Nutrient dynamics in wetland systems associated with hydrological and anthropogenic variations in the south of Samborombón Bay, Argentina

Wetlands provide numerous ecosystem services to the environment, such as nutrient removal and storage. The aim of this work is to evaluate the nutrient dynamics in different sectors within wetland systems in the south of the Samborombón Bay (Argentina) based on hydrological and/or anthropogenic variations. For this purpose, the hydrological features of the wetland were defined through the analysis of satellite images, precipitation and tidal data, and field surveys. Three sectors were identified in the wetland: one with tidal influence, another which is dependent on rainfall, and another that receives inputs from rainfall and from a sewage effluent treatment plant. In order to analyze the nutrient dynamics, samples of surface water, groundwater, and sediments were collected from these sectors. Measurements of pH and electrical conductivity were determined in situ in water samples, while the concentration of inorganic forms of phosphorus and nitrogen, soluble reactive silica, and organic carbon were determined through laboratory analysis. Also, bioavailable phosphorus, organic matter, pH, and electrical conductivity were determined in the sediment samples collected. Statistical analysis of the data reveals differences between the sectors and allows the interpretation of the dynamics of the studied components in the wetland. Electrical conductivity distinguishes the intertidal sectors of the wetland while components associated with P and N discriminate the sectors with inputs from the sewage effluent treatment plant. On the other hand, soluble reactive silica, organic carbon, and organic matter do not seem to be influenced by the tide or effluent discharge. This study demonstrates that the studied wetland works as a nutrient retention area, providing ecosystem services to local inhabitants. Although these services can be utilized, they require a continuous monitoring over time to provide an early warning in case the variations in P and N cycles could lead to eutrophication or wetland degradation.

Hydrochemistry and trace metals in water and sediments in forest coastal wetlands influenced by tidal regime in the middle Río de la Plata estuary, Argentina

Coastal wetland ecosystems are of utmost importance in regulating the mobility and distribution of elements in water and sediments, being the flooding by tidal events a recurrent process that strongly controls the hydrodynamics of the system. The aim of this work is to assess the control of the tidal regime and anthropogenic influence on the dynamics of some trace metals in water and sediments in the Punta Lara Natural Reserve situated in the Río de la Plata littoral. For that purpose, relationship between tidal flows, surface water and groundwater was evaluated. Also, hydrochemistry was analyzed based on the study of major ions and trace metals, being the presence of high concentrations of elements in groundwater, such as Fe and Mn, probably favoured by redox processes associated with organic matter decomposition in the water - sediment interaction. Sediments in the wetland register deficient to minimal enrichment in most of the studied trace metals despite the numerous contributions that the Río de la Plata receives in relation to dissolved and particulate trace metals from diverse anthropogenic contributions. Despite that, there is a moderate enrichment in Pb and Cr in the surface sediments of the wetland. The data analyzed within the natural reserve in relation to the chemical composition of the water and sediments of the coastal wetland showed the strong influence of the tidal regime over the area.

Assessment of meso- and microplastics distribution in coastal sediments and waters at the middle estuary of the Rio De La Plata, Argentina (SW Atlantic Ocean)

Estuarine coastal water and sediments collected from multiple locations within the middle Río de la Plata (RDLP) estuary were analyzed in order to identify the presence of microplastics (MPs, <5 mm) and mesoplastics (MePs, 5-25 mm) in one of the most significant estuaries in the Southwestern Atlantic. The present study represents one of the first researches to survey MPs and MePs contamination in key stations at RDLP estuary. Average concentrations of 14.17 ± 5.50 MPs/L and 10.00 MePs/L were detected in water samples, while 547.83 ± 620.06 MPs/kg (dry weight) and 74.23 ± 47.29 MePs/kg d.w. were recorded in sediments. The greatest abundances were observed in the more anthropized areas, near urban settlements. Fibers were the most conspicuous plastic items in water and sediments, followed by fragments. On the other hand, surface sediments, and 50 cm and 100 cm-depth sediments also presented MPs and MePs indicating they could serve as a stratigraphic indicator for recently formed sediments. The main polymer type identified were acrylic fibers, followed by polypropylene (PP) and polyethylene terephthalate (PET). Besides, SEM-EDX detected the presence of Si, Fe, Ti, Al and Cl onto the plastics' surface. These elements may serve as additives to enhance the plastics' properties, such as in the case of Ti, or they could originate from the environment, like biogenic Si or Fe, and Al possibly as a component of the suspended particles or sediments adhered to the micro or meso plastics. Finally, the results of the present study showed that MPs and MePs are commonly found in waters and also tend to be trapped in sediments of the RDLP estuary supporting the assertion that these areas play a substantial role in influencing the transport, dispersion, and buildup of MPs in estuarine regions.

Assessment of groundwater-driven dissolved nutrient inputs to coastal wetlands associated with marsh-coastal lagoons systems of the littoral of the outer Río de la Plata estuary

In coastal wetlands the hydrological dynamics and in particular the groundwater flows play a critical role in the establishment of wetlands and in the transport of salts and nutrients. The aim of the work is to analyze the role that groundwater discharge has in the dynamics of the dissolved nutrients of the wetland associated with the coastal lagoon and marshes of the Punta Rasa Natural Reserve, which is located on the coastal sector of the southern end of the Río de la Plata estuary. A monitoring network in the form of transects was generated in order to define groundwater flows and take samples of dissolved species of N and P. The presence of sandy sediments with similar granulometric profiles in all geomorphological environments determines that the underground flow occurs in a homogeneous aquifer. From the dunes and beach ridges the fresh to brackish groundwater flows with a very low hydraulic gradient towards the marsh and coastal lagoon. The contributions of N and P would derive from the degradation of the organic matter of the environment, in the case of the marsh and coastal lagoon also from the tidal flow and discharge of groundwater, and possibly from atmospheric sources in the case of N. Since in all environments oxidizing conditions dominate, nitrification is the main process which is why the most abundant species of N is the NO₃^-. Under oxidizing conditions, P has a greater affinity for the sediments in which it is mostly retained, registering it in low concentrations in water. The discharge of groundwater from the dunes and beach ridges provides dissolved nutrients to the marsh and coastal lagoon. However, the low hydraulic gradient and the dominant oxidizing conditions determine that the flow is scarce and that it only acquires relevance in the contribution of NO₃^-.

A New Potential Resource in the Fight against Candida auris: the Cinnamomum zeylanicum Essential Oil in Synergy with Antifungal Drug

Candida auris is a multidrug-resistant fungus known to be a global public health problem. The skin-based transmission, together with the marked resistance to drugs, resulted in its rapid spread to all continents. The aim of this study was to identify an essential oil (EO) active in the fight against C. auris. A total of 15 EOs were tested against 10 clinical strains of C. auris. Cinnamomum zeylanicum EO (CZ-EO) was the most effective (MIC90 and MFC90 equal to 0.06% vol/vol). Three fractions obtained from CZ-EO, and the cinnamaldehyde (CIN), the major chemical compound, were tested to identify the principal compound effectives against C. auris. All CIN-containing samples showed anti-fungal activity. To study the synergy with fluconazole, CZ-EO, its active fraction (FR2), and CIN were tested in checkerboard tests. Results show that CZ-EO and FR2, but not CIN, synergize with fluconazole. Furthermore, only the copresence of CZ-EO or FR2 synergize with fluconazole at therapeutic concentrations of the drug (0.45 ± 0.32 μg/mL and 0.64 ± 0.67 μg/mL, respectively), while CIN only shows additive activity. In vivo studies conducted on Galleria mellonella larvae show the absence of toxicity of CZ-EO up to concentrations of 16% vol/vol, and the ability of CZ-EO to reactivate the efficacy of fluconazole when formulated at synergic concentrations. Finally, biochemical tests were made to study the mechanism of action of CZ-EO. These studies show that in the presence of both fluconazole and CZ-EO, the activity of fungal ATPases decreases and, at the same time, the amount of intracellular drug increases. IMPORTANCE This study highlights how small doses of CZ-EO are able to inhibit the secretion of fluconazole and promote its accumulation in the fungal cell. In this manner, the drug is able to exert its pharmacological effects bypassing the resistance of the yeast. If further studies will confirm this synergy, it will be possible to develop new therapeutic formulations active in the fight against C. auris resistances.

