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PubMed1979

Opponent chromatic mechanisms: relation to photopigments and hue naming.

Opponent chromatic response functions were determined from monochromatic, equal-luminance stimuli from 400 to 700 nm for three observers using a hue cancellation procedure. The same observers scaled the hue of the stimuli using the terms red, green, yellow, and blue. The results showed that the hue scaling was accurately predicted from the cancellation functions using the model of Hurvich and Jameson. Theoretical curves were generated to fit the chromatic response functions with a linear combination of three cone photopigments. The theoretical photopigments were based on an idopsin nomogram with lambdamax at a = 435, beta = 530, and lambda = 562 nm. An estimate of the density of each observer's preretinal optic media was obtained in order to relate the photopigment absorption spectra to the psychophysical data. Good linear fits were obtained for each observer's red-green curve, but not for the yellow-blue curves. A nonlinear model with an expansive exponent was used to fit the yellow-blue response functions with the three theoretical photopigments.

Adult↗
PubMed1991

An updated comparison of drug dosing methods. Part IV: Vancomycin.

The resurgence of the use of and interest in vancomycin, in conjunction with the high degree of interpatient variability in its pharmacokinetic profile, has prompted the development of many and varied dosing methods. Several dosing nomograms have been proposed and evaluated, methods which are useful for initial dosing but do not allow for individualisation of dosage. Given these constraints, several investigators have attempted to apply conventional least-squares regression techniques and, more recently, Bayesian methodologies using either 1- or 2-compartment pharmacokinetic models. Comparative information evaluating algorithmic methods demonstrates that those of Moellering and Lake offer the least biased and most precise predictions of vancomycin dosage. Patient individualisation using conventional least-squares methodology offers some improvement over nomogram-based methods, both in predictive performance and in dosage adjustment once serum concentration data are available. Overall, the latest data indicate that regimens which incorporate Bayesian principles tend to give better results than nomogram-based or conventional least-squares dosing methods for this drug. Despite the advances in methods for dosing vancomycin, several questions remain to be answered. A lack of convincing evidence of a correlation between serum concentrations and therapeutic outcome has prompted debate over the need for serum concentration monitoring and, if it is needed, over which patient population would most benefit. Secondly, little comparative information is currently available as to the dosing of vancomycin in paediatric and neonatal patient populations. Several nomograms for initial dosing have been proposed, but only 2 have been subject to subsequent testing. Finally, information regarding cost-effectiveness and the quality of patient outcome is lacking from the current literature.

Bayes Theorem↗
PubMed2006

Does a delay between diagnosis and radical prostatectomy increase the risk of disease recurrence?

BACKGROUND: Men diagnosed with clinically localized prostate carcinoma have several treatment options. The investigation of these options may delay the initiation of definitive therapy. In the current study, the authors evaluated whether time from biopsy to radical prostatectomy (RP) was predictive of postoperative biochemical disease recurrence (BCR). METHODS: A total of 3149 consecutive patients who underwent RP as their initial treatment for prostate carcinoma within a year of diagnosis were identified. The time between diagnosis and RP was entered as a predictor in a multivariate logistic regression model predicting BCR at 3 years, 5 years, 8 years, and 10 years. The year surgery was performed and the nomogram-predicted probability of recurrence, which incorporates stage of disease, Gleason grade, and prostate-specific antigen (PSA) level, were used as covariates. RESULTS: The authors found no clear evidence of a significant effect of delay to diagnosis on BCR. For those patients treated within 6 months (96% of the total sample) the odds ratio for each additional month of delay was 1.04, 1.07, 1.08, and 1.02, respectively, for 3-year, 5-year, 8-year, and 10-year BCR-free survival (P>0.2 for all analyses). However, the 95% confidence intervals were wide and included the possibility that even a minor delay in surgery might have a large impact on the probability of BCR. CONCLUSIONS: The time between biopsy and surgery does not appear to have a large effect on the risk of disease recurrence. Counseling patients on the importance of avoiding undue delay to surgery must be based on clinical judgment, particularly with respect to modifying advice based on the patient's risk.

