Two risk assessments: Evaluating the use of indicator HF183 Bacteroides versus pathogen measurements for modelling recreational illness risks in an urban watershed

The purpose of this study was to evaluate the performance of HF183 Bacteroides for estimating pathogen exposures during recreational water activities. We compared the use of Bacteroides-based exposure assessment to exposure assessment that relied on pathogen measurements. We considered two types of recreational water sites: those impacted by combined sewer overflows (CSOs) and those not impacted by CSOs. Samples from CSO-impacted and non-CSO-impacted urban creeks were analysed by quantitative polymerase chain reaction (qPCR) for HF183 Bacteroides and eight human gastrointestinal pathogens. Exposure assessment was conducted two ways for each type of site (CSO-impacted vs. non-CSO impacted): 1) by estimating pathogen concentrations from HF183 Bacteroides concentrations using published ratios of HF183 to pathogens in sewage and 2) by estimating pathogen concentrations from qPCR measurements. QMRA (quantitative microbial risk assessment) was then conducted for swimming, wading, and fishing exposures. Overall, mean risk estimates varied from 0.27 to 53 illnesses per 1,000 recreators depending on exposure assessment, site, activity, and norovirus dose-response model. HF183-based exposure assessment identified CSO-impacted sites as higher risk, and the recommended HF183 risk-based threshold of 525 genomic copies per 100 mL was generally protective of public health at the CSO-impacted sites but was not as protective at the non-CSO-impacted sites. In the context of our urban watershed, HF183-based exposure assessment over- and under-estimated risk relative to exposure assessment based on pathogen measurements, and the etiology of predicted pathogen-specific illnesses differed significantly. Across all sites, the HF183 model overestimated risk for norovirus, adenovirus, and Campylobacter jejuni, and it underestimated risk for E. coli and Cryptosporidium. To our knowledge, this study is the first to directly compare health risk estimates using HF183 and empirical pathogen measurements from the same waterways. Our work highlights the importance of site-specific hazard identification and exposure assessment to decide whether HF183 is applicable for monitoring risk.

Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433

SS 433 is a microquasar, a stellar binary system that launches collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an energy-dependent shift in the apparent position of the gamma-ray emission from the parsec-scale jets. These observations trace the energetic electron population and indicate that inverse Compton scattering is the emission mechanism of the gamma rays. Our modeling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system, at distances of 25 to 30 parsecs, and that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons.

Academic clinician frontline-worker wellbeing and resilience during the COVID-19 pandemic experience: Were there gender differences?

Prior research suggests COVID-19 has amplified stress on Academic Clinician Frontline-Workers (ACFW). The aim of this paper is: (1) to better understand the experiences of ACFW during the COVID-19 pandemic including their mental-emotional wellbeing, academic productivity, clinical experiences, and (2) to examine any gender differences. A cross-sectional survey was administered to University of Minnesota/M Health Fairview systems' faculty February-June 2021. Of the 291 respondents, 156 were clinicians, with 91 (58 %) identifying as Frontline-Workers (ACFW). Faculty wellbeing was assessed using validated measures in addition to measures of productivity and sociodemographics. For example, ACFW reported a higher Work-Family Conflict (WFC) scores compared to non-ACFW (26.5 vs. 24.1, p = 0.057) but did not report higher Family-Work Conflict (FWC) scores (17.7 vs. 16.3, p = 0.302). Gender sub-analyses, revealed that women ACFW compared to men ACFW reported higher WFC scores (27.7 vs. 24.1, p = 0.021) and FWC (19.3 vs. 14.3, p = 0.004). Academically, ACFW reported submitting fewer grants and anticipated delays in promotion and tenure due to the COVID-19 (p = 0.035). Results suggest COVID-19 has exacerbated ACFW stress and gender inequities. Reports of anticipated delay in promotion for ACFW may pose a challenge for the long-term academic success of ACFW, especially women ACFW. In addition, women may experience higher FWC and WFC as compared to men. Schools of academic medicine should consider re-evaluating promotion/tenure processes and creating resources to support women ACFW as well as ACFW caregivers.

Factor structure of the Oxford Shoulder Score: secondary analyses of the UK FROST and PROFHER trial populations

AIMS

Frozen shoulder and proximal humeral fracture can cause pain, stiffness and loss of function. The impact of these symptoms on patients can be measured using the comprehensively validated, 12-item Oxford Shoulder Score (OSS). Evidence suggests that pain and function may have a differential impact on patients' experience of shoulder conditions, and this may be important for clinical management. We therefore explored the factor structure of the OSS within the UK FROST and PROFHER trial populations.

