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PubMed2004

Comparative analysis of passive dosimetry and biomonitoring for assessing chlorpyrifos exposure in pesticide workers.

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the US Environmental Protection Agency (EPA) has the authority to regulate the use of pesticides to prevent unreasonable adverse human health effects associated with pesticide exposure. Accordingly, the EPA requires pesticide registrants to perform studies evaluating the potential for pesticide handler exposure. Data from five such studies that included exposure measurements based on both external measurements and biological monitoring were used to examine methods of assessment, routes and determinants of exposure and dose to the pesticide chlorpyrifos. Eighty workers across four job classes were included: mixer/loaders (M/L, n = 24), mixer/loader/applicators (M/L/A, n = 37), applicators (A, n = 9) and re-entry scouts (RS, n = 10). Results showed that doses were highly variable and differed by job class (P < 0.05) with median total (inhalation and dermal combined) exposure-derived absorbed doses (EDADtot) of 129, 88, 85 and 45 microg/application for A, M/L/A, M/L and RS, respectively. Doses derived from the measurement of 3,5,6-trichloro- 2-pyridinol (3,5,6-TCP) in urine were similar in magnitude but differed in rank with median values of 275, 189, 122 and 97 microg/application for A, M/L, RS, and M/L/A, respectively. The relative contribution of dermal to inhalation exposure was examined by their ratio. The median ratios of exposure-derived absorbed dermal dose (EDADderm) (assuming 3% absorption) to exposure-derived absorbed inhalation dose (EDADinh) (assuming 100% absorption) across job classes were 1.7, 1.5, 0.44 and 0.18 for RS, M/L, A and M/L/A, respectively, with an overall median of 0.6. For 34 of 77 workers (44%), this ratio exceeded 1.0, indicating the significance of the dermal exposure pathway. Different dermal absorption factor (DAF) assumptions were examined by comparing EDADtot to the biomarker-derived absorbed dose (BDAD) as a ratio where EDADtot was calculated assuming a DAF of 1, 3 and 10%. Median ratios of 0.45, 0.71 and 1.28, respectively, were determined suggesting the DAF is within the range of 3-10%. A simple linear regression of urinary 3,5,6-TCP against EDADtot indicates a positive association explaining 29% of the variability in the 3,5,6-TCP derived estimate of dose. A multiple linear regression model including the variables EDADderm, EDADinh and application type explained 46% of the variability (R2 = 0.46) in the urinary dose estimate. EDADderm was marginally significant (P = 0.066) while EDADinh was not (P = 0.57). The EDADderm regression coefficient (0.0007) exceeded the coefficient for EDADinh (0.00002) by a factor of 35. This study demonstrates the value of the pesticide registrant database for the purpose of evaluating pesticide worker exposure. It highlights the significance of the dermal exposure pathway, and identifies the need for methods and research to close the gap between external and internal exposure measures.

Agriculture↗
PubMed1993

Independent associations between plasma lipoprotein subfraction levels and the course of coronary artery disease in the St. Thomas' Atherosclerosis Regression Study (STARS).

