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PubMedDate not supplied

Using direct current resistivity sounding and geostatistics to aid in hydrogeological studies in the Choshuichi alluvial fan, Taiwan.

Ground water reservoirs in the Choshuichi alluvial fan, central western Taiwan, were investigated using direct-current (DC) resistivity soundings at 190 locations, combined with hydrogeological measurements from 37 wells. In addition, attempts were made to calculate aquifer transmissivity from both surface DC resistivity measurements and geostatistically derived predictions of aquifer properties. DC resistivity sounding data are highly correlated to the hydraulic parameters in the Choshuichi alluvial fan. By estimating the spatial distribution of hydraulic conductivity from the kriged well data and the cokriged thickness of the correlative aquifer from both resistivity sounding data and well information, the transmissivity of the aquifer at each location can be obtained from the product of kriged hydraulic conductivity and computed thickness of the geoelectric layer. Thus, the spatial variation of the transmissivities in the study area is obtained. Our work is more comparable to Ahmed et al. (1988) than to the work of Niwas and Singhal (1981). The first "constraint" from Niwas and Singhal's work is a result of their use of linear regression. The geostatistical approach taken here (and by Ahmed et al. [1988]) is a natural improvement on the linear regression approach.

Electricity↗
PubMed1992

Rapid estimation of left ventricular ejection fraction in acute myocardial infarction by echocardiographic wall motion analysis.

Echocardiographic estimates of left ventricular ejection fraction (ECHO-LVEF) in acute myocardial infarction (AMI) were obtained by a new approach, using visual analysis of left ventricular wall motion in a nine-segment model. The method was validated in 41 patients using radionuclide ventriculography (RNV) and contrast ventriculography measurements of LVEF for comparison. ECHO-LVEF from the 41 patients correlated well with the reference methods (y = 1.5x - 14.7, r = 0.93; linear regression analysis; 95% confidence limit for a single determination of ECHO-LVEF was 17.2). Interobserver variability by linear regression was r = 0.89, SEE = 7.1 with a mean difference between paired observations of -1.5 +/- 6.9 (SD). In a random sample of 18 patients (45 observations), ECHO-LVEF allowed separation between RNV-LVEF values greater than or equal to 40 and less than 40, representing low and high risk groups following AMI. Thus, the results showed that simple, readily available wall motion-derived estimates of LVEF were as closely associated with LVEF measured by standard reference methods as were previously published, more cumbersome, planimetric echocardiographic methods. Reporting on global LVEF function in LVEF units rather than in nonstandardized wall motion scores of index values may facilitate intra- and interhospital communication and the use of optimized echocardiographic risk stratification after AMI.

Echocardiography↗
PubMed1982

Photographic, stereological and statistical methods in evaluation of aggregation of red cells in disease: part I: kinetics of aggregation.

Kinetics of red cells aggregation were studied by microphotography of blood contained between parallel-plates in a slit of 12.5 micrometers. Blood samples, anticoagulated with EDTA, were adjusted to haematocrit of 0.30 using native plasma. Blood was allowed to flow at shear rate of 2000 sec-1, flow was stopped, and sequential photography carried out. Full development of aggregation required from 2 to 10 minutes, depending on the blood sample. Blood studied included normal donors and patients with polycythaemia, lymphoma, hyperparathyroidism, Waldenström's macroglobulinaemia, influenza. The quantitative evaluation of colour slides was carried out on Microvideomat No. 2 with Zeiss Interference Monochromator, using light wave length of 460 or 560 nanometers. The stereological parameters defined included d(Heyn), Lamda, and S/V. Linear regressions of stereological parameters against square root of stasis time showed correlation coefficients of 0.8 up to 0.99. Linear regressions for different blood samples were compared, and significance of differences between slopes or between elevations was defined using F-distribution. Such differences were significant up to P less than 0.001. Rate of aggregation was much higher in macroglobulinaemia or lymphoma than in normals, and it was lowest in the hyperparathyroid disease.

Erythrocyte Aggregation↗
PubMed2002

Trends of childhood diabetes incidence in Slovakia 1985-2000: accelerated increase in the years 1990-2000.

