell attachment activity of laminin. Preincubation of cells with soluble fibronectin inhibited initial cell attachment to fibronectin but not to laminin substrates, and, reversely, soluble laminin selectively inhibited cell attachment to laminin. These results suggest that attachment of cells to substrates of the two proteins involves different cellular receptors recognizing distinct and nonidentical structures in the proteins.

scholarly journals Substrate adhesion of rat hepatocytes: on the mechanism of attachment to fibronectin.

1984 ◽  
Vol 98 (3) ◽  
pp. 810-817 ◽  
Author(s):  
S Johansson ◽  
M Höök
Keyword(s):  
Cell Attachment ◽  
Weak Interactions ◽  
Active Form ◽  
Rat Hepatocytes ◽  
Inhibitory Effect ◽  
Antigenic Structure ◽  
Cell Binding ◽  
Collagen Peptide ◽  
Substrate Adhesion ◽  
Species Specific

We examined the mechanisms of cell attachment to fibronectin-coated substrates. Inhibition of cell attachment was obtained by species-specific antifibronectin antibodies, which presumably recognize a distinct antigenic structure in the protein located at, or in the immediate vicinity of, the cell-binding site. The inhibiting antibodies could be adsorbed on a column of Sepharose substituted with plasma fibronectin. The initial phase of cell attachment was also inhibited by addition of soluble fibronectin to the incubation medium in a reaction that exhibited specificity and concentration dependence. These data suggest that cell-binding sites are available in an active form on the surface of soluble fibronectin. However, the inhibitory effect of fibronectin was greatly enhanced by adding the protein together with heparin, heparan sulfate, collagen, or a fibronectin-binding collagen peptide (CB-7), which is consistent with an "activation" of fibronectin on binding to these matrix components. A similar activation of fibronectin was obtained by cleaving the protein with trypsin. We discuss these findings in relation to conformational rearrangements in the fibronectin molecule. Data is presented supporting a mechanism of cell attachment to fibronectin involving multiple weak interactions between cellular receptors and substrate molecules, although some steps in the attachment process appear to disobey the requirements for such a mechanism.

Cytochemical Studies of Cell Wall Biosynthesis in Staphylococcus Aureus

1972 ◽  
Vol 30 ◽  
pp. 328-329
Author(s):  
Masaatsu Koike ◽  
Koichi Nakashima ◽  
Kyoko Iida
Keyword(s):  
Staphylococcus Aureus ◽  
Periodate Oxidation ◽  
Early Time ◽  
The Other ◽  
Penicillin G ◽  
Cell Wall Biosynthesis ◽  
Septal Wall ◽  
Peptidoglycan Biosynthesis ◽  
Gram Positive Bacteria ◽  
Cross Linkage

Penicillin exerts the activity to inhibit the peptide cross linkage between each polysaccharide backbone at the final stage of wall-peptidoglycan biosynthesis of bacteria. Morphologically, alterations of the septal wall and mesosome in gram-positive bacteria, which were occurred in early time after treatment with penicillin, have been observed. In this experiment, these alterations were cytochemically investigated by means of silver-methenamine staining after periodate oxidation, which is applied for detection of localization of wall mucopolysaccharide.Staphylococcus aureus strain 209P treated with 100 u/ml of penicillin G was divided into two aliquotes. One was fixed by Kellenberger-Ryter's OSO4 fixative at 30, 60 and 120 min after addition of the antibiotic, dehydrated through alcohol series, and embedded in Epon 812 (Specimen A). The other was fixed by 21 glutaraldehyde, dehydrated through glycolmethacrylate series and embedded in glycolmethacrylate mixture, according to Bernhard's method (Specimen B).

