Marek Marcinkiewicz

Declined human esophageal mucin secretion in patients with severe reflux esophagitis

It has been recently demonstrated that human esophageal submucosal mucous glands exhibit the ability to secrete copious amounts of mucin, well known within the gastrointestinal tract for its protective quality against hydrogen ion and pepsin. Since mucin may also play a protective role within the esophageal compartment, we have studied the rate of secretion of esophageal mucin in patients with RE. Mucin was assessed by periodic acid-Schiff methodology in esophageal secretion collected during continuous perfusion with saline (period I) followed by HCl (period II), HCl/pepsin (period III), and final saline (period IV), mimicking the natural gastroesophageal scenario. The basal rate of the luminal release of mucin in patients with grade II RE was 18% lower as compared with controls. During exposure of the esophageal mucosa to an HCl/pepsin solution, esophageal mucin output in the RE group was 52% lower than in the control group (0.154 ± 0.027 vs 0.320 ± 0.049 mg/cm2/min;P=0.025). Furthermore, the rates of esophageal mucin output in patients with grade III RE during esophageal perfusion with saline and HCl/pepsin were 62% (0.090 ± 0.021 vs 0.239 ± 0.036 mg/cm2/min;P=0.016) and 86% (0.048 ± 0.010 vs 0.320 ± 0.049 mg/cm2/min;P=0.001) lower when compared with corresponding values in controls. After endoscopic healing of RE, the overall impairment in the rate of esophageal mucin secretion in patients with grade II improved from 31% to 17% at the end of therapy, whereas in patients with grade III the impairment in mucin secretion improved only marginally from 71% to 69%. Significant impairment in the rate of esophageal mucin output in patients with severe esophagitis (grade III), prevailing despite healing of endoscopic changes, indicates that a low rate of esophageal mucin secretion may be a potential contributing factor in the development of severe mucosal damage in patients with excessive gastroesophageal reflux.

Esophagoprotective potential of cisapride: an additional benefit for gastroesophageal reflux disease

Cisapride is a novel prokinetic agent thatreleases acetylcholine at the level of the myentericplexus. Acetylcholine also plays a role in the secretoryfunction of salivary glands evoked by intraesophagal mechanical and chemical stimulation, mediatedthrough the esophagosalivary reflex. The impact,however, of cisapride on salivary protective componentsmediated by esophagosalivary reflex remains unknown. Therefore, we have studied salivary pH,bicarbonate, nonbicarbonate, glycoconjugate, protein,EGF, TGF-α, and PGE2 before and afterthe administration of cisapride. The study was conductedin 20 asymptomatic volunteers (9 women and 11 men, mean age 36,range 26-52). Salivary secretions were collected underbasal conditions and during masticatory, mechanical, andchemical stimulation before and after four days of cisapride administration (10 or 20 mg fourtimes a day). Cisapride administration resulted in a 45%increase in salivary volume during the basal condition(P < 0.01), a 32% increase during mastication (P < 0.05), a 53% increase during mechanical(P < 0.05), and a 51% increase during chemical (P< 0.01) stimulation. Cisapride administrationresulted also in a significant increase in salivaryprotein output (P < 0.05), salivary bicarbonate (P <0.05), and nonbicarbonate buffers (P < 0.05), andsalivary EGF (P < 0.05). Salivary glycoconjugatesignificantly increased only during mechanicalstimulation with the catheter and at the end of the esophageal perfusionprocedure (P < 0.05). Although a similar trend wasalso recorded during the analysis of salivaryPGE2, this difference did not reachstatistical significance. Salivary pH and TGF-α before and after cisaprideadministration remained unchanged. The stimulatoryimpact of cisapride on salivary volume and inorganic(bicarbonate and nonbicarbonate buffers) and organic(protein, glycoconjugate, and EGF) protective componentswould benefit patients with GERD and would also bepotential therapy for xerostomia.

Detrimental Impact of Acid and Pepsin on the Rate of Luminal Release of Transforming Growth Factor α: Its Potential Pathogenetic Role in the Development of Reflex Esophagitis

The impact of intraluminal acid and pepsin on the rate of esophageal luminal release of transforming growth factor alpha (TGF alpha), measured by RIA, in 21 asymptomatic volunteers and 26 patients with reflux esophagitis (RE) was investigated. Esophageal secretion was collected, using an esophageal perfusion catheter, during mucosal exposure to NaCl, HCl or HCl/Pepsin and final saline. The basal rate of luminal TGF alpha release in controls was steady throughout the entire four perfusion periods with saline. This rate declined by 71% during mucosal exposure to HCl (p = 0.002) and by 74% during esophageal perfusion with HCl/pepsin (p = 0.011). The basal rate of luminal TGF alpha release in patients with RE was 27% higher than the corresponding value in controls (1.076 +/- 0.140 vs. 0.850 +/- 0.180 ng/min, p = 0.050). Mucosal exposure to acid and acid/pepsin solutions in RE patients also resulted in a significant decline in the luminal release of TGF alpha by 43% (p < 0.001) and by 42% (p < 0.001) respectively. Despite this decline, TGF alpha in patients with RE was significantly higher (p < 0.001) than in controls. The decline in esophageal TGF alpha release during HCl and HCl/pepsin exposure may facilitate the development of mucosal damage. The increase in esophageal TGF alpha release in patients with RE may represent a compensatory mechanism developed by the mucosal inflammatory changes.

