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PubMed1998

Comparison of anion gap and strong ion gap as predictors of unmeasured strong ion concentration in plasma and serum from horses.

OBJECTIVE: To compare the accuracy of anion gap (AG) and strong ion gap (SIG) for predicting unmeasured strong ion concentration in plasma and serum from horses. ANIMALS: 6 well-trained Standardbred horses undergoing high-intensity exercise (experimental study) and 78 horses and ponies that underwent i.v. administration of lactic acid or endotoxin, and endurance, submaximal, or high-intensity exercise. PROCEDURE: Anion gap was calculated as AG = (Na+ + K+) - (Cl- + HCO3-), and SIG was calculated, using the simplified strong ion model, whereby SIG (mEq/L) = 2.24 x total protein (g/dl)/(1 + 10(6.65-pH)) - AG. The relation between AG or SIG and plasma lactate concentration was evaluated, using linear regression analysis. RESULTS: Linear relations between plasma lactate concentration and AG and SIG were strong for the experimental study (r2 = 0.960 and 0.966, respectively) and the published studies (r2 = 0.914 and 0.925, respectively). The following relations were derived: AG = 1.00 x plasma lactate + 10.5; SIG = 0.99 x plasma lactate + 2.8. An AG > 15 mEq/L indicated an increased unmeasured anion concentration, whereas a SIG < -2 mEq/L indicated an increased unmeasured strong anion concentration. CONCLUSIONS AND CLINICAL RELEVANCE: Anion gap and SIG can be used to predict plasma lactate concentration in horses. AG is accurate and clinically useful for estimating unmeasured strong ion concentration in horses with total protein concentrations within or slightly outside reference range, whereas SIG is more accurate in horses with markedly abnormal total protein concentrations and those of various ages and with various concentrations of albumin, globulin, and phosphate.

Acid-Base Equilibrium↗
PubMed2004

Retained placenta in Friesian mares: incidence, and potential risk factors with special emphasis on gestational length.

During the foaling seasons of 1999 and 2000, the incidence of retained placenta in 495 normal parturitions of 436 Friesian brood mares was studied. Retained placenta was defined as a failure to expel all fetal membranes within 3 h of the delivery of the foal. Furthermore, the sex of the foal, month of breeding, sire and dam's sire, age of the mare, and time of day of foaling, were studied as factors that might be associated with retained placenta in Friesian mares after normal foalings, and with gestational length. The analysis was carried out using marginal logistic regression, and mixed linear regression, respectively. The incidence of retained placenta was 54%. Mean length of gestation was 331.6 days. Colts were carried 1.5 days longer than fillies. Mares bred in July-September had a 4-day shorter gestation period (329 days) than mares bred earlier in the year. There was a mare, sire, and dam's sire effect on gestational length, and a mare effect on the occurrence of retained placenta. Mares foaling at 4 and >17 years of age, tended to have a lower incidence of retained placenta than mares foaling at 5-17 years of age. No association was found between the occurrence of retained placenta, and gestational length, sex of the foal, month of breeding, dam's sire, and time of day of foaling. It was concluded that the observed high incidence of retained placenta indicates that the Friesian breed of horses has a higher risk for retained placenta than other breeds of horses.

Animals↗
PubMed2002

Association of the blood/air partition coefficient of 1,3-butadiene with blood lipids and albumin.

Pulmonary gas uptake is a function of the blood solubility of a vapor, indicated by the blood/air partition coefficient. We hypothesized that blood lipid compositions are associated with the blood/air partition coefficients of lipophilic toxic vapors such as 1,3-butadiene. Our goal was to investigate cross-sectional and longitudinal relationships of blood triglycerides, total cholesterol, and albumin to the blood/air partition coefficient of butadiene. We collected blood samples from 24 subjects at three time points: a fasting baseline and 2 and 4 hr after drinking a standardized high-fat milk shake (107 g fat, 80 g sugar, and 27 g protein). The blood/air partition coefficient was determined using the closed vial-equilibrium technique. Triglycerides and total cholesterol were analyzed by an enzymatic method, and albumin was analyzed with an immunoassay technique. We used multiple linear regression and general linear models to examine the cross-sectional and longitudinal relationship, respectively. The results showed that the blood/air partition coefficient of butadiene was cross-sectionally associated only with triglycerides at baseline, and longitudinally related to baseline triglycerides, total cholesterol, and the change in triglycerides over time. The blood/air partition coefficient of butadiene increased, on average, by approximately 20% and up to 40% for subjects with borderline higher triglyceride levels after ingestion of a standardized milk shake. In addition, a time factor beyond lipids was also significant in predicting the blood/air partition coefficient of butadiene. This may represent the effects of other unmeasured parameters related to time or time of day on the blood/air partition coefficient of butadiene. Because the blood/air partition coefficient is a major determinant of gas uptake, ingestion of a high fat meal before this type of exposure may significantly increase an individual's absorbed dose, possibly increasing the risk of adverse effects.

