Marcia Helena Appel

Identification, cloning, expression and functional characterization of an astacin-like metalloprotease toxin from Loxosceles intermedia (brown spider) venom

Injuries caused by brown spiders (Loxosceles genus) are associated with dermonecrotic lesions with gravitational spreading and systemic manifestations. The venom has a complex composition containing many different toxins, of which metalloproteases have been described in many different species of this genus. These toxins may degrade extracellular matrix constituents acting as a spreading factor. By using a cDNA library from an Loxosceles intermedia venom gland, we cloned and expressed a 900 bp cDNA, which encoded a signal peptide and a propeptide, which corresponded to a 30 kDa metalloprotease, now named LALP (Loxosceles astacin-like protease). Recombinant LALP was refolded and used to produce a polyclonal antiserum, which showed cross-reactivity with a 29 kDa native venom protein. CD analysis provided evidence that the recombinant LALP toxin was folded correctly, was still in a native conformation and had not aggregated. LALP addition to endothelial cell cultures resulted in de-adhesion of the cells, and also in the degradation of fibronectin and fibrinogen (this could be inhibited by the presence of the bivalent chelator 1,10-phenanthroline) and of gelatin in vitro. Sequence comparison (nucleotide and deduced amino acid), phylogenetic analysis and analysis of the functional recombinant toxin revealed that LALP is related in both structure and function to the astacin family of metalloproteases. This suggests that an astacin-like toxin is present in a animal venom secretion and indicates that recombinant LALP will be a useful tool for future structural and functional studies on venom and the astacin family.

Histopathological findings in rabbits after experimental acute exposure to the Loxosceles intermedia (brown spider) venom

Loxoscelism, the term used to describe envenomation with brown spiders, is characterized by a dermonecrotic lesion at the bite site. In the present investigation we submitted albino rabbits to an acute experimental envenomation protocol using Loxosceles intermedia (brown spider) venom, with in order to determine the pathogenesic features of the lesion induced by this spider, which is the cause of several accidents throughout the world. Rabbits received intradermal injections of the venom and were monitored over the first 4 h, and then at 12 h and 1, 2 and 5 days after envenomation. Histological specimens from 3 rabbits per time point were collected from euthanized animals and processed for histological examination by light microscopy. Major findings observed during the first 4 h were oedema, haemorrhage, degeneration of blood vessel walls, plasma exudation, thrombosis, neutrophil accumulation in and around blood vessels with an intensive diapedesis, a diffuse collection of inflammatory cells (polymorphonuclear leucocytes) in the dermis, and subcutaneous muscular oedema. Over the following hours and up to 5 days after envenomation the changes progressed to massive neutrophil infiltration (with no other leucocytes) into the dermis and even into subcutaneous muscle tissue, destruction of blood vessels, thrombosis, haemorrhage, myonecrosis, and coagulative necrosis on the 5th day.

TCTP as a therapeutic target in melanoma treatment

Background:Translationally controlled tumour protein (TCTP) is an antiapoptotic protein highly conserved through phylogeny. Translationally controlled tumour protein overexpression was detected in several tumour types. Silencing TCTP was shown to induce tumour reversion. There is a reciprocal repression between TCTP and P53. Sertraline interacts with TCTP and decreases its cellular levels.Methods:We evaluate the role of TCTP in melanoma using sertraline and siRNA. Cell viability, migration, and clonogenicity were assessed in human and murine melanoma cells in vitro. Sertraline was evaluated in a murine melanoma model and was compared with dacarbazine, a major chemotherapeutic agent used in melanoma treatment.Results:Inhibition of TCTP levels decreases melanoma cell viability, migration, clonogenicity, and in vivo tumour growth. Human melanoma cells treated with sertraline show diminished migration properties and capacity to form colonies. Sertraline was effective in inhibiting tumour growth in a murine melanoma model; its effect was stronger when compared with dacarbazine.Conclusions:Altogether, these results indicate that sertraline could be effective against melanoma and TCTP can be a target for melanoma therapy.

