Lag time determination in DEC measurements with PTR-MS

The disjunct eddy covariance (DEC) method has emerged as a popular technique for micrometeorological flux measurements of volatile organic compounds (VOCs). It has usually been combined with proton transfer reaction mass spectrometry (PTR-MS), an online technique for VOC concentration measurements. However, the determination of the lag time between wind and concentration measurements has remained an important challenge. To address this issue, we studied the effect of different lag time methods on DEC fluxes. The analysis was based on both actual DEC measurements with PTR-MS and simulated DEC data derived from high frequency H<sub>2</sub>O measurements with an infrared gas analyzer. Conventional eddy covariance fluxes of H<sub>2</sub>O served as a reference in the DEC simulation. The individual flux measurements with PTR-MS were rather sensitive to the lag time methods, but typically this effect averaged out when the median fluxes were considered. The DEC simulation revealed that the maximum covariance method was prone to overestimation of the absolute values of fluxes. The constant lag time methods, one based on a value calculated from the sampling flow and the sampling line dimensions and the other on a typical daytime value, had a tendency to underestimate. The visual assessment method and our new averaging approach utilizing running averaged covariance functions did not yield statistically significant errors and thus fared better than the habitual choice, the maximum covariance method. Given this feature and the potential for automatic flux calculation, we recommend using the averaging approach in DEC measurements with PTR-MS. It also seems well suited to conventional eddy covariance applications when measuring fluxes near the detection limit

Comparison of Diatoms and Dinoflagellates from Different Habitats as Sources of PUFAs

Recent studies have clearly shown the importance of omega-3 (ω-3) and omega-6 (ω-6) polyunsaturated fatty acids (PUFAs) for human and animal health. The long-chain eicosapentaenoic acid (EPA; 20:5ω-3) and docosahexaenoic acid (DHA; 22:6ω-3) are especially recognized for their nutritional value, and ability to alleviate many diseases in humans. So far, fish oil has been the main human source of EPA and DHA, but alternative sources are needed to satisfy the growing need for them. Therefore, we compared a fatty acid profile and content of 10 diatoms and seven dinoflagellates originating from marine, brackish and freshwater habitats. These two phytoplankton groups were chosen since they are excellent producers of EPA and DHA in aquatic food webs. Multivariate analysis revealed that, whereas the phytoplankton group (46%) explained most of the differences in the fatty acid profiles, habitat (31%) together with phytoplankton group (24%) explained differences in the fatty acid contents. In both diatoms and dinoflagellates, the total fatty acid concentrations and the ω-3 and ω-6 PUFAs were markedly higher in freshwater than in brackish or marine strains. Our results show that, even though the fatty acid profiles are genetically ordered, the fatty acid contents may vary greatly by habitat and affect the ω-3 and ω-6 availability in food webs

Marine Cryptophytes Are Great Sources of EPA and DHA

Microalgae have the ability to synthetize many compounds, some of which have been recognized as a source of functional ingredients for nutraceuticals with positive health effects. One well-known example is the long-chain polyunsaturated fatty acids (PUFAs), which are essential for human nutrition. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the two most important long-chain omega-3 (-3) PUFAs involved in human physiology, and both industries are almost exclusively based on microalgae. In addition, algae produce phytosterols that reduce serum cholesterol. Here we determined the growth rates, biomass yields, PUFA and sterol content, and daily gain of eight strains of marine cryptophytes. The maximal growth rates of the cryptophytes varied between 0.34-0.70 divisions day(-1), which is relatively good in relation to previously screened algal taxa. The studied cryptophytes were extremely rich in -3 PUFAs, especially in EPA and DHA (range 5.8-12.5 and 0.8-6.1 mu g mg dry weight(-1), respectively), but their sterol concentrations were low. Among the studied strains, Storeatula major was superior in PUFA production, and it also produces all PUFAs, i.e., -linolenic acid (ALA), stearidonic acid (SDA), EPA, and DHA, which is rare in phytoplankton in general. We conclude that marine cryptophytes are a good alternative for the ecologically sustainable and profitable production of health-promoting lipids.Peer reviewe

Suitability of Phytosterols Alongside Fatty Acids as Chemotaxonomic Biomarkers for Phytoplankton

