scholarly journals The biosynthesis of intestinal mucins. The effect of salicylate on glycoprotein biosynthesis by sheep colonic and human gastric mucosal tissues in vitro

1968 ◽  
Vol 106 (3) ◽  
pp. 645-658 ◽  
Author(s):  
P W Kent ◽  
A. Allen
Keyword(s):  
Oxygen Consumption ◽  
Amino Sugar ◽  
Inhibitory Effect ◽  
Total Radioactivity ◽  
Human Gastric Mucosa ◽  
Enzyme Preparations ◽  
Acetylneuraminic Acid ◽  
Control Value ◽  
Glycoprotein Biosynthesis

1. Incubation of sheep colonic mucosal scrapings in Krebs–Ringer buffer for 2½hr. in the presence of salicylate (15mm) resulted in decreased incorporation of radioactivity into the epithelial glycoprotein from the following labelled precursors: 16·6μm-d-[2−14C]glucose (83·9% inhibition), 20μm-l-[U−14C]threonine (82%) and 35SO42−(79%). Oxygen uptake measured simultaneously was diminished to 41% of the control value. 2. At lower concentrations of salicylate (e.g. 3·75mm), incorporation of 20μm-l-[U−14C]threonine was little affected (3–6% inhibition), whereas utilization of 4μm-d-[U−14C]glucose and 35SO42− was inhibited (41–48% and 40–59% of the control values respectively). 3. Analysis of the papain-digested glycoprotein from tissue incubations with 16·6μm-d-[2−14C]glucose in the presence of salicylate (3·75mm) showed large decreases in labelling of N-acetylneuraminic acid and N-glycollylneuraminic acid residues (57% and 34% of the control values respectively) and of hexosamine constituents (glucosamine, 55% inhibition; galactosamine, 33% inhibition). Labelling of neutral sugars (galactose and fucose) was relatively little affected (9 and 11% inhibition respectively). 4. Glucose 6-phosphate transaminase and glucosamine 6-phosphate acetylase in particle-free enzyme preparations of the sheep tissue were unaffected by salicylate at the above concentrations. Acetyl-CoA synthetase was markedly inhibited. 5. Human gastric mucosa (from operation), on incubation as above, had in one experiment an oxygen consumption of 9·9μl./hr./mg. dry wt. of tissue and incorporated 5μm-d-[U−14C]glucose (15·8% of the total radioactivity added) into bound hexosamine (20·6% of the total radioactivity incorporated), hexoses (glucose and galactose, 5·7%) and fucose (14·2%). The presence of salicylate (15mm) decreased the incorporation of 5μm-d-[U−14C]glucose into the glycoprotein by 74%, all sugar constituents being affected, without influence on the rate of oxygen consumption. 6. The results suggest an inhibitory effect of salicylate on glycoprotein biosynthesis at the level of the amino sugar intermediates.

scholarly journals Inhibitory effect of propafenone derivatives on pseudomonas aeruginosa biofilm and pyocyanin production

2020 ◽  
Vol 148 (3-4) ◽  
pp. 196-202
Author(s):  
Snjezana Petrovic ◽  
Jasmina Basic ◽  
Zoran Mandinic ◽  
Dragana Bozic ◽  
Marina Milenkovic ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Laboratory Strain ◽  
Inhibitory Effect ◽  
Negative Control ◽  
Clinical Strains ◽  
Control Value ◽  
Essential Components ◽  
Pyocyanin Production

