Asger Roer Pedersen

Salinity Induced Regime Shift in Shallow Brackish Lagoons

In brackish lagoons, Daphnia is replaced by calanoid copepods (Eurytemora affinis, Acartia spp.) and rotifers when a certain threshold (depending on, for instance, fish density) is reached. We hypothesize that loss of Daphnia induces a regime shift from clear to turbid at high nutrient concentrations. We conducted a factorial designed enclosure experiment with contrasting salinities (0–16‰), low fish predation (one three-spined stickleback, Gasterosteus aculeatus, m−2) and three levels of nutrient loading in a shallow brackish lagoon. A change point analysis suggests a strong regime shift from a clear to a turbid state at 6–8‰ salinity at low and high loading, but not for the control. From the low to the high salt regime, chlorophyll a (Chla), Chla:total phosphorus (TP) and Chla:total nitrogen (TN) ratios shifted highly significantly for all nutrient treatments, and the bacterioplankton production followed the changes in Chla. These changes occurred parallel with a shift from cladoceran and cyclopoid copepod to rotifer dominance. Monitoring data from 60 Danish brackish lagoons show increasing Chla with increasing TP and TN as well as interactive effects of TN and salinity, peaking at intermediate salinity. A relatively weak effect of salinity at low nutrient concentrations and the stronger effect at intermediate high salinity are in accordance with the experimental results. However, these data suggest a lower salinity threshold than in the experiment, which may be explained by a higher fish density. Our results have implications for the management of coastal lagoons both at present and in a future (predicted) warmer climate: (1) improved water quality can be obtained by reducing the nutrient loading or enhancing the freshwater input to a level triggering a shift to Daphnia dominance (typically <2‰), (2) fish manipulation is probably not a useful tool for brackish lagoons, unless the salinity is below the threshold for a potential shift to a clear Daphnia dominated state, and (3) more abrupt changes will expectedly occur in low-saline coastal lagoons at increasing salinity during summer in a future warmer climate.

Effects of resistance training and aerobic training on ambulation in chronic stroke.

ObjectiveThe aim of this study was to directly compare the effects of aerobic training (AT) with progressive resistance training (RT) after stroke to determine whether AT-induced fitness gains or RT-induced strength gains translate into improved ambulation across a 12-wk intervention and whether gains are retained 1 yr after cessation of formal training. DesignThis study is a randomized controlled 12-wk intervention trial with a 1-yr follow-up. Forty-three community-dwelling independent walkers with a chronic ischemic hemiparetic stroke were allocated to AT using a cycle ergometer (n = 13), RT using training machines (n = 14), or low-intensity sham training of the arms (n = 16). The main outcome measures were 6-min walk distance and fast 10-m walking speed. ResultsComparisons between AT, RT, and sham training revealed no clinically relevant effects on walking velocity or walking distance. Muscle strength improved after RT (P < 0.0001) and was preserved at 1-yr follow-up (P < 0.001). Aerobic capacity increased after AT (P < 0.001) but was lost during the follow-up observation period. ConclusionsImprovement of muscle strength or aerobic capacity using non–task-specific training methods does not result in improved ambulation in patients with chronic stroke. Muscle strength gains were maintained at follow-up, whereas all improvements of aerobic capacity were lost, indicating a long-lasting effect of intensive RT even without maintenance training.

The Effect of Age on Rehabilitation Outcome After Traumatic Brain Injury Assessed by the Functional Independence Measure (FIM)

Background. The impact of age on rehabilitation outcome after traumatic brain injury (TBI) as measured by changes in the Functional Independence Measure (FIM) has been addressed in several seemingly conflicting reports. Differences may be explained by different study populations and different ways of analyzing data. Objective. To investigate the role of data analysis in the interpretation of the age effect on rehabilitation outcome after TBI by comparing classical analyses of the total FIM score with a new item-wise analysis that unfolds the comprehensive amount of information contained in the FIM measurement otherwise concealed by the total score. Methods. We analyzed admission and discharge FIM data from 411 consecutive TBI patients admitted to inpatient rehabilitation during 1998-2011 by both methods. Results. The classical analysis indicated similar rehabilitation outcome in the 18 to 39, 40 to 64, and 65+ years age groups, which could be explained by selection of strong elderly patients and/or methodological problems with classical data analyses, whereas the item-wise analysis demonstrated profound age effect on most FIM items throughout the age interval covered. Conclusions. The item-wise analysis meets requirements of proper data analysis, avoids concealing diversity in rehabilitation outcome behind the total FIM score, and provides a flexible, informative, and clinically relevant data analysis.

