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Results for “Model explainability”

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At least 19 recordsLinked to original sources
PubMed1992

A simplified two-pore filtration model explains the effects of hypoproteinemia on lung and soft tissue lymph flux in awake sheep.

We used a simplified two-pore filtration model to examine the effects of hypoproteinemia on lung and soft tissue lymph flux in awake sheep (n = 7). To induce hypoproteinemia, we subjected each animal to 3 days of batch plasmapheresis (6 units per day). Data were collected in near steady-state conditions, 15-18 hr following completion of the last plasmapheresis episode. At this time, plasma protein concentration had fallen by 34%, while lung and soft tissue lymph protein concentrations had fallen by 55 and 62%, respectively. Lung and soft tissue lymph flows increased 52 and 87%, respectively. The plasma-to-lymph osmotic pressure gradients for lung and soft tissue lymph were unchanged by protein depletion (soft tissue, 7.7 mm Hg; lung, 4.8 mm Hg). We applied these results to a heteropore model of the microvascular barrier that consisted of two types of pores: those which plasma proteins could not cross (sigma = 1) and those which proteins could cross without restriction (sigma = 0). We varied the proportion of small pores to large pores until the measured data fit a model in which the calculated microvascular hydrostatic pressures in normal and hypoproteinemic conditions were equal. This was based on the assumption that microvascular hydrostatic pressure did not change with plasma protein depletion. These conditions could be satisfied when the small pores accounted for 90% of total barrier porosity. According to the model, lymph flow increased in hypoproteinemia because of an increase in protein-free liquid flux through the large percentage of small pores; protein flux through the small percentage of large pores remained unchanged. The net result was an increase in lymph flow and a decrease in the lymph protein concentration. The model reproduced these changes even though the plasma-to-lymph osmotic pressure gradients were unchanged. We conclude that a simplified heteropore model can explain the effects of hypoproteinemia on lung and soft tissue lymph flux.

Animals↗
PubMed1976

The opiate receptor: a model explaining structure-activity relationships of opiate agonists and antagonists.

A model of the opiate receptor is proposed which explains structure-activity relationships of opiate drugs, including (i) the unique potency of certain opiates such as etonitazene, fentanyl, phenazocine, and oripavines; (ii) the role of N-allyl substituents in conferring antagonist properties; and (iii) chemical features that afford "pure" antagonists. The model indicates mlecular mechanisms for interconversion of the opiate receptor between respective states that bind agonists or antagonists with high affinity.

Allosteric Regulation↗
PubMed1990

Measurements of plasma colloid osmotic pressure, total protein and sodium concentration during haemodialysis: can single-pool sodium modelling explain the results?

Considering the plasma colloid osmotic pressure (COP) as a possible parameter for the monitoring of dialysis treatment compatibility, a characteristic time course was found. The COP and the total protein concentration very often do not increase significantly during the first treatment hour in spite of ultrafiltration. An increase in the plasma sodium concentration, which was higher than expected, was found to be the reason for a plasma dilution effect. This can be explained by a transcapillary sodium transfer coefficient which is not infinitely high as assumed in single-pool sodium modelling. From a 2-pool model considering the plasma volume as a separate pool and including capillary filtration time courses for plasma sodium, total protein concentration and COP could be calculated, which was very similar to the measured curves.

Blood Proteins↗
PubMed2025

EDAmame: interactive exploratory data analyses with explainable models.

SUMMARY: Complex tabular datasets comprising many diverse features can require specific expertise to interpret, posing a barrier to researchers with minimal data science experience. EDAmame is an interactive tool that simplifies initial analysis and visualization of these datasets, providing insights into data quality and feature relationships. By leveraging open-source machine learning frameworks in R, EDAmame allows researchers to perform effective exploratory data analysis without command-line or coding requirements. AVAILABILITY AND IMPLEMENTATION: A limited online version can be accessed at https://edamame.org.au/ or can be downloaded from https://doi.org/10.5281/zenodo.15356492. The app is developed in R Shiny and implements tidyverse and tidymodels packages.

Machine Learning↗
PubMed1978

Effect of enzymatic adenylylation on dihydrostreptomycin accumulation in Escherichia coli carrying an R-factor: model explaining aminoglycoside resistance by inactivating mechanisms.

