Heavy rains control the floating macroplastic inputs into the sea from coastal Mediterranean rivers: A case study on the Têt River (NW Mediterranean Sea).

This study focuses on the relevance of small watersheds in the macroplastic pollution of coastal environments. It aims to identify and quantify in terms of composition, number and mass, current riverine flows of floating macroplastics (>2.5 cm). Estimates are based on 66 visual monitoring of total litter over a 4-year-period (2016-2019) in a small coastal Mediterranean river, the Têt River (NW Mediterranean Sea). The plastic fraction represented 97 % of the observed litter, mainly cigarette butts (20.5 %), polystyrene fragments (18.8 %) and light packaging (16.3 %). The Tet River is characterized by frequent flash-flood events caused by heavy rain, that can induce a sudden rise of the water discharge. Such hydroclimatic forcing greatly influence macroplastic flows, both in terms of their average compositions and loads. We have estimated that 354,000 macroplastic items, corresponding to 0.65 tons, are discharged annually from the Tet River into the sea, and that 73 % of them are released during rain events (∼6 % of the year). The short observation distance from the water surface allowed to exhibit the great abundance of small litter (80 % of them were < 10 cm) and to evaluate to 1.8 g the average mass of floating plastics. Our results suggest that remediation actions must be taken on rainy days and target small litter in order to significantly limit macroplastic inputs from rivers to the sea. Moreover, the large share of cigarette butts in macrolitter inputs demonstrates that reducing ocean pollution cannot be achieved solely by improving waste management, but that changes in social behavior are also needed to stem waste production at the source.

Use of routine CT-SCANS to detect severe postoperative complications after pancreato-duodenectomy.

BACKGROUND: To evaluate the performance of CT-scans performed one week after pancreato-duodenectomy (PD) to detect severe postoperative complications requiring an invasive treatment. PATIENTS AND METHODS: This monocentric retrospective study was conducted on data collected between 2005 and 2013. Patients undergoing PD underwent CT-scan with IV contrast at the end of the first postoperative week. The results of the CT-scans were analyzed to evaluate the usefulness of this procedure. The main assessment criterion was the occurrence of type-III complication (or greater) according to the Dindo-Clavien classification. RESULTS: In total, 138 patients were included. The mortality rate was 2.2%. The postoperative complication rate was 57.2%. The pancreatic fistula rate was 19.6%; 46 patients (33.3%) presented with a severe complication. A total of 138 CT-scans were analyzed: 44 (31.8%) were abnormal, 94 (68.2%) were normal. Among patients with abnormal CT-scans, 17 (39%) presented with a severe complication requiring an invasive treatment. Among the 94 patients with normal CT-scans, 14 patients (15%) presented a severe postoperative complication. Evaluation of the performance of the CT-scans at the end of the first postoperative week found a sensitivity of 55%, a specificity of 75%, a positive predictive value of 39%, and a negative predictive value of 85%. CONCLUSION: Systematic CT-scans performed at the end of the first postoperative week do not effectively detect severe complications after PD and do not help to prevent them.

An annual survey of bacterial production, respiration and ectoenzyme activity in coastal NW Mediterranean waters: temperature and resource controls.

We simultaneously measured bacterial production (BP), bacterial respiration (BR), alkaline phosphatase activity (phos) and ectoaminopeptidase activity (prot) in relation to biogeochemical parameters, nutritive resources and in situ temperature over a 1-year survey at the long-term observatory the SOLEMIO station (Marseille bay, NW Mediterranean Sea). Despite its proximity to the coast, oligotrophic conditions prevailed at this station (yearly mean of Chl a = 0.43 µg dm(-3), NO3 = 0.55 µmol dm(-3) and PO4 = 0.04 µmol dm(-3)). Episodic meteorological events (dominant winds, inputs from the Rhone River) induced rapid oscillations (within 15 days) in temperature and sometimes salinity that resulted in rapid changes in phytoplankton succession and a high variability in C/P ratios within the particulate and dissolved organic matter. Throughout the year, BP ranged from 0.01 to 0.82 µg C dm-(3) h-(1) and bacterial growth efficiency varied from 1 to 39%, with higher values in summer. Enrichment experiments showed that BP was limited most of the year by phosphorus availability (except in winter). A significant positive correlation was found between in situ temperature, BP, BR and phos. Finally, we found that temperature and phosphate availability were the main factors driving heterotrophic bacterial activity and thus play a fundamental role in carbon fluxes within the marine ecosystem.

Effects of photochemical transformations of dissolved organic matter on bacterial metabolism and diversity in three contrasting coastal sites in the Northwestern Mediterranean Sea during summer.