Matrix-Mineral Relationships-A. Morphologist's Viewpoint

1979 ◽  
Vol 58 (2_suppl) ◽  
pp. 922-929 ◽  
Author(s):  
M.U. Nylen
Keyword(s):  
Organic Material ◽  
Crucial Role ◽  
Crystal Surface ◽  
Organic Matrix ◽  
The Other ◽  
Enamel Matrix ◽  
Initial Cell ◽  
Cell Product ◽  
Ultrastructural Morphology ◽  
The Matrix

The literature on the ultrastructural morphology of the enamel matrix and its relationship to the crystals is reviewed. Two morphological entities of the matrix are discussed: One is the so-called stippled material which may be the initial cell product; the other, variously described as fibrillar, lamellar, tubular or helical, is thought by many to play a crucial role in nucleation and orientation of the crystals. A number of observations, however, suggest that the latter structures form secondarily to the crystals and that in reality they represent organic material adsorbed to the crystal surface and maintained as independent structures upon removal of the mineral. The need for additional studies is stressed including systematic studies of interactions between constituents of the organic matrix and the apatite crystals.

scholarly journals XXI. On the construction of a new calorimeter for determining the radiating powers of surfaces in air; and its application to the surfaces of various mineral substances

1860 ◽  
Vol 150 ◽  
pp. 379-408
Keyword(s):  
Surrounding Medium ◽  
The Other ◽  
Absolute Amount ◽  
Present Communication ◽  
Atmospheric Air ◽  
Glass Bulb ◽  
Heated Body ◽  
Series Of Experiments ◽  
Quantity Of Heat ◽  
Limited Induction

When my paper on the Conductivity of various Substances was presented to the Society, it was intimated to me on the part of the Council of the Society, that it might be advisable to determine absolute instead of relative conductivities, the latter being alone attempted in my previous experiments. It has been partly in consequence of this intimation, as well as from the desire to make my investigations the more complete, that I have given my attention to the construction of a calorimeter which might serve for this purpose. The present communication contains a description of this instrument, with the results which it has enabled me to obtain respecting the absolute quantities of heat which emanate from the surfaces of certain substances under given conditions. 1. When a body is placed in atmospheric air (or any gas), the quantity of heat which is lost from its surface in a given time, when its temperature is higher than that of the surrounding medium, will be greater than if it were placed in a vacuum, other conditions remaining unaltered. In the latter case the heat escapes by simple radiation; in the other case a portion of the heat also escapes in consequence of the contact of the air with the surface of the heated body. Dulong and Petit ascertained by a careful series of experiments, the laws according to which the mercury contained in the bulb of a thermometer cools, or those which govern the quantity of heat which escapes from the surface of the containing bulb, when placed in a vacuum, in air, or in several kinds of gases. These experiments were made with the glass bulb naked, and also when it was silvered, so that the laws of radiation which they established were strictly in reference only to surfaces of glass and those of silver. Certain laws were identical in both these cases, and hence it was concluded, though by a limited induction, that the same laws were applicable to all other surfaces. They did not, however, give the absolute quantity of heat which, under given circumstances, and in a given time, emanates from the surfaces of the glass or silver with which they experimented. The instrument which I have constructed gives very easily this absolute amount of heat, as I believe, with very approximate accuracy.

scholarly journals Testing the in vitro performance of hydroxyapatite coated magnesium (AZ91D) and titanium concerning cell adhesion and osteogenic differentiation

2015 ◽  
Vol 16 (1) ◽  
Author(s):  
Claudia Kleinhans ◽  
Gabriele Vacun ◽  
Roman Surmenev ◽  
Maria Surmeneva ◽  
Petra Juliane Kluger
Keyword(s):  
Cell Adhesion ◽  
Osteogenic Differentiation ◽  
Cell Attachment ◽  
Human Mesenchymal Stem Cell ◽  
Adhesion Properties ◽  
Sputtering Deposition ◽  
Initial Cell ◽  
Tissue Culture Polystyrene ◽  
Diffraction Patterns

AbstractIn the current study the in vitro outcome of a degradable magnesium alloy (AZ91D) and standard titanium modified by nanostructured-hydroxyapatite (n-HA) coatings concerning cell adhesion and osteogenic differentiation was investigated by direct cell culture. The n-HA modification was prepared via radio-frequency magnetron sputtering deposition and proven by field emission scanning electron microscopy and X-ray powder diffraction patterns revealing a homogenous surface coating. Human mesenchymal stem cell (hMSCs) adhesion was examined after one and 14 days displaying an enhanced initial cell adhesion on the n-HA modified samples. The osteogenic lineage commitment of the cells was determined by alkaline phosphatase (ALP) quantification. On day one n-HA coated AZ91D exhibited a comparable ALP expression to standard tissue culture polystyrene samples. However, after 14 days solely little DNA and ALP amounts were measurable on n-HA coated AZ91D due to the lack of adherent cells. Titanium displayed excellent cell adhesion properties and ALP was detectable after 14 days. An increased pH of the culture was measured for AZ91D as well as for n-HA coated AZ91D. We conclude that n-HA modification improves initial cell attachment on AZ91D within the first 24 h. However, the effect does not persist for 14 days in in vitro conditions.

