Dosimetric Analysis of Major Wound Complications Following Preoperative Ultra-Hypofractionated Radiation Therapy for Soft Tissue Sarcoma

PURPOSE/OBJECTIVE(S)

Preoperative radiation therapy (RT) for soft tissue sarcomas (STS), delivered with conventional fractionation, has been shown to reduce long-term toxicity at the expense of increased postoperative major wound complications (MWC). Ultra-hypofractionated RT has emerged as a potential alternative preoperative modality with early but comparable outcomes to conventional regimens. However, limited data are available evaluating dosimetric, patient, and treatment specific factors associated with development of MWC in this setting.

MATERIALS/METHODS

This IRB approved review included STS patients treated with preoperative 5 fraction daily RT followed by surgical resection within 7 days. Patients were evaluated for MWCs in association with patient and tumor characteristics, dosimetric parameters, and treatment techniques. MWCs were defined as a return to operating room, readmission for wound care or IV antibiotics, and persistent deep packing for >120 days. Prescription isodose line, PTV mean dose and the PTV volume exposed to 105% and 110% of prescribed dose were recorded. Dose to tissue likely to be involved in wound healing was assessed by creating a 1 cm thick superficial skin strip within 2 cm of the PTV which was then evaluated for volume, mean dose, V15, V21, V27, and V30. Secondary endpoints were locoregional control (LRC), metastasis free survival (MFS), and overall survival (OS).

RESULTS

A total of 31 patients with a median age of 66 years (range 28-87) and a median follow up of 21 months (IQR 8-43) were included. All patients received 30 Gy in 5 fractions using IMRT/VMAT. There were 11 upper limb (36%) and 20 lower limb (65%) tumors included. Median time to resection following RT was 1 day (IQR 0-3). Median tumor size was 8 cm (IQR 5-13). MWC occurred in 13 patients (42%) with 10 patients (32%) requiring additional surgery. Dehiscence and infection requiring IV antibiotics occurred in 12 (39%) and 6 patients (19%), respectively. RT plans were predominately prescribed to the PTV mean (87%) with a median prescription isodose of 97% (IQR 96-97) and PTV mean dose of 3110 cGy (IQR 3089-3142). Median PTV volume, mean dose, and volume of PTV receiving 105% and 110% of the prescribed dose were higher in the MWC cohort although none reached significance. Similarly, for the 1 cm skin strip the median volume, mean dose, V30, V27, V21, and V15 were all higher in the MWC cohort without significant difference. Among patient, treatment, and tumor factors: tumor size, location, grade, margin status, type of wound closure, and prior non-oncologic resection were not associated with MWC. LRC, MFS, and OS at 3-years were 96%, 67%, and 76%, respectively.

CONCLUSION

Although not reaching significance, increased plan homogeneity and reduced dose/volume relationships in proximity to the skin trended to reduced MWC in this limited cohort. Multi-institutional collaboration may be warranted to better identify factors associated with MWC in patients treated with preoperative ultra-hypofractionated RT.

Meta-Analysis of Five Fraction Preoperative Radiotherapy for Soft Tissue Sarcoma

PURPOSE/OBJECTIVE(S)

There is increasing interest in shorter courses of radiation therapy (RT) in the management of soft tissue sarcoma (STS). Studies investigating preoperative ultra-hypofractionated 5-fraction RT for STS are few and often limited to single institution experiences with less than 50 patients. We therefore performed a meta-analysis to determine the efficacy and safety of preoperative 5-fraction RT for STS based on currently published literature, with an analysis evaluating effects of dose delivered.

MATERIALS/METHODS

This study level meta-analysis was conducted using Bayesian methods. Statistical estimation for risk of outcome rates were conducted by posterior mean and 95% highest posterior density (HPD) intervals. Studies with two-year local control (LC) and description of major wound complications (MWC) per the CAN-NCIC-SR2 study were included in this meta-analysis, and these served as the primary endpoints. Secondary endpoints included rates of acute and late toxicity. A total of ten studies were identified; seven met inclusion criteria (Kalbasi 2020, Kubicek 2021, Leite 2021, Spalek 2021, Gobo Silva 2021, Bedi 2022, Mayo 2022). Three studies (Kosela-Paterczyk 2014, Kosela-Paterczyk 2021, Potkrajcic 2021) did not include adequate information to accurately determine 2-year LC or MWC. Subgroup analyses were performed for ≥30 Gy vs <30 Gy as the EQD2 of 30 Gy in 5 fractions for an α/β of 3-4 is 50-54 Gy, equivalent to standard preoperative RT fractionation.

RESULTS

A total of 208 patients were included from seven studies. Five studies used ≥30 Gy (n = 144) and 2 studies <30 Gy (n = 64). The median follow-up was 29 months (range: 21-57). Primary tumor location was lower extremity in 68%, upper extremity in 22%, and trunk in 10%. In studies with available information, most tumors were intermediate (27%, 46/169) or high grade (67%, 114/169) and 50% (79/158) were >10 cm. Two-year LC for the entire cohort was 96.9% (95% HPD: 0.9374-0.9889) and the rate of MWC was 30.6% (95% HPD: 0.2106-0.4149). Acute grade 2 and 3 dermatitis was seen in 12.7% and 2.2%, respectively. Late grade 2 toxicities included fibrosis (11.1%), stiffness (6.0%), and lymphedema (4.0%) and late grade 3 toxicities included fibrosis (1.8%) and stiffness (0.4%). Grade 4 toxicity was rare and included fibrosis (0.6%) and stiffness (0.6%). There was a trend toward improved LC with ≥ 30 Gy (95% HPD: 0.949-0.997 vs 0.838-0.986). There was no difference in MWC (95% HPD: 0.185-0.420 vs 0.172-0.553) or late toxicity between the two groups. Acute grade 3 dermatitis was seen less frequently with regimens <30 Gy (95% HPD: 0-0 vs 0.009-0.072), however rare overall.

CONCLUSION

Preoperative 5-fraction RT for STS demonstrates excellent 2-year LC with MWC and toxicity similar to standard fractionation preoperative RT. Multi-institutional trials with a universal RT protocol and larger sample size are warranted to assess this novel treatment paradigm.

Radio-Immune Response of Spatially Fractionated Radiotherapy for VMAT Lattice Plans

PURPOSE/OBJECTIVE(S)

To evaluate radio-immune response of spatially fractionated radiotherapy (SFRT) for large tumors using VMAT Lattice technique in terms of tumor volume under irradiation and dose fractionation schemes after SFRT.

MATERIALS/METHODS

Eleven patients treated with SFRT from a single institution were retrospectively replanned to deliver 15Gy in single fraction using Lattice technique. High dose regions are defined by multiple spheres with the diameter of 1.25 to 1.5cm and their vertex space of 3.0 to 4.0cm inside of GTV. VMAT plans with multiple arcs were developed for SFRT. Four palliative fractionation regimens of 200cGy x 12 (EQD2 = 24Gy with a/b of 10Gy), 400cGy x 5 (23.3Gy), 600cGy x 3 (24Gy) and 800cGy x2 (24Gy) and four definitive regimens of 200cGy x 24 (EQD2 = 48Gy), 400cGy x 10 (46.7Gy), 600cGy x 6 (48Gy) and 800cGy x 4 (48Gy) were considered for radiotherapy to follow SFRT. Linear quadratic (LQ) model is compared with radio-immune (RI) response model in which the activation of cytotoxic T lymphocytes, tumor immune suppression capability and immunotherapy drugs can be considered. Tumor regrowth time (TRT, time to tumor regrowth to the original volume after treatment) from each model was compared as a measure of benefit achieved from the application of SFRT.