Strains of Escherichia coli carrying R-factor R71(a), which codes for a streptomycin-spectinomycin adenylyltransferase, have elevated levels of resistance to dihydrostreptomycin (DHS) compared with isogenic R(-) bacteria. DHS accumulated by whole cells and spheroplasts of R(+) bacteria is lower than that observed for R(-) strains, a result of the absence of the second and more rapid of the two energy-dependent phases of DHS uptake seen in susceptible E. coli. A mutant of R(+)E. coli with reduced DHS resistance has been shown to have reduced levels of streptomycin-spectinomycin adenylyltransferase activity as well as enhanced drug accumulation. Actively accumulated DHS was recovered from R(+) cells as the adenylylated derivative. Neither was inactivated antibiotic detected in culture filtrates, nor was actively accumulated drug lost from R(+) cells under normal conditions. The cellular distribution of actively accumulated DHS in R(+) and R(-) cells was found to be the same. Membranes isolated from these cells retained only a small fraction ( approximately 1%) of the total cell-associated drug. The R(+) derivative of a mutant with defective energy transduction (E. coli NR-70) and reduced ability to transport aminoglycosides has a significantly higher minimal inhibitory concentration of DHS than its R(+) parent (strain 7). Streptomycin-spectinomycin adenylyltransferase activity, from comparisons of K(m) values and total activities of enzyme, was the same in both strains. The enzyme has been localized to the exterior surface of the bacterial inner membrane, although isolated membranes lacked detectable enzyme activity. The preceding observations are consistent with the proposal that the level of R71(a)-mediated DHS resistance is the outcome of competition between the rate of adenylylation and the rate of the first energy-dependent phase of DHS transport. When the rate of adenylylation exceeds the first energy-dependent phase, adenylylated DHS is accumulated, apparently in a manner identical to the accumulation of DHS. Unlike DHS, adenylylated DHS does not interact with ribosomes, and, consequently, there is a failure to initiate ribosomally dependent sequelae such as the second energy-dependent phase of accumulation, inhibition of protein synthesis, and/or misreading of mRNA.

Aminoglycosides↗
PubMed1990

[Simple model explaining the caries inhibiting effect of fluoride].

The pH at which enamel dissolves is affected by presence of fluoride in the plaque fluid. It appears that the degree of oral hygiene will also be important because pH can drop so low in old plaque that even solid fluorapatite dissolves. Improved oral hygiene would thus reduce caries in high risk patients even in the presence of fluoride.

Dental Caries↗
PubMed1979

A cell kinetic model to explain the time of appearance of skin reaction after X-rays or ultraviolet light irradiation.

Skin reactions to various doses of X-rays (300 and 10 kV) and ultraviolet light (u.v.) have been compared using hairless mice. Two regions of epidermis with widely differing cell kinetics and gross structure have been compared. Little evidence could be found to support the idea that the early phases of the reaction are dependent on cell cycle time. The data can be explained by a model based on the assumption that epidermis contains only a small fraction of clonogenic (stem) cells and this fraction may vary in different epidermal regions. X-rays appear to exert their greatest destructive action on these clonogenic cells while u.v. is more indiscriminate in its action, killing both clonogenic and non-clonogenic cells.

Animals↗
PubMed1992

Synthesis and dopaminergic activity of some 3-(1,2,3,6-tetrahydro-1-pyridylalkyl)indoles. A novel conformational model to explain structure-activity relationships.

The synthesis and dopaminergic properties of a novel type of dopamine agonist is described. The number and kind of essential structural elements differ significantly from that of the rigid apomorphine-type dopamine agonists. Using standard molecular modeling techniques, a conformational model is developed proposing a U-shaped conformation which might be energetically preferred through aromatic pi-pi-interactions between both of the electron rich aromatic structural elements of this class of compounds. Superimposition of conformations of the lead compound 28 with apomorphine yields a novel model explaining the atypical structure-activity relationships found in this class of indolealkylamines.

Animals↗
PubMed1975

Kinetics and mechanisms of monolayer interactions. III: models to explain time-dependent effects of injected cetrimonium bromide.

Two kinetic models are derived to explain the time-dependent effects of cetrimonium ions injected beneath an air-aqueous solution interface without any previously adsorbed or spread monolayer at different ionic strengths. The data show excellent fit and consistency with a nulticompartmental kinetic model which postulates a barrier or intermediate compartment between the ionic surfactant in the subphase and the sites on the surface. Such a barrier inhibits free diffusion of the surfactant from the bulk of the solution to these sites. The experimental data are not inconsistent with a model that postulates a time-dependent binding process and the absence of a diffusion-limiting subinterface since, within the limits of the error, the derived rate constants conform to the model prediction that they should be proportional to the surfactant-ion concentration.

