Simulation of suspended sediment transport in a floating canopy channel based on random displacement model.

In conventional research, the suspended sediment distribution in a channel under the action of floating canopy has been rarely studied. In this study, experiments on sediment transport in flume with fixed suspended vegetation were carried out under different velocity conditions. It was performed to examine the suspended sediment transport and distribution law as impacted by the floating canopy. The vertical distribution formula of velocity impacted by the floating canopy was derived based on improved two-layer theory. Combined with the random displacement model (RDM), a Lagrangian method was developed to simulate the suspended sediment transport under the action of the floating canopy. Compared with the experimental data, the R2 of vertical velocity simulation was higher than 0.96, and the vertical distribution of suspended sediment concentration varied significantly (4.64 to 19.83 g/L) following the vertical coordinate. Subsequently, the numerical model of sandy flow with the floating canopy was established by complying with the stratified sediment turbulence diffusion coefficient to predict the suspended sediment transport. Besides, the established numerical model can lay a theory basis for sediment transport in such channels (floating canopy channels).

The bacterial community structure in epiphytic biofilm on submerged macrophyte Potamogetom crispus L. and its contribution to heavy metal accumulation in an urban industrial area in Hangzhou.

Submerged macrophytes and their epiphytic biofilms are important media for metal transport/transformation in aquatic environment. However, the bacterial community structure and the contribution of the epiphytic biofilm to the heavy metal accumulation remain unclear. Therefore, in this study, water, sediment, submerged macrophyte (Potamogeton crispus L.) and its epiphytic biofilm samples in three sites of the moat in the industrial area of Hangzhou were collected for analyzing. The bacterial community structure was significantly impacted by the TN concentrations, and Genus Aeromonas (24.5-41.8%), Acinetobacter (16.2-29.8%) and Pseudomonas (12.6-23.6%) dominated in all epiphytic biofilm samples, which had the heavy metal pollutant resistibility. The contents of Cr in biofilms (7.4-8.3 mg/kg, DW) were significantly higher than those in leaves (1.0-2.4 mg/kg, DW), while the contents of Cu (11.0-13.9 mg/kg, DW) in leaves were significantly higher than those in biofilms (0.7-3.9 mg/kg, DW) in all the three sites. The BCF values of metals in the biofilm were followed the order of YF < IC < ETS. The results indicated that the epiphytic biofilm had positive effects on the metal bioaccumulation, and the metal accumulation ability increased with the hydrodynamic forces. Bioaccumulation by the epiphytic biofilm may be an effective way for metal (especially Cr) remediation.

Removal of nitrate from agricultural runoff in biochar electrode based biofilm reactor: Performance and enhancement mechanisms.

A biochar electrode based biofilm reactor was developed for advanced removal of nitrate from agricultural runoff. The corn-straw (Zea mays L.) biochar formed at 500 °C has an adsorption capacity of NO3--N up to 2.659 mg g-1. After 45-day start-up phase, the removal efficiency of nitrate reached 93.4% when impressed current was 20 mA, hydraulic retention time was 12 h and chemical oxygen demand/total nitrogen (C/N) ratio was 0.56 without additional carbon source. In comparison, neither electrochemical reduction alone nor microbial denitrification alone could obtain the ideal nitrate removal efficiency. The results implied that bio-electrochemical reduction was the main way of nitrate removal in the biofilm electrode reactor (BER). The denitrification efficiency of 88.9% could still be obtained when C/N = 0. It is because biochar can significantly promote the utilization efficiency of cathode electrons by microorganisms. Thus, biochar is a promising electrode material, which provides a new idea for the optimization of BER.

Nitrogen transformation in slightly polluted surface water by a novel biofilm reactor: Long-term performance and microbial population characteristics.

