458 Patient Willingness to Undergo Elective Orthopaedic Surgery in Relation to the COVID-19 Outbreak

Objective

To determine patients’ willingness to undergo elective orthopaedic surgery during the COVID-19 pandemic.

Method

4 groups of patients were chosen based on type of surgery. A telephone survey was conducted, including questions on diagnosis, symptom duration, pain severity, co-morbidities, anxiety levels for COVID-19 and surgery. Patients were given the conditions for surgery and asked whether they would undergo surgery, have the operation carried out by another consultant and any factors that would increase their confidence.

Results

Of 200 patients, 156 participated (78%). 78.2% were willing to undergo surgery. There was a statistically significant difference in willingness between age groups 40-49 (100%) and 80 + (58.3%). Differences in willingness between surgery types, BOA risk class, sex, symptom duration and pain scores, were not statistically significant.

Patients unwilling to undergo surgery reported statistically higher anxiety scores for health (4.39) and surgery (4.62) compared to the willing group (2.89 and 2.71 respectively). Patients’ main concern was contracting COVID (35.2%).

Conclusions

Our study demonstrated that the majority of patients were willing to undergo surgery. This can be used to inform strategies for resuming elective surgeries. It has also highlighted several areas in patient perception that warrant further investigation and the importance of enhanced consent on the specific risks.

Synthesis of proteins by automated flow chemistry

Ribosomes can produce proteins in minutes and are largely constrained to proteinogenic amino acids. Here, we report highly efficient chemistry matched with an automated fast-flow instrument for the direct manufacturing of peptide chains up to 164 amino acids long over 327 consecutive reactions. The machine is rapid: Peptide chain elongation is complete in hours. We demonstrate the utility of this approach by the chemical synthesis of nine different protein chains that represent enzymes, structural units, and regulatory factors. After purification and folding, the synthetic materials display biophysical and enzymatic properties comparable to the biologically expressed proteins. High-fidelity automated flow chemistry is an alternative for producing single-domain proteins without the ribosome.

MR Imaging of Renal Transplant Rejection

The results of 62 consecutive MR examinations were correlated with the subsequent clinical course and histologic results. Twenty-six cases of rejection showed a marked diminution of cortico-medullary differentiation (CMD). The renal parenchymal vascular pattern and visibility of renal sinus fat were not markedly altered in rejection and there was no difference between normal and rejected allograft shape. The ability of MR imaging to diagnose renal transplant rejection is only based on CMD, which, however, is non-specific. In 2 cases of severe acute rejection, T2 weighted images showed an abnormal signal intensity of the cortex due to renal infarction. Our preliminary results in 8 patients with Gd-DOTA injection showed 2 cases with necrosis seen as areas with absent contrast enhancement. This technique seems to be promising in the detection of perfusion defects.

Hypofractionated Simultaneous Integrated Boost (SIB) versus Conventional Fractionation in Localized Prostate Cancer: A Randomized Pilot Study

PURPOSE

Radical prostatectomy or radiotherapy has comparable results in the treatment of localized prostate cancer. High dose external irradiation entails a prolonged 7-8 weeks of treatment with significant inconvenience to elderly patients. Hypofractionated regimen in prostate cancer depends on the distinctive radiobiological properties of prostate cancer cells; their relative low alpha beta ratio compared to that for late-reacting rectal tissue allows for significant dose escalation per fraction without expected increase in late normal tissue reaction.

PATIENTS AND MATERIALS

Between July 2012 and December 2013, twenty patients were blindly randomized into two groups. The planning target volume in the study group received 65Gy to 67.5Gy/25 fractions over 5 weeks. The patients in the control arm received 74Gy to 78Gy in 2Gy/fraction. Cost-benefit was evaluated for both regimens.

RESULTS

Both groups were comparable regarding risk factors, with no significant statistical differences. Four patients in the study group developed grade 2 urinary toxicity and one patient had grade 3 during treatment. At six months no patient had urinary symptoms. In the control arm 4 patients have grade 2 toxicity during treatment which disappeared at six months. The two groups showed no statistical difference in the mean quality of life. Serum PSA reached a nadir value of 0.02 and 0.04 in the study and control groups respectively at 3 month post-treatment. The cost of treatment for the study group was 25000 L.E. per patient compared to 40000 L.E. in the control group. The hypofractionated group consumed 31138 MU compared to 45611 MU for the control group with a p-value of 0.015.

