Neutralizing circulating ghrelin by expressing a growth hormone secretagogue receptor-based protein protects against high-fat diet-induced obesity in mice

Ghrelin is a stomach-derived peptide hormone that stimulates appetite and promotes adiposity through binding to the growth hormone secretagogue receptor (GHS-R1a). Administration of ghrelin in rodents increases weight gain due to stimulating food intake and reducing fat utilization. Therefore, reducing circulating ghrelin levels holds the potential to reduce weight gain. We developed a GHS-R1a-fusion constructs of a decoy protein containing the ligand-binding domains of the ghrelin receptor. Intramuscular injection of the GHSR/Fc plasmid decreased circulating levels of acylated-ghrelin. When challenged with the high fat diet, treated mice displayed reduced weight gain compared with controls, which was associated with reduced fat accumulation in the peritoneum but not lean mass. Quantitative PCR with reverse transcription showed increased PPARγ and hormone sensitive lipase transcripts levels in adipose tissue of treated animals, illustrating a preference for increased fat utilization. Intra-peritoneal glucose tolerance and insulin tolerance tests showed improved glucose clearance and insulin sensitivity in GHSR/Fc treated animals. We suggest that in vivo expression of the GHSR-based fusion protein prevents diet-induced weight gain, altering adipose gene expression and improving glucose tolerance. These findings, while confirming the role of ghrelin in peripheral energy metabolism, suggest that a strategy involving neutralization of the circulation ghrelin by intramuscular injection of the GHSR1/Fc fusion construct may find clinical application in the treatment of obesity.

Integrating silver compounds and nanoparticles into ceria nanocontainers for antimicrobial applications

Silver compounds and nanoparticles (NPs) are gaining increasing interest in medical applications, specifically in the treatment and prevention of biomaterial-related infections.

A functional model of the human C1 complex Emergence of a functional model

Precise structural data on C1s-C1r-C1r-C1s, the catalytic subunit of C1 (the first component of the classical pathway of human complement), led to the emergence of a structural and functional model of this complex protease. Now with new structural information on the amino acid sequence of the protease responsible for C1 activation (C1r), Gérard Arlaud and his colleagues propose a refinement of their original C1 model, and an overall scheme of the intramolecular events associated with the activation and control of C1.

Metformin directly inhibits ghrelin secretion through AMP-activated protein kinase in rat primary gastric cells

The antidiabetic drug Metformin causes weight loss in both diabetic and non-diabetic individuals. Metformin treatment is also associated with lower circulating levels of the orexigenic hormone ghrelin. To test whether Metformin directly affects ghrelin cells, rat primary stomach cells were treated with Metformin and the levels of ghrelin secretion, proghrelin gene expression and activation of adenosine monophosphate-activated protein kinase (AMPK) were examined. Metformin significantly reduced ghrelin secretion and proghrelin mRNA production and both these effects were blocked by co-incubation with the AMPK inhibitor compound C. Furthermore, the AMPK activator 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (AICAR) significantly inhibited ghrelin secretion. Additionally, ghrelin cells were shown to express AMPK. Finally, Metformin treatment caused a significant increase in the level of phosphorylated (active) AMPK. Our results show that Metformin directly inhibits stomach ghrelin production and secretion through AMPK. This reduction in ghrelin secretion may be one of the key components in Metformin's mechanism of weight loss.

Versatile apparatus for attosecond metrology and spectroscopy

We present the AS-2 Attosecond Beamline at the Joint Laboratory for Attosecond Physics of the Max-Planck-Institut für Quantenoptik and Ludwig-Maximilians-Universität for time resolved pump/probe experiments with attosecond resolution. High harmonic generation and subsequent filtering of the generated extreme ultraviolet (XUV) continuum by means of metal filters and XUV multilayer mirrors serve for the generation of isolated attosecond laser pulses. After high harmonic generation, the remaining fundamental laser pulse is spatially separated from the attosecond XUV pulse, to what is to our knowledge for the first time, by means of a perforated mirror in a Mach-Zehnder interferometer. Active stabilization of this interferometer guarantees the necessary temporal resolution for tracking attosecond dynamics in real time. As a proof-of-principle, photoelectron streaking experiments are performed and experimental techniques for their realization are summarized. Finally we highlight the potential of the presented beamline system for future experiments in comparison with previously demonstrated attosecond beamlines.

