David X. Jin

Lung specific expression of a human mutant p53 affects cell proliferation in transgenic mice

The human mutant p53(273H) has been shown inxa0vitro to have both dominant-negative and gain-of-function properties, as well as to retain partial DNA-binding and transcriptional activation functions. We have developed a line of transgenic mice in which the human mutant p53(273H) is expressed in a lung specific manner (p53+/+/TG). Crossing of the transgenic mice with p53 knockout mice led to generate mice with various genetic backgrounds. To evaluate the influence of p53 mutants in cell proliferation in mice lung tissue, we analyzed cell proliferation rate by Bromodeoxyuridine (BrdU) labeling and by expression of proliferating cell nuclear antigen (PCNA). BrdU analysis showed a 3.7-fold increase in the number of BrdU positive cells in the (p53−/+/TG) mice compared to the (p53−/+) mice, whereas no difference was observed in proliferation rate in the p53−/−/TG lungs as compared to p53−/− lungs. After the mice were treated with γ-irradiation, BrdU positive cells were absent from both the p53−/+/TG and p53−/+ mice, whereas a decrease in the rate of cell proliferation occurred in p53−/−/TG lungs as compared to p53−/− lungs. Real time PCR results indicated that the p53(273H) mutant did not retain the function to activate expression of p21WAF1/CIP1 in the transgenic mice. The above results indicate that overexpression of the human mutant p53(273H) inxa0vivo results in an increase in basal proliferation rate which requires the presence of wild type p53. Mutant p53(273H) may affect cell proliferation by interrupting murine endogenous p53 function.

The role of glucocorticoids for spiral ganglion neuron survival.

Glucocorticoids, which are steroidal stress hormones, have a broad array of biological functions. Synthetic glucocorticoids are frequently used therapeutically for many pathologic conditions, including diseases of the inner ear; however, their exact functions in the cochlea are not completely understood. Recent work has clearly demonstrated the presence of glucocorticoid signaling pathways in the cochlea and elucidated their protective roles against noise-induced hearing loss. Furthermore, indirect evidence suggests the involvement of glucocorticoids in age-related loss of spiral ganglion neurons and extensive studies in the central nervous system demonstrate profound effects of glucocorticoids on neuronal functions. With the advancement of recent pharmacologic and genetic tools, the role of these pathways in the survival of spiral ganglion neurons after noise exposure and during aging should be revealed.

Age-related neuronal loss in the cochlea is not delayed by synaptic modulation.

Age-related synaptic change is associated with the functional decline of the nervous system. It is unknown whether this synaptic change is the cause or the consequence of neuronal cell loss. We have addressed this question by examining mice genetically engineered to over- or underexpress neuregulin-1 (NRG1), a direct modulator of synaptic transmission. Transgenic mice overexpressing NRG1 in spiral ganglion neurons (SGNs) showed improvements in hearing thresholds, whereas NRG1 -/+ mice show a complementary worsening of thresholds. However, no significant change in age-related loss of SGNs in either NRG1 -/+ mice or mice overexpressing NRG1 was observed, while a negative association between NRG1 expression level and survival of inner hair cells during aging was observed. Subsequent studies provided evidence that modulating NRG1 levels changes synaptic transmission between SGNs and hair cells. One of the most dramatic examples of this was the reversal of lower hearing thresholds by turning-off NRG1 overexpression. These data demonstrate for the first time that synaptic modulation is unable to prevent age-related neuronal loss in the cochlea.

A Meta-Analysis of GLP-1 After Roux-En-Y Gastric Bypass: Impact of Surgical Technique and Measurement Strategy

BackgroundRoux-en-Y gastric bypass (RYGB) is an effective treatment for diabetes. Glucagon-like peptide-1 (GLP-1) is a gut hormone that is important to glucose homeostasis.ObjectiveThis study aimed to assess GLP-1 level and its predictors after RYGB.MethodsThe study design was a meta-analysis. The data sources were MEDLINE, EMBASE, Web of Science, and the Cochrane Databases. The study selection composed of studies with pre- and post-RYGB levels. The main outcomes were as follows: Primary outcome was the change in postprandial GLP-1 levels after RYGB. Secondary outcomes included the changes in fasting glucose, fasting insulin, and fasting GLP-1 levels after RYGB. Meta-regression to determine predictors of changes in GLP-1 levels was performed. Outcomes were reported using Hedge’s g.ResultsTwenty-four studies with 368 patients were included. Postprandial GLP-1 levels increased after RYGB (Hedge’s gxa0=xa01.29, pxa0<xa00.0001), while fasting GLP-1 did not change (pxa0=xa00.23). Peak postprandial GLP-1 levels gave the most consistent results (I2xa0=xa09.11). Fasting glucose and insulin levels decreased after RYGB (pxa0<xa00.0001).Roux limb length was a significant predictor for amount of GLP-1 increase (βxa0=xa0−xa00.01, pxa0=xa00.02). Diabetes status, amount of weight loss, length of biliopancreatic limb, and time of measurement were not significant predictors (pxa0>xa00.05).ConclusionPostprandial GLP-1 levels increase after RYGB, while fasting levels remain unchanged. Shorter Roux limb length is associated with greater increase in postprandial GLP-1, which may lead to better glycemic control in this population.