The flavo-oxidase QSOX1 supports vascular smooth muscle cell migration and proliferation: Evidence for a role in neointima growth.

Quiescin sulfhydryl oxidase 1 (QSOX1) is a flavoenzyme largely present in the extracellular milieu whose physiological functions and substrates are not known. QSOX1 has been implicated in the regulation of tumor cell survival, proliferation and migration, in addition to extracellular matrix (ECM) remodeling. However, data regarding other pathophysiological conditions are still lacking. Arterial injury by balloon catheter is an established model of post-angioplasty restenosis. This technique induces neointima formation due to migration and proliferation of vascular smooth muscle cells (VSMC), followed by ECM synthesis and remodeling. Here, we show that QSOX1 knockdown inhibited VSMC migration and proliferation in vitro. In contrast, QSOX1 overexpression stimulated these processes. While migration could be induced by the incubation of cells with the active recombinant QSOX1, proliferation was induced by addition of the active and also of an inactive mutant QSOX1 protein. The proliferation induced by both recombinants was independent of intracellular hydrogen peroxide and dependent of the MEK/ERK pathway. To recapitulate in vivo VSMC pathophysiology, balloon-induced arterial injury was performed. The expression of QSOX1 in the neointimal layer of balloon-injured rat carotids was high and peaked at 14 days post-injury. In vivo QSOX1 knockdown led to a significant decrease in PCNA expression at day 14 post-injury and a decreased intima/media area ratio at day 21 post-injury, compared with scrambled siRNA transfection. In summary, our findings demonstrate that QSOX1 induces VSMC migration and proliferation in vitro and contributes to neointima thickening in balloon-injured rat carotids.

Fish Oil Supplementation Enhances Pulmonary Strength and Endurance in Women Undergoing Chemotherapy

ABSTRACT We investigated the effect of fish oil (FO) supplementation, at 4 g/day, on the respiratory performance and blood lipid profile of 32 patients with breast cancer at the beginning of chemotherapy. They were randomized into two groups: control (C) and FO supplemented (S). Both groups underwent three respiratory evaluations and blood harvest (before chemotherapy—Day 0, and 30 and 60 days after supplementation). The S group showed a significant increase in the maximal inspiratory and expiratory pressure (P ≤ 0.05 vs. Day 0) and in the maximum voluntary ventilation (P ≤ 0.05). In the treadmill 6-min-walk test, the S group had a significant increase in the walked distance (P ≤ 0.05). Blood lactate concentration was significantly lower in the S group after 60 days, at rest, when compared to C (P ≤ 0.05). Plasma high-density lipoprotein (HDL) cholesterol concentration remained the same after 60 days of supplementation, while in the C group, it decreased significantly (P ≤ 0.05 Day 0 vs. Day 60). Triacylglycerol (TAG) plasma concentration in the S group was lower when compared to the C group (P ≤ 0.05 Day 60S vs. Day 60). Supplementation with FO caused improvement in the respiratory muscle strength and endurance, ameliorated functional performance, and kept TAG, HDL cholesterol, and lactate plasma concentration at normal levels.

Quinolone resistance and ornithine decarboxylation activity in lactose-negative Escherichia coli

Quinolones and fluoroquinolones are widely used to treat uropathogenic Escherichia coli infections. Bacterial resistance to these antimicrobials primarily involves mutations in gyrA and parC genes. To date, no studies have examined the potential relationship between biochemical characteristics and quinolone resistance in uropathogenic E. coli strains. The present work analyzed the quinolone sensitivity and biochemical activities of fifty-eight lactose-negative uropathogenic E. coli strains. A high percentage of the isolates (48.3%) was found to be resistant to at least one of the tested quinolones, and DNA sequencing revealed quinolone resistant determining region gyrA and parC mutations in the multi-resistant isolates. Statistical analyses suggested that the lack of ornithine decarboxylase (ODC) activity is correlated with quinolone resistance. Despite the low number of isolates examined, this is the first study correlating these characteristics in lactose-negative E. coli isolates.