In vitro metabolism of etoposide (VP-16-213) by liver microsomes and irreversible binding of reactive intermediates to microsomal proteins

We have studied the metabolism of VP-16-213 (etoposide, VP-16), an antitumor agent, by mouse liver microsomes to reactive intermediates and the subsequent covalent binding to microsomal proteins. This metabolism was shown to involve the O-demethylation of VP-16 and resulted in the formation of a 3',4'-dihydroxy derivative (DHVP-16) which was identified by both HPLC and mass spectrometry. The formation of DHVP-16 was cytochrome P-450-mediated as indicated by its dependence on NADPH, its increased production following treatment of mice with phenobarbital, and its marked inhibition by SKF-525A and piperonyl butoxide. Furthermore, DHVP-16 formation required oxygen. Microsomal incubation of VP-16 resulted in an irreversible binding of the drug to the proteins, which was also shown to be cytochrome P-450 dependent. The covalent binding of the VP-16 metabolite(s) was inhibited by DHVP-16 in a dose-dependent fashion, suggesting that the reactive intermediates that bound to proteins were derived from DHVP-16. Electron spin resonance studies indicated that the same semiquinone radical was formed during enzymatic (oxidation or reduction) metabolism of DHVP-16 and the o-quinone derivative of VP-16 (VP-16-Q). VP-16-Q and its semiquinone radical are suggested to be the bioalkylating species.     

Aluminothermic Synthesis of Dispersed Electrides Based on Mayenite: XRD and EPR Study

The evolution of the structure and the phase composition of a dispersed mayenite at its interaction with metallic aluminum was studied in a temperature range from 900 to 1400 °C in both argon and air atmospheres. The aluminum loading was varied from 0 to 50 wt%. It was found that the addition of aluminum significantly affects the stability of the mayenite and other calcium aluminate phases within the studied temperature range. The formation of the electride state registered by the appearance of a characteristic electron paramagnetic resonance (EPR) signal from F⁺-like centers (g~1.994) in an argon atmosphere was shown to take place already at 1150 °C due to an aluminothermic reduction of this material. The super-narrow (H_p-p < 0.5 G) EPR spectra from F⁺-like centers, which were recently observed for the core–shell structures of the C12A7@C type only, were registered for mayenite for the first time. The results obtained in the present study testify firstly towards the possibility of significantly diminishing the temperatures required for the formation of the electride state in such systems and secondly towards the ability to stabilize the size of small electride nanoparticles within the synthesized calcium aluminate matrix.     

Pulmonary pattern in systemic vasculitis: granulomatosis,lung cancer or both?

As clinical manifestations of systemic vasculitides share many common features with other conditions, the rate of diagnostic errors and delayed diagnoses is high. Hence we performed an analysis of the available data regarding misdiagnosis of vasculitis as lung cancer and vice versa, as well as coexistence of vasculitis and lung cancer. The present case-based review highlights the diagnostic challenges encountered when granulomatosis with polyangiitis (GPA) mimics lung cancer. The importance of a multidisciplinary team approach to patients with pulmonary involvement and multisystem manifestations is essential for appropriate planning of further diagnostic steps and for minimizing the delay in correct diagnosis and treatment. In the present case, although computed tomography raised suspicion for lung cancer, further biopsies and laboratory screening for systemic vasculitides rejected malignancy and confirmed the diagnosis of GPA.     

Pregnancy management for a woman with extensive vulvar and pelvic malformations caused by Klippel–Trénaunay syndrome

Klippel–Trénaunay syndrome (KTS) is a rare congenital disorder defined by a triad of capillary malformation, venous malformation, and soft tissue or bone hypertrophy most commonly affecting unilateral lower limbs. Due to the rarity of KTS, evidence‐based guidelines for the management of pregnancy in people with KTS are still lacking. A 34‐year‐old woman (gravidity 1; parity 0) presented at 25 weeks of gestation with malformations of the right side of her body. The extent of the KTS affecting the vulva, pelvis, and right leg was remarkable. As the prenatal MRI showed massive vascular malformations of the pelvis and vulva, we performed an elective cesarean section to avoid severe perinatal hemorrhage during a vaginal delivery. Intraoperatively, we observed varices on the parietal peritoneum within the vesico‐uterine pouch and the isthmocervical transition of the uterus, which were not identifiable in the preoperative MRI. Although KTS patients have been discouraged from pregnancy in the past because of a high risk for complications, successful and uncomplicated pregnancies are possible. For this purpose, we believe a multidisciplinary strategy that is crucial.     

Triangulo-{ErIII3} complex showing field supported slow magnetic relaxation

The triangulo-{Er₃} complex [Er₃Cl(o-van)₃(OH)₂(H₂O)₅]Cl₃·nH₂O (n = 9.4; H(o-van) = o-vanillin) (1) was generated by an in situ method. The isolated Er(iii) complex 1 was characterized by elemental analysis and molecular spectroscopy. The results of single crystal X-ray diffraction studies have shown that 1 is built up of trinuclear [Er₃Cl(o-van)₃(OH)₂(H₂O)₅]³⁺ complex cations, chloride anions and water solvate molecules. Within the complex cation the three Er(iii) central atoms are placed at the apexes of a triangle which are bridged by three (o-van)⁻ ligands with additional chelating functions and two μ₃-OH⁻ ligands. Additionally five aqua and one chlorido ligands complete the octa-coordination of the three Er(iii) atoms. AC susceptibility measurements reveal that the compound exhibits slow magnetic relaxation with two relaxation modes.

The triangulo-{Er₃} complex [Er₃Cl(o-van)₃(OH)₂(H₂O)₅]Cl₃·nH₂O (n = 9.4; H(o-van) = o-vanillin) (1) was generated by an in situ method.     

Stability of monoclonal antibodies after simulated subcutaneous administration

Changes in the environment from the drug product to the human physiology might lead to physical and/or chemical modifications of the protein drug, such as in vivo aggregation and fragmentation. Although subcutaneous (SC) injection is a common route of administration for therapeutic proteins, knowledge on in vivo stability in the SC tissue is limited. In this study, we developed a physiologic in vitro model simulating the SC environment in patients. We assessed the stability of two monoclonal antibodies (mAbs) in four different protein-free fluids under physiologic conditions. We monitored protein stability over two weeks using a range of analytical methods, in analogy to testing purposes of a drug product. Both mAbs showed an increase of protein aggregates, fragments, and acidic species. mAb1 was consistently more stable in this in vitro model than mAb2, highlighting the importance of comparing the stability of different mAbs under physiologic conditions. Throughout the study, both mAbs were substantially less stable in bicarbonate buffers as compared to phosphate-buffered saline. In summary, our developed model was able to differentiate stability between molecules. Bicarbonate buffers were more suitable compared to phosphate-buffered saline in regards to simulating the in vivo conditions and evaluating protein liabilities.