Significant Change in Marine Plankton Structure and Carbon Production After the Addition of River Water in a Mesocosm Experiment.

Rivers are known to be major contributors to eutrophication in marine coastal waters, but little is known on the short-term impact of freshwater surges on the structure and functioning of the marine plankton community. The effect of adding river water, reducing the salinity by 15 and 30%, on an autumn plankton community in a Mediterranean coastal lagoon (Thau Lagoon, France) was determined during a 6-day mesocosm experiment. Adding river water brought not only nutrients but also chlorophyceans that did not survive in the brackish mesocosm waters. The addition of water led to initial increases (days 1-2) in bacterial production as well as increases in the abundances of bacterioplankton and picoeukaryotes. After day 3, the increases were more significant for diatoms and dinoflagellates that were already present in the Thau Lagoon water (mainly Pseudo-nitzschia spp. group delicatissima and Prorocentrum triestinum) and other larger organisms (tintinnids, rotifers). At the same time, the abundances of bacterioplankton, cyanobacteria, and picoeukaryote fell, some nutrients (NH4+, SiO43-) returned to pre-input levels, and the plankton structure moved from a trophic food web based on secondary production to the accumulation of primary producers in the mesocosms with added river water. Our results also show that, after freshwater inputs, there is rapid emergence of plankton species that are potentially harmful to living organisms. This suggests that flash flood events may lead to sanitary issues, other than pathogens, in exploited marine areas.

[Utilization of a self-contained psychometry-oriented device, for study of affective and cognitive function of a subject]. / Utilisation d'un appareil autonome de psychométrie pour l'étude des fonctions affectives et cognitives d'un sujet.

We appraised the possibility to use the Psycho-Log 24, an ambulatory, adapted to chronopsychometry device, which realizes simplified questionnaires and performance test adaptable to each subject; this device has dimensions like a pocketbook; its storage capacity is compatible with a long time use. 9 adult volunteers (8 healthy subjects and 1 depressive patient) participated to this study. All of them effected reaction times (TRS) during 3 to 31 days at the rate of at least 4 sessions/day; some of them completed mental calculations (CM), letters cancellations (BRL) and auto-estimation scales (from 1 to 9 items, also measured by a classic method). For TRS and all the subjects, the frequencies histograms calculated by hour and on a 24 h scale, showed a bimodal variation, with a major peak suggesting a circadian rhythm. 5 subjects had different time for the daily best performances of each hand (shifted from 5 to 12 h). In the healthy adults, for BRL and CM, the best performances in speed and precision are shifted and could be related to the "fatigue" auto-estimated peaks. There is a significant correlation between auto-estimations by Psycho-Log and the classic method. The coherence between the auto-estimations of the depressive subject is strong during the remission stage, and lower during the relapse stage. The used method seems an effective mean to know the temporal structure of the cognitive and affective functions of a subject, and to estimate the preserving of this structure; the method first could constitute an exploratory mean for an objective evaluation of the drugs effects and patients quality of life, secondly could be implicated in researches with diagnosis target.

Circadian rhythm period in reaction time to light signals: difference between right- and left-hand side.

The study was designed to test the hypothesis that the prominent rhythm period tau of simple reaction time (SRT) and three-choice reaction time (CRT) to light signals may vary between the dominant (DH) and non-dominant (NDH) hand. Eleven healthy subjects, 8 males (16-74 years, including two left-handed) and 3 females (18-43 years), synchronized with a diurnal activity (approximately 07.00 h to approximately 23.00 h) and a nocturnal rest, volunteered for the study. A battery-powered ambulatory device was used to self-record SRT to a yellow light signal and CRT to yellow, green and red signals. Tests were performed 4-7 times/24 h during a 12- to 15-day span. Power spectra, ANOVA, cosinor, chi2 and correlation tests were used to individually analyze time series. Tau = 24 h in SRT rhythms of DH (8/11 cases) and NDH (6/11 cases) with chi2 = 3.5 and p > 0.05. In CRT rhythms, tau = 24 h for DH (8/11 cases) while tau = 8 h for NDH (7/11 cases), a difference which was statistically significant (chi2 = 9.4 with p < 0.02). Concordant results were obtained with other statistical tests leading to the conclusion that the rather complex cognitive task (CRT) and, to a certain extent, SRT of certain individuals, were associated with tau = 24 h for DH and tau = 8 h for NDH. These findings are in favor of the hypothesis that functional clocks are present in the human brain cortex, associated with the possible expression of rhythms with a prominent period differing from the right- and left-hand side.

[Validation of a new interactive software monitoring a controlled-flow infusion pump for cisplatin dosage regimen adjustment]. / Validation d'un nouveau logiciel interactif intégré à une pompe à débit contrlé et permettant l'adjustement de posologie du cisplatine en temps réel.