Assessment of cation exchange as conditioning processes of water chemistry in freshwater lenses

Freshwater lenses are groundwater sources of limited dimensions that can be usually found in a variety of climates worldwide. These aquifers' quality is important for socioeconomic development, being cation exchange one of the most important geochemical processes that can change the water geochemistry. This study aims to assess the cation exchange processes that determine the chemistry of freshwater lenses in a multilayer aquifer type, considering the center-east of the Pampean Region (Argentina) as a case study. Water samples were taken from the freshwater lenses at different depths to analyze major ions in the laboratory. In addition, geological profiles were made along with the extraction of sediment samples for X-ray diffractometry (XRD) and laboratory tests to analyze the cation exchange capacity. The results show that water stored in the lenses has a vertical facies variation from Ca-HCO₃ to Na-HCO₃ . According to the laboratory results, the change of water facies mainly occurs in the clayey sediments that divide the carbonate bioclastic material above and the loessic sediment below, being cation exchange the most important process. PRACTITIONER POINTS: Cation exchange is the main geochemical process regulating groundwater chemistry. Hydrochemical changes determine the quality of freshwater lenses. Na/Ca exchange is mainly regulated by the groundwater flow into the bioturbated clay. Batch exchange tests were also carried out to quantify the Na/Ca exchange processes.

Flood hazard assessment in large plain basins with a scarce slope in the Pampean Plain, Argentina

Floods are one of the most common natural phenomena and represent a serious hazard when they affect human activities. Structural measures are commonly used to mitigate them; however, these do not always give good results, mainly in plain areas with scarce slope. In this sense, the generation of a flood hazard map contributes to adequate hazard management and disaster prevention. The aim of this work is to evaluate the flood hazard areas in hydrological plain basins with scarce slope, taking as a case study the Samborombón river basin located in the Pampean Plain, Argentina. For this, a flood hazard map was made based on the analytical hierarchy process and using a GIS, taking into account physical aspects of the terrain, observations, and field measurements. Likewise, the map was validated using satellite images and the inhabitants in danger in the basin were quantified. The results show that the flood hazard areas correspond mainly to the floodplain of rivers and tributaries, while the main and secondary divide zones have low flood hazard sectors. On the other hand, numerous urban settlements were identified within flood hazard areas, these being urban settlements in the vicinity of old urban centers and new gated communities with high value homes, quantifying 1961 inhabitants at flood hazard and showing poor territorial planning. The methodology proposed gives to the management agencies the possibility of generating land use maps, as well as designing mitigation and contingency plans after a large rainfall event.

Processes controlling groundwater salinity in coastal wetlands of the southern edge of South America

The Argentine Atlantic coast constitutes an extensive area where numerous wetlands develop under humid, semi-arid and arid conditions, in which there are also variations in relation to tidal influence with estuarine, mixing and marine areas. The aim of this work is to conduct a comparative study on the processes controlling the groundwater salinity in medium to high latitudinal coastal wetlands of four natural reserves with contrasting hydrological and climatic conditions. In each study area a monitoring network was established where the content of CO₃^2-, HCO₃^-, Cl^-, SO₄^2-, Ca²⁺, Mg²⁺, Na⁺, K⁺, δ²H and δ¹⁸O of the water were determined. The results show a saline groundwater increase along a latitudinal gradient with electrical conductivities varying from 0.3 mS/cm at 34°47' S to 154 mS/cm at 42° 25' S. The results obtained show that the ionic contents in groundwater are partially controlled by the salinity of the tidal flood water whose electrical conductivity varies from 0.3 mS/cm in the Río de la Plata estuary to 52 mS/cm in the sea water of the southern study area. In the southern wetlands, where an increase of aridity is also registered, there is a clear increase in groundwater ionic concentrations, which occurs without isotopic enrichment indicating processes of salts dissolution of the sediments. The evaporites precipitation occurs due to the total evaporation of the tidal water that floods the wetlands in spring high tides. The salinization of groundwater responds to natural processes inherent to the hydrological, climatic and lithological characteristics of each wetland. Given that the areas studied correspond to natural reserves, the results generate databases that will allow the identification of future changes in salinity associated with anthropic influences or changes in hydrological and/or climatic conditions as a result of climate change.

Geochemical mechanisms controlling the isotopic and chemical composition of groundwater and surface water in a sector of the Pampean plain (Argentina)

The Samborombón River basin, which has eminently rural characteristics, develops within the Pampean plain along with other basins with serious contamination problems due to the growth of the industrial activities and the absence of a proper groundwater management. Considering that the knowledge of the natural baseline quality is important to measure an imposed environmental change, the aim of this work was to study the mechanisms that control the natural composition of groundwater and superficial water in the Samborombón River basin. In order to achieve this, detailed analysis of the minerals forming the aquifer matrix along with the data obtained from isotopes, major and trace elements were performed. Geochemical processes that define the chemical characteristics and contribute to the evolution of both surface and groundwater are associated with rainwater infiltration, carbonate dissolution, cation exchange and evaporation. Additionally, the low concentration of heavy metals may respond to natural background levels. Comprehending the hydrochemical processes governing groundwater and superficial water quality, particularly in a rural area where water supply is vital for the development of human activities, is essential to prevent environmental deterioration and thus, enhance socio-economic growth.

Industrial waste as a source of surface and groundwater pollution for more than half a century in a sector of the Río de la Plata coastal plain (Argentina)

Environmental liabilities have become one of the most important problems of the last years, especially those of contaminated sites located in urban areas which have been abandoned by pollution intensive industries. Such sites may contain hazardous materials that pose risks to human health and the environment. Industrial waste from the ancient sulfuric acid industry is scattered in a local area at the petrochemical pole in a sector of the Río de la Plata coastal plain. The aim of this work is to define the geochemical processes that determine the alteration of waste in the old sulfuric acid industry (OSAI) area and to study the migration of soluble pollutants to groundwater. A survey of soil and waste deposit was carried out and samples were examined by X-ray diffraction, under a scanning electron microscope and a polarizing microscope. Surface water and groundwater samples, both to the unconfined and semi-confined aquifers, were collected to determine electrical conductivity, pH and major elements. The results show the presence of minerals composed of sulfur associated with jarosite and iron oxides on superficial sediments. The detailed study of soil sediments together with that of the water physicochemical characteristics make it possible to understand the geochemical processes developed in soil that cause the high concentrations of sulfates in groundwater. Furthermore, high SO₄^-2 concentration registered in the semi-confined aquifer due to its infiltration from the unconfined aquifer shows that the industrial pollution has an important impact at local level. These results may contribute to the understanding of chemical processes and pollutants distribution in highly industrialized coastal plain areas.

Freshwater lenses as ecological and population sustenance, case study in the coastal wetland of Samborombón Bay (Argentina)

Freshwater lenses associated to shell ridges and sand sheets exist on the coastal wetland of Samborombón Bay. As they constitute one of the most vulnerable aquifer systems, it is the aim of this study to determine the hydrogeochemical processes that condition the chemical quality of its groundwater and to assess their present and future capability as sustenance of native woods and local villagers. To achieve this, hydrogeomorphological field surveys were made and groundwater samples were taken. Results show that lenses have a mean thickness of 12m and its chemical quality depends on the dissolution of CO_2(g) and carbonates, weathering of silicates and ion exchange. Lenses can be affected by long-term climatic variability and mining. The study of morphology and geochemistry of the freshwater lenses bring lights into important information about the management of water resources and conservation of the environment.

Hydrogeochemical and isotopic signature of surface and groundwater in a highly industrialized sector of the Rio de la Plata coastal plain (Argentina)

The coastal plain of the middle estuary of the Río de la Plata is a highly industrialized area and is densely populated by sectors. The main human activity in the sector encompassed between the cities of Ensenada and Berisso is associated with the petrochemical industry. In this work, hydrogeochemical and isotopic characteristics of surface and groundwater in the impacted area are analyzed and the results are contrasted with those obtained in an undisturbed protected area. Major and trace elements were determined using standardized methods while the stable isotopes δ¹⁸O y δ²H were analyzed by mass spectroscopy. Human impact is evidenced by the occurrence of large variations in the major chemical composition of water, and also by the elevated concentrations of some trace elements that are not contributed from natural sources. These results may contribute to the understanding of chemical processes and pollutants distribution in highly industrialized coastal plain areas.

Non-invasive hemodynamic analysis in cardiac resynchronization therapy patients wearing quadripolar left ventricular leads: the importance of pacing electrode selection

AIM

Quadripolar left ventricular (LV) leads offer multiple choices for LV pacing increasing programming flexibility. Aim of this study is to assess the influence of LV pacing vector selection on hemodynamic parameters for patients who underwent cardiac resynchronization therapy (CRT) using quadripolar LV lead chronically evaluated with a non-invasive approach by Nexfin(®) system provided analysis (BMEYE B.V., Amsterdam, The Netherlands).

