Major efforts have been made world-wide to improve the ecological quality of shallow lakes by reducing external nutrient loading. These have often resulted in lower in-lake total phosphorus (TP) and ...decreased chlorophyll a levels in surface water, reduced phytoplankton biomass and higher Secchi depth. Internal loading delays recovery, but in north temperate lakes a new equilibrium with respect to TP often is reached after <10-15 years. In comparison, the response time to reduced nitrogen (N) loading is typically <5 years. Also increased top-down control may be important. Fish biomass often declines, and the percentage of piscivores, the zooplankton:phytoplankton biomass ratio, the contribution of Daphnia to zooplankton biomass and the cladoceran size all tend to increase. This holds for both small and relatively large lakes, for example, the largest lake in Denmark (40 km²), shallow Lake Arresø, has responded relatively rapidly to a ca. 76% loading reduction arising from nutrient reduction and top-down control. Some lakes, however, have proven resistant to loading reductions. To accelerate recovery several physico-chemical and biological restoration methods have been developed for north temperate lakes and used with varying degrees of success. Biological measures, such as selective removal of planktivorous fish, stocking of piscivorous fish and implantation or protection of submerged plants, often are cheap versus traditional physico-chemical methods and are therefore attractive. However, their long-term effectiveness is uncertain. It is argued that additional measures beyond loading reduction are less cost-efficient and often not needed in very large lakes. Although fewer data are available on tropical lakes these seem to respond to external loading reductions, an example being Lake Paranoá, Brazil (38 km²). However, differences in biological interactions between cold temperate versus warm temperate-subtropical-tropical lakes make transfer of existing biological restoration methods to warm lakes difficult. Warm lakes often have prolonged growth seasons with a higher risk of long-lasting algal blooms and dense floating plant communities, smaller fish, higher aggregation of fish in vegetation (leading to loss of zooplankton refuge), more annual fish cohorts, more omnivorous feeding by fish and less specialist piscivory. The trophic structures of warm lakes vary markedly, depending on precipitation, continental or coastal regions locations, lake age and temperature. Unfortunately, little is known about trophic dynamics and the role of fish in warm lakes. Since many warm lakes suffer from eutrophication, new insights are needed into trophic interactions and potential lake restoration methods, especially since eutrophication is expected to increase in the future owing to economic development and global warming.
Critical illness impairs physical function. The NONSEDA trial was a multicenter randomized trial, assessing non-sedation versus sedation during mechanical ventilation. The aim of this sub-study was ...to assess the effect of non-sedation on physical function.
All patients from one NONSEDA trial site were included. At ICU discharge and three months thereafter, survivors were assessed for physical function.
205 patients were included, 118 survived to follow-up, 116 participated (98%). Primary outcome: Three months after ICU-discharge, health-related quality of life (SF-36, physical component score) was similar (non-sedated 38.3 vs sedated 36.6, mean difference 1.7, 95% CI -1.7 to 5.1), as was function in activities of daily living (Barthel Index, non-sedated 19.5 vs sedated 18, median difference 1.5, 95% CI -0.2 to 3.2). Secondary outcomes: Non-sedated patients had a better Barthel Index at ICU-discharge (median 9 vs 4, median difference 5, 95% CI 2.5 to 7.5). At three months post-ICU discharge, the two groups did not differ regarding handgrip strength, walking distance, muscle size or biomechanical data.
Non-sedation did not lead to improved quality of life regarding physical function or better function in activities of everyday living. Non-sedated patients had a better physical recovery at ICU discharge.
Clinicaltrials.govNCT02034942, registered January 14., 2014.
•Non-sedation did not lead to significant improvements in quality of life.•Non-sedation did not improve ADL-function 3 months post ICU discharge.•Non-sedated patients had better ADL-function at ICU discharge.•Non-sedated patients generally had a better physical recovery at ICU discharge.
1. In some shallow lakes, Daphnia and other important pelagic consumers of phytoplankton undergo diel horizontal migration (DHM) into macrophytes or other structures in the littoral zone. Some ...authors have suggested that DHM reduces predation by fishes on Daphnia and other cladocerans, resulting in a lower phytoplankton biomass in shallow lakes than would occur without DHM. The costs and benefits of DHM, and its potential implications in biomanipulation, are relatively unknown, however.
