Vibron Self--trapped States in Biological Macromolecules: Comparison of Different Theoretical Approaches

A study of the applicability of the variational treatments based on using of the modified Lang-Firsov unitary transformation (MLF method) in the investigation of the vibron self-trapped states in biological macromolecular chains are presented. We compare the values of the ground state energy predicted by MLF methods with the values of the ground state energy predicted by the standard small-polaron theory, for various values of the basic energy parameters of the system. We obtain regions in system parameter space where MLF approach gives better description of the vibron states.Comment: 8 pages, 4 figures, To appear in the Proceedings of Conference Dubna-Nano2012 (July 9 - 14, 2012

Contribution of the μ-opioid receptor system to affective disorders in temporal lobe epilepsy: A bidirectional relationship?

OBJECTIVE Affective disorders are frequent comorbidities of temporal lobe epilepsy (TLE). The endogenous opioid system has been implicated in both epilepsy and affective disorders, and may play a significant role in their bidirectional relationship. In this cross-sectional study, we investigated the association between μ-opioid receptor binding and affective disorders in patients with TLE. METHODS Nine patients with TLE and depression/anxiety underwent $^{11}$ C-carfentanil positron emission tomography (CFN PET) and neuropsychiatric assessment, including the Hospital Anxiety and Depression Scale and the Positive and Negative Affect Schedule. The normalized CFN PET scans were compared with those of 26 age-matched healthy controls. Correlation analyses with affective symptoms were performed by region of interest-based analysis focusing on the limbic circuit and orbitofrontal cortex. RESULTS We observed widely reduced CFN binding potential (BP) in bilateral frontal lobes and striata in patients with TLE compared to healthy controls. In the TLE group, more severe anxiety and negative affect were associated with decreased CFN BP in the posterior cingulate gyrus. SIGNIFICANCE In patients with TLE, interictally reduced binding in the opioid system was associated with higher levels of anxiety and negative affect. We speculate that seizure-related agonist-driven desensitization and downregulation of opioid receptors could be a potential underlying pathomechanism

Hippocampal profiling: Localized magnetic resonance imaging volumetry and T2 relaxometry for hippocampal sclerosis

Objective: Hippocampal sclerosis (HS) is the most common cause of drug‐resistant temporal lobe epilepsy, and its accurate detection is important to guide epilepsy surgery. Radiological features of HS include hippocampal volume loss and increased T2 signal, which can both be quantified to help improve detection. In this work, we extend these quantitative methods to generate cross‐sectional area and T2 profiles along the hippocampal long axis to improve the localization of hippocampal abnormalities. Methods: T1‐weighted and T2 relaxometry data from 69 HS patients (32 left, 32 right, 5 bilateral) and 111 healthy controls were acquired on a 3‐T magnetic resonance imaging (MRI) scanner. Automated hippocampal segmentation and T2 relaxometry were performed and used to calculate whole‐hippocampal volumes and to estimate quantitative T2 (qT2) values. By generating a group template from the controls, and aligning this so that the hippocampal long axes were along the anterior‐posterior axis, we were able to calculate hippocampal cross‐sectional area and qT2 by a slicewise method to localize any volume loss or T2 hyperintensity. Individual patient profiles were compared with normative data generated from the healthy controls. Results: Profiling of hippocampal volumetric and qT2 data could be performed automatically and reproducibly. HS patients commonly showed widespread decreases in volume and increases in T2 along the length of the affected hippocampus, and focal changes may also be identified. Patterns of atrophy and T2 increase in the left hippocampus were similar between left, right, and bilateral HS. These profiles have potential to distinguish between sclerosis affecting volume and qT2 in the whole or parts of the hippocampus, and may aid the radiological diagnosis in uncertain cases or cases with subtle or focal abnormalities where standard whole‐hippocampal measurements yield normal values. Significance: Hippocampal profiling of volumetry and qT2 values can help spatially localize hippocampal MRI abnormalities and work toward improved sensitivity of subtle focal lesions

