Chronic administration of EGb 761 modulates synaptic and mitochondrial plasticity in adult vitamin E-deficient rats.

A computer-assisted morphometric study has been carried out on synaptic junctions and synaptic mitochondria in the dentate gyrus supragranular layer of vitamin E-deficient rats undergone chronic administration of the extract EGb 761 from Ginkgo biloba leaves (100 mg/kg body weight, daily, from 4 to 7 months of age). Control animals were fed with the vitamin E-deficient diet from 1 to 7 months of age. Numeric density (Nv), surface density (Sv) and average size of the synaptic junctions (S), mitochondrial numeric density (Nvm), volume density (Vv) and average volume (V) were the measured parameters. In EGb 761-treated animals, Nv was significantly increased and S significantly decreased, while Sv was unchanged. EGb 761 administration resulted in an increased percentage of synapses of smaller size. In EGb 761-treated rats, Nvm significantly increased and V significantly decreased, while no significant difference of Vv was found. The population of synaptic mitochondria in EGb 761 -treated animals was composed of a higher number of smaller organelles. The measured parameters report on the structural dynamics of synapses and mitochondria, thus our findings support that EGb 761 administration is able to improve the physiological adaptive capacities of the investigated structures by a positive modulation of their morphofunctional features.     

Hyperspectral Remote Sensing of Canopy Biodiversity in Hawaiian Lowland Rainforests

Mapping biological diversity is a high priority for conservation research, management and policy development, but few studies have provided diversity data at high spatial resolution from remote sensing. We used airborne imaging spectroscopy to map woody vascular plant species richness in lowland tropical forest ecosystems in Hawai’i. Hyperspectral signatures spanning the 400–2,500 nm wavelength range acquired by the NASA Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) were analyzed at 17 forest sites with species richness values ranging from 1 to 17 species per 0.1–0.3 ha. Spatial variation (range) in the shape of the AVIRIS spectra (derivative reflectance) in wavelength regions associated with upper-canopy pigments, water, and nitrogen content were well correlated with species richness across field sites. An analysis of leaf chlorophyll, water, and nitrogen content within and across species suggested that increasing spectral diversity was linked to increasing species richness by way of increasing biochemical diversity. A linear regression analysis showed that species richness was predicted by a combination of four biochemically-distinct wavelength observations centered at 530, 720, 1,201, and 1,523 nm (r ² = 0.85, p < 0.01). This relationship was used to map species richness at approximately 0.1 ha resolution in lowland forest reserves throughout the study region. Future remote sensing studies of biodiversity will benefit from explicitly connecting chemical and physical properties of the organisms to remotely sensed data.     

Distinctive functional features in prokaryotic and eukaryotic Cu,Zn superoxide dismutases

Bacterial and eukaryotic Cu,Zn superoxide dismutases show remarkable differences in the active site region and in their quaternary structure organization. We report here a functional comparison between four Cu,Zn superoxide dismutases from Gram-negative bacteria and the eukaryotic bovine enzyme. Our data indicate that bacterial dimeric variants are characterized by catalytic rates higher than that of the bovine enzyme, probably due to the solvent accessibility of their active site. Prokaryotic Cu,Zn superoxide dismutases also show higher resistance to hydrogen peroxide inactivation and lower HCO3- -dependent peroxidative activity. Moreover, unlike the eukaryotic enzyme, all bacterial variants are susceptible to inactivation by chelating agents and show variable sensitivity to proteolytic attack, with the E. coli monomeric enzyme showing higher rates of inactivation by EDTA and proteinase K. We suggest that differences between individual bacterial variants could be due to the influence of modifications at the dimer interface on the enzyme conformational flexibility.     

