Revolutionizing DNA repair research and cancer therapy with CRISPR-Cas screens.

All organisms possess molecular mechanisms that govern DNA repair and associated DNA damage response (DDR) processes. Owing to their relevance to human disease, most notably cancer, these mechanisms have been studied extensively, yet new DNA repair and/or DDR factors and functional interactions between them are still being uncovered. The emergence of CRISPR technologies and CRISPR-based genetic screens has enabled genome-scale analyses of gene-gene and gene-drug interactions, thereby providing new insights into cellular processes in distinct DDR-deficiency genetic backgrounds and conditions. In this Review, we discuss the mechanistic basis of CRISPR-Cas genetic screening approaches and describe how they have contributed to our understanding of DNA repair and DDR pathways. We discuss how DNA repair pathways are regulated, and identify and characterize crosstalk between them. We also highlight the impacts of CRISPR-based studies in identifying novel strategies for cancer therapy, and in understanding, overcoming and even exploiting cancer-drug resistance, for example in the contexts of PARP inhibition, homologous recombination deficiencies and/or replication stress. Lastly, we present the DDR CRISPR screen (DDRcs) portal , in which we have collected and reanalysed data from CRISPR screen studies and provide a tool for systematically exploring them.

SOX9 maintains human foetal lung tip progenitor state by enhancing WNT and RTK signalling.

The balance between self-renewal and differentiation in human foetal lung epithelial progenitors controls the size and function of the adult organ. Moreover, progenitor cell gene regulation networks are employed by both regenerating and malignant lung cells, where modulators of their effects could potentially be of therapeutic value. Details of the molecular networks controlling human lung progenitor self-renewal remain unknown. We performed the first CRISPRi screen in primary human lung organoids to identify transcription factors controlling progenitor self-renewal. We show that SOX9 promotes proliferation of lung progenitors and inhibits precocious airway differentiation. Moreover, by identifying direct transcriptional targets using Targeted DamID, we place SOX9 at the centre of a transcriptional network, which amplifies WNT and RTK signalling to stabilise the progenitor cell state. In addition, the proof-of-principle CRISPRi screen and Targeted DamID tools establish a new workflow for using primary human organoids to elucidate detailed functional mechanisms underlying normal development and disease.

Are children with food allergies more likely to have lower urinary tract symptoms? A case-control study.

INTRODUCTION: There are multiple historic reports linking lower urinary tract symptoms (LUTS) in children with food allergies (FA), but contemporary studies are sparse. The objective of this study was to evaluate a potential link between FA and LUTS in the pediatric population. We hypothesized that children with FAs are more likely to have LUTS. MATERIALS AND METHODS: After local IRB approval, pediatric patients (6-17 years [y]) with FAs proven by positive skin prick and/or serum IgE testing were invited to participate. A control group of pediatric patients without FAs was also recruited. All families/legal guardians signed informed consent, and all children signed written assent. Each participant filled out the Vancouver Symptom Score (VSS), a validated questionnaire for dysfunctional elimination syndrome, and the Pediatric Incontinence Questionnaire (PinQ), a validated quality of life assessment for children with bladder dysfunction. Demographic and clinical information were obtained retrospectively. RESULTS: From 2019-2020, 26 children with FAs and 57 without agreed to participate. Mean age was 9.3 y (IQR 7.9 y-13.5 y). There were no differences in gender, age, or race between the two cohorts. There were no significant differences between the two groups in mean VSS score or mean PinQ score. Four children with FAs (15%) and 15 children without (26%) had VSS score ≥ 11 (p = 0.339), indicating dysfunctional elimination. The median PinQ score was 0 (IQR 0-2) in both cohorts. CONCLUSIONS: This study did not identify an association between FAs and LUTS in a population of pediatric patients with laboratory proven FAs.

Near-Field Coupling with a Nanoimprinted Probe for Dark Exciton Nanoimaging in Monolayer WSe2.

