Rodrigo A. Silva

Structural and proactive safety aspects of oxidation debris from multiwalled carbon nanotubes

The removal of oxidation debris from the oxidized carbon nanotube surface with a NaOH treatment is a key step for an effective functionalization and quality improvement of the carbon nanotube samples. In this work, we show via infrared spectroscopy and ultrahigh resolution and accuracy mass spectrometry that oxidation debris obtained from HNO(3)-treated multiwalled carbon nanotubes is a complex mixture of highly condensed aromatic oxygenated carbonaceous fragments. We have also evaluated their cytotoxicity by using BALB/c 3T3 mouse fibroblasts and HaCaT human keratinocytes as models. By knowing the negative aspects of dissolved organic carbon (DOC) to the water quality, we have demonstrated the removal of these carbon nanotube residues from the NaOH solution (wastewater) by using aluminium sulphate, which is a standard coagulant agent used in conventional drinking water purification and wastewater treatment plants. Our results contribute to elucidate the structural and proactive safety aspects of oxidation debris from oxidized carbon nanotubes towards a greener nanotechnology.

Anti-inflammatory properties of a heparin-like glycosaminoglycan with reduced anti-coagulant activity isolated from a marine shrimp.

The anti-inflammatory properties of a heparin-like compound from the shrimp Litopenaeus vannamei are related. Besides reducing significantly (p<0.001) the influx of inflammatory cells to injury site in a model of acute inflammation, shrimp heparin-like compound was able to reduce the matrix metalloproteinase (MMPs) activity in the peritoneal lavage of inflamed animals. Moreover, this compound also reduced almost 90% the activity of MMP-9 secreted by human activated leukocytes. Negligible anti-coagulant activities in aPPT assay and a poor bleeding potential make this compound a better alternative than mammalian heparin as a possible anti-inflammatory drug.

Inhibition of tumor growth by quercetin with increase of survival and prevention of cachexia in Walker 256 tumor-bearing rats.

Quercetin, a flavonoid abundantly present in fruit, vegetables, wine and tea, has revealed several properties such as antioxidant, antiproliferative and anticancer. Cachexia is a poorly understood syndrome present in already compromised cancer patients, decreasing the quality of life and increasing mortality. Many studies have been performed in an attempt to discover an effective treatment for cachexia, but none of the tested therapies has fulfilled expectations. The objective of the present study was to analyze the effect of quercetin in the therapeutic treatment of cachexia and reversion of tumor growth in rats bearing Walker 256 carcinosarcoma (W256). Rats bearing W256 were treated daily with I.P. quercetin injections, at different doses (10, 15, 25 and 35 mg/kg). The results show that 10 mg/kg quercetin inhibited tumor growth by about 50% (ED(50)) when compared with controls (CTR). Moreover, two animals of this group presented complete tumor regression. Matrix metalloproteinase-2 (MMP-2) activity and vascular endothelial growth factor (VEGF) expression decreased in rats bearing W256 treated with 10 mg/kg quercetin when compared with CTR. Thus, the inhibition of tumor growth, survival increase, decrease of MMP-2 and VEGF levels and reduction of cachexia in animals treated with quercetin strongly support the anticancer function of this flavonoid.

Phosphoproteome Reveals an Atlas of Protein Signaling Networks During Osteoblast Adhesion

Cell adhesion on surfaces is a fundamental process in the emerging biomaterials field and developmental events as well. However, the mechanisms regulating this biological process in osteoblasts are not fully understood. Reversible phosphorylation catalyzed by kinases is probably the most important regulatory mechanism in eukaryotes. Therefore, the goal of this study is to assess osteoblast adhesion through a molecular prism under a peptide array technology, revealing essential signaling proteins governing adhesion‐related events. First, we showed that there are main morphological changes on osteoblast shape during adhesion up to 3 h. Second, besides classical proteins activated upon integrin activation, our results showed a novel network involving signaling proteins such as Rap1A, PKA, PKC, and GSK3β during osteoblast adhesion on polystyrene. Third, these proteins were grouped in different signaling cascades including focal adhesion establishment, cytoskeleton rearrangement, and cell‐cycle arrest. We have thus provided evidence that a global phosphorylation screening is able to yield a systems‐oriented look at osteoblast adhesion, providing new insights for understanding of bone formation and improvement of cell–substratum interactions. Altogether, these statements are necessary means for further intervention and development of new approaches for the progress of tissue engineering. J. Cell. Biochem. 109: 957–966, 2010.

Environmental heterogeneity: Anuran diversity in homogeneous environments

The northwestern region of Sao Paulo was extensively deforested during the agricultural expansion in the last century and only small fragments of the original vegetation cover remained. In this study, we investigated how habitat features influence the composition, richness, and diversity of anurans in environments homogenized by agricultural activities. We sampled monthly six breeding ponds located in pasture areas during twelve months. We recorded ten environmental descriptors for each breeding pond. We found 18 anuran species. The breeding ponds were structurally similar, but species composition differed among them. The environmental descriptors influence varies for each species, as demonstrated by the different associations between species and environmental descriptors shown in the Canonical Correspondence Analysis (CCA). Seven of the ten environmental descriptors explained 67% of the species richness, showing that environmental characteristics influenced the occurrence of the different species. There is no such data set for the region and also for most Brazilian regions, despite its importance in guiding species-oriented conservation actions.