Aged↗
PubMed2001

A study of pretreatment nomograms to predict pathological stage and biochemical recurrence after radical prostatectomy for clinically resectable prostate cancer in Japanese men.

BACKGROUND: Accurate pretreatment identification of the risks that prostate cancer has extended beyond the gland and that it will recur would significantly influence practice patterns. Preoperative nomograms to predict such risks have not been developed for the oriental male population. METHODS: Construction of nomograms to predict preoperatively pathological outcome and early biochemical failure following radical prostatectomy in Japanese males was based on logistic regression analysis, with predicted probabilities and 95% confidence intervals for the final model being obtained by repeating the analysis on 1000 bootstrap samples from the original cohort. RESULTS: Prostate-specific antigen level, clinical stage and biopsy Gleason score contributed significantly to the prediction of pathological stage and of biochemical failure in the univariate analysis (p < 0.001). Combined use of these three variables predicted these treatment outcomes better than any single variable (p < 0.001). Nomograms combining these three variables to predict final pathological findings and early biochemical failure were then developed. The medians and 95% confidence intervals of the predicted probabilities are presented in the nomograms. CONCLUSIONS: This information enables clinicians to use their nomograms when counseling Japanese patients, leading to more informed treatment decisions and helping to identify those with a high risk of early biochemical failure. The nomograms may also be used to assure comparability of different treatment modalities in investigational trials.

Aged↗
PubMed2002

Estimation of prostate cancer risk on the basis of total and free prostate-specific antigen, prostate volume and digital rectal examination.

BACKGROUND AND OBJECTIVE: Approximately 70% of the men with an elevated serum prostate-specific antigen (PSA) identified in prostate cancer screening do not have prostate cancer. Other available diagnostic variables may be utilized to reduce the number of false positive PSA results, but few algorithms for calculation of the combined impact of multiple variables are available. The objective of this study was to establish nomograms showing the probability of detecting prostate cancer at biopsy on the basis of total PSA, and the percentage of free PSA in serum, prostate volume and digital rectal examination (DRE) findings. METHODS: In a randomized, population-based prostate cancer screening trial 10284 men aged 55-67 years were screened during 1996 and 1997 in two metropolitan areas in Finland. Results for men (n=758) with a serum PSA of 4-20 microg/l were used to establish the risk nomograms. Of these 200 (26%) had prostate cancer at biopsy. RESULTS: Prostate cancer probability depended most strongly on the percentage of free PSA. Total PSA, prostate volume, and DRE also contributed to prostate cancer probability, whereas age and family history of prostate cancer did not. More false positive PSA results could be eliminated by using the multivariate risk model rather than the percentage of free PSA (p<0.001) or PSA density (p=0.003) alone. CONCLUSIONS: Wide variation in probability of detecting prostate cancer among screened men with a serum PSA of 4-20 microg/l was observed. The nomograms established can be used to avoid or defer biopsy in men with a low prostate cancer probability in spite of a serum PSA level exceeding 4 microg/l.

Aged↗
PubMed2025

Anoikis classification of lung squamous cell carcinoma reveals correlation with clinical prognosis and immune characteristics.

BACKGROUND: Anoikis is a new mode of cell death that has been shown to correlate significantly with tumors. However, the clinical prognostic significance of anoikis in lung squamous cell carcinoma (LUSC) remains poorly studied. METHODS: The differentially expressed ARGs and candidate genes were selected by the differential analysis to construct a predictive model. Independent prognostic gene was determined by Cox and LASSO analysis and we used the HCC95 and NCI H520 cell line to verify the gene function. We used the data from TCGA, GEO, GeneCards, and Harmonizome databases to analyze the immune microenvironment, functional enrichment, and drug sensitivity analysis. RESULTS: We identified 717 differentially expressed and selected 3 ARGs (FADD, SNAI1, and BAG4) to construct a predictive model. We found that SNAI1 is an independent prognostic gene and confirmed that knocking out the SNAI1 inhibited the HCC95/NCI H520 cell proliferation. We used single-sample gene-set enrichment analysis (ssGSEA) to evaluate the immune infiltration based on the 3 ARG expression levels. We constructed a risk score and provided a visual representation of the prophetic implications of the ARGs-based signature through a nomogram. We found 15 susceptible drugs in the high-risk group and 15 sensitive drugs in the low-risk group by the drug sensitivity analysis. CONCLUSION: We used ARGs to construct a prognosis model for LUSC that can accurately predict the prognosis of LUSC patients. ARGs, especially SNAI1, play an essential role in developing LUSC. These findings could provide individualized treatment plans and new research ideas for LUSC patients.

