scholarly journals Identification and characterization of a phospholipase C activity in resident mouse peritoneal macrophages. Inhibition of the enzyme by phenothiazines

1981 ◽  
Vol 197 (2) ◽  
pp. 523-526 ◽  
Author(s):  
Paul D. Wightman ◽  
Mary Ellen Dahlgren ◽  
James C. Hall ◽  
Philip Davies ◽  
Robert J. Bonney
Keyword(s):  
Phospholipase C ◽  
High Activity ◽  
Peritoneal Macrophages ◽  
Ph Optimum ◽  
Reaction Velocity ◽  
Neutral Ph ◽  
Maximum Reaction ◽  
Mouse Peritoneal Macrophages ◽  
Identification And Characterization

Resident mouse peritoneal macrophages contain a phospholipase C of high activity that is specific for phosphatidylinositol. The activity has a neutral pH optimum, is Ca2+-dependent and has a maximum reaction velocity of 525nmol/h per mg of protein. Certain phenothiazines are potent inhibitors of this activity.

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: VII. THE DECOMPOSITION OF ETHYLIDENE DIBUTYRATE AND HEPTYLIDENE DIACETATE

1937 ◽  
Vol 15b (6) ◽  
pp. 247-253 ◽  
Author(s):  
C. C. Coffin ◽  
J. R. Dacey ◽  
N. A. D. Parlee
Keyword(s):  
Activation Energy ◽  
Homologous Series ◽  
Reaction Velocity ◽  
Vapor State ◽  
Specific Reaction ◽  
First Order ◽  
Gas Reactions

Ethylidene dibutyrate and heptylidene diacetate decompose in the vapor state at temperatures between 200° and 300 °C. to form an aldehyde and an anhydride. The reactions are homogeneous, unimolecular, and complete. The activation energy is the same as that previously found for other members of this homologous series. Ethylidene dibutyrate decomposes at the same rate as ethylidene diacetate, and thus provides further evidence that the specific reaction velocity is independent of the size of the anhydride radicals. Heptylidene diacetate decomposes at the same rate as butylidene diacetate. This indicates that after the aldehyde radical has attained a certain size (three or four carbon atoms) the addition of –CH2− groups leaves the specific reaction velocity unchanged. The velocity constants are given by the equations[Formula: see text]

scholarly journals Assessment of Acupuncture and Moxibustion Effects on the Electrophysiological Properties of the Ulnar Nerve: A Nerve Conduction Study

2018 ◽  
Vol 4 (3-4) ◽  
pp. 198-207 ◽  
Author(s):  
Sónia Chan ◽  
Sérgio Ferreira ◽  
Bruno Ramos ◽  
Maria João Santos ◽  
Luís Carlos Matos ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Ulnar Nerve ◽  
Rating Scale ◽  
Intervention Group ◽  
Maximum Amplitude ◽  
Numeric Rating Scale ◽  
Control Group ◽  
Reaction Velocity ◽  
Electrophysiological Properties ◽  
Acupuncture And Moxibustion

Background/Aims: Acupuncture and moxibustion, when used together, have act mechanically and thermally on treated reflexological areas. The main goal of this work was to evaluate the effects of acupuncture and moxibustion on the electrophysiological properties of the ulnar nerve. Methods: Electrical stimulation was applied to the ulnar nerve above the epi­condyle of 28 volunteers. A 20-V potential was applied, and after each 10 impulses it was increased by 10 V, up to a maximum of 80 V. At 20 and 80 V, the participants were asked to rate the discomfort from 0 to 10 on a Numeric Rating Scale for pain. After the first stimulation and data collection, the control group rested for 6 min, while the intervention group was submitted to acupuncture and moxibustion on Lingdao (HT 4). Following this period of time, a second electrical stimulation was performed on both groups. Results: The discomfort was greater in the intervention group during the second stimulation. The stimulus required to achieve the maximum amplitude decreased, but the changes were only statistically significant in the intervention group (p = 0.006). An increase in latency and a decrease in reaction velocity were noticed between the first and the second stimulation for both groups; however, only the control group presented statistically significant differences (p = 0.018 and p = 0.022, respectively). Conclusions: Acupuncture and moxibustion on HT 4 increased the electrical sensitivity, decreased the stimulus intensity to achieve the maximum amplitude, and avoided a significant increase in latency and decrease in reaction velocity in two consecutive electrical stimulations.

