Complement-dependent cellular cytotoxicity due to alternative pathway C3 activation by the target cell membrane

The cytotoxic activity of human blood lymphocytes toward Raji cells was strongly elevated when human serum (HS) was included in the cytotoxicity assay. This phenomenon also occurred when the effector cells were activated by interferon (IFN). Hypogammaglobulinemic serum (HyS) and heat-inactivated serum could also augment cytotoxicity, but C3-depleted serum was inefficient. IFN treatment of Raji cells decreased their sensitivity to lysis and this effect was counteracted by addition of HS to the system. It is likely that C3 activation by, and deposition on, Raji cells when used as targets for cytotoxicity facilitate their recognition and lysis by lymphocytes. These events may represent one mechanism operating in the natural killing phenomenon.     

Dopamine Receptor Stimulation Decreases Cytosolic γ Protein Kinase C Immunoreactivity in Rat Hippocampal Slices: Evidence for Increased Ca2+-Dependent Proteolysis

Abstract: The effect of dopamine (DA) receptor stimulation on the distribution of γ protein kinase C (γPKC) in hippocampal slices was assessed. Nanomolar concentrations of DA decreased cytosolic γPKC (56%) without altering membrane γPKC levels, resulting in decreased total γPKC immunoreactivity. The maximal decrease in cytosolic γPKC occurred at 20 min of incubation and was significantly blocked by the D₁ DA antagonist SCH 23390 (10⁻⁶ M ) but not by the D₂ antagonist sulpiride (10⁻⁵ M ). The D₁ agonists SKF 38393 and A 77636 mimicked the effect of DA with similar responses produced at 10 µ M and 1 n M , respectively. The D₂ agonist quinpirole had no effect on γPKC immunoreactivity, thus indicating that this dopaminergic response is mediated through a D₁-like receptor. DA had no effect on α, δ, or ζPKC isozyme immunoreactivity in the same hippocampal preparations. The DA-induced decrease in cytosolic γPKC immunoreactivity was blocked by the Ca²⁺-dependent protease inhibitor N -acetyl-Leu-Leu-norleucinal (100 µ M ) and by the inorganic Ca²⁺ channel blocker Co²⁺. The data suggest that DA stimulates a D₁-like DA receptor, which increases the influx of Ca²⁺ and activates the Ca²⁺-dependent proteolysis of γPKC.     

Severe hepatopathy in geese and broilers associated with ochratoxin in their feed

The feeding of a shipment of imported corn was associated with a severe reduction in growth and increased mortality in geese, and increased mortality in broilers. Pathological examinations revealed hepatopathy, visceral gout and mild nephropathy in geese, and in broilers an hepatopathy, which was often severe, and ascites. Samples of feed from affected geese farms were examined for up to 24 mycotoxins, and ochratoxin was found in 6 of 15 samples at levels up to 930 ng/g. The syndrome was experimentally reproduced by feeding geese and broilers suspect feeds with the natural ochratoxin contamination. It is believed that another, unidentified, mycotoxin was the major cause of the hepatotoxicity, and that ochratoxin served in this case as an indicator of a multi-mycotoxin involvement. This revised version was published online in June 2006 with corrections to the Cover Date.     

Characterization of the Phosphoinositide-Linked Dopamine Receptor in a Mouse Hippocampal-Neuroblastoma Hybrid Cell Line

Abstract: Previous studies have established that dopamine (DA) can stimulate phosphoinositide (PI) metabolism in the CNS and in the periphery. The present study summarizes our attempt to find a cell line that expresses this dopaminergic system. We describe that the stable clonal HN33.11 cell line, established by fusion of mouse hippocampal cells with neuroblastoma cells (N18TG2) that originate from A/J mouse, natively expresses the D₁ DA receptor system that couples to PI hydrolysis. In this cell line, 500 µM DA or SKF38393 produced 43 and 75% increases in inositol phosphate (IP) accumulations, respectively. In contrast, noradrenaline or 5-hydroxytryptamine did not affect IP accumulations. The formation of IP that was stimulated by DA or SKF38393 was selectively blocked by the D₁ DA receptor antagonist SCH23390 with IC₅₀ values of 13 and 16 µM. This response was not mediated by the D_1A DA receptor and was cyclic AMP-independent, as HN33.11 cells did not express this receptor, and DA or SKF38393 was unable to stimulate the formation of cyclic AMP. In Ca²⁺-free/100 µM EGTA medium, basal IP level was reduced by 31.5%, but SKF38393-stimulated PI hydrolysis was not affected. SKF38393-stimulated IP accumulation was also not affected by pertussis toxin (PTX) treatment (200 ng/ml), suggesting that this dopaminergic response is mediated by PTX-insensitive G proteins. Co-immunoprecipitation studies indicated that in membranes of HN33.11 cells, D₁-like binding sites are coupled to Gα_q protein. Blockade of SKF38393-induced PI hydrolysis with antiserum against phospholipase C (PLC) isozymes, performed in permeabilized cells, as well as co-immunoprecipitation studies implicate PLCβ3 and PLCβ4 in this dopaminergically mediated PI hydrolysis cascade. The results indicate that HN33.11 cells express a D₁-like DA receptor that couples to PLCβ3/4 via Gα_q protein. These cells may therefore be a useful model system for investigating this receptor system.     