Tip-enhanced photoluminescence (TRPL) is a powerful technique for spatially and spectrally probing local optical properties of 2-dimensional (2D) materials that are modulated by the local heterogeneities, revealing inaccessible dark states due to bright state overlap in conventional far-field microscopy at room temperature. While scattering-type near-field probes have shown the potential to selectively enhance and reveal dark exciton emission, their technical complexity and sensitivity can pose challenges under certain experimental conditions. Here, we present a highly reproducible and easy-to-fabricate near-field probe based on nanoimprint lithography and fiber-optic excitation and collection. The novel near-field measurement configuration provides an ∼3 orders of magnitude out-of-plane Purcell enhancement, diffraction-limited excitation spot, and subdiffraction hyperspectral imaging resolution (below 50 nm) of dark exciton emission. The effectiveness of this high spatial XD mapping technique was then demonstrated through reproducible hyperspectral mapping of oxidized sites and bubble areas.

Direct Visualization of the Charge Transfer in a Graphene/α-RuCl3 Heterostructure via Angle-Resolved Photoemission Spectroscopy.

We investigate the electronic properties of a graphene and α-ruthenium trichloride (α-RuCl3) heterostructure using a combination of experimental techniques. α-RuCl3 is a Mott insulator and a Kitaev material. Its combination with graphene has gained increasing attention due to its potential applicability in novel optoelectronic devices. By using a combination of spatially resolved photoemission spectroscopy and low-energy electron microscopy, we are able to provide a direct visualization of the massive charge transfer from graphene to α-RuCl3, which can modify the electronic properties of both materials, leading to novel electronic phenomena at their interface. A measurement of the spatially resolved work function allows for a direct estimate of the interface dipole between graphene and α-RuCl3. Their strong coupling could lead to new ways of manipulating electronic properties of a two-dimensional heterojunction. Understanding the electronic properties of this structure is pivotal for designing next generation low-power optoelectronics devices.

Understanding factors influencing primary treatment with intradetrusor onabotulinumtoxinA versus augmentation cystoplasty in patients with spina bifida.

PURPOSE: Surgical interventions in the urologic management of children with neurogenic bladder secondary to spina bifida aim to preserve upper tract function, prevent urinary tract infections, and optimize quality of life. However, since the introduction of intravesical onabotulinumtoxinA (Botox) in the management of these patients, the indications for choosing Botox over augmentation cystoplasty (AC) remain undefined. The objective of this study was to determine which factors lead patients to undergo Botox versus AC as a primary surgical treatment after failing medical management. METHODS: We retrospectively reviewed the records of pediatric patients with myelomeningocele undergoing either primary Botox or primary AC at our institution between 2013 and 2018. We recorded demographic and clinical information. We identified 10 important clinical decision-making factors: bladder trabeculation, vesicoureteral reflux, or hydronephrosis on imaging; end-filling pressure (EFP) ≥40 cm H2O, detrusor overactivity, detrusor-sphincter dyssynergia, or reduced capacity on urodynamic studies; physician-perceived bladder hostility; and patient/family desire for continence and independence. The presence of these factors was compared between patients undergoing either primary Botox or primary AC. RESULTS: We identified 14 and 50 myelomeningocele patients who underwent primary AC and primary Botox, respectively. We found no significant differences in age, sex, race, or history of reconstructive surgery (antegrade continence enema or catheterizable channel). For the 10 decision-making factors, desire for independence/continence (p = <0.001) and reduced capacity (p = 0.002) were significantly associated with AC, while trabeculation (p = 0.006), EFP ≥40 cm H2O (p = 0.029), rising slope (p = 0.019), and physician-perceived hostility (p = 0.012) were significantly more common with Botox. CONCLUSIONS: At our institution, quality of life measures prompted AC over objective urodynamic or imaging findings before attempting Botox. These findings support a shared decision-making approach when considering surgical intervention for neurogenic bladder secondary to myelomeningocele.

