Some effects of positively charged surface groups on cell aggregation

1976 ◽  
Vol 21 (2) ◽  
pp. 219-225
Author(s):  
D.E. Maslow ◽  
L. Weiss
Keyword(s):  
Amino Acids ◽  
Electrophoretic Pattern ◽  
Aggregate Size ◽  
Cell Aggregation ◽  
Neural Retina ◽  
Minor Role ◽  
Cell Periphery ◽  
Cellulose Acetate Electrophoresis ◽  
A Minor ◽  
Positively Charged

A study was made of the effects of 2,3-dimethylmaleic anhydride (DMA), a reagent removing positive charges, on the aggregation and surface charge of embryonic chick neural retina cells. Neural retina cells, recovered from the dissociation procedure, were cultured on a gyratory shaker and the aggregate dimaeters formed in the presence of DMA or DMA-serum dialysate, following DMA-pretreatment, or in appropriate control cultures measured. The electrophoretic mobilities of similarly treated cells were also determined. In addition, cellulose acetate electrophoresis was carried out on samples of serum containing DMA, and the incorporation of 14C-amino acids into DMA-treated cells studied. Aggregates formed in the presence of DMA, or following DMA-pretreatment, were significantly smaller than aggregates from control cultures. The electrophoretic mobility of DMA-treated cells was significantly increased in serum-containing medium, but not serum-free Hanks' solution. At 24 h after removal of DMA-containing medium, the mobilities of pretreated cells were similar to those of controls. The electrophoretic pattern of DMA-treated serum was changed only with concentrations of DMA many times that affecting cell aggregation or mobility. DMA-serum dialysate did not significanlty reduce aggregate size. The incorporation of 14C-amino acids in DMA-treated cells and the structure of aggregates were unchanged from controls. It is concluded that positively charged consituents of the cell periphery play a demonstrable, but not limiting, role in cell aggregation, while a minor role for positive charges on serum protein cannot be totally excluded.

The effects of tumour cells on embryonic cell aggregation, adhesion and detachment

1978 ◽  
Vol 29 (1) ◽  
pp. 271-275
Author(s):  
D.E. Maslow ◽  
L. Weiss
Keyword(s):  
Aggregate Size ◽  
Cell Aggregation ◽  
Inhibitory Effect ◽  
Neural Retina ◽  
Embryonic Cell ◽  
Tumour Cells ◽  
Ehrlich Ascites ◽  
Initial Adhesion ◽  
Ehrlich Ascites Cells ◽  
Gyratory Shaker

The presence of small numbers of tumour cells inhibits the aggregation of embryonic chicken neural retina cells grown in gyratory shaker culture. The aggregation of neural retina cells was also inhibited by ascites cell medium. We investigated whether the inhibitory effect of the tumour cells on aggregate size is effected by inhibition of the initial adhesion or by enhancement of their separation. The number of neural retina cells adherent to microtest plate surfaces was significantly reduced after incubation with either Ehrlich ascites cells or cell-free, conditioned medium, while the percentage of cells removed from glass by shearing was unchanged under those conditions. These results suggest that the reduction in neural retina cell aggregate size produced by Ehrlich ascites cells and their products is due to partial inhibition of neural retina cell adhesion processes, as distinct from enhancement of separation.

scholarly journals The fate of absorbed and exogenous ammonia as influenced by forage or forage–concentrate diets in growing sheep

1996 ◽  
Vol 76 (2) ◽  
pp. 231-248 ◽  
Author(s):  
G. E. Lobley ◽  
P. J. M. Weijs ◽  
A. Connell ◽  
A. G. Calder ◽  
D. S. Brown ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Ammonium Salt ◽  
Free Amino ◽  
Essential Amino Acids ◽  
Whole Body ◽  
Minor Role ◽  
N Removal ◽  
A Minor ◽  
Branched Chains