Associations between plasma lipoprotein subfractions and changes in coronary artery diseases (CAD) were examined in 74 men who completed the St. Thomas' Atherosclerosis Regression Study (STARS). Plasma lipoproteins were isolated by stepwise, preparative ultracentrifugation at repeated intervals during the 38-month trial. Paired coronary angiograms were quantitatively analyzed by a computerized method. In univariate linear regression analysis, changes in mean absolute width (delta MAWS) and minimum absolute with (delta MinAWS) of coronary segments were significantly correlated with in-trial concentrations of cholesterol in intermediate-density lipoprotein ([IDL] d = 1.006 to 1.019 kg/L), low-density lipoprotein ([LDL2] d = 1.019 to 1.040 kg/L; LDL3, d = 1.040 to 1.063 kg/L), and high-density lipoprotein ([HDL3] d = 1.125 to 1.210 kg/L) subfractions; no significant associations were found with other lipoproteins. IDL, LDL3, and HDL3 cholesterol were then selected for multiple linear regression analysis because these variables were not co-correlated and because they attained a significance of P less than or equal to .1 in univariate regression. In this analysis, only LDL3 cholesterol level was a significant negative predictor (P < .05) of both delta MAWS and delta MinAWS; a positive association between delta MinAWS and HDL3 cholesterol level just failed to reach conventional statistical significance (P = .066). Correlations between changes in coronary luminal dimensions and LDL3 cholesterol level were independent of age, smoking, weight, and blood pressure. Most patients showing regression of coronary atherosclerosis had an LDL3 cholesterol level of less than 1.8 mmol/L. The findings suggest that LDL3 is the plasma lipoprotein subfraction that exerts the single most powerful effect on the course of CAD in middle-aged men with hypercholesterolemia.

Analysis of Variance↗
PubMedDate not supplied

Repeatability of replicate breath alcohol measurements collected in short time intervals.

The effect of short time interval sampling between replicate breath alcohol samples has been investigated. The results from 10 samples, which were collected approximately one minute apart from eight individuals and approximately 20 seconds apart from one individual, were evaluated by simple linear regression. The regression coefficient (slope) and its standard error were evaluated for the presence of any trend in alcohol depletion. Other statistical analyses were also included in this assessment. All nine subjects had linear regression coefficients for the end-expiratory results that were not significantly different from zero (P > 0.05). In view of the respiratory physiology, there does not appear to be any measurable depletion of breath alcohol concentration due to sampling intervals as short as one minute.

Alcohol Drinking↗
PubMed1999

Use of segmental tissue Doppler velocity to quantitate exercise echocardiography.

BACKGROUND: A quantitative technique is required to reduce the subjectivity and improve the reproducibility of stress echocardiography. Tissue Doppler imaging may offer these benefits, but its feasibility with exercise echocardiography (ExE) is undefined. This study sought the determinants of the exercise tissue Doppler velocity (TDV) response and the feasibility and accuracy of color TDV during ExE. METHODS AND RESULTS: Fifteen volunteers and 85 patients (age 60 +/- 10 years, 19 women) with known or suspected coronary artery disease were studied with standard 2-dimensional (2D) echocardiography and pulsed wave (PW) and color TDV before and after they underwent exercise treadmill testing. After the study PW TDV was measured in 6 basal segments, and off-line software was used to display color TDV data from all myocardial segments. Color TDV was compared with PW TDV in the basal segments at rest and stress with the use of linear regression. Color TDV in mid and basal segments was compared with wall motion on 2D echocardiography. The predictors of the TDV response to exercise were defined in a multiple linear regression. A logistic regression model was used to integrate clinical, exercise, and TDV variables for prediction of abnormal regional left ventricular function. Color and PW correlated well at rest (r = 0.81) and stress (r = 0.84), but PW was greater than color velocities at rest and stress. On the basis of 2D echocardiography, 752 myocardial segments were classified as normal in patients without evidence of coronary disease, 309 were normal in patients with abnormal wall motion in another territory, and 128 showed ischemia or scar. Segmental comparison of velocities assessed by color TDV showed that scar segments had a lower velocity than normal segments at rest and stress (P <.001). Ischemic segments had a lower peak TDV and less increment in velocity than normal segments. Heart rate, functional capacity, and regional dysfunction (scar or ischemia) were independent predictors of TDV at peak exercise. With the use of receiver operating characteristic analysis, the "correction" of TDV by these other variables increased the accuracy of the technique for the detection of regional left ventricular dysfunction. CONCLUSION: Color TDV is feasible during ExE. The correlation found between TDV and wall motion analysis of experienced observers indicates that TDV may be useful as a quantitative tool for interpretation of ExE.

Blood Flow Velocity↗
PubMed1999

External beam radiotherapy for painful osseous metastases: pooled data dose response analysis.