Loss of Cyclin C or CDK8 provides ATR inhibitor resistance by suppressing transcription-associated replication stress.

The protein kinase ATR plays pivotal roles in DNA repair, cell cycle checkpoint engagement and DNA replication. Consequently, ATR inhibitors (ATRi) are in clinical development for the treatment of cancers, including tumours harbouring mutations in the related kinase ATM. However, it still remains unclear which functions and pathways dominate long-term ATRi efficacy, and how these vary between clinically relevant genetic backgrounds. Elucidating common and genetic-background specific mechanisms of ATRi efficacy could therefore assist in patient stratification and pre-empting drug resistance. Here, we use CRISPR-Cas9 genome-wide screening in ATM-deficient and proficient mouse embryonic stem cells to interrogate cell fitness following treatment with the ATRi, ceralasertib. We identify factors that enhance or suppress ATRi efficacy, with a subset of these requiring intact ATM signalling. Strikingly, two of the strongest resistance-gene hits in both ATM-proficient and ATM-deficient cells encode Cyclin C and CDK8: members of the CDK8 kinase module for the RNA polymerase II mediator complex. We show that Cyclin C/CDK8 loss reduces S-phase DNA:RNA hybrid formation, transcription-replication stress, and ultimately micronuclei formation induced by ATRi. Overall, our work identifies novel biomarkers of ATRi efficacy in ATM-proficient and ATM-deficient cells, and highlights transcription-associated replication stress as a predominant driver of ATRi-induced cell death.

Measuring particle size in ultra-low concentration suspensions by removing the number fluctuation contribution in dynamic light scattering.

In ultra-low concentration suspensions, particle number fluctuations in the scattering volume add a long delay component to the intensity autocorrelation function (ACF) in dynamic light scattering (DLS) measurements. This gives a strong artifact peak in the particle size distribution (PSD) recovered. To improve the accuracy of DLS at ultra-low concentrations, we analyzed the different decay characteristics of particle Brownian motion and particle number fluctuation in the ACF. By differentiating the ACF we were able to identify and separate the number fluctuation term and then analyze the ACF to recover the PSD. The results for simulated DLS data at 151nm and 690nm diameters with average particle numbers of 6, 12, 24 and 48 in the scattering volume at four noise levels show that, compared with the usual DLS data processing method, inversion of the ACF after the separation of the number fluctuation term effectively eliminates the strong artifact peaks, and the relative errors of peak positions and distribution errors are significantly reduced. This was further verified with experimental results from samples of standard polystyrene spheres.

Effect of Prenatal Repair of Myelomeningocele on Urological Outcomes at School Age.

PURPOSE: We investigated longer term urological outcomes in patients enrolled in the Management of Myelomeningocele Study (MOMS). MATERIALS AND METHODS: Women who participated in the original trial were asked for consent for followup for their child at age 6 years or older in a single comprehensive study visit to a MOMS center. Participating children underwent urological and radiologic procedures to provide objective evidence of current bladder functioning. Primary urological outcome was defined as any among need for clean intermittent catheterization, vesicostomy, urethral dilatation or augmentation cystoplasty. RESULTS: A total of 156 children were evaluated, with a mean age of 7.4 years. Overall 62% vs 87% in the prenatal and postnatal surgery groups, respectively, were placed on clean intermittent catheterization (RR 0.71, 95% CI 0.58-0.86, p <0.001). Voiding status was significantly different between the groups (p <0.001) as 24% in the prenatal group vs 4% in the postnatal group (RR 5.8, 95% CI 1.8-18.7) were reported to be voiding volitionally. Augmentation cystoplasty, vesicostomy and urethral dilation did not differ between the 2 groups. Aside from a larger post-void residual urodynamic catheterization volume, there were no other statistical differences in videourodynamic data or findings on renal/bladder ultrasound. CONCLUSIONS: Prenatal closure of myelomeningocele resulted in less reported clean intermittent catheterization at school age and the mechanism for this is unclear. Although most children are in diapers or on clean intermittent catheterization, parental reports showed children who underwent prenatal closure may be more likely to void volitionally than the postnatal group. Despite these findings, urological outcomes alone should not be the sole impetus to perform in utero closure in children with spina bifida.

