Benthic macroinfaunal assemblages associated with Amazonian saltmarshes

The composition and abundance of the poorly known benthic macroinfauna associated with northern Brazilian saltmarshes, were described from eight sites (between 0°42′2.5″S, 47°52′44.1″W and 0°50′17.3″S, 46°36′13.3″W) along the Pará coast, Brazil. Sampling was carried out in November of 2007. Univariate and multivariate analyses were used to test for differences in sediment, vegetation and macroinfaunal variables among sites. No vertical zonation of the macroinfauna was detected. Macroinfaunal structure differed greatly among sites with different sediment and vegetation characteristics. Number of individuals and taxa were low in sites with sandy sediments and short, sparse vegetation and high in those with silty sediments with high organic matter and water contents, and tall, dense vegetation. Increasing number of individuals and taxa were associated with a geographical gradient in pore water salinity, which increases from west to east, coinciding with patterns of rainfall described for the Pará coast.     

Trypanosoma evansi: Activities of adenine nucleotide degradation enzymes in cerebral cortex of infected rats

This study aimed to evaluate the activities of the ectoenzymes NTPDase and 5′-nucleotidase in synaptosomes from cerebral cortex of rats experimentally infected with Trypanosoma evansi. The animals were divided in four groups (n = 10) according to the time and degree of parasitemia (groups A, B, C and D). The animals from group A were euthanized on day 3 (low parasitemia), group B on day 5 (high parasitemia) and group C on day 15 (low parasitemia). Group D consisted of healthy rats (not-infected, n = 15) and were divided in three periods (n = 5) in order to compare with the infected groups. After euthanasia, cerebral cortex was removed for the preparation of synaptosomes and enzymatic assays. Group A showed no changes in enzymatic activities compared with control. The hydrolysis of ATP, ADP and AMP by the enzymes NTPDase and 5′-nucleotidase were increased (P < 0.05) in group B (38%, 140% and 61%, respectively) when compared with control. In the group C it was observed a decreased (22%) hydrolysis of ATP when compared with control group. The activities of NTPDase and 5′-nucleotidase in synaptosomes alters the acute phase of the disease when the number of circulating parasites is high, thus the change observed is probably due to the parasitemia.     

Differential responses of antioxidant enzymes in pioneer and late-successional tropical tree species grown under sun and shade conditions

To investigate the ability of pioneer and late-successional species to adapt to a strong light environment in a reforestation area, we examined the activities of antioxidant enzymes in relation to photosystem II, chlorophyll a fluorescence and photosynthetic pigment concentration for eight tropical tree species grown under 100% (sun) and 10% (shade) sunlight irradiation. The pioneer (early-succession) species (PS) were Cecropia pachystachya, Croton urucurana, Croton floribundus and Schinus terebinthifolius. The non-pioneer (late succession) species (LS) were Hymenaea courbaril L. var. stilbocarpa, Esenbeckia leiocarpa, Cariniana legalis and Tabebuia roseo-alba. We observed a greater decline in the ratio of variable to maximum chlorophyll a fluorescence (F_v/F_m) under full sunlight irradiation in the late-successional species than in the pioneer species. The LS species most sensitive to high irradiance were C. legalis and H. courbaril. In LS species, chlorophyll a, chlorophyll b and total chlorophyll concentrations were higher in the shade-grown plants than in plants that developed under full sunlight, but in the PS species C. floribundus and C. pachystachya, we did not observe significant changes in chlorophyll content when grown in the two contrasting environments. The carotenoids/total chlorophyll ratio increased significantly when plants developed under high-sunlight irradiation, but this response was not observed in the PS species S.terebinthifolius and C. pachystachya. The improved performance of the pioneer species in high sunlight was accompanied by an increase in superoxide dismutase (SOD, EC 1.15.1.1) activity, though no light-dependent increase in the activity of ascorbate peroxidase (APX, EC 1.11.1.11) was observed. The activity of catalase (CAT, EC 1.11.1.6) was reduced by high irradiation in both pioneer and late-successional species. Our results show that pioneer species perform better under high-sunlight irradiation than late-successional species, as indicated by increased SOD activity and a higher F_v/F_m ratio. C. legalis was the LS species most susceptible to photoinhibition under full sunlight conditions. These results suggest that pioneer plants have more potential tolerance to photo-oxidative damage than late-successional species associated with the higher SOD activity found in pioneer species. Reduced photoinhibition in pioneer species probably results from their higher photosynthetic capacities, as has been observed in a previous survey carried out by our group.     