METHODS

We performed exploratory factor analysis (EFA), followed by confirmatory factor analysis (CFA), on baseline UK FROST data from 490 of the 503 trial participants. Data at 6 months post-randomisation were used for 228 of the 250 participants for the PROFHER trial.

RESULTS

UK FROST factor extraction results, using Velicer's Minimum Average Partial and Horn's Parallel Analysis tests, suggested a unifactorial solution, but two factors were weakly indicated by the less reliable 'Kaiser's eigenvalue > 1' and scree tests. We explored this further using EFA. Eight items (2 to 7, 9 and 10) loaded onto a 'Function' factor, three on a 'Pain' factor (1, 8 and 12) and item 11 cross-loaded. However, one- and two-factor models were rejected in CFA. Factor extraction of PROFHER data at 6 months demonstrated a single first-order factor solution, which was also subsequently rejected in CFA.

CONCLUSION

Insufficient evidence was found, within the constraints of the data available, to support the use of 'Pain' and 'Function' sub-scales of the OSS in either patient population.

Should Cystatin C eGFR Become Routine Clinical Practice?

Kidney function assessment is crucial for diagnosing and managing kidney diseases. Glomerular filtration rate (GFR) is widely used as an indicator of kidney function, but its direct measurement is challenging. Serum creatinine, a commonly used marker for estimating GFR (eGFR), has limitations in accuracy and sensitivity. Cystatin C, a protein freely filtered by the glomerulus, has emerged as a promising alternative marker for kidney function. It is unaffected by muscle mass and shows stronger associations with cardiovascular disease and mortality than creatinine. Various equations have been developed to estimate GFR using creatinine or cystatin C alone or in combination. The CKD-EPI_creat-cys equation combining both markers demonstrates improved accuracy in GFR estimation, especially for individuals with eGFR values of 45-59 mL/min/1.73 m². Cystatin C-based estimates of GFR outperform creatinine-based estimates in predicting clinical outcomes and identifying patients at higher risk, particularly in elderly and non-white ethnic groups. Cystatin C offers advantages over creatinine as a marker of kidney function. It is not influenced by non-kidney factors and provides more accurate estimation of GFR, aiding in the early detection of kidney disease and predicting adverse outcomes. Incorporating cystatin C into routine kidney function assessment may improve patient risk stratification and guide clinical decision-making. However, widespread adoption of cystatin C testing requires increased availability and accessibility in clinical laboratories. Further research and implementation efforts are needed to fully realize the potential of cystatin C in kidney function assessment and improving patient outcomes.

Search for Dark Matter Annihilation Signals in the H.E.S.S. Inner Galaxy Survey

The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new observations from an unprecedented γ-ray survey of the Galactic Center (GC) region, i.e., the Inner Galaxy Survey, at very high energies (≳100  GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant γ-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section ⟨σv⟩. Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach ⟨σv⟩ values of 3.7×10^{-26}  cm^{3} s^{-1} for 1.5 TeV DM mass in the W^{+}W^{-} annihilation channel, and 1.2×10^{-26}  cm^{3} s^{-1} for 0.7 TeV DM mass in the τ^{+}τ^{-} annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based γ-ray observations thus probe ⟨σv⟩ values expected from thermal-relic annihilating TeV DM particles.

Extending the scope of practice for experienced assistant practitioners in breast screening and the impact on service resilience

INTRODUCTION

Historically, the NHS Breast Screening Programme (NHSBSP) required Assistant Practitioners (APs), who are non-registered practitioners, to be supervised by and work alongside a registered radiographer (RPs). Following a national pilot looking at the implementation of two APs working remotely without direct supervision by a radiographer, this study seeks to evaluate a local trial of this new model of working.

METHODS

Pairs of APs were deployed to work together on a mobile breast screening unit over a four-month period. Assessments were carried out to review technical performance using established NHSBSP technical repeat and recall rates in the United Kingdom. Notes on any queries from those involved during the dual AP sessions were prospectively collected and reviewed. Feedback from APs and other multi-disciplinary team members were collected and content analysis was applied.