RESULTS

The average volume of GTVs in this study was 776cc (range 58-2944cc). Three different SFRT plans (2D GRID technique with conventional collimator, 2D GRID with step & shoot IMRT, and 3D Lattice) were developed for each patient but only Lattice plans were considered in this study since they produced comparable dose modulation inside the tumor but only Lattice significantly reduced skin and critical organ dose. Radio-immune response model always expects longer TRT than LQ model. For palliative regimens, TRT of RI model is longer than that of LQ model by 14.5±9.9, 15.1±10.6, 17.2±12.4, 17.5±12.8 days for each fractionation scheme. When Lattice plan of 15Gy is delivered before the palliative treatment, the difference becomes 25.9±15.3, 31.5±23.3, 36.7±27.6, 37.5±28.5 days. The benefit of SFRT from RI response is only about 10-20 days. Interestingly, RI response is inversely proportional to tumor volume. When curative dose is considered, the difference of TRT is drastically changed from 25.9±9.8, 460.7±285.8, 1180.8±985.7, 1512.0±1327.5 days to 20.7±4.4, 449.0±411.7, 1725.4±2171.0, 3517.7±4531.7 days. The benefit of SFRT from RI response appears larger for large tumor with hypo-fractionation in definitive regimens.

CONCLUSION

The benefit of SFRT is significant for large tumors with hypo fractionation in the definitive regimens when radio-immune response model is considered which is not apparent in LQ model. Radio-immune response model may help to guide the development of successful treatment scheme large tumor volumes.

Radio-Immune Response Model for Radiotherapy Plans with Heterogeneous Dose Distribution

PURPOSE/OBJECTIVE(S)

In order to model the immune response in tumor of the patients under radiotherapy for cancer. Characteristics of the numerical model and preliminary application are presented.

MATERIALS/METHODS

Immune response was modelled by 4 set of ordinary difference equations (ODE) as a function of biomedical variables including the amount of tumor antigen naturally released by tumor, the activation of cytotoxic T-lymphocytes (CTL) by radiation, immune suppression by tumor volume and the use of immunotherapy drugs. The effect of heterogeneous radiation dose distribution is also considered by hyperbolic tangent function to account for the immunogenic response of tissue under highly heterogeneous dose distribution intentionally modulated in spatially fractionated radiotherapy. Boundary behaviors of the model were investigated for tumors with different biomedical characteristics and under different treatment conditions. The developed model was applied to the tumor volume change in a mouse with 67NR tumors after radiation of 10 Gy to full or half volume of tumor and a clinical patient treated for sarcoma three times over 4 years.

RESULTS

Tumor growth is exponential at early phase, slow down over time with increasing immune response and eventually reaches an equilibrium condition (known as terminal tumor volume) for tumors with little to no immune suppression capability (ISC) even in the lack of radiation treatment. Breaking-through the equilibrium for tumor to grow exponentially happens when ISC is larger than the bifurcation threshold, analytically calculated from the proposed model. Tumor with ISC close to the bifurcation threshold can show complex growth behavior depending on the treatment condition and it should be carefully considered for the optimal treatment. Tumor volume change over 30 days period on mouse was modeled well with this model. Full dose irradiation reduced the tumor volume faster in the first 10 days but half volume irradiation reduced the tumor volume faster at later stage due to the improved immune response which cannot be modelled with traditional linear quadratic model. Tumor volume on a patient retreated three times over 4 years was also accurately estimated.

CONCLUSION

The proposed immune response model is capable to estimate tumor volume response under full or partial volume irradiation considering the complex immune characteristics of the tissue.

Trial in Progress: Adaptive RADiation Therapy with Concurrent Sacituzumab Govitecan (SG) for Bladder Preservation in Patients with MIBC (RAD-SG)

PURPOSE/OBJECTIVE(S)

A substantial proportion of patients with muscle invasive bladder cancer do not receive curative intent therapy, especially if unfit for or refuse radical cystectomy. Concurrent chemoradiation is an effective alternative to radical cystectomy, however systemic radio-sensitizing chemotherapy may have off target side effects. A Phase I study is accruing which will investigate the concurrent administration of a bladder cancer targeted antibody drug conjugate (Sacituzumab Govitecan) with radiotherapy.

MATERIALS/METHODS

This trial in progress is a Phase I study of Adaptive RADiation therapy with concurrent Sacituzumab Govitecan (SG) for bladder preservation in patients with muscle invasive bladder cancer (MIBC). Eligible patients will have localized muscle invasive bladder cancer (MIBC) confined to the bladder. The initial cohort is expected to accrue 20 patients. The primary endpoint is to establish the safety, tolerability, and feasibility of bladder preservation therapy treatment with concurrent SG and adaptive image-guided radiation therapy for patients with localized MIBC. The secondary endpoints are to determine the bladder intact event-free survival (BI-EFS) with concurrent SG and radiation therapy for MIBC and compare to historical controls with other concurrent chemoradiation regimens. BI-EFS is defined as the time from treatment to the first documented occurrence of residual/recurrent MIBC, nodal or distant metastases on imaging, radical cystectomy, or death from any cause. Sacituzumab Govitecan targets TROP-2, a surface protein expressed in urothelial cancers of the bladder. SG will be delivered IV, 10 mg/kg, 21-day cycles for 1 loading cycle prior to radiation and two subsequent cycles with concurrent adaptive radiotherapy over a period of 6 weeks (64 Gy). Correlative objectives (Supported by NCI/NIH U54) and will involve 1) elucidation of the genetic and microenvironmental mechanisms that drive efficacy and resistance to combined ADC plus radiation therapy and 2) characterization of tumor clonal dynamics, immune repertoire editing, and imaging changes following treatment with SG plus radiation.

RESULTS

To be determined.

CONCLUSION

To be determined.

Graph 'texture' features as novel metrics that can summarize complex biological graphs

Objective.Image texture features, such as those derived by Haralicket al, are a powerful metric for image classification and are used across fields including cancer research. Our aim is to demonstrate how analogous texture features can be derived for graphs and networks. We also aim to illustrate how these new metrics summarize graphs, may aid comparative graph studies, may help classify biological graphs, and might assist in detecting dysregulation in cancer.Approach.We generate the first analogies of image texture for graphs and networks. Co-occurrence matrices for graphs are generated by summing over all pairs of neighboring nodes in the graph. We generate metrics for fitness landscapes, gene co-expression and regulatory networks, and protein interaction networks. To assess metric sensitivity we varied discretization parameters and noise. To examine these metrics in the cancer context we compare metrics for both simulated and publicly available experimental gene expression and build random forest classifiers for cancer cell lineage.Main results.Our novel graph 'texture' features are shown to be informative of graph structure and node label distributions. The metrics are sensitive to discretization parameters and noise in node labels. We demonstrate that graph texture features vary across different biological graph topologies and node labelings. We show how our texture metrics can be used to classify cell line expression by lineage, demonstrating classifiers with 82% and 89% accuracy.Significance.New metrics provide opportunities for better comparative analyzes and new models for classification. Our texture features are novel second-order graph features for networks or graphs with ordered node labels. In the complex cancer informatics setting, evolutionary analyses and drug response prediction are two examples where new network science approaches like this may prove fruitful.

Small + Safe + Well: lessons learned from a Total Worker Health® randomized intervention to promote organizational change in small business

BACKGROUND

Leadership commitment to worker safety and health is one of the most important factors when organizations develop and implement a Total Worker Health® approach. We aimed to assess the effectiveness of a Total Worker Health ("TWH") leadership development program that targeted owners and other senior-level leadership positions on changing organizational and worker outcomes from baseline to one-year later.

METHODS

The Small + Safe + Well study included small businesses from a variety of industries in the state of Colorado, USA that were participating in Health Links™. We designed a randomized waitlisted control comparison design (RCT) to evaluate the added benefit of a TWH leadership development program. An employer assessment tool was used to assess TWH policies and programs, and an employee health and safety survey was used to assess safety leadership and health leadership practices, safety climate and health climate, safety behaviors and health behaviors, and well-being. We used a linear mixed model framework with random effects for business and employee to assess the impact of intervention on the outcomes of interest.

RESULTS

Thirty-six businesses (37% retention) and 250 employees (9% retention) met the RCT study inclusion criteria and were included in the analysis. Businesses improved their TWH policies and programs score from baseline to one-year later, regardless of leadership intervention group assignment. Neither intervention group demonstrated improvements in employee-reported outcomes.

