Analysis of trichothecenes in laboratory rat feed by gas chromatography-tandem mass spectrometry

A method for the determination of seven trichothecenes, neosolaniol (NEO), diacetoxyscirpenol (DAS), deoxynivalenol (DON), nivalenol (NIV), fusarenon-X (FUS-X), 3-acetyldeoxynivalenol (3-ADON) and 15-acetyldeoxynivalenol (15-ADON), in laboratory rat feed by GC-MS/MS was developed. Sample extraction and purification was performed by an acidified mixture of acetonitrile/water (80–20% v/v). Limits of quantitation (LOQs) were between 1 and 10 μg kg^–1 for all studied trichothecenes. Eight concentration levels between the LOQ and 100 × LOQ were used for the calibration curves. Matrix-matched calibration was used for quantitation purposes to compensate the detector signal enhancement obtained for all the analytes. The method accuracy was evaluated by recovery assays at three concentration levels, 25, 50 and 100 μg kg^–1 (n = 9). Recoveries ranged from 62% to 97% and precision, expressed as intra- and inter-day relative standard deviations, was evaluated for all compounds. The validated method was successfully applied to the analysis of 35 laboratory rat feed samples showing mycotoxin contamination in 66% of the samples. DON was the most prevalent trichothecene followed by 15-ADON, NIV and 3-ADON. The maximum DON concentration reached in real samples was 2156 ± 4.3 μg kg^–1, while NEO, DAS and FUS-X were not detected in any sample. Multi-contamination by at least two mycotoxins was observed in 17% of the analysed feed samples.     

New evidence on imitation in an enculturated chimpanzee (Pan troglodytes).

Imitation in the great apes continues to be an active field of research and one that is not free of controversy. Several studies suggest that these species do not tend to match the motor movements of the model they observe, but try to achieve the same results using their own methods (emulation of results). In the studies reviewed, gestures have been used very infrequently outside an intraspecific communicative context to evaluate imitation. In fact, the imitation of gestural actions has been tested only in 4 individual great apes. This study assessed a chimpanzee’s (Pan troglodytes) ability to imitate 52 actions in 4 categories. The levels of accuracy attained by the subject in her imitations exceeded those described in previous studies. Moreover, contrary to the idea defended in some articles, the subject seemed to find it easier to imitate gestures than actions with objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychosocial predictors of the short-term course and outcome of major depression: A longitudinal study of a nonclinical sample with recent-onset episodes.

Three variables have been hypothesized to play important roles in prolonging the course of depressive episodes: a ruminative response style, significant interpersonal relationships, and childhood adversity. The authors examined whether these variables predicted the short-term course of major depressive disorder (MDD). Participants (n/&=/&84) were college students with a recent-onset major depressive episode. Assessments included several interview and self-report measures, and data on interpersonal relationships were obtained from close confidants. Follow-up interviews were conducted 6 mo later. After controlling for baseline severity, harsh discipline in childhood significantly predicted mean level of depression across the follow-up and level of depression at follow-up. Harsh discipline was also significantly associated with relapse but not with recovery. After controlling for baseline severity, rumination and the interpersonal variables did not predict the outcome of MDD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of ozone on nicotine desorption from model surfaces: evidence for heterogeneous chemistry

Assessment of secondhand tobacco smoke exposure using nicotine as a tracer or biomarker is affected by sorption of the alkaloid to indoor surfaces and by its long-term re-emission into the gas phase. However, surface chemical interactions of nicotine have not been sufficiently characterized. Here, the reaction of ozone with nicotine sorbed to Teflon and cotton surfaces was investigated in an environmental chamber by monitoring nicotine desorption over a week following equilibration in dry or humid air (approximately 0% or 65-70% RH, respectively). The Teflon and cotton surfaces had N2-BET surface areas of 0.19 and 1.17 m2 g(-1), and water mass uptakes (at 70% RH) of 0 and 7.1% respectively. Compared with dry air baseline levels in the absence of O3, gas-phase nicotine concentrations decreased by 2 orders of magnitude for Teflon after 50 h at 20-45 ppb O3, and by a factor of 10 for cotton after 100 h with 13-15 ppb O3. The ratios of pseudo first-order rate constants for surface reaction (r) to long-term desorption (k) were r/k = 3.5 and 2.0 for Teflon and cotton surfaces, respectively. These results show that surface oxidation was competitive with desorption. Hence, oxidative losses could significantly reduce long-term re-emissions of nicotine from indoor surfaces. Formaldehyde, N-methylformamide, nicotinaldehyde, and cotinine were identified as oxidation products, indicating that the pyrrolidinic N was the site of electrophilic attack by O3. The presence of water vapor had no effect on the nicotine-O3 reaction on Teflon surfaces. By contrast, nicotine desorption from cotton in humid air was unaffected by the presence of ozone. These observations are consistent with complete inhibition of ozone-nicotine surface reactions in an aqueous surface film present in cotton but not in Teflon surfaces.     