Adult↗
PubMed2001

Antibiotic prescribing in acute infections of the nose or sinuses: a matter of personal habit?

BACKGROUND: A proper understanding of how and why GPs prescribe antibiotics in general practice is essential for the design of strategies aimed at making prescribing more rational. OBJECTIVE: The intention of this study is to contribute to such understanding by investigating which elements are important in the GP's decision to prescribe antibiotics for patients with acute infectious complaints of the nose and/or sinuses. METHODS: During their training in general practice, students observed the following elements while attending encounters between their trainer-GP and patients with a runny nose, blocked nose or cough: patient characteristics, contact characteristics, signs and symptoms, diagnosis and prescriptions. Information on practice characteristics and characteristics of the trainer-GP were collected. Data were analysed using multiple logistic regression and multiple linear regression. RESULTS: A total of 722 cases were analysed with the following results: the best independent predictor of an antibiotic prescription is the individual antibiotic prescribing rate (IAPR), which expresses the personal habit of the GP in prescribing antibiotics [adjusted odds ratio (OR) 5.27, 95% confidence interval (CI) 3.22-8.62]. Others are the diagnostic labels "sinusitis" (adjusted OR 2.80, 95% CI 1.2-6.49) and "flu-like syndrome" (adjusted OR 0.08, 95% CI 0.01-0.45), and the sign "sinus tenderness" (adjusted OR 4.37, CI 2.15-8.89). The antibiotic prescribing behaviour intensifies with an increasing tendency to prescribe medication in general (beta = 0.46, P: < 0.00) and with an increasing defensive attitude (beta = 0.22, P: < 0.05). CONCLUSIONS: Whether or not a patient with an acute infection of the nose and/or sinuses will be handed an antibiotic prescription seems to depend more on the attending doctor's prescribing behaviour than on the clinical picture. Further qualitative research into attitudes which may be related to a high tendency to prescribe antibiotics consequently is of the utmost importance.

Acute Disease↗
PubMed2006

The association of mood with quality of life ratings in epilepsy.

OBJECTIVE: To determine the relative contributions of psychological (mood and anxiety), social, and seizure-related variables to quality of life (QOL) scores in epilepsy. METHODS: Outpatients (n = 435) with epilepsy completed the Quality of Life in Epilepsy 31 Inventory (QOLIE-31), Beck Depression Inventory II (BDI-II), Beck Anxiety Inventory, and a social survey. Stepwise linear regression and general linear model analyses determined the set of best predictors and the most unique predictors of composite QOLIE-31 score and subscale scores. RESULTS: A three-variable model accounted for 56% of the variance for the composite QOLIE-31 score. The BDI-II was the strongest (often by several multiples in terms of variance explained) and most consistent predictor of the composite and QOLIE subscales in both types of analytic approaches. In no case did BDI-II significantly interact with the other variables, suggesting that its effect on QOL was direct and not mediated by other factors. Throughout the results, depression had an inverse relation to scores, i.e., lower levels of depression correlated with high QOL scores. Separate correlational analyses showed that poor seizure control was associated with increased numbers of depressive symptoms. DISCUSSION: Quality of Life in Epilepsy (QOLIE) scores, reflecting both general and specific aspects of quality of life, are strongly influenced by mood state, such as depression. Factors such as seizure control exert a more limited effect on the QOLIE. Health-related quality of life measures are needed in which mood does not play such a dominant role.

