A structural study of the retinal photoreceptor, plexiform and ganglion cell layers following exposure to UV-B and UV-C radiation in the albino rat

Over the last two decades, ultraviolet radiation levels (UV), reaching the Earth's surface, have been increasing at a rate of 1.5% per each 1% loss of the ozone layer. Moreover, artificial UV-sources have also proliferated and contributed to the rising UV-stress that many organisms have to face. To assess how the vertebrate retina responds to an exposure of short wavelength UV, we focused our attention on the rat retina, observing photoreceptor (containing outer and inner segments of rods and cones), inner plexiform, and ganglion cell layers by light and transmission electron microscopy using conventional and cytochemical techniques. We analyzed how cells of the layers in question responded to a 30 min exposure to UV-C and UV-B radiation with doses of 7200 and 590 J/cm², respectively. The results show that there are significant changes in the nuclei and cytoplasmic organelles of the exposed retinae when compared with those of the unexposed controls. The changes include an increase in heterochromatin, distension of rough endoplasmic reticulum, mitochondrial disruptions, and increases in the number of myelin bodies. The recorded morphological changes, especially those of the ganglion cells, are suggestive of apoptotic processes and show that the exposure of vertebrate retina to wavelengths ranging from 254 to 312 nm can produce alterations that are likely to impact negatively on the retina's proper functioning.     

Influence of N-doping on the structure and electronic properties of titania nanoparticle photocatalysts

N-containing TiO(2)-based nanostructured materials (average particle size approximately 10 nm) with an anatase-type structure were investigated using oxygen (O) K-edge and titanium (Ti) K- and L-edge X-ray absorption near-edge spectroscopy (XANES). The Ti K pre-edge features indicate that samples predominantly contain ([6])Ti with some ([5])Ti, and there is no evidence for ([4])Ti. We observed that those samples with a larger fraction of Ti in a fivefold coordination, that is, with a significant number of oxygen vacancies, also present a modified Ti environment at the medium-range scale. The presence of these defects drastically modifies the electronic structure of the conduction band, as evidenced by the O K XANES spectra, but does not result in the presence of reduced Ti(3+) states. We discuss the influence of N-doping on titania nanoparticles and their structure, electronics and photocatalytic activity.     

Validation of the antifactor Xa and antifactor IIa assays for the potency assessment of nadroparin in pharmaceutical formulations

The low-molecular weight heparin nadroparin calcium is used clinically for the prevention and treatment of venous and arterial thrombosis. The antifactor Xa and antifactor IIa assays were validated by investigating the parameters of range, linearity (r2 = 0.9905 and r2 = 0.9914, respectively) precision, accuracy, and robustness. The 2 methods incorporated a chromogenic endpoint and detection at 405 nm, yielding good results with detection limits of 0.004 and 0.01 IU/mL and quantitation limits of 0.01 and 0.03 IU/mL, respectively, for the antifactor Xa and antifactor IIa assays. Nadroparin calcium pharmaceutical products were evaluated by the antifactor Xa assay and the antifactor IIa assay, giving potencies between 93.86 and 109.88%, with an antifactor Xa/antifactor IIa ratio between 3.2 and 3.7. The results demonstrated the validity of the assays that are useful methodologies for the routine quality control of nadroparin in pharmaceutical formulations.     

Hydantoin derivatives of L- and D-amino acids: synthesis and evaluation of their antiviral and antitumoral activity

3,5-Disubstituted hydantoin (1,3-imidazolidinedione) derivatives 5a-h were prepared by base induced cyclization of the corresponding N-(1-benzotriazolecarbonyl)-L- and D-amino acid amides 4a-h. Compounds 5a-h were evaluated for their cytostatic and antiviral activities. Among all the compounds evaluated, 3-benzhydryl-5-isopropyl hydantoin (5a) showed a weak but selective inhibitory effect against vaccinia virus (EC(50) = 16 microg/mL; selectivity index: 25). 3-Cyclohexyl-5-phenyl hydantoin (5g) showed inhibitory activity against cervical carcinoma (HeLa, IC(50) = 5.4 microM) and breast carcinoma (MCF-7, IC(50) = 2 microM), but also cytotoxic effects towards human normal fibroblasts (WI 38). On the contrary, the 3-benzhydryl-5-phenyl substituted hydantoin derivative 5h showed moderate inhibitory activity towards HeLa, MCF-7, pancreatic carcinoma (MiaPaCa-2), lung carcinoma (H 460) and colon carcinoma (SW 620) (IC(50) = 20-23 microM), but no effect on WI 38.     