This study proposes a modular floating biofilm reactor (MFBR) for in situ nitrogen removal from slightly polluted water in rivers using enriched indigenous microorganisms. Its main structure is a 60 cm × 60 cm × 90 cm rectangular reactor filled with hackettens. After a 96-day startup, the removal efficiencies of ammonia-N and total N (TN) reached 80% and 25%, respectively, with a hydraulic retention time (HRT) of 10 h, whereas those in a control reactor (without biofilm) were only 4.9% and 0.2%, respectively. The influences of HRT and dissolved oxygen (DO) were also investigated. As a key factor, HRT significantly affected the removal efficiencies of ammonia-N and TN. When HRT was close to the actual value for a river studied (2.4 min), the removal efficiencies of ammonia-N and TN were only 8.7% and 3.1%, respectively. Aeration increased the concentration of DO in water, which enhanced nitrification but inhibited denitrification. When HRT was 2.4 min, aeration intensity was 20 L/min; the ammonia-N and TN removal rates were 9.5 g/(m2·d) and 11.3 g/(m2·d), respectively. The results of microbial community analysis indicated that the microorganisms forming the biofilm were indigenous bacteria. The findings demonstrated a concept-proof of MFBR, which may be evaluated in scaling up investigation for developing a new methodology for nitrogen removal from slightly polluted surface water in plain river networks.

Efficacy and safety of acupoint catgut embedding in treating postoperative pain of mixed hemorrhoids: A randomized controlled trial protocol.

BACKGROUND: Pain is a common complication after mixed hemorrhoids, which seriously affects the recovery of patients and prolongs the length of hospital stay. Acupoint catgut embedding has advantages in improving a variety of acute and chronic pain diseases, but there is still a lack of rigorous randomized controlled studies to verify its efficacy and safety in the treatment of postoperative pain of mixed hemorrhoids. Therefore, the purpose of this randomized controlled trial is to evaluate the clinical efficacy of acupoint catgut embedding in the treatment of postoperative pain of mixed hemorrhoids. METHODS: This is a prospective randomized controlled trial to study the efficacy and safety of acupoint catgut embedding in the treatment of postoperative pain of mixed hemorrhoids. Approved by the clinical research ethics committee of our hospital, the patients were randomly divided into observation group and control group according to 1:1. The observation group received acupoint catgut embedding before the operation, while the control group received no special treatment. The efficacy and safety indexes were concerned after the operation, and the observation indexes included: resting state and visual analogue scale (VAS) score during defecation, postoperative hospitalization time, total amount of analgesic use, adverse reactions, etc. Finally, we carried on the data statistical analysis through the SPSS version 19.0. DISCUSSION: This study will evaluate the efficacy and safety of acupoint catgut embedding in the treatment of postoperative pain of mixed hemorrhoids, and the results of this study will provide a new idea for the selection of postoperative analgesia for mixed hemorrhoids resection. TRIAL REGISTRATION: OSF Registration number: DOI 10.17605/OSF.IO/T2ZGY.

Bioaccumulation of potentially toxic elements by submerged plants and biofilms: A critical review.

The accumulation of potentially toxic elements (PTEs) in aquatic ecosystems has become a global concern, as PTEs may exert a wide range of toxicological impacts on aquatic organisms. Submerged plants and the microorganisms attached to their surfaces, however, have displayed great potential as a means of coping with such pollution. Therefore, it is crucial to understand the transport pathways of PTEs across sediment and organisms as well as their accumulation mechanisms in the presence of submerged plants and their biofilms. The majority of previous studies have demonstrated that submerged plants and their biofilms are indicators of PTE pollution in the aquatic environment, yet relatively little is known about PTE accumulation in epiphytic biofilms. In this review, we describe the transport pathways of PTEs in the aquatic environment in order to offer remarkable insights into bioaccumulation mechanisms in submerged plants and their biofilms. Based on the literature cited in this review, the roles of epiphytic biofilms in bioaccumulation and as an indicator of ecosystem health are discussed.

miR-17-3P regulates the proliferation and survival of colon cancer cells by targeting Par4.

