PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “predictive modelling”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources
PubMed1990

Predictive models for achievement of complete remission and duration of first remission in adult acute myeloid leukemia.

Achievement of CR. Using the data of 501 patients treated identically with the TAD9 regimen we could not find any factor of predictive value besides age and state of health. The effect of FAB-M seems to be spurious as it disappeared using prospective data. Duration of Relapse-Free Survival. In patients with monthly maintenance, the maintenance overrides the possible effects of the considered factors. In patients without monthly maintenance we only found a slight effect of WBC.

Aged↗
PubMed1997

Effects of avitriptan, a new 5-HT 1B/1D receptor agonist, in experimental models predictive of antimigraine activity and coronary side-effect potential.

Several acutely acting antimigraine drugs, including ergotamine and sumatriptan, have the ability to constrict porcine arteriovenous anastomoses as well as the human isolated coronary artery. These two experimental models seem to serve as indicators, respectively, for the therapeutic and coronary side-effect potential of the compounds. Using these two models, we have now investigated the effects of avitriptan (BMS-180048; 3-[3-[4-(5-methoxy-4-pyrimidinyl)-l-piperazinyl[propyl]-N-methyl-l H-indole-5-methane-sulfonamide monofumarate), a new 5-HT 1B/1D receptor agonist. In anaesthetized pigs, avitriptan (10, 30, 100 and 300 micrograms.kg-1) decreased the total carotid blood flow by exclusively decreasing arteriovenous anastomotic blood flow; capillary blood flow was increased. The mean +/- SEM i.v. dose of avitriptan eliciting a 50% decrease (ED50) in the porcine carotid arteriovenous anastomotic blood flow was calculated to be 76 +/- 23 micrograms.kg-1 (132 +/- 40 nmol.kg-1) and the highest dose (300 micrograms.kg-1) produced a 72 +/- 4% reduction. In recent comparative experiments (DeVries et al. 1996), the mean +/- SEM ED50 (i.v.) of sumatriptan in decreasing carotid arteriovenous anastomotic blood flow was 63 +/- 17 micrograms.kg-1 (158 +/- 43 nmol.kg-1), with a reduction of 76 +/- 4% by 300 micrograms.kg-1, i.v. Both avitriptan (pD2; 7.39 +/- 0.09; Emax: 13.0 +/- 4.5% of the contraction to 100 mM K+) and sumatriptan (pD2: 6.33 +/- 0.09; Emax: 15.5 +/- 2.3% of the contraction to 100 mM K+) contracted the human isolated coronary artery. The above results suggest that avitriptan should be able to abort migraine headaches in patients, but may exhibit sumatriptan-like effects on coronary arteries. Initial clinical studies have demonstrated the therapeutic action of the drug in acute migraine.

Animals↗
PubMed2002

Post-RT CT results as a predictive model for the necessity of planned post-RT neck dissection in patients with cervical metastatic disease from squamous cell carcinoma.

PURPOSE: To establish whether the extent of neck disease on postradiation therapy (RT) computed tomography (CT) can predict the likelihood of positive neck nodes and, thereby, the necessity of planned post-RT neck dissection. METHODS AND MATERIALS: Ninety-five patients who underwent post-RT neck dissection within 2 months for squamous cell carcinoma of the head and neck were eligible. Of the 95 patients, 37 (32.7%) of 113 hemineck specimens were pathologically positive. On post-RT CT imaging studies, the number and size of lymph nodes >1 cm were recorded. Internal focal defects and the likelihood of extracapsular spread were graded. RESULTS: If lymph nodes on post-RT CT were < or = 15 mm, free of significant internal focal low-attenuation or calcification, and without imaging evidence of extracapsular spread, the surgical hemineck specimen was positive in 1 (3.4%) of the 29 hemineck specimens. A focal low-attenuation defect (p = 0.0078) and evidence of extracapsular spread (p = 0.0721) seen in the residual nodal mass on CT were independent predictors of a positive surgical specimen by multivariate analysis. CONCLUSION: CT findings on post-RT neck studies can help predict the likelihood of residual disease and, thereby, the necessity of planned post-RT neck dissection.

Adult↗
PubMed2006

Flux decline in nanofiltration due to adsorption of dissolved organic compounds: model prediction of time dependency.

