PGE2 Content Research Articles

Prostaglandin E(2) and F(2 alpha) production by equine conceptuses and concentrations in conceptus fluids and uterine flushings recovered from early pregnant and dioestrous mares

A growing equine conceptus must suppress the cyclical release of PGF(2 alpha) from the endometrium to effect maternal recognition of its presence in the uterus. Paradoxically, the conceptus itself secretes PGF(2 alpha), together with other prostaglandins. In this study, the PGF(2 alpha) and PGE(2) content of, and production in vitro by, day 10-32 equine conceptuses were measured and the influence of pregnancy on the concentrations of these prostaglandins in the uterine lumen was examined. In vitro, the release of both prostaglandins per mg conceptus tissue was very high on day 10 after ovulation and lower thereafter. However, while PGF(2 alpha) production decreased further after day 18 of gestation, PGE(2) production remained high until day 32. Prostaglandin concentrations in yolk sac fluid were unaffected by gestational age and PGE(2) concentrations in this compartment were two to five times higher than PGF(2a) concentrations. PGF(2 alpha) concentrations reached high values in uterine flushings recovered from cyclic mares during days 14-16 after ovulation, the expected time of luteolysis, but were negligible in flushings recovered from pregnant mares at this time. Beyond day 18 of gestation, PGF(2 alpha) concentrations in uterine flushings were high and strikingly similar to those recorded during cyclical luteolysis. It is concluded that the equine conceptus effects maternal recognition of pregnancy primarily by inhibiting the ability of the endometrium to release PGF(2 alpha) during days 12-16 after ovulation. However, the conceptus appears to delay, rather than prevent, the development of the uterine PGF(2 alpha) release pathway and an alternative mechanism must prevent luteolysis from being triggered during days 18-32 of gestation.

A baseline survey of the distribution and origin of platinum group elements in contemporary fluvial sediments of the Kentish Stour, England

The extensive anthropogenic use of the platinum group elements (PGE: Ru, Rh, Pd, Os, Ir and Pt) is the main factor responsible for the widespread dispersion of these elements throughout the environment. Significant quantities of the PGE enter fluvial systems via road runoff, storm drains and wastewater and sewage treatment systems, and may accumulate in fluvial sediments by physical and chemical processes. A baseline survey of contemporary fluvial sediments in the Kentish Stour river, east Kent, England, has been undertaken to document the sources and distribution of anthropogenic PGE in an attempt to constrain some of the physical and chemical parameters that may influence the distribution of these elements. The geology of the catchment of the Kentish Stour is dominated by carbonate and silicate sedimentary rocks, and the river passes through urban and rural land and receives inputs of waste from sewage works. Nine sedimentary rocks, 4 motorway-runoff sediments and 22 river sediments were analysed for PGE by NiS fire assay preconcentration and ICP–MS. The highest element abundances occur in the motorway-runoff sediments (maximum total PGE content of 55 ng/g), whilst the lowest values were recorded in the sedimentary rocks, where some samples contain PGE at concentrations below the limit of detection. The total PGE content of the river sediments ranged from 0.4 to 10.8 ng/g. The distribution and variation in concentrations and ratios of the PGE in the contemporary fluvial sediments of the Kentish Stour correspond strongly with land-use changes (urban versus rural) and with points of discharge from sewage works. The absence of a pure catalytic converter signature in the river sediments, however, indicates that source signatures may be mixed in sewage works or that PGE may chemically fractionate in the fluvial environment.

Prevention by parenteral aspirin of indomethacin-induced gastric lesions in rats: mediation by salicylic acid.

Nonsteroidal antiinflammatory drugs (NSAIDs) produce gastric damage in experimental animals, irrespective of the route of administration. However, aspirin (ASA) causes damage only when it is given orally. In the present study, we examined the gastric ulcerogenic effect of subcutaneously administered ASA in rats, in comparison with various NSAIDs, and investigated the reason why ASA does not cause damage in the stomach, in relation to its metabolite salicylic acid (SA). Since the antiinflammatory action of SA is known to be mediated, partly, by endogenous adenosine (AD), we also examined the possible involvement of AD in the protective action of SA. Various NSAIDs (indomethacin, flurbiprofen, naproxen, diclrofenac, ASA, SA) were administered subcutaneously, and the gastric mucosa was examined macroscopically 4 hr later. All NSAIDs tested, except ASA and SA, caused hemorrhagic lesions in the stomach, with a marked gastric hypermotility and a decrease of mucosal PGE2 contents. These ulcerogenic and motility responses caused by NSAIDs were blocked by pretreatment with atropine or PGE2. ASA, although inhibiting PGE2 generation, caused neither hypermotility nor damage in the stomach. On the other hand, SA alone inhibited basal gastric motility without any effect on mucosal PGE2 contents, and this agent, when given together with indomethacin, prevented gastric hypermotility and lesion formation in response to indomethacin, without affecting the reduced PGE2 contents. Likewise, ASA inhibited these responses to indomethacin, yet the effects appeared later than those of SA. Following administration of ASA, the blood SA levels reached a peak within 30 min and remained elevated for 4 hr. In addition, the protective effect of SA was not significantly influenced by either the AD deaminase or the AD-receptor antagonists. These results suggest that the failure of parenteral ASA to induce gastric damage may be explained by a protective action of SA metabolized from ASA. SA has a cytoprotective action against NSAID-induced gastric lesions, and this action is not mediated by endogenous AD but may be functionally associated with inhibition of the gastric motility response.

