A Generative and Causal Pharmacokinetic Model for Factor VIII in Hemophilia A: A Machine Learning Framework for Continuous Model Refinement

In rare diseases, such as hemophilia A, the development of accurate population pharmacokinetic (PK) models is often hindered by the limited availability of data. Most PK models are specific to a single recombinant factor VIII (rFVIII) concentrate or measurement assay, and are generally unsuited for answering counterfactual ("what-if") queries. Ideally, data from multiple hemophilia treatment centers are combined but this is generally difficult as patient data are kept private. In this work, we utilize causal inference techniques to produce a hybrid machine learning (ML) PK model that corrects for differences between rFVIII concentrates and measurement assays. Next, we augment this model with a generative model that can simulate realistic virtual patients as well as impute missing data. This model can be shared instead of actual patient data, resolving privacy issues. The hybrid ML-PK model was trained on chromogenic assay data of lonoctocog alfa and predictive performance was then evaluated on an external data set of patients who received octocog alfa with FVIII levels measured using the one-stage assay. The model presented higher accuracy compared with three previous PK models developed on data similar to the external data set (root mean squared error = 14.6 IU/dL vs. mean of 17.7 IU/dL). Finally, we show that the generative model can be used to accurately impute missing data (< 18% error). In conclusion, the proposed approach introduces interesting new possibilities for model development. In the context of rare disease, the introduction of generative models facilitates sharing of synthetic data, enabling the iterative improvement of population PK models.

On inductive biases for the robust and interpretable prediction of drug concentrations using deep compartment models

Conventional pharmacokinetic (PK) models contain several useful inductive biases guiding model convergence to more realistic predictions of drug concentrations. Implementing similar biases in standard neural networks can be challenging, but might be fundamental for model robustness and predictive performance. In this study, we build on the deep compartment model (DCM) architecture by introducing constraints that guide the model to explore more physiologically realistic solutions. Using a simulation study, we show that constraints improve robustness in sparse data settings. Additionally, predicted concentration-time curves took on more realistic shapes compared to unconstrained models. Next, we propose the use of multi-branch networks, where each covariate can be connected to specific PK parameters, to reduce the propensity of models to learn spurious effects. Another benefit of this architecture is that covariate effects are isolated, enabling model interpretability through the visualization of learned functions. We show that all models were sensitive to learning false effects when trained in the presence of unimportant covariates, indicating the importance of selecting an appropriate set of covariates to link to the PK parameters. Finally, we compared the predictive performance of the constrained models to previous relevant population PK models on a real-world data set of 69 haemophilia A patients. Here, constrained models obtained higher accuracy compared to the standard DCM, with the multi-branch network outperforming previous PK models. We conclude that physiological-based constraints can improve model robustness. We describe an interpretable architecture which aids model trust, which will be key for the adoption of machine learning-based models in clinical practice.

ChatGPT in pharmacometrics? Potential opportunities and limitations

The potential of using ChatGPT in pharmacometrics was explored in this study, with a focus on developing a population pharmacokinetic (PK) model for standard half-life factor VIII. Our results demonstrated that ChatGPT can be utilized to accurately obtain typical PK parameters from literature, generate a population PK model in R and develop an interactive Shiny application to visualize the results. ChatGPT's language generation capabilities enabled the development of R codes with minimal programming knowledge and helped to identify as well fix errors in the code. While ChatGPT presents several advantages, such as its ability to streamline the development process, its use in pharmacometrics also has limitations and challenges, including the accuracy and reliability of AI-generated data, the lack of transparency and reproducibility regarding codes generated by ChatGPT. Overall, our study demonstrates the potential of using ChatGPT in pharmacometrics, but researchers must carefully evaluate its use for their specific needs.

Economic evaluation of flap fixation techniques after mastectomy: Results of a double-blind randomized controlled trial (SAM-trial)

BACKGROUND

An economic evaluation was performed alongside an RCT investigating flap fixation in reducing seroma formation after mastectomy. The evaluation focused on the first year following mastectomy and assessed cost-effectiveness from a health care and societal perspective.

METHODS

The economic evaluation was conducted between 2014 and 2018 in four Dutch breast clinics. Patients with an indication for mastectomy or modified radical mastectomy were randomly assigned to: conventional closure (CON), flap fixation with sutures (FFS) or flap fixation with tissue glue (FFG). Health care costs, patient and family costs and costs due to productivity losses were assessed. Outcomes were expressed in incremental cost-effectiveness ratios (ICERs): the incremental cost per quality-adjusted life year (QALY). Bootstrapping techniques, sensitivity and secondary analyses were employed to address uncertainty.

RESULTS

The FFS-group yielded most QALYs (0.810; 95%-CI 0.755-0.856), but also incurred the highest mean costs at twelve months (€10.416; 95%-CI 8.231-12.930). CON was the next best alternative with 0.794 QALYs (95%-CI 0.733-0.841) and mean annual costs of €10.051 (95%-CI 8.255-12.044). FFG incurred fewer QALYs and higher costs, when compared to the CON group. The ICER of FFS compared to CON was €22.813/QALY. Applying a willingness to pay threshold in the Netherlands of €20.000/QALY, the probability that FFS was cost-effective was 42%, compared to 37% and 21% for CON and FFG, respectively.

CONCLUSION

The cost-effectiveness of FFS following mastectomy, versus CON and FFG, is uncertain from a societal perspective. Yet, from a health care and hospital perspective FFS is likely to be the most cost-effective intervention.

The road to implementation of pharmacokinetic-guided dosing of factor replacement therapy in hemophilia and allied bleeding disorders. Identifying knowledge gaps by mapping barriers and facilitators

Clinical guidelines and expert groups recommend the use of pharmacokinetic (PK)-guided dosing of factor replacement therapy for the treatment of bleeding disorders, especially for patients with hemophilia. Although PK-guided dosing is increasingly applied, it is generally not considered standard clinical practice. The aim of this scoping review is to map barriers and facilitators for the implementation of PK-guided dosing in clinical practice and to identify knowledge gaps. A literature search was performed and 110 articles were included that describe PK-guided dosing in patients with bleeding disorders, mostly hemophilia A. We defined two overarching themes, efficacy and feasibility, and discuss five topics within each theme. For each topic, barriers, facilitators and knowledge gaps were described. Although consensus was found with regard to some topics, contradicting reports were found for others, especially with respect to the efficacy of PK-guided dosing. These contradictions highlight the need for future research to elucidate current ambiguities.