Adult↗
PubMed2002

Relationship between rate of change in acid exposure along the esophagus and length of Barrett's epithelium.

OBJECTIVE: Gastroesophageal reflux disease (GERD) plays a major role in the development of Barrett's esophagus. Recently, we demonstrated that duration of esophageal acid exposure in the distal esophagus correlates with the length of Barrett's mucosa. The aim of this study was to determine whether there is a relationship between the rate of the change in acid exposure along the esophagus and the length of Barrett's esophagus. METHODS: A total of 17 patients (16 men and one woman; mean age 66 +/- 15 yr, range 41-83 yr) with varying lengths of biopsy-proven Barrett's esophagus were recruited prospectively into the study. Ambulatory 24-h esophageal pH monitoring was performed using a commercially available pH probe with four sensors located 5 cm apart. For each patient, a least squares regression line of the fraction of the study that the pH was <4 against the height of the sensor above the lower esophageal sphincter was fit. The slope of the regression line was used to represent the rate of change in acid exposure. Linear regression analysis was conducted to analyze the relationship between the rate of change in acid exposure and the length of Barrett's mucosa. RESULTS: The mean Barrett's length was 5 +/- 3 cm (range 1-11 cm). Linear regression demonstrated a statistically significant relationship between the rate of change in acid exposure and the length of Barrett's esophagus for the 24-h duration of the study, as well as for the fraction of the study that patients were in the upright position (p = 0.0096 and 0.0076, respectively). For the supine position, the relationship did not reach statistical significance (p = 0.095). CONCLUSIONS: We demonstrated a significant relationship between the rate of change in acid exposure and the length of Barrett's mucosa. Thus, as the rate at which recorded acid exposure values increases from the proximal to distal esophagus, the length of Barrett's esophagus significantly increases (for percent total time and upright position).

Adult↗
PubMed2004

Prediction of aqueous solubility based on large datasets using several QSPR models utilizing topological structure representation.

Several QSPR models were developed for predicting intrinsic aqueous solubility, S(o). A data set of 5,964 neutral compounds was sub-divided into two classes, aromatic and non-aromatic compounds. Three models were created with different methods on both data sets: two regression models (multiple linear regression and partial least squares) and an artificial neural network model. These models were based on 3343 aromatic and 1674 non-aromatic compounds for training sets; 938 compounds were used in external validation testing. The range in -log S(o) is -1.6 to 10. Topological structure descriptors were used with all models. A genetic algorithm was used for descriptor selection for regression models. For the artificial neural network (ANN) model, descriptor selection was done with a backward elimination process. All models performed well with r2 values ranging 0.72 to 0.84 in external validation testing. The mean absolute errors in validation ranged from 0.44 to 0.80 for the classes of compounds for all the models. These statistical results indicate a sound ANN model. Furthermore, in a comparison with eight other available models, based on predictions using a validation test set (442 compounds), the artificial neural network model presented in this work (CSLogWS) was clearly superior based on both the mean absolute error and the percentage of residuals less than one log unit. In the ANN model both E-State and hydrogen E-State descriptors were found to be important.

Databases, Factual↗
PubMed2003

Prediction of human pharmacokinetics from animal data and molecular structural parameters using multivariate regression analysis: oral clearance.

The aim of the study reported here was to develop a regression equation for predicting oral clearance of various kinds of drugs in humans using experimental data from rats and dogs and molecular structural parameters. The data concerning the oral clearance of 87 drugs from rats, dogs, and humans were obtained from literature. The compounds have various structures, pharmacological activities, and pharmacokinetic characteristics. In addition, the molecular weight, calculated partition coefficient (c log P), and the number of hydrogen bond acceptors were used as possible descriptors related to oral clearance in human. Multivariate regression analyses, multiple linear regression analysis, and the partial least squares (PLS) method were used to predict oral clearance in human, and the predictive performances of these techniques were compared by allometric approaches, which have been used in interspecies scaling. Interaction terms were also introduced into the regression analysis to evaluate the nonlinear relationship. For the data set used in this study, the PLS model with the tertiary term descriptors gave the best predictive performance, and the value of the squared cross-validated correlation coefficient (q(2)) was 0.694. This PLS model, using animal oral clearance data for only two species and easily calculated molecular structural parameters, can generally predict oral clearance in human better than the allometric approaches. In addition, the molecular structural parameters and the interaction term descriptors were useful for predicting oral clearance in human by PLS. Another advantage of this PLS model is that it can be applied to drugs with various characteristics.

