Light and temperature controls of aquatic plant photosynthesis downstream of a hydropower plant and the effect of plant removal.

Many rivers worldwide are regulated, and the altered hydrology can lead to mass development of aquatic plants. Plant invasions are often seen as a nuisance for human activities leading to costly remedial actions with uncertain implications for aquatic biodiversity and ecosystem functioning. Mechanical harvesting is often used to remove aquatic plants and knowledge of plant growth rate could improve management decisions. Here, we used a simple light-temperature theoretical model to make a priori prediction of aquatic plant photosynthesis. These predictions were assessed through an open-channel diel change in O2 mass balance approach. A Michaelis-Menten type model was fitted to observed gross primary production (GPP) standardised at 10 °C using a temperature dependence from thermodynamic theory of enzyme kinetics. The model explained 87 % of the variability in GPP of a submerged aquatic plant (Juncus bulbosus L.) throughout an annual cycle in the River Otra, Norway. The annual net plant production was about 2.4 (1.0-3.8) times the standing biomass of J. bulbosus. This suggests a high continuous mass loss due to hydraulic stress and natural mechanical breakage of stems, as the biomass of J. bulbosus remained relatively constant throughout the year. J. bulbosus was predicted to be resilient to mechanical harvesting with photosynthetic capacity recovered within two years following 50-85 % plant removal. The predicted recovery was confirmed through a field experiment where 72 % of J. bulbosus biomass was mechanically removed. We emphasise the value of using a theoretical approach, like metabolic theory, over statistical models where a posteriori results are not always easy to interpret. Finally, the ability to predict ecosystem resilience of aquatic photosynthesis in response to varying management scenarios offers a valuable tool for estimating aquatic ecosystem services, such as carbon regulation. This tool can benefit the EU Biodiversity Strategy and UN Sustainable Development Goals.

Estimation of ecosystem respiration and photosynthesis in supersaturated stream water downstream of a hydropower plant.

The estimation of whole stream metabolism, as determined by photosynthesis and respiration, is critical to our understanding of carbon cycling and carbon subsidies to aquatic food-webs. The mass development of aquatic plants is a worldwide problem for human activities and often occurs in regulated rivers, altering biodiversity and ecosystem functions. Hydropower plants supersaturate water with gases and prevent the use of common whole stream metabolism models to estimate ecosystem respiration. Here we used the inert noble gas argon to parse out biological from physical processes in stream metabolism calculations. We coupled the O2:Ar ratio determined by gas chromatography in grab samples with in-situ oxygen concentrations measured by an optode to estimate aquatic plant photosynthesis and ecosystem respiration during supersaturation events through a parsimonious approach. The results compared well with a more complicated two-station model based on O2 mass balances in non-supersatured water, and with associated changes in dissolved CO2 (or dissolved inorganic carbon). This new method provides an independent approach to evaluate alternative corrections of dissolved oxygen data (e.g. through the use of total dissolved gases) in long term studies. The use of photosynthesis-irradiance models allows the determination of light parameters such as the onset of light saturation or low light use efficiency, which could be used for inverse modelling. The use of the O2:Ar approach to correct for oversaturation may become more applicable with the emergence of portable mass inlet mass spectrometers (MIMS). Photosynthesis was modest (2.9-5.8 g O2 m2 day-1) compared to other rivers with submerged vegetation, likely indicating nutrient co-limitations (CO2, inorganic N and P). Respiration was very low (-2.1 to -3.9 g O2 m2 day-1) likely due to a lack of allochthonous carbon supply and sandy sediment.

Effects of pollution-induced changes in oxygen conditions scaling up from individuals to ecosystems in a tropical river network.

Anthropogenic inputs of nutrients and organic matter are common in tropical lowland rivers while little is known about the pollution-induced changes in oxygen availability and respiratory performance of ectotherms in these high temperature systems. We investigated the effects of agriculture and urban land-use on river water oxygen levels (diel measurements), decomposition rates (Wettex) and macroinvertebrate assemblages (field studies), as well as the oxy-regulatory capacity of eight riverine macroinvertebrate taxa (laboratory study) from a tropical lowland river network in Myanmar. The highest decomposition rates (0.1-5.5 mg Wettex degree day-1) and oxygen stress (≤91% saturation deficits) were found in reaches draining degraded catchments with elevated concentrations of nutrients. All individual macroinvertebrate taxa investigated were to some extent able to regulate their respiration when placed under oxygen stress in the laboratory (regulation value of 0.74-0.89). The oxy-regulation capacity of macroinvertebrate assemblages in the river network were, as predicted, inversely related to diel oxygen stress (maximum deficit; lm, R2 = 0.69), where taxonomic richness and pollution sensitivity (ASPT metric) also declined sharply (lm, R2 ≥ 0.79). Our study shows that eutrophication and organic pollution induce oxygen deficits in tropical rivers but stimulate decomposition rates, which may further deplete oxygen levels. Furthermore, macroinvertebrate oxy-regulatory capacity predicts assemblage composition along gradients in oxygen stress at the ecosystem level. Our findings suggest that tropical lowland river systems could be highly sensitive to pollution by nutrients and organic matter leading to substantial impacts on ectotherm community composition and ecosystem functioning.