BACKGROUND: A sudden rise in the incidence of childhood diabetes (DM 1) in Central and Eastern Europe over the last decade has been reported. AIM: To compare in Slovakia incidence trends in the 80s with those in the 90s. SUBJECTS AND METHODS: The data from the Slovak Register of Diabetic Children diagnosed in 1985-2000 (n=1818) were divided into 6 groups according to sex and age at diagnosis (0-4, 5-9, 10-14). Trends were computed separately for 1985-1990 and 1990-2000. The 95% confidence estimates of linear regression coefficients and as percentages from the estimated starting values in 1985 and 1990, were calculated by the linear regression based on statistical inferential approach. RESULTS: Non-significant increasing or decreasing trends were found in 6 gender/age groups 1985-1990. In the 90s, however, significantly increasing trends were present in each of 6 groups. They were significant (p<0.05) in the male groups and in the total of all cases. The overall incidence rise (+0.03 cases per 100000 children per year) was nonsignificant in the 80s but significant in the 90s (+0.63/100000/year). As a result, the incidence rate of childhood diabetes in Slovakia rose from 6.01 new cases per 100000 children per one year in 1985 to 13.53/100000/year in 2000. CONCLUSION: The overall DM 1 incidence increaseed from the 1980s (80s) to the 1990s (90s), expressed in the number of new cases, is more than a 20-fold absolutely and almost 10-fold in relative terms. This was not due to an improvement in diagnosis in 1990s. Both the gender and age heterogeneity were present. (Tab. 2, Fig. 2, Ref. 25.).

Adolescent↗
PubMed2000

High-dose rectal and oral acetaminophen in postoperative patients--serum and saliva concentrations.

BACKGROUND: The primary purpose of the study was to examine the absorption of acetaminophen by measuring serum and saliva concentrations produced by a standard postoperative acetaminophen dosing regimen and secondary to examine the correlation between saliva and serum concentrations of acetaminophen after rectal and oral dosing. METHODS: Twenty-four women, aged 18-60 years, scheduled for minor gynaecological laparoscopic surgery were studied. Patients received acetaminophen 2000 mg suppositories after surgery and oral doses of 1000 mg at 4 and 8 h postoperatively. Alfentanil was available via patient-controlled analgesia. Saliva and blood samples were collected postoperatively. RESULTS: At 1, 2, 3, and 4 h after rectal dosing the saliva concentrations (mean+/-SD) were 15.2+/-5.9 micromol/l, 33.7+/-12.5 micromol/l, 45.5+/-19.1 micromol/l, and 55.4+/-23.1 micromol/l, respectively. The serum concentrations at 2 and 4 h were 31.0+/-11.2 micromol/l and 54.8+/-23.8 micromol/l, respectively. Additional oral dosing resulted in saliva concentrations at 5, 8, and 9 h of 99.7+/-49.5 micromol/l, 106.9+/-31.7 micromol/l, and 139.3+/-55.4 micromol/l, respectively, with coincident serum concentrations of 100.1 +/- 50.2 micromol/l, 105.6+/-29.0 micromol/l, and 141.2+/-52.1 micromol/l. After rectal dosing the linear regression resulted in r2=0.96, P<0.001 and saliva/ serum-ratio=0.99. After additional oral dosing the outcome of linear regression was: r2=0.90, P<0.001 and saliva/serum-ratio= 1.00. CONCLUSION: The slow and ongoing absorption process resulting in no maximum concentration within 4 h after administration of 2000 mg acetaminophen suppositories makes this rectal regimen therapeutically irrational for treatment of postoperative pain. The significant ratio and linear correlation between saliva and serum concentrations of acetaminophen suggests that saliva could be used instead of blood to monitor acetaminophen administration in patients.

Absorption↗
PubMed1994

Rate-related and autonomic effects on atrioventricular conduction assessed through beat-to-beat PR interval and cycle length variability.

