Gastric mucosal damage by aspirin

Co-lyophilized Aspirin with Trehalose Causes Less Injury to Human Gastric Cells and Gastric Mucosa of Rats

BACKGROUND

Aspirin is one of the most popular NSAIDs worldwide because of its anti-inflammatory and anticoagulant effects, and however, gastrointestinal injury remains a major complication. We previously reported co-lyophilized aspirin/trehalose (Lyo A/T) decreased the aspirin-induced gastric lesions in dogs.

AIM

This study investigated the mechanism of gastroprotective effects of trehalose in vitro and in vivo.

METHODS

The apoptotic assays were performed in a human gastric carcinoma cell line, which was treated with aspirin, mixed aspirin/trehalose (Mix A/T) or Lyo A/T. Gastric ulcer severity was examined after oral administration of drugs in rats. In addition, the mucosal tissue apoptotic status in drug-treated rats was evaluated. Molecular dynamics simulations and laser Raman spectroscopy were performed in order to examine the molecular properties of Lyo A/T.

RESULTS

DNA fragmentation was detected in AGS cells that were treated with aspirin and Mix A/T, but not in the Lyo A/T-treated cells. There were fewer apoptotic cells in the Lyo A/T-treated cells than in the other cells. Gastric injury was reduced in rats that received oral Lyo A/T compared with the others, while PGE2 synthesis was equally decreased in all groups. TUNEL assay and immunohistochemistry of cleaved caspase-3 in the mucosal tissues also revealed that Lyo A/T treatment induced less apoptosis than the others. The Lyo A/T spectrum showed clear differences in several Raman bands compared with that of Mix A/T.

CONCLUSIONS

Our data showed that co-lyophilization of aspirin with trehalose reduced gastric injury, potentially through suppression of aspirin-induced mucosal cell apoptosis while retaining its anti-inflammatory effects.

Emesis in dogs: a review

Emesis is a common presenting sign in small animal practice. It requires a rational approach to management that is based upon a sound understanding of pathophysiology combined with logical decision making. This review, which assesses the weight of available evidence, outlines the physiology of the vomiting reflex, causes of emesis, the consequences of emesis and the approach to clinical management of the vomiting dog. The applicability of diagnostic testing modalities and the merit of traditional approaches to management, such as dietary changes, are discussed. The role and usefulness of both traditional and novel anti-emetic drugs is examined, including in specific circumstances such as following cytotoxic drug treatment. The review also examines areas in which common clinical practice is not necessarily supported by objective evidence and, as such, highlights questions worthy of further clinical research.

Immunoelectrophoretic pattern of native mucosal intracellular glycoproteins of hog healthy and drug-intoxicated stomachs and of hog body fluids

Naturally occurring glycoproteins have been extracted from fundic and antral mucosal tissue of the hog stomach by means of nondegrading techniques. Major and retarded glycoprotein fractions separated by gel filtration were further dissociated from appreciable amounts of noncovalently bound proteins by CsCl density gradient centrifugation. Antisera to glycoprotein fractions of fundic and antral regions of the stomach were prepared in rabbits. The major fractions from both gastric regions have similar molecular mass (approximately 2 x 10(6)), sedimentation coefficient (approximately 31.5 s), and specific viscosity (approximately 1.6). Purified fractions from each region were further separated into two subfractions by affinity chromatography on wheat germ lectin. Glycoprotein subfractions from antrum and fundus differ appreciably in their carbohydrate and amino acids content, share antigenic determinants, but do not cross-react with anti-hog serum protein antisera. Further diversity in native mucin glycoproteins was observed by the use of one-(D) and two-dimensional (2D) immunoelectrophoresis; subfractions that cross-react with specific anti-hog gastric glycoproteins were found to contain three or more components. D-Immunoelectrophoretic analyses demonstrated (1) in vivo degradation of glycoprotein components of the major fundic fraction isolated from mucosal tissue of alcohol/acetyl salicylate-intoxicated hog stomachs and (2) in vitro catabolism of major fundic glycoproteins by corresponding mitochondrial lysosomal (ML) acid hydrolases. Furthermore, 2D-immunoelectrophoretic analyses showed that (1) hog synovial fluid and plasma proteins have similar prosthetic moieties as either reacted with anti-hog serum proteins antisera. Nonetheless, locations, shapes, and staining intensities of the immunoprecipitate lines differed, which is indicative of different structures of the carbohydrate moieties of components of synovial fluid and plasma proteins, and (2) only a minor fraction of hog cerebrospinal fluid cross-reacted with anti-hog serum protein antisera. This is contrary to the generally accepted deduction based on high-resolution 2D-electrophoresis, indicative of different compositional patterns of plasma and cerebrospinal fluids.