HIDEA syndrome: A new case report highlighting similarities with ROHHAD syndrome

Context: ROHHAD syndrome presents a significant resemblance to HIDEA syndrome. The latter is caused by biallelic loss-of-function variants in the P4HTM gene and encompasses hypotonia, intellectual disabilities, eye abnormalities, hypoventilation, and dysautonomia. We report the first patient identified with HIDEA syndrome from our ROHHAD cohort. Clinical case: Our patient was a 21-month-old girl who had a history of severe respiratory infections requiring intensive care, hypotonia, abnormal eye movements, and rapid weight gain. Polysomnography identified severe central hypoventilation. During her follow-up, a significant psychomotor delay and the absence of language were gradually observed. The prolactin levels were initially increased. Hypothermia was reported at 4 years. Exome sequencing identified a new homozygous truncating P4HTM variant. Discussion: Our patient met the diagnosis criteria for ROHHAD, which included rapid weight gain, central hypoventilation appearing after 1.5 years of age, hyperprolactinemia suggesting hypothalamic dysfunction, and autonomic dysfunction manifesting as strabismus and hypothermia. However, she also presented with severe neurodevelopmental delay, which is not a classic feature of ROHHAD syndrome. HIDEA syndrome presents similarities with ROHHAD, including hypoventilation, obesity, and dysautonomia. To date, only 14% of endocrinological disturbances have been reported in HIDEA patients. Better delineation of both syndromes is required to investigate the eventual involvement of P4HTM, a regulator of calcium dynamics and gliotransmission, in ROHHAD patients. Conclusion: In the case of clinical evidence of ROHHAD in a child with abnormal neurological development or eye abnormalities, we suggest that the P4HTM gene be systematically interrogated in addition to the analysis of the PHOX2B gene. A better delineation of the natural history of HIDEA is required to allow further comparisons between features of HIDEA and ROHHAD. The clinical similarities could potentially orient some molecular hypotheses in the field of ROHHAD research.

Adoption of Machine Learning in Pharmacometrics: An Overview of Recent Implementations and Their Considerations

Pharmacometrics is a multidisciplinary field utilizing mathematical models of physiology, pharmacology, and disease to describe and quantify the interactions between medication and patient. As these models become more and more advanced, the need for advanced data analysis tools grows. Recently, there has been much interest in the adoption of machine learning (ML) algorithms. These algorithms offer strong function approximation capabilities and might reduce the time spent on model development. However, ML tools are not yet an integral part of the pharmacometrics workflow. The goal of this work is to discuss how ML algorithms have been applied in four stages of the pharmacometrics pipeline: data preparation, hypothesis generation, predictive modelling, and model validation. We will also discuss considerations before the use of ML algorithms with respect to each topic. We conclude by summarizing applications that hold potential for adoption by pharmacometricians.

Application of SHAP values for inferring the optimal functional form of covariates in pharmacokinetic modeling

In population pharmacokinetic (PK) models, interindividual variability is explained by implementation of covariates in the model. The widely used forward stepwise selection method is sensitive to bias, which may lead to an incorrect inclusion of covariates. Alternatives, such as the full fixed effects model, reduce this bias but are dependent on the chosen implementation of each covariate. As the correct functional forms are unknown, this may still lead to an inaccurate selection of covariates. Machine learning (ML) techniques can potentially be used to learn the optimal functional forms for implementing covariates directly from data. A recent study suggested that using ML resulted in an improved selection of influential covariates. However, how do we select the appropriate functional form for including these covariates? In this work, we use SHapley Additive exPlanations (SHAP) to infer the relationship between covariates and PK parameters from ML models. As a case-study, we use data from 119 patients with hemophilia A receiving clotting factor VIII concentrate peri-operatively. We fit both a random forest and a XGBoost model to predict empirical Bayes estimated clearance and central volume from a base nonlinear mixed effects model. Next, we show that SHAP reveals covariate relationships which match previous findings. In addition, we can reveal subtle effects arising from combinations of covariates difficult to obtain using other methods of covariate analysis. We conclude that the proposed method can be used to extend ML-based covariate selection, and holds potential as a complete full model alternative to classical covariate analyses.

Deep compartment models: A deep learning approach for the reliable prediction of time-series data in pharmacokinetic modeling

Nonlinear mixed effect (NLME) models are the gold standard for the analysis of patient response following drug exposure. However, these types of models are complex and time-consuming to develop. There is great interest in the adoption of machine-learning methods, but most implementations cannot be reliably extrapolated to treatment strategies outside of the training data. In order to solve this problem, we propose the deep compartment model (DCM), a combination of neural networks and ordinary differential equations. Using simulated datasets of different sizes, we show that our model remains accurate when training on small data sets. Furthermore, using a real-world data set of patients with hemophilia A receiving factor VIII concentrate while undergoing surgery, we show that our model more accurately predicts a priori drug concentrations compared to a previous NLME model. In addition, we show that our model correctly describes the changing drug concentration over time. By adopting pharmacokinetic principles, the DCM allows for simulation of different treatment strategies and enables therapeutic drug monitoring.

Clinical presentation, disease course, and outcome of COVID-19 in hospitalized patients with and without pre-existing cardiac disease: a cohort study across 18 countries

AIMS

Patients with cardiac disease are considered high risk for poor outcomes following hospitalization with COVID-19. The primary aim of this study was to evaluate heterogeneity in associations between various heart disease subtypes and in-hospital mortality.

