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PubMed2006

Bone mass and the risk of breast cancer: the influence of cumulative exposure to oestrogen and reproductive correlates. Results of the Marburg breast cancer and osteoporosis trial (MABOT).

BACKGROUND: Recent studies suggest an inverse relation between breast cancer and osteoporosis. Oestrogen is important in the pathophysiology of both breast and bone, and although cumulative exposure to oestrogen may explain the link between breast cancer and bone mass, this has never been proved. The Marburg breast cancer and osteoporosis trial (MABOT) aimed to elucidate the relation between breast cancer and bone mass ascertained by ultrasonometry measurement and to investigate whether endogenous and exogenous exposure to oestrogen and reproductive correlates has a role in this association. METHODS: We performed a case-control study including 2492 women (mean age+/-S.D., 54.4+/-10.3 years) in whom diseases and drug treatments known to affect bone metabolism, except for HT, had been excluded. All women underwent ultrasonometry measurement at the heel; 242 of the women had an incident breast cancer without a prior, specific pharmacological breast cancer treatment. The ultrasonometry variables - speed of sound (SOS), broadband ultrasound attenuation (BUA) and the stiffness index (SI) - were calculated and compared in women with and without breast cancer. Because of significant intergroup differences in factors such as age, body mass index and exposure to oestrogen, a multiple linear regression analysis as well as a second analysis of ultrasonometry variables was undertaken using a randomly selected sample of 242 healthy women post-matched with the breast cancer group for possible confounding variables. Odds ratios were used to compare the relation between breast cancer risk and ultrasonometry heel measurements. RESULTS: Women with breast cancer were significantly older, weighed more, had a higher body mass index, were more likely to be parous and to have breast fed, were older at the menopause and had been exposed to oestrogen for longer than control women. In addition, the ultrasonometry variables speed of sound and the stiffness index T- and Z-score were significantly higher in women with breast cancer even after a matched pair analysis was performed (p<0.001). Additionally, results of a multiple linear regression showed that women with breast cancer had a significantly higher SOS (p<0.001), body weight (p<0.05) and duration of breast feeding (p<0.05) while osteoporotic fracture were reduced (p<0.001). When women with breast cancer and their matched controls were finally grouped according to SOS and T-score quartiles, the odds ratios (95% confidence intervals) for breast cancer risk in the second, third and fourth quartiles compared with the lowest quartile were 2.5 (1.4-4.3), 3.1 (1.8-5.3) and 4.7 (2.7-8.2) as well as 1.9 (1.1-3.2), 2.3 (1.3-3.9) and 2.9 (1.7-5.0), respectively. CONCLUSIONS: The ultrasonometry variables speed of sound, stiffness index, T- and Z-score are higher in women with an incident breast cancer than in healthy controls, even after post-matching for possible confounding variables. This association was confirmed in a multiple linear regression model. Women with SOS and T-score values in the higher quartiles have a greater risk of breast cancer than women in the lowest quartile. We found no association between the higher ultrasonometry variables and cancer specific characteristics or reproductive correlates such as age at menarche and menopause or cumulative oestrogen exposure. Although the biological mechanisms linking bone mass and the risk of breast cancer are not fully understood, factors other than reproductive correlates, endogenous and exogenous exposure to oestrogen must play a part.

Adult↗
PubMed2003

Prediction of human pharmacokinetics from animal data and molecular structural parameters using multivariate regression analysis: volume of distribution at steady state.

The aim of this study was to develop a regression equation for predicting volume of distribution at steady state (Vd(ss)) in humans to enable application to various types of drugs using animal experimental data for rats and dogs and some molecular structural parameters. The Vd(ss) data for rats, dogs and humans of 64 drugs were obtained from literature. The compounds have various structures, pharmacological activities and pharmacokinetic characteristics. In addition, the molecular weight, calculated partition coefficient (clogP), and the number of hydrogen bond acceptors were used as possible descriptors related to the Vd(ss) in humans. Multivariate regression analyses, multiple linear regression analysis and the partial least squares (PLS) method were used to predict Vd(ss) in humans. Interaction terms were also introduced into the regression analysis to evaluate the non-linear relationship. For the data set used in the present study, PLS with quadratic term descriptors gave the best predictive performance. The PLS model using Vd(ss) data for only two animal species and using easily calculated structural parameters could generally predict Vd(ss) in humans better than an allometric method. In addition, the PLS model with only animal data gave almost the same predictive performance as the PLS model with quadratic term descriptors. This model may be easier to use and be practical in a realistic situation, and could predict Vd(ss) in humans better than the allometric method.