CONCLUSIONS

This study sought to address a gap in the literature regarding small business senior leadership development for TWH. Our study demonstrates many of the challenges of conducting studies focused on organizational change in workplaces, specifically in small businesses. When designing TWH intervention studies, researchers should consider how to best engage small business leaders in interventions and implementations early on, as well as methods that are well matched to measuring primary and secondary outcomes longitudinally. Future research is needed to test the feasibility and sustainability of TWH interventions in small business.

TRIAL REGISTRATION

The trial was retrospectively registered with ClinicalTrials.gov ( ID U19OH011227 ).

Evaluation of a Total Worker Health® leadership program for small business leaders

Leaders play a critical role in the development and execution of Total Worker Health (TWH). Small businesses, in particular, can benefit from strong leadership support for TWH as the burden of work-related injury, illness and fatality, as well as poor health and well-being is high in this population. In the present study, we conducted a program evaluation of a TWH leadership development program for small business leaders using the RE-AIM framework. The goal of the program was to help change leaders' behaviors around health, safety and well-being practices following the theory of transformational leadership. Two leaders from each business participated in pre-training activities on their own, a 6-hour in-person training, and three months of access to virtual training transfer activities, including coaching and goal tracking. Our results suggest that the TWH leadership development program is effective at improving leaders' self-reported TWH leadership practices and that the in-person training was implemented successfully. However, leaders did not report improvements in their personal health and in fact reported increased levels of work stress after the program. We also observed some challenges when implementing our training transfer strategies. Our study suggests that leaders may benefit from attending TWH leadership trainings alongside other colleagues in their organization to facilitate a shared vision and goals for TWH in their organization. As a next step, it will be important to determine the program's effectiveness in changing business TWH policies and practices, employee perceptions of TWH and leadership, and employee health and safety outcomes.

Optimal post-selection inference for sparse signals: a nonparametric empirical Bayes approach

Many recently developed Bayesian methods focus on sparse signal detection. However, much less work has been done on the natural follow-up question: how does one make valid inferences for the magnitude of those signals after selection? Ordinary Bayesian credible intervals suffer from selection bias, as do ordinary frequentist confidence intervals. Existing Bayesian methods for correcting this bias produce credible intervals with poor frequentist properties. Further, existing frequentist approaches require sacrificing the benefits of shrinkage typical in Bayesian methods, resulting in confidence intervals that are needlessly wide. We address this gap by proposing a nonparametric empirical Bayes approach to constructing optimal selection-adjusted confidence sets. Our method produces confidence sets that are as short as possible on average, while both adjusting for selection and maintaining exact frequentist coverage uniformly over the parameter space. We demonstrate an important consistency property of our procedure: under mild conditions, it asymptotically converges to the results of an oracle-Bayes analysis in which the prior distribution of signal sizes is known exactly. Across a series of examples, the method is found to outperform existing frequentist techniques for post-selection inference, producing confidence sets that are notably shorter, but with the same coverage guarantee.

Investigating the role of hallucinatory experiences in the transition from suicidal thoughts to attempts

OBJECTIVE

Psychotic experiences, including auditory hallucinatory experiences (HEs), are strongly associated with both suicidal thoughts and behaviour. This study examined their role in the ideation-to-attempt transition in adolescents, including their direct and indirect effect via potential mediators.

METHOD

Participants were from an Australian prospective longitudinal cohort of 1669 adolescents (12-17 years); of which a subsample endorsing baseline suicidal ideation (n = 216) was the focus of most analyses. Suicidal thoughts and behaviours were measured using the Self-Harm Behaviour Questionnaire. The Diagnostic Interview Schedule for Children was used to assess auditory HEs. Potential mediators of interest were psychological distress and Interpersonal Theory of Suicide (IPTS) constructs.

RESULTS

Among adolescents reporting suicidal ideation at baseline (n = 216), 6.5% had attempted suicide during follow-up. The size of auditory HEs' univariate effect suggests a possible strong relationship with increased risk of incident suicide attempts (OR = 2.40; 95%CI = 0.76-7.56); however, there was inadequate statistical power to produce a precise estimate. When HEs were accompanied by distress there was a nine-fold increased risk of acting on suicidal thoughts. Distress was independently associated with risk of attempt transition (OR = 4.09), whereas IPTS constructs were poor explanatory variables in most models.

CONCLUSION

Adolescents with psychological distress and auditory HEs are at high risk of incident suicide attempts. Further investigations on the role of negative/distressing content of hallucinations in the ideation-to-attempt transition are warranted.

Highlights from occupational safety and health continuing education needs assessment

BACKGROUND

There is a lack of trained Occupational Safety and Health (OSH) professionals able to meet the current and future demand for such expertize in the United States. Many OSH professionals are required to perform duties, which are outside of their primary area of expertize; thus, expansion of continuing education (CE) may be necessary to properly train individuals for new OSH responsibilities.

METHODS

The National Institute for Occupational Safety and Health-funded Education and Research Centers collectively developed and distributed an internet-based survey to gauge the CE needs and interests of the OSH workforce.

RESULTS

A total of 2064 responses were received. The most common primary professions represented were safety (28%), occupational health nursing (18%), and industrial hygiene (12%). The majority of respondents (61%) reported that they perform work activities outside of those associated with their primary OSH profession. The CE offerings with the highest interest among respondents were related to safety. Other courses with high levels of interest included topics such as legal issues in OSH (88%), compliance (88%), risk management (85%), OSH management (83%), risk communication (83%), and communication in accident prevention (81%). Health and safety leadership (82%), health and safety culture (78%) and total worker health (74%) were also significant interests.

CONCLUSIONS

It is important to be responsive to the evolving needs of the OS&H community. Developing relevant courses will help ensure that OS&H professionals have access to the training they need to perform essential job functions and keep employees healthy and safe.

Smokin' hot: adolescent smoking and the risk of psychosis

OBJECTIVE

Daily smoking has been associated with a greater risk of psychosis. However, we are still lacking studies to adjust for baseline psychotic experiences and other substance use. We examined associations between daily smoking and psychosis risk in a 15-year follow-up while accounting for these covariates in a prospective sample (N = 6081) from the Northern Finland Birth Cohort 1986.

METHODS

Self-report questionnaires on psychotic experiences (PROD-screen), tobacco smoking and other substance use were completed when the cohort members were 15-16 years old. Tobacco smoking was categorized into three groups (non-smokers, 1-9 cigarettes and ≥10 cigarettes/day). Psychosis diagnoses were obtained from national registers until the age of 30 years.

RESULTS

Subjects in heaviest smoking category were at increased risk of subsequent psychosis (unadjusted HR = 3.15; 95% CI 1.94-5.13). When adjusted for baseline psychotic experiences the association persisted (HR = 2.87; 1.76-4.68) and remained significant even after adjustments for multiple known risk factors such as cannabis use, frequent alcohol use, other illicit substance use, parental substance abuse, and psychosis. Furthermore, number of smoked cigarettes increased psychosis risk in a dose-response manner (adjusted OR = 1.05; 1.01-1.08).

CONCLUSION

Heavy tobacco smoking in adolescence was associated with a greater risk for psychosis even after adjustment for confounders.

Why are psychotic experiences associated with self-injurious thoughts and behaviours? A systematic review and critical appraisal of potential confounding and mediating factors

Psychotic experiences (PEs), including hallucination- and delusion-like experiences, are robustly associated with self-injurious thoughts and behaviours (SITB) in the general population. However, it remains unclear as to why there is an association. The purpose of this systematic review was to elucidate the role of other factors that influence the association between PEs and SITB and, in doing so, highlight potential mechanisms underlying the relationship. A search of electronic international databases was undertaken, including PubMed, PsycINFO and EMBASE, and eligible studies were grouped according to seven confounder categories: sociodemographics, mental disorders, alcohol and substance use, environmental, psychological, intervention and family history/genetic factors. The systematic search strategy identified 41 publications reporting on 1 39 427 participants from 16 different countries. In the majority of studies, where adjustment for other variables occurred, the association between PEs and SITB persisted, suggesting PEs have an independent role. Common mental disorders, psychological distress and negative environmental exposures explained a substantial amount of the variance and therefore need to be considered as potential underlying mechanisms. There was high variability in the variables adjusted for in these studies, and so the question still remains as to whether the association between PEs and self-harm/suicidality can be attributed (fully or in part) to confounding and mediating factors or directly causal mechanisms. Regardless of causality, the now extensive literature reporting an association between these two clinical phenomena supports the broad usefulness of PEs as an indicator of risk for SITB.

