Pharmacological characterisation of the effort for reward task as a measure of motivation for reward in male mice

RATIONALE

Motivational deficits are a common symptom shared across multiple psychiatric and neurodegenerative disorders. Effort-based decision-making tasks are a translatable method for assessing motivational state. Much of the preclinical validation of the task derives from acute pharmacological manipulations in rats. However, mice currently offer a greater genetic toolkit to study risk genes and phenotypic models. Despite this, there is limited characterisation of their behaviour in this type of motivation task.

OBJECTIVES

Here, we investigate the effort for reward (EfR) task as a measure of motivational state in mice using drugs previously shown to modulate effort-based decision-making in rats and humans.

METHOD

Using male C57bl/6j mice, we test the effects of drugs which modulate DA transmission. We also test the effects of CP101-606 which does not act directly via DA modulation but has been shown to exert beneficial effects on motivational state. Finally, we test the sensitivity of the task to a chronic corticosterone (CORT) treatment.

RESULTS

Amphetamine, methylphenidate, and CP101606 in mice increased high-effort responses for high-value reward, while administration of haloperidol decreased high-effort responses. Surprisingly, tetrabenazine had no effect at the doses tested. Chronic, low-dose CORT consumption did not alter task performance.

CONCLUSION

These data suggest that the EfR task is sensitive to acute dopaminergic modulation and NR2B selective antagonism in mice. However, it may lack sensitivity to non-acute phenotypic models. Further work is required to demonstrate the utility of the task in this context.

A Radiation Therapy Contouring Atlas for Delineation of the Level I-II Axilla in the Prone Position

PURPOSE/OBJECTIVE(S)

When patients are treated prone for whole breast irradiation (WBI), the axilla typically receives less dose than when patients are treated with WBI in the supine position. There are situations, however, where the axilla is a target as in a situation where the physician intends to treat with "high tangents" to provide good coverage of both the breast and level I-II axilla. In these scenarios, ideal target delineation when the patient is in the prone position is not well-defined. While different consensus guidelines exist for delineation of the nodal areas in the supine position, to our knowledge there are no contouring guidelines for the regional nodes in the prone position based on bone, skin, vascular and muscle landmarks.

MATERIALS/METHODS

Forty-three patients treated with high tangents in the prone position from 2012-2018 were identified as representative cases. The level I and II regional nodal contours from the Radiation Therapy Oncology Group (RTOG) breast cancer atlas were adapted for prone position by a radiation oncologist and a breast radiologist based on anatomic considerations and changes observed from supine to prone positioning on diagnostic imaging. The revised nodal contours were reviewed by an expanded expert multidisciplinary panel including additional breast radiation oncologists and surgical oncologists to delineate the level I and II axilla on noncontrast computed tomography (CT) scans.

RESULTS

We adapted the RTOG breast cancer atlas, supported by detailed figures, in order to create a CT based atlas of the level I and II axillary lymph node stations in the prone position. For the level I axilla, the cranial and caudal anatomic boundaries remain unchanged. With transition to the prone position from supine, tenting of the pectoralis major occurs displacing the muscle from the chest wall and shifting the axillary space anteromedial to the lateral border of the pectoralis major. Therefore, the anterior boundary is now defined by the plane of the anterior extent of the pectoralis major to skin. The medial boundary is defined by the plane of the lateral border of the pectoralis major and pectoralis minor including to ribs and intercostal muscles. The lateral boundary is defined by the skin, cropped by 5mm. The posterior boundary is defined by the plane of the anterior surface of the latissimus dorsi and subscapularis muscle to skin. For the level II axilla, the cranial, posterior, medial and lateral boundaries remain unchanged. With transition from supine to prone, the axilla exhibits an anterolateral shift, now laterally abutting the lateral border of the pectoralis minor. The anterior boundary is now defined as the posterior aspect of the pectoralis major muscle. The caudal boundary is where the pectoralis minor inserts into ribs.

