Marine mammals from northeast Atlantic: relationship between their trophic status as determined by delta13C and delta15N measurements and their trace metal concentrations.

The relationship between trophic position through delta13C and delta15N and trace metal concentrations (Zn, Cd, Cu and Hg) was investigated in the tissues of six marine mammal species from the Northeast Atlantic: striped dolphin Stenella coeruleoalba, common dolphin, Delphinus delphis, Atlantic white-sided dolphin Lagenorhynchus acutus, harbour porpoise Phocoena phocoena, white beaked-dolphin Lagenorhynchus albirostris, grey seal Halichoerus grypus stranded on French Channel and Irish coasts. White-beaked dolphins, harbour porpoises, white-sided dolphins, common and striped dolphins display the same relative and decreasing trophic position, as measured by delta15N values, along both the Irish and French channel coasts, reflecting conservative trophic habits between these two places. Hepatic and renal Cd concentrations were significantly correlated to muscle delta13C and delta15N values while Hg, Zn and Cu did not. These results suggest that Cd accumulation is partly linked to the diet while other factors such as age or body condition might explain Hg, Zn or Cu variability in marine mammals. Combined stable isotope and trace metal analyses appear to be useful tools for the study of marine mammal ecology.

The potential of the beta-Microprobe, an intracerebral radiosensitive probe, to monitor the [(18)F]MPPF binding in the rat dorsal raphe nucleus.

The aim of this study was to demonstrate the ability of a recently developed beta(+)-range sensitive intracerebral probe (beta-Microprobe) to measure the binding kinetics of [(18)F]MPPF, a well-documented 5-HT(1A) serotoninergic receptor ligand, in the dorsal raphe nucleus (DRN) of the anaesthetised rat. This midbrain nucleus presents a high concentration of 5-HT(1A) receptors known to be implicated in the effects of antidepressants. The difficulty confronting this study lay in the fact that the dimensions of the DRN are smaller than the detection volume of the beta-Microprobe. In the first part of the study, we studied the feasibility of this measurement from a theoretical point of view by autoradiography and a Monte Carlo simulation. We determined the optimal beta-Microprobe location close to the DRN and verified that this configuration allowed accurate determination of [(18)F]MPPF specific binding in the nucleus. In the second part of our study, we measured the in vivo time-concentration curves of [(18)F]MPPF binding in the DRN in comparison with the cerebellum. The specificity of [(18)F]MPPF binding in the DRN was confirmed by its displacement after non-labelled 5-HT(1A)antagonist injection (MPPF or WAY-100635). Moreover, we verified the feasibility of using beta-Microprobe monitoring and simultaneous validation by microdialysis to study the effect of an increase in extracellular serotonin, induced by fenfluramine injection, on [(18)F]MPPF binding in the DRN. Our theoretical simulations, confirmed by our experimental results, demonstrate the ability of this new device to monitor in vivo the binding of [(18)F]MPPF in the DRN of anaesthetised rodents.

The unstable urethra in the female.

The clinical and urodynamic characteristics of 54 women with unstable urethras (falls of urethral pressures of at least 20 cm H2O) were compared with those of 171 patients with stable urethras. The unstable-urethra patients were younger and presented with an increased incidence of marked urgency and a lower incidence of genuine stress incontinence. The average urethral pressure fall was preceded by a 6-cm increase in maximum urethral pressure. The mean (+/- SD) fall of urethral pressure was 30 +/- 12 cm H2O and the average duration of the event was 8 seconds. The level of the urethral pressure fall was not influenced by bladder volume but correlated positively with higher maximum urethral pressures. The present findings suggest that the unstable urethra plays a limited role in genuine stress incontinence but may be linked with the unstable detrusor.

Diagnosis of the unstable detrusor: comparison of an incremental and continuous infusion technique.

Incremental infusion cystometry and continuous infusion urethrocystometry were performed on sequential days in 52 patients with an unstable detrusor. Bladder compliance was the same in both techniques. However, continuous infusion urethrocystometry demonstrated involuntary detrusor contractions in three times as many patients as incremental infusion cystometry. It is concluded that in the supine position, medium rate continuous infusion urethrocystometry is more discriminating than rapid rate incremental infusion cystometry with a Lewis recording cystometer in the demonstration of involuntary detrusor contractions.