INTRODUCTION: Atrioventricular (AV) conduction time varies on a beat-by-beat basis in response to the influences of cardiac efferent autonomic activity and rate-dependent electrical recovery processes. The goals of this study were to distinguish these effects on AV conduction time and to compare the variability in sinoatrial and AV nodal function. METHODS AND RESULTS: The PR interval on the surface ECG served as an index of AV conduction time in this study of 14 adult human subjects undergoing a random interval breathing protocol. P and R waves were located by a template-matching algorithm. Spectral analysis allowed frequency-domain comparisons between PR and RR interval variability. Spectra of PR and RR intervals had similar power distributions, although the power of the RR interval spectra was much greater. Autonomic blockade with atropine plus propranolol reduced the power of both spectra. Standing significantly decreased the spectral power from 0.15 to 0.5 Hz for PR and RR spectra, and introduced a peak near 0.1 Hz in the mean PR and RR spectra, although the latter finding was significant only for the RR interval spectra. Propranolol had no significant effects on the PR and RR interval spectra. Linear regression analysis allowed quantification of the autonomic and recovery effects on AV conduction and showed which effect predominated. Simple linear regression confirmed in adults a previous finding in children that conduction time may be either positively or negatively correlated with cycle length. By multiple regression and transfer function analysis, the inverse relation seen in some subjects was attributed to the effect of recovery from the preceding cycle. With the preceding recovery period accounted for, the conduction time and cycle length of the current beat were positively correlated, presumably due to the parallel autonomic effects on the sinoatrial and AV nodes. The magnitude of the recovery effect predicted by the regression analysis was similar to published values. CONCLUSION: A noninvasive evaluation of the surface ECG can be used to compare variability in AV conduction time and cycle length and characterize the effects of autonomic efferent activity and rate-related recovery on AV nodal function.

Adult↗
PubMed1997

The association between ionized calcium in blood and selected parameters in dairy cows with left displaced abomasum.

The objective of this study was to examine the association between blood calcium (Ca) and left displaced abomasum (LDA), and between Ca and selected anamnestic, blood and urine parameters in cows diagnosed with LDA. One hundred and forty-four cows diagnosed with LDA and 20 controls were used. The association between Ca and LDA was evaluated using linear regression. Possible associations between anamnestic, blood and urine parameters and blood calcium were assessed using a forward stepwise procedure in linear regression. Ca was not significantly associated with LDA. In control cows, Ca was explained by urea alone (R2 = 0.6); this was a negative association. In cows diagnosed with LDA, the final model of Ca included base excess (partial R2 = 0.31), urea (partial R2 = 0.11), phosphorus (partial R2 = 0.03) and potassium (partial R2 = 0.03). A negative linear association was found between base excess and Ca. A quadratic association was found between urea and Ca. We conclude that Ca is significantly associated with urea in dairy cows. Ca is not significantly associated with displaced abomasum in cows diagnosed with LDA. Blood base excess and urea explain Ca in cows diagnosed with LDA.

Abomasum↗
PubMedDate not supplied

Comparison of chairside microbiological screening systems and conventional selective media in children with and without visible dental caries.

PURPOSE: The purpose of this study was to compare the results of commercial chairside microbial tests (CT) and conventional selective media (GS, gold standards) for mutans streptococci (MS) and lactobacilli (LB) using oral specimens from young children with and without visible dental caries. METHODS: Using cotton swabs to collect oral microbial specimens from children 10 to 36 months old, microbial counts of CT and GS were compared with caries experience of the subjects. Contamination levels by non-MS or non-LB isolates on CT and GS were also determined. The CT employed were: (1) CRT bacteria for MS and LB; (2) CarioCheck Plus for MS and LB; and (3) Dentocult SM and Mucount for MS. RESULTS: All CT and GS for MS represented caries status of the participants (P<.001, Fisher exact test; P<.015 linear regression), whereas only GS for LB showed significant association with caries status (P<.001, Fisher exact test; P<.001, linear regression). Non-MS or non-LB isolates were observed on most media, and CT usually exhibited higher contaminant levels than GS. Dentocult SM and Mucount did not harbor contaminants. CONCLUSIONS: Despite contamination, CT and GS for MS and GS for LB exhibited satisfactory outcomes based on cross-sectional caries experience of infants and toddlers.

Chi-Square Distribution↗
PubMed2002

Modified regression model for the Logan plot.