METHODS AND RESULTS

We used data from the CAPACITY-COVID registry and LEOSS study. Multivariable Poisson regression models were fitted to assess the association between different types of pre-existing heart disease and in-hospital mortality. A total of 16 511 patients with COVID-19 were included (21.1% aged 66-75 years; 40.2% female) and 31.5% had a history of heart disease. Patients with heart disease were older, predominantly male, and often had other comorbid conditions when compared with those without. Mortality was higher in patients with cardiac disease (29.7%; n = 1545 vs. 15.9%; n = 1797). However, following multivariable adjustment, this difference was not significant [adjusted risk ratio (aRR) 1.08, 95% confidence interval (CI) 1.02-1.15; P = 0.12 (corrected for multiple testing)]. Associations with in-hospital mortality by heart disease subtypes differed considerably, with the strongest association for heart failure (aRR 1.19, 95% CI 1.10-1.30; P < 0.018) particularly for severe (New York Heart Association class III/IV) heart failure (aRR 1.41, 95% CI 1.20-1.64; P < 0.018). None of the other heart disease subtypes, including ischaemic heart disease, remained significant after multivariable adjustment. Serious cardiac complications were diagnosed in <1% of patients.

CONCLUSION

Considerable heterogeneity exists in the strength of association between heart disease subtypes and in-hospital mortality. Of all patients with heart disease, those with heart failure are at greatest risk of death when hospitalized with COVID-19. Serious cardiac complications are rare during hospitalization.

The actual use of directional steering and shorter pulse width in selected patients undergoing deep brain stimulation

INTRODUCTION

Directional deep brain stimulation (DBS) and pulse with <60μs increase side-effects threshold, enlarging the therapeutic window. However, new systems allowing these advanced features are more expensive and often available only for a limited number of patients in some centers. It is unknown how many and which DBS patients actually need the advanced features because of an insufficient improvement with standard parameters.

METHODS

We included in the analysis all patients with Parkinson's disease, dystonia and tremor who were selected to receive implantation of advanced DBS systems based on specific preoperative or intraoperative clinical features.

RESULTS

After a median follow-up of 15 months, 54.9% of the 51 patients implanted with directional leads were using the advanced features in one or both leads (n = 42 leads, 42%), meaning these leads were programmed either with directional stimulation (n = 9, 9%), a shorter pw (n = 20, 20%) or both (n = 13, 13%). This included 92% of patients implanted in the Vim, 44% of those implanted in the STN, and 40% of those implanted in the GPi.

CONCLUSIONS

DBS systems with advanced features may be particularly indicated for selected patients based on some clinical characteristics and the chosen target. This data may help clinicians allocate resources in a more informed way.

Negative pressure wound therapy does not decrease postoperative wound complications in patients undergoing mastectomy and flap fixation

Patients and breast cancer surgeons are frequently confronted with wound complications after mastectomy. Negative pressure wound therapy (NPWT) is a promising technique for preventing wound complications after skin closure in elective surgery. However, a clinical study evaluating postoperative complications following the use of NPWT, focusing solely on closed incisions in patients undergoing mastectomy, has yet to be performed. Between June 2019 and February 2020, 50 consecutive patients underwent mastectomy with NPWT during the first seven postoperative days. This group was compared to a cohort of patients taking part in a randomized controlled trial between June 2014 and July 2018. Primary outcome was the rate of postoperative wound complications, i.e. surgical site infections, wound necrosis or wound dehiscence during the first three postoperative months. Secondary outcomes were the number of patients requiring unplanned visits to the hospital and developing clinically significant seroma (CSS). In total, 161 patients were analyzed, of whom 111 patients in the control group (CON) and 50 patients in the NPWT group (NPWT). Twenty-eight percent of the patients in the NPWT group developed postoperative wound complications, compared to 18.9% in the control group (OR = 1.67 (95% CI 0.77–3.63), p = 0.199). The number of patients requiring unplanned visits or developing CSS was not statistically significant between the groups. This study suggests that Avelle negative pressure wound therapy in mastectomy wounds does not lead to fewer postoperative wound complications. Additionally, it does not lead to fewer patients requiring unplanned visits or fewer patients developing clinically significant seromas.

Trial registration: ClinicalTrials.gov number, NCT03942575. Date of registration: 08/05/2019.

[Treatment of tracheo(broncho)malacia in children]

Tracheomalacia (TM) is characterized by tracheal collapse due to an intrinsic anomaly resulting in a lack of rigidity of the cartilaginous rings and/or the posterior membrane during expiration, coughing or crying. It may also be secondary to external compression or acquired during endobronchial diseases. TM is commonly associated with other syndromes or airway abnormalities. Tracheomalacia can be localized or diffused and if the main bronchi are involved, the term of tracheobronchomalacia (TBM) is used. The most common symptoms include expiratory stridor, barking cough and recurrent respiratory tract infections. If tracheal weakness is severe, Acute Life Threating Events (ALTE) or Brief Resolved Unexplained Event (BRUE) can occur. While mild forms usually do not require any treatment, severe TBM may require medical and/or surgical management. Amongst several possible treatments, including tracheostomy, noninvasive ventilation and airway stenting, the pexy surgical approach (posterior, anterior tracheopexy or aortopexy) is currently the favoured option.

Reducing Seroma Formation and Its Sequelae After Mastectomy by Closure of the Dead Space: A Multi-center, Double-Blind Randomized Controlled Trial (SAM-Trial)

BACKGROUND

Seroma is a common complication after mastectomy, with an incidence of 3% to 85%. Seroma is associated with pain, delayed wound healing, and additional outpatient clinic visits, leading potentially to repeated seroma aspiration or even surgical interventions. This study aimed to assess the effect of flap fixation using sutures or tissue glue in preventing seroma formation and its sequelae.

METHODS

Between June 2014 and July 2018, 339 patients with an indication for mastectomy or modified radical mastectomy were enrolled in this randomized controlled trial in the Netherlands. Patients were randomly allocated to one of the three following arms: conventional wound closure (CON, n = 115), flap fixation using sutures (FFS, n = 111) or flap fixation using tissue glue (FFG, n = 113). The primary outcome was the need for seroma aspiration. The secondary outcomes were additional outpatient department visits, surgical-site infection, shoulder function and mobility, cosmesis, skin-dimpling, and postoperative pain scores.