COX and NOS isoforms involved in acid-induced duodenal bicarbonate secretion in rats.

Duodenal HCO3- secretion increases in response to luminal acid, mediated by endogenous nitric oxide (NO) as well as prostaglandins (PGs). In this study, we examined the effects of various inhibitors of cyclooxygenase (COX) or NO synthase (NOS) on the acid-induced HCO3- secretion in rats and determined the enzyme isoforms responsible for this response. A proximal duodenal loop was perfused with saline under urethane anesthesia, and the HCO3- secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Mucosal acidification was performed by exposing the loop to 10 mM HCl for 10 min. Indomethacin, SC-560 (a selective COX-1 inhibitor) and rofecoxib (a selective COX-2 inhibitor) were given intraduodenally 1 hr before exposure to 10 mM HCl, while N(G)-nitro-L-arginine methyl ester (L-NAME: a nonselective NOS inhibitor) and aminoguanidine (a relatively selective inhibitor of iNOS) were given subcutaneously 3 hr before the acidification. The mucosal acidification increased the HCO3- secretion, with a rise in mucosal PGE2 content and luminal release of NO. The HCO3- secretory and PGE2 biosynthetic responses were significantly inhibited by indomethacin and SC-560, while rofecoxib had no effect on these responses. On the other hand, L-NAME, but not aminoguanidine, attenuated NO release following the acidification, resulting in inhibition of the acid-induced HCO3- secretion in a L-arginine-sensitive manner. Neither COX-2 nor iNOS mRNAs were observed in the mucosa before and 1 hr after acidification, while the gene expression of COX-1 and nNOS was constitutively detected in the mucosa and appeared to be slightly up-regulated after the acid stimulation. These results suggest that COX-1 and cNOS play as the respective key enzyme responsible for producing PG and NO following the duodenal acidification, both of which are involved in the mechanism for the acid-induced HCO3- secretion in the duodenum.

Mechanisms involved in protection afforded by L-arginine in ibuprofen-induced gastric damage: role of nitric oxide and prostaglandins.

L-Arginine (L-arg) exhibits multiple biological properties and plays an important role in the regulation of different functions in pathological conditions. Many of these effects could be achieved on this amino acid serving as a substrate for the enzyme nitric oxide synthase (NOS). At the gastrointestinal level, recent reports revealed its protective activities involving a hyperemic response increasing the gastric blood flow. The aim of this study was to characterize the relationship between NOS activity/expression and prostaglandin changes (PGs) in rats gastric mucosa, with L-arg associated resistance to the nonsteroidal anti-inflammatory drug (NSAID) ibuprofen (IBP). The protective effect of oral L-arg (100 mg/kg body wt), administerred together with IBP (100 mg/kg body wt, per os), was evident enough 90 min after drug administration, although a significant protection persisted for more than 6 hr. Pretreatment with N(G)-nitro-L-arginine (L-NNA) (40 mg/kg body wt, intraperitoneally), a competitive inhibitor of constitutive NOS, partly altered the protection afforded by the amino acid. In contrast, no changes could be observed after inducible NOS inhibition [aminoguanidine (AG) 50 mg/Kg body wt, intraperitoneally). L-arg, plus IBP, produced a significant increase of the cyclic GMP (cGMP) response in tissue samples from rat stomach, 90 min and 6 h after drug administration. iNOS activity and mRNA expression were higher in IBP-treated rats, and no differences were observed in inducible responses in the L-arg plus IBP group. No variations in the cNOS activity and expression were found among the different groups of animals assayed. The measurement of mucosal PGE2 content confirmed that biosynthesis of the eicosanoid is maintained by L-arg for over 90 min after IBP, while a total inhibition was observed 6 hr later. The mechanisms of the L-arg protective effect on the damaged induced by IBP could be explained by the different period after drug administration. The early phase is mediated by cyclooxygenase/prostaglandins pathway (COX/PGs) although NO liberated by cNOS and the guanylate cyclase/cGMP pathway could be also relevant. The later phase implicates inhibition of the iNOS/NO response.

