HPLC-UV and GC-MS Methods for Determination of Chlorambucil and Valproic Acid in Plasma for Further Exploring a New Combined Therapy of Chronic Lymphocytic Leukemia

High performance liquid chromatography with ultra-violet detection (HPLC-UV) and gas chromatography–mass spectrometry (GC-MS) methods were developed and validated for the determination of chlorambucil (CLB) and valproic acid (VPA) in plasma, as a part of experiments on their anticancer activity in chronic lymphocytic leukemia (CLL). CLB was extracted from 250 µL of plasma with methanol, using simple protein precipitation and filtration. Chromatography was carried out on a LiChrospher 100 RP-18 end-capped column using a mobile phase consisting of acetonitrile, water and formic acid, and detection at 258 nm. The lowest limit of detection LLOQ was found to be 0.075 μg/mL, showing sufficient sensitivity in relation to therapeutic concentrations of CLB in plasma. The accuracy was from 94.13% to 101.12%, while the intra- and inter-batch precision was ≤9.46%. For quantitation of VPA, a sensitive GC-MS method was developed involving simple pre-column esterification with methanol and extraction with hexane. Chromatography was achieved on an HP-5MSUI column and monitored by MS with an electron impact ionization and selective ion monitoring mode. Using 250 µL of plasma, the LLOQ was found to be 0.075 μg/mL. The accuracy was from 94.96% to 109.12%, while the intra- and inter-batch precision was ≤6.69%. Thus, both methods fulfilled the requirements of FDA guidelines for the determination of drugs in biological materials.     

Characterization of Adducts Formed in the Reactions of Methylglyoxal and Malonaldehyde with Lysine and Histidine Derivatives

Glycation of biopolymers by α‐oxoaldehydes such as methylglyoxal is believed to play a major role in the complex pathologies associated with diabetes and metabolic diseases. To design strategies that could interfere with the endogenous production of such aldehydes or promote their detoxification or, alternatively, to develop therapeutic procedures that could inhibit the deleterious effects of the oxoaldehydes at the cellular level, it is important to characterize the wide spectrum of reactions between these compounds and biomolecules, and gain insight into their mechanisms. In this study, we investigated the reactivity of endogenous α‐oxoaldehyde, methylglyoxal, and of malonaldehyde towards amino acid derivatives, and we identified new adducts with N^α‐acetyllysine and N^α‐acetylhistidine. In addition, we showed that a structurally analogous adduct is also formed with the model peptide N‐acetylglycyllysine O‐methyl ester. The characterized compounds were most likely derived from the addition of the appropriate nucleophilic center of the studied biomolecules to the C?C bond of the initially formed aldehyde conjugate. The resulted adducts contain an electrophilic β‐dicarbonyl moiety and could potentially be involved in the formation of DNA? protein or protein cross? links.     

Experimental studies of charge density distribution in the crystals of cytisine and N-methylcytisine. Inside the <Emphasis Type="Italic">Fake Tobacco</Emphasis>

The high-resolution X-ray data for two bioactive molecules: cytisine (1) and its N-methyl derivative (2) have been collected up to sinθ/λ = 1.12 Å^?1 for 1 and 1.0 Å^?1 for 2. This data was used for modeling of the fine features of electron density distribution, including bonding density and electron lone pairs. The quality of the model was checked by, e.g., rigid bond test and RDA analysis. The topological analysis (gradient field analysis) has been also performed for both inter- and intramolecular interactions. In case of 1 a number of intermolecular interactions, from relatively strong N-H···O hydrogen bonds to weak H···H contacts was found, and their topological features were analyzed. For N-methyl derivative, only few intermolecular bonding contacts were found. The analyzed features show that besides the structural similarities of both alkaloids, the electron density distribution and consequently all its derivatives differ quite significantly in places.     

How to use thermal imaging in venous insufficiency?