The composition and abundance of phytoplankton is an important factor defining ecological status of marine and freshwater ecosystems. Chemotaxonomic markers (e.g., pigments and fatty acids) are needed for monitoring changes in a phytoplankton community and to know the nutritional quality of seston for herbivorous zooplankton. Here we investigated the suitability of sterols along with fatty acids as chemotaxonomic markers using multivariate statistics, by analyzing the sterol and fatty acid composition of 10 different phytoplankton classes including altogether 37 strains isolated from freshwater lakes. We were able to detect a total of 47 fatty acids and 29 sterols in our phytoplankton samples, which both differed statistically significantly between phytoplankton classes. Due to the high variation of fatty acid composition among Cyanophyceae, taxonomical differentiation increased when Cyanophyceae were excluded from statistical analysis. Sterol composition was more heterogeneous within class than fatty acids and did not improve separation of phytoplankton classes when used alongside fatty acids. However, we conclude that sterols can provide additional information on the abundance of specific genera within a class which can be generated by using fatty acids. For example, whereas high C-16 omega-3 PUFA (polyunsaturated fatty acid) indicates the presence of Chlorophyceae, a simultaneous high amount of ergosterol could specify the presence of Chlamydomonas spp. (Chlorophyceae). Additionally, we found specific 4 alpha-methyl sterols for distinct Dinophyceae genera, suggesting that 4a-methyl sterols can potentially separate freshwater dinoflagellates from each other.Peer reviewe

Macular edema after cataract surgery in eyes with and without pseudoexfoliation syndrome

Background: The purpose of the study was to identify macular edema after cataract surgery in eyes with and without pseudoexfoliation syndrome. The study was a post-hoc analysis of a randomized, double-blind, prospective single-center study. Patients were enrolled between January 2016 and October 2016 as per the national guidelines for the management of cataract in the Department of Ophthalmology, Kymenlaakso Central Hospital, Kotka, Finland. Methods: One hundred and fifty-six eyes of 149 patients undergoing routine cataract surgery. Postoperatively anti-inflammatory medication was either dexamethasone (N = 78) or diclofenac (N = 78). Spectral domain optical coherence tomography imaging and laser flare meter measurement of the anterior chamber were conducted before surgery and at the control visit 28 days postoperatively. Results: Baseline variables were comparable between eyes with pseudoexfoliation syndrome (N = 32) and those without (N = 124), except for intraocular pressure (P = 0.002) and glaucoma medication (P <0.001). In patients having pseudoexfoliation syndrome, central retinal thickness increase (mean +/- standard error of the mean) was 63.3 +/- 35.5 mu m for dexamethasone and 17.6 +/- 5.8 mu m for diclofenac, compared to 28.9 +/- 8.0 mu m (P = NS) and 6.9 +/- 1.3 mu m (P = 0.014) in eyes without pseudoexfoliation syndrome, respectively. Aqueous flare at 28 days was 25.8 +/- 5.4 pu/ms for patients with pseudoexfoliation syndrome and 18.3 +/- 1.8 pu/ms for those without (P = 0.030). Best corrected visual acuity gain and best corrected visual acuity at 28 days were less in patients having pseudoexfoliation syndrome compared to those without (0.39 +/- 0.07 vs 0.59 +/- 0.03 decimals, P = 0.007; and 0.77 +/- 0.06 vs 0.92 +/- 0.03 decimals, P = 0.008, respectively). Conclusion: Eyes with pseudoexfoliation syndrome may be predisposed to an increased aqueous flare and macular edema after cataract surgery. This study outlines the need to determine the optimal anti-inflammatory medication after cataract surgery in patients with pseudoexfoliation syndrome.Peer reviewe

Selective Fatty Acid Retention and Turnover in the Freshwater Amphipod Pallaseopsis quadrispinosa

Gammarid amphipods are a crucial link connecting primary producers with secondary consumers, but little is known about their nutritional ecology. Here we asked how starvation and subsequent feeding on different nutritional quality algae influences fatty acid retention, compound-specific isotopic carbon fractionation, and biosynthesis of ω-3 and ω-6 polyunsaturated fatty acids (PUFA) in the relict gammarid amphipod Pallaseopsis quadrispinosa. The fatty acid profiles of P. quadrispinosa closely matched with those of the dietary green algae after only seven days of refeeding, whereas fatty acid patterns of P. quadrispinosa were less consistent with those of the diatom diet. This was mainly due to P. quadrispinosa suffering energy limitation in the diatom treatment which initiated the metabolization of 16:1ω7 and partly 18:1ω9 for energy, but retained high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) similar to those found in wild-caught organisms. Moreover, α-linolenic acid (ALA) from green algae was mainly stored and not allocated to membranes at high levels nor biosynthesized to EPA. The arachidonic acid (ARA) content in membrane was much lower than EPA and P. quadrispinosa was able to biosynthesize long-chain ω-6 PUFA from linoleic acid (LA). Our experiment revealed that diet quality has a great impact on fatty acid biosynthesis, retention and turnover in this consumer