Introduction/Objective. Biofilm and pyocyanin production are essential components of Pseudomonas aeruginosa virulence and antibiotic resistance. Our objective was to examine inhibitory effect of synthetized propafenone derivatives 3-(2-Fluorophenyl)- 1-(2- (2-hydroxy-3-propylamino-propoxy)-phenyl)-propan-1-one hydrochloride (5OF) and3-(2- Trifluoromethyl-phenyl)-1-(2-(2-hydroxy-3-propylamino-propoxy)-phenyl)-propan-1-one hydrochloride (5CF3) on biofilm and pyocyanin in Pseudomonas aeruginosa clinical strains. Methods. Effects were tested on nine clinical isolates and one control laboratory strain of P. aeruginosa. In vitro analysis of biofilm growing was performed by incubating bacteria (0.5 McFarland) with 5OF and 5CF3 (500?31.2 ?g/ml) and measuring optical density (OD) at 570 nm. Bacteria in medium without compounds were positive control. Blank medium (an uninoculated medium without test compounds) was used as negative control. Pyocyanin production was estimated by OD at 520 nm, after bacteria incubated with 5CF3 and 5OF (250 and 500 ?g/ml), treated with chloroform, and chloroform layer mixed with HCl. Results. A total of 500 ?g/ml of 5OF and 5CF3 completely inhibited biofilm formation in 10/10 and 4/10 strains, respectively. A total of 250 ?g/ml of 5OF and 5CF3 strongly inhibited biofilm formation in 7/10 strains, while inhibition with 125 ?g/ml of 5OF and 5CF3 was moderate. Lower concentrations had almost no effect on biofilm production. Pyocyanin production was reduced to less than 40% of the control value in 6/9, and less than 50% of the control in 7/9 strains with 500 ?g/ml of 5OF and 5CF3, respectively. At 250 ?g/ml 5OF and 5CF3, most strains had pyocyanin production above 50% of the control value. Conclusion. Synthetized propafenone derivatives, 5OF and 5CF3, inhibited biofilms and pyocyanin production of Pseudomonas aeruginosa clinical strains. Presented results suggest that propafenone derivatives are potential lead-compounds for synthesis of novel antipseudomonal drugs.

scholarly journals Mechanisms of zinc uptake in gills of freshwater rainbow trout: interplay with calcium transport

1996 ◽  
Vol 270 (5) ◽  
pp. R1141-R1147 ◽  
Author(s):  
C. Hogstrand ◽  
P. M. Verbost ◽  
S. E. Bonga ◽  
C. M. Wood
Keyword(s):  
Rainbow Trout ◽  
Control Level ◽  
Inhibitory Effect ◽  
Chloride Cells ◽  
Water Addition ◽  
Uptake Mechanism ◽  
Basolateral Membranes ◽  
Control Value

The uptake mechanism of Zn2+ through the gill epithelium of freshwater rainbow trout was investigated both in intact animals and in isolated basolateral membranes. Involvement of the apical Ca2+ uptake sites in Zn2+ uptake was examined in vivo by pharmacological manipulation of the apical Ca2+ permeability. The apical entries of Ca2+ and Zn2+, but not Na2+ and Cl-, were inhibited by addition of La to the water. Addition of 1.0 microM La reduced the influxes of Ca2+ and Zn2+ to 22 +/- 3 and 53 +/- 7% (mean +/- SE) of the control value, respectively. Injection of CaCl2 also reduced the branchial influxes of Ca2+ and Zn2+. This treatment decreased the influx of Ca2- to 45 +/- 4% of the control level and the Zn2+ influx to 68 +/- 5%. These results strongly imply that Zn2+ passes across the apical membrane of the chloride cells of the gills via the same pathway as Ca2+. The presence of an active basolateral transporter for Zn2+ was investigated in vitro on isolated basolateral membranes. There was no ATP-dependent or Na2+(-)gradient driven transport of Zn2+ at physiological Zn2+ activities. The same system was used to study potential effects of Zn2+ on the basolateral Ca2+(-)adenosinetri-phosphatase. Zn2+ was found to be a potent blocker of this transporter, causing a mixed inhibitory effect on the ATP driven Ca2+ transport at a free Zn2+ activity of 100 pM.

