Elevated cholesterol reduces acetylsalicylic acid-mediated platelet acetylation

We describe the role of plasma and platelet cholesterol content in the ability of acetylsalicylic acid (ASA) to acetylate platelet proteins and inhibit platelet function. Platelet susceptibility to ASA was monitored in subjects differing in plasma total cholesterol and in suspensions of cholesterol-enriched or cholesterol-depleted platelets. Platelets from subjects with higher plasma cholesterol (>6 mmol/l) showed reduced platelet sensitivity to ASA (inhibition of platelet aggregation and thromboxane generation by 60% and 68% in 'lower-' vs. 32% and 56% in 'higher-cholesterol' donors; n=13 in each group; p=0.056 and p<0.04, respectively). [Acetyl-1-(14)C] incorporation to platelet proteins in subjects with higher plasma cholesterol was significantly reduced (11.0 vs. 14.6 nmol/g protein, p<0.0001) and correlated significantly with blood total cholesterolemia (R(K)=-0.430, p<0.003) and LDL-cholesterol (R(K)=-0.349, p<0.012), but not with platelet cholesterol content. In conclusion, elevated plasma cholesterol is an important determinant of ASA-induced acetylation of platelets and platelet diminished sensitivity to ASA. The molecular basis of such an association remains obscure, notwithstanding it may constitute a link between sub-optimal platelet response to aspirin and lipid metabolic disorders.     

Accumulation of amino acids and phenolic compounds in biochemical plant responses to feeding of two different herbivorous arthropod pests

The study aimed at comparing the changes in the content of free amino acids, phenolic compounds and the activity of PAL and TAL caused by two piercing-sucking arthropods: the grape mealybug (Pseudococcus maritimus Ehrh.) and the two-spotted spider mite (Tetranychus urticae Koch) in the leaves of orchid and strawberry, respectively. The obtained results show that the amino acid content and the ratio of amino acids to phenolic compounds increased in both plant species infested by the mealybug and the mite. However, such response was weakly dependent on changes in activity of the analysed enzymes. The pest feeding affected accumulation of the phenolic compounds, since the induction of the PAL activity in mealybug-infested orchid leaves during the first 5 h of the experiment preceded the increase in phenolic compounds during the first week of insect feeding. Instead, the increased activity of TAL was accompanied by elevated levels of phenolic compounds in the leaves of strawberry infested by mites. Mechanisms of biochemical plant responses induced by infestation of the studied herbivorous arthropods are discussed.     

CCT chaperonins and their cochaperons

Chaperonins are large oligomers consisting of two superimposed rings, each enclosing a cavity used for the folding of other proteins. They have been divided into two groups. Chaperonins of type I were identified in mitochondria and chloroplasts (Hsp60) or bacterial cytosol (GroEL) as well. Chaperonins type II were found in Archea and the eukaryotic cell cytosol (CCT). Protein folding occurs in the chaperonin after its conformational changes induced upon ATP binding. Mechanism of the protein folding, although still poorly defined, clearly differs from the one established for GroEL. Although CCT with prefoldin seems to be mainly involved in the folding of actin and tubulin, other substrates engaged in various cellular processes are beginning to be characterized, including proteins possessing WD40-repeats. Moreover, several lines of evidence suggest that beside prefoldin, CCT may work in concert with phosducin-like proteins (PhLPs).     

Independent and combined cytotoxicity and genotoxicity of triethylene glycol dimethacrylate and urethane dimethacrylate

Dental composite materials contain polymers of methacrylates, which, due to mechanical abrasion and enzymatic action of saliva, may release their monomers into oral cavity and the pulp. Moreover, polymerization is always incomplete and leaves usually considerable fraction of free monomers. Mechanisms of the genotoxicity of methacrylate monomers have been rarely explored. As the polymerization of a monomer is catalyzed by a co-monomer, their combined action should be considered. In the present work, we investigated cytotoxic and genotoxic effects of urethane dimethacrylate (UDMA), often used as a monomer, at 1 mM, and triethylene glycol dimethacrylate (TEGDMA), a typical co-monomer, at 5 mM singly and in combination. Experiments were conducted on Chinese hamster ovary cells. Cell viability, apoptosis and cell cycle were assessed by flow cytometry, whereas DNA damage was evaluated by plasmid conformation test and comet assay. Both compounds decreased the viability of the cells, but did not induce strand breaks in an isolated plasmid DNA. However, both substances, either singly or in combination, damaged DNA in CHO cells as evaluated by comet assay. Both compounds induced apoptosis, but a combined action of them led to a decrease in the number of apoptotic cells. The combined action of UDMA and TEGDMA in the disturbance of cell cycle was lesser compared to the action of each compound individually. Individually, though UDMA and TEGDMA may induce cytotoxic and genotoxic, however, a combination of both does not produce a significant increase in these effects.     