Animals↗
PubMed1993

Real-time gas-exchange measurement of oxygen consumption in neonates and infants after cardiac surgery.

OBJECTIVES: The purposes of this study were: a) to measure oxygen consumption (VO2) in ventilated neonates and infants after cardiac surgery, utilizing a real-time gas exchange system; and b) to assess this new method by comparing the measured VO2 with calculated VO2 (using the Fick equation and simultaneously determined thermodilution cardiac output, measured hemoglobin, and measured mixed venous and arterial saturations). DESIGN: Prospective, comparison study. Comparison of measured VO2 and calculated VO2 using correlation coefficient, linear regression analysis, and bias and precision. SETTING: Cardiac intensive care unit in a children's hospital. PATIENTS: A total of 60 direct comparisons were made between measured and calculated VO2 in 15 patients (ages ranging from 4 days to 14.1 months with median age of 2.4 months) who were receiving mechanical ventilation after undergoing corrective cardiac surgery. INTERVENTIONS: a) Direct measurement of VO2 using gas exchange method involving a pneumotachograph and a gas sampling system; b) determination of cardiac output by the thermodilution technique; c) measurement of arterial and mixed venous oxygen content by blood sampling. MEASUREMENTS AND RESULTS: The absolute measured VO2 ranged from 19 to 154 mL/min with a mean of 52 +/- 32 mL/min (when indexed, the range was 81 to 367 mL/min/m2 with mean 185 +/- 69 mL/min/m2, or range 4.7 to 18.8 mL/min/kg with mean 10.4 +/- 3.3 mL/min/kg). While 34 (57%) of 60 measured VO2 values were within 10% of their respective calculated VO2 values, 58 (97%) of 60 were within 25%; the mean percent difference between measured and calculated VO2 values was 10.6 +/- 7.7%. In comparing the measured VO2 and calculated VO2, the correlation coefficient was good (r2 = .87; p < .01) and the linear regression equation was: measured VO2 = 1.1 x calculated VO2 -9.0 mL/min/m2. The mean difference, or bias, was 0 mL/min/m2 with precision of 26 and 52 mL/min/m2 (at 1 and 2 SD). As an alternative means of examining the measured VO2 data, we also directly compared the thermodilution cardiac output with cardiac output derived by using the measured VO2 and the Fick equation. The range of Fick-derived cardiac output was between 1.69 to 8.11 L/min/m2 (mean 3.72 +/- 1.56) and the range of thermodilution cardiac output was between 1.75 to 7.42 L/min/m2 (mean 3.71 +/- 1.36). The correlation coefficient between thermodilution cardiac output and Fick-derived cardiac output was good with r2 = .88 (p < .01) and the linear regression equation was: thermodilution cardiac output = 0.81 x Fick-derived cardiac output + 0.71 L/min/m2. The bias was -0.01 L/min/m2 with a precision of 0.54 L/min/m2 at 1 SD (or 1.08 L/min/m2 for 2 SD). CONCLUSIONS: Measured VO2 using a gas-exchange system compared favorably with calculated VO2 values using the Fick equation and simultaneously obtained thermodilution cardiac output and arterial and venous oxygen concentrations. By employing this breath-by-breath gas-exchange system, real-time VO2 measurement in ventilated neonates and infants is now feasible.

Bias↗
PubMed1987

Monoclonal antibody technique for detection of estrogen receptors in human breast cancer: greater sensitivity and more accurate classification of receptor status than the dextran-coated charcoal method.