Logan's graphical model is a robust estimation of the total distribution volume (DVt) of reversibly bound radiopharmaceuticals, but the resulting DVt values decrease with increasing noise. The authors hypothesized that the noise dependence can be reduced by a linear regression model that minimizes the sum of squared perpendicular rather than vertical (y) distances between the data points and fitted straight line. To test the new method, 15 levels of simulated noise (repeated 2,000 times) were added to synthetic tissue activity curves, calculated from two different sets of kinetic parameters. Contrary to the traditional method, there was no ( P > 0.05) or dramatically decreased noise dependence with the perpendicular model. Real dynamic 11C (+) McN5652 serotonin transporter binding data were processed either by applying Logan analysis to average counts of large areas or by averaging the Logan slopes of individual-voxel data. There were no significant differences between the parameters when the perpendicular regression method was used with both approaches. The presented experiments show that the DVt calculated from the Logan plot is much less noise dependent if the linear regression model accounts for errors in both the x and y variables, allowing fast creation of unbiased parametric images from dynamic positron-emission tomography studies.

Artifacts↗
PubMed2005

Quantifying the uncertainty of on-line sensors at WWTPs during field operation.

It remains an ongoing task to quantify the uncertainty of continuous measuring systems at WWTPs during field operation. The commonly used methods are based on lab experiments under standardized conditions and are only suitable for characterizing the measuring device itself. For measuring devices under field conditions, a knowledge of the response time, trueness and precision is equally important. A method is proposed which can be used to characterize newly installed on-line sensors or to evaluate monitoring data which may contain systematic errors. The concept is based on comparative measurements between the sensor and a reference. A linear regression is used to differentiate between trueness and precision. Various statistical tests are conducted to validate the preconditions of linear regression. The information about the trueness and precision of the measuring system under field conditions helps to adapt control strategies more effectively to the relevant processes and permits sophisticated control concepts. Moreover, the concept can help to define guidelines for evaluating the uncertainties of effluent quality monitoring to overcome the concerns about on-line sensors, improve the trust in these systems and to allow the use of continuously measuring systems for legislative purposes. The approach is discussed in detail in this paper and all statistical tests and formulas are listed in the Appendix.

Linear Models↗
PubMed2002

Defining the relationship between plasma glucose and HbA(1c): analysis of glucose profiles and HbA(1c) in the Diabetes Control and Complications Trial.

OBJECTIVE: To define the relationship between HbA(1c) and plasma glucose (PG) levels in patients with type 1 diabetes using data from the Diabetes Control and Complications Trial (DCCT). RESEARCH DESIGN AND METHODS: The DCCT was a multicenter, randomized clinical trial designed to compare intensive and conventional therapies and their relative effects on the development and progression of diabetic complications in patients with type 1 diabetes. Quarterly HbA(1c) and corresponding seven-point capillary blood glucose profiles (premeal, postmeal, and bedtime) obtained in the DCCT were analyzed to define the relationship between HbA(1c) and PG. Only data from complete profiles with corresponding HbA(1c) were used (n = 26,056). Of the 1,441 subjects who participated in the study, 2 were excluded due to missing data. Mean plasma glucose (MPG) was estimated by multiplying capillary blood glucose by 1.11. Linear regression analysis weighted by the number of observations per subject was used to correlate MPG and HbA(1c). RESULTS: Linear regression analysis, using MPG and HbA(1c) summarized by patient (n = 1,439), produced a relationship of MPG (mmol/l) = (1.98 . HbA(1c)) - 4.29 or MPG (mg/dl) = (35.6 . HbA(1c)) - 77.3, r = 0.82). Among individual time points, afternoon and evening PG (postlunch, predinner, postdinner, and bedtime) showed higher correlations with HbA(1c) than the morning time points (prebreakfast, postbreakfast, and prelunch). CONCLUSIONS: We have defined the relationship between HbA(1c) and PG as assessed in the DCCT. Knowing this relationship can help patients with diabetes and their healthcare providers set day-to-day targets for PG to achieve specific HbA(1c) goals.

Blood Glucose↗
PubMed2005

Validity and validation of expert (Q)SAR systems.