The effects of phototransformation of dissolved organic matter (DOM) on bacterial growth, production, respiration, growth efficiency, and diversity were investigated during summer in two lagoons and one oligotrophic coastal water samples from the Northwestern Mediterranean Sea, differing widely in DOM and chromophoric DOM concentrations. Exposure of 0.2-microm filtered waters to full sun radiation for 1 d resulted in small changes in optical properties and concentrations of DOM, and no changes in nitrate, nitrite, and phosphate concentrations. After exposure to sunlight or dark (control) treatments, the water samples were inoculated with the original bacterial community. Phototransformation of DOM had contrasting effects on bacterial production and respiration, depending on the water's origin, resulting in an increase of bacterial growth efficiency for the oligotrophic coastal water sample (120%) and a decrease for the lagoon waters (20 to 40%) relative to that observed in dark treatments. We also observed that bacterial growth on DOM irradiated by full sun resulted in changes in community structure of total and metabolically active bacterial cells for the three locations studied when compared to the bacteria growing on un-irradiated DOM, and that changes were mainly caused by phototransformation of DOM by UV radiation for the eutrophic lagoon and the oligotrophic coastal water and by photosynthetically active radiation (PAR) for the mesoeutrophic lagoon. These initial results indicate that phototransformation of DOM significantly alters both bacterial metabolism and community structure in surface water for a variety of coastal ecosystems in the Mediterranean Sea. Further studies will be necessary to elucidate a more detailed appreciation of potential temporal and spatial variations of the effects measured.

Nigroamygdaloid dopamine neurons: nigral modulation of their activity.

In order to study the mechanisms regulating the dopaminergic nigroamygdaloid cells, the release of dopamine was observed in the central nucleus of the amygdaloid complex. Halothane anesthetized rats were implanted, according to the experiment, with one or two push-pull cannulae in the central nuclei of the amygdala (ACE), the substantia nigra (SN) and/or the caudate nucleus (CN). Canulae were supplied with artificial cerebrospinal fluid (CSF) containing tritiated tyrosine, and labeled dopamine [3H]DA was evaluated in successive superfusate fractions. Electrical stimulation of the medial forebrain bundle with an implanted bipolar electrode induced an increase of the [3H]DA release in the ipsi- and contralateral ACE. Electrical stimulation of the SN produced only a very delayed effect in the ipsilateral ACE but an immediate and large increase of [3H]DA release in the contralateral structure. Superfusion of unlabeled DA and alpha-methyl-p-tyrosine in the SN remained ineffective on the [3H]DA release in the ipsilateral ACE. In this structure the release of [3H]DA was, however, decreased by nigral superfusion with gamma-amino-butyric acid (GABA). D-(+)-Amphetamine (1 microM), when superfused in the CN, induced a large enhancement of the [3H]DA release in the ipsilateral ACE simultaneously with the local increase of [3H]DA release. The results presented here are in agreement with the previous studies concerning the anatomical organization of the dopaminergic nigroamygdaloid pathway. The DA cell bodies located in the SN appear insensitive to a local action of DA, perhaps due to a lack of autoreceptors. They are, however, powerfully inhibited by GABA and the relation observed between the [3H]DA release in the CN and ACE support the hypothesis that the SN can act as a relay between the extrapyramidal and limbic systems.

In vivo release of adenosine from cat basal ganglia-studies with a push pull cannula.

The release of newly synthesized [(3)H]adenosine has been studied in vivo in cat caudate nucleus and substantia nigra, using a push pull cannula. In the presence of [(3)H]adenosine as precursor, spontaneously released [(3)H]adenosine was easily detectable in superfusates of the push pull cannula. In the caudate nucleus, potassium and veratridine caused a marked and reversible increase in [(3)H]adenosine release. The effect of veratridine was completely blocked by tetrodotoxin (TTX) although TTX had no action by itself. Ouabain as well as glutamate, also markedly increased the release of [(3)H]adenosine. The specific 5? nucleotidase inhibitor ?,?-methylene ADP, did not alter the increase in the amount of [(3)H]adenosine obtained by veratridine, although it diminished the spontaneous release of [(3)H]adenosine by about 20%. Push pull cannulae were also implanted simultaneously into the caudate nucleus and substantia nigra. Potassium applied into the caudate nucleus increased the local release of adenosine but did not change that observed in the substantia nigra. When potassium was applied into the substantia nigra, it also increased the local release of adenosine but did not change that observed in the caudate nucleus. The results are discussed in term of the possible existence of "purinergic neurons" and of the relation between the adenosine release and central nervous activity.

Release of adenosine in vivo from cat caudate nucleus.

A push-pull perfusion technique was used to study the release of endogenously synthesized [3H]-adenosine from caudate nucleus in the anaesthetized cat. The spontaneous release of [3H]adenosine newly synthesized from [3H]adenine reached a steady state level 40 min after the beginning of superfusion and continued for 4 h. Potassium and veratridine increased the release of newly synthetized [3H]-adenosine. The action of veratridine was completely blocked by tetrodotoxin. We conclude that spontaneous and evoked release of adenosine occurs in the cat striatum and might potentially affect central nervous function.