Administration, Oral↗
PubMed1980

Distribution of ethanol between blood and dorsal subcutaneous air of the rat and the feasibility of using this distribution coefficient to estimate blood ethanol.

Equilibration of ethanol between dorsal subcutaneous air and blood is rapid, a steady state being already present in 60 seconds after air injection in the rat. The mean in vivo partition coefficient (blood/air) is 2,875, the linear regression coefficient having a standard error of 112, the high F value of this regression indicating the linearity and reliability of the estimates of calculated blood ethanol; the variance arises mainly from temperature variance of the air bleb. Although the concentration of alcohol in the blood must remain the standard of comparison, the production of the air bleb and its subsequent serial sampling is a virtually noninvasive technique which yields an almost immediate result at a sensitivity and specificity greater than that from the usual enzymatic determination of ethanol in blood.

Air↗
PubMed1997

Relationship of critical velocity to marathon running performance.

The purpose of this investigation was to evaluate the critical velocity (CV) test for prediction of marathon running performance. Twelve subjects [mean age (SD) = 29 (4) years; mean body mass = 63 (13) kg] were tested for CV and completed the 1994 New York City Marathon. The CV (m.s-1) was determined from times to exhaustion at four treadmill running velocities. In addition, peak oxygen consumption (VO2peak; ml.kg-1.min-1) and ventilatory threshold (Thvent) were determined from an incremental treadmill test. The Thvent was calculated using bi-segmental linear regression and was expressed as the velocity (m.s-1) at Thvent. Separate simple linear regression analyses showed that marathon time [MT; mean (SD) = 231.9 (27.4) min] correlated more highly with CV [MT = 445.3 - 50.3 (CV); r2 = 0.76, SEE = 14.1 min] than either VO2peak [MT = 390.7-2.7 (VO2peak); r2 = 0.51, SEE = 20.1 min] or Thvent [MT = 353.5 - 30.1 (Thvent) r2 = 0.28, SEE = 27.4 min]. A stepwise regression analysis resulted in CV (entered first) and Thvent being included in the prediction equation [MT = 443.5-78.9 (CV) + 34.3 (Thvent). R2 = 0.88, SEE = 10.7 min], while VO2peak was not included. These preliminary data indicate that the CV test may be an attractive field test for assessing marathon performance capabilities.

Adult↗
PubMed2006

True prediction of lowest observed adverse effect levels.

A database of structurally heterogeneous chemical structures with their experimental values of Lowest Observed Adverse Effect Levels (LOAELs) was modeled using graph theoretical descriptors. Variable selection for multiple linear regression (MLR) and linear discriminant analysis (LDA) was accomplished by the Internal Test Set (ITS) method in order to achieve true predicted LOAEL values. The results obtained can be considered good if we take in count the structural diversity of the training set.

Algorithms↗
PubMed2005

The bootstrap: a technique for data-driven statistics. Using computer-intensive analyses to explore experimental data.

BACKGROUND: The concept of resampling data--more commonly referred to as bootstrapping--has been in use for more than three decades. Bootstrapping has considerable theoretical advantages when it is applied to non-Gaussian data. Most of the published literature is concerned with the mathematical aspects of the bootstrap but increasingly this technique is being utilized in medical and other fields. METHODS: I reviewed the published literature following a 1994 publication assessing the transfer of technology, including the bootstrap, to the biomedical literature. RESULTS: In the ten-year period following that 1994 paper there were 1679 published references to the technique in Medline. In that same time period the following citations were found in the four major medical journals-British Medical Journal (48), JAMA (51), Lancet (52) and the New England Journal of Medicine (45). CONTENT: I introduce the basic theory of the bootstrap, the jackknife, and permutation tests. The bootstrap is used to estimate the accuracy of an estimator such as the standard error, a confidence interval, or the bias of an estimator. The technique may be useful for analysing smallish expensive-to-collect data sets where prior information is sparse, distributional assumptions are unclear, and where further data may be difficult to acquire. Some of the elementary uses of bootstrapping are illustrated by considering the calculation of confidence intervals such as for reference ranges or for experimental data findings, hypothesis testing such as comparing experimental findings, linear regression, and correlation when studying association and prediction of variables, non-linear regression such as used in immunoassay techniques, and ROC curve processing. CONCLUSIONS: These techniques can supplement current nonparametric statistical methods and should be included, where appropriate, in the armamentarium of data processing methodologies.