Colorectal cancer (CRC) is a common malignancy worldwide. However, the pathogenesis by which CRC progression occurs remains to be elucidated. The present study investigated the role of miRNA (miR)­17­3P in the regulation of CRC cell survival. Firstly, miR­17­3P expression was aberrantly upregulated in human CRC tumor tissues compared with controls. Further results demonstrated that the proliferation capacity of human CRC SW480 and LoVo cells was significantly increased by an miR­17­3P specific mimic, and was inhibited by miR­17­3P silencing. Conversely, the apoptosis of human CRC cells was remarkably decreased by miR­17­3P mimic, and enhanced by miR­17­3P suppression compared with control. Additionally, it was observed that there was a potential binding site of miR­17­3P on the 3'­untranslated region of Prostate apoptosis responde­4 (Par4) and miR­17­3P may directly target Par4 mRNA. In human CRC cells, an miR­17­3P inhibitor significantly upregulated Par 4 expression, however the miR­17­3P mimic reduced Par4expression. Furthermore, Par4 expression exhibited an inhibitory effect on the proliferation of CRC cells transfected with miR­17­3P mimic, and exhibited a promoting role in the repressed apoptosis by miR­17­3P mimic. Inconclusion, the results of the present study demonstrated that miR­17­3P is important in CRC cell survival by targeting Par4, indicating a novel finding regarding human CRC progression.

Microarray studies on effects of Pneumocystis carinii infection on global gene expression in alveolar macrophages.

BACKGROUND: Pneumocystis pneumonia is a common opportunistic disease in AIDS patients. The alveolar macrophage is an important effector cell in the clearance of Pneumocystis organisms by phagocytosis. However, both the number and phagocytic activity of alveolar macrophages are decreased in Pneumocystis infected hosts. To understand how Pneumocystis inactivates alveolar macrophages, Affymetrix GeneChip RG-U34A DNA microarrays were used to study the difference in global gene expression in alveolar macrophages from uninfected and Pneumocystis carinii-infected Sprague-Dawley rats. RESULTS: Analyses of genes that were affected by Pneumocystis infection showed that many functions in the cells were affected. Antigen presentation, cell-mediated immune response, humoral immune response, and inflammatory response were most severely affected, followed by cellular movement, immune cell trafficking, immunological disease, cell-to-cell signaling and interaction, cell death, organ injury and abnormality, cell signaling, infectious disease, small molecular biochemistry, antimicrobial response, and free radical scavenging. Since rats must be immunosuppressed in order to develop Pneumocystis infection, alveolar macrophages from four rats of the same sex and age that were treated with dexamethasone for the entire eight weeks of the study period were also examined. With a filter of false-discovery rate less than 0.1 and fold change greater than 1.5, 200 genes were found to be up-regulated, and 144 genes were down-regulated by dexamethasone treatment. During Pneumocystis pneumonia, 115 genes were found to be up- and 137 were down-regulated with the same filtering criteria. The top ten genes up-regulated by Pneumocystis infection were Cxcl10, Spp1, S100A9, Rsad2, S100A8, Nos2, RT1-Bb, Lcn2, RT1-Db1, and Srgn with fold changes ranging between 12.33 and 5.34; and the top ten down-regulated ones were Lgals1, Psat1, Tbc1d23, Gsta1, Car5b, Xrcc5, Pdlim1, Alcam, Cidea, and Pkib with fold changes ranging between -4.24 and -2.25. CONCLUSIONS: In order to survive in the host, Pneumocystis organisms change the expression profile of alveolar macrophages. Results of this study revealed that Pneumocystis infection affects many cellular functions leading to reduced number and activity of alveolar macrophages during Pneumocystis pneumonia.

Adiponectin receptor-1 expression is decreased in the pancreas of obese mice.