RESULTS

Flap fixation after mastectomy leads to fewer seroma aspirations than conventional wound closure (CON 17.5% vs FFS 7.3% vs FFG 10.8%; p = 0.057), with a significant difference between flap fixation with sutures and conventional wound closure (odds ratio [OR], 0.37; 95% confidence interval [CI], 0.16-0.89; p = 0.025). Flap fixation has no significant negative effect on surgical-site infections, shoulder function and mobility, cosmesis, skin-dimpling, or postoperative pain.

CONCLUSION

Flap fixation using sutures leads to a significant reduction in aspirations of post-mastectomy seromas. The authors strongly advise surgeons to use sutures for flap fixation in patients undergoing mastectomy. (ClinicalTrials.gov no. NCT03305757).

PREREGISTRATION

The trial was registered after enrollment of the first participant. However, no specific explanation exists for this except that through the years more importance has been given to central trial registration. Our research team can ensure that after enrollment of the first participant, no changes were made to the trial, analysis plan, and/or study design.

Field distribution patterns of pests are asymmetrically affected by the presence of other herbivores

Because plant phenotypes can change in response to attacks by herbivores in highly variable ways, the distribution of herbivores depends on the occurrence of other herbivore species on the same plant. We carried out a field study to evaluate the co-occurrence of three coconut pests, the mites Aceria guerreronis (Acari: Eriophyidae), Steneotarsonemus concavuscutum (Acari: Tarsonemidae) and the moth Atheloca bondari (Lepidoptera: Pyralidae). The eriophyid mite Ac. guerreronis is the most important coconut pest around the world, whereas S. concavuscutum and At. bondari are economically important only in some areas along the Brazilian coast. A previous study suggested that the necrosis caused by Ac. guerreronis facilitates the infestation of At. bondari larvae. Because all three species infest the area under the perianths on coconuts and S. concavuscutum also causes necrosis that could facilitate At. bondari, we evaluated the co-occurrence of all three species. We found that the occurrence of At. bondari was positively associated with Ac. guerreronis, but negatively associated with S. concavuscutum. In addition, the two mite species showed negative co-occurrence. Atheloca bondari was found on nuts of all ages, but more on nuts that had fallen than on those on the trees, suggesting that nuts infested by At. bondari tend to fall more frequently. We discuss the status of At. bondari as a pest and discuss experiments to test the causes of these co-occurrence patterns.

Molecular analysis of sentinel lymph nodes in patients with breast cancer using one-step nucleic acid amplification (OSNA): Does not lead to overtreatment in the current era of de-escalating axillary management

PURPOSE

OSNA is a molecular technique for sentinel lymph node (SN) analysis in breast cancer. Compared to histology, OSNA may yield more (micro)metastases and thereby result in more axillary lymph node dissections or radiotherapy. We investigated whether axillary treatments increase when using OSNA, applying current guidelines for de-escalating axillary management.

METHODS

All patients treated for cT1-3N0 breast cancer in our hospital between December 2013 and February 2016 were included. In 148 prospectively included patients (January 2015-February 2016), SN's were examined with OSNA. In a retrospective cohort of 123 patients (December 2013-December 2014), SN's were examined with conventional histology. Outcomes were: number of macro and micrometastases, amount of patients receiving axillary dissection or irradiation, number of patients receiving adjuvant systemic therapy. Data were analyzed using Mann-Whitney and Pearson Chi-square test. P < 0.05 was considered statistically significant.

RESULTS

230 SN's from 123 patients were examined with conventional histology. 229 SN's from 148 patients were evaluated with OSNA. Amount of macrometastases was equal between groups (histology 17.9% versus OSNA 16.2%, p = 0.715). We found significantly more micrometastases when using OSNA (histology 11.4% versus OSNA 25.0%, p = 0.004). Total number of axillary lymph node dissections was comparable in both groups (histology 12.2%, OSNA 12.2%, p = 0.993), as well as number of axillary radiations (histology 8.9%, OSNA 11.5%, p = 0.493). Also, the number of patients receiving adjuvant systemic therapy was similar between conventional histology and OSNA (histology 53.7% versus OSNA 58.1%, p = 0.462).

CONCLUSION

OSNA analysis for SN in breast cancer is a highly sensitive technique, detecting more micrometastases than standard histology. When applying current guidelines, OSNA analysis does not lead to overtreatment with more axillary dissections or irradiation.

Diffuse alveolar hemorrhage in infants: Report of five cases

Diffuse alveolar hemorrhage (DAH) is a rare life-threatening condition in children. In this entity, the bleeding originates from the pulmonary microvasculature as a result of microvascular damage leading to blood leakage into the alveolar spaces. DAH can occur as an isolated medical entity or may be associated with other organ system injury or dysfunction. The classic triad of symptoms includes hemoptysis, anemia and diffuse pulmonary infiltrates. Hemoptysis is the usual presenting symptom but is not constant. A variety of diseases is associated with the development of DAH. Current classification organize the etiologies of diffuse alveolar hemorrhage based on the presence of severe immune disorders (such as systemic vasculitis and collagenosis) or non-immunodeficiency disorders (with an identified cardiac or non-cardiac origin, or idiopathic). The five cases of DAH presented in this study were all diagnosed in full-term infants, four males and one female, with normal neonatal adaptation and without family history of notable diseases. In all cases the diagnosis was made between the age of three and eighteen weeks-old. Moreover, all five patients, at the time of diagnosis, presented with hemoptysis, mild or severe dyspnea, anemia and abnormal chest X-rays. Consequently, the diagnosis of DAH was strongly suspected and, eventually, confirmed by bronchoscopy. Additional laboratory tests, as well as selected serologic and radiographic studies were performed in order to identify a specific etiology. The final diagnoses reflect a variety of causes: infections, idiopathic pulmonary hemosiderosis, accidental suffocation and Heiner syndrome. Treatment included oral corticosteroids except from one patient that received antimicrobial therapy.

