- Email: [email protected]
Mo2027 Comparison of Chronic Radiation Proctopathy After Brachytherapy Alone and in Combination With External-Beam Radiotherapy for Prostate Cancer
Mo2026
miR-378 Attenuates Intestinal Ischemia /Reperfusion Injury by Inhibiting Intestinal Mucosal Apoptosis via Targeting Caspase-3 Signaling Yunsheng Li, Weifeng Liu, Wenjing Yang, XuYu Zhang, ShiHong Wen, Kexuan Liu
Pelvic Radiation Disease - How Common Are Multiple Underlying Diagnoses? Rhodri Stacey, Bryony Cox, Jeff Turner, John Green Recent developments in the treatment of cancer have led to a threefold rise in the number of cancer survivors in the UK. Pelvic radiotherapy, although effective as a treatment against cancer, is well known to have severe late effects, which can significantly affect patient's quality of life. We have begun to develop a specialized service for these patients with Pelvic Radiation Disease (PRD) and have been using a systematic algorithm published in recent guidelines1 to aid our management. Although it is recognized that multiple gastrointestinal conditions can co-exist in PRD, there is little data in the literature to state how common these multiple diagnoses are. We identified 88 patients (55% female, 45% male, median age 76) referred to gastroenterology clinic in Cardiff, United Kingdom, with symptoms of suspected pelvic radiation disease, all of whom had previously received radiotherapy. A database search and examination of electronic patient records was used to identify cases. Patients were managed as per recent guidelines. Some patients did not receive all appropriate tests due to failure to attend appointments / patient choice. The four most common symptoms were diarrhea, rectal bleeding, abdominal pain and bloating. 65 patients (73.86%) had one or more causes found for their symptoms. 18 patients (20.45%) had more than on diagnosis made (i.e. had dual pathology). 7 patients (7.95%) had three or more pathologies identified. Diarrhoea, bloating and abdominal pain were more commonly associated with multiple underlying diagnoses than rectal bleeding. Table 1 outlines the number and percentage of patients with multiple diagnoses by underlying diagnosis, whereas table 2 outlines the number and percentage of patients with multipe diagnoses by presenting symptom. Pelvic radiation disease is common. Amongst patients with PRD, dual pathologies frequently coexist to cause a compound effect on symptoms. This is particularly true of patients with diarrhea and bloating. A systematic approach to these patients is beneficial and avoids missing potentially treatable conditions that can heavily impact upon quality of life. 1. Andreyev HJN, Muls AC, Norton C, Ralph C, Watson L, Shaw C, et al. Guidance: The practical management of the gastrointestinal symptoms of pelvic radiation disease. Frontline Gastroenterology. 2014 Jun 17. Table 1 - Numbers and % of patients with multiple diagnoses by underlying diagnosis
Background and objective: Intestinal ischemia-reperfusion (I/R) injury is a serious clinical setting which is associated with a high morbidity and mortality. Previous studies show apoptosis is the major mode of intestinal mucosal cell death induced by I/R injury. Recent studies show that miRNA played an important role in cardiac, cerebral, renal I/R injury, and their role was related to apoptosis. The changes of miRNA expression in the intestinal mucosal tissue after intestinal I/R injury are unclear. Thus, studies are needed to better understand the characterization of miRNA expression and their function involved in intestinal I/R injury. Methods and results: miRNA analysis was performed to identify different miRNAs expression in mice intestine subjected to 60 min ischemia follow by 120 min reperfusion. MiR-378, one of miRNAs down-regulated by I/R, was further verified by quantitative RTPCR. Next, we used agomir/ antagomir or mimic/inhibitor to increase or decrease the expression of miR-378 in mice and IEC-6 cells respectively. Using TUNEL and flow cytometric analysis respectively, we found overexpression miR-378 protected intestine from I/R injury both in vivo and vitro by inhibiting intestinal mucosal apoptosis. Further more, we used TG mice which overexpressed miR-378 to repeat the experiments and had the same results. We also found overexpression miR-378 reduced expression of caspase-3 both in vivo and in vitro. Finally, the luciferase reporter revealed that caspase-3 was a target of miR-378, this indicated that miR-378 inhibited the synthesis of caspase-3 proteins through posttranscriptional mechanisms. In summary, miR-378 attenuated intestinal I/R injury by inhibiting intestinal mucosal apoptosis via targeting caspase-3 signaling. Conclusions: These findings provide new insights into the molecular basis of diseases related to intestinal I/R injury and point to miR-378 as a potential therapeutic target in these settings.