METHODS AND RESULTS

In 16 CRT patients implanted with a quadripolar LV lead (mean follow-up 8,8 ±13,4 months after implantation), we measured Cardiac Output (CO), Mean Blood Pressure (MBP), Total Peripheral Resistance (TPR), LV dP/dt max and Stroke volume (SV) from each one of the ten available bipolar pacing configurations. All the recorded parameters showed marked differences among the ten pacing configurations, but dP/dt max, SV and TPR were those showing the wider range, depending of the selected pacing vector. The average delta for the whole group of subjects between the maximum and minimum hemodynamic values for each pacing configuration were 15.9% for SV, 21.1% for dP/dt max and 20.3% for TPR. Inter-individual analysis of data failed to identify a link between a specific pacing vector and the hemodynamic response.

CONCLUSION

Our study demonstrates that different bipolar pacing configurations, even if arising from a single CS branch, substantially modify the hemodynamic effect of LV pacing in CRT patients. Moreover, the non-invasive hemodynamic analysis suggests the better pacing configuration should be established individually and could represent an important issue in optimizing CRT during follow-up.

NSAIDs, coxibs, CINOD and H2S-releasing NSAIDs: what lies beyond the horizon

Nonsteroidal anti-inflammatory drugs are widely prescribed for treatment of pain and inflammation, despite their association with gastrointestinal complications, including bleeding and perforation. Inhibition of cyclo-oxygenases, is the main mechanism of action of aspirin and nonsteroidal anti-inflammatory drugs. Non-selective nonsteroidal anti-inflammatory drugs inhibit cyclo-oxygenase-1 and cyclo-oxygenase-2. Inhibition of cyclo-oxygenase-1 derived prostanoids in the stomach represent the underlying mechanism involved in development of gastric and duodenal ulcers in patients taking nonsteroidal anti-inflammatory drugs. Selective cyclo-oxygenases-2 inhibitor (coxibs) spare cyclo-oxygenase-1 show enhanced safety profile in the gastrointestinal tract, but increase the risk of heart attack and stroke. Spurred by these findings, two coxibs, rofecoxib and valdecoxib, were withdrawn from the market. In addition to prostanoids, two gaseous mediators, nitric oxide (NO) and hydrogen sulfide (H(2)S) exert protective effects in gastric mucosa. The inhibitory effects of NO on nonsteroidal anti-inflammatory drugs-induced leukocyte adherence have been exploited in the development of NO-releasing nonsteroidal anti-inflammatory drugs, also indicated as cyclo-oxygenase-inhibiting NO-donating drugs. Despite its non-selective profile versus cyclo-oxygenase isoenzymes, naprocyclo-oxygenase-inhibiting NO-donating drugs, the prototype of this class of anti-inflammatory agents, reduces systemic blood pressure and might have enhanced cardiovascular safety than coxibs, while causing less gastrointestinal damage than its parent drug, the naproxen. H(2)S-releasing nonsteroidal anti-inflammatory drugs derivatives have been recently developed, based on the observed ability of this gaseous mediator to cause vasodilation and to prevent leukocyte adherence. In pre-clinical settings, H(2)S-releasing nonsteroidal anti-inflammatory drugs produce less gastric damage as compared to the parent drugs. Cyclo-oxygenases-inhibiting NO-donating drugs and H(2)S-releasing nonsteroidal anti-inflammatory drugs represent examples of new anti-inflammatory drugs created through the exploitation of the beneficial effects of endogenous gaseous mediators in the gastrointestinal and cardiovascular systems.

Enhanced activity of a hydrogen sulphide-releasing derivative of mesalamine (ATB-429) in a mouse model of colitis

BACKGROUND AND PURPOSE

Mesalamine is the first-line therapy for colitis, but it lacks potency and is only effective for mild-to-moderate forms of this disease. Hydrogen sulphide has been shown to be a potent, endogenous anti-inflammatory substance, modulating leukocyte-endothelial adhesion and leukocyte migration. The purpose of this study was to determine if an H(2)S-releasing derivative of mesalamine (ATB-429) would exhibit increased potency and effectiveness in a mouse model of colitis.

EXPERIMENTAL APPROACH

Colitis was induced in mice with trinitrobenzene sulphonic acid and the effects of ATB-429 and mesalamine were compared in several treatment regimens. The severity of colitis was determined using several indices, including a disease activity score (comprised of scores for diarrhea, weight loss and fecal blood), colonic myeloperoxidase activity and macroscopic/microscopic scoring of tissue injury.

KEY RESULTS

Irrespective of the treatment regiment, ATB-429 was more effective than mesalamine in reducing the severity of colitis. ATB-429 was particularly effective in reducing granulocyte infiltration into the colonic tissue (by approximately 70%), as well as reducing the expression of mRNA for several key proinflammatory cytokines/chemokines (e.g., TNFalpha, IFNgamma). Treatment with ADT-OH, the H(2)S-releasing moiety of ATB-429, did not affect severity of colitis.

CONCLUSIONS AND IMPLICATIONS

ATB-429 exhibits a marked increase in anti-inflammatory activity and potency in a murine model of colitis, as compared to mesalamine. These results are consistent with recently described anti-inflammatory effects of H(2)S. ATB-429 may represent an attractive alternative to mesalamine for the treatment of inflammatory bowel disease.

GITR modulates innate and adaptive mucosal immunity during the development of experimental colitis in mice

BACKGROUND

Uncontrolled T cell activation and abnormal function of the innate immune system against normal enteric bacterial flora play a critical part in the pathogenesis of inflammatory bowel disease (IBD). Therefore, pharmacological strategies directed to restore the normal responsiveness of the immune system could be efficacious in the treatment of these pathological conditions. Glucocorticoid-induced tumour necrosis factor receptor (GITR)-related gene is a member of the tumour necrosis factor receptor superfamily that is constitutively expressed at high levels on regulatory T cells and at low levels on unstimulated T cells, B cells and macrophages. GITR triggering leads to activation of T effectors and reversal of suppressive function of regulatory T cells.

AIM

To investigate the role of GITR in the development of experimental colitis in mice.

RESULTS

Using GITR(-/-) mice, GITR deletion protected against 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced colitis by reducing innate immune responses and effector T cell activity. Effector T cells isolated from GITR(-/-) mice were less effective than T cells isolated from GITR(+/+) mice to transfer colitis in immunodeficient mice. Blocking the GITR/ligand for GITR (GITRL) signal by giving soluble GITR prevented TNBS-induced colitis in normal GITR(+/+) and also in lymphocyte-deficient SCID mice.

CONCLUSIONS

Collectively, these data suggest that GITR plays a critical part in regulating both acquired and innate mucosal immune responses during the development of experimental colitis in mice. Therefore, targeting the GITR/GITRL system signalling may represent a potential pharmacological tool for the treatment of IBD.

Circulating anti-actin and anti-ATP synthase antibodies identify a sub-set of patients with idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome (iNS) with resistance or dependence to steroids is a common disease in children but in spite of an increasing clinical impact its pathogenesis is unknown. We screened for the presence of circulating antibodies against glomerular (podocytes, mesangium) and tubular cells (tubular epithelia) a cohort of 60 children with iNS including 8 patients with a familial trait of iNS or with proven mutation of NPHS1-NPHS2 and 12 with good sensitivity to steroids. Positive sera were found in 8 cases, all belonging to the category without familial trait/molecular defects. The targets of antibodies were characterized with Western blot and MALDI-Mass utilizing beta-hexyl cell extracts separated with two-dimensional electrophoresis. In all cases antibodies of the IgM class were directed against ATP synthase beta chain alone (4 cases) or in combination with actin (3 cases); one child presented IgG against aldose reductase. The clinical picture was nephrotic syndrome with steroid resistance or dependence and variable cyclosporin sensitivity; 3 patients developed end stage renal failure. The basic pathology picture was focal segmental glomerulosclerosis (FSGS) in 4 cases and mesangial proliferative glomerulonephrites with deposition of IgM in 2. Overall, patients with circulating auto-antibodies could not be readely differentiated on clinical grounds with the exception of 3 children who developed positivity for antinuclear antibodies during the follow-up. Affinity-purified IgM from one patient who underwent plasmapheresis for therapeutical pourposes (but not from a normal pool) induced proteinuria in Sprague-Dawley rats and concomitant human IgM deposition within glomeruli. This is the first report of circulating anti-actin/ATP synthase beta chain antibodies in a subset of patients with iNS. Both pathological significance and clinical impact given by the presence of these antibodies and the relationship with other conditions such as lupus-erythematosus, characterized by their presence, must be defined.