EFFECTS OF DIHYDROSTREPTOMYCIN ON AMINO ACID INCORPORATION INTO THE PROTEINS OF M. TUBERCULOSIS (BCG)

1959 ◽  
Vol 37 (1) ◽  
pp. 687-697
Author(s):  
E. Stachiewicz ◽  
J. H. Quastel
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Sodium Stearate ◽  
Ehrlich Ascites Carcinoma ◽  
Inhibitory Effect ◽  
Total Radioactivity ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Drug Concentrations

A study has been made of the effects of dihydrostreptomycin on amino acid incorporation into the proteins of M. tuberculosis (BCG). Suspensions of this organism on incubation at 37° with glycine-1-C14give rise, aerobically, to labelled proteins in which 80% of the radioactivity appears in the glycine and serine moieties of the proteins and about 20% in alanine and aspartic acid. In presence of glycine-2-C14, radioactivity appears in a larger number of amino acids of the protein. Incubation with serine-3-C14leads to a distribution of radioactivity in the amino acids in BCG proteins but alanine-1-C14and valine-1-C14give rise to proteins with the radioactivity almost entirely in the corresponding amino acids. The process of aerobic incorporation of radioactivity from glycine-1-C14in BCG proteins is stimulated by the presence of glucose, glycerol, sodium pyruvate, sodium stearate, or sodium benzoate in the medium in which the cells are incubated, the rate of incorporation being approximately constant over a period of 4 hours. The incorporation depends largely on the presence of oxygen. Dihydrostreptomycin (33 μg per ml) markedly inhibits labelling of proteins in the cell suspensions in presence of radioactive amino acids, the inhibition increasing with concentration of the streptomycin to an optimal concentration of 200 μg/ml. Penicillin and isonicotinic hydrazide are inactive but chloromycetin is an effective inhibitor. Cyanide, arsenite, and azide are inhibitory. The presence of lecithin stimulates incorporation of radioactivity from glycine-1-C14into BCG proteins. Dihydrostreptomycin inhibitions of amino acid incorporation into BCG proteins increase with time of incubation of the cells with the drug. Concentrations of dihydrostreptomycin that inhibit labelled amino acid incorporation into labelled proteins by 50% have no effect on BCG respiration. The drug has no inhibitory effect on labelled amino acid incorporation in E. coli or Ehrlich ascites carcinoma cells in vitro but is effective with M. phlei. It does not affect selectively the distribution of radioactivities of the component amino acids of BCG proteins; only the total radioactivity incorporated into the proteins is diminished. The results lead to the conclusion that dihydrostreptomycin brings about an inhibition of protein synthesis in the BCG strain of M. tuberculosis at concentrations at which it exerts antibiotic effects.

Doxorubicin and epirubicin iron-induced generation of free radicals In vitro. A comparative study

1987 ◽  
Vol 7 (8) ◽  
pp. 653-658 ◽  
Author(s):  
Kjell Grankvist ◽  
Roger Henriksson
Keyword(s):  
Oxygen Consumption ◽  
Free Radicals ◽  
Myocardial Injury ◽  
Oxygen Free Radicals ◽  
Oxygen Electrode ◽  
Inhibitory Effect ◽  
Free System ◽  
A Cell ◽  
Strong Inhibitory Effect

To ascertain any differences in myocardial injury exerted by the anthracyclines doxorubicin and epirubicin, their ability to generate oxygen free radicals when mixed with Fe(II) was examined in vitro using an oxygen electrode. 5–250 μg/ml doxorubicin or epirubicin consumed oxygen when mixed with 50 or 100 μmol/1 Fe(II). Addition of 75 μmol/1 cytochrome C showed that of the consumed oxygen, approximately 80% entered the monovalent pathway of oxygen reduction. The strong inhibitory effect of 250 mg/1 catalase indicates that most of the superoxide radicals generated are further reduced to hydrogen peroxide by both anthracyclines. Addition of metal chelators DTPA (100/μmol/1), or DDTC (50 μmol/1) did not affect oxygen consumption, whereas EDTA (100/μmol/1) or desferrioxamine (100 μmol/1) with anthracyclines and Fe(II) rather stimulated oxygen consumption. It is concluded that there are no significant differences in the amount or proportion of generated oxygen free radicals between doxorubicin and epirubicin when mixed with Fe(II) in a cell-free system in vitro. Thus, the ability of the anthracyclines, in conjunction with iron alone, to generate radicals does not explain the differences of the drugs in causing myocardial injury.

