A pharmacokinetic-pharmacodynamic (PKPD) model-based analysis of tedizolid against enterococci using the hollow-fibre infection model

BACKGROUND

Tedizolid is a novel oxazolidinone antibiotic. Considering the higher antibacterial effect in immunocompetent compared with immunosuppressed animals, it is not recommended in immunocompromised patients.

OBJECTIVES

In this study, we assessed the 'pure' pharmacokinetic-pharmacodynamic (PKPD) relationship for tedizolid against Enterococcus in the hollow-fibre infection model (HFIM).

METHODS

Unbound plasma concentration time profiles (200-5000 mg/day IV) were simulated in the HFIM over 120 h against an Enterococcus faecalis strain and two clinical isolates of Enterococcus faecium (VRE-vanB and VRE-vanA). Next, a PKPD model describing tedizolid efficacy against bacterial isolates was developed. A population PK model was linked to the developed PKPD model and utilized to predict the bacterial kinetics in plasma and in target tissues [adipose, muscle, epithelial lining fluid (ELF) and sputum] over 120 h of therapy.

RESULTS

The PKPD model adequately described the bacterial kill kinetics for all bacterial populations. At the human recommended dose of 200 mg/day, bacterial growth was predicted in plasma and all tissues, except for ELF. Bacteriostasis was observed only at a higher dose of 1200 mg/day over 120 h. An fAUC/MIC of 80 related to stasis over 120 h. Subpopulations resistant to 3 × MIC were amplified in plasma and target tissues, except for ELF, at doses of 200-800 mg/day.

CONCLUSIONS

The human dose of 200 mg/day was insufficient to suppress bacterial growth in the HFIM, indicating that further components contribute to the clinical effect of tedizolid. This study supports the warning/precaution for tedizolid to limit its use in immunocompromised patients.

SP7.1.3 An integrated and upgraded meta-analysis of published randomized, controlled trials exploring the role of oral metronidazole as post-operative proctological analgesic agent

Aims

Proctological procedures such as haemorrhoidectomy have been reported with significant post-operative pain affecting quality of life as well as capacity to perform daily activities. The objective of this article is to explore the role of conventionally used antibiotic metronidazole as a proctological analgesic.

Methods

A systematic review of the randomized, controlled trials reporting the use of oral metronidazole as post-operative proctological analgesic agent in patients undergoing haemorrhoidectomy published on Embase, Medline, PubMed, PubMed Central and Cochrane databases was performed using the principles of meta-analysis.

Results

A total of eight randomized, controlled trials on 447 patients were included in this study. In the random effects model analysis using the statistical software Review Manager, the use of oral metronidazole as a post-operative proctological analgesic agent was significantly associated with the reduced pain score on day 1 (Standardized mean difference (SMD), -0.56; 95% CI, -1.04, -0.07; z = 2.26; P = 0.02), day 3 (SMD, -0.82; 95% CI, -1.33, -0.31; z = 3.15; P = 0.002) and day 7 (SMD, -1.48; 95% CI, -2.51, -0.45; z = 2.82; P = 0.005). There was significant heterogeneity (Tau2 = 0.39, chi2 = 38.38, df = 7, [p = 0.00001]; I2 = 82 %) among included studies.

Conclusion

The use of oral metronidazole as a post-operative proctological analgesic agent following haemorrhoidectomy seems to have proven clinical advantages and may routinely be used.

Investigation of Power Specific Motor Primitives in an Upper Limb Rotational Motion

The purpose of this study was to investigate muscle synergies (MS) during upper limb cycling motion across power levels (20, 40, 60, 80, 100, and 120 watts). The MS hypothesis is important to the understanding of modular control for human movements. In this study, we explore its importance in execution of phasic movements at various power levels. Electromyographic (EMG) signals were recorded from 7 upper limb muscles during cycling for 30s on a hand-cycle ergometer. A Non-Negative Matrix factorization (NNMF) algorithm was used to extract MS. Cosine similarity was used to compare the MS and cross-correlation was used to compare activation coefficients. We found that the number and structure of synergies were consistent across power levels while admitting modulation in their activation coefficients. A total of three shared MS explaining ≥95% of the variance accounted for (VAF) represented push and pull mechanism during cyclic motion.