Humans↗
PubMed1997

Pharmacokinetics and pharmacodynamics of remifentanil. II. Model application.

BACKGROUND: The pharmacokinetics and pharmacodynamics of remifentanil were studied in 65 healthy volunteers using the electroencephalogram (EEG) to measure the opioid effect. In a companion article, the authors developed complex population pharmacokinetic and pharmacodynamic models that incorporated age and lean body mass (LBM) as significant covariates and characterized intersubject pharmacokinetic and pharmacodynamic variability. In the present article, the authors determined whether remifentanil dosing should be adjusted according to age and LBM, or whether these covariate effects were overshadowed by the interindividual variability present in the pharmacokinetics and pharmacodynamics. METHODS: Based on the typical pharmacokinetic and pharmacodynamic parameters, nomograms for bolus dose and infusion rates at each age and LBM were derived. Three populations of 500 individuals each, ages 20, 50, and 80 yr, were simulated base on the interindividual variances in model parameters as estimated by the NONMEM software package. The peak EEG effect in response to a bolus, the steady-state EEG effect in response to an infusion, and the time course of drug effect were examined in each of the three populations. Simulations were performed to examine the time necessary to achieve a 20%, 50%, and 80% decrease in remifentanil effect site concentration after a variable-length infusion. The variability in the time for a 50% decrease in effect site concentrations was examined in each of the three simulated populations. Titratability using a constant-rate infusion was also examined. RESULTS: After a bolus dose, the age-related changes in V1 and Ke0 nearly offset each other. The peak effect site concentration reached after a bolus dose does not depend on age. However, the peak effect site concentration occurs later in elderly individuals. Because the EEG shows increased brain sensitivity to opioids with increasing age, an 80-yr old person required approximately one half the bolus dose of a 20-yr old of similar LBM to reach the same peak EEG effect. Failure to adjust the bolus dose for age resulted in a more rapid onset of EEG effect and prolonged duration of EEG effect in the simulated elderly population. The infusion rate required to maintain 50% EEG effect in a typical 80-yr old is approximately one third that required in a typical 20-yr old. Failure to adjust the infusion rate for age resulted in a more rapid onset of EEG effect and more profound steady-state EEG effect in the simulated elderly population. The typical times required for remifentanil effect site concentrations to decrease by 20%, 50%, and 80% after prolonged administration are rapid and little affected by age or duration of infusion. These simulations suggest that the time required for a decrease in effect site concentrations will be more variable in the elderly. As a result, elderly patients may occasionally have a slower emergence from anesthesia than expected. A step change in the remifentanil infusion rate resulted in a rapid and predictable change of EEG effect in both the young and the elderly. CONCLUSIONS: Based on the EEG model, age and LBM are significant demographic factors that must be considered when determining a dosage regimen for remifentanil. This remains true even when interindividual pharmacokinetic and pharmacodynamic variability are incorporated in the analysis.

Adult↗
PubMed1997

Combination of prostate-specific antigen, clinical stage, and Gleason score to predict pathological stage of localized prostate cancer. A multi-institutional update.