Computers↗
PubMed2005

Polymerization shrinkage and contraction stress of dental resin composites.

OBJECTIVE: The aim of this study was to evaluate the shrinkage, contraction stress, tensile modulus, and the flow factor of 17 commercially available dental resin composites. METHOD: The volumetric shrinkage measurements were performed by mercury dilatometry, and the contraction stress and tensile modulus were determined by means of stress-strain analysis. The statistical analysis was conducted by ANOVA and Tukey's post hoc test, and linear regression. RESULTS: Strong linear correlation for most resin composites were found for (i) contraction stress and shrinkage (ii) contraction stress and tensile modulus, and (iii) shrinkage and tensile modules. For most of the materials the unpolymerized resin content determines the amount of shrinkage, contraction stress and tensile modules. The pre-polymerized clusters in Heliomolar results in improved shrinkage/contraction stress properties. The shrinkage/contraction stress for Filtek Z100, Aelite Flo, and Flow-it was too high for the amount of resin in the resin composite. This was rationalized by high polymerization rates, a flow factor, and the nature of the resin. SIGNIFICANCE: High shrinkage and/or high contraction stress may lead to failure of the bond between the resin composites and the tooth structure. This study shows that the unpolymerized resin content determines the amount of shrinkage, contraction stress and tensile modules. Therefore, using pre-polymerized clusters will improve shrinkage/contraction stress properties, as was shown in Heliomolar, while high polymerization rates, and low flow factors have a deteriorative effect on the shrinkage/contraction stress properties.

Acrylic Resins↗
PubMed2004

Impact of pleural effusion pH on the efficacy of thoracoscopic mechanical pleurodesis in patients with breast carcinoma.

OBJECTIVE: A prospective randomised study was conducted to compare the efficacy of treating malignant pleural effusions (MPE) in patients with breast carcinoma by thoracoscopic mechanical pleurodesis (TMP) as a new palliative treatment and talc pleurodesis (TP) at various pleural fluid pH levels and to determine whether at low pH values, when the success of TP is reduced, TMP is more successful. METHODS: 87 female patients with breast carcinoma and a resulting MPE resistant to systemic therapy were divided into two groups: TMP and TP groups. In the TMP group 24 patients with pH levels above 7.3 and 21 patients with pH levels below 7.3 underwent thoracoscopic parietal and visceral pleural abrasion utilising general anaesthesia. In the TP group, 22 patients with pH levels above 7.3 and 20 patients with pH levels below 7.3 were administered 5 g of sterile talc, dissolved in 100 ml of physiological solution, via a chest tube, utilising local anaesthesia. Postoperative follow-up was performed to determine a possible recurrence of MPE with periodic radiographs, the duration of chest tube drainage and hospitalisation, occurrence of complications, and perioperative mortality. The following was used for statistical analysis: t-test for odd samples, chi2 test, logistic regression, and multiple linear regression. RESULTS: TMP and TP were equally successful (92 and 91%) in patients with pH levels above 7.3. Differences occurred in patients with pH below 7.3 (81 and 55%) (P = 0.07). The lowest pH value at which TMP proved successful was 7.06, while for TP this value was 7.25. In TMP group the average duration of chest tube drainage amounted to 3.8 days and hospitalisation to 5.5 days, while in TP group it was 5.6 and 7.5 days, respectively. Differences were statistically significant (P < 0.05). 16% of easily treatable complications and no case of perioperative mortality were identified in TMP group, while 26% of complications and four cases of perioperative mortality were noted in TP group. CONCLUSIONS: TMP is a safe palliative treatment for MPE in breast carcinoma, with a minimal number of complications and a short hospital stay; it is more successful than TP in patients with pH of MPE below 7.3.