Adaptive dosing of cisplatin (CDDP) results in reduced haematological and renal toxicity but it has never been clearly shown that it affects the tumoral response rate. Before undertaking a clinical randomized study of CDDP monitoring versus standard dose, a comparative study was performed between a new software dedicated to the interactive adjustments--the AJI software--and the APIS software for clinical pharmacokinetics which incorporates a bayesian procedure and a population information computed according to a three compartment model. CDDP was administered by continuous infusion at variable rates with a controlled flow pump during four days in order to reach the target of 1.3 mg/L at the end of the first day, and to maintain this level during the whole treatment. This study was carried out on two groups of patients. Group 1 (12 patients; 27 courses) received CDDP with sequential flow rates in order to obtain a population information to be used with AJI. For patients in group 2 (14 patients; 26 courses), doses (flows) were adapted in a prospective study using the AJI software two to three times the first day, then daily. They could have been adapted (retrospective study) after platin pharmacokinetic parameters identification by APIS. The dosage recommendations proposed by APIS the first day, from 12 hours to 24 hours, to reach the target of 1.3 mg/L at 24 hours, and then daily up to D4 (AAPT at Di) to maintain this level were compared to those which were really administered during the interactive treatment (DA at Di). There were no statistically significant difference for D2, D4 and for the total dose (118.7 +/- 20.1 mg and 118.5 +/- 45.1 mg). The difference was statistically significant for D1 and D3 (P < 0.05). The inter-individual variability was less important with AJI (CV = 16.9% for DA total) than with APIS (CV = 38.0% for ADAPT total). The platin pharmacokinetic parameters identified the first day by APIS were not statistically different from those identified from the whole treatment for clearance (5.92 and 5.63 l/d) and Vtotal 87.8 and 93.1 L); the difference was statistically significant for Vinitial (34.7 and 42.5 L; P < 0.05) and the terminal half-life (13.1 and 15.5 days; P < 0.05).

[Circadian rhythm of the axillary temperature in mood disorders. Prominent ultradian period in major thymic disorders]. / Rythme circadien de la température axillaire dans les maladies de l'humeur. Prédominance d'une période ultradienne lors de troubles thymiques majeurs.

Axillary temperature was recorded in in-patients with affective disorders (DSM III-R). The results suggest that ultradian temperature rhythm could be the indice of an internal desynchronisation associated with acute episode of major affective disorders.

[Axillary temperature rhythms: the predominance of ultradian periodicity in major affective disorders]. / Rythmes de la température axillaire: prédominance d'une période ultradienne lors de troubles affectifs majeurs.

Axillary temperature was recorded at least twice during a 48 hrs. span at 6 min. intervals in 10 hospitalized subjects with major affective disorders (DSM III 296. xx). During the clinical occurrence of acute symptoms 7 out of 10 subjects exhibited a prominent ultradian periodicity (period tau less than 20 hrs.) in their temperature time series. Whatever the used therapeutic mean (electroconvulsive therapy and/or chemotherapy) the improvement was associated with a circadian rhythmicity (20 hrs. less than or equal to tau less than or equal to 28 hrs.). A prominent temperature ultradian rhythm (which occurs only in the new born) could be the index of an internal desynchronization associated with major affective disorders.

Internal desynchronization of circadian rhythms and tolerance of shift work.

Fifteen male subjects including 12 shift workers (oil refinery operators) volunteered to document circadian rhythms in sleep-wake, grip strength of both hands, peak expiratory flow, heart rate, self-rated drowsiness, fatigue and attention. Each of these variables was measured 4 to 6 times/day for 2 to 3 weeks. In addition, both axillary temperature (with a shielded probe) and wrist activity were almost continuously recorded at 15 min intervals during the same time span. Individual time series were analyzed according to several statistical methods (power spectrum, cosinor, chi 2, etc.), in order to estimate the prominent circadian period tau and to evaluate both individual and subgroup differences with regard to tolerance of shift work, age, duration of shift work. The present study confirms for continuously recorded temperature and wrist activity, grip strength of both hands, heart rate and peak expiratory flow that intolerance of shift work is frequently associated with an internal desynchronization. However, this conclusion cannot be extended to circadian rhythms in self-rated drowsiness, fatigue and attention. The internal desynchronization among several circadian rhythms supports the hypothesis that these latter are driven by several oscillators, with presumable differences between right and left hemispheres as suggested by unequal values of tau in rhythms of both hand grip strength. Since an internal desynchronization can be observed in tolerant shift workers having no complaint, it is likely that symptoms of intolerance are related to the subject's sensitivity to internal desynchronization rather than to the desynchronization itself.

[Kinetic evaluation of the adrenocortical response to telemetric stimulation of the hypothalamus in thalamic pigeons]. / Etude cinétique de la réponse corticosurrénalienne à la téléstimulation de l'hypothalamus du pigeon thalamique.

Kinetic evaluation of the adrenocortical activation induced after hypothalamic stimulation was obtained by determining plasma corticosterone levels (protein binding assay) at 2, then 5 and 10 min intervals for 100 min. Chronic catheterization and an electronic miniature device for hypothalamic telestimulation allowed for avoiding any environmental disturbance. Plasma corticosterone was rapidly increasing up to a peak (x 4 basal initial level) at 14 min after stimulating the hypothalamus for one sec. Corticosteronemia was then decreasing to resting level within one hour. This response was approximately the same in intact as in thalamic pigeons.