| 1. |
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| 2. |
- Frisk, Pia, 1968-
(author)
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Surveys and services : The feasibility of conducting research in Swedish community pharmacies
- 2018
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Doctoral thesis (other academic/artistic)abstract
- For the past decades, there has been a shift in community pharmacy practice from dispensing and compounding towards provision of pharmacy services. Research is important to generate evidence for new services within pharmacy practice. Pharmacy practice research can be divided in two main themes: research related to pharmacy as a data source and to the pharmacy as the object of research, respectively.The purpose of this thesis is to increase the understanding of the conditions required for successful involvement of Swedish community pharmacy staff in pharmacy-based research, and to evaluate the data generated through a certain type of research: pharmacy-based patient surveys on drug utilization.Specific aims were to evaluate if there is a selection bias in drug utilization surveys conducted in Swedish community pharmacies, to explore the experiences of pharmacists either conducting the surveys or recruiting patients to research on adherence-promoting services, and to describe barriers and facilitators to conducting research in community pharmacies.Data were collected via pharmacy-based patient surveys, dispensing data, individual interviews, a cross-sectional staff survey and focus group interviews.In community pharmacy-based surveys or services research, with the dispensed drug as the trigger for inclusion, patients aged 75 years or older are underrepresented since they less often visit the pharmacy to redeem their prescriptions themselves. Due to their perceived workload, dispensing pharmacists sometimes avoid including patients perceived as complex due to age, polypharmacy or communication difficulties. These processes contribute to a healthy selection effect in both types of research and pharmacy services not reaching the patients in most need of support with their medication.The pharmacists were generally positive to conducting surveys and being involved in services research, but reported a perceived lack of sufficient communication and research skills, and a lack of time.Since competing commercial priorities hamper pharmacists’ research involvement, separate research funding is an important facilitator. For surveys to include all eligible patients, services to be relevant for both practice and patients and to target the patients in most need of support with their medication, research collaboration with healthcare, other professions and across pharmacies is also necessary.
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| 3. |
- Andrén, Elinor, et al.
(author)
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Holocene climate and environmental change in north-eastern Kamchatka (Russian Far East), inferred from a multi-proxy study of lake sediments
- 2015
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In: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 134, s. 41-54
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Journal article (peer-reviewed)abstract
- A sediment record from a small lake in the north-eastern part of the Kamchatka Peninsula has been investigated in a multi-proxy study to gain knowledge of Holocene climatic and environmental change. Pollen, diatoms, chironomids and selected geochemical parameters were analysed and the sediment record was dated with radiocarbon. The study shows Holocene changes in the terrestrial vegetation as well as responses of the lake ecosystem to catchment maturity and multiple stressors, such as climate change and volcanic eruptions. Climate change is the major driving force resulting in the recorded environmental changes in the lake, although recurrent tephra deposition events also contributed. The sediment record has an age at the base of about 10,000 cal yrs BP, and during the first 400 years the climate was cold and the lake exhibited extensive ice-cover during winter and relatively low primary production. Soils in the catchment were poor with shrub alder and birches dominatingthe vegetation surrounding the lake. At about 9600–8900 cal yrs BP the climate was cold and moist, and strong seasonal wind stress resulted in reduced ice-cover and increased primary production. After ca. 8900 cal yrs BP the forest density increased around the lake, runoff decreased in a generally drier climate resulting in decreasedprimary production in the lake until ca. 7000 cal yrs BP. This generally dry climate was interrupted by a brief climatic perturbation, possibly attributed to the 8.2 ka event, indicating increasingly windy conditions with thick snow cover, reduced ice-cover and slightly elevated primary production in the lake. The diatom record shows maximum thermal stratification at ca. 6300–5800 cal yrs BP and indicates together with the geochemical proxies a dry and slightly warmer climate resulting in a high productive lake. The most remarkably change in the catchment vegetation occurred at ca. 4200 cal yrs BP in the form of a conspicuous increase in Siberian dwarf pine (Pinus pumila), indicating a shift to a cooler climate with a thicker and more long-lasting snow cover. Thisvegetational change was accompanied by marked shifts in the diatom and chironomid stratigraphies, which are also indicative of colder climate and more extensive ice-cover.