CONCLUSION

The adaptations to the RTOG breast cancer atlas for prone positioning will enable radiation oncologists to more accurately target the level I and II axilla when treating patients prone in whom the axilla is a target in addition to the breast.

A Phase II Trial Evaluating Rapid Mid-Treatment Nodal Shrinkage to Select for Adaptive Deescalation in p16+ Oropharyngeal Cancer Patients Undergoing Definitive Chemoradiation

PURPOSE/OBJECTIVE(S)

The purpose of this study is to determine if rapid mid-treatment nodal shrinkage (RMNS) can identify patients with p16+ oropharyngeal cancer (OPC) who can be safely deescalated with reduced dose chemoradiation therapy (CRT). The primary endpoint was 2-year progression free survival (PFS).

MATERIALS/METHODS

Inclusion criteria were as follows: T1-3, N1, M0 (AJCC 8th edition) p16+ OPC with <10 pack-year smoking history. All patients were initially planned for standard dose CRT (70 Gy) and weekly cisplatin. Patients were evaluated with a CT scan at week 4 for RMNS, defined as >40% nodal volumetric reduction from baseline. If RMNS was achieved, they proceeded to deescalated CRT (60 Gy). If not, they received standard CRT. Biomarker correlates were collected at baseline and week 4 of CRT including plasma TTMV (tumor tissue modified viral) HPV DNA and MRI diffusion weighted imaging (DWI). Univariate logistic regression analyses (UVA) were performed to evaluate predictors of RMNS. Odds ratios with 95% CI are reported, using a p<0.05 for statistical significance with a two-sided test. Wilcoxon rank sum tests were used to evaluate differences between the two groups using p < 0.05, 2-sided) for statistical significance. All statistical procedures were performed using R () with no adjustments for multiple testing.

RESULTS

Thirty-six patients were enrolled: median age: 60 years; 81% male; primary site: 36% base of tongue, 53% tonsil, 11% both; T-stage: 39% T1, 50% T2, 11% T3; N-stage: 100% N1; any smoking history: 58% yes, 42% no; 67% (n = 24) had RMNS and received deescalated CRT while the remaining proceeded to standard CRT. At a median follow-up of 32.4 months, 2-year PFS between the standard and deescalated groups were 91.7% vs 90.9%, respectively (p = 0.97). All patients with recurrence underwent successful salvage treatment with 2-year OS 100% for all patients. On UVA, rapid TTMV HPV DNA clearance (baseline to week 4) (OR 12.0 [1.65-250], p = 0.034), lower MRI diffusivity (ADC) at baseline (OR 0.79 [0.61-0.97], p = 0.042) and week 4 (OR 0.76 [0.60-0.91], p = 0.009), and higher MRI diffusional kurtosis at baseline (OR 1.09 [1.01-1.21], p = 0.051) and week 4 (OR 1.24 [1.09-1.52], p = 0.009) were significantly associated with RMNS. When comparing the deescalated and standard cohorts, the mean baseline and week 4 MRI ADC were significantly lower and week 4 MRI diffusional kurtosis was significantly higher in the deescalated group.

CONCLUSION

In this phase II study, rapid mid-treatment nodal shrinkage appeared to select favorable risk p16+ oropharynx cancer patients for treatment de-escalation. Rapid clearance of TTMV HPV DNA at week 4 as well as MRI DWI biomarkers of low ADC and high diffusional kurtosis values were correlated with RMNS. A larger study is planned to incorporate RMNS and biomarkers for further treatment de-escalation. Additional trial information is available at ClinicalTrials.gov (Identifier: NCT03215719).

A11 ISOLATION OF NON-POLAR METABOLITES IN EXCRETORY/SECRETORY PRODUCTS FROM PARASITIC HELMINTHS AND THEIR POTENTIAL AS IMMUNOTHERAPY IN INFLAMMATORY BOWEL DISEASE

Background

Parasitic helminths are known to modulate host immune responses. This is thought to be mediated by their secretome. We are interested in the excretory/secretory products and mechanisms for modulating immune dysfunction in autoinflammatory diseases.