RESULTS

A total of 828 women were screened across the 26 AP clinics that were delivered. Technical repeat and recall rates of participating APs remained stable throughout the pilot period and marginally improved across all participating staff. No women attended the AP clinic who could not be screened and no support from a RP was required during the sessions. Seven normal clinics were converted to AP clinics due to lack of staff on the day, avoiding the cancellation of screening clinics. Feedback from across the screening team was positive.

CONCLUSIONS

Increasing the autonomy of experienced APs can significantly contribute to the delivery of a resilient radiographic workforce that maintains service performance. Suitable experience and wider team involvement appear to be keys to success in this case.

IMPLICATION FOR PRACTICE

Increasing the autonomy and voice of the APs has a positive effect on the resilience of the wider radiographic workforce and the service as a whole. It also can provide a mechanism for raising their profile with a possible raise in job satisfaction, staff engagement and retention.

Do changes in primary care service use over time differ by neighbourhood income? Population-based longitudinal study in British Columbia, Canada

Background

Strong primary care systems have been associated with improved health equity. Primary care system reforms in Canada may have had equity implications, but these have not been evaluated. We sought to determine if changes in primary care service use between 1999/2000 and 2017/2018 differ by neighbourhood income in British Columbia.

Methods

We used linked administrative databases to track annual primary care visits, continuity of care, emergency department (ED) visits, specialist referrals, and prescriptions dispensed over time. We use generalized estimating equations to examine differences in the magnitude of change by neighbourhood income quintile, adjusting for age, sex/gender, and comorbidity, and stratified by urban/rural location of residence. We also compared the characteristics of physicians providing care to people living in low- and high-income neighbourhoods at two points in time.

Results

Between 1999/2000 and 2017/8 the average number of primary care visits per person, specialist referrals, and continuity of care fell in both urban and rural settings, while ED visits and prescriptions dispensed increased. Over this period in urban settings, primary care visits, continuity, and specialist referrals fell more rapidly in low vs. high income neighbourhoods (relative change in primary care visits: Incidence Rate Ratio (IRR) 0.881, 95% CI: 0.872, 0.890; continuity: partial regression coefficient -0.92, 95% CI: -1.18, -0.66; specialist referrals: IRR 0.711, 95%CI: 0.696, 0.726), while ED visits increased more rapidly (IRR 1.06, 95% CI: 1.03, 1.09). The percentage of physicians who provide the majority of visits to patients in neighbourhoods in the lower two income quintiles declined from 30.6% to 26.3%.

Conclusion

Results raise concerns that equity in access to primary care has deteriorated in BC. Reforms to primary care that fail to attend to the multidimensional needs of low-income communities may entrench existing inequities. Policies that tailor patterns of funding and allocation of resources in accordance with population needs, and that align accountability measures with equity objectives are needed as part of further reform efforts.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12939-022-01679-4.

Time-resolved hadronic particle acceleration in the recurrent nova RS Ophiuchi

Recurrent novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of fresh material from a binary companion. The shock generated when ejected material slams into the companion star's wind can accelerate particles. We report very-high-energy (VHE, [Formula: see text]) gamma rays from the recurrent nova RS Ophiuchi, up to a month after its 2021 outburst, observed using the High Energy Stereoscopic System. The VHE emission has a similar temporal profile to lower-energy GeV emission, indicating a common origin, with a two-day delay in peak flux. These observations constrain models of time-dependent particle energization, favoring a hadronic emission scenario over the leptonic alternative. Shocks in dense winds provide favorable environments for efficient acceleration of cosmic-rays to very high energies.

Revealing x-ray and gamma ray temporal and spectral similarities in the GRB 190829A afterglow

Gamma-ray bursts (GRBs), which are bright flashes of gamma rays from extragalactic sources followed by fading afterglow emission, are associated with stellar core collapse events. We report the detection of very-high-energy (VHE) gamma rays from the afterglow of GRB 190829A, between 4 and 56 hours after the trigger, using the High Energy Stereoscopic System (H.E.S.S.). The low luminosity and redshift of GRB 190829A reduce both internal and external absorption, allowing determination of its intrinsic energy spectrum. Between energies of 0.18 and 3.3 tera-electron volts, this spectrum is described by a power law with photon index of 2.07 ± 0.09, similar to the x-ray spectrum. The x-ray and VHE gamma-ray light curves also show similar decay profiles. These similar characteristics in the x-ray and gamma-ray bands challenge GRB afterglow emission scenarios.

