N-methyl bases of ethanolamine prevent apoptotic cell death induced by oxidative stress in cells of oligodendroglia origin

A major reason for brain tissue vulnerability to oxidative damage is the high content of polyunsaturated fatty acids (PUFAs). Oligodendroglia-like OLN 93 cells lack PUFAs and are relatively insensitive to oxidative stress. When grown in serum-free defined medium in the presence of 0.1 mM docosahexaenoic acid (DHA; 22:6 n-3) for 3 days, OLN 93 cells release in the medium 2.6-fold more thiobarbituric acid-reactive substances (TBARS) after a 30-min exposure to 0.1 mM H2O2 and 50 microM Fe2+. Release of TBARS was substantially decreased by approximately 20 and 30% on coincubation with either 1 mM N-monomethylethanolamine or N,N'-dimethylethanolamine (dEa), respectively. The protective effect of dEa was concentration- and time-dependent and was still visible after dEa removal, suggesting a long-lasting mechanism of protection. After 24 h following H2O2-induced stress, cell death monitored by cell sorting showed 16% of the cells in the sub-G1 area, indicative of apoptotic cell death. DHA-supplemented cultures showed 35% cell death, whereas cosupplements with dEa reduced cell death to 12%, indicating cell rescue. Although the exact mechanism for this protection is not known, the nature of the polar head group and the degree of unsaturation may determine the ultimate resistance of nerve cells to oxidative stress.     

Homogeneity of Trypanosoma evansi isolates from domestic and sylvatic mammals from the Pantanal of Mato Grosso

'Mal de Cadeiras' is a disease which causes great mortality in horses in the Pantanal Matogrossense region, Brazil. The agent of this disease is Trypanosoma evansi, a kinetoplastid flagellate which belongs to the Trypanosomatidae family, classified into the Salivarian section. Transmission occurs mechanically by haematophagous Diptera, mainly by Stomoxys sp. and Tabanus sp. and vampire bats. Outbreaks of Mal de Cadeiras in horses result in economic losses, thus limiting their use in cattle raising. Ten isolates of T. evansi recently derived from coati (Nasua nasua, Carnivora, Procyonidae), horses and dogs were compared, using schizodeme analyses from DNA digested by the restriction enzyme Hin fl. The results showed similar electrophoretic profiles for all isolates from wherever the host came. Homogeneity of isolates from domestic and sylvatic animals suggested two hypotheses: (1) the parasites circulated in only one transmission cycle;, and (2) independent cycles were not established in sufficient time to modify the molecular profiles of the isolates.     

State-dependent expression of pressure diuresis in conscious rats

In 1967, Guyton and Coleman modeled pressure diuresis as the underlying, essential, long-term mechanism that regulates arterial pressure when sodium intake changes. Other mechanisms that influence renal function interact with pressure diuresis to achieve sodium balance and determine the blood pressure. Increases in sodium intake suppress sodium conserving mechanisms and activate natriuretic mechanisms; decreases in sodium intake have the opposite effect. If the Guyton-Coleman model is correct, then pressure diuresis should be more readily detected in animals on a high-salt diet than in animals on a low-salt diet. We measured spontaneous changes in arterial pressure and urine flow in conscious rats fed low-salt (0. 4% NaCl) and high-salt (8.0% NaCl) chow. For 10 rats fed a high-salt diet, arterial pressure and urine flow were positively correlated in 19 of 32 (59%) trials. In 10 rats fed a low-salt diet, a positive correlation was observed in 10 of 33 (30%) trials. Chi-square analysis revealed that differences in Na+ content of the diet were significantly associated with the probability of a positive relationship between blood pressure and urine flow. These results support the hypothesis that the expression of pressure diuresis across time is dependent on the state of sodium balance.     

Biological detoxification of coffee husk by filamentous fungi using a solid state fermentation system

Studies were carried out on detoxification of coffee husk in solid state fermentation using three different strains of Rhizopus, Phanerochaete, and Aspergillus sp. Fungal strains were selected by their ability to grow on a coffee husk extract-agar medium. Using R. arrizus LPB-79, the best results on the degradation of caffeine (87%) and tannins (65%) were obtained with pH 6.0 and moisture 60% in 6 days. When P. chrysosporium BK was used, maximum degradation of caffeine and tannins were 70.8 and 45%, respectively, with coffee husk having 65% moisture and pH 5.5 in 14 days. The Aspergillus strain, isolated from the coffee husk, showed best biomass formation on coffee husk extract-agar medium. Optimization assays were conducted using factorial design, and surface response experiments with Aspergillus sp. The best detoxification rates achieved were 92% for caffeine and 65% for tannins. The results showed good prospects of using these fungal strains, in particular Aspergillus sp., for the detoxification of coffee husk.     

