| 1. |
- Fensholt, Rasmus, et al.
(author)
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Greenness in semi-arid areas across the globe 1981-2007 - an Earth Observing Satellite based analysis of trends and drivers
- 2012
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In: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257. ; 121, s. 144-158
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Journal article (peer-reviewed)abstract
- Semi-arid areas, defined as those areas of the world where water is an important limitation for plant growth, have become the subject of increased interest due to the impacts of current global changes and sustainability of human lifestyles. While many ground-based reports of declining vegetation productivity have been published over the last decades, a number of recent publications have shown a nuanced and, for some regions, positive picture. With this background, the paper provides an analysis of trends in vegetation greenness of semi-arid areas using AVHRR GIMMS from 1981 to 2007. The vegetation index dataset is used as a proxy for vegetation productivity and trends are analyzed for characterization of changes in semi-arid vegetation greenness. Calculated vegetation trends are analyzed with gridded data on potential climatic constraints to plant growth to explore possible causes of the observed changes. An analysis of changes in the seasonal variation of vegetation greenness and climatic drivers is conducted for selected regions to further understand the causes of observed inter-annual vegetation changes in semi-arid areas across the globe. It is concluded that semi-arid areas, across the globe, on average experience an increase in greenness (0.015 NDVI units over the period of analysis). Further it is observed that increases in greenness are found both in semi-arid areas where precipitation is the dominating limiting factor for plant production (0.019 NDVI units) and in semi-arid areas where air temperature is the primarily growth constraint (0.013 NDVI units). Finally, in the analysis of changes in the intra-annual variation of greenness it is found that seemingly similar increases in greenness over the study period may have widely different explanations. This implies that current generalizations, claiming that land degradation is ongoing in semi-arid areas worldwide, are not supported by the satellite based analysis of vegetation greenness. (c) 2012 Elsevier Inc. All rights reserved.
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| 2. |
- Helldén, Anders, et al.
(author)
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Adverse drug reactions and impaired renal function in elderly patients admitted to the emergency department : a retrospective study
- 2009
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In: Drugs & Aging. - : Wolters Kluwer. - 1170-229X .- 1179-1969. ; 26:7, s. 595-606
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Journal article (peer-reviewed)abstract
- BACKGROUND: Adverse drug reactions (ADRs) are common in elderly patients. There are various reasons for this, including age- and disease-related alterations in pharmacokinetics and pharmacodynamics as well as the common practice of polypharmacy. The decline in renal function in elderly patients may also predispose them to pharmacological ADRs (type A, augmented). Patients receiving home healthcare may be at even higher risk.OBJECTIVES: To study ADRs as a cause of acute hospital admissions in a defined cohort of elderly patients (aged >or=65 years) registered to receive home healthcare services, with special reference to impaired renal function as a possible risk factor.METHODS: This was a retrospective study of 154 elderly patients aged >or=65 years admitted to the emergency department of a university hospital in Stockholm, Sweden, in October-November 2002. Estimated creatinine clearance (eCL(CR)) was calculated from the Cockcroft-Gault formula, and estimated glomerular filtration rate (eGFR) by the Modification of Diet in Renal Disease (MDRD) equation. ADRs were defined according to WHO criteria. All medications administered to patients at admission and at discharge were collated. These and other data were collected from computerized hospital records.RESULTS: ADRs were judged to contribute to or be the primary cause of hospitalization in 22 patients, i.e. 14% of 154 patients registered to receive home healthcare. Eleven of the 22 patients were women. All but one ADR were type A. Excessive doses or drugs unsuitable in renal insufficiency were present in seven patients in the ADR group compared with only four patients in the group without ADRs (p = 0.0001). Patients with ADRs did not differ significantly from those without ADRs in relation to age, plasma creatinine, eCL(CR), weight or number of drugs prescribed at admission. However, women with ADRs were significantly older than women without ADRs (mean +/- SD age 88.8 +/- 5.7 years vs 82.5 +/- 8.0 years, respectively; p = 0.014) and had significantly lower mean +/- SD eCL(CR) values (25.5 +/- 10.8 and 37.1 +/- 17.1 mL/min, respectively; p = 0.035). Median MDRD eGFR was significantly higher than median eCL(CR) (59 [range 6-172] mL/min/1.73 m2 vs 38 [range 5-117] mL/min, respectively; p = 0.0001).CONCLUSIONS: In elderly patients registered to receive home healthcare, 14% of hospital admissions were primarily caused by ADRs. One-third of these ADRs were related to impaired renal function, generally in very old women. These ADRs may be avoided by close monitoring of renal function and adjustments to pharmacotherapy (drug selection and dose), particularly in very elderly women.