Intraoperative Use of Cone-Beam Computed Tomography in the Treatment of Atlantoaxial Rotatory Subluxation

BACKGROUND

Atlantoaxial rotatory subluxation (AARS) is a rare pathological condition of the upper cervical spine. It can be caused by multiple mechanisms, including minor neck manipulations. Children are more prone owing to the weaker periarticular soft tissue and a steeper slant of the C1 facet plane against the vertical axis of the dens. If AARS does not resolve spontaneously, a normal position of the atlantoaxial joint must be achieved by reduction and stabilization.

CASE DESCRIPTION

A 15-year-old girl had presented with a painful torticollis that had already been present for 4 weeks after trimaxillary jaw correction for skeletal class II malocclusion. A computed tomography (CT) scan of the cervical spine showed AARS Field and Hawkins classification type I. We first attempted 1 week of conservative treatment with a soft collar and the prescription of a muscular relaxant. However, because the AARS persisted, we performed transoral closed reduction with the patient under general anesthesia, as previously described. During the procedure, we used intraoperative cone-beam CT to evaluate the degree of reduction. After obtaining complete reduction, immobilization with a halo-vest was applied.

CONCLUSIONS

Complete reduction of the AARS was achieved with closed intraoral reduction. We used intraoperative cone-beam CT to confirm complete reduction. We found cone-beam CT to be a very useful tool.

Infectious diseases and antimicrobial prescribing: Online spaced education for junior doctors

BACKGROUND

Inappropriate antimicrobial prescribing may harm patients and drive antimicrobial resistance. Junior doctors' knowledge of infectious diseases and antimicrobial prescribing is inadequate. Online spaced case-based learning can improve knowledge.

OBJECTIVE

To develop infectious diseases and antimicrobial prescribing course content for online spaced education and assess its effectiveness and feasibility for junior doctors.

METHODS

Infectious diseases and antimicrobial course content was developed for an online spaced education platform (Qstream Inc., Burlington, MA). Junior doctors (postgraduate years 1-3) at two tertiary teaching hospitals in Sydney participated in the study. Course content was provided with Qstream at one hospital and at the other hospital via two face-to-face (FTF) tutorials from August to October 2017. Knowledge and self-confidence were compared before and after training within and between both cohorts.

RESULTS

Participation in the course was higher in the Qstream cohort with 48/127 (37.8%) completing the course compared with 44/110 (40%) attending one or both FTF sessions, of whom 22/110 (20%) attended both. Improvement in mean knowledge score from 69.7% to 81.5% in the Qstream cohort was significantly greater than the FTF cohort's minimal improvement from 67.6% to 67.9% (95% CI 2.79-20.33; P=0.01). In the Qstream cohort mean confidence rating (0-10) improvement from 5.14 to 6.55 was greater than the FTF group improvement from 5.37 to 5.85 (95% CI 0.132-1.171; P=0.02). Qstream feedback was very positive.

CONCLUSIONS

Online spaced education in infectious diseases and antimicrobial prescribing was feasible, acceptable and effective for junior doctors. It has potential to reduce inappropriate antimicrobial prescribing and warrants further investigation.

Currently available and experimental dyes for intraoperative near-infrared fluorescence imaging of the ureters: a systematic review

Background

Iatrogenic ureteral injury (IUI) following abdominal surgery has a relatively low incidence, but is associated with high risks of morbidity and mortality. Conventional assessment of IUI includes visual inspection and palpation. This is especially challenging during laparoscopic procedures and has translated into an increased risk of IUI. The use of near-infrared fluorescent (NIRF) imaging is currently being considered as a novel method to identify the ureters intraoperatively. The aim of this review is to describe the currently available and experimental dyes for ureter visualization and to evaluate their feasibility of using them and their effectiveness.

Methods

This article adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standard for systematic reviews. A systematic literature search was performed in the PubMed database. All included articles were screened for eligibility by two authors. Three clinical trial databases were consulted to identify ongoing or completed unpublished trials. Risk of bias was assessed for all articles.

Results

The search yielded 20 articles on ureter visualization. Two clinically available dyes, indocyanine green (ICG) and methylene blue (MB), and eight experimental dyes were described and assessed for their feasibility to identify the ureter. Two ongoing clinical trials on CW800-BK and one trial on ZW800-1 for ureter visualization were identified.

Conclusions

Currently available dyes, ICG and MB, are safe, but suboptimal for ureter visualization based on the route of administration and optical properties, respectively. Currently, MB has potential to be routinely used for ureter visualization in most patients, but (cRGD-)ZW800-1 holds potential for this role in the future, owing to its exclusive renal clearance and the near absence of background. To assess the benefit of NIRF imaging for reducing the incidence of IUI, larger patient cohorts need to be examined.

Electronic supplementary material

The online version of this article (10.1007/s10151-019-01973-4) contains supplementary material, which is available to authorized users.

Hospital referral of detainees during police custody in Amsterdam, The Netherlands

This study describes how many detainees have been referred to emergency departments for further evaluation or emergency care while in police custody in Amsterdam (years 2012/2013). It provides insights into the diagnoses assigned by forensic doctors and hospital specialists and the appropriateness of the referrals. We made use of the electronic registration system of the Forensic Medicine Department of the Public Health Service Amsterdam. This department is in charge of the medical care for detainees in the Amsterdam region. Hospital diagnoses were obtained through collaboration with several Amsterdam-based hospitals. According to our results, in 1.5% of all consultations performed, the detainee was referred to hospital. The most frequent reasons for referral were injuries (66%), intoxication/withdrawal (11%) and cardiac problems (7%). In 18% of all referrals, hospital admission (defined as at least one night in the hospital) was the consequence. After review of hospital files, the indication for referral as stated by the forensic physician was confirmed in 77% of all cases. A minority of referrals was considered unnecessary (7%). The identified cases allow for a discussion of cases of over-referral. Future research should focus on the problem of under-referral and associated health risks.