BACKGROUND: Obesity is epidemic in the 21st century and has been shown to be a risk factor for developing severe acute pancreatitis. Adipose tissue produces small molecules called adipokines, which are important in modulating metabolism and inflammation. The anti-inflammatory adipokine adiponectin is decreased in obesity and inversely mirrors the severity of pancreatitis in a murine experimental model. Adiponectin acts through two receptors, AdipoR1 and AdipoR2; no data are currently available regarding adiponection receptor expression in the obese murine pancreas. MATERIALS AND METHODS: Immunohistochemical and reverse transcription-polymerase chain reaction analysis were undertaken to determine expression of adiponectin receptors AdipoR1 and AdipoR2 in the pancreas and liver of lean (C57BL/6J) and congenitally obese (Lep(Ob) and Lep(Db)) mice. RESULTS: Immunohistochemistry confirmed expression of both AdipoR1 and AdipoR2 in the pancreas of all three murine strains. Staining was positive in acinar cells and to a lesser extent in islet cells. Pancreatic gene expression of AdipoR2 was similar among lean and obese mice. AdipoR1 gene expression, however, was significantly (P < 0.001) decreased in the pancreas of both Lep(Ob) and Lep(Db) mice compared to wild-type lean animals. Gene expression of both AdipoR1 and AdipoR2 was significantly less in the liver of obese (Lep(Ob) and Lep(Db)) mice compared to wild-type lean animals (P < 0.001). CONCLUSIONS: These data show for the first time that the adiponectin receptors AdipoR1 and AdipoR2 are expressed in the obese murine pancreas. The paucity of AdipoR1 receptors may be important when considering the role played by adipokines in the genesis of severe pancreatitis in obesity.

A murine model of obesity implicates the adipokine milieu in the pathogenesis of severe acute pancreatitis.

Obesity is clearly an independent risk factor for increased severity of acute pancreatitis (AP), although the mechanisms underlying this association are unknown. Adipokines (including leptin and adiponectin) are pleiotropic molecules produced by adipocytes that are important regulators of the inflammatory response. We hypothesized that the altered adipokine milieu observed in obesity contributes to the increased severity of pancreatitis. Lean (C57BL/6J), obese leptin-deficient (LepOb), and obese hyperleptinemic (LepDb) mice were subjected to AP by six hourly intraperitoneal injections of cerulein (50 microg/kg). Severity of AP was assessed by histology and by measuring pancreatic concentration of the proinflammatory cytokines IL-1beta and IL-6, the chemokine MCP-1, and the marker of neutrophil activation MPO. Both congenitally obese strains of mice developed significantly more severe AP than wild-type lean animals. Severity of AP was not solely related to adipose tissue volume: LepOb mice were heaviest; however, LepDb mice developed the most severe AP both histologically and biochemically. Circulating adiponectin concentrations inversely mirrored the severity of pancreatitis. These data demonstrate that congenitally obese mice develop more severe AP than lean animals when challenged by cerulein hyperstimulation and suggest that alteration of the adipokine milieu exacerbates the severity of AP in obesity.

Leptin regulates gallbladder genes related to gallstone pathogenesis in leptin-deficient mice.