Estrogen receptor (ER) concentrations have been determined in 191 freshly prepared cytosols from breast cancer biopsies using both the monoclonal enzyme immunoassay (ER-EIA) and the dextran-coated charcoal (ER-DCC) methods in a single laboratory. The concentrations of the ER detected using the two methods are highly and significantly correlated (linear regression curve: ER-EIA = 15.5 + 0.82 ER-DCC; r = 0.97). Nevertheless, it may be most correct to interpret the data by resolving the correlation into two lines, one describing the fit for cytosols with low and intermediate concentrations (the first 75% of the distribution of ER values for all primary breast cancers; less than 217 fmol ER/mg cytosol protein) and one describing the fit for cytosols with the highest ER concentrations (i.e., greater than or equal to 217 fmol ER/mg cytosol protein). Using a cutoff limit of 10 fmol/mg cytosol protein to distinguish between ER positive and ER negative biopsies, discrepancies in the classification of ER status were found in only 6% (12 of 191) of the cases using the two different methods. In all 12 cases, the ER concentrations as determined by both methods were in the lower range of receptor concentrations (0-53 fmol/mg cytosol protein). Of the 12 discrepancies, 10 biopsies were classified as ER negative using the ER-DCC method but ER positive using the ER-EIA method. Additional available data for these 10 patients indicate that the ER-EIA assay yielded the more biologically "correct" result. All 10 of these biopsies were either progesterone receptor positive or had nuclear ER. By identifying the outliers of the linear regression curves (points exceeding the 80% confidence interval) of the logarithmically transformed ER concentrations, 9 of the 12 biopsies were identified. Thus, it is unlikely that the observed discrepancies are due to random events in most cases here. Since most of the few deviations observed appear to represent true differences in the sensitivities of the two methods, the ER-EIA method appears to be superior to the ER-DCC method in our hands. The concentration of ER in 47 cytosols stored at -70 degrees C for 3-6 yr was analyzed using the ER-EIA method, and results were compared to the concentration of ER found using the ER-DCC method on freshly prepared cytosols when the biopsies had been received at the laboratory. The linear regression curve of the correlation between ER concentrations determined using the two methods did not differ significantly from that found for the 191 freshly prepared cytosols.

Antibodies, Monoclonal↗
PubMedDate not supplied

Polymerization shrinkage of flowable resin-based restorative materials.

This study measured the linear polymerization displacement and polymerization forces induced by polymerization shrinkage of a series of flowable resin-based restorative materials. The materials tested were 22 flowable resin-based restorative materials (Admira Flow, Aelite Flow, Aeliteflow LV, Aria, Crystal Essence, Definite Flow, Dyract Flow, Filtek Flow, FloRestore, Flow-it, Flow-Line, Freedom, Glacier, OmegaFlo, PermaFlo, Photo SC, Revolution 2, Star Flow, Synergy Flow, Tetric Flow, Ultraseal XT and Wave). Measurements for linear polymerization displacement and polymerization forces were performed using custom made measuring devices. Polymerization of the test materials was carried out for 60 seconds by means of a light curing unit, and each property was measured for 180 seconds from the start of curing in eight specimens for each material. Statistical evaluation of the data was performed with one-way analysis of variance (ANOVA), Tukey's Studentized Range (HSD) test (p=0.05) and simple linear regression. A wide range of values was recorded for linear polymerization displacement (26.61 to 80.74 microns) and polymerization forces (3.23 to 7.48 kilograms). Statistically significant differences among materials were found for both properties studied. Very few materials (Freedom, Glacier, and Photo SC) presented low values of linear polymerization displacement and polymerization forces (similar to hybrid resin composites), while the majority of materials presented very high values in both properties studied. Study of the shrinkage kinetics revealed the exponential growth process of both properties. The polymerization forces development exhibited a few seconds delay over linear polymerization displacement. Simple linear regression showed that the two polymerization shrinkage properties that were studied were not highly correlated (r2=0.59).

Analysis of Variance↗
PubMedDate not supplied

A powerful, yet easy to use, computerized analysis of competitive protein binding and radioimmunoassay data.