The impact of e-alerts on inpatient diagnosis and management of acute kidney injury

AIMS/BACKGROUND

Electronic alerts can help with the early detection of acute kidney injury in hospitalised patients. Evidence for their role in improving patient care is limited. The authors have completed an audit loop to evaluate the impact of electronic alerts, and an associated acute kidney injury management pathway, on patient care.

METHODS

The audits were conducted at a large tertiary care hospital in the UK. Case notes were reviewed for 99 patients over two periods: pre-alert (in 2013; n=55) and post-alert (in 2018; n=44), using the same methodology. Patients for case note reviews were randomly chosen from the list of acute kidney injury alerts generated by the local laboratory information management system.

RESULTS

Recognition of acute kidney injury, as documented in the case notes, increased from 15% to 43% between the two periods. Time to first medical review (following electronic alerts) improved by 17 minutes (median 4 hours 4 minutes in 2013 vs 3 hours 47 minutes in 2018). Completion of pre-defined acute kidney injury assessment tasks (review of vital signs, biochemistry and acid-base parameters, evidence of fluid balance assessment, consideration of possible sepsis, and examination or requesting urinalysis) improved in 2018. However, acute kidney injury management tasks (correction of hypovolaemia, addressing or investigating obstruction, medications review, renal referral, requesting of further biochemical tests, addressing possible sepsis) showed very little or no improvement.

CONCLUSIONS

The introduction of acute kidney injury electronic alerts and management pathway resulted in improved recognition and initial assessment of patients with acute kidney injury. Further steps are needed to translate this in to improved patient management.

Injury surveillance in elite Paralympic athletes with limb deficiency: a retrospective analysis of upper quadrant injuries

Background

Compared to injury surveillance in Olympic athletes relatively little literature exists for Paralympic athletes. Injury surveillance data underpin design and evaluation of injury prevention strategies in elite sport. The aim of this study is investigate upper quadrant injuries in elite athletes with limb deficiency.

Methods

A retrospective analysis of upper quadrant injuries in elite athletes with limb deficiency with available data (2008–2016) was conducted using medical notes extracted from English Institute of Sport (EIS) records. Eligibility criteria included funded athletes, eligible for EIS physiotherapy support with an upper and/or lower limb disability arising from full or partial limb deficiency.

Results

A total 162 injuries from 34 athletes were included. Participant characteristics: 20 males (59%), from 9 sports, with mean age 27 years (range 16–50 years) and 15 with congenital limb loss (44%). Athletes age 20–29 years experienced most injuries, four per athlete. The glenohumeral joint was the reported injury site (23%, n = 38). Index (first) injuries accounted for 77% (n = 128) injuries, 17% (n = 28) a recurrence and 6% (n = 10) an exacerbation. More than half of injuries occurred in training (58%, n = 94), this being slightly higher in those with traumatic limb loss. Athletes with quadruple levels of limb deficiency had double the number of recurrent injuries as those with single or double limb deficiency.

Conclusion

Elite athletes with limb deficiency experience upper quadrant injuries, with glenohumeral joint the most frequently reported. The quality and consistency of data reported limits definitive conclusions, although findings highlight the importance of precision and accuracy in recording injury surveillance to enable implementation of effective injury prevention strategies.

Abstract IA20: Radiotherapy plus cetuximab or cisplatin in human papilloma-virus positive oropharyngeal cancer (NRG 1016): A randomized multicenter noninferiority trial*

Background: Patients with HPV-related oropharynx cancer have high survival when treated with radiotherapy plus cisplatin. Whether replacement of cisplatin with cetuximab can preserve high survival and reduce toxicity is unknown. We performed a randomized trial comparing survival and toxicity in 987 patients enrolled at 182 health care centers in the US and Canada between July 2011 and July 2014.

Methods: Eligibility included histologically confirmed HPV positive carcinoma, clinical stage TI-T2, N2-N3 or T3-T4, N0-N3. Zubrod status 0 or 1. All patients received intensity modulated radiotherapy (IMRT) delivered in 35 fractions to 70 gray over 6 weeks using 6 fractions per week. High-dose cisplatin at 100 mg/m² was given every 3 weeks for 2 cycles in arm A (standard of care) versus arm B loading dose cetuximab plus weekly cetuximab. Patients were stratified by T category, N category, Zubord performance status, and smoking history.