EFFECT OF IODIDE AND THYROTROPHIN ON IN VITRO 14C-AMINO ACID INCORPORATION INTO RAT THYROID PROTEINS

1974 ◽  
Vol 76 (2) ◽  
pp. 273-285 ◽  
Author(s):  
Lubomir J. Valenta
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Relative Concentration ◽  
Total Radioactivity ◽  
Amino Acid Incorporation ◽  
Control Value ◽  
Acid Incorporation ◽  
Rat Thyroid

ABSTRACT Thyroid lobes from rats on normal (NID) or low iodine (LID) intake were incubated for 4 hours in vitro in the presence of 14C-amino acids. The 14C-amino acid incorporation into thyroid protein was significantly higher in thyroids from LID than from NID fed rats, 7.82 ± 1.01 % (mean ± sd) of total radioactivity of the incubation mixture per 100 mg tissue compared to 3.74 ± 0.60 % respectively. Thyrotrophin (TSH) in vitro did not influence the 14C-amino acid incorporation. Iodide in concentration 10−7 m and higher decreased 14C-radioactivity incorporation into protein by 19.40 ± 3.06 and 26.59 ± 4.06 % of the control value for NID and LID rats respectively. This effect of iodide did not depend on iodine organification and was not influenced by the changes of free amino acids pool. There were no significant differences in the relative concentration of 14C-labelled thyroglobulin and total 14C-thyroid protein. Differential fragility demonstrable by unfolding or dissociation was observed between different classes of thyroglobulin. The fragility was increasing from the old non-labelled molecules to newly iodinated and newly synthesized ones. It is concluded that iodide has a direct intrathyroidal blocking effect on thyroid protein synthesis which may contribute to its antigoitrogenic action. The lack of in vitro stimulation of protein synthesis by TSH remains unexplained.

Effects of fasting on the diuretic response and disposition of furosemide in rats

1980 ◽  
Vol 58 (2) ◽  
pp. 205-211 ◽  
Author(s):  
Saroj K. Chakrabarti ◽  
Jules Brodeur
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Inhibitory Effect ◽  
Kidney Cortex ◽  
Control Mechanisms ◽  
Tissue Slices ◽  
Control Value ◽  
Renal Tubular Cells ◽  
Renal Tubular

The influence of fasting on the relationship between the disposition and diuretic effect of furosemide was studied in rats. Fasting consisted of withholding solid food, but not water, for a period of 16 h before administering furosemide (10 mg/kg, sc) or a saline vehicle. Normally fed animals also received furosemide or the vehicle. Fasting did not modify the diuretic or the natriuretic effect (per 100 g body weight) of furosemide. The distribution of total furosemide in plasma or tissues was not affected by fasting. On the other hand, fasting which produced increasing amounts of endogenous free fatty acids in plasma and kidneys increased the concentration of free furosemide in fasting plasma but not in fasting kidney or liver of rats. The in vitro binding constant of furosemide to physiological concentrations of plasma proteins was decreased from the control value by a factor of 6.5 as a result of fasting. Neither unchanged furosemide nor its metabolite in the urine was affected by fasting. Incubation of kidney cortex tissue slices with furosemide both in the presence and absence of free fatty acid indicated an inhibition of furosemide uptake in a manner closely parallel to inhibition by probenecid. Thus, failure to observe a more pronounced diuretic and saluretic effects of furosemide in fasted rats, in spite of higher concentration of free plasma furosemide, might be due to the inhibitory effect of endogenous free fatty acids and (or) other endogenous substances on the uptake of furosemide by renal tubular cells although some homeostatic control mechanisms related to fasting could also be involved.