Table 2 - Number of patients with multiple diagnoses by symptom
The effects of miR-378
Mo2027 Comparison of Chronic Radiation Proctopathy After Brachytherapy Alone and in Combination With External-Beam Radiotherapy for Prostate Cancer Masahiro Ohtani, Hiroyuki Suto, Hidetaka Matsuda, Katsushi Hiramatsu, Tomoyuki Nemoto, Yasunari Nakamoto Background and aims: Radiotherapy plays a pivotal role in management of prostate cancer. Brachytherapy (BT) alone or in combination with external-beam radiotherapy (EBRT) was undergone based on prostate cancer risk groups. Chronic radiation proctopathy is a late complication following radiotherapy for pelvic malignancies. We compared the influence of three different radiotherapy modalities on pathology and endoscopic features of radiation proctopathy. Methods: On hundred twenty-one patients with localized prostate cancer were received BT as a monotherapy (group A, n=47), BT as a boost after EBRT (group B, n=21) and BT followed by EBRT (group C, n=53). BT was performed with permanent seed implantation and EBRT dose was 44-50 Gy. Rectal toxicity was evaluated with a modified Radiation Therapeutic Oncology Group 5-garde rectal bleeding scale. We retrospectively investigated 5-year incidence, endoscopic findings, and treatment outcomes of radiation proctopathy in patients with prostate cancer. Endoscopic findings of radiation proctopathy were assessed using Vienna Rectoscopy Score (VRS). Statistical analyses were performed using Student's t test and Kruskal-Wallis test followed by Mann-Whitney U test. Results: The 5-year grade 1 rectal bleeding rates were 6.3% in group A, 33.3% in group B, and 39.6% in group C. Grade 2-4 rectal bleeding rates were 4.2 % in group A, 19.0% in group B, and 26.4% in group C. The risk of rectal bleeding in group A was significantly lower than that in group B and group C (p < 0.05). The time to development of rectal bleeding post BT in group C (64.4 weeks) is significantly shorter than that in group A (92.4 weeks, p < 0.05) ant group B (86.5 weeks, p < 0.05). VRS scores of patients with rectal toxicity ≥ grade 1 in group C (2.31) was significantly higher than those in group A (1.00, p < 0.05) and group B (1.45, p < 0.05). Argon plasma coagulation therapy or hyperbaric oxygen therapy for rectal bleeding were effective, and these treatments were performed in 9.5% of patients in group B, and
The luciferase reporter:caspase-3 is a target of miR-378{BR}
S-773
AGA Abstracts
AGA Abstracts
Mo2025
AGA Abstracts
11.3% in group C. Conclusions BT monotherapy had a significantly lower risk of radiation proctopathy compared to BT in combination with EBRT. BT followed by EBRT boost increased endoscopic severity of radiation proctopathy compared to BT boost after EBRT. These findings may allow one to decrease rectal morbidity caused by radiotherapy for prostate cancer.
Table 1
Mo2028 A Functional Approach to Improve Barrier Function in Irradiated Mice Lauren Vaught, Liangjie Yin, Astrid Grosche, Amy Zhang, Paul Okunieff, Sadasivan Vidyasagar Tight junctions are formed by mature enterocytes and create an efficient barrier that has the necessary machinery for electrolyte and nutrient absorption. Radiotherapy causes epithelial barrier dysfunction leading to increased macromolecular translocation into the systemic compartment causing endotoxemia and inflammatory response. Recently, it was shown that glucose and some amino acids (AAs) activated active anion secretion and/ or increased paracellular permeability, whereas our mitigating amino acids mixture (MAAM) comprised of lysine, glycine, tryptophan, tyrosine, aspartic acid, isoleucine, threonine, valine, and serine increased electrolyte absorption and decreased paracellular permeability. The mechanism by which these amino acids tightened the mucosal barrier was not known. Therefore, studies were undertaken to determine the mechanism by which MAAM tightened the mucosal barrier. NIH Swiss mice were irradiated using a 137Cs source. Radiation dose-dependent and time-dependent (0, 6, 12, 24, 48, 72, and 144 hr after irradiation) changes in transepithelial electrical resistance (TEER) and dilution potential (DP) and the relative permeability of Cl- and Na+ (PCl/PNa) were measured. Transmission electron microscopy (TEM) images, Western blot analysis, and immunohistochemistry (IHC) for the cell junction protein complex (Claudin 1, 2, 5, Nectin, and E-cadherin) were performed at similar time points. Radiation resulted in a dose-dependent increase in conductance (43.3 ± 1.2, 29.5 ± 1.2, 48.2 ± 2.3, 48.9 ± 1.7, 38.7 ± 1.2 mS at 0, 1, 3, 5, 7 Gy, respectively). Similarly, time-dependent changes in conductance showed a maximal increase occurring in the first 6 hr (46.3 ± 1.5); there was no significant difference with increasing time after irradiation. Treatment with MAAM resulted in a significant decrease in conductance. DP studies showed that MAAM restored ion selectivity. TEM showed disruption of the cell junction complex and formation of clear space between the cells as early as 6 hr after irradiation. The changes persisted for the duration of the experiment (6 days). MAAM prevented cell junction disruption in mice; this was identifiable at 6 hr after irradiation. Western analysis and IHC showed a radiation dose-dependent increase in Claudin 1, 2, 5, Nectin, and E-cadherin except at 7 Gy. MAAM further increased Claudin 1, 2, 5, Nectin, and E-cadherin across all radiation doses. MAAM treatment decreased paracellular permeability. TEM showed disruption of the cell junction complex that peaked at 6 hours and was corrected using MAAM. Western analysis and IHC showed that radiation-induced alterations in the cell junction protein complex were further corrected in the MAAM group. We conclude that the disruption in the barrier results from changes in the cell junction complex and that MAAM restores the barrier function by correcting these changes.