A neonatal mouse model of intestinal perforation : Investigating the harmful synergism between glucocorticoids and indomethacin

Background: Early postnatal steroids and indomethacin in combination have been shown to increase the risk of spontaneous intestinal perforation (SIP) in infants with extremely low birth weight (ELBW), but the mechanism behind this synergistic effect is unknown. Materials and Methods: Based on literature in a variety of models suggesting that glucocorticoids and nonsteroidal antiinflammatory agents diminish complementary isoforms of nitric oxide synthase (NOS), we hypothesized that perturbations in NO metabolism contribute to SIP. Results: Our results using newborn wild-type (WT) and endothelial NOS-knockout (eNOS KO) mice treated with dexamethasone and/or indomethacin indicate that indomethacin treatment diminishes ileal eNOS abundance; dexamethasone treatment diminishes ileal inducible NOS and neuronal NOS (nNOS); 100% of dexamethasone-treated eNOS KO mice die after 3 days; eNOS KO mice treated for 2 days with dexamethasone develop acute pyloric stenosis in association with reduced expression of pyloric nNOS; and isolated ileum from eNOS KO mice treated for 2 days with dexamethasone exhibit a significant decrease in spontaneous peristalsis, decreased circumference, and decreased capacitance for forced volume before ileal perforation compared with ileum from untreated controls. Conclusions: Our findings suggest that eNOS and nNOS display functional overlap in the newborn mouse gastrointestinal tract and that simultaneous reduction in the activity of both NOS isoforms may be a risk factor for neonatal ileal perforation. If this holds true in human infants, then it provides a plausible etiologic explanation for the strong temporal association between SIP and the simultaneous treatment of ELBW infants with glucocorticoids and indomethacin.

Impact of Helicobacter pylori colonization on immunoreactive epidermal growth factor and transforming growth factor-alpha in gastric juice. Its potential pathogenetic implications.

Epidermal growth factor (EGF), pivotal in mucosal protection, is partly degraded proteolytically at low pH in the gastric milieu; gastric acid secretion, on the other hand, remains influenced byH. pylori colonization. The aim of this study, therefore, was to evaluate the impact of low pH andH. pylori colonization status on immunoreactive EGF and the other member of EGF-family, immunoreactive transforming growth factor-α (TGF-α). Eighteen patients with nonulcer dyspepsia (NUD) colonized byH. pylori and 55 NUD patients withoutH. pylori colonization were investigated. Gastric juice samples were aspirated at the beginning of the endoscopy procedure and immediately placed on ice, and their pH was recorded. The measurement of immunoreactive EGF and TGF-α was performed using commercially available radioimmunoassays (RIAs) after adjustment of pH to neutral using an assay buffer. Statistical analysis was performed using Σ-Stat for Windows. The concentration of immunoreactive EGF in patients with NUD colonized byH. pylori was 80% lower (P < 0.02) than in those withoutH. pylori and in both groups immunoreactive EGF was significantly lower when the pH of gastric juice was below 4.0. The concentration of immunoreactive EGF inH. pylori(+) andH. pylori(−) patients was similar when the pH of aspirated gastric juice was above 4.0. However, with gastric juice pH<4.0, the EGF concentration was 64% lower inH. pylori(+) patients thanH. pylori(−) patients (P<0.05). In general, the concentration of immunoreactive TGF-α in gastric juice was unaffected byH. pylori colonization or pH of gastric juice. It is concluded that: (1) significantly lower immunoreactive EGF concentrations in patients with pH below 4.0 indicate that immunoreactive EGF but not immunoreactive TGF-α is affected by an acidic gastric milieu; (2) the further reduction of gastric juice immunoreactive EGF at pH below 4.0 in patients colonized byH. pylori suggests that this microorganism may elaborate factors that accelerate its proteolytic degradation or inhibit its rate of synthesis and/or secretion; and (3) this diminished content of immunoreactive EGF at low pH, especially in patients colonized byH. pylori, may facilitate the development and/or progression of mucosal damage.

Adenosine deaminase activity in the gastric mucosa in patients with gastric ulcer. Effects of ranitidine and sucralfate

Adenosine deaminase activity was studied in the gastric mucosa of patients with peptic ulcer in relation to ulcer localisation and treatment with ranitidine or sucralfate. Enzyme activities observed in the corpus mucosa were higher at a distance of over 2 cm from the ulcer margin than that recorded close to the ulcer. A significant decrease in adenosine deaminase activity was found after treatment with ranitidine but not with sucralfate. In the antral mucosa, enzyme activity was constant in all the groups observed. The evaluation of adenosine deaminase activity in gastric mucosa can be useful for studies of pathologic changes in the stomach.

