Effects of fluoride emission on the morphoanatomy of three plant species endemics to Brazil using passive biomonitoring

Fluoride is the most phytotoxic atmospheric pollutant. The objective of this study was to evaluate the effects of fluoride emissions by an aluminum smelter on three plant species endemics to Brazil, located at Parque Estadual do Itacolomi (PEI). The monitored species were Byrsonima variabilis (Malpighiaceae), Myrceugenia alpigena (Myrtaceae), and Eremanthus erythropappus (Asteraceae), which were monitored during 9 months using passive biomonitoring at five different locations with different distances from the smelter. The monitored species did not show macroscopic phytotoxicity damage to fluoride; however, they did show microscopic damage. The species closer to the smelter presented more severe anatomic damages, such as rupture of cell walls, protoplast retraction, and trichome alterations. Damaged stomatal ledges, flaking epicuticular wax, and damages to trichomes were observed. M. alpigena showed a higher accumulation of fluoride than the other species at all monitored sites. The test for cell death with Evans Blue was positive for the three studied species. Through biomonitoring in the PEI, we concluded that the emissions from the aluminum smelter affect the native vegetation and that due to the greater accumulation of fluoride and the diversity of microscopic damage in M. alpigena, the use of this species in the monitoring of environments polluted by fluoride is enhanced.

Application of a programmed semi-automated Ulva pertusa bioassay for testing single toxicants and stream water quality

A toxicity test based on inhibition of reproduction in the green macroalga Ulva pertusa involves quantifying the change in thallus color as reproduction progresses. However, interpretation of this color change is reliant on the skill level of the examiner. This study aimed to validate a new toxicity test based on inhibition of reproduction in the green macroalga U. pertusa using a vital stain and programmed semi-automated analysis (using Image J) of the change in thallus color. The toxicity rank by inverse EC₅₀ values was: irgarol (0.048 mg L^-1) > Ag (0.132 mg L^-1) > As (0.172 mg L^-1) > simazine (0.378 mg L^-1) > formaldehyde (0.442 mg L^-1) > DCOIT (0.783 mg L^-1) > ZnPT (3.556 mg L^-1) > medetomidine (11.600 mg L^-1) > phenol (29.316 mg L^-1) > methanol (2,736 mg L^-1) > ethanol (3,306 mg L^-1). The sensitivity of the U. pertusa test to stream waters was similar to or lower than those of the commonly-used Lemna minor and Daphnia magna bioassays. The U. pertusa bioassay is sensitive to, and suitable for, testing various toxicants including metals, volatile organic compounds, herbicide, antifouling agents and phenol and can also be applied to testing freshwater quality after salinity adjustment.

Reappraisal of the toxicity test method using the green alga Ulva pertusa Kjellman (Chlorophyta)

This study was aimed to develop an objective way of quantifying the reproductive status of the green macroalga, Ulva pertusa using a vital stain and programmed automated analysis (by Image J program). The EC₅₀ values (with 95% CI), the concentrations of toxicants inducing a reduction of 50% in sporulation after 96 h exposure, from the newly developed method were similar to those obtained by the conventional method: 0.651 (0.598-0.705) mg l^-1 for Cd, 0.144 (0.110-0.162) mg l^-1 for Cu, 0.180 (0.165-0.195) mg l^-1 for atrazine, 0.076 (0.049-0.094) mg l^-1 for diuron and 30.6 (26.5-34.4) ml l^-1 for DMSO, respectively. When the EC₅₀ values from this study were compared to that those from literatures, the sensitivity for some toxicants was similar or higher than that of U. fasciata (1.930 mg l^-1 for germination for Cd), U. armoricana (0.250 mg l^-1 for Fv/Fm for Cu), U. reticulata (0.126-1.585 mg l^-1 for growth for Cu), and U. intestinalis (0.650 mg l^-1 for Fv/Fm for atrazine). The subjective views of the experimental performers can be eliminated using the newly developed method. The Ulva method gave consistent responses to Cu and Cd of internationally allowable ranges for effluents, implying that the method is a useful tool for monitoring industrial wastewaters containing these metals.

The accuracy of the modified Evan's blue dye test in detecting aspiration in tracheostomised patients

OBJECTIVES

To evaluate the sensitivity and specificity of the modified Evans blue dye test compared to the fibre-optic endoscopic evaluation of swallowing to detect aspiration in tracheostomised patients.

METHODS

This observational accuracy study included 17 patients hospitalised for respiratory complications, subjected to prolonged intubation, and for this reason, tracheostomised.

RESULTS

Mean patient age was 60.2 ± 21.0 years. Aspiration was identified in 10 patients when assessed by fibre-optic endoscopic evaluation of swallowing; of these, 1 had aspiration when evaluated by modified Evans blue dye test. The dye test had a sensitivity of 10.0 per cent and specificity of 100.0 per cent for detecting aspiration. Fibre-optic endoscopic evaluation of swallowing revealed no statistically significant associations between aspiration presence and: speech and language therapy duration, intubation time, or tracheostomy plus mechanical ventilation duration.

CONCLUSION

The modified Evans blue dye test is simple and inexpensive, and does not require prior knowledge in endoscopy; it may be used as an initial screening test in all tracheostomised patients for evaluating aspiration. However, fibre-optic endoscopic evaluation of swallowing should be used for a more comprehensive diagnosis of tracheostomy patients, especially for those at high risk for aspiration.