Antagonism of Haloxyfop Activity in Tall Fescue (Festuca arundinacea) by Dicamba and Bentazon

Weed Science ◽  
1991 ◽  
Vol 39 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Renan Aguero-Alvarado ◽  
Arnold P. Appleby ◽  
Donald J. Armstrong
Keyword(s):  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Enzyme Level ◽  
Inhibitory Effect ◽  
Herbicidal Activity ◽  
Vitro Activity ◽  
Acetyl Coa Carboxylase ◽  
In Vitro Activity ◽  
Enzyme Preparations

Studies were conducted to test if dicamba reduces haloxyfop herbicidal activity and to determine if this interaction by auxin-type herbicides or bentazon was caused by preventing the haloxyfop-induced inhibition of acetyl-CoA carboxylase (ACCase). Addition of dicamba at concentrations of 2.17 or 4.34 mM reduced haloxyfop activity on tall fescue shoots. Haloxyfop at 14 to 20 μM inhibited the activity of ACCase in cell-free extracts from tall fescue by nearly 50%. Dicamba did not prevent the inhibitory effect of haloxyfop on ACCase activity in these cell-free enzyme preparations. Dicamba alone at concentrations as high as 3.2 mM had no significant effect on the in vitro activity of the enzyme. Bentazon concentrations up to 10 mM did not prevent haloxyfop inhibition of ACCase activity. Bentazon alone or mixed with haloxyfop significantly inhibited ACCase activity at bentazon concentrations starting at 1 mM with near 40% inhibition at 10 mM. of the numerous possible explanations for the interference of dicamba or bentazon with haloxyfop action, interaction directly at the enzyme level appears to have been eliminated.

Comparative protection against oxyradicals by three flavonoids on cultured endothelial cells

1997 ◽  
Vol 75 (6) ◽  
pp. 717-720 ◽  
Author(s):  
Ling-Hua Zeng ◽  
Jun Wu ◽  
Beverly Fung ◽  
Jeffrey H Tong ◽  
Donald Mickle ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Oxygen Consumption ◽  
Xanthine Oxidase ◽  
Inhibitory Effect ◽  
Control Group ◽  
Aortic Endothelial Cells ◽  
Cytochrome C Reduction ◽  
Porcine Aortic Endothelial Cells ◽  
Aortic Endothelial

Oxygen-derived free radicals are known to injure the endothelium of aorta in diverse disorders. In this study we compared the cytoprotective effects of three flavonoids against oxyradical damage to porcine aortic endothelial cells in vitro. Cultured porcine aortic endothelial cells were exposed to oxyradicals generated by xanthine oxidase - hypoxanthine (XO-HP). The cytoprotective activities of morin, quercetin, and catechin on these systems were compared using established morphologic criteria. The results in the XO-HP system showed that morin at 0.125, 0.25, and 0.5 mM delayed cell necrosis to 27.4 ± 1.3, 46.8 ± 1.8, and longer than 70 min, respectively, compared with 12.0 ± 1.3 min in the control group. These degrees of protection were significantly stronger than those provided by quercetin and catechin at corresponding concentrations (p < 0.01). Morin and quercetin were moderate inhibitors of xanthine oxidase on the basis of the oxygen consumption rate, whereas catechin at the same concentrations had little inhibitory effect. The data from uric acid formation and cytochrome c reduction were consistent with the oxygen consumption measurement for the three flavonoids. Key words: flavonoids, oxyradicals, aortic endothelial cells.

