Using Microdialysis to Monitor Dopaminergic Support of Limb-Use Control Following Mesencephalic Neurosphere Transplantation in a Rodent Model of Parkinson's Disease.

Controlled nigrostriatal dopamine release supports effective limb use during locomotion coordination that becomes compromised after this pathway deteriorates in Parkinson's Disease (PD). How dopamine release relates to active ongoing behavior control remains unknown. Restoring proper release strategy appears important to successful PD treatment with transplanted dopamine-producing stem cells. This is suggested by apparently distinct behavioral support from tonic or phasic release and corresponding requirements of requisite afferent control exhibited by intact nigrostriatal neurons. Our laboratory previously demonstrated that transplanted dopaminergic cells can elicit skilled movement recovery known to depend on phasic dopamine release. However, efforts to measure this movement-related dopamine release yielded seemingly paradoxical, incongruent results. In response, here we explored whether those previous observations derived from rapid reuptake transport into either transplanted cells or residual, lesion-surviving terminals. We confirmed this using minimal reuptake blockade during intrastriatal microdialysis. After unilateral dopamine depletion, rats received transplants and were subjected to our swimming protocol. Among dopamine-depleted and transplanted rats, treatment supported restoration of limb movement symmetry. Interestingly, subsequent reuptake-restricted microdialysis confirmed distinct swimming-induced dopamine increases clearly occurred among these lesioned/transplanted subjects. Thus, phasic firing control appears to contribute to transplant-derived recovery in Parkinsonian animals.

Return to Duty in Military Service Members Following Minimally Invasive Sacroiliac Joint Fusion.

INTRODUCTION: As the utilization of minimally invasive sacroiliac joint fusion (SIJF) continues to expand, a better understanding of postoperative outcomes is needed, particularly in young and active individuals. The purpose of this study is to assess the outcomes of this procedure in an active duty military population by examining return-to-duty (RTD) rates. MATERIALS AND METHODS: A retrospective review of the electronic medical record from a tertiary military medical center was performed for active duty service members undergoing SIJF from January 2013 to January 2019. The primary outcome measured was RTD at 6 months, with active duty status at 1 year, last follow-up, and revision surgery as secondary outcomes. Demographic and surgical variables recorded included patient age, gender, military rank, utilization of navigation, and implant type. RESULTS: Sixteen service members met the inclusion criteria, with a mean age of 40.5 ± 6.7 years. The mean follow-up after surgery was 24 ± 15 months. Patients received either cylindrical (n = 6) or triangular (n = 10) implants placed with (n = 6) or without (n = 10) navigation. Within 6 months of surgery, 56% of patients were able to RTD. Patients undergoing navigation-assisted procedures were significantly more likely to RTD at 6 months (100% vs. 30%, P = .011) compared to those undergoing surgery performed with orthogonal fluoroscopic imaging. Compared to those with cylindrical implants, patients with triangular implants were also more likely to RTD at 6 months (80% vs. 17%, P = .035). CONCLUSIONS: Following SIJF, a small majority of service members were able to return to full active duty status by 6 months. Further studies are needed to assess the potential benefits of navigation and implant selection, as our retrospective review noted differences in outcomes based on these variables.

Development of Electronic Health Record-Based Machine Learning Models to Predict Barrett's Esophagus and Esophageal Adenocarcinoma Risk.

