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PubMed1995

Spirometric reference values in school children from Dalmatia.

Data on spirometric reference values in children are based on small, selected populations. We performed spirometric testing (forced vital capacity (FVC); forced expiratory volume in one second (FEV1); forced mid-expiratory flow rate (FEF25-75%)) in 2,500 healthy nonsmoking school children (1,250 boys and 1,250 girls) in the region of Dalmatia, Croatia. Significantly higher FVC and FEV1 values were noted in boys. Standing and sitting heights correlated significantly with FVC and FEV1 in boys and girls. Regression equations were derived, utilizing the multiple linear regression analysis, for FVC, FEV1 and FEF25-75% related to five (sex, age, weight, standing and sitting heights) or three (sex, age and standing height) variables. The reference spirometric values in the Dalmatian school boys were in close agreement with Knudson et al., while the values in girls were closest to those of Knudson et al. and Cotes et al. It is suggested that for calculation of ventilatory reference values in boys and girls the age and the standing height should be used.

Adolescent↗

PubMed2026

Multi-locus allelic architecture underlying natural variation in leaf rolling in japonica rice.

Leaf rolling is a key component of rice canopy architecture that affects light interception, microclimate formation, and planting density. The contribution of naturally occurring allelic variation to quantitative variation in leaf rolling within cultivated rice remains poorly understood, while extreme leaf rolling caused by loss-of-function mutations often results in detrimental pleiotropic effects. Herein, we examined how multi-locus allelic variation contributes to natural variation in leaf rolling within japonica rice. Leaf rolling was quantified based on the leaf rolling index (LRI) using a panel of 201 japonica accessions. The phenotype was transformed using the Yeo-Johnson method to reduce strong right skewness and improve the distributional properties of the data, thereby facilitating subsequent regression modeling. Haplotype analyses were performed for previously reported leaf rolling-associated genes and genome-wide association study (GWAS) lead loci, leading to the identification of five loci exhibiting substantial haplotype-dependent phenotypic variation. Phenotypically defined allelic groups represented these loci were subsequently evaluated using multiple linear regression (MLR), with the first two principal components derived from genome-wide SNP data included as covariates to account for population structure. The final MLR model identified four loci (qALR1, OsYABBY1, OsSLL2, and OsSRL10) as the independent contributors to leaf rolling variation, collectively explaining 21% of the variance in the transformed phenotype after accounting for population structure. Model diagnostics and ten-fold cross-validation supported the statistical validity of the framework and indicated stable model performance across validation folds. Analysis of multi-locus allelic combinations showed 13 distinct configurations that clustered into three phenotypically differentiated groups. This reflected the cumulative dosage of high-leaf rolling alleles. Thus, the natural variation in leaf rolling in japonica rice is governed by the additive effects of multiple moderate-impact loci. The multi-locus allelic framework established here provides a statistically sound and biologically interpretable basis for dissecting polygenic canopy traits and practical guidance for developing genetic materials aimed at optimizing rice plant architecture.

cross-validation↗

PubMed1993

Insulin-stimulated glucose utilization and borderline hypertension in young adult blacks.

The purpose of this investigation was to determine whether there is a relation between impaired insulin-stimulated glucose utilization, or insulin resistance, and blood pressure (BP) in a young adult black population. Clinically well, young black men and women, including normotensive (BP < 135/85 mm Hg, n = 23) and borderline hypertensive (BP > or = 135/85 mm Hg, n = 27) individuals, were studied. Each subject had an oral glucose tolerance test (OGTT) and underwent a euglycemic hyperinsulinemic clamp procedure. A two-way analysis of variance demonstrated a significantly greater fasting insulin plasma concentration (P < .02) and sum of insulin levels during the OGTT (P = .04) in the borderline hypertensive compared with normotensive subjects. In both BP groups, women had significantly higher fasting plasma insulin levels than men (P < .02 and P = .009). Body mass index was a significantly covariate of the plasma insulin concentration. Data obtained from the clamp demonstrated significant insulin resistance in borderline hypertensive compared with normotensive subjects (4.69 +/- 0.50 versus 6.57 +/- 0.63 mg/kg per minute, P = .002). A stepwise multiple linear regression analysis demonstrated that there are significant multiple correlations of insulin resistance with body mass index, clamped insulin level, BP group, and systolic BP (multiple R = .7862, P < .001). Application of this analysis to the nonobese sample (n = 33) found significant correlations of insulin resistance with sex, BP group, and systolic BP (multiple R = .6817, P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1975

Surgical resection of tumor bulk in the primary treatment of ovarian carcinoma.

