FTIR, 1H NMR,ESR, TGA and DTA Analysis of Trithiocarbonates of Captopril and 6‐Mercaptopurine as Their Palladium(II) Chloride Complexes

A simple and sensitive spectrophotometric method has been developed for the determination of the antihypertensive drug captopril and anticancer drug 6‐mercaptopurine, in their trithiocarbonate (TTC) form by using Pd(II) chloride as a coloring reagent. Captopril TTC forms a stable dark yellow colored complex with λ_max 383 nm, molar absorption coefficient 1.35 × 10⁵ l/mole/cm and a Beer's law range from 0.084‐1.26 ppm. 6‐Mercaptopurine TTC forms a stable deep yellow colored complex with λ_max 345 nm, molar absorption coefficient 6.9 × 10⁵ l/mole/cm and a Beer's law range from 0.0319 ppm to 3.519 ppm. The M: L ratio of palladium: TTC complexes were confirmed by Job's method of continuous variance and mole ratio method and was found to be 1:1 for both captopril TTC as well as 6‐mercaptopurine TTC. In addition, on the basis of, FTIR, ¹H NMR, ESR and thermal analysis data a plausible structure of mononuclear Pd(II) complex of Captopril TTC and 6‐mercaptopurine TTC has been reported.     

EEG quality during simultaneous functional MRI of interictal epileptiform discharges

This article concerns the evaluation of the quality of interictal epileptiform EEG discharges recorded throughout simultaneous echo planar imaging (EPI). BOLD (blood oxygen level dependent) functional MRI (fMRI) images were acquired continuously on a patient with intractable epilepsy. EEG was sampled simultaneously, during and after imaging, with removal of pulse and imaging artifacts by subtraction of channel-specific running averages. Contiguous EEG epochs recorded with and without fMRI (fMRI+ve vs. fMRI−ve) were next randomized and presented to two blinded observers. Epileptiform discharges were identified retrospectively, and comparison was made in terms of the number of identified events, their amplitude, and spatiotemporal distribution. A spectral analysis was also performed on the EEG. In the randomized comparison of EEG segments, 80 (fMRI+ve) vs. 69 (fMRI−ve) discharges were noted with good interobserver agreement (69%). There were no significant differences in amplitude or spatio-temporal distribution. Comparison of the events detected and measured by two expert observers demonstrated that the Interictal Epileptiform Discharge (IED) characteristics were indistinguishable with and without scanning. We review briefly the existing literature on EEG recording quality for combined EEG/fMRI.     

Modelling large motion events in fMRI studies of patients with epilepsy

EEG-correlated fMRI can provide localisation information on the generators of epileptiform discharges in patients with focal epilepsy. To increase the technique's clinical potential, it is important to consider ways of optimising the yield of each experiment while minimizing the risk of false-positive activation. Head motion can lead to severe image degradation and result in false-positive activation and is usually worse in patients than in healthy subjects. We performed general linear model fMRI data analysis on simultaneous EEG-fMRI data acquired in 34 cases with focal epilepsy. Signal changes associated with large inter-scan motion events (head jerks) were modelled using modified design matrices that include 'scan nulling' regressors. We evaluated the efficacy of this approach by mapping the proportion of the brain for which F-tests across the additional regressors were significant. In 95% of cases, there was a significant effect of motion in 50% of the brain or greater; for the scan nulling effect, the proportion was 36%; this effect was predominantly in the neocortex. We conclude that careful consideration of the motion-related effects in fMRI studies of patients with epilepsy is essential and that the proposed approach can be effective.     

The MR detection of neuronal depolarization during 3-Hz spike-and-wave complexes in generalized epilepsy

Previously, an analysis of activations observed in a patient with idiopathic generalized epilepsy using electroencephalogram-correlated functional magnetic resonance imaging (MRI) during runs of 3-Hz generalized spike–wave discharge (GSWD) was presented by Salek-Haddadi. Time-locked, bilateral, thalamic blood oxygenation level-dependent increases were reported to be accompanied by widespread, symmetric, cortical deactivation with a frontal maximum. In light of recent investigations into MRI detection of the magnetic field perturbations caused by neuronal current loops during depolarization, we revisited the analysis of the data of Salek-Haddadi as a preliminary search for a neuroelectric signal. We modeled the MRI response as the sum of a fast signal and a slower signal and demonstrated significant MRI activity at a time scale of the order of 30 ms associated with GSWDs. Further work is necessary before firm conclusions may be drawn about the nature of this signal.     

Mapping of spikes, slow waves, and motor tasks in a patient with malformation of cortical development using simultaneous EEG and fMRI

We report on the simultaneous and continuous acquisition of EEG and functional MRI data in a patient with a left hemiparesis and focal epilepsy secondary to malformation of cortical development in the right hemisphere. EEG-triggered fMRI localization was previously demonstrated in this patient. In the experiments reported here, 322 spikes maximum at electrode C4 and 126 focal slow waves were identified offline. A hierarchy of models was explored in order to assess the relative contributions of each type of EEG event. Modeling the BOLD response to C4 spikes alone showed an area of activation within the large malformation, adjacent to the area of infolding cortex. However, also modeling slow-waves gave rise to a broader and stronger activation, suggesting that the generators overlap. Motor mapping of the right hand showed activation in the left sensorimotor cortex; left-hand tapping led to a more diffuse area of activation, displaced superiorly into the superior frontal gyrus, and a small area of activation within the lesion. In conclusion, continuous EEG-fMRI is useful to compare the functional mapping of epileptiform activity and eloquent cortices in individual patients.