Delayed gastric ulcer healing after extirpation of submandibular glands is sex-dependent

Sex-specific association of epidermal growth factor gene polymorphisms with acute respiratory distress syndrome

Epidermal growth factor (EGF) is involved in alveolar epithelial repair, lung fluid clearance and inflammation, and is regulated by sex hormones. An unmatched, nested case-control study was conducted to evaluate the associations of EGF variants with acute respiratory distress syndrome (ARDS) and the role of sex on the associations between EGF variants and ARDS. Patients with ARDS risk factors upon intensive care unit admission were enrolled. Cases were 416 Caucasians who developed ARDS and controls were 1,052 Caucasians who did not develop ARDS. Cases were followed for clinical outcomes and 60-day mortality. One functional single nucleotide polymorphism (SNP), rs4444903, and six haplotype-tagging SNPs spanning the entire EGF gene were genotyped. No individual SNP or haplotype was associated with ARDS risk or outcomes in all subjects. Sex-stratified analyses showed opposite effects of EGF variants on ARDS in males versus in females. SNPs rs4444903, rs2298991, rs7692976 and rs4698803, and haplotypes GGCGTC and ATCAAG were associated with ARDS risk in males. No associations were observed in females. Interaction analysis showed that rs4444903, rs2298991, rs7692976 and rs6533485 significantly interacted with sex for ARDS risk. The present study suggests that associations of epidermal growth factor gene variants with acute respiratory distress syndrome risk are modified by sex. The current findings should be replicated in other populations.

An overview of acetic acid ulcer models--the history and state of the art of peptic ulcer research

Four types of experimental chronic ulcer models, named acetic acid ulcer models, have been developed to examine the healing process of peptic ulcers, screen anti-ulcer drugs, and better evaluate the adverse effects of various anti-inflammatory drugs on the gastrointestinal mucosa. The model easily and reliably produces round, deep ulcers in the stomach and duodenum, allowing acetic acid ulcer production in mice, rats, Mongolian gerbils, guinea pigs, cats, dogs, miniature pigs, and monkeys. These ulcer models highly resemble human ulcers in terms of both pathological features and healing process. The models have been established over the past 35 years and are now used throughout the world by basic and clinical scientists. One of the characteristic features of acetic acid ulcers in rats is the spontaneous relapse of healed ulcers >100 d after ulceration, an endoscopically confirmed phenomenon. Indomethacin significantly delays the healing of acetic acid ulcers, probably by reducing endogenous prostaglandins and inhibiting angiogenesis in ulcerated tissue. Helicobacter pylori significantly delays healing of acetic acid ulcers and causes relapse of healed ulcers at a high incidence in Mongolian gerbils. Anti-secretory drugs (e.g. omeprazole), prostaglandin analogs, mucosal defense agents (e.g. sucralfate), and various growth factors all significantly enhance healing of acetic acid ulcers. Gene therapy with epidermal growth factor and vascular endothelial growth factor applied to the base of acetic acid ulcers in rats is effective in enhancing ulcer healing. Since an inhibitor of nitric oxide syntase prevents ulcer healing, nitric oxide might be involved in the mechanism underlying ulcer healing. We conclude that acetic acid ulcer models are quite useful for various studies related to peptic ulcers.