OBJECTIVE: To combine the clinical data from 3 academic institutions that serve as centers of excellence for the surgical treatment of clinically localized prostate cancer and develop a multi-institutional model combining serum prostate-specific antigen (PSA) level, clinical stage, and Gleason score to predict pathological stage for men with clinically localized prostate cancer. DESIGN: In this update, we have combined clinical and pathological data for a group of 4133 men treated by several surgeons from 3 major academic urologic centers within the United States. Multinomial log-linear regression was performed for the simultaneous prediction of organ-confined disease, isolated capsular penetration, seminal vesicle involvement, or pelvic lymph node involvement. Bootstrap estimates of the predicted probabilities were used to develop nomograms to predict pathological stage. Additional bootstrap analyses were then obtained to validate the performance of the nomograms. PATIENTS AND SETTINGS: A total of 4133 men who had undergone radical retropubic prostatectomy for clinically localized prostate cancer at The Johns Hopkins Hospital (n=3116), Baylor College of Medicine (n=782), and the University of Michigan School of Medicine (n=235) were enrolled into this study. None of the patients had received preoperative hormonal or radiation therapy. OUTCOME MEASURES: Simultaneous prediction of organ-confined disease, isolated capsular penetration, seminal vesicle involvement, or pelvic lymph node involvement using updated nomograms. RESULTS: Prostate-specific antigen level, TNM clinical stage, and Gleason score contributed significantly to the prediction of pathological stage (P<.001). Bootstrap estimates of the median and 95% confidence interval of the predicted probabilities are presented in the nomograms. For most cells in the nomograms, there is a greater than 25% probability of qualifying for more than one of the pathological stages. In the validation analyses, 72.4% of the time the nomograms correctly predicted the probability of a pathological stage to within 10% (organ-confined disease, 67.3%; isolated capsular penetration, 59.6%; seminal vesicle involvement, 79.6%; pelvic lymph node involvement, 82.9%). CONCLUSIONS: The data represent a multi-institutional modeling and validation of the clinical utility of combining PSA level measurement, clinical stage, and Gleason score to predict pathological stage for a group of men with localized prostate cancer. Clinicians can use these nomograms when counseling individual patients regarding the probability of their tumor being a specific pathological stage; this will enable patients and physicians to make more informed treatment decisions based on the probability of a pathological stage, as well as risk tolerance and the values they place on various potential outcomes.

Decision Support Techniques↗
PubMed1989

Processes that contribute to radiocesium decontamination of feta cheese.

In a series of experiments, the transfer of radiocesium from ovine milk to feta cheese was investigated through modifications of the standard cheese making procedure. All variations explored showed no significant change in the percentage of radiocesium transfer and the milk-to-cheese transfer coefficient was determined as f=.79 plus/minus .04 L.kg-1. It is concluded that cesium, like the rest of the alkali metals, remains in the water phase and thus follows very closely the distribution of moisture into the products of cheese making. The possibility of radiocesium decontamination of mature feta during the customary storage of the product in brine was also explored in a second series of experiments. The theoretical model employed in the analysis of cesium transport from feta to brine is presented in the Appendix to this paper. Predictions of the model were validated by experiments. A procedure is thus proposed for decontaminating mature feta during storage through successive replacements of the storage medium. Nomograms are presented for the determination of the optimum time interval between changes of the brine and the radiocesium concentration remaining in the feta. Changes in the properties of the product induced by the proposed treatment were also investigated with respect to composition, taste, and overall quality.

Animals↗
PubMed1994

An analysis of birth weight by gestational age using a computerized perinatal data base, 1975-1992.