Multi-angle dynamic light scattering analysis based on successive updating of the angular weighting.

The angular weighting coefficient is key to accurate particle size distribution (PSD) measurement using multiangle dynamic light scattering (MDLS). However, determining the weighting coefficient is affected by the noise in the measured MDLS data. In this paper, a novel successive updating of the angular weighting (AWSU) method is proposed. By using information character weighting, the angular weighting coefficient and the character weighting matrix are updated once with each additional angle. The effect of autocorrelation function (ACF) denoising and information extraction is improved by using information character weighting step-by-step. The results for broad unimodal and closely-spaced bimodal PSDs demonstrate the effectiveness of this method. Compared with another routinely used inversion method, it is found that the increase in PSD information retrieved from MDLS depends not only on increasing the number of angles, but also on the calculation of the angular weightings. An accurate weighting algorithm can reduce the number of scattering angles required. Using the AWSU method for PSD recovery with 4 scattering angles can give better results than the usual method with 6 scattering angles. It is also found that the AWSU method not only improves the accuracy of the weightings, but it also contributes directly to the PSD recovery by reconstructing the ACF with the PSD obtained by the weighted inversion. The combination of these two contributions not only reduces the number of scattering angles needed, but also keeps the PSD recovery results from getting worse because of excessive scattering angles.

Pelvic floor biofeedback therapy in children: Assessment of symptom scores in responders and non-responders.

INTRODUCTION: Pelvic Floor Biofeedback Therapy (PFBT) can be an effective treatment for pediatric lower urinary tract symptoms (LUTS). Due to differing perceptions of efficacy and practice patterns, we sought to further evaluate PFBT in our practice. We hypothesized that PFBT results in quiescence of EMG activity during voiding and improves questionnaire scores in patients with LUTS. METHODS: We retrospectively reviewed all patients undergoing PFBT and refined the analysis to females ≥6 years old with ≥2 sessions with completed voiding questionnaires pre- and post-treatment, active EMG during voiding, with non-neurogenic urinary tract complaints refractory to standard urotherapy. Validated Bladder Bowel Dysfunction (BBD) questionnaires were collected at each visit. Quiescence of EMG activity and changes in BBD score were the primary outcomes. RESULTS: 229 patients underwent ≥1 PFBT session, of which 64 females ≥6 years of age with ≥2 PFBT sessions and completed pre and post PFBT voiding questionnaires were identified. In this group, mean age at PFBT start was 10.1 (6.2-17.0). Patients completed 3.1 sessions (2-6). No difference was seen in post-void residual (PVR) between first and last session (23.8 vs 22.6 mL, P = 0.55). Median questionnaire score decreased from 18 (4-42) before to 13 (2-28) following PFBT (P < 0.0001). Responders, characterized by silencing of the EMG after PFBT, occurred in 31% (20/64). Non-responders were younger (P = 0.007) with higher pre-PFBT questionnaire scores. CONCLUSION: The use of PFBT appears to result in a significant reduction in symptom scores, though quiescence of EMG was observed following therapy in less than 1/3 of patients.

Interrater Reliability in Interpretation of Neuropathic Pediatric Urodynamic Tracings: An Expanded Multicenter Study.

