A haplotype in the dipeptidyl peptidase 4 gene impacts glycemic-related traits of Brazilian older adults.

Dipeptidyl peptidase 4 (DPP4) regulates various physiological pathways and has a pivotal role in glucose homeostasis. The objective of this study was to verify the association of a haplotype constituted by two single nucleotide polymorphisms (rs2268894 and rs6741949) in the DPP4 gene with type 2 diabetes mellitus (T2DM) and fasting glycemia-related variables in a sample of Brazilian older adults, taking serum levels and enzymatic activity of DPP4 into account. Clinical, biochemical, and anthropometric characteristics as well as DPP4 serum levels and enzymatic activity were determined in 800 elderly (≥60 years old) individuals. Assessment of polymorphic sites was performed by real-time PCR whereas haplotypes were inferred from genotypic frequencies. Statistical analyses compared measures and proportions according to T2DM diagnosis and DPP4 haplotypic groups. The most common haplotype consisted of the T-rs2268894/G-rs6741949 string, which was 20% more frequent among non-diabetics. Considering non-diabetic patients alone, carriers of the T/G haplotype had significantly lower levels of blood glucose, insulin, HOMA-IR index, and DPP4 activity. Among diabetic patients, the T/G haplotype was associated with lower DPP4 levels whereas glycemic scores were not affected by allelic variants. Our results suggested that the genetic architecture of DPP4 affects the glycemic profile and DPP4 serum levels and activity among elderly individuals according to the presence or absence of T2DM, with a possible implication of the T/G haplotype to the risk of T2DM onset.

A haplotype in the dipeptidyl peptidase 4 gene impacts glycemic-related traits of Brazilian older adults

Dipeptidyl peptidase 4 (DPP4) regulates various physiological pathways and has a pivotal role in glucose homeostasis. The objective of this study was to verify the association of a haplotype constituted by two single nucleotide polymorphisms (rs2268894 and rs6741949) in the DPP4 gene with type 2 diabetes mellitus (T2DM) and fasting glycemia-related variables in a sample of Brazilian older adults, taking serum levels and enzymatic activity of DPP4 into account. Clinical, biochemical, and anthropometric characteristics as well as DPP4 serum levels and enzymatic activity were determined in 800 elderly (≥60 years old) individuals. Assessment of polymorphic sites was performed by real-time PCR whereas haplotypes were inferred from genotypic frequencies. Statistical analyses compared measures and proportions according to T2DM diagnosis and DPP4 haplotypic groups. The most common haplotype consisted of the T-rs2268894/G-rs6741949 string, which was 20% more frequent among non-diabetics. Considering non-diabetic patients alone, carriers of the T/G haplotype had significantly lower levels of blood glucose, insulin, HOMA-IR index, and DPP4 activity. Among diabetic patients, the T/G haplotype was associated with lower DPP4 levels whereas glycemic scores were not affected by allelic variants. Our results suggested that the genetic architecture of DPP4 affects the glycemic profile and DPP4 serum levels and activity among elderly individuals according to the presence or absence of T2DM, with a possible implication of the T/G haplotype to the risk of T2DM onset.

Schistocins: Novel antimicrobial peptides encrypted in the Schistosoma mansoni Kunitz Inhibitor SmKI-1.

BACKGROUND: Here we describe a new class of cryptides (peptides encrypted within a larger protein) with antimicrobial properties, named schistocins, derived from SmKI-1, a key protein in Shistosoma mansoni survival. This is a multi-functional protein with biotechnological potential usage as a therapeutic molecule in inflammatory diseases and to control schistosomiasis. METHODS: We used our algorithm enCrypted, to perform an in silico proteolysis of SmKI-1 and a screening for potential antimicrobial activity. The selected peptides were chemically synthesized, tested in vitro and evaluated by both structural (CD, NMR) and biophysical (ITC) studies to access their structure-function relationship. RESULTS: EnCrypted was capable of predicting AMPs in SmKI-1. Our biophysical analyses described a membrane-induced conformational change from random coil-to-α-helix and a peptide-membrane equilibrium for all schistocins. Our structural data allowed us to suggest a well-known mode of peptide-membrane interaction in which electrostatic attraction between the cationic peptides and anionic membranes results in the bilayer disordering. Moreover, the NMR H/D exchange data with the higher entropic contribution observed for the peptide-membrane interaction showed that schistocins have different orientations upon the membrane. CONCLUSIONS: This work demonstrate the robustness for using the physicochemical features of predicted peptides in the identification of new bioactive cryptides. Besides, it demonstrates the relevance of combining these analyses with biophysical methods to understand the peptide-membrane affinity and improve further algorithms. GENERAL SIGNIFICANCE: Bioprospecting cryptides can be conducted through data mining of protein databases demonstrating the success of our strategy. The peptides-based agents derived from SmKI-1 might have high impact for system-biology and biotechnology.