INTRODUCTION: Screening for Barrett's esophagus (BE) is suggested in those with risk factors, but remains underutilized. BE/esophageal adenocarcinoma (EAC) risk prediction tools integrating multiple risk factors have been described. However, accuracy remains modest (area under the receiver-operating curve [AUROC] ≤0.7), and clinical implementation has been challenging. We aimed to develop machine learning (ML) BE/EAC risk prediction models from an electronic health record (EHR) database. METHODS: The Clinical Data Analytics Platform, a deidentified EHR database of 6 million Mayo Clinic patients, was used to predict BE and EAC risk. BE and EAC cases and controls were identified using International Classification of Diseases codes and augmented curation (natural language processing) techniques applied to clinical, endoscopy, laboratory, and pathology notes. Cases were propensity score matched to 5 independent randomly selected control groups. An ensemble transformer-based ML model architecture was used to develop predictive models. RESULTS: We identified 8,476 BE cases, 1,539 EAC cases, and 252,276 controls. The BE ML transformer model had an overall sensitivity, specificity, and AUROC of 76%, 76%, and 0.84, respectively. The EAC ML transformer model had an overall sensitivity, specificity, and AUROC of 84%, 70%, and 0.84, respectively. Predictors of BE and EAC included conventional risk factors and additional novel factors, such as coronary artery disease, serum triglycerides, and electrolytes. DISCUSSION: ML models developed on an EHR database can predict incident BE and EAC risk with improved accuracy compared with conventional risk factor-based risk scores. Such a model may enable effective implementation of a minimally invasive screening technology.

A prospective phase 2 clinical trial of a C5a complement inhibitor for acute GVHD with lower GI tract involvement.

Involvement of lower gastrointestinal tract (LGI) occurs in 60% of patients with graft-versus-host-disease (GVHD). Complement components C3 and C5 are involved in GVHD pathogenesis. In this phase 2a study, we evaluated the safety and efficacy of ALXN1007, a monoclonal antibody against C5a, in patients with newly diagnosed LGI acute GVHD receiving concomitant corticosteroid. Twenty-five patients were enrolled; one was excluded from the efficacy analysis based upon negative biopsy. Most patients (16/25, 64%) had acute leukemia; 52% (13/25) had an HLA-matched unrelated donor; and 68% (17/25) received myeloablative conditioning. Half the patients (12/24) had a high biomarker profile, Ann Arbor score 3; 42% (10/24) had high-risk GVHD per Minnesota classification. Day-28 overall response was 58% (13/24 complete response, 1/24 partial response), and 63% by Day-56 (all complete responses). Day-28 overall response was 50% (5/10) in Minnesota high-risk and 42% (5/12) in high-risk Ann Arbor patients, increasing to 58% (7/12) by Day-56. Non-relapse mortality at 6-months was 24% (95% CI 11-53). The most common treatment-related adverse event was infection (6/25, 24%). Neither baseline complement levels (except for C5), activity, nor inhibition of C5a with ALXN1007 correlated with GVHD severity or responses. Further studies are needed to evaluate the role of complement inhibition in GVHD treatment.

Glioma progression is shaped by genetic evolution and microenvironment interactions.

The factors driving therapy resistance in diffuse glioma remain poorly understood. To identify treatment-associated cellular and genetic changes, we analyzed RNA and/or DNA sequencing data from the temporally separated tumor pairs of 304 adult patients with isocitrate dehydrogenase (IDH)-wild-type and IDH-mutant glioma. Tumors recurred in distinct manners that were dependent on IDH mutation status and attributable to changes in histological feature composition, somatic alterations, and microenvironment interactions. Hypermutation and acquired CDKN2A deletions were associated with an increase in proliferating neoplastic cells at recurrence in both glioma subtypes, reflecting active tumor growth. IDH-wild-type tumors were more invasive at recurrence, and their neoplastic cells exhibited increased expression of neuronal signaling programs that reflected a possible role for neuronal interactions in promoting glioma progression. Mesenchymal transition was associated with the presence of a myeloid cell state defined by specific ligand-receptor interactions with neoplastic cells. Collectively, these recurrence-associated phenotypes represent potential targets to alter disease progression.

Single-cell multimodal glioma analyses identify epigenetic regulators of cellular plasticity and environmental stress response.