OBJECTIVE: To develop birth weight-for-gestational age nomograms based on a computerized perinatal data base collected prospectively from 1975-1992. METHODS: Using information from over 60,000 singleton deliveries (January 1975 through October 1992) at the MetroHealth Medical Center in Cleveland, Ohio, standard curves for normal birth weights were computed. Nomograms were developed for the overall population and for subgroups determined by factors known to affect fetal growth, including sex, race, smoking status, and gestational diabetes. The nomograms included the tenth, 50th, and 90th percentiles of birth weights for 24-44 weeks' gestation. Gestational age was based on clinical obstetric estimates confirmed by Dubowitz assessment of the neonate. In addition, third-order regression models were developed to predict median birth weight using gestational age. These models were validated using delivery data for the months of November and December, 1992, which were not included in model development. RESULTS: The most significant predictors of median birth weight were the first-, second-, and third-order gestational ages, which explained over 80% of the total variation in birth weight. Other significant factors influencing birth weight included infant gender, maternal race, parity, smoking, and diabetes status. Among the marginally significant factors influencing birth weight were pay status and maternal age. In general, before 33 weeks' gestation, there were few differences in the birth weight percentiles of various groups except for those with diabetes; infants of diabetic women exhibited greater birth weights as early as 26 weeks' gestation. CONCLUSIONS: Considering the large size of the data base and the diverse background of the study population, we believe that these nomograms provide useful norms of birth weight for an indigent urban population. These norms enhance the obstetrician's and neonatologist's ability to identify true cases of retardation or acceleration of intrauterine growth. Simple mathematical models provide easy calculation of the median birth weights for 24-44 weeks while adjusting for many confounding factors.

Adult↗
PubMed1999

In vitro analysis of colour Doppler flow with the use of proximal isovelocity surface area: improved flow estimates using a nonhemispherical model.

OBJECTIVE: To examine the geometry of the proximal isovelocity surface area (PISA) envelope and its associated isotach, and to evaluate the accuracy of two models of calculating volumetric flow by using the PISA technique. DESIGN: A new model for determining isotach geometry from the PISA envelope was developed and tested in an in vitro simulation. SETTING: Echocardiography Laboratory, Hotel Dieu Hospital, Kingston, Ontario. MATERIALS AND METHODS: PISA envelopes were visualized using an in vitro flow simulator with a series of sharp-edged orifices (2.5 to 16 mm diameter) at a range of flow rates (10 to 110 mL/s). INTERVENTIONS: Flow calculations based on the traditional hemispherical geometric assumption for the isotach and the new model were made and compared with measured flow rates. MAIN RESULTS: The hemispherical model systematically and significantly underestimated flow. The nonhemispherical model, which requires measurement of both the height (a) and lateral width (2d) of the PISA envelope, provided improved estimates of flow. CONCLUSIONS: The nonhemispherical model provides a better estimate of flow through an orifice. Flow rate Q can be calculated directly from the size of the PISA envelope and the aliasing velocity (VA) by using the relationship Q = (3.14d2 + 5.97da + 1.37a2)VA or can be read from a nomogram.

Aortic Valve Insufficiency↗
PubMed1999

An appraisal of the Peer Assessment Rating (PAR) Index and a suggested new weighting system.

The PAR Index was developed to measure treatment outcome in orthodontics. Validity was improved by weighting the scores of some components to reflect their relative importance. However, the index still has limitations, principally due to the high weight assigned to overjet. Difficulties also arise from the application of one weighting system to all malocclusions, since occlusal features vary in importance in different classes of malocclusion. The present study examined PAR Index validity using orthodontic consultant assessments as the 'Gold standard' and clinical ranking of occlusal features and statistical modelling to derive a new weighting system, separate for each malocclusion class. Discriminant and regression analyses were used to derive new criteria for measuring treatment outcome. As a result a new and more sensitive method of assessment is suggested which utilizes a combination of point and percentage reductions in PAR scores. This was found to have better correlations with the 'Gold standard' than the PAR nomogram.

Dental Occlusion↗
PubMed1995

Bioimpedance analysis (BIA) in hemodialysis: technical aspects.

Phase-sensitive impedance analysis in association with anthropometric parameters provides adequate body composition estimates in nephropathic subjects, with complex three-compartment modelling as a reference. Extracellular fluid shifts can be detected during ultrafiltration by phase sensitive impedance analyzers. Rough impedance parameters such as Reactance and Phase Angle have been normalized with large series of data collected from reference populations and a bioelectric nomogram, termed Biagram, is proposed to assess the normality between Extracellular and Intracellular spaces, without the need of anthropometric parameters such as Height and Weight.