Mo2030 Neurobiology of Psychological Resilience in Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Disease (IBD) Patients Lisa A. Kilpatrick, Arpana Gupta, Aubrey D. Love, Jennifer S. Labus, Mher Alaverdyan, Kirsten Tillisch, Bruce D. Naliboff, Emeran A. Mayer BACKGROUND: Resilience is commonly defined as the process of adapting well in the face of adversity. Stressful life events have been associated with the onset or symptom exacerbation of gstrointestinal disorders such as IBS as well as inflammatory bowel disease IBD. A better understanding of the neural circuitry associated with enhanced or deficient resilience holds promise for the development of new interventions to improve health. AIMS: To examine structural brain changes associated with psychological resilience in male and female IBS and IBD patients compared to healthy controls (HCs). We hypothesized that reduced resilience in pain populations would be associated with alterations in emotionarousal related brain regions. METHODS: 48 HCs (33 female), 54 IBS patients (43 females) and 27 IBD patients (14 females) completed MRI scans and resilience questionnaires. The questionnaires consisted of the Brief Resilience Scale (BRS) and the Connor-Davidson Resilience (CD-RISC) scale. The CD-RISC was comprised of 4 factors representing (1) persistence, (2) emotional/cognitive control, (3) ability to bounce back, and (4) sense of control/meaning of one's life. Volume measures for 165 brain regions were calculated and entered into partial least squares (PLS) analyses with the behavioral data. RESULTS: Male and female IBS patients demonstrated significantly reduced psychological resilience, particularly in terms of ‘bounce back'. While male IBD patients did not differ from HCs in terms of resilience; female IBD patients showed significantly reduced BRS scores. PLS identified a brain-behavior pattern (accounting for 34.4% cross-block variance; p=.05) demonstrating that reduced resilience in male IBS patients was related to decreased volume of a set of brain regions including: precuneus, rectal gyrus, anterior cingulate gyrus, postcentral gyrus and postcentral sulcus and increased volume of the brainstem. Male HCs and IBD patients did not demonstrate this brain-behavior pattern. For female subjects, PLS identified a brain-behavior pattern (accounting for 40.2% cross-block variance, p=.05) demonstrating that resilience in female HCs was associated with increased volume of the cerebellum and postcentral sulcus and decreased volume of the precuneus, insula, and orbital gyri. Female IBS patients failed to demonstrate this brain-behavior pattern while female IBD patients showed a similar pattern to HCs in terms of BRS but not CD-RISC. DISCUSSION: Reduced psychological resilience was more prominent in IBS patients than in IBD patients, particularly for males. IBS males demonstrated a relationship between reduced psychological resilience and decreased volume of brain regions associated with autonomic and emotional-arousal functions. Female subjects demonstrated different brain-behavior patterns, highlighting a need to consider sex in resilience research.