Gastrointestinal ulcerations induced by anti-inflammatory drugs in rats. Physicochemical and biochemical factors involved

Aspirin, diclofenac, diflunisal, ibuprofen and indomethacin were given orally or intravenously to fasted or fed rats. The resulting gastric and intestinal damage was assessed using standard methods. The same drugs were administered to rats with biliary fistulas, and the fraction of drug excreted in bile was quantified using HPLC methods. We found that gastric damage occurred only in the fasted animals and was found to be dose-dependent and related to the amount (r = 0.871) and solubility (r = 0.909) of the individual drug. As far as acute gastric toxicity is concerned, neither the potency of a drug as an inhibitor of cyclo-oxygenase nor the fraction of unchanged or conjugated agent excreted in bile appeared to be relevant. Secondly, ulcerations of the small intestine occurred in fed animals only. The degree of damage was related to the amount of unchanged or conjugated drug excreted in bile and cyclo-oxygenase inhibitory potency (r = 0.873). The administered dose (within the range investigated) and drug solubility appeared not to contribute to intestinal toxicity. It is concluded that, in the rat, acute gastric and intestinal toxicity of non-steroidal anti-inflammatory drugs are due to different mechanisms. Whereas gastric toxicity is strongly influenced by the amount of drug dissolved under the pH conditions in the stomach, intestinal toxicity appears to depend on biliary excretion and enterohepatic circulation of a drug as well as on its potency as an inhibitor of prostaglandin synthesis.

Reduction in gastric mucosal hemorrhage and ulceration with chronic high-level dosing of enteric-coated aspirin granules two and four times a day

When administered on a chronic high-dosage regimen, enteric-coated aspirin granules produced significantly less gastric damage than plain aspirin or aspirin-antacid combinations. Clinically meaningful damage occurred in all subjects receiving plain aspirin, 93% of those receiving aspirin-antacid combination and only 27% and 20% of those receiving enteric-coated aspirin granules qid and bid, respectively. All three aspirin formulations were taken as 1 g qid (4 g/day) and an additional group received enteric granules administered as 2 g bid (4 g/day). Gastric damage was assessed by means of endoscopy carried out after seven days of treatment. Enteric granules are equally safe when administered on a bid or qid regimen (at same total daily dosage) and, in a bid regimen, should provide a compliance advantage for patients on high-dose therapy for diseases such as rheumatoid arthritis.

Evaluation of radiochromium blood loss studies in unexplained iron-deficiency anaemia

Radiochromium measurement of gastrointestinal (GI) blood loss was performed on an outpatient basis on 57 patients with unexplained iron-deficiency anaemia. With the exception of pre-menopausal women, patients were only selected for study if the anaemia remained unexplained after careful GI radiological and endoscopic examination. Occult GI blood loss was confirmed in 31 patients and further investigation including laparotomy in some cases, led to a diagnosis in 17 of the 31. Carcinoma was present in five (colon four, stomach one) and benign lesions of the small intestine in five. There was no correlation between the severity or pattern of bleeding and the nature of the lesion. Of the 26 patients without demonstrable occult bleeding, anaemia was aspirin-induced in five and caused by menorrhagia in six. With the pre-menopausal women, measurement of both GI and menstrual blood loss resulted in detection of silent GI lesions in four and gynaecological disease in six. The cause of anaemia has not been elucidated in 23 of the 57 patients, including seven of 11 with aortic valve disease, even after follow-up for an average of 3.0 years. These results indicate that radiochromium studies effectively identify the patients with unexplained iron-deficiency anaemia who require continued active investigation for a focal GI lesion.