Analysis of δ-globin gene alleles in Tunisians: description of three new delta-thalassemia mutations

Molecular Biology Reports - Thalassemia is one of the most prevalent worldwide autosomal recessive disorders characterized by a great molecular and clinical expression heterogeneity. Alpha and...     

A Point Mutation in the Ethylene-Inducing Xylanase Elicitor Inhibits the β-1-4-Endoxylanase Activity But Not the Elicitation Activity

Ethylene-inducing xylanase (EIX) elicits plant defense responses in certain tobacco (Nicotiana tabacum) and tomato cultivars in addition to its xylan degradation activity. It is not clear, however, whether elicitation occurs by cell wall fragments released by the enzymatic activity or by the xylanase protein interacting directly with the plant cells. We cloned the gene encoding EIX protein and overexpressed it in insect cells. To determine the relationship between the two activities, substitution of amino acids in the xylanase active site was performed. Substitution at glutamic acid-86 or -177 with glutamine (Gln), aspartic acid (Asp), or glycine (Gly) inhibited the β-1-4-endoxylanase activity. Mutants having Asp-86 or Gln-177 also lost the ability to induce the hypersensitive response and ethylene biosynthesis. However, mutants having Gln-86, Gly-86, Asp-177, or Gly-177 retained ability to induce ethylene biosynthesis and the hypersensitive response. Our data show that the xylanase activity of EIX elicitor can be separated from the elicitation process, as some of the mutants lack the former but retain the latter.     

Changes in microbial diversity in industrial wastewater evaporation ponds following artificial salination

The salinity of industrial wastewater evaporation ponds was artificially increased from 3-7% to 12-16% (w/v), in an attempt to reduce the activity of sulfate-reducing bacteria (SRB) and subsequent emission of H2S. To investigate the changes in bacterial diversity in general, and SRB in particular, following this salination, two sets of universal primers targeting the 16S rRNA gene and the functional apsA [adenosine-5'-phosphosulfate (APS) reductase alpha-subunit] gene of SRB were used. Phylogenetic analysis indicated that Proteobacteria was the most dominant phylum both before and after salination (with 52% and 68%, respectively), whereas Firmicutes was the second most dominant phylum before (39%) and after (19%) salination. Sequences belonging to Bacteroidetes, Spirochaetes and Actinobacteria were also found. Several groups of SRB from Proteobacteria and Firmicutes were also found to inhabit this saline environment. Comparison of bacterial diversity before and after salination of the ponds revealed both a shift in community composition and an increase in microbial diversity following salination. The share of SRB in the 16S rRNA gene was reduced following salination, consistent with the reduction of H2S emissions. However, the community composition, as shown by apsA gene analysis, was not markedly affected.     

Pharmacological properties of biogenically synthesized silver nanoparticles using endophyte Bacillus cereus extract of Berberis lyceum against oxidative stress and pathogenic multidrug-resistant bacteria

The emergence of multidrug resistance in pathogenic bacteria limits the utilization of available antibiotics. The development of alternate options to treat infectious diseases is the need of the day.The present study was aimed to synthesize, characterize and evaluate the bioactive properties of silver nanoparticles. Endophytic bacterium Bacillus cereus (MT193718) isolated from Berberis lycium was used to synthesize biocompatible silver nanoparticles. Antibacterial properties of AgNPs were evaluated against clinically isolated multidrug-resistant strains of Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae. AgNPs indicated significant antibacterial activity against S. aureus and K. pneumoniae fwith a zone of inhibition of 17 and 18 mm at a concentration of 1000 µg/ mL with minimum inhibitory concentration of 15.6 and 62.5 µg/mL respectively. Significant antioxidant activity with an IC50 value of 9.5 µg/mL was recorded. Biosynthesized AgNPs were found compatible with red blood cells at a concentration of 31.5 µg/ml with no clumping of erythrocytes. The study suggested that AgNPs synthesized by the endophytic bacterium Bacillus cereus are biologically active and can be used as antioxidant and antibacterial agents against drug-resistant bacteria.