The APOB rs693 polymorphism impacts the lipid profile of Brazilian older adults.

The apolipoprotein B (APOB) gene contains several polymorphic sites described as risk modifiers for cardiovascular events. The objective of this study was to verify the association of the classic APOB Xba I polymorphism (rs693) with atherosclerotic risk factors in a segment of the Brazilian elderly population considering their usual dietary intake. Clinical and biochemical characteristics as well as total caloric and fat intake data were determined from 644 elderly individuals. Polymorphism analysis was performed by conventional polymerase chain reaction followed by enzyme restriction. Statistical analyses compared measures and proportions according to different APOB genotypic combinations. Statistically significant association was found between Xba I polymorphism and serum LDL, total cholesterol, and total lipid levels, with important elevations among T homozygotes compared to the other genotypes. There was homogeneity in all other parameters analyzed (including intake pattern), with a tendency for reduced levels of circulating apolipoprotein B among TT individuals. Our results pointed out that genetic variation in APOB affected the lipemic profile of elderly individuals in a context not biased by diet, generating a pattern suggestive of secretory disorder of lipoprotein particles, with possible implication in atherosclerotic risk.

The APOB rs693 polymorphism impacts the lipid profile of Brazilian older adults

The apolipoprotein B (APOB) gene contains several polymorphic sites described as risk modifiers for cardiovascular events. The objective of this study was to verify the association of the classic APOB Xba I polymorphism (rs693) with atherosclerotic risk factors in a segment of the Brazilian elderly population considering their usual dietary intake. Clinical and biochemical characteristics as well as total caloric and fat intake data were determined from 644 elderly individuals. Polymorphism analysis was performed by conventional polymerase chain reaction followed by enzyme restriction. Statistical analyses compared measures and proportions according to different APOB genotypic combinations. Statistically significant association was found between Xba I polymorphism and serum LDL, total cholesterol, and total lipid levels, with important elevations among T homozygotes compared to the other genotypes. There was homogeneity in all other parameters analyzed (including intake pattern), with a tendency for reduced levels of circulating apolipoprotein B among TT individuals. Our results pointed out that genetic variation in APOB affected the lipemic profile of elderly individuals in a context not biased by diet, generating a pattern suggestive of secretory disorder of lipoprotein particles, with possible implication in atherosclerotic risk.

Antimicrobial alumina nanobiostructures of disulfide- and triazole-linked peptides: Synthesis, characterization, membrane interactions and biological activity.

Due to the its physical-chemical properties, alumina nanoparticles have potential applications in several areas, such as nanobiomaterials for medicinal or orthodontic implants, although the introduction of these devices poses a serious risk of microbial infection. One convenient strategy to circumvent this problem is to associate the nanomaterials to antimicrobial peptides with broad-spectrum of activities. In this study we present two novel synthesis approaches to obtain fibrous type alumina nanoparticles covalently bound to antimicrobial peptides. In the first strategy, thiol functionalized alumina nanoparticles were linked via disulfide bond formation to a cysteine residue of an analog of the peptide BP100 containing a four amino acid spacer (Cys-Ala-Ala-Ala). In the second strategy, alumina nanoparticles were functionalized with azide groups and then bound to alkyne-decorated analogs of the peptides BP100 and DD K through a triazole linkage obtained via a copper(I)-catalyzed cycloaddition reaction. The complete physical-chemical characterization of the intermediates and final materials is presented along with in vitro biological assays and membrane interaction studies, which confirmed the activity of the obtained nanobiostructures against both bacteria and fungi. To our knowledge, this is the first report of aluminum nanoparticles covalently bound to triazole-peptides and to a disulfide bound antimicrobial peptide with high potential for biotechnological applications.

Assessment of the ozone tolerance of two soybean cultivars (Glycine max cv. Sambaíba and Tracajá) cultivated in Amazonian areas.