BACKGROUND: Little is known about the genetic factors that cause alterations in gallbladder motility, cholesterol crystal nucleation, biliary lipids, and, ultimately, cholesterol gallstones. Obese, leptin-deficient (Lep(ob)) mice have large gallbladder volumes with decreased contraction in vitro and are predisposed to cholesterol crystal formation. Leptin administration to these mice causes weight loss and restores gallbladder function. We hypothesize that administration of leptin to Lep(ob) mice would cause weight loss, decrease gallbladder volume, and change gallbladder genes related to gallbladder motility, nucleating factors, and lipid metabolism. STUDY DESIGN: Twenty-four 8-week-old Lep(ob) mice were fed a nonlithogenic diet for 4 weeks. Twelve mice received daily IP saline injections, and 12 received 5 mug/g recombinant leptin. Gallbladder mRNA was pooled and analyzed on murine genome microarray chips. Selected genes were confirmed by real-time polymerase chain reaction (PCR) in a second group of mice treated by the same protocol. RESULTS: Leptin-deficient mice given leptin had significant weight loss and reductions in gallbladder volume. These mice had upregulation of the leptin receptor (p = 0.007; PCR = 1.1-fold increase) but downregulation of leptin (p = 0.003; PCR = 13.5-fold decrease). Leptin upregulated the cholecystokinin A receptor (p < 0.001; PCR = 3.1-fold increase), acetylcholine beta2 receptor (p = 0.005), and the Ca+-calmodulin-dependent protein kinase (p = 0.002) genes. Leptin also altered immunoglobulin heavy chain 4 (p = 0.005; PCR = 17.7-fold increase), mucin 3 (p = 0.006), and carboxylesterase (p = 0.016; PCR = 2.5-fold decrease) genes. Leptin downregulated 3-hydroxy 3-methylglutaryl coenzyme A reductase (p = 0.006; PCR = 2.5-fold decrease) and LDL receptor (p = 0.003). CONCLUSIONS: Leptin modulates obesity and regulates gallbladder genes related to cholesterol gallstone pathogenesis.

Steatocholecystitis: the influence of obesity and dietary carbohydrates.

INTRODUCTION: We have recently demonstrated that obese and lean mice fed a high fat diet have increased gallbladder wall fat and decreased gallbladder contractility, cholecystosteatosis. Animal and human data also suggest that diets high in refined carbohydrates lead to gallstone formation. However, no data are available on the role of dietary carbohydrates on gallbladder wall fat and inflammation. Therefore, we tested the hypothesis that both obesity and dietary carbohydrates would increase gallbladder fat and cytokines, steatocholecystitis. METHODS: At 8 wk of age, 47 lean and 22 obese female mice were fed a 45% carbohydrate (CHO) diet while an equal number of lean and obese mice were fed a 75% CHO diet for 4 wk. All mice underwent cholecystectomy, and the gallbladders were snap-frozen. Individual and total lipids were measured by gas chromatography. Interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, and IL-6 were measured by enzyme-linked immunosorbent assay. Data were analyzed by analysis of variance and Tukey test. RESULTS: Gallbladder total fat, triglycerides, and cholesterol were maximum (P < 0.001) in obese mice on the 75% CHO diet. Gallbladder TNF-alpha and IL-1beta as well as serum cholesterol levels showed a similar pattern (P < 0.001). Gallbladder saturated free fatty acids and IL-6 levels were highest (P < 0.001) in obese mice on the 45% CHO diet. CONCLUSIONS: These data suggest that (1) both obesity and dietary carbohydrates increase gallbladder total fat, triglycerides, cholesterol, TNF-alpha, and IL-1beta and (2) obesity also increases gallbladder free fatty acids and IL-6. Therefore, we conclude that obesity is associated with steatocholecystitis and that a high carbohydrate diet exacerbates this phenomenon.

Is autotaxin (ENPP2) the link between hepatitis C and hepatocellular cancer?

INTRODUCTION: Hepatitis C is the most significant risk factor for development of hepatocellular carcinoma. Inflammation, fibrosis, and liver cell proliferation may contribute to cancer development either through malignant hepatocyte transformation or extracellular matrix remodeling within the tumor microenvironment. The study objective was to investigate differences in gene expression between patients with Hepatitis C (+/- cancer) and normal that might explain the increased cancer risk. METHODS: Liver tissue was collected from three patient groups: 1) healthy patients, 2) Hepatitis C patients without cancer, 3) patients with Hepatitis C and hepatocellular carcinoma. Microarray analysis was performed on samples from each group. Western blot and real-time polymerase chain reaction (PCR) analyses corroborated the microarray data. A p value of 0.05 was set as significant. RESULTS: Microarray analysis showed overexpression of autotaxin in patients with cancer versus hepatitis patients or normal patients. Rho GTPase binding proteins (Cdc42s) associated with lysophosphatidic acid signaling were also overexpressed in cancer patients. Real-time polymerase chain reaction showed overexpression of several factors associated with autotaxin in patients with Hepatitis C (+/- cancer) versus normal patients. CONCLUSIONS: Patients with Hepatitis C and hepatocellular carcinoma show differential expression of various components of the autotaxin pathway versus normal patients. This merits further investigation in the context of early diagnosis.