Mo2029 Differential Activity of NHE3 and NHE2 in the Small Intestine of Irradiated Mice Liangjie Yin, Lauren Vaught, Amy Zhang, Paul Okunieff, Sadasivan Vidyasagar Introduction: The major functions of the gastrointestinal (GI) tract are the mucosal barrier and the absorption of nutrients, electrolytes, and water. Electrolyte absorption occurs in fully mature and differentiated villus cells via coupled sodium-hydrogen exchange (NHE3) and chloride bicarbonate exchange (Cl-HCO3). Radiation targets rapidly dividing cells, such as cancer cells, and clonogenic cells located in the crypts, causing a decrease in proliferation, maturation, and differentiation that causes villus shortening. A decrease in villus height is therefore responsible for the diarrhea associated with radiation exposure. Also, it was previously shown that radiation increases intracellular calcium oscillations and cyclic adenosine monophosphate (cAMP) levels in enterocytes. Elevated intracellular cAMP is known to inhibit NHE3 and increase NHE2 activity. However, the effect of radiation on NHE3 and NHE2 is not known. Therefore, we investigated the effect of radiation on NHE2 and NHE3 activity in the GI tract. Methods: NIH Swiss mice were irradiated using a 137Cs source. The small intestinal mucosa of mice with 0, 1, 3, 5, or 7 Gy were studied on day 6. 22Na flux studies were undertaken to measure Na absorption. Relatively specific NHE2 inhibitor 5-(N-EthylN-isopropyl)amiloride (EIPA) and NHE3 inhibitor 5-(N,N-Hexamethylene)amiloride (HMA) were used to determine their activity. Immunohistochemistry and Western blot analysis were performed to study NHE2 and NHE3 protein and expression levels. Results: Radiation increased basal short circuit current (Isc) in a dose-dependent fashion until 5 Gy. At 7 Gy there was a marginal decrease when compared to 5 Gy. Isotope flux studies showed a radiation dose-dependent decrease in Na absorption. The addition of EIPA or HMA did not decrease the basal Isc across all radiation doses. HMA-inhibitable flux decreased with increasing radiation dose, while EIPA-inhibitable flux increased with increasing radiation dose. IHC showed that NHE3 and NHE2 expression occurs mostly along the brush boarder membrane of villus epithelial cells. NHE3 expression and its protein levels decreased with increasing radiation doses, while NHE2 expression and protein levels increased with increasing radiation doses. The maximal increase in NHE2 protein level was detected at 7 Gy. Conclusions: Radiation decreases sodium absorption and results in decreased expression of NHE3. A small but significant portion of the sodium flux in the small intestine of irradiated mice was maintained by NHE2 activity. NHE2 activity in the presence of radiation suggests a less efficient but alternate mechanism for sodium absorption.
AGA Abstracts
Mo2031 Involvement of Catechol-O-Methyltransferase Genetic Reduction in Murine Intestinal Dysmotility: A Possible Link Between Psychiatric Disorders and Irritable Bowel Syndrome Valentina Caputi, Ilaria Marsilio, Lucia Cavallo, Stefania A. Frizzo, Francesca Marinelli, Maddalena Mereu, Isabella Lante, Genny Orso, Francesco Papaleo, Maria Cecilia Giron Introduction. Irritable bowel syndrome (IBS) is a still poorly understood functional disorder, associated with significant psychological distress and psychiatric comorbidities in the absence of organic disease. Aim. Since psychiatric disorders and pain syndromes are associated to low catechol-O-methyltransferase (COMT) activity and these conditions are both related to IBS we assessed whether COMT genetic reduction affects enteric nervous system (ENS) homeostasis and intestinal function. Methods. Female COMT heterozygous (COMT+/-) and wild-type (COMT+/+) mice (12±2 weeks) were used and their genotypes were confirmed by PCR on mouse tail DNAs. In isolated ileum segments, mounted vertically in organ baths, changes in muscle tension were recorded by isometric transducers following charbacol (0.001-100 μM) or 60 mM KCl treatment, electric field stimulation (EFS, 1-40 Hz, in presence or absence of 1 μM tetrodotoxin or atropine) or non-adrenergic non-cholinergic (NANC) neurotransmission (EFS=20 Hz, 1 μM atropine and 1 μM guanethidine, with and without 0.1 mM L-NAME). In ileum whole mount preparations changes in neuronal markers, such as HuC/D and betaIII-tubulin, and in glia markers, S100beta and glial fibrillary acidic protein (GFAP) were determined by confocal immunofluorescence. Acetylcholinesterase and NADPH-diaphorase biochemical assays together with nNOS immunohistochemistry were performed to evaluate the integrity of ENS neurochemical code. Gastrointestinal transit were assessed after 30 minutes post intragastric administration of a fluorescent labeled dextran probe. Results. In vitro contractility studies have shown altered receptor and not-receptor mediated responses (-41±8% of Emax for carbachol and -38±5% of contraction to KCl, respectively) together with an altered neuronal cholinergic and nitrergic transmission (33±6% and +56±11% at 20 Hz, respectively) in COMT+/- mice. In the ENS of COMT+/mice the ileal distribution of S100beta and GFAP immunoreactivity was found significantly increased in myenteric ganglia. A reduced staining of acetylcholinesterase+ fibers (-26±3%) and NADPH-diaphorase+ neurons (-23±4%) together with an altered distribution of nNOS immunopositive neurons was found in COMT+/- mice compared to wild-type animals. The