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| 4. |
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| 5. |
- Berglund, B. E., et al.
(author)
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Holocene forest dynamics and climate changes in the Abisko area, northern Sweden : the Sonesson model of vegetation history reconsidered and confirmed
- 1996
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In: Ecological Bulletins. - 0346-6868. ; 1996:1, s. 15-30
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Journal article (peer-reviewed)abstract
- A new palaeoecological and palaeoclimatic project in the subalpine Abisko area, N Scandes, founded upon the pollen zone system defined by Sonesson is described. This model of vegetation history has been confirmed, although the chronology is partly revised. Sonesson's pollen diagrams are combined with new results from a lake sediment sequence at the tree-limit, which include sedimentologic, mineral magnetic, oxygen isotope and plant macrofossil studies. Since the deglaciation at c9000-8500 14C yr BP the vegetation of the Abisko area has generally been dominated by a subalpine birch Betula woodland tundra. The cliamte has generally been subarctic-oceanic since the deglaciation except for the period c.5500-3500 BP when temperate-continental conditions prevailed. This climatic development differs from the situation in the central Scandes.
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| 6. |
- Bjorck, S, et al.
(author)
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Synchronized terrestrial-atmospheric deglacial records around the North Atlantic
- 1996
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In: SCIENCE. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075. ; 274:5290, s. 1155-1160
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Journal article (other academic/artistic)abstract
- On the basis of synchronization of three carbon-14 (C-14)-dated lacustrine sequences from Sweden With tree ring and ice core records, the absolute age of the Younger Dryas-Preboreal climatic shift was determined to be 11,450 to 11,390 +/- 80 years before
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| 7. |
- Boström, Emma, 1975-
(author)
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Pharmacokinetics and Pharmacodynamics of Oxycodone and Morphine with Emphasis on Blood-Brain Barrier Transport
- 2007
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Doctoral thesis (other academic/artistic)abstract
- The pharmacokinetics and pharmacodynamics of oxycodone and morphine was investigated and related to the transport across the blood-brain barrier (BBB) in rats. The influence of a P-glycoprotein (P-gp) inhibitor on the plasma pharmacokinetics and pharmacodynamics of oxycodone was evaluated. Microdialysis experiments were conducted to evaluate the unbound pharmacokinetics, including the rate and extent of transport across the BBB, of oxycodone and morphine. Mathematical models were used to assess the pharmacokinetics and also the relationship between pharmacokinetics and pharmacodynamics of the drugs.Oxycodone clearance, volume of distribution at steady-state, half-life, total brain tissue concentrations and tail-flick latency were all unaffected when a P-gp inhibitor was co-administered with oxycodone as compared to a control group. The lack of differences between the groups indicates that oxycodone BBB transport is not affected by P-gp inhibition. Investigating the unbound concentrations of oxycodone in brain and blood using microdialysis revealed an exciting finding. At steady-state, the unbound concentration in brain was 3 times higher than in blood (i.e. a Kp,uu of 3), indicating that active influx is involved in the BBB transport of oxycodone. In contrast, the Kp,uu of morphine was estimated to 0.56, which is an indication that active efflux mechanisms are involved in the BBB transport of morphine. This means that based on the same unbound concentration in blood, an approximately 6-fold higher unbound concentration of oxycodone compared to morphine will be reached in the brain. Using pharmacokinetic-pharmacodynamic modelling, the unbound brain concentrations of oxycodone and morphine were correlated to the tail-flick latency in vivo. The relative potency of the drugs was found to be concentration dependent with an infliction point of 55 nM.In summary, this thesis emphasise the importance of taking the local brain pharmacokinetics into consideration when investigating the pharmacokinetics and the pharmacokinetic-pharmacodynamic relationships of centrally acting drugs.
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| 8. |
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| 9. |
- Chaurasia, Chandra S., et al.