Gender-specific differences in cannibalism between a laboratory strain and a field strain of a predatory mite

Many phytoseiid species, including Phytoseiulus persimilis, are known to engage in cannibalism when food is scarce and when there is no possibility to disperse. In nature adult females of P. persimilis are known to disperse when prey is locally depleted. Males, in contrast, are expected to stay and wait for potential mates to mature. During this phase, males can obtain food by cannibalizing. Therefore, we hypothesize that male P. persimilis exhibit a higher tendency to cannibalize than females. Because rearing conditions in the laboratory usually prevent dispersal, prolonged culturing may also affect cannibalistic behavior. We hypothesize that this should especially affect cannibalism by females, because they consume far more food. We tested these hypotheses by comparing males and females from two strains, one of which had been in culture for over 20 years, whereas the other was recently collected from the field. It is known that this predator can discriminate between kin and non-kin and prefers cannibalizing the latter, hence to construct lines with high relatedness we created isofemale lines of these two original strains. We subsequently tested to what extent the adult females and males of the original strains and the isofemale lines cannibalized conspecific larvae from the same strain/line in a closed system. Relatedness with the victims did not affect cannibalistic behavior, but males engaged more often in cannibalism than females, and females of the laboratory strain engaged more in cannibalism than those of the field strain, both in agreement with our ideas. We hypothesize that the difference in cannibalism between the two genders will increase when they have the alternative to disperse.

Markov Tail Chains

The extremes of a univariate Markov chain with regularly varying stationary marginal distribution and asymptotically linear behavior are known to exhibit a multiplicative random walk structure called the tail chain. In this paper we extend this fact to Markov chains with multivariate regularly varying marginal distributions inRd. We analyze both the forward and the backward tail process and show that they mutually determine each other through a kind of adjoint relation. In a broader setting, we will show that even for non-Markovian underlying processes a Markovian forward tail chain always implies that the backward tail chain is also Markovian. We analyze the resulting class of limiting processes in detail. Applications of the theory yield the asymptotic distribution of both the past and the future of univariate and multivariate stochastic difference equations conditioned on an extreme event.

Predator performance is impaired by the presence of a second prey species

The simultaneous infestation of a plant by several species of herbivores may affect the attractiveness of plants to the natural enemies of one of the herbivores. We studied the effect of coconut fruits infested by the pests Aceria guerreronis and Steneotarsonemus concavuscutum, which are generally found together under the coconut perianth. The predatory mite Neoseiulus baraki produced lower numbers of offspring on fruits infested with S. concavuscutum and on fruits infested with both prey than on fruits with A. guerreronis only. The predators were attracted by odours emanating from coconuts with A. guerreronis, but not by odours from coconuts with S. concavuscutum, even when A. guerreronis were present on the same fruit. Fewer N. baraki were recaptured on fruits with both prey or with S. concavuscutum than on fruits with only A. guerreronis. Furthermore, the quality of A. guerreronis from singly and multiply infested coconuts as food for N. baraki did not differ. Concluding, our results suggest that N. baraki does not perform well when S. concavuscutum is present on the coconuts, and the control of A. guerreronis by N. baraki may be negatively affected by the presence of S. concavuscutum.

Towards better dose individualisation: metabolic phenotyping to predict cabazitaxel pharmacokinetics in men with prostate cancer

BACKGROUND

Cabazitaxel is approved for treatment of castration-resistant metastatic prostate cancer. The current dosing strategy of cabazitaxel is based on body surface area (BSA). Body surface area is known as a poor predictor for total systemic exposure to drugs, since it does not take into account variability in activity of metabolising enzymes, necessary for clearance of drugs. As exposure to cabazitaxel is related to treatment response, it is essential to develop a better individualised dosing strategy.

METHODS

Ten patients with metastatic castration-resistant prostate cancer, who received cabazitaxel dosed on BSA as a part of routine palliative care, were enrolled in this study. Midazolam was administered as phenotyping probe for cytochrome P450 isoenzyme 3A (CYP3A). The relationship between midazolam and cabazitaxel clearance was investigated using non-linear mixed effects modelling.

RESULTS

The clearance of Midazolam highly correlated with cabazitaxel clearance (R=0.74). Midazolam clearance significantly (P<0.004) explained the majority (∼60%) of the inter-individual variability in cabazitaxel clearance in the studied population.

CONCLUSIONS

Metabolic phenotyping of CYP3A using midazolam is a promising strategy to individualise cabazitaxel dosing. Before clinical application, a randomised study is warranted.

Live Observation of Atherosclerotic Plaque Disruption in Apolipoprotein E-Deficient Mouse

AIM

The actual occurrence of spontaneous plaque rupture in mice has been a matter of debate. We report on an in vivo observation of the actual event of possible plaque disruption in a living ApoE(-/-) mouse.

METHODS AND RESULTS

During live contrast-enhanced ultrasonography of a 50-week-old ApoE(-/-) male mouse, symptoms suggesting plaque disruption in the brachiocephalic artery were observed. Histological analysis confirmed the presence of advanced atherosclerotic lesions with dissections and intraplaque hemorrhage in the affected brachiocephalic trunk, pointing towards plaque rupture as the cause of the observed event. However, we did not detect a luminal thrombus or cap rupture, which is a key criterion for plaque rupture in human atherosclerosis.

CONCLUSION

This study reports the real-time occurrence of a possible plaque rupture in a living ApoE(-/-) mouse.

Basal Ganglia Iron in Patients with Multiple Sclerosis Measured with 7T Quantitative Susceptibility Mapping Correlates with Inhibitory Control

BACKGROUND AND PURPOSE

T2 hypointensity in the basal ganglia of patients with MS has been associated with clinical progression and cognitive decline. Our objectives were the following: 1) to compare signal in T2WI, R2 (ie, 1/T2), and R2* (ie, 1/T2*) relaxation rates and quantitative susceptibility mapping; and 2) to investigate the associations among MR imaging, clinical scores, and cognitive measures of inhibitory control linked to basal ganglia functioning.

