Inhibition of energy-producing pathways of HepG2 cells by 3-bromopyruvate

3-BrPA (3-bromopyruvate) is an alkylating agent with anti-tumoral activity on hepatocellular carcinoma. This compound inhibits cellular ATP production owing to its action on glycolysis and oxidative phosphorylation; however, the specific metabolic steps and mechanisms of 3-BrPA action in human hepatocellular carcinomas, particularly its effects on mitochondrial energetics, are poorly understood. In the present study it was found that incubation of HepG2 cells with a low concentration of 3-BrPA for a short period (150 microM for 30 min) significantly affected both glycolysis and mitochondrial respiratory functions. The activity of mitochondrial hexokinase was not inhibited by 150 microM 3-BrPA, but this concentration caused more than 70% inhibition of GAPDH (glyceraldehyde-3-phosphate dehydrogenase) and 3-phosphoglycerate kinase activities. Additionally, 3-BrPA treatment significantly impaired lactate production by HepG2 cells, even when glucose was withdrawn from the incubation medium. Oxygen consumption of HepG2 cells supported by either pyruvate/malate or succinate was inhibited when cells were pre-incubated with 3-BrPA in glucose-free medium. On the other hand, when cells were pre-incubated in glucose-supplemented medium, oxygen consumption was affected only when succinate was used as the oxidizable substrate. An increase in oligomycin-independent respiration was observed in HepG2 cells treated with 3-BrPA only when incubated in glucose-supplemented medium, indicating that 3-BrPA induces mitochondrial proton leakage as well as blocking the electron transport system. The activity of succinate dehydrogenase was inhibited by 70% by 3-BrPA treatment. These results suggest that the combined action of 3-BrPA on succinate dehydrogenase and on glycolysis, inhibiting steps downstream of the phosphorylation of glucose, play an important role in HepG2 cell death.     

Nutrient addition experiments in Lago Jacaretinga,Central Amazon,Brazil: 2. The effect of humic and fulvic acids

Enrichment experiments consisting of additions of nutrients (nitrogen and phosphorus) and humic and fulvic acids were carried out using natural phytoplankton assemblages from Lago Jacaretinga, Central Amazon, Brazil. The addition of nutrients resulted in greatly stimulated primary production whereas addition of humic and fulvic acids had no effect. When both nutrients and humic and fulvic acids were added in combination, algal community response was identical to treatments in which only nutrients had been added. The result contrasts with previous phytoplankton culture studies in which the addition of humic material to the culture media increased production. Comparison of absorbance spectra indicated a severe reduction in the quantity and quality of light in Amazonian black waters relative to that in white waters.     

Human dendritic cells transduced with herpes simplex virus amplicons encoding human immunodeficiency virus type 1 (HIV-1) gp120 elicit adaptive immune responses from human cells engrafted into NOD/SCID mice and confer partial protection against HIV-1 challenge

Small-animal models are needed to test human immunodeficiency virus (HIV) vaccine efficacy following viral challenge. To this end, we examined HIV-1-specific immune responses following immunization of nonobese diabetic-severe combined immunodeficient mice that were repopulated with human peripheral blood lymphocytes (hu-PBL-NOD/SCID mice). Autologous dendritic cells (DC) were transduced ex vivo with replication-defective, helper virus-free, herpes simplex virus type 1 (HSV-1) amplicons that expressed HIV-1 gp120 and were then injected into the hu-PBL-NOD/SCID mice. This resulted in primary HIV-1-specific humoral and cellular immune responses. Serum samples from vaccinated animals contained human immunoglobulin G that reacted with HIV-1 Env proteins by enzyme-linked immunosorbent assay and neutralized the infectivity of HIV-1 LAI and ADA strains. T cells isolated from the mice responded to viral antigens by producing gamma interferon when analyzed by enzyme-linked immunospot assay. Importantly, exposure of the vaccinated animals to infectious HIV-1 demonstrated partial protection against infectious HIV-1 challenge. This was reflected by a reduction in HIV-1(ADA) and by protection of the engrafted human CD4(+) T lymphocytes against HIV-1(LAI)-induced cytotoxicity. These data demonstrate that transduction of DC by HSV amplicon vectors expressing HIV-1 gp120 induce virus-specific immune responses in hu-PBL-NOD/SCID mice. This mouse model may be a useful tool to evaluate human immune responses and protection against viral infection following vaccination.     

