Alexandra Sousa

Acute effects of Benzo[a]pyrene, anthracene and a fuel oil on biomarkers of the common goby Pomatoschistus microps (Teleostei, Gobiidae).

The objective of this study was to investigate the effects of two different PAHs and a complex petrochemical mixture on the common goby, Pomatoschistus microps, using selected biomarkers as effect criteria. Benzo[a]pyrene (BaP) and anthracene were used as reference substances, while the water accommodated fraction of #4 fuel-oil (#4 WAF) was used as an example of a petrochemical mixture. P. microps was used since it is both a suitable bioindicator and a good test organism. Groups of fish were exposed to different concentrations of each of the test substances for 96 h and the activities of several enzymes commonly used as biomarkers were determined at the end of the bioassays. All the substances inhibited P. microps acetylcholinesterase (AChE) indicating that they have at least one mechanism of neurotoxicity in common: the disruption of cholinergic transmission by inhibition of AChE. An induction of lactate dehydrogenase (LDH) activity was found in fish exposed to BaP or to anthracene, suggesting an increase of the anaerobic pathway of energy production. On the contrary, inhibition of LDH was found in fish exposed to #4 WAF, suggesting a distinct effect of the mixture. An induction of P. microps glutathione S-transferase (GST) activity was found in fish exposed to BaP or to #4 WAF, while an inhibition was observed after exposure to anthracene. These results suggest that GST is involved in the detoxification of BaP and #4 WAF, but not of anthracene. All the substances increased catalase activity and isolated PAHs also increased superoxide dismutase, glutathione reductase and glutathione peroxidase activities, while #4 WAF did not cause significant alterations on these enzymes. These results suggest that all the substances may induce oxidative stress on P. microps, with BaP and anthracene apparently having more oxidative stress potential than #4 WAF.

Solanum nigrum L. weed plants as a remediation tool for metalaxyl-polluted effluents and soils

In this work, the phytoremediation potential of metalaxyl, a commonly used persistent, mobile and leachy fungicide, by Solanum nigrum L. plants was studied. The study revealed that this plant species can be used as an excellent metalaxyl phytoremediation tool, thus providing a cost effective and environmentally friendly clean technology for the decontamination of sites and effluents. As it can be sowed directly in the remediation site, is able to complete its life cycle without suffering major stress. Because it accumulates high amounts of the fungicide in the aboveground tissues, enables its concentration and proper disposal by cutting off the corresponding plant part. The study also suggests that the tolerance to metalaxyl is due to a suitable antioxidant response comprising proline accumulation and guaiacol peroxidase and glutathione-S-transferase enhanced activities, that reduce oxidative damage to the plant organs.

The usefulness of the head-up tilt test in patients with suspected epilepsy.

PURPOSE It is estimated that approximately 20-30% of patients diagnosed with epilepsy have been misdiagnosed, and neurocardiogenic syncope (NCS) might frequently be the real cause of transient loss of consciousness (TLOC) episodes. We assessed the role of the head-up tilt test (HUTT) in patients previously diagnosed with refractory epilepsy to evaluate the ability of this test to correctly diagnose patients with NCS. METHOD We retrospectively analysed the clinical records of 107 consecutive patients with a previous diagnosis of refractory epilepsy that were taking antiepileptic drugs and who were referred for HUTT between January 2000 and December 2010. During the subsequent follow-up, we recorded the treatments performed and the recurrence of symptoms. RESULTS Complete follow-up data were available for 94 (88%) patients, and the mean follow-up period was 80±36 months. The HUTT was positive in 54% of patients. Thirty-one (33%) patients were misdiagnosed with epilepsy, and 20 (21%) patients had a dual diagnosis of NCS and epilepsy. The recurrence of TLOC was reported in 55% of the patients, but it was significantly lower in the misdiagnosed group (42% versus 64%; P=0.039). CONCLUSION NCS is an important cause of epilepsy misdiagnosis. The HUTT is often critical for making an accurate diagnosis and subsequently selecting the appropriate treatment for patients presenting with TLOC. The diagnostic overlap between epilepsy and NCS is not uncommon, suggesting that electroencephalographic monitoring during a HUTT may play an important role in diagnosing patients with recurrent, undiagnosed TLOC episodes.