Self-protection of individual CD4+ T cells against R5 HIV-1 infection by the synthesis of anti-viral CCR5 ligands

It is well established that paracrine secretion of anti-viral CCR5 ligands by CD8+ and CD4+ T cells can block the infection of activated CD4+ T cells by R5 and dual-tropic isolates of HIV-1. By contrast, because CD4+ T cells can be infected by HIV-1 and at least some subsets secrete anti-viral CCR5 ligands, it is possible that these ligands protect against HIV-1 via autocrine as well as paracrine pathways. Here we use a model primary CD4+ T cell response in vitro to show that individual CD4+ T cells that secrete anti-viral CCR5 ligands are 'self-protected' against infection with R5 but not X4 strains of HIV-1. This protection is selective for CD4+ T cells that secrete anti-viral CCR5 ligands in that activated CD4+ T cells in the same cultures remain infectable with R5 HIV-1. These data are most consistent with an autocrine pathway of protection in this system and indicate a previously unappreciated selective pressure on the emergence of viral variants and CD4+ T cell phenotypes during HIV-1 infection.     

Apolipoprotein [a] genotype influences isoform dominance pattern differently in African Americans and Caucasians

Plasma lipoprotein [a] (Lp[a]) concentrations are inversely associated with, and largely determined by, apolipoprotein [a] (apo[a]) gene size, a highly polymorphic trait. We studied if, within an individual, the smaller apo[a] isoform always dominated, whether there was interaction between the two alleles, and whether these features differed between Caucasians and African Americans. We determined apo[a] gene sizes, apo[a] protein sizes and relative amounts, and plasma Lp[a] levels in 430 individuals (263 Caucasians and 167 African Americans). Of the 397 heterozygotes with at least one detectable apo[a] isoform (238 Caucasians and 159 African Americans), the larger allele dominated in 28% of Caucasians and 23% of African Americans, while the smaller allele dominated in 56% of Caucasians and 45% of African Americans. In Caucasians, dominance of the smaller allele increased with Lp[a] levels, from 44% at Lp[a] < or = 30 nM to 81% at Lp[a] >100 nM (P < 0.0001). Dominance by the smaller allele increased with increasing size of the larger allele in both groups but with the smaller allele only in African Americans. There was no interaction between apo[a] alleles within genotypes; one apo[a] isoform level was not associated with the other isoform level, and isoform levels were not affected by the difference in size. More of the dominance pattern was explained by Lp[a] level and apo[a] genotype in African Americans than in Caucasians (29% vs. 13%). Thus, genotype influences isoform-specific Lp[a] levels and dominance patterns differently in African Americans and in Caucasians.     

Ferritin from the spleen of the Antarctic teleost Trematomus bernacchii is an M-type homopolymer.

Ferritin from the spleen of the Antarctic teleost Trematomus bernacchii is composed of a single subunit that contains both the ferroxidase center residues, typical of mammalian H chains, and the carboxylate residues forming the micelle nucleation site, typical of mammalian L chains. Comparison of the amino-acid sequence with those available from lower vertebrates indicates that T. bernacchii ferritin can be classified as an M-type homopolymer. Interestingly, the T. bernacchii ferritin chain shows 85.7% identity with a cold-inducible ferritin chain of the rainbow trout Salmo gairdneri. The structural and functional properties indicate that cold acclimation and functional adaptation to low temperatures are achieved without significant modification of the protein stability. In fact, the stability of T. bernacchii ferritin to denaturation induced by acid or temperature closely resembles that of mesophilic mammalian ferritins. Moreover iron is taken up efficiently and the activation energy of the reaction is 74.9 kJ.mol(-1), a value slightly lower than that measured for the human recombinant H ferritin (80.8 kJ.mol(-1)).     

Fine mapping of the Autosomal Dominant Split Hand/Split Foot Locus on Chromosome 7, Band q21.3-q22.1

Split hand/split foot (SHFD) is a human developmental defect characterized by missing digits, fusion of remaining digits, and a deep median cleft in the hands and feet. Cytogenetic studies of deletions and translocations associated with this disorder have indicated that an autosomal dominant split hand/split foot locus (gene SHFD1) maps to 7q21-q22. To characterize the SHFD1 locus, somatic cell hybrid lines were constructed from cytogenetically abnormal individuals with SHFD. Molecular analysis resulted in the localization of 93 DNA markers to one of 10 intervals surrounding the SHFD1 locus. The translocation breakpoints in four SHFD patients were encompassed by the smallest region of overlap among the SHFD-associated deletions. The order of DNA markers in the SHFD1 critical region has been defined as PON–D7S812–SHFD1–D7S811–ASNS. One DNA marker, D7S811, detected altered restriction enzyme fragments in three patients with translocations when examined by pulsed-field gel electro-phoresis (PFGE). These data map SHFD1, a gene that is crucial for human limb differentiation, to a small interval in the q21.3-q22.1 region of human chromosome 7.     

