Gene therapy for ulcerations of the gastrointestinal tract

Ulcer healing requires cell proliferation, migration (re-epithelialization) and angiogenesis - all ultimately leading to scar formation. All these processes are controlled by growth factors. Gene therapy has shown only limited promise for effective treatment of congenital diseases. This is due to time-limited gene expression, adverse immune responses and/or complications related to viral vectors. However, short- term expression of genes encoding angiogenic growth factors appears to be ideal for treatment of chronic ulcers and wounds, which require only limited temporal gene overexpression. Since angiogenesis is essential for wound and ulcer healing, the genes encoding proangiogenic growth factors have been utilized for treatment of experimental esophageal, gastric and duodenal ulcers. These studies demonstrated that a single local injection of plasmids expressing vascular endothelial growth factor and angiopoietin-1 dramatically accelerates the healing of duodenal, gastric and esophageal gastric ulcers. Preliminary data indicate that such treatment can also be effective for the healing of experimental colitis.

Gastric cytoprotection beyond prostaglandins: cellular and molecular mechanisms of gastroprotective and ulcer healing actions of antacids

This article updates current views on gastric mucosal defense, injury, protection and ulcer healing with a focus on mucosal protective and ulcer healing actions of antacids. The gastric mucosa is continuously exposed to a variety of noxious factors, both endogenous such as: 0.1N hydrochloric acid, pepsin, bile acids, lysolecithin, H. pylori toxins and exogenous such as NSAIDs, ethanol and others. Gastric mucosal integrity is maintained by pre-epithelial, epithelial and post-epithelial defense mechanisms permitting the mucosa to withstand exposure to the above damaging factors. When mucosal defense is weakened or overwhelmed by injurious factors, injury develops in the form of erosions or ulcers. In the late 1970s Andre Robert and coworkers discovered that microgram amounts of a prostaglandin E2 analog protects the gastric mucosa against a variety of ulcerogenic and necrotizing agents - even such strong inducers of injury as 100% ethanol and boiling water. They proposed a new concept of cytoprotection. Subsequently, other compounds, such as sulfhydryls, sucralfate and epidermal growth factor were shown to exert protective action on gastric mucosa. Additionally, some antacids have been shown to exert a potent mucosal protective action against a variety of injurious factors and accelerate healing of erosions and gastric ulcers. These actions of antacids, especially hydrotalcite - the newest and the most extensively studied antacid - are due to activation of prostaglandin synthesis; binding to and inactivation of pepsin, bile acids and H. pylori toxins; induction of heat shock proteins; and, activation of genes encoding growth factors and their receptors.

Effect of calcitonin on the formation, composition, and enzymatic activity of the hepatic bile in guinea pgs

Porcine calcitonin given to guinea pigs in doses causing hypocalcaemia and hypophosphataemia decreased the bilirubin concentration and increased the activity of gamma glutamyl transpeptidase (GGTP) in the hepatic bile. Calcitonin had no effect on bile flow, its pH, electrolyte composition including calcium, or on the concentration of protein, glucose, cholesterol, nonprotein nitrogen (NPN), and bile acids. It also did not affect the activities of alanine aminotransferase (AIAT) and alkaline phosphatase (AP) in the hepatic bile. Calcitonin increased the calcium content in the liver.

Editor-in-Chief articles of choice and comments from January to June 2024

As the Editor-in-Chief of the World Journal of Gastroenterology , I carefully review all articles every week before a new issue’s online publication, including the title, clinical and research importance, originality, novelty, and ratings by the peer reviewers. Based on this review, I select the papers of choice and suggest pertinent changes (e.g. , in the title or text) to the company editors responsible for publication. This process, while time-consuming, is essential for assuring the quality of publications and highlighting important articles that readers may revisit.

Editor-in-Chief articles of choice and comments at the year-end of 2023

As the Editor-in-Chief of World Journal of Gastroenterology, every week prior to a new issue's online publication, I perform a careful review of all encompassed articles, including the title, clinical and/or research importance, originality, novelty, and ratings by the peer reviewers. Based on this review, I select the papers of choice and suggest pertinent changes (e.g., in the title) to the Company Editors responsible for publication. This process, while time-consuming, is very important for assuring the quality of publications and highlighting important articles that Readers may revisit.