Brazilian soybean cultivars (Glycine max Sambaíba and Tracajá) routinely grown in Amazonian areas were exposed to filtered air (FA) and filtered air enriched with ozone (40 and 80 ppb, 6 h/day for 5 days) to assess their level of tolerance to this pollutant by measuring changes in key biochemical, physiological, and morphological indicators of injury and in enzymatic and non-enzymatic antioxidants. Sambaíba plants were more sensitive to ozone than Tracajá plants, as revealed by comparing indicator injury responses and antioxidant stimulations. Sambaíba exhibited higher visible leaf injury, higher stomatal conductance, and a severe decrease in the carbon assimilation rate. Higher ozone level (80 ppb) caused an increase in cell death in both cultivars. Levels of malondialdehyde and hydrogen peroxide also increased in Tracajá exposed under 80 ppb. Sambaíba plants exhibited decreases in ascorbate and glutathione levels and in enzymatic activities associated with these antioxidants. The higher tolerance of the Tracajá soybean appeared to be indicated by reduced physiological injuries and lower stomatal conductance, which might decrease the influx of ozone and enhance oxidation-reduction reactions involving catalase, ascorbate peroxidase, ascorbate, and glutathione, most likely stimulated by higher hydrogen peroxide.

Effect of exhaustive ultra-endurance exercise in muscular glycogen and both Alpha1 and Alpha2 Ampk protein expression in trained rats

Glycogen is the main store of readily energy in skeletal muscle and plays a key role in muscle function, demonstrated by the inability to sustain prolonged high-intensity exercise upon depletion of these glycogen stores. With prolonged exercise, glycogen depletion occurs and 5Œ-AMP-activated protein kinase (AMPK), a potent regulator of muscle metabolism and gene expression, is activated promoting molecular signalling that increases glucose uptake by muscular skeletal cells. The aim of this study was primarily to determine the effect of ultra-endurance exercise on muscle glycogen reserves and secondly to verify the influence of this type of exercise on AMPK protein expression. Twenty-four male Wistar rats, 60 days old, were divided into four experimental groups: sedentary, sedentary exhausted (SE), endurance trained (T) and endurance trained exhausted (TE). The animals ran for 10 to 90 min/day, 5 days/week, for 12 weeks to attain trained status. Rats were killed immediately after the exhaustion protocol, which consisted of running on a treadmill (at approximately 60 % Vmax until exhaustion). Optical density of periodic acid-Schiff was detected and glycogen depletion observed predominantly in type I muscle fibres of the TE group and in both type I and II muscle fibres in the SE group. Plasma glucose decreased only in the TE group. Hepatic glycogen was increased in T group and significantly depleted in TE group. AMPK protein expression was significantly elevated in TE and T groups. In conclusion, acute exhaustive ultra-endurance exercise promoted muscle glycogen depletion. It seems that total AMPK protein and gene expression is more influenced by status training (AU)

Effect of exhaustive ultra-endurance exercise in muscular glycogen and both Alpha1 and Alpha2 Ampk protein expression in trained rats.

Glycogen is the main store of readily energy in skeletal muscle and plays a key role in muscle function, demonstrated by the inability to sustain prolonged high-intensity exercise upon depletion of these glycogen stores. With prolonged exercise, glycogen depletion occurs and 5'-AMP-activated protein kinase (AMPK), a potent regulator of muscle metabolism and gene expression, is activated promoting molecular signalling that increases glucose uptake by muscular skeletal cells. The aim of this study was primarily to determine the effect of ultra-endurance exercise on muscle glycogen reserves and secondly to verify the influence of this type of exercise on AMPK protein expression. Twenty-four male Wistar rats, 60 days old, were divided into four experimental groups: sedentary, sedentary exhausted (SE), endurance trained (T) and endurance trained exhausted (TE). The animals ran for 10 to 90 min/day, 5 days/week, for 12 weeks to attain trained status. Rats were killed immediately after the exhaustion protocol, which consisted of running on a treadmill (at approximately 60% Vmax until exhaustion). Optical density of periodic acid-Schiff was detected and glycogen depletion observed predominantly in type I muscle fibres of the TE group and in both type I and II muscle fibres in the SE group. Plasma glucose decreased only in the TE group. Hepatic glycogen was increased in T group and significantly depleted in TE group. AMPK protein expression was significantly elevated in TE and T groups. In conclusion, acute exhaustive ultra-endurance exercise promoted muscle glycogen depletion. It seems that total AMPK protein and gene expression is more influenced by status training.

Chronic exercise promotes alterations in the neuroendocrine profile of elderly people.