S-774
miR-378 Attenuates Intestinal Ischemia /Reperfusion Injury by Inhibiting Intestinal Mucosal Apoptosis via Targeting Caspase-3 Signaling Yunsheng Li, Weifeng Liu, Wenjing Yang, XuYu Zhang, ShiHong Wen, Kexuan Liu
Pelvic Radiation Disease - How Common Are Multiple Underlying Diagnoses? Rhodri Stacey, Bryony Cox, Jeff Turner, John Green Recent developments in the treatment of cancer have led to a threefold rise in the number of cancer survivors in the UK. Pelvic radiotherapy, although effective as a treatment against cancer, is well known to have severe late effects, which can significantly affect patient's quality of life. We have begun to develop a specialized service for these patients with Pelvic Radiation Disease (PRD) and have been using a systematic algorithm published in recent guidelines1 to aid our management. Although it is recognized that multiple gastrointestinal conditions can co-exist in PRD, there is little data in the literature to state how common these multiple diagnoses are. We identified 88 patients (55% female, 45% male, median age 76) referred to gastroenterology clinic in Cardiff, United Kingdom, with symptoms of suspected pelvic radiation disease, all of whom had previously received radiotherapy. A database search and examination of electronic patient records was used to identify cases. Patients were managed as per recent guidelines. Some patients did not receive all appropriate tests due to failure to attend appointments / patient choice. The four most common symptoms were diarrhea, rectal bleeding, abdominal pain and bloating. 65 patients (73.86%) had one or more causes found for their symptoms. 18 patients (20.45%) had more than on diagnosis made (i.e. had dual pathology). 7 patients (7.95%) had three or more pathologies identified. Diarrhoea, bloating and abdominal pain were more commonly associated with multiple underlying diagnoses than rectal bleeding. Table 1 outlines the number and percentage of patients with multiple diagnoses by underlying diagnosis, whereas table 2 outlines the number and percentage of patients with multipe diagnoses by presenting symptom. Pelvic radiation disease is common. Amongst patients with PRD, dual pathologies frequently coexist to cause a compound effect on symptoms. This is particularly true of patients with diarrhea and bloating. A systematic approach to these patients is beneficial and avoids missing potentially treatable conditions that can heavily impact upon quality of life. 1. Andreyev HJN, Muls AC, Norton C, Ralph C, Watson L, Shaw C, et al. Guidance: The practical management of the gastrointestinal symptoms of pelvic radiation disease. Frontline Gastroenterology. 2014 Jun 17. Table 1 - Numbers and % of patients with multiple diagnoses by underlying diagnosis
Background and objective: Intestinal ischemia-reperfusion (I/R) injury is a serious clinical setting which is associated with a high morbidity and mortality. Previous studies show apoptosis is the major mode of intestinal mucosal cell death induced by I/R injury. Recent studies show that miRNA played an important role in cardiac, cerebral, renal I/R injury, and their role was related to apoptosis. The changes of miRNA expression in the intestinal mucosal tissue after intestinal I/R injury are unclear. Thus, studies are needed to better understand the characterization of miRNA expression and their function involved in intestinal I/R injury. Methods and results: miRNA analysis was performed to identify different miRNAs expression in mice intestine subjected to 60 min ischemia follow by 120 min reperfusion. MiR-378, one of miRNAs down-regulated by I/R, was further verified by quantitative RTPCR. Next, we used agomir/ antagomir or mimic/inhibitor to increase or decrease the expression of miR-378 in mice and IEC-6 cells respectively. Using TUNEL and flow cytometric analysis respectively, we found overexpression miR-378 protected intestine from I/R injury both in vivo and vitro by inhibiting intestinal mucosal apoptosis. Further more, we used TG mice which overexpressed miR-378 to repeat the experiments and had the same results. We also found overexpression miR-378 reduced expression of caspase-3 both in vivo and in vitro. Finally, the luciferase reporter revealed that caspase-3 was a target of miR-378, this indicated that miR-378 inhibited the synthesis of caspase-3 proteins through posttranscriptional mechanisms. In summary, miR-378 attenuated intestinal I/R injury by inhibiting intestinal mucosal apoptosis via targeting caspase-3 signaling. Conclusions: These findings provide new insights into the molecular basis of diseases related to intestinal I/R injury and point to miR-378 as a potential therapeutic target in these settings.
