Theoretical Time Course Research Articles

Neurolinguistic Priming and Gender Stereotype Effects in the Ratings of Justice vs. Authority Moral Violations: Republicans and Democrats

ABSTRACT An experimental method for assessing gender biases was used to compare Republicans’ and Democrats’ ratings of moral violations in the domains of justice vs. respect for authority. Four experimental conditions of a text-based survey instrument manipulated the gender of the protagonist and the location of the first instance of gender information in single-sentence moral violation vignettes. Results were consistent with the theoretical time course of neurolinguistic gender priming and the hypothesized influence of implicit stereotypes on moral judgments. Republicans demonstrated a gender bias in ratings of authority violations by rating violations committed by girls and women as worse when compared to a pronoun only condition. Democrats demonstrated the opposite bias by rating authority violations committed by boys and men as worse when compared to violations committed by girls and women. No significant bias was found for any of the justice violation conditions for either Republicans or Democrats.

Kinetics of α-Globin Binding to α-Hemoglobin Stabilizing Protein (AHSP) Indicate Preferential Stabilization of Hemichrome Folding Intermediate

Human α-hemoglobin stabilizing protein (AHSP) is a conserved mammalian erythroid protein that facilitates the production of Hemoglobin A by stabilizing free α-globin. AHSP rapidly binds to ferrous α with association (k'(AHSP)) and dissociation (k(AHSP)) rate constants of ≈10 μm(-1) s(-1) and 0.2 s(-1), respectively, at pH 7.4 at 22 °C. A small slow phase was observed when AHSP binds to excess ferrous αCO. This slow phase appears to be due to cis to trans prolyl isomerization of the Asp(29)-Pro(30) peptide bond in wild-type AHSP because it was absent when αCO was mixed with P30A and P30W AHSP, which are fixed in the trans conformation. This slow phase was also absent when met(Fe(3+))-α reacted with wild-type AHSP, suggesting that met-α is capable of rapidly binding to either Pro(30) conformer. Both wild-type and Pro(30)-substituted AHSPs drive the formation of a met-α hemichrome conformation following binding to either met- or oxy(Fe(2+))-α. The dissociation rate of the met-α·AHSP complex (k(AHSP) ≈ 0.002 s(-1)) is ∼100-fold slower than that for ferrous α·AHSP complexes, resulting in a much higher affinity of AHSP for met-α. Thus, in vivo, AHSP acts as a molecular chaperone by rapidly binding and stabilizing met-α hemichrome folding intermediates. The low rate of met-α dissociation also allows AHSP to have a quality control function by kinetically trapping ferric α and preventing its incorporation into less stable mixed valence Hemoglobin A tetramers. Reduction of AHSP-bound met-α allows more rapid release to β subunits to form stable fully, reduced hemoglobin dimers and tetramers.

Kinetic modelling and simulation of laccase catalyzed degradation of reactive textile dyes

A kinetic model based on Michaelis–Menten equation was developed to simulate the dye decolourisation of Reactive Black 5 (RB5), Reactive Blue 114 (RB114), Reactive Yellow 15 (RY15), Reactive Red 239 (RR239) and Reactive Red 180 (RR180) dyes by commercial laccase. The unusual kinetic behavior of some of these reactions suggests that the kinetic model must consider the activation of the laccase-mediator system. Several reactions at different concentrations of each dye were performed in batch reactors and time courses were obtained. A LSODE code to solve the differential equation obtained from the batch reactor was combined with an optimization Fortran program to obtain the theoretical time courses. The time courses obtained from the developed program were compared with the experimentally obtained ones to estimate the kinetic constants that minimized the difference between them. The close correlation between the predicted and the experimental results seems to support the reliability of the established models.

Forearm postural control during unloading: anticipatory changes in elbow stiffness.

