| 61. |
- Hall, Marianne, 1976, et al.
(författare)
-
Which are the most important parameters for modelling carbon assimilation in boreal Norway spruce under elevated [CO2] and temperature conditions?
- 2013
-
Ingår i: Tree Physiology. - : Oxford University Press (OUP). - 0829-318X .- 1758-4469. ; 33:11
-
Tidskriftsartikel (refereegranskat)abstract
- Photosynthesis is highly responsive to environmental and physiological variables, including phenology, foliage nitrogen (N) content, atmospheric CO2 concentration ([CO2]), irradiation (Q), air temperature (T) and vapour pressure deficit (D). Each of these responses is likely to be modified by long-term changes in climatic conditions such as rising air temperature and [CO2]. When modelling photosynthesis under climatic changes, which parameters are then most important to calibrate for future conditions? To assess this, we used measurements of shoot carbon assimilation rates and microclimate conditions collected at Flakaliden, northern Sweden. Twelve 40-year-old Norway spruce trees were enclosed in whole-tree chambers and exposed to elevated [CO2] and elevated air temperature, separately and in combination. The treatments imposed were elevated temperature, +2.8 °C in July/August and +5.6 °C in December above ambient, and [CO2] (ambient CO2 ∼370 μ mol mol−1, elevated CO2 ∼700 μ mol mol−1). The relative importance of parameterization of Q, T and D responses for effects on the photosynthetic rate, expressed on a projected needle area, and the annual shoot carbon uptake was quantified using an empirical shoot photosynthesis model, which was developed and fitted to the measurements. The functional form of the response curves was established using an artificial neural network. The [CO2] treatment increased annual shoot carbon (C) uptake by 50%. Most important was effects on the light response curve, with a 67% increase in light-saturated photosynthetic rate, and a 52% increase in the initial slope of the light response curve. An interactive effect of light saturated photosynthetic rate was found with foliage N status, but no interactive effect for high temperature and high CO2. The air temperature treatment increased the annual shoot C uptake by 44%. The most important parameter was the seasonality, with an elongation of the growing season by almost 4 weeks. The temperature response curve was almost flat over much of the temperature range. A shift in temperature optimum had thus an insignificant effect on modelled annual shoot C uptake. The combined temperature and [CO2] treatment resulted in a 74% increase in annual shoot C uptake compared with ambient conditions, with no clear interactive effects on parameter values.
|
|
| 62. |
|
|
| 63. |
- Hasper, Thomas Berg, et al.
(författare)
-
Stomatal CO2 responsiveness and photosynthetic capacity of tropical woody species in relation to taxonomy and functional traits
- 2017
-
Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 184:1, s. 43-57
-
Tidskriftsartikel (refereegranskat)abstract
- © 2017 The Author(s)Stomatal CO2 responsiveness and photosynthetic capacity vary greatly among plant species, but the factors controlling these physiological leaf traits are often poorly understood. To explore if these traits are linked to taxonomic group identity and/or to other plant functional traits, we investigated the short-term stomatal CO2 responses and the maximum rates of photosynthetic carboxylation (Vcmax) and electron transport (Jmax) in an evolutionary broad range of tropical woody plant species. The study included 21 species representing four major seed plant taxa: gymnosperms, monocots, rosids and asterids. We found that stomatal closure responses to increased CO2 were stronger in angiosperms than in gymnosperms, and in monocots compared to dicots. Stomatal CO2 responsiveness was not significantly related to any of the other functional traits investigated, while a parameter describing the relationship between photosynthesis and stomatal conductance in combined leaf gas exchange models (g1) was related to leaf area-specific plant hydraulic conductance. For photosynthesis, we found that the interspecific variation in Vcmax and Jmax was related to within leaf nitrogen (N) allocation rather than to area-based total leaf N content. Within-leaf N allocation and water use were strongly co-ordinated (r2 = 0.67), such that species with high fractional N investments into compounds maximizing photosynthetic capacity also had high stomatal conductance. We conclude that while stomatal CO2 responsiveness of tropical woody species seems poorly related to other plant functional traits, photosynthetic capacity is linked to fractional within-leaf N allocation rather than total leaf N content and is closely co-ordinated with leaf water use.
|
|
| 64. |
|
|
| 65. |
- Hasper, Thomas Berg, et al.
