Slow intravenous administration of low dose aspirin inhibits both vascular and platelet cyclooxygenase activity: an experimental study in the rat

Aspirin irreversibly inhibits cyclooxygenase, thus preventing thromboxane (Tx)A2 production in platelets and prostacyclin in vascular cells. While it is generally accepted that the inhibitory effect of low dose aspirin is cumulative on platelet cyclooxygenase, it is still a matter of debate whether a similar phenomenon also occurs on vascular cyclooxygenase. We have measured in anesthetized rats the inhibitory effect of two doses of aspirin (2.5 and 5.0 mg/kg), given intravenously either as a bolus or as a continuous infusion (for 30 min), on platelet TxB2 and 6-ketoprostaglandin F1 alpha generation by different vascular segments. Aspirin significantly inhibited both platelet and vascular cyclooxygenase independently of the rate of drug administration. The aspirin peak plasma levels at the end of bolus injection was about 170 times higher than the average level measured during the slow infusion (1.21 +/- 0.15 micrograms/ml). At this concentration aspirin did not affect in vitro either platelet or vascular cyclooxygenase activity. Thus the inhibitory effect of aspirin on both platelet and vascular cyclooxygenase seems to be related to total exposure of the enzyme to the drug rather than to the maximal drug concentration attainable in the systemic circulation. These findings may be relevant to the current debate on optimal conditions for the biochemical selectivity of aspirin as an antithrombotic drug.     

Isolation,molecular characterization and virome analysis of culturable wood fungal endophytes in esca symptomatic and asymptomatic grapevine plants

Europe is the world largest grape producer, but in recent years, the report of diseases due to infection by grapevine trunk pathogens (GTPs) is becoming one of the main constraints for viticulture. Among grapevine trunk diseases (GTDs), esca syndrome is one of the most complex, characterized by simultaneous infection of several fungi, which leads to important reduction in yield and quality. Previous characterization of fungal isolates associated with esca syndrome leads to the recognition of at least three important players: Phaeocremonium minimum, Phaemoniella chlamydospora and Fomitiporia mediterranea. Here we isolated and characterized molecularly fungal endophytes directly from field wood tissues of plants showing or not esca symptoms. In addition, to better characterize such collection, a deep RNA sequencing (100 M reads in paired-end) to screen for mycovirus presence was performed. Thirty-nine viral genomes were detected, 38 of which were putative new viral species; some of these viruses infected GTPs, including P. minimum and F. mediterranea. In this work, we reported for the first time a curated collection of grapevine fungal endophytes identifying the associated mycoviruses some of which could be employed in future biotechnological exploitation as biological control agents for sustainable plant protection.     

Genetic transformation of fruit trees: current status and remaining challenges

Genetic transformation has emerged as a powerful tool for genetic improvement of fruit trees hindered by their reproductive biology and their high levels of heterozygosity. For years, genetic engineering of fruit trees has focussed principally on enhancing disease resistance (against viruses, fungi, and bacteria), although there are few examples of field cultivation and commercial application of these transgenic plants. In addition, over the years much work has been performed to enhance abiotic stress tolerance, to induce modifications of plant growth and habit, to produce marker-free transgenic plants and to improve fruit quality by modification of genes that are crucially important in the production of specific plant components. Recently, with the release of several genome sequences, studies of functional genomics are becoming increasingly important: by modification (overexpression or silencing) of genes involved in the production of specific plant components is possible to uncover regulatory mechanisms associated with the biosynthesis and catabolism of metabolites in plants. This review focuses on the main advances, in recent years, in genetic transformation of the most important species of fruit trees, devoting particular attention to functional genomics approaches and possible future challenges of genetic engineering for these species in the post-genomic era.     

Free fatty acid receptor 3 is a key target of short chain fatty acid: What is the impact on the sympathetic nervous system?