Prostaglandin E2 concentrations in gingival crevicular fluid: observations in untreated chronic periodontitis.

We set out to monitor gingival crevicular fluid prostaglandin E2 (GCF-PGE2) concentrations longitudinally in a cohort of subjects with chronic periodontitis, given that we had noted an unexplained trend for GCF-PGE2 concentrations to gradually increase in control groups and placebo populations in previously published clinical trials. 41 adults with moderate-severe chronic periodontitis were recruited. GCF samples were collected from 8 test sites (with 5-8 mm probing depths and attachment loss) every 30 days for 150 days, and assayed for PGE2. Clinical measurements (probing depths, attachment levels, bleeding on probing) were recorded at days 0 and 150. A gradual and statistically significant increase in GCF-PGE2 concentrations was observed over the course of the study, from 40.3 ng/ml to 83.1 ng/ml (p<0.001). When data were expressed as absolute PGE2 content, a similar statistically significant increase from baseline to day 150 was observed (p<0.001). GCF volumes did not vary significantly during the study (p>0.05). Over the same time period, no statistically significant changes in clinical parameters were recorded, with the exception of mean probing depths, which decreased slightly from 5.73 mm to 5.51 mm (p<0.05). A trend for gradually increasing GCF-PGE2 concentrations in the absence of any clinical signs of disease progression was noted in a group of patients monitored longitudinally. We suggest that this phenomenon is to be expected in longitudinal clinical trials, and propose a new model for the role of PGE2 in the pathogenesis of periodontal destruction. We feel that if GCF mediators are to be monitored in clinical studies, then both concentrations and absolute mediator content should be calculated, and a standardised sampling protocol should be employed.

Effect of carnitine on stress-induced lipid peroxidation in rat gastric mucosa

Carnitine is an essential cofactor in the mitochondrial transfer of fatty acids, but is also a scavenger of oxygen free radicals in mammalian tissues. It has been shown that cold-restraint stress (CRS) produces gastric mucosal injury due to oxygen free radicals. The aim of this study was to determine the effect of L-carnitine on lipid peroxidation induced by CRS in rat stomachs. Rats pretreated with L-carnitine (50 mg/kg per day for 10 days) were restrained in a wire cage for 4 h at 4 degrees C. At the end of the experimental period, the lesion index in gastric mucosa was determined. In blood and gastric mucosa samples, the content of mucin, prostaglandin (PG)E2, the products of lipid peroxidation, and catalase activity were measured. CRS caused a significant decrease in gastric mucin and PGE2 content, while in the gastric mucosa of rats pretreated with L-carnitine, the changes in gastric mucin and PGE2 content, as well as gastric lesion development and enhanced lipid peroxide formation due to stress, were prevented. On the other hand, catalase activity in blood increased in the CRS group, while its value in gastric mucosa was not different from that in the control rats. L-Carnitine treatment increased catalase activity in both blood and gastric mucosa in control animals. Following stress, increased catalase activity of blood was associated with decreased mucosal catalase activity in rats that received L-carnitine. L-Carnitine prevents the occurrence of mucosal lesions by strengthening the gastric mucosal barrier and by reducing the products of lipid peroxidation against noxious factors that cause elevation of lipid peroxidation, such as CRS.

Adaptive gastric cytoprotection is mediated by prostaglandin EP1 receptors: A study using rats and knockout mice

Endogenous prostaglandins (PGs) play a central role in adaptive cytoprotection induced in the stomach by mild irritants. In the present study, we used taurocholate (TC) as a mild irritant in both rats and EP-receptor knockout mice, and examined which EP receptor is responsible for the adaptive gastric cytoprotection. Gastric lesions were induced by p.o. administration of HCl/ethanol (60% ethanol in 150 mM HCl). TC (5-20 mM) or PGE2 was administered p.o. 30 min before HCl/ethanol. HCl/ethanol-induced gastric lesions were dose dependently prevented by TC, and the effect at 20 mM was equivalent to that induced by PGE2 at 0.3 mg/kg. The protective effect of TC was significantly attenuated by indomethacin as well as ONO-AE-829, the EP1 antagonist, but not by either NS-398, the selective cyclooxygenase (COX)-2 inhibitor, or chemical ablation of capsaicin-sensitive sensory neurons. Likewise, the protective action of PGE2 was also antagonized by ONO-AE-829 but not chemical deafferentation. TC significantly increased PGE2 contents in the stomach, with or without chemical deafferentation, and this effect was blocked in the presence of indomethacin but not NS-398 or ONO-AE-829. TC increased the mucosal PGE2 contents similarly in both wild-type and knockout mice lacking EP1 or EP3 receptors, yet the protective action of TC against HCl/ethanol was observed in both wild-type and EP3 receptor knockout mice, but not in mice lacking EP1 receptors. The present findings confirmed a role for endogenous PGE2 produced by COX-1 in adaptive gastric cytoprotection and suggested that this action is mediated by activation of EP1-receptors but not associated with capsaicin-sensitive afferent neurons.