Ezetimibe ameliorates cholecystosteatosis.

BACKGROUND: Cholecystosteatosis is the accumulation of gallbladder wall fats leading to decreased gallbladder emptying. Ezetimibe inhibits intestinal fat absorption and prevents murine gallstone formation. However, the influence of ezetimibe on gallbladder emptying and cholecystosteatosis has not been studied. Therefore, we tested the hypothesis that ezetimibe would improve gallbladder motility by preventing the buildup of fats in the gallbladder wall. METHODS: Forty lean female mice were fed either a control diet or a lithogenic diet for 6 weeks. Half of the mice on each diet received ezetimibe. At 11 weeks of age, all mice were fasted overnight and underwent gallbladder ultrasonography to determine ejection fraction. One week later, the mice were fasted and underwent cholecystectomy. Bile was examined for cholesterol crystals. The gallbladders were snap-frozen for lipid analysis. RESULTS: The lithogenic diet significantly (P < 0.05) increased serum cholesterol, biliary crystals, gallbladder wall cholesterol and cholesterol/phospholipid ratio, and decreased gallbladder ejection fraction. All of these abnormalities were reversed (P < 0.05) by the addition of ezetimibe to the diet. CONCLUSIONS: These data suggest that ezetimibe lowers serum cholesterol, prevents biliary crystals, and normalizes gallbladder wall fat and function. We conclude that ezetimibe ameliorates cholecystosteatosis and may be an effective agent for gallstone prevention.

Leptin regulates gallbladder genes related to absorption and secretion.

Dysregulation of gallbladder ion and water absorption and/or secretion has been linked to cholesterol crystal and gallstone formation. We have recently demonstrated that obese, leptin-deficient (Lep(ob)) mice have enlarged gallbladder volumes and decreased gallbladder contractility and that leptin administration to these mice normalizes gallbladder function. However, the effect of leptin on gallbladder absorption/secretion is not known. Therefore, we sought to determine whether leptin would alter the expression of genes involved in water and ion transport across the gallbladder epithelium. Affymetrix oligonucleotide microarrays representing 39,000 transcripts were used to compare gallbladder gene-expression profiles from 12-wk-old control saline-treated Lep(ob) and from leptin-treated Lep(ob) female mice. Leptin administration to Lep(ob) mice decreased gallbladder volume, bile sodium concentration, and pH. Leptin repletion upregulated the expression of aquaporin 1 water channel by 1.3-fold and downregulated aquaporin 4 by 2.3-fold. A number of genes involved in sodium transport were also influenced by leptin replacement. Epithelial sodium channel-alpha and sodium hydrogen exchangers 1 and 3 were moderately downregulated by 2.0-, 1.6-, and 1.3-fold, respectively. Carbonic anhydrase-IV, which plays a role in the acidification of bile, was upregulated 3.7-fold. In addition, a number of inflammatory cytokines that are known to influence gallbladder epithelial cell absorption and secretion were upregulated. Thus leptin, an adipocyte-derived cytokine involved with satiety and energy balance, influences gallbladder bile volume, sodium, and pH as well as multiple inflammatory cytokine genes and genes related to water, sodium, chloride, and bicarbonate transport.

High dietary carbohydrates decrease gallbladder volume and enhance cholesterol crystal formation.