Sialoadenectomy alters liver cell turn-over and function in mice

In rodents, submandibular salivary glands accumulate a number of biologically active peptides, and release some of them to both saliva and the bloodstream. Surgical removal of these glands (sialoadenectomy) alters the ability of the liver to regenerate after partial hepatectomy. We show here that 5 weeks after surgery, the liver of sialoadenectomized mice contained 40% fewer hepatocytes than the liver of sham-operated mice. We did not obtain evidence of necrotic cell death after surgery. In contrast, sialoadenectomy transiently increased apoptotic hepatocyte death, as revealed by terminal deoxynucleotidyl transferase(TdT)-mediated dUTP nick-end labeling (TUNEL) assay. DNA synthesis was determined in vivo by the incorporation of bromo-deoxyuridine (BrdU) into hepatocyte nuclei. BrdU-labeling progressively increased after sialoadenectomy. We conclude that sialoadenectomy induced a transient wave of apoptotic cell death followed by a rise in DNA synthesis but not by cell division. This reduced cell number but increased mean cell volume. In spite of these alterations in cellularity, the liver responded adequately to several stressful conditions, as judged by the lack of any differential effect of sialoadenectomy on liver glycogen and plasma glucose concentration after immobilization, aggressive encounter, or fasting. However, the liver of sialoadenectomized mice was more sensitive to the effect of a non-lethal dose of bacterial lipopolysaccharide (LPS) combined with d-galactosamine, as shown by the enhanced rise in plasma alanine aminotransferase and aspartate aminotransferase, and liver myeloperoxidase (MPO) activities. All these results indicate that a submandibular salivary glands-liver axis is involved in the maintenance of liver structure in mice. A disturbance of this axis induces an adaptive response that preserves the metabolic function of the liver but renders it more sensitive to bacterial endotoxins.

Epidermal growth factor is critical for intestinal adaptation following small bowel resection

The loss of small intestinal mucosal surface area is a relatively common clinical situation seen in both the pediatric and adult population. The most frequent causes include mesenteric ischemia, trauma, inflammatory bowel disease, necrotizing enterocolitis, and volvulus. Following surgical resection, the remnant intestine compensates or adapts to the loss of native bowel by increasing its absorptive surface area and functional capacity. Unfortunately, many patients fail to adapt adequately, and are relegated to lifelong intravenous nutrition. Research into intestinal adaptation following small bowel resection (SBR) has evolved only recently from the gross and microscopic level to the biochemical and genetic level. As understanding of this process has increased, numerous therapeutic strategies to augment adaptation have been proposed. Epidermal growth factor (EGF) is an endogenous peptide that is secreted into the gastrointestinal tract and able to influence gut ontogeny, as well as mucosal healing. Early studies have demonstrated its ability to augment the adaptive process. Focusing on a murine model of massive intestinal loss, the morphological, structural, biochemical, and genetic changes that occur during the intestinal adaptive process will be reviewed. The role of EGF and its receptor as critical mediators of the adaptive process will be discussed. Additionally, the ability of EGF to augment intestinal proliferation and diminish programmed cell death (apoptosis) following SBR will be examined. Enhancing adaptation in a controlled manner may allow patients to transition off parenteral nutrition to enteral feeding and, thereby, normalize their lifestyle.

Epidermal growth factor is critical for intestinal adaptation following small bowel resection

The loss of small intestinal mucosal surface area is a relatively common clinical situation seen in both the pediatric and adult population. The most frequent causes include mesenteric ischemia, trauma, inflammatory bowel disease, necrotizing enterocolitis, and volvulus. Following surgical resection, the remnant intestine compensates or adapts to the loss of native bowel by increasing its absorptive surface area and functional capacity. Unfortunately, many patients fail to adapt adequately, and are relegated to lifelong intravenous nutrition. Research into intestinal adaptation following small bowel resection (SBR) has evolved only recently from the gross and microscopic level to the biochemical and genetic level. As understanding of this process has increased, numerous therapeutic strategies to augment adaptation have been proposed. Epidermal growth factor (EGF) is an endogenous peptide that is secreted into the gastrointestinal tract and able to influence gut ontogeny, as well as mucosal healing. Early studies have demonstrated its ability to augment the adaptive process. Focusing on a murine model of massive intestinal loss, the morphological, structural, biochemical, and genetic changes that occur during the intestinal adaptive process will be reviewed. The role of EGF and its receptor as critical mediators of the adaptive process will be discussed. Additionally, the ability of EGF to augment intestinal proliferation and diminish programmed cell death (apoptosis) following SBR will be examined. Enhancing adaptation in a controlled manner may allow patients to transition off parenteral nutrition to enteral feeding and, thereby, normalize their lifestyle.