Permissive role of neutrophils in pathogenesis of indomethacin-induced gastric lesions in rats

We examined the possible role of neutrophils in the pathogenesis of indomethacin-induced gastric lesions, in comparison with prostaglandin (PG) deficiency.Rats were given indomethacin (35 mg/kg, s.c.) and killed 4 hr later. Gastric motility, mucosal PGE2 levels, and myeloperoxidase (MPO) activity were measured following indomethacin. Atropine was given s.c. 30 min before administration of indomethacin, while 16, 16-dimethyl PGE2 (dmPGE2) or anti-rat neutrophil antiserum (ANS) was given i.v. 10 min or 1 hr, respectively, before indomethacin treatment.Indomethacin reduced PGE2 contents in the stomach and produced hemorrhagic lesions in the stomach, with an increase of gastric motility and MPO activity. Indomethacin-induced gastric lesions were significantly prevented by dmPGE2 as well as atropine, at any time points during a 4 hr-test period. By contrast, the pretreatment of ANS did not prevent the development of gastric lesions when examined at either 1, 2 or 3 hr following indomethacin, but significantly reduced the severity of these lesions at 4 hr after indomethacin treatment. Both dmPGE2 and atropine inhibited the increase of gastric motility and MPO activity in response to indomethacin, whereas ANS prevented the increase of MPO activity, without any effect on the gastric hypermotility.These results confirmed that indomethacin-induced gastric lesions occurred in association with gastric hypermotility, in both atropine and PG-sensitive manners, and further suggest that the neutrophil activation/migration is not sufficient by itself to induce damage in the stomach and may be implicated in the process of later extension of damage.

Both cyclooxygenase-1 and cyclooxygenase-2 mediate osteoblast response to titanium surface roughness.

Previous studies suggest that the enhanced expression of the osteoblastic phenotype exhibited by MG63 osteoblast-like cells on rough Ti surfaces (R(a) 4-5 microm) involves increased production of prostaglandin. Inhibition of prostaglandin synthesis by indomethacin blocks surface-roughness-dependent decreases in cell proliferation and increases in alkaline phosphatase activity and the production of osteocalcin and TGF-beta1. This study examined the hypothesis that the increase in expression of the osteoblastic phenotype noted in MG63 cells cultured on rough Ti surfaces is mediated by inducible cyclooxygenase-2 (Cox-2) whereas Cox-1 modulates prostaglandin production and phenotypic expression of the cells under standard conditions and on smooth Ti surfaces. MG63 cells were cultured on tissue culture plastic, smooth Ti (PT, R(a) = 0.60 microm), and two rough Ti surfaces with differing morphologies (SLA, R(a) = 3.97 microm and TPS, R(a) = 5.21 microm). At 24 h after plating, media were replaced with media containing the general Cox inhibitor indomethacin (10(-7)M), the Cox-1 inhibitor resveratrol (1 or 10 microM), or the Cox-2 inhibitor NS-398 (1 or 10 microM). Media were changed again after 48 h. Five days after plating, osteocalcin, PGE(2), and TGF-beta1 content of the conditioned media were determined. Cell numbers were assessed in the same cultures used for determination of osteocalcin production. Cell layer protein and alkaline phosphatase specific activity were assessed in cultures used to measure PGE(2) and TGF-beta1. Indomethacin, resveratrol, and NS-398 had no effect on cell number. Indomethacin blocked the surface-roughness-dependent increase in PGE(2) production by up to 80%. Similarly, resveratrol inhibited up to 50% of the PGE(2) production on smooth surfaces and up to 80% on rough surfaces. In contrast, NS-398 had no effect on PGE(2) production by cells on smooth surfaces but caused a 60% reduction in cultures on rough surfaces. Indomethacin reduced alkaline phosphatase on all surfaces below basal levels. However, neither resveratrol nor NS-398 had an effect. Indomethacin blocked the stimulatory effect of surface roughness on osteocalcin production while resveratrol only partially reduced osteocalcin production, and NS398 completely blocked the surface-dependent increase. TGF-beta1 production on rough surfaces was blocked by indomethacin. The effects of resveratrol and NS-398 were dose dependent, but neither agent caused total inhibition of the increase noted on SLA, and only resveratrol blocked the increase on TPS. These results indicate that both Cox-1 and Cox-2 are involved in the response of osteoblasts to surface roughness with respect to production of PGE(2), TGF-beta1, and osteocalcin. While prostaglandin mediates the effects of surface roughness on alkaline phosphatase, neither Cox-1 nor Cox-2 appears to be involved, at least with respect to the two inhibitors used.