The effect of tumor bulk resection on survival was studied in 102 patients with stages II and III ovarian cancer. A multiple linear regression equation provuded both simultenaous control of multiple confounding variables and an assessment of these variables as independent predictors of survival. The most important factors were the histologic grade of the tumor and the size of the largest residual tumor mass after operation. Survival time was uniformly poor if the diameter of the largest residual tumor mass exceeded 1.5 cm irrespective of total tumor volume (mean=12.7 months, SE=1.6 mo). Survival time was inversely proportional to residual mass size under 1.6 cm, and surgery improved survival relative to reduction in mass size below this limit. Extensive resections of tumor bulk with failure to remove all masses greater than 1.5 cm in diameter did not influence survival. Surgery provides optimum benefit when all gross tumor can be excised safely.

Adult↗

PubMed1995

Burns mortality and hospitalization time--a prospective statistical study of 352 patients in an Asian National Burn Centre.

A prospective study of 352 patients in an Asian National Burn Centre has been used to develop statistical predictive models for mortality and hospitalization time. The patients are largely of Asian origin. Total burn surface area (% TBSA) and presence of respiratory burns are significant independent predictors of mortality in the multiple logistic regression analysis with an accuracy of 98.3 per cent. Age is not a significant predictor of mortality in our patients. Age, % TBSA, full thickness % TBSA and respiratory burns are significant independent predictors of length of stay in hospital with a R2 value of 0.57 in the multiple linear regression analysis. There were 16 deaths, many of whom had developed multiple complications, common causes of which were sepsis, bronchopneumonia, DIVC and multiorgan failure. The final causes of death were septicaemic shock in 10 patients, extensive burns in four patients, ARDS in one patient and bleeding peptic ulcer in one patient. The development of these two mortality and morbidity predictive models is the first step in the evaluation of our results. These models have to be tested against a future set of patients. After confirmation they will aid in patient management, clinical audit, patient and family counselling. They will also serve as baseline standards for evaluation of new therapies, assist us in the allocation of resources and identifying the at-risk population for improvements in therapy.

Adolescent↗

PubMed1985

A free lignocaine index as a guide to unbound drug concentration.

A free lignocaine index was developed on the basis of measurements of plasma lignocaine and its principle binding protein, alpha 1-acid glycoprotein (AAG) in 80 samples from 16 patients admitted to the coronary care unit and given prophylactic lignocaine therapy. The free drug fraction, fu, of lignocaine was determined by equilibrium dialysis and its relationship to AAG and total lignocaine concentration (T) defined by multiple linear regression analysis as l/fu = 1.45 + 0.023 (AAG) -0.129 (T) (multiple r = 0.872, P less than 0.001). This relationship was used to calculate the 'free lignocaine index' as fu X T and compared with the observed value obtained by equilibrium dialysis of 178 samples from 41 separate subjects who received lignocaine after suspected myocardial infarction. There was a highly significant relationship (r = 0.933, n = 178, P less than 0.001) between the observed and predicted values. We conclude that the free drug index may be useful in rapidly assessing the unbound (free) concentration of lignocaine in plasma.

Humans↗

PubMed1978

Skin colorimetry in Belize. I. Conversion formulae.

Comparisons between skin colorimetry reports have been hampered by the common use of two different types of portable reflectometers, which sample reflectances at different wavelengths. In an attempt to provide direct comparability between the two machines, multiple linear regression equations were derived from reflectance spectrophotometry readings on 308 Black Caribs and 175 Creoles in Belize, Central America, using both machines. Cross validation tests show the coefficients presented are applicable to independent data sets and generally applicable to other heavily pigmented populations. Comparisons with previously published conversion formulae, which were from very small samples using simple linear regression, show a definite improvement in predictive accuracy when using multiple regression equations based on a large sample.

Belize↗

PubMed1989

Determinants of maximum exercise capacity in patients with chronic airflow obstruction.