Nervous system (NS) activity participates in metabolic homeostasis by detecting peripheral signal molecules derived from food intake and energy balance. High quality diets are thought to include fiber-rich foods like whole grain rice, breads, cereals, and grains. Several studies have associated high consumption of fiber-enriched diets with a reduced risk of diabetes, obesity, and gastrointestinal disorders. In the lower intestine, anaerobic fermentation of soluble fibers by microbiota produces short chain fatty acids (SCFAs), key energy molecules that have a recent identified leading role in the intestinal gluconeogenesis, promoting beneficial effects on glucose tolerance and insulin resistance¹. SCFAs are also signaling molecules that bind to specific G-protein coupled receptors (GPCRs) named Free Fatty Acid Receptor 3 (FFA3, GPR41) and 2 (FFA2, GPR43). However, how SCFAs impact NS activity through their GPCRs is poorly understood. Recently, studies have demonstrated the presence of FFA2 and FFA3 in the sympathetic NS of rat, mouse and human^{2, 3}. Two studies have showed that FFA3 activation by SCFAs increases firing and norepinephrine (NE) release from sympathetic neurons^{3, 4}. However, the recent study from the Ikeda Laboratory² revealed that activation of FFA3 by SCFAs impairs N-type calcium channel (NTCC) activity, which contradicts the idea of FFA3 activation leading to increased action potential evoked NE release. Here we will discuss the scope of the latter study and the putative physiological role of SCFAs and FFAs in the sympathetic NS.     

Investigations on the turnover of adrenocortical mitochondria

The effects of chronic administration of ACTH and dexamethasone on the morphology of mitochondria in zona glomerulosa cells of the rat adrenal cortex were investigated by stereological techniques. It was found that the volume of the mitochondrial compartment as well as the surface of the outer and inner mitochondrial membranes were significantly increased or decreased in relation to the number of days of ACTH- or dexamethasone-treatment. In ACTH-administered rats, the average volume of individual mitochondria decreased significantly up to the 6th day of treatment and then showed a conspicuous increase from the 6th to the 15th day, whereas in dexamethasone administered animals this parameter, after a small increase during the first 6 days of treatment, displayed a significant decrease. The number of mitochondria per cell showed a dramatic increase during the first 6 days of treatment with ACTH and continued to increase, but only slightly, with the subsequent treatment. In contrast, this parameter showed a parabolic decrease as a function of the duration of treatment in animals receiving dexamethasone. In the light of evidence showing that dexamethasone blocks ACTH-release, these findings are discussed and interpreted to indicate that ACTH is involved in the maintenance and stimulation of the growth and proliferative activity of mitochondria in rat adrenal zona glomerulosa.     

Sea urchin embryos do not synthesize diadenosinetetraphosphate

Sea urchin embryos were labelled with [³H]adenine at two different developmental stages (cleavage and prism). Analysis by DEAE-Sephadex 7 M urea and DEAE cellulose columns of the acidsoluble nucleotide pool revealed no radioactivity under the region of the Ap₄A used as internal marker. We conclude that there is no appreciable de novo synthesis of Ap₄A during these two developmental stages.     

Design of vanadium mixed-ligand complexes as potential anti-protozoa agents

In the search for new therapeutic tools against Chagas’ disease (American Trypanosomiasis) four novel mixed-ligand vanadyl complexes, [V^IVO(L²-2H)(L¹)], including a bidentate polypyridyl DNA intercalator (L¹) and a tridentate salycylaldehyde semicarbazone derivative (L²) as ligands were synthesized, characterized by a combination of techniques, and in vitro evaluated. EPR suggest a distorted octahedral geometry with the tridentate semicarbazone occupying three equatorial positions and the polypyridyl ligand coordinated in an equatorial/axial mode. Both complexes including dipyrido[3,2-a: 2′,3′-c]phenazine (dppz) as polypyridyl coligand showed IC₅₀ values in the μM range against Dm28c strain (epimastigotes) of Trypanosoma cruzi, causative agent of the disease, being as active as the anti-trypanosomal reference drug Nifurtimox. To get an insight into the trypanocidal mechanism of action of these compounds, DNA was evaluated as a potential parasite target and EPR, and ⁵¹V NMR experiments were also carried out upon aging aerated solutions of the complexes. Data obtained by electrophoretic analysis suggest that the mechanism of action of these complexes could include DNA interactions.