scholarly journals Induction of δ-aminolaevulinate synthetase under environmental-stress conditions

1973 ◽  
Vol 136 (4) ◽  
pp. 1091-1096 ◽  
Author(s):  
E. Amruthavalli ◽  
T. Ramasarma
Keyword(s):  
Environmental Stress ◽  
Initial Phase ◽  
Adenine Nucleotides ◽  
Ambient Pressure ◽  
Specific Effect ◽  
Inhibitory Effect ◽  
Stress Conditions ◽  
General Effect ◽  
Maximum Inhibition ◽  
Permanent Effect

1. Exposure of rats to environmental-stress conditions of hypobaria, hypoxia and cold did not alter the activity of hepatic δ-aminolaevulinate synthetase. 2. Induction of the enzyme by diethoxycarbonyldihydrocollidine was inhibited when the rats were exposed to hypobaria before or during the treatment with the drug but not after the initial phase when the process of induction was initiated. Neither increased concentration of the drug nor the time of induction had any effect on the inhibition under hypobaria. 3. A period of 12–24h of pre-exposure to hypobaria gave the maximum inhibition, and on longer exposure the inhibitory effect was decreased. 4. The inhibition was not a permanent effect and could be substantially reversed in 12h of withdrawal to ambient pressure. 5. Inhibition of induction was found under hypobaria and hypoxia, but not on exposure to cold. This suggests a specific effect of lack of O2 rather than a general effect of stress. 6. It appears possible that alteration of concentration of endogenous adenine nucleotides may control the process of diethoxycarbonyldihydrocollidine-mediated induction of δ-aminolaevulinate synthetase, since treatment with ATP, cyclic AMP or theophylline produced inhibition similar to that under hypobaria and hypoxia.

The Effects of Heparin and Annexin V on Fibrin Accretion after Injury in the Jugular Veins of Rabbits

1993 ◽  
Vol 69 (03) ◽  
pp. 227-230 ◽  
Author(s):  
J Van Ryn-McKenna ◽  
H Merk ◽  
T H Müller ◽  
M R Buchanan ◽  
W G Eisert
Keyword(s):  
Vessel Wall ◽  
Thrombin Generation ◽  
Antithrombin Iii ◽  
Specific Effect ◽  
Annexin V ◽  
Inhibitory Effect ◽  
Jugular Veins ◽  
Prothrombinase Complex ◽  
Wall Injury

SummaryWe compared the relative abilities of unfractionated heparin and annexin V to prevent fibrin accretion onto injured jugular veins in vivo. Heparin was used to accelerate the inhibition of thrombin by antithrombin III, and annexin V was used to inhibit the assembly of the prothrombinase complex on phospholipid surfaces, thereby blocking thrombin generation. Rabbit jugular veins were isolated in situ, a 2 cm segment was injured by perfusing it with air, and then blood flow was re-established. Five minutes later, each rabbit was injected with heparin (20 U/kg) or annexin V (0.3 mg/kg) and then with 125I-fibrinogen. The amount of 125I-fibrin accumulation onto each injured vessel wall segment was measured 4 h later. Each injured vessel was completely deendothelialized as a result of the air perfusion as demonstrated by electron microscopy. 125I-fibrin accretion onto the injured jugular veins was enhanced 2.4-fold as compared to the uninjured veins in sham-operated animals. Heparin treatment did not reduce fibrin accretion, whereas, annexin V treatment decreased fibrin accretion by 60%, p <0.05. This latter effect was achieved without sustained circulating anticoagulation. Additional experiments confirmed that the inhibitory effect of annexin V on fibrin accretion was associated with a surface specific effect, since more annexin V bound to the injured jugular vein segments as compared to the non-injured jugular veins. We conclude that, i) mild vessel wall injury (selective de-endothelialization) in veins results in a thrombogenic vessel wall; ii) the thrombogenecity of which is not inhibited by prophylactic doses of heparin; but iii) is inhibited by annexin V, which binds to injured vessel wall surface, and inhibits thrombin generation independently of antithrombin III.

scholarly journals Dimerization Is Required for Activation of eIF2 Kinase Gcn2 in Response to Diverse Environmental Stress Conditions

2004 ◽  
Vol 279 (22) ◽  
pp. 22820-22832 ◽  
Author(s):  
Jana Narasimhan ◽  
Kirk A. Staschke ◽  
Ronald C. Wek
Keyword(s):  
Environmental Stress ◽  
Stress Conditions

scholarly journals Metabolic aspects of the secretion of stored compounds from blood platelets. The effect of NaF at different pH on nucleotide metabolism and function of washed platelets

