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.

Disc degeneration in magnetic resonance imaging. A comparative biochemical, histologic, and radiologic study in cadaver spines.

Abstract: Magnetic resonance imaging (MRI) findings of 89 autopsied intervertebral discs from 22 cadaveric lumbar spines were correlated with biochemical composition, conventional radiography, and histologic structure to study the nature of disc intensity changes seen in MRI. Discs with a low signal intensity on T2-weighted MRI were characterized by shortening of relaxation times, dehydration, and decreases in total proteoglycan content and chondroitin-keratan sulfate ratios in the nucleus pulposus. This corresponded well with previously published studies. In histologic structure, no obvious differences between MRI findings were found. In conclusion, a low signal intensity in a lumbar disc on T2-weighted MRI probably reflects a true biochemical disc degeneration, but its relation to structural degenerative changes is uncertain. Therefore, MRI seems to be a sensitive and a specific imaging modality for detecting pathologic biochemical disc changes in the spine of a young adult.

Integrin α2β1 Mediates Isoform-Specific Activation of p38 and Upregulation of Collagen Gene Transcription by a Mechanism Involving the α2 Cytoplasmic Tail

Abstract: Two collagen receptors, integrins α1β1 and α2β1, can regulate distinct functions in cells. Ligation of α1β1, unlike α2β1, has been shown to result in recruitment of Shc and activation of the Ras/ERK pathway. To identify the downstream signaling molecules activated by α2β1 integrin, we have overexpressed wild-type α2, or chimeric α2 subunit with α1 integrin cytoplasmic domain in human osteosarcoma cells (Saos-2) lacking endogenous α2β1. The chimeric α2/α1 chain formed a functional heterodimer with β1. In contrast to α2/α1 chimera, forced expression of α2 integrin resulted in upregulation of α1 (I) collagen gene transcription in response to three-dimensional collagen, indicating that the cytoplasmic domain of α2 integrin was required for signaling. Furthermore, signals mediated by α2β1 integrin specifically activated the p38α isoform, and selective p38 inhibitors blocked upregulation of collagen gene transcription. Dominant negative mutants of Cdc42, MKK3, and MKK4 prevented α2β1 integrin–mediated activation of p38α. RhoA had also some inhibitory effect, whereas dominant negative Rac was not effective. Our findings show the isoform-specific activation of p38 by α2β1 integrin ligation and identify Cdc42, MKK3, and MKK4 as possible downstream effectors. These observations reveal a novel signaling mechanism of α2β1 integrin that is distinct from ones previously described for other integrins.

How should we define fitness in structured metapopulation models? Including an application to the calculation of evolutionarily stable dispersal strategies.

Abstract: We define a fitness concept applicable to structured metapopulations consisting of infinitely many equally coupled patches. In addition, we introduce a more easily calculated quantity Rm that relates to fitness in the same manner as R0 relates to fitness in ordinary population dynamics: the Rm of a mutant is only defined when the resident population dynamics converges to a point equilibrium and Rm is larger (smaller) than 1 if and only if mutant fitness is positive (negative). Rm corresponds to the average number of newborn dispersers resulting from the (on average less than one) local colony founded by a newborn disperser. Efficient algorithms for calculating its numerical value are provided. As an example of the usefulness of these concepts we calculate the evolutionarily stable conditional dispersal strategy for individuals that can account for the local population density in their dispersal decisions. Below a threshold density x, at which staying and leaving are equality profitable, everybody should stay and above x everybody should leave, where profitability is measured as the mean number of dispersers produced through lines of descent consisting of non-dispersers.

Tweets as impact indicators: Examining the implications of automated bot accounts on Twitter

Abstract: This brief communication presents preliminary findings on automated Twitter accounts distributing links to scientific articles deposited on the preprint repository arXiv. It discusses the implication of the presence of such bots from the perspective of social media metrics altmetrics, where mentions of scholarly documents on Twitter have been suggested as a means of measuring impact that is both broader and timelier than citations. Our results show that automated Twitter accounts create a considerable amount of tweets to scientific articles and that they behave differently than common social bots, which has critical implications for the use of raw tweet counts in research evaluation and assessment. We discuss some definitions of Twitter cyborgs and bots in scholarly communication and propose distinguishing between different levels of engagement-that is, differentiating between tweeting only bibliographic information to discussing or commenting on the content of a scientific work.

Atherosclerosis precursors in Finnish children and adolescents. I. General description of the cross-sectional study of 1980, and an account of the children's and families' state of health

Abstract: The paper describes the general outline of a multicentre study on the risk factors of coronary heart disease (CHD) and their determinants in children of various ages in different parts of Finland. The study was a cross-sectional one, and was carried out in 1980 in five university cities of Finland with medical schools and in 12 rural communities in their vicinity. The randomized sample included an equal number of boys and girls, aged 3, 6, 9, 12, 15, and 18 years, and an equal number of urban and rural population in each area. The total sample size was 4,320 subjects, and of these 3,596 participated (83.1%). The families received before the medical examination of the child, questionnaires on the socioeconomic background the child's general health and development, the parents' and grandparents' health status, and the child's food and exercise habits. At the physical examination also a fasting blood sample (lipids, insulin, trace elements) was taken, a bundle of hair was cut for trace element analysis, and a 48-hour recall on food intake was obtained from every second subject. 19.5% of the children had in their history some long-term disease, allergic diseases being the most common. CHD and other cardiovascular diseases were significantly more frequent among the grandparents and parents in eastern than in western Finland. The study is meant to be a basis for a longitudinal study.