University of Turku

About: University of Turku is a education organization based out in Turku, Finland. It is known for research contribution in the topics: Population & Galaxy. The organization has 16296 authors who have published 45124 publications receiving 1505428 citations. The organization is also known as: Turun yliopisto & Åbo universitet.

Excess Copper Predisposes Photosystem II to Photoinhibition in Vivo by Outcompeting Iron and Causing Decrease in Leaf Chlorophyll

Abstract: Photoinhibition of photosystem II was studied in vivo with bean (Phaseolus vulgaris) plants grown in the presence of 03 (control), 4, or 15 μm Cu2+ Although photoinhibition, measured in the presence of lincomycin to block concurrent recovery, is faster in leaves of Cu2+-treated plants than in control leaves, thylakoids isolated from Cu-treated plants did not show high sensitivity to photoinhibition Direct effects of excess Cu2+ on chloroplast metabolism are actually unlikely, because the Cu concentration of chloroplasts of Cu-treated plants was lower than that of their leaves Excess Cu in the growth medium did not cause severe oxidative stress, collapse of antioxidative defenses, or loss of photoprotection Thus, these hypothetical effects can be eliminated as causes for Cu-enhanced photoinhibition in intact leaves However, Cu treatment lowered the leaf chlorophyll (Chl) concentration and reduced the thylakoid membrane network The loss of Chl and sensitivity to photoinhibition could be overcome by adding excess Fe together with excess Cu to the growth medium The addition of Fe lowered the Cu2+ concentration of the leaves, suggesting that Cu outcompetes Fe in Fe uptake We suggest that the reduction of leaf Chl concentration, caused by the Cu-induced iron deficiency, causes the high photosensitivity of photosystem II in Cu2+-treated plants A causal relationship between the susceptibility to photoinhibition and the leaf optical density was established in several plant species Plant species adapted to high-light habitats apparently benefit from thick leaves because the rate of photoinhibition is directly proportional to light intensity, but photosynthesis becomes saturated by moderate light

Validation in interpretive management accounting research

Abstract: This paper extends and contributes to emerging debates on the validation of interpretive research (IR) in management accounting. We argue that IR has the potential to produce not only subjectivist, emic understandings of actors’ meanings, but also explanations, characterised by a certain degree of “thickness”. Mobilising the key tenets of the modern philosophical theory of explanation and the notion of abduction, grounded in pragmatist epistemology, we explicate how explanations may be developed and validated, yet remaining true to the core premises of IR. We focus on the intricate relationship between two arguably central aspects of validation in IR, namely authenticity and plausibility. Working on the assumption that validation is an important, but potentially problematic concern in all serious scholarly research, we explore whether and how validation efforts are manifest in IR using two case studies as illustrative examples. Validation is seen as an issue of convincing readers of the authenticity of research findings whilst simultaneously ensuring that explanations are deemed plausible. Whilst the former is largely a matter of preserving the emic qualities of research accounts, the latter is intimately linked to the process of abductive reasoning, whereby different theories are applied to advance thick explanations. This underscores the view of validation as a process, not easily separated from the ongoing efforts of researchers to develop explanations as research projects unfold and far from reducible to mere technicalities of following pre-specified criteria presumably minimising various biases. These properties detract from a view of validation as conforming to pre-specified, stable, and uniform criteria and allow IR to move beyond the “crisis of validity” arguably prevailing in the social sciences.

Alpha-synuclein-immunoreactive cortical Lewy bodies are associated with cognitive impairment in Parkinson's disease

Abstract: Amygdala, hippocampus and six cortical gyri were examined for the Lewy body (LB) degeneration and Alzheimer’s disease (AD) type changes in 45 patients with Parkinson’s disease (PD). For detection of LBs, the brain areas were stained with an antibody against alpha-synuclein. The extent of neuropathological lesions was investigated in relation to cognitive dysfunction and apolipoprotein E (apoE) ɛ4 allele dosage. At least one cortical LB was found in 95% of cases (43/45). Furthermore, 40% of cases (18/45) had histological findings of definite AD (CERAD class C). Those PD cases with the apoE ɛ4 allele had a significantly greater number of cortical LBs than those without the apoE ɛ4 allele, but this was statistically significant only in precentral, angular and temporal gyri. The LB density correlated better with the number of plaques than with the density of tangles. The number of LBs in several cortical areas correlated significantly with the cognitive impairment. In stepwise linear regression analysis, the number of LBs in the cingulate gyrus and the amount of tangles in the temporal cortex remained statistically significant. When the CERAD class C was excluded, the correlation between cognitive decline and the number of LBs in cortical areas became even more pronounced. A stepwise linear regression analysis in these cases found the number of LBs in the frontal gyrus to be the statistically most significant predictor of cognitive impairment. This study shows, for the first time, that in PD, alpha-synuclein-positive cortical LBs are associated with cognitive impairment independent of AD-type pathology.

Dementia in Parkinson's disease is related to neuronal loss in the medial substantia nigra.

Abstract: Regional neuronal loss in the substantia nigra was studied in relation to extrapyramidal symptoms and dementia in 12 patients with idiopathic Parkinson's disease (PD) and in 18 control subjects. Four areas of the right substantia nigra were investigated at the level of the superior colliculus and caudal red nucleus. In Parkinson's disease, the percentages of neurons, from the medial to the lateral part of the substantia nigra, were reduced to 49%, 31%, 41%, and 25% of the control values. The number of neurons in the lateral part showed a negative correlation with the severity of rigidity and hypokinesia, whereas tremor was less noticeable in patients with few neurons. The degree of dementia of the patients had a significant correlation only with neuronal loss in the medial part of the substantia nigra, suggesting, in view of the topographical organization of the neurons in the substantia nigra, that intact projections to the caudate nucleus and limbic and cortical areas are a prerequisite for normal cognitive functioning and that their dysfunction leads to clinical dementia.