Fluid-inclusion Data for Vein-type Cu-Ni-PGE Footwall Ores, Sudbury Igneous Complex and Their Use in Establishing an Exploration Model for Hydrothermal PGE-enrichment Around Mafic-Ultramafic Intrusions

Cu-Ni-PGE footwall ore deposits were studied in the McCreedy East and Whistle mines along the North Range, and the Lindsley and Little Stobie mines along the South Range of the Sudbury Igneous Complex. The footwall ores in these localities differ from typical magmatic Fe-Ni-Cu-PGE deposits in the Sudbury mining camp: they have higher Cu/Ni ratios, higher PGE content, vein-like appearance and ubiquitous association of ore with hydrous silicates. Results of comparative fluid inclusion petrography and microthermometry of footwall ores indicate that high temperatures (300°C to 480°C) and heavy-metal rich saline (up to about 40 NaCl equivalent wt% salinity) fluids were associated with the formation of the PGE-rich footwall ores at moderately high pressures (around 2 kbars). However, several, possibly independent fluid circulation stages were also found at the different localities and there also are differences in detailed characteristics for ore-forming fluids especially comparing data from the North Range and the South Range. Thus, in addition to the high temperature and salinity of fluids, there are local variations in the nature of hydrothermal processes. These differences may be related to the diverse origin of fluids (magmatic, metamorphic, and formational brines) and their differing extents of interaction with the compositionally different footwall lithologies.

MODIFIED RESPONSES TO PGE2 IN POLYAMINE BIOSYNTHESIS BY T LYMPHOCYTES OF GASTRIC- AND CONJUNCTIVA BASAL CELL-CARCINOMA PATIENTS

The response to Prostaglandin (PG) E2 of T cells from gastric carcinoma (GC)- and conjunctiva-basal cell carcinoma (conjunctiva-BCC)-bearing patients has been studied in relation to polyamine metabolism. Polyamines are crucial cofactors in cell growth as well as differentiation and many works report that lymphocyte spermine (SP), spermidine (SPD) and putrescine (PUT) levels may be related to tumor proliferation. The present work aims to detect the basal and PGE2 induced concentrations of these polyamines and cAMP, ornithine decarboxylase (ODC), spermine N1-acetyltransferase (SAT) activities of T lymphocytes drawn from patients suffering from GC and conjunctiva-BCC since many carcinomas are characterized by high levels of PGE2. Data obtained from lymphocytes of neoplastic subjects were compared with those derived from PGE2-treated control lymphocytes. Results highlight a very significant increase of all the polyamine metabolites in PGE2-treated T cells from neoplastic patients in respect to the untreated and PGE2-treated control lymphocytes. Therefore, it is conceivable that the PGE2 content increase, often occurring during the epithelial tumour development, may contribute, through enhancement of polyamine metabolism, to tumor progression.

Role of endogenous nitric oxide and prostaglandin in duodenal bicarbonate response induced by mucosal acidification in rats.

Duodenal HCO3- secretion increases in response to mucosal acidification by luminal acid. Although this process is known to be mediated by endogenous prostaglandins (PGs), the role of nitric oxide (NO) in this response has been little studied. We examined the effects of indomethacin and N(G)-nitro-L-arginine methyl ester (L-NAME) on the acid-induced HCO3- secretion in the rat duodenum, together with those on PGE2 generation as well as luminal release of NO metabolites (NOx). A proximal duodenal loop was perfused with saline, and the HCO3- secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Mucosal acidification was performed by exposing the loop to 10 or 100 mM HCl for 10 min. Acidification of the duodenal mucosa stimulated the HCO3- secretion, with concomitant increase of mucosal PGE2 contents and luminal release of NOx, the response being much greater in case of 100 mM HCl. Indomethacin significantly inhibited the acid-induced HCO3- secretion as well as the PGE2 biosynthetic response, without influence on the NOx release. Pretreatment of the animals with L-NAME attenuated both the increase of mucosal PGE2 contents and luminal release of NOx following the acidification, resulting in a marked inhibition of the acid-induced HCO3- response, and these effects were significantly antagonized by coadministration of L-arginine. Duodenal HCO3- secretion was also increased by mucosal exposure to NOR-3 (a NO donor), with concomitant increase of PGE2 generation, but these effects were mitigated in the presence of indomethacin. In addition, the duodenal damage caused by mucosal perfusion with 100 mM HCl for 4 hr was markedly aggravated by pretreatment with L-NAME as well as indomethacin. These results suggest that both endogenous NO and PGs are involved in the mechanism for the acid-induced duodenal HCO3- secretion, and that NO may increase the HCO3- secretion by stimulating PG generation.