Patients with chronic airflow obstruction (CAO) often develop impairment of respiratory muscle function. We hypothesized that inspiratory muscle strength, as assessed by resting, peak inspiratory pressure (PIP) may be an important determinant of maximum exercise capacity in patients with CAO. Twenty ambulatory male patients (mean age, 56 +/- 3 years [+/- SE]) with CAO (FEV1, 1.72 +/- 0.21 L) comprised the studied population. Oxygen consumption at incremental cycle ergometry to tolerance (VO2max, 1.80 +/- 0.20 L/min) served as the dependent variable for regression vs measures of resting pulmonary function. Significant correlations with VO2max included power output in watts (r = 0.951), VEmax (r = 0.858), Dsb (r = 0.841), PIP (r = 0.816), age (r = -0.809), FEV1 (r = 0.763), and FVC (r = 0.663). The FEV1, Dsb, and PIP each entered into a multiple linear regression relationship describing VO2max. Also, when paired with VEmax as independent variables in multiple regression, PIP and Dsb each improved description of VO2max over VEmax alone (p less than 0.05), whereas FEV1 and FVC did not (p greater than 0.05). We conclude that factors other than ventilatory capacity also have a quantitative effect on VO2max and that PIP constitutes a determinant of maximum exercise capacity in patients with CAO.

Exercise Test↗

PubMed1993

A mathematical model for cell killing by heat applied to a C3H mammary carcinoma in vivo.

Jung (1986) has proposed a mathematical model for cell killing by hyperthermia which assumes that heat killing involves two steps: the production (p) of non-lethal lesions at random and a subsequent conversion (c) into lethal lesions. The p & c model has been shown to predict the survival of CHO cells heated in vitro even when complicated biological phenomena such as thermotolerance and step-down heating (SDH) are involved (Jung 1986, 1991). In the present study the objective was to test the p & c model's ability to describe the effect of single heating and SDH in an experimental tumour in vivo. The endpoint was tumour growth delay (GD). The doubling times (DT) for untreated and heated tumours were similar, and the surviving fraction (SF) could therefore be estimated using: SF = -in(2).GD/DT. SF was fitted to the model by non-linear regression. The p & c model adequately described the GD obtained by SDH (39-44.5 degrees C) and single heating above 42.5 degrees C. Multiple linear regression showed that the residuals for single heating and SDH were independent of both heating time and temperature. However, the residuals for single heating (41-44.5 degrees C) were significantly correlated to heating time when analysed separately. The GD obtained by the use of extended single heating times at or below 42.5 degrees C was therefore overestimated by the model. Development of chronic thermotolerance during heating may account for the observed divergence. The Arrhenius plots for both p and c were log-linear with activation energies of 678 and 311 kJ/mol, respectively. Jung (1986) has previously reported similar p and c activation energies above 42.5 degrees C for CHO cells in vitro.

Animals↗

PubMed1993

Epidemiology of cardiovascular disease risk factors in Catalonia (Spain).

Cardiovascular disease is one of the most important public health problems in developed countries. We have studied the epidemiology of the following cardiovascular disease risk factors in a random sample (n = 704) of the adult population of Catalonia (Spain): hypercholesterolemia (> or = 6.1) mmol/l or 240 mg/dl), hypertension (SBP > or = 160 and/or DBP > or = 95 mmHg), low HDL-cholesterol concentrations (< 0.9 mmol/l or 35 mg/dl), hypertriglyceridemia (> 2.8 mmol/l or 250 mg/dl), obesity (BMI > 30), smoking and history of diabetes and coronary heart disease. Two percent of participants had hypertriglyceridemia, 3% had a history of coronary heart disease, 4% a history of diabetes, 6% low HDL-cholesterol concentrations, 12% were obese, 20% had hypertension, 24% had hypercholesterolemia and 36% were smokers. 58% of hypertensive individuals had been previously detected, 46% were currently on treatment, and 21% had their blood pressure controlled (SBP < 160 and DBP < 95 mmHg). Correlation and multiple regression analyses were used to investigate the association between cardiovascular risk factors. Multiple linear regression analysis showed independent correlations between risk factors. Prevalence of hypercholesterolemia, obesity and diabetes was higher and prevalence of smoking was lower in hypertensives than normotensives. The odds ratio was 3.68 (95% CI = 2.07-6.54) for hypercholesterolemia, 3.26 (95% CI = 1.52-7.02) for obesity, 3.81 (95% CI = 1.09-7.02) for diabetes and 0.40 (95% CI = 0.22-0.70) for smoking. The adjusted odds ratio was statistically significant for hypercholesterolemia (OR = 2.74, 95% CI = 1.01-3.75). The prevalence of cardiovascular risk factors was similar to that observed in other Mediterranean communities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1988

Hemorrhagic complications associated with the use of intravenous tissue plasminogen activator in treatment of acute myocardial infarction.

