Measuring nutrient fluxes across the sediment-water interface using benthic chambers

11 páginas, 8 figuras, 2 tablas.This paper presents a simple model to determine the benthic fluxes of matter across the sediment-water interface when a benthic chamber is used. The model is based on accepting that the limiting step for the overall rate of transfer while the chamber is in position is the diffusion through the diffusive boundary layer (DBL) overlying the sediment, and it assumes that this rate is necessarily affected by the procedure employed to measure the flux. Alteration of the benthic fluxes due to the action of macrofauna is included in the model and, operatively, is expressed in terms of a reduction in the thickness of the DBL between the sediment and the water. If the diffusive fluxes are determined simultaneously with the benthic chamber experiments, a value can be estimated for the thickness of the 'stagnant film'. Owing to the assumptions made and to the micro-heterogeneities of the sediment, this thickness can be considered to have both an operative and a statistical meaning, with respect to the entire surface area covered by the chamber. The values calculated in the Bay of Cádiz (SW Spain) vary between 0.36 and 0.71 mm, which are in agreement with measurements of this film made by different techniques in other littoral ecosystems. However, the values of the in situ fluxes estimated using this model and by other established procedures described in the literature can differ by more than 50%, for the same experiment, in strongly irrigated zones.The work was supported by the Consejo Superior de Investigaciones Científicas (CSIC) through research grant 630/070-1988.Peer reviewe

Myotonic dystrophy type 1 presenting with stroke-like episodes: a case report

BACKGROUND: It is well known that myotonic dystrophy type 1 (DM1) - Curschmann-Steinert disease - is associated with white matter lesions in the brain. Further, DM1 patients may suffer from cardiac involvement and cardioembolic strokes. We report on the unique case of an adult-onset DM1 without cardiac or vascular abnormalities presenting with stroke-like episodes. CASE PRESENTATION: A 40 y old white female was admitted twice to our stroke unit with apoplectic dizziness, nausea, headaches, and numbness in the right arm. She was suffering from type 2 diabetes, cataract, and endometriosis. Magnetic resonance imaging (MRI) revealed confluent white matter lesions in all cerebral lobes. There was no hyperintensity on diffusion-weighted imaging (DWI) and no gadolinium enhancement. Cerebrospinal fluid was normal. Surprisingly, myotonic discharges were detected in electromyography (EMG). Genetic testing revealed 200 ± 10 CTG repeats in the dystrophia myotonica protein kinase (DMPK) gene on chromosome 19 and DM1 was diagnosed. CONCLUSIONS: DM1 may be the cause of cerebral white matter lesions. This is the first case of DM1 presenting with stroke-like episodes

The Early Functional Abilities (EFA) scale to assess neurological and neurosurgical early rehabilitation patients

BACKGROUND: It is difficult to assess neurological and neurosurgical early rehabilitation patients comprehensively. Available scales focus on activities of daily living (Barthel (BI) and Early Rehabilitation Barthel Index (ERBI)) or wakefulness (Glasgow Coma Scale (GCS), Coma Remission Scale (CRS)) while cognitive items are missing. METHODS: The Early Functional Abilities (EFA) scale comprises 20 items referring to activities of daily living (ADL), wakefulness and cognitive abilities. To evaluate its validity, n = 623 early neurological and neurosurgical rehabilitation patients (most of them after ischemic stroke or cerebral bleeding) were assessed on admission using the EFA, ERBI, GCS, CRS and measures of morbidity (co-diagnoses). RESULTS: The more co-diagnoses the lower EFA sum scores were obtained (Spearman-Rho r(s) = -0.509, p < 0.001). EFA predicted length of stay (LOS, r(s) = -0.565, p < 0.001) and BI at discharge (r(s) = 0.571, p < 0.001). CONCLUSIONS: The results suggest that EFA is a valid instrument to assess critically ill neurological and neurosurgical early rehabilitation patients. It may be used as a measure of morbidity and a predictor of LOS and outcome. Further studies are strongly encouraged