Superpredation patterns in four large European raptors

Predatory interactions among top predators, like superpredation or intraguild predation (IGP), can influence community structure. Diurnal raptors occupy high trophic levels in terrestrial food webs, and thus can regulate the presence of mesopredators. We studied superpredation (the killing and eating of another predator) in four large European raptors. We gathered 121 dietary studies, totalling 161,456 prey for the Goshawk Accipiter gentilis L., Golden Eagle Aquila chrysaetos L., Bonelli’s Eagle Aquila fasciata Vieillot, and Eagle Owl Bubo bubo L. Results showed that superpredation: (1) is a widespread interaction in large raptors, but it can vary according to the top predator species; (2) is not an important energetic resource for large raptors, but rather seems mostly related to diet diversification when the main prey decreases; (3) is spatially clustered reflecting habitat heterogeneity, but shows no temporal or large-scale spatial trends; and (4) it is associated with lower breeding success of the top predator species. These findings support the food stress hypothesis as the main driving force behind increases in superpredation and IGP in raptors, with the decrease in breeding performance as a side effect. Superpredation by large raptors deserves future research to understand its effects on mesopredators, because on one hand it might contribute to promote biodiversity, while on the other hand, it can sometimes represent an additional risk for small populations of endangered mesopredators.     

Environmental factors influence on chemical polymorphism of the essential oils of Lychnophora ericoides

Lychnophora ericoides is a Brazilian medicinal plant used in folk medicine as an anti-inflammatory and analgesic agent. The essential oils from leaves of two populations with and without scent, collected at 2-month intervals during an 1-year period, were analysed by GC-MS. The results were submitted to principal component and cluster analysis which allowed two groups of essential oils to be distinguished with respect to sampling site and scent: cluster I (Vianópolis site, with specimens exhibiting an aromatic scent) containing a high percentage of alpha-bisabolol (44.7-76.4%) and alpha-cadinol (10.9-23.5%), and cluster II (Cristalina site, with specimens without scent) characterised by a high content of (E)-nerolidol (31.3-47.1%) and ar-dihydro-turmerone (4.8-15.4%). The canonical discriminant analysis showed that using the data set of the seven sampling months and (E)-nerolidol and alpha-bisabolol as predictable variables, it was possible to distinguish between the samples harvested according to Cerrado seasons, dry winter (May-September) and humid summer (November-March). In addition, canonical correlation analysis between the soil sampling sites and the populations revealed a significant relationship between oil components and edaphic factors. Oxygenated sesquiterpenes and potential acidity, Al saturation, cationic exchange capacity, silt, and sand load as the first canonical variate were fairly strongly related to samples collected in Vianópolis site. On the other hand, monoterpenes and sesquiterpene hydrocarbons were strongly related to chemical balance in soils (organic matter, P and base saturation), which is related to samples at the Cristalina site. The chemovariation observed appears to be environmentally determined.     

Further insights on chromosomal pairing of autopolyploids: a triploid and tetraploids of rye

Chromosomal pairing of one triploid and three tetraploid plants of rye, Secale cereale, was analyzed by electron microscopy in surface-spread prophase I nuclei and compared with light microscopic observations of metaphase I cells. Prophase I is characterized by: (i) the weak alignment showed by the three or four unsynapsed or partially homologous synapsed axes; (ii) the low number ber of pairing partner switches (PPSs) displayed by both trivalents and quadrivalents; and (iii) the existence of complex multivalents in which up to 13 chromosomes in the triploid and 22 chromosomes in the tetraploids were involved. However, only few heterologous chromosomal associations were maintained at metaphase I. The results obtained are discussed under the assumptions of the random end pairing model with some modifications.     