A computerized method has been developed and tested for the automatic computation of data obtained from competitive radio-binding assays, that is easily used by computer and non-computer oriented individuals. The program requires a series of only eleven parameter lines coded from the assay protocol, followed by the data exactly as it is produced from a standard sample counter. From the set of parameters the program is able to find standard curves at scattered locations through an assay, check their "log dose-logit response" least squares linear regression equations statistically for homogeneity of slopes and elevations, pool the standard curves and check the pooled least squares linear regression equation statistically for linearity and non-linearity. The results of the pooled standard curve is presented graphically and in tabular form. Using the linear equation for the pooled standard curves, the concentration for each unknown sample is predicted with its corresponding 95% confidence interval and presented in a table of unknowns. Also provided in the table of unknowns is a mean and standard error of the mean for all biological replicates, including footnote flags to warn the user when an unknown concentration: (i) is outside the 0-100% bound range; (ii) is estimated from a range outside that covered by the standards; or (iii) was estimated from the unusable tail regions of the standard curve.

Binding, Competitive↗
PubMed2001

Clinical and behavioural risk indicators for root caries in older people.

OBJECTIVE: To investigate the clinical and behavioural factors indicating root caries risk among older people. DESIGN: Cross-sectional clinical and interview data from the National Diet and Nutrition Survey (aged 65 years and over) in Great Britain. Logistic regression models of the prevalence of root caries and linear regression models of the extent of root caries were constructed to quantify the role of a range of clinical and behavioural risk indicators, including sugars intake. SETTING: A national sample of older British adults, free-living and institutionalised. PARTICIPANTS: 462 dentate adults aged 65 years or over. RESULTS: Nine or more intakes of sugars per day more than doubled the odds of root caries being present (OR 2.2-2.4). Other clinical and behavioural factors affecting root caries included wearing a partial denture in the presence of heavy plaque deposits (OR 2.1-2.6) and infrequent tooth brushing (OR 2.8-4.1). Linear regression models showed that, amongst those that had root caries, sucking sweets in the presence of a dry mouth, poor hygiene, partial dentures and living in an institution contributed to the extent of root caries, as measured by the RCI(d). CONCLUSIONS: Of the factors open to possible clinical or behavioural intervention, frequent sugars intake, poor hygiene and partial dentures were all associated with large increases in risk.

Aged↗
PubMed2002

Changes in the rapidly extracted auditory evoked potentials index and the bispectral index during sedation induced by propofol or midazolam under epidural block.

BACKGROUND: The bispectral index (BIS) and the rapidly extracted auditory evoked potentials index (A-line ARX Index or AAI) have been proposed as methods to measure the depth of sedation. A prospective study was designed to assess the performance of both these methods for measuring the depth of sedation induced by propofol or midazolam under epidural block. METHODS: Thirty-two ASA I and II adult patients undergoing elective gynaecological surgery under low-thoracolumbar epidural block were studied. Eighteen patients received propofol (Group P: 20 mg bolus every 3 min) and 14 received midazolam (Group M: 0.5 mg bolus every 5 min) until an observer's assessment of alertness/sedation (OAA/S) scale score of 1 was achieved. AAI and BIS were monitored for different OAA/S scores. RESULTS: AAI and BIS decreased and increased following the changes on the patients' OAA/S scores and correlated with sedation significantly. During the onset phase, the coefficients of Spearman's rank correlation for AAI and BIS were respectively 0.958 and 0.898 (P < 0.001) for Group P, and 0.973 and 0.945 (P < 0.001) for Group M. During the recovery phase in Group P, the coefficients were respectively 0.946 and 0.702 (P < 0.001). Linear regression analysis showed that both AAI and BIS were linearly related to the OAA/S scores. The coefficients of Spearman's rank correlation and linear regression for AAI were all greater than those for BIS (P < 0.05). CONCLUSIONS: Both AAI and BIS correlated well with the depth of sedation induced by propofol or midazolam under epidural block. AAI may be more valuable when monitoring depth of sedation.

Adult↗
PubMed2004

Prediction of premolar tooth lengths based on their panoramic radiographic lengths.