Glioma intratumoral heterogeneity enables adaptation to challenging microenvironments and contributes to therapeutic resistance. We integrated 914 single-cell DNA methylomes, 55,284 single-cell transcriptomes and bulk multi-omic profiles across 11 adult IDH mutant or IDH wild-type gliomas to delineate sources of intratumoral heterogeneity. We showed that local DNA methylation disorder is associated with cell-cell DNA methylation differences, is elevated in more aggressive tumors, links with transcriptional disruption and is altered during the environmental stress response. Glioma cells under in vitro hypoxic and irradiation stress increased local DNA methylation disorder and shifted cell states. We identified a positive association between genetic and epigenetic instability that was supported in bulk longitudinally collected DNA methylation data. Increased DNA methylation disorder associated with accelerated disease progression and recurrently selected DNA methylation changes were enriched for environmental stress response pathways. Our work identified an epigenetically facilitated adaptive stress response process and highlights the importance of epigenetic heterogeneity in shaping therapeutic outcomes.

Radiotherapy is associated with a deletion signature that contributes to poor outcomes in patients with cancer.

Ionizing radiation causes DNA damage and is a mainstay for cancer treatment, but understanding of its genomic impact is limited. We analyzed mutational spectra following radiotherapy in 190 paired primary and recurrent gliomas from the Glioma Longitudinal Analysis Consortium and 3,693 post-treatment metastatic tumors from the Hartwig Medical Foundation. We identified radiotherapy-associated significant increases in the burden of small deletions (5-15 bp) and large deletions (20+ bp to chromosome-arm length). Small deletions were characterized by a larger span size, lacking breakpoint microhomology and were genomically more dispersed when compared to pre-existing deletions and deletions in non-irradiated tumors. Mutational signature analysis implicated classical non-homologous end-joining-mediated DNA damage repair and APOBEC mutagenesis following radiotherapy. A high radiation-associated deletion burden was associated with worse clinical outcomes, suggesting that effective repair of radiation-induced DNA damage is detrimental to patient survival. These results may be leveraged to predict sensitivity to radiation therapy in recurrent cancer.

Spatial concordance of DNA methylation classification in diffuse glioma.

BACKGROUND: Intratumoral heterogeneity is a hallmark of diffuse gliomas. DNA methylation profiling is an emerging approach in the clinical classification of brain tumors. The goal of this study is to investigate the effects of intratumoral heterogeneity on classification confidence. METHODS: We used neuronavigation to acquire 133 image-guided and spatially separated stereotactic biopsy samples from 16 adult patients with a diffuse glioma (7 IDH-wildtype and 2 IDH-mutant glioblastoma, 6 diffuse astrocytoma, IDH-mutant and 1 oligodendroglioma, IDH-mutant and 1p19q codeleted), which we characterized using DNA methylation arrays. Samples were obtained from regions with and without abnormalities on contrast-enhanced T1-weighted and fluid-attenuated inversion recovery MRI. Methylation profiles were analyzed to devise a 3-dimensional reconstruction of (epi)genetic heterogeneity. Tumor purity was assessed from clonal methylation sites. RESULTS: Molecular aberrations indicated that tumor was found outside imaging abnormalities, underlining the infiltrative nature of this tumor and the limitations of current routine imaging modalities. We demonstrate that tumor purity is highly variable between samples and explains a substantial part of apparent epigenetic spatial heterogeneity. We observed that DNA methylation subtypes are often, but not always, conserved in space taking tumor purity and prediction accuracy into account. CONCLUSION: Our results underscore the infiltrative nature of diffuse gliomas and suggest that DNA methylation subtypes are relatively concordant in this tumor type, although some heterogeneity exists.

Vaping disrupts ventilation-perfusion matching in asymptomatic users.

