A study of the interaction of mechanically generated polypropylene radicals with phenolic antioxidant in the presence of oxygen by EPR spectroscopy

Isotactic polypropylene (iPP) was mechanically degraded in the absence and presence of a phenolic antioxidant at liquid nitrogen temperature in the presence of oxygen. The interaction of the primarily formed iPP macroradicals with oxygen and phenol was studied by EPR spectroscopy in the temperature region between 77 and 303 K at antioxidant concentrations of 0.1, 0.5, and 3.0 wt%. It was found that iPP macroradicals react at low temperature with oxygen, yielding peroxy radicals, and with antioxidant, with a simultaneous formation of phenoxy radicals. The development and decay of all kinds of radicals was studied. The rate constants for peroxy radical decay were determined and the apparent activation energies for the regions of slow and fast decay were calculated. © 1993 John Wiley & Sons, Inc.     

Diagnosis of Liposcelis entomophila (Insecta: Psocodea: Liposcelididae) based on morphological characteristics and DNA barcodes

Liposcelis entomophila infests stored grain and is one of the most important psocid species worldwide. Six geographically isolated strains of L. entomophila from Asia, Europe, and United States of America (USA) were compared based on morphological attributes and by molecular methods. Decisive characters of morphological diagnosis were studied using body size measurements and Scanning Electron Microscopy (SEM). Molecular identification of the six strains was performed via identification of DNA sequence similarities and phylogenetic analyses based on a 655-bp fragment from the 5′ end of the standard mitochondrial gene cytochrome c oxidase I (COI) barcode region. The results showed that both morphological and molecular approaches were able to accurately identify this species. Kimura-2-Parameter (K2P) divergence between geographically isolated strains was on average 1.75% for the COI sequence. Phylogenetic analyses revealed that sequences of L. entomophila strains' COI barcodes formed clusters with tight cohesion that were clearly distinct from those of allied species.     

Differentiation of toxigenic fungi using hyperspectral imagery

Some pathogenic fungi, Aspergillus flavus for example, produce mycotoxins that can contaminate grain products including wheat and corn. The contaminated grain poses a threat to the health of both humans and animals. Therefore, from the perspective of food safety and protection, it is important to detect and identify the different toxin-producing fungi encountered in food production. Earlier studies examined various spectral-based, non-destructive methods for the detection of fungi and toxins. The present report focused on the feasibility of using spectral image data for fungal species classification. A tabletop hyperspectral imaging system, VNIR-100E, was used for spectral and spatial data acquisition. A total of five fungal species were selected for a two-part experiment: Penicillium chrysogenum, Fusarium moniliforme (verticillioides), Aspergillus parasiticus, Trichoderma viride, and Aspergillus flavus. All fungal isolates were cultured on media under laboratory conditions and were imaged on day 5 of growth. The objective of the study was to use visible near-infrared hyperspectral imagery to differentiate fungal species. Results indicate that all five fungi are highly separable with classification accuracy of 97.7%. In addition, all five fungi could be classified by using only three narrow bands (bandwidth = 2.43 nm) centered at 743 nm, 458 nm, and 541 nm.     

In vitro study of partially hydrolyzed poly(2-ethyl-2-oxazolines) as materials for biomedical applications

Polymers based on 2-oxazoline, such as poly(2-ethyl-2-oxazolines) (PETOx), are considered to be a type of ‘pseudopeptide’ with the ability to form novel biomaterials. The hydrolysis of PETOx was carried out to evaluate its use in biomedical applications. In the present work, PETOx samples with a range of molar masses were prepared by living cationic polymerization. Hydrolysis was carried out at time intervals ranging from 15 to 180 min to prepare copolymers with different amounts of ethylene imine units. ¹H NMR spectroscopy was used to identify the structure of the hydrolyzed polymers. The dependence of in vitro cell viability on the degree of hydrolysis was determined using three different model cell lines, namely, mouse embryonic 3T3 fibroblasts, pancreatic βTC3 cells, and mouse lymphoid macrophages P388.D1. It was demonstrated that increasing the degree of hydrolysis decreased cell viability for all cell types. Fibroblast cells displayed the highest tolerance; additionally, the effect of polymer size showed no observable significance. Macrophage cells, immune system representatives, displayed the highest sensitivity to contact with hydrolyzed PETOx. The effect of polymer hydrolysis, polymer concentration and the incubation time on cell viability was experimentally observed. Confocal laser-scanning microscopy provided evidence of cellular uptake of pyrene-labeled (co)polymers.     

