Effects of short vs. prolonged mechanical ventilation on antioxidant systems in piglet diaphragm

Objective Prolonged controlled mechanical ventilation (MV) is known to induce diaphragmatic oxidative stress that seems to be an important factor reducing force-generating capacity. To better understand the cellular mechanisms involved, this work examined the effect of short vs. prolonged MV on antioxidant defense in the diaphragm.Design and setting Prospective, randomized, controlled animal study in a university laboratory.Methods Eleven piglets (15–20 kg) were assigned to one of two groups: a long-MV group (n=6) ventilated for 3 days or a short-MV group (n=5) ventilated for 3 h. Force frequency curves of the transdiaphragmatic pressure (Pdi) were obtained in vivo by phrenic nerve pacing. Oxidative stress was evaluated by thiobarbituric reactive substance (TBARs) content and the enzymatic antioxidant activity of both superoxide dismutase (SOD) and glutathione peroxidase (GPx) in samples of diaphragm.Results Pdi decreased in the long-MV group by 30–35% over the 3 days at all frequencies compared to the short-MV group. Diaphragm TBARs content was significantly higher and SOD activity lower in long-MV animals than in short-MV animals after 72 h. GPx activity tended to be lower in diaphragms from long-MV animals, but this difference was not significant.Conclusions This study shows that 3 days of MV in piglets is associated with a decrease in antioxidant activity which could emphasize oxidative stress and both contribute to the diaphragm dysfunction caused by MVElectronic Supplementary Material Electronic supplementary material to this paper can be obtained by using the Springer Link server located at .S. Jaber and M. Sebbane contributed equally to this study.This article refers to the editorial     

Cyanobacterial extracts containing microcystins affect the growth,nodulation process and nitrogen uptake of faba bean (<Emphasis Type="Italic">Vicia faba</Emphasis> L., Fabaceae)

The use of irrigation water containing cyanobacterial toxins may generate a negative impact in both yield and quality of agricultural crops causing significant economic losses. We evaluated the effects of microcystins (MC) on the growth, nodulation process and nitrogen uptake of a Faba bean cultivar (Vicia faba L., Fabaceae), particularly the effect of MC on rhizobia-V. faba symbiosis. Three rhizobial strains (RhOF4, RhOF6 and RhOF21), isolated from nodules of local V. faba were tested. The exposure of rhizobia to MC showed that the toxins had a negative effect on the rhizobial growth especially at the highest concentrations of 50 and 100 μg/l. The germination of faba bean seeds was also affected by cyanotoxins. We registered germination rates of 75 and 68.75% at the toxin levels of 50 and 100 μg/l as compared to the control (100%). The obtained results also showed there was a negative effect of MC on plants shoot, root (dry weight) and total number of nodules per plant. Cyanotoxins exposure induced a significant effect on nitrogen assimilation by faba bean seedlings inoculated with selected rhizobial strains RhOF6 and RhOF21, while the effect was not significant on beans seedling inoculated with RhOF4. This behavior of tolerant rhizobia-legumes symbioses may constitute a very important pathway to increase soil fertility and quality and can represent a friendly biotechnological way to remediate cyanotoxins contamination in agriculture.     

Acute hypertension in intracerebral hemorrhage: pathophysiology and treatment

Non-traumatic or spontaneous intracerebral hemorrhage (ICH) is defined as intra-parenchymal bleeding with or without extension into the ventricles and rarely into the subarachoid space. Primary ICH in most cases is associated with chronic hypertension. Acute hypertension is associated with hematoma expansion, and poor neurological outcome. The treatment of hypertension in acute ICH is a topic of controversy. Experiments have shown an area of ischemia around the hematoma, with the reduction of regional cerebral blood flow (CBF) secondary to compression of microvasculature. Not all scientific results agree with the above findings. Recent studies have shown that CBF decreases in the perihematoma region but with concomitant reduction of cerebral metabolism, which would argue against an area of ischemia in the perihematoma region. Based on the above result, there have been several clinical trials looking at clinical outcome and decrease in hematoma expansion rates with reduction of blood pressure acutely after ICH. The parameters for the blood pressure control are still under investigation. The American Heart Association has put forward guidelines for blood pressure control which have been adopted in the centers around the country. We have described the protocol we use at our center for the blood pressure control in patients with acute ICH.     

Linear quantitation of Abeta aggregation using Thioflavin T: reduction in fibril formation by colostrinin

Thioflavin T (ThT) fluorescence is a commonly used method to monitor Aβ protein fibril formation. This method is particularly attractive since ThT fluoresces only when bound to fibrils, the reaction is completed within 1 min and ThT does not interfere with aggregation of Aβ fibrils. One of the drawbacks of this method is the lack of a strict quantitative relationship between ThT fluorescence and fibril content. It was observed that, when the same gram molecular weight of Aβ (1–40) is dissolved into varying amounts of base then placed into a constant volume of aqueous buffer, a non-linear fluorescent response is obtained. By maintaining a strict relationship between Aβ content and the volume of base, this anomalous result can be alleviated and a linear dose response curve is obtained at much lower Aβ concentrations than is typically observed.

In addition, differences in Aβ batch to batch preparations are alleviated. It was previously reported that colostrinin (CLN), a proline-rich peptide derived from colostrum, reduces fibril content and protects neuroblastoma cells against Aβ peptide-induced toxicity. The newly developed ThT fluorescence protocol was used to quantify Aβ fibril content after treatment with CLN. We also demonstrate that CLN, can solubilize Aβ fibrils in a dose and time-dependent fashion.     

The role of flagellin versus motility in acute lung disease caused by Pseudomonas aeruginosa

The flagellum of Pseudomonas aeruginosa has been implicated in acute pneumonia, and its flagellin is known to cause lung inflammation. However, its proinflammatory role, versus its motility function, as a cause of death by a whole bacterium has not been demonstrated. This issue was examined in a lung model of acute infection using different flagellar mutants. We found that the absence of motility does not significantly alter the LD(50), whereas the production of excess amounts of flagellin lowers it and results in early death. Next, we found that the absence of the Toll-like receptor 5 (TLR5) ligand, flagellin, results in slower clearance of this organism from the lungs and a delay in the time to death. These findings demonstrate the dual role of flagellin in host defense and in disease and suggest that the death in this model may be biphasic with flagellin playing a role early in the disease.