OBJECTIVE: Establishing a linear regression model for the determination of first premolar lengths based on panoramic radiographs. MATERIALS AND METHODS: The real lengths of 112 first premolars extracted for orthodontic reasons were measured and compared with their panoramic lengths. The teeth were divided into four groups according to their intraoral quadrant locations (T14, T24, T34, T44) and regression analysis was conducted for each group. RESULTS: A linear regression model for the prediction of tooth length (mm) based on the panoramic length was established (P < 0.0001): For group T14 the predicted length = (panoramic length x 0.698) + 2.61. For group T24 the predicted length = (panoramic length x 0.5056) + 7.844. For group T34 the predicted length = (panoramic length x 0.5075) + 9.282. For group T44 the predicted length = (panoramic length x 0.436) + 11.298. CONCLUSION: Prediction of all first premolar lengths using their panoramic images is both feasible and reliable.

Adolescent↗
PubMed1997

The internal dose of passive smoking at home depends on the size of the dwelling.

As part of a longitudinal study two urine samples (survey 1 in 1991 and survey 2 in 1992) were collected from 602 elementary school children to investigate the relationship between urinary cotinine excretion (UCE) and the daily consumption of cigarettes at home (exposure). Size of the dwelling, educational level, and maternal smoking were taken into consideration as additional predictors. The history regarding parental smoking habits and confounding variables was ascertained by standardized questionnaires completed by the parents. Cotinine was measured using gas chromatography selected ion monitoring. UCE was expressed as cotinine/creatinine (ng/mg). In children with detectable UCE in survey 1 (35%) and in survey 2 (44%) the excretion ranged between 1.5 and 24.7 ng/mg (5-95%) and between 1.2 and 25.2 ng/mg, respectively. UCE measurements in both surveys were highly correlated (r = 0.65, P = 0.0001), and 59.6% of the UCE in survey 2 can be explained in linear regression by the UCE in survey 1. Using multiple linear regression, the categorized number of cigarettes reported to be consumed at home (20 cigarettes and more: 1991, P = 0.0001; 1992, P = 0.0003) and low educational level of the parents (P = 0.011 in 1991, P = 0.04 in 1992) were positively associated with UCE, whereas the size of the dwelling turned out to be negatively associated with UCE (P = 0.12 in 1991, P = 0.001 in 1992). In small dwellings (< or = 80 m2) the effect of exposure on UCE was much more pronounced. In conclusion, a single UCE measurement provides information which is widely stable within a yearly interval and is related to passive smoke history as well as to socio-economic status and the size of the dwelling. The latter variable should be considered as an effect modifier of exposure on internal dose and should be taken into account in future studies on passive smoke exposure.

Analysis of Variance↗
PubMed1999

Validation of Tu's cardiac surgical risk prediction index in a Western Australian population.

Tu's cardiac surgical risk prediction index for a Western Australian population was examined in a prospective observational cohort study. Risk score and outcome data were collected for 367 consecutive patients. Logistic regression analysis for Tu score prediction of hospital mortality and linear regression analysis for prediction of ICU and hospital stays were performed. The Tu index accurately predicted mortality rates (P = 0.002, odds ratio 1.46). The linear regression analyses of Tu score on ICU and hospital stays showed an excellent fit (P = 0.0001). The area under the receiver-operating characteristic curve for prolonged ICU stay was 0.75. The Tu risk index is valid for a Western Australian cardiac surgical population and practice.

Aged↗
PubMed2007

Facets of acculturation and their diverse relations to body shape concern in Fiji.

OBJECTIVE: The present study examines the relation between acculturation and body shape concern in Fiji--a society undergoing rapid social change. METHOD: Data were from two cohorts of ethnic Fijian girls and women collected in 1998 (n = 115). A factor analysis was performed to identify dimensions of acculturation. The association of these with body shape concern was examined with linear regression. RESULTS: Three dimensions of acculturation were identified. Multiple linear regression models demonstrated that each of these dimensions of acculturation had a unique relation to body shape concern. The adjusted R(2) for the fully adjusted model relating acculturation to body concern was 0.63, indicating a substantial degree of shared variation between measures of body shape concern and measures of acculturation. CONCLUSION: Acculturation may have a strong impact on body shape concern in Fiji. However, acculturation is a multidimensional construct and does not likely have a monolithic relation to body shape concern.