Inhalation of e-cigarette's aerosols (vaping) has the potential to disrupt pulmonary gas exchange, but the effects in asymptomatic users are unknown. We assessed ventilation-perfusion (V̇A/Q̇) mismatch in asymptomatic e-cigarette users, using magnetic resonance imaging (MRI). We hypothesized that vaping induces V̇A/Q̇ mismatch through alterations in both ventilation and perfusion distributions. Nine young, asymptomatic "Vapers" with >1-yr vaping history, and no history of cardiopulmonary disease, were imaged supine using proton MRI, to assess the right lung at baseline and immediately after vaping. Seven young "Controls" were imaged at baseline only. Relative dispersion (SD/means) was used to quantify the heterogeneity of the individual ventilation and perfusion distributions. V̇A/Q̇ mismatch was quantified using the second moments of the ventilation and perfusion versus V̇A/Q̇ ratio distributions, log scale, LogSDV̇, and LogSDQ̇, respectively, analogous to the multiple inert gas elimination technique. Spirometry was normal in both groups. Ventilation heterogeneity was similar between groups at baseline (Vapers, 0.43 ± 0.13; Controls, 0.51 ± 0.11; P = 0.13) but increased after vaping (to 0.57 ± 0.17; P = 0.03). Perfusion heterogeneity was greater (P = 0.04) in Vapers at baseline (0.53 ± 0.06) compared with Controls (0.44 ± 0.10) but decreased after vaping (to 0.42 ± 0.07; P = 0.005). Vapers had greater (P = 0.01) V̇A/Q̇ mismatch at baseline compared with Controls (LogSDQ̇ = 0.61 ± 0.12 vs. 0.43 ± 0.12), which was increased after vaping (LogSDQ̇ = 0.73 ± 0.16; P = 0.03). V̇A/Q̇ mismatch is greater in Vapers and worsens after vaping. This suggests subclinical alterations in lung function not detected by spirometry.NEW & NOTEWORTHY This research provides evidence of vaping-induced disruptions in ventilation-perfusion matching in young, healthy, asymptomatic adults with normal spirometry who habitually vape. The changes in ventilation and perfusion distributions, both at baseline and acutely after vaping, and the potential implications on hypoxic vasoconstriction are particularly relevant in understanding the pathogenesis of vaping-induced dysfunction. Our imaging-based approach provides evidence of potential subclinical alterations in lung function below thresholds of detection using spirometry.

Comparative Molecular Life History of Spontaneous Canine and Human Gliomas.

Sporadic gliomas in companion dogs provide a window on the interaction between tumorigenic mechanisms and host environment. We compared the molecular profiles of canine gliomas with those of human pediatric and adult gliomas to characterize evolutionarily conserved mammalian mutational processes in gliomagenesis. Employing whole-genome, exome, transcriptome, and methylation sequencing of 83 canine gliomas, we found alterations shared between canine and human gliomas such as the receptor tyrosine kinases, TP53 and cell-cycle pathways, and IDH1 R132. Canine gliomas showed high similarity with human pediatric gliomas per robust aneuploidy, mutational rates, relative timing of mutations, and DNA-methylation patterns. Our cross-species comparative genomic analysis provides unique insights into glioma etiology and the chronology of glioma-causing somatic alterations.

Molecular and clonal evolution in recurrent metastatic gliosarcoma.

We discuss the molecular evolution of gliosarcoma, a mesenchymal type of glioblastoma (GBM), using the case of a 37-yr-old woman who developed two recurrences and an extracranial metastasis. She was initially diagnosed with isocitrate dehydrogenase (IDH) wild-type gliosarcoma in the frontal lobe and treated with surgery followed by concurrent radiotherapy with temozolomide. Five months later the tumor recurred in the left frontal lobe, outside the initially resected area, and was treated with further surgery and radiotherapy. Six months later the patient developed a second left frontal recurrence and was again treated with surgery and radiotherapy. Six weeks later, further recurrence was observed in the brain and bone, and biopsy confirmed metastases in the pelvic bones. To understand the clonal relationships between the four tumor instances and the origin of metastasis, we performed whole-genome sequencing of the intracranial tumors and the tumor located in the right iliac bone. We compared their mutational and copy-number profiles and inferred the clonal phylogeny. The tumors harbored shared alterations in GBM driver genes, including mutations in TP53, NF1, and RB1, and CDKN2A deletion. Whole-genome doubling was identified in the first recurrence and the extracranial metastasis. Comparisons of the metastatic to intracranial tumors highlighted a high similarity in molecular profile but contrasting evidence regarding the origin of the metastasis. Subclonal reconstruction suggested a parallel evolution of the recurrent tumors, and that the metastatic tumor was largely derived from the first recurrence. We conclude that metastasis in glioma can be a late event in tumorigenesis.

