A molecular basis of peptic ulceration due to diet.

Fresh rice oil protects against gastric ulceration in rats maintained on an impoverished diet, whereas stored oil is ulcerogenic. Rice oil contains ketoaldehydes which are ulcerogenic but their activity is