Spectroscopic and calorimetric studies on trazodone hydrochloride-phosphatidylcholine liposome interactions in the presence and absence of cholesterol.

The interaction of antidepressant drug trazodone hydrochloride (TRZ) with dipalmitoyl phosphatidylcholine (DPPC) multilamellar liposomes (MLVs) in the presence and absence of cholesterol (CHO) was investigated as a function of temperature by using Electron Paramagnetic Resonance (EPR) spin labeling, Fourier Transform Infrared (FTIR) Spectroscopy and Differential Scanning Calorimetry (DSC) techniques. These interactions were also examined for dimyristoyl phosphatidylcholine (DMPC) multilamellar liposomes by using Electron Paramagnetic Resonance (EPR) spin labeling technique. In the EPR spin labeling studies, 5- and 16-doxyl stearic acid (5-DS and 16-DS) spin labels were used to monitor the head group and alkyl chain region of phospholipids respectively. The results indicated that TRZ incorporation causes changes in the physical properties of PC liposomes by decreasing the main phase transition temperature, abolishing the pre-transition, broadening the phase transition profile, and disordering the system around the head group region. The interaction of TRZ with unilamellar (LUV) DPPC liposomes was also examined. The most pronounced effect of TRZ on DPPC LUVs was observed as the further decrease of main phase transition temperature in comparison with DPPC MLVs. The mentioned changes in lipid structure and dynamics caused by TRZ may modulate the biophysical activity of membrane associated receptors and in turn the pharmacological action of TRZ.

Rapid diagnosis of malignant pleural mesothelioma and its discrimination from lung cancer and benign exudative effusions using blood serum.

Malignant pleural mesothelioma (MPM), an aggressive cancer associated with exposure to fibrous minerals, can only be diagnosed in the advanced stage because its early symptoms are also connected with other respiratory diseases. Hence, understanding the molecular mechanism and the discrimination of MPM from other lung diseases at an early stage is important to apply effective treatment strategies and for the increase in survival rate. This study aims to develop a new approach for characterization and diagnosis of MPM among lung diseases from serum by Fourier transform infrared spectroscopy (FTIR) coupled with multivariate analysis. The detailed spectral characterization studies indicated the changes in lipid biosynthesis and nucleic acids levels in the malignant serum samples. Furthermore, the results showed that healthy, benign exudative effusion, lung cancer, and MPM groups were successfully separated from each other by applying principal component analysis (PCA), support vector machine (SVM), and especially linear discriminant analysis (LDA) to infrared spectra.

EPR investigation of clomipramine interaction with phosphatidylcholine membranes in presence and absence of cholesterol.

The effects of tricylic antidepressant clomipramine (CLO) on the membrane properties of saturated dimyristoyl phosphatidylcholine and dipalmitoyl phosphatidylcholine as well as on unsaturated egg yolk phosphatidylcholine liposomes were investigated by the electron paramagnetic resonance spin-labeling technique, in combination with the simulation of the spectra, taking into account that the membrane is heterogeneous and composed of the regions with different fluidity characteristics. Different spin labels, monitoring membrane properties in the upper and inner parts of the membrane, were used. In general, two spectral components, having different motional characteristics, were detected in all liposomes investigated. In liposomes with saturated chains, CLO decreased the phase-transition temperature, disordered the membrane, and increased polarity in the upper part of the membrane. However, less impact was observed in liposomes with unsaturated chains. In dipalmitoyl phosphatidylcholine liposomes, it also induced molecular rearrangements near the pretransition temperature. The presence of 30 mol% cholesterol increased the fluidizing effect of CLO and modified the lateral diffusion of nitroxide in the inner part of the membrane. A unique anomalous increase in diffusion of nitroxide, dependent on CLO concentration, was detected in the temperature region where the phosphatidylcholine membrane without cholesterol experiences the phase transitions. Since the changes in the central part of the membrane were even more pronounced than in the upper part of the membrane, it could be concluded that CLO incorporates into the membrane with its hydrophobic ring parallel to the phospholipid chains.