Longitudinal molecular trajectories of diffuse glioma in adults.

The evolutionary processes that drive universal therapeutic resistance in adult patients with diffuse glioma remain unclear1,2. Here we analysed temporally separated DNA-sequencing data and matched clinical annotation from 222 adult patients with glioma. By analysing mutations and copy numbers across the three major subtypes of diffuse glioma, we found that driver genes detected at the initial stage of disease were retained at recurrence, whereas there was little evidence of recurrence-specific gene alterations. Treatment with alkylating agents resulted in a hypermutator phenotype at different rates across the glioma subtypes, and hypermutation was not associated with differences in overall survival. Acquired aneuploidy was frequently detected in recurrent gliomas and was characterized by IDH mutation but without co-deletion of chromosome arms 1p/19q, and further converged with acquired alterations in the cell cycle and poor outcomes. The clonal architecture of each tumour remained similar over time, but the presence of subclonal selection was associated with decreased survival. Finally, there were no differences in the levels of immunoediting between initial and recurrent gliomas. Collectively, our results suggest that the strongest selective pressures occur during early glioma development and that current therapies shape this evolution in a largely stochastic manner.

Lymphocytic ganglionitis leading to megacolon in lymphocyte-rich glioblastoma.

T-cell immune attack of cancer cells underlies the efficacy of immune checkpoint inhibitors in many cancer subtypes, but is not yet well established in the primary brain cancer glioblastoma. Immune checkpoint inhibitor treatments that disinhibit the immune system to enhance immune clearance of cancer have in rare cases resulted in T-cell attack of peripheral ganglia causing lymphocytic ganglionitis. In glioblastoma, lymphocytic ganglionitis has not been reported and checkpoint inhibitors are not routinely used. Here we report a case of glioblastoma not treated with checkpoint inhibitors in which the primary tumor and peripheral ganglia of the celiac and sympathetic chains, as well as myenteric plexus, are infiltrated by CD8+ cytotoxic T-cells. In addition to the marked lymphocytic infiltrates, this case is also notable for an unusually long survival (8 years) after diagnosis with glioblastoma, but an ultimately fatal outcome due to ileus. The findings suggest T-cell immune attack of glioblastoma may prolong survival, but also suggest T-cell autoimmune diseases such as lymphocytic ganglionitis could become a risk with the future use of immune-targeted therapies for glioblastoma.

Spontaneous regression of pancreatic cancer with liver metastases.

Spontaneous cancer regression is a rare event, scarcely reported among gastrointestinal malignancies. Pancreatic adenocarcinoma regression has been documented in five previous cases, none of which included liver metastases, and the mechanism by which this occurs is not known. A 56-year-old woman with history of discoid lupus, homocysteinemia and peripheral vascular disease was diagnosed with stage IV pancreatic ductal adenocarcinoma (PDA) metastatic to the liver. She received palliative chemotherapy with 5-fluorouracil, leucovorin, irinotecan and oxaliplatin (FOLFIRINOX) for 6 months, complicated by mucositis, diarrhoea, vomiting and two Clostridium difficile colitis episodes. Cancer initially responded to chemotherapy. However, due to substantial toxicities, she decided to discontinue cytotoxic chemotherapy and focus on palliation alone. Thereafter, CT and carbohydrate antigen (CA) 19-9 showed further response and ultimately complete cancer regression that has persisted for 33 months after cessation of chemotherapy. This is the first report in the English literature showing spontaneous regression of a PDA with liver metastases. Two possible mechanisms are proposed: antitumoral autoimmunity and tumour hypoxia related to vascular disease.