Aging and physical inactivity are 2 factors that favour the development of cardiovascular disease, metabolic syndrome, obesity, and diabetes. In contrast, adopting a habitual moderate exercise routine may be a nonpharmacological treatment alternative for neuroendocrine aging disorders. We aimed to assess the effects of moderate exercise training on the metabolic profiles of elderly people with sedentary lifestyles. Fourteen sedentary, healthy, elderly male volunteers participated in a moderate training regimen for 60 min/day, 3 days/week for 24 weeks at a work rate equivalent to their ventilatory aerobic threshold. The environment was maintained at a temperature of 23±2°C, with a humidity of 60±5%. Blood samples for analysis were collected at 3 intervals: at baseline (1 week before training began), and 3 and 6 months after training. The training promoted increased aerobic capacity (relative VO(2), and time and velocity to VO(2)max; (p<0.05)) and reduced serum α-MSH (p<0.05) after 3 months of training when compared with the baseline data. In addition, serum thyroid hormone (T3 and T4) was reduced after 6 months of training compared with baseline levels. Our results demonstrate that a moderate exercise training protocol improves the metabolic profile of older people, and metabolic adaptation is dependent on time.

The use of a Ga+ focused ion beam to modify graphene for device applications.

In this work, we clarify the features of the lateral damage of line defects in single layer graphene. The line defects were produced through well-controlled etching of graphene using a Ga(+) focused ion beam. The lateral damage length was obtained from both the integrated intensity of the disorder induced Raman D band and the minimum ion fluence. Also, the line defects were characterized by polarized Raman spectroscopy. It was found that graphene is resilient under the etching conditions since the intensity of the defect induced Raman D peak exhibits a dependence on the direction of the lines relative to the crystalline lattice and also on the direction of the laser polarization relative to the lines. In addition, electrical measurements of the modified graphene were performed. Different ion fluences were used in order to obtain a completely insulating defect line in graphene, which was determined experimentally by means of charge injection and electric force microscopy measurements. These studies demonstrate that a Ga+ ion column combined with Raman spectroscopy is a powerful technique to produce and understand well-defined periodic arrays of defects in graphene, opening possibilities for better control of nanocarbon devices.

Angiotensin II-induced JNK activation is mediated by NAD(P)H oxidase in isolated rat pancreatic islets.

Angiotensin II (AII), the active component of the renin angiotensin system (RAS), plays a vital role in the regulation of physiological processes of the cardiovascular system, but also has autocrine and paracrine actions in various tissues and organs. Many studies have shown the existence of RAS in the pancreas of humans and rodents. The aim of this study was to evaluate potential signaling pathways mediated by AII in isolated pancreatic islets of rats. Phosphorylation of MAPKs (ERK1/2, JNK and p38MAPK), and the interaction between proteins JAK/STAT were evaluated. AII increased JAK2/STAT1 (42%) and JAK2/STAT3 (100%) interaction without altering the total content of JAK2. Analyzing the activation of MAPKs (ERK1/2, JNK and p38MAPK) in isolated pancreatic islets from rats we observed that AII rapidly (3 min) promoted a significant increase in the phosphorylation degree of these proteins after incubation with the hormone. Curiously JNK protein phosphorylation was inhibited by DPI, suggesting the involvement of NAD(P)H oxidase in the activation of protein.

Thermal enhancement of chemical doping in graphene: a Raman spectroscopy study.

The Raman spectrum of monolayer graphene deposited on the top of a silicon oxide/silicon substrate was investigated as a function of temperature up to 515 K. An anomalous temperature dependence of the Raman features was observed, including an important frequency upshift for the Raman G band at room temperature, after the heating process. On the other hand, the frequency of the Raman G(') band is only slightly affected by the thermal treatment. We discuss our experimental results in terms of doping and strain effects associated with the interaction of graphene with the substrate and with the presence of water in the sample. We conclude that the doping effect gives the most important contribution to the spectral changes observed after the thermal cycle.

Observation of distinct electron-phonon couplings in gated bilayer graphene.

A Raman study of a back gated bilayer graphene sample is presented. The changes in the Fermi level induced by charge transfer splits the Raman G band, hardening its higher component and softening the lower one. These two components are associated with the symmetric (S) and antisymmetric vibration (AS) of the atoms in the two layers, the later one becoming Raman active due to inversion symmetry breaking. The phonon hardening and softening are explained by considering the selective coupling of the S and AS phonons with interband and intraband electron-hole pairs.

Transcriptome characterization of the dimorphic and pathogenic fungus Paracoccidioides brasiliensis by EST analysis.

