Gastric cytoprotection by sodium salicylate

Sodium salicylate (SA), contrary to acetylsalicylic acid (ASA, aspirin), was not ulcerogenic in rats. SA was also found to be cytoprotective: it prevented formation of gastric mucosal necrosis produced by either absolute ethanol or 0.6 M HCl, and formation of gastric ulcers produced by acidified ASA. The degree of protection was dose dependent. The mechanism of this cytoprotection is unknown, but unlike cytoprotection elicited by mild irritants, e.g., 20% ethanol or 0.35 M HCl, whose effects appear to be due to endogenous formation of PG by the stomach, SA acts through a different mechanism, since its protective effect was not blocked by indomethacin.     

Apparent reduction of endogenous creatinine clearance by salicylate treatment.

A prospective study of nine patients with rheumatoid arthritis and 11 healthy volunteers who started salicylate treatment showed that in 18 of the 20 subjects creatinine clearance values fell the average being 25%. Serum creatinine concentration was increased by an average of 38%, although blood urea levels were unchanged. Since 51Cr-edetic acid clearance tests performed at the same time in 12 of the subjects were not affected, the fall in creatinine clearance was probably not due to impaired glomerular function, and salicylate ingestion may therefore invalidate the creatinine clearance test as an index of glomerular filtration rate. It is clearly important to inquire into the patient''s analgesic comsumption when using the creatinine clearance test to assess glomerular function.     

The promoter of Rv0560c is induced by salicylate and structurally-related compounds in Mycobacterium tuberculosis

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a major global health threat. During infection, bacteria are believed to encounter adverse conditions such as iron depletion. Mycobacteria synthesize iron-sequestering mycobactins, which are essential for survival in the host, via the intermediate salicylate. Salicylate is a ubiquitous compound which is known to induce a mild antibiotic resistance phenotype. In M. tuberculosis salicylate highly induces the expression of Rv0560c, a putative methyltransferase. We identified and characterized the promoter and regulatory elements of Rv0560c. P(Rv0560c) activity was highly inducible by salicylate in a dose-dependent manner. The induction kinetics of P(Rv0560c) were slow, taking several days to reach maximal activity, which was sustained over several weeks. Promoter activity could also be induced by compounds structurally related to salicylate, such as aspirin or para-aminosalicylic acid, but not by benzoate, indicating that induction is specific to a structural motif. The -10 and -35 promoter elements were identified and residues involved in regulation of promoter activity were identified in close proximity to an inverted repeat spanning the -35 promoter element. We conclude that Rv0560c expression is controlled by a yet unknown repressor via a highly-inducible promoter.     

Naphthalene degradation via salicylate and gentisate by Rhodococcus sp. strain B4.

Rhodococcus sp. strain B4, isolated from a soil sample contaminated with polycyclic aromatic hydrocarbons, grows with naphthalene as the sole source of carbon and energy. Salicylate and gentisate were identified as intermediates in the catabolism of naphthalene. In contrast to the well-studied catabolic pathway encoded by the NAH7 plasmid of Pseudomonas putida, salicylate does not induce the genes of the naphthalene-degradative pathway in Rhodococcus sp. strain B4. The key enzymes of naphthalene degradation in Rhodococcus sp. strain B4 have unusual cofactor requirements. The 1,2-dihydroxynaphthalene oxygenase activity depends on NADH and the salicylate 5-hydroxylase requires NADPH, ATP, and coenzyme A.