1981 ◽  
Vol 194 (1) ◽  
pp. 187-192 ◽  
Author(s):  
E H Mürer ◽  
K Davenport ◽  
E Siojo ◽  
H J Day
Keyword(s):  
Time Course ◽  
Adenine Nucleotides ◽  
Blood Platelets ◽  
Fluoride Concentration ◽  
Indirect Evidence ◽  
Inhibitory Effect ◽  
Nucleotide Metabolism ◽  
Wide Range ◽  
And Function ◽  
Special Circumstances

The purpose of this study was to investigate the response of human blood platelets to fluoride at different pH. The results were as follows. (1) Fluoride induced secretion faster and at a lower concentration when pH was lowered. (2) Platelets exposed to 2 mM-fluoride at 0 degrees C at pH 5.3 underwent secretion when first pH and then temperature was raised, although no secretion was seen at 2 mM-fluoride concentration in the absence of the preincubation at low pH. (3) The concentration of [14C]ATP in platelets decreased steeply in response to fluoride before induction of secretion. Addition of antimycin blocked or partly inhibited secretion. Fluoride thus exerts an inhibitory effect on platelet glycolysis before induction of secretion. (4) Fluoride accumulated in the platelet pellet by a time course that preceded secretion. The accumulation was faster and greater at pH 6 than at 7.4. These four points are taken as indirect evidence that fluoride has to penetrate to the interior of the platelet to induce secretion. The activation takes place over a wide range of acid pH in contrast with induction of platelet function via the outside of the plasma membrane. In addition evidence is presented that the salvage pathway may under special circumstances play an important role in the re-synthesis of platelet adenine nucleotides.

A Quantitative Study of the Behaviour of the Male Mormoniella Vitripennis (Walker) (Hymenoptera, Pteromalidae) Towards Two Constant Stimulus-Situations

Behaviour ◽  
1961 ◽  
Vol 18 (4) ◽  
pp. 288-311 ◽  
Author(s):  
Robert Barrass
Keyword(s):  
Nervous Activity ◽  
Specific Effect ◽  
Inhibitory Effect ◽  
Constant Stimulus ◽  
Receptive Female ◽  
Short Term ◽  
Excitatory Effect ◽  
Time Intervals ◽  
Almost All ◽  
Term Response

Abstract1. The method of dual quantification was used to study the effect of courtship of both receptive and non-receptive females on the subsequent behaviour of the male Mormoniella vitripennis. 2. The male's responsiveness to successive non-receptive females waned when the time between presentations was short. The extent of this waning was less with longer time intervals. 3. When many females were presented to a male one after another the male courted almost all of them if they were receptive females but only a few if they were non-receptive females. 4. A single courtship of either a receptive or a non-receptive female had a similar effect on the male's subsequent behaviour and recovery occurred in a similar way. 5. Courtship of 20 non-receptive females reduced the male's response to further females more than did courtship of 20 receptive females. 6. The significance of these observations is discussed with reference to the use of dummy animals and to the recent ethological concepts of reaction specific energy, motivational impulses, specific action potentiality and consummatory act. 7. An endogenous central nervous influence on the male's readiness to respond is postulated. Courtship has a short-term response-specific effect (receptive or non-receptive females) and an inhibitory stimulus-specific effect (non-receptive females). With receptive females the inhibitory effect is absent and/or mating has an excitatory effect. The stimuli provided by a receptive female must direct nervous activity rather than release a limited amount of stored energy.

Effects of adenosine 5′-monophosphate and adenosine 3′,5′-cyclic monophosphate on l cells

1975 ◽  
Vol 19 (2) ◽  
pp. 305-313
Author(s):  
J. Taylor-Papadimitriou ◽  
T. Karemfyllis ◽  
A. Eukarpidou ◽  
G. Karamanlidou
Keyword(s):  
Cyclic Amp ◽  
Adenine Nucleotides ◽  
Inhibitory Effect ◽  
S Phase ◽  
Breakdown Product ◽  
Intracellular Level ◽  
Effective Inhibitor ◽  
Growth Inhibitory Effect ◽  
L Cells ◽  
Growth Inhibitory

The adenine nucleotides, 5′-AMP and 3′,5′-cyclic AMP block L cells in the S-phase of the cell cycle. The intracellular level of cyclic AMP is reduced after incubation of cells with 5′-AMP, and rates of uridine transport are increased after incubation with either 5′-AMP or cyclic AMP. On the contrary, cyclic AMP levels are increased and uridine transport decreased in cells treated with an inhibitor of the cyclic AMP phosphodiesterase. This inhibitor partially reverses the growth-inhibitory effect of cyclic AMP, indicating that a breakdown product is the effective inhibitor of growth. The inhibition of cell growth induced by the adenine nucleotides is prevented by uridine, suggesting that the block in S is due to a lack of availability of pyrimidines.