MATERIALS AND METHODS

Twenty-nine patients with MS underwent a battery of neuropsychological tests including the Flanker and Stroop tasks. 7T MR imaging included 3D gradient-echo and single-echo multishot spin-echo EPI. Quantitative susceptibility mapping images were calculated by using a Wiener filter deconvolution algorithm. T2WI signal was normalized to CSF. R2 and R2* were calculated by log-linear regression. Average MR imaging metrics for the globus pallidus, putamen, and caudate were computed from manually traced ROIs including the largest central part of each structure.

RESULTS

Marked spatial variation was consistently visualized on quantitative susceptibility mapping and T2/T2*WI within each basal ganglia structure. MR imaging metrics correlated with each other for each basal ganglia structure individually. Notably, caudate and putamen quantitative susceptibility mapping metrics were similar, but the putamen R2 was larger than the caudate R2. This finding suggests that tissue features contribute differently to R2 and quantitative susceptibility mapping. Caudate and anterior putamen quantitative susceptibility mapping correlated with the Flanker but not Stroop measures; R2 did not correlate with inhibitory control measures. Putamen quantitative susceptibility mapping and caudate and putamen R2 correlated with the Expanded Disability Status Scale.

CONCLUSIONS

Our study showed that quantitative susceptibility mapping and R2 may be complementary indicators for basal ganglia tissue changes in MS. Our findings are consistent with the hypothesis that decreased performance of basal ganglia-reliant tasks involving inhibitory control is associated with increased quantitative susceptibility mapping.

Epidemiology of augmented renal clearance in mixed ICU patients

BACKGROUND

Augmented renal clearance (ARC) or renal hyperfiltration is increasingly reported in intensive care unit (ICU) patients. The goal of this analysis was to study the epidemiology of ARC in a cohort of mixed ICU patients

METHODS

Single center retrospective cohort study of adult ICU patients (12/2008-2/2010). When data were available, urinary creatinine clearance (CLCR) was calculated for all patients throughout their ICU stay. ARC was defined as a body surface adjusted CLCR≥130 mL/min/1.73m2. We sought to study the incidence of ARC and identify patient characteristics associated with ARC.

RESULTS

A total of 1081 patients were included in the analysis, generating 4472 ICU patient days. Median age was 62 y (IQR 50-72), and 63% were male. The initial CLCR was 86 (39-151) mL/min and the maximal CLCR was 145 (76-237) mL/min. ARC occurred in 55.8% of patients, and was about as frequent in men and women (37%% vs. 35%%, P=0.73). Patients with ARC were younger (57 vs. 67 years, P<0.001) and were less frequently treated with vasopressors (27% vs. 39%, P<0.01). ARC incidence was 36.6 ARC days per 100 ICU days. ARC throughout the ICU stay occurred in 32.8% of patients.

CONCLUSION

ARC was a frequent finding in this cohort of ICU patients, with more than half of the patient expressing ARC at least once during their ICU stay, and an incidence of 36.6 ARC days/100 patient days.

Multiple nocardial abscesses of the brainstem and spinal cord diagnosed after an open biopsy through a cervical partial central corpectomy: case report

Nocardiosis of the central nervous system is a challenging and difficult diagnosis for the clinician. The combination of infections of the brain and spinal cord is even more rare. The authors report on a patient with multiple lesions in the brainstem and cervical spinal cord. This 81-year-old immunocompetent woman presented with symptoms of progressive walking difficulty and ataxia. The results of an extensive workup with laboratory investigation, MRI, lumbar puncture, positron emission tomography (PET), and bone marrow biopsy remained inconclusive. Only after an open biopsy of a cervical lesion by an anterior approach through a partial central corpectomy of the cervical spine, was the diagnosis of nocardiosis made, allowing for specific antibiotic treatment.

Inhibition of the spindle assembly checkpoint kinase TTK enhances the efficacy of docetaxel in a triple-negative breast cancer model

BACKGROUND

Triple-negative breast cancers (TNBC) are considered the most aggressive type of breast cancer, for which no targeted therapy exists at the moment. These tumors are characterized by having a high degree of chromosome instability and often overexpress the spindle assembly checkpoint kinase TTK. To explore the potential of TTK inhibition as a targeted therapy in TNBC, we developed a highly potent and selective small molecule inhibitor of TTK, NTRC 0066-0.

RESULTS AND CONCLUSIONS

The compound is characterized by long residence time on the target and inhibits the proliferation of a wide variety of human cancer cell lines with potency in the same range as marketed cytotoxic agents. In cell lines and in mice, NTRC 0066-0 inhibits the phosphorylation of a TTK substrate and induces chromosome missegregation. NTRC 0066-0 inhibits tumor growth in MDA-MB-231 xenografts as a single agent after oral application. To address the effect of the inhibitor in breast cancer, we used a well-defined mouse model that spontaneously develops breast tumors that share key morphologic and molecular features with human TNBC. Our studies show that combination of NTRC 0066-0 with a therapeutic dose of docetaxel resulted in doubling of mouse survival and extended tumor remission, without toxicity. Furthermore, we observed that treatment efficacy is only achieved upon co-administration of the two compounds, which suggests a synergistic in vivo effect. Therefore, we propose TTK inhibition as a novel therapeutic target for neoadjuvant therapy in TNBC.