Breast Neoplasms↗
PubMed2005

Assessing contamination paths of the German adult population with gold and platinum. The German Environmental Survey 1998 (GerES III).

BACKGROUND: Even though increased environmental platinum levels were found since the introduction of automobile catalytic converters, little is known about the pathways of corporal uptake and the bioavailability of platinum in the general adult population. The aim of this study is to identify and quantify the main exposure pathways of gold and platinum in the general adult population. METHODS: The German Environmental Survey 1998 (GerES III) collected population-based data on the corporal gold and platinum burden from a large sample of 1080 persons, 18-69 years of age. Urinary metal concentration was analysed by SF-ICP-MS. Exposure data were assessed by standardized questionnaires. Data were log transformed and analysed using multiple linear regression analysis with respect to exposure variables. RESULTS: The R2 of the linear regression model of urinary gold and platinum (ng/l) burden is 0.349 and 0.235, respectively. In both models, the number of teeth with noble metal dental alloy restorations (NMDAR) is the most important exposure pathway. One versus no tooth with NMDAR is associated with an increase of 23.7% in urinary gold and 35.6% in platinum concentration. Chewing gum intensifies the release of gold and platinum from NMDAR: every additional day per week when gum is chewed is associated with an increased gold (5.6%) and platinum (6.9%) burden. Furthermore, elevated urinary gold and platinum concentrations were found for higher creatinine concentrations, more frequent coffee consumption and for people from the upper social class. Gold burden is also increased in people with arthritis. Platinum burden is also increased in people living in western or northern Germany. Traffic-related variables had no significant effect on platinum burden.

Adult↗
PubMed2026

Microbial Interactions with Protein Intake and Preterm Infant Body Composition: Secondary Analysis of a Randomized Trial.

BACKGROUND: Enteral protein supplementation improves preterm infant growth and may impact body composition and the gut microbiota. OBJECTIVES: This study aimed to identify the effects of additional enteral protein supplementation on the gut microbiota and microbial and clinical drivers of body composition. METHODS: Secondary analysis of a masked randomized trial of additional enteral protein vs. standard fortification in preterm infants born at 25 to 28 weeks of gestation (NCT03586102) was conducted. Stool samples at weeks 4 and 8 underwent 16S rRNA sequencing; functional potential was predicted by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt2). Body composition was measured by air-displacement plethysmography at 36 wk postmenstrual age (PMA). Least absolute shrinkage and selection operator (LASSO) regression with multivariable linear regression identified body composition predictors. RESULTS: Among 46 infants, gestational age (P = 0.16) and sex (P = 0.55) did not differ between groups. The protein group had higher week 4 Shannon diversity than standard fortification (median 1.2 vs. 0.87, P = 0.049). Week 4 Shannon diversity was positively correlated with fat-free mass z-score at 36 wk PMA (r2 = 0.34, P = 0.02). Adjusting for covariates, the protein group had higher Peptoniphilus (&#x3b2; = 1.6, Padj = 0.10) and lower Vibrio centered log-ratio abundance (&#x3b2; = -0.98, Padj = 0.10); 62 predicted metabolic pathways were lower in the protein group (false discovery rate < 0.20). In combined LASSO models, Bacillus abundance at week 4 was the strongest predictor of fat-free mass z-score (&#x3b2; = -0.17, P < 0.001; R2 = 0.80) and fat mass z-score (&#x3b2; = -0.31, P < 0.001; R2 = 0.66). CONCLUSIONS: Additional protein supplementation is associated with fat-free mass z-score and alterations to the gut microbiota. Clinical variables and microbial variables are key predictors of body composition, suggesting that nutrition, clinical factors, and the gut microbiota jointly contribute to body composition in extremely preterm infants. This study was registered at clinicaltrials.gov as NCT03586102 https://clinicaltrials.gov/study/NCT03586102 (registered in March 2020).

Humans↗
PubMed2004

Polymerization shrinkage: effects of constraint and filling technique in composite restorations.