Effect of Novel AKT Inhibitor Vevorisertib as Single Agent and in Combination with Sorafenib on Hepatocellular Carcinoma in a Cirrhotic Rat Model

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality worldwide. The AKT pathway is often activated in HCC cases, and a longer exposure to tyrosine kinase inhibitors such as sorafenib may lead to over-activation of the AKT pathway, leading to HCC resistance. Here, we studied the efficacy of a new generation of allosteric AKT inhibitor, vevorisertib, alone or in combination with sorafenib. To identify specific adverse effects related to the background of cirrhosis, we used a diethylnitrosamine (DEN)-induced cirrhotic rat model. Vevorisertib was tested in vitro on Hep3B, HepG2, HuH7 and PLC/PRF cell lines. Rats were treated weekly with intra-peritoneal injections of DEN for 14 weeks to obtain cirrhosis with fully developed HCC. After that, rats were randomized into four groups (n = 7/group): control, sorafenib, vevorisertib and the combination of vevorisertib + sorafenib, and treated for 6 weeks. Tumor progression was followed by MRI. We demonstrated that the vevorisertib is a highly potent treatment, blocking the phosphorylation of AKT. The tumor progression in the rat liver was significantly reduced by treatment with vevorisertib + sorafenib (49.4%) compared to the control group (158.8%, p < 0.0001). Tumor size, tumor number and tumor cell proliferation were significantly reduced in both the vevorisertib group and vevorisertib + sorafenib groups compared to the control group. Sirius red staining showed an improvement in liver fibrosis by vevorisertib and the combination treatment. Moreover, vevorisertib + sorafenib treatment was associated with a normalization in the liver vasculature. Altogether, vevorisertib as a single agent and its combination with sorafenib exerted a strong suppression of tumor progression and improved liver fibrosis. Thus, results provide a rationale for testing vevorisertib in clinical settings and confirm the importance of targeting AKT in HCC.     

The effect of traditional production methods on microbial,physico‐chemical and sensory properties of ‘Slovenská bryndza’ Protected Geographical Indication cheese

Bryndza is a natural, white, mature and spreadable kind of cheese, and since 2008, it has been manufactured in specified mountainous areas of the Slovak Republic with Protected Geographical Indication. The aim of this work was to provide useful information about the microbial, physico‐chemical and sensory characteristics of bryndza, taking into consideration the variabilities related to the traditional methods of production technology of three bryndza cheese varieties. Statistically significant differences were observed in bryndza cheese production methods in chemical parameters of NaCl and malondialdehyde content (P < 0.05) and in the microbial presence of Enterococcus spp. (P < 0.001) and Staphylococcus spp. (P < 0.01).     

Reduced graphene oxide/ZnO nanocomposite modified electrode for the detection of tetracycline

Journal of Materials Science - In this work, rGO-ZnO (reduced graphene oxide–zinc oxide) nanocomposite was prepared and used for modification of GC (glassy carbon) surface in order to obtain...     

Targeting Akt in Hepatocellular Carcinoma and Its Tumor Microenvironment

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related deaths worldwide, and its incidence is rising. HCC develops almost exclusively on the background of chronic liver inflammation, which can be caused by chronic alcohol consumption, viral hepatitis, or an unhealthy diet. The key role of chronic inflammation in the process of hepatocarcinogenesis, including in the deregulation of innate and adaptive immune responses, has been demonstrated. The inhibition of Akt (also known as Protein Kinase B) directly affects cancer cells, but this therapeutic strategy also exhibits indirect anti-tumor activity mediated by the modulation of the tumor microenvironment, as demonstrated by using Akt inhibitors AZD5363, MK-2206, or ARQ 092. Moreover, the isoforms of Akt converge and diverge in their designated roles, but the currently available Akt inhibitors fail to display an isoform specificity. Thus, selective Akt inhibition needs to be better explored in the context of HCC and its possible combination with immunotherapy. This review presents a compact overview of the current knowledge concerning the role of Akt in HCC and the effect of Akt inhibition on the HCC and liver tumor microenvironment.     

Improved Production of Recombinant Myrosinase in Pichia pastoris

The effect of the deletion of a 57 bp native signal sequence, which transports the nascent protein through the endoplasmic reticulum membrane in plants, on improved AtTGG1 plant myrosinase production in Pichia pastoris was studied. Myrosinase was extracellularly produced in a 3-liter laboratory fermenter using α-mating factor as the secretion signal. After the deletion of the native signal sequence, both the specific productivity (164.8 U/L/h) and volumetric activity (27 U/mL) increased more than 40-fold compared to the expression of myrosinase containing its native signal sequence in combination with α-mating factor. The deletion of the native signal sequence resulted in slight changes in myrosinase properties: the optimum pH shifted from 6.5 to 7.0 and the maximal activating concentration of ascorbic acid increased from 1 mM to 1.5 mM. Kinetic parameters toward sinigrin were determined: 0.249 mM (K_m) and 435.7 U/mg (V_max). These results could be applied to the expression of other plant enzymes.