In this study, the equilibrium-point hypothesis of muscle-torque generation is used to evaluate the changes in central control parameters in the process of postural-maintenance learning. Muscle torque is described by a linear spring equation with modifiable stiffness, viscosity, and equilibrium angle. The stiffness is considered to be the estimation of the central command for antagonist-muscle coactivation and the equilibrium angle to be the estimation of the reciprocal command for a shift of invariant characteristics of the joint. In the experiments, a load applied to the forearm was released. The subjects were instructed to maintain their forearm in the initial horizontal position. Five sessions of approximately twenty trials each were carried out by eight subjects. During two "control" series, the load release was triggered by the experimenter. During three "learning" series, the load supported by one forearm was released by the subject's other hand. The elbow-joint angle, the angular acceleration, and the external load on the postural forearm were recorded. These recordings as well as anthropometric forearm characteristics were used to calculate the elbow-joint torque (which we called "experimental"). Linear regression analysis was performed to evaluate the equilibrium angle, joint stiffness, and viscosity at each trial. The "theoretical" torque was calculated using a linear spring equation with the found parameters. The good agreement observed between experimental and theoretical joint-torque time courses, apart from the very early period following unloading, argues in favor of the idea that the movement was mainly performed under a constant central command presetting the joint stiffness and the equilibrium angle. An overall increase in the stiffness occurred simultaneously with a decrease in the equilibrium angle during the "learning" series in all the subjects. This suggests that subjects learn to compensate for the disturbing effects of unloading by increasing the joint stiffness. The mechanism possibly responsible for the presetting of the central control parameters is discussed.

Nucleotide binding to chloroplast F1‐ATPase (CF1) cannot be explained by a two‐site model

AbstractThe kinetics of nucleotide binding to the chloroplast coupling factor, CF1, have been analysed by stopped‐flow measurements using the fluorescent trinitrophenyl analog TNP‐ADP. Experimental determined time courses were compared with several different theoretical time courses. The following observations were obtained: (a) in stopped‐flow experiments the half time of the reaction was at highest with a ligand‐to‐enzyme ratio of 2:1. The half time of the binding reaction decreased, if the ratio was lower than 2:1. (b) This characteristic cannot be explained by a bimolecular reaction mechanism of several independent (classes of) binding sites, (c) Theoretical time courses according to a “two‐site” model with the inclusion of a conformational change of each site after binding of ligand showed the observed characteristic (see (a)), (d) However, this “two‐site” model including a conformational change of each site after binding of ligand failed to simulate the measured time courses of nucleotide binding.

Time Course of Bell Palsy

This study was designed to quantitatively characterize the time course of facial palsy and the relationship between electroneurography and the facial nerve grading percentage as a function of onset time. Bilateral electroneurographic recordings during different stages in the course of the disease were repeated and compared with categorized videotaped facial movements using the House-Brackmann facial nerve grading system in 32 patients with Bell palsy. Preliminary results of this study demonstrate a time gap between the percentage of electroneurographic response and the category of the facial nerve grading system during the same period of disease progress. A theoretical model of the time course and specific patterns regarding the recovery of facial function is established. The theoretical time course of facial palsy is divided into 3 stages; preclinical, clinical, and postclinical. Based on the time course of electroneurographic and facial grading functions, the period between 10 and 14 days after onset was found to be most valuable for prediction of recovery. According to this theoretical model, a given time course pattern based on the results of serial electroneurographic recordings provides reliable prognostic information on recovery from Bell palsy.

Relationship between electromotive force and batch culture process of an iron-oxidizing bacterium

The electromotive force (EMF) occurring during batch culture of an iron-oxidizing bacterium was measured, and the relationship between the time evolution of the EMF, substrate concentration and bacterial density was investigated both experimentally and theoretically. The aim was to examine whether the monitoring and control of the culture process by measurement of the EMP and the utilization of electrical energy were possible. The measured and theoretical maximum EMF values were 288 mV and 322 mV respectively. The EMF calculated using the Nernst equation, based on the Monod equation of bacterial growth and the theoretical time course of the consumption of limiting substrate (FeSO 4), was in good agreement with the measured values.

Kinetic analysis of ligand-receptor association data that display an overshoot phenomenon.