2. In this review, we compare studies on diel vertical migration (DVM) to assess factors potentially influencing DHM (e.g. predators, food, light, temperature, dissolved oxygen, pH). We first provide examples of DHM and examine avoidance by Daphnia of both planktivorous (PL) fishes and predacious invertebrates.
3. We argue that DHM should be favoured when the abundance of macrophytes is high (which reduces planktivory) and the abundance of piscivores in the littoral is sufficient to reduce planktivores. Food in the littoral zone may favour DHM by daphnids, but the quality of these resources relative to pelagic phytoplankton is largely unknown.
4. We suggest that abiotic conditions, such as light, temperature, dissolved oxygen and pH, are less likely to influence DHM than DVM because weaker gradients of these conditions occur horizontally in shallow lakes relative to vertical gradients in deep lakes.
5. Because our understanding of DHM is rudimentary, we highlight potentially important research areas: studying a variety of systems, comparing temporal and spatial scales of DHM in relation to DVM, quantifying positive and negative influences of macrophytes, focusing on the role of invertebrate predation, testing the performance of cladocerans on littoral versus pelagic foods (quantity and quality), investigating the potential influence of temperature, and constructing comprehensive models that can predict the likelihood of DHM. Our ability to biomanipulate shallow lakes to create or maintain the desired clear water state will increase as we learn more about the factors initiating and influencing DHM.
Purpose
The purpose of this study is to compare dynamic and static whole-body (WB)
18
FNaF PET/CT scan methods used for analysis of bone plasma clearance in patients with chronic kidney ...disease-mineral and bone disorder (CKD-MBD).
Methods
Seventeen patients with CKD-MBD underwent a 60-min dynamic scan followed by a 30-min static WB scan. Tracer kinetics in four thoracic vertebrae were analysed using nonlinear regression and Patlak analysis using image-derived arterial input functions. The static WB scan was analysed using a simplified Patlak method requiring only a single data point in combination with a fixed y-intercept value (
V
0
), both obtained using a semi-population function. The semi-population function was constructed by combining a previously derived population input function in combination with data from venous blood samples. Static WB scan analysis data, obtained from the semi-population input functions, was compared with paired data obtained using dynamic input functions.
Results
Bone plasma clearance (
K
i
) from Patlak analyses correlated well with nonlinear regression analysis, but
K
i
results using Patlak analysis were lower than
K
i
results using nonlinear regression analysis. However, no significant difference was found between
K
i
obtained by static WB scans and
K
i
obtained by dynamic scans using nonlinear regression analysis (
p
= 0.29).
Conclusion
Bone plasma clearance measured from static WB scans correlates with clearance data measured by dynamic analysis. Static 18FNaF PET/CT scans can be applied in future studies to measure K
i
in patients with CKD-MBD, but the results should not be compared uncritically with results obtained by dynamic scan analysis.
Sleep patterns in critically ill patients’ polysomnographic sleep studies (PSG) are severely abnormal.
Purpose
We aimed to investigate the association of atypical sleep patterns, micro-sleep ...phenomena (sleep spindles and K-complexes) and rapid eye movement (REM) sleep with intensive care unit (ICU), in-hospital and 90-day mortality in conscious critically ill patients on mechanical ventilation.
Method
This was a prospective descriptive study. We analysed 52 PSGs recorded in conscious critically ill patients on mechanical ventilation. PSGs were scored according to standard classification when possible. Otherwise, modified classification proposed for scoring sleep in critically ill patients was used. The association of PSG findings with mortality was studied using logistic regression and Weibull model of survival analysis.
Results
The presence of atypical sleep patterns in accordance with modified sleep scoring classification was associated with higher odds for ICU mortality (odds ratio 11.63;
p
= 0.03). The absence of K-complexes was associated with higher odds for ICU mortality (odds ratio 11.63;
p
= 0.03), while the absence of sleep spindles was associated with higher odds for in-hospital (odds ratio 7.80;
p
= 0.02) and 90-day mortality (odds ratio 5.51;
p
= 0.02). Loss of sleep spindles was associated with higher mortality risk with cutoff point 90 days (hazard ratio 3.87;
p
= 0.03).