Bioacústica e sítio de vocalização em taxocenoses de anuros de área aberta no noroeste paulista

The calling site and the acoustic parameters of the advertisement call were determined for 18 anuran species in six ponds in the northwest region of Sao Paulo State. The dominant frequency of the advertisement call was positively correlated with the CRC of the species: small size species vocalized in a higher frequency, whereas larger species vocalized in a lower frequency. The similarity in the spectral and temporal parameters of the advertisement call was high among 94% of the recorded species. The similarity on calling site was low; only 22% of species presented high overlap, in spite of about a half of the species have been generalist in calling site use. Analysing simultaneously the similarity on calling site, habitat and advertisement call parameters, the proportion of species with high overlap decreased from 94 to 11%, corresponding to the overlap between a single pair of species: Dendropsophus elianeae and D. minutus. The species that overlap in calling site presented segregation in acoustic parameters, and those that overlap in acoustic parameters tended to partition the calling site. This result suggests the occurrence of niche complementarity, since species that occupied a similar position in one dimension tended to differ in another dimension. The structural homogeneity of ponds, the climatic severity of the region and the high degree of habitat loss restrict the abundance of population and the species richness of the anuran assemblages. The low overlap on the calling site is probably associated with the insaturation of the sampled communities.

Pouterin, a novel potential cytotoxic lectin-like protein with apoptosis-inducing activity in tumorigenic mammalian cells

In this study, the cytotoxicity of pouterin in tumorigenic and non-tumorigenic mammalian cell lines was investigated. We found that HeLa, Hep-2 and HT-29 tumor cells were highly sensitive to pouterin cytotoxicity in a dose-dependent manner, whereas non-tumorigenic Vero cells and human lymphocytes were relatively resistant to the protein. Among the tumor cell lines, HeLa cells showed the highest susceptibility to pouterin cytotoxicity, exhibiting a time-dependent increase in LDH leakage and an IC(50) value of 5mug/mL. Morphological alterations such as rounding, cell shrinkage and chromatin condensation, consistent with apoptotic cell death were observed. Apoptosis induction was demonstrated by DNA fragmentation as detected by terminal dUTP nick-end labeling (TUNEL). Furthermore, HeLa cells incubated with pouterin showed disruption of the actin cytoskeleton. Western blot analysis revealed that pouterin caused increased expression of p21, thus indicating cell cycle arrest. Subsequent studies provided evidence that apoptosis may be partially explained in the activation of the tumor necrosis factor receptor 1 (TNFR1) signaling. Interestingly, a time-dependent decrease of the expression of p65 nuclear factor kappa B (NFkappaB) subunit, concomitant with a downregulation of the inhibitor of apoptosis protein 1 (IAP1) was observed, suggesting that TNFR-mediated apoptosis is the predominant pathway induced by pouterin in HeLa cells.

Antioxidant and Antiproliferative Activities of Methanolic Extract from a Neglected Agricultural Product: Corn Cobs

Neglected agricultural products (NAPs) are defined as discarded material in agricultural production. Corn cobs are a major waste of agriculture maize. Here, a methanolic extract from corn cobs (MEC) was obtained. MEC contains phenolic compounds, protein, carbohydrates (1.4:0.001:0.001). We evaluated the in vitro and in vivo antioxidant potential of MEC. Furthermore, its antiproliferative property against tumor cells was assessed through MTT assays and proteins related to apoptosis in tumor cells were examined by western blot. MEC showed no hydroxyl radical scavenger capacity, but it showed antioxidant activity in Total Antioxidant Capacity and DPPH scavenger ability assays. MEC showed higher Reducing Power than ascorbic acid and exhibited high Superoxide Scavenging activity. In tumor cell culture, MEC increased catalase, metallothionein and superoxide dismutase expression in accordance with the antioxidant tests. In vivo antioxidant test, MEC restored SOD and CAT, decreased malondialdehyde activities and showed high Trolox Equivalent Antioxidant Capacity in animals treated with CCl4. Furthermore, MEC decreased HeLa cells viability by apoptosis due an increase of Bax/Bcl-2 ratio, caspase 3 active. Protein kinase C expression increased was also detected in treated tumor cells. Thus, our findings pointed out the biotechnological potential of corn cobs as a source of molecules with pharmacological activity.

In vitro cytotoxicity assays of solid lipid nanoparticles in epithelial and dermal cells

In recent years, the interest in nanostructured systems to drug delivery has increased because they offer several advantages over conventional dosage forms. Solid Lipid Nanoparticles (SLN) have been highlighted among these systems because they have advantages such as high physical stability, protection against drug degradation and ease of scale-up and manufacturing, without using organic solvent. The aim of this work was to evaluate the potential of SLN, by in vitro cytotoxicity assays, for dermal drug delivery. SLN of three different lipids were prepared by hot high pressure homogenization and the cytotoxicity was assessed by 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test in mouse 3T3 fibroblasts and human HaCaT keratinocytes. SLN showed no cytotoxic potential suggesting a great potential for dermal application.

Topology-Aware Virtual Machine Placement in Data Centers

This paper presents the Topology-aware Virtual Machine Placement algorithm, which aims at placing groups of virtual machines in data centers. It was designed to occupy small areas of the data center network in order to consolidate the network flows produced by the virtual machines. Extensive simulation is used to show that the proposed algorithm prevents the formation of network bottlenecks, therefore accepting more requests of allocation of virtual machines. Moreover, these advantages are obtained without compromising energy efficiency. The energy consumption of servers and switches are taken into account, and these are switched off whenever idle.This paper presents the Topology-aware Virtual Machine Placement algorithm, which aims at placing groups of virtual machines in data centers. It was designed to occupy small areas of the data center network in order to consolidate the network flows produced by the virtual machines. Extensive simulation is used to show that the proposed algorithm prevents the formation of network bottlenecks, therefore accepting more requests of allocation of virtual machines. Moreover, these advantages are obtained without compromising energy efficiency. The energy consumption of servers and switches are taken into account, and these are switched off whenever idle.