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Query: UMLS:C0162871 (abdominal aortic aneurysm)
 8,664 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied 114 patients (out of a cohort of 797 consecutive patients admitted with abdominal aortic aneurysm) who were denied any immediate operation because of patient's refusal, high surgical risk, or small transverse diameter as assessed by CT scanning and ultrasonography. All patients not operated on, underwent from two to six repeated examinations during an average follow-up period of 16.8 months (range, 3 to 132). Forty-seven patients (41.2%) were subsequently operated on electively because of marked increase of transverse diameter of the aneurysm (n = 44) or for other reasons (n = 3), with a death rate of 0%. Eighteen other patients underwent emergency operation for leaking or ruptured aneurysms, and there were five deaths. The incidence of rupture was clearly related to the final diameter value, rising from 0% in aneurysms less than 40 mm to 22% in large size aneurysms (> or = 50 mm). Among the 49 patients not operated on, one died of rupture before operation and five of causes unrelated to the disease. Using individual serial measurements, we determined the linear expansion rate of the aneurysm, which proved to be related to initial diameter values: 5.3 mm/year for diameters less than 40 mm (n = 49), 6.9 mm/year in the 40 to 49 mm group (n = 41), and 7.4 mm/year for diameters of 50 mm or more (n = 24). We also fitted an exponential model to the patient data and determined in each case an "exponential" expansion rate expressed in year-1. The overall mean was equal to 0.129 year-1, and individual values were found to be independent of initial diameter size. The superiority of the exponential model over the linear model was shown to be statistically significant. Our study confirms that expansion of aneurysms is related to initial diameter values and shows that the time evolution of the disease process can be adequately described by an exponential model. It also suggests that rupture of aneurysms is not only related to their size but also to their rate of expansion.
Bull Mem Acad R Med Belg 1992
PMID:[Determination of level of expansion and incidence of rupture of abdominal aortic aneurysms]. 128 6

The relationship between atherosclerosis and abdominal aortic aneurysm development is well known. Atherosclerosis cannot explain the whole mechanism. Genetic characters of mechanisms leading to abdominal aortic development is obvious from this study and others. Our study evidences an increased metalloproteases activity in aortic wall proportionally to the size of the abdominal aortic aneurysm. A decrease of aortic wall elastin is evidenced proportionally to the AAA size. Extractable collagen is significantly increased in the aortic wall of patients operated on for aortic rupture.
Bull Mem Acad R Med Belg 1997
PMID:[Mechanism of the growth and rupture of abdominal aortic aneurysm]. 962 40

Using a conditioned suppression task, we investigated extinction and renewal of Pavlovian modulation in human sequential Feature Positive (FP) discrimination learning. In Experiment 1, in context a participants were first trained on two FP discriminations, X-->A+/A- and Y-->B+/B-. Extinction treatment was administered in the acquisition context a (aaa group) or in a new context b (aba group), and comprised X-->A- extinction and Y- control trials. Discriminative X-->A/A responding was lost in both groups when tested in the extinction context, but partially recovered in the aba and not in the aaa group when tested in the acquisition context, suggesting extinction and renewal of extinguished modulation. The same was observed for the Y-->B/B control pair, however, questioning whether the loss of discriminative X-->A/A responding represented genuine extinction of modulation. In Experiment 2, including only aba groups, participants were trained in context a on two FP discriminations, X-->A+/A- and Y-->B+/B-, after which the group "Extinction" was exposed to X-->A- extinction trials in context b, whereas the group "Control" was exposed to X- control trials; concurrently, both groups received further Y-->B+/B- training. In the group Control, differential Y-->B/B and X-->A/A responding were acquired and maintained throughout the experiment. In the group Extinction, while Y-->B/B responding was also maintained throughout, differential X-->A/A responding disappeared because of X-->A- extinction treatment when tested in the extinction context b, but partially reappeared when tested in the acquisition context a. This evidences aba-renewal of extinguished modulation.
Learn Mem
PMID:Extinction and renewal of Pavlovian modulation in human sequential Feature Positive discrimination learning. 1580 15

Extinction learning is modulated by N-methyl d-aspartate receptors (NMDAR) particularly in prefrontal and hippocampal brain regions. The use of of NMDA agonists in exposure therapy of anxiety disorders has been investigated in various patient groups. Behavioral results showed beneficial effects of pre-learning administration of the partial NMDAR agonist d-Cycloserine (DCS) on therapy success. However, the impact of DCS upon non-fear-related contextual extinction, and associated recruitment of extinction-relevant brain regions is as yet unknown. In the present fMRI study, healthy human participants performed a context-related associative learning and extinction task. A single dose of DCS, administered prior to extinction learning, enhanced extinction learning performance in an identical context, and increased activation in prefrontal, temporal as well as hippocampal/insular regions, compared to placebo controls. In contrast, DCS did not affect extinction learning in a novel context, nor the renewal effect, which describes the recovery of an extinguished response if the context of extinction differs from the context of recall. Our findings demonstrate a specific involvement of prefrontal and hippocampal NMDAR in the modification of established stimulus-outcome associations in identical contexts and thus their role in behavioral flexibility, underlining their potential for enhancing AAA extinction learning.
Neurobiol Learn Mem 2017 Oct
PMID:d-Cycloserine facilitates extinction learning and enhances extinction-related brain activation. 2880 95