To our readers: Important questions from the editors/editorial board

This letter proposes updating the World Journal of Gastroenterology (WJG ) with several new items and subsections and seeks the readers’ input for these suggested changes. In order to further enhance the scope of the WJG , to make it more interactive, and to accommodate our readers’ interest, the editors ask the readers for their input regarding potential new proposed changes and new subsections listed below: (1) new subsection - selected highlights from other related Baishideng Publishing Group world series journals; (2) new subsection - challenging images of the week - a quiz with an answer and references on another page; (3) to re-introduce or restore for some issues the cover page on which selected illustration; (4) new subsection - new hypotheses, new concepts and revisiting old concepts in a short, commentary format; (5) preview of the forthcoming issue articles (title and authors); (6) suggestions submitted by the readers - new topics and initiatives; and (7) additional topic area - molecular basis of gastric/liver diseases as an additional area for articles submitted to the journal.

Protection of the gastric mucosa by linoleic acid--a nutrient essential fatty acid

We studied whether linoleic acid, a precursor for arachidonic acid and prostaglandins, could protect the gastric mucosa against ethanol-induced injury. Fasted male rats received intragastric pretreatment with 1 ml of one of: a) solubilizer; b) solubilized linoleic acid (74 mg); or c) solubilized oleic acid (74 mg) (a nonessential fatty acid). One hour later, 2 ml 100% ethanol was given intragastrically. Three hours after ethanol administration, the gastric mucosa was assessed for gross necrosis and for histologic changes. Three hours after ethanol administration in solubilizer, pretreated-group gross mucosal necrosis involved 35 +/- 3% of total mucosal area, while deep histologic necrosis involved 52 +/- 4% of the mucosal strip length. Pretreatment with linoleic acid (but not oleic acid) significantly reduced gross histologic necrosis, to 2.3 +/- 0.5%, and deep histologic necrosis to 4 +/- 2% (both p less than 0.001 versus solubilizer group). The protective action of linoleic acid was significantly reduced (greater than 10-fold) by pretreatment with indomethacin (prostaglandins synthetase inhibitor), suggesting prostaglandins as mediators of protection. The present study showed that effective protection of the gastric mucosa against ethanol injury can be achieved by intragastric administration of linoleic acid, a dietary essential fatty acid.

Rebamipide treatment activates epidermal growth factor and its receptor expression in normal and ulcerated gastric mucosa in rats: one mechanism for its ulcer healing action?

Rebamipide (Mucosta) is a novel mucosal protective and ulcer-healing drug. Clinical and experimental data indicate that it accelerates ulcer healing and improves the quality of the scar. Since epidermal growth factor (EGF) and its receptor (EGF-R) play important roles in mucosal protection and ulcer healing, we studied whether rebamipide treatment affects expression of EGF and EGF-R in normal and ulcerated gastric mucosa in rats. Forty-eight male rats without or with gastric ulcers (induced by acetic acid) received intragastrically either placebo or rebamipide, 40 mg twice daily, for 14 days. Ulcer size was measured under a dissecting microscope; mucosal sections were stained with H&E or immunostained with specific antibodies against EGF and EGF-R. The distribution and intensity of fluorescence signal was quantified using a video image system. Rebamipide significantly accelerated ulcer healing, produced a significant increase in EGF and EGF-R expression in normal gastric mucosa (both P < 0.001), and increased expression of EGF and EGF-R in regenerating glands of the ulcer scar. Since EGF and its receptor are crucial for epithelial cell proliferation, re-epithelialization, and gland reconstruction, the above actions of rebamipide may provide a new mechanism for its ulcer healing action.

Arachidonic acid protection of gastric mucosa against alcohol injury: sequential analysis of morphologic and functional changes

We have shown previously that arachidonic acid (AA) prevents gastric mucosal injury by ethanol (ETOH). The present study was designed to determine the sequence of morphological and functional changes in the gastric mucosa during ETOH-induced injury and AA-promoted protection. Fasted male rats received intragastrically 1 ml of vehicle (PL) or 1 ml of 120 mM AA followed 1 hr later by 2 ml of absolute ETOH. Mucosal changes were assessed at 10, 15, and 30 min and 1, 2, 3, 6, and 15 hr after ETOH: (1) macroscopically, histologically, and by scanning EM; and (2) by determinations of (a) mitotic activity and 3H-thymidine incorporation in vivo, (b) gastric volume, pH, and electrolytes, and (c) gastric PD. Macroscopic necrotic changes were present in PL-but not AA-pretreated animals throughout the 15 hr after ETOH. Histological examination and scanning EM showed desquamation of the surface epithelium at 10 min to 2 hr and deep necrotic lesions throughout the 15 hr after ETOH in PL-pretreated animals. In AA-pretreated rats, deep necrotic lesions did not occur, but desquamation of the surface epithelium was seen during the initial 30 min after ETOH. A continuous layer of the surface epithelium was restored within 3 hr after ETOH in AA group, with resumption of the transport and barrier functions. The main feature of AA protection of gastric mucosa against ETOH injury is preservation of the mucosal proliferative zone.