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| 3. |
- Helldén, Anders, et al.
(author)
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Fluconazole-induced intoxication with phenytoin in a patient with ultra-high activity of CYP2C9
- 2010
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In: European Journal of Clinical Pharmacology. - : Springer Science and Business Media LLC. - 0031-6970 .- 1432-1041. ; 66:8, s. 791-5
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Journal article (peer-reviewed)abstract
- PURPOSE: The cytochrome P450 enzyme CYP2C9 metabolizes several important drugs, such as warfarin and oral antidiabetic drugs. The enzyme is polymorphic, and all known alleles, for example, CYP2C9*2 and*3, give decreased activity. Ultra-high activity of the enzyme has not yet been reported.METHODS: We present a patient with Behçet's disease who required treatment with high doses of phenytoin. When fluconazole, a potent inhibitor of CYP2C9, was added to the treatment regimen, the patient developed ataxia, tremor, fatigue, slurred speech and somnolence, indicating phenytoin intoxication. On suspicion of ultra-high activity of CYP2C9, a phenotyping test for CYP2C9 with losartan was performed.RESULTS: The patient was shown to have a higher activity of CYP2C9 than any of the 190 healthy Swedish Caucasians used as controls.CONCLUSIONS: Our finding of an ultrarapid metabolism of losartan and phenytoin may apply to other CYP2C9 substrates, where inhibition of CYP2C9 may cause severe adverse drug reactions.
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| 4. |
- Hellden, Anders, et al.
(author)
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Renal function estimations and dose recommendations for dabigatran, gabapentin and valaciclovir : a data simulation study focused on the elderly
- 2013
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In: BMJ Open. - London, UK : BMJ. - 2044-6055. ; 3:4, s. e002686-
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Journal article (peer-reviewed)abstract
- Objectives The thrombin inhibitor dabigatran is mainly excreted by the kidneys. We investigated whether the recommended method for estimation of renal function used in the clinical trials, the Cockcroft-Gault (CG(old)) equation and the estimated glomerular filtration rate (eGFR) modification of diet in renal disease equation 4 (MDRD4), differ in elderly participants, resulting in erroneously higher dose recommendations of dabigatran, which might explain the serious, even fatal, bleeding reported. The renally excreted drugs gabapentin and valaciclovir were also included for comparison. Design A retrospective data simulation study. Participants Participants 65years and older included in six different studies. Main outcome measure Estimated renal function by CG based on uncompensated (old Jaffe' method) creatinine (CG(old)) or by MDRD4 based on standardised compensated P-creatinine traceable to isotope-dilution mass spectrometry, and the resulting doses. Results 790 participants (432 females), mean age (SD) 77.6 +/- 5.7years. Mean estimated creatinine clearance (eCrCl) by the CG(old) equation was 44.2 +/- 14.8ml/min, versus eGFR 59.6 +/- 20.7ml/min/1.73m(2) with MDRD4 (p<0.001), absolute median difference 13.5, 95% CI 12.9 to 14.2. MDRD4 gave a significantly higher mean dose (valaciclovir +21%, dabigatran +25% and gabapentin +37%) of all drugs (p<0.001). With MDRD4 58% of the women would be recommended a full dose of dabigatran compared with 18% if CG(old) is used. Conclusions MDRD4 would result in higher recommended doses of the three studied drugs to elderly participants compared with CG, particularly in women, and thus increased the risk of dose and concentration-dependent adverse reactions. It is important to know which method of estimation of renal function the Summary of Products Characteristics was based on, and use only that one when prescribing renally excreted drugs with narrow safety window. Doses based on recently developed methods for estimation of renal function may be associated with considerable risk of overtreatment in the elderly.
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| 5. |
- Helldén, Johan, et al.