Interaction of glutamine and arginine on cerebrovascular reactivity to hypercapnia

2000 ◽  
Vol 278 (5) ◽  
pp. H1577-H1584 ◽  
Author(s):  
Toshiki Okada ◽  
Yukinaga Watanabe ◽  
Saul W. Brusilow ◽  
Richard J. Traystman ◽  
Raymond C. Koehler
Keyword(s):  
Ammonium Acetate ◽  
Inhibitory Effect ◽  
Cerebrovascular Reactivity ◽  
Control Group ◽  
Vascular Effect ◽  
Arginine Infusion ◽  
Control Value ◽  
Cranial Window

Glutamine is purported to inhibit recycling of citrulline to arginine and to limit nitric oxide release in vitro. However, vasoactive effects of glutamine have not been clearly demonstrated in vivo. During hyperammonemia, impaired cerebrovascular reactivity to CO2 is related to glutamine accumulation. We tested the hypotheses that 1) glutamine infusion in the absence of hyperammonemia impairs cerebrovascular CO2 reactivity and 2) arginine infusion preserves CO2 reactivity during glutamine infusion and during hyperammonemia. Pentobarbital sodium-anesthetized rats were equipped with a closed cranial window for measuring pial arteriolar diameter. Intravenous infusion of 3 mmol ⋅ kg− 1 ⋅ h− 1of l-glutamine for 6 h produced threefold increases in plasma and cerebrospinal fluid concentrations. Dilation to hypercapnia was reduced by 45% compared with that of a time control group at 6 h but not at 3 h of glutamine infusion. Coinfusion of 2 mmol ⋅ kg− 1 ⋅ h− 1of l-arginine with glutamine maintained the hypercapnic vasodilation at the control value. Infusion of ammonium acetate at a rate known to produce threefold increases in cortical tissue glutamine concentration resulted in no significant hypercapnic vasodilation. Coinfusion of arginine with ammonium acetate maintained hypercapnic vasodilation at 60% of the control value. Arginine infusion did not augment hypercapnic vasodilation in a control group. We conclude that glutamine modulates cerebrovascular CO2 reactivity in vivo. Glutamine probably acts by limiting arginine availability because the vascular inhibitory effect required >3 h to develop and because arginine infusion counteracted the vascular effect of both endogenously and exogenously produced increases in glutamine.

Reversible Inhibition of the In Vitro Coagulation of Human Plasma by Lectins

1982 ◽  
Vol 48 (02) ◽  
pp. 120-124 ◽  
Author(s):  
J-M Freyssinet ◽  
D Thevenon ◽  
A Souque ◽  
M Suscillon
Keyword(s):  
Blood Clotting ◽  
Inhibitory Effect ◽  
Phospholipid Vesicles ◽  
Carbohydrate Binding ◽  
Clotting Factors ◽  
Con A ◽  
Acetylneuraminic Acid ◽  
Human Control ◽  
Blood Clotting Factors

SummaryWheat germ agglutinin (WGA) and concanavalin A (Con-A) (also red kidney bean agglutinin, PHA) have been found to be inhibitors of plasma clotting in vitro. At 40 µg/ml and 250 µg/ml (4.4 µM and 10 µM in carbohydrate binding sites, final concentrations) respectively, WGA and Con-A are able to double the activated partial thromboplastin time of normal human control plasma. Their inhibitory effect is due to their capacity to interact with the carbohydrate portion of blood clotting factors. It is totally abolished in the presence of specific saccharides for WGA or Con-A and is attenuated in the presence of 4% (v/v, final concentration) of human erythrocytes. The action of WGA is mediated by its ability to interact with N-acetylneuraminic acid. When purified phospholipid vesicles plus kaolin are used as an activator instead of cephalidin, this effect persists to the same extent. These two lectins also prolong the plasma clotting time using Russell's viper venom plus purified phospholipid vesicles as an activator. Quick's time was also prolonged by WGA and Con-A but to a lesser extent in this case. WGA can interact directly with some purified blood clotting factors (IX, X and II) in a classical lectin-glycoprotein precipitin reaction. When assessed at individual factors level in whole plasma using clotting assays, direct inhibitions by WGA are only apparent.

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