Simultaneous absorption of UV-vis and circular dichroism to measure enantiomeric concentrations of praziquantel under nonlinear conditions

Beer-Lambert-Bouguer law is for a limiting case and, therefore, it is not useful to describe the relationship between absorption signal and enantiomer concentration in a stream when there are nonlinear phenomena present. In this work, the Chiral Detector (CD-2095 JASCO) equipment was used to measure simultaneously the UV-Vis and circular dichroism (CD) signals of a stream with different compositions of praziquantel enantiomers. The tested models were calibrated (parameter estimation) and validated using the Leave-One-Out Cross Validation (LOOCV) method. Both UV-vis and CD signals were absorbed differently in mixtures in comparison to pure solutions, indicating a nonlinear relationship between the absorbed signal and the enantiomer concentration in a mixture stream. Empirical mathematical relationships were tested for each signal (UV-vis and CD) and the pair of equations was evaluated using the Mean Square Error (MSE) metric for each enantiomer concentration (MSE_L and MSE_D) and the pair of equations with the smallest MSE_t (=MSE_L + MSE_D) metric was chosen. Confidence interval analysis helped to find even simpler equations in comparison to the chosen ones. Higher nonlinearity was observed for a mixture with low L-PZQ concentration. The developed methodology allowed the choice of an empiric model to give good predictions in a wide range of concentration, what is of utmost importance for monitoring and automatic control purposes, for instance.

Otorhinolaryngological and esophageal manifestations of epidermolysis bullosa

Epidermolysis bullosa (EB) is a group of skin diseases with different clinical manifestations and varied inheritance patterns. Blisters may appear spontaneously or following minimal trauma to the skin or mucosa.

Aim

this paper aims to describe the otorhinolaryngological manifestations and esophageal complications related to EB, and the experience in treating patients with esophageal stenosis secondary to this disease.

Materials and method

this descriptive study enrolled 60 patients with EB seen from June 1999 to December 2006 at the Head and Neck Surgery Service of X Hospital, a reference center for EB.

Results

the patients’ mean age was 14.5 years. Twenty-eight (46.6%) were females and 32 (53.4%) were males. Eight (13.4%) were diagnosed with epidermolysis bullosa simplex, while 51 (85%) had epidermolysis bullosa dystrophica; one (1.6%) patient had one acquired EB. Lips, mouth, tongue and ears were the most frequently involved sites (32 patients - 53.3%). Dysphagia was found in 28 patients (46.6%). After esophageal dilatation the symptoms subsided.

Conclusion

EB is a rare disease and patients must be sent for treatment at reference centers. Physicians treating patients for EB must be aware of the measures required to improve the quality of the treatment provided without putting the patients in harm’s way.

[Contributions to the neuropsychology of executive behavior: performance of normal individuals on the Tower of London and Wisconsin tests]

The concept of "executive behavior" encompasses a set of abilities which are critical for the organization of thought and behavior. To test the hypothesis that executive behavior is composed of multiple modules we investigated the performance of 61 normal adults on two widely used executive tasks, the Wisconsin Card Sorting (WCST) and the Tower of London (TOL) tests. We hypothesized that if executive behavior were composed of multiple modules, the main dimensions of each task would be weakly, if at all, statistically related. We also tested the hypothesis that occupational functioning would be related to executive performance. Our results revealed no significant association between the WCST and TOL tasks, favoring the idea that executive behavior is made up of multiple neuropsychological dimensions. Secondly, men fared significantly better than women on the difficult (4 and 5-moves) TOL puzzles. Finally, there was a significant association between performance on the difficult TOL puzzles and level of occupational functioning. These findings may explain certain dissociations in executive behavior commonly observed in patients with focal or diffuse brain damage. If replicated, they might be useful in the prediction of success in cognitive rehabilitation programs.

Trail making and cognitive set-shifting

We tested the hypothesis that Part B of the Trail Making Test (TMT) is a measure of cognitive set-shifting ability in 55 normal subjects with the conventional (written) TMT and a verbal adaptation, the "verbal TMT" (vTMT). The finding of a significant association between Parts B of TMT and vTMT (r = 0,59, p < 0,001), after correcting for age and education, supports the view that Part B of TMT is a valid measure of the ability to alternate between cognitive categories.

Functional MRI correlates of real and imagined tool-use pantomimes

OBJECTIVE

To study the pattern of cerebral activation related to the performance of tool-use pantomimes with functional MRI (fMRI) using a task-subtraction design.

BACKGROUND

Tool use comprises a particular category of transitive actions. Inability to pantomime the use of tools has been classically associated with retrorolandic dominant hemisphere damage. However, where in the left hemisphere these transitive representations are generated is unclear.

METHODS

Echoplanar images were acquired in eight alternating task and control periods. Sixteen right-handed normal adults pantomimed the use of common tools and utensils with each hand. The control condition consisted of a sequence of nonsymbolic complex movements of forearm, hand, and fingers at a self-paced rate. Eight individuals also imagined the execution of the real task and control actions. A repeated measures ANOVA compared activations in five regions of interest in each hemisphere.

RESULTS

Regardless of which hand was used, the left hemisphere was more active than the right in both real (p < 0.02) and imagined (p < 0.04) tasks. Activations clustered in the left intraparietal cortex and posterior dorsolateral frontal cortex.

CONCLUSIONS

Pantomiming the use of tools is associated with activation of the left intraparietal cortex and dorsolateral frontal cortex. The left intraparietal cortex may store the representations of tool-use formulae, whereas the dorsolateral frontal cortex activation may reflect the switching between innervatory motor programs.