Proved viraemia in asian influenza (Hong Kong variant) during incubation period

During an outbreak of influenza specimens were obtained from 21 patients with influenza-like illnesses and from 29 healthy subjects in close contact with the patients. Throat washings from 12 of the patients were positive for influenza virus but virus was not detected from the blood specimens. One healthy contact became ill 12 hours after the specimens were obtained, and the virus was isolated from his blood and throat washings. The remaining contacts showed no clinical illness; but the virus was isolated from the throat washings of four of them, with no viral isolation from the blood specimens.     

Aluminium toxicity and binding to Escherichia coli

The toxicity and binding of aluminium to Escherichia coli has been studied. Inhibition of growth by aluminium nitrate was markedly dependent on pH; growth in medium buffered to pH 5.4 was more sensitive to 0.9 mM or 2.25 mM aluminium than was growth at pH 6.6–6.8. In medium buffered with 2-(N-morpholino)ethanesulphonic acid (MES), aluminium toxicity was enhanced by omission of iron from the medium or by use of exponential phase starter cultures. Analysis of bound aluminium by atomic absorption spectroscopy showed that aluminium was bound intracellularly at one type of site with a K _m of 0.4 mM and a capacity of 0.13 mol (g dry wt)^-1. In contrast, binding of aluminium at the cell surface occurred at two or more sites with evidence of cooperativity. Addition of aluminium nitrate to a weakly buffered cell suspension caused acidification of the medium attributable to displacement of protons from cell surfaces by metal cations. It is concluded that aluminium toxicity is related to pH-dependent speciation [with Al(H₂O) ₆ ³⁺ probably being the active species] and chelation of aluminium in the medium. Aluminium transport to intracellular binding sites may involve Fe(III) transport pathways.     

Effect of a normal protein diet on oxidative stress and organ damage in malnourished rats

Background

We investigated the effects of three weeks of renutrition with a normal protein diet on oxidant/antioxidant status in malnourished rats using biochemistry and histology.

Methods

Eighteen young Wistar rats were divided into three groups: control group was fed on a normal protein diet; malnourished group was fed on low protein diet and renourished group was fed on low protein diet followed by a normal protein diet. Serum albumin was evaluated. Malondialdehyde, protein carbonyl, superoxide dismutase and catalase levels were determined in the intestine, muscle and liver. Intestinal and hepatic damage were assessed by histological examination.

Results

Protein malnutrition resulted in a significant decrease of body weight, albumin level, villus length, intraepithelial lymphocytes counts (IELC) and superoxide dismutase level (liver and muscle). However, catalase activity increased significantly in muscle and gut but there was no difference in liver. In all organs, malondialdehyde and protein carbonyl content of malnourished group showed a significant increase. Interestingly, a normal protein diet for three weeks resulted in a return to normal levels of superoxide dismutase, albumin, malondialdehyde and protein carbonyl in all organs. Catalase activity decreased in the muscle and gut and exhibited no significant difference in the liver. The renutrition diet enhanced also the recovery of intestinal epithelium by increasing villus length. Hepatic damage of rats fed normal protein diet was markedly reduced (macrovesicular steatosis decreased by 45%).

Conclusion

The normal protein diet could improve the oxidant/antioxidant imbalance and organ damage induced by protein malnutrition.

     

Acetylated pseudoguaianolides from Parthenium hysterophorus and their cytotoxic activity

Chemical examination of the flowers of Parthenium hysterophorus has resulted in the isolation of four acetylated pseudoguaianolides along with several known constituents. The structures of the compounds were derived from detailed studies of their spectral (1D and 2D NMR and FABMS) data and by comparison of the values with those of parthenin, a major known constituent of the plant. The cytotoxic activity of parthenin and the constituents was evaluated using Jurkat (human: T lymphocyte; acute T cell leukemia), HL-60 (human leukemia) and Hela (human cervical carcinoma) cells.     

Activation of the heat shock response in plants by chlorophenols: transgenic Physcomitrella patens as a sensitive biosensor for organic pollutants

The ability to detect early molecular responses to various chemicals is central to the understanding of biological impact of pollutants in a context of varying environmental cues. To monitor stress responses in a model plant, we used transgenic moss Physcomitrella patens expressing the beta-glucuronidase reporter (GUS) under the control of the stress-inducible promoter hsp17.3B. Following exposure to pollutants from the dye and paper industry, GUS activity was measured by monitoring a fluorescent product. Chlorophenols, heavy metals and sulphonated anthraquinones were found to specifically activate the hsp17.3B promoter (within hours) in correlation with long-term toxicity effects (within days). At mildly elevated physiological temperatures, the chemical activation of this promoter was strongly amplified, which considerably increased the sensitivity of the bioassay. Together with the activation of hsp17.3B promoter, chlorophenols induced endogenous chaperones that transiently protected a recombinant thermolabile luciferase (LUC) from severe heat denaturation. This sensitive bioassay provides an early warning molecular sensor to industrial pollutants under varying environments, in anticipation to long-term toxic effects in plants. Because of the strong cross-talk between abiotic and chemical stresses that we find, this P. patens line is more likely to serve as a direct toxicity bioassay for pollutants combined with environmental cues, than as an indicator of absolute toxicity thresholds for various pollutants. It is also a powerful tool to study the role of heat shock proteins (HSPs) in plants exposed to combined chemical and environmental stresses.     