OP0078 HIGH MEDIAN NERVE LESION SECONDARY TO SEVERE GIANT CELL ARTERITIS (GCA)

Background:

Giant cell arteritis (GCA) is a systemic vasculitis affecting large to medium-sized vessels. Cranial nerve lesions are frequently documented secondary to GCA, however peripheral nerves are rarely involved.

Objectives:

We present an unusual case of a GCA-associated isolated high median nerve palsy.

Methods:

Case report.

Results:

A 76 year old white British female presented in Spain with three weeks of frontotemporal headaches, mandibular claudication, photopsia and constitutional symptoms, followed by acute-onset right hand paresis and dysaesthesia. Acute-phase reactants were elevated. COVID-19 PCR was negative. Shortly after admission she developed acute bilateral anterior ischaemic optic neuropathy and tongue necrosis with autoamputation. Temporal artery ultrasound and biopsy confirmed GCA. PET-CT showed no evidence of a diffuse large-vessel vasculitis. She was repatriated to the UK for ongoing inpatient care. Upper limb neurophysiology two months later demonstrated an isolated right high median nerve lesion, with reduced median motor responses and absent sensory responses with denervation in extensor carpi radialis. Imaging excluded a central lesion. The timing of her symptoms suggested the lesion was secondary to GCA. Treatment was with tocilizumab, methotrexate and tapering corticosteroids, alongside PEG feeding and careful multi-disciplinary rehabilitation.

Conclusion:

We suggest there are two important learning points from this complex case. Firstly, peripheral nerve lesions can occur in GCA, although they are rare. A literature search identified a modest number of case reports of brachial plexus or lower cervical nerve lesions1,2. Neurologic manifestations in GCA are attributed to vasculitis of the vasa nervorum, or extension of inflammation from arteries to contiguous nerves1,2. The restriction of clinical involvement to the median nerve alone would appear to favour the former mechanism. Functional recovery of neurological deficits is typically partial at best.

Secondly, this case highlights the difficulty faced by clinicians in recognising GCA and the importance of urgent treatment with glucocorticoids. The patient developed GCA during the ongoing COVID-19 pandemic when Spain was the second-worst affected European country (5% seroprevalence; 95% CI 4.7-5.4)3. The partial overlap in symptoms between GCA and COVID-19 (e.g. headache, pyrexia, malaise, elevated acute-phase reactants) can cause diagnostic confusion and treatment delay4. GCA should be considered in the differential diagnosis of older patients with suspected COVID-19, or the non-specifically unwell elderly patient.

References:

[1]Blaise S, et al. Horton’s disease revealed by brachial C5 plexopathy [French]. Rev Med Interne. 2005;26(7):578-82.

[2]Merianos P, et al. Giant cell arteritis of the median nerve simulating carpal tunnel syndrome. Hand. 1983;15(3): 249-251.

[3]Pollán M, et al. Prevalence of SARS-CoV-2 in Spain (ENE-COVID): a nationwide, population-based seroepidemiological study. Lancet. 2020; 396(10250): 535-544.

[4]Monti S, Delvino P, et al. Impact of delayed diagnoses at the time of COVID-19: increased rate of preventable bilateral blindness in giant cell arteritis. Ann Rheum Dis. 2020;79:1658-1659.

Table 1.Area/movementResultAbductor pollicis brevisGrade 2 weaknessOpponens pollicisGrade 4 weaknessPronator teres/quadratusGrade 4 weaknessFlexor pollicis longusGrade 1-2 weaknessFlexor digitorum profundus (digit 2 and 3)Grade 1-2 weaknessFinger abductionPreservedFinger extensionPreservedOther commentsDysaesthesia in distribution of median nerve

Disclosure of Interests:

Kundan Iqbal: None declared, James Miller Speakers bureau: Dr Miller has participated in pharmaceutical-sponsored symposiums previously but not in last five years., Consultant of: Dr Miller has participated in pharmaceutical-sponsored consultancy previously but not in last five years., Ming Lai: None declared, Mia Charnley: None declared, Muhammad Meraj: None declared, Ben Thompson Speakers bureau: Dr Thompson has participated in educational talks for Roche, Novartis, Lilly and UCB., Consultant of: Dr Thompson has participated in advisory boards for Roche, Novartis, Lilly, Gilead, Abbvie and UCB.

