PON1 Paraoxonase Activity is Reduced During HDL Oxidation and is an Indicator of HDL Antioxidant Capacity

The aim of this study was to investigate the effect of HDL oxidation on PON1 paraoxonase activity. Also, we were interested in investigating the mechanism by which PON1 could be inactivated and the correlation between its enzymatic activity and the antioxidant properties of HDL. Three different oxidation systems were used for the HDL oxidation: (1) oxidation induced by THP1 cells, (2) oxidation induced by copper ions at a concentration 10 &#119 M, and (3) oxidation induced by &#148 OH and O 2 &#148 &#109 oxygen free radicals produced by &#110 -radiolysis. HDL oxidation was followed by the measurement of lipid peroxide formation, and PON1 activity was determined by measuring the rate of paraoxon hydrolysis. Our results show that HDL oxidation is accompanied by a reduction in the PON1 paraoxonase activity. The extent of PON1 inactivation depends both on the extent of HDL oxidation and on the oxidation system used. The rates of HDL oxidation and PON1 inactivation were significantly correlated ( r =0.93, p <0.0054). Our results show that oxidized HDL loses its protective effect toward LDL oxidation. The antioxidant action of HDL towards LDL oxidation and the degradation of PON1 paraoxonase activity were significantly correlated ( r =0.95, p <0.04).     

Extra EF Hand Unit (DX) Mediated Stabilization and Calcium Independency of α-Amylase

It is the common feature of α-amylases that calcium ion is required for their structural integrity and thermal stability. All amylases have at least one Ca²⁺ per molecule; therefore amino acids involved in calcium binding are specific and conserved. In this study, sequence analysis revealed the presence of EF-hand-like motif in calcium-binding loop of Bacillus megaterium WHO (BMW)-amylase that was previously isolated from BMW. The EF-hand motif and its variants (EF-hand-like motif) are the most common calcium-binding motifs found in a large number of protein families. To investigate the effect of calcium ion on the thermal stability and activity of BMW-amylase, we used site-directed mutagenesis to replace histidine 58 with Asp (D), Ile (I), Tyr (Y), Phe (F), and Arg (R) at the seventh position of EF-hand-like motif. Upon the addition of an extra DX unit to the calcium-binding loop in H58D variant, thermal stability, catalytic activity, and chelating power of the enzyme improved due to higher affinity toward calcium. H58D variant demonstrated calcium independency compared to the wild type and other created mutants. Conformational changes in the presence and absence of Ca²⁺ were monitored using fluorescence technique.     

Self‐assembly of designed coiled coil peptides studied by small‐angle X‐ray scattering and analytical ultracentrifugation

α‐Helical coiled coil structures, which are noncovalently associated heptad repeat peptide sequences, are ubiquitous in nature. Similar amphipathic repeat sequences have also been found in helix‐containing proteins and have played a central role in de novo design of proteins. In addition, they are promising tools for the construction of nanomaterials. Small‐angle X‐ray scattering (SAXS) has emerged as a new biophysical technique for elucidation of protein topology. Here, we describe a systematic study of the self‐assembly of a small ensemble of coiled coil sequences using SAXS and analytical ultracentrifugation (AUC), which was correlated with molecular dynamics simulations. Our results show that even minor sequence changes have an effect on the folding topology and the self‐assembly and that these differences can be observed by a combination of AUC, SAXS, and circular dichroism spectroscopy. A small difference in these methods was observed, as SAXS for one peptide and revealed the presence of a population of longer aggregates, which was not observed by AUC. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Preconditioning with diosgenin and treadmill exercise preserves the cardiac toxicity of isoproterenol in rats

This study was aimed to evaluate the preventive effect of diosgenin and exercise on tissue antioxidant status in isoproterenol-induced myocardial infarction (MI) in male Wistar rats. Levels of lipid peroxides, reduced glutathione (GSH), and the activities of glutathione-dependent antioxidant enzymes (glutathione peroxidise and glutathione reductase) and antiperoxidative enzymes (catalase and superoxide dismutase) in the plasma and the heart tissue of experimental groups of rats were determined. Pretreatment with diosgenin and exercise exerted an antioxidant effect against isoproterenol-induced myocardial infarction by blocking the induction of lipid peroxidation. A tendency to prevent the isoproterenol-induced alterations in the level of GSH, in the activities of glutathione-dependent antioxidant enzymes and antiperoxidative enzymes was also observed. Histopathological findings of the myocardial tissue showed a protective role for combination of diosgenin and exercise in isoproterenol (ISO)-treated rats. Thus, the present study reveals that preconditioning with diosgenin and exercise exerts cardioprotective effect against ISO-induced MI due to its free radical scavenging and antioxidant effects, which maintains the tissue defense system against myocardial damage.     