A High-Throughput Chemical Screening Method for Inhibitors and Potentiators of Hypersensitive Cell Death Using Suspension Cell Culture of Arabidopsis thaliana

Chemical biology provides an alternative way to identify genes involved in a particular biological process. It has the potential to overcome issues such as redundancy or lethality often found in genetic approaches, since the chemical compounds can simultaneously target all homologous proteins that function at the same step, and chemicals can be applied conditionally. Even with a variety of genetic approaches, the molecular mechanisms of plant hypersensitive cell death that occurs during disease resistance responses remain unclear. Therefore, application of chemical biology should provide new insights into this phenomenon. Here we describe a high-throughput chemical screening procedure to detect hypersensitive cell death quantitatively, using a suspension cell culture of Arabidopsis thaliana and a well-studied avirulent bacterial pathogen, Pseudomonas syringae pv. tomato DC3000 avrRpm1.

A Mouse Controlled Cortical Impact Model of Traumatic Brain Injury for Studying Blood-Brain Barrier Dysfunctions

Traumatic brain injury (TBI) is one of the leading causes of death and disability worldwide. It is a silently growing epidemic with multifaceted pathogenesis, and current standards of treatments aim to target only the symptoms of the primary injury, while there is a tremendous need to explore interventions that can halt the progression of the secondary injuries. The use of a reliable animal model to study and understand the various aspects the pathobiology of TBI is extremely important in therapeutic drug development against TBI-associated complications. The controlled cortical impact (CCI) model of TBI described here, uses a mechanical impactor to inflict a mechanical injury into the mouse brain. This method is a reliable and reproducible approach to inflict mild, moderate or severe injuries to the animal for studying TBI-associated blood-brain barrier (BBB) dysfunctions, neuronal injuries, brain edema, neurobehavioral changes, etc. The present method describes how the CCI model could be utilized for determining the BBB dysfunction and hyperpermeability associated with TBI. Blood-brain barrier disruption is a hallmark feature of the secondary injury that occur following TBI, frequently associated with leakage of fluid and proteins into the extravascular space leading to vasogenic edema and elevation of intracranial pressure. The method described here focuses on the development of a CCI-based mouse model of TBI followed by the evaluation of BBB integrity and permeability by intravital microscopy as well as Evans Blue extravasation assay.

Evaluation of Vascularity, Blood Perfusion, and Oxygen Tension in Tumor Xenografts with Fluorescent Microscopy

Histologic heterogeneity in glioblastoma (GBM) is highlighted by regional variability in vascular density. Areas of vascular hyperplasia are interspersed with avascular territories, in which necrosis is surrounded by a zone of hypoxic tumor cells expressing stem cell markers, a phenomenon known as pseudopalisading necrosis. This vascular heterogeneity suggests intratumoral oxygen gradients, which regulate cellular and metabolic adaptations in tumor cells. Quantification of tumor vascularity, blood perfusion and oxygenation is therefore critical. In this chapter, we describe three different methods, all of which involve microscopy to analyze these parameters in tumor xenografts. We present detailed protocols for analysis of tumor endothelium using endothelial markers, blood perfusion by systemic infusion of Evans Blue and oxygen tension by pimonidazole injection, followed by immunostaining.

Docosahexaenoic acid improves behavior and attenuates blood-brain barrier injury induced by focal cerebral ischemia in rats

BACKGROUND

Ischemic brain injury disrupts the blood-brain barrier (BBB) and then triggers a cascade of events, leading to edema formation, secondary brain injury and poor neurological outcomes. Recently, we have shown that docosahexaenoic acid (DHA) improves functional and histological outcomes following experimental stroke. However, little is known about the effect of DHA on BBB dysfunction after cerebral ischemia-reperfusion injury. The present study was designed to determine whether DHA protects against BBB disruption after focal cerebral ischemia in rats.

METHODS

Physiologically-controlled SD rats received 2 h middle cerebral artery occlusion (MCAo). DHA (5 mg/kg) or vehicle (saline) was administered I.V. at 3 h after onset of MCAo. Fluorometric quantitation of Evans Blue dye (EB) was performed in eight brain regions at 6 h, 24 h or 72 h after MCAo. Fluorescein isothiocynate (FITC) - dextran leakage and histopathology was evaluated on day 3 after stroke.

RESULTS

Physiological variables were stable and showed no significant differences between groups. DHA improved neurological deficits at 24 h, 48 h and 72 h and decreased EB extravasation in the ischemic hemisphere at 6 h (by 30%), 24 h (by 48%) and 72 h (by 38%). In addition, EB extravasation was decreased by DHA in the cortex and total hemisphere as well. FITC-dextran leakage was reduced by DHA treatment on day 3 by 68% compared to the saline group. DHA treatment attenuated cortical (by 50%) and total infarct volume (by 38%) compared to vehicle-treated rats on day 3 after stroke.

CONCLUSIONS

DHA therapy diminishes BBB damage accompanied with the acceleration of behavioral recovery and attenuation of the infarct volume. It is reasonable to propose that DHA has the potential for treating focal ischemic stroke in the clinical setting.