Impact of Smoking and Chewing Tobacco on Arsenic-Induced Skin Lesions

BACKGROUND: We recently reported that the main reason for the documented higher prevalence of arsenic-related skin lesions among men than among women is the result of less efficient arsenic metabolism. OBJECTIVE: Because smoking has been associated with less efficient arsenic methylation, we aimed to elucidate interactions between tobacco use and arsenic metabolism for the risk of developing skin lesions. METHODS: We used a population-based case-referent study that showed increased risk for skin lesions in relation to chronic arsenic exposure via drinking water in Bangladesh and randomly selected 526 of the referents (random sample of inhabitants > 4 years old; 47% male) and all 504 cases (54% male) with arsenic-related skin lesions to measure arsenic metabolites [methylarsonic acid (MA) and dimethylarsinic acid (DMA)] in urine using high-performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICPMS). RESULTS: The odds ratio for skin lesions was almost three times higher in the highest tertile of urinary %MA than in the lowest tertile. Men who smoked cigarettes and bidis (locally produced cigarettes; 33% of referents, 58% of cases) had a significantly higher risk for skin lesions than did nonsmoking men; this association decreased slightly after accounting for arsenic metabolism. Only two women smoked, but women who chewed tobacco (21% of referents, 43% of cases) had a considerably higher risk of skin lesions than did women who did not use tobacco. The odds ratio (OR) for women who chewed tobacco and who had < or = 7.9%MA was 3.8 [95% confidence interval (CI), 1.4-10] compared with women in the same MA tertile who did not use tobacco. In the highest tertile of %MA or %inorganic arsenic (iAs), women who chewed tobacco had ORs of 7.3 and 7.5, respectively, compared with women in the lowest tertiles who did not use tobacco. CONCLUSION: The increased risk of arsenic-related skin lesions in male smokers compared with nonsmokers appears to be partly explained by impaired arsenic methylation, while there seemed to be an excess risk due to interaction between chewing tobacco and arsenic metabolism in women

Experimental studies in cue probability learning

Härtill 9 delar.digitalisering@um

Omission of feedback in single-cue probability learning

Brehmer,B.,and Lindberg, L. Omission of feedback in single-cue probability learning. Umeå Psychological Reports, No. 46, 1971. - The effects of the omission of feedback in single-cue probability learning was studied as a function of the sign and magnitude of the correlation between cue and criterion variables, the magnitude of the slope relating the criterion values to the cue values, and the magnitude of the unaccounted for variance in the task in three experiments. Replicating earlier findings, the results of these experiments show that the omission of feedback results in an increase in the correlations between cues and judgments. This increase in correlations is due to an increase in the slopes of the regression lines relating the subjects' judgments to the cue values.digitalisering@um

Effects of task information and active feedback control in inductive inference

Lindberg, L-Å., and Brehmer, B. Effects of task information and active feedback control in inductive inference. Umeå Psychological Reports No. 123, 1977. - Learning of an inductive task with one linear and one quadratic cue was investigated in a 2 (levels of task information: maximum vs. minimum) x 2 (control of outcome feedback: active vs.passive) x H (blocks of trials) factorial experiment. In the maximum information condition subjects were given the criterion distribution, including the mean, for each combination of cue values. Under the active feedback condition subjects selected cue combinations and feedback instances in whatever order they wanted. Positive effects of all three factors were obtained with respect to subjects'selection of inference rules and level of task control. It was concluded that subjects' inconsistency under ordinary outcome feedback conditions is due in part to lack of memory capacity and in part to the fact that subjects are prevented from active hypothesis testing. However,these factors do not fully explain the lack of consistency as shown by the fact that subjects under the present maximal information/active feedback condition did not reach the maximal level of task control, although they used the optimal inference rules.digitalisering@um