PURPOSE: Little attention has been paid to the importance of clinical factors associated with bleeding complications caused by the use of thrombolytic agents. The goal of our study was to examine clinical and hematologic factors associated with an increased risk of bleeding in a prospectively observed population that received intravenous tissue plasminogen activator for acute myocardial infarction. PATIENTS AND METHODS: Bleeding complications were evaluated in 386 consecutive patients treated with 150 mg of tissue plasminogen activator over six to eight hours for acute myocardial infarction. All patients also underwent immediate cardiac catheterization. RESULTS: Quantitation of blood loss during the patients' hospital stay included a median drop in hematocrit of 11.4 points, a median nadir hematocrit of 31.2, a 14 percent rate of significant clinically evident bleeding, and a 31 percent rate of transfusion of two or more units of blood. All of these parameters were much more severe in patients treated with coronary artery bypass surgery. Access site hematoma was the most common source of bleeding (45 percent of patients), whereas 8 percent had gastrointestinal bleeding, two patients had retroperitoneal bleeding, and two patients had intracranial bleeding. The median nadir fibrinogen was 1.3 g/liter. Multiple linear regression models were used to investigate the relationship between clinical variables, including multiple hematologic measurements, and measures of the amount of blood loss. The use of coronary artery bypass grafting was the variable most closely associated with hemorrhage. Other invasive procedures (angioplasty and intra-aortic balloon pumping) were also associated with increased bleeding. Among the patient descriptors examined, lighter weight, older age, female sex, and history of hypertension were associated with greater blood loss. Of laboratory coagulation parameters, only nadir fibrinogen levels were significantly associated with more bleeding. CONCLUSION: Careful clinical evaluation may improve assessment of the risk/benefit ratio of thrombolytic therapy.

Age Factors↗

PubMed1991

Prediction of gas chromatographic relative retention times of anabolic steroids.

The prediction of gas chromatographic relative retention times (RRTs) of anabolic steroids, used in the doping control of athletes, was performed by a quantitative structure-retention relationship (QSRR) and multiple linear regression analysis study. A nine-variable model was generated with a multiple correlation coefficient R = 0.991 and relative standard error of less than 3%. Preliminary results indicated that the application of the model, especially in the prediction of RRTs of metabolites of the anabolic steroids, will be helpful.

Anabolic Agents↗

PubMedDate not supplied

Age and height as predictors of peak expiratory flow rate in Indian girls.

Peak expiratory flow rate (PEF) was measured on 175 healthy Indian girls in the age range 8-18 years with the help of Wright's Peak Flow Meter. PEF was recorded in the post absorptive phase at least 1 h after breakfast. The subjects rested for 0.5 h before the test procedure and tests were carried out between 1000-11000 hrs to avoid diurnal changes. The highest of three recordings was noted as the subject's PEF. PEF, age, height and body weight were correlated with each other and an intercorrelation matrix between these variables has been designed. It was observed, after performing multivariate regression analysis, that age and height are significant predictors of PEF. A multiple linear regression equation and a nomogram have been constructed for predicting PEF from age and height in young healthy Indian girls.

Adolescent↗

PubMed1992

Case-mix groups for VA hospital-based home care.

The purpose of this study is to group hospital-based home care (HBHC) patients homogeneously by their characteristics with respect to cost of care to develop alternative case mix methods for management and reimbursement (allocation) purposes. Six Veterans Affairs (VA) HBHC programs in Fiscal Year (FY) 1986 that maximized patient, program, and regional variation were selected, all of which agreed to participate. All HBHC patients active in each program on October 1, 1987, in addition to all new admissions through September 30, 1988 (FY88), comprised the sample of 874 unique patients. Statistical methods include the use of classification and regression trees (CART software: Statistical Software; Lafayette, CA), analysis of variance, and multiple linear regression techniques. The resulting algorithm is a three-factor model that explains 20% of the cost variance (R2 = 20%, with a cross validation R2 of 12%). Similar classifications such as the RUG-II, which is utilized for VA nursing home and intermediate care, the VA outpatient resource allocation model, and the RUG-HHC, utilized in some states for reimbursing home health care in the private sector, explained less of the cost variance and, therefore, are less adequate for VA home care resource allocation.