Acculturation↗
PubMed1998

Stereospecific analysis of soybean triacylglycerols.

Thirty soybean germplasm lines representing a wide distribution of fatty acid compositions were analyzed stereospecifically by using a chiral column to resolve the sn-1 and sn-3 positions of glycerol. The amounts of each acyl group on each of the sn positions were plotted vs. the amount of that acyl group in the triacylglycerols (TAG), and the plots were fitted by linear regression. The deviation of individual data points from the linear regressions was much greater than observed in previous studies. This could be attributed to the inclusion of a number of germplasm lines with elevated or reduced percentages of saturates. The stereospecific distributions could not be fit with previously suggested mathematical models because the plots had intercepts that were not allowed by the models. Statistical tests of the analytical procedure indicated that slight oxidation of or bias against the polyunsaturates had occurred and that the Grignard deacylation method gave slightly less representative analyses of the sn-2 position than pancreatic lipase deacylation on these TAG.

Fatty Acids↗
PubMed1988

Analysis of chromium-51 release assay data using personal computer spreadsheet software.

The Chromium-51 release assay is a widely used technique to assess the lysis of labeled target cells in vitro. We have developed a simple technique to analyze data from Chromium-51 release assays using the widely available LOTUS 1-2-3 spreadsheet software. This package calculates percentage specific cytotoxicity and lytic units by linear regression. It uses all data points to compute the linear regression and can determine if there is a statistically significant difference between two lysis curves. The system is simple to use and easily modified, since its implementation requires neither knowledge of computer programming nor custom designed software. This package can help save considerable time when analyzing data from Chromium-51 release assays.

Chromium Radioisotopes↗
PubMed2006

Are small renal tumors harmless? Analysis of histopathological features according to tumors 4 cm or less in diameter.

PURPOSE: Small renal tumors detected incidentally are considered to have less aggressive potential. This assumption is mainly based on the low tendency to increase in size on serial imaging studies, but histopathological parameters of progression in larger patient series are scant. MATERIALS AND METHODS: We reviewed data of 287 tumor bearing kidneys in which solid tumors 4 cm or less in diameter were detected by cross-sectional imaging and subsequently removed surgically. Tumor size as documented by preoperative computerized tomography was correlated to histological diagnosis, and in cases of malignancy correlated to tumor type, pathological TNM stage and nuclear (Fuhrman) grade. With multifocal lesions the largest single tumor was considered the reference lesion but multifocality was also considered a separate parameter. RESULTS: At a mean tumor diameter of 2.94 +/- 0.87 cm 65 (22.6%) tumors were 2 cm or less, 103 (35.9%) were 2.1 to 3.0 cm and 119 (41.5%) were 3.1 to 4 cm in diameter. A total of 56 (19.5%) tumors were benign with no correlation to tumor size (Pearson test p = 0.660). Renal cell cancer was found in 227 (79.1%) patients with 159 (70.0%) clear cell, 47 (20.7%) papillary, 11 (4.8%) chromophobe and 10 others with no correlation to tumor diameter. Of the kidneys 31 (13.6%) had multifocal renal cell carcinoma, with a significant correlation to larger tumor diameter (linear regression p = 0.048) and papillary renal cell carcinoma subtype (linear regression p = 0.018). Two (4.2%), 4 (5%) and 25 (25.5%) cases of renal cell carcinoma 2 cm or less, 2.1 to 3 cm and 3.1 to 4 cm in diameter had Fuhrman grade G3/4, respectively (Pearson p = 0.0007). Advanced stage (pT3a or greater) was documented in 2 (4.2%), 12 (14.9%) and 35 (35.7%) cases for the same categories, respectively (p = 0.0023). Whereas distant metastases were diagnosed in only 4 patients with renal cell carcinoma with tumors 3 cm or less, distant metastases were in 10 (8.4%) patients with tumors 3.1 to 4 cm (p = 0.045). CONCLUSIONS: The aggressive potential of small renal cell carcinoma increases dramatically beyond a tumor diameter of 3 cm. Given the difficulty in measuring tumor diameters reliably with sequential imaging studies, the threshold for selecting patients for a surveillance strategy should be set well under this parameter.