Dopamine, psychosis and schizophrenia: the widening gap between basic and clinical neuroscience

The stagnation in drug development for schizophrenia highlights the need for better translation between basic and clinical research. Understanding the neurobiology of schizophrenia presents substantial challenges but a key feature continues to be the involvement of subcortical dopaminergic dysfunction in those with psychotic symptoms. Our contemporary knowledge regarding dopamine dysfunction has clarified where and when dopaminergic alterations may present in schizophrenia. For example, clinical studies have shown patients with schizophrenia show increased presynaptic dopamine function in the associative striatum, rather than the limbic striatum as previously presumed. Furthermore, subjects deemed at high risk of developing schizophrenia show similar presynaptic dopamine abnormalities in the associative striatum. Thus, our view of subcortical dopamine function in schizophrenia continues to evolve as we accommodate this newly acquired information. However, basic research in animal models has been slow to incorporate these clinical findings. For example, psychostimulant-induced locomotion, the commonly utilised phenotype for positive symptoms in rodents, is heavily associated with dopaminergic activation in the limbic striatum. This anatomical misalignment has brought into question how we assess positive symptoms in animal models and represents an opportunity for improved translation between basic and clinical research. The current review focuses on the role of subcortical dopamine dysfunction in psychosis and schizophrenia. We present and discuss alternative phenotypes that may provide a more translational approach to assess the neurobiology of positive symptoms in schizophrenia. Incorporation of recent clinical findings is essential if we are to develop meaningful translational animal models.

The association between adolescent psychopathology and subsequent physical activity in young adulthood: a 21-year birth cohort study

BACKGROUND

The beneficial effects of physical activity (PA) for both physical and mental wellbeing are well established. Given that adolescence presents a critical developmental period during which life-long patterns of PA become established, the exploration of the longitudinal impact of adolescent psychopathology on adult PA status is of interest.

METHODS

We analysed prospective data from 3663 young adults who participated in the Mater-University of Queensland Study of Pregnancy. Psychopathology was measured using the Youth Self-Report (YSR) at age 14. Participants' engagement in three types of PA (vigorous exercise, moderate exercise and walking) at age 21 were dichotomised into either 'none' or 'any'. For our main analysis, we examined the association between the YSR score and subsequent PA engagement using logistic regression. We also conducted sensitivity analyses of longitudinal associations between the YSR internalising and externalising symptoms score at age 14 and PA engagement at age 21.

RESULTS

We found no longitudinal association between the total YSR score at age 14 and PA engagement at age 21. In addition, there was no longitudinal association between the YSR internalising or externalising symptoms and PA engagement.

CONCLUSION

Our findings suggest that there is no longitudinal association between adolescent psychopathology and PA in young adulthood.

Diversity of knockdown resistance alleles in a single house fly population facilitates adaptation to pyrethroid insecticides

Insecticide use exerts a tremendous selection force on house fly populations, but the frequencies of the initial resistance mutations may not reach high levels if they have a significant fitness cost in the absence of insecticides. However, with the continued use of the same (or similar) insecticides, it is expected that new mutations (conferring equal or greater resistance, but less of a fitness cost) will evolve. Pyrethroid insecticides target the insect voltage sensitive sodium channel (VSSC) and have been widely used for control of house flies at animal production facilities for more than three decades. There are three Vssc mutations known that cause resistance to pyrethroids in house flies: knockdown resistance (kdr, L1014F), kdr-his (L1014H) and super-kdr (M918T + L1014F). Whether or not there are any new mutations in house fly populations has not been examined for decades. We collected house flies from a dairy in Kansas (USA) and selected this population for three generations. We discovered multiple new Vssc alleles, including two that give very high levels of resistance to most pyrethroids. The importance of these findings to understanding the evolution of insecticide resistance, designing appropriate resistance monitoring and management schemes, and the future of pyrethroids for house fly control are discussed.

Correlates of physical activity in people living with psychotic illness

OBJECTIVE

In the light of the high prevalence of physical comorbidities in people with psychotic illness, there is a need to explore modifiable risk factors that may contribute to this disease burden. The benefits of physical activity to both physical and mental health have been well established. We aimed to examine the prevalence and correlates of physical activity in a national sample of adults living with psychotic illness.

METHODS

Physical activity was assessed in 1801 people using the International Physical Activity Questionnaire. Participants were dichotomised into low and moderate-high physical activity groups and associations between physical activity and a range of sociodemographic, clinical and physical comorbidity variables were examined using logistic regression.

RESULTS

More than half the participants were categorised in the moderate-high physical activity group with nearly half of the sample engaged in physical activity every day. There were significant associations between low physical activity and older age, unemployment, educational non-participation, antipsychotic medication use, social dysfunction, self-reported loneliness and obesity. However, there was no significant association between physical activity and sex, psychosis type, illness duration, physical comorbidity or negative symptoms.

CONCLUSION

The findings from this study may inform future interventions designed to increase physical activity in people with psychotic illness.

Overcoming super-knock down resistance (super-kdr) mediated resistance: multi-halogenated benzyl pyrethroids are more toxic to super-kdr than kdr house flies

Target site insensitivity because of mutations in the voltage-sensitive sodium channel gene (Vssc) is a major mechanism of resistance to pyrethroid insecticides in the house fly, Musca domestica. There are three known Vssc alleles that confer resistance to pyrethroids in the house fly: knock down resistance (kdr; L1014F), super-kdr (M918T + L1014F) and kdr-his (L1014H), but there has been no side-by-side comparison of the resistance levels that they confer. We compared the levels of resistance conferred by the three Vssc alleles in congenic strains to 19 structurally diverse pyrethroids, and compared the full-length Vssc cDNA sequences from each strain. Generally, the levels of resistance conferred were kdr-his < kdr < super-kdr. However, there was significant variation in this pattern, especially for super-kdr, for which both high and low resistance ratios were observed for several pyrethroids. We also examined the levels of resistance in heterozygotes. Resistance in each of the hybrids was generally inherited as an incompletely recessive trait, except for the kdr-his/kdr hybrids, which showed incompletely to completely dominant resistance (ie had resistance levels comparable to kdr homozygotes). The importance of these results to understanding the frequencies of these resistance alleles in natural populations, the evolution of insecticide resistance and resistance management strategies are discussed.

Abstract P3-12-03: Utilizing the genomically adjusted dose (GAD) to personalize radiotherapy in adjuvant breast cancer management

Background: We have previously validated a multi-gene model of tumor radiosensitivity (RSI) with validation in multiple independent cohorts including breast, rectal, esophageal, head and neck, glioblastoma, and prostate malignancies. Utilizing the linear quadratic model and RSI, we derived an expression for the genomically adjusted dose (GAD) to model radiation dose effect for individual patients.

Methods: As RSI models the surviving fraction of cells at 2 Gy (SF2), we are able to derive a patient specific alpha. These terms were used in the linear quadratic model to calculate a GAD to model radiation effect and its association with local control. A higher GAD implies a higher predicted radiation therapy effect. Clinical and array-based gene expression were obtained from 75 ER negative patients from the Netherlands Cancer Institute (NKI) and the Institut Curie treated with breast conservation therapy.

Results: Median follow-up for all patients was 10 years with a median age of 42 years (range: 23-50 years). Adjuvant radiation dose to the whole breast was 50 Gy (range: 45-55 Gy). When assessing local recurrence on multivariate analysis, we found GAD to be a significant predictor of local recurrence when dichotomized at the median (GAD-low vs GAD-high Hazard Ratio (HR) 4.5; 95% CI 1.7-13.5; p=0.0031). GAD was also significant per unit change (HR 0.91; 95% CI 0.83-0.99; p=0.021). We then modeled GAD for an escalated dose up to 60 Gy and found an additional 48% of GAD-low patients could achieve a GAD-high with dose escalation.

