Propranolol in conscious spontaneously hypertensive rats

The disposition of dl-propranolol was studied in spontaneously hypertensive rats (SHR), both after subcutaneous (s.c.) and intracerebroventricular (i.c.v.) injection of 1 mg/kg. 1. Upon s.c. injection propranolol appeared rapidly in plasma. A maximum concentration of 374 +/- 33 ng/ml (N = 10) was reached 5 min after injection. After a distribution phase with a half-life of t 1/2 alpha = 17 min propranolol was eliminated with a t 1/2 beta = 59 min. 2. Both propranolol and its metabolites were taken up rapidly into all tissues studied. Highest concentrations (10.4 +/- 1.5 micrograms/g, N = 5) were found in lungs 30 min after injection. 3. Neither propranolol nor its metabolites accumulated in any of the tissues examined. 4. Upon i.c.v. injection of propranolol, a maximal concentration of 573 +/- 47 ng/ml (N = 3) was reached in plasma already 2 min after injection. In this case t 1/2 alpha was 13 min and t 1/2 beta was 80 min. 5. Dialysis experiments indicated that propranolol is bound to plasma proteins for 92% in the concentration range of 20--100 ng/ml. With increasing concentrations binding diminishes progressively. At the highest concentration tested (345 ng/ml) only 76% was bound. It is concluded that s.c. and i.c.v. injection of an identical dose of propranolol gives a similar plasma concentration-time profile. Moreover, it is suggested that the pharmacokinetic behaviour of propranolol in SHR does not explain the delayed antihypertensive effect of this drug.     

Impact of oil-sands based wetlands on the growth of mallard (Anas platyrhynchos) ducklings

Identifying the potential effects of industrially formed wetlands on waterfowl populations is important for assessing the suitability of such wetlands in industrial reclamation strategies. Mallard ducklings were held in situ on two industrially formed wetlands and one reference wetland in northern Alberta, Canada. Duckling mass and skeletal size were measured at regular intervals over 33 d, and blood was collected to investigate the analysis of plasma metabolites (triglyceride and glycerol) as an indicator of physiological condition. In repeated-measures analysis of variance (ANOVA), multivariate ANOVA, and subsequent multiple-comparisons tests, body mass and skeletal size were significantly lower in ducklings maintained on the industrial wetland after 2, 5, 9, and 13 d of exposure. In this situation, plasma metabolite analysis did not provide additional information on mass-independent condition. We conclude that if the observed differences in growth and size translate into a decreased survival of juvenile waterfowl inhabiting these wetlands, then populations of these birds in the area could be negatively affected. We emphasize the importance of field-based ecological research in toxicological studies of wildlife.     

Spatial, temporal, and dietary determinants of organic contaminants in nestling tree swallows in Point Pelee National Park, Ontario, Canada

Point Pelee National Park of Canada in southwestern Ontario, an important migratory route and vital breeding area for many birds, has localized areas of organochlorine (OC) pesticide contamination from agricultural production during the 1950s and 1960s. During 2001 and 2002, we investigated movement of persistent contaminants through the food web with the insectivorous tree swallow (Tachycineta bicolor) as a sentinel. The a priori site classifications, contaminated or reference, were based on soil residues of dichlorodiphenyltrichloroethane (DDT) and its breakdown products (sigmaDDT), dieldrin, and other OC pesticides. In 2001, all nestling tissue samples were pooled by site, and residue levels did not reflect the soil contaminant status. To improve sampling accuracy in 2002, tissue residues were determined from birds in individual nests. This showed OC pesticides to be higher in samples from contaminated sites compared with reference sites (p = 0.031). Polychlorinated biphenyls (PCBs), which were not detected in soil samples, were present in the nestlings and were not related to site of origin (p = 0.422). In 2002, dietary samples were collected from nestlings and identified to taxon, and representative insects collected from nesting sites were analyzed for PCBs and other OCs. Consumption of terrestrial prey was positively correlated with tissue residues of sigmaDDT (p = 0.006), whereas PCBs came from aquatic prey, Hexagenia mayflies (p = 0.003). Dietary details proved valuable in this study of contaminant transfer in insectivorous vertebrates.     

External validation of the Canadian CT Head Rule and the New Orleans Criteria for CT scanning in patients with minor head injury

Context  Two decision rules for indications of computed tomography (CT) in patients with minor head injury, the Canadian CT Head Rule (CCHR) and the New Orleans Criteria (NOC), suggest that CT scanning may be restricted to patients with certain risk factors, which would lead to important reductions in the use of CT scans. Objective  To validate and compare these 2 published decision rules in Dutch patients with head injuries. Design, Setting, and Patients  A prospective multicenter study conducted between February 11, 2002, and August 31, 2004, in 4 university hospitals in the Netherlands of 3181 consecutive adult patients with minor head injury who presented with a Glasgow Coma Scale (GCS) score of 13 to 14 or with a GCS score of 15 and at least 1 risk factor. Main Outcome Measures  Primary outcome was any neurocranial traumatic finding on CT scan. Secondary outcomes were neurosurgical intervention and clinically important CT findings. Sensitivity and specificity were estimated for each outcome for the CCHR and the NOC, using both rules as originally derived and also as adapted to apply to an expanded patient population. Results  Of 3181 patients with a GCS score of 13 to 15, neurosurgical intervention was performed in 17 patients (0.5%); neurocranial traumatic CT findings were present in 312 patients (9.8%). Sensitivity for neurosurgical intervention was 100% for both the CCHR and the NOC. The NOC had a higher sensitivity for neurocranial traumatic findings and for clinically important findings (97.7%-99.4%) than did the CCHR (83.4%-87.2%). Specificities were very low for the NOC (3.0%-5.6%) and higher for the CCHR (37.2%-39.7%). The estimated potential reduction in CT scans for patients with minor head injury would be 3.0% for the adapted NOC and 37.3% for the adapted CCHR. Conclusions  For patients with minor head injury and a GCS score of 13 to 15, the CCHR has a lower sensitivity than the NOC for neurocranial traumatic or clinically important CT findings, but would identify all cases requiring neurosurgical intervention, and has greater potential for reducing the use of CT scans.