| 131. |
- Agius, Stephanie C, et al.
(författare)
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The internal rotenone-insensitive NADPH dehydrogenase contributes to malate oxidation by potato tuber and pea leaf mitochondria
- 1998
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317. ; 104:3, s. 329-336
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Tidskriftsartikel (refereegranskat)abstract
- Inside-out submitochondrial particles from both potato (Solanum tuberosum L. cv. Bintje) tubers and pea (Pisum sativum L. cv. Oregon) leaves possess three distinct dehydrogenase activities: Complex I catalyzes the rotenone-sensitive oxidation of deamino-NADH, NDin(NADPH) catalyzes the rotenone-insensitive and Ca2+-dependent oxidation of NADPH and NDin(NADH) catalyzes the rotenone-insensitive and Ca2+-independent oxidation of NADH. Diphenylene iodonium (DPI) inhibits complex I, NDin(NADPH) and NDin (NADH) activity with a Ki of 3.7, 0.17 and 63 µM, respectively, and the 400-fold difference in Ki between the two NDin made possible the use of DPI inhibition to estimate NDin (NADPH) contribution to malate oxidation by intact mitochondria. The oxidation of malate in the presence of rotenone by intact mitochondria from both species was inhibited by 5 µM DPI. The maximum decrease in rate was 10–20 nmol O2 mg-1 min-1. The reduction level of NAD(P) was manipulated by measuring malate oxidation in state 3 at pH 7.2 and 6.8 and in the presence and absence of an oxaloacetate-removing system. The inhibition by DPI was largest under conditions of high NAD(P) reduction. Control experiments showed that 125 µM DPI had no effect on the activities of malate dehydrogenase (with NADH or NADPH) or malic enzyme (with NAD+ or NADP+) in a matrix extract from either species. Malate dehydrogenase was unable to use NADP+ in the forward reaction. DPI at 125 µM did not have any effect on succinate oxidation by intact mitochondria of either species. We conclude that the inhibition caused by DPI in the presence of rotenone in plant mitochondria oxidizing malate is due to inhibition of NDin(NADPH) oxidizing NADPH. Thus, NADP turnover contributes to malate oxidation by plant mitochondria.
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| 132. |
- Agrell, Berit
(författare)
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Stroke in geriatric patients - Aspects of depression, cognition and motor activity
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Six depression rating scales, GDS, Zung, CES-D, CPRS-D and Cornell, were compared in 40 patients. The validity was good for all scales except for the Cornell scale. A comprehensive investigation was done in 116 elderly stroke patients. There was no difference in prevalence and severity of post-stroke depression in relation to side of lesion. A test for receptive aphasia, the Token test, showed that 75% of patients with left hemisphere lesion and aphasia, 36% of patients with right hemisphere lesion and 5% of controls had abnormal test initially. The relationships and sensitivity of different visuo-spatial neglect tests were examined. Sensitivity was around 50% for the best tests. Neglect patients showed a greater cognitive dysfunction initially and a slower recovery. The validity of a cognitive test, the MMSE, was examined. Five neuropsychological tests were used as a subgroup of patients.MMSE scores were significant lower for the patients than for the controls. The sensitivity of the MMSE was 56%, the specificity 80% and the false negative ratio 39% against the neuropsychological tests. Motor activity after stroke was assessed by parts of the Fugl-Meyer test in different infarction subgroups and initial severity groups. The initial severity groups were better predictors for outcome. Multiple regression showed three variables to be predictors: initial motor activity, Barthel Index and right hemisphere lesion.
