Guanosine Neuroprotective Action in Hippocampal Slices Subjected to Oxygen and Glucose Deprivation Restores ATP Levels,Lactate Release and Glutamate Uptake Impairment: Involvement of Nitric Oxide

Neurochemical Research - Stroke is a major cause of disability and death worldwide. Oxygen and glucose deprivation (OGD) in brain tissue preparations can reproduce several pathological features...     

Host‐cell lipid rafts: a safe door for micro‐organisms?

The lipid raft hypothesis proposed that these microdomains are small (10–200 nM), highly dynamic and enriched in cholesterol, glycosphingolipids and signalling phospholipids, which compartmentalize cellular processes. These membrane regions play crucial roles in signal transduction, phagocytosis and secretion, as well as pathogen adhesion/interaction. Throughout evolution, many pathogens have developed mechanisms to escape from the host immune system, some of which are based on the host membrane microdomain machinery. Thus lipid rafts might be exploited by pathogens as signalling and entry platforms. In this review, we summarize the role of lipid rafts as players in the overall invasion process used by different pathogens to escape from the host immune system.     

Toxicokinetics and toxicological effects of single oral dose of fumonisin B1 containing Fusarium verticillioides culture material in weaned piglets

Toxicokinetics and the toxicological effects of culture material containing fumonisin B₁ (FB₁) were studied in male weaned piglets by clinical, pathological, biochemical and sphingolipid analyses. The animals received a single oral dose of 5 mg FB₁/kg of body weight, obtained from Fusarium verticillioides culture material. FB₁ was detected by HPLC in plasma collected at 1-h intervals up to 6 h and at 12-h intervals up to 96 h. FB₁ eliminated in feces and urine was quantified over a 96-h period and in liver samples collected 96 h post-intoxication. Blood samples were obtained at the beginning and end of the experiment to determine serum enzyme activity, total bilirubin, cholesterol, sphinganine (Sa), sphingosine (So) and the Sa/So ratio. FB₁ was detected in plasma between 30 min and 36 h after administration. The highest concentration of FB₁ was observed after 2 h, with a mean concentration of 282 μg/ml. Only 0.93% of the total FB₁ was detected in urine between 75 min and 41 h after administration, the highest mean concentration (561 μg/ml) was observed during the interval after 8 at 24 h. Approximately 76.5% of FB₁ was detected in feces eliminated between 8 and 84 h after administration, with the highest levels observed between 8 and 24 h. Considering the biochemical parameters, a significant increase only occurred in cholesterol, alkaline phosphatase and aspartate aminotransferase activities. In plasma and urine, the highest Sa and Sa/So ratios were obtained at 12 and 48 h, respectively.     

Isolation and Properties of Macronuclei from Tetrahymena thermophila1

A simple and efficient method is described for the isolation of macronuclei from Tetrahymena thermophila (7B). The steps involved are deciliation and removal of the mucocysts’ contents by dibucaine treatment, digitonin mediated lysis, differential centrifugations, and finally isopyenic sucrose density gradient centrifugation. Judging from the distribution of marker enzymes and electron microscopy, the macronuclei obtained were free of cytoplasmic and paniculate contamination and were highly active in endogenous RNA-synthesis (1.5 pmol UTP incorporation/ng DNA min at 30°C). The ratio of protein: RNA: DNA was 2.0:0.33:1.0 (weight) and each macronucleus contained an average of 17 pg DNA. The average yield of isolation was 50%.     

Geochemical Characteristics Related to the Gregite-Producing Multicellular Magnetotactic Prokaryote Candidatus Magnetoglobus multicellularis in a Hypersaline Lagoon

We studied the geochemical properties of sediment layers where the gregite-producing multicellular magnetotactic prokaryote Candidatus Magnetoglobus multicellularis exists. The ratio of iron and bioavailable sulfur concentrations regulates the population density of this microorganism. The population density can reach 8.5 × 10² cells/cm³ at an iron to sulfur ratio of 0.5. In iron- and sulfur-rich environments, microorganisms concentrated in the upper region of the oxic-anoxic zone, following an increasing nitrogen gradient with a lower isotopic ¹⁵N/¹⁴N ratio. Candidatus Magnetoglobus multicellularis prefers environmental conditions that favor the biomineralization of greigite, but in situations where the nutrient availability is low, it moves to more suitable sites.     

A sensitive method for the quantification of the mass of inositol phosphates using gas chromatography-mass spectrometry

A sensitive method to directly measure the mass of inositol phosphates from biologic samples is described. The procedure uses ammonium sulfate gradient elution anion exchange column chromatography to isolate inositol monophosphate, bisphosphate, trisphosphate, and tetrakisphosphate. The isolated fractions are dephosphorylated and subsequently desalted by a novel approach using solid barium hydroxide in a 1:1 stoichiometric ratio to the amount of ammonium sulfate present in the dephosphorylated sample. The myo-inositol derived from each inositol phosphate species was quantified by stable isotope dilution gas chromatography-mass spectrometry of the hexakis(trimethylsilyl) derivative using hexadeutero-myo-inositol as the internal standard. The applicability and sensitivity of this method are illustrated by measuring the mass of individual inositol phosphates in isolated adult canine cardiac myocytes.     

Duckein,an alkaloid from Aniba duckei

A re-investigation of the trunk wood of Aniba duckei Kosterm. (Lauraceae) revealed the presence of two new natural compounds, 2,6-dihydroxy-4-methoxyphenyl 3-pyridyl ketone (duckein) and 2,6,4′-trihydroxy-4-methoxybenzophenone.     

Hyperglycemia Differentially Affects Maternal and Fetal DNA Integrity and DNA Damage Response

Objective: Investigate the DNA damage and its cellular response in blood samples from both mother and the umbilical cord of pregnancies complicated by hyperglycemia. Methods: A total of 144 subjects were divided into 4 groups: normoglycemia (ND; 46 cases), mild gestational hyperglycemia (MGH; 30 cases), gestational diabetes mellitus (GDM; 45 cases) and type-2 diabetes mellitus (DM2; 23 cases). Peripheral blood mononuclear cell (PBMC) isolation and/or leukocytes from whole maternal and umbilical cord blood were obtained from all groups at delivery. Nuclear and mitochondrial DNA damage were measured by gene-specific quantitative PCR, and the expression of mRNA and proteins involved in the base excision repair (BER) pathway were assessed by real-time qPCR and Western blot, respectively. Apoptosis was measured in vitro experiments by caspase 3/7 activity and ATP levels. Results: GDM and DM2 groups were characterized by an increase in oxidative stress biomarkers, an increase in nuclear and mitochondrial DNA damage, and decreased expression of mRNA (APE1, POLβ and FEN1) and proteins (hOGG1, APE1) involved in BER. The levels of hyperglycemia were associated with the in vitro apoptosis pathway. Blood levels of DNA damage in umbilical cord were similar among the groups. Newborns of diabetic mothers had increased expression of BER mRNA (APE1, POLβ and FEN1) and proteins (hOGG1, APE1, POLβ and FEN1). A diabetes-like environment was unable to induce apoptosis in the umbilical cord blood cells. Conclusions: Our data show relevant asymmetry between maternal and fetal blood cell susceptibility to DNA damage and apoptosis induction. Maternal cells seem to be more predisposed to changes in an adverse glucose environment. This may be due to differential ability in upregulating multiple genes involved in the activation of DNA repair response, especially the BER mechanism. However if this study shows a more effective adaptive response by the fetal organism, it also calls for further studies to determine the limit of this response that definitely changes the fate of a fetus under these conditions of cellular stress.