Statin-Induced Low Cholesterol is Not Associated With Poor Outcome in Chronic Heart Failure

Background: Low cholesterol levels are associated with a worse outcome in patients with heart failure (HF). Use of statins in HF remains controversial. We aimed to assess whether the prognosis of patients with intrinsically low cholesterol levels differed from that of those with pharmacologically induced low cholesterol. Materials and Methods: We conducted a retrospective cohort study on 464 ambulatory patients attending a specialized HF clinic. Patients were cross-classified according to statin therapy and admission total cholesterol level (low cholesterol <150 mg/dL and cholesterol ≥150 mg/dL): (1) low total cholesterol level on statin therapy; (2) low total cholesterol level not taking statins; (3) cholesterol ≥150 mg/dL on statin therapy; and (4) cholesterol ≥150 mg/dL not on statin therapy. Patients were followed up to 5 years and the outcome was all-cause death. A Cox regression analysis was used in prognosis assessment. Results: Almost two thirds of the patients were men and the median population age was 69 years; 22.8% of the patients had preserved ejection fraction and 43.5% severe systolic dysfunction. The patients with an intrinsically low cholesterol had a hazard ratio of all-cause death up to 5 years of 2.38 (1.08-7.14) compared to those with low cholesterol induced by statin use. This association was independent of other variables associated with outcome. Conclusions: Patients with HF with instrisically low cholesterol levels have a double risk of death up to 5 years compared to patients with pharmacologically induced low cholesterol. Clinicians should not limit the use of statins by fear of lowering the cholesterol levels.

Embolic complication of left ventricular non-compaction as an unusual cause of acute myocardial infarction

One of the greatest challenges in medicine consists of arriving at a correct diagnosis despite different presentations of the disease. We present a case in which, notwithstanding the initial diagnosis, the search for the etiology was essential for clinical guidance. Left ventricular non-compaction (LVNC) was first described by Chin et al. in 1990. This relatively new entity is characterized by excessive thickening of the myocardial wall, formed of a thin epicardial layer and a substantially thicker non-compacted endocardial layer. The clinical presentation is highly variable but it must always be borne in mind that heart failure, atrial and ventricular arrhythmias and embolic events are common complications of LVNC.

Prevalence, predictors and prognosis of ventricular reverse remodeling in idiopathic dilated cardiomyopathy

INTRODUCTION Cardiac remodeling is manifested as changes in size, shape and function of the heart. We studied the prevalence, prognosis and predictors of left ventricular reverse remodeling (LVRR) in idiopathic dilated cardiomyopathy (IDCM) after optimized medical therapy. METHODS A total of 113 IDCM patients were followed for 7.1±5.6 years. LVRR was defined as an increase of 10 units in ejection fraction (EF) and decrease in left ventricular diastolic diameter (LVDD), in the absence of resynchronization therapy. RESULTS Baseline EF was 27±8% and LVDD index was 37.1±6.3 mm/m(2). LVRR occurred in 34.5% within 22.6 months. Final EF was 47.5±10.1%, LVDD index was 30.2±3.9 mm/m(2). LVRR was associated with better NYHA class (I-II) and lower BNP (p<0.01) and all patients were alive. Univariate predictive factors of LVRR (p<0.05) were mild hypertension, atrial fibrillation, ventricular hypertrophy on ECG, absence of left bundle branch block, shorter QRS duration, higher hematocrit, lower LVDD index, higher peak oxygen uptake efficiency (VO2/log 10[VE]) and lower dVE/VCO2/VO2, treatment with angiotensin-converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB) and use of maximal doses of ACEI/ARB and beta-blockers. Multivariate regression analysis showed that higher doses of ACEI/ARB (OR: 0.32, 95% CI 0.11-0.92) were independently associated with LVRR. Non-transmural late enhancement on cardiac MRI was not a predictor of LVRR. CONCLUSIONS LVRR occurred in one third of IDCM patients, especially in those with mild hypertension and with less advanced disease, who may have benefited from maximal drug titration.

Oxidative Metabolism of Rye (Secale cereale L.) after Short Term Exposure to Aluminum: Uncovering the Glutathione–Ascorbate Redox Network

One of the major limitations to plant growth and yield in acidic soils is the prevalence of soluble aluminum ions (Al3+) in the soil solution, which can irreversible damage the root apex cells. Nonetheless, many Al-tolerant species overcome Al toxicity and are well-adapted to acidic soils, being able to complete their life cycle under such stressful conditions. At this point, the complex physiological and biochemical processes inherent to Al tolerance remain unclear, especially in what concerns the behavior of antioxidant enzymes and stress indicators at early plant development. Since rye (Secale cereale L.), is considered the most Al-tolerant cereal, in this study we resort to seedlings of two genotypes with different Al sensitivities in order to evaluate their oxidative metabolism after short term Al exposure. Al-induced toxicity and antioxidant responses were dependent on rye genotype, organ and exposure period. Al affected biomass production and membrane integrity in roots and leaves of the sensitive (RioDeva) genotype. Catalase was the primary enzyme involved in H2O2 detoxification in the tolerant (Beira) genotype, while in RioDeva this task was mainly performed by GPX and POX. Evaluation of the enzymatic and non-enzymatic components of the ascorbate–glutathione cycle, as well the oxalate content, revealed that Beira genotype coped with Al stress by converting DHA into oxalate and tartarate, which posteriorly may bind to Al forming non-toxic chelates. In contrast, RioDeva genotype used a much more ineffective strategy which passed through ascorbate regeneration. So, remarkable differences between MDHAR and DHAR activities appear to be the key for a higher Al tolerance.