PURPOSE: Urodynamic findings often guide treatment for neuropathic bladder and are reported as objective data points in multi-institutional trials. However, urodynamic interpretation can be variable. In a pilot study pediatric urologists interpreting videourodynamics exhibited only moderate agreement despite similar training and practice patterns. We hypothesized the pilot study variability would be replicated in a multi-institutional study. MATERIALS AND METHODS: We developed an anonymous electronic survey that contained 20 scenarios, each with a brief patient history, 1 urodynamic tracing and fluoroscopic imagery. All videourodynamics were completed during routine care of patients with neuropathic bladder at a single institution. Pediatric urologists from Centers for Disease Control and Prevention Urologic Protocol sites were invited to complete an interpretation instrument for each scenario. Fleiss kappa and 95% confidence limits were reported, with Fleiss kappa 1.00 corresponding to perfect agreement. RESULTS: The survey was completed by 14 pediatric urologists at 7 institutions. Substantial agreement was seen for assessment of fluoroscopic bladder shape (Fleiss kappa 0.73), while moderate agreement was observed for assessment of bladder safety, end filling detrusor pressure and bladder capacity (Fleiss kappa 0.50, 0.56 and 0.54, respectively). Fair agreement was seen for electromyographic synergy and presence of detrusor overactivity (Fleiss kappa 0.21 and 0.35, respectively). CONCLUSIONS: Experienced pediatric urologists demonstrate variability during interpretation of videourodynamic tracings. Subjectivity of assessment of electromyographic activity and detrusor overactivity was confirmed in this expanded study. Future work to improve the reliability of videourodynamic interpretation would improve the quality of clinical care and the quality of multi-institutional studies that use urodynamic data points as outcomes.

Optimized criteria for angular parameter selection for the Chin-Shifrin integral transform inversion.

The accuracy of the particle size distribution (PSD) recovered from laser diffraction measurements by the Chin-Shifrin integral transform algorithm is reduced unless the proper angular parameters, including the lower and upper angular integration limits (θmax and θmin) and the angular resolution (Δθ), are used. To determine the selection criteria for these parameters, we use two metrics: the inversion error of the non-negative PSD, ε1, and the fitting error of the scattered laser light, ε2. By studying the variation of the minimum θmax and ε2 with the particle size at different inversion errors, and by analyzing the inversion error, as θmin and Δθ are varied, the optimized selection criteria for the minimum θmax, θmin and Δθ are obtained respectively. The inversion errors of the Chin-Shifrin algorithm with different selection criteria are compared, the different PSDs are recovered, and the optimal pixel selection range of the linear charge-coupled-device (CCD) array is determined according to the optimized selection criteria. Simulation results show that the optimized selection criteria for the angular parameters make the PSDs retrieved with the Chin-Shifrin algorithm more accurate.

Information-weighted constrained regularization for particle size distribution recovery in multiangle dynamic light scattering.

In particle size measurement with dynamic light scattering (DLS), it is difficult to get an accurate recovery of a bimodal particle size distribution (PSD) with a peak position ratio less than ~2:1, especially when large particles (>350nm) are present. This is due to the inherent noise in the autocorrelation function (ACF) data and the scarce utilization of PSD information during the inversion process. In this paper, the PSD information distribution in the ACF data is investigated. It was found that the initial decay section of the ACF contains more information, especially for a bimodal PSD. Based on this, an information-weighted constrained regularization (IWCR) method is proposed in this paper and applied in multiangle DLS analysis for bimodal PSD recovery. By using larger (or smaller) coefficients for weighting the ACF data, more (or less) weight can then be given to the initial part of the ACF. In this way, the IWCR method can enhance utilization of the PSD information in the ACF data, and effectively weaken the effect of noise at large delay time on PSD recovery. Using this method, bimodal PSDs (with nominal diameters of 400:608 nm, 448:608 nm, 500:600 nm) were recovered successfully from simulated data and it appears that the IWCR method can improve the recovery resolution for closely spaced bimodal particles. Results of the PSD recovery from experimental DLS data confirm the performance of this method.

Update on Continent Catheterizable Channels and the Timing of their Complications.