Primary analysis was based on modified intention to treat for all patients meeting eligibility criteria. 849 patients were randomly assigned to radiation plus cetuximab (425) or radiotherapy plus cisplatin (424). Median follow-up is 4.5 years.

Results: Radiotherapy plus cetuximab did not meet the non-inferiority criteria for overall survival. Estimated 5-year overall survival was 78% in the cetuximab group versus 85% in the cisplatin group (p=0.016). Progression-free survival was 67% versus 78% (p=0.0002). Local-regional failure was higher in the cetuximab group, 17% versus 10% (p=0.005). High-grade acute toxicity was similar at 77% for both groups. Late toxicity was also similar.

Conclusions: For HPV-positive oropharyngeal carcinoma, radiotherapy plus cetuximab showed inferior overall survival, progression-free survival, and locoregional control compared with radiation plus cisplatin. This study defines radiation using IMRT plus cisplatin as the standard of care for this population.

*Lancet. Vol 393, p 40-50, January 5, 2019

Citation Format: J.A. Ridge, J. Ringash, M. Yao, D.M. Blakaj, M.A. Razaq, A.D. Colevas, J.J. Beitler, C.U. Jones, N.E. Dunlap, S.A. Seaward, S. Spencer, T.J. Galloway, J.J. Dignam, Q.T. Le, M.L. Gillison, E.M. Sturgis, J. Phan, A.M. Trotti, J. Harris, A. Eisbruch, P.M. Harari, D.J. Adelstein, S.A. Koyfman, B. Burtness. Radiotherapy plus cetuximab or cisplatin in human papilloma-virus positive oropharyngeal cancer (NRG 1016): A randomized multicenter noninferiority trial [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr IA20.

Effects of Methamphetamine Self-Administration and Extinction on Astrocyte Structure and Function in the Nucleus Accumbens Core

Astrocytes provide support for neurons, regulate metabolic processes, and influence neuronal communication in a variety of ways, including through the homeostatic regulation of glutamate. Following 2-h cocaine or methamphetamine self-administration (SA) and extinction, rodents display decreased levels of basal glutamate in the nucleus accumbens core (NAcore), which transitions to elevated glutamate levels during drug seeking. We hypothesized that, like cocaine, this glutamate 'overflow' during methamphetamine seeking arises via decreased expression of the astroglial glutamate transporter GLT-1, and withdrawal of perisynaptic astroglial processes (PAPs) from synapses. As expected, methamphetamine self-administration and extinction decreased the level of contact made by PAPs in the NAcore, yet did not impact glutamate uptake, GLT-1 expression, or the general structural characteristics of astrocytes. Interestingly, systemic administration of N-acetylcysteine (NAC), a drug that both upregulates GLT-1 and promotes glial-glutamate release, reduced cued methamphetamine seeking. In order to test the impact of astrocyte activation and the induction of glial glutamate release within the NAcore, we employed astrocyte-specific expression of designer receptors exclusively activated by designer drugs (DREADDs). We show here that acute activation of Gq-coupled DREADDs in this region inhibited cued methamphetamine seeking. Taken together, these data indicate that cued methamphetamine seeking following two-hour SA is not mediated by deficient glutamate clearance in the NAcore, yet can be inhibited by engaging NAcore astrocytes.

A comparison of screw versus drill and curettage epiphysiodesis to correct leg-length discrepancy

PURPOSE

To compare two common surgical techniques of epiphysiodesis: drill/curettage epiphysiodesis (PDED) versus cross screw epiphysiodesis (PETS). The hypothesis is that the two techniques have similar efficacy but demonstrate differences in length of hospital stay (LOS), time to return to activity and complication rates.

METHODS

A retrospective review of growing children and adolescents less than 18 years old who required an epiphysiodesis with leg-length discrepancy (LLD) of 2 cm to 6 cm with minimum two years of follow-up was conducted. Characteristics including age at surgery, gender, epiphysiodesis location, side, operative time, LOS and hardware removal were compared across treatment groups. LLD, expected growth remaining (EGR) and bone age were determined preoperatively and at most-recent visit. The correction ratio (change in EGR) was calculated along with a 95% confidence interval (CI) to assess if correction in leg length was achieved.