649 COVID BOAST In Practice: Our Experience Implementing BOA Recommendations During the UK Coronavirus Pandemic Peak

Background

In anticipation of the UK coronavirus pandemic peak, BOA published new pandemic-specific guidance (“COVID BOAST”) in April 2020. We describe our experience implementing this restructured T&O service in a busy DGH setting during the pandemic peak.

Method

A rapid retrospective audit was conducted of all patients presenting to our T&O service in April 2020, with particular emphasis compliance with COVID BOAST.

Results

Our service conducted 511 outpatient reviews, and 95 operative procedures. 94% of outpatients were treated non-operatively. We provided telephone appointments to 12.8% of follow-up patients, and 39% of new patients. 82% of patients were treated with removable casts/splints/boots. 23% of patients were discharged direct from VFC or after one face-to-face fracture clinic review. Residual deformity was consciously accepted in 13% of patients. Theatre throughput fell significantly due to pandemic precautions however, femoral neck fracture volumes remained constant.

Conclusions

We demonstrate broad compliance with COVID BOAST guidance. The majority of patients were treated non-operatively, including conscious acceptance of residual deformity. Our pre-existing VFC allowed us to provide a significant number of telephone consultations, although despite the practice shift towards removable splintage, face-to-face consultations were required for clinical and/or radiological assessment. The impact of increased conservative management on patients’ long-term outcomes needs further evaluation.

Distal biceps short head tears: repair, reconstruction, and systematic review

BACKGROUND

Isolated short head tears of the distal biceps are uncommon and often underappreciated. The aim of this study was to describe the presenting features and management of acute and chronic short head ruptures treated at our unit and in the published literature.

METHODS

Six short head ruptures in 5 patients are described. The clinical and radiographic findings, operative techniques, and postoperative outcomes are reported for all patients. A systematic review of the existing literature was also performed.

RESULTS

All patients presented with pain and weakness following an acute traumatic event. One patient presented with bilateral tears 3 years apart. Four of the ruptures underwent acute repair. Two ruptures presented chronically with retracted short head tears and were treated with allograft reconstruction of the short head. Preoperative magnetic resonance imaging findings demonstrated retraction of the short head affecting only 1 muscle belly, and in all patients the hook test was intact. All patients reported excellent functional outcome scores with no postoperative complications. The systematic review identified 9 previously reported cases, of which 8 were treated surgically with a successful outcome. Detailed analysis of these cases demonstrated clinical findings consistent with our cases, and these are outlined in depth in the article.

DISCUSSION/CONCLUSIONS

Isolated short head ruptures are a rare and distinct form of distal biceps tear that present with consistent clinical findings that can aid in diagnosis. They present acutely, have a poor natural history akin to complete tears, and have good outcomes with acute and delayed reconstruction.

Complications After Distal Biceps Tendon Repair: A Systematic Review

BACKGROUND

Distal biceps tendon injuries typically occur in the dominant arm of men in their fourth decade of life. Surgical repair restores flexion and supination strength, resulting in good functional outcome. The complication profile of each surgical approach and fixation technique has not been widely studied in the literature.

PURPOSE

To report the rate of complications after repair of complete distal biceps ruptures, to classify them according to surgical approach and fixation technique, and to analyze risk factors and outcomes of the individual complications.

STUDY DESIGN

Systematic review.

METHODS

Studies published in English on primary repair of the distal biceps between January 1998 and January 2019 were identified. Data on complications were extracted and classified as major and minor for analysis. A quantitative synthesis of data was done to compare the complication rates between (1) limited anterior incision, extensile anterior incision, and double incision and (2) 4 fixation methods.