Conclusions: We found GAD to be significantly correlated with local control following breast conservation therapy. Modeling dose escalation with GAD, we identified a select population of patients whom we hypothesize may benefit from genomically guided increased dose in the adjuvant setting. This population may represent a cohort for future clinical trial enrollment.

Citation Format: Ahmed KA, Venkat PS, Scott JG, Diaz RJ, Fulp WJ, Torres-Roca JF. Utilizing the genomically adjusted dose (GAD) to personalize radiotherapy in adjuvant breast cancer management. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-03.

Abstract P3-12-04: The genomically adjusted radiation dose (GAD) and its association with distant metastases in breast cancer: A feasible approach to precision medicine in radiation oncology

Background: Clinical validation studies in over 2,200 patients across 8 different disease sites, including breast cancer, have shown the radiosensitivity index (RSI), a gene expression signature, predicts outcomes in patients treated with radiation. We hypothesize that an approach to personalize radiation dose could be developed by integrating RSI into the linear quadratic model of dose and fractionation.

Methods: Utilizing the linear quadratic model and RSI, we derived an expression for the genomically adjusted dose (GAD) to model radiation dose effect for individual patients. A higher GAD implies a higher predicted radiation therapy effect. GAD was evaluated as a predictor of clinical outcome in two independent datasets of breast cancer patients treated with surgery and radiation. The association between GAD and distant-metastasis free survival (DMFS) and relapse-free survival (RFS) using univariate (UVA) and multivariate (MVA) Cox proportional hazard models was assessed. Clinical and array-based gene expression were obtained from two independent, previously described cohorts from the Karolinska Institutet and Erasmus University Medical Center.

Results: Full radiation treatment details were available for 263 patients in the Erasmus dataset, median follow-up 60 months. GAD-low patients (&lt;75% GAD distribution) were found to have decreased DMFS when compared to GAD-high patients (≥25% GAD distribution) (Hazard Ratio (HR) = 2.31 (95% CI 1.25, 4.25), p=0.006). On MVA, GAD was an independent predictor of DMFS for the whole cohort (HR= 2.11 (1.13, 3.94), p=0.02). When the analysis was restricted to the ER positive cohort, GAD was an independent predictor of outcome both as a continuous (HR=0.977, (0.955, 1.0), p = 0.049) and as a dichotomous variable (HR = 3.42, (1.53, 7.67), p=0.003). These results were independently confirmed in the second Karolinska dataset. The 5 year RFS was 95% for GAD-high patients and 76% in GAD-low patients (p=0.027) and GAD was a significant predictor on MVA for RFS (HR =7.42, (1.41, 137.6), p=0.014). In the Karolinska cohort, we estimate a significant proportion of GAD-low patients (59%) would achieve GAD-high with dose escalation up to 70 Gy.

Conclusions: In this study, we develop and validate GAD, a novel and patient-specific measure of radiation dose effect. Importantly, GAD is a clinically actionable metric by adjusting radiation dose. We propose that GAD based radiation dosing is a feasible approach to precision medicine in breast radiation oncology.

Citation Format: Ahmed KA, Scott JG, Diaz RJ, Fulp WJ, Torres-Roca JF. The genomically adjusted radiation dose (GAD) and its association with distant metastases in breast cancer: A feasible approach to precision medicine in radiation oncology. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-04.

The epidemiology and global burden of autism spectrum disorders

BACKGROUND

Autism spectrum disorders (ASDs) are persistent disabling neurodevelopmental disorders clinically evident from early childhood. For the first time, the burden of ASDs has been estimated for the Global Burden of Disease Study 2010 (GBD 2010). The aims of this study were to develop global and regional prevalence models and estimate the global burden of disease of ASDs.

METHOD

A systematic review was conducted for epidemiological data (prevalence, incidence, remission and mortality risk) of autistic disorder and other ASDs. Data were pooled using a Bayesian meta-regression approach while adjusting for between-study variance to derive prevalence models. Burden was calculated in terms of years lived with disability (YLDs) and disability-adjusted life-years (DALYs), which are reported here by world region for 1990 and 2010.

RESULTS

In 2010 there were an estimated 52 million cases of ASDs, equating to a prevalence of 7.6 per 1000 or one in 132 persons. After accounting for methodological variations, there was no clear evidence of a change in prevalence for autistic disorder or other ASDs between 1990 and 2010. Worldwide, there was little regional variation in the prevalence of ASDs. Globally, autistic disorders accounted for more than 58 DALYs per 100 000 population and other ASDs accounted for 53 DALYs per 100 000.

CONCLUSIONS

ASDs account for substantial health loss across the lifespan. Understanding the burden of ASDs is essential for effective policy making. An accurate epidemiological description of ASDs is needed to inform public health policy and to plan for education, housing and financial support services.

Psychotic experiences and psychological distress predict contemporaneous and future non-suicidal self-injury and suicide attempts in a sample of Australian school-based adolescents

BACKGROUND

Recent cross-sectional studies have shown psychotic experiences (PEs) are associated with suicidal ideation and behaviours. We aimed to examine associations between psychotic experiences (including persistent PE), and contemporaneous and incident non-suicidal self-injury (NSSI) and suicide attempts.

METHOD

Participants were from an Australian longitudinal cohort of 1896 adolescents (12-17 years). NSSI and suicide attempts were measured using the Self-Harm Behaviour Questionnaire. Items from the Diagnostic Interview Schedule for Children were used to assess psychotic experiences, and the General Health Questionnaire-12 measured psychological distress.

RESULTS

Adolescents both psychologically distressed and endorsing psychotic experiences had increased odds of contemporaneous and incident NSSI and attempted suicide. Psychotic experiences alone did not predict future risk. Persistent psychotic experiences were associated with increased risk of NSSI and suicide attempts.

CONCLUSIONS

Psychological distress with accompanying psychotic experiences and persistent psychotic experiences are important predictors of NSSI and suicide attempts. Screening these phenotypes in adolescents will assist in discerning those adolescents most at risk, providing opportunities for targeted suicide prevention strategies.

The heritability of delusional-like experiences

OBJECTIVE

Delusional-like experiences (DLE) are common in the general community and are associated with a family history of mental illness. The aim of this study was to estimate the heritability of DLE.

METHOD

The Peter's Delusional Inventory (PDI) was administered to a population-based cohort of mothers (n = 2861, aged 35-67 years) and their adult offspring (n = 3079, aged 18-23 years). Heritability of DLE was estimated from the sum scores of the 21 item PDI under the assumption that the covariance between mother-offspring scores is attributable to shared additive genetic factors.

RESULTS

The means (medians and standard deviations) for the total PDI scores for the mothers and their offspring were 3.6 (3.0, 3.0) and 5.0 (4.0, 3.5), respectively. The Pearson correlation coefficient between mother and offspring PDI scores was 0.17 (P < 0.001). The heritability was estimated to be 0.35 (standard error 0.04).

CONCLUSION

Heritable factors contribute to over a third of the variance of PDI scores in this population. In light of the association between a family history of a wide range of mental disorders and DLE, these experiences may represent a useful quantitative endophenotype for genetic studies of common mental disorders in population settings.

Investigating prostate cancer tumour-stroma interactions: clinical and biological insights from an evolutionary game

BACKGROUND

Tumours are made up of a mixed population of different types of cells that include normal structures as well as ones associated with the malignancy, and there are multiple interactions between the malignant cells and the local microenvironment. These intercellular interactions, modulated by the microenvironment, effect tumour progression and represent a largely under-appreciated therapeutic target. We use observations of primary tumour biology from prostate cancer to extrapolate a mathematical model. Specifically, it has been observed that in prostate cancer three disparate cellular outcomes predominate: (i) the tumour remains well differentiated and clinically indolent--in this case the local stromal cells may act to restrain the growth of the cancer; (ii) early in its genesis the tumour acquires a highly malignant phenotype, growing rapidly and displacing the original stromal population (often referred to as small cell prostate cancer)--these less common aggressive tumours are relatively independent of the local microenvironment and (iii) the tumour co-opts the local stroma--taking on a classic stromagenic phenotype where interactions with the local microenvironment are critical to the cancer growth.