The potential role of the esophageal pre-epithelial barrier components in the maintenance of integrity of the esophageal mucosa in patients with endoscopically negative gastroesophageal reflux disease

OBJECTIVE: Patients with gastroesophageal reflux disease (GERD) accompanied by erosive reflux esophagitis (RE) exhibit an impairment within the esophageal pre-epithelial barrier protective components that may facilitate the development and/or progression of the mucosal injury. Little is known, however, whether such impairment is a general phenomenon affecting all patients with GERD or whether this is a characteristic feature only of patients with erosive RE. We therefore studied the rate of secretion of esophageal inorganic and organic protective factors in patients with endoscopically negative [E (−)] GERD and compared these results with the corresponding values in asymptomatic volunteers (CTRL). METHODS: The study was conducted on 33 white asymptomatic volunteers and 10 white patients with a long history of GERD confirmed by 24-h pH monitoring and a grossly negative upper endoscopy. Esophageal secretion was collected during mucosal exposure to NaCl, HCl, HC/pepsin and NaCl using the esophageal perfusion catheter. In collected samples all investigated parameters were measured. RESULTS: The pH of esophageal secretion and its content of bicarbonate, EGF, and PGE 2 in patients with E (−) GERD and asymptomatic volunteers were similar. Unexpectedly, the rate of esophageal glycoconjugate (predominantly mucin) secretion was significantly higher in patients with E (−) GERD than in controls during perfusion with HCl ( p < 0.05). Furthermore, secretion of protein in patients with E (−) GERD was significantly higher than in the control group during the mucosal exposure to HCl/Pepsin ( p < 0.05). The nonbicarbonate buffer secretion during perfusion with HCl and HCl/Pepsin as well as the rate of esophageal TGFα output during infusion of final saline in patients with E (−) GERD were significantly lower than in CTRL group ( p < 0.05). CONCLUSIONS: Our data indicate that patients with E (−) GERD have an esophageal secretory potential, in terms of glycoconjugate and protein, higher than that in asymptomatic controls. This phenomenon in patients with E (−) GERD may, by enhancing the quantity of the esophageal pre-epithelial barrier, help to prevent the development of erosive esophagitis. A significantly lower esophageal secretory response in patients with E (−) GERD in terms of nonbicarbonate buffers and TGFα may facilitate the development of GERD symptoms and histological changes of GERD, respectively.

The potential role of the esophageal pre-epithelial barrier components in the maintenance of integrity of the esophageal mucosa in patients with endoscopically negative gastroesophageal reflux disease.

Patients with gastroesophageal reflux disease (GERD) accompanied by erosive reflux esophagitis (RE) exhibit an impairment within the esophageal pre-epithelial barrier protective components that may facilitate the development and/or progression of the mucosal injury. Little is known, however, whether such impairment is a general phenomenon affecting all patients with GERD or whether this is a characteristic feature only of patients with erosive RE. We therefore studied the rate of secretion of esophageal inorganic and organic protective factors in patients with endoscopically negative [E (-)] GERD and compared these results with the corresponding values in asymptomatic volunteers (CTRL). The study was conducted on 33 white asymptomatic volunteers and 10 white patients with a long history of GERD confirmed by 24-h pH monitoring and a grossly negative upper endoscopy. Esophageal secretion was collected during mucosal exposure to NaCl, HCl, HC/pepsin and NaCl using the esophageal perfusion catheter. In collected samples all investigated parameters were measured. The pH of esophageal secretion and its content of bicarbonate, EGF, and PGE2 in patients with E (-) GERD and asymptomatic volunteers were similar. Unexpectedly, the rate of esophageal glycoconjugate (predominantly mucin) secretion was significantly higher in patients with E (-) GERD than in controls during perfusion with HCl (p < 0.05). Furthermore, secretion of protein in patients with E (-) GERD was significantly higher than in the control group during the mucosal exposure to HCl/Pepsin (p < 0.05). The nonbicarbonate buffer secretion during perfusion with HCl and HCl/Pepsin as well as the rate of esophageal TGFalpha output during infusion of final saline in patients with E (-) GERD were significantly lower than in CTRL group (p < 0.05). Our data indicate that patients with E (-) GERD have an esophageal secretory potential, in terms of glycoconjugate and protein, higher than that in asymptomatic controls. This phenomenon in patients with E (-) GERD may, by enhancing the quantity of the esophageal pre-epithelial barrier, help to prevent the development of erosive esophagitis. A significantly lower esophageal secretory response in patients with E (-) GERD in terms of nonbicarbonate buffers and TGFalpha may facilitate the development of GERD symptoms and histological changes of GERD, respectively.