Mechanical removal of macrophytes in freshwater ecosystems: Implications for ecosystem structure and function.

Macrophytes are generally considered a nuisance when they interfere with human activities. To combat perceived nuisance, macrophytes are removed, and considerable resources are spent every year worldwide on this practice. Macrophyte removal can, however, have severe negative impacts on ecosystem structure and functioning and interfere with management goals of healthy freshwater ecosystems. Here, we reviewed the existing literature on mechanical macrophyte removal and summarised current information from 98 studies on short- and long-term consequences for ecosystem structure and functioning. In general, the majority of studies were conducted in rivers and streams and evaluated short-term effects of removal on single ecosystem properties. Moreover, most studies did not address the interrelationships between ecosystem properties and the underlying mechanisms. Contrasting effects of removal on ecosystem structure and function were found and these discrepancies were highly dependent on the context of each study, making meaningful quantitative comparisons across studies very difficult. We illustrated how a Bayesian network (BN) approach can be used to assess the implications of macrophyte removal on interrelated ecosystem properties across a wide range of environmental conditions. The BN approach could also help engage a conversation with stakeholders on the management of freshwater ecosystems.

Juncus Bulbosus Tissue Nutrient Concentrations and Stoichiometry in Oligotrophic Ecosystems: Variability with Seasons, Growth Forms, Organs and Habitats.

Aquatic plant nutrient concentrations provide important information to characterise their role in nutrient retention and turnover in aquatic ecosystems. While large standing biomass of aquatic plants is typically found in nutrient-rich localities, it may also occur in oligotrophic ecosystems. Juncus bulbosus is able to form massive stands even in very nutrient-dilute waters. Here we show that this may be achieved by tissues with very high carbon-to-nutrient ratios combined with perennial (slow) growth and a poor food source for grazers inferred from plant stoichiometry and tissue nutrient thresholds. We also show that the C, N, P and C:N:P stoichiometric ratios of Juncus bulbosus vary with the time of year, habitats (lakes versus rivers) and organs (roots versus shoots). We found no differences between growth forms (notably in P, inferred as the most limiting nutrient) corresponding to small and large plant stands. The mass development of J. bulbosus requires C, N and P, whatever the ecosystem (lake or river), and not just CO2 and NH4, as suggested in previous studies. Since macrophytes inhabiting oligotrophic aquatic ecosystems are dominated by isoetids (perennial plants with a high root/shoot ratio), attention should be paid to quantifying the role of roots in aquatic plant stoichiometry, nutrient turnover and nutrient retention.

Rethinking Phage Ecology by Rooting it Within an Established Plant Framework.

Despite the abundance and significance of bacteriophages to microbial ecosystems, no broad ecological frameworks exist within which to determine "bacteriophage types" that reflect their ecological strategies and ways in which they interact with bacterial cells. To address this, we repurposed the well-established Grime's triangular CSR framework, which classifies plants according to three axes: competitiveness (C), ability to tolerate stress (S), and capacity to cope with disturbance (R). This framework is distinguished from other accepted schemes, as it seeks to identify individual characteristics of plants to understand their biological strategies and roles within an ecosystem. Our repurposing of the CSR triangle is based on phage transcription and the observation that typically phages have three major distinguishable transcription phases: early, middle, and late. We hypothesize that the proportion of genes expressed in these phases reflects key information about the phage "ecological strategy," namely the C, S, and R strategies, allowing us to examine phages in a similar way to how plants are projected onto the triangle. In the "phage version" of this scheme, we suggest: (1) that some phages prioritize the early phase of transcription that shuts off host defense mechanisms, which reflects competitiveness; (2) other phages prioritize tuning resource management mechanisms in the cell such as nucleotide metabolism during their "mid" expression profile to tolerate stress; and (3) a further subset of phages (termed Ruderals) survive disturbance by investing significant resources into regeneration so they express a higher proportion of their genes during late infection. We examined 42 published phage transcriptomes and show that they fall into discrete CSR categories according to their expression profiles. We discuss these positions in the context of their biology, which is largely consistent with our predictions of specific phage characteristics. In this opinion article, we suggest a starting point to ascribe phages into different functional types and thus understand them in an ecological framework. We suggest that this may have far-reaching implications for the application of phages in therapy and their exploitation to manipulate bacterial communities. We invite further use of this framework via our online tool; www.PhageCSR.ml.