Flux decline during nanofiltration of aqueous solutions containing dissolved organic compounds is mainly caused by adsorption of these compounds in the membrane pores and on the membrane surface. In this paper, flux decline is modeled by incorporating the loss of permeability due to adsorption in the Spiegler-Kedem equation. This results in a logarithmic relation between normalized flux decline and time until the adsorption equilibrium is reached and the flux reaches a constant value. In this way, the expected flux decline due to adsorption of organic compounds can be estimated. Two different parameters were used in the model: the time delay t(0), which corresponds to the time at which the adsorption process in the membrane pores and on the membrane surface sets in, and the corresponding reduction of free (pore) volume (b). Both parameters depend on the hydrophobicity of the compounds and on the feed concentration.

Journal Article↗
PubMed2004

Comparison of three models predicting developmental milestones given environmental and individual variation.

In all organisms, phenotypic variability is an evolutionary stipulation. Because the development of poikilothermic organisms depends directly on the temperature of their habitat, environmental variability is also an integral factor in models of their phenology. In this paper we present two existing phenology models, the distributed delay model and the Sharpe and DeMichele model, and develop an alternate approach, called the Extended von Foerster model, based on the age-structured McKendrick-von Foerster partial differential model. We compare the models theoretically by examining the biological assumptions made in the basic derivation of each approach. In particular, we focus on each model's ability to incorporate variability among individuals as well as variability in the environment. When compared against constant temperature mountain pine beetle (Dendroctonus ponderosae Hopkins) laboratory developmental data, the Extended von Foerster model exhibits the highest correlation between theory and observation.

Animals↗
PubMed2001

Validation of a mapping and prediction model for human fasciolosis transmission in Andean very high altitude endemic areas using remote sensing data.

The present paper aims to validate the usefulness of the Normalized Difference Vegetation Index (NDVI) obtained by satellite remote sensing for the development of local maps of risk and for prediction of human fasciolosis in the Northern Bolivian Altiplano. The endemic area, which is located at very high altitudes (3800-4100 m) between Lake Titicaca and the valley of the city of La Paz, presents the highest prevalences and intensities of fasciolosis known in humans. NDVI images of 1.1 km resolution from the Advanced Very High Resolution Radiometer (AVHRR) sensor on board the National Oceanic and Atmospheric Administration (NOAA) series of environmental satellites appear to provide adequate information for a study area such as that of the Northern Bolivian Altiplano. The predictive value of the remotely sensed map based on NDVI data appears to be better than that from forecast indices based only on climatic data. A close correspondence was observed between real ranges of human fasciolosis prevalence at 13 localities of known prevalence rates and the predicted ranges of fasciolosis prevalence using NDVI maps. However, results based on NDVI map data predicted zones as risk areas where, in fact, field studies have demonstrated the absence of lymnaeid populations during snail surveys, corroborated by the absence of the parasite in humans and livestock. NDVI data maps represent a useful data component in long-term efforts to develop a comprehensive geographical information system control program model that accurately fits real epidemiological and transmission situations of human fasciolosis in high altitude endemic areas in Andean countries.

Altitude↗
PubMed2000

Development and evaluation of a model predicting the survival of Escherichia coli O157:H7 NCTC 12900 in homemade eggplant salad at various temperatures, pHs, and oregano essential oil concentrations.

Homemade eggplant salad, a traditional Greek appetizer, was inoculated with Escherichia coli O157:H7 NCTC 12900 supplemented with different concentrations of oregano essential oil (0.0, 0.7, 1. 4, and 2.1% [vol/wt]) and stored at different temperatures (0, 5, 10, and 15 degrees C). The product's pH was adjusted to 4.0, 4.5, or 5. 0 with lemon juice. For each combination of the environmental factors, the bacterial counts were modeled, using the Baranyi model, as a function of time to estimate the kinetic parameters of the pathogen. A reduction of more than 1 log unit in E. coli O157:H7 counts was observed in all cases, and the death rate depended on the pH, the storage temperature, and the essential oil concentration. Separate quadratic models were developed with natural logarithms of the shoulder period and death rate as estimated by the growth model, as a function of temperature, pH, and oregano essential oil concentrations. These were further used to predict the population of E. coli O157:H7 NCTC 12900 from other inoculated eggplant salads at random conditions of temperature, pH, and oregano oil concentration. The predicted values were compared with viable-count measurements for validation.

Colony Count, Microbial↗
PubMed1994

Remotely related sequences and structures: analysis and predictive modelling.

Through the comprehensive analysis of protein sequence and structural data, relationships can be established that suggest, with varying degrees of success, structural models for a protein for which only the sequence is known. The certainty with which a model can be proposed depends on the degree of similarity between the sequence of unknown structure and the sequence of a protein of known structure. Methods are being developed to detect remote similarities between sequences or structures, and to predict protein structure based on such small levels of similarity.

Amino Acid Sequence↗
PubMed2000

Functional profile of almotriptan in animal models predictive of antimigraine activity.