Conclusions
The presence of atypical sleep and absence of normal PSG sleep characteristics in conscious critically ill patients on mechanical ventilation indicates involvement of sleep producing brain structures in the pathological process and is associated with poor outcome.
Transcatheter aortic valve implantation (TAVI) has been approved for the treatment of severe aortic stenosis since 2008 and recent trials have shown that TAVI is at least non-inferior to surgical ...aortic valve replacement (SAVR) with regards to short-term efficacy and safety in patients across all surgical risk profiles. Prosthetic valve endocarditis of the transcatheter heart valve is a feared complication; data on the risk of infective endocarditis (IE) subsequent to TAVI are now gradually emerging.
We set forth to conduct a review of the incidence, diagnosis, microbial aetiologies, prevention, outcome and management of TAVI-IE.
From the MEDLINE database we included a total of 12 observational studies and five studies of long-term results from randomized controlled trials.
The incidence of TAVI-IE was reported to be between 0.7% and 3.0% per person-year. The most common microbes were reported to be enterococci, Staphylococcus aureus, streptococci and coagulase-negative staphylococci. International guidelines on prevention strategies of IE recommend good sanitary conditions including cutaneous care, good oral hygiene and good care of dialysis catheters. Antibiotic prophylaxis is recommended by guidelines prior to dental procedures in patients with TAVI; however, evidence is sparse. The majority of the patients included in this review with TAVI-IE had an indication for surgical intervention due to IE (50.0% or more); however, only a small subset of the patients underwent surgery (16.4% or less). The in-hospital mortality was around 25%, i.e. of the same order of magnitude as in prosthetic valve IE in general, but varied substantially between studies (from 11% to 64%).
The US Food and Drug Administration's approval of TAVI in patients at low surgical risk may change the characteristics of patients with TAVI, which may influence the incidence, management, and outcome of patients with TAVI-IE.
Cytokine networks in cerebrospinal fluid (CSF) are important to our understanding of several neuroinflammatory diseases. Knowledge about optimal handling of samples is limited but important to ...minimize bias and reduce costs in CSF biomarker studies. The aim of this study was to examine the effect of storage temperature and time delay from CSF sample collection until freezing on the concentration of 11 different cytokines thought to be associated with chronic pain. CSF samples from 21 individuals undergoing hip or knee arthroplasty under spinal anesthesia were divided between two tubes. One tube was stored and centrifuged (within 30 min) at room temperature, and one tube was stored in ice water and centrifuged (within 30 min) at 4 °C. Each tube was split into six vials that were frozen at −80 °C, 0.5, 1, 2, 3, 4, or 5 h after collection. Cytokines were analyzed using a multiplex panel. A random effect panel data regression was conducted for each biomarker including the variables of storage temperature until freezing and time delay. Four cytokines had detectable levels: Fractalkine, monocyte chemoattractant protein 1(MCP-1), interleukine 6 (IL-6), and interleukine 8 (IL-8). There was no significant effect of storage temperature and time delay on MCP-1, IL-6, or IL-8 concentrations. Fractalkine concentration showed no clear trend. No concentration differences were observed between samples kept in ice water and those at room temperature except at the 3-h time point, and there was no overall significant effect of time delay on fractalkine concentration. We found no clear effect of storage temperature and time delay up to five hours from sample collection until freezing on the CSF concentrations of fractalkine, MCP-1, IL-6, or IL-8.
•Prefreezing stability of Cytokines to temperature and time delay is unclear.•Optimal handling of CSF-samples is important to minimize bias in cytokine studies.•CSF-samples were kept at room temperature or in ice water until freezing.•CSF-samples were frozen at 30, 60, 120, 180, 240 and 300 min.•No effect of sample handling on CX3CL1, MCP-1, IL-6, IL-8 concentrations.
Background
Abolished circadian rhythm is associated with altered cognitive function, delirium, and as a result increased mortality in critically ill patients, especially in those who are mechanically ...ventilated. The causes are multifactorial, of which changes in circadian rhythmicity may play a role. Melatonin plays a crucial role as part of the circadian and sleep/wake cycle. Whether sedation effects circadian regulation is unknown. Hence, the objective of this study was to evaluate the melatonin concentration in critically ill patients randomized to sedation or non-sedation and to investigate the correlation with delirium.