This paper is intended to provide studies performed on usefulness of thermal imaging for the insufficiency of superficial veins in the lower limbs. The results are a continuation of the previous research and show a new way of analysis and better correlation between standard methods of parameters like duplex ultrasonography and parameters derived from thermal imaging. In particular promised seems to be using the mean whole limb temperature of healthy volunteers at a proper age as a threshold to count the isotherm area, and in isotherm analysis should be taken for the whole lower limb—the sum of thermal images from anterior and posterior views (Method II). The study was performed by the use of a Thermovision E60 camera by Flir Systems. All studies (duplex ultrasonography as well as thermal imaging) were performed in a research room with a stabilized temperature on two groups of patients, a group of healthy people and patients suffering from chronic venous disease. During the study, the correlation parameters were obtained with ultrasound and thermal parameters. The results showed that temperature changes observed in the lower extremities of the thermal skin map are associated with a healthy state of blood supply which might be connected with blood stasis, inflammatory states and swelling that occurs in the soft tissues. We found the mean and higher correlations between thermal and ultrasound parameters, for example, a good positive correlation (r = 0.63) between the thermal range to the total limb length radio and the range of reflux was obtained. The correlation between thermal imaging parameters and duplex ultrasound parameters may show that thermovision is an extremely promising method, and it can be useful in the screening of diagnosis of superficial vein insufficiency.     

Anodic polarization of nanocrystalline titanium

TiO₂ nanotubes are extensively investigated because of their unique properties and wide range of applications, e.g., in biomedicine. They are used as coatings on titanium implant materials accelerating osteoblast (bone cell) adhesion and improving osteointegration. Owing to its high mechanical properties, nanocrystalline titanium is likely to replace the widely used titanium alloys, which contains harmful ions such as V and Al. The performance properties of nanocrystalline titanium can be modified by subjecting it to various surface treatments tailored to the demands of a given application. The aim of this study is to determine whether the grain refinement of the titanium substrate has an influence on the formation of TiO₂ nanotubes. The TiO₂ nanotubes were fabricated by anodic polarization of micro- and nanotitanium at a constant voltage of 10, 15, and 20 V for 2 h in an electrolyte containing fluoride ions. The nanocrystalline bulk titanium (grade 2) with grain size of about 90 nm and high density of dislocations was obtained using hydrostatic extrusion. Commercially available coarse-grained titanium with grain size of 20 μm was used as a reference sample. The microstructure of the fabricated nanotubular layers was revealed using scanning electron microscopy and focus ion beam microscopy. Auger electron spectroscopy and X-ray photoelectron spectroscopy were used to determine the chemical composition of the fabricated layers. The results indicate that grain refinement influences the morphology of TiO₂ nanotubes while their chemistry remains unchanged.     

Hybridization of a Flexible Cyclooctatetraene Core and Rigid Aceneimide Wings for Multiluminescent Flapping π Systems

The hybridization of flexible and rigid π‐conjugated frameworks is a potent concept for producing new functional materials. In this article, a series of multifluorescent flapping π systems that combine a flexible cyclooctatetraene (COT) core and rigid aceneimide wings with various π‐conjugation lengths has been designed and synthesized, and their structure/properties relationships have been investigated. Whereas these molecules have a V‐shaped bent conformation in the ground state, the bent structure changes to a planar conformation in the lowest excited singlet (S₁) state irrespective of the lengths of the aceneimide wings. However, the fluorescence behavior in solution is distinct between the naphthaleneimide system and the anthraceneimide system. The former has a nonemissive S₁ state owing to the significant contribution of the antiaromatic character of the planar COT frontier molecular orbitals, thereby resulting in complete fluorescence quenching in solution. In contrast, the latter anthraceneimide system shows an intense emission, which is ascribed to the planar but distorted S₁ state that shows the allowed transition between the π‐molecular orbitals delocalized over the COT core and the acene wings. The other characteristic of these π systems is the significantly redshifted fluorescence in the crystalline state relative to their monomer fluorescence. The relationship between the packing structures and the fluorescence properties was investigated by preparing a series of hybrid π systems with different sizes of substituents on the imide moieties, which revealed the effect of the twofold π‐stacked structure of the V‐shaped molecules on the large bathochromic shift in emission.     