Common variants of xeroderma pigmentosum genes and prostate cancer risk

The genetic basis of prostate cancer (PC) is complex and appears to involve multiple susceptibility genes. A number of studies have evaluated a possible correlation between several NER gene polymorphisms and PC risk, but most of them evaluated only single SNPs among XP genes and the results remain inconsistent. Out of 94 SNPs located in seven XP genes (XPA–XPG) a total of 15 SNPs were assayed in 720 unselected patients with PC and compared to 1121 healthy adults. An increased risk of disease was associated with the XPD SNP, rs1799793 (Asp312Asn) AG genotype (OR = 2.60; p < 0.001) and with the AA genotype (OR = 531; p < 0.0001) compared to the control population. Haplotype analysis of XPD revealed one protective haplotype and four associated with an increased disease risk, which showed that the A allele (XPD rs1799793) appeared to drive the main effect on promoting prostate cancer risk. Polymorphism in XPD gene appears to be associated with the risk of prostate cancer.     

Modulation of adipocyte differentiation by omega‐3 polyunsaturated fatty acids involves the ubiquitin‐proteasome system

We have evaluated the effects of three different omega‐3 polyunsaturated fatty acids (ω‐3 PUFAs) – docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA) on fat accumulation and expression of adipogenic and inflammatory markers using both 3T3‐L1 pre‐adipocytes and differentiated 3T3‐L1 adipocytes. Our results indicate that ω‐3 PUFAs induce the degradation of fatty acid synthase through the ubiquitin‐proteasome system, which is likely to have beneficial metabolic effect on adipose cells. Omega‐3 PUFAs also increase overall levels of polyubiquitinated proteins, at least in part through decreasing the expression of proteasome subunits. Moreover, adipocytes are resistant to proteasome inhibition, which induces adipophilin while decreasing perilipin expression. On the other hand, ω‐3 PUFAs decrease expression of SREBP1 while inducing expression of adipophilin and GLUT4. Moreover, all three ω‐3 PUFAs appear to induce tumour necrosis factor‐α without affecting NFκB levels. All three ω‐3 PUFAs appear to have overall similar effects. Further research is needed to elucidate their mechanism of action.     

Myofibrillar myopathy in the genomic context

Myofibrillar myopathy (MFM) is a group of inherited muscular disorders characterized by myofibril dissolution and abnormal accumulation of degradation products. The diagnosis of muscular disorders based on clinical presentation is difficult due to phenotypic heterogeneity and overlapping symptoms. In addition, precise diagnosis does not always explain the disease etiopathology or the highly variable clinical course even among patients diagnosed with the same type of myopathy. The advent of high-throughput next-generation sequencing (NGS) has provided a successful and cost-effective strategy for identification of novel causative genes in myopathies, including MFM. So far, pathogenic mutations associated with MFM phenotype, including atypical MFM-like cases, have been identified in 17 genes: DES, CRYAB, MYOT, ZASP, FLNC, BAG3, FHL1, TTN, DNAJB6, PLEC, LMNA, ACTA1, HSPB8, KY, PYROXD1, and SQSTM + TIA1 (digenic). Most of these genes are also associated with other forms of muscle diseases. In addition, in many MFM patients, numerous genomic variants in muscle-related genes have been identified. The various myopathies and muscular dystrophies seem to form a single disease continuum; therefore, gene identification in one disease impacts the genetic etiology of the others. In this review, we describe the heterogeneity of the MFM genetic background focusing on the role of rare variants, the importance of whole genome sequencing in the identification of novel disease-associated mutations, and the emerging concept of variant load as the basis of the phenotypic heterogeneity.     

Source of nitrogen as a factor limiting saponin production by hairy root and suspension cultures of <Emphasis Type="Italic">Calendula officinalis</Emphasis> L.

Triterpenic saponins represented in Calendula officinalis L. by oleanolic acid (OA) glycosides are pentacyclic triterpene compounds with a wide range of biological and medicinal properties. This report demonstrates nitrogen source impact on growth, saponin accumulation, and secretion in hairy root and suspension cultures of marigold. Hairy roots preferred nitrate as a mineral source of nitrogen, but its impact on growth, OA glycosides accumulation, and secretion were line-dependent. The best productivity of OA glycosides was found in CC16 line (74.86 mg flask^?1) in ½ MS medium modified by 2.5× KNO₃ and ammonium elimination with 2.5 g l^?1 peptone. Organic nitrogen source at 27.5-g l^?1 impairs the growth rate of hairy roots. Its effect on saponin accumulation and secretion to the surrounding medium depended on line and media composition. Nitrate:ammonium ratio of 4:2 for CC16 resulted in 5.7-fold increment of saponin secretion comparing to the standard medium. Embryo roots, apical bud, and hypocotyls explants were crucial for induction of suspension culture synthesizing saponins; however, effect of mineral form of nitrogen in cultivating medium had to be considered. The highest OA glycosides level (171.97 μg g^?1 of dry weight) was recorded in the root derived culture with nitrate as a sole mineral form of nitrogen. Peptone from lactalbumin decidedly inhibited the saponin formation; however, it was essential for culture initiation, proliferation, and organ differentiation.