Effect of propofol on the medial temporal lobe emotional memory system: a functional magnetic resonance imaging study in human subjects

BACKGROUND

Subclinical doses of propofol produce anterograde amnesia, characterized by an early failure of memory consolidation. It is unknown how propofol affects the amygdala-dependent emotional memory system, which modulates consolidation in the hippocampus in response to emotional arousal and neurohumoral stress. We present an event-related functional magnetic resonance imaging study of the effects of propofol on the emotional memory system in human subjects.

METHODS

Thirty-five healthy subjects were randomized to receive propofol, at an estimated brain concentration of 0.90 μg ml(-1), or placebo. During drug infusion, emotionally arousing and neutral images were presented in a continuous recognition task, while blood-oxygen-level-dependent activation responses were acquired. After a drug-free interval of 2 h, subsequent memory for successfully encoded items was assessed. Imaging analysis was performed using statistical parametric mapping and behavioural analysis using signal detection models.

RESULTS

Propofol had no effect on the stereotypical amygdalar response to emotional arousal, but caused marked suppression of the hippocampal response. Propofol caused memory performance to become uncoupled from amygdalar activation, but it remained correlated with activation in the posterior hippocampus, which decreased in proportion to amnesia.

CONCLUSIONS

Propofol is relatively ineffective at suppressing amygdalar activation at sedative doses, but abolishes emotional modulation and causes amnesia via mechanisms that commonly involve hyporesponsiveness of the hippocampus. These findings raise the possibility that amygdala-dependent fear systems may remain intact even when a patient has diminished memory of events. This may be of clinical importance in the perioperative development of fear-based psychopathologies, such as post-traumatic stress disorder.

CLINICAL TRIAL REGISTRATION

NCT00504894.

A single stent strategy in patients with lifestyle limiting claudication: 3-year results from the Durability II trial

OBJECTIVES

To evaluate longer-term safety and efficacy of a single self-expanding stent up to 20 cm in length in patients with atherosclerotic disease of the superficial femoral (SFA) and proximal popliteal arteries.

BACKGROUND

Angioplasty and stenting are options for revascularization of symptomatic peripheral artery disease. While angioplasty alone is effective in short lesions, outcomes in longer lesions (i.e., mean 8.7 cm) show suboptimal patency rates of 33% at one year.

METHODS

Two hundred eighty-seven patients (mean age 68 years, 66% male) were treated with the EverFlex™ Self-Expanding Peripheral Stent System. Patients were followed through 3 years with yearly core lab adjudicated duplex ultrasonography for patency, radiographic assessment of stent fractures, and resting ankle brachial indices.

RESULTS

Overall freedom from loss of primary patency at 3 years was 60.0%. Patency was significantly higher for lesions ≤8 cm compared with lesions >8 cm (71.0 vs. 50.5%, P < 0.0001). There was no significant difference in patency between single-stent and multistent recipients (60.4 vs. 52.4%, P = 0.343). The three-year freedom from clinically driven target lesion revascularization was 70.0%. At 3 years, the overall stent fracture rate was 0.9%.

CONCLUSIONS

DURABILITY II is the first investigational device exemption trial to report 3-year duplex Doppler defined stent patency and CD-TLR outcomes in long SFA and proximal popliteal lesions and demonstrated acceptable stent patency and freedom from CD-TLR with a low fracture rate. These data suggest that use of a single long stent provides reasonable long-term outcomes when intervention is required for symptomatic SFA and proximal popliteal arterial disease.

One-year results of the ANCHOR trial of EndoAnchors for the prevention and treatment of aortic neck complications after endovascular aneurysm repair

Objectives

EndoAnchors have been used to address proximal aortic neck complications including type Ia endoleaks and endograft migration after endovascular aortic aneurysm repair (EVAR).

Methods

The study population included 100 patients with one-year follow-up in the ANCHOR study. A primary cohort ( N = 73) comprised patients who underwent EndoAnchor implantation at the time of an initial EVAR and a Revision cohort ( N = 27) included patients treated remote from EVAR. A hostile neck was defined for neck length <10 mm, neck diameter >28 mm, angulation >60°, conical configuration or significant mural thrombus or calcium.

Results

Baseline anatomy included neck length of 17 ± 14 mm, diameter of 27 ± 5 mm, and angulation of 35 ± 18°; 83% of patients had hostile necks. Over 18 ± 4 months of clinical follow-up, six patients (6%) underwent aneurysm-related reinterventions. There were no aneurysm ruptures. Over 13 ± 2 months of imaging follow-up, freedom from type Ia endoleak was 95% in the Primary Arm and 77% in the Revision Arm ( P = .006). Aneurysm sacs regressed > 5 mm within one year in 45% of the Primary cases and in 25% of the Revisions. Aneurysm expansion > 5 mm occurred in one revision patient.

Conclusion

Despite a high frequency of hostile neck anatomy, proximal neck complications were relatively infrequent after EndoAnchor use.

Plasma protein biomarkers of Alzheimer's disease endophenotypes in asymptomatic older twins: early cognitive decline and regional brain volumes

There is great interest in blood-based markers of Alzheimer's disease (AD), especially in its pre-symptomatic stages. Therefore, we aimed to identify plasma proteins whose levels associate with potential markers of pre-symptomatic AD. We also aimed to characterise confounding by genetics and the effect of genetics on blood proteins in general. Panel-based proteomics was performed using SOMAscan on plasma samples from TwinsUK subjects who are asymptomatic for AD, measuring the level of 1129 proteins. Protein levels were compared with 10-year change in CANTAB-paired associates learning (PAL; n = 195), and regional brain volumes (n = 34). Replication of proteins associated with regional brain volumes was performed in 254 individuals from the AddNeuroMed cohort. Across all the proteins measured, genetic factors were found to explain ~26% of the variability in blood protein levels on average. The plasma level of the mitogen-activated protein kinase (MAPK) MAPKAPK5 protein was found to positively associate with the 10-year change in CANTAB-PAL in both the individual and twin difference context. The plasma level of protein MAP2K4 was found to suggestively associate negatively (Q < 0.1) with the volume of the left entorhinal cortex. Future studies will be needed to assess the specificity of MAPKAPK5 and MAP2K4 to eventual conversion to AD.