Changes in splanchnic energy and N metabolism were studied in sheep, prepared with vascular catheters across the portal-drained viscera (PDV) and the Liver, and maintained on supramaintenance intakes of either grass or grass + barley pellets. The animals were challenged, on both diets, with 4 d intra- mesenteric vein infusions of NH4CI (25 µmol/min) plus NH4HCO3(at either 0 or 125 µmol/min). On the final day of each treatment the natural abundance NH4Cl was replaced with15NH4Cl over a 10 h infusion while over the same period [l-13C]leucine was infused via a jugular vein. Measurements were made of blood flow plus mass transfers of NH3, urea, free amino acids and O2, across the PDV and liver. Enrichments of [14N15N]urea and [15N15N]urea plus [15N]glutamine, aspartate and glutamate were also monitored. Whole-body urea flux was determined by infusion of [14C]urea. At the end of the study the animals were infused for 3 h with15NH4CI, killed and liver samples assayed for intracellular free amino acid enrichments and concentrations. Blood flows across the splanchnic region were unaffected by either diet or level of ammonium salt infusion. At the lower ammonium salt infusion there was a trend for greater absorption of NH3across the PDV (P<0·10) with grass + barley than with the grass diet, while removal of urea was unaltered. At the higher ammonium salt infusions there was a significantly greater appearance of NH, across the PDV and this exceeded the extra infused. Urea-N removal, however, was also elevated and by more than that required to account for the additional NH3. The PDV contributed 19–28% to whole-body O2consumption and the liver 23–32%. Hepatic extraction of absorbed NH3was complete on all treatments and systemic pH remained constant. The fractions of urea-N apparently derived from NH3, were similar on the grass (0·59–0·64) and grass + barley (0·64–0·67) diets. Hepatic production of urea agreed well with urea flux measurements. Between the two levels of ammonium salt infusion and within diets the additional NH3removed across the PDV was accounted for by the increased urea-N production. The [14N15N]: [15N15N] ratio of the urea produced was 97:3, while the enrichment of hepatic intracellular free aspartate was lower than that of [14N15N]urea. Glutamine enrichments were 0·23–0·37 those of [14N15N]urea, indicating a minor role for those hepatocytes (probably perivenous) which contain glutamine synthetase (EC6.3.1.2). Leucine kinetics, either for the whole body or splanchnic tissues, were not different between diets or level of ammonium salt infusion, except for oxidation which was less on the grassfbarley ration. Amino acid concentrations were lower on the grass + barley diet but net PDV absorptions were similar. The pattern of essential amino acids absorbed into the PDV showed good agreement with the published composition of mixed rumen microbial protein. Fractional disappearances of absorbed free essential amino acids across the liver varied from 0·4 (branched chains) to near unity (histidine, phenylalanine)

Possible mechanisms for the initiation and maintenance of postprandial intestinal hyperemia

1985 ◽  
Vol 249 (3) ◽  
pp. G301-G308 ◽  
Author(s):  
R. H. Gallavan ◽  
C. C. Chou
Keyword(s):  
Amino Acids ◽  
Blood Flow ◽  
Minor Role ◽  
Regulatory Pathways ◽  
Intestinal Peptides ◽  
Undigested Food ◽  
A Minor ◽  
Tissue Osmolality ◽  
Hyperemic Response

Postprandial intestinal hyperemia is a locally mediated vascular response to the presence of nutrients in the lumen. In this review we discuss the role of various constituents of chyme in the development of the hyperemia and possible mechanisms of action. The luminal contents that produce the hyperemia are digested products of food; undigested food or pancreatic enzymes have no effect. Micellar fatty acids are the most potent vasodilators, whereas amino acids at physiological concentrations have little effect on intestinal blood flow. However, by-products of protein digestion are as potent as those of carbohydrates in increasing the blood flow. Bile increases ileal but does not alter jejunal blood flow. In addition, bile enhances the glucose-induced hyperemia and renders fatty and amino acids vasoactive. The mechanisms by which bile exerts its effect on the vasoactivity of these nutrients are poorly understood. The intestinal hyperemic response to the presence of nutrients in the lumen is mediated by a variety of regulatory pathways that vary with the nutrient. Factors involved include tissue metabolic rate, metabolites, nutrient absorption, tissue osmolality, tissue oxygen tension, intestinal peptides such as neurotensin and vasoactive intestinal polypeptide, and paracrine substances such as prostaglandins and histamine. It is likely that the hyperemia results from the complex interplay of all these factors on the intestinal vascular smooth muscle. Extrinsic and intrinsic nerves play a minor role in nutrient-induced hyperemia.