IL-1 beta converting enzyme is a target for nitric oxide-releasing aspirin: new insights in the antiinflammatory mechanism of nitric oxide-releasing nonsteroidal antiinflammatory drugs

Caspase-1, the IL-1beta converting enzyme (ICE), is required for intracellular processing/maturation of IL-1beta and IL-18. NO releasing nonsteroidal antiinflammatory drugs (NSAIDs) are a new class of NSAID derivatives that spare the gastric mucosa. Here, we tested the hypothesis that NCX-4016, a NO-aspirin derivative, inhibits proinflammatory cytokine release from endotoxin (LPS)-challenged monocytes. Our results demonstrated that exposing LPS-stimulated human monocytes to NCX-4016 resulted in a 40-80% inhibition of IL-1beta, IL-8, IL-12, IL-18, IFN-gamma, and TNF-alpha release with an EC(50) of 10-20 microM for IL-1beta and IL-18. Incubating LPS-primed monocytes with NCX-4016 resulted in intracellular NO formation as assessed by measuring nitrite/nitrate, intracellular cGMP concentration, and intracellular NO formation. Exposing LPS-stimulated monocytes to aspirin or celecoxib caused a 90% inhibition of prostaglandin E(2) generation but had no effect on cytokine release. NCX-4016, similar to the NO donor S-nitroso-N-acetyl-D-L-penicillamine, inhibited caspase-1 activity with an EC(50) of approximately 20 microM. The inhibition of caspase-1 by NCX-4016 was reversible by the addition of DTT, which is consistent with S-nitrosylation as the mechanism of caspase-1 inhibition. NCX-4016, but not aspirin, prevented ICE activation as measured by assessing the release of ICE p20 subunit. IL-18 immunoneutralization resulted in a 60-80% reduction of IL-1beta, IL-8, IFN-gamma, and TNF-alpha release from LPS-stimulated monocytes. Taken together, these data indicate that incubating human monocytes with NCX-4016 causes intracellular NO formation and suppresses IL-1beta and IL-18 processing by inhibiting caspase-1 activity. Caspase-1 inhibition is a new, cycloxygenase-independent antiinflammatory mechanism of NO-aspirin.

Galectin-1 exerts immunomodulatory and protective effects on concanavalin A-induced hepatitis in mice

Galectin-1, an endogenous lectin with immunomodulatory activities, induces selective, Fas-independent apoptosis of activated T cells. The aim of the present study was to evaluate the effect galectin-1 exerts on concanavalin A (Con A)-induced hepatitis, a T-cell-dependent model of liver injury. Con A administration resulted in liver injury, as shown by the increased transaminase plasma levels and liver DNA fragmentation, and caused spleen T-cell activation, which was associated with a strong increment in liver infiltrating T helper cells. Moreover, Con A injection leads to a marked increase in plasma tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) levels. Galectin-1 pretreatment dose-dependently prevented both liver injury and T-helper cell liver infiltration induced by Con A. In vivo and in vitro experiments indicated that the protective effects of galectin-1 depend on the selective elimination of Con A-activated T cells. In addition, galectin-1 almost completely prevented the Con A-induced increase in plasma TNF-alpha and IFN-gamma, an effect that was, at least in part, independent on the elimination of activated T helper cells, because galectin-1 prevented lipopolysaccharide (LPS)-induced release of TNF-alpha and IFN-gamma also from macrophages in vitro, without affecting their viability. The present study suggests that galectin-1 is potentially useful in the treatment of T-cell-mediated human liver disorders.

NO-aspirin protects from T cell-mediated liver injury by inhibiting caspase-dependent processing of Th1-like cytokines

BACKGROUND & AIMS

Concanavalin A (con A)-induced hepatitis is an immunomediated disease in which assembly of CD4(+) T cells and T helper (Th)1-like cytokines causes Fas-mediated liver cell death. Nitric oxide (NO) modulates Th1 response in vitro. NCX-4016 is an NO-aspirin derivative that spares the gastrointestinal tract and shares molecular targets with NO. The aim of this study was to investigate whether this NO-aspirin modulates Th1-like response induced by con A.

METHODS

BALB/c mice were injected with 0.3 mg con A per mouse alone or in combination with NO-aspirin (18-100 mg/kg) or aspirin (10-55 mg/kg).

RESULTS

NO-aspirin, but not aspirin, caused a dose-dependent protection against liver damage induced by con A. At a dose of 100 mg/kg, NO-aspirin caused a 40%-80% reduction of interleukin (IL)-1beta, IL-12, IL-18, interferon (IFN)-gamma, and tumor necrosis factor alpha production without affecting cytokine messenger RNA expression. NO-aspirin prevented Fas, Fas ligand, and IL-2 receptor up-regulation on spleen lymphocytes and Fas ligand on hepatocytes and caused the S-nitrosylation/inhibition of IL-1beta-converting enzyme-like cysteine proteases (caspases) involved in the processing and maturation of IL-1beta and IL-18. IL-18 immunoneutralization prevented IFN-gamma release and protected from liver injury induced by con A. In contrast to a selective caspase 1 inhibitor, zVAD.FMK, a pancaspase inhibitor, prevented IFN-gamma release and protected the liver from injury.

CONCLUSIONS

Th1-like response induced by con A is mediated by IL-18 and requires activation of multiple caspases. NCX-4016 causes the S-nitrosylation/inhibition of caspases involved in cytokine production. Inhibition of Th1-like response is a new anti-inflammatory mechanism of action of NO-aspirin.

Anti-very late antigen-1 monoclonal antibody modulates the development of secondary lesion and T-cell response in experimental arthritis

Rats injected in the hind paw with a mixture of Mycobacterium butirricum emulsified in mineral oil (FA) developed a severe polyarthritis that shared some immunological features with human rheumatoid arthritis. After this local administration, rats developed a secondary lesion (edema) in the contralateral paw, which is a hallmark of immune system activation. In vivo intravenous treatment with a monoclonal anti-very late antigen (VLA)-1 antibody (HA31/8) significantly reduced the edema formation in the contralateral paw. T cells isolated from contralateral paw draining lymph nodes of FA rats treated with HA31/8 showed a reduced cell proliferation in vitro, after stimulation with concanavalin A. Furthermore FACS analysis showed that the reduction in proliferation was concomitant to a reduction in the number of T cells positive to surface IL-2 receptor expression. Our data indicate that after in vivo treatment with a monoclonal anti-very late antigen-1 antibody, there is a beneficial effect on the development of the secondary lesion, which correlates to the reduced ability of T cells to proliferate in vitro as well as to a reduced surface expression of IL-2 receptor. The association of this antibody to other drugs interfering at other levels in rheumatoid arthritis may open a new therapeutic window.

Gastrointestinal safety of nitric oxide-derived aspirin is related to inhibition of ICE-like cysteine proteases in rats

BACKGROUND & AIMS

Caspases, a class of cysteine proteases, modulate apoptosis. Nitric oxide (NO)-releasing nonsteroidal anti-inflammatory drugs (NSAIDs) are a new class of NSAID derivatives with reduced gastrointestinal toxicity. The aim of this study was to investigate whether cysteine endoproteases are involved in the pathogenesis of NSAID gastropathy and are target for NO-aspirin (NCX-4016).

METHODS

Rats were treated orally with aspirin or equimolar doses of NCX-4016. Caspase activities were measured by fluorometric assay. Apoptosis was quantified by an enzyme-linked immunosorbent assay for histone-associated DNA, DNA ladder on agarose gel, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay. A primary culture of gastric chief cells was used to investigate whether NCX-4016 modulates guanosine 3',5'-cyclic monophosphate (cGMP)-dependent pathways.

RESULTS

Short- and long-term (7 days) aspirin administration resulted in a time- and dose-dependent gastric injury that was associated with apoptosis and caspase up-regulation. Z-VAD.FMK, a pancaspase inhibitor, and NO donors protected from acute damage induced by aspirin. NCX-4016 spared the gastric mucosa and caused caspase inactivation by S-nitrosylation. Inhibition of tumor necrosis factor (TNF)-alpha release or activity by TAPI-2 or anti-TNF-alpha receptor monoclonal antibodies protected against mucosal damage and caspase activation. NCX-4016 protected gastric chief cells from toxicity induced by TNF-alpha by activating cGMP-dependent pathways.

CONCLUSIONS

Aspirin administration leads to a TNF-alpha-dependent activation of gastric caspases. NO-aspirin spares the gastric mucosa and inhibits caspase activity through cGMP-dependent and -independent pathways.