A Lower Cyst Fluid CEA Cut-Off Increases Diagnostic Accuracy in Identifying Mucinous Pancreatic Cystic Lesions

Context Carcinoembryonic antigen analysis of pancreatic cyst fluid is the tumor marker of choice for preoperatively differentiating mucinous from non-mucinous cystic lesions. Objective We aim to determine the most accurate cyst carcinoembryonic antigen cut-off value for distinguishing mucinous cysts from non-mucinous cysts with a focus on discriminating intraductal papillary mucinous neoplasms. Methods The results of pancreatic cyst aspiration carcinoembryonic antigen levels from a single center were retrospectively collected and evaluated for a diagnosis of a mucinous cyst and an assessment of malignancy using surgical histology as the diagnostic standard in 86 patients. Results The median cyst carcinoembryonic antigen level (ng/mL) was significantly higher in mucinous cysts compared with non-mucinous cysts (218 vs. 4.4; P=0.0006) and in intraductal papillary mucinous neoplasms compared with non-mucinous cysts (135 vs. 4.4; P=0.0027). A cyst carcinoembryonic antigen cut-off of 30.7 ng/mL was most accurate (87.2%) for differentiating mucinous from non-mucinous cysts and specifically for differentiating intraductal papillary mucinous neoplasms from non-mucinous cysts (82.7%). Cyst carcinoembryonic antigen levels were not significantly different between malignant and non-malignant mucinous cysts (68.5 vs. 238.1; P=0.51). Conclusions Pancreatic cyst fluid carcinoembryonic antigen can accurately differentiate histologically verified mucinous lesions, including intraductal papillary mucinous neoplasms, from non-mucinous lesions with an optimal cut-off that is much lower than previously reported values. Cyst carcinoembryonic antigen levels are not a reliable predictor of malignancy. Image: Sensitivity and specificity curves of cyst fluid CEA levels for differentiating mucinous from non-mucinous cysts.

Early Abdominal Imaging Remains Over-Utilized in Acute Pancreatitis

BackgroundEarly abdominal computed tomography (CT) or magnetic resonance (MR) imaging is common in acute pancreatitis (AP). Guidelines (2007–2013) indicate routine use is unwarranted.AimsTo compare the frequency and evaluate the predictors of early CT/MR utilization for AP between September 2006–2007 (period A) and September 2014–2015 (period B).MethodsAP patients presenting directly to a large academic emergency department were prospectively enrolled during each period. Cases requiring imaging to fulfill diagnostic criteria were excluded. Early CT/MR (within 24xa0h of presentation) utilization rates were compared using Fisher’s exact test. Predictors of early imaging usage were assessed with multivariate logistic regression.ResultsThe cohort included 96 AP cases in period A and 97 in period B. There were no significant differences in patient demographics, comorbidity scores, or AP severity. Period B cases manifested decreased rates of the systemic inflammatory response syndrome (SIRS) during the first 24xa0h of hospitalization (67% period A vs. 43% period B, pxa0=xa00.001). Independent predictors of early imaging included age >60 and SIRS or organ failure on day 1. No significant decrease in early CT/MR usage was observed from period A to B on both univariate (49% period A vs. 40% period B, pxa0=xa00.25) and multivariate (OR 1.0 for period B vs. A, 95% CI 0.5–1.9) analysis.ConclusionsIn a comparison of imaging practices for AP, there was no significant decrease in early abdominal CT/MR utilization from 2007 to 2015. Quality improvement initiatives specifically targeting early imaging overuse are needed.

Tu1222 A Low CEA Cut-off Identifies Mucinous Pancreatic Cystic Lesions With Increased Diagnostic Accuracy

G A A b st ra ct s was used to measure CEA in cyst fluid. Results: Consistent with recent concerns1, the intra-class correlation (ICC) between undiluted cyst fluid CEA measurements and CEA measurements from cyst fluid diluted in UD or saline was only 0.5 (Figure 1). The low ICC was due to significant positive bias in the measurement of CEA in about 1/2 of the cyst fluids that were diluted with UD or saline (Mean bias UD or saline = 0.6, P-values , 0.0001). Similarly, the ICC between undiluted CEA measurements and CEA measurements diluted in RPD was only 0.5. However, about 1/2 RPD diluted fluids had significant negative bias in the measurement of CEA (Mean bias RPD = 2.5, P-value , 0.0001). Based on these observations, we determined cyst fluid biochemical characteristics that could identify fluids that when excluded from the analysis removed the positive and negative bias observed with each respective diluent. When these biochemical characteristics were used to dictate which diluent to implement, the resulting ICC between diluted and undiluted CEA was 0.9 (Figure 1). The use of each diluent based on these biochemical properties removed all significant bias in the CEA measurement (Mean bias saline [or UD] and RPD = 1.3, P-value = 0.4). Conclusions: Cyst fluid dilution can significantly impact the accuracy of CEA measurement. Dilution induced errors in CEA are due to properties of cyst fluid samples. The use of saline (or UD) and RedPaths novel diluent (RPD), based onmeasurable biochemical fluid properties, results in more accurate CEA measurement in diluted pancreatic cyst fluid. References: 1 Boot, C. S., et al. Clinical chemistry 56, 1351-1352, doi:10.1373/clinchem.2010.146373 (2010).