(author)
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AAPS-FDA workshop white paper : microdialysis principles, application and regulatory perspectives
- 2007
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In: Pharmaceutical research. - : Springer Science and Business Media LLC. - 0724-8741 .- 1573-904X. ; 24:5, s. 1014-1025
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Journal article (peer-reviewed)abstract
- Many decisions in drug development and medical practice are based on measuring blood concentrations of endogenous and exogenous molecules. Yet most biochemical and pharmacological events take place in the tissues. Also, most drugs with few notable exceptions exert their effects not within the bloodstream, but in defined target tissues into which drugs have to distribute from the central compartment. Assessing tissue drug chemistry has, thus, for long been viewed as a more rational way to provide clinically meaningful data rather than gaining information from blood samples. More specifically, it is often the extracellular (interstitial) tissue space that is most closely related to the site of action (biophase) of the drug. Currently microdialysis (microD) is the only tool available that explicitly provides data on the extracellular space. Although microD as a preclinical and clinical tool has been available for two decades, there is still uncertainty about the use of microD in drug research and development, both from a methodological and a regulatory point of view. In an attempt to reduce this uncertainty and to provide an overview of the principles and applications of microD in preclinical and clinical settings, an AAPS-FDA workshop took place in November 2005 in Nashville, TN, USA. Stakeholders from academia, industry and regulatory agencies presented their views on microD as a tool in drug research and development.
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| 10. |
- Chaurasia, Chandra S., et al.
(author)
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AAPS-FDA Workshop White Paper : microdialysis principles, application, and regulatory perspectives
- 2007
-
In: Journal of clinical pharmacology. - : Wiley. - 0091-2700 .- 1552-4604. ; 47:5, s. 589-603
-
Journal article (peer-reviewed)abstract
- Many decisions in drug development and medical practice are based on measuring blood concentrations of endogenous and exogenous molecules. Yet most biochemical and pharmacological events take place in the tissues. Also, most drugs with few notable exceptions exert their effects not within the bloodstream, but in defined target tissues into which drugs have to distribute from the central compartment. Assessing tissue drug chemistry has, thus, for long been viewed as a more rational way to provide clinically meaningful data rather than gaining information from blood samples. More specifically, it is often the extracellular (interstitial) tissue space that is most closely related to the site of action (biophase) of the drug. Currently microdialysis (μD) is the only tool available that explicitly provides data on the extracellular space. Although μD as a preclinical and clinical tool has been available for two decades, there is still uncertainty about the use of μD in drug research and development, both from a methodological and a regulatory point of view. In an attempt to reduce this uncertainty and to provide an overview of the principles and applications of μD in preclinical and clinical settings, an AAPS-FDA workshop took place in November 2005 in Nashville, TN, USA. Stakeholders from academia, industry and regulatory agencies presented their views on μD as a tool in drug research and development.
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| 11. |
- Dahl, Tais W., et al.
(author)
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Devonian rise in atmospheric oxygen correlated to the radiations of terrestrial plants and large predatory fish
- 2010
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 107:42, s. 17911-17915
-
Journal article (peer-reviewed)abstract
- The evolution of Earth's biota is intimately linked to the oxygenation of the oceans and atmosphere. We use the isotopic composition and concentration of molybdenum (Mo) in sedimentary rocks to explore this relationship. Our results indicate two episodes of global ocean oxygenation. The first coincides with the emergence of the Ediacaran fauna, including large, motile bilaterian animals, ca. 550-560 million year ago (Ma), reinforcing previous geochemical indications that Earth surface oxygenation facilitated this radiation. The second, perhaps larger, oxygenation took place around 400 Ma, well after the initial rise of animals and, therefore, suggesting that early metazoans evolved in a relatively low oxygen environment. This later oxygenation correlates with the diversification of vascular plants, which likely contributed to increased oxygenation through the enhanced burial of organic carbon in sediments. It also correlates with a pronounced radiation of large predatory fish, animals with high oxygen demand. We thereby couple the redox history of the atmosphere and oceans to major events in animal evolution.