scholarly journals Some nuclear transformations of beryllium and boron and the masses of the light elements

1935 ◽  
Vol 150 (869) ◽  
pp. 241-258 ◽  
Keyword(s):  
Spontaneous Emission ◽  
Periodic Table ◽  
Small Error ◽  
The Other ◽  
Light Elements ◽  
Mass Energy ◽  
Present Communication ◽  
Mass Data ◽  
The Masses ◽  
Α Particles

In a recent paper we showed that the nuclear transformations produced in lithium by bombarding the element with protons and with ions of heavy hydrogen were in complete accord with the laws of the conservation of mass-energy and of momentum. At the same time we pointed out that there were serious discrepancies between the mass-data and the transformation-data in some other cases, and we stressed the fact that the concordance for lithium was one between mass-differences, and gave no test of the correctness or otherwise of the absolute masses in terms of O 16 = 16·000. In the present communication we present the results of experiments on the transformation of beryllium and boron by protons and by ions of heavy hydrogen. It is shown that it is not possible to interpret these results on the mass-data at present available, and we indicate how the difficulties may be overcome by the assumption of a single small error in the mass-spectrographic value for the mass of He 4 . Beryllium So far as it is known beryllium consists of a single isotope,* the mass of which according to Bainbridge is 9·0155. This mass is greater than that of two α-partieles and a neutron (8·0043 + 1·0080§ = 9·0123) by nearly three million volts, and hence great difficulties have been en­countered in nuclear theory in accounting for the observed stability. It had been found by Rayleigh|| that the mineral beryl contained an abnormal quantity of helium, while the experiments of Curie-Joliot and of Chadwick¶ had shown that beryllium gave a copious emission of neutrons when bombarded by α-particles, but the most careful search has failed to give any evidence whatever for a spontaneous emission of particles from the element. Both lithium and boron, of atomic numbers 3 and 5 respectively, are very easily transformed by bombardment wit protons and with ions of heavy hydrogen, so that it was to be expected that beryllium, which lies between them in the periodic table, would also give effects when bombarded by the same ions. Observation of the energies evolved if the reactions are known with certainty, should then lead to values for the mass of Be 9 in terms of the masses of the other products of the transformations, which can be used to check the mass found by Bainbridge.

scholarly journals DNA and proteins of the nuclear matrix are the main targets of benzo[a]pyrene's action in rat hepatocytes.

1993 ◽  
Vol 40 (4) ◽  
pp. 559-562 ◽  
Author(s):  
P Widłak ◽  
J Rzeszowska-Wolny
Keyword(s):  
Molecular Weight ◽  
Dna Adducts ◽  
Dna Sequences ◽  
Nuclear Matrix ◽  
Rat Hepatocytes ◽  
The Other ◽  
Matrix Proteins ◽  
Nuclear Matrix Proteins ◽  
Cultured Rat Hepatocytes ◽  
High Molecular Weight Proteins

The binding of [14C]benzo[a]pyrene (B[a]P) to DNA and proteins in total nuclei and subnuclear fractions of cultured rat hepatocytes was compared. The main targets of B[a]P were non-histone high molecular weight proteins of the nuclear matrix and DNA sequences attached to this structure. Following 24 h exposure to B[a]P the amounts of adducts in the nuclear matrix DNA and proteins were twice as high as in total nuclei. After withdrawal of the carcinogen containing medium the level of B[a]P-induced adducts gradually decreased but always remained the highest in the nuclear matrix proteins. Removal of adducts from the nuclear matrix DNA was more efficient than from the other DNA fractions, and 72 h after exposure to the carcinogen the level of DNA adducts in this fraction was similar to that in total nuclei.

scholarly journals V.—Note on an Undescribed Area of Lower Greensand or Vectian in Dorset