(författare)
-
Water use by Swedish boreal forests in a changing climate
- 2016
-
Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 30:5, s. 690-699
-
Tidskriftsartikel (refereegranskat)abstract
- The rising levels of atmospheric carbon dioxide concentration ([CO2]) and temperature have the potential to substantially affect the terrestrial water and energy balance by altering the stomatal conductance and transpiration of trees. Many models assume decreases in stomatal conductance and plant water use under rising [CO2], which has been used as a plausible explanation for the positive global trend in river run-off over the past century. Plant water use is, however, also affected by changes in temperature, precipitation and land use, and there is yet no consensus about the contribution of different drivers to temporal trends of evapotranspiration (ET) and river run-off. In this study, we assessed water-use responses to climate change by using both long-term monitoring and experimental data in Swedish boreal forests. Historical trends and patterns in ET of large-scale boreal landscapes were determined using climate and run-off data from the past 50 years, while explicit tree water-use responses to elevated [CO2] and/or air temperature were examined in a whole-tree chamber experiment using mature Norway spruce (Picea abies (L.) Karst.) trees. The results demonstrated that ET estimated from water budgets at the catchment scale increased by 18% over the past 50 years while run-off did not significantly change. The increase in ET was related to increasing precipitation and a steady increase in forest standing biomass over time. The whole-tree chamber experiment showed that Norway spruce trees did not save water under elevated [CO2] and that experimentally elevated air temperature did not increase transpiration as decreased stomatal conductance cancelled the effect of higher vapour pressure deficit in warmed air. Our findings have important implications for projections of future water use of European boreal coniferous forests, indicating that changes in precipitation and standing biomass are more important than the effects of elevated [CO2] or temperature on transpiration rates.
|
|
| 66. |
- Hellberg, Victoria, et al.
(författare)
-
Cisplatin and oxaliplatin toxicity : importance of cochlear kinetics as a determinant for ototoxicity
- 2009
-
Ingår i: Journal of the National Cancer Institute. - Cary : Oxford University Press. - 0027-8874 .- 1460-2105. ; 101:1, s. 37-47
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cisplatin is a cornerstone anticancer drug with pronounced ototoxicity, whereas oxaliplatin, a platinum derivative with a different clinical profile, is rarely ototoxic. This difference has not been explained.METHODS: In HCT-116 cells, cisplatin (20 microM)-induced apoptosis was reduced by a calcium chelator from 9.9-fold induction (95% confidence interval [CI] = 8.1- to 11.7-fold), to 3.1-fold induction (95% CI = 2.0- to 4.2-fold) and by superoxide scavenging from 9.3-fold (95% CI = 8.8- to 9.8-fold), to 5.1-fold (95% CI = 4.4- to 5.8-fold). A guinea pig model (n = 23) was used to examine pharmacokinetics. Drug concentrations were determined by liquid chromatography with post-column derivatization. The total platinum concentration in cochlear tissue was determined by inductively coupled plasma mass spectrometry. Drug pharmacokinetics was assessed by determining the area under the concentration-time curve (AUC). Statistical tests were two-sided.RESULTS: In HCT-116 cells, cisplatin (20 microM)-induced apoptosis was reduced by a calcium chelator from 9.9-fold induction (95% confidence interval [CI] = 8.1- to 11.7-fold to 3.1-fold induction) (95% CI = 2.0- to 4.2-fold) and by superoxide scavenging (from 9.3-fold, 95% CI = 8.8- to 9.8-fold, to 5.1-fold, 95% CI = 4.4- to 5.8-fold). Oxaliplatin (20 microM)-induced apoptosis was unaffected by calcium chelation (from 7.1- to 6.2-fold induction) and by superoxide scavenging (from 5.9- to 5.6-fold induction). In guinea pig cochlea, total platinum concentration (0.12 vs 0.63 microg/kg, respectively, P = .008) and perilymphatic drug concentrations (238 vs 515 microM x minute, respectively, P < .001) were lower after intravenous oxaliplatin treatment (16.6 mg/kg) than after equimolar cisplatin treatment (12.5 mg/kg). However, after a non-ototoxic cisplatin dose (5 mg/kg) or the same oxaliplatin dose (16.6 mg/kg), the AUC for perilymphatic concentrations was similar, indicating that the two drugs have different cochlear pharmacokinetics.CONCLUSION: Cisplatin- but not oxaliplatin-induced apoptosis involved superoxide-related pathways. Lower cochlear uptake of oxaliplatin than cisplatin appears to be a major explanation for its lower ototoxicity.
|
|
| 67. |
- Hellberg, Victoria, et al.
(författare)
-
Cochlear Pharmacokinetics of Cisplatin : An In Vivo Study in the Guinea Pig
- 2013
-
Ingår i: The Laryngoscope. - : Wiley. - 0023-852X .- 1531-4995. ; 123:12, s. 3172-3177
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives/HypothesisCisplatin produces toxic lesions to outer hair cells (OHCs) in the cochlear base but not in the apex. The objective of this study was to compare the pharmacokinetic profile of cisplatin in scala tympani (ST) perilymph in the cochlear base and apex, respectively. Study DesignIn vivo animal study. MethodsForty-seven guinea pigs were given an intravenous bolus injection of an ototoxic dose of cisplatin. Ten to 240 minutes after cisplatin was given, blood, cerebrospinal fluid (CSF), and ST perilymph were aspirated within the same target time. ST perilymph was aspirated from the basal turn and from the apex of the cochlea by two different sampling techniques. Liquid chromatography with postcolumn derivatization was used for quantitative determination of the parent drug. ResultsTen minutes after administration, the concentration of cisplatin in ST perilymph was 4-fold higher in the basal turn of the cochlea than in the apex. At 30 minutes, the drug concentrations did not differ. At 60 minutes, the level of cisplatin in ST perilymph and blood UF was equivalent. The perilymph-blood ratio increased thereafter with time. ConclusionThe pharmacokinetic findings of an early high concentration of cisplatin in the base of the cochlea and delayed elimination of cisplatin from ST perilymph compared to blood might correlate to the cisplatin-induced loss of OHCs in the base of the cochlea. Level of EvidenceN/A. Laryngoscope, 123:3172-3177, 2013
|
|
| 68. |
- Hellman, Per, et al.