OBJECTIVES: To evaluate the linear polymerization shrinkage (LPS) and its effect upon mean gap width, bond strength and cohesive strength of a composite placed under different constraints (C-factors--CF) and filling techniques. METHODS: Composite was placed in cavities sized 4 x 4 x 2 mm3 (CF = 3) or on flat dentin surfaces (CF = 0.3) of bovine incisors, after adhesive application. They were inserted in one or three increments, and light cured (600 mW/cm2) for 80 s. The LPS was measured by placing a probe on the top surface of the composite in order to measure its dislodgment in the top-bottom direction. Half of the sample was sectioned to obtain composite resin sticks subjecting them to tensile forces at 0.5 mm/min. The other half of the sample was sectioned and the mean gap width was measured in both sides of the sections. Then the sections were sliced again to obtain composite/dentin sticks. The mean gap width in the sticks was performed before subjecting them to tensile forces at 0.5 mm/min. Data was analyzed by a two-way ANOVA and the correlation between the bond strength and gap width was analyzed by simple linear regression. RESULTS: (1) Linear polymerization shrinkage: significant differences were observed for the interaction (p < 0.05). Under the low constraint, the LPS were similar for both filling techniques. Under higher constraint, polymerization shrinkage was lower for the incremental technique. (2) Gap width and bond strength: no difference was detected either for interaction, or for technique (p > 0.05). Under higher constraint, the gap width was higher and the bond strength lower. (3) The cohesive strength of composite resin was similar for all groups (p > 0.05). No correlation between bond strength and gap width was found (p = 0.17). SIGNIFICANCE: The effects of polymerization shrinkage were not reduced by the filling technique under the different cavity constraints tested.

Analysis of Variance↗
PubMed2000

Increased intraocular pressure and visual field defects in high resistance wind instrument players.

OBJECTIVE: In this twofold study, part 1 aimed to determine whether the playing of high resistance wind instruments elevates intraocular pressure (IOP) and if so, to investigate the mechanism of IOP elevation and whether its magnitude differs while playing high resistance versus low resistance instruments. The purpose of part 2 was to evaluate whether high resistance players have a greater incidence of glaucomatous changes than other musicians. DESIGN: Three case reports and a cross-sectional study. PARTICIPANTS: Two players of high resistance instruments and one player of high and low resistance wind instruments participated in part 1 of the study. Nine high resistance wind players, 12 low resistance wind players, and 24 nonwind players were recruited among professional musicians in the Boston area to participate in part 2. INTERVENTION: In part 1, IOP and uveal thickness changes were measured by pneumatonometry and ultrasound biomicroscopy in two participants playing their high resistance wind instruments (trumpet and oboe) and in a third participant playing both high (trumpet) and low (clarinet and saxaphone) resistance instruments. Each musician in part 2 underwent medical and musical history, measurement of IOP, Humphrey visual field testing, slit-lamp examination, gonioscopy, and dilated examination. MAIN OUTCOME MEASURES: Intraocular pressure and uveal thickness changes, and visual field loss and optic nerve head appearance were the main parameters measured in part 1 and part 2, respectively. RESULTS: In part 1, pneumatonometry showed IOP elevation dependent on the force of blowing, and ultrasound biomicroscopy revealed uveal thickening associated with IOP elevation. The magnitude of IOP elevation was dependent on the amount of expiratory resistance provided by the particular instrument. Part 2 showed that life hours of high resistance wind instrument playing had a significant relationship to abnormal visual field (P = 0.03) and corrected pattern standard deviation (CPSD) scores (P = 0.007) in univariate logistic regression and univariate linear regression, respectively. A 0.011-unit increase in CPSD for each 1000 life hours of high resistance wind playing was found. CONCLUSIONS: High and low resistance wind musicians experience a transient rise in their IOP while playing their instruments as a result least in part of uveal engorgement. The magnitude of IOP increase is greater in high resistance wind players versus low resistance wind players. High resistance wind musicians had a small but significantly greater incidence of visual field loss (abnormal fields and increased CPSD scores) than other musicians, which was related to life hours of playing. The cumulative effects of long-term intermittent IOP elevation during high resistance wind instrument playing may result in glaucomatous damage, which could be misdiagnosed as normal-tension glaucoma.

Aged↗