Selective Fatty Acid Retention and Turnover in the Freshwater Amphipod Pallaseopsis quadrispinosa

Gammarid amphipods are a crucial link connecting primary producers with secondary consumers, but little is known about their nutritional ecology. Here we asked how starvation and subsequent feeding on different nutritional quality algae influences fatty acid retention, compound-specific isotopic carbon fractionation, and biosynthesis of ω-3 and ω-6 polyunsaturated fatty acids (PUFA) in the relict gammarid amphipod Pallaseopsis quadrispinosa. The fatty acid profiles of P. quadrispinosa closely matched with those of the dietary green algae after only seven days of refeeding, whereas fatty acid patterns of P. quadrispinosa were less consistent with those of the diatom diet. This was mainly due to P. quadrispinosa suffering energy limitation in the diatom treatment which initiated the metabolization of 16:1ω7 and partly 18:1ω9 for energy, but retained high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) similar to those found in wild-caught organisms. Moreover, α-linolenic acid (ALA) from green algae was mainly stored and not allocated to membranes at high levels nor biosynthesized to EPA. The arachidonic acid (ARA) content in membrane was much lower than EPA and P. quadrispinosa was able to biosynthesize long-chain ω-6 PUFA from linoleic acid (LA). Our experiment revealed that diet quality has a great impact on fatty acid biosynthesis, retention and turnover in this consumer

Symptomatic plate removal after treatment of facial fractures

Aims: To identify the rates and reasons for plate removal (PR) among patients treated for facial fractures. Materials and methods: A retrospective review of files of 238 patients. Results: Forty-eight patients (20.2%) had plates removed. The reason for removal was objective in 33.3% and subjective in 29.2%. The most common subjective reason was cold sensitivity, and the most common objective reason was wound dehiscence/infection. Women had PR for subjective reasons more often than men (p = 0.018). Removal was performed more often for subjective reasons after zygomatico-orbital fractures than after mandibular fractures (p = 0.002). Plates inserted in the mandible from an intraoral approach were removed more frequently than extraorally inserted mandibular plates, intraorally inserted maxillary plates, and extraorally inserted plates in other locations (p < 0.001). Orbital rim plates had a higher risk of being removed than maxillary or frontal bone plates (p = 0.02). Conclusions: Subjective discomfort is a notable reason for PR among Finnish patients, suggesting that the cold climate has an influence on the need for removal. Patients receiving mandibular osteosynthesis with miniplates from an intraoral approach are at risk of hardware removal because of wound dehiscence/infection and loose/broken hardware, reminding us that more rigid fixation devices should not be forgotten despite the widespread use of miniplates. (C) 2010 European Association for Cranio-Maxillo-Facial Surger

Metabolic plasticity of mixotrophic algae is key for their persistence in browning environments

Light availability is the main regulator of primary production, shaping photosynthetic communities and their production of ecologically important biomolecules. In freshwater ecosystems, increasing dissolved organic carbon (DOC) concentrations, commonly known as browning, leads to lower light availability and the proliferation of mixotrophic phytoplankton. Here, a mixotrophic algal species (Cryptomonas sp.) was grown under five increasing DOC concentrations to uncover the plastic responses behind the success of mixotrophs in browning environments and their effect in the availability of nutritionally important biomolecules. In addition to the browning treatments, phototrophic, heterotrophic and mixotrophic growth conditions were used as controls. Despite reduced light availability, browning did not impair algal growth compared to phototrophic conditions. Comparative transcriptomics showed that genes related to photosynthesis were down-regulated, whereas phagotrophy gene categories (phagosome, lysosome and endocytosis) were up-regulated along the browning gradient. Stable isotope analysis of phospholipid fractions validated these results, highlighting that the studied mixotroph increases its reliance on heterotrophic processes with browning. Metabolic pathway reconstruction using transcriptomic data suggests that organic carbon is acquired through phagotrophy and used to provide energy in conjunction with photosynthesis. Although metabolic responses to browning were observed, essential fatty acid content was similar between treatments while sterol content was slightly higher upon browning. Together, our results provide a mechanistic model of how a mixotrophic alga responds to browning and how such responses affect the availability of nutritionally essential biomolecules for higher trophic levels.Peer reviewe