1,720,970 research outputs found
Effects of inorganic and organic mercury on intracellular calcium levels in rat t lymphocytes
No full textThe importance of cytosolic free calcium level (fCa2+]i) in lymphocyte activation prompted us to investigate changes in [Ca2+]i in T cells caused by mercury com-pounds, which have been shown to have immunomodulatory and immunotoxic properties. Using fura-2 as fluorescent Ca2+ indicator, we found that both methyl- mercury (MeHg; 0.02-2 nM) and inorganic mercury (HgCI2; 0.01-1 pM) increased [Ca2+]i in lymphocytes from rat spleen in a concentration-dependent manner. The effect of MeHg was rapid and the increase of Ca2+ level was sustained in time, while HgCI2 caused a slow rise in [Ca2+]i. The effects of mercury compounds did not appear to be associated with alterations of membrane integrity, since there was no significant difference in the extent of MnCI2 quench between control and mercury-treated cells. However, HgCI2 (1 jtM) and MeHg (2 nM) appeared to cause membrane damage at longer incubation times (15 min). When cells were incubated in Ca2+-free medium (in the presence of 1 mM EDTA) MeHg still increased [Ca2+]i, though to a lesser extent, while HgCI2 had no effect. Heparin, an inhibitor of inositol 1, 4, 5,-trisphosphate-induced Ca2+ mobilization partially blocked this rise of [Ca2+]i, white carbonyl cyanide m-chlorophenylhydraxone (CCCP),. © 1988 by Hemisphere Publishing Corporation
Prolonged ethanol ingestion enhances benzene myelotoxicity and lowers urinary concentrations of benzene metabolite levels in CD-1 male mice.
No full textEffects of mercuric chloride and methyl mercury on cholinergic neuromuscular transmission in the guinea-pig ileum
No full textThe effects of mercuric chloride (HgCl2) and methyl mercury (MeHg) were examined on basal mechanical activity and electrically-induced neurogenic cholinergic contractions (twitch contractions) in longitudinal muscle-myenteric plexus strips from guinea-pig distal ileum. Both compounds at 0.33 microM slightly enhanced the amplitude of twitch contractions in approximately 50% preparations. This effect was probably due to facilitation of acetylcholine (ACh) release since 0.1 and 1 microM mercurials increased electrically-evoked tritium outflow from [3H]choline preloaded muscle layer with attached myenteric plexus. Conversely, higher mercury concentrations inhibited twitch contractions (HgCl2 IC50 = 21.3 +/- 6.4 microM; MeHg IC50 = 45.1 +/- 5.5 microM), as well as contractions to exogenous ACh (0.1 microM) in resting preparations, and concomitantly increased the basal tone. The former effects possibly reflected an antimuscarinic activity of mercury, while the latter was related to alterations of calcium homeostasis in the effector cells. Indeed, the effect of HgCl2 on basal tone was antagonized by the Ca2+ entry blocker nifedipine (3, 10, 30 nM), indicating Hg-induced facilitation of Ca2+ influx through voltage-dependent channels. On the whole, our results suggest that cholinergic neuromuscular transmission and Ca(2+)-dependent mechanisms underlying smooth muscle contractility are targets for mercury toxicity in the intestine
Carbon monoxide cardiotoxicity
No full textCardiac dysfunction including arrhythmias and myocardial ischemia have often been reported in carbon monoxide poisoning; scattered punctiform hemorrhages throughout the heart have been documented in autopsy samples. An appropriate diagnostic approach is crucial to assess carbon monoxide cardiac damage. This evaluation may be confounded by several factors, including the absence of overt symptoms and of specific ischemic changes in the electrocardiogram. In experimental studies, laboratory animals can develop cardiac changes similar to those seen in humans and therefore proved to be useful models to study the effects and the mechanisms of cardiac damage due to carbon monoxide. These investigations, as well as others performed in vitro, provide support for a direct action of carbon monoxide on the heart, in addition to systemic hypoxia produced by carboxyhemoglobin formation. This review focuses on the diagnostic aspects of carbon monoxide cardiotoxicity. Experimental results obtained in animals and in vitro models are also discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Bisphenol A (BPA) hazard assessment protocol
No full textTo ensure an efficient, transparent and methodologically rigorous re-assessment of the safety for consumers of bisphenol A (BPA), the European Food Safety Authority (EFSA) has undertaken the task to develop a protocol detailing a priori the approach and methodology for performing BPA hazard identification and characterisation. The general aim of this hazard assessment will be to assess whether the new scientific evidence (published from 2013 onwards and not previously appraised by EFSA) still supports the current temporary Tolerable Daily Intake (t-TDI) for BPA of 4 µg/kg bw per day. In line with the principles highlighted in the EFSA project PROmoting METHods for Evidence Use in scientific assessments (PROMETHEUS, https://www.efsa.europa.eu/en/efsajournal/pub/4121), the protocol states upfront and in detail the methods and/or the criteria that will be used in the planned BPA re-evaluation for data collection, study inclusion, evidence appraisal and integration. To pursue the goal of openness, this protocol was subjected to a web-based public consultation and was presented publicly in a stakeholder event. All the relevant comments and feedback received through these procedures were considered
Cardiac damage in pediatric carbon monoxide poisoning
No full textBACKGROUND: Cardiovascular disorders including myocardial ischemia and heart failure have been described in both laboratory animals and humans following carbon monoxide poisoning. Carbon monoxide cardiotoxicity may be clinically occult and often remains undiagnosed because of the lack of overt symptoms and specific ischemic changes in the electrocardiogram. Routine myocardial necrosis markers have low diagnostic efficiency, particularly in patients with concomitant skeletal muscle necrosis or multiple organ failure complicating carbon monoxide poisoning. Carbon monoxide-induced cardiotoxicity has been investigated rarely in children. CASE REPORT: This paper describes carbon monoxide poisoning in a 12-year-old child who suffered from occult cardiac damage despite mild symptoms and low carboxy hemoglobin concentrations. Myocardial and mitral valve dysfunctions were observed, suggesting an ischemia-like syndrome. Cardiac damage was completely reversible within 1 month. CONCLUSION: This case report supports that a prolonged carbon monoxide exposure can cause cardiac damage in children even in the absence of specific symptoms, cerebral failure and high carboxyhemoglobin concentrations
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Cardiotoxic effects of moderate acute carbon monoxide poisoning in the rabbit
No full textThe study shows that even moderate CO poisoning can produce heart damage in the rabbit as demonstrated by long lasting alterations in myocardial metabolism and acute blood levels increase of necrosis markers
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