PURPOSE: Although the effectiveness of external beam irradiation in palliation of pain from osseous metastases is well established, the optimal fractionation schedule has not been determined. Clinical studies to date have failed to demonstrate an advantage for higher doses. To further address this issue, we conducted a pooled dose response analysis using data from published Phase III clinical trials. METHODS AND MATERIALS: Complete response (CR) was used as an endpoint because it was felt to be least susceptible to inconsistencies in assessment.The biological effective dose (BED) was calculated for each schedule using the linear-quadratic model and an alpha/beta of 10. Using SAS version 6.12, the data were fitted using a weighted linear regression, a logistic model, and the spline technique. Finally, BED was categorized, and odds ratios for each level were calculated. RESULTS: CR was assessed early and late in 383 and 1,007 patients, respectively. Linear regression on the early-response data yielded a poor fit and a nonsignificant dose coefficient. With the late-response data, there was an excellent fit (R-square = 0.842) and a highly significant dose coefficient (p = 0.0002). Fitting early CR to a logistic model, we could not establish a significant dose response relationship. However, with the late-response data there was an excellent fit and the dose coefficient was significantly different from zero (0.017 +/- 0.00524; p = 0.0012). Application of the spline technique or removal of an outlier resulted in an improved fit (p = 0.048 and p = 0.0001, respectively). Using BED of < 14.4 Gy as a reference level, the odds ratios for late CR were 2.29-3.32 (BED of 19.5-51.4 Gy, respectively). CONCLUSION: Our results demonstrate a clear dose-response for pain relief. Further testing of high intensity regiments is warranted.

Bone Neoplasms↗
PubMed2001

Evolution of invertase activity in honey over two years.

Invertase activity is a good parameter for evaluating honey freshness. Invertase activity evolution was determined on 57 fresh, unheated, commercially purchased Galician (northwestern Spain) floral honey samples. All honeys were stored in darkness at room temperature for up 24 months and analyzed each 6 months so as to determine the invertase activity evolution tendency for the first time. Invertase activity analysis was carried out according to Siegenthaler's method and in a simple assay, the latter showing a good precision (coefficient of variation between 0.35 and 0.66%). Initial invertase activity mean value was 163.9 (48.4-251.0) micromol of 4-nitrophenyl-alpha-D-glucopyranoside hydrolyzed/kg of honey/min. After application of the SPSS statistical package, the values of invertase activity showed five types of temporal behavior: exponential (56% of samples), linear (25% of samples), logarithmic (11% of samples), inverse (5% of samples), and quadratic (3% of samples). Linear regression equations were used to predict the invertase activity at 6, 12, 18, and 24 months from the initial Galician honeys' invertase activities; no statistical differences were found between experimental data and the activities calculated from the linear regression equations.

Food Preservation↗
PubMed1994

EEGs in cognitive stages of Alzheimer's-type dementia.

The purpose of this study was to evaluate electroencephalogram (EEG) changes in various stages of dementia of the Alzheimer's type (DAT) through comparison with normal persons of the same age and gender. The study included 20 patients with DAT in four cognitive stages as defined by the Global Deterioration Scale (GDS) and a control group of 20 age- and gender-matched individuals without DAT. The EEGs were recorded using a Grass Model C7 Polygraph instrument and analyzed for number of alpha, beta, delta and theta waves in four leads. Statistical analysis included two-way analysis of variance (ANOVA), multiple linear regression and profile analysis. Alpha and theta waves were significant when comparing persons with DAT and control participants (p = 0.05). Delta waves were significant for group, gender and lead placement (p = 0.012). Linear regression showed a high significance between cognitive stage of the participant and alpha (p = 0.000), theta (p = 0.000) and delta (p = 0.005) waves.

Aged↗
PubMed1999

Cognitive function and endogenous sex hormones in older women.