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| 12. |
- Dahl, Tais W., et al.
(author)
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Reply to Butterfield : The Devonian radiation of large predatory fish coincided with elevated athospheric oxygen levels
- 2011
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 108:9, s. E29-
-
Journal article (peer-reviewed)abstract
- We welcome this opportunity to clarify the conclusions and implications of our recent publication in PNAS. Butterfield (1) raises four issues regarding the oxygenation of the Paleozoic Earth's surface and its correlation to animal evolution. Our geochemical and paleontological data supported ocean oxygenation in the Silurian-Early Devonian (2), a critical transition in Earth history that influenced biogeochemical cycles and biological systems. First, Butterfield suggests that evidence of charcoal in late Silurian rocks is incompatible with our claim that the earlier Paleozoic atmosphere had oxygen levels below 50% PAL (present-day atmospheric level). This counterargument rests on the assumption that the “fire window” of 62–166% PAL oxygen is well defined, but this is not the case (3).
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| 13. |
- Edvardsson, Johannes, et al.
(author)
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Exploring climate forcing of growth depression in subfossil South Swedish bog pines using stable isotopes
- 2014
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In: Dendrochronologia. - : Elsevier BV. - 1125-7865. ; 32:1, s. 55-61
-
Journal article (peer-reviewed)abstract
- Comparison between growth variability, based on ring-width (RW) analysis, and moisture-sensitive signals in tree-ring carbon and oxygen stable-isotope composition provides increased understanding of how climate and hydrology influenced bog pines (Pinus sylvestris L) at two sites in southern Sweden during the mid- and late Holocene. Tree-ring sequences from two subfossil trees collected at raised bogs having different hydrology and catchment size were analyzed to probe the stable-isotope signals associated with two bog-wide episodes of growth depression, one during the Holocene Thermal Maximum and the other during the Neoglacial Transition. The occurrence of lower whole-wood delta C-13 and cellulose 813C and 8180 values immediately prior to the onset of growth depression in both trees, suggesting increased atmospheric relative humidity, is consistent with the notion that excessive effective moisture impeded tree growth. Correlation analysis indicates that the growth response lagged about three years behind the decline in delta C-13 and delta O-18 values in each tree, possibly reflecting relatively slow rise in the local water table in response to wetter climate. (c) 2013 Elsevier GmbH. All rights reserved.
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| 14. |
- Edwards, Thomas W. D., et al.
(author)
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Seasonal variability in Northern Hemisphere atmospheric circulation during the Medieval Climate Anomaly and the Little Ice Age
- 2017
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In: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 165, s. 102-110
-
Journal article (peer-reviewed)abstract
- Here we report new reconstructions of winter temperature and summer moisture during the past millennium in southeastern Sweden, based on stable-isotope data from a composite tree-ring sequence, that further enhances our knowledge and understanding of seasonal climate variability in the Northern Hemisphere over the past millennium. Key features of these new climate proxy records include evidence for distinctive fluctuations in winter temperature in SE Sweden, superimposed upon the general pattern of cooling between the so-called Medieval Climate Anomaly (MCA) of the early millennium and the Little Ice Age (LIA) of the late millennium, as well as evidence for sustained summer wetness during the MCA, followed by drier and less variable conditions during the LIA. We also explore these new records within a circumpolar spatial context by employing self-organizing map analysis of meteorological reanalysis data to identify potential modern analogues of mid-tropospheric synoptic circulation types in the Northern Hemisphere extratropics that can reconcile varying seasonal climate states during the MCA and LIA in SE Sweden with less variable conditions in southwestern Canada, as portrayed by paleoclimate records developed in the same manner in an earlier study.
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| 15. |
- Gill, Benjamin C., et al.