Detection of an invasive aquatic plant in natural water bodies using environmental DNA.

The ability to detect founding populations of invasive species or rare species with low number of individuals is important for aquatic ecosystem management. Traditional approaches use historical data, knowledge of the species' ecology and time-consuming surveys. Within the past decade, environmental DNA (eDNA) has emerged as a powerful additional tracking tool. While much work has been done with animals, comparatively very little has been done with aquatic plants. Here we investigated the transportation and seasonal changes in eDNA concentrations for an invasive aquatic species, Elodea canadensis, in Norway. A specific probe assay was developed using chloroplast DNA to study the fate of the targeted eDNA through space and time. The spatial study used a known source of Elodea canadensis within Lake Nordbytjern 400 m away from the lake outlet flowing into the stream Tveia. The rate of disappearance of E. canadensis eDNA was an order of magnitude loss over about 230 m in the lake and 1550 m in the stream. The time series study was performed monthly from May to October in lake Steinsfjorden harbouring E. canadensis, showing that eDNA concentrations varied by up to three orders of magnitude, peaking during fall. In both studies, the presence of suspended clay or turbidity for some samples did not hamper eDNA analysis. This study shows how efficient eDNA tools may be for tracking aquatic plants in the environment and provides key spatial and temporal information on the fate of eDNA.

Functional biogeography: Stoichiometry and thresholds for interpreting nutrient limitation in aquatic plants.

Atmospheric N pollution may shift nutrient limitations in aquatic autotrophs from N to P or cause an intensification of P limitation in formerly pristine areas. Small changes in nutrient supply in oligotrophic lakes and rivers could lead to large changes in relative plant growth and yield with possible knock on effects on ecosystem carbon cycling through changes in the decomposition rate of their tissue. Previous biogeographical studies have shown inconsistent responses of plant nutrient tissue content and stoichiometry (functional traits) to external nutrient availability. Here we used a single species, Juncus bulbosus, to test the interplay between plant tissue nutrient (content and stoichiometry) and external environmental factors (local and catchment scale). We developed a comparative approach applicable globally to assess the thresholds for nutrient limitation in aquatic plants in the wild. Phosphorus in Juncus bulbosus tissue was negatively related to sediment organic matter (Fe root plaque limiting P uptake) and catchment vegetation cover (less P leaching to lakes). Our comparative approach revealed that the lack of increase in N plant tissue along the strong gradient in external N concentration may be explained by P limitation and strict plant tissue N:P ratio. Our comparative approach further showed that the nutrient content and stoichiometry of Juncus bulbosus was similar to other submerged aquatic plants growing in nutrient poor aquatic ecosystems. In southern Norway, mass development of Juncus bulbosus may be primarily triggered by changes in P availability, rather than CO2 or inorganic N, as previously thought, although co-limitations are also possible. If so, the mass development of Juncus bulbosus in oligotrophic aquatic ecosystems could be an early indicator of increasing P fluxes through these ecosystems which are less limited by N due to high atmospheric N deposition.

Athletic pubalgia: Return to play after targeted surgery.