RESULTS

Seventy-two articles including 3091 primary distal biceps repairs were identified. The overall complication rate was 25% (n = 774). The major complication rate was 4.6% (n = 144) and included a 1.6% (n = 51) rate of posterior interosseous nerve injury; 0.3% (n = 10), median nerve injury; 1.4% (n = 43), rerupture; and a 0.1% (n = 4), synostosis. Brachial artery injury, ulnar nerve injury, compartment syndrome, proximal radius fracture, and chronic regional pain syndrome occurred at a rate of <0.1% each. The majority of nerve injuries resolved with an expectant approach. The minor complication rate was 20.4% (n = 630). The most common complication was lateral cutaneous nerve injury (9.2%, n = 283). An extensile single incision was associated with a higher rate of superficial radial nerve injury when compared to limited single incision(6% vs 2.1%, P = .002). Limited anterior single incision technique had a higher rate of lateral antebrachial cutaneous nerve injury compared to extensile single incision. (9.7% vs 5.2%, P = .03). Synostosis occurred only with double incision. Fixation technique had no significant effect on rerupture rate and posterior interosseous nerve injury rate.

CONCLUSION

This is the largest analysis of complications after distal biceps repair, indicating a major complication rate of 4.6%. This study provides valuable data with regard to the choice of technique, surgical approach, and rate of complications, which is essential for surgical planning and patient consent.

REGISTRATION

CRD42017074066 (PROSPERO).

Biomedical soft robots: current status and perspective

This paper reviews the current status of soft robots in biomedical field. Soft robots are made of materials that have comparable modulus of elasticity to that of biological systems. Several advantages of soft robots over rigid robots are safe human interaction, ease of adaptation with wearable electronics and simpler gripping. We review design factors of soft robots including modeling, controls, actuation, fabrication and application, as well as their limitations and future work. For modeling, we survey kinematic, multibody and numerical finite element methods. Finite element methods are better suited for the analysis of soft robots, since they can accurately model nonlinearities in geometry and materials. However, their real-time integration with controls is challenging. We categorize the controls of soft robots as model-based and model-free. Model-free controllers do not rely on an explicit analytical or numerical model of the soft robot to perform actuation. Actuation is the ability to exert a force using actuators such as shape memory alloys, fluid gels, elastomers and piezoelectrics. Nonlinear geometry and materials of soft robots restrict using conventional rigid body controls. The fabrication techniques used for soft robots differ significantly from that of rigid robots. We survey a wide range of techniques used for fabrication of soft robots from simple molding to more advanced additive manufacturing methods such as 3D printing. We discuss the applications and limitations of biomedical soft robots covering aspects such as functionality, ease of use and cost. The paper concludes with the future discoveries in the emerging field of soft robots.

Evaluation of dose conformity and coverage of target volume for intensity-modulated radiotherapy of pelvic cancer treatment

BACKGROUND

Better conformity may help in delivering minimum dose to organs at risk (OARs) and maximum dose to planning target volume (PTV). As per the requirements of modern radiotherapy, 95% isodose should cover the PTV, so conformity indices (CIs) are used for evaluating quality of conformation of treatment plans.

AIM

This study aimed to investigate degree of conformity for pelvic patients using intensity-modulated radiotherapy (IMRT) technique. Three formulas of CIs described in literature were analyzed in this study.

SETTINGS AND DESIGN

This study was performed to evaluate degree of conformity of 18 patients treated with radiotherapy treatment plan using cumulative dose volume histogram. Effectiveness of different CIs was explored for IMRT plans using 15 MV photon beam. Doses delivered to OAR were also studied.

STATISTICAL ANALYSIS USED

CI suggested by the International Commission on Radiation Units and Measurements, radiation CI and CI prescription isodose to target volume (PITV) had mean ± standard deviation values of 1.02 ± 0.018, 0.98 ± 0.017, and 1.63 ± 0.333, respectively.