(author)
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Redox dynamics of later Cambrian oceans
- 2021
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In: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182. ; 581
-
Journal article (peer-reviewed)abstract
- A growing body of evidence suggests that the deep oceans during the early Paleozoic Era were widely oxygen deficient, despite evidence for increased marine oxygenation during the Neoproterozoic. However, the temporal and geographic extents and dynamics of reducing marine conditions within these oceans are not well understood. Here, we investigate marine redox history during the Drumian through the earliest Jiangshanian International Stages of the Cambrian Period, using concentrations of redox-sensitive metals (vanadium, uranium, and molybdenum), iron speciation, and Mo isotope stratigraphy of the Alum Shale Formation of Scandinavia. These data suggest a major perturbation occurred in trace metal cycling during the later Cambrian Period that was linked to a transient change in marine redox conditions coincident with the well-known Steptoean Positive Isotope Excursion or SPICE. The δ98Mo measurements of the Alum shale show systematic variations during the interval that contains the SPICE which are broadly consistent with a transient expansion of sulfidic, reducing marine environments — indicating a significant exacerbation of an already-common condition during the Cambrian Period. Additionally, iron speciation data record a local transition from predominantly anoxic, ferruginous (Fe+2 containing) to anoxic, euxinic (sulfide containing) water column conditions near the initiation of the SPICE. Trace metal abundances, however, appear to decline well before the start of the SPICE, suggesting an earlier initiation of the global expansion of reducing environments. More broadly, our data and modeling support the notion that significant portions of the oceans remained oxygen deficient throughout the later portion of the Cambrian, and that these oceans were also prone to transient intervals of more reducing conditions similar to the Oceanic Anoxic Events of the Mesozoic.
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| 16. |
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| 17. |
- Hammarlund, Dan, et al.
(author)
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Late Holocene expansion of Siberian dwarf pine (Pinus pumila) in Kamchatka in response to increased snow cover as inferred from lacustrine oxygen-isotope records
- 2015
-
In: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 134:SI, s. 91-100
-
Journal article (peer-reviewed)abstract
- Holocene records of cellulose-inferred lake-water δ18O were produced from two lake-sediment sequences obtained in central and northern Kamchatka, Russian Far East. The sediment records share similar fluctuations in δ18O during the interval of ca. 5000-800calyr BP that correspond (inversely) with changes in K+ content of the GISP2 ice-core record from Greenland, a proxy for the relative strength of the Siberian High, suggesting control by climate-related variability in δ18O of regional precipitation. The dramatic expansion of Siberian dwarf pine (Pinus pumila) in northern and central Kamchatka between ca. 5000 and 4000calyr BP, as inferred from pollen records from the same and neighbouring sites, appears to have occurred at a time of progressively declining δ18O of precipitation. This development is interpreted as reflecting a regional cooling trend accompanied by increasing winter snowfall related to gradual intensification of the Siberian High from ca. 5000 to ca. 3000calyr BP. A thicker and more long-lasting snow cover can be assumed to have favoured P. pumila by providing a competitive advantage over other boreal and subalpine tree and shrub species in the region during the later part of the Holocene. These results, which are the first of their kind from Kamchatka, provide novel insight into the Holocene vegetational and climatic development in easternmost Asia, as well as long-term atmospheric circulation dynamics in Beringia.
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| 18. |
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| 19. |
- Hammarlund, Dan, et al.
(author)
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Palaeolimnological and sedimentary responses to Holocene forest retreat in the Scandes Mountains, west-central Sweden
- 2004
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In: Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 14:6, s. 862-876
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Journal article (peer-reviewed)abstract
- A suite of analyses was performed on sediments accumulated during the last 10 700 years in Lake Spaime, a small, hydrologically open water body in the modern alpine tundra zone of the Scandes Mountains, west-central Sweden. The study aimed to evaluate (1) the nature of climate changes that forced the late-Holocene lowering of altitudinal tree limit in the region, the timing of which is known from prior studies based on radiocarbon dating of subfossil wood, and (2) the impact of these vegetational changes on an aquatic ecosystem. Arboreal pollen and plant macrofossil data confirm the persistence of trees in the lake catchment at least from c. 9700 cal. BP until c. 3700 cal. BP. Although growing-season temperature is commonly believed to be the dominant factor driving boreal forest tree-limit variations in the region, a chironomid-based reconstruction of mean July air temperature suggests that local deforestation during the late Holocene was not accompanied by a significant cooling. The tree-limit retreat was more likely caused by increasing effective moisture and declining length of the growing season. The ecohydrological response of Lake Spaime to this combination of climate and vegetational changes included a decline in primary productivity, as indicated by an abrupt decrease in sediment organic matter content, while associated increases in organic delta(13)C, delta(15)N and C/N point to diminished fluxes and altered balance of catchment-derived nutrients following deforestation. The decline in aquatic productivity is also marked by a distinct change in the mineral magnetic properties, from a high magnetic concentration assemblage dominated by fine-grained magnetite of biogenic origin to one dominated by background levels of coarse-grained detrital magnetite.