Nitric oxide-releasing NSAIDs inhibit interleukin-1beta converting enzyme-like cysteine proteases and protect endothelial cells from apoptosis induced by TNFalpha

BACKGROUND

Nitric oxide (NO)-releasing NSAIDs are a new class of NSAID derivatives with markedly reduced gastrointestinal toxicity. Although it has been demonstrated that NO-NSAIDs spare gastric mucosal blood flow, molecular determinants involved in this effect are unknown.

AIM

To investigate the effect of aspirin, naproxen and flurbiprofen, and their NO-derivatives, on gastric apoptosis and endothelial cell damage induced by tumour necrosis factor-alpha (TNFalpha). In other systems, TNFalpha-induced apoptosis is mediated by caspases, a growing family of cysteine proteases similar to the IL-1beta converting enzyme (ICE), and so we have investigated whether NO-NSAIDs modulate ICE-like endopeptidases.

METHODS

Rats were treated orally with aspirin, naproxen and flurbiprofen, or their NO-releasing derivatives in equimolar doses, and were killed 3 h later to assess mucosal damage and caspase activity. Endothelial cells (HUVECs) were obtained from human umbilical cord by enzymatic digestion. Caspase 1 and 3 activities were measured by a fluorimetric assay using selective peptides as substrates and inhibitors. Apoptosis was quantified by ELISA specific for histone-associated DNA fragments and by the terminal transferase nick-end translation method (TUNEL).

RESULTS

In vivo NSAID administration caused a time-dependent increase in gastric mucosal damage and caspase activity. NCX-4016, NO-naproxen and NO-flurbiprofen did not cause any mucosal damage and prevented cysteine protease activation. NSAIDs and NO-NSAIDs stimulated TNFalpha release. Exposure to TNFalpha resulted in a time- and concentration-dependent HUVEC apoptosis, an effect that was prevented by pretreating the cells with NCX-4016, NO-naproxen, NO-flurbiprofen, SNP or Z-VAD.FMK, a pan-caspase inhibitor. The activation of ICE-like cysteine proteases was required to mediate TNFalpha-induced apoptosis of HUVECs. Exogenous NO donors inhibited TNFalpha-induced cysteine protease activation. Inhibition of caspase activity was due to S-nitrosylation of ICE/CPP32-like proteases. NO-NSAIDs prevented IL-1beta release from endotoxin-stimulated macrophages.

CONCLUSIONS

NO-releasing NSAIDs are a new class of non-peptide caspase inhibitors. Inhibition of ICE-like cysteine proteases prevents endothelial cell damage induced by pro-inflammatory agents and might contribute to the gastro-protective effects of NO-NSAIDs.

TNFalpha processing enzyme inhibitors prevent aspirin-induced TNFalpha release and protect against gastric mucosal injury in rats

BACKGROUND

Although previous studies indicate that prevention of tumour necrosis factor alpha (TNFalpha) release protects against NSAID-induced gastric mucosal injury, intracellular pathways by which aspirin causes TNFalpha release are unknown. TNFalpha is synthesized as a precursor which is proteolytically cleaved by a specific converting enzyme, TACE, to release the mature cytokine. TACE inhibitors prevent TNFalpha release and protect against TNFalpha-mediated disease.

AIM

To investigate: (i) molecular events that regulate TNFalpha secretion in response to aspirin in vivo and in vitro; (ii) whether TNFalpha secretion inhibitors prevent aspirin-induced TNFalpha release and protect against gastric mucosal damage; and (iii) whether TNFalpha exerts a direct cytotoxic effect on gastric epithelial cells.

METHODS

In vitro studies were carried out on mouse macrophages and rat gastric mucosal cells. Gastric mucosal damage was induced in rats by oral administration of 300 mg/kg aspirin. TNFalpha cytotoxicity on gastric mucosal cells was examined by treating rats with lipopolysaccharide to release TNFalpha or by incubating dispersed gastric mucosal cells with increasing concentrations of TNFalpha.

RESULTS

Aspirin increases intracellular calcium (Ca2+) levels and causes a time and concentration dependent increase in macrophage TNFalpha mRNA accumulation and cytokine release. Agents that cause Ca2+ mobilization with a receptor-independent mechanism, such as ionomycin and thapsigargin, stimulate TNFalpha release. Incubating the macrophages in a Ca2+ free medium inhibited TNFalpha secretion. Agents that prevent TNFalpha mRNA transcription, e.g. lisophylline, PGE2, interleukin-10 and 8-BrcAMP, or TACE inhibitors, e.g. EDTA, TAPI-2 and BB-3103, inhibit TNFalpha release and protect rats against gastric mucosal injury induced by oral administration of aspirin. TNFalpha exerts a direct cytotoxic effect on gastric epithelial cells as demonstrated by the reduced viability observed in gastric mucosal cells prepared from rats treated with lipopolysaccharide, or directly incubated with increasing concentrations of TNFalpha.

CONCLUSIONS

(i) Aspirin directly stimulates TNFalpha gene transcription; (ii) TACE inhibitors protect against aspirin-induced gastric mucosal injury; and (iii) TNFalpha exerts a direct cytotoxic effect on gastric epithelial cells.

NSAIDs upregulate beta 2-integrin expression on human neutrophils through a calcium-dependent pathway

BACKGROUND

Margination of circulating neutrophils (PMN) into the gastric microcirculation is an early and critical event in the pathogenesis of non-steroidal antinflammatory drug (NSAID)-induced gastropathy. This effect is mediated through the upregulation of beta 2 integrins on the PMN surface.

AIMS

To investigate whether indomethacin modulates: (1) Mac-1 expression; (2) Ca2+ mobilization ([Ca2+]i), protein kinase C and nitric oxide accumulation; and (3) mitogen-associated protein kinase phosphorylation in human PMN.

METHODS

Human PMN were isolated by centrifugation through a double Ficoll gradient. [Ca2+]i was measured in PMN loaded with fura-2 and Mac-1 expression by flow cytometry.

RESULTS

Indomethacin caused a concentration- and time-dependent upregulation of CD11b and CD18 expression and PMN adhesion to endothelial cells. Maximal upregulation of Mac-1 expression (40-50%) occurred after a 30-min incubation with 0.1mM indomethacin. The effect was prevented by removing the Ca2+. Ionomycin and thapsigargin caused a 7-10-fold increase in [Ca2+]i and a 2-4-fold increase in Mac-1 expression. Indomethacin induced a concentration-dependent phosphorylation of a 41-kDa mitogen-associated protein kinase. Tyrosine kinase inhibitors prevented the effect of indomethacin on Mac-1 expression and Ca2+ mobilization. Indomethacin and ionomycin increased superoxide generation, myeloperoxidase secretion and PMN adherence to endothelial cells and stimulated nitric oxide production. Indomethacin-induced Mac-1 upregulation was prevented by a nitric oxide synthase inhibitor.

CONCLUSIONS

Indomethacin-induced upregulation of Mac-1 is mediated by changes in [Ca2+]i and nitric oxide. Phosphorylation of the 41-kDa mitogen-associated protein isoform is a previously unreported target of NSAID action. These effects might help to explain the ability of indomethacin to cause gastric neutrophil margination.

Epidermal growth factor modulates pepsinogen secretion in guinea pig gastric chief cells

BACKGROUND & AIMS

Although epidermal growth factor (EGF) inhibits gastric acid secretion, the effects it exerts on gastric chief cells are unknown. The aim of this study was to investigate whether EGF modulates pepsinogen release and intracellular Ca2+ concentrations ([Ca2+]i) and whether the effect involves mitogen-activated protein (MAP) kinase, eicosanoid generation, and nitric oxide.

METHODS

Chief cells were obtained by sequential digestion with collagenase and Ca2+ chelation. [Ca2+]i was measured in cells loaded with Fura-2 and NO generation by the NO coproduct citrulline.

RESULTS

In situ hybridization, immunohistochemistry, and immunoblotting showed that EGF receptor and MAP kinases were constitutively expressed in chief cells. EGF caused a concentration-dependent stimulation of pepsinogen secretion and MAP kinase activity and determined a 2.5-7.0-fold increase in [Ca2+]i, inositol 1,4,5-tryphosphate, prostaglandin E2, and leukotriene B4. Tyrosine kinase inhibitors and cyclooxygenase and lipoxygenase inhibitors reduced pepsinogen secretion and eicosanoid generation induced by EGF. EGF increased citrulline generation and guanosine 3',5'-cyclic monophosphate accumulation sixfold; the effect was blocked by NG monomethyl-L-arginine, which is an NO synthase inhibitor.