METHODS

We present an evolutionary game theoretical construct that models the influence of tumour-stroma interactions in driving these outcomes. We consider three characteristic and distinct cellular populations: stromal cells, tumour cells that are self-reliant in terms of microenvironmental factors and tumour cells that depend on the environment for resources, but can also co-opt stroma.

RESULTS

Using evolutionary game theory we explore a number of different scenarios that elucidate the impact of tumour-stromal interactions on the dynamics of prostate cancer growth and progression, and how different treatments in the metastatic setting can affect different types of tumours.

CONCLUSION

The tumour microenvironment has a crucial role in selecting the traits of the tumour cells that will determine prostate cancer progression. Equally important treatments like hormone therapy affect the selection of these cancer phenotypes making it very important to understand how they impact prostate cancer's somatic evolution.

Socio-economic disadvantage and delusional-like experiences: a nationwide population-based study

PURPOSE

Delusional-like experiences (DLE) have been associated with low income, suggesting that more broadly defined socio-economic disadvantage may be associated with these experiences. We had the opportunity to explore the association between DLE and both individual- and area-level measures of socio-economic disadvantage.

METHOD

Subjects were drawn from the Australian National Survey of Mental Health and Wellbeing 2007. The Composite International Diagnostic Interview was used to identify DLE, common psychiatric disorders, and physical disorders. Individual-level and area-level socio-economic disadvantage measures were available based on variables including income, educational attainment, employment status, and housing. We examined the relationship between the variables of interest using logistic regression, adjusting for potential confounding factors.

RESULTS

Of the 8773 subjects, 8.4% (n=776) positively endorsed one or more DLE. DLE screen items were more likely to be endorsed by those who were (a) younger, (b) never married, or widowed, separated or divorced status, (c) migrants, or (d) living in rented houses. There were significant associations between socio-economic disadvantage and increased DLE endorsement, and this was found for both individual-level and area-level measures of socio-economic disadvantage. In general, the associations remained significant after adjusting for a range of potential confounding factors and in planned sensitivity analyses.

CONCLUSIONS

DLE are associated with socio-economic disadvantage in the general population. We speculate that the link between socio-economic disadvantage and DLE may be mediated by psychosocial stress and general psychological distress.

Hormone receptor-like in 96 and Broad-Complex modulate phenobarbital induced transcription of cytochrome P450 CYP6D1 in Drosophila S2 cells

Phenobarbital (PB) is a prototypical inducer for studies of xenobiotic responses in animals. In mammals, the nuclear receptors constitutive androstane receptor (CAR) and pregnane X receptor (PXR) have been identified as key transcription factors regulating PB induced transcription of xenobiotic responsive genes. In insects, much less is known about the transcription factors involved in regulating PB induced transcription, although CAR and PXR have a single orthologue hormone receptor-like in 96 (HR96) in Drosophila melanogaster. Using dual luciferase reporter assays in Drosophila Schneider (S2) cells, constructs containing variable lengths of the promoter of the PB inducible cytochrome P450 CYP6D1 were evaluated in the presence and absence of PB. The promoter region between -330 and -280 (relative to the position of transcription start site, +1) was found to be critical for PB induction. Putative binding sites for Drosophila Broad-Complex (BR-C) and deformed (Dfd) were identified within this promoter region using TFsearch. RNA interference (RNAi) treatment of S2 cells in conjunction with CYP6D1 promoter assays showed that suppression of Drosophila HR96 and BR-C transcription in S2 cells resulted in a significant decrease and increase, respectively, of PB induction. Effects of HR96 and BR-C in mediating PB induction were PB specific and PB dependent. This represents new functional evidence that Drosophila HR96 and BR-C can act as an activator and repressor, respectively, in regulating PB induced transcription in insects.

Use of isogenic strains indicates CYP9M10 is linked to permethrin resistance in Culex pipiens quinquefasciatus

Previous studies on a strain of Culex pipiens quinquefasciatus from Saudi Arabia indicated permethrin resistance was a result of cytochrome P450 mediated detoxification and kdr. The P450 detoxification was found to be larval specific and associated with a fitness cost in certain environments. The P450 responsible for resistance (and the fitness cost) has not been identified, but recently two candidate P450s (CYP4H34 and CYP9M10) have been found. We measured cytochrome P450 and cytochrome b₅ content as well as the expression levels of CYP4H34 and CYP9M10 in a susceptible (SLAB) and two isogenic strains (isolated by repeated backcrossing and selection) of mosquito (ISOP450 and ISOJPAL) resistant to permethrin. Cytochrome P450 protein levels of the resistant strains were significantly higher (1.5-fold) than SLAB, but were not significantly different from one another. Expression of CYP4H34 in the larvae and adults of the resistant (ISOP450 and ISOJPAL) and susceptible (SLAB) strains were not statistically different. CYP9M10 was found to be significantly over-expressed in larvae of both permethrin-resistant isogenic strains (1800-fold in ISOP450 and 870-fold in ISOJPAL) when compared to SLAB. Partial sequence analysis of CYP9M10 revealed eight polymorphic sites that distinguished the susceptible allele from the resistant allele. We conclude that CYP9M10 is linked to permethrin resistance in these strains of C. p. quinquefasciatus, and is likely to be the P450 gene responsible for resistance in these strains.

Differences in development, glycogen, and lipid content associated with cytochrome P450-mediated permethrin resistance in Culex pipiens quinquefasciatus (Diptera: Culicidae)

Insecticide resistance in populations of mosquitoes is an escalating problem that can directly affect disease prevalence. Determining the fitness associated with an insecticide resistance mechanism (allele) will provide for greater understanding of the evolution of resistance, and help inform effective vector management programs. Previously, a population cage experiment in which the alleles of two highly related strains of Culex pipiens quinquefasciatus (Say) SLAB (susceptible) and ISOP450 (permethrin resistant because of cytochrome P450-mediated detoxification) were placed in direct competition in the absence of insecticide revealed that the P450 resistance allele frequency decreased over time. In the current study, SLAB and ISOP450 development, mortality and energetic resources derived from glycogen, other sugars and lipids were measured to identify biological parameters that might explain the previously observed fitness cost. SLAB exhibited shorter egg-to-adult female development time and larger body size when reared in groups when compared with ISOP450. ISOP450 female adults provided 20% sugar water lived longer than 20% sugar water fed females of the SLAB strain. No significant differences in larval development time, larval mortality, pupal stage duration time, pupal mortality, longevity of male and female adults provided with distilled water and males provided sugar water were found between the strains. The caloric content from glycogen and lipids were significantly higher in SLAB relative to ISOP450 in adults. The slower female emergence time and smaller body size when reared in groups combined with lower energy reserves (glycogen and lipids) associated with the resistance allele (in ISOP450) are likely fitness costs associated with the resistance allele of P450-mediated detoxification.

Transcriptional diversity and allelic variation in nicotinic acetylcholine receptor subunits of the red flour beetle, Tribolium castaneum

Sequence analysis of 168 cDNA clones encoding 12 nicotinic acetylcholine receptor subunits, Tcasalpha1-Tcasalpha11 and Tcasbeta1, from the red flour beetle, Tribolium castaneum, revealed extensive post-transcriptional modification and multiple alleles. The greatest diversity was found for Tcasa6, where 18 unique transcripts, as a result of alternative and optional exon usage, were seen. A novel alternative exon 8d was found in one Tcasalpha6 transcript. Tcasalpha5 transcripts did not contain previously reported exons 8-10. Six subunits had transcripts that contained unspliced introns, which introduced premature stop codons. Intron 3' splice site variants were seen at six intron boundaries across five subunits. A-to-I RNA editing was seen only in Tcasalpha6. Alleles were found for all subunit genes, except Tcasalpha1 and Tcasalpha10. Transcriptional and allelic diversity are discussed with respect to receptor function and potential interactions with insecticides.