Control of salivary secretion by nitric oxide and its role in neuroimmunomodulation.

In many in vivo systems exposure to endotoxins (LPS) leads to the co-induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), which is important to the regulation of the function of different systems during infection. In submandibular glands (SMG) neural (n)NOS is localized in neural terminals and in striated, granular convoluted and excretory ducts, endothelial (e)NOS in vascular endothelium and ducts, and iNOS in macrophages and in tubules and ducts. In normal adult male rats, injection of an inhibitor of NOS decreased the stimulated salivary secretion and a donor of NO potentiated it, indicating that NO exerts a stimulatory role. A single high dose of LPS (5 mg/kg, i.p.) induced an increase in NOS activity measured by the 14C-citrulline method, increased PGE content almost 100% as measured by RIA, and blocked stimulated salivary secretion. The administration of a specific iNOS inhibitor, aminoguanidine (AG), with LPS not only decreased NOS activity but significantly decreased PGE content, indicating that NO triggered the activation of COX-2. LPS increased conversion of labeled arachidonate to prostaglandins (PGs) showing that COX was induced. Since a PGE1 analogue blocked stimulated salivation, the LPS-induced inhibition of salivation is probably due to release of PGs. Therefore, the use of inhibitors of iNOS and COX-2 could be very useful to increase salivation during infection since saliva has antimicrobial actions.

Diminished PGE2 content, enhanced PGE2 release and defects in 3H-PGE2 transport in embryos from overtly diabetic rats.

Diminished PGE2 levels in diabetic embryos are related to the development of malformations, and thus the aim of the present study was to determine whether PGE2 levels are modified in rat embryos cultured in diabetic serum during organogenesis, and if PGE2 content and release, and 3H-PGE2 uptake and release, are altered in incubated diabetic embryos. Rats were made diabetic by steptozotocin (60 mg kg(-1)) before mating. Control rat embryos cultured for 24 h (explantation Day 9) in the presence of diabetic serum showed diminished PGE2 levels. When Day 10 diabetic embryos were incubated, embryo PGE2 levels were lower, but the PGE2 released to the incubation media was much higher than in controls. Uptake of 3H-PGE2 by diabetic embryos was initially enhanced (5-10 min), then reached similar levels to controls (20-100 min). Release of 3H-PGE2 previously incorporated during a 60-min incubation was greater in diabetic embryos than in controls. These results show diminished PGE2 content in both diabetic and normal embryos cultured in the presence of diabetic serum, but suggest that diabetic embryos have the capability to produce and release high levels of PGE2. The enhanced release of PGE2 is probably the result of transport abnormalities, and leads to the elevated PGE2 concentrations found in the incubating medium and to the diminished intraembryonic PGE2 levels that alter embryonic development.

Relationship between selective COX-2 inhibition and tissue selectivity of prostaglandin biosynthesis inhibition of zaltoprofen

The tissue selectivity of zaltoprofen (ZP) and other non-steroidal anti-inflammatory drugs (NSAIDs), against prostaglandin (PG) biosynthesis on inflammatory site and stomach was investigated from the viewpoint of eyclooxygenase (COX) enzyme, anti-carrageenin-induced edema and ulcerogenic activity. All the drugs tested inhibited COX-1 and COX-2 activities using the refined enzymes in the concentration-dependent manner. The selectivity ratio of CO-1/CG-2 inhibition was the order that ZP (6.56) >etodolac (EL, 3.93) >diclofenac sodium (DF, 1.96) >loxoprofen (SRS-trans-alcohol form) (1.90) >indomethacin (IM, 0.16) . Selectivity for COX-2 of ZP was superior to those of other NSAIDs. The inhibitory effects of ZP, loxoprofen sodium (LP), EL and IM on the PGE2 content in the carrageenin-air pouch and the PGE2 release from the gastric ucosa of the same rat were determined. At the doses of NSAIDs which inhibited the PGE2 biosynthesis at the same degree in the carrageenin-air pouch, ZP hardly inhibited the PGE2 release from the gastric mucosa. EL and LP inhibited the PGE2 biosynthesis at the same degree between inflammatory site and gastric mucosa. On the other hand, IM markedly inhibited the PGE2 release. All NSAIDs tested inhibited the carrageenin-induced edema in the dose-dependent manner, ED50 values of ZP, EL, LP, DF and IM were 2.4, 13.8, 1.9, 6.4 and 3.7 mg/kg, p.o., respectively. On the other hand, ulcerogenic activity (UD50 value) of ZP, EL, LP, DF and INI were 45.3, 12.5, 5.9, 4.1 and 3.3 mg/kg, p.o., respectively. The good correlation between UD50 values and the inhibitory activity of the PG release from the gastric mucosa of NSAIDs was noted.From these results, it was found that the inhibitory activity of NSAIDs on the PGE2 release in the stomach correlated well with the selectivity ratio of COX-1/COX-2 inhibition using enzymes and ulcerogenic activity. So, it was suggested that the selectivities for COX-2 of NSAIDs are associated with anti-inflammatory effects and ulcerogenic activity. Also, it was found that ZP has more selectivity for COX-2 and the PG biosynthesis in the inflammatory site compared with other NSAIDs, which were used in the present study. These properties of ZP were seemed to be contributed to the lower ulcerogenic activity on clinical uses.