(author)
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Åtgärdslösningar : – erfarenheter och tillgängliga metoder
- 2006
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Reports (other academic/artistic)abstract
- Efter en kraftigt ökande aktivitet inom området förorenad mark finns ett stort behov av kunskap och erfarenheter hos de många aktörer vilka förväntas fatta beslut om åtgärdsalternativ. Projektets särskilda strategi för att bemöta detta har varit att inventera och bygga på de erfarenheter som finns från efterbehandlingar och att kombinera detta med en beskrivning av olika åtgärdsmetoder. I en första fas gjordes en inventering och sammanställning där målet var att få en översiktlig bild av hur saneringar bedrivits. I den översiktliga sammanställningen ingår 226 objekt vilket uppskattas till ca en sjättedel av totala antalet anmälda saneringar till tillsynsmyndighet. Till sammanställningen utvaldes ett antal saneringar som genomförts av SPI Miljösaneringsfond AB, SPIMFAB, totalt 90 fall, där de 10 % största schakt och sortering/ transport-saneringarna samt ett antal in situ-saneringar ingick. Kommuner, statliga eller andra privata beställare står för de resterande 136 fallen. Varje objekt beskrivs i tabellformat i bilaga 1. Som stöd till tolkning av de beskrivna fallen eller som ett läromedel i allmänhet finns en omfattande genomgång och beskrivning av olika åtgärdstekniker. Fokus för teknikbeskrivningarna ligger i första hand på de metoder som använts i Sverige och beskrivningarna refererar till fallstudier i angränsande kapitel.Sjutton utvalda fall analyseras fördjupat baserat på rapporter och intervjuer med inblandade parter. Projekten omfattar olika behandlingsmetoder, och tar upp såväl lyckade som problemfyllda projekt. Fallstudierna refererar till inhämtat rapportmaterial där åtgärdstekniken beskrivs, och fokuserar på i vilken grad uppställda åtgärdsmål har uppfyllts, samt på att identifiera framgångskritiska faktorer som styrt resultatet. Baserat på tillgängligt material i SPIMFAB:s databas har även statistik tagits fram som visar vad som styr resultat och ekonomi i ett stort antal saneringar. För att få en uppfattning om vad som händer med mottagna massor på behandlingsanläggningar genomfördes även en enkätundersökning till tillståndsgivna anläggningar. Fallstudierna visar att mer än hälften av SPIMFAB:s in situ-projekt fick slutföras genom bortgrävning av massor. En förklaring verkar vara att det under de första åren generellt funnits liten erfarenhet av metoderna och att appliceringen av in situ-teknik baserats på för vaga förundersökningar. De in situ-saneringar som varit lyckosamma har föregåtts av grundliga kartläggningar av förorenings- och markförhållanden. För såväl SPIMFAB:s projekt som övriga gäller att schakt och sortering/transport som åtgärdsstrategi dominerat stort. Den näst vanligaste strategin har varit in situ-saneringar med vakuumextraktion/markventilering. Även ett flertal andra in situ-metoder har använts med gott resultat, exv stimulerad nedbrytning med bakterietillsatser, eller olika former av barriärer och filter.Marksanering är en verksamhet som i hög grad styrs av plastspecifika förutsättningar vilket kräver flexibla problemlösningar. Projektets fallstudier ger en rad exempel på olika problem av vitt skilda slag som kan uppstå. Den klart största andelen jord som tas emot på behandlingsanläggningarna är oljeförorenadjord som behandlas biologiskt genom kompostering. Enligt behandlingsanläggningarna ger metoden goda resultat och det finns stor efterfrågan efter behandlade massor för sluttäckningar eller som konstruktionsmaterial på deponier. Behovet av sådant material verkar vara en stark drivkraft för att ta emot förorenade massor för behandling. En inte oansenlig andel av de behandlade massorna återanvänds även som konstruktionsmaterial utanför behandlingsanläggningen. Efterbehandling är i sig själv en miljöfarlig verksamhet och kan leda till en konflikt mellan olika nationella miljömål. Med utgångspunkt från tillgänglig litteratur om livscykelanalys (LCA) föreslås hur enkla index för s k eko-effektivitet kan användas för att värdera och styra val av saneringsåtgärder. I ett exempel visas även hur energiåtgång kan översättas till utsläpp av koldioxid och viktas mot sanerad mängd jord. Denna typ av index bör kunna användas som kriterier i upphandlingar av saneringsåtgärder. För att förbättra möjligheten att redovisa miljövinster och eventuella förluster samt styra val av åtgärder föreslås att data från miljörapporter från efterbehandlingsverksamhet sammanställs som en del av de ordinarie regionala och nationella årliga rapporterna. Ett sammanfattande intryck av det insamlade materialet är att en hel del branschmognad och tekniketablering skett de senaste 10 åren. Biologisk behandling dominerar som metod och genomförs nu framgångsrikt på ett stort antal behandlingsanläggningar. Jordtvätt och in situ markventilering är två metoder som haft en hel del bakslag men där aktörerna dragit lärdomar och blivit säkrare i sitt genomförande. Ett stort antal andra metoder som etablerats i omvärlden har emellertid varit svårare att etablera i Sverige (exempelvis termisk desorption, stimulerad gasfasavdrivning, kemisk oxidation, övervakad naturlig nedbrytning, filtertekniker et c). Följden av att det finns få alternativa åtgärdslösningar bidrar till att hålla priserna uppe och ger begränsande möjligheter att välja lösningar med avseende på minsta negativa miljöeffekt. Behandlingsanläggningarnas stora behov av täckmassor till avslutning av deponier är exempel på en betydande faktor som idag främjar ex situ-behandling. En generell åtgärd för att stimulera branschutvecklingen vore att organisera systematisk återkoppling och kvalitetsutveckling. Detta kan göras genom att bygga vidare på den inventering och sammanställning som gjorts i detta projekt. Enklare standardformulär kan iordningställas, vilka ifylls och rapporteras till tillsynsmyndigheten för sammanställning. Formulären föreslås innehålla uppgifter liknande de i bilaga 1. Som för andra industriella verksamheter bör även marksanering följas upp vad gäller miljörapportering. Faktorer som exv energiåtgång är således parametrar som bör finnas med i myndighetens sammanställning. Uppgifterna sammanställs och återrapporteras till bransch och samhälle, där de kan användas som aktuellt beslutsunderlag för olika förbättringsåtgärder.