Table 2 - Number of patients with multiple diagnoses by symptom
The effects of miR-378
Mo2027 Comparison of Chronic Radiation Proctopathy After Brachytherapy Alone and in Combination With External-Beam Radiotherapy for Prostate Cancer Masahiro Ohtani, Hiroyuki Suto, Hidetaka Matsuda, Katsushi Hiramatsu, Tomoyuki Nemoto, Yasunari Nakamoto Background and aims: Radiotherapy plays a pivotal role in management of prostate cancer. Brachytherapy (BT) alone or in combination with external-beam radiotherapy (EBRT) was undergone based on prostate cancer risk groups. Chronic radiation proctopathy is a late complication following radiotherapy for pelvic malignancies. We compared the influence of three different radiotherapy modalities on pathology and endoscopic features of radiation proctopathy. Methods: On hundred twenty-one patients with localized prostate cancer were received BT as a monotherapy (group A, n=47), BT as a boost after EBRT (group B, n=21) and BT followed by EBRT (group C, n=53). BT was performed with permanent seed implantation and EBRT dose was 44-50 Gy. Rectal toxicity was evaluated with a modified Radiation Therapeutic Oncology Group 5-garde rectal bleeding scale. We retrospectively investigated 5-year incidence, endoscopic findings, and treatment outcomes of radiation proctopathy in patients with prostate cancer. Endoscopic findings of radiation proctopathy were assessed using Vienna Rectoscopy Score (VRS). Statistical analyses were performed using Student's t test and Kruskal-Wallis test followed by Mann-Whitney U test. Results: The 5-year grade 1 rectal bleeding rates were 6.3% in group A, 33.3% in group B, and 39.6% in group C. Grade 2-4 rectal bleeding rates were 4.2 % in group A, 19.0% in group B, and 26.4% in group C. The risk of rectal bleeding in group A was significantly lower than that in group B and group C (p < 0.05). The time to development of rectal bleeding post BT in group C (64.4 weeks) is significantly shorter than that in group A (92.4 weeks, p < 0.05) ant group B (86.5 weeks, p < 0.05). VRS scores of patients with rectal toxicity ≥ grade 1 in group C (2.31) was significantly higher than those in group A (1.00, p < 0.05) and group B (1.45, p < 0.05). Argon plasma coagulation therapy or hyperbaric oxygen therapy for rectal bleeding were effective, and these treatments were performed in 9.5% of patients in group B, and
The luciferase reporter:caspase-3 is a target of miR-378{BR}
S-773
AGA Abstracts
AGA Abstracts
Mo2025
AGA Abstracts
11.3% in group C. Conclusions BT monotherapy had a significantly lower risk of radiation proctopathy compared to BT in combination with EBRT. BT followed by EBRT boost increased endoscopic severity of radiation proctopathy compared to BT boost after EBRT. These findings may allow one to decrease rectal morbidity caused by radiotherapy for prostate cancer.
Table 1
Mo2028 A Functional Approach to Improve Barrier Function in Irradiated Mice Lauren Vaught, Liangjie Yin, Astrid Grosche, Amy Zhang, Paul Okunieff, Sadasivan Vidyasagar Tight junctions are formed by mature enterocytes and create an efficient barrier that has the necessary machinery for electrolyte and nutrient absorption. Radiotherapy causes epithelial barrier dysfunction leading to increased macromolecular translocation into the systemic compartment causing endotoxemia and inflammatory response. Recently, it was shown that glucose and some amino acids (AAs) activated active anion secretion and/ or increased paracellular permeability, whereas our mitigating amino acids mixture (MAAM) comprised of lysine, glycine, tryptophan, tyrosine, aspartic acid, isoleucine, threonine, valine, and serine increased electrolyte absorption and decreased paracellular permeability. The mechanism by which these amino acids tightened the mucosal barrier was not known. Therefore, studies were undertaken to determine the mechanism by which MAAM tightened the mucosal barrier. NIH Swiss mice were irradiated using a 137Cs source. Radiation dose-dependent and time-dependent (0, 6, 12, 24, 48, 72, and 144 hr after irradiation) changes in transepithelial electrical resistance (TEER) and dilution potential (DP) and the relative permeability of Cl- and Na+ (PCl/PNa) were measured. Transmission electron microscopy (TEM) images, Western blot analysis, and immunohistochemistry (IHC) for the cell junction protein complex (Claudin 1, 2, 5, Nectin, and E-cadherin) were performed at similar time points. Radiation resulted in a dose-dependent increase in conductance (43.3 ± 1.2, 29.5 ± 1.2, 48.2 ± 2.3, 48.9 ± 1.7, 38.7 ± 1.2 mS at 0, 1, 3, 5, 7 Gy, respectively). Similarly, time-dependent changes in conductance showed a maximal increase occurring in the first 6 hr (46.3 ± 1.5); there was no significant difference with increasing time after irradiation. Treatment with MAAM resulted in a significant decrease in conductance. DP studies showed that MAAM restored ion selectivity. TEM showed disruption of the cell junction complex and formation of clear space between the cells as early as 6 hr after irradiation. The changes persisted for the duration of the experiment (6 days). MAAM prevented cell junction disruption in mice; this was identifiable at 6 hr after irradiation. Western analysis and IHC showed a radiation dose-dependent increase in Claudin 1, 2, 5, Nectin, and E-cadherin except at 7 Gy. MAAM further increased Claudin 1, 2, 5, Nectin, and E-cadherin across all radiation doses. MAAM treatment decreased paracellular permeability. TEM showed disruption of the cell junction complex that peaked at 6 hours and was corrected using MAAM. Western analysis and IHC showed that radiation-induced alterations in the cell junction protein complex were further corrected in the MAAM group. We conclude that the disruption in the barrier results from changes in the cell junction complex and that MAAM restores the barrier function by correcting these changes.