Evidence of uranium and associated trace element mobilization and retention processes at Oklo (Gabon), a naturally radioactive site

The processes that affect the mobility of uranium and other radionuclides in the environment have been largely studied at both the laboratory and the field scales. The natural reactors found at the Oklo uranium mine in Gabon constitute a unique investigation setting as spontaneous fission reactions occurred two billion years ago. Oklo uraninites contain a large amount of other radionuclides as a result of the fission process. We have investigated the dissolution behavior of four uraninite samples from Oklo as a function of temperature (25 and 60 degrees C) and bicarbonate concentration (2.7-30 mmol/L). We have also investigated the dissolution behavior of minor components of the uraninites (i.e., Nd, Cs, Mo, Yb, and Sb) in relation to the dissolution of uranium. The results of the reported work are in good agreement with the kinetic rate laws derived from other uranium(IV) dioxide studies. Some of the minor components are found to be congruently released from the uraninite phase, while it is postulated that dissolution from segregated phases might affect the final concentrations of some of the rare earth elements, i.e., Nd and Yb. In addition, we have performed dissolution studies at 60 degrees C with two uraninites representative of different geochemical environments at Oklo, to study the uranium dissolution rates as a function of the temperature. This has allowed derivation of apparent activation energies for the bicarbonate-promoted oxidative dissolution of the Oklo uraninites. The dissolution behavior of the minor components of the uraninites at 60 degrees C was found to closely follow the behavior observed at 25 degrees C. This indicates that similar codissolution mechanisms operate in the temperature range studied. The implications for the mobility of uranium and other radionuclides in natural and anthropogenic environments are discussed.     

Massive tumorous pulmonary embolism in hepatocarcinoma

Tumoral pulmonary embolism is among the causes of acute dyspnea in patients with neoplasia. This phenomenon, different to thrombotic embolism, occurs frequently in patients with lung, gastrointestinal, liver, breast and uterus neoplasia. It is usually asymptomatic and usually constitutes an autopsy finding in these patients. More rarely it manifests as a cor pulmonale which evolves subacutely. Exceptionally large tumoral emboli spread from a primary tumoral mass, and obstruct main pulmonary arterial vessels, causing a clinical picture indistinguishable from massive pulmonary thromboembolism. We present case of massive tumoral pulmonary embolism by an hepatocarcinoma. In spite of an early thrombolytic treatment the patient died from acute pulmonary hypertension.     

The federal health expenditure on the uninsured population: Mexico 1980-1995

An analysis of three-dimensional movement of the mitral valve annulus (MVA) may address the question of geometrical change after mitral valve repair to preserve mitral annular function. Conventionally, annular contraction has been studied for this purpose. We investigated this geometrical change occurring in the anterior half of the MVA and discuss its clinical significance. Three-dimensional images of the MVA during systole were reconstructed from magnetic resonance images of eight normal subjects. The posterior half of the MVA exhibited translational motion. We assume that this portion, exhibiting translational motion as well as contraction, purely follows the motion of the left ventricular contraction. Compensating for the discrepancy between the motion of the aortic root and that of the posterior half of the MVA, the anterior half exhibited a flexible change in shape during systole, thus maintaining a sufficient left ventricular outflow tract (LVOT). The increase in the extent of displacement of the anterior MVA from the posterior half of the MVA during systole, which was 3.6 +/- 1.0 mm (mean +/- SD), indicates the annular flexibility. The preservation of annular flexibility may prevent LVOT obstruction. Further geometrical analysis of patients after mitral repair will clarify annular function as presented in this article.