PURPOSE: We previously reported catheterizable channel associated outcomes and concluded that the incidence of postoperative complications was greatest in the first 2 years after surgery. At that time our followup was short. In this series we sought to determine whether complications continued to accumulate with longer followup in an updated cohort of patients. MATERIALS AND METHODS: We comprehensively reviewed the outcomes in 81 consecutive patients who underwent construction of a MACE (Malone antegrade continence enema) and/or a Mitrofanoff channel in association with complex genitourinary reconstruction. Mean followup was 80.1 months. Outcomes of these 119 stomas were classified by Clavien-Dindo grade and time to complication. RESULTS: The 48 unique, channel related events (40.3%) necessitated a total of 70 interventions with a mean 24.2 months to the first event. Difficult catheterization was the most common event, occurring in 20.1% of channels an average of 29.9 months after surgery. Stomal stenosis was also common, developing in 12.6% of channels at an average of 19.9 months after surgery. Unique complications clustered in the first 2 years, after which there was a statistically significant decline (p = 0.0013). High grade complications similarly clustered (p <0.0001). Channel composition was significantly associated with rates of difficult catheterization events. CONCLUSIONS: Compared to our previous cohort of patients with similar volume but shorter followup, our assumption that channel associated complications cluster postoperatively and then decrease significantly was correct. Our current and more detailed series demonstrates that the rate of postoperative complications decreases with time. However, with longer followup patients continue to experience lower grade events requiring fewer interventions.

Interrater Reliability in Pediatric Urodynamic Tracings: A Pilot Study.

PURPOSE: Urodynamic studies are crucial to neuropathic bladder management and they often determine surgical intervention. However, current evidence indicates that interpretations show poor agreement across physicians. We sought to determine the interrater reliability of urodynamic interpretation in our practice. We hypothesized that there would be strong correlation among pediatric urologists of similar training in a single academic practice. MATERIALS AND METHODS: We retrospectively identified patients with neuropathic bladder who underwent urodynamics at our institution between 2014 and 2015. An anonymous electronic survey (phase I) was developed with 20 clinical scenarios, each containing a brief history, a single urodynamic tracing and an accompanying fluoroscopic image. Faculty members assessed each tracing by an online instrument developed using urodynamic reports and published literature. The primary outcome was statistical correlation across raters as measured by the Spearman correlation coefficient. In a followup study (phase II) we investigated the sources of variability in urodynamic interpretations. RESULTS: Six faculty members completed the study with a response rate of 100%. In comparing urodynamic interpretation across raters, the faculty demonstrated a weak to strong correlation (rs 0.39-0.61, p <0.001). A strong correlation was found for fluoroscopic and clinical decision making variables, while electromyography synergy and detrusor overactivity demonstrated weaker correlation across physicians. CONCLUSIONS: Faculty interpretations of urodynamic tracings showed only moderate agreement despite a close working relationship and similar training at a single institution. Variability in interpretation can strongly impact patient treatment. Therefore, further work is needed to standardize the reporting and interpretation of urodynamic studies to optimize patient care.

Lp-norm-residual constrained regularization model for estimation of particle size distribution in dynamic light scattering.

In particle size measurement using dynamic light scattering (DLS), noise makes the estimation of the particle size distribution (PSD) from the autocorrelation function data unreliable, and a regularization technique is usually required to estimate a reasonable PSD. In this paper, we propose an Lp-norm-residual constrained regularization model for the estimation of the PSD from DLS data based on the Lp norm of the fitting residual. Our model is a generalization of the existing, commonly used L2-norm-residual-based regularization methods such as CONTIN and constrained Tikhonov regularization. The estimation of PSDs by the proposed model, using different Lp norms of the fitting residual for p=1, 2, 10, and ∞, is studied and their performance is determined using simulated and experimental data. Results show that our proposed model with p=1 is less sensitive to noise and improves stability and accuracy in the estimation of PSDs for unimodal and bimodal systems. The model with p=1 is particularly applicable to the noisy or bimodal PSD cases.

Prospective Evaluation of Sacral Neuromodulation in Children: Outcomes and Urodynamic Predictors of Success.