A case for sequencing the genome of Musca domestica (Diptera: Muscidae)

House flies are carriers of >100 devastating diseases that have severe consequences for human and animal health. Despite the fact that it is a passive vector, a key bottleneck to progress in controlling the human diseases transmitted by house flies is lack of knowledge of the basic molecular biology of this species. Sequencing of the house fly genome will provide important inroads to the discovery of novel target sites for house fly control, understanding of the house fly immune response, rapid elucidation of insecticide resistance genes, and understanding of numerous aspects of the basic biology of this insect pest. The ability of the house fly to prosper in a remarkably septic environment motivates analysis of its innate immune system. Its polymorphic sex determination system, with male-determining factors on either the autosomes or the Y chromosome, is ripe for a genomic analysis. Sequencing of the house fly genome would allow the first opportunity to study the interactions between a pest insect and its parasitoid (Nasonia vitripennis) at the whole genome level. In addition, the house fly is well placed phylogenetically to leverage analysis of the multiple Dipteran genomes that have been sequenced (including several mosquito and Drosophila species). The community of researchers investigating Musca domestica are well prepared and highly motivated to apply genomic analyses to their widely varied research programs.

Multiplicative interaction between the two major mechanisms of permethrin resistance, kdr and cytochrome P450-monooxygenase detoxification, in mosquitoes

Epistasis is the nonadditive interaction between different loci which contribute to a phenotype. Epistasis between independent loci conferring insecticide resistance is important to investigate as this phenomenon can shape the rate that resistance evolves and can dictate the level of resistance in the field. The evolution of insecticide resistance in mosquitoes is a growing and world-wide problem. The two major mechanisms that confer resistance to permethrin in Culex mosquitoes are target site insensitivity (i.e. kdr) and enhanced detoxification by cytochrome P450 monooxygenases. Using three strains of mosquitoes, and crosses between these strains, we assessed the relative contribution of the two independent loci conferring permethrin resistance, individually and when present together. We found that for all genotype combinations tested, Culex pipiens quinquefasciatus exhibited multiplicative interactions between kdr and P450 detoxification, whether the resistance alleles were homozygous or heterozygous. These results provide a basis for further analysis of the evolution and maintenance of insecticide resistance in mosquitoes.

A high frequency of male determining factors in male Musca domestica (Diptera: Muscidae) from Ipswich, Australia

The male sex determining factor (M) in the house fly is linked to the Y chromosome in the ancestral condition, but can also be linked to another chromosome (I-V or X). However, descriptions of the linkage and frequency of M factors in different populations throughout the world are vastly incomplete. We collected house flies from a dairy in Ipswich, Australia, and determined that M was linked to chromosomes II, III, IV, and Y. Most males (69.8%) were homozygous for M on autosome II and/or III, and 92.3% of the males had multiple M factors. In all, there were 13 different male genotypes found. The high frequency of M, the presence of M on four different linkage groups, and the large number of male genotypes found in this population make it unique relative to other populations of house flies that have been examined.

The nicotinic acetylcholine receptor subunits Mdalpha5 and Mdbeta3 on autosome 1 of Musca domestica are not involved in spinosad resistance

Spinosad is a relatively new insecticide that exerts its toxic action via nicotinic acetylcholine receptors (nAChRs). Spinosad resistance in house flies appears to be due to an altered target site. To evaluate the molecular basis of spinosad resistance, two nAChR subunit genes, Mdalpha5 and Mdbeta3 were cloned and characterized from an insecticide-susceptible (aabys) and spinosad resistant (rspin) strain of the house fly, Musca domestica. The Mdalpha5 and Mdbeta3 cDNAs encode proteins of 781 and 432 amino acid residues, respectively. Phylogenetic analysis with insect nAChR subunits suggested that Mdalpha5 and Mdbeta3 are most closely related to Dalpha5 and Dbeta3 of Drosophila melanogaster, respectively. Mdbeta3 is intronless, which is unique among all previously described nAChR genes. A-to-I RNA editing was found at 13 sites in Mdalpha5, eleven of which resulted in amino acid substitutions. No evidence for A-to-I RNA editing was found in Mdbeta3. Mdalpha5 expression, quantified by real time PCR, was 340- and 23-fold higher in the head and thorax than in the abdomen. Mdbeta3 expression was more uniform, being only 2.4-fold higher in the head and 1.4-fold lower in the thorax, compared to the abdomen. There was no difference in the expression of Mdalpha5 and Mdbeta3 between the aabys and rspin strains. Although Mdalpha5 and Mdbeta3 both map to the same chromosome as spinosad resistance, there were no unique features of either gene in rspin, relative to the aabys strain. This suggests neither Mdalpha5 nor Mdbeta3 is responsible for spinosad resistance in house flies.

The nicotinic acetylcholine receptor subunit Mdalpha6 from Musca domestica is diversified via post-transcriptional modification

Recent studies showed that deletion of a nicotinic acetylcholine receptor (nAChR) subunit gene, Dalpha6 in Drosophila melanogaster results in a strain that is resistant to spinosad, indicating that Dalpha6 is important for the toxic action of this insecticide. To determine if spinosad resistance in house flies was due to a mutation(s) of Mdalpha6 (the orthologue of Dalpha6 from house flies), cDNAs were cloned and characterized from an insecticide-susceptible and a spinosad-resistant strain of the house fly, Musca domestica. The cDNAs contain a 1470-bp open reading frame encoding 490 amino acid residues, 415-bp 5' untranslated region (UTR) and a polymorphic 3'-UTR of approximately 371 bp. The predicted mature protein possesses 468 amino acid residues, has the typical features of a nAChR alpha subunit and is 97% identical to Dalpha6. Quantitative real-time PCR analysis revealed that Mdalpha6 was expressed in the head and the thorax at 1300- and 26-fold higher levels, respectively, than in the abdomen. There was no difference in the expression level of Mdalpha6 between spinosad-resistant and susceptible strains. Ten isoforms arising from alternative splicing were characterized, with isoform II being most common. A-to-I RNA editing was examined and found at 12 sites: editing at 11 of these sites resulted in an amino acid substitution. Mdalpha6 is linked to autosome 1 (spinosad resistance was previously shown to be linked to autosome 1). Single nucleotide polymorphisms, alternative splicing, mRNA levels and A-to-I RNA editing were compared between head and thorax and between insecticide-susceptible and spinosad-resistant strains. These comparisons indicate that Mdalpha6 is not responsible for spinosad resistance in house flies.

Use of quantitative real-time polymerase chain reaction to estimate the size of the house-fly Musca domestica genome

House-flies, Musca domestica, are carriers of more than 100 devastating diseases that have severe consequences for human and animal health. A key bottleneck to progress in controlling the devastating human diseases transmitted by house-flies is lack of knowledge of the basic molecular biology of this species. However, before sequencing of the house-fly genome can be seriously considered it is important to know the size of the genome. In this paper, we used quantitative real-time polymerase chain reaction to calculate genome size of the house-fly in side-by-side experiments with Drosophila melanogaster (known genome size of 180 Mb). Our results indicate the size of the house-fly genome is 295 +/- 10 Mb and that of D. melanogaster is 184 Mb. Thus, the house-fly genome is only about 1.6-fold larger than the genome of D. melanogaster. This indicates that the size of the house-fly genome makes it an excellent candidate for whole genome sequencing and that quantitative real-time polymerase chain reaction is an accurate method for the estimation of the size of insect genomes.