Adsorption↗
PubMed1991

Comparison of linear and exponential multivariate models for explaining national infant and child mortality.

Product form multivariate regression models (multiplicative exponential) were developed with infant and child mortality as outcomes, and national economic, health, nutrition, education, and demographic statistics as predictor variables. The models were applied to data from 129 countries, resulting in R-square values for the product form models of infants and child mortality of 0.77 and 0.80. For comparison purposes, more conventional sum form models (additive linear) were also estimated, and yielded R-square values (0.22, 0.29) markedly lower than the product form models. The product form models also had a much more uniform distribution of residuals and provided improved model fit across the different categories of nations. An inherent advantage to the product form models is that they did not predict negative mortality rates, in contrast to the sum form models which did predict negative mortalities for some of the more developed nations. Using a product form model, the correlation between physicians per capita and infant mortality was shown to be negative rather than positive--thus correcting for an anomaly seen in previous studies which showed a positive correlation between physicians per capita and infant mortality.

Child↗
PubMed1979

A model to explain the posterior limit of the bite point in reptiles.

A biomechanical model of the jaw mechanism in some reptiles is presented. Symmetrical muscle activity that produces equal forces on both sides of the head is assumed. The model predicts the position of the most posterior bit point and offers a functional explanation for this prediction. Turtles are used to illustrate the idea.

Animals↗
PubMed1978

A tunnelling model to explain the reduction of ferricytochrome c by H and OH radicals.

The kinetics of the reaction of OH radicals with ferricytochrome c was studied in the time range 1 microsecond to 1 s by means of pulse radiolysis. The OH radicals reduce ferricytochrome c by 40% +/- 10%. The time course of the reduction is explained by a mechanism whereby a radical formed after hydrogen has been abstracted from the outer surface of the protein reduces the iron by electron tunnelling. We have calculated that the reducing electron in the radical is bound with an energy of at least 1.75 eV and that the frequency factor of the tunnelling process is v=10(11.5)s-1. This model accounts for the observed absorbance change in time range 5 . 10(-6)--10(-1)s. The time course of the reduction of ferricytochrome c by H radicals (Lichtin, N.N., Shafferman A. and Stein, G. (1974) Biochim. Biophys. Acta 357, 386--398) is explained by the same model.

Calorimetry↗
PubMedDate not supplied

An educational model for explaining hospice services.

Explaining the concept and philosophy of hospice can be difficult. There is a reluctance in our society to openly address dying/death issues; there is a reluctance on the part of many health-care professionals to look beyond physical issues. The following model has been used successfully to explain hospice to both the general public and health care professionals. It is not intended to introduce hospice to a patient/family during the initial referral/assessment visit.

Health Education↗
PubMed1976

Simple model to explain effects of plasma protein binding and tissue binding on calculated volumes of distribution, apparent elimination rate constants and clearances.

A simple pharmacokinetic model, incorporating linear plasma protein binding, linear tissue binding, and first order elimination of free (unbound) drug, was studied. If Clp is the plasma clearance, Vf is the "true" volume of distribution of free drug, beta is the apparent elimination rate constant, sigma is the fraction of the drug which is free in plasma, f is the fraction of the drug which is free in the entire body, kf is the intrinsic elimination rate constant for free drug, and AoTB is the initial amount of drug which is bound to tissues, then the model indicates that the following relationships hold: (1) Clp = Vfsigma kf; (2) beta = f kf; and Vdext = (sigma/f) Vf. Only sigma, and not f, can be measured experimentally. Dividing Clp by sigma provides an estimate of the intrinsic clearance of free drug, Vfkf. A plot of Vdext versus sigma has an intercept equal to Vf, and the ratio of the slope/intercept is an estimate of AoTB/Aof, where Aof is the initial amount of free drug (equal to Vf times initial concentration of free drug in plasma). Thus, an estimate of AoTB may be obtained. Dividing the intrinsic clearance by Vf provides an estimate of kf. Thus, theoretically, estimates of Vf, kf, AoTB and f may be obtained. The variables are not separated when beta is plotted versus sigma, and curvature of such plots is expected; no useful information is obtained from such plots.

Blood Proteins↗