Weeks Of Ablation Research Articles

Melanin-concentrating hormone neurons affect adipose tissues and modulate weight gain.

Melanin-concentrating hormone neurons affect adipose tissues and modulate weight gain.

Su2027 Regeneration of Myenteric Neurons Following Low Concentration Benzylkonium Chloride Is Associated With Increased Expression of Sox2

Background: Application of the surfactant benzylkonium chloride (BAC) to the serosal surface of the intestine causes ablative neurodegeneration within two days. Modest neurogenesis within 4-8 weeks of ablation has been observed in this model with neurons derived from glial precursors. We hypothesized that non-ablative concentrations of BAC would spare potential neural precursors and allow a more robust neuroregeneration. Aims: To determine whether low concentration BAC causes neurodegeneration and subsequent neurogenesis and whether markers of neural progenitors are expressed following BAC treatment. Methods: In C57Bl/6 mice, following laparotomy, a 1x0.2cm piece of absorbent paper soaked in 0.0001% BAC was applied to the serosal surface of the jejunum for 5 min. Following various periods of recovery, fixed segments of the external muscle layers were immunostained for HuC/D (mature enteric neurons), S100β (enteric glia), doublecortin (DCX; immature neurons), and/or SOX2 (neural pluripotency transcription factor). Immunoreactive (IR) cells were enumerated as the number of cells per ganglion. In some mice, EdU (100mg/kg IP) was administered daily between 12-16d post-BAC before animals were euthanized 21d postBAC. Results: In mice two days after BAC treatment there was a significant reduction in the number of HuC/D-IR cells per ganglion in the region of treatment (27 ± 8) compared to an orally-adjacent region (61 ± 7; P<0.05). In mice 21 days after BAC treatment, the number of neurons per ganglion in the treated region (45 ± 5) were no longer significantly less than the orally-adjacent region (61 ± 6; P<0.05). There was no evidence for EdU incorporation in HuC/D-IR cells. Although DCX-IR was detected in the rostral migratory stream of the CNS, DCX-IR was rarely detected in the myenteric plexus. SOX2-IR was increased in HuC/ D-IR neurons at 21d post-BAC. SOX2-IR was detected in S100β-IR cells as early as 2d postBAC and S100β-IR was detected in a proportion of HuC/D-IR cells in the BAC-treated region between 2-14d post-BAC. Conclusion: Low concentration BAC caused moderate neurodegeneration in the myenteric plexus of the mouse jejunum. The number of myenteric neurons increased by 21d post-BAC. The pluripotency transcription factor SOX2, which in the CNS is capable of reprogramming astrocytes to mature neurons, is expressed in enteric glial cells early following BAC treatment and in a proportion of mature neurons by 21d post-BAC. These data support the concept of neuroregeneration of the enteric nervous system, and suggest that SOX2 expression in enteric glia may drive adult neurogenesis without cell proliferation.

Su2029 Medium Conditioned With Conventionally-Activated M1 Macrophages Inhibits Survival of Mouse Interstitial Cells of Cajal in Primary Culture

Background: Application of the surfactant benzylkonium chloride (BAC) to the serosal surface of the intestine causes ablative neurodegeneration within two days. Modest neurogenesis within 4-8 weeks of ablation has been observed in this model with neurons derived from glial precursors. We hypothesized that non-ablative concentrations of BAC would spare potential neural precursors and allow a more robust neuroregeneration. Aims: To determine whether low concentration BAC causes neurodegeneration and subsequent neurogenesis and whether markers of neural progenitors are expressed following BAC treatment. Methods: In C57Bl/6 mice, following laparotomy, a 1x0.2cm piece of absorbent paper soaked in 0.0001% BAC was applied to the serosal surface of the jejunum for 5 min. Following various periods of recovery, fixed segments of the external muscle layers were immunostained for HuC/D (mature enteric neurons), S100β (enteric glia), doublecortin (DCX; immature neurons), and/or SOX2 (neural pluripotency transcription factor). Immunoreactive (IR) cells were enumerated as the number of cells per ganglion. In some mice, EdU (100mg/kg IP) was administered daily between 12-16d post-BAC before animals were euthanized 21d postBAC. Results: In mice two days after BAC treatment there was a significant reduction in the number of HuC/D-IR cells per ganglion in the region of treatment (27 ± 8) compared to an orally-adjacent region (61 ± 7; P<0.05). In mice 21 days after BAC treatment, the number of neurons per ganglion in the treated region (45 ± 5) were no longer significantly less than the orally-adjacent region (61 ± 6; P<0.05). There was no evidence for EdU incorporation in HuC/D-IR cells. Although DCX-IR was detected in the rostral migratory stream of the CNS, DCX-IR was rarely detected in the myenteric plexus. SOX2-IR was increased in HuC/ D-IR neurons at 21d post-BAC. SOX2-IR was detected in S100β-IR cells as early as 2d postBAC and S100β-IR was detected in a proportion of HuC/D-IR cells in the BAC-treated region between 2-14d post-BAC. Conclusion: Low concentration BAC caused moderate neurodegeneration in the myenteric plexus of the mouse jejunum. The number of myenteric neurons increased by 21d post-BAC. The pluripotency transcription factor SOX2, which in the CNS is capable of reprogramming astrocytes to mature neurons, is expressed in enteric glial cells early following BAC treatment and in a proportion of mature neurons by 21d post-BAC. These data support the concept of neuroregeneration of the enteric nervous system, and suggest that SOX2 expression in enteric glia may drive adult neurogenesis without cell proliferation.

Phase I Study Demonstrates Safety and Tolerability of Radiofrequency Ablation (RFA) of the Anal Mucosa

Background Anal carcinoma is increasing in high-risk populations. Dysplasia is often distributed throughout the anal mucosa, and focal ablative techniques have high rates of recurrence. Methods With the goal of eradicating dysplasia from the entire anal mucosa, we conducted a phase I dose-ranging study to determine the safety and tolerability of radiofrequency ablation (RFA). HIV-infected individuals with high-grade anal intraepithelial neoplasia underwent RFA of the anal mucosa. Patient-reported procedural and postprocedural symptoms were recorded, and mucosal healing was visually assessed. Results Four groups of 3 subjects each were treated with incrementally increasing numbers of RF pulses (1-3) applied to a single area of anal mucosa. Two or three doses of 12 J/cm2 were found to have acceptable patient tolerance and healing of the mucosa within 4 weeks of ablation. Using these doses, 2 groups underwent ablation of 180° of contiguous mucosa. Subjects experienced a loss of 1 to 3 days of daily activities of living, 7 to 14 days of postprocedure symptoms, and mucosal healing within 4 weeks. One subject in the first treatment group had the procedure aborted due to severe procedural pain. Conclusions The study provides evidence of the safety and tolerability of anal RFA of 180° of contiguous mucosa in a single procedure and will allow future RFA efficacy studies in the treatment of anal dysplasia.