Methods
All patients were included and randomized at the intensive care unit at the hospital of southwest Jutland, Denmark. Seventy-nine patients completed the study (41 sedated and 38 non-sedated). S-melatonin was measured 3 times per day, (03.00, 14.00, and 22.00), for 4 consecutive days in total, starting on the second day upon randomization/intubation. The study was conducted as a sub-study to the NON-SEDA study in which one hundred consecutive patients were randomized to sedation or non-sedation with a daily wake-up call (50 in each arm). Primary outcome: melatonin concentration in sedated vs. non-sedated patients (analyzed using linear regression). Secondary outcome: risk of developing delirium or non-medically induced (NMI) coma in sedated vs. non-sedated patients, assessed by CAM-ICU (Confusion Assessment Method for the Intensive Care Unit) analyzed using logistic regression.
Results
Melatonin concentration was suppressed in sedated patients compared to the non-sedated. All patients experienced an elevated peak melatonin level early on in the course of their critical illness (
p
= 0.01). The risk of delirium or coma (NMI) was significantly lower in the non-sedated group (OR 0.42 CI 0.27; 0.66
p
< 0.0001). No significant relationship between delirium development and suppressed melatonin concentration was established in this study (OR 1.004
p
= 0.29 95% CI 0.997; 1.010).
Conclusion
Melatonin concentration was suppressed in sedated, critically ill patients, when compared to non-sedated controls and the frequency of delirium was elevated in sedated patients.
Trail registration
Clinicaltrials.gov (NCT01967680) on October 23, 2013.
The cichlids in Lake Bosumtwi are under increasing pressure with a recent build-up in local fishing pressure. This study was conducted to assess the status and seasonal catch rates of fish species ...using gillnets over a two-year period. Four species and one introduced fish belonging to the Cichlidae family were encountered in the study. Coptodon discolor (Günther, 1903) was the most abundant species, making up 75.5% of the total fish caught (100.1 kg). Tilapia busumana (Günther, 1903) was the least abundant species, representing only 0.6% of biomass. Catch per unit effort was significantly affected by seasonality; however, species diversity, richness and evenness were not influenced by seasonal variations. The highest catch rates (975.62 g net
−1
night
−1
) were recorded in the minor wet season (August to November). No statistical differences were detected in the diversity indices estimated for all three seasons of study. The key physico-chemical parameters (conductivity, salinity, temperature and pH) measured were within the tolerance range for tilapia survival and growth, with the exception of dissolved oxygen that decreased below 3 mg l
−1
during the lake's deep mixing events in August. Overall, physico-chemical factors explained 75% of fish catches, with salinity levels correlating significantly with catch per unit effort.
Summary
1. Pigment analysis by high‐performance liquid chromatography (HPLC) combined with data analysis using the CHEMTAX program has proven to be a fast and precise method for determining the ...abundance of phytoplankton groups in marine environments. To determine whether CHEMTAX is applicable also to freshwater phytoplankton, 20 different species of freshwater algae were cultured and their pigment/chlorophyll a (Chl a) ratios determined for exponential growth at three different light intensities and for stationary growth at one light intensity.
2. The different treatments had a relatively insignificant impact on the absolute values of the diagnostic pigment/Chl a ratios, with the exception of cyanobacteria and cryptophytes for which the zeaxanthin/Chl a and alloxanthin/Chl a ratios varied considerably.
3. The pigment ratios were tested on samples collected in six different eutrophic Danish lakes during two summer periods using the CHEMTAX program to calculate the biomass of the phytoplankton groups as Chl a. The CHEMTAX‐derived seasonal changes in Chl a biomass corresponded well with the volume of the microscopically determined phytoplankton groups. More phytoplankton groups were detected by the pigment method than by the microscopic method.
4. Applying the pigment ratios developed in this study, the pigment method can be used to determine the abundance of the individual phytoplankton groups, which are useful as biological water quality indicators when determining the ecological status of freshwater lakes.
![Comparison of [18F] NaF PET...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2191-219X/small "Comparison of [18F] NaF PET/CT dynamic analysis methods and a static analysis method including derivation of a semi-population input function for site-specific measurements of bone formation in a population with chronic kidney disease-mineral and bone disorder")
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