A novel interface for hybrid mock circulations to evaluate ventricular assist devices

This paper presents a novel mock circulation for the evaluation of ventricular assist devices (VADs), which is based on a hardware-in-the-loop concept. A numerical model of the human blood circulation runs in real time and computes instantaneous pressure, volume, and flow rate values. The VAD to be tested is connected to a numerical-hydraulic interface, which allows the interaction between the VAD and the numerical model of the circulation. The numerical-hydraulic interface consists of two pressure-controlled reservoirs, which apply the computed pressure values from the model to the VAD, and a flow probe to feed the resulting VAD flow rate back to the model. Experimental results are provided to show the proper interaction between a numerical model of the circulation and a mixed-flow blood pump.

Quantifying leukocytes in first catch urine provides new insights into our understanding of symptomatic and asymptomatic urethritis

We quantitatively investigated inflammatory cells in the male urethra. Leukocytes in the first catch urine (FCU) from 87 men with and without urethritis were quantitated using haemocytometer counts and stained with an anti-CD45 pan-leukocyte antibody. An increased number of leukocytes in FCU specimens was associated with urethritis (P > 0.002), the presence of discharge and/or dysuria (P < 0.001), and detection of Chlamydia trachomatis (P < 0.001) and Neisseria gonorrhoeae (P < 0.001). In men with urethritis, higher leukocyte counts were also observed in the above groups (P = 0.07, 0.03 and P < 0.0001, respectively). As leukocyte number increased, the likelihood of detecting either pathogen increased. This study suggests that symptoms and signs are a surrogate marker for the degree of inflammation present, and that as urethral inflammation increases, the likelihood of detecting a sexually transmitted pathogen also increases. This would explain why men with asymptomatic urethritis are less likely to have a sexually transmitted infection detected than those with discharge and/or dysuria.

Computer-assisted arthroplasty using bioengineered autografts

Recent advances in tissue-engineered cartilage open the door to new clinical treatments of joint lesions. Common to all therapies with in-vitro-engineered autografts is the need for optimal fit of the construct to allow screwless implantation and optimal integration into the live joint. Computer-assisted surgery (CAS) techniques are prime candidates to ensure the required accuracy, while at the same time simplifying the procedure. A pilot study has been conducted aiming at assembling a new set of methods to support ankle joint arthroplasty using bioengineered autografts. Computer assistance allows planning of the implant shape on a computed tomography (CT) image, manufacturing the construct according to the plan, and interoperatively navigating the surgical tools for implantation. A rotational symmetric model of the joint surface was used to avoid segmentation of the CT image; new software was developed to determine the joint axis and make the implant shape parameterizable. A complete cycle of treatment from planning to operation was conducted on a human cadaveric foot, thus proving the feasibility of computer-assisted arthroplasty using bioengineered autografts