New bisphosphorothioates and bisphosphoroamidates: synthesis, molecular modeling and determination of insecticide and toxicological profile

A series of new compounds, N,N'-bis(dialkylphosphoryl)diamines and S,S'-bis(dialkylphosphoryl)-1,3-propanedithiols were prepared by a Todd-Atherton like reaction of dialkylphosphites with symmetrical diamines and 1,3-propanedithiols in a biphasic system [F.R. Athertoon, H.T. Howard, A.R. Todd, J. Chem. Soc. (1948) 1106-1111; F.R. Athertoon, H.T. Openshaw, A.R. Todd, J. Chem. Soc. (1945) 660-663]. The structures were characterized by IR, 1H NMR, 13C NMR and mass spectrometry. Compounds with butoxy, isobutoxy and isopropoxy groups linked in the phosphorus atom showed the lowest LD50 values when tested against Musca domestica and Stomoxys calcitrans. The pharmacological and toxicological evaluation of N,N'-bis(diisobutylphosphoryl)-1,3-propylenediamine and S,S'-bis(diisobutylphosphoryl)-1,3-propanedithiol, which were very active against M. domestica and S. calcitrans, demonstrated that these compounds present no toxicological effects against mice in a concentration of 200mg/kg. An explanation for the observed activity profile is presented based on results obtained in a molecular modeling study with insect and mammalian acetylcholinesterase models.     

Stem cells from umbilical cord blood differentiate into myotubes and express dystrophin in vitro only after exposure to in vivo muscle environment

BACKGROUND INFORMATION: Duchenne muscular dystrophy is a disease characterized by progressive and irreversible muscle degeneration for which there is no therapy. HUCB (human umbilical cord blood) has been considered as an important source of haematopoietic and mesenchymal stem cells, each having been shown to differentiate into distinct cell types. However, it remains unclear if these cells are able to differentiate into muscle cells. RESULTS: We have showed that stem cells from HUCB did not differentiate into myotubes or express dystrophin when cultured in muscle-conditioned medium or with human muscle cells. However, delivery of GFP (green fluorescent protein)-transduced mononucleated cells from HUCB, which comprises both haematopoietic and mesenchymal populations, into quadriceps muscle of mdx (mouse dystrophy X-chromosome linked) mice resulted in the expression of human myogenic markers. After recovery of these cells from mdx muscle and in vitro cultivation, they were able to fuse and form GFP-positive myotubes that expressed dystrophin. CONCLUSIONS: These results indicate that chemical factors and cell-to-cell contact provided by in vitro conditions were not enough to trigger the differentiation of stem cells into muscle cells. Nevertheless, we showed that the HUCB-derived stem cells were capable of acquiring a muscle phenotype after exposure to an in vivo muscle environment, which was required to activate the differentiation programme.     

Bioactive phenolic compounds from aerial parts of Plinia glomerata

The present work describes the antinociceptive properties and chemical composition of the aerial parts of Plinia glomerata (Myrtaceae). Both of the extracts evaluated, acetonic and methanolic, showed potent antinociceptive action, when analyzed against acetic acid-induced abdominal constrictions in mice, with calculated ID50 (mg/kg, i. p.) values of 24.8 and 3.3, respectively. Through usual chromatographic techniques with an acetonic extract, the following compounds were obtained: 3,4,3'-trimethoxy flavellagic acid (1), 3,4,3'-trimethoxy flavellagic acid 4'-O-glucoside (3) and quercitrin (4), which were identified based on spectroscopic data. Compounds 1 (ID50 = 3.9 mg/kg, i. p., or 10.8 micromol/kg) and 3 (ID50 = 1.3 mg/kg or 2.5 micromol/kg) were notably more active than some well-known analgesic drugs used here for comparison.     

Mesenchymal stem cells differentiate into keratinocytes and express epidermal kallikreins: Towards an in vitro model of human epidermis