1891 ◽  
Vol 8 (10) ◽  
pp. 456-458 ◽  
Author(s):  
A. J. Jukes-Browne
Keyword(s):  
Lower Cretaceous ◽  
Small Area ◽  
Upper Cretaceous ◽  
The Other ◽  
Present Communication ◽  
The Subject ◽  
Geological Magazine

Until recently no outcrop of the Vectian or Lower Greensand was known to occur between Lulworth on the coast of Dorset and the neighbourhood of Devizes in Wiltshire. It was supposed that, with the exception of a small area of Wealden in the Vale of Wardour, the whole of the Lower Cretaceous Series in Dorset and South Wilts was concealed and buried beneath the overlapping Upper Cretaceous strata. A recent examination of this district however has revealed two areas where the Vectian sands emerge from beneath the Gault. One of these has already been indicated in the pages of the Geological Magazine; the other is the subject of the present communication.

The effects of substrate morphology by regulating pseudopods formation on cell directional alignment and migration

2021 ◽  
Author(s):  
Jing Zou ◽  
Kun Jin ◽  
Tongsheng Chen ◽  
Xinlei Li
Keyword(s):  
Cell Membrane ◽  
Substrate Surface ◽  
Membrane Curvature ◽  
Curvature Radius ◽  
Nano Structure ◽  
Initial Cell ◽  
Substrate Adhesion ◽  
Directional Alignment ◽  
And Migration ◽  
Minimum Resistance

Abstract When cells are cultured on the micro- or nano- structure substrate, filamentous pseudopods are formed at specific locations due to the effects of substrate morphology and local membrane curvature, which provides a powerful method to guide cell migration and neurite orientation. However, it is unclear the effects of substrate surface morphology and initial cell membrane on pseudopod formation and growth. Here, we present a quantitative thermodynamic model to investigate the difficulty of pseudopod formation. Based on the established model, we studied the effects of substrate morphology and the curvature of the initial cell membrane on filamentous pseudopods formation by analyzing the magnitude of an average driving force. We find that the pseudopod-substrate adhesion and the larger curvature radius of the initial cell membrane can facilitate filamentous pseudopods formation due to the smaller minimum resistance energy. Furthermore, our theoretical results seem to show a broad agreement with experimental observations, which implies that these studies would provide useful guidance to control the pseudopods formation on substrate for biomedical applications.

scholarly journals The transfer of mannose to dolichol diphosphate oligosaccharides in pig liver endoplasmic reticulum

1975 ◽  
Vol 152 (2) ◽  
pp. 191-199 ◽  
Author(s):  
Gerard J. A. Oliver ◽  
Frank W. Hemming
Keyword(s):  
Endoplasmic Reticulum ◽  
Periodate Oxidation ◽  
The Other ◽  
Microsomal Preparation ◽  
Pig Liver ◽  
Mannose Residue ◽  
Chromatographic Data ◽  
Endogenous Lipid

The transfer, catalysed by pig liver microsomal preparations, of mannose, from GDP-mannose, to lipid-linked oligosaccharides and the properties of the products are described. Solubility, hydrolytic and chromatographic data suggest that they are dolichol diphosphate derivatives. The presence of two N-acetyl groups in at least part of the heterogenous oligosaccharide portion was tentatively deduced. Reduction with borohydride of the oligosaccharide showed that the newly added mannose residues were not at its reducing end. Periodate oxidation suggested that 60% of these were at the non-reducing terminus and that 40% were positioned internally. T.l.c. showed the presence of seven oligosaccharide fractions with chromatographic mobilities corresponding to glucose oligomers with 7–13 residues. The molar proportions of the oligosaccharide fractions in the mixture were determined by borotritiide reduction and the number of mannose residues added to each oligosaccharide fraction during the incubation was calculated. Two of the oligosaccharide fractions had received on average one, or slightly more than one, mannose residue per chain during the incubation; four of the other fractions were each shown to be a mixture, 20–25% of which had received one mannose residue during the incubation and 75–80% of which had not been mannosylated during the incubation. This supported other evidence for the presence of endogenous lipid-linked oligosaccharides in the microsomal preparation which had been formed before the incubation in vitro. Evidence for the possibility of two pools of dolichol monophosphate mannose, one being more closely associated with mannosyl transfer to dolichol diphosphate oligosaccharides than the other, is also discussed.

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