A systematic review of interventions promoting clinical information retrieval technology (CIRT) adoption by healthcare professionals

PURPOSE

This paper presents the evidence on the effectiveness of interventions promoting the use of clinical information retrieval technologies (CIRTs) by healthcare professionals.

METHODS

We electronically searched articles published between January 1990 and March 2008 using following inclusion criteria: (1) participants were healthcare professionals; (2) specific intervention promoted CIRT adoption; (3) studies were randomised controlled trials, controlled clinical trials, controlled before and after studies or interrupted time series analyses; and (4) they objectively reporting measured outcomes on CIRT use.

RESULTS

We found nine studies focusing on CIRT use. Main outcomes measured were searching skills and/or frequency of use of electronic databases by healthcare professionals. Three studies reported a positive effect of the intervention on CIRT use, one showed a positive impact post-intervention, and four studies failed to demonstrate significant intervention effect. The ninth study examined financial disincentives, and found a significant negative effect of introducing user fees for searching MEDLINE in clinical settings. A meta-analysis showed that educational meetings were the only type of interventions reporting consistent positive effects on CIRT adoption.

CONCLUSION

CIRT is an information and communication technology commonly used in healthcare settings. Interventions promoting CIRT adoption by healthcare professionals have shown some success in improving searching skills and use of electronic databases. However, the effectiveness of these interventions remains uncertain and more rigorous studies are needed.

Attosecond streaking enables the measurement of quantum phase

Attosecond streaking, as a measurement technique, was originally conceived as a means to characterize attosecond light pulses, which is a good approximation if the relevant transition matrix elements are approximately constant within the bandwidth of the light pulse. Our analysis of attosecond streaking measurements on systems with a complex response to the photoionizing pulse reveals the relation between the momentum-space wave function of the outgoing electron and the result of conventional retrieval algorithms. This finding enables the measurement of the quantum phase associated with bound-continuum transitions.

Occlusion of the common and internal iliac arteries for aortoiliac aneurysm repair: experience with the Amplatzer vascular plug

BACKGROUND

We sought to evaluate and describe our centre's experience with the Amplatzer vascular plug (AVP) for the occlusion of common and internal iliac arteries (CIA; IIA) during endovascular aortic aneurysm repair (EVAR).

METHODS

We performed a retrospective analysis of 20 consecutive patients between October 2006 and December 2007, who underwent occlusion of the CIA or IIA before or during EVAR to prevent endoleak.

RESULTS

Among these 20 patients, 21 occlusion procedures occurred and 20 were successful. In the only unsuccessful case, the patient had EVAR, but occlusion with an AVP was not possible because of severe narrowing at the origin of the vessel. Of the successfully treated patients, 2 presented with ruptured aneurysms, whereas the others had elective procedures. Eleven patients received aortouni-iliac grafts and femoral-femoral bypass, and 9 patients received a bifurcated stent graft. In 5 patients, the AVP occlusion and EVAR procedures were staged; in these cases occlusion occurred first, followed by EVAR on average 29 (standard deviation [SD] 23) days later. We deployed 7 AVPs in the CIA, whereas 13 were deployed in the IIA. The average diameter of the vessels occluded was 10 (SD 1) mm and the average size of the device used was 13 (SD 1) mm, representing a device diameter 28% (SD 2%) greater than the vessel diameter. We used a single device in 18 patients, whereas 2 devices were deployed in the same artery in 2 patients. Four patients underwent concomitant coil embolization. On follow-up computed tomography (CT) scans, all occlusion procedures were clinically successful. At the 14-month (SD 1 mo) follow-up, 4 patients had a small type-II endoleak unrelated to the occlusion procedure and 1 had a type-I endoleak that required graft limb extension. Four patients had buttock claudication but none had changes in sexual function, ischemic complications or device dislodgement on CT scans.

CONCLUSION

The AVP is a safe and effective method to occlude the CIA and IIA in patients undergoing EVAR.