Drug-Protein Interaction: 8-Methoxy Psoralen as Photosensitizer of Enzymes and Amino Acids

1979 ◽  
Vol 34 (5-6) ◽  
pp. 392-396 ◽  
Author(s):  
F. M. Veronese ◽  
O. Schiavon ◽  
R. Bevilacqua ◽  
G. Rodighiero
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Methylene Blue ◽  
Mechanism Of Action ◽  
Protein Interaction ◽  
Rose Bengal ◽  
Molecular Basis ◽  
Minor Role ◽  
Low Molecular Weight ◽  
A Minor

Abstract For a better insight of the molecular basis of the photobiological effects of furocoumarins, the relevance of proteins oxydation by singlet oxygen produced by these substrates under irradiation with long u. v. light was studied.Complex oligomeric as well as simple monomeric purified enzymes with high or low molecular weight and different properties and simple amino acids were irradiated under oxygen in presence of 8-methoxy-psoralen. The effects on both proteins and amino acids were compared with those obtained under similar conditions with typical photosensitizers as methylene blue and Rose Bengal. The results indicated that the photooxydation of proteins, although possible, appears to play a minor role, if any, in the mechanism of action of furocoumarin.

A Quantitative Structure-Property Relationship Study of the Adsorption of Amino Acids on Kaolinite Surfaces

2018 ◽  
Vol 3 (2) ◽  
pp. 21-35 ◽  
Author(s):  
Yu Heng Ou ◽  
Len Chang ◽  
Chia Ming Chang
Keyword(s):  
Amino Acids ◽  
Chemical Potential ◽  
Electron Flow ◽  
Minor Role ◽  
Quantitative Structure ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Adsorption Behaviors ◽  
Quantitative Structure Property Relationships ◽  
A Minor

This article describes how the adsorption behaviors of various kinds of amino acids onto kaolinite surfaces were investigated by the quantum-chemical calculations and the quantitative structure-property relationships (QSPR). The QSPR results revealed that both adsorption energies of amino acids on tetrahedral Si-O and octahedral Al-O surfaces were mainly affected by the chemical potential and the negative of maximum negative charges of amino acids, which represent the electron flow and the hydrogen bonding between adsorbent-adsorbate interactions. The dispersion and polarization play a minor role in the amino acids adsorption on tetrahedral Si-O and octahedral Al-O surfaces, respectively.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

Use of Different Tissue Thromboplastins in the Control of Anticoagulant-Therapy

1958 ◽  
Vol 02 (05/06) ◽  
pp. 462-480 ◽  
Author(s):  
Marc Verstraete ◽  
Patricia A. Clark ◽  
Irving S. Wright
Keyword(s):  
Prothrombin Time ◽  
Anticoagulant Therapy ◽  
Factor Vii ◽  
Rabbit Brain ◽  
Minor Role ◽  
Rabbit Lung ◽  
Coagulation Mechanism ◽  
Time Test ◽  
The One ◽  
A Minor

SummaryAn analysis of the results of prothrombin time tests with different types of thromboplastins sheds some light on the problem why the administration of coumarin is difficult to standardize in different centers. Our present ideas on the subject, based on experimental data may be summarized as follows.Several factors of the clotting mechanism are influenced by coumarin derivatives. The action of some of these factors is by-passed in the 1-stage prothrombin time test. The decrease of the prothrombin and factor VII levels may be evaluated in the 1-stage prothrombin time determination (Quick-test). The prolongation of the prothrombin times are, however, predominantly due to the decrease of factor VII activity, the prothrombin content remaining around 50 per cent of normal during an adequate anticoagulant therapy. It is unlikely that this degree of depression of prothrombin is of major significance in interfering with the coagulation mechanism in the protection against thromboembolism. It may, however, play a minor role, which has yet to be evaluated quantitatively. An exact evaluation of factor VII is, therefore, important for the guidance of anticoagulant therapy and the method of choice is the one which is most sensitive to changes in factor VII concentration. The 1-stage prothrombin time test with a rabbit lung thromboplastin seems the most suitable method because rabbit brain preparations exhibit a factor VII-like activity that is not present in rabbit lung preparations.