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| 6. |
- Helldén, Ulf
(author)
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A coupled human-environment model for desertification simulation and impact studies
- 2008
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In: Global and Planetary Change. - : Elsevier BV. - 1872-6364 .- 0921-8181. ; 64:3-4, s. 158-168
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Journal article (peer-reviewed)abstract
- This paper presents the development of a system dynamic model to simulate and analyze desertification. The human-environment coupled model integrates socio-economic drivers with bio-physical drivers of biomass production, land degradation and desertification. It is based on the UN and GEF definitions of desertification. It illustrates the concept of desertification through differential equation and simulation output graphics. It is supplemented with a causal loop diagram demonstrating the existing feed-back mechanisms. The model relates population pressure and dynamics over time to the growth and availability of biomass resources. The human population stock is described as a function of growth rate, death rate and resources dependent in and out migration of people. The relative growth rate of the stock of resources is modeled as a function of climate and exploitation pressure affecting soil erosion and water availability. The model is applied for the Sahelian desertification syndrome using input data to illustrate and simulate a 150 years period (1900-2050) in Kordofan, Sudan. The model indicates that it is difficult to generate irreversible desertification. (C) 2008 Elsevier B.V. All rights reserved.
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| 7. |
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| 8. |
- Helldén, Ulf, et al.
(author)
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CASE STUDIES OF DESERTIFICATION MONITORING. -A DISCUSSION OF EU INITIATIVES
- 2005
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In: Proceedings: Local & Regional Desertification Indicators in a Global Perspective. ; , s. 195-203
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Conference paper (peer-reviewed)abstract
- The word “desertification” was introduced in 1949 by the French scientist Aubreville in his report “Climats, forêts et désertification de l´Afrique tropicale”. The concept, however, was discussed earlier by European and American scientists in terms of increased sand movements, desiccation, desert and Sahara encroachment and man made deserts. Desertification, at the beginning of last century, meant the spreading (expansion) of deserts or desert-like (non productive or very low productive) conditions from existing deserts into non-desert areas close to the desert margins. The symptoms of the phenomena were often related to sand movement and encroachment into oasis and desert margins. Aubreville also stated in 1949 that there are real deserts being born, under our very eyes, in the 700-1500 mm annual rainfall areas. At that time, one school favored the idea of a postglacial long term climate change (desiccation) as a major driving force causing desertification. Others stressed the importance of human impact. The human impact was expressed in terms of bad management of the natural resources including over cutting, overgrazing, over cultivation and misuse of water. Since then, different concepts of desertification have developed and been discussed over and over again by scientists, politicians and the international aid and development society. Important international events were UNCOD in Nairobi 1977, UNCED in Rio de Janeiro 1992 followed up by the UNCCD adopted in 1994 and entering into force in 1996. The choice of land degradation mitigation strategies and the degree of resulting control success varies with the prevailing concepts of causes and consequences. These concepts are dependent on the monitoring approach used. This is exemplified through a discussion of a few desertification monitoring case studies followed by a presentation of a recent EU integrated assessment, monitoring and modelling initiative, DeSurvey (2005-2010). The initiative is targeting desertification affected areas in Europe, Africa, China and South America. It probably constitutes the largest ever international research project to exclusively focus on desertification surveillance and assessment. Conclusion: The causes, consequences and methods of control of desertification cannot be generalized but are site specific. Every site and case needs its own diagnosis, based on an integrated and systemic survey approach, before the right cure can be identified and implemented. The DeSurvey consortium aims at developing a generic survey, monitoring and modelling system for such an approach.
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| 10. |
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