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| 20. |
- Hammarlund, Dan, et al.
(author)
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Stable isotope variations in stalagmites from northwestern Sweden document changes in temperature and vegetation during the early Holocene: a comment on Sundqvist et al. 2007a
- 2008
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In: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 18:6, s. 1007-1008
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Journal article (other academic/artistic)abstract
- We offer an alternative palaeoenvironmental interpretation of oxygen-isotope data obtained on two early-Holocene stalagmite records from caves in the Scandes Mountains of northern Sweden (Korallgrottan and Labrintgrottan), and the well-known Soylegrotta (Norway) SG93 record with which they are compared, that differs in several respects from that proposed by the authors. Contrary to viewing these as inverted palaeotemperature records, we suggest that they primarily reflect changes in the delta O-18 of local annual precipitation, modified by secondary temperature-dependent variation in water-calcite oxygen-isotope fractionation, at each of the three sites. This is supported by the striking similarity over the entire Holocene between the SG93 calcite delta O-18 record and the lacustrine carbonate delta O-18 record from Lake Tibetanus (northern Sweden), which implies straightforward transfer of annual precipitation delta O-18 signals into cave drip waters. Recent studies of drip waters in Korallgrottan also support this model. This further enhances the value of cave deposits as palaeoclimate archives in this region and provides additional evidence of the sensitivity of the precipitation 'isotope thermometer' to changes in atmospheric circulation patterns.
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| 21. |
- Jones, T. R., et al.
(author)
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Delayed maximum northern European summer temperatures during the Last Interglacial as a result of Greenland Ice Sheet melt
- 2017
-
In: Geology. - 0091-7613. ; 45:1, s. 23-26
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Journal article (peer-reviewed)abstract
- Here we report a new quantitative mean July temperature reconstruction using non-biting midges (chironomids) from the Danish Last Interglacial (LIG) site Hollerup (spanning 127-116 ka). We find that peak mean July temperatures of 17.5 °C, similar to those of the present day (1961-1990 CE), were reached shortly before the onset of the regional Carpinus pollen zone. Through comparison to terrestrial and marine sequences we demonstrate that peak summer warmth took place some three millennia after the onset of LIG warming in Europe, a marked delay in line with records from the North Atlantic. Crucially, the warmest northern European summer temperatures appear to follow maximum Greenland Ice Sheet mass loss, implying that meltwater substantially reduced Atlantic Meridional Overturning Circulation and depressed European temperatures during the early part of the interglacial.
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| 22. |
- Klimaschewski, A., et al.
