Trace metals in ambient air: Hourly size-segregated mass concentrations determined by synchrotron-XRF

Trace metals are ubiquitous in urban ambient air, with mass concentrations in the range of a few microg/m3 down to less than 100 pg/m3. To measure such low concentrations represents a challenge for chemical and physical analysis. In this study, ambient aerosol was collected in Zürich (Switzerland) in 1-h intervals and three size fractions (aerodynamic diameters 0.1-1 microm, 1-2.5 microm, and 2.5-10 microm), using a three-stage rotating drum impactor (RDI). The samples were analyzed by energy-dispersive Synchrotron radiation X-ray fluorescence spectrometry (SR-XRF) to obtain size-segregated hourly elemental aerosol mass concentrations for Cr, Mn, Fe, Cu, Zn, Br, and Pb, along with S, Cl, and Ca under the selected experimental conditions. The high sensitivity of SR-XRF allowed for detection limits of <50 pg/m3 for most of the above elements, with a net analysis time of only 15 s per sample. The data obtained with this technique illustrate that there is a considerable gain of relevant information when time resolution for measurements is increased from 1 day to 1 h. The individual size fractions of a specific element may show significantly different short-term patterns.     

Growth dilution of metals in microalgal biofilms

Despite the key role microalgae play in introducing toxicants into aquatic food webs, little is known about the effects of environmental factors on metal accumulation by these primary producers. Environmental factors such as light and nutrients alter growth rates and may consequently influence metal concentrations in microalgae through growth dilution. Laboratory experiments suggested that metal uptake and elimination by microalgal biofilms were gradual enough to enable dilution of metals within the biofilms by photosynthetically accrued carbon, and a simple kinetic model of metal accumulation predicted significant variation in metal content due to growth dilution over the natural range of microalgal growth rates. The ratio of metal uptake to carbon uptake by microalgal biofilms decreased exponentially with increasing light in short-term laboratory experiments because photosynthesis was much more sensitive to a light gradient than was metal uptake. The effect of light on biofilm metal concentrations was confirmed in situ with a long-term experiment in which experimental shading of biofilms in a metal-contaminated stream decreased biofilm growth rates and caused a 3x increase in biofilm concentrations of twelve metals, including methylmercury. Slow growth at the primary producer level is a likely contributor to higher biotic metal concentrations in shaded, oligotrophic, or cold ecosystems.     

The lantibiotic lacticin 3147 produced in a milk-based medium improves the efficacy of a bismuth-based teat seal in cattle deliberately infected with Staphylococcus aureus

A preparation of the bacteriocin lacticin 3147 (prepared from a demineralized whey protein fermentation liquor) was combined as a powder with a bismuth-based intramammary teat seal and evaluated for its potential as an antimicrobial in non-lactating cows. The lacticin/teat seal formulation enabled significant bacteriocin release from the seal without the requirement for a surfactant. Studies in vivo in lactating cows demonstrated that this formulation was effective in reducing bacterial recoveries (approximately 20-fold) from teats deliberately inoculated with Staphylococcus aureus after infusion. Moreover, this formulation also significantly reduced the numbers of Staph. aureus recovered from teats that were exposed to the challenge bacterium before the infusion of the teat seal preparation. The powdered preparation of lacticin 3147 did, however, cause some teat irritation as evidenced by associated rises in somatic cell count (SCC). However, this effect was short-lived and when the mean SCC readings pre-infusion and the final two readings post-infusion were compared, there was no significant difference in the immunological acceptance between treatments.     

Catamnestic studies on the prodomal phase of myocardial infarct

In a retrospective study by means of a half-standardized method of interview in 154 patients with acute myocardial infarction and in a control group of the same age (n = 100) anamnestic data were established, particularly taking into consideration the preinfarction phase. 27% of the patients were surprised by an acute myocardial infarction without prodromal symptoms, in 32% the first occurrence of complaints of angina pectoris was during the last two months before the infarction. 41% had a preexisting angina pectoris which usually showed a crescendo-course with increasing approximation to the infarction. More than half of the patients reported on physical activity or/and emotional stress as causal factors of the preinfarction complaints. The correlation with the localisation of the infarction showed above all an occurrence of the prodromal symptoms in infarctions of the anterior wall and in lesions of the myocardium which in most cases could be ascertained only enzymatically. A greater accumulation of the prodromi was furthermore found in younger patients, in hypertension and preexisting restriction of the heart function. 70% of the patients with warning symptoms consulted a physician because of their heart complaints. In the control group 22% of the persons reported on heart complaints.     

Absorption and distribution studies on chlorinated oleic acid and extracts of chlorinated lipid and protein fractions of flour in rats

Fourty-five reconstructions of the profunda femoris artery were performed in 41 patients during the period from 1972 to 1974. 78% were operated upon for pain at rest or distal gangrene. Three patients died postoperatively and in 5 cases the reconstruction failed to save the limb. In 1 additional case the operation probably lowered the amputation level to below knee. There was only 1 late occlusion. In the present material profundaplasty alone or combined with iliac reconstruction could relieve rest pain and save limbs when no other possibilities except amputation existed. However, when significant obstruction of the profounda femoris artery is demonsrated by angiography, profundaplasty should probably be perferred to femoro-popliteal reconstruction in most cases since it represents a minor operation with encouraging long-term results. Lateral angiograms of the deep femoral artery should supplement conventional angiography or lower limb atherosclerosis.     

Effects of hypoxia on the hemodynamic actions of prostaglandin E1

The effect of prostaglandin E1 (PGE1) on central and peripheral hemodynamics was studied in seven conscious dogs under conditions of normoxia and hypobaric hypoxia to ascertain if hypoxia attenuated the cardiovascular actions of PGE1. Silastic catheters were chronically implanted in the pulmonary artery, left atrium, and aorta. Acute hypoxia was produced in a hypobaric chamber maintained at 446 mmHg pressure (14,000 feet). PGE1 at sea level (normoxia) resulted in significant increases in heart rate, cardiac output, left ventricular stroke work and pulmonary blood volume as well as significant decreases in aortic, pulmonary arterial, and left atrial pressures. During hypobaric hypoxia, PGE1 produced essentially identical effects on all hemodynamic parameters except pulmonary blood volume and pulmonary arterial pressure where marked attenuation of PGE1 action occurred.