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Arnljot Flaa Øivind Ekeberg Sverre Erik Kjeldsen Morten Rostrup 《BioPsychoSocial medicine》2007,1(1):1-8
Background
Possible mechanisms behind psychophysiological hyperreactivity may be located at a cognitive-emotional level. Several personality traits have been associated with increased cardiovascular reactivity. Subjects with white coat hypertension, which may constitute a kind of hyperreactivity, are found to suppress their emotions and adapt to the surroundings to a larger extent than controls. 相似文献3.
Anders Hougaard Bettina Hagstr?m Jensen Faisal Mohammad Amin Egill Rostrup Michael B. Hoffmann Messoud Ashina 《PloS one》2015,10(5)
Hemispheric asymmetry of a wide range of functions is a hallmark of the human brain. The visual system has traditionally been thought of as symmetrically distributed in the brain, but a growing body of evidence has challenged this view. Some highly specific visual tasks have been shown to depend on hemispheric specialization. However, the possible lateralization of cerebral responses to a simple checkerboard visual stimulation has not been a focus of previous studies. To investigate this, we performed two sessions of blood-oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) in 54 healthy subjects during stimulation with a black and white checkerboard visual stimulus. While carefully excluding possible non-physiological causes of left-to-right bias, we compared the activation of the left and the right cerebral hemispheres and related this to grey matter volume, handedness, age, gender, ocular dominance, interocular difference in visual acuity, as well as line-bisection performance. We found a general lateralization of cerebral activation towards the right hemisphere of early visual cortical areas and areas of higher-level visual processing, involved in visuospatial attention, especially in top-down (i.e., goal-oriented) attentional processing. This right hemisphere lateralization was partly, but not completely, explained by an increased grey matter volume in the right hemisphere of the early visual areas. Difference in activation of the superior parietal lobule was correlated with subject age, suggesting a shift towards the left hemisphere with increasing age. Our findings suggest a right-hemispheric dominance of these areas, which could lend support to the generally observed leftward visual attentional bias and to the left hemifield advantage for some visual perception tasks. 相似文献
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Summary. The effects of dioxygen on tyrosine hydroxylase (TH) activity was studied, measuring the formation of DOPA from tyrosine,
3H2O from 3,5-3H-tyrosine, or by direct oxygraphic determination of oxygen consumption. A high enzyme activity was observed during the initial
1–2 min of the reactions, followed by a decline in activity, possibly related to a turnover dependent substoichiometrical
oxidation of enzyme bound Fe(II) to the inactive Fe(III) state. During the initial reaction phase, apparent K
m-values of 29–45 μM for dioxygen were determined for all human TH isoforms, i.e. 2–40 times higher than previously reported
for TH isolated from animal tissues. After 8 min incubation, the K
m (O2)-values had declined to an average of 20 ± 4 μM. Thus, TH activity may be severely limited by oxygen availability even at
moderate hypoxic conditions, and the enzyme is rapidly and turnover dependent inactivated at the experimental conditions commonly
employed to measure in vitro activities.
Authors’ address: Jan Haavik, Department of Biomedicine, University of Bergen, 5009 Bergen, Norway 相似文献
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Sigrún?D?gg?EddudóttirEmail authorView authors OrcID profile Egill?Erlendsson Guerún?Gísladóttir 《Vegetation History and Archaeobotany》2017,26(4):389-402
Vegetation plays a key role in preventing the remobilisation of tephra and aeolian activity following tephra fall. Recent volcanic eruptions in Iceland have highlighted the consequences of tephra fall for ecosystems and human health. Improved understanding of the mechanisms behind ecosystem recovery following tephra fall is particularly important for Iceland. Today?~42% of the country is classified as desert and unvegetated and sparsely vegetated areas are unable to trap tephra fall and prevent subsequent wind erosion. This paper presents palaeoenvironmental reconstructions before and after the Hekla 4 tephra from two lakes in Northwest Iceland, from within a woodland in the lowland, and in open woodland under stress at the highland margin. The c. 4,200 cal bp. Hekla 4 tephra is one of the most extensive Icelandic Holocene tephra layers and the eruption produced an estimated?~9 km3 of tephra. The palaeoecological reconstructions provide an insight into the responses of two relatively stable ecosystems to thick tephra deposits during a period of cooling climate. The understory vegetation in the lowland woodland was buried by the tephra, however Betula pubescens trees were not severely affected and the woodland recovered relatively quickly. In contrast, open woodland at the highland margin that was already at its ecological limit, shifted to dwarf shrub heath, a more resilient vegetation community in response to the tephra fall and cooling climate. 相似文献
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The molecular dissection of mtDNA haplogroup H confirms that the Franco-Cantabrian glacial refuge was a major source for the European gene pool
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Achilli A Rengo C Magri C Battaglia V Olivieri A Scozzari R Cruciani F Zeviani M Briem E Carelli V Moral P Dugoujon JM Roostalu U Loogväli EL Kivisild T Bandelt HJ Richards M Villems R Santachiara-Benerecetti AS Semino O Torroni A 《American journal of human genetics》2004,75(5):910-918