Mechanisms and ecological consequences of plant defence induction and suppression in herbivore communities

BACKGROUND

Plants are hotbeds for parasites such as arthropod herbivores, which acquire nutrients and energy from their hosts in order to grow and reproduce. Hence plants are selected to evolve resistance, which in turn selects for herbivores that can cope with this resistance. To preserve their fitness when attacked by herbivores, plants can employ complex strategies that include reallocation of resources and the production of defensive metabolites and structures. Plant defences can be either prefabricated or be produced only upon attack. Those that are ready-made are referred to as constitutive defences. Some constitutive defences are operational at any time while others require activation. Defences produced only when herbivores are present are referred to as induced defences. These can be established via de novo biosynthesis of defensive substances or via modifications of prefabricated substances and consequently these are active only when needed. Inducibility of defence may serve to save energy and to prevent self-intoxication but also implies that there is a delay in these defences becoming operational. Induced defences can be characterized by alterations in plant morphology and molecular chemistry and are associated with a decrease in herbivore performance. These alterations are set in motion by signals generated by herbivores. Finally, a subset of induced metabolites are released into the air as volatiles and function as a beacon for foraging natural enemies searching for prey, and this is referred to as induced indirect defence.

SCOPE

The objective of this review is to evaluate (1) which strategies plants have evolved to cope with herbivores and (2) which traits herbivores have evolved that enable them to counter these defences. The primary focus is on the induction and suppression of plant defences and the review outlines how the palette of traits that determine induction/suppression of, and resistance/susceptibility of herbivores to, plant defences can give rise to exploitative competition and facilitation within ecological communities "inhabiting" a plant.

CONCLUSIONS

Herbivores have evolved diverse strategies, which are not mutually exclusive, to decrease the negative effects of plant defences in order to maximize the conversion of plant material into offspring. Numerous adaptations have been found in herbivores, enabling them to dismantle or bypass defensive barriers, to avoid tissues with relatively high levels of defensive chemicals or to metabolize these chemicals once ingested. In addition, some herbivores interfere with the onset or completion of induced plant defences, resulting in the plant's resistance being partly or fully suppressed. The ability to suppress induced plant defences appears to occur across plant parasites from different kingdoms, including herbivorous arthropods, and there is remarkable diversity in suppression mechanisms. Suppression may strongly affect the structure of the food web, because the ability to suppress the activation of defences of a communal host may facilitate competitors, whereas the ability of a herbivore to cope with activated plant defences will not. Further characterization of the mechanisms and traits that give rise to suppression of plant defences will enable us to determine their role in shaping direct and indirect interactions in food webs and the extent to which these determine the coexistence and persistence of species.

Comparison of different equations to assess glomerular filtration in critically ill patients

PURPOSE

To evaluate equations for estimation of glomerular filtration rate (GFR) and measured urinary creatinine clearance, compared to measured GFR in critically ill patients.

METHODS

GFR was measured using inulin clearance. Multiple blood samples were collected per patient for determination of serum creatinine, cystatin C and inulin. GFR was estimated by the use of the following estimation equations (eGFR): four commonly used creatinine-based equations [Cockcroft-Gault, Modification of Diet in Renal Disease (both the short and long formula) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)], five cystatin C based estimation equations (Hoek, Larsson, Filler, Le Bricon, CKD-EPIcys) and one equation combining cystatin C and serum creatinine (CKD-EPIcr-cys). In addition we measured urinary creatinine clearance. Bias, precision and accuracy of all estimates were compared to those of the inulin clearance.

RESULTS

Data were collected from 83 patients, of whom 68 were considered evaluable. The median age was 58 years [interquartile range (IQR) 39-68]. The median inulin clearance was 80 mL/min/1.73 m(2) (IQR 31-114). Equations based on creatinine had much bias and poor precision and accuracy. Measured urinary creatinine clearances overestimated GFR. Equations based on cystatin C were free of bias, but also had limited precision and accuracy.

CONCLUSIONS

In this cohort of patients, estimates of GFR had low accuracy and precision. Cystatin C based formulas, especially CKD-EPIcr-cys, showed limited bias; however, the accuracy and precision of these estimates were still insufficient. Measured urinary creatinine clearance overestimates GFR, but may provide a cheap alternative, when this is taken into account.

Second family with the Boston-type craniosynostosis syndrome: novel mutation and expansion of the clinical spectrum

Craniosynostosis, caused by early fusion of one or more cranial sutures, can affect the coronal or lambdoid sutures, or include premature fusion of the sagittal (scaphocephaly) or metopic suture (trigonocephaly). Often occurring as isolated finding, their co-existence in a craniosynostosis syndrome is infrequent. We describe a four-generation family with variable expression of a craniosynostosis phenotype with scaphocephaly and a particularly severe trigonocephaly. Molecular analysis revealed a missense mutation in the MSX2-associated with the Boston-type craniosynostosis syndrome-affecting the same amino-acid residue as in the original Boston family. Besides unique features such as the cranial sutures involved, minor limb abnormalities and incomplete penetrance, our patients share with the original family autosomal dominant inheritance and the presence of multiple endocranial erosions on CT imaging. Though these findings appear to be important diagnostic clues for MSX2-related craniosynostosis, it is noteworthy that the first affected generation in this family presented merely with isolated sagittal or unicoronal craniosynostosis and cutaneous syndactyly. Molecular analysis of MSX2 should therefore be considered in patients with isolated scaphocephaly/unicoronal synostosis, especially in the presence of a family history for craniosynostosis or syndactyly.

Genetic instability: tipping the balance

Tumor cells typically contain a genome that is highly divergent from the genome of normal, non-transformed cells. This genetic divergence is caused by a number of distinct changes that the tumor cell acquires during its transformation from a normal cell into a tumorigenic counterpart. Changes to the genome include mutations, deletions, insertions, and also gross chromosomal aberrations, such as chromosome translocations and whole chromosome gains or losses. This genetic disorder of the tumor cell has complicated the identification of crucial driver mutations that cause cancer. Moreover, the large genetic divergence between different tumors causes them to behave very differently, and makes it difficult to predict response to therapy. In addition, tumor cells are genetically unstable and frequently acquire new mutations and/or gross chromosomal aberrations as they divide. This is beneficial for the overall capacity of a tumor to adapt to changes in its environment, but newly acquired genetic alterations can also compromise the genetic dominance of the tumor cell and thus affect tumor cell viability. Here, we review the mechanisms that can cause gross chromosomal aberrations, and discuss how these affect tumor cell viability.