RESULTS

A total of 115 patients underwent epiphysiodesis in the femur (53%), tibia (24%) or a combination (24%). The cohort was 47% male, with a mean age of 12.6 years (7.7 to 17.7) at surgery. Median follow-up was 3.7 years (2.0 to 12.7). In all, 23 patients underwent PETS and 92 patients had PDED. Both treatment groups achieved expected LLD correction. There was no significant difference in median operative time, complication rates or LOS. PETS patients returned to activity at a mean 1.4 months (interquartile range (IQR) 0.7 to 2.1) while PDED patients returned at a mean 2.4 months (IQR 1.7 to 3) (p < 0.001).

CONCLUSION

Effectiveness in achieving expected correction, LOS and operative time are similar between screw and drill/curettage epiphysiodesis. Patients undergoing PETS demonstrated a faster return to baseline activity than patients with PDED.

LEVEL OF EVIDENCE

III.

Abstract 2817: RAD6 promotes acquired chemoresistance and a poor prognostic marker in ovarian cancer

Ovarian cancer (OC) is deadly and incurable for patients who relapse after primary cancer is treated with surgery and platinum-based chemotherapy. Unfortunately, OC has a high rate of disease recurrence (70-80%) and most recurrent tumors are chemoresistant, causing deaths of nearly 15,000 women from this disease each year in U.S.A., which highlights the need for new therapeutic strategies. Platinum drug resistance and refractory disease pose major challenges in treating this disease and are major factors contributing to the poor survival rate of OC patients. Our studies demonstrated that RAD6 (an E2 ubiquitin conjugating enzyme) signaling is stimulated upon chemotherapeutic treatment and promotes expression of DNA repair proteins including Fanconi anemia (FA) pathway. Analysis of clinical samples revealed upregulation of RAD6 in ovarian tumors compared to normal ovarian tissues and RAD6 inhibition reduces cancer cell survival. In a pilot clinical study (n=26) comparing matched OC tumors from patients before and after carboplatin chemotherapy regimen, we found that RAD6 was upregulated after treatment and correlated with both chemoresistance and poor progression-free survival. Knockdown or inhibition of catalytic activity (small-molecule inhibitor) of RAD6 attenuated carboplatin-induced monoubiquitination of target proteins such as FANCD2, PCNA and histone 2B, thereby sensitizing OC cells to carboplatin. Interestingly, inhibition of RAD6 alone in OC cells induced replication stress and reduced cell survival and proliferation by arresting cells in the G2/M phase. Moreover, RAD6 plays an important role in the activation of the trans-lesion synthesis (TLS) pathway by monoubiquitinating PCNA and in the activation of the FA DNA repair pathway. These are critical mechanisms for cells to repair DNA crosslinks induced by platinum drugs. Together with these observations, our data suggest that inhibition of RAD6 could be a viable therapeutic target for overcoming platinum resistance and disease recurrence induced by FA pathway in ovarian cancer.

Citation Format: Chinnadurai Mani, David Clark, Ranganatha Somasagara, Sebastian Spencer, Kaushlendra Tripathi, Komariah Palle. RAD6 promotes acquired chemoresistance and a poor prognostic marker in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2817.

The Nucleus Accumbens: Mechanisms of Addiction across Drug Classes Reflect the Importance of Glutamate Homeostasis

The nucleus accumbens is a major input structure of the basal ganglia and integrates information from cortical and limbic structures to mediate goal-directed behaviors. Chronic exposure to several classes of drugs of abuse disrupts plasticity in this region, allowing drug-associated cues to engender a pathologic motivation for drug seeking. A number of alterations in glutamatergic transmission occur within the nucleus accumbens after withdrawal from chronic drug exposure. These drug-induced neuroadaptations serve as the molecular basis for relapse vulnerability. In this review, we focus on the role that glutamate signal transduction in the nucleus accumbens plays in addiction-related behaviors. First, we explore the nucleus accumbens, including the cell types and neuronal populations present as well as afferent and efferent connections. Next we discuss rodent models of addiction and assess the viability of these models for testing candidate pharmacotherapies for the prevention of relapse. Then we provide a review of the literature describing how synaptic plasticity in the accumbens is altered after exposure to drugs of abuse and withdrawal and also how pharmacological manipulation of glutamate systems in the accumbens can inhibit drug seeking in the laboratory setting. Finally, we examine results from clinical trials in which pharmacotherapies designed to manipulate glutamate systems have been effective in treating relapse in human patients. Further elucidation of how drugs of abuse alter glutamatergic plasticity within the accumbens will be necessary for the development of new therapeutics for the treatment of addiction across all classes of addictive substances.