Relapsing-Remitting Multiple Sclerosis diagnosis from cerebrospinal fluids via Fourier transform infrared spectroscopy coupled with multivariate analysis.

Multiple sclerosis (MS) is a chronic, progressive, inflammatory and degenerative disease of central nervous system. Here, we aimed to develop a method for differential diagnosis of Relapsing-Remitting MS (RRMS) and clinically isolated syndrome (CIS) patients, as well as to identify CIS patients who will progress to RRMS, from cerebrospinal fluid (CSF) by infrared (IR) spectroscopy and multivariate analysis. Spectral analyses demonstrated significant differences in the molecular contents, especially in the lipids and Z conformation of DNA of CSF from CIS, CIS to RRMS transformed (TCIS) and RRMS groups. These changes enables the discrimination of diseased groups and controls (individuals with no neurological disease) from each other using hierarchical cluster and principal component analysis. Some CIS samples were consistently clustered in RRMS class, which may indicate that these CIS patients potentially will transform to RRMS over time. Z-DNA band at 795 cm-1 that is existent only in diseased groups and significant increase in carbonyl amount, decrease in amideI/amide II and lipid/protein ratios observed only for RRMS groups can be used as diagnostic biomarkers. The results of the present study shed light on the early diagnosis of RRMS by IR spectroscopy complemented with multivariate analysis tools.

Effect of cis-(Z)-flupentixol on DPPC membranes in the presence and absence of cholesterol.

Cis-(Z)-flupentixol dihydrochloride (FLU), a thioxanthene drug, is used in therapy of schizophrenia as well as in anxiolytic and depressive disorders. Since the action mechanism of FLU is not completely understood, the main objective of present study is to provide a detailed evaluation of flupentixol-phospholipid membrane interactions at molecular level. FLU-dipalmitoylphosphatidylcholine (DPPC) interactions in presence and absence of cholesterol (CHO) were investigated as a function of temperature. The changes in upper part of membrane were more pronounced than those in central part of membrane, as indicated by EPR and FTIR. FLU was proposed to incorporate into phospholipid membranes with its triple ring parallel to head group and its chain toward alkyl chain of phospholipids. According to DSC results, the incorporation of 10 mol% FLU into DPPC caused a shoulder in transition peak, suggesting the occurence of a phase separation, and formation of this new phase is still observable in presence of CHO. It is well known that, structure and dynamics of lipids have significant influence on the function of membrane bound proteins, and consecutively their actions. Based upon these, it was proposed that FLU may modify membrane associated receptors and transport proteins, which would form the basis of its clinical efficiency.

Interaction of antidepressant drug, clomipramine, with model and biological stratum corneum membrane as studied by electron paramagnetic resonance.

The interactions of tricyclic antidepressant drug, clomipramine (CLO), with pig ear stratum corneum (SC) and model membranes were investigated by electron paramagnetic resonance (EPR) spin labeling to get some insight into the possible application of this drug in transdermal delivery. The changes in membrane characteristics caused by CLO in the regions that are close to the water-lipid interfaces and the central parts of the membranes were searched. The experimental results were supported by computer simulation of EPR spectra, which showed heterogeneity of the membranes composed of regions with different fluidity characteristics. CLO was effective in both parts of the layers, indicating intercalation of the drug into model membranes as well as into the pig ear SC. Introduction of various molar ratios of CLO caused a decrease in the order parameter and an increase in the rotational diffusion of nitroxide moiety in different membrane regions as well as an increase in the polarity of spin probe environment. It also changed the number of resolved spectral components, which reflects the heterogeneity of the membrane. The fluidizing effect of CLO on pig ear SC throughout the whole membrane layers indicates that CLO penetrates into the SC, which is important for its transdermal delivery.