An explanation for observed estrogen receptor binding to single-stranded estrogen-responsive element DNA.

Estrogen-inducible genes contain an enhancer called the estrogen response element (ERE), a double-stranded inverted repeat. The estrogen receptor (ER) is generally thought to bind to the double-stranded ERE. However, some reports provide evidence that an ER homodimer can bind a single strand of the ERE and suggest that single-stranded ERE binding is the preferred binding mode for ER. Since these two models describe quite different mechanisms of receptor action, we have attempted to reconcile the observations. Analyzing DNA structure by nuclease sensitivity, we found that two identical molecules of a single strand of DNA containing the ERE sequence can partially anneal in an antiparallel manner. Bimolecular annealing produces double-stranded inverted repeats, with adjacent unannealed tails. The amount of annealing correlates exactly with the ability of ER to bind bimolecular EREs. Either strand of an ERE could anneal to itself in a way that would bind ER. We conclude that ER binds only the annealed double-stranded ERE both in vitro and in vivo.     

Regulation of TGF-β1-driven Differentiation of Human Lung Fibroblasts: EMERGING ROLES OF CATHEPSIN B AND CYSTATIN C*

Lung matrix homeostasis partly depends on the fine regulation of proteolytic activities. We examined the expression of human cysteine cathepsins (Cats) and their relative contribution to TGF-β1-induced fibroblast differentiation into myofibroblasts. Assays were conducted using both primary fibroblasts obtained from patients with idiopathic pulmonary fibrosis and human lung CCD-19Lu fibroblasts. Pharmacological inhibition and genetic silencing of Cat B diminished α-smooth muscle actin expression, delayed fibroblast differentiation, and led to an accumulation of intracellular 50-kDa TGF-β1. Moreover, the addition of Cat B generated a 25-kDa mature form of TGF-β1 in Cat B siRNA-pretreated lysates. Inhibition of Cat B decreased Smad 2/3 phosphorylation but had no effect on p38 MAPK and JNK phosphorylation, indicating that Cat B mostly disturbs TGF-β1-driven canonical Smad signaling pathway. Although mRNA expression of cystatin C was stable, its secretion, which was inhibited by brefeldin A, increased during TGF-β1-induced differentiation of idiopathic pulmonary fibrosis and CCD-19Lu fibroblasts. In addition, cystatin C participated in the control of extracellular Cats, because its gene silencing restored their proteolytic activities. These data support the notion that Cat B participates in lung myofibrogenesis as suggested for stellate cells during liver fibrosis. Moreover, we propose that TGF-β1 promotes fibrosis by driving the effective cystatin C-dependent inhibition of extracellular matrix-degrading Cats.     

Proteomics analysis of date palm leaves affected at three characteristic stages of brittle leaf disease

Proteomics analysis has been performed in leaf tissue from field date palm trees showing the brittle leaf disease (BLD) or maladie des feuilles cassantes, the main causal agent of the date palm decline in south Tunisia. To study the evolution of the disease, proteins from healthy and affected leaves taken at three disease stages (S1, S2 and S3) were trichloroacetic acid acetone extracted and subjected to two-dimensional gel electrophoresis (5–8 pH range). Statistical analysis showed that the protein abundance profile is different enough to differentiate the affected leaves from the healthy ones. Fifty-eight variable spots were successfully identified by matrix-assisted laser desorption ionization time of flight, 60 % of which corresponded to chloroplastic ones being involved in the photosynthesis electronic chain and ATP synthesis, metabolic pathways implicated in the balance of the energy, and proteases. Changes in the proteome start at early disease stage (S1), and are greatest at S2. In addition to the degradation of the ribulose-1.5-bisphosphate carboxylase oxygenase in affected leaflets, proteins belonging to the photosynthesis electronic chain and ATP synthesis decreased following the disease, reinforcing the relationship between BLD and manganese deficiency. The manganese-stabilizing proteins 33 kDa, identified in the present work, can be considered as protein biomarkers of the disease, especially at early disease step.     

Cascade bioreactor with submerged biofilm for aerobic treatment of Tunisian landfill leachate

A bioreactor cascade with a submerged biofilm is proposed to treat young landfill leachate of jbel chakir landfill site south west from capital Tunis, Tunisia. The prototype was run under different organic loading charges varying from 0.6 to 16.3 kg TOC m⁻³ day⁻¹. Without initial pH adjustment total organic carbon (TOC) removal rate varied between 65% and 97%. The total reduction of COD reached 92% at a hydraulic retention time of 36 h. However, the removal of total kjeldahl nitrogen for loading charges of 0.5 kg N m⁻³ day⁻¹ reached 75%. The adjustment of pH to 7.5 improved nitrogen removal to a rate of 85% for loading charge of 1 kg N m⁻³ day⁻¹. The main bacterial groups responsible for a simultaneous removal of organic carbon and nitrogen belonged to Bacillus, Actinomyces, Pseudomonas and Burkholderia genera. These selected isolates showed a great capacity of degradation at different leachate concentrations of total organic carbon.