Mo2030 Neurobiology of Psychological Resilience in Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Disease (IBD) Patients Lisa A. Kilpatrick, Arpana Gupta, Aubrey D. Love, Jennifer S. Labus, Mher Alaverdyan, Kirsten Tillisch, Bruce D. Naliboff, Emeran A. Mayer BACKGROUND: Resilience is commonly defined as the process of adapting well in the face of adversity. Stressful life events have been associated with the onset or symptom exacerbation of gstrointestinal disorders such as IBS as well as inflammatory bowel disease IBD. A better understanding of the neural circuitry associated with enhanced or deficient resilience holds promise for the development of new interventions to improve health. AIMS: To examine structural brain changes associated with psychological resilience in male and female IBS and IBD patients compared to healthy controls (HCs). We hypothesized that reduced resilience in pain populations would be associated with alterations in emotionarousal related brain regions. METHODS: 48 HCs (33 female), 54 IBS patients (43 females) and 27 IBD patients (14 females) completed MRI scans and resilience questionnaires. The questionnaires consisted of the Brief Resilience Scale (BRS) and the Connor-Davidson Resilience (CD-RISC) scale. The CD-RISC was comprised of 4 factors representing (1) persistence, (2) emotional/cognitive control, (3) ability to bounce back, and (4) sense of control/meaning of one's life. Volume measures for 165 brain regions were calculated and entered into partial least squares (PLS) analyses with the behavioral data. RESULTS: Male and female IBS patients demonstrated significantly reduced psychological resilience, particularly in terms of ‘bounce back'. While male IBD patients did not differ from HCs in terms of resilience; female IBD patients showed significantly reduced BRS scores. PLS identified a brain-behavior pattern (accounting for 34.4% cross-block variance; p=.05) demonstrating that reduced resilience in male IBS patients was related to decreased volume of a set of brain regions including: precuneus, rectal gyrus, anterior cingulate gyrus, postcentral gyrus and postcentral sulcus and increased volume of the brainstem. Male HCs and IBD patients did not demonstrate this brain-behavior pattern. For female subjects, PLS identified a brain-behavior pattern (accounting for 40.2% cross-block variance, p=.05) demonstrating that resilience in female HCs was associated with increased volume of the cerebellum and postcentral sulcus and decreased volume of the precuneus, insula, and orbital gyri. Female IBS patients failed to demonstrate this brain-behavior pattern while female IBD patients showed a similar pattern to HCs in terms of BRS but not CD-RISC. DISCUSSION: Reduced psychological resilience was more prominent in IBS patients than in IBD patients, particularly for males. IBS males demonstrated a relationship between reduced psychological resilience and decreased volume of brain regions associated with autonomic and emotional-arousal functions. Female subjects demonstrated different brain-behavior patterns, highlighting a need to consider sex in resilience research.