Almotriptan is a new 5-HT(1B/1D) receptor agonist whose clinical efficacy for the treatment of migraine attacks has been demonstrated in Phase III clinical trials. We now compare the functional profile of almotriptan (assessed using animal models) with that of sumatriptan. Almotriptan selectively increased carotid vascular resistance in anaesthetised cats after intravenous or intraduodenal administration (ED(100)=11 microg/kg, i.v.; ED(50)=339 microg/kg, i. d.) and in anaesthetised beagle dogs following intravenous administration (ED(50)=116 microg/kg). A study in anaesthetised cats also demonstrated that almotriptan acts by selectively increasing the resistance of the carotid arteriovenous anastomoses without adversely affecting brain irrigation. In addition, almotriptan inhibited meningeal extravasation produced by electrical stimulation of the trigeminal ganglion in anaesthetised guinea pigs in the dose range of 0.3-3 mg/kg, i.v. In conclusion, almotriptan is both a selective constrictor affecting intracranial blood vessels and an inhibitor of neurogenically evoked plasma protein extravasation of the dura mater.

Animals↗
PubMed1993

Evaluation of two prediction models for digoxin dosing.

The relationship between the digoxin elimination parameter (A%) and creatinine clearance (CLCr) was determined, from blood level data of 160 hospital patients receiving digoxin tablets. The linear regression equation obtained, which varied only slightly from that reported by Jelliffee previously, was used to predict serum digoxin concentrations in 140 patients of four age groups (50-60, 60-70, 70-80 and 80-90 years). The predictions made were found to be less biased and more precise, irrespective of the age of the patients, than those produced using another predictive method known as Dobbs method. However, correlation coefficients of predicted versus measured serum digoxin concentrations for each method did not differ significantly and frequency distribution analyses of prediction errors gave poor results (up to 63% only). Therefore, neither method can be considered to be superior to the other nor can they be said to ensure accurate predictions of serum digoxin concentrations.

Aged↗
PubMed1992

Comparing the accuracies of entire-group and subgroup models to predict NBME-I scores for medical school applicants.

To address the question of whether prediction models for subgroups of medical school applicants lead to more accurate predictions of performance than does one model for an entire group of applicants, the authors used data from two groups of students at Jefferson Medical College: 415 students who entered Jefferson in 1985 and 1986, and 396 who entered in 1987 and 1988. Both groups were divided into two subgroups by gender and two subgroups by age. Data from the first group were used to develop prediction models based on the entire group and on its four subgroups. The predictors were undergraduate grade-point averages and Medical College Admission Test scores; the criterion measures were scores on the National Board of Medical Examiners Part I examinations. The prediction models were then applied to data from the second group and its four subgroups: differences in the validity coefficients (.40 to .56) and residual scores (7.2 to 17.9) were not considered to be of practical importance. Hence, the authors suggest that gender and age do not contribute to a prediction bias and that an entire-group prediction model can be used without serious concern for over-or underestimating the predicted scores.

Adult↗
PubMed2003

Gene expression profiling in clinically localized prostate cancer: a four-gene expression model predicts clinical behavior.

PURPOSE: New diagnostic and prognostic molecular markers are required for prostate cancer, one of the most common male malignancies in Western countries. Gene expression profiling may help to identify genes involved in prostate carcinogenesis, yield clinical biomarkers, and improve tumor classification. EXPERIMENTAL DESIGN: To identify fundamental differences between normal and neoplastic prostate tissue, we used real-time quantitative RT-PCR assays to quantify the mRNA expression of 291 selected genes in samples of normal prostate and of well-documented primary, clinically localized prostate tumors. RESULTS: Forty-six genes showed significantly different expression in tumors relative to normal prostate. The dysregulated genes belong notably to the extracellular membrane and extracellular membrane remodeling categories and are involved in angiogenesis. Furthermore, we obtained a four-gene (XLKD1/LYVE1, CGA, F2R/PAR1, and BCL-G) model that discriminated between the seven patients with and the seven patients without relapse, independently of stage and grade. CONCLUSIONS: Some dysregulated genes are good candidates for use as molecular markers and/or therapeutic targets. Furthermore, differential gene expression profiling of clinically localized prostate tumors from relapsing and nonrelapsing patients identified a set of four genes with a pattern of expression that defines a molecular signature that could predict the clinical behavior of this disease.

Aged↗
PubMed1985

Ultrasonic estimation of fetal weight: a new predictive model incorporating femur length for the low-birth-weight fetus.