Volumetric analysis of the piriform cortex in temporal lobe epilepsy

The piriform cortex, at the confluence of the temporal and frontal lobes, generates seizures in response to chemical convulsants and electrical stimulation. Resection of more than 50% of the piriform cortex in anterior temporal lobe resection for refractory temporal lobe epilepsy (TLE) was associated with a 16-fold higher chance of seizure freedom. The objectives of the current study were to implement a robust protocol to measure piriform cortex volumes and to quantify the correlation of these volumes with clinical characteristics of TLE. Sixty individuals with unilateral TLE (33 left) and 20 healthy controls had volumetric analysis of left and right piriform cortex and hippocampi. A protocol for segmenting and measuring the volumes of the piriform cortices was implemented, with good inter-rater and test-retest reliability. The right piriform cortex volume was consistently larger than the left piriform cortex in both healthy controls and patients with TLE. In controls, the mean volume of the right piriform cortex was 17.7% larger than the left, and the right piriform cortex extended a mean of 6 mm (Range: -4 to 12) more anteriorly than the left. This asymmetry was also seen in left and right TLE. In TLE patients overall, the piriform cortices were not significantly smaller than in controls. Hippocampal sclerosis was associated with decreased ipsilateral and contralateral piriform cortex volumes. The piriform cortex volumes, both ipsilateral and contralateral to the epileptic temporal lobe, were smaller with a longer duration of epilepsy. There was no significant association between piriform cortex volumes and the frequency of focal seizures with impaired awareness or the number of anti-seizure medications taken. Implementation of robust segmentation will enable consistent neurosurgical resection in anterior temporal lobe surgery for refractory TLE.

Palaeoenvironmental reconstruction of the Milna valley on the island of Vis (Central Adriatic) during the late Holocene.

This study provides a reconstruction of the 1.5 ka palaeoenvironmental evolution of the small, and presently dry, Milna valley on the island of Vis. Sediments from the valley were studied using multi-proxy approach, applying sedimentological, mineralogical, petrological, anthracological, malacological, 14C and land cover analyses, in regard to climatic, vegetation, and hydrological changes. The mineral composition of the siliciclastic detritus from the Milna valley points to the Dinaride Ophiolite Zone in Bosnia as its dominant source of origin, eroded by the Neretva River, and deposited in the form of alluvial sediments in the Central Adriatic area. However, Cetina and Drin Rivers may have also contributed some of the sediments. Regional aeolian resedimentation of the material occurred during Pleistocene, which later accumulated and became preserved in the Milna valley. Beside the Dinaride Ophiolite Zone, part of the mineral composition is influenced by minerals from the Alpine region and by neutral to basic volcanism, probably of Italian origin. During the Dark Age Cold Period (DACP) the Milna valley was covered by forests of the Pinus sylvestris group, within which cold-resistant and closed forest habitat preferring species (molluscs) lived. This forested environment probably lasted until the Little Ice Age (LIA) period when fires occurred in the 15th and 16th centuries. The opening of the landscape corresponded to the resettling of the population from the interior to the coast and to the expansion of vineyards on the island. The deforestation enabled the formation of torrential flows and deposition of unsorted sediments. Most of the pebbles are rounded clasts of the Middle Cretaceous (Cenomanian) dolomite in which the valley is formed. However, pebbles which are not present in outcrops of the Milna valley have also been identified. After the LIA, the valley became dry again and has been continuously under anthropogenic impact ever since. Different cartographic sources enable the further tracing of land cover changes from the beginning of the 19th century to present day. The analysis revealed that the highest anthropogenic impact on the landscape occurred in the second part of the 19th century, after which afforestation started. Moreover, the major issue today relates to changes influenced by the current relative sea level rise. This study adds to the knowledge on coastal fluviokarst valley evolution in typical Mediterranean conditions, relating our understanding of Holocene deposition, human activity, and land cover changes on the island of Vis