OBJECTIVE: To determine if endogenous hormone levels predict cognitive function in older women. DESIGN: A longitudinal, population-based study. SETTING: Rancho Bernardo, California PARTICIPANTS: A total of 393 community-dwelling women aged 55 to 89 years who were not using replacement estrogen. METHODS: Between 1984 and 1987, sera were collected for measurement of total and bioavailable testosterone, total and bioavailable estradiol, and estrone. Between 1988 and 1991, 12 standard neuropsychological tests were administered, including two items from the Blessed Information-Memory-Concentration Test, three measures of retrieval from the Buschke-Fuld Selective Reminding Test, a category fluency test, immediate and delayed recall from the Visual Reproduction Test, the Mini-Mental State Examination (MMSE) with individual analysis of the Serial 7's and the "World" Backwards components, and the Trail-Making Test part B (Trails B). The association between the five hormones and the 12 cognitive function tests was tested in age- and education-adjusted analyses using linear regression, partial correlation, quintile and categorical analyses. RESULTS: Women with better MMSE scores (>23) had significantly higher adjusted mean total and bioavailable testosterone levels (P = .009; P = .02, respectively). Using linear regression, the mean total testosterone was significantly associated with better performance on the World component of the MMSE (b = .12; P = .08). With regard to estrogen, the only statistically significant (P = .02) association was better performance on one test in women with very low levels of estradiol. CONCLUSIONS: In these older women, higher endogenous estrogen levels were not associated with significantly better performance on any cognitive function test. In contrast, higher levels of testosterone predicted better categorical performance on the MMSE and the World component of the MMSE. These novel findings warrant further research.

Age Factors↗
PubMedDate not supplied

Prediction of soil sorption coefficient of a diverse set of organic chemicals from molecular structure.

A correlation study based on simple structural descriptors for predicting the soil sorption coefficient, log K(oc), of a diverse set of 568 organic compounds is presented. Using a training set of 403 compounds, in which the log K(oc) values were in the range 0-6.5, multiple linear regression (MLR) was utilized to build the models. The models were validated using a test set of 165 chemicals not included in the training set. The statistics for a linear regression model with calculated aqueous solubility, log S, were r(2) = 0.80 and s = 0.51 in the training set, and r(2) = 0.76 and s = 0.61 in the test set. The model parameters used allow rapid and accurate calculation of log K(oc) values for a diverse set of organic chemicals, and propose the importance of molecular solubility, lipophilicity, size, flexibility, and ionization for a chemicals' sorption to organic soil material.

Journal Article↗
PubMed2000

Coffee consumption and decreased serum gamma-glutamyltransferase: a study of middle-aged Japanese men.

The potential inverse association between coffee intake and serum gamma-glutamyltransferase (GGT) was examined in a cross-sectional study involving 1353 Japanese male office workers aged 35-59 years in Osaka, Japan. Those who had serum aminotransferases exceeding the normal range and/or who had been administered medical care for, or had a past history of, liver disease were excluded. Multiple linear regression analysis and analysis of covariance were used to control for confounding variables (age, body mass index, alcohol use, and cigarette smoking) and to examine possible interactions. From the linear regression analysis, coffee intake was inversely related to serum GGT levels independently of age, body mass index, alcohol intake, and cigarette smoking. All of the latter variables were also independently and positively associated with serum GGT levels. When the interactions between coffee and each of four covariates on serum GGT were evaluated by adding each interaction term to the above regression model, significant negative interactions were observed for age and cigarette smoking. From the analysis of covariance, lower levels of serum GGT associated with coffee consumption were more evident in the older age group and at the higher levels of cigarette smoking. These findings suggest that coffee consumption is inversely related to serum GGT and that coffee may inhibit the inducing effects of aging and possibly of smoking on serum GGT in the liver.

Adult↗
PubMed2003

Alternative site blood glucose testing: a multicenter study.