Ultrasonic measurements of biparietal diameter, head circumference, abdominal circumference, and femur length were made in 50 preterm fetuses within 48 h of delivery. Measurements of femur length in addition to fetal head and abdomen significantly improved fetal weight prediction. A computer-derived formula incorporating femur length as an index of total fetal length was derived. This predicted 84% of weights within 10% of the birth weight. Comparisons with other formulas are given.

Birth Weight↗
PubMed2002

The confirmation rate of primary hits: a predictive model.

HTS data from primary screening are usually analyzed by setting a cutoff for activity, in order to minimize both false-negative and false-positive rates. An alternative approach, based on a calculated probability of being active, is presented here. Given the predicted confirmation rate derived from this probability, the number of primary positives selected for follow-up can be optimized to maximize the number of true positives without picking too many false positives. Typical cutoff-determining methods are more serendipitous in their nature and not easily optimized in an effort to optimize screening efforts. An additional advantage of calculating a probability of being active for each compound screened is that orthogonal mixtures can be deconvoluted without presetting a deconvolution threshold. An important consequence of using the probability of being active with orthogonal mixtures is that individual compound screening results can be recorded irrespective of whether the assays were performed on single compounds or on cocktails.

Biological Assay↗
PubMed2001

War head injury score: an outcome prediction model in War casualties with acute penetrating head injury.

OBJECTIVE: To evaluate in war casualties with acute penetrating head injury whether the summed War Head Injury Score (WHIS) is a better predictor of mortality than either the Glasgow Coma Scale (GCS) score or the Injury Severity Score (ISS) alone and to establish its specific applicability. METHODS: Sensitivity, specificity, correct outcome prediction, and discrimination were assessed in 43 patients in the war group (ballistic injuries) and 41 patients in the civil group (nonballistic injuries) during the period 1991 to 1995. The new model was generated using the sum of GCS scores and ISS, to which a coded value was applied for summation. RESULTS: In the war group, the mortality rate was 23%; the sensitivity and specificity of WHIS were 100% and 79%, the sensitivity and specificity of GCS score were 90% and 85%, and the sensitivity and specificity of ISS were 100% and 49%, respectively. In the civil group, the mortality rate was 39%; the sensitivity and specificity of WHIS were 87% and 76%, the sensitivity and specificity of GCS score were 63% and 90%, and the sensitivity and specificity of ISS were 100% and 56%, respectively. CONCLUSION: With regard to civilians, war casualties with acute penetrating head injury more often have multiple injuries. WHIS represents a new scoring system that incorporates both GCS score and ISS.

Adult↗
PubMed1996

Investigations with GMC2021 in experimental models predictive of antimigraine activity and coronary side-effect potential.

Several acutely acting antimigraine drugs, including sumatriptan and other second generation 5-HT1D receptor agonists, have the ability to constrict porcine carotid arteriovenous anastomoses as well as the human isolated coronary artery. These two experimental models seem to serve as indicators, respectively, for the therapeutic and coronary side-effect potential of the compounds. Using these two models, we have now investigated the effects of GMC2021 (3-[2-(dimethylanimo)ethyl]-5-[(trifluoromethyl)sulfonyl]oxy][1 H]indole oxalate, a close analogue of sumatriptan. GMC2021 (30, 100, 300 and 1000 micrograms.kg-1, i.v.) decreased the total carotid blood flow by exclusively decreasing arteriovenous anastomotic blood flow; capillary blood flow to the skin and ears was moderately increased. The mean +/- S.E.M. dose of GMC2021 eliciting a 50% decrease (ED50) in the porcine carotid arteriovenous anastomotic blood flow was found to be 1.1 +/- 0.3 mumol.kg-1 and the highest dose (1000 micrograms.kg-1) produced a 67 +/- 4% reduction. The carotid haemodynamic effects of GMC2021 were reduced by the selective 5-HT1D receptor antagonist, GR127935 (N-[methoxy-3-(4-methyl-1- piperazinyl)phenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)[1 , 1-biphenyl]-4-carboxamide hydrochloride), which completely antagonizes porcine carotid haemodynamic responses to sumatriptan (ED50: 0.16 mumol.kg-1, i.v.). Compared to sumatriptan (pD2: 6.12 +/- 0.15; Emax: 31.3 +/- 12.3% of contractions to 100 mM K+), GMC2021 was less potent in constricting the human isolated coronary artery (pD2: 5.45 +/- 0.2; Emax: 21.0 +/- 4.8% of contractions to 100 mM K+). The above results suggest that GMC2021 constricts carotid arteriovenous anastomoses partly by a 5-HT1D receptor and partly by another, probably novel, receptor and that GMC2021 should be able to abort migraine headaches in patients, with perhaps a less propensity for coronary side effects.

Animals↗