BACKGROUND: Surgery for athletic pubalgia usually consists in abdominal wall repair combined with routine bilateral adductor tenotomy. We currently confine the surgical procedure to the injured structure(s) (abdominal wall only, adductor tendon only, or both) to limit morbidity and expedite recovery. Outcomes of this à la carte approach are unclear. The objectives of this retrospective study were to determine the return to play (RTP) time, evaluate the potential influence of injury location, and assess the frequency of recurrence or contralateral involvement. HYPOTHESIS: À la carte surgery for athletic pubalgia is associated with similar RTP times as the conventional procedure and is not followed by recurrence. MATERIAL AND METHODS: Consecutive adults younger than 40 years of age who underwent surgery for athletic pubalgia with injury to the abdominal wall and/or adductor attachment sites between 2009 and 2015 were included. Patients with intra-articular hip disorders, isolated pubic symphysis involvement, or herniation were not eligible. The diagnosis was established clinically then confirmed by at least one imaging technique (ultrasonography plus either a radiograph of the pelvis or magnetic resonance imaging of the pelvis). The criterion for performing surgery was failure of appropriate conservative therapy followed for at least 3 months. RESULTS: Of the 27 included patients, eight had abdominal wall involvement only, seven adductor tendon involvement only, and 12 both. Overall, 25 (92.6%) patients returned to play at their previous level, after a mean of 112±38 days (range, 53-223 days), and experienced no recurrence during the 1-year follow-up. Mean RTP time was significantly shorter in the group with abdominal wall injury only (91.1±21.0 days) compared to the groups with adductor tendon injury only (101.7±42.0 days) or combined injuries (132.5±39.0) (p=0.02). DISCUSSION: In patients with athletic pubalgia, à la carte surgery confined to the injured structure(s) produces excellent RTP outcomes. RTP time is shortest in patients with isolated lower abdominal wall injuries. LEVEL OF EVIDENCE: IV, retrospective study with no control group.

Profil de sensibilisation aux allergènes des asthmatiques adultes à Kinshasa, RDC : Etude transversale par prick-tests

Contexte. Environ 80% des asthmatiques sont atopiques. La sensibilisation aux allergènes communs présente certaines variabilités environnementales et géographiques. Objectif. Déterminer le profil de sensibilisation aux allergènes communs des asthmatiques adultes de la ville de Kinshasa. Méthodes. De juin 2017 à février 2018, 216 asthmatiques de 18 ans et plus, des 2 sexes, ont été consécutivement recrutés aux Cliniques Universitaires de Kinshasa et dans certaines paroisses et églises de réveil de la ville de Kinshasa. A l'aide d'un questionnaire validé, les variables sociodémographiques ont été précisées. Le prick-test a été réalisé avec cinq extraits commerciaux standardisés de phanères de chien et chat, l'acarien de poussière de maison (Blomia tropicalis, Bt), les moisissures (Alternaria alternata), et le jaune d'œuf. Résultats. L'âge moyen de la population était de 45,23 (ET=17,56) ans, 74% de sexe féminin, 47 % non sensibilisés et 53% sensibilisés à au moins un allergène. Vingt-cinq pourcent étaient monosensibilisées et 27% plurisensibilisées. Le profil de sensibilisation était Blomia tropicalis (72%), phanères de chat (46%), phanères de chien (34%), Alternaria alternata (13%) et jaune d'œuf (11%). Conclusion. Une plurisensibilisation aux allergènes communs chez les asthmatiques dans notre milieu est présente dont le profil dominé par les acariens et les phanères de chats. Des enquêtes futures incluant un plus grand nombre de sujets et recourant à des batteries de tests plus élargies s'imposent en vue d'une définition d'options diagnostiques et thérapeutiques dans notre contexte

Temperature effects on fish production across a natural thermal gradient.

Global warming is widely predicted to reduce the biomass production of top predators, or even result in species loss. Several exceptions to this expectation have been identified, however, and it is vital that we understand the underlying mechanisms if we are to improve our ability to predict future trends. Here, we used a natural warming experiment in Iceland and quantitative theoretical predictions to investigate the success of brown trout as top predators across a stream temperature gradient (4-25 °C). Brown trout are at the northern limit of their geographic distribution in this system, with ambient stream temperatures below their optimum for maximal growth, and above it in the warmest streams. A five-month mark-recapture study revealed that population abundance, biomass, growth rate, and production of trout all increased with stream temperature. We identified two mechanisms that contributed to these responses: (1) trout became more selective in their diet as stream temperature increased, feeding higher in the food web and increasing in trophic position; and (2) trophic transfer through the food web was more efficient in the warmer streams. We found little evidence to support a third potential mechanism: that external subsidies would play a more important role in the diet of trout with increasing stream temperature. Resource availability was also amplified through the trophic levels with warming, as predicted by metabolic theory in nutrient-replete systems. These results highlight circumstances in which top predators can thrive in warmer environments and contribute to our knowledge of warming impacts on natural communities and ecosystem functioning.

Aquatic macrophytes as bioindicators of carbon dioxide in groundwater fed rivers.