Determination of hafnium at the 10% level (relative to zirconium content) using neutron activation analysis,inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry

Hafnium at the very low level of 1–8 ppm (in relation to zirconium) was determined in zirconium sulfate solutions (originating from investigations of the separation of ca. 44 ppm Hf from zirconium by means of the ion exchange method) by using three independent methods: inductively coupled plasma mass spectrometry (ICP MS), neutron activation analysis (NAA) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The results of NAA and ICP MS determinations were consistent with each other across the entire investigated range (the RSD of both methods did not exceed 38%). The results of ICP-AES determination were more diverse, particularly at less than 5 ppm Hf (RSD was significantly higher: 29–253%). The ion exchange method exploiting Diphonix^® resin proved sufficient efficiency in Zr–Hf separation when the initial concentration ratio of the elements ([Zr]₀/[Hf]₀) ranged from 1200 to ca. 143,000.     

Structural Variety of Cobalt(II), Nickel(II), Zinc(II), and Cadmium(II) Complexes with 4,4′‐Azopyridine: Synthesis,Structure and Luminescence Properties

Self‐assembled bi‐ and polymetallic complexes of Co^II, Ni^II, Zn^II, and Cd^II were obtained by the reaction of 4,4′‐azopyridine (azpy) with metal tri‐tert‐butoxysilanethiolates (Co, 1 ; Cd, 2 ), acetylacetonates (Ni, 3 ; Zn, 4 ), and acetates (Cd, 5 ). All compounds were characterized by single‐crystal X‐ray structure analysis, elemental analysis, FTIR spectroscopy, and thermogravimetry. Complexes 1 , 2 and 4 , 5 exhibit diverse structural conformations: 1 is bimetallic, 2 and 4 are 1D coordination polymers, and 5 is a 2D coordination framework formed from bimetallic units. The obtained complexes contain metal atoms bridged by a molecule of azpy. The luminescent properties of 1–5 were investigated in the solid state.     

Optimization and Evaluation of 5-Styryl-Oxathiazol-2-one Mycobacterium tuberculosis Proteasome Inhibitors as Potential Antitubercular Agents

This is the first report of 5-styryl-oxathiazol-2-ones as inhibitors of the Mycobacterium tuberculosis (Mtb) proteasome. As part of the study, the structure–activity relationship of oxathiazolones as Mtb proteasome inhibitors has been investigated. Furthermore, the prepared compounds displayed a good selectivity profile for Mtb compared to the human proteasome. The 5-styryl-oxathiazol-2-one inhibitors identified showed little activity against replicating Mtb, but were rapidly bactericidal against nonreplicating bacteria. (E)-5-(4-Chlorostyryl)-1,3,4-oxathiazol-2-one) was most effective, reducing the colony-forming units (CFU)/mL below the detection limit in only seven days at all concentrations tested. The results suggest that this new class of Mtb proteasome inhibitors has the potential to be further developed into novel antitubercular agents for synergistic combination therapies with existing drugs.     

Analytical procedure for steroid profiling valid for Athlete Biological Passport

Although various attempts have been made to eliminate doping in sport, hitherto they all have proved futile. Moreover, the main class of substances that jeopardises the fair play rule remains the same — anabolic androgenic steroids (AAS). To date, longitudinal monitoring of the fluctuations of the endogenous steroids content for a given athlete is regardeded as the most effective approach to the detection of AAS abuse. This is based on the fact that the activity of the steroid biosynthesis pathway may undergo significant changes in response to the AAS administration. This paper presents the entire analytical procedure for quantification of steroids crucial for the Athlete Biological Passport (ABP): testosterone, epitestosterone, dehydroepiandrosterone, androsterone, etiocholanolone, 5-α-androstandiol and 5-β-androstandiol. The procedure consists of a four-step sample preparation process followed by analysis by gas chromatography coupled with mass spectrometry. The limits of quantification for the substances listed above were; 0.44 ng mL^?1, 2.07 ngmL^?1, 1.24 ng mL^?1, 62.49 ng mL^?1, 36.20 ng mL^?1, 16.90 ng mL^?1 and 14.92 ng mL^?1, respectively. Aqueous solutions containing deuterated and non-deuterated steroids were used for calibration purposes. Subsequently, the validation parameters, e.g., precision, accuracy and recovery were evaluated for each substance individually.