RESULTS AND CONCLUSION

Dose distribution for all patients was highly conformal and clinically acceptable. Values of CI PITV exceeded acceptable value for 27% patients with minor deviation. No statistically significant differences were observed for three CIs reported. Target volume lies between 95% and 107% of prescribed dose which shows ideal target coverage. This simple parameter is advantageous since it is easy to interpret and helped determine quality of treatment plan. This study clearly demonstrated that favorable dose distribution in PTV and OARs is achieved using IMRT technique, and hence, the risk of damage to normal tissues is reduced.

Synchronic inverse seasonal rhythmus of energy density of food intake and sleep quality: a contribution to chrono-nutrition from a Polish adult population

BACKGROUND/OBJECTIVES

There is evidence which suggests that sleep behavior and dietary intake are interlinked. Thus, we investigated whether a seasonal rhythm in food-energy density exists, and how this relates to quality of sleep.

SUBJECTS/METHODS

Two hundred and thirty adult volunteers were investigated across the four seasons. Anthropometrical measurements were obtained and The Pittsburgh Sleep Quality Index was used for an assessment of sleep quality and disturbances. The dietary intake was evaluated using a 24 h dietary recall. Generalized estimating equations were used to estimate seasonal changes in energy density and sleep quality, as well as the association of energy density with sleep quality. All analyses were adjusted for age, sex, education, occupation and shift-work.

RESULTS

Mean food energy density was significantly higher in winter as compared with other seasons (P<0.05), although no seasonal variations were observed in macronutrient intake (fat and protein). Overall, the sleep quality was low (score value >5) in all seasons, with the lowest quality occurring in winter and the highest in spring (P<0.05). The components of sleep quality score showed that winter had statistically (P<0.05) poorer subjective sleep quality, sleep latency and sleep disturbances, but lower daytime dysfunction compared with spring and summer. After adjusting for seasonal effects (correlated outcome data) and shift-work, energy density was found to be inversely associated (P<0.0001) with sleep quality.

CONCLUSIONS

An inverse association between seasonal fluctuation of food energy density and sleep quality was found with winter time, associated with the intake of higher energy dense food products and the lowest sleep quality.

Factors associated with poor outcomes in patients with lupus nephritis

The objective of this study was to identify the factors associated with important clinical outcomes in a case-control study of 213 patients with lupus nephritis. Included were 47% Hispanics, 44% African Americans and 9% Caucasians with a mean age of 28 years. Fifty-four (25%) patients reached the primary composite outcome of doubling serum creatinine, end-stage renal disease or death during a mean follow-up of 37 months. Thirty-four percent African Americans, 20% Hispanics and 10% Caucasians reached the primary composite outcome ( P < 0.05). Patients reaching the composite outcome had predominantly proliferative lupus nephritis (WHO classes: 30% III, 32% IV, 18% V and 5% II, P < 0.025) with higher activity index score (7 ± 6 versus 5 ± 5, P<0.05), chronicity index (CI) score (4 ± 3 versus 2 ± 2 unit, P<0.025), higher baseline mean arterial pressure (MAP) (111 ± 21 versus 102 ± 14 mmHg, P<0.025) and serum creatinine (1.9 ± 1.3 versus 1.3 ± 1.0 mg/dL, P<0.025), but lower baseline hematocrit (29 ± 6 versus 31 + 5%, P<0.025) and complement C3 (54 ± 26 versus 65 + 33 mg/dL, P<0.025) compared to controls. More patients reaching the composite outcome had nephrotic range proteinuria compared to controls (74% versus 56%, P<0.025). By multivariate analysis, CI (hazard ratio [95% CI] 1.18 [1.07-1.30] per point), MAP (HR 1.02 [1.00-1.03] per mmHg), and baseline serum creatinine (HR 1.26 [1.04-1.54] per mg/dL) were independently associated with the composite outcome. We concluded that hypertension and elevated serum creatinine at the time of the kidney biopsy as well as a high CI are associated with an increased the risk for chronic renal failure or death in patients with lupus nephritis.