Body Composition↗
PubMedDate not supplied

The urinary excretion of cocaine and metabolites in humans: a kinetic analysis of published data.

Cocaine plasma levels and urinary excretion data from the literature were subjected to kinetic analysis. The objective was to present the available empirical data in a more useful form and provide a basis for interpretation of cocaine and/or metabolite concentrations in isolated urine samples. Cocaine disposition was modeled as a one-compartment open kinetic system exhibiting linearity within the usually encountered dose range. Model-predicted urine concentrations of cocaine, benzoylecgonine, and ecgonine methyl ester after a 100-mg cocaine dose were compared with literature values to test the validity of the model, and to indicate the use of ratios of concentrations in isolated urine samples to estimate the time since the dose of cocaine. A nomogram relating BZ urine concentrations to cocaine doses was constructed.

Cocaine↗
PubMed1986

The Astrand-Ryhming nomogram revisited.

Relationships among O2 uptake (VO2), heart rate, and work rate during constant-load submaximal cycle ergometry and ramp-forced exercise to exhaustion have been studied in core groups of trained (n = 15) and untrained (n = 10), 20- to 29-yr-old males. A signal aim was to improve on the accuracy of the 1954 Astrand-Ryhming (A-R) nomogram predicting maximum aerobic power from heart rate elevation at submaximum work rates. A new nomogram has been developed based on a linear relationship, established in experimental groups, between VO2 and delta HR, the latter being defined as the elevation of exercise heart rate above that reached during zero-load pedaling at 90 rpm. The delta HR variable used in a nomogram linking it and submaximum VO2 (either derived by calculation from the concomitant steady-state work rate or measured directly from respiratory gas analysis) successfully differentiated maximum aerobic power of trained from untrained subjects in core groups whose different abilities could not otherwise be distinguished by the A-R nomogram itself. In a validation group of trained (n = 5), untrained (n = 5), and moderately trained (n = 4) 20- to 29-yr-old males, the correlation measured between VO2max values and those predicted from the new nomogram was significantly better (r = 0.98) (P less than 0.05) than predictions made from the A-R nomogram (r = 0.80).

Adult↗
PubMed2003

[The urodynamic nomogram in defining various levels of obstruction in patients with benign prostatic enlargement (part I)].

AIM: To determine matching degrees of urodynamic obstruction among available nomograms in patients with confirmed benign prostatic enlargement (BPE). SAMPLE AND METHODOLOGY: 102 patients with confirmed BPE underwent a complete urodynamic investigation (uroflowmetry, cystometry and pressure/flow study). All the measurements were based on definitions adopted by the International Continence Society. Basic urodynamic data were then manually plotted on the Abrams-Griffiths, URA, ICS and Schafer (LinPURR) nomograms; A/G number was calculated as well. RESULTS: Patients were allocated in the three levels of obstruction by Schafer's nomogram; 24 patients (23.5%) had no obstruction, 28 patients (27.4%) had equivocal or non-defined obstruction, while 50 patients (49.1%) had a significant level of obstruction. Spearman rank correlation coefficient has shown a rather uniform correlation of all nomograms. The correlation between Shafer's nomogram and ICS nomogram is the best one, with rho = 0.89 (p < 0.00001), which is followed by correlations between ICS and A/G nomograms with rho = 0.88 (p < 0.00001) and Schafer and A/G with rho = 0.87 (p < 0.00001). URA nomogram and A/G number have a similar correlation of r = 0.87 (p < 0.00001). According to the levels of obstruction, there is a good correlation in the zone of clear obstruction, as well in the zone out of obstruction among available nomograms (chi 2 test, p > 0.05) (URA has not been subject to this process). However, the above nomograms have shown a significant difference in figures relating to the unclassified zone of obstruction (chi 2 test; p < 0.05). CONCLUSION: Despite a very high degree of correlation among individual nomograms, there are considerable differences in figures relating to the unclassified zone of obstruction. This zone should, therefore, be avoided by establishing an optimum model of clear obstruction defining.

Humans↗