CONCLUSIONS

EGF stimulates pepsinogen secretion by activating eicosanoid generation, tyrosine kinases, MAP kinases, Ca2+, NO, and guanosine 3',5'-cyclic monophosphate.

Interleukin 10 reduces lethality and hepatic injury induced by lipopolysaccharide in galactosamine-sensitized mice

BACKGROUND & AIMS

Tumor necrosis factor alpha (TNF-alpha) release plays a pivotal role in the pathogenesis of liver injury induced by lipopolysaccharide (LPS) administration in D-galactosamine (GalN)-sensitized mice. Interleukin (IL) 10 is an anti-inflammatory cytokine that inhibits TNF-alpha synthesis and release both in vitro and in vivo and prevents lethality from experimental endotoxemia. The present study was designed to ascertain whether in vivo treatment with IL-10 protects mice against LPS/GalN-induced liver injury.

METHODS

Mice were treated with an intraperitoneal dose of LPS/GalN with or without IL-10 pretreatment. Liver injury was assessed biochemically and histologically, and plasma TNF-alpha levels, liver myeloperoxidase activity, and adhesion molecule expression were determined.

RESULTS

Administration of LPS in GalN-sensitized mice caused lethal shock and massive hepatic necrosis in almost 100% of the mice. The effect was associated with a significant increase in plasma TNF-alpha concentrations, liver myeloperoxidase activity, and up-regulation of adhesion molecules on liver specimens and circulating neutrophils. Pretreatment with IL-10 reduced plasma TNF-alpha concentrations and LPS/GalN-induced liver injury and lethality. Moreover, IL-10 reduced the LPS/GalN-induced liver neutrophil margination and up-regulation of adhesion molecules both on liver specimens and circulating neutrophils.

CONCLUSIONS

The present results suggest that IL-10 therapy could be useful in the treatment of TNF-alpha-mediated liver diseases.

Selective endoscopic retrograde cholangiography and preoperative bile duct stone removal in patients scheduled for laparoscopic cholecystectomy: a prospective study

OBJECTIVES

Laparoscopic cholecystectomy (LC) has become the treatment of choice for patients with symptomatic cholelithiasis. About 10% of patients with symptomatic gallstones may bear associated common bile duct (CBD) stones. The preferred approach to these patients is the removal of CBD stones by endoscopic retrograde cholangiography (ERCP) before LC. However, ERCP before LC should be performed only in patients with suspected choledocholithiasis. The aims of this study were to: 1) generate an efficacious predictive model for selecting patients with suspected choledocholithiasis to submit to preoperative ERCP, and 2) test the safety of the endoscopic/laparoscopic procedure.

METHODS

Historical, biochemical, and ultrasonographic data were collected prospectively. Receiver operating characteristics curve analysis was adopted for determining optimal biochemical and ultrasonographic cut-off values. Multivariate analysis using logistic regression with generation of the best model identifying independent predictors of CBD stones was also employed.

RESULTS

The optimal model predicted a 95% probability of CBD stones in a patient who presented with elevated ALP (over 300 IU/L) and ALT (over 40 IU/L) levels and CBD dilation > 8 mm at ultrasonography. Endoscopic removal of CBD stones was achieved in 95% of patients, with minimal morbidity and no mortality.

CONCLUSIONS

The identified independent predictors of CBD stones are highly efficient selectors of patients with choledocholithiasis. Moreover, endoscopic removal of CBD stones before LC is a safe and efficacious procedure.

A 4-week, double-blind, parallel-group study to compare the gastrointestinal effects of meloxicam 7.5 mg, meloxicam 15 mg, piroxicam 20 mg and placebo by means of faecal blood loss, endoscopy and symptom evaluation in healthy volunteers

Meloxicam is a new non-steroidal anti-inflammatory drug (NSAID) which preferentially inhibits cyclooxygenase-2 (COX-2) over cyclooxygenase-1 (COX-1). Gastrointestinal (GI) tolerability of meloxicam 7.5 and 15 mg vs piroxicam 20 mg was evaluated in a 4-week, double-blind, parallel group, placebo-controlled study in 51 healthy male volunteers, using a combination of oesphago-gastro-duodenal endoscopy, faecal blood loss measurement and symptom evaluation. Analysis of covariance found no significant difference in faecal blood loss between the groups. However, significantly higher bleeding was found with piroxicam 20 mg compared with placebo using a Student's t-test on the weighted means. Endoscopy score were significantly higher with piroxicam than with meloxicam 7.5 mg or placebo (P < 0.01). A significant difference from baseline was observed in the meloxicam 15 mg and piroxicam groups (P < 0.05), but not in the meloxicam 7.5 mg and placebo groups. Six piroxicam-treated volunteers were withdrawn following a poor endoscopic score, but no such withdrawals occurred in the meloxicam and placebo groups (P < 0.01). Meloxicam 7.5 mg caused less GI damage compared with piroxicam 20 when administered to healthy young volunteers for 28 days; a possible dose dependency effect in GI tolerability was also suggested for meloxicam 7.5 and 15 mg, in relation to endoscopic findings.

Isolated guinea pig gastric chief cells express tumour necrosis factor receptors coupled with the sphingomyelin pathway

The tumour necrosis factor alpha (TNF), has been implicated in the pathogenesis of non-steroidal anti-inflammatory drug (NSAID) induced gastropathy and Helicobacter pylori induced gastritis. Both conditions are characterised by high plasma pepsinogen concentrations, which are thought to reflect an increased rate of enzyme release by the pepsinogen secreting (chief) cells. The mechanisms responsible for this cell dysfunction are unknown. This study investigates whether chief cells express TNF receptors and, if so, whether their activation results in cell death. Immunohistochemical studies conducted with monoclonal antibodies (mAbs) directed against two TNF receptor associated proteins of 55 kDa (TNF-R1) and 75 kDa (TNF-R2) showed that TNF binding sites were expressed in approximately 100% gastric chief cells. Western blot analysis of whole chief cell lysates probed with the TNF-R1 and TNF-R2 mAbs gave two distinct bands of 55 and 75 kDa in the immunoprecipitate. Incubating chief cells with TNF caused concentration and time dependent cell death, which was prevented by pretreating the cells with anti-TNF receptor mAbs. Exposing the cells to TNF reduced sphingomyelin content by 25%. Sphingomyelinase (10(-6) to 10(-2) IU/ml) mimicked the effect of TNF in that it provoked a concentration and time dependent reduction in chief cell viability and increased pepsinogen release. In conclusion, gastric chief cells express two TNF receptors partially linked to the sphingomyelin pathway. TNF induced chief cell dysfunction might be responsible for the high plasma pepsinogen concentrations seen in patients with NSAID gastropathy or H pylori induced gastritis.

Nitric oxide modulates pepsinogen secretion induced by calcium-mediated agonist in guinea pig gastric chief cells

BACKGROUND & AIMS

Nitric oxide, a putative cellular messenger synthesized from L-arginine, is a powerful modulator of gastric motility and secretions. The aim of this study was to investigate whether (1) guinea pig gastric chief cells express NO synthase, (2) NO modulates the pepsinogen secretion and guanosine 3',5'-cyclic monophosphate (cGMP) generation induced by calcium (Ca2+)-mediated agents, and (3) NO donors and cGMP analogues stimulate pepsinogen release.

METHODS

Chief cells were prepared by sequential digestion with collagenase and Ca2+ chelation. NO generation was measured by determining the NO coproduct citrulline.

RESULTS

NO synthase immunoreactivities were constitutively expressed in approximately 70% chief cells. Carbachol (10 mumol/L) caused a 4- 6-fold increase in pepsinogen release, citrulline generation, intracellular Ca2+ concentration ([Ca2+]i) and cGMP concentration. These effects were concentration dependently inhibited by NG-monomethyl-L-arginine (L-NMMA). As gastrin, cholecystokinin, thapsigargin, and Ca2+ ionophore increased NO generation, [Ca2+]i seemed to regulate NO synthase activity. [Ca2+]i chelator and calmodulin antagonist inhibited the carbachol-induced pepsinogen secretion and NO generation. Preincubating the cells with L-NMMA had no effect on carbachol-stimulated inositol triphosphate generation or [Ca2+]i or Ca(2+)-dependent adenosine triphosphatase levels. Nitrovasodilator agents and 8-bromo-cGMP stimulated pepsinogen release.

CONCLUSIONS

Gastric chief cells express a Ca2+/calmodulin-dependent NO synthase. NO modulates the stimulatory effect of Ca(2+)-mediated agonists on pepsinogen release.