A binding overshoot was frequently observed in the time course of association of diazepam with rat brain membrane receptors shortly after the start of the interaction. Such time profiles most likely reflect the "receptor switch" mechanism, assuming an equilibrium between two forms of a receptor (R and R*) that possess different affinities to the ligand (L) in question. Similar effects could be caused by the presence of a slowly dissociating competitor. The kinetics of these mechanisms were verified by simulation of theoretical time courses. A computer program for simulation of the time course, and estimation of rate constants of the individual reaction steps, was developed and is described in this communication. It employs the Euler-Cauchy integration for simulation of theoretical time courses. Optimised estimates of the rate constants were computed by simultaneous random variation of parameters within a pre-set interval. Stable solutions can be obtained for this system, thus enabling evaluation of equilibrium constants defined by the model. The source code is available in Turbo-Pascal. It can be used, after re-writing the rate equations, for fitting of similar kinetic models to suitable experimental data.

Combined film and membrane diffusion-controlled transport of ions through charged membrane

A methematical model based on the Nernst-Planck equation has been suggested for predicting the ionic transport rate in a bi-ionic system under the condition controlled by combined film and membrane diffusion. The Na + − H + system with a cation-exchange membrane was studied experimentally as a test of the model, and the mass transfer coefficients in the liquid film that yielded an optimum fit of the experimental data to the theoretical curves were determined. The obtained mass transfer coefficients were found to be function of the stirring speed and solution composition. The theoretical time course of the concentration calculated using the obtained diffusion coefficients and mass transfer coefficients agreed well with the experimental results.

Diffusion and Electric Mobility of KCI within Isolated Cuticles of Citrus aurantium

Fick's second law has been used to predict the time course of electrical conductance change in isolated cuticles following the rapid change in bathing solution (KCI) from concentration C to 0.1 C. The theoretical time course is dependent on the coefficient of diffusion of KCI in the cuticle and the cuticle thickness. Experimental results, obtained from cuticles isolated from sour orange (Citrus aurantium), fit with a diffusion model of an isolated cuticle in which about 90% of the conductance change following a solution change is due to salts diffusing from polar pores in the wax, and 10% of the change is due to salt diffusion from the wax. Short and long time constants for the washout of KCI were found to be 0.11 and 3.8 hours, respectively. These time constants correspond to KCI diffusion coefficients of 1 x 10(-15) and 3 x 10(-17) square meters per second, respectively. The larger coefficient is close to the diffusion coefficient for water in polar pores of Citrus reported elsewhere (M Becker, G Kerstiens, J Schönherr [1986] Trees 1: 54-60). This supports our interpretation of the washout kinetics of KCI following a change in concentration of bathing solution.

Rate and mechanism of the assembly of tropomyosin with actin filaments

The rate of assembly of tropomyosin with actin filaments was measured by stopped-flow experiments. Binding of tropomyosin to actin filaments was followed by the change of the fluorescence intensity of a (dimethylamino)naphthalene label covalently linked to tropomyosin and by synchrotron radiation X-ray solution scattering. Under the experimental conditions (2 mM MgCl2, 100 mM KCl, pH 7.5, 25 degrees C) and at the protein concentrations used (2.5-24 microM actin, 0.2-3.4 microM tropomyosin) the half-life time of assembly of tropomyosin with actin filaments was found to be less than 1 s. The results were analyzed quantitatively by a model in which tropomyosin initially binds to isolated sites. Further tropomyosin molecules bind contiguously to bound tropomyosin along the actin filaments. Good agreement between the experimental and theoretical time course of assembly was obtained by assuming a fast preequilibrium between free and isolatedly bound tropomyosin.

The determination of diffusion coefficients of counter-ions in the ion-exchange membrane by means of batchwise Donnan dialytic experiments

A new method, based on the Nernst-Planck equation, has been proposed for determining diffusion coefficients of counter-ions in an ion-exchange membrane for bi-ionic Donnan dialysis. This method involves dialytic experiments in which both the solution concentration and the membrane potential are measured under the condition controlled by diffusion resistance in the membrane. It also involves mathematical optimization treatment of the experimental data. The K +−H + system with a cation-exchange membrane was studied, and the optimum diffusion coefficients of these counter-ions were obtained. The diffusion coefficients were found to vary with the ionic composition of the solution. The theoretical time courses of the concentration and membrane potential calculated by using the optimum diffusion coefficients agreed with the experimental results.