Aquatic plants have been used as hydrological tracers in groundwater fed river systems. In nature, patterns in plant distribution have been attributed to ammonium (NH(4)) toxicity and phosphate (PO(4)) limitation, while some laboratory studies have focused on the role of the partial pressure of CO(2) (pCO(2)). The aims of this study were (i) to test whether plant distribution was more related to pCO(2) than NH(4) and PO(4) in nature, (ii) to develop and test the predictive power of new plant indices for pCO(2), NH(4) and PO(4), and (iii) to test the potential causality of the relationships using species eco-physiological traits. These tests were carried out with field data from the Rhine, Rhône and Danube river basins. Species composition was best related to the effect of pCO(2). The pCO(2) plant index was well calibrated (r(2)=0.73) and had the best predictive power (r(2)=0.47) of the three indices tested on independent datasets. The plant-pCO(2) relationship was supported by a biological mechanism: the ability of strictly submerged species of aquatic vascular plants to use HCO(3) under low pCO(2). This was not the whole story: the effects of pCO(2), NH(4) and PO(4) on plant distribution were partially confounded and interacted all together with temperature. However, neither NH(4) toxicity nor P limitation could be asserted using species eco-physiological traits. Moreover, the predictive power of the NH(4) and PO(4) plant indices was not as strong as pCO(2), at r(2)=0.24 and r(2)=0.27, respectively. Other potentially confounding variables such as spatial structure, biotic and physical factors were unlikely to confound the findings of this study.

Distribution of aquatic macrophytes in contrasting river systems: a critique of compositional-based assessment of water quality.

A brief summary of the historical developments relating to plant distribution and aquatic macrophyte-nutrient indices provided a means of assessing the general context and validity of previous assumptions. This has particular current relevance because of the prominent use of bioindicators for defining nutrient enrichment. A survey of 161 sites distributed across two broadly contrasting groups of rivers (circum-neutral versus alkaline) recorded 110 species of aquatic macrophytes and these have been statistically analyzed to (i) rank and separate the individual effects of local environmental conditions and spatial isolation on species distribution in the two contrasting groups of sites; (ii) calculate a macrophyte index based on plant cover and species indicator values (Mean Trophic Rank, MTR); and finally (iii) investigate the implications for biomonitoring. Chemical, physical and hydrological site attributes together with spatial isolation, each explained a significant and at least partially independent influence over plant species distribution. It was extremely difficult, however, to separate the single effects of different site attributes on plant distribution. While some plant species are more restricted to certain environmental conditions, many appeared indifferent to the range of those being tested. The role played by nutrients (nitrogen (N) and phosphorus (P)) were either mostly indistinguishable from other site attributes (e.g., nitrate from conductivity) or subordinate (e.g., soluble reactive phosphorus, ammonium). It is therefore very unlikely that macrophyte species composition could provide a reliable bioindicator of the surrounding nutrient (N, P) status. The calculation of the plant index illustrated this unreliability by showing that strong correlations existed with many environmental variables, not just inorganic N and P.

[Adventitial mucoid cyst of the radial artery associated with volar wrist ganglion. A case report]. / Kyste mucoïde adventitiel de l'artère radiale associé à un kyste arthrosynovial radiocarpien de la gouttière du pouls. A propos d'un cas.

The authors report a rare case of a 51-years old woman presenting with cystic mucoid adventitial disease of the radial artery associated with a volar wrist ganglion. Imaging namely doppler sonography, magnetic resonance scanning and angio-MR was performed preoperatively because of a history of radial artery aneurysm in the opposite wrist. The radial artery was resected and the defect bridged by a venous autograft; the volar wrist ganglia was removed. Postoperative histological analysis confirmed mucoid adventitial cyst without communication with the volar wrist ganglion. Surgeons ought to be aware of this rare differential diagnosis (less than ten cases in the literature) in cases of preoperative or peroperative diagnostic doubt.

[Percutaneous compression plate for pertrochanteric fixation of hip fractures: surgical technique and first results]. / Ostéosynthèse des fractures du massif trochantérien par plaque de compression percutanée: Technique chirurgicale et premiers résultats.

We have used a minimally invasive technique for fixation of trochanteric fractures since 2003. We use the percuntaneous compression plate described by Gotfried. We describe here the osteosynthsis technique and our special approach which limits operative time. This technique avoids wide opening of the aponeurosis of the tensor fascia lata, major detachment, and section of the vastus lateralis. The plate is inserted via a 2-cm incision over the greater trochanter. Head and shaft screws are inserted via a second incision measuring 3 to 4 cm. Perfect reduction before plate insertion is the key to success. The results of our first twenty cases have demonstrated an uneventful postoperative period and a short operative time of 25 minutes on average. Peri-operative bleeding has been very limited. Radiographic healing was obtained in three months. Weight bearing was possible immediately after fixation in five cases and was delayed in fifteen. There were two early displacements which were analyzed.

