8:30am - 8:45am
Can Bioprosthetic Valve Thrombosis Be Promoted by Aortic Root Morphology? An in vitro Study
1ARTORG Center for Biomedical Engineering Research, University of Bern, Switzerland; 2Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Switzerland; 3Department of Cardiology, Inselspital, Bern University Hospital, Switzerland; 4Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, Switzerland
Introduction: Recent studies have shown that bioprosthetic valve thrombosis (BPVT) is more common than previously know. The wash-out sufficiency of the sinus portions behind the leaflets is believed to be a factor for BPVT, and regions with low blood flow and regions with turbulent flow have been linked to thrombus formation. The aim of this study, was to investigate the impact of aortic root morphology on the blood flow in the aortic sinuses in an in vitro flow loop, and compare the results with in vivo data obtained from transcatheter aortic valve implanted (TAVI) patients.
Method: Two different aortic root morphologies (symmetric and patient-specific) were fabricated with silicone. A bioprosthetic valve was inserted in both phantoms, and in vitro measurements were performed in a left heart flow loop at a heart rate of 60 beats per minute, a cardiac output of 3.5 l/min, and an aortic pressure of 105/65 mmHg. Contrast-agent (CA) was injected to visualize the flow in the aortic root. High-speed camera recordings were post-processed to quantify CA distribution in the aortic sinus, and compared with angiographic images after TAVI.
Results: The wash-out of the sinus portion and the flow in the aortic root were significantly affected by aortic root morphology. The arrival of CA at the aortic sinus had a different delay in the two phantoms, with arrival at 0.09 s and 0.16 s after valve opening in the symmetric and the patient-specific phantom, respectively. In the TAVI patients different delays of CA was also observed.
Conclusion: The blood flow in the aortic root and sinus is affected by aortic root morphology, and may therefore be a factor in BPVT. The aortic root morphology of a patient should therefore also be considered before prosthesis selection and positioning.
8:45am - 9:00am
Site Capacity to Screen for and Manage Renal Dysfunction Among HIV-Infected Persons Receiving Care in Low- and Middle-Income Countries (LMICs)
1Institute of Social and Preventive Medicine, University of Bern, Switzerland; 2University of Zambia, School of Medicine, Lusaka, Zambia; 3Icahn School of Medicine at Mount Sinai, New York, NY, USA; 4CMSDS, Abidjan, Côte d'Ivoire; 5HIV-NAT, Thai Red Cross AIDS Research Centre, Bangkok, Thailand; 6Indiana University School of Medicine, Indianapolis, IN, USA; 7Vanderbilt University School of Medicine, Nashville, TN, USA; 8City University of New York, New York, USA
Background: Acute kidney injury (AKI) and chronic kidney disease (CKD) are more common in HIV-infected, ART-treated adults than in the general population. Markers of renal dysfunction including microalbuminuria, proteinuria, and/or reduced glomerular filtration rate have been associated with increased mortality in HIV-infected patients. ART programs may be the largest chronic care programs implemented in LMICs, but little is known regarding their capacity to prevent, screen for, diagnose, and manage NCDs including kidney disease.
Methods: REDCap administeredcross-sectional site-level survey of non-communicable disease (NCD) screening and management capacities and practices among a stratified random sample of 95 HIV care and treatment sites in 29 LMICs within the International epidemiology Databases to Evaluate AIDS (IeDEA).
Results: 76 sites (80%) are located in an urban setting; 17 sites (18%) serve adults only, 61 (64%) serve both pediatric and adult patients, and 17 sites (18%) serve children only. 53 sites (56%) were of tertiary health care level (regional, provincial or university hospital). Screening for kidney complications was available in 90% (95% CI: 82 - 95) of sites. Screening availability is similar across income groups. Peritoneal dialysis and kidney transplantation are not available in any site located in a low income setting; hemodialysis is available in only 9% (95% CI: 3 – 23) of sites located within either a low or lower middle income country.
Conclusions: The majority of LMIC HIV care sites provide screening for and managing kidney disease onsite. However, tests allowing for identification of earlier stage disease (e.g. uACR) and definitive histopathologic determination (biopsy) are largely unavailable. Such preliminary data provide baseline information to guide the design of future, prospective studies.