Aims

This research studies the mechanisms of immune modulation by parasitic helminths in the context of IBD. We aim to describe immunomodulatory helminth-derived metabolites (ESM).

Methods

Helminth-conditioned media was used to isolate ESM, which were further purified using column chromatography.

Bone marrow (BM) derived macrophages (BMDM) from C57BL6 mice, were treated with ESP fractions from Trichuris suis, Ascaris suum, Heligmosomoides polygyrus bakeri or Dirofilaria immitis, stimulated with LPS, and secreted cytokine levels measured. Moreover, BM was cultured with or without ESM throughout differentiation to BMDM.

Colitic mice (3% DSS, 5 days) were treated with A. suum ESM or PBS once daily IP. Colon lengths and TNFα mRNA were measured, and histological preparations were scored to assess pathology.

Bioactive D. immitis ESM were fractionated using preparatory HPLC and assayed for bioactivity. Active fractions were analysed using MS/MS and fragmentation patterns and molecular weights were obtained. The active fractions are currently being studied by NMR to deduce a structure of an active metabolite.

Results

BMDM treated with crude ESM decreased TNFα secretion and increased IL-10. BMDM precursors which were treated with A. suum ESM throughout differentiation had reduced proliferation in a dose dependent manner. These BMDM showed remodeling of BMDM metabolic pathways. Intracellular ROS production was inversely proportional to Alamar blue oxidation.

We found that ESM from A. suum improved DSS-colitis. Specifically, mice with DSS-induced colitis given IP ESM had longer colons, lower histolopathology score, and lower TNFα mRNA expression in gut tissue.

HPLC-fractionated D. immitis ESM used to treat BMDM yielded varying suppression of TNFα with LPS stimulation. MS/MS of TNFα suppressive fractions contained masses with fragmentation patterns which were detected in fractions of several of the above-mentioned parasite species. Preliminary NMR studies will determine if this represents a conserved structure.

Conclusions

Helminth-derived components can immunologically polarize a response in vitro, as well as favour recovery in DSS colitis. Through multiple purification steps, a nearly pure fraction is found to have bioactivity, suggesting a single, bioactive molecule that is conserved across several parasitic helminths. These data are important in understanding the host-parasite interaction modulated by ESM, as well as provide therapeutic potential in IBD.

Funding Agencies

NSERC, FRQNT

Spontaneous coronary artery thrombosis in the setting of active lupus mesenteric vasculitis

A 33-year-old male with systemic lupus erythematosus (SLE) presented with acute abdominal pain and was found to have lupus mesenteric vasculitis on imaging and during exploratory laparotomy. Post laparotomy he continued to have persistent nausea and dyspepsia and an electrocardiogram showed evidence of an inferior ST elevation myocardial infarction (STEMI). Emergency cardiac catheterization showed evidence of thrombotic right coronary artery occlusion. His coronaries were otherwise normal with no evidence of underlying coronary artery disease. Extensive workup with trans-esophageal echo, serologies for antiphospholipid antibody syndrome (APS) and bubble study was negative. This effectively ruled out Libman–Sacks endocarditis, APS-induced arterial thrombus and paradoxical emboli as potential causes of his STEMI. By exclusion of other causes, the etiology of his STEMI was felt to be secondary to in-situ coronary artery thrombosis in the setting of active SLE. To the best of our knowledge, this is the first report of a patient with SLE presenting with both lupus mesenteric vasculitis and in-situ coronary arterial thrombosis in the absence of APS.