The aim of this study was to compare glucose measurements between fingertip and forearm using the blood glucose (BG) monitoring system One Touch Ultra (LifeScan), an electrochemical sensor that requires only a very small drop of blood (1 microL). Patients with type 1 or type 2 diabetes were identified in five outpatient diabetes clinics. Participants were requested to use the One Touch Ultra at home for 1 week for the measurement of BG levels from both sites. Patients filled in a questionnaire about their experience with testing blood samples from fingertip and forearm. The agreement between the measurements from the two sites was assessed using linear regression analysis, mean absolute relative error (MARE), the Bland-Altman method, and Error Grid Analysis (EGA). Overall, 112 patients were recruited, of whom 58% had type 1 diabetes. Linear regression analysis showed an intercept of 17.7, statistically different from 0 (p<0.0001). The slope was 0.956, and the Pearson correlation coefficient was 0.95. A MARE of 12.1% (SD=11.8%) was obtained, with a greater deviation of the forearm values from the fingertip ones in the hypoglycemic range (MARE=22.3%; SD=21.7%). The Bland-Altman bias plot showed a mean bias of 10.2 mg/dL (SD=23.1), with no correlation between mean difference and average BG levels (r=0.02). The EGA showed that 89.2% of the values fell in zone A, 10.4% in zone B, and 0.4% in zone C. The vast majority of patients (71%) declared that the collection of blood from the forearm caused no pain or less pain than the traditional site. Only 17% of the patients declared that it was impossible to obtain any blood from the forearm, while 63% reported with satisfaction that the quantity requested was small. At the end of the study period, 32% of the participants indicated the forearm as the preferred test site. Alternative site testing on the arm, with a BG meter that requires only a very small drop of blood, is feasible and reliable under routine clinical conditions. When testing with the express purpose of detecting hypoglycemia, the finger still remains the recommended test site.

Adolescent↗
PubMed1996

Clinical laboratory investigation of the Sanofi ACCESS CK-MB procedure and comparison to electrophoresis and Abbott IMx.

This evaluation was undertaken to verify the application protocol for the CK-MB assay on the ACCESS Immunoassay Analyzer (Sanofi Diagnostics Pasteur, Chaska, MN). The results show that the ACCESS CK-MB assay total imprecision was 6.8% to 9.1%. Analytical linearity of the ACCESS CK-MB assay was excellent in the range of < 1-214 micrograms/L. A comparison of the ACCESS CK-MB assay with the IMx (Abbott Laboratories, Abbott Park, IL) method shows good correlation r = 0.990 (n = 108). Linear regression analysis yielded Y = 1.36X-0.3, Sx/y = 7.2. ACCESS CK-MB values also correlated well with CK-MB by electrophoresis with r = 0.968 (n = 132). The linear regression equation for this comparison was Y = 1.08X + 1.4, Sx/y = 14.1. The expected non-myocardial infarction range of CK-MB determined by the ACCESS system was 1.3-9.4 micrograms/L (mean = 4.0, n = 58). The ACCESS CK-MB assay would appear to be rapid, precise and clinically useful.

Adolescent↗
PubMed1997

Metabolic determinants of the age-related improvement in one-mile run/walk performance in youth.

We examined the metabolic determinants of the age-related improvement in 1-mile run/walk (MRW) performance in boys and girls. Treadmill VO2peak (ml.kg-1.min-1), running economy (VO2 in ml.kg-1.min-1 at 8 km.h-1; VO2econ), and %VO2peak used during a simulated MRW were determined in 92 boys and 53 girls, 7-17 yr of age. Simple linear regression analyses indicated that MRW time decreased 0.52 min.y-1, VO2econ decreased 1.0 ml.kg-1.min-1.y-1, %VO2peak increased 1.5%.y-1, and no significant change occurred in VO2peak. Multiple linear regression analyses indicated that the increase in %VO2peak used during the run accounted for about 42% of the decrease in MRW time with age. With the effects of VO2peak and %VO2peak held constant, the improvement in VO2econ accounted for an additional 31% of the age-related decrease in MRW time. We conclude that the age-related improvement in MRW performance in youth is explained primarily by an increase in the %VO2peak used during the MRW and improvement in VO2econ. Age-related changes in MRW time should not be used to infer changes in VO2peak.