Compatible Solutes in the Thermophilic Bacteria Rhodothermus marinus and "Thermus thermophilus"

(sup13)C nuclear magnetic resonance spectroscopy and (sup1)H nuclear magnetic resonance spectroscopy were used to identify and quantify the organic solutes of several strains of halophilic or halotolerant thermophilic bacteria. Two strains of Rhodothermus marinus and four strains of "Thermus thermophilus" grown in complex medium containing NaCl were examined. 2-O-Mannosylglycerate was a major compatible solute in all strains: the Thermus strains accumulated the (beta)-anomer only, whereas both anomers were found in R. marinus. 2-O-(beta)-mannosylglycerate and 2-O-(alpha)-mannosylglycerate were the major compatible solutes in R. marinus. The former was the predominant solute in cells grown in 2.0 and 4.0% NaCl-containing medium, while the latter was the predominant compatible solute at higher salinities. Glutamate, trehalose, and glucose were also present as minor components. The intracellular K(sup+) concentration, as determined by (sup39)K nuclear magnetic resonance spectroscopy, in R. marinus increased with salinity and was sufficient to balance the negative charges of the mannosylglycerate. In addition to 2-O-(beta)-mannosylglycerate, trehalose was a major compatible solute of "T. thermophilus." 2-O-(beta)-Mannosylglycerate was the main solute in medium containing 1.0 or 2.0% NaCl, while trehalose predominated in cells grown in medium supplemented with 3.0 or 4.0% NaCl. Glycine betaine, in lower concentrations, was also detected in two "T. thermophilus" strains. This is the first report of mannosylglycerate as a compatible solute in bacteria.     

The [(Cp)M(CO)(3) ] (M=Re, (99m) Tc) Building Block for Imaging Agents and Bioinorganic Probes: Perspectives and Limitations

Starting from asymmetric Thiele's acid derivatives, two different imaging probes [(99m) Tc(CO)(3) (CpR)] (R=potential targeting vector) are generated simultaneously in one-pot and from one substrate. This extends the previously introduced labeling strategy of metal-mediated retro-Diels?Alder reaction with HCp-R dimers. We demonstrate that chemically active functionalities such as hydroxamic acids are not following this labeling strategy. Adopting the principle of replacing phenyl rings by [Re(CO)(3) (Cp)] entities, potent histone deacetylase (HDAC)-inhibiting Re analogs of suberoylanlilide hydroxamic acid (SAHA; N-hydroxy-N'-phenyloctanediamide) were synthesized and characterized. Cytotoxic evaluation on different tumor cell lines revealed low IC(50) values [μM] for these compounds, comparable to their purely organic congeners.     

Evaluation of the anti-inflammatory and antinociceptive properties of p-cymene in mice

We attempted to identify the antinociceptive and anti-inflammatory actions of the monoterpene p-cymene. Firstly, behavioural screening was carried out to verify the influence of p-cymene [25, 50, and 100 mg/kg intraperitoneal (i.p.)] on the central nervous system (CNS) activity. The antinociceptive activity of p-cymene was evaluated by the acetic acid-induced writhing response, formalin, and hot-plate test, respectively. The leukocyte migration induced by injection of carrageenan was used to assess the anti-inflammatory activity. p-Cymene showed depressant activity on CNS after 4 h of treatment and also a possible action on the autonomous nervous system (ANS), mainly at the dose of 100 mg/kg (i.p.). It was found that p-cymene (50 and 100 mg/kg, i.p.) significantly (p < 0.05) reduced the writhing responses induced by acetic acid. p-Cymene also decreased the licking time in the first and second phase, respectively, of the formalin test. The results of the hot-plate test showed that all doses of p-cymene increased significantly the latency time of the response to the thermal stimulus in both licking and jumping parameters. In addition, there was a significantly (p < 0.05) decreased leukocyte migration at all doses of p-cymene. The experimental data demonstrate that p-cymene possesses antinociceptive and anti-inflammatory activities.