Epidermal differentiation is a complex process in which keratinocytes go through morphological and biochemical changes in approximately 15 to 30 days. Abnormal keratinocyte differentiation is involved in the pathophysiology of several skin diseases. In this scenario, mesenchymal stem cells (MSCs) emerge as a promising approach to study skin biology in both normal and pathological conditions. Herein, we have studied the differentiation of MSC from umbilical cord into keratinocytes. MSC were cultured in Dulbecco's modified Eagle's medium (DMEM) (proliferation medium) and, after characterization, differentiation was induced by culturing cells in a defined keratinocyte serum-free medium (KSFM) supplemented with epidermal growth factor (EGF) and calcium chloride ions. Cells cultivated in DMEM were used as control. Cultures were evaluated from day 1 to 23, based on the cell morphology, the expression of p63, involucrin and cytokeratins (KRTs) KRT5, KRT10 and KRT14, by quantitative polymerase chain reaction, Western blot analysis or immunofluorescence, and by the detection of epidermal kallikreins activity. In cells grown in keratinocyte serum-free medium with EGF and 1.8 mM calcium, KRT5 and KRT14 expression was shown at the first day, followed by the expression of p63 at the seventh day. KRT10 expression was detected from day seventh while involucrin was observed after this period. Data showed higher kallikrein (KLK) activity in KSFM-cultured cells from day 11th in comparison to control. These data indicate that MSC differentiated into keratinocytes similarly to that occurs in the human epidermis. KLK activity detection appears to be a good methodology for the monitoring the differentiation of MSC into the keratinocyte lineage, providing useful tools for the better understanding of the skin biology.     

Cellulolytic enzyme production from agricultural residues for biofuel purpose on circular economy approach

This study evaluated the production of cellulolytic enzymes from different agricultural residues. The crude enzyme extract produced was characterized and applied for saccharification of some agricultural residues. Maximum cellulolytic activities were obtained using soybean hulls. All enzymatic activities were highly stable at 40 °C at a pH range of 4.5–5.5. For stability at low temperatures, the enzyme extract was stored at freezing temperature and cooling for about 290 days without major loss of activity. The K_m values found for total cellulase (FPase), endoglucanase (CMCase), and xylanase were 19.73 mg ml⁻¹, 0.65 mg ml⁻¹, and 22.64 mg ml⁻¹, respectively, and V_max values were 0.82 mol min⁻¹ mg⁻¹, 0.62 mol min⁻¹ mg⁻¹, and 104.17 mol min⁻¹ mg⁻¹ to cellulose, carboxymethyl cellulose, and xylan, respectively. In the saccharification tests, the total amount of total reducing sugars (TRS) released from 1 g of soybean hulls catalyzed by the enzymes present in the crude enzyme extract was 0.16 g g⁻¹ dry substrate.

     

Scanning X‐ray microdiffraction of decellularized pericardium tissue at increasing glucose concentration

Blood glucose supplies energy to cells and is critical for the human brain. Glycation of collagen, the nonenzymatic formation of glucose‐bridges, relates to diseases of aging populations and diabetics. This chemical reaction, together with its biomechanical effects, has been well studied employing animal models. However, the direct impact of glycation on collagen nano‐structure is largely overlooked, and there is a lack of ex vivo model systems. Here, we present the impact of glucose on collagen nanostructure in a model system based on abundantly available connective tissue of farm animals. By combining ex vivo small and wide‐angle X‐ray scattering (SAXS/WAXS) imaging, we characterize intra‐ and inter‐molecular parameters of collagen in decellularized bovine pericardium with picometer precision. We observe three distinct regimes according to glucose concentration. Such a study opens new avenues for inspecting the effects of diabetes mellitus on connective tissues and the influence of therapies on the resulting secondary disorders.      

Nosocomial Bloodstream Candida Infections in a Tertiary-Care Hospital in South Brazil: A 4-Year Survey

The aims of this study were to evaluate the epidemiology of nosocomial candidemia in a tertiary hospital in South Brazil and the in vitro antifungal susceptibility of isolates. Blood strains from 108 patients were identified by PCR-based method. Some 30.5 % of candidemia were caused by Candida tropicalis, 28.7 % were due to Candida albicans, 24.1 % with Candida parapsilosis sensu stricto, 8.3 % with Candida glabrata sensu lato, 1.8 % involved Candida krusei and 6.6 % with other species. Candidemia was more common in intensive care unit settings (66 %). In vitro susceptibility to antifungal drugs was determined by a microdilution method; and new species-specific clinical breakpoints for fluconazole and voriconazole were applied. Overall susceptibility rates were 100 % for itraconazole, 91 % for fluconazole, 98 % for voriconazole and 99 % for amphotericin B. Fluconazole resistance was mostly among C. parapsilosis sensu stricto isolates (26.9 %). Most of the findings reported here agreed with epidemiological features common to other tertiary hospitals in Brazil; but also revealed some peculiarities, such as a high frequency of C. tropicalis associated with candidemia. Besides, high rate of fluconazole resistance among C. parapsilosis stricto sensu isolates was obtained when applying the new species-specific clinical breakpoints.