(författare)
-
Endokrina sjukdomar
- 2016. - 4
-
Ingår i: Kirurgi. - Lund : Studentlitteratur AB. - 9789144099842 ; , s. 521-564
-
Bokkapitel (refereegranskat)
|
|
| 69. |
- Holmberg, M., et al.
(författare)
-
Treatment outcome 6-10 years after diagnosis of hyperthyroidism in 2916 patients : a longitudinal evaluation of a swedish incidence cohort
- 2018
-
Ingår i: Thyroid. - : Mary Ann Liebert. - 1050-7256 .- 1557-9077. ; :S1
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Treatment of Graves’ disease (GD) and toxic nodular goiter (TNG) has the objectives to cure hyperthyroidism, prevent recurrent disease and preserve thyroid function. Treatment efficacies and long-termout comes of antithyroid drugs (ATD), radioactive iodine (RAI) or surgery varies in the literature. We report outcome of treatment, cure rate and risk factors for relapse for GD and TNG in an unselected cohort. A prospective incidence-cohort of de novo diagnosed GD and TNG patients (n = 2916) from 2003-05, were invited to a follow-up 6 - 10 years after diagnosis. Questionnaires were sent to 2430 patients regarding treatments, cure rate, recurrence, quality of life, demographic data, comorbidities and life-style factors. Patients were treated according to clinical routine with ATD, RAI or surgery. Of those included, 1186 (83.3%) had GD and 237 (16.7%) had TNG. In GD patients, 351 (45.3%), 264 (81.5%), and 52 (96.3%) were cured by ATD, RAI or surgery respectively as first line treatment. Of those, 77.0%, 15.4% and 3.8% respectively were without levothyr-oxine supplementation at follow-up at 8 – 0.9 years. Including all treatment modalities, 851 (71.8%) of GD patients were cured within one treatment period. At follow-up, 278 (23%) of GD patients had been operated. In TNG patients, RAI cured 88.6% and surgery 92.9%, whereof 52/154 (33.8%) and 3/15 (20%) had no levothyroxine supplementation post RAI and surgery, respectively.The proportion that did not feel fully recovered at follow-up was 25.3% of GD and 18.1% of the TNG patients. Overall, treatment of hyperthyroidism results in preserved thyroid function only in 35.3% and 44.7% of GD and TNG cases, respectively. As many as 23.4% of the GD patients end up with surgery although only 4.6% choose it from the beginning. Our treatment tradition cures 71.8% of GD patients and 78.1% of TNG patients within one treatment period. The high number of patients who do not feel recovered 6 -10 years after hyperthyroidism in GD and TNG is are minder of the chronic nature of hyperthyroidism.
|
|
| 70. |
- Hyvonen, R., et al.
(författare)
-
The likely impact of elevated [CO2], nitrogen deposition, increased temperature and management on carbon sequestration in temperate and boreal forest ecosystems: a literature review
- 2007
-
Ingår i: New Phytologist. - Cambridge : Wiley. - 0028-646X .- 1469-8137. ; 173:3, s. 463-480
-
Forskningsöversikt (refereegranskat)abstract
- Temperate and boreal forest ecosystems contain a large part of the carbon stored on land, in the form of both biomass and soil organic matter. Increasing atmospheric [CO2], increasing temperature, elevated nitrogen deposition and intensified management will change this C store. Well documented single-factor responses of net primary production are: higher photosynthetic rate (the main [CO2] response); increasing length of growing season (the main temperature response); and higher leaf-area index (the main N deposition and partly [CO2] response). Soil organic matter will increase with increasing litter input, although priming may decrease the soil C stock initially, but litter quality effects should be minimal (response to [CO2], N deposition, and temperature); will decrease because of increasing temperature; and will increase because of retardation of decomposition with N deposition, although the rate of decomposition of high-quality litter can be increased and that of low-quality litter decreased. Single-factor responses can be misleading because of interactions between factors, in particular those between N and other factors, and indirect effects such as increased N availability from temperature-induced decomposition. In the long term the strength of feedbacks, for example the increasing demand for N from increased growth, will dominate over short-term responses to single factors. However, management has considerable potential for controlling the C store.
|
|