(author)
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Holocene environmental changes in southern Kamchatka, Far Eastern Russia, inferred from a pollen and testate amoebae peat succession record
- 2015
-
In: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 134, s. 142-154
-
Journal article (peer-reviewed)abstract
- High resolution palaeoenvironmental records in Far-Eastern Russia are rare, and the Kamchatka Peninsula is among the least studied areas of the region. This paper describes a record spanning the last ca. 11,000 yr, obtained from a bog in the southern part of Kamchatka. The radiocarbon dated core was analysed for pollen, testate amoebae, charcoal and loss-on-ignition (LOI). The vegetation during the early Holocene was dominated by grasses (Poaceae), birch (Betula) and heath (Ericaceae p. p.). Around 10,300 cal yr BP there was a substantial change in the vegetation cover to shrub alder (Alnus viridis s.I.) stands with sedges and ferns (Polypodiophyta) as well as herbs such as meadow rue (Thalictrum) in the understory. In the surroundings of Utka peatlands started to form. The variations in the vegetation cover were most probably caused by climatic changes. At the beginning of sediment accumulation, before 10,300 cal yr BP, the composition of the vegetation points to cooler summers and/or decreased annual precipitation. Around 10,300 cal yr BP, changes in vegetation occurred due to rising temperatures and/or changed water regimes. Increased abundancies of dry indicating testate amoebae after 9100 cal yr BP point to intermediate to dry soil conditions. Between 8600 and 7700 cal yr BP tree alder (Alnus incana) was widely spread at the site which probably indicates optimal environmental conditions. The tephra layer at 381-384.5 cm (ca. 8500 cal yr BP) produces a strong impact on the testate amoebae assemblages. At 7700 cal yr BP there was a sudden drop of A. incana in the local vegetation. From this time on, A. incana and also A. viridis decrease continuously whereas Betula gradually increases. The upper part of the sequence (after 6300 cal yr BP) shows higher abundancies of meadowsweet (Filipendula) and sweet gale (Myrica) pollen. After 6300 cal yr BP, changes in testate amoebae demonstrate variable soil moisture conditions at the site. Between 3700 and 1800 cal yr BP, wet conditions dominate as dry indicating testate amoebae decrease. After 1800 cal yr BP soil conditions become more variable again but this time with dry dominating testate amoebae. In contrast to surrounding regions, there is no evidence of trees such as spruce or larch growing in the surroundings of the site even though those trees are characteristic of many eastern Siberian sites. This difference might be because of the maritime influence of the Okhotsk Sea. Even dwarf pine (Pinus pumila), which is currently widely dispersed in northern Kamchatka, became part of the local vegetation only during the last 700 yr.
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| 23. |
- Kokfelt, U., et al.
(author)
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Diatom blooms and associated vegetation shifts in a subarctic peatland : responses to distant volcanic eruptions?
- 2016
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In: Journal of Quaternary Science. - : Wiley. - 0267-8179 .- 1099-1417. ; 31:7, s. 723-730
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Journal article (peer-reviewed)abstract
- We test the hypothesis that rich occurrences of diatoms observed at transitions between major peat units representing different vegetation communities in a peat sequence from subarctic northern Sweden reflect responses to acid deposition from the Samalas AD 1257 and Laki AD 1783/1784 eruptions. We observe sudden changes in the mire ecosystem and thereby in the trophic status and biogeochemical cycling of the peatland. Both the eruptions are known to have been associated with significant acid deposition events and climatic anomalies, as recorded in polar ice cores. To test the hypothesis, new chronological analyses and age modelling were applied to existing biogeochemical and biological records from the peat sequence. This approach yielded modelled age ranges of AD 1239-1284 (1s)/AD 1210-1303 (2s) (median: AD 1260) and AD 1674-1795 (1s)/AD 1665-1875 (2s) (median AD 1743), respectively, for the stratigraphic transitions. Hence, the modelled age ranges bracket the ages of the eruptions in question and the hypothesis could therefore not be rejected. Impacts of acid deposition from the eruptions are assumed to have caused instant acidification, vegetation damage, increased nutrient cycling and blooms of opportunistic epiphytic diatoms. In addition, cooling may have contributed to vegetation changes through permafrost inception, frost heave and thereby altered hydrological conditions.
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| 24. |
- Kozik, Nevin P., et al.
