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Baseline Diameter (baseline + diameter)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

ApoE allelic variability influences pupil response to cholinergic challenge and cognitive impairment

GENES, BRAIN AND BEHAVIOR, Issue 3 2007
L.F.M. Scinto
Exaggerated pupil response to dilute tropicamide has been suggested as an early biological marker for Alzheimer's disease. The current study links apolipoprotein E (ApoE) allelic variability to the magnitude of pupil response in a sample of community-dwelling elderly without a diagnosis of Alzheimer's disease or dementia. Possession of an ,4 allele influences both the likelihood of exhibiting an exaggerated pupil response above a predetermined cut-off (13% above baseline diameter) and the absolute overall magnitude of the response. Allelic variability was also shown to correlate with cognitive impairments in memory and attention. The data in this study further elucidate the nature of the biological bond between an exaggerated pupil response and the pathology of Alzheimer's disease. ApoE allelic variability is probably linked to pupil response through its influence on tau hyperphosphorylation. The early Alzheimer's pathology seen in the Edinger,Westphal area of cranial nerve III, a major centre for pupil control, is primarily tau-based with significant cell loss in this nucleus leading to central denervation hypersensitivity even in elderly who are clinically silent but who have early pathology. [source]

Effects of atrial natriuretic peptide on the extrasplenic microvasculature and lymphatics in the rat in vivo

THE JOURNAL OF PHYSIOLOGY, Issue 1 2005
Zoë L. S. Brookes
We developed a novel model using fluorescent intravital microscopy to study the effect of atrial natriuretic peptide (ANP) on the extrasplenic microcirculation. Continuous infusion of ANP into the splenic artery (10 ng min,1 for 60 min) of male Long,Evans rats (220,250 g, n= 24) induced constriction of the splenic arterioles after 15 min (,7.2 ± 6.6% from baseline diameter of 96 ± 18.3 ,m, mean ±s.e.m.) and venules (,14.4 ± 4.0% from 249 ± 25.8 ,m; P < 0.05). At the same time flow did not change in the arterioles (from 1.58 ± 0.34 to 1.27 ± 0.27 ml min,1), although it decreased in venules (from 1.67 ± 0.23 to 1.15 ± 0.20 ml min,1) and increased in the lymphatics (from 0.007 ± 0.001 to 0.034 ± 0.008 ml min,1; P < 0.05). There was no significant change in mean arterial pressure (from 118 ± 5 to 112 ± 5 mmHg). After continuous ANP infusion for 60 min, the arterioles were dilated (108 ± 16 ,m, P < 0.05) but the venules remained constricted (223 ± 24 ,m). Blood flow decreased in both arterioles (0.76 ± 0.12 ml min,1) and venules (1.03 ± 0.18 ml min,1; P < 0.05), but was now unchanged from baseline in the lymphatics (0.01 ± 0.001 ml min,1). This was accompanied by a significant decrease in MAP (104 ± 5 mmHg; P < 0.05). At 60 min, there was macromolecular leak from the lymphatics, as indicated by increased interstitial fluorescein isothiocyanate,bovine serum albumin fluorescence (grey level: 0 = black; 255 = white; from 55.8 ± 7.6 to 71.8 ± 5.9, P < 0.05). This study confirms our previous proposition that, in the extrasplenic microcirculation, ANP causes greater increases in post- than precapillary resistance, thus increasing intrasplenic capillary hydrostatic pressure (Pc) and fluid efflux into the lymphatic system. Longer-term infusion of ANP also increases Pc, but this is accompanied by increased ,permeability' of the extrasplenic lymphatics, such that fluid is lost to perivascular third spaces. [source]

Genotype,phenotype relationships in an investigation of the role of proteases in abdominal aortic aneurysm expansion

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 11 2005
P. Eriksson
Background: The aim of the study was to investigate the effect of functional polymorphisms in promoters of matrix metalloproteinase (MMP) 2, MMP-3, MMP-9, MMP-12 and plasminogen activator inhibitor (PAI) 1 genes on the growth rate of small abdominal aortic aneurysms (AAA). Methods: Some 455 individuals with a small AAA (4·0,5·5 cm) were monitored for aneurysm growth by ultrasonography (mean follow-up 2·6 years). They also provided a DNA sample for analysis of the ,1306 C > T, ,1171 5A > 6A, ,1562 C > T, ,82 A > G and ,675 4G > 5G alleles of MMP-2, MMP-3, MMP-9, MMP-12 and PAI-1, respectively. Mean linear AAA growth rates were calculated by flexible modelling; the sample size was sufficient to detect variants that influenced the growth rate by 25 per cent. Results: For MMP-2, MMP-9 and MMP-12 genotypes, growth rates were similar to the mean linear growth rate of 3·08 mm per year. For MMP-3, growth rates were 3·05 (for 5A5A), 3·19 (for 5A6A) and 2·90 (for 6A6A) mm per year. For PAI-1, patients with 4G4G, 4G5G and 5G5G genotypes had growth rates of 3·18, 2·92 and 3·47 mm per year, respectively, for aneurysms with a baseline diameter of 45·1, 44·6 and 46·2 mm. The increased growth rate for patients with PAI-1 5G5G genotype was not statistically significant (P = 0·061), although these patients had the lowest plasma PAI-1 concentrations (P = 0·018). Conclusion: There was no evidence that any specific MMP polymorphism had a clinically significant effect on AAA expansion. The plasminogen system may have a small but clinically significant role in AAA development. Much larger studies would be needed to evaluate genes of smaller effect. Copyright © 2005 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source]

Resource allocation and fluid intelligence: Insights from pupillometry

PSYCHOPHYSIOLOGY, Issue 1 2010
Elke Van Der Meer
Abstract Thinking is biological work and involves the allocation of cognitive resources. The aim of this study was to investigate the impact of fluid intelligence on the allocation of cognitive resources while one is processing low-level and high-level cognitive tasks. Individuals with high versus average fluid intelligence performed low-level choice reaction time tasks and high-level geometric analogy tasks. We combined behavioral measures to examine speed and accuracy of processing with pupillary measures that indicate resource allocation. Individuals with high fluid intelligence processed the low-level choice reaction time tasks faster than normal controls. The task-evoked pupillary responses did not differ between groups. Furthermore, individuals with high fluid intelligence processed the high-level geometric analogies faster, more accurately, and showed greater pupil dilations than normal controls. This was only true, however, for the most difficult analogy tasks. In addition, individuals with high fluid intelligence showed greater preexperimental pupil baseline diameters than normal controls. These results indicate that individuals with high fluid intelligence have more resources available and thus can solve more demanding tasks. Moreover, high fluid intelligence appears to be accompanied by more task-free exploration. [source]