[A 36 month prospective study of 12 plate osteosyntheses of distal radius fractures]. / Etude prospective sur 36 mois de 12 ostéosynthèses en vasque de l'extrémité distale du radius.

INTRODUCTION: We performed a prospective study of 12 intra-articular distal radial fractures. The fractures were treated with an anterior plate together with posterior pinning. The aim of the study was to examine whether it was technically feasible to fix such fractures using this technique and to assess the stability of the fixation at follow up. METHOD: Twelve articular fractures were included with a mean age of 47.1 years. All patients were followed up from first admission to the 36th postop month with clinical and radiological checks. RESULTS: At follow up, we found 8 good and excellent clinical results, 3 fair and 1 poor. The combination of an anterior plate with posterior pinning allowed a good initial reduction but could not protect from secondary displacement particularly in the presence of a comminuted metaphysal fracture. DISCUSSION: This procedure gave clinically satisfactory results but did not control ulnar variance. This procedure should be combined with bone grafting in complex metaphysal fractures and epiphysal screws should be used whenever possible.

[Extensor tendon rupture after dorsal surgery of the rheumatoid wrist: analysis of nine reviewed cases]. / Les ruptures des tendons extenseurs aprés chirurgie dorsale du poignet rhumatoïde: analyse de 9 cas revus.

We led a retrospective study to determine the causes of the tendon ruptures post-operating in the surgery of the wrist rheumatoid dorsal and to estimate the clinical result. At follow-up, we measured the extension lag and the rolling-up of fingers by the distance palm-pulps. Nine patients were so revised in the average of 40 months, average age was of 50.7 years. The tendon ruptures arose in 3 months in 67% of the cases. Seven times, a procedure on the distal radio-ulnar joint had been necessary (5 Sauvé-Kapandji and 2 Darrach). Thirty tendons had been concerned in this study, that is 3.3 tendons on average (1-5). Two main causes were found: attrition on the stub ulnaire and great intra-tendinous synovitis (per operating observation). At the revision, the lag extension means was 23 degrees (0-40). Rolling-up of the long fingers was complete 4 times on 7. The best results were observed after tendinous grafting or index proprius transfer with a lateral suture. Tendinous adhesions had arisen 6 times and persisted still at 3 patients. Our study underlines the interest to stabilize the stub ulnaire to prevent the post-operating ruptures and proposes a transfer or a graft in front of tendons very weakened by the synovitis.

[Fracture-dislocation of the second carpometacarpal joint. Case report and review of the literature]. / Fracture-luxation carpométacarpienne du deuxième rayon à propos d'un cas et revue de la littérature.

A 26-year-old man was involved in a car crash then he presented an isolated trauma of the hand. We found out a dorsal dislocation of the second carpometacarpal joint with trapezoid fracture and a Rolando fracture. In emergency, closed reduction with percutaneous wires to stabilize, was performed. In the same time, the Rolando fracture was treated by internal fixation (plate). In a second time, after computerized tomography of the carpus, the trapezoid was reduced through a dorsal incision and held with two Kirschner-wires. At last follow-up one year after injury, the result was good. All movements of the wrist and fingers were full and pain free. Thumb index pinch and grasp were approximately 80% those of the uninjured hand. The mechanisms of injury, anatomic factors and management of seventy-one cases of similar trauma (included at least a dislocation of the second carpometacarpal joint) were reviewed in the literature.

Slow (0.7-2 Hz) and fast (2-4 Hz) delta components are differently correlated to theta, alpha and beta frequency bands during NREM sleep.

OBJECTIVES: Spectral power of 40 all-night sleep EEGs (Cz-Pz bipolar lead) recorded in 20 healthy young subjects was calculated after normalization on 30-s consecutive epochs by means of an autocorrelation method based on a 15-order autoregressive model. METHODS: The spectral parameters were calculated for the 7 main EEG bands: slow delta (0.7-2 Hz); fast delta (2-4 Hz); theta (4-8 Hz); alpha (8-12 Hz); sigma (12-16 Hz); beta1 (16-35 Hz); and beta 2 (>35 Hz). RESULTS: Strong negative correlations were found between power in the fast delta and either the alpha or the beta bands and between slow delta and theta bands, whereas the two delta bands showed little correlation with each other. CONCLUSION: The possibility that theses different relationships of slow and fast delta components with other frequency bands might reflect the neocortical or the thalamocortical origin of the delta waves is discussed.