(author)
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Rapid marine oxygen variability : Driver of the Late Ordovician mass extinction
- 2022
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In: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 8:46
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Journal article (peer-reviewed)abstract
- The timing and connections between global cooling, marine redox conditions, and biotic turnover are underconstrained for the Late Ordovician. The second most severe mass extinction occurred at the end of the Ordovician period, resulting in ~85% loss of marine species between two extinction pulses. As the only “Big 5” extinction that occurred during icehouse conditions, this interval is an important modern analog to constrain environmental feedbacks. We present a previously unexplored thallium isotope records from two paleobasins that record global marine redox conditions and document two distinct and rapid excursions suggesting vacillating (de)oxygenation. The strong temporal link between these perturbations and extinctions highlights the possibility that dynamic marine oxygen fluctuations, rather than persistent, stable global anoxia, played a major role in driving the extinction. This evidence for rapid oxygen changes leading to mass extinction has important implications for modern deoxygenation and biodiversity declines.
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| 25. |
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| 26. |
- Loryan, Irena, 1977-, et al.
(author)
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Quantitative Assessment of Drug Delivery to Tissues and Association with Phospholipidosis: A Case Study with Two Structurally Related Diamines in Development
- 2017
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In: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 14:12, s. 4362-4373
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Journal article (peer-reviewed)abstract
- Drug induced phospholipidosis (PLD) may be observed in the preclinical phase of drug development and pose strategic questions. As lysosomes have a central role in pathogenesis of PLD, assessment of lysosomal concentrations is important for understanding the pharmacokinetic basis of PLD manifestation and forecast of potential clinical appearance. Herein we present a systematic approach to provide insight into tissue-specific PLD by evaluation of unbound intracellular and lysosomal (reflecting acidic organelles) concentrations of two structurally related diprotic amines, GRT1 and GRT2. Their intratissue distribution was assessed using brain and lung slice assays. GRT1 induced PLD both in vitro and in vivo. GRT1 showed a high intracellular accumulation that was more pronounced in the lung, but did not cause cerebral PLD due to its effective efflux at the blood-brain barrier. Compared to GRT1, GRT2 revealed higher interstitial fluid concentrations in lung and brain, but more than 30-fold lower lysosomal trapping capacity. No signs of PLD were seen with GRT2. The different profile of GRT2 relative to GRT1 is due to a structural change resulting in a reduced basicity of one amino group. Hence, by distinct chemical modifications, undesired lysosomal trapping can be separated from desired drug delivery into different organs. In summary, assessment of intracellular unbound concentrations was instrumental in delineating the intercompound and intertissue differences in PLD induction in vivo and could be applied for identification of potential lysosomotropic compounds in drug development.
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- St Amour, Natalie A., et al.
(author)
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New insights into Holocene atmospheric circulation dynamics in central Scandinavia inferred from oxygen-isotope records of lake-sediment cellulose
- 2010
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In: Boreas. - : Wiley. - 1502-3885 .- 0300-9483. ; 39:4, s. 770-782
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Journal article (peer-reviewed)abstract
- Cellulose-inferred lakewater oxygen-isotope records have been obtained from two hydrologically open basins (Lake Spaime and Lake Svartkalstjarn), located on a west east transect across central Sweden, to investigate changes in atmospheric circulation patterns during the Holocene. The Lake Spaime delta O-18 record is sensitive to changes in the seasonal distribution of precipitation in the Scandes Mountains of west-central Sweden, and thus generally portrays variations in delta O-18 of precipitation (delta O-18(P)) that are governed predominantly by the influence of air masses originating from the North Atlantic. In contrast, the Lake Svartkalstjarn delta O-18 record appears to reflect the varying influence of air masses delivering moisture from the North Atlantic and the Baltic Sea. A comparison of inferred changes in delta O-18(P) over the Holocene between the two sites reveals systematic patterns of variability over widely different time scales. These include: (1) a previously recognized long-term regional decline in delta O-18(P), possibly in response to the declining vigour of Northern Hemisphere atmospheric circulation related to decreasing summer solar insolation; (2) newly identified inverse centennial- to millennial-scale delta O-18(P) fluctuations at the two sites that may be linked to changes in modes of atmospheric circulation analogous to those described at interannual to multidecadal time scales by the North Atlantic Oscillation (NAO) index; and (3) a prolonged interval of apparent climatic stability in the mid-Holocene (c. 6300-4200 cal. yr BP) characterized by persistently negative NAO-like circulation.
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