Cytosolic phospholipase A2α sustains pAKT,pERK and AR levels in PTEN-null/mutated prostate cancer cells

Constitutive phosphorylation of protein kinase B (AKT) is a common feature of cancer caused by genetic alteration in the phosphatase and tensin homolog (PTEN) gene and is associated with poor prognosis. This study determined the role of cytosolic phospholipase A₂α (cPLA₂α) in AKT, extracellular signal-regulated kinase (ERK) and androgen receptor (AR) signaling in PTEN-null/mutated prostate cancer cells. Doxycycline (Dox)-induced expression of cPLA₂α led to an increase in pAKT, pGSK3β and cyclin D1 levels in LNCaP cells that possess a PTEN frame-shift mutation. In contrast, silencing cPLA₂α expression with siRNA decreased pAKT, pGSK3β and cyclin D1 levels in both PC-3 (PTEN deletion) and LNCaP cells. Silencing of cPLA₂α decreased pERK and AR protein levels. The inhibitory effect of cPLA₂α siRNA on pAKT and AR protein levels was reduced by the addition of arachidonic acid (AA), whereas the stimulatory effect of AA on pAKT, pERK and AR levels was decreased by an inhibitor of 5-hydroxyeicosatetraenoic acid production. Pharmacological blockade of cPLA₂α with Efipladib reduced pAKT and AR levels with a concomitant inhibition of PC-3 and LNCaP cell proliferation. These results demonstrate an important role for cPLA₂α in sustaining AKT, ERK and AR signaling in PTEN-null/mutated prostate cancer cells and provide a potential molecular target for treating prostate cancer.     

Phylogenetic Analysis Reveals a High Prevalence of Sporothrix brasiliensis in Feline Sporotrichosis Outbreaks

Sporothrix schenckii, previously assumed to be the sole agent of human and animal sporotrichosis, is in fact a species complex. Recently recognized taxa include S. brasiliensis, S. globosa, S. mexicana, and S. luriei, in addition to S. schenckii sensu stricto. Over the last decades, large epidemics of sporotrichosis occurred in Brazil due to zoonotic transmission, and cats were pointed out as key susceptible hosts. In order to understand the eco-epidemiology of feline sporotrichosis and its role in human sporotrichosis a survey was conducted among symptomatic cats. Prevalence and phylogenetic relationships among feline Sporothrix species were investigated by reconstructing their phylogenetic origin using the calmodulin (CAL) and the translation elongation factor-1 alpha (EF1α) loci in strains originated from Rio de Janeiro (RJ, n = 15), Rio Grande do Sul (RS, n = 10), Paraná (PR, n = 4), São Paulo (SP, n = 3) and Minas Gerais (MG, n = 1). Our results showed that S. brasiliensis is highly prevalent among cats (96.9%) with sporotrichosis, while S. schenckii was identified only once. The genotype of Sporothrix from cats was found identical to S. brasiliensis from human sources confirming that the disease is transmitted by cats. Sporothrix brasiliensis presented low genetic diversity compared to its sister taxon S. schenckii. No evidence of recombination in S. brasiliensis was found by split decomposition or PHI-test analysis, suggesting that S. brasiliensis is a clonal species. Strains recovered in states SP, MG and PR share the genotype of the RJ outbreak, different from the RS clone. The occurrence of separate genotypes among strains indicated that the Brazilian S. brasiliensis epidemic has at least two distinct sources. We suggest that cats represent a major host and the main source of cat and human S. brasiliensis infections in Brazil.     

SIVcpz cross-species transmission and viral evolution toward HIV-1 in a humanized mouse model

HIV-1 evolved from its progenitor SIV strains, but details are lacking on its adaptation to the human host. We followed the evolution of SIVcpz in humanized mice to mimic cross-species transmission. Increasing viral loads, CD4⁺ T-cell decline, and non-synonymous mutations were seen in the entire genome reflecting viral adaptation.     

LED light mediates phenolic accumulation and enhances antioxidant activity in Melissa officinalis L. under drought stress condition

The popularity of lemon balm in conventional medicine is suggested by the existence of two groups of compounds, namely essential oil and phenylpropanoids pathway derivatives. One of the promising approaches to improve tolerance to drought stress induced oxidative damage in seedlings grown in greenhouses and plant growth chambers is replacing the traditional and high-cost light technologies by recently developed light emitting diodes (LED). In this experiment, we analyzed the role of various LED lights including red (R), blue (B), red (70%) + blue (30%) (RB), and white (W) as well as normal greenhouse light (as control) to stimulate defense mechanisms against drought stress in two genotypes of Melissa officinalis L. The present study demonstrates that pre-treatment with LEDs with high-intensity output for 4 weeks alleviated harmful effects of drought stress in the two genotypes. Under drought stress, RB LED pre-treated plantlets of the two genotypes exhibited the highest relative growth index of shoot and root and total phenolic and anthocyanin content compared to those irradiated with other LEDs and greenhouse lights. The highest amount of malondialdehyde level was detected in R LED exposed plants. In response to drought, LED-exposed plants especially RB light-irradiated plants of the two genotypes maintained significantly higher antioxidant and phenylalanine ammonia-lyase (PAL) enzyme activities and higher expression level of the PAL1 and 4CL-1 genes compared to those irradiated with greenhouse light. We concluded that RB LED light provides a better growth condition and resistance to drought stress for the two genotypes of lemon balm by the highest antioxidant activity and the least amount of damage to the cell membranes. Our data suggest that LED light pre-treatments as moderate stress activate antioxidant systems, enhance the scavenging of ROS and induce drought stress tolerance in the two genotypes of lemon balm plants.

     

Mimicking SIV chimpanzee viral evolution toward HIV-1 during cross-species transmission

HIV-1 evolved from SIV during cross-species transmission events, though viral genetic changes are not well understood. Here, we studied the evolution of SIVcpzLB715 into HIV-1 Group M using humanized mice. High viral loads, rapid CD4⁺ T-cell decline, and non-synonymous substitutions were identified throughout the viral genome suggesting viral adaptation.     

Assessment of Heavy Metal Pollution and Human Health Risks Assessment in Soils Around an Industrial Zone in Neyshabur,Iran

Biological Trace Element Research - Heavy metal pollution of soils in industrial zones continues to attract attention because of its potential human health risks. The present research is an attempt...