Differential regulation of metalloproteinase production, proliferation and chemotaxis of human lung fibroblasts by PDGF, interleukin-1beta and TNF-alpha.

Fibroblast migration, proliferation, extracellular matrix protein synthesis and degradation, all of which play important roles in inflammation, are themselves induced by various growth factors and cytokines. Less is known about the interaction of these substances on lung fibroblast function in pulmonary fibrosis. The goal of this study was to investigate the effects of PDGF alone and in combination with IL-1beta and TNF-alpha on the production of human lung fibroblast matrix metalloproteinases, proliferation, and the chemotactic response. The assay for MMPs activity against FITC labeled type I and IV collagen was based on the specificity of the enzyme cleavage of collagen. Caseinolytis and gelatinolytic activities of secreted proteinases were analyzed by zymography. Fibronectin in conditioned media was measured using human lung fibronectin enzyme immunoassay. Cell proliferation was measured by 3H-Thymidine incorporation assay. Cell culture supernatants were tested for PGE2 content by ELISA. Chemotactic activity was measured using the modified Boyden chamber. Matrix metalloproteinase assay indicated that IL-1beta, TNF-alpha and PDGF induced intestitial collagenase (MMP-1) production. MMP assay also indicated that IL-1beta and TNF-alpha had inhibitory effects on MMP-2,9(gelatinaseA,B) production. Casein zymography confirmed that IL-1beta stimulated stromlysin (matrix metalloproteinase 3; MMP-3) and gelatin zymography demonstrated that TNF-alpha induced MMP-9 production in human lung fibroblast, whereas PDGF alone did not. PDGF in combination with IL-1beta and TNF-alpha induced MMP-3 and MMP-9 activity, as demonstrated by zymography. PDGF stimulated lung fibroblast proliferation in a concentration-dependent manner, whereas IL-1beta and TNF-alpha alone had no effect. In contrast, the proliferation of human lung fibroblasts by PDGF was inhibited in the presence of IL-1beta and TNF-alpha, and this inhibition was not a consequence of any elevation of PGE2. PDGF stimulated fibroblast chemotaxis in a concentration-dependent manner, and this stimulation was augmented by combining PDGF with IL-1beta and TNF-alpha. These findings suggested that PDGF differentially regulated MMPs production in combination with cytokines, and further that MMP assay and zymography had differential sensitivity for detecting MMPs. The presence of cytokines with PDGF appears to modulate the proliferation and chemotaxis of human lung fibroblasts.

Palm vitamin E and the healing of ethanol-induced gastric lesions

The main focus of the study was to examine the effect of palm vitamin E (a tocotrienol-enriched fraction of palm oil) on the healing of ethanol-induced gastric mucosal lesions. The study was divided into three sections.Study 1 determined the gastric content of vitamin E after dietary supplementation with palm vitamin E for 3 weeks. Seven rats were fed a normal diet and another 7 were fed a palm vitamin E-enriched diet (150 mg/kg food). The gastric content of vitamin E levels were higher in rats fed with a palm vitamin E-enriched diet (p<0.01). Study 2 determined the time-dependent effects of palm vitamin E on gastric lesions and gastric acidity postethanol administration. Two groups of rats were fed either a normal rat diet or a palm vitamin E-enriched diet (150 mg/kg food). After 3 weeks, the control and a treated group received a single intragastric dose of 100% ethanol. Assessment of gastric lesions after 1 week showed a lower gastric lesion index in the palm vitamin E group compared with the controls (p<0.05) but there was no difference in the gastric acid content after 1 week between the two groups. Study 3 determined the effects of palm vitamin E on the gastric tissue content of malondialdehyde (MDA), PGE2 and gastric acidity without ethanol administration. The MDA content was lower in the palm vitamin E-treated group (p<0.05). However, the gastric acid and PGE2 content in both groups did not differ. The findings suggest that feeding with a palm vitamin E-enriched diet (150 mg/kg food) for 3 weeks resulted in a significant concentration of vitamin E in the gastric tissue. It was concluded that palm vitamin E may promote the healing of ethanol-induced gastric lesions through minimizing the lipid preoccupation process in the gastric mucous.