Canadian experience with percutaneous endovascular aneurysm repair: short-term outcomes

BACKGROUND

To decrease the morbidity associated with cut-downs during endovascular aneurysm repair, some authors have suggested the totally percutaneous endovascular repair (PEVAR). The goal of this report is to evaluate and describe our centre's experience with the total percutaneous endovascular aneurysm repair (PEVAR) for aortic abdominal aneurysm (AAA).

METHODS

We performed a retrospective analysis of 15 consecutive patients with AAA, including 1 with right common iliac artery aneurysm.

RESULTS

There were 12 men and 3 women with a mean age of 74 (standard deviation [SD] 2) years who underwent PEVAR with a Perclose ProGlide suture-mediated closure system between July 2007 and July 2008. All surgeries were elective. Forty percent of patients had a history of smoking, 73% were hypertensive, 33% were diabetic, 20% had chronic obstructive pulmonary disease and 40% had coronary artery disease. Fourteen patients had bilateral deployment for bifurcated devices (7 bifurcated Gore Excluder, 7 bifurcated Cook Zenith grafts), and 1 patient had unilateral deployment for a Cook Zenith device. The outer diameter of the sheaths used for puncture sites was on average 18.1-Fr (SD 0.6), with main bodies being 21.1-Fr (SD 0.3) and contralateral sides 15-Fr (SD 0.3). Procedural success was 93%, with 1 patient requiring a femoral artery cut-down because of failure of the Perclose device to deploy in the groin. Another patient had persistent venous bleeding in 1 puncture site that stopped with skin suturing. Endovascular aneurysm repair was 100% with no conversion to open surgery and no type-I endoleaks. The mean length of stay in hospital was 2.2 (SD 0.4) days. There were no long-term groin complications at 6 (SD 1) months' follow-up.

CONCLUSION

To our knowledge, this is the first Canadian report of experience with PEVAR using the Perclose device. The technique is safe, reliable and allows discharge of patients soon after surgery.

Use of short-radius centrifugation to augment ankle-brachial indices

BACKGROUND

Peripheral arterial disease is mainly caused by atherosclerosis and is characterized by decreased circulation, lower blood pressure, and insufficient tissue perfusion in the lower extremities. The hemodynamics of standing and altered gravity environments have been well studied relative to arm blood pressures but are less well understood for ankle pressures.

METHODS

Because regional blood pressure depends, in part, on the gravitational pressure gradient, we hypothesized that artificial gravity exposure on a short-arm centrifuge with the center of rotation above the head would increase blood pressure in the lower extremities. Cardiovascular parameters for 12 healthy subjects were measured during exposure to supine short-arm centrifugation at 20, 25, and 30 revolutions per minute (rpm), corresponding to centripetal accelerations of 0.94, 1.47, and 2.11 Gz at the foot level, respectively.

RESULTS

Systolic ankle blood pressure significantly increased at all levels of centrifugation. Ankle-brachial indices (the ratio of systolic ankle to arm blood pressures) increased significantly from 1.17 +/- 0.03 to 1.58 +/- 0.03 at 0.94 Gz (P < 0.005), 1.74 +/- 0.02 at 1.47 Gz (P < 0.005), and 1.89 +/- 0.06 at 2.11 Gz (P < 0.005). Systolic arm blood pressure significantly increased at 2.11 Gz, but heart rate did not change significantly. All parameters returned to normal after cessation of centrifugation.

CONCLUSIONS

We demonstrated that short-radius centrifugation leads to an increase in ankle-brachial indices. This could have potential implications for the treatment of peripheral arterial disease.

Adventitial Cystic Disease of Common Femoral Artery

Adventitial cystic disease (ACD) is an uncommon cause of ischemia. The majority of ACD is located in the popliteal artery. Over 49 extrapopliteal locations have been described. We report on a case of femoral artery ACD in a young patient with claudication. The diagnosis was made with duplex ultrasound and confirmed with computed tomographic angiogram. The patient underwent a surgical treatment. One year postoperatively, the patient is active with no claudication. To our knowledge, this is the first reported case of extrapopliteal artery ACD in Canada.