Glucose Production from Maltohexaose as a Substrate by the Bacterial Alpha‐amylase‐catalyzed Reaction. Its Time Courses Obtained by a Theoretical and an Experimental Approaches

AbstractBased on the subsite structure of an α‐amylase from Bacillus subtilis, production of glucose from a substrate maltohexaose in the amylase‐catalyzed reaction was theoretically predicted as a function of time. The theoretical time course was found consistent with the experimental results, which were obtained by the determination of a product glucose with a commercial assay‐kit. Hence, glucose, product from a substrate maltohexaose, will be a useful probe for the amylase‐catalyzed reaction.

Chymotrypsin‐catalyzed peptide synthesis

The kinetics of peptide-bond formation catalyzed by delta-chymotrypsin has been studied for a number of peptide products of different length using fixed concentrations of the acyl component (Ac-Phe-OMe, Ac-Ala-Ala-Phe-OMe, or Ac-Ala-Ala-Tyr-OMe) and varying concentration of the amino component (H-Ala-NH2 or H-Ala-Ala-NH2). The time course of the reactions was followed by monitoring ester consumption and peptide product formation by analytical HPLC. On the basis of a plausible four-centre mechanistic model, the theoretical time course of these reactions was calculated using rate and equilibrium constants determined by separate kinetic experiments. The excellent agreement observed between the theoretical and the experimental time courses supports the proposed mechanism and provides evidence for the validity of the present kinetic approach. By focusing attention on the rate constants which are critical for efficient synthesis, this mechanistic information constitutes a valuable basis for the use of the enzymatic peptide synthesis in preparative applications.

Inorganic Carbon Uptake during Photosynthesis

Equations have been developed which quantitatively predict the theoretical time-course of photosynthetic (14)C incorporation when CO(2) or HCO(3) (-) serves as the sole source of exogenous inorganic carbon taken up for fixation by cells during steady state photosynthesis. Comparison between the shape of theoretical (CO(2) or HCO(3) (-)) and experimentally derived time-courses of (14)C incorporation permits the identification of the major species of inorganic carbon which crosses the plasmalemma of photosynthetic cells and facilitates the detection of any combined contribution of CO(2) and HCO(3) (-) transport to the supply of intracellular inorganic carbon. The ability to discriminate between CO(2) or HCO(3) (-) uptake relies upon monitoring changes in the intracellular specific activity (by (14)C fixation) which occur when the inorganic carbon, present in the suspending medium, is in a state of isotopic disequilibrium (JT Lehman 1978 J Phycol 14: 33-42). The presence of intracellular carbonic anhydrase or some other catalyst of the CO(2)-HCO(3) (-) interconversion reaction is required for quantitatively accurate predictions. Analysis of equations describing the rate of (14)C incorporation provides two methods by which any contribution of HCO(3) (-) ions to net photosynthetic carbon uptake can be estimated.

A kinetic analysis of the acidic degradation of penicillin G and confirmation of penicillamine as a degradation product

Two recently proposed degradation pathways for the acidic degradation of pencillin G were examined by calculating the theoretical time course based on each pathway and examining the fit of the theoretical predictions to the experimental data. A substantial difference in the goodness of fit was observed. The degradation pathway which provided the best fit included penicillamine as a terminal degradation product. This pathway is therefore favoured since penicillamine was also identified as a degradation product of penicillin G by both reversed-phase high pressure liquid chromatography and differential pulse polarography.

Light-driven Uptake of Oxygen, Carbon Dioxide, and Bicarbonate by the Green Alga Scenedesmus