Adolescent↗
PubMed2005

Impairment of visual acuity and reading performance and the relationship with cataract type and density.

PURPOSE: To evaluate the association between the density of nuclear, cortical, and posterior subcapsular lens opacities and visual impairment in patients with cataract. METHODS: In 80 patients, visual acuity and reading performance were evaluated 1 day before and 4 weeks after cataract surgery. Cataracts were categorized and graded according to the Lens Opacities Classification System (LOCS) III of nuclear color (NC), nuclear opalescence (NO), cortical (C), and posterior subcapsular cataract (P). A multiple linear regression analysis and partial correlation coefficients were calculated. Data were also checked for significant pre- and postoperative differences in visual performance related to cataract grading. RESULTS: In the multiple linear regression analysis, significant associations were found between the improvement in visual acuity and reading performance after cataract surgery and the NC, NO, and P scores (P < 0.001); no significant association was found for the C score (P > 0.05). High partial correlation coefficients were found between the P score and the preoperative visual acuity (r = 0.6; P < 0.001), reading acuity (r = 0.74; P < 0.001), and maximum reading speed (MRS; r = -0.77; P < 0.001). Significant but lower partial correlation coefficients were found for the NO score. No significant partial correlation coefficients were found for the NC and C score. Significant pre- and postoperative differences in MRS were found in patients with P scores > or =3 or NO and NC scores > or =5, representing functionally relevant impairment. CONCLUSIONS: A strong association was found between visual impairment in patients with cataract and the severity of posterior subcapsular cataract (PSC) and nuclear opacity. Particularly in patients with PSC, deficits in reading performance significantly increased. The functionally relevant deficits in patients with P scores > or =3 or NO and NC scores > or =5, should be carefully considered for planning cataract surgery or visual rehabilitation.

Aged↗
PubMed1992

The correlation between serum selenium and blood selenium in cattle.

The selenium (Se) concentration of paired blood and serum samples from cattle was determined by 2 methods: 1) atomic absorption spectroscopy using hydride generation (HG-AAS), and 2) inductively coupled argon plasma emission spectroscopy using hydride generation (ICP). Samples from 327 cattle were analyzed by HG-AAS, and samples from 344 cattle were analyzed by ICP. The data were examined by linear regression analysis, and the technique of inverse prediction was utilized to determine prediction intervals for estimating blood Se concentration from known serum Se concentration. The correlation coefficients, by simple linear regression of serum Se on blood Se, were 0.79 (r2 = 0.62) and 0.88 (r2 = 0.77) for the HG-AAS data and the ICP data, respectively. For the HG-AAS data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was [formula; see text]. For the ICP data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was [formula; see text]. The prediction intervals were quite wide, and the accuracy of estimating blood Se from a known serum Se was not useful for diagnostic purposes. The use of serum Se concentration to assess nutritional status of cattle with respect to Se does not appear to be appropriate.

Animals↗
PubMed2002

Protein kinase C activity and the relations between blood lead and neurobehavioral function in lead workers.