At a recent workshop in Setubal (Portugal) principles were drafted to assess the suitability of (quantitative) structure-activity relationships ((Q)SARs) for assessing the hazards and risks of chemicals. In the present study we applied some of the Setubal principles to test the validity of three (Q)SAR expert systems and validate the results. These principles include a mechanistic basis, the availability of a training set and validation. ECOSAR, BIOWIN and DEREK for Windows have a mechanistic or empirical basis. ECOSAR has a training set for each QSAR. For half of the structural fragments the number of chemicals in the training set is >4. Based on structural fragments and log Kow, ECOSAR uses linear regression to predict ecotoxicity. Validating ECOSAR for three 'valid' classes results in predictivity of > or = 64%. BIOWIN uses (non-)linear regressions to predict the probability of biodegradability based on fragments and molecular weight. It has a large training set and predicts non-ready biodegradability well. DEREK for Windows predictions are supported by a mechanistic rationale and literature references. The structural alerts in this program have been developed with a training set of positive and negative toxicity data. However, to support the prediction only a limited number of chemicals in the training set is presented to the user. DEREK for Windows predicts effects by 'if-then' reasoning. The program predicts best for mutagenicity and carcinogenicity. Each structural fragment in ECOSAR and DEREK for Windows needs to be evaluated and validated separately.

Algorithms↗
PubMed2006

Factors determining post-colonoscopy abdominal pain: prospective study of screening colonoscopy in 1000 subjects.

BACKGROUND: Factors determining post-colonoscopy abdominal pain remain poorly understood. Accordingly, a prospective study was conducted to reveal the key determinants. METHODS: One thousand consecutive and asymptomatic patients (569 men, 431 women; mean age 51 years, range 19-84 years) undergoing total colonoscopy were evaluated to assess their abdominal pain. Their demographic data, psychological profiles (determined on the Brief Symptom Rating Scale and Maudsley Personality Inventory), and endoscopic findings were treated as independent variables in polytomous logistic regression in which pain severities were treated as outcome variables. Factors affecting the duration of pain were evaluated on multivariate linear regression. RESULTS: Colonoscopy duration (s; odds ratio [OR]: 1.001, 95% confidence interval [CI]: 1-1.002, P<0.01) and female sex (OR: 1.368, 95%CI: 1.02-1.853, P=0.03) were significantly associated with abdominal pain, but age, body mass index, psychological traits, conscious sedation, use of i.v. hyoscine butylbromide, and colonic preparation were not. Duration of the colonoscopy was longer in female than male subjects (P=0.04). On stepwise linear regression, irritable bowel syndrome (regression coefficient: 27.47, 95%CI: 6.99-47.67, P<0.01) and conscious sedation (regression coefficient: -22.17, 95%CI: -42.52 to -1.42, P = 0.036) were the best predictors of prolonged pain in 485 patients who had pain. CONCLUSIONS: Female sex and duration of colonoscopy increased the likelihood of post-procedural abdominal pain. Conscious sedation temporarily suppressed the pain but had no effect on its occurrence. Irritable bowel syndrome may have prolonged the discomfort.

Abdominal Pain↗
PubMed2002

Relationship between cyclosporine concentrations obtained using the Roche Cobas Integra and Abbott TDx monoclonal immunoassays in pre-dose and two hour post-dose blood samples from kidney transplant recipients.

Current evidence suggests that cyclosporine (CsA) concentration in blood samples taken 2 hours after Neoral microemulsion (Novartis Pharmaceuticals; East Hanover, NJ) administration (C2) predicts clinical events in transplant patients better than the pre-dose (trough) concentration (C0). Similarly, previous findings have shown that the metabolites/CsA ratio is substantially lower in C2 than in C0 samples; however the between-monoclonal immunoassay differences for C2 samples have received little attention in the literature. In 56 C samples and 60 C samples from renal transplant patients, CsA levels were determined using the monoclonal fluorescence polarization immunoassay (mFPIA) from Abbott (Abbott Park, IL) and the homogeneous enzyme immunoassay technique (HEIT) from Roche Diagnostics (Basel, Switzerland). In both cases a high correlation coefficient between the results was obtained (r > or = 0.971), with a linear regression for C0 samples: mFPIA = 1.47 HEIT + 22.0 and for C2 samples: mFPIA = 1.11 HEIT + 71.96. The difference between the linear regression slopes was statistically significant (P < 0.001), and the mFPIA/HEIT ratio was significantly higher for C than for C samples (P < 0.001).