Produktivkraft als Versprechen

2016 ◽  
Vol 46 (185) ◽  
pp. 621-638 ◽  
Author(s):  
Christian Siefkes
Keyword(s):  
Private Consumption ◽  
Minor Role ◽  
Progressive Reduction ◽  
Internal Forces ◽  
A Minor

The ‘Fragment on Machines’ from Marx’s Grundrisse is often cited as an argument that the internal forces of capitalism will lead to its doom. But the argument that the progressive reduction of labor must doom capitalism lacks a proper foundation, as a comparison with the ‘Schemes of Reproduction’ given in Capital II shows. The latter, however, aren’t fully convincing either. In reality, more depends on the private consumption of capitalists than either model recognizes. Ultimately, most can be made of the ‘Fragment on Machines’ by reading it not as an exposure of capitalism’s internal contractions, but as a discussion of a possible communist future where labor (or work) will play but a minor role.

Effects of Myo-inositol Alone and in Combination with Seleno-Lmethionine on Cadmium-Induced Testicular Damage in Mice

2019 ◽  
Vol 12 (4) ◽  
pp. 311-323 ◽  
Author(s):  
Salvatore Benvenga ◽  
Antonio Micali ◽  
Giovanni Pallio ◽  
Roberto Vita ◽  
Consuelo Malta ◽  
...  
Keyword(s):  
Structural Changes ◽  
Natural Antioxidants ◽  
Minor Role ◽  
Positive Role ◽  
Testosterone Levels ◽  
Tnf Α ◽  
Testicular Lesions ◽  
A Minor ◽  
Immunohistochemical Analyses

Background: Cadmium (Cd) impairs gametogenesis and damages the blood-testis barrier. Objective: As the primary mechanism of Cd-induced damage is oxidative stress, the effects of two natural antioxidants, myo-inositol (MI) and seleno-L-methionine (Se), were evaluated in mice testes. Methods: Eighty-four male C57 BL/6J mice were divided into twelve groups: 0.9% NaCl (vehicle; 1 ml/kg/day i.p.); Se (0.2 mg/kg/day per os); Se (0.4 mg/kg/day per os); MI (360 mg/kg/day per os); MI plus Se (0.2 mg/kg/day); MI plus Se (0.4 mg/kg/day); CdCl2 (2 mg/kg/day i.p.) plus vehicle; CdCl2 plus MI; CdCl2 plus Se (0.2 mg/kg/day); CdCl2 plus Se (0.4 mg/kg/day); CdCl2 plus MI plus Se (0.2 mg/kg/day); and CdCl2 plus MI plus Se (0.4 mg/kg/day). After 14 days, testes were processed for biochemical, structural and immunohistochemical analyses. Results: CdCl2 increased iNOS and TNF-α expression and Malondialdehyde (MDA) levels, lowered glutathione (GSH) and testosterone, induced testicular lesions, and almost eliminated claudin-11 immunoreactivity. Se administration at 0.2 or 0.4 mg/kg significantly reduced iNOS and TNF-α expression, maintained GSH, MDA and testosterone levels, structural changes and low claudin-11 immunoreactivity. MI alone or associated with Se at 0.2 or 0.4 mg/kg significantly reduced iNOS and TNF-α expression and MDA levels, increased GSH and testosterone levels, ameliorated structural organization and increased claudin-11 patches number. Conclusion: We demonstrated a protective effect of MI, a minor role of Se and an evident positive role of the association between MI and Se on Cd-induced damages of the testis. MI alone or associated with Se might protect testes in subjects exposed to toxicants, at least to those with behavior similar to Cd.

Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

1985 ◽  
Vol 50 (3) ◽  
pp. 581-599 ◽  
Author(s):  
Petr Vaňura ◽  
Emanuel Makrlík
Keyword(s):  
Stability Constants ◽  
Organic Phase ◽  
Equilibrium Constants ◽  
Minor Role ◽  
Nitrobenzene Solution ◽  
Ligand Structure ◽  
Stability Constants Of Complexes ◽  
Separation Factors ◽  
The Stability ◽  
A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

Sign in / Sign up

Export Citation Format

Share Document