Aftercare↗

PubMedDate not supplied

Lung volumes in healthy nonsmoking adults.

Total lung capacity (TLC), functional residual capacity, residual volume, and corresponding 95% confidence intervals were measured in 245 healthy nonsmoking person (122 women, 123 men) using a single-breath helium technique. Prediction equations for lung volumes were generated by multiple linear regression. The resultant equations are similar to previously published equations using multiple-breath gas equilibration techniques. Measured 95% confidence intervals can be closely approximated by using two times the standard error of the estimate for each equation, but cannot be approximated by using +/- 20% of the predicted value. Radiographic TLC was not significantly different from the helium dilution TLC.

Adult↗

PubMed1994

Dehydroepiandrosterone sulphate and bone mineral density.

Several series of data suggest that alterations in adrenal androgen output might be a contributing factor to changes in bone mass. To study the possible relationship between bone density and serum levels of dehydroepiandrosterone sulphate (DHEAS) we investigated 105 women (aged 45-69 years; 76 postmenopausal, 29 perimenopausal). The patients were divided into two groups according to the bone mineral density (BMD) measurement (normal density n = 50, low density n = 55). BMD was measured by dual-energy X-ray absorptiometry of the lumbar spine and femoral neck. Bone mineral content (BMC) of the radius midshaft was measured by single photon absorptiometry. Serum DHEAS level was significantly lower in the 'low density' group than in the 'normal' one (1.91 +/- 1.04 v 4.77 +/- 2.03 mumol/l, p < 0.001). The serum DHEAS level decreased significantly with age in both groups (r = 0.43, p < 0.001 in the 'normal' group; r = 0.35, p < 0.01 in the 'low density' group). Unlike the slopes, the positions of the regression lines differed significantly (difference 2.85 mumol/l, p < 0.001). Correcting for age by multiple linear regression we established a significant positive relationship between DHEAS and BMD of the lumbar spine and femoral neck, and BMC of radius midshaft as well. Since there was no significant difference between the two groups regarding oestrogens, we suggest that DHEAS may have a non-oestrogenic effect on bone. The odds ratio of a subject with a low (< 3.3 mumol/l) serum DHEAS level having low BMD was 40 (confidence interval 13-126).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1987

Pharmacodynamics of 3-hydroxyquinidine alone and in combination with quinidine in healthy persons.

The relation between serum concentration of 3-hydroxyquinidine (3-OHQ), a major metabolite of quinidine in humans, and the pharmacologic effect alone and in combination with the parent drug was studied. The heart rate-corrected, computer-averaged QT interval (QTc) was used as the pharmacologic endpoint. In a randomized, double-blind study, 5 healthy subjects received, on 3 separate days 1 week apart, either (1) 300 to 400 mg 3-OHQ orally or (2) 150 mg quinidine base intravenously or (3) a combination in the same doses. Blood samples and electrocardiographic recordings were obtained over the following 10 hours. Serum concentrations of 3-OHQ and quinidine were determined by high-pressure liquid chromatography and the free fraction by ultrafiltration. Peak concentrations of 3-OHQ varied between 1,362 and 3,480 ng/ml after oral 3-OHQ ingestion, but were negligible after intravenous quinidine infusion. The free fraction was 49% +/- 4.8 (mean +/- standard deviation) for 3-OHQ and 20% +/- 4.3 for quinidine. In all 5 subjects a statistically significant correlation was found between serum concentration and QTc prolongation for both quinidine and 3-OHQ (largest p value less than 0.025). The mean slope of the regression line was 0.0184 +/- 0.0128 for 3-OHQ and 0.0297 +/- 0.0111 for quinidine. Multiple linear regression revealed in each subject a significant additive effect of 3-OHQ when administered together with quinidine (largest p value less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Prediction of gas chromatographic relative retention times of stimulants and narcotics.

The ADAPT software system was used to create models for the prediction of gas chromatographic relative retention times (RRTs) of stimulants and narcotics that are analyzed in doping control of athletes. The two main methods that were followed for building the models were the quantitative structure-retention relationship (QSRR) and multiple linear regression analysis. The main proposed model for the entire data set had a multiple correlation coefficient R = 0.991 and standard error s = 0.046 or approximately 4.5%. Because of the relatively high standard error of the main model, a second model was built on a subset of compounds with R = 0.982 and s = 0.027 or approximately 2.5%.

Central Nervous System Stimulants↗