Viscoelastic dissipation in compact bone: implications for stress-induced fluid flow in bone

Viscoelastic properties of wet and dry human compact bone were studied in torsion and in bending for both the longitudinal and transverse directions at frequencies from 5 mHz to 5 kHz in bending to more than 50 kHz in torsion. Two series of tests were done for different longitudinal and transverse specimens from a human tibia. Wet bone exhibited a larger viscoelastic damping tan delta (phase between stress and strain sinusoids) than dry bone over a broad range of frequency. All the results had in common a relative minimum in tan delta over a frequency range, 1 to 100 Hz, which is predominantly contained in normal activities. This behavior is inconsistent with an optimal "design" for bone as a shock absorber. There was no definitive damping peak in the range of frequencies explored, which could be attributed to fluid flow in the porosity of bone.     

Ace/Fgf8 is required for forebrain commissure formation and patterning of the telencephalon

Fibroblast growth factors (Fgfs) form a large family of secreted signalling proteins that have a wide variety of roles during embryonic development. Within the central nervous system (CNS) Fgf8 is implicated in patterning neural tissue adjacent to the midbrain-hindbrain boundary. However, the roles of Fgfs in CNS tissue rostral to the midbrain are less clear. Here we examine the patterning of the forebrain in zebrafish embryos that lack functional Fgf8/Ace. We find that Ace is required for the development of midline structures in the forebrain. In the absence of Ace activity, midline cells fail to adopt their normal morphology and exhibit altered patterns of gene expression. This disruption to midline tissue leads to severe commissural axon pathway defects, including misprojections from the eye to ectopic ipsilateral and contralateral targets. Ace is also required for the differentiation of the basal telencephalon and several populations of putative telencephalic neurons but not for overall regional patterning of forebrain derivatives. Finally, we show that ace expression co-localises with anterior neural plate cells that have previously been shown to have forebrain patterning activity. Removal of these cells leads to a failure in induction of ace expression indicating that loss of Ace activity may contribute to the phenotypes observed when anterior neural plate cells are ablated. However, as ace mutant neural plate cells still retain at least some inductive activity, then other signals must also be produced by the anterior margin of the neural plate.     

The identification of tryptophan residues responsible for ATP-induced increase in intrinsic fluorescence of myosin subfragment 1

ATP binding to myosin subfragment 1 (S1) induces an increase in tryptophan fluorescence. Chymotryptic rabbit skeletal S1 has 5 tryptophan residues (Trp113, 131, 440, 510 and 595), and therefore the identification of tryptophan residues perturbed by ATP is quite complex. To solve this problem we resolved the complex fluorescence spectra into log-normal and decay-associated components, and carried out the structural analysis of the microenvironment of each tryptophan in S1. The decomposition of fluorescence spectra of S1 and S1-ATP complex revealed 3 components with maxima at ca. 318, 331 and 339-342 nm. The comparison of structural parameters of microenvironment of 5 tryptophan residues with the same parameters of single-tryptophan-containing proteins with well identified fluorescence properties applying statistical method of cluster analysis, enabled us to assign Trp595 to 318 nm, Trp440 to 331 nm, and Trp 13, 131 and 510 to 342 nm spectral components. ATP induced an almost equal increase in the intensities of the intermediate (331 nm) and long-wavelength (342 nm) components, and a small decrease in the short component (318 nm). The increase in the intermediate component fluorescence most likely results from an immobilization of some quenching groups (Met437, Met441 and/or Arg444) in the environment of Trp440. The increase in the intensity and a blue shift of the long component might be associated with conformational changes in the vicinity of Trp510. However, these conclusions can not be extended directly to the other types of myosins due to the diversity in the tryptophan content and their microenvironments.     

Phosphocholine as a pattern recognition ligand for CD36

We have previously shown that CD36 recognizes oxidation products of phospholipids on oxidized LDL (OxLDL) such as 1-palmitoyl-2-(5'-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC). The current study was designed to examine whether the phosphocholine (PC) headgroup in POVPC constitutes an obligatory binding target for CD36. To examine the contribution of PC in the binding of POVPC to CD36, we used well-defined synthetic oxidized phospholipids (OxPLs) cross-linked to BSA or to a hexapeptide. The OxPL adducts were then tested for their ability to bind to CD36-transfected cells and for their ability to inhibit OxLDL binding to CD36. Both POVPC-BSA and POVPC-peptide adducts were high-affinity ligands for CD36 and potent inhibitors of OxLDL binding. Enzymatic removal of the entire PC moiety of the POVPC-peptide, or of the choline headgroup alone, as well as substitution of the choline headgroup by ethanolamine abrogated the inhibitory activity of POVPC. Interestingly, PC by itself or cross-linked to BSA did not show any intrinsic competition activity. In conclusion, our data demonstrate that the PC headgroup of OxPL alone is sufficient for binding to CD36, but only if presented in the correct conformation as in OxPL of OxLDL or as in POVPC-peptide adducts.