Oxidative damage of the gastric mucosa in Helicobacter pylori positive chronic atrophic and nonatrophic gastritis, before and after eradication

Background. Helicobacter pylori is the main cause of gastritis and a primary carcinogen. The aim of this study was to assess oxidative damage in mucosal compartments of gastric mucosa in H. pylori positive and negative atrophic and nonatrophic gastritis. Materials and methods. Five groups of 10 patients each were identified according to H. pylori positive or negative chronic atrophic (Hp‐CAG and CAG, respectively) and nonatrophic gastritis (Hp‐CG and CG, respectively), and H. pylori negative normal mucosa (controls). Oxidative damage was evaluated by nitrotyrosine immunohistochemistry in the whole mucosa and in each compartment at baseline and at 2 and 12 months after eradication. Types of intestinal metaplasia were classified by histochemistry. Results. Total nitrotyrosine levels appeared significantly higher in H. pylori positive than in negative patients, and in Hp‐CAG than in Hp‐CG (p < .001); no differences were found between H. pylori negative gastritis and normal mucosa. Nitrotyrosine were found in foveolae and intestinal metaplasia only in Hp‐CAG. At 12 months after H. pylori eradication, total nitrotyrosine levels showed a trend toward a decrease in Hp‐CG and decreased significantly in Hp‐CAG (p = .002), disappearing from the foveolae (p = .002), but remaining unchanged in intestinal metaplasia. Type I and II of intestinal metaplasia were present with the same prevalence in Hp‐CAG and CAG, and did not change after H. pylori eradication. Conclusions. Oxidative damage of the gastric mucosa increases from Hp‐CG to Hp‐CAG, involving the foveolae and intestinal metaplasia. H. pylori eradication induces a complete healing of foveolae but not of intestinal metaplasia, reducing the overall oxidative damage in the mucosa.     

The phosphoinositide 3-kinase/AKT1 pathway involvement in drug and all-trans-retinoic acid resistance of leukemia cells

Disruption of the apoptotic pathways may account for resistance to chemotherapy and treatment failures in human neoplastic disease. To further evaluate this issue, we isolated a HL-60 cell clone highly resistant to several drugs inducing apoptosis and to the differentiating chemical all-trans-retinoic acid (ATRA). The resistant clone displayed an activated phosphoinositide 3-kinase (PI3K)/AKT1 pathway, with levels of phosphatidylinositol (3,4,5) trisphosphate higher than the parental cells and increased levels of both Thr 308 and Ser 473 phosphorylated AKT1. In vitro AKT1 activity was elevated in resistant cells, whereas treatment of the resistant cell clone with two inhibitors of PI3K, wortmannin or Ly294002, strongly reduced phosphatidylinositol (3,4,5) trisphosphate levels and AKT1 activity. The inhibitors reversed resistance to drugs. Resistant cells overexpressing either dominant negative PI3K or dominant negative AKT1 became sensitive to drugs and ATRA. Conversely, if parental HL-60 cells were forced to overexpress an activated AKT1, they became resistant to apoptotic inducers and ATRA. There was a tight relationship between the activation of the PI3K/AKT1 axis and the expression of c-IAP1 and c-IAP2 proteins. Activation of the PI3K/AKT1 axis in resistant cells was dependent on enhanced tyrosine phosphorylation of the p85 regulatory subunit of PI3K, conceivably due to an autocrine insulin-like growth factor-I production. Our findings suggest that an up-regulation of the PI3K/AKT1 pathway might be one of the survival mechanisms responsible for the onset of resistance to chemotherapeutic and differentiating therapy in patients with acute leukemia.