Vibrational circular dichroism of adenosine crystals.

Adenosine is one of the building blocks of nucleic acids and other biologically important molecules. Spectroscopic methods have been among the most utilized techniques to study adenosine and its derivatives. However, most of them deal with adenosine in solution. Here, we present the first vibrational circular dichroism (VCD) spectroscopic study of adenosine crystals in solid state. Highly regular arrangement of adenosine molecules in a crystal resulted in a strongly enhanced supramolecular VCD signal originating from long-range coupling of vibrations. The data suggested that adenosine crystals, in contrast to guanosine ones, do not imbibe atmospheric water. Relatively large dimensions of the adenosine crystals resulted in scattering and substantial orientational artifacts affecting the spectra. Several strategies for tackling the artifacts have been proposed and tested. Atypical features in IR absorption spectra of crystalline adenosine (e.g., extremely low absorption in mid-IR spectral range) were observed and attributed to refractive properties of adenosine crystals.

Vibrational Circular Dichroism Unravels Supramolecular Chirality and Hydration Polymorphism of Nucleoside Crystals.

Invited for the cover of this issue are Valery Andrushchenko, Monika Krupová, and co-workers at the Institute of Organic Chemistry and Biochemistry (IOCB Prague) of the Czech Academy of Sciences. The image depicts a "crystal city" illuminated by "chiral suns" shining left- and right-circularly polarized light (L-CPL and R-CPL), which reveals differences in the structure of the chiral crystalline "skyscrapers". Designed by Tomás Bellon @ IOCB Prague. Read the full text of the article at 10.1002/chem.202201922.

Vibrational Circular Dichroism Unravels Supramolecular Chirality and Hydration Polymorphism of Nucleoside Crystals.

Vibrational circular dichroism (VCD) spectroscopy has been widely used to study (bio)molecules in solution. However, its solid-state applications have been restricted due to experimental limitations and artifacts. Having overcome some of them, the first VCD study of nucleoside crystals is now presented. A two-orders-of-magnitude enhancement of VCD signal was observed due to high molecular order in the crystals and resulting supramolecular chirality. This allowed to obtain high-quality VCD spectra within minutes using minute amounts of samples. The VCD technique is extremely sensitive in detecting changes in a crystal order and is able to distinguish different hydration states of crystals. This elevates it to a new level, as a fast and efficient tool to study chiral crystalline samples. This study demonstrates that VCD is capable of near-instantaneous detection of hydration polymorphs and crystal degradation, which is of substantial interest in pharmaceutical industry (quality and stability control).

Differential response of liver sinusoidal endothelial cells and hepatocytes to oleic and palmitic acid revealed by Raman and CARS imaging.

Excess circulating fatty acids contribute to endothelial dysfunction that subsequently aggravates the metabolic conditions such as fatty liver diseases. However, the exact mechanism of this event is not fully understood, and the investigation on the effect of a direct exposure to fatty acids together with their subsequent fate is of interest. In this work we employed a chemically specific and label-free techniques such as Raman and CARS microscopies, to investigate the process of lipid droplets (LDs) formation in endothelial cells and hepatocytes after exposure to oleic and palmitic acid. We aimed to observe the changes in the composition of LDs associated with metabolism and degradation of lipids. We were able to characterize the diversity in the formation of LDs in endothelium as compared to hepatocytes, as well as the differences in the formation of LDs and degradation manner with respect to the used fatty acid. Thus, for the first time the spectral characteristics of LDs formed in endothelial cells after incubation with oleic and palmitic acid is presented, including the time-dependent changes in their chemical composition.

Raman spectroscopy-based insight into lipid droplets presence and contents in liver sinusoidal endothelial cells and hepatocytes.

Liver sinusoidal endothelial cells (LSECs), a type of endothelial cells with unique morphology and function, play an important role in the liver hemostasis, and LSECs dysfunction is involved in the development of nonalcoholic fatty liver disease (NAFLD). Here, we employed Raman imaging and chemometric data analysis in order to characterize the presence of lipid droplets (LDs) and their lipid content in primary murine LSECs, in comparison with hepatocytes, isolated from mice on high-fat diet. On NAFLD development, LDs content in LSECs changed toward more unsaturated lipids, and this response was associated with an increased expression of stearylo-CoA desaturase-1. To the best of our knowledge, this is a first report characterizing LDs in LSECs, where their chemical composition is analyzed along the progression of NAFLD at the level of single LD using Raman imaging.

The dynamics of the oxidant-antioxidant balance in the early phase of human acute biliary pancreatitis.

BACKGROUND/AIM: Reactive oxygen species play an important role in the pathogenesis of acute pancreatitis (AP) in animal models. Data on the oxidant-antioxidant balance in humans are scanty. The present study was undertaken to evaluate the dynamics of changes in the oxidant-antioxidant balance in the early phase of human AP. METHODS: 74 consecutive patients with acute biliary pancreatitis (16 with severe, 58 with mild pancreatitis), treated endoscopically, were included in the study. Serum concentrations of sulfhydryl groups (SH; main nonenzymatic antioxidant; 73 patients) and thiobarbituric acid reactive substances (TBARS; markers of reactive oxygen species-mediated tissue damage; 56 patients) were determined on admission and on each of 10 successive days. The analysis comprised the comparison of results in patients with mild and severe outcome of pancreatitis. RESULTS: Serum SH dropped by 27%, reaching the trough level on day 4 of hospitalization, whereas serum TBARS rose by 28%, reaching a peak 1 day later. Neither SH nor TBARS returned to initial values at the end of observation. The most dynamic changes in both SH and TBARS concentrations occurred in the first 3 days of hospitalization. The changes were significantly greater in patients with complicated pancreatitis in comparison to patients with mild disease, and were most pronounced in patients who developed infected pancreatic necrosis and who subsequently died. CONCLUSIONS: The oxidant-antioxidant balance changes rapidly in the early phase of human AP, confirming the role of oxidative stress in the pathogenesis of AP. The degree of changes correlates with the clinical severity of pancreatitis.