Contribution of flow conditions and sand addition on hyporheic zone exchange in gravel beds

We conducted a series of tracer test experiments in 12 outdoor semi-natural flumes to assess the effects of variable flow conditions and sand addition on hyporheic zone conditions in gravel beds, mimicking conditions in headwater streams under sediment pressure. Two tracer methods were applied in each experiment: 2–5 tracer-pulse tests were conducted in all flumes and pulses were monitored at three distances downstream of the flume inlet (0 m, 5 m and 10 m, at bed surface), and in pipes installed into the gravel bed at 5 m and 10 m distances. The tracer breakthrough curves (total of 120 tracer injections) were then analysed with a one-dimensional solute transport model (OTIS) and compared with data from the gravel pipes in point-dilution pulse tests. Sand addition had a strong negative effect on horizontal fluxes (qh), whereas the fraction of the median travel time due to transient storage (F200) was determined more by flow conditions. These results suggest that even small additions of sand can modify the hyporheic zone exchange in gravel beds, thus making headwater streams with low sediment transport capacity particularly vulnerable to sediments transported into the stream from catchment land use activities

Effects of Age of Onset of Tonic-Clonic Seizures on Neuropsychological Performance in Children

Forty-eight children (aged 9 to 15 years) with tonic-clonic seizures were administered a neuropsychological test battery. The children with seizures of early onset (before age 5) were significantly impaired relative to the children with later onset on 8 of the 14 measures in the battery. The deficits were seen on tasks whose requirements included the repetition of a simple motor act, attention and concentration, memory, and complex problem solving. These findings emphasize the need for further research to determine the causal factors of the greater dysfunction seen in the early onset group. RÉSUMÉ Quarante huit enfants ÁgÉs de 9 À 15 ans souffrant de crises Épileptiques tonico-cloniques ont ÉtÉÉtudiÉs avec une batterie de tests neuropsychologiques. Pour huit des quatorze mesures de cette batterie de tests les enfants dont les cirses avaient dÉbutÉ prÉcocÉment (avant cinq ans) se sont avÉrÉs Étre signiflcativement dÉtÉriorÉs par rapport À ceux dont les crises avaient dÉbutÉ plus tardivement. Les dÉficits se sont manifestÉs pour des tÁches nÉcessitant la rÉpÉtition d'un acte moteur simple, attention et concentration, mÉmoire et capacitÉÀ rÉsoudre des problÈmes complexes. Ces rÉsultats mettent l'accent sur la nÉcessitÉ de poursuivre les recherches afin de dÉterminer les facteurs responsables de la plus grande dysfonction observÉe chez les enfants dont l'Épilepsie a dÉbutÉ tÔt dans la vie. RESUMEN Se ha aplicado una bateria de tests neuro-psicolÓgicos a 48 niÑos de 9 a 15 aÑos de edad que padecÍan ataques tonico-clÓnicos. Los niÑos con ataques de comienzo precoz (antes de los 5 aÑos) mostraron incapacidades significativas compareÁndolos con niÑos con comienzos mÁs tardios en 8 de los 14 tests de la bateria. Los defectos fueron detectados en las pruebas cuyos requisitos incluÍan la repeticiÓn de un acto motor simple, atenciÓn y concentraciÓn, memoria y resoluciÓn de problemas complejos. Estos hallazgos indican la necesidad de continuar la inves-tigaciÓn para determinar los factores causales de la mayor disfunciÓn observada en el grupo de comienzo precoz. ZUSAMMENFASSUNG 48 Kinder (9 bis 15 Jahre alt) mit tonisch-klonischen KrÄmpfen wurden mit einer neuropsychologischen Testbatterie untersucht. Die Kinder mit einem FrÜhbeginn der AnfÄlle (vor dem Alter von 5 Jahren) zeigten sich bei 8 von 14 Tests der Serie deutlich beeintrÄchtigt im VerhÄltnis zu Kindern mit spÄterem Anfallsbeginn. Die Defekte traten bei Aufgaben auf, die folgende AnsprÜche stellten: Wiederholung einer einfachen motorischen Handlung, Aufmerksamkeit und Konzentration, GedÄchtnis und komplexes ProblemlÖsen. Diese Befunde deuten auf die Notwendigkeit weiterer Untersuchungen, um die ursÄchlichen Faktoren der grÖßeren Funktionseinbuße zu bestimmen, die bei Patienten mit frÜhem Anfallsbeginn beobachtet wird.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65238/1/j.1528-1157.1981.tb04102.x.pd