Antibodies, Monoclonal↗
PubMed2004

Admission lactate level and the APACHE II score are the most useful predictors of prognosis following torso trauma.

BACKGROUND: Markers of dysoxic metabolism and scoring systems for triage have been widely used in critically injured patients. However, so far, no model is sufficiently reliable to predict the outcome in trauma victims. The purposes of the present study, therefore, were to determine whether a correlation exits between the main trauma scoring systems and the markers of dysoxic metabolism. Moreover, to assess if any of the admission parameters can be used to indicate outcome. METHODS: Sixty-four patients were included in this study. Admission data, including arterial lactate level, base deficit (BD), pH, revised trauma score (RTS), injury severity score (ISS), shock index (SI), and Acute Physiology and Chronic Health Evaluation (APACHE II), were collected and analysed by logistic regression analysis. Degree of association between continuous variables were calculated by either Pearson's or Spearman's correlation coefficient, where applicable. The dependence of lactate on two or more other variables was evaluated by multiple linear regression analysis. RESULTS: Logistic regression analysis showed that the fatal outcome following major torso trauma was principally associated with the APACHE II score and lactate. The specificity and the sensitivity of this logistic regression model was 94.6 and 79.2%, respectively. According to standardised linear regression coefficients, BD was the best single predictor of lactate, and APACHE II added a small amount of predictive power. The proportion of total variation in lactate level explained by base deficit, APACHE II and age is R2=85.2%. CONCLUSION: APACHE II score and the arterial lactate level are the most important determinants of clinical outcome in critically injured patients. A correlation exits between lactate and APACHE II and between lactate and base deficit.

APACHE↗
PubMed2006

Differences in Michaelis-Menten kinetics for different cultivars of maize during cyanide removal.

Knowledge of the kinetic parameters, the half-saturation constant (K(m)) and the maximum metabolic capacity (v(max)), is very useful for the characterization of enzymes and biochemical processes. Little is known about rates of which vegetation metabolizes environmental chemicals. It is known, however, that vascular plants possess an enzyme system that detoxifies cyanide by converting it into the amino acid asparagine. This study investigated the differences in Michaelis-Menten kinetics of cyanide removal by different cultivars of maize. Detached leaves (1.0 g fresh weight) of seven different cultivars of maize (Zea mays L.) were kept in glass vessels with 100mL of aqueous solution spiked with potassium cyanide at 25+/-0.5 degrees C for 28 h. Four treatment concentrations of cyanide were used, ranging from 0.43 to 7.67 mgCNL(-1). The disappearance of cyanide from the aqueous solution was analyzed spectrophotometrically. Realistic values of K(m) and v(max) were estimated by a computer program using non-linear regression treatment. Lineweaver-Burk plots were also used to estimate the kinetic parameters for comparison. Using non-linear regression treatments, values of v(max) and K(m) were found to be between 10.80 and 22.80 mgCNkg(-1)h(-1), and 2.57 and 7.09 mgCNL(-1), respectively. The highest v(max) was achieved by the cultivars HengFen 1, followed by NongDa 108. The lowest v(max) was demonstrated by JingKe 8. The highest K(m) was found in NongDa 108, followed by HengFen 1. The lowest K(m) was associated with JingKe 8. Results from this study indicated that significant removal of cyanide from an aqueous solution was observed in the presence of plant materials without apparent phytotoxicity, even at the high concentration of cyanide used in this study. All maize cultivars used in this study were able to metabolize cyanide efficiently, although with different metabolic capacities. Results also showed a small variation of metabolic rates between the different cultivars. This leads to the conclusion that plants can be used as a phytoremediation agent in the detoxification of cyanide, presenting a feasible option for cleaning up soils and water contaminated with cyanide.