Potentiodynamic examination of electrode kinetics for electroactive adsorbed species: applications to the reduction of noble metal surface oxides

1969 ◽  
Vol 310 (1503) ◽  
pp. 541-563 ◽  
Keyword(s):  
Noble Metals ◽  
Reaction Rate ◽  
Substrate Surface ◽  
Intrinsic Property ◽  
Surface Heterogeneity ◽  
Surface Oxide ◽  
Rate Equations ◽  
Quasi Equilibrium ◽  
Linear Potential ◽  
Reaction Velocity

The relation between reaction rate and potential (or time) for electrochemical surface processes occurring under potentiodynamic control (linear potential-time programme) has been investigated with particular reference to the behaviour of thin surface oxide films on noble metals. The kinetics of processes involving adsorbed electroactive species are treated for several model cases; the rate equations are developed for mechanisms involving various reaction orders or for processes involving adsorbed reactant interactions and surface heterogeneity effects. By examination of the dependence of the reaction rate (current) with time and the effect of potential scan rate, v , on the maximum reaction velocity and the potential at which it occurs, the models may be distinguished. In this manner, the inter­dependence of v and the reaction velocity constants k a and k c for the anodic oxidation and the cathodic reduction processes respectively, can be quantitatively established. The relation between quasi-equilibrium situations where the reverse reaction is significant and irreversible situations where it is not can be demonstrated. Heterogeneity terms introduced into the kinetic relations express deviations from Langmuir adsorption behaviour and may be an intrinsic property of the substrate surface or a property of the adsorbed reactant (induced heterogeneity). Applications of the treatment are made to reduction of surface oxide species at the noble metals and the significance of hysteresis and time effects in the processes of electrochemical formation and reduction of surface oxide at platinum, rhodium, iridium and palladium is investigated.

scholarly journals Characteristics of the rat liver microsomal enzyme system converting cholecalciferol into 25-hydroxycholecalciferol. Evidence for the participation of cytochrome p-450

1979 ◽  
Vol 184 (3) ◽  
pp. 491-499 ◽  
Author(s):  
T C Madhok ◽  
H F DeLuca
Keyword(s):  
Vitamin D ◽  
White Light ◽  
Microsomal Fraction ◽  
Enzyme System ◽  
Initial Reaction ◽  
Microsomal Enzyme ◽  
Reaction Velocity ◽  
Calcium And Phosphorus ◽  
Cytochrome P 450 ◽  
25 Hydroxycholecalciferol

Properties of the rat hepatic cholecalciferol 25-hydroxylase have been studied. An assay system has been developed in which 25-hydroxycholecalciferol production is linear for at least 2h in both homogenates and microsomal fraction. Furthermore, the initial reaction velocity is linearly related to the amount of liver tissue or microsomal fraction. This enzyme system also metabolizes an analogue of cholecalciferol, namely dihydrotachysterol 3, into 25-hydroxydihydrotachysterol 3. The 25-hydroxylase is in the microsomal fraction and not in mitochondria. It has a Km of 44 nM for cholecalciferol and 360 nM for dihydrotachysterol 3. Its activity is not altered by dietary concentrations of calcium and phosphorus. Vitamin D-deficient rats have higher activities of the hepatic 25-hydroxylase than those receiving 25 ng of cholecalciferol daily. The 25-hydroxylase is inhibited by metyrapone. An atmosphere of CO/O2 (9:1, v/v) inhibits the reaction by 87%. This inhibition is partially reversed by white light. Additionally, cholecalciferol and 25-hydroxycholecalciferol competitively inhibit aminopyrine demethylase. These results support the idea that the cholecalciferol 25-hydroxylase is a cytochrome P-450-dependent mono-oxygenase.

scholarly journals Diffusion and chemical reaction velocity as joint factors in determining the rate of uptake of oxygen and carbon monoxide by the red blood corpuscle

1932 ◽  
Vol 111 (769) ◽  
pp. 1-36 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Cross Sections ◽  
The Other ◽  
Blood Corpuscle ◽  
Reaction Velocity ◽  
Two Fluids ◽  
Mixing Chamber ◽  
Haemoglobin Solution ◽  
Moving Fluid

In a paper on this subject published four years age, Hartridge and Roughton (1927) described some preliminary experiments upon the rate of uptake of oxygen and carbon monoxide by the red blood corpuscle, the observations being made by means of their reaction velocity technique (Hartridge and Roughton, 1922–1927). The general principles of the method were as follows. Through one lead of the apparatus a suspension of reduced corpuscles in saline was forces into the mixing chamber, whilst through the other lead was forced a solution of oxygen (or carbon monoxide) in saline. The two fluids mixed in the mixing chamber within 0·001 second or less and then travelled down the observation tube. Determination of the percentage of oxyhæmoglobin (or carboxyhæmoglobin) in the moving fluid at various cross sections of the observation tube was made by means of the reversion spectroscope, these measurements, together with a knowledge of the rate of flow of the fluid down the observation tube, giving the necessary data for plotting the rate of uptake of O 2 or CO by the corpuscles against time. The most interesting feature of the results was the much slower uptake of O 2 by hæmoglobin in the intact corpuscle as compared with the of O 2 by hæmoglobin in laked solution as previously recorded by Hartridge and Roughton (1925). In the corpuscle experiments the time scale had to be expressed in hundredths of a second instead of in thousandths of a second as in the hæmoglobin solution experiments ( vide fig. 2 of Hartridge and Roghton, 1927). Confirmatory results by somewhat different technique have been obtained lately by Dirken and Mook (1931). These will be referred to again later.

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