Salivary epidermal growth factor and intestinal adaptation in male and female mice

Salivary epidermal growth factor (sEGF) levels are increased in male mice after small bowel resection (SBR) and may be important during intestinal adaptation. Since males have greater sEGF than females, the influence of sex on postresection adaptation was tested. Females had lower sEGF; however, sEGF substantially increased in both sexes after a massive (50%) SBR. Adaptive increases in DNA and protein content, villus height, and crypt depth, as well as crypt cell proliferation rates in the remnant ileum, were not different between males and females. Although significant postresection increases in sEGF were identified, EGF mRNA and protein did not change within the submandibular gland. Glandular kallikrein-13 and ileal EGF receptor expression were greater after SBR in female mice. Intestinal adaptation is equivalent in female and male mice after SBR. Despite lower sEGF, females demonstrated increased expression of a kallikrein responsible for sEGF precursor cleavage as well as amplified ileal EGF receptor expression. These results endorse an important differential response between sexes regarding sEGF mobilization and intestinal receptor availability during adaptation.

Review article: factors protecting the oesophagus against acid-mediated injury

Reflux of gastric acid and pepsins into the lower oesophagus causes symptoms such as heartburn and nausea, and tissue injury leading to erosive oesophagitis and stricture formation. This article reviews the mechanisms involved in protecting the oesophagus against acid-mediated injury, including the role of the lower oesophageal sphincter, secondary oesophageal peristalsis and swallowed saliva. The oesophageal mucosa has inherent abilities to resist acid damage, and recent data from three laboratories suggest a secretory function with local production of bicarbonate and mucus responsive to local acidification. The evidence for these putative oesophageal defence mechanisms is discussed.

Neuroendocrine regulation of inflammation and tissue repair by submandibular gland factors

Interactions between the immune, nervous and endocrine systems are important in inflammation and tissue repair. One neuroendocrine pathway involves polypeptide factors derived from the submandibular glands, whose synthesis and release are controlled by cervical sympathetic nerves. This novel pathway of immune-neuroendocrine communication is the cervical sympathetic trunk-submandibular gland (CST-SMG) axis. Here, Ronald Mathison, Joseph Davison and Dean Befus discuss the contributions of this axis to the neuroendocrine regulation of inflammation and tissue repair.

Epidermal growth factor accelerates connective tissue wound healing in the perforated rat mesentery

Epidermal growth factor (EGF) has been reported to stimulate healing of wounds in skin, cornea, and gastric mucosa. In the present study, we further investigate the effect of endogenous and exogenous EGF in healing of connective tissue wounds using the rat perforated mesentery model. Healing of mesenteric perforations is accomplished by the connective tissue fibroblasts since there are no interfering variables such as interactions of epithelial cells, desiccation, or foreign materials such as sutures or subcutaneous implants. We performed laparotomy in 114 adult male Sprague-Dawley rats and made 20 standardized perforations in the mesentery of each rat with a scalpel. Rats were randomly assigned to five groups. Group I received no treatment after surgery; Group II received intraperitoneal injections of phosphate-buffered saline (PBS) after surgery and then twice daily for the following 3 days; Group III received 10 micrograms of EGF in the PBS injections according to the same regimen as Group II; Group IV had sham exploration of the submandibular salivary glands; and Group V animals had excision of the submandibular glands 3 days before laparotomy to deprive the main source of EGF in rat. On Days 4 through 10 after surgery rats were sacrificed and the percentage of perforations in each rat which were closed was determined. The curves for the time course of wound closure for Groups IV and V were not different indicating that endogenous submandibular EGF does not play a role in healing of mesenteric wounds.(ABSTRACT TRUNCATED AT 250 WORDS)