Severe gastric mucosal damage induced by NSAIDs in healthy subjects is associated with Helicobacter pylori infection and high levels of serum pepsinogens

Helicobacter pylori infection and NSAIDs are considered the two most important exogenous factors in ulcer disease. The interrelation between the two factors is not, however, clear. Moreover, serum pepsinogen has been suggested as a risk marker for the development of NSAID-induced gastrointestinal lesions. Fifty-one healthy volunteers, enrolled in a prospective, double-blind study carried out to evaluate gastrointestinal side effects of meloxicam and piroxicam, were analyzed to determine whether: (1) the prevalence of H. pylori correlates with the occurrence and severity of NSAID-induced gastrointestinal lesions, and (2) serum pepsinogen A and C levels could be used as markers of NSAID-induced mucosal damage. Upper endoscopy was performed by the same investigator before and after 28 days of treatment with placebo, meloxicam (7.5 mg/day and 15 mg/day), or piroxicam (20 mg/day). NSAID-induced damage was graded separately for hemorrhages and erosion ulcers according to Lanza's scale. There were no statistically significant differences in the prevalence of H. pylori in subjects with and without NSAID-induced mucosal lesions. However, there was a positive association between H. pylori infection and the severity of mucosal damage: total mean endoscopic score was 2.9 +/- 0.3 in H. pylori-positive subjects versus 1.6 +/- 0.5 in H. pylori-negative subjects (P < 0.05). Pepsinogen A and C levels increased from 55.3 +/- 3 to 149.4 +/- 15 and from 6.3 +/- 0.5 to 11.5 +/- 2.2, respectively (P < 0.05) in subjects who developed severe endoscopic injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of NSAIDs on pepsinogen secretion and calcium mobilization in isolated chief cells

Acid and pepsin are thought to play an important role in the process of gastrointestinal side effects induced by nonsteroidal anti-inflammatory drugs (NSAIDs). Although NSAIDs increase basal gastric acid secretion, the effect they exert on pepsinogen secretion is unknown. Because pepsin plays a key role in many acid-related diseases, we investigated whether NSAIDs directly stimulate pepsinogen secretion from isolated chief cells. Exposure of guinea pig gastric chief cells to indomethacin (10 microM) did not reduce cell viability as evaluated by lactate dehydrogenase and 51Cr release and trypan blue incorporation. Indomethacin (10 microM) caused two- to threefold increases in pepsinogen secretion and intracellular calcium concentrations ([Ca2+]i). Both effects were concentration dependent. Removal of extracellular Ca2+ or pretreatment of the cells with 0.5 mM lanthanum blocked both pepsinogen secretion and the [Ca2+]i increase in chief cells stimulated with 10 microM indomethacin. Exposure of isolated chief cells to indomethacin caused a 90% inhibition of prostaglandin (PG) E2 generation, but a 12-fold increase in leukotriene (LT) B4 release. Incubating chief cells with exogenously added LTB4, LTC4, LTD4, and LTE4 provoked a concentration-dependent stimulation of pepsinogen release (mean effective concentration of 0.05-0.1 nM). Maximally effective concentrations of all LTs (10 microM) increased [Ca2+]i two- to threefold. Pretreating the cells with a 5-lipoxygenase inhibitor abolished LTB4 generation induced by Ca2+ ionophore and indomethacin and reduced indomethacin-induced pepsinogen secretion 20%. In conclusion, indomethacin induced a concentration-dependent stimulation of pepsinogen secretion and [Ca2+]i in isolated chief cells. Indomethacin inhibits PGE2 generation, but increases LTB4 release. This "lipoxygenase shunt" may contribute to the effect indomethacin exerts on isolated chief cells.

Leukotrienes stimulate pepsinogen secretion from guinea pig gastric chief cells by a nitric oxide-dependent pathway

BACKGROUND/AIMS

Leukotrienes (LTs) are involved in many inflammatory conditions including gastric damage induced by nonsteroidal anti-inflammatory drugs. Although LTs stimulate acid secretion, the effect they exert on pepsinogen secretion is unknown. The aim of this study was to investigate whether LTs stimulate pepsinogen secretion by isolated chief cells and to identify the intracellular messengers that mediate this action.

METHODS

Isolated chief cells were incubated with concentrations of LTB4, LTC4, LTD4, or LTE4 ranging from 0.1 pmol/L to 10 mumol/L, and pepsinogen release, intracellular calcium and inositol(1,4,5)-trisphosphate (IP3) concentrations were measured. Nitric oxide generation was determined by the amount of citrulline generated during incubation.

RESULTS

All four LTs caused a concentration-dependent stimulation of pepsinogen secretion with 50% effective concentration of 0.05-0.1 nmol/L and a dose-dependent increase in cytoplasmic free calcium and IP3 concentration. The LTB4 and LTD4 antagonists caused selective, concentration-dependent inhibition of LTB4- and LTD4-induced pepsinogen secretion, calcium mobilization, and IP3 generation. All four LTs increased NO generation, and the effect was inhibited by LTB4 and LTD4 antagonists and an NO synthase inhibitor NG-monomethyl-L-arginine and reversed by L-arginine. NG-monomethyl-L-arginine caused a 50%-60% reduction of LT-induced pepsinogen release. Each of the four LTs caused a fivefold increase in 5'-cyclic guanosine monophosphate.

CONCLUSIONS

LTs are powerful stimulators of pepsinogen secretion in isolated chief cells and act via occupancy of specific cell-surface receptors.

Circadian variations in gastric acid and pepsin secretion and intragastric bile acid in patients with reflux esophagitis and in healthy controls

OBJECTIVES

Duodenogastric reflux is a physiological phenomenon in both fasting and postprandial state. Because this suggests that bile acids may reflux into the esophagus together with the acid in patients with reflux esophagitis, we investigated the circadian variations of acid and pepsin secretion and intragastric bile acid concentrations in 25 patients with reflux esophagitis and in 15 healthy controls.

METHODS

Between-meal, nocturnal gastric and meal-stimulated acid and pepsin secretion and bile acid concentrations were measured by continuous gastric aspiration and intragastric titration.

RESULTS

Bile acids were found in 85 and 59% of gastric samples (p < 0.05). Intragastric bile acid concentrations were 6-8-fold higher in esophagitis patients than controls during the day. Approximately 10% of gastric samples from reflux esophagitis patients had a pH greater than 7, and all contained more than 500 mumol/L bile acids. Bile acids and pepsin were simultaneously revealed in 98% of the gastric samples from patients with reflux esophagitis with pH less than 4. Mean daily acid output (meal excluded) averaged 3.5 +/- 0.1 in healthy subjects and 2.7 +/- 0.2 mmol/30 minutes in esophagitis patients (p < 0.05); meal-induced acid secretions were similar. Total (24-h) acid secretion averaged 192.3 +/- 12.4 and 162.4 +/- 10.5 mmol/24 h (p < 0.05). There were no differences in the daily pepsin output.

CONCLUSIONS

Our data indicate that almost all "acid" gastroesophageal refluxes should be considered as "mixed" refluxes. Because bile acids are found in the stomach irrespective of whether the environment was acid or alkaline, pH-metry provides no useful information on the pattern of duodenogastric reflux into the esophagus. Variability in the composition of the gastro-esophageal refluxate may explain why the severity of esophageal lesions differs in patients with similar pattern of acid refluxes.

Role of tumor necrosis factor alpha release and leukocyte margination in indomethacin-induced gastric injury in rats

BACKGROUND/AIMS

Several studies have shown that polymorphonuclear neutrophil leukocyte (PMN) margination is an early and critical event in the pathogenesis of gastric mucosal injury caused by nonsteroidal anti-inflammatory drugs. Tumor necrosis factor (TNF) alpha is a proinflammatory cytokine that causes PMN margination by up-regulating expression of adhesion molecules on both PMN and endothelial cells. This study investigated whether substances that modulate TNF synthesis and release influence PMN margination and indomethacin-induced gastric damage.

METHODS

Rats were treated with several doses of indomethacin alone or in association with substances known to increase (interleukin 2 and lipopolysaccharide) or inhibit (pentoxifylline, dexamethasone, granulocyte colony-stimulating factor [G-CSF]) TNF synthesis and release.

RESULTS

Indomethacin administration caused dose-dependent damage and increased PMN margination and plasma TNF concentrations. Pretreatment with interleukin 2 and lipopolysaccharide significantly increased TNF release, PMN margination, and gastric mucosal damage, but administration of dexamethasone, pentoxifylline, and G-CSF provided almost total protection. The administration of G-CSF alone caused a significant increase in gastric PMN margination but protected against the indomethacin-induced gastropathy.