Genetic control of susceptibility to infection with Plasmodium chabaudi chabaudi AS in inbred mouse strains

To identify genetic effects modulating blood stage replication of the malarial parasite, we phenotyped a group of 25 inbred mouse strains for susceptibility to Plasmodium chabaudi chabaudi AS infection (peak parasitemia, survival). A broad spectrum of responses was observed, with strains such as C57BL/6J being the most resistant (low parasitemia, 100% survival), and strains such as NZW/LacJ and C3HeB/FeJ being extremely susceptible (very high parasitemia and uniform lethality). A number of strains showed intermediate phenotypes and gender specific effects, suggestive of rich genetic diversity in response to malaria in inbred strains. An F2 progeny were generated from SM/J (susceptible) and C57BL/6J (resistant) parental strains, and was phenotyped for susceptibility to P. chabaudi chabaudi AS. A whole genome scan in these animals identified the Char1 locus (LOD=7.40) on chromosome 9 as a key regulator of parasite density and pointed to a conserved 0.4Mb haplotype at Char1 that segregates with susceptibility/resistance to infection. In addition, a second locus was detected in [SM/J x C57BL/6J] F2 mice on the X chromosome (LOD=4.26), which was given the temporary designation Char11. These studies identify a conserved role of Char1 in regulating response to malaria in inbred mouse strains, and provide a prioritized 0.4Mb interval for the search of positional candidates.

Outcome of components separation for contaminated complex abdominal wall defects

BACKGROUND

Contaminated large abdominal wall defects can pose a formidable challenge to the surgeon. This study compared the outcome of components separation (CS) for complex ventral defects with or without contamination.

METHODS

A retrospective review was conducted of all patients who underwent CS over an 8-year period. Pre-operative factors such as the presence/absence of contamination were analyzed for their effect on length of hospitalization, readmission rate, post-operative complications, re-intervention rate, and long-term recurrence.

RESULTS

A total of 34 patients was analyzed. There were 18 males (53%) with a mean age of 57 years. Mean body mass index was 31 kg/m(2). Seventeen patients (50%) had prior repair (mean 2.1 repairs per patient, median 2). Mean size of abdominal defect was 255 cm(2). Out of the 34 patients, 13 had infected or contaminated defects, including 5 patients with infected mesh. Length of stay was longer in the contaminated group (11.1 vs 3.1 days, P < 0.01). A higher complication rate was noted in the setting of contamination (77 vs 38%, P = 0.03). During a mean follow-up of 47 months, no difference was noted in the re-intervention rate (38 vs 29%, P = 0.70) or long-term recurrence rate of the defect (8 vs 5%, P = 1.0) (contaminated vs non-contaminated group, respectively).

CONCLUSIONS

CS is a good option for closure of large contaminated complex abdominal wall defects. Despite an increased risk of postoperative complications and longer hospitalization length, long-term outcomes are favorable.

Mapping of Char10, a novel malaria susceptibility locus on mouse chromosome 9

Resistance to blood-stage malaria in AcB55 and AcB61 is caused by a loss of function mutation in pyruvate kinase (Pklr(I90N)). Likewise, pyruvate kinase (PK) deficiency in humans is protective against Plasmodium replication in vitro. We identified a third AcB strain, AcB62 that also carries the Pklr(I90N) mutation. However, AcB62 mice were susceptible to P.chabaudi infection and showed high levels of parasite replication (54-62% peak parasitemia). AcB62 mice showed the hallmarks of PK deficiency-associated anemia similar to AcB55/61 with reticulocytosis, splenic red pulp expansion, tissue iron overload, and increased expression of iron metabolism proteins. This suggests that malaria susceptibility in AcB62 is not because of absence of PK deficiency-associated pathophysiology. To map novel genetic factors affecting malaria susceptibility in AcB62, we generated an informative F2 population using AcB62 (Pklr(I90N)) and CBA-Pk(slc) (Pklr(G338D)) as progenitors and identified a novel locus on chromosome 9 (Char10; LOD=7.24) that controls peak parasitemia. A weaker linkage to the Pklr region of chromosome 3 (LOD=3.7) was also detected, a finding that may reflect the segregation of the two defective Pklr alleles. AcB62 alleles at both loci are associated with higher peak parasitemia. These results identify Char10 as a novel locus modulating severity of malaria in the context of PK deficiency.