Biodegradation, Environmental↗
PubMedDate not supplied

Radiopacity of compomers, flowable and conventional resin composites for posterior restorations.

The objective of this study was to densitometrically determine the relative radiopacity (aluminum [Al]-equivalent values) of dentin, enamel, and 20 resin composite materials currently used for posterior restorations. Specimens 5 mm in diameter and 2 mm thick were fabricated from 20 materials (n = 7) for a total of 140 specimens. Human molars were longitudinally sectioned 2.0 mm thick to include both enamel and dentin. The optical densities of enamel, dentin, restorative materials, lead, and aluminum step wedge were obtained from radiographic images, using a transmission photodensitometer. The Al equivalent (mm) for each material was calculated from the linear regression equation of the log of normalized optical density and Al mm thickness obtained from the step wedge. A linear regression of the logarithm of normalized optical density and Al mm thickness was plotted (r2 = 0.9953), and the relative radiopacities, expressed as equivalent thickness of Al, were ranked ordinally. All materials tested, with the exception of an unfilled resin adhesive, complied with ISO Standard 4049, being at least as radiopaque as a 2.0 mm thickness of 99.6% pure Al. Four of six flowable composites had radiopacity values that fell between that of dentin and enamel, while two materials were more radiopaque than enamel. The three compomers tested had radiopacities greater than enamel. In addition, all traditional light- and chemical-cure resin composite materials tested were more radiopaque than enamel. All materials tested, with the exception of one adhesive resin, were at least as radiopaque as dentin and complied with ISO Standard 4049. Clinicians should be able to distinguish these restorative materials radiographically from recurrent decay, voids, gaps, or other defects that lead to clinical failure. Utilization of materials ranked more radiopaque than enamel would enable clinicians to distinguish the restorative material from tooth structure.

Absorptiometry, Photon↗
PubMed2004

[Bispectral index and desflurane concentration below 1 MAC].

INTRODUCTION: We investigated the relationship between bispectral index (BIS, A-2000, Aspect Medical Systems, USA) and end-tidal desflurane concentrations below 1 MAC which is especially the range of interest if desflurane is combined with remifentanil for fast-track anaesthesia. METHODS: With institutional review board approval and written informed consent we investigated 50 adult ASA I-III patients scheduled for minor orthopaedic surgical procedures. The BIS electrode (BIS-Sensor, Aspect Medical Systems, USA) was positioned on the patient's forehead as recommended by the manufacturer. All patients were premedicated with 0.15 mg x kg(-1) diazepam orally in the evening and on the morning before surgery. Induction of anaesthesia was started with a remifentanil infusion at 0.4 micro g x kg(-1) x min(-1) and 5 min later 2 mg x kg(-1) propofol was given for hypnosis. Immediately after intubation, remifentanil was reduced to 0.2 micro g x kg(-1) x min(-1), and the depth of anaesthesia was adjusted according to clinical needs by regulating the desflurane concentration. Starting 20 min after induction, a total of 1,483 data pairs, i.e. end-tidal desflurane concentrations with corresponding BIS values, was recorded. During surgery data pairs were analysed by linear regression analysis for each patient separately. During emergence from anaesthesia, desflurane effect compartment concentrations were simulated and non-linear regression analysis was applied. RESULTS: We found a relationship between BIS ranges and mean end-tidal desflurane concentrations: A BIS range of 100-85 was related to 1.1+/-0.7 vol%, BIS 84-65 to 1.5+/-1.2 vol%, BIS 64-50 to 2.9+/-1.3 vol% and BIS 49-40 to 3.1+/-0.9 vol%. In particular, end-tidal desflurane concentrations related to these BIS ranges were significantly different from each other (ANOVA; P<0.05). Intraoperatively, we obtained a correlation coefficient of R=0.42+/-0.24 (mean+/-SD, range 0.05-0.96), during emergence from anaesthesia the correlation coefficient was R=0.84+/-0.12 (range 0.61-0.99). CONCLUSION: We could demonstrate a relationship between bispectral index and end-tidal desflurane concentrations below 1 MAC with a BIS range of 49-40 being associated with approximately 0.5 MAC of desflurane during desflurane-remifentanil-anaesthesia.

Adult↗