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| 133. |
- Agrell, Cecilia
(författare)
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Atmospheric transport of persistent organic pollutants to aquatic ecosystems
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The load of persistent organic pollutants (POPs) is considered high in the Baltic ecosystem. The Baltic Sea spans over 12 latitudes and the regional differences in climate affect the behavior of POPs. Therefore spatial and temporal variability of the concentrations of POPs in air and precipitation within this area has been investgated at 16 (mostly rural) stations around the Baltic Sea between 1990-1993. In addition, the deposition of gaseous and particulate associated POPs to the Baltic Sea is estimated from empirical data. This atmospheric input of POPs is compared with the input from rivers. Additionally, data from Ross Island, Antarctica and Lake Kariba, Zimbabwe, Africa is presented, and all results are discussed and explained using the ”global fractionation hypothesis” as a framework. In the Baltic Sea, concentrations of individual POPs in air were found to be influenced by their physical-chemical properties, ambient air temperature and location. A latitudinal gradient, with higher levels in the south was found for PCBs and the gradient was more pronounced for the low volatility congeners. As a result, the high volatility congeners in air increased in relative importance with latitude. Generally, PCB concentrations increased with temperature, but slopes of the partial pressure in air versus reciprocal temperature were different between congeners and between stations. In general, the low volatility congeners were more temperature dependent than the high volatility PCB congeners. Steep slopes at a sampling location indicate that the concentration in air is largely determined by diffusive exchange with soils. Lack of a temperature dependence may be due to the influence of long-range transported air masses at remote sites and due to the episodic, or random nature of PCB sources at urban sites. The concentrations of individual congeners in precipitation were found to be influenced by atmospheric concentrations of PCBs, ambient temperature, precipitation volume and the compounds physical-chemical properties. Concentrations of PCBs in precipitation decreased with temperature, and the slopes of this relationship were the same for all stations but differed between congeners. High volatility congeners showed steeper slopes for the temperature relationship than did low volatility PCB congeners. Annual wash out ratios were calculated and found to decrease with congener volatility. Wash out ratios generally decreased with temperature. At snow scavenging events the wash out ratio of PCBs increased with a factor of 2. Latitudinal trends for PCB concentrations in precipitation and for deposition were not statistically significant, but tended to be higher in the south for low volatility congeners. For high volatility congeners the latitudinal trend was reversed. Deposition of PCB congeners varied seasonally, with a factor between 2.0-3.2, and was generally highest during fall. The calculated yearly deposition of PCBs to the Baltic Sea was 387 kg and 5-18 kg for individual congeners, with PCB-138 having the highest flux.
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| 134. |
- Agrell, Cecilia, et al.
(författare)
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Evidence of Latitudinal Fractionation of Polychlorinated Biphenyl Congeners along the Baltic Sea Region
- 1999
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 33:8, s. 1149-1156
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Tidskriftsartikel (refereegranskat)abstract
- Annual cycles of the atmospheric concentrations of PCBs were determined at 16 (mostly rural) stations around the Baltic Sea between 1990 and 1993. The concentration levels of individual congeners were found to be influenced by their physical-chemical properties, ambient temperature, and geographical location. Median levels of PCBs were similar at all stations except at one urban site near Riga. A latitudinal gradient with higher levels in the south was found for the sum of PCB as well as for individual congeners, and the gradient was more pronounced for the low volatility congeners. As a result, the high volatility congeners increased in relative importance with latitude. Generally, PCB concentrations increased with temperature, but slopes of the partial pressure in air versus reciprocal temperature were different between congeners and between stations. In general, the low volatility congeners were more temperature dependent than the high volatility PCB congeners. Steep slopes at a sampling location indicate that the concentration in air is largely determined by diffusive exchange with soils. Lack of a temperature dependence may be due to the influence of long-range transported air masses at remote sites and due to the episodic or random nature of PCB sources at urban sites.
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| 135. |
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| 136. |
- Ahadi, Aylin
(författare)
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Model representation of sand tests
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A non-associated plasticity model for friction materials was presented by Krenk (1999) and an efficient calibration procedure developed by Ahadi & Krenk (1999). The ability of the model to represent the behaviour of sand was verified by calibrating the model from different sets of triaxial drained tests for both loose and dense sand performed at different confining pressures. This paper is a collection of calibration and prediction examples. The model was calibrated according to the procedure described in Ahadi & Krenk (1999) and results were compared to experimental data from Borup & Hedegaard (1995) and Ibsen & Jakobssen (1996). The obtained material parameters indicate that the shear modulus $G$ should increase with the mean stress, while the increase of the bulk stiffness should be less than linear. The dependency on mean stress is studied by fitting a power law function for both $G$ and $kappa$. Finally prediction for undrained (constant volume) test at different initial pressures are presented with material parameter determined from drained triaxial test data.
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| 137. |
- Ahadi, Aylin, et al.
(författare)
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Non-associated plasticity for soils
- 1998
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Ingår i: Trita-BKN. Bulletin. - 1103-4270. ; , s. 19-22
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Konferensbidrag (refereegranskat)abstract
- A brief overview is given of a non-associated plasticity theory developed for soils based on the concept of a characteristic stress state of vanishing incremental dilation, and a calibration procedure using only test data from a standard triaxial test. The capability of the model is illustrated by calibration examples and predictions made for standard triaxial tests at different confining stress levels and constant volume tests on sand. The model is found to predict stress-strain behaviour and development of volumetric strain well.
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| 138. |
- Ahlberg, Per, et al.
(författare)
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Geological fieldwork in the Kirwanveggen area
- 1992
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Ingår i: Swedish Antarctic research programme : a cruise report. 1991/92, Dronning Maud Land, Livingston Island, South Georgia. - 9197076988 ; , s. 13-21
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Bokkapitel (refereegranskat)
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| 139. |
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| 140. |
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