Examining the effects of adjuvant chemotherapy on cognition and the impact of any cognitive impairment on quality of life in colorectal cancer patients: study protocol

Background: Research suggests that chemotherapy can cause deficits in both patients’ objectively measured and self-reported cognitive abilities which can in turn affect their quality of life (QoL). The majority of research studies have used post-treatment retrospective designs or have not included a control group in prospective cohorts. This has limited the conclusions that can be drawn from the results. There have also been a disproportionate number of studies focussed on women with breast cancer, which has limited the generalisability of the results to other cancer populations. Aim: This study aims to identify the extent and impact of chemotherapy-induced cognitive decline in colorectal cancer patients. Possible associations with poorer QoL will also be explored. Design: This will be a longitudinal controlled cohort study. Questionnaires measuring subjective cognitive functioning, QoL, fatigue and mood, and neuropsychological assessments of objective cognitive function will be collected pre-, mid- and post- chemotherapy treatment from a consecutive sample of 78 colorectal cancer patients from five London NHS Trusts. A further 78 colorectal cancer surgery only patients will be assessed at equivalent time points; this will allow the researchers to compare the results of patients undergoing surgery, but not chemotherapy against those receiving both treatments. Pre- and post-chemotherapy difference scores will be calculated to detect subtle changes in cognitive function as measured by the objective neuropsychological assessments and the self-reported questionnaires. A standardised zscore will be computed for every patient on each neuropsychological test, and for each test at each time point. The post-chemotherapy score will then be subtracted from the pre-chemotherapy score to produce a relative difference score for each patient. ANCOVA will be used to compare mean difference z-scores between the chemotherapy and surgery-only groups while controlling for the effects of gender, age, depression, anxiety, fatigue and education. Discussion: The result from this study will indicate whether a decline in cognitive functioning can be attributed to chemotherapy or to disease, surgical or some other confounding factor. Identification of risk factors for cognitive deficits may be used to inform targeted interventions, in order to improve QoL and help patients’ cope

HIV-associated neurocognitive disorders in sub-Saharan Africa: a pilot study in Cameroon

<p>Abstract</p> <p>Background</p> <p>The disease burden of human immunodeficiency virus (HIV) - acquired immunodeficiency syndrome (AIDS) is highest in sub-Saharan Africa but there are few studies on the associated neurocognitive disorders in this region. The objectives of this study were to determine whether Western neuropsychological (NP) methods are appropriate for use in Cameroon, and to evaluate cognitive function in a sample of HIV-infected adults.</p> <p>Methods</p> <p>We used a battery of 19 NP measures in a cross-sectional study with 44 HIV+ adults and 44 demographically matched HIV- controls, to explore the validity of these NP measures in Cameroon, and evaluate the effect of viral infection on seven cognitive ability domains.</p> <p>Results</p> <p>In this pilot study, the global mean z-score on the NP battery showed worse overall cognition in the HIV+ individuals. Significantly lower performance was seen in the HIV+ sample on tests of executive function, speed of information processing, working memory, and psychomotor speed. HIV+ participants with AIDS performed worse than those with less advanced HIV disease.</p> <p>Conclusions</p> <p>Similar to findings in Western cohorts, our results in Cameroon suggest that HIV infection, particularly in advanced stages, is associated with worse performance on standardized, Western neurocognitive tests. The tests used here appear to be promising for studying NeuroAIDS in sub-Saharan Africa.</p