Mucosal adenosine deaminase activity and gastric ulcer healing

Adenosine deaminase activity was studied in gastric corpus mucosa close to an ulcer crater. It was found that 6 weeks of therapy with ranitidine was accompanied by a decrease in enzyme activity in the mucosa around healed ulcers and an increase around those which failed to heal. The different activities of adenosine deaminase in the vicinity of healed and unhealed ulcers may indicate its possible role in peptic ulcer healing.

A role for plasmin in platelet aggregation: differential regulation of IGF release from IGF-IGFBP complexes?

OBJECTIVES To determine if plasmin differentially augments platelet aggregation through variable efficiencies of IGF-IGFBP complex cleavage. METHODS We utilized ADP-triggered platelet aggregation assays to test the effects of IGF-I versus IGF-II in complex with IGFBP-2 or IGFBP-3 upon the efficiency of plasmin (a known IGFBP protease) as a pro-aggregatory stimulus. In vitro proteolysis assays were performed as controls. RESULTS We found that IGF-I complexes augmented platelet-mediated aggregation whereas IGF-II either had no effect (IGFBP-2) or inhibited platelet-mediated aggregation (IGFBP-3). In vitro proteolysis assays of IGFBP-2 and IGFBP-3 using plasmin revealed that three of the four aggregation findings were explained by the disparate efficiencies of IGFBP proteolysis associated with each IGF. Only IGF-II-IGFBP-2 complex resulted in a finding that could not be explained by the concept of differential regulation of plasmins proteolysis efficiency by the two IGF ligands. CONCLUSIONS Our findings demonstrate that the plasmin can differentially modulate platelet aggregation in response to intrinsic heterogeneities within the IGF axis.

An analysis of IGFBP evolution

OBJECTIVES To perform a synonymous, non-synonymous codon mutational analysis of the IGFBP gene family and identify mechanisms by which the IGFBP subfamilies diverged. METHODS We identified 78 intact nucleotide sequences from 6 IGFBP subfamilies and 12 different species and used them for phylogenetic and synonymous, non-synonymous codon mutational analysis. Deletion and insertion comparisons were performed across subfamilies to determine if this might play a unique role in subfamily genesis. RESULTS IGFBP-2 was identified by phylogenetic analysis to be the most related subfamily of the IGFBP progenitor, followed by IGFBP-4. Insertions and deletions within the variable domains were associated with divergence of each subfamily from its progenitor, suggesting a common motif for IGFBP evolution. Insertions unique to mammals were also found within the amino terminus of IGFBP-2. CONCLUSION IGFBP subfamily divergence is associated with variable domain insertion or deletion and vigorous non-synonymous codon mutation. Our findings suggest strong selective pressure for IGFBP divergence in terrestrial vertebrates.

A distinct salivary secretory response mediated by the esophago-salivary reflex in patients with Barrett's esophagus: Its potential pathogenetic implications

PURPOSE A significantly compromised epidermal growth factor (EGF) secretion by basal parotid saliva may contribute to the development of Barretts esophagus (BE). The rate of secretion of EGF as well as a wide spectrum of protective factors in total basal and stimulated saliva in BE patients remains to be explored. We therefore studied the rate of secretion of salivary buffers, glycoconjugate, protein, EGF, transforming growth factor α (TGFα) and prostaglandin E₂ (PGE₂), evoked by esophago-salivary reflex, in patients with BE and controls (CTRL). MATERIAL/METHODS Salivary secretion was collected during basal condition, mastication, and intraesophageal mechanical and chemical stimulations respectively, mimicking the natural gastroesophageal reflux scenario. RESULTS Salivary pH in BE was significantly lower than in controls during mechanical (p<0.001) and chemical stimulations (p<0.001). Bicarbonate and protein outputs in BE were significantly lower during mechanical (p<0.05) and chemical stimulations (p<0.01). The non-bicarbonate and glycoconjugate outputs in BE were lower during chemical stimulation (p<0.05) and during mechanical (p<0.05) and chemical stimulations (p<0.05) respectively. The rate of salivary EGF output in BE was significantly lower during mechanical stimulation (p<0.05). We observed a higher TGFα output during mastication (p<0.05) and PGE2 secretion during basal and masticatory condition (p<0.05) in BE. CONCLUSIONS Patients with BE demonstrated significantly compromised salivary pH and rate of secretion of bicarbonate, non-bicarbonate, glycoconjugate, protein and EGF. This impairment could potentially predispose to the development of accelerated esophageal mucosal injury. Potential restoration of this impairment by masticatory stimulation of salivary secretion using sugarless chewing gum justifies further clinical exploration.