Carcinoma, Renal Cell↗
PubMed1998

Role of stationary phase and eluent composition on the determination of log P values of N-hydroxyethylamide of aryloxyalkylen and pyridine carboxylic acids by reversed-phase high-performance liquid chromatography.

The partition coefficients, P, between n-octanol and water of a number of growth stimulating substances, N-hydroxyethylamide of aryloxyalkylen- and pyridine carboxylic acids were obtained from Pomona College (C log P), and Rekker's (log P(Rekker)) revised fragmental constant system was used to calculate log P data sets. Both of these data sets were correlated with two different substance lipophilicity parameters, log k(w) and phi0. Log k(w) was obtained by extrapolation of log retention factor (k) to 0% organic modifier measured in reversed-phase liquid chromatography (RPLC) systems. Phi0 values were obtained from the slopes and intercepts of these relationships. The RPLC experiments were performed on four commercially available reversed-phase columns. Binary mixtures of methanol-water, methanol-phosphate buffer (pH 7.0), methanoltricine buffer (pH 7.0) and acetonitrile-water were used as mobile phases for the determination of log k(w) values. For the methanolic eluents linear regression provided satisfactory correlations (r>0.99) for the relationships log k vs. organic modifier content in the eluent, while for the acetonitrile-containing eluents a second-degree polynominal regression was necessary. For all four RPLC columns, by linear regression satisfactory correlations (r>0.99) were obtained between log k(w) and log P data using methanolic eluents. In such eluents phi0 values were shown to be the second-best lipophilicity parameters. For acetonitrile-containing eluents the use of second-degree polynominal regression was necessary and, in contrast to methanol, significant influence of the applied column on regression results was observed. For acetonitrile-containing eluents the phi0-index does not provide satisfactory results for our substances. No difference in regression results between the use of buffered and non-buffered eluents was observed.

Amides↗
PubMed2003

Shot range estimation based on pellet distribution in shots with a pump-action shotgun.

In the present study, shots from different ranges were fired using a non-choked pump-action shotgun (Hugsan) of calibre 12 with a bore length of 52cm and pellets of various sizes. The aim of the study is range estimation from the distribution of pellets. Using pellets of 2, 3.5, 5 and 8mm size, 5 shots were fired from: 0.7, 0.8, 0.9, 1, 2, 3, 5, 10, 15, 20 and 25ms. The maximum distance between the pellets in vertical and horizontal direction was measured. Statistical evaluation of the data revealed a highly significant correlation for each pellet type; the constant values a and b were calculated to be used in the linear regression equation y=a+bx. As a conclusion, the linear regression equation as well as table data may allow range determination within acceptable ranges of error for the same barrel length and diameter for the same cartridge type. Under identical conditions they may also provide information for pellets of comparable size.

Journal Article↗
PubMed1997

The pharmacokinetics of a single dose of artemisinin in subjects with liver cirrhosis. Bach Mai-Amsterdam Research Group on Artemisinin.

Artemisinin is mainly eliminated by hepatic transformation. To investigate whether the clearance of artemisinin in patients with liver cirrhosis is different from healthy volunteers, a pharmacokinetic study was performed in male Vietnamese patients with Child B cirrhosis of the liver who received 500 mg of artemisinin orally. The results were compared to those found in a previous study in healthy subjects. The mean (+/- SD) area under the concentration time curve was 2365 (+/- 1761) h ng/ml; the mean (+/- SD) clearance, 382 (+/- 303)L/h. The elimination half life was 4 (+/- 1.3) h extimated by log-linear regression and 2.4 +/- 0.9 h estimated by non-linear regression using a one-compartment first order elimination model. The mean (+/- SD) absorption time was 1.55 (+/- 0.8) h. These results were not different from the results of healthy subjects and show that liver disease has no effect on the availability and clearance of oral artemisinin, indicating that artemisinin has an intermediate hepatic extraction ratio and that there is no significant first pass effect.

Administration, Oral↗