Developmental toxicity of combined ethylbenzene and methylethylketone administered by inhalation to rats

Pregnant Sprague–Dawley rats were exposed to ethylbenzene (EB; 0, 250, or 1000 ppm) and methylethylketone (MEK; 0, 1000, or 3000 ppm), alone and in combination, by inhalation, for 6 h/day, during days 6–20 of gestation. Maternal toxicity, evidenced by decreased in body weight gain and food consumption, tended to be greater after simultaneous exposures to the high concentrations of 1000 ppm EB and 3000 ppm MEK, when compared to the treatments with individual compounds. No significant increase in embryo/fetal lethality or incidence of malformations and variations was observed in any of the treatment groups. Fetal body weight was significantly reduced after individual treatment with 1000 ppm EB or 3000 ppm MEK, and in the combined groups. There was no evidence of interaction between EB and MEK in causing developmental toxicity

Genesis of self-organized zebra textures in burial dolomites: Displacive veins, induced stress, and dolomitization

The dolomite veins making up rhythmites common in burial dolomites are not cement infillings of supposed cavities, as in the prevailing view, but are instead displacive veins, veins that pushed aside the host dolostone as they grew. Evidence that the veins are displacive includes a) small transform-fault-like displacements that could not have taken place if the veins were passive cements, and b) stylolites in host rock that formed as the veins grew in order to compensate for the volume added by the veins. Each zebra vein consists of crystals that grow inward from both sides, and displaces its walls via the local induced stress generated by the crystal growth itself. The petrographic criterion used in recent literature to interpret zebra veins in dolomites as cements - namely, that euhedral crystals can grow only in a prior void - disregards evidence to the contrary. The idea that flat voids did form in dolostones is incompatible with the observed optical continuity between the saddle dolomite euhedra of a vein and the replacive dolomite crystals of the host. The induced stress is also the key to the self-organization of zebra veins: In a set of many incipient, randomly-spaced, parallel veins just starting to grow in a host dolostone, each vein¿s induced stress prevents too-close neighbor veins from nucleating, or redissolves them by pressure-solution. The veins that survive this triage are those just outside their neighbors¿s induced stress haloes, now forming a set of equidistant veins, as observed

Antiplatelet and anticoagulant therapy after coronary-artery stenting

To the Editor: Schömig et al. (April 25 issue) report that they did not observe neutropenia in any of the 257 patients receiving short-term ticlopidine therapy after coronary stenting

Tourmaline records the hydrothermal events related to Zn-Pb mineralization around the Murguía diapir (Basque Cantabrian Basin, N Spain)

The chemical composition of tourmaline has been used as a host environment register as well as a potential exploration tool for mineral deposits. In this study, the textural and chemical composition of tourmalines associated with Zn-Pb mineralizations around the Murguía diapir (Basque Cantabrian Basin, N Spain) are examined to verify if they record the mineralizing events in the area. Petrographically, tourmalines have been differentiated between inherited and authigenic. Colorless authigenic tourmalines are present as halos partially around green and pleochroic detrital grains or as individual crystals. Inherited and authigenic tourmalines are also chemically distinct. Authigenic tourmalines show different X-site occupancies, a Mg/(Mg+Fe) ratio above 0.77, and are aluminum rich and plot to the right of the povondraite-oxidravite join, above the schorl-dravite join. Inherited tourmalines plot within the alkaline (Na+K) group field, and have a Mg/(Mg+Fe) ratio below 0.77. These data suggest that authigenic tourmalines grew under reducing conditions, compatible with the hydrothermal event responsible for the ore deposition and caprock formation during the diapir ascent

Use of environmental isotopes (13C, 15N, and 18O) for evaluating sources and fate of nitrate and tetrachloroethene in an alluvial aquifer

Environmental isotopes and geochemical parameters were used to evaluate the sources and fate of nitrate (NO3-) and tetrachloroethene (PCE) in an alluvial contaminated aquifer. Isotope data and redox parameters data indicated that biodegradation does not play any role in the attenuation of these compounds along the groundwater flow system. Furthermore, nitrate isotopes and concentration data allowed the authors to distinguish two nitrate inputs and relate them to their possible sources. The primary source originates from septic waste and the secondary source is associated with nitrogenous fertilizer application. Regarding PCE, the δ13C values do not change for almost 1000 m along the groundwater flow system despite large decreases of PCE concentration, thus confirming that physical processes do not alter the isotopic composition of organic compounds; this finding has a significant implication for the use of carbon isotope ratios for fingerprinting sources of PCE in VOC plumes. This study has shown that combined use of environmental isotopes and geochemical parameters is an efficient approach for water resource management studies in sites polluted by various types of contaminants

Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO2 and water fluxes through combined in situ measurements and ecosystem modelling

Water stress is a defining characteristic of Mediterranean ecosystems, and is likely to become more severe in the coming decades. Simulation models are key tools for making predictions, but our current understanding of how soil moisture controls ecosystem functioning is not sufficient to adequately constrain parameterisations. Canopy-scale flux data from four forest ecosystems with Mediterranean-type climates were used in order to analyse the physiological controls on carbon and water flues through the year. Significant non-stomatal limitations on photosynthesis were detected, along with lesser changes in the conductance-assimilation relationship. New model parameterisations were derived and implemented in two contrasting modelling approaches. The effectiveness of two models, one a dynamic global vegetation model ('ORCHIDEE'), and the other a forest growth model particularly developed for Mediterranean simulations ('GOTILWA+'), was assessed and modelled canopy responses to seasonal changes in soil moisture were analysed in comparison with in situ flux measurements. In contrast to commonly held assumptions, we find that changing the ratio of conductance to assimilation under natural, seasonally-developing, soil moisture stress is not sufficient to reproduce forest canopy CO2 and water fluxes. However, accurate predictions of both CO2 and water fluxes under all soil moisture levels encountered in the field are obtained if photosynthetic capacity is assumed to vary with soil moisture. This new parameterisation has important consequences for simulated responses of carbon and water fluxes to seasonal soil moisture stress, and should greatly improve our ability to anticipate future impacts of climate changes on the functioning of ecosystems in Mediterranean-type climates

Cephalosporin-resistant Escherichia coli among Summer Camp Attendees with Salmonellosis

Investigation of an acute gastroenteritis outbreak involving >100 persons at a summer camp in Girona, Spain, in June 2002 led to the detection of Salmonella and extended-spectrum cephalosporin-resistant Escherichia coli (ESCREC). Stool cultures were performed for 22 symptomatic campers, three asymptomatic food handlers, and 10 healthy household members. Of the 22 campers, 19 had Salmonella enterica, 9 had an ESCREC strain carrying an extended-spectrum β-lactamase, and 2 had a second ESCREC strain carrying a plasmidic cephamycinase. Related ESCREC were detected in two (salmonella-negative) asymptomatic food handlers and in none of the healthy household members. Fecal ESCREC and its β-lactamases and plasmids were extensively characterized. Three of the five ESCREC clones were recovered from multiple hosts. The apparent dissemination of ESCREC suggests a food or water vehicle. The observed distribution of resistance plasmids and β-lactamase genes in several clones indicates a high degree of horizontal transfer. Heightened vigilance and increased efforts must be made to discover the reservoirs and vehicles for community dissemination of ESCREC

Aortic perforation by active-fixation atrial pacing lead: an unusual but serious complication

Perforation of a cardiac chamber is an infrequent but serious sequela of pacemaker lead implantation. An even rarer event is the perforation of the aorta by a protruding right atrial wire. We present here the first case in the medical literature of aortic perforation as a sequela to the implantation of a cardiac resynchronization therapy defibrillator. The patient was a 54-year-old man with idiopathic dilated cardiomyopathy who underwent the implantation of a defibrillator, with no apparent sequelae. Six hours after the procedure, he experienced cardiac tamponade and required urgent open-chest surgery. The pericardial effusion was found to be caused by mechanical friction of a protruding right atrial wire on the aortic root. The aortic root and the atrial wall were both repaired with Prolene suture, which achieved complete control of the bleeding. There was no need to reposition the atrial wire. The patient had a good postoperative recovery

Tractament de les coxitis reumàtiques amb pròtesi total

La nostra experiència quirúrgica en el tractament de les coxitis reumàtiques es fonamenta en una sèrie de 37 malalts dels quals 33 patien l'afectació bilateral; sumen un total de 70 anques reumàtiques. Foren operats amb pròtesi total tots 37 malalts i 11 d'ells la reberen bilateral: tenim, dones, 48 pròtesis..