Using EFA and FIM rating scales could provide a more complete assessment of patients with acquired brain injury

Abstract Purpose: In some hospitals, patients exhibit significant heterogeneity of function at admission and discharge. The current study aims to assess if concurrent usage of the Early Functional Assessment (EFA) and Functional Independence Measure (FIM®) is warranted and practical in rehabilitation centers with diverse patient groups and outcomes. Methods: This retrospective study examined a data set of all patients with concurrent EFA and FIM scores admitted to a single rehabilitation center (4076 scores from 1251 patients). The patients had acquired brain injury of multiple etiologies and a range of severities. Results: The EFA scale was more able to characterize the function of lower functioning patients according to the FIM while the FIM scale was more able to characterize the function of higher functioning patients according to the EFA. This was highlighted by 21% of assessments with the lowest FIM score (18) having corresponding EFA scores of 22–76 and 27% of assessments with the highest EFA score (>90) having corresponding FIM scores of 38–126. Conclusions: In rehabilitation centers with diverse patient groups and outcomes, the FIM and EFA scale could be used to characterize the heterogeneity of function in patients with acquired brain injury. The EFA/FIM scale could be used concurrently in certain patients providing a more complete view of patients throughout the rehabilitation process. Implications for Rehabilitation Rehabilitation scales can be administered on multiple occasions to track the progress of a patient throughout the rehabilitation process; however, a lot of popular scales (such as the FIM®) are limited containing ceiling and floor effects for higher and lower functioning patients, respectively. In rehabilitation centers with diverse patient groups and outcomes, the FIM and EFA scale could be used to characterize the heterogeneity of function in patients with acquired brain injury. Concurrent usage of the scales could be indicated for some patients and each scale could provide information that the other scale does not provide however the FIM and EFA scales should be administered solely for EFA scores >90 (FIM administered solely) and the lowest FIM scores (EFA administered solely).

Return to Work After Severe Traumatic Brain Injury: A Nationwide Follow-up Study.

Objective: To determine return to work (RTW) after severe traumatic brain injury (TBI) and to compare long-term labor market attachment (LMA) with the general population. Participants: All persons aged 18 to 64 years who received highly specialized neurorehabilitation after severe TBI between 2004 and 2012 (n = 637) were matched to general population controls on age, sex, preinjury employment status, educational level, and residence (n = 2497). Design: Nationwide follow-up study using weekly records on public assistance benefits. Main Measures: Both RTW and LMA were defined as having no public assistance benefits except education grants/leave. Stable LMA was defined as weeks with LMA of 75% or more. LMA among persons with severe TBI and controls was compared using multivariable conditional logistic regression. Results: RTW mainly occurred within first 2 years after severe TBI, with 30% of the people attempting RTW and 16% achieving stable LMA within 2 years. The prevalence of people with LMA decreased to 11% from 2½ years to 5 years postinjury. Adjusted odds ratios were 0.01 for LMA up to 2 years postinjury and 0.05 for stable LMA for persons with severe TBI compared with the general population. Conclusion: Both RTW and long-term LMA after severe TBI were low in Denmark when compared with the general population and other countries.

Skeletal muscle fiber characteristics and oxidative capacity in hemiparetic stroke survivors

Introduction: Skeletal muscle is changed after stroke, but conflicting data exist concerning muscle morphology and oxidative enzyme capacity. Methods: In 36 chronic stroke patients bilateral rectus femoris muscle biopsies were analyzed, and fiber type proportions and cross‐sectional areas were determined by ATPase histochemistry. Enzymatic concentrations of citrate synthase (CS) and 3‐Hydroxyacyl‐coenzymeA‐dehydrogenase (HAD) were determined using freeze‐dried muscle tissue. Findings were correlated with clinical outcomes. Results: In the paretic muscles the mean fiber area was smaller (P = 0.0004), and a lower proportion of type 1 fibers (P = 0.0016) and a higher proportion of type 2X fibers (P = 0.0002) were observed. The paretic muscle had lower CS (P = 0.013) and HAD concentrations (P = 0.037). Mean fiber area correlated with muscle strength (r = 0.43; P = 0.041), and CS concentration correlated with aerobic capacity (r = 0.47; P = 0.01). Conclusions: In stroke survivors there is a phenotypic shift toward more fatigable muscle fibers with reduced oxidative enzymatic capacity that relates to clinical outcomes. Muscle Nerve 53: 748–754, 2016

Diurnal and day-to-day variation of isometric muscle strength in myasthenia gravis.