Effects of task information and active feedback control in inductive inference

Lindberg, L-Å., and Brehmer, B. Effects of task information and active feedback control in inductive inference. Umeå Psychological Reports No. 123, 1977. - Learning of an inductive task with one linear and one quadratic cue was investigated in a 2 (levels of task information: maximum vs. minimum) x 2 (control of outcome feedback: active vs.passive) x H (blocks of trials) factorial experiment. In the maximum information condition subjects were given the criterion distribution, including the mean, for each combination of cue values. Under the active feedback condition subjects selected cue combinations and feedback instances in whatever order they wanted. Positive effects of all three factors were obtained with respect to subjects'selection of inference rules and level of task control. It was concluded that subjects' inconsistency under ordinary outcome feedback conditions is due in part to lack of memory capacity and in part to the fact that subjects are prevented from active hypothesis testing. However,these factors do not fully explain the lack of consistency as shown by the fact that subjects under the present maximal information/active feedback condition did not reach the maximal level of task control, although they used the optimal inference rules.digitalisering@um

Subjects' selection of feedback information in an inductive inference task

Lindberg, L-Å.,and Brehmer, B. Subjects' selection of feedback information in an inductive inference task. Umeå Psychological Reports No. 122, 1977. - Subjects' selection of outcome feedback instances in a probabilistic inference task with one linear and one nonlinear cue was investigated in a 2 (levels of task information: maximum vs. minimum) x 4 (blocks of trials) factorial experiment. Maximal information included the criterion distribution for each cue combination as well as aids for recording feedback instances, while minimal information consisted of standard instructions and no memory aids. Under both information conditions, subjects (1) examined one cue at a time, (2) gave priority to the more difficult quadratic cue, and (3) systematically changed their distribution and order of selections as a function of blocks.That is, subjects used the feedback infornation in a way that is not possible in the standard experimenter controlled reception paradigm. Furthermore, subjects made consequtive selections of the same cue combination more frequently in the maximum information condition that in the minimum information condition. These results are consistent with the assumptions that subjects under both conditions try to find the functional parameters of the task by means of a hypothesis testing activity, and that they learn to eliminate incorrect hypotheses with practice.digitalisering@um

Progression and hypothesis testing in an inductive inference task

Lindberg, L-Å., &amp; Brehmer, B. Progression and hypothesis testing in an inductive inference task. Umeå Psychological Reports No. 121, 1977. - Subjects performance in a two-cue inference task was studied in three experiments as a function of (1) relative cue complexity, (2) relative cue validity, (3) task predictability, and (4) cue-criterion function form.Cues were defined through the velocity (more complex) and starting position (less complex) of a moving light spot. Results indicate that while relative cue complexity does not affect performance, the statistical structure of the task determines subjects' relative cue weighting as well as the final level of task control. These results contradict the Progression hypothesis, formulated for perceptual-motor skill development in tracking, and are consistent with earlier studies within the regression-correlation paradigm.digitalisering@um

Evaluation of ultrasound Tissue Velocity Imaging : a phantom study of velocity estimation in skeletal muscle low-level contractions

Background: Tissue Velocity Imaging (TVI) is an ultrasound based technique used for quantitative analysis of the cardiac function and has earlier been evaluated according to myocardial velocities. Recent years several studies have reported applying TVI in the analysis of skeletal muscles. Skeletal tissue velocities can be very low. In particular, when performing isometric contractions or contractions of low force level the velocities may be much lower compared to the myocardial tissue velocities. Methods: In this study TVI was evaluated for estimation of tissue velocities below the typical myocardial velocities. An in-house phantom was used to see how different PRF-settings affected the accuracy of the velocity estimations. Results: With phantom peak velocity at 0.03 cm/s the error ranged from 31% up to 313% with the different PRF-settings in this study. For the peak velocities at 0.17 cm/s and 0.26 cm/s there was no difference in error with tested PFR settings, it is kept approximately around 20%. Conclusions: The results from the present study showed that the PRF setting did not seem to affect the accuracy of the velocity estimation at tissue velocities above 0.17 cm/s. However at lower velocities (0.03 cm/s) the setting was crucial for the accuracy. The PRF should therefore preferable be reduced when the method is applied in low-level muscle contraction