BACKGROUND: Animal and human data suggest that a diet high in refined carbohydrates leads to gallstone formation. However, no data are available on the role of dietary carbohydrates on gallbladder volume or on cholesterol crystal formation. Therefore, we tested the hypothesis that a high carbohydrate diet would alter gallbladder volume and enhance cholesterol crystal formation. METHODS: At 8 weeks of age, 60 lean and 36 obese leptin-deficient female mice were fed a 45% carbohydrate diet while an equal number of lean and obese mice were fed a 75% carbohydrate diet for 4 weeks. All animals then underwent cholecystectomy, and gallbladder bile volume was recorded. Bile was pooled, filtered, and maintained in a water bath at 37 degrees C for 14 days. Birefringent cholesterol crystals in bile were counted daily; crystal observation time and crystal mass were determined. RESULTS: The crystal observation time was significantly shortened in both lean and obese mice on the 75% diet compared with their counterparts on the 45% diet. The crystal mass was significantly increased in the lean mice on the 75% diet compared with the 45% diet. Gallbladder volumes were significantly reduced in both lean and obese mice on the 75% diet compared with their counterparts on the 45% diet. CONCLUSIONS: These data suggest that a high carbohydrate diet decreases gallbladder volume, shortens cholesterol crystal observation time, and increases crystal mass. We conclude that dietary carbohydrates may play a role in cholesterol gallstone formation by altering biliary motility and by enhancing crystal formation.

Resistin-like molecule alpha reduces gallbladder optimal tension.

INTRODUCTION: Insulin resistance is associated with increased gallbladder volume and impaired gallbladder emptying. Resistin and resistin-like molecule alpha (RELM-alpha) are adipose-derived hormones that are believed to mediate insulin resistance. Therefore, we tested the hypothesis that administration of resistin or RELM-alpha would cause insulin resistance and diminish gallbladder contractility. METHODS: In two sequential studies 40 eight-week-old nondiabetic lean mice were fed a chow diet for 4 weeks. In Study A, 10 mice received 20 microg of resistin IP, while in Study B 10 mice received 20 microg of RELM-alpha IP for seven days. In each study, 10 control mice received an equal volume of saline IP for seven days. At 12 weeks animals were fasted and underwent cholecystectomy, and in vitro gallbladder response to neurotransmitters was determined. Serum resistin, RELM-alpha, glucose, and insulin levels were measured. HOMA index, a measure of insulin resistance, was calculated. RESULTS: RELM-alpha significantly increased HOMA index. RELM-alpha decreased gallbladder optimal tension, but did not alter responses to neurotransmitters. Resistin had no effect on HOMA index or on gallbladder optimal tension or response. CONCLUSION: These data suggest that in nondiabetic lean mice: 1) resistin does not alter insulin resistance or gallbladder optimal tension, but 2) RELM-alpha increases insulin resistance and reduces gallbladder optimal tension. Therefore, we concluded that RELM-alpha may play a role in insulin-resistance mediated gallbladder dysmotility.

Nonalcoholic fatty pancreas disease.