Complete sequencing of 62 mitochondrial DNAs (mtDNAs) belonging (or very closely related) to haplogroup H revealed that this mtDNA haplogroup--by far the most common in Europe--is subdivided into numerous subhaplogroups, with at least 15 of them (H1-H15) identifiable by characteristic mutations. All the haplogroup H mtDNAs found in 5,743 subjects from 43 populations were then screened for diagnostic markers of subhaplogroups H1 and H3. This survey showed that both subhaplogroups display frequency peaks, centered in Iberia and surrounding areas, with distributions declining toward the northeast and southeast--a pattern extremely similar to that previously reported for mtDNA haplogroup V. Furthermore, the coalescence ages of H1 and H3 (~11,000 years) are close to that previously reported for V. These findings have major implications for the origin of Europeans, since they attest that the Franco-Cantabrian refuge area was indeed the source of late-glacial expansions of hunter-gatherers that repopulated much of Central and Northern Europe from ~15,000 years ago. This has also some implications for disease studies. For instance, the high occurrence of H1 and H3 in Iberia led us to re-evaluate the haplogroup distribution in 50 Spanish families affected by nonsyndromic sensorineural deafness due to the A1555G mutation. The survey revealed that the previously reported excess of H among these families is caused entirely by H3 and is due to a major, probably nonrecent, founder event. 相似文献
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Amishi P. Jha Alexandra B. Morrison Justin Dainer-Best Suzanne Parker Nina Rostrup Elizabeth A. Stanley 《PloS one》2015,10(2)
We investigated the impact of mindfulness training (MT) on attentional performance lapses associated with task-unrelated thought (i.e., mind wandering). Periods of persistent and intensive demands may compromise attention and increase off-task thinking. Here, we investigated if MT may mitigate these deleterious effects and promote cognitive resilience in military cohorts enduring a high-demand interval of predeployment training. To better understand which aspects of MT programs are most beneficial, three military cohorts were examined. Two of the three groups were provided MT. One group received an 8-hour, 8-week variant of Mindfulness-based Mind Fitness Training (MMFT) emphasizing engagement in training exercises (training-focused MT, n = 40), a second group received a didactic-focused variant emphasizing content regarding stress and resilience (didactic-focused MT, n = 40), and the third group served as a no-training control (NTC, n = 24). Sustained Attention to Response Task (SART) performance was indexed in all military groups and a no-training civilian group (CIV, n = 45) before (T1) and after (T2) the MT course period. Attentional performance (measured by A’, a sensitivity index) was lower in NTC vs. CIV at T2, suggesting that performance suffers after enduring a high-demand predeployment interval relative to a similar time period of civilian life. Yet, there were significantly fewer performance lapses in the military cohorts receiving MT relative to NTC, with training-focused MT outperforming didactic-focused MT at T2. From T1 to T2, A’ degraded in NTC and didactic-focused MT but remained stable in training-focused MT and CIV. In sum, while protracted periods of high-demand military training may increase attentional performance lapses, practice-focused MT programs akin to training-focused MT may bolster attentional performance more than didactic-focused programs. As such, training-focused MT programs should be further examined in cohorts experiencing protracted high-demand intervals. 相似文献
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Otto M. Henriksen Lars T. Jensen Katja Krabbe Per Guldberg Tom Teerlink Egill Rostrup 《PloS one》2014,9(5)
Background and Purpose
Both cerebral hypoperfusion and vascular risk factors have been implicated in early aging of the brain and the development of neurodegenerative disease. However, the current knowledge of the importance of cardiovascular health on resting brain perfusion is limited. The aim of the present study was to elucidate the relation between brain perfusion variability and risk factors of endothelial dysfunction and atherosclerosis in healthy aged subjects.Methods
Thirty-eight healthy subjects aged 50–75 years old were included. Mean global brain perfusion was measured using magnetic resonance phase contrast mapping and regional brain perfusion by use of arterial spin labeling.Results
Mean global brain perfusion was inversely correlated with caffeine and hematocrit, and positively with end-tidal PCO2. Furthermore, the mean global brain perfusion was inversely correlated with circulating homocysteine, but not with asymmetric dimethylarginine, dyslipidemia or the carotid intima-media thickness. The relative regional brain perfusion was associated with circulating homocysteine, with a relative parietal hypoperfusion and a frontal hyperperfusion. No effect on regional brain perfusion was observed for any of the other risk factors. A multiple regression model including homocysteine, caffeine, hematocrit and end-tidal PCO2, explained nearly half of the observed variability.Conclusion
Both intrinsic and extrinsic factors influenced global cerebral perfusion variation between subjects. Further, the results suggest that the inverse relation between homocysteine and brain perfusion is owing to other mechanisms, than reflected by asymmetric dimethylarginine, and that homocysteine may be a marker of cerebral perfusion in aging brains. 相似文献9.
Claire Vit Egill Richard Florian Fournes Clmence Whiteway Xavier Eyer Delphine Lapaillerie Vincent Parissi Didier Mazel Cline Loot 《Nucleic acids research》2021,49(10):5654
Integrons confer a rapid adaptation capability to bacteria. Integron integrases are able to capture and shuffle novel functions embedded in cassettes. Here, we investigated cassette recruitment in the Vibrio cholerae chromosomal integron during horizontal transfer. We demonstrated that the endogenous integrase expression is sufficiently triggered, after SOS response induction mediated by the entry of cassettes during conjugation and natural transformation, to mediate significant cassette insertions. These insertions preferentially occur at the attIA site, despite the presence of about 180 attC sites in the integron array. Thanks to the presence of a promoter in the attIA site vicinity, all these newly inserted cassettes are expressed and prone to selection. We also showed that the RecA protein is critical for cassette recruitment in the V. cholerae chromosomal integron but not in mobile integrons. Moreover, unlike the mobile integron integrases, that of V. cholerae is not active in other bacteria. Mobile integrons might have evolved from the chromosomal ones by overcoming host factors, explaining their large dissemination in bacteria and their role in antibioresistance expansion. 相似文献
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