Unusual calibration curves observed for iron using high-resolution continuum source graphite furnace atomic absorption spectrometry

The simultaneous determination of cadmium and iron in plant and soil samples has been investigated using high-resolution continuum source graphite furnace atomic absorption spectrometry. The primary cadmium resonance line at 228.802 nm and an adjacent secondary iron line at 228.726 nm, which is within the spectral interval covered by the charge-coupled device (CCD) array detector, have been used for the investigations. Due to the very high iron content in most of the soil samples the possibility has been investigated to reduce the sensitivity and extend the working range by using side pixels for measurement at the line wings instead of the line core. It has been found that the calibration curves measured at all the analytically useful pixels of this line consisted of two linear parts with distinctly different slopes. This effect has been independent of the positioning of the wavelength, i.e., if the Cd line or the Fe line was in the center of the CCD array. The most likely explanation for this unusual behavior is a significant difference between the instrument width Δλ_Instr and the absorption line width Δλ_Abs, which is quite pronounced in the case of Fe. Using both parts of the calibration curves and simultaneous measurement at the line center and at the wings made it possible to extend the working range for the iron determination to more than three orders of magnitude.     

Harnack inequality for harmonic functions relative to a nonlinear p-homogeneous Riemannian Dirichlet form

We state a Wiener criterion for the regularity of points with respect to a relaxed Dirichlet problem for a p-homogeneous Riemannian Dirichlet form.     

p doping in expanded phases of ZnO: an ab initio study

The issue of p doping in nanostructured cagelike ZnO is investigated by state-of-the-art calculations. Our study is focused on one prototypical structure, namely, sodalite, for which we show that p-type doping is possible for elements of the V, VI, and VII columns of the periodic table. However, some dopants tend to form dimers, thus impairing the stability of this kind of doping. This difference of behavior is discussed, and two criteria are proposed to ensure stable p doping.     

Front Cover: Critical Assessment of pH-Dependent Lipophilicity Profiles of Small Molecules: Which One Should We Use and In Which Cases? (ChemPhysChem 24/2023)

Lipophilicity is a physicochemical property with wide relevance in drug design, computational biology, food, environmental and medicinal chemistry. Lipophilicity is commonly expressed as the partition coefficient for neutral molecules, whereas for molecules with ionizable groups, the distribution coefficient (D) at a given pH is used. The logD_pH is usually predicted using a pH correction over the logP_N using the pK_a of ionizable molecules, while often ignoring the apparent ion pair partitioning . In this work, we studied the impact of on the prediction of both the experimental lipophilicity of small molecules and experimental lipophilicity-based applications and metrics such as lipophilic efficiency (LipE), distribution of spiked drugs in milk products, and pH-dependent partition of water contaminants in synthetic passive samples such as silicones. Our findings show that better predictions are obtained by considering the apparent ion pair partitioning. In this context, we developed machine learning algorithms to determine the cases that should be considered. The results indicate that small, rigid, and unsaturated molecules with logP_N close to zero, which present a significant proportion of ionic species in the aqueous phase, were better modeled using the apparent ion pair partitioning . Finally, our findings can serve as guidance to the scientific community working in early-stage drug design, food, and environmental chemistry.     

Biodegradable polymeric films based on microbial poly(3-hydroxybutyrate). Effect of gamma-radiation on mechanical properties and biodegradability

Two samples of microbial poly(3-hydroxybutyrate) (PHB) having different molecular weight were used for the preparation of films to be exposed to gamma radiation. The effect of radiation on those samples with high molecular weight increased the fragility of the film. Biodegradability increased with time and reached about 95% after 18 days. Weight-loss of both samples (irradiated and non-irradiated) after 23 days were 100%, for those films with molecular weight of 265 kD.     

ChemInform Abstract: Identification of Novel Cu,Ag, and Au Ternary Oxides from Global Structural Prediction.

Ab initio global structural prediction and specifically, the minima hopping method combined with high‐throughput calculations are used to explore the periodic table in search of novel oxide phases.