PURPOSE: Sacral neuromodulation has been demonstrated to improve refractory bowel bladder dysfunction in children. The purpose of the current study was to determine whether results are durable in children after longer followup, whether children with a lower body mass index are at risk for device failure and whether pretreatment urodynamic evaluation can predict posttreatment outcome. MATERIALS AND METHODS: Pediatric patients with refractory bowel bladder dysfunction were enrolled following informed consent and followed prospectively. All patients underwent preoperative videourodynamic evaluation and a 2-stage implantation procedure. Validated questionnaires were used to assess symptom severity and quality of life. Complications were analyzed with regard to treatment required and patient body mass index. RESULTS: During 45 months 30 patients were enrolled. Median age was 8.3 years at enrollment. Median followup was 14.8 months. Patients had significant improvement in quality of life and symptom scores, which persisted at the most recent followup. Patients who had uninhibited detrusor contractions on preoperative urodynamic assessment had significantly greater improvement in symptoms. Of the patients 23% had a complication requiring reoperation, most commonly neurostimulator lead breakage in those with a significantly lower body mass index. CONCLUSIONS: Sacral neuromodulation significantly improves quality of life and symptom severity in children with refractory bowel bladder dysfunction. Children gain greater benefit if they show uninhibited bladder contractions on preoperative urodynamic evaluation. Children have a high rate of lead breakage requiring operative revision, which was seen after minor trauma in those with a lower body mass index.

Bullying and lower urinary tract symptoms: why the pediatric urologist should care about school bullying.

PURPOSE: Bullying has become a social plague associated with various deleterious outcomes. We hypothesized that pediatric lower urinary tract symptoms could be associated with exposure to bullying. MATERIALS AND METHODS: We assessed exposure to school bullying via the Setting the Record Straight bullying questionnaire in children 8 to 11 years old being evaluated for lower urinary tract symptoms at our pediatric urology clinic. Lower urinary tract symptoms were quantified with the Vancouver Symptom Score. Children 8 to 11 years old presenting for pediatric well visits also completed the questionnaires. Linear regression assessed the relationship between Vancouver Symptom Score and bullying score. Categorical variables were compared by chi-square test, while continuous variables were compared using the Student t-test. RESULTS: A total of 113 children at the urology clinic and 63 children in the primary care setting consented to participate. There were significant differences between the 2 populations, including gender and race, with significantly more perpetrators of bullying in the primary care group (7.9% vs 0.9%, p = 0.02). When looking specifically at the urology group, there was a significant association between Vancouver Symptom Score and self-perceived (p <0.001) and peer perceived (p <0.001) victimization scores. In the primary care group there was also a significant association between Vancouver Symptom Score and self-perceived (p = 0.01) and peer perceived (p = 0.001) bullying perpetrator scores. Of children seen at the primary care office 33% had a significant Vancouver Symptom Score. CONCLUSIONS: Although bullying exposure is multifactorial, we found that Vancouver Symptom Score can be associated with bullying victimization and perpetrator scores.

Effect of scattering angle error on particle size determination by multiangle dynamic light scattering.

Dynamic light scattering (DLS) is a popular method of particle size measurement. Multiangle dynamic light scattering (MDLS) collects DLS data at multiple angles and analyzes the data simultaneously to improve the particle size measurement. Using data from several scattering angles admits the possibility of introducing noise caused by scattering angle error in the measurement, which may have an impact on the performance of the MDLS technique. We investigate the effect of scattering angle noise on recovered particle size distributions (PSDs) using simulated and measured MDLS data and various levels of angular noise. Our results show that, for unimodal PSDs, those with small particle sizes are more strongly affected by the noise than are medium and large particle size systems. For bimodal PSDs, those containing small-sized particles are also more affected by the noise than the systems of larger particles. Furthermore, broad PSDs are more vulnerable to angular noise than narrow PSDs.