Paracoccidioides brasiliensis is a pathogenic fungus that undergoes a temperature-dependent cell morphology change from mycelium (22 degrees C) to yeast (36 degrees C). It is assumed that this morphological transition correlates with the infection of the human host. Our goal was to identify genes expressed in the mycelium (M) and yeast (Y) forms by EST sequencing in order to generate a partial map of the fungus transcriptome. Individual EST sequences were clustered by the CAP3 program and annotated using Blastx similarity analysis and InterPro Scan. Three different databases, GenBank nr, COG (clusters of orthologous groups) and GO (gene ontology) were used for annotation. A total of 3,938 (Y = 1,654 and M = 2,274) ESTs were sequenced and clustered into 597 contigs and 1,563 singlets, making up a total of 2,160 genes, which possibly represent one-quarter of the complete gene repertoire in P. brasiliensis. From this total, 1,040 were successfully annotated and 894 could be classified in 18 functional COG categories as follows: cellular metabolism (44%); information storage and processing (25%); cellular processes-cell division, posttranslational modifications, among others (19%); and genes of unknown functions (12%). Computer analysis enabled us to identify some genes potentially involved in the dimorphic transition and drug resistance. Furthermore, computer subtraction analysis revealed several genes possibly expressed in stage-specific forms of P. brasiliensis. Further analysis of these genes may provide new insights into the pathology and differentiation of P. brasiliensis.

Pollen mother cells of Tradescantia clone 4430 and Tradescantia pallida var. purpurea are equally sensitive to the clastogenic effects of X-rays

The Tradescantia micronucleus test is a sensitive bioassay for mutagenesis that may be employed both under field and laboratory conditions. This test has been standardized mostly on the basis of the results obtained with clone 4430. However, this clone is not well adapted to tropical weather, frequently showing problems with growth and flowering. In addition, it is attacked by parasites and insects, a fact that limits its use in field studies aiming at the biomonitoring of air pollution. In the city of Säo Paulo, Tradescantia pallida (Rose) Hunt. var. purpurea Boom is widely distributed as an ornamental plant in gardens and along roadsides and streets, mostly because of its natural resistance and its easy propagation. In this report, we present dose-response curves indicating that the sensitivity of T. pallida and clone 4430 to X-radiation (1, 10, 25 and 50 cGy) is similar. The results confirm our previous suggestion that T. pallida represents a good alternative for in situ mutagenesis testing in tropical regions, especially biomonitoring studies in which the exposure conditions may not be fully controllable

Pollen mother cells of Tradescantia clone 4430 and Tradescantia pallida var. purpurea are equally sensitive to the clastogenic effects of X-rays.

The Tradescantia micronucleus test is a sensitive bioassay for mutagenesis that may be employed both under field and laboratory conditions. This test has been standardized mostly on the basis of the results obtained with clone 4430. However, this clone is not well adapted to tropical weather, frequently showing problems with growth and flowering. In addition, it is attacked by parasites and insects, a fact that limits its use in field studies aiming at the biomonitoring of air pollution. In the city of São Paulo, Tradescantia pallida (Rose) Hunt. var. purpurea Boom is widely distributed as an ornamental plant in gardens and along roadsides and streets, mostly because of its natural resistance and its easy propagation. In this report, we present dose-response curves indicating that the sensitivity of T. pallida and clone 4430 to X-radiation (1, 10, 25 and 50 cGy) is similar. The results confirm our previous suggestion that T. pallida represents a good alternative for in situ mutagenesis testing in tropical regions, especially biomonitoring studies in which the exposure conditions may not be fully controllable.

Exploring the clastogenic effects of air pollutants in São Paulo (Brazil) using the Tradescantia micronuclei assay.

This study was designed to determine the clastogenicity of particulate matter (aerodynamic diameter smaller than 10 microm) in the urban polluted air in the city of São Paulo. The Tradescantia-micronucleus (Trad-MCN) assay was used throughout this study to evaluate the clastogenicity of the extracts of the particulate matter. Tradescantia pallida (Rose) Hunt. cv. purpurea, an indigenous cultivar, was used in the Trad-MCN assay. The efficacy of this plant material for the Trad-MCN assay was validated with dose-response studies using formaldehyde and beta radiation. Dose-response curves were established with these known mutagens. The extracts of the PM10 particles at concentrations between 5 and 50 ppm induced a dose-related increase in MCN frequencies. The results indicate that T. pallida is equally sensitive to mutagens as the standard Tradescantia clone 4430 or 03 and the particulate matter in the urban air are clastogenic to the chromosomes of this plant. Inhalation of these particles by urban dwellers may affect their health by inducing similar genetic damage.