At picomolar concentrations, lead activates protein kinase C (PKC). This activation has been implicated in the neurotoxicity of lead. No prior study has evaluated the association of PKC activity with neurobehavioral function in humans. The purpose of this study was to determine whether PKC activity is associated with neurobehavioral function or modifies the relationship between blood lead levels and neurobehavioral test scores. In this cross-sectional study of 212 current lead workers in the Republic of Korea, we assessed blood lead levels, neurobehavioral test scores, and PKC activity. PKC activity was determined by measuring the levels of phosphorylation of three erythrocyte membrane proteins (spectrin and the 52-kDa and 48-kDa subunits of band 4.9), using an in vitro back-phosphorylation assay. When linear regression was used to control for confounding variables, blood lead was a significant predictor of decrements in performance on tests of psychomotor function, manual dexterity, and executive ability. In linear regression models, back-phosphorylation levels were not associated with neurobehavioral test scores, but when dichotomized at the median, back-phosphorylation levels modified the relationship between blood lead and test scores. For spectrin and the 52-kDa and 48-kDa subunits of band 4.9, 5, 2, and 5 of 14 interaction terms, respectively, had associated p-values less than 0.10, all with positive signs, indicating that blood lead was associated with worse test scores only in subjects with lower back-phosphorylation levels. These data indicate that blood lead levels are associated with decrements in neurobehavioral test scores, mainly in the domains of manual dexterity and psychomotor function, but only in subjects with lower in vitro back-phosphorylation levels, which is equivalent to higher in vivo PKC activity. We hypothesize that subjects with higher PKC activity in the presence of lead may be more susceptible to the health effects of lead.

Adult↗
PubMed1990

Tackling the non-linearizeable dose-response relationship in clotting time assays of heparin.

Heparin sodium was assayed by turbidimetric measurement of the clotting time of bovine citrate plasma with thromboplastin, between the moment of recalcification and the moment of maximal speed of polymerization of the fibrinogen monomer, as marked by the turning-point of the trace of the turbidimetric record. Most assays were practiced in the range of 0.2-2.0 units per test volume. The lower end of the range could be extended by decreasing the thromboplastin dose, the higher end by increasing this dose. The dose-response relationship for heparin sodium, i.e. between the nominal heparin activity x and the clotting time y, was non-linear in such a way that no uniform mathematical transformation could provide a valid linearization over the whole range. A non-linear regression in the form of a cubic fit, applied to the data pairs (x, y) of both standard and test sample, proved to be satisfactory. The two non-linear regression curves were compared at varying levels of x by computing the quotient of nominal and actual activity for equal clotting times, and by computing the quotient of the slopes (tangents) of the curves for these times. The percentual deviation of the test sample potency from the standard's potency as obtained from the former quotient was termed Za, and the deviation as computed from the latter quotient was termed Ztg, Za and Ztg as functions of x were plotted and were found to intersect invariably at critical points of Za(x) within the range of the experiment. This seems to be a theorem.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

Tests of efficacy of antidotes for removal of methylmercury in human poisoning during the Iraq outbreak.

Three complexing agents and a thiolated resin were tested for their ability to reduce the T 1/2 of methylmercury in blood during an outbreak of human poisoning. The slope of the line relating the natural logarithm of the blood concentration to time during treatment was calculated by a parametric (linear regression) and a nonparametric (two-point) method. The mean slope for each treatment group was calculated and the T 1/2 was calculated from the mean slope. Both the linear regression and two-point methods yield similar mean values. The "two-point" T 1/2 will be quoted here. The mean T 1/2 in six patients receiving no specific treatment was 65 days and in 10 patients receiving placebo was 61 days, and these values did not differ from those reported in the literature. All four treatments significantly reduced the mean T 1/2 values below the mean for the combined placebo and no treatment groups. Sodium 2,3-dimercaptopropane-1-sulfonate was the most effective agent, reducing the mean T 1/2 in 10 patients to 10 days. The thiolated resin given to eight patients produced a mean T 1/2 of 20 days. The penicillamines also produced a significant reduction in T 1/2 values; the mean T 1/2 for D-penicillamine in 12 patients was 26 days and N-acetyl-DL-penicillamine in 17 patients yielded a mean T 1/2 of 24 days. This is the first report of the effects of sodium 2,3-dimercaptopropane-1-sulfonate and resin in human subjects exposed to methylmercury. No adverse effects were observed in any of the treatment groups. A clinical trial was not possible but it is concluded that agents that reduce blood levels and accelerate excretion are probably clinically useful if given before irreversible damage has occurred.

Adolescent↗