Mo2029 Differential Activity of NHE3 and NHE2 in the Small Intestine of Irradiated Mice Liangjie Yin, Lauren Vaught, Amy Zhang, Paul Okunieff, Sadasivan Vidyasagar Introduction: The major functions of the gastrointestinal (GI) tract are the mucosal barrier and the absorption of nutrients, electrolytes, and water. Electrolyte absorption occurs in fully mature and differentiated villus cells via coupled sodium-hydrogen exchange (NHE3) and chloride bicarbonate exchange (Cl-HCO3). Radiation targets rapidly dividing cells, such as cancer cells, and clonogenic cells located in the crypts, causing a decrease in proliferation, maturation, and differentiation that causes villus shortening. A decrease in villus height is therefore responsible for the diarrhea associated with radiation exposure. Also, it was previously shown that radiation increases intracellular calcium oscillations and cyclic adenosine monophosphate (cAMP) levels in enterocytes. Elevated intracellular cAMP is known to inhibit NHE3 and increase NHE2 activity. However, the effect of radiation on NHE3 and NHE2 is not known. Therefore, we investigated the effect of radiation on NHE2 and NHE3 activity in the GI tract. Methods: NIH Swiss mice were irradiated using a 137Cs source. The small intestinal mucosa of mice with 0, 1, 3, 5, or 7 Gy were studied on day 6. 22Na flux studies were undertaken to measure Na absorption. Relatively specific NHE2 inhibitor 5-(N-EthylN-isopropyl)amiloride (EIPA) and NHE3 inhibitor 5-(N,N-Hexamethylene)amiloride (HMA) were used to determine their activity. Immunohistochemistry and Western blot analysis were performed to study NHE2 and NHE3 protein and expression levels. Results: Radiation increased basal short circuit current (Isc) in a dose-dependent fashion until 5 Gy. At 7 Gy there was a marginal decrease when compared to 5 Gy. Isotope flux studies showed a radiation dose-dependent decrease in Na absorption. The addition of EIPA or HMA did not decrease the basal Isc across all radiation doses. HMA-inhibitable flux decreased with increasing radiation dose, while EIPA-inhibitable flux increased with increasing radiation dose. IHC showed that NHE3 and NHE2 expression occurs mostly along the brush boarder membrane of villus epithelial cells. NHE3 expression and its protein levels decreased with increasing radiation doses, while NHE2 expression and protein levels increased with increasing radiation doses. The maximal increase in NHE2 protein level was detected at 7 Gy. Conclusions: Radiation decreases sodium absorption and results in decreased expression of NHE3. A small but significant portion of the sodium flux in the small intestine of irradiated mice was maintained by NHE2 activity. NHE2 activity in the presence of radiation suggests a less efficient but alternate mechanism for sodium absorption.
AGA Abstracts
Mo2031 Involvement of Catechol-O-Methyltransferase Genetic Reduction in Murine Intestinal Dysmotility: A Possible Link Between Psychiatric Disorders and Irritable Bowel Syndrome Valentina Caputi, Ilaria Marsilio, Lucia Cavallo, Stefania A. Frizzo, Francesca Marinelli, Maddalena Mereu, Isabella Lante, Genny Orso, Francesco Papaleo, Maria Cecilia Giron Introduction. Irritable bowel syndrome (IBS) is a still poorly understood functional disorder, associated with significant psychological distress and psychiatric comorbidities in the absence of organic disease. Aim. Since psychiatric disorders and pain syndromes are associated to low catechol-O-methyltransferase (COMT) activity and these conditions are both related to IBS we assessed whether COMT genetic reduction affects enteric nervous system (ENS) homeostasis and intestinal function. Methods. Female COMT heterozygous (COMT+/-) and wild-type (COMT+/+) mice (12±2 weeks) were used and their genotypes were confirmed by PCR on mouse tail DNAs. In isolated ileum segments, mounted vertically in organ baths, changes in muscle tension were recorded by isometric transducers following charbacol (0.001-100 μM) or 60 mM KCl treatment, electric field stimulation (EFS, 1-40 Hz, in presence or absence of 1 μM tetrodotoxin or atropine) or non-adrenergic non-cholinergic (NANC) neurotransmission (EFS=20 Hz, 1 μM atropine and 1 μM guanethidine, with and without 0.1 mM L-NAME). In ileum whole mount preparations changes in neuronal markers, such as HuC/D and betaIII-tubulin, and in glia markers, S100beta and glial fibrillary acidic protein (GFAP) were determined by confocal immunofluorescence. Acetylcholinesterase and NADPH-diaphorase biochemical assays together with nNOS immunohistochemistry were performed to evaluate the integrity of ENS neurochemical code. Gastrointestinal transit were assessed after 30 minutes post intragastric administration of a fluorescent labeled dextran probe. Results. In vitro contractility studies have shown altered receptor and not-receptor mediated responses (-41±8% of Emax for carbachol and -38±5% of contraction to KCl, respectively) together with an altered neuronal cholinergic and nitrergic transmission (33±6% and +56±11% at 20 Hz, respectively) in COMT+/- mice. In the ENS of COMT+/mice the ileal distribution of S100beta and GFAP immunoreactivity was found significantly increased in myenteric ganglia. A reduced staining of acetylcholinesterase+ fibers (-26±3%) and NADPH-diaphorase+ neurons (-23±4%) together with an altered distribution of nNOS immunopositive neurons was found in COMT+/- mice compared to wild-type animals. The
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