SiO₂ nanomaterial as a tool to improve Hordeum vulgare L. tolerance to nano-NiO stress

This work was designed to assess the potential role of silicon dioxide nanomaterial (nano-SiO2) in enhancing barleys tolerance to nickel oxide nanomaterial (nano-NiO). For this purpose, plants were grown for 14days under nano-NiO (120mgkg-1) single and co-exposure with nano-SiO2 (3mgkg-1). The exposure of barley to nano-NiO caused a significant decrease in growth-related parameters and induced a negative response on the photosynthetic apparatus. However, upon nano-SiO2 co-exposure, the inhibitory effects of nano-NiO were partially reduced, with lower reductions in fresh and dry biomass, and with the recovery of the photosynthesis-related parameters. Plants growing under nano-NiO stress showed an overproduction of superoxide anion (O2.-), which favored the occurrence of oxidative stress and the enhancement of lipid peroxidation (LP), but the co-treatment with nano-SiO2 reverted this tendency, generally lowering or maintaining the levels of LP and stimulating the redox pathway of thiols. The evaluation of the antioxidant (AOX) system revealed that nano-NiO induced the accumulation of proline, along with a decrease in ascorbate in leaves. Furthermore, superoxide dismutase (SOD) activity was significantly enhanced and catalase (CAT) and ascorbate peroxidase (APX) seemed to have a pivotal role in H2O2 detoxification in leaves and roots, respectively. The response of the AOX system was even more prominent upon nano-SiO2 co-exposure, reinforcing the ameliorating functions of this nanomaterial. Overall, the present study highlighted the protective role of nano-SiO2 in barley plants under nano-NiO stress, possibly due to the Si-mediated protection against oxidative stress, by a more proactive performance of the plant AOX system.

Temperature Variation under Continuous Light Restores Tomato Leaf Photosynthesis and Maintains the Diurnal Pattern in Stomatal Conductance

The response of tomato plants (Solanum lycopersicum L. cv. Aromata) to continuous light (CL) in relation to photosynthesis, abscisic acid (ABA) and reactive oxygen species (ROS) was investigated to improve the understanding of the development and/or alleviation of CL-induced leaf injury in constant and diurnal temperature fluctuations with similar daily light integral and daily mean temperature. The plants were grown in three photoperiodic treatments for 15 days; One treatment with a 16/8 h light/dark period and a light/dark temperature of 27/17°C (Control), two CL treatments with 24 h photoperiods, one with a constant temperature of 24°C (CLCT) and the other one with variable temperature of 27/17°C for 16/8 ho, respectively (CLVT). A diurnal pattern of stomatal conductance (gs) and [ABA] was observed in the plants grown in the control and CLVT conditions, while the plants in CLCT conditions experienced a significant decrease in stomatal conductance aligned with an increase in ABA. The net photosynthesis (A) was significantly reduced in CLCT, aligned with a significant decrease in the maximum rate of Rubisco carboxylation (Vcmax), the maximum rate of electron transport (Jmax) and mesophyll diffusion conductance to CO2 (gm) in comparison to the control and CLVT. An increased production of H2O2 and O2•- linked with increased activities of antioxidative enzymes was seen in both CL treatments, but despite of this, leaf injuries were only observed in the CLCT treatment. The results suggest that the diurnal temperature fluctuations alleviated the CL injury symptoms, probably because the diurnal cycles of cellular mechanisms were maintained. The ROS were shown not to be directly involved in CL-induced leaf injury, since both ROS production and scavenging was highest in CLVT without leaf chlorotic symptoms.

Left ventricular apical hypoplasia: An unusual diagnosis

A 36-year-old woman was referred for medical evaluation prior to non-cardiac surgery. She was healthy and only complained of sporadic palpitations. The 12-lead electrocardiogram showed sinus rhythm and left bundle branch block. Transthoracic echocardiography revealed a normally functioning, slightly dilated left ventricle (LV), with the interventricular septum bulging toward the right ventricle (RV), which was elongated and wrapped around the LV (Figure 1; Supplementary material Videos S1 and S2). The papillary muscles were structurally abnormal and presented