Comparison of rat liver response to coumarin administered in vivo versus in vitro

1964 ◽  
Vol 206 (1) ◽  
pp. 229-238 ◽  
Author(s):  
Judith G. Pool ◽  
C. F. Borchgrevink
Keyword(s):  
Amino Acid ◽  
Oxidative Phosphorylation ◽  
Vitamin K ◽  
Inhibitory Effect ◽  
Factor Vii ◽  
General Effect ◽  
Liver Slices ◽  
Cell Energy

Warfarin added to incubated liver slices inhibits the synthesis of factor VII (proconvertin) in proportion to the log of its concentration; surprisingly, it has the same inhibitory effect on the transport and incorporation of amino acid into protein of the liver slices. This latter finding seems to support the frequently proposed concept that vitamin K has a role in oxidative phosphorylation and that coumarin compounds, by antagonizing vitamin K, uncouple oxidative phosphorylation and thus have a general effect on cell energy supply. However, when we studied the liver of rats depleted of vitamin K the same effect was not seen. Liver slices from such animals produced little factor VII but they incorporated amino acid at the normal rate. Furthermore, administration of warfarin in vivo had the same result as vitamin K depletion: a fall in circulating prothrombin complex but no decrease in either labeling of plasma proteins by intravenous C14-amino acid or incorporation of amino acid into subsequently excised liver slices. There is thus a striking discrepancy between the action of warfarin administered in vitro and that administered in vivo.

Cholecystokinin inhibits gastric acid secretion through type "A" cholecystokinin receptors and somatostatin in rats

1992 ◽  
Vol 263 (3) ◽  
pp. G287-G292 ◽  
Author(s):  
K. C. Lloyd ◽  
H. E. Raybould ◽  
J. H. Walsh
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Type A ◽  
Inhibitory Effect ◽  
Cck Receptors ◽  
Cholecystokinin Receptors ◽  
Maximum Inhibition ◽  
Vagal Reflex ◽  
Dependent Pathway

The purpose of this study was to determine whether selective antagonism of type "A" cholecystokinin (CCK) receptors blocks inhibition of gastric acid secretion produced by CCK and whether this inhibition is mediated through either a somatostatin-dependent pathway or a vago-vagal reflex. Intravenous infusion of CCK (0.04-10 nmol.kg-1.h-1) dose dependently inhibited pentagastrin-stimulated gastric acid secretion in urethan-anesthetized rats, with a 50% inhibitory dose of 0.9 nmol.kg-1.h-1 and a maximum inhibition of approximately 50%. Blockade of type A CCK receptors using the selective type A receptor antagonist MK-329 completely reversed the inhibitory effect produced by a maximal dose (4 nmol.kg-1.h-1) of CCK. Immunoneutralization of endogenous somatostatin by administration of somatostatin monoclonal antibody abolished the inhibition produced by CCK. Concentrations of somatostatin in portal venous plasma were significantly increased after CCK administration; the increase in somatostatin was blocked by pretreatment with MK-329. In contrast, CCK-induced inhibition of gastric acid secretion was unaltered after perivagal capsaicin treatment. These results indicate that CCK inhibits gastric acid secretion in rats by activation of type A CCK receptors and through release of endogenous somatostatin.

scholarly journals Effect of Terminalia catappa Leaves Extract on Corrosion of Mild Steel using Response Surface Methodology

2020 ◽  
Vol 27 (2) ◽  
pp. 47-56
Author(s):  
A.O. Okewale ◽  
O.A. Adesina ◽  
B.H. Akpeji
Keyword(s):  
Response Surface Methodology ◽  
Mild Steel ◽  
Response Surface ◽  
Inhibition Efficiency ◽  
Desirability Function ◽  
Inhibitory Effect ◽  
Quadratic Model ◽  
Box Behnken Design ◽  
Terminalia Catappa ◽  
Maximum Inhibition

Effect of Terminalia catappa leaves (TCL) extract in inhibiting corrosion of mild steel was investigated. In order to obtain the maximum inhibition efficiency, optimization of the process variables affecting corrosion of mild steel was carried out using the Box – Behnken Design plan and desirability function of Response Surface Methodology (RSM). The three parameters - varied include; TCL concentration (inhibitor), immersion time, and temperature and there effects in corrosion inhibition were established. The optimum conditions predicted from the quadratic model were inhibitor’s concentratrion (0.39 g/l), exposure time (8.68 hours), and temperature (36.06 oC) with the inhibition efficiency of 91.95 %. The data fitted well to the quadratic model which was validated. Adsorption of the extract’s component on the mild steel was responsible for the inhibitory effect of the TCL extract.The results showed that 97.92% of the total variation in the inhibition efficiency of TCL can be connected to the variables studied. Keywords: Mild steel, acid, Terminalia catappa, Corrosion, Response surface methodology (RSM).

Sign in / Sign up

Export Citation Format

Share Document