Performance of select color-difference formulas in the blue region

The main objective of this work was to test the performance of major formulas for assessment of small suprathreshold color differences in the blue region. The models examined include CIELAB color space based equations, including CIELAB, CIE94, CIEDE2000, CMC (l:c), BFD (l:c), and formulas based on more uniform color spaces, such as DIN99d, CAM02-SCD, CAM02-UCS, OSA-GP, and OSA-Eu in comparison against data obtained via visual assessments. For this purpose, a dataset around the CIE high-chroma blue color center, hereafter called NCSU-B2, was developed. The NCSU-B2 dataset comprised 65 textile substrates and a standard, with a mean ΔE(ab)* color difference of 2.72, ranging from 0.54-5.72. Samples were visually assessed by 26 subjects against the reference gray scale in three separate trials with at least 24 h between assessments. A total of 5070 assessments were obtained. The standardized residual sum of squares (STRESS) index was used to examine the performance of various formulas for this dataset, as well as a previously developed NCSU-B1 low-chroma blue dataset [Color Res. Appl. 36, 27, 2011], and blue centers from other established visual datasets. Results show that formulas based on more recent uniform color spaces provide better agreement with perceptual data compared with models based on CIELAB space.

Quality assurance evaluation of spot scanning beam proton therapy with an anthropomorphic prostate phantom

OBJECTIVE

The purpose of this study was to evaluate spot scanning proton therapy with an anthropomorphic prostate phantom at the Proton Therapy Center of The University of Texas MD Anderson Cancer Center at Houston, TX (PTCH).

METHODS

An anthropomorphic prostate phantom from the Radiological Physics Center (RPC), The University of Texas MD Anderson Cancer Center, Houston, TX, was used, which contained thermoluminescent dosemeters and GAFCHROMIC(®) EBT2 film (ISP Technologies, Wayne, NJ). The phantom was irradiated by the Hitachi synchrotron (Hitachi America, Ltd, Tarrytown, NY), and the results were compared between the treatment planning system (TPS) and RPC measurements.

RESULTS

RPC results show that the right/left, inferior/superior and posterior/anterior aspects of the coronal/sagittal and EBT2 film measurements were within ±7%/±4 mm of the TPS. The RPC thermoluminescent dosemeter measurements of the prostate and femoral heads were within 3% of the TPS.

CONCLUSION

The RPC prostate phantom is a useful mechanism to evaluate spot scanning beam proton therapy within certain confidence levels.

ADVANCES IN KNOWLEDGE

The RPC anthropomorphic prostate phantom could be used to establish quality assurance of spot scanning proton beam for patients with prostate cancer.

Characterization of riboflavin-modified dentin collagen matrix

Crosslinking is considered a possible approach to increasing the mechanical and structural stability and biodegradation resistance of the dentin collagen matrix. The aim of this study was to investigate the mechanical and chemical variations and collagen degradation resistance associated with crosslinking of the dentin collagen matrix with UVA-activated riboflavin. Dentin collagen matrix specimens were treated with 0.1 and 1% riboflavin for 2 min and photo-activated with 7 mW/cm(2) UVA (368 nm) for 2 min. The structural change of the dentin collagen network with collagenase exposure was investigated by AFM and SEM at different time-points. The variations in surface/bulk mechanical properties and biodegradation resistance were characterized by nano-indentation, conventional mechanical testing, and hydroxyproline liberation at different time-points. Chemical changes associated with riboflavin/collagen-matrix interaction were analyzed by micro-Raman spectroscopy. UVA-activated riboflavin increased the mechanical properties, mechanical stability, and biodegradation resistance of the dentin collagen matrix. Higher collagen-network structural resistance against collagenolytic challenges was found with crosslinking. micro-Raman spectroscopy showed a strong dependency, in both intensity and wave-number, of certain Raman bands (1242-1667 cm(-1)) with crosslinking indicating the collagen/riboflavin interactions. UVA-activated riboflavin (1%) more efficiently crosslinked the dentin collagen matrix within a relatively clinically acceptable time-frame compared with 0.1% riboflavin.