CONCLUSIONS

Agents that regulate TNF synthesis and release influence gastric susceptibility to indomethacin by modulating PMN margination. G-CSF increased PMN infiltration but protected against the mucosal injury, suggesting that PMN margination alone is not sufficient to induce mucosal damage.

Effect of erythromycin administration on upper gastrointestinal motility in scleroderma patients

BACKGROUND

Gastrointestinal involvement is frequent in patients with scleroderma. Erythromycin, a macrolide antibiotic, has been shown to accelerate gastric emptying in normal subjects and diabetic patients. The present study investigated the effects of acute erythromycin administration on gastric and gallbladder motility in patients with scleroderma and gastrointestinal involvement.

METHODS

Twelve scleroderma patients and 14 healthy subjects were investigated. Each subject was investigated on 4 different days. Gastric and gallbladder emptying and gastric motility were determined by sonography and manometry, and the effect of 2 mg/kg/h erythromycin in fasted patients or after semisolid meal evaluated.

RESULTS

The half-time of gastric emptying in response to semisolid meal was 121.3 +/- 14.0 min (SE) in scleroderma patients and 45.7 +/- 10.4 min in healthy subjects (P < 0.01). The peak of gallbladder emptying occurred later in scleroderma patients (95.0 +/- 5.0 min) than in healthy subjects (45.0 +/- 8.0 min) (P < 0.01). Erythromycin stimulated gastric and gallbladder motility in fasted subjects, as shown by manometry and sonography, and accelerated gastric and gallbladder emptying when administered immediately before the meal (P < 0.01).

CONCLUSIONS

Erythromycin accelerates gastric and gallbladder emptying in scleroderma patients and might be helpful in the treatment of gastrointestinal motor abnormalities in these patients.

Pentoxifylline prevents indomethacin induced acute gastric mucosal damage in rats: role of tumour necrosis factor alpha

Neutrophil adherence within the gastric microcirculation is thought to be a major step in the pathogenesis of gastric mucosal damage induced by indomethacin. Pentoxifylline, a methylxanthine derivative, prevents leukocyte adherence to vascular endothelium and protects organs from shock by reducing tumour necrosis factor alpha (TNF alpha) concentrations. Rats were treated with 20 mg/kg oral indomethacin, pretreated with vehicle or with four different doses of pentoxifylline intraperitoneally, and killed after three hours. The gross gastric mucosal injury, neutrophil margination into the gastric microcirculation, mucosal concentrations of 6-keto-prostaglandin F1 alpha (PGF1 alpha), and PGE2 and serum TNF alpha values were measured. Whether the pentoxifylline induced protection involved nitric oxide mediated pathways or gastric acid secretion was evaluated. The data indicate that pentoxifylline reduces indomethacin induced mucosal damage and neutrophil margination in a dose dependent manner without exerting any effect on gastric mucosal prostaglandin concentrations. The maximally effective dose (200 mg/kg) of pentoxifylline reduced gastric damage by 90% and slightly stimulated acid secretion. The effect of pentoxifylline was not affected by pretreatment with the nitric oxide inhibitor. Pentoxifylline prevented the indomethacin induced increase in TNF alpha concentrations in a dose dependent fashion. Serum TNF alpha values were 30.5 (7.0) IU/ml (mean (SEM)) in rats treated with indomethacin alone and 5.0 (2.5) IU/ml (p < 0.01) in rats treated with indomethacin plus 200 mg/kg pentoxifylline. Pentoxifylline, therefore, prevents the acute gastric mucosal damage and neutrophil margination induced by indomethacin and reduces indomethacin induced release of TNF alpha.

5-hydroxytryptamine 3-receptor antagonist modulates gallbladder emptying and motilin release induced by erythromycin

In the present study we evaluated the effect of ondansetron (formerly indicated as GR38032F), a potent and selective type-3 5-hydroxytryptamine receptor antagonist, on erythromycin-induced gallbladder emptying and motilin release, as well as gallbladder emptying induced by a regular meal in healthy volunteers. Gallbladder emptying was evaluated by sonography. Ondansetron, at the dose of 0.05 mg/kg, significantly reduced (P < 0.001 by ANOVA) the gallbladder emptying induced by 2 mg/kg/hr erythromycin, but did not increase basal gallbladder volume or inhibit gallbladder emptying induced by a regular meal. Ondansetron also inhibited the motilin release induced by erythromycin (P < 0.001, by ANOVA). These results suggest that serotoninergic mechanisms modulate the effects of erythromycin on the gastrointestinal tract. The exact site of action of ondansetron remains to be identified.

Placebo-controlled comparison of piroxicam-beta-cyclodextrin, piroxicam, and indomethacin on gastric potential difference and mucosal injury in humans

The acute gastroduodenal mucosa injury and gastric potential difference (GPD) drops provoked by 14-day administration of 20 mg/day of a new piroxicam formulation (piroxicam-beta-cyclodextrin), 20 mg/day standard piroxicam and 100 mg/day indomethacin were evaluated and compared in a randomized, double-blind, placebo-controlled study carried out on 64 volunteers. Endoscopic examinations, performed after 14-day treatment, demonstrated that piroxicam-beta-cyclodextrin was less gastrolesive (mean endoscopic score +/- SE = 0.56 +/- 0.2) than either piroxicam (2.06 +/- 0.5) or indomethacin (2.25 +/- 0.5) (p < 0.01). The drop in GPD after a single dose of the assigned drug was considerably greater for piroxicam and indomethacin than for piroxicam-beta-cyclodextrin (p < 0.01), which registered similar values to placebo. Since GPD is an expression of the anatomo-functional integrity of the gastric barrier, the results indicate that piroxicam-beta-cyclodextrin exerts less direct acute damage on the gastric mucosa. Therefore, when administered short-term, piroxicam-beta-cyclodextrin appears to be less gastrolesive than either indomethacin or the standard piroxicam formulation.

Gastric acidity and gastroesophageal reflux patterns in patients with esophagitis

Esophageal pH-metry is the test of choice for diagnosing gastroesophageal reflux. However, although it allows acid refluxes to be distinguished, it is of limited value for identifying alkaline or mixed (acid mixed with alkaline material) refluxes. To evaluate the ability of dual pH-metry to identify alkaline or mixed refluxes, the gastric acidity and gastroesophageal reflux pattern were evaluated simultaneously in 64 patients with mild-moderate esophagitis, in 28 patients with severe or complicated esophagitis, and in 20 healthy subjects. A dual esophageal gastric pH-probe allowed three different types of esophageal reflux to be distinguished: (a) acid refluxes, defined as a drop in esophageal pH to values less than 4 together with a gastric pH less than 4; (b) mixed refluxes, defined as a drop in esophageal pH from baseline to values greater than 4 associated with rises in gastric pH to greater than 4 values; (c) alkaline refluxes, defined as a rise in esophageal pH to greater than 7 associated with a simultaneous increase in gastric pH to greater than 4. Gastric acidity was more significantly reduced in patients with severe or complicated esophagitis than it was in healthy subjects (P less than 0.01). The reflux pattern in both mild-moderate and severe esophagitis was characterized by mainly acid refluxes and a marked increase in the time the esophagus mucosa was exposed to acid (P less than 0.001). Pure alkaline refluxes were rare (less than 1%) in both healthy subjects and esophagitis patients. The number of mixed refluxes was considerably higher in severe esophagitis patients than it was in either mild-moderate esophagitis patients or controls (P less than 0.05). The finding of mixed refluxes in severe or complicated esophagitis suggests that biliary acids and/or pancreatic enzymes are involved in the pathogenesis of severe forms of esophagitis.

Endoscopic treatment of bile duct stones

Approximately fifteen per cent of patients who undergo gallstones also have concomitant common bile duct stones. Endoscopic papillosphincterotomy (EPS) is the treatment of choice for common bile duct stones in cholecystectomized patients as well as in patients with gallbladder in situ but at high operative risk. Endoscopic papillosphincterotomy is a highly effective technique and able to remove stones from choledochus in 85-90% of cases. The failure of EPS is mainly related to the size of stones (greater than 15 mm). However, recently introduced sophisticated techniques, such as extraluminal (extracorporeal shock wave lithotripsy) or intraluminal lithotripsy (mechanical, electro-hydraulical or laser) now allow to fragment and remove also "large" stones. Should EPS fail to remove stones, a naso-biliary tube can be endoscopically positioned and attempts made to dissolve the stone by infusing chemical solvents. However, until now the chemical dissolution has only a marginal efficacy in the treatment of common bile duct stones. If all these techniques fail, good operative risk patients can be treated by surgical choledochotomy, while high operative risk patients can be treated by permanent biliary endoprosthesis or percutaneous techniques.