BACKGROUND: Obesity leads to fat infiltration of multiple organs including the heart, kidneys, and liver. Under conditions of oxidative stress, fat-derived cytokines are released locally and result in an inflammatory process and organ dysfunction. In the liver, fat infiltration has been termed nonalcoholic fatty liver disease, which may lead to nonalcoholic steatohepatitis. No data are available, however, on the influence of obesity on pancreatic fat and cytokines, and nonalcoholic fatty pancreas disease (NAFPD) has not been described. Therefore, we designed a study to determine whether obesity is associated with increased pancreatic fat and cytokines. MATERIALS AND METHODS: Thirty C57BL/6J lean control and 30 leptin-deficient obese female mice were fed a 15% fat diet for 4 weeks. At 12 weeks of age all animals underwent total pancreatectomy. Pancreata from each strain were pooled for measurement of a) wet and dry weight, b) histologic presence of fat, c) triglycerides, free fatty acids (FFAs), cholesterol, phospholipids, and total fat, and d) interleukin (IL)-1beta and tumor necrosis factor-alpha (TNF-alpha). Data were analyzed by Student's t test and Fisher's exact test. RESULTS: Pancreata from obese mice were heavier (p<0.05) and had more fat histologically (p<0.05). Pancreata from obese mice had more triglycerides, FFAs, cholesterol, and total fat (p<0.05). Triglycerides represented 11% of pancreatic fat in lean mice compared with 67% of pancreatic fat in obese mice (p<0.01). Cytokines IL-1beta and TNF-alpha also were elevated in the pancreata of obese mice (p<0.05). CONCLUSIONS: These data suggest that obese mice have 1) heavier pancreata, 2) more pancreatic fat, especially triglycerides and FFAs, and 3) increased cytokines. We conclude that obesity leads to nonalcoholic fatty pancreatic disease.

Pioglitazone increases gallbladder volume in insulin-resistant obese mice.

BACKGROUND: Both obesity and diabetes are associated with an increased incidence of gallstones. Recent animal and human data from our laboratory suggest that insulin resistance is associated with increased gallbladder volume and/or impaired gallbladder emptying. Pioglitazone is a thiazolidinedione that has been shown to improve insulin resistance. Therefore, we tested the hypothesis that pioglitazone would improve insulin resistance, decrease resting gallbladder volume and improve gallbladder response to neurotransmitters in insulin-resistant obese mice fed a 25% carbohydrate diet. MATERIALS AND METHODS: Twenty eight-week-old insulin-resistant obese (Lep(ob)) mice fed a 25% carbohydrate diet for 4 weeks. Half of the animals had 0.3 g/kg pioglitazone added to their diet. At 12 weeks all animals were fasted and underwent cholecystectomy. Gallbladder volume and weight were measured, and fresh gallbladders were placed in a muscle bath to assess response to acetylcholine (ACh 10(-5)M), neuropeptide Y (NPY 10(-8,-7,-6)M) and cholecystokinin (CCK 10(-10,-9,-8,-7)M). Serum glucose and insulin were measured, and HOMA Index, a measure of insulin resistance, was calculated. RESULTS: Fasting serum insulin and HOMA Index were significantly decreased (P < 0.03), but gallbladder volume was significantly increased (P < 0.03) in the pioglitazone treated group. Pioglitazone did not alter gallbladder weight or response to ACh, NPY, or CCK. CONCLUSION: These data suggest that in insulin-resistant obese mice pioglitazone 1) lowers insulin-resistance, 2) increases resting gallbladder volume, and 3) does not alter gallbladder response to neurotransmitters. Therefore, we conclude that pioglitazone, while improving insulin resistance, paradoxically increases gallbladder volume and, thereby, may increase the propensity for gallstone formation by enhancing gallbladder stasis.

CD80 binding polyproline helical peptide inhibits T cell activation.

The critical role played by the CD28/CD152-CD80/CD86 costimulatory molecules in mediating T cell activation and suppression provides attractive targets for therapeutic strategies. CD28 and CD152 share a conserved polyproline motif in the ligand-binding region. Similar proline-rich regions in globular domains preferentially adopt a polyproline type II (PP) helical conformation and are involved in transient (II)protein-protein interactions. Interestingly, in the human CD80-CD152 complex, Pro(102) of CD152 restricts the preceding proline to PP(II) helix in the binding orientation in relation to the shallow binding pocket of CD80. Peptide agents derived from binding sites of receptors that mimic the bioactive conformation have been shown to block receptor-ligand interactions. Contact preferences of the interface amino acids at the protein-protein interaction sites and the propensity of each residue to form PP(II) helix were integrated in the design of novel peptide agents referred to as CD80 competitive antagonist peptides. Structural and functional studies suggest potential therapeutic value for select CD80 competitive antagonist peptides.