Frequencies of the pyrethroid resistance alleles of Vssc1 and CYP6D1 in house flies from the eastern United States

House flies were collected from four dairies in Maine, New York, North Carolina, and Florida, where high levels of resistance to permethrin have been documented. Regions of two genes, CYP6D1 and Vssc1, having alleles that confer resistance to permethrin (and other pyrethroids) were analysed from individuals at each collection site. The combinations of resistance alleles for Vssc1 and CYP6D1 were highly variable between each state. The resistance allele CYP6D1v1 was found at a high frequency (0.63-0.91) at all sites. Individuals homozygous susceptible for CYP6D1 were very rare and detected only at the dairy in Maine. In addition to the typical Vssc1 mutation responsible for resistance, kdr (L1014F), we also identified individuals with a L1014H mutation. Although house flies homozygous for the L1014H mutation had a lower level of resistance to permethrin, compared to L1014F, the H1014 resistance allele was frequently detected. No individuals with the super-kdr allele (M918T + L1014F) were detected from the field collections. The intron 3 bp downstream of the kdr mutation was found to be extremely variable, providing an opportunity to reconstruct a phylogeny of Vssc1 alleles. Based on this analysis it appears the kdr-his mutation had multiple evolutionary origins, but that the kdr mutation may have had a single origin. The impacts of these findings on resistance management are discussed.

Increased HVA detected on organic acid analysis in a patient with Costello syndrome

Urine organic acid analysis is routinely performed to investigate inborn errors of metabolism; however, interpretation can be difficult owing to the detection of compounds derived from other disease states or from nonpathological causes. We describe the finding of elevated homovanillc acid (HVA) on urine organic acid analysis which was not associated with medication or a neuroendocrine tumour but with Costello syndrome.

Botanical insecticides for controlling agricultural pests: piperamides and the Colorado Potato Beetle Leptinotarsa decemlineata say (Coleoptera: Chrysomelidae)

The efficacy of extracts from two Piperaceae species, Piper nigrum L. and P. tuberculatum Jacq. were evaluated using larvae and adults of the Colorado Potato Beetle Leptinotarsa decemlineata (Say). Young larvae and neonates were the most susceptible; a 24-h LD(50) of 0.064% extract of P. tuberculatum was determined for 4-day-old larvae, while 0.05% extract of P. nigrum reduced larval survival up to 70% within one week after treatment of potato Solanum tuberosum L. (Solanaceae) plants. When an insecticide resistant strain of L. decemlineata larvae was tested with the P. tuberculatum extract, there was less than a 2-fold tolerance ratio compared to the 22-fold tolerance ratio to cypermethrin, a pyrethroid. Older larvae, pre-pupal stage and adults, were less sensitive to the P. nigrum extracts; the 24-h LD(50) was 0.5% (95% C.I. = 0.36, 0.65). However, the same concentration was equally effective under field conditions. In the greenhouse, P. nigrum at 0.5% was as effective at reducing adult L. decemlineata feeding as combinations with 2 separate botanical mixtures, garlic and lemon grass oil. Under field conditions, the residual activity of the P. nigrum extracts was less than 3 h. When adult L. decemlineata were placed on treated plants exposed to full sunlight for 0, 1.5, and 3 h, leaf damage progressively increased as the main active compound, piperine, was found to degrade by 80% after 3 h. An in vitro polysubstrate monoxygenase (PSMO) enzyme assay, using the substrate methoxyresorufin O-demethylation (MROD), determined that the principal P. nigrum active compound, piperine, is responsible for inhibition of that specific enzyme. The results suggest that Piper extracts could be used effectively as contact botanical insect control agents to protect potato plants from developing L. decemlineata larvae at concentrations less than 0.1%. There is also potential for Piper extracts to control insecticide resistant populations in conjunction with other integrated pest management (IPM) strategies used in conventional and organic agriculture.

The house fly aliesterase gene (MdalphaE7) is not associated with insecticide resistance or P450 expression in three strains of house fly

It was recently proposed that a mutation (G137D) in the MdalphaE7 gene was responsible for increasing transcription of a P450 (CYP6A1) resulting in resistance to diazinon. To examine if MdalphaE7 had a role in resistance in other strains we sequenced a fragment (approximately 700 bp) of the MdalphaE7 gene from individual flies of two insecticide susceptible and three insecticide resistant (due to increased monooxygenase-mediated detoxification) strains. Five unique alleles were discovered. While all of the susceptible strains had Gly137, so did the resistant LPR and NG98 strains. Of the two alleles in the YPER strain one had the G137D substitution and the other did not. Based on the lack of correlation between the presence of the 'mutant' MdalphaE7 and resistance (or P450 levels), we conclude that the G137D mutation in MdalphaE7 is not involved in transcriptional control of the P450s involved in resistance in the LPR, NG98 or YPER strains. The relationship between MdalphaE7 alleles and insecticide resistance is discussed in light of these findings.

Expression and regulation of CYP6D3 in the house fly, Musca domestica (L.)

Recently, a new cytochrome P450 gene, CYP6D3, was identified from house fly. CYP6D3 was found upstream of a related gene (CYP6D1) on autosome 1. CYP6D3 cDNA sequences were obtained and compared from insecticide resistant (LPR) and susceptible (CS and Edinburgh) strains. Although each strain had a different CYP6D3 allele, the deduced amino acid sequences revealed no consistent differences between the susceptible and resistant strains. There was approximately 12-fold more CYP6D3 mRNA detected in adult LPR flies compared to CS, and the elevated level of expression in LPR was not due to gene amplification. Northern blots indicate expression of CYP6D3 mRNA is developmentally regulated with no expression in eggs, yet it is readily detectable in larvae as well as male and female adults. Phenobarbital is a well studied inducer of P450s in insects and it induced expression of CYP6D3 mRNA in both the CS (16-fold) and LPR (1.6 fold) strains. The CYP6D3 5' flanking regions were sequenced from the resistant and susceptible strains. Possible regulatory sequences within this region are discussed.

Cytochromes P450 of insects: the tip of the iceberg

The cytochrome P450-dependent monooxygenases are an extremely important metabolic system involved in the metabolism of endogenous compounds and xenobiotics. Collectively, P450 monooxygenases can metabolize numerous substrates and carry out multiple oxidative reactions. The large number of substrates metabolized is due to the plethora of P450 isoforms and to the broad substrate specificity of some isoforms. Monooxygenases of insects have several functional roles, including growth, development, feeding and protection against xenobiotics, including resistance to pesticides and tolerance to plant toxins. This review begins with background information about P450s and their evolution, followed by a discussion of the extraordinary diversity of insect P450s. Given the enormous interest in studying individual P450s, we then provide a synopsis of the different methods that have been used in their isolation and the substrates that are known to be metabolized. We conclude by summarizing the lessons we have learned from the study of individual insect P450s, including their roles in insecticide resistance, plant-insect interactions and insect physiology. However, these studies are just the 'tip of the iceberg'. Our knowledge continues to expand at a rapid pace, suggesting that the next decade will outpace the last in terms of improving our understanding of the cytochromes P450 of insects.

Antibiotic use in acute respiratory infections and the ways patients pressure physicians for a prescription

OBJECTIVE

We identified those aspects of physician-patient communication that influence physicians to prescribe antibiotics for respiratory infections.

STUDY DESIGN

A multimethod comparative case study was performed including descriptive field notes of outpatient visits.

POPULATION

We included patients (children and adults) and clinicians in 18 purposefully selected family practices in a midwestern state. A total of 298 outpatient visits for acute respiratory tract (ART) infections were selected for analysis from more than 1600 encounters observed.

OUTCOMES MEASURED

Unnecessary antibiotic use and patterns of physician-patient communication were measured.

RESULTS

Antibiotics were prescribed in 68% of the ART infection visits, and of those, 79% were determined to be unnecessary according to Centers for Disease Control and Prevention guidelines. Patients were observed to pressure physicians for medication. The types of patterns identified were direct request, candidate diagnosis (a diagnosis suggested by the patient), implied candidate diagnosis (a set of symptoms specifically indexing a particular diagnosis), portraying severity of illness, appealing to life-world circumstances, and previous use of antibiotics. Also, clinicians were observed to rationalize their antibiotic prescriptions by reporting medically acceptable reasons and diagnoses to patients.

CONCLUSIONS

Patients strongly influence the antibiotic prescribing of physicians by using a number of different behaviors. To decrease antibiotic use for ART infections, patients should be educated about the dangers and limited benefits of such use, and clinicians should consider appropriate responses to these different patient pressures to prescribe antibiotics.