Introduction: In patients with myasthenia gravis (MG), muscle strength is expected to decrease gradually during the day due to physical activities. Methods: Isometric muscle strength at the shoulder, knee, and ankle was determined in 10 MG patients (MGFA class II–IV) who were receiving usual medical treatment and in 10 control subjects. To determine diurnal and day‐to‐day variation, muscle strength was measured 4 times during day 1 and once at day 2. Results: Knee extension strength decreased during the day in both patients and controls. Neither diurnal nor day‐to‐day variation of muscle strength was higher in patients compared with controls. Conclusions: Patients with mild to moderate MG did not have increased variation of isometric muscle strength during the day or from day‐to‐day compared with controls. This suggests that isometric muscle performance can be determined with high reproducibility in similar groups of MG patients without regard to time of day. Muscle Nerve 53: 67–72, 2016

Cognitive status does not predict motor gain from post stroke constraint-induced movement therapy

BACKGROUND Constraint-Induced Movement Therapy (CIMT) is an evidence-based rehabilitation intervention for stroke. Several factors influence the motor gain from CIMT, including age and level of impairment. However, it is currently unknown to what extent cognitive status affects motor gain during CIMT. OBJECTIVE The aim of this study was to investigate whether cognitive and emotional status affects motor improvement during two weeks of CIMT and retention of the gain at three months follow-up. METHODS Twenty stroke patients (3-12 months post stroke) completed two weeks of CIMT. Motor performance was measured using the Wolf Motor Function Test (WMFT). Cognitive and emotional status was measured with a comprehensive neuropsychological test battery and a questionnaire on emotional status. All measures were performed at baseline, after two weeks of training, and at three months follow-up. RESULTS We found no significant correlation between cognitive or emotional measures at baseline and improvement in motor performance post training. Also, cognitive and emotional status did not correlate with motor retention at three months follow-up. CONCLUSIONS We found no evidence to support that cognitive performance in stroke patients can predict motor gain from CIMT.

Effect of transcranial direct current stimulation on neuroplasticity in corticomotor pathways of the tongue muscles

The aim of this study is to investigate effects of transcranial direct current stimulation (tDCS) on neuroplasticity in corticomotor pathways related to tongue muscles evoked by a training task using the tongue drive system (TDS). Using a crossover design, 13 healthy participants completed two sessions of tDCS while performing 30 min of TDS training. Sessions were spaced at least 2 weeks apart and participants randomly received anodal and sham tDCS stimulation in the first session and the other condition in the second session. Single and paired pulse transcranial magnetic stimulation was used to elicit motor evoked potentials (MEPs) of the tongue at three time-points: before, immediately after and 30 min after training. Participant-based reports of fun, pain, fatigue and motivation, level of difficulty and effort were evaluated on numerical rating scales. There was no consistent significant effect of anodal and sham stimulation on single or paired pulse stimulation MEP amplitude immediately or 30 min after TDS training. Irrespective of tDCS type, training with TDS induced cortical plasticity in terms of increased MEP amplitudes for higher stimulus intensities after 30 min compared with before and immediately after training. Participant-based reports revealed no significant difference between tDCS conditions for level of fun, fatigue, motivation, difficulty and level of effort but a significant increase in pain in the anodal condition, although pain level was low for both conditions. In conclusion, tongue MEP amplitudes appear to be sensitive to training with the tongue using TDS; however, anodal tDCS does not have an impact on training-evoked neuroplasticity of tongue corticomotor pathways.

Constraint-induced aphasia therapy in subacute neurorehabilitation

Background: Constraint-induced aphasia therapy (CIAT) is an intensive, short-term speech and language therapy. Previous research indicates that CIAT can lead to lasting improvements in chronic aphasia. CIAT in the subacute phase of recovery has only been sparsely investigated and only in modified versions compared to the original protocol. Aims: The aim of the current pilot study was to investigate unmodified CIAT in stroke patients in the subacute phase of recovery in the frame of an inpatient multidisciplinary neurorehabilitation program. Methods & Procedures: Eleven stroke patients with subacute aphasia completed 30 hr of CIAT in 10 weekdays. Language functions as well as the amount and quality of communication were assessed four times, before the control period, pre- and post-CIAT, and at follow-up. The primary outcome measure was Western Aphasia Battery. Secondary measures were the Danish adaptions of Communication Effectiveness Index and of Communication Effectiveness Profile. Issues of applicability were observed currently. Outcomes & Results: The improvement of neither language nor communication was statistically significant; however, all completing participants presented an improved or at least stable language function. CIAT was applied without modification of intensity and as group therapy to a subgroup of patients with aphasia in the first months after stroke in an inpatient multidisciplinary setting. Only one participant dropped out. Logistics, prioritisation of rehabilitation needs, and prioritisation of the resources of the patients and of the speech and language pathologists turned out to be issues of applicability. Conclusions: The improvement of language and of real-life communication was not statistically significant. The original protocol was followed demonstrating that CIAT can be applied without modifications in a subacute, inpatient multidisciplinary setting. Issues of applicability were identified.