Visceral Pleural Invasion in Pulmonary Adenocarcinoma: Differences in CT Patterns between Solid and Subsolid Cancers.

PURPOSE: To analyze the incidence and CT patterns of visceral pleural invasion (VPI) in adenocarcinomas on the basis of their CT presentation as solid or subsolid nodules. MATERIALS AND METHODS: A total of 286 adenocarcinomas in direct contact with a pleural surface, resected at an institution between 2005 and 2016, were included in this retrospective, institutional review board-approved study. CT size and longest contact length with a pleural surface were measured and their ratios computed. Pleural deviation, pleural thickening, spiculations, different pleural tag types, pleural effusion, and the CT appearance of transgression into an adjacent lobe or infiltration of surrounding tissue were evaluated. Fisher exact tests and simple and multiple logistic regression models were used. RESULTS: Of the 286 nodules, 179 of 286 (62.6%) were solid and 107 of 286 (37.4%) were subsolid. VPI was present in 49 of 286 (17.1%) nodules and was significantly more frequent in solid (44 of 179; 24.6%) than in subsolid nodules (five of 107; 4.7%; P < .001). In solid nodules, multiple regression analysis showed an association of higher contact length-to-size ratio (adjusted odds ratio [OR], 1.02; P = .007) and the presence of multiple pleural tag types (adjusted OR, 5.88; P = .002) with VPI. In subsolid nodules, longer pleural contact length of the solid nodular component (adjusted OR, 1.27; P = .017) and the CT appearance of transgression or infiltration (adjusted OR, 10.75; P = .037) were associated with VPI. CONCLUSION: During preoperative evaluation of adenocarcinomas for the likelihood of VPI, whether a tumor manifests as a solid or a subsolid nodule is important to consider because the incidence of VPI is significantly higher in solid than in subsolid nodules. In addition, this study showed that the CT patterns associated with VPI differ between solid and subsolid nodules.© RSNA, 2019Supplemental material is available for this article.See also the commentary by Elicker in this issue.

Low- vs. High-Dose Neoadjuvant Radiation in Trimodality Treatment of Locally Advanced Esophageal Cancer.

BACKGROUND: The optimal dose of neoadjuvant radiation for locally advanced, resectable esophageal cancer remains controversial in the absence of randomized clinical trials, with conventional practice favoring the use of 50.4 vs. 41.4 Gy. METHODS: Retrospective analysis of adults with non-metastatic esophageal cancer in the National Cancer Database (2004-2015) treated with neoadjuvant chemoradiotherapy. Outcomes were compared between patients undergoing 41.4, 45, or 50.4 Gy. Primary outcome was overall survival. Secondary outcomes included T and N downstaging and perioperative mortality adjusted for demographics, clinicopathologic factors, and facility volume. RESULTS: Eight thousand eight hundred eighty-one patients were included: 439 (4.9%) received low-dose (41.4 Gy), 2194 (24.7%) received moderate-dose (45 Gy), and 6248 (70.4%) received high-dose (50.4 Gy) neoadjuvant radiation. Compared to high-dose, low-dose radiation was associated with superior median overall survival (52.6 vs. 40.7 months) and 5-year survival (48.3% vs. 40.2%), and lower unadjusted 90-day mortality (2.3% vs. 6.5%, all p ≤ 0.01). Multivariable proportional hazards models confirmed an increased hazard of death associated with high-dose radiation therapy (HR = 1.38, 95% CI 1.10-1.72, p = 0.005). There was no significant difference in T and/or N downstaging between low-dose vs. high-dose therapy (p > 0.1 for both). Patients receiving 45 Gy exhibited the lowest median overall survival (37.2 months) and 5-year survival (38.7%, log-rank p = 0.04). CONCLUSIONS: Compared to 50.4 Gy, 41.4 Gy is associated with reduced perioperative mortality and superior overall survival with similar downstaging in locally advanced esophageal cancer. In the absence of randomized clinical data, our findings support the use of 41.4 Gy in patients with chemoradiation followed by esophagectomy. Prospective trials are warranted to further validate these results.