Mass spectrometric techniques were used to study several aspects of the competition between O(2) and species of inorganic carbon for photosynthetically generated reducing power in the green alga, Scenedesmus.In contrast to wild type, no appreciable light-driven O(2) uptake was observed in a mutant lacking photosystem I. It is concluded that the carbon cycle-independent reduction of O(2) occurs at the expense of photosystem I-generated reducing equivalents.The commonly observed differences between CO(2)-grown and air-grown Scenedesmus with respect to CO(2) uptake and glycolate formation cannot be ascribed to differences in their capacity for light-driven O(2) uptake. There were no intrinsic differences found in O(2) uptake capacity between the two physiological types under conditions in which CO(2) was saturating or CO(2) uptake was inhibited. It was only under CO(2)-limited conditions that pronounced differences between the two physiological types were observed. This fact suggests that differences in O(2) metabolism and sensitivity between the two types really reflect differences in their capacity to assimilate inorganic carbon; in this respect they are analogous to C(3) and C(4) plants.The hypothesis that air-grown Scenedesmus can assimilate HCO(3) (-) by directly monitoring the time course of dissolved CO(2), O(2) uptake, and O(2) evolution in illuminated algal suspensions at alkaline pH was tested. Inasmuch as the measuring technique employed was fast compared to the nonenzymic equilibration of the inorganic carbon species, it was possible to determine the degree to which the CO(2) concentration deviated from equilibrium (with the other inorganic carbon species) during the course of illumination. The observed kinetics in air-grown and CO(2)-grown algae in the presence and absence of carbonic anhydrase, and a comparison of these kinetics with theoretical (computer-generated) time courses, support the idea that air-adapted algae are able to assimilate HCO(3) (-) actively at a high rate. The data suggest that these algae preferentially assimilate CO(2) and supply the balance of their needs by taking up HCO(3) (-). Since (unlike C(4) plants) these algae have no special CO(2) pump, and thus have a relatively low affinity for CO(2), HCO(3) (-) assimilation is the major carbon uptake process at alkaline pH even when the total CO(2) is present in millimolar concentrations.

A new method to distinguish separate components in cytochemically stained macromolecules by analysis of the kinetics of the staining and destaining processes.

A new method making it possible to analyze properties of the end products of cytochemical staining reactions in macromolecular substances not expressed in the absorption spectra is described. Mathematical analysis of the course of changes in the absorbance during staining or destaining of the macromolecular substance provides information about the reaction velocities of these processes for the individual components present as well as about the concentrations of the components thus detected. This analysis is performed by a procedure of computerized curve-fitting between experimentally determined and theoretically expected absorbance curves. The theoretical time course of absorbance is derived for a number of pseudo first-order reaction schemes, and a description is given of the way in which the most appropriate reaction scheme can be recognized and the parameters are estimated, both on the basis of the experimental absorbance curve. Possible complications due to dye impurities, depolymerization and diffusion processes are discussed.

Assessment of the 220 Rn Franction Retained in Mice after a Single Injection of 224 Ra

The time course of ${}^{224}{\rm Ra}$, ${}^{212}{\rm Pb}$, and212 Bi retention and220 Rn exhalation was measured in two groups of mice after a single intraperitoneal administration of ${}^{224}{\rm Ra}$. The retained220 Rn fraction was calculated using two approaches: (1) From measured activity of220 Rn in exhaled air and from ${}^{224}{\rm Ra}$ retention data. (2) From the measured ${}^{212}{\rm Pb}$ or212 Bi retention and using a theoretical time course of the retention of these radionuclides; it was assumed in this case that the retained220 Rn fraction is constant within the duration of the experiment, i.e., during the first 3 wk after ${}^{224}{\rm Ra}$ administration. The retained fractions found using the two approaches are in good agreement equaling 60-70% in both groups of mice; thus the fraction exhaled amounts to 30-40%.

A simple resolution of the kinetic anomaly in the exchange of different sugars across the membrane of the human red blood cell.

Abstract 1. 1. Using human red blood cells, we measured the time courses of efflux of labelled mannose, glucose or galactose (all at 130 mM) into equimolar concentrations of different sugars. 2. 2. We confirmed that the rates of exchange of mannose with mannose and galactose with galactose are somewhat slower than that of glucose with glucose at the particular concentration studied. The rates of exchange for glucose into mannose and for glucose into galactose are (we confirm) faster, but those for mannose into glucose and galactose into glucose are (we show) slower than for the exchange of either glucose into glucose, mannose into mannose or galactose into galactose. 3. 3. We determined directly, using the single sugars alone, the kinetic parameters K m and V for exchange transport. The different sugars demonstrated different values for V as well as for K m . 4. 4. Based on the values obtained, the theoretical time course of the exchange between pairs of sugars at 130 mM was computed according to the conventional carrier model and the recently proposed tetramer model. The experimental results fitted well with the predictions of the tetramer model and to a lesser extent with the carrier model. Thus the previously reported anomaly in the exchange experiments was merely an apparent one due, first, to the fact that different sugars possess different maximum velocities and, second, to the accumulation of the unlabelled sugars within the cell.