9:00am - 9:15am
Electrophysiological Measurements During a Sounding Rocket Flight
1Lucerne School of Engineering and Architecture, Lucerne University of Applied Sciences and Arts, Horw, Switzerland; 2Institute for Surgical Technology & Biomechanics, Tissue & Organ Mechanobiology, University of Bern, Bern, Switzerland
The mechanism how cells detect external mechanical forces has not been fully clarified yet. Among other mechanisms, mechano-sensitive ion channels are thought to be of central importance in transducing the information on the physical force into a biological response. With the previously introduced “OoClamp” device, we are able to study the gating properties of such mechano-sensitive channels under various gravity conditions. The device applies an adapted patch clamp technique that has proven to be operational even during parabolic flights and on centrifugation up to 20 g. Within the REXUS program we have proposed to conduct electrophysiological measurements on-board of a sounding rocket.
In order to determine the transmembrane conductivity through the target ion channels, an oocyte from the Xenopus laevis frog was captured in a silicone chip. A small aperture electrically isolated a patch of the cell membrane. This membrane patch was located adjacent to a fluidic chip, allowing fast exchange of medium. By using particular drugs, the ion channels of interest can be pharmaceutically isolated. The conductivity across the patch under different treatment protocols was then measured using a four electrode voltage clamp setup. The experimental hardware as a whole was designed as a stacked structure. At the bottom, liquid containers and gas pressure cartridges were mounted. Above, six recording chambers and medium containers found place in a structure that allowed the insertion through a late access hatch. This enabled us to load the recoding chambers with fresh oocytes shortly before launch to insure optimal viability. The board computer, which controlled the entire experiment, was mounted on top of the hardware.
The aim of this experiment was to assess for the first time, whether electrophysiological measurements with Xenopus leavis oocytes on board of sounding rocket flights are possible. The experiment flew in March 2016 with the REXUS 20 flight.
9:15am - 9:30am
Living in Stone Age Switzerland—A Continuous Study of 5000 Year Old Human Bones from Switzerland
1Department of Physical Anthropology, Institute of Forensic Medicine, University of Bern, Switzerland; 2Department of Prehistory, Institute of Archaeological Sciences, University of Bern, Switzerland; 3Institute for Archaeological Sciences, Archaeo- and Palaeogenetics, University of Tübingen, Germany; 4Max Planck Institute for the Science of Human History, Jena, Germany; 5Senckenberg Centre for Human Evolution and Palaeoenvironment, University of Tübingen, Germany
Collective burials of the Late Neolithic (~4300-2400 BC) are found all over Europe; however, undisturbed inhumations are rare. Therefore, the dolmen of Oberbipp provides a great opportunity for a multidisciplinary study. The aim of the project is the reconstruction of the living conditions of Neolithic Swiss populations based on morphological and biochemical analyses.
Morphological methods are used to evaluate the minimum number of buried individuals, their age at death, stature, and the presence of pathologies and trauma. Stable isotope and aDNA analyses combined with 14C dating are applied to gain knowledge about dietary habits, migration patterns, and population dynamics. Biochemical analyses are carried out on pars petrosae and femora.
Over 1750 complete and fragmented bones are the base for the morphological study. A minimum of 40 people were buried in the dolmen and the age at death estimation revealed 37.5% (n=15/40) subadults and 62.5% (n=25/40) adults (based on the right femora). The aDNA results indicate an even presence of male (42.3%) and female (38.5%) individuals (19.2%=id; n=26). Stature estimations indicate a mean body height between 155-172 cm (n=4 bones). The caries intensity (CI) is 6.7% (n=21/313). The 14C dates indicate a use of the dolmen between 3350-2950 BC and a possible second occupation between 2900-2650 BC.
The first morphological data, including the CI, indicate a «normal» Late Neolithic population that corresponds well with other sides in Central Europe. Based on 14C and aDNA results it is assumed that the first occupation phase was not longer than 75 years (approx. 3 generations). The analysis of trauma and degenerative alterations on bones in addition to stable isotope analysis (C, N, S) will provide further information about the “health status” and dietary habits of this population. Combined with additional material from Central Europe a strong basis of knowledge about Late Neolithic populations of modern Switzerland will be generated.