Pathologic T Descriptor of Nonmucinous Lung Adenocarcinomas Now Based on Invasive Tumor Size: How Should Pathologists Measure Invasion?

OBJECTIVES: The eighth edition of the American Joint Committee on Cancer staging manual now stratifies nonmucinous lung adenocarcinomas (nmLACAs) by the size of the invasive component only. This is determined by direct gross or microscopic measurement; however, a calculated invasive size based on the percentage of invasive growth patterns has been proposed as an alternative option. METHODS: To compare radiologic with different pathologic assessments of invasive tumor size, we retrospectively reviewed a cohort of resected nmLACAs with a part-solid appearance on computed tomography (CT) scan (n = 112). RESULTS: The median direct microscopic pathologic invasive measurements were not significantly different from the median calculated pathologic invasive measurements; however, the median CT invasive measurements were 0.26 cm larger than the median direct pathologic measurements (P < .001). CONCLUSIONS: Our results show that pathologic calculated invasive tumor measurements are comparable to direct microscopic measurements of invasive tumor, thereby supporting the recommendation for use of calculated invasive tumor size by the pathologist if necessary.

Synchronous granular cell tumors of the pancreas and cecum.

Granular cell tumors (GCT) are rare and typically benign. Diagnosis is challenging due to nonspecific imaging characteristics and symptomatology. Herein, we report a combination of pancreatic/cecal GCTs in a 43-year-old man. Contrast enhanced MDCT demonstrated a 1.5 cm well-defined homogeneous intraluminal cecal mass and a 1.6 cm slightly hypervascular pancreatic body mass. On MRI, the pancreatic mass showed increased enhancement on post-gadolinium delayed sequences. Diagnosis was confirmed by excisional pathology (S100 and CD68, PAS-D positive). Radiologists, gastroenterologists, and surgeons should ponder the possibility of GCTs in the differential diagnosis of any small, pancreatic or cecal well-defined tumor.

Behavioral and neurochemical responses derived from dopaminergic intrastriatal grafts in hemiparkinsonian rats engaged in a novel motor task.

BACKGROUND: Putative treatments derived from in vivo stem cell transplant-derived dopamine (DA) in hemiparkinsonian rats have been assessed via DA-agonist-induced rotations involving imbalanced intra-hemispheric striatal DA receptor stimulation. However, such tests obscure the natural responses of grafts to sensory stimuli, and drug-induced plasticity can modify the circuit being tested. Thus, we propose an alternative testing strategy using a novel water tank swimming apparatus. NEW METHOD: Microdialysis was used to compare striatal DA levels when rats were: (1) in a rest-phase within a bowl-shaped apparatus, or (2) in an active forced-swim phase within a specially-equipped water tank. Resting-phase DA release levels were compared with active-phase levels obtained while rats were required to swim in the water-tank task. Behavioral variables such as asymmetric circling while swimming (rotations), front-limb strokes, and front-limb reaches were captured by a camera for analysis. RESULTS AND COMPARISON WITH EXISTING METHODS: Transplanted cells had a very modest effect on percentage of contralateral front-limb strokes, but did not reduce lesion-induced rotational asymmetry in the swim task. Neither striatal DA levels, nor their breakdown products, were significantly different between transplanted and sham-transplanted groups. Our new behavioral test eliminates the need for pharmacological stimulation, enabling simultaneous assessment of DA released in resting and active phases to explore graft control. CONCLUSIONS: Our new method allows for accurate assessments of stem cell therapy for PD as an alternative to "rotation" tests. Use of natural motivations to engage in sensory-driven motor tasks provides more accurate insights into ongoing graft-derived behavioral support.