CONCLUSION

Hypofractionated IMRT with concomitant boost for localized cancer prostate is a feasible option with lesser cost and comparable toxicities. Longer followup is required to assess the late effects before recommending it as a standard of care.

Brownian dynamics simulations of confined tethered polymers in shear flow: the effect of attractive surfaces

Coarse grain Brownian dynamics simulations of the bead-spring model are used to investigate the effect of attractive surfaces on the stretching of confined tethered polymers under shear flow. The weak and strong adsorbed regimes have been addressed by means of a coarse grain van der Waals potential to simulate polymer substrate interactions. Different stationary cyclic dynamics are observed upon varying shear flow intensity and surface potential strength. Polymer stretching decreases as increasing the attractive potential strength, breaking down the scaling predictions for non-adsorbed polymers. We found that adsorption is enhanced by the shear flow strength in agreement to simulations of adsorbed non-tethered polymers.

An optically actuated surface scanning probe

We demonstrate the use of an extended, optically trapped probe that is capable of imaging surface topography with nanometre precision, whilst applying ultra-low, femto-Newton sized forces. This degree of precision and sensitivity is acquired through three distinct strategies. First, the probe itself is shaped in such a way as to soften the trap along the sensing axis and stiffen it in transverse directions. Next, these characteristics are enhanced by selectively position clamping independent motions of the probe. Finally, force clamping is used to refine the surface contact response. Detailed analyses are presented for each of these mechanisms. To test our sensor, we scan it laterally over a calibration sample consisting of a series of graduated steps, and demonstrate a height resolution of ∼ 11 nm. Using equipartition theory, we estimate that an average force of only ∼ 140 fN is exerted on the sample during the scan, making this technique ideal for the investigation of delicate biological samples.

Stability analysis and thermal motion of optically trapped nanowires

We investigate the stability and thermal motion of optically trapped nanowires, with aspect ratios in the range 10-100. A simple analytical model is used to determine qualitative features of the system, assuming that the nanowire is weakly scattering and the incident beam is paraxial. As expected, the model predicts that the nanowire will align with the beam axis. In this configuration the translational stiffness coefficients of the trap approach their limiting values for long nanowires like O(L(-3)), where L is the nanowire length, the limit for the stiffness parallel to the beam axis being zero. The rotational stiffness coefficients vary more slowly, according to O(L(-1)). Also, it is predicted that defocusing decreases the translational stiffness perpendicular to the beam, while increasing rotational stiffness. These findings are reinforced by comparison with rigorous electromagnetic calculations which additionally reveal the effects of radiation pressure and finite scattering. A strong polarization effect is observed in the numerical simulations and coupled translational and rotational motions arise which influence the trap stability. The use of nanowire traps for force sensing is discusse.

Computer simulations of the growth of synthetic peptide fibres

We present a coarse-grained computer model designed to study the growth of fibres in a synthetic self-assembling peptide system. The system consists of two 28 residue α-helical sequences, denoted AB and CD, in which the interactions between the half peptides, A, B, C and D, may be tuned individually to promote different types of growth behaviour. In the model, AB and CD are represented by double ended rods, with interaction sites distributed along their lengths. Monte Carlo simulations are performed to follow fibre growth. It is found that lateral and longitudinal growth of the fibre are governed by different mechanisms--the former is diffusion limited with a very small activation energy for the addition of units, whereas the latter occurs via a process of secondary nucleation at the fibre ends. As a result, longitudinal growth generally proceeds more slowly than lateral growth. Furthermore, it is shown that the aspect ratio of the growing fibre may be controlled by adjusting the temperature and the relative strengths of the interactions. The predictions of the model are discussed in the context of published data from real peptide systems.

Calibration of optically trapped nanotools

Holographically trapped nanotools can be used in a novel form of force microscopy. By measuring the displacement of the tool in the optical traps, the contact force experienced by the probe can be inferred. In the following paper we experimentally demonstrate the calibration of such a device and show that its behaviour is independent of small changes in the relative position of the optical traps. Furthermore, we explore more general aspects of the thermal motion of the tool.