Expected Valence Predicts Choice in a Recurrent Decision Task

There is empirical evidence that expected yet not current affect predicts decisions. However, common research designs in affective decision-making show consistent methodological problems (e.g., conceptualization of different emotion concepts; measuring only emotional valence, but not arousal). We developed a gambling task that systematically varied learning experience, average feedback balance and feedback consistency. In Experiment 1 we studied whether predecisional current affect or expected affect predict recurrent gambling responses. Furthermore, we exploratively examined how affective information is represented on a neuronal level in Experiment 2. Expected and current valence and arousal ratings as well as Blood Oxygen Level Dependent (BOLD) responses were analyzed using a within-subject design. We used a generalized mixed effect model to predict gambling responses with the different affect variables. Results suggest a guiding function of expected valence for decisions. In the anticipation period, we found activity in brain areas previously associated with valencegeneral processing (e.g., anterior cingulate cortex, nucleus accumbens, thalamus) mostly independent of contextual factors. These findings are discussed in the context of the idea of a valence-general affective work-space, a goal-directed account of emotions, and the hypothesis that current affect might be used to form expectations of future outcomes. In conclusion, expected valence seems to be the best predictor of recurrent decisions in gambling tasks

Long-term outcomes of community-based intensive care treatment following neurological early rehabilitation: results of a multicentric German study

Background: Weaning from mechanical ventilation (MV) and tracheal cannula (TC) during neurological early rehabilitation (NER) is mostly successful. However, some patients leave NER with TC/MV, requiring home-based specialized intensive care nursing (HSICN). Data on medical and demographic characteristics and long-term outcomes of these patients are limited. Methods: A multicentric retrospective observational study across five German NER hospitals collected data from neurological patients with TC/MV at discharge. The study aimed to assess patients' health status at NER discharge, and to identify predictors of post-discharge survival. Survival rates were analyzed using Kaplan-Meier estimates; further predictors of survival post-discharge were analyzed using Cox regression. Results: Among 312 patients, the one-year survival rate was 61.9%, decreasing to 38.1% after approximately 4 years. Older age, higher overall morbidity and discharge with MV were associated with an increased likelihood of death, while a longer stay in NER correlated with survival. Conclusions: Patients requiring HSICN after discharge from NER have a high mortality rate. Identifying survival predictors may help to identify patients at risk, and thus could be integrated into the decision-making process for NER discharge. The high mortality post-discharge warrants an evaluation of the current post-hospital care model. Optimizing therapeutic care in the HSICN setting may have the potential to reduce mortality and neuro-disability, and enhance the quality of life in these neurologically severely affected patients. Trial registration: The trial OptiNIV - Retrospective study of post-hospital intensive care in neurological patients has been retrospectively registered in the German Clinical Trials Register (DRKS) since 28.10.2022 with the ID DRKS00030580

Hoffnung für Huntington-Patienten – erste klinische Gene-Silencing-Studie

ZusammenfassungBei der Huntington-Erkrankung handelt es sich um eine bisher nicht kausal behandelbare neurodegenerative Erkrankung, die mit motorischen, psychiatrischen und kognitiven Symptomen einhergehen kann.Die Ursache der in Deutschland mit einer Häufigkeit von etwa 1:10 000 auftretenden, autosomal-dominant vererbten Erkrankung, ist eine Mutation im Huntingtin-Gen (CAG-Expansion). Diese führt zu einer Polyglutamin-Expansion im Huntingtin-Protein (HTT). Das so veränderte HTT (mHTT) hat eine zytotoxische Wirkung, ist schlecht löslich, neigt zur Aggregation in der Zelle und löst eine komplexe pathophysiologische Kaskade aus, an deren Ende eine gestörte Zellfunktion und schließlich der Zelltod stehen. In dem vorliegenden Artikel wird das Prinzip des Gene Silencing erklärt, mit dem Transkription bzw. Translation des Huntingtins gehemmt werden können. Ein Ansatz, der zu einer Suppression der Translation führt, ist der Einsatz von Antisense Oligonukleotiden (ASO), welche an prä-mRNA andocken. Eine erste klinische Studie bei frühmanifesten Huntington-Patienten wird seit August 2015 mit ASO (Studiensubstanz: IONIS-HTTRx) durchgeführt (NCT02519036). Auch wenn Ergebnisse noch abgewartet werden müssen, könnte die Studie den Weg zu einer ersten kausalen Therapie der Huntington-Erkrankung ebnen.</jats:p

Das Myalgie-Faszikulations-Krampus-Syndrom (MFKS)

ZusammenfassungDie vorliegende Übersichtsarbeit beschäftigt sich mit dem Myalgie-Faszikulations-Krampus-Syndrom (MFKS), einer gutartigen Erkrankung, die zu den Hyperexzitabilitätssyndromen des peripheren Nervensystems gezählt wird. Der Artikel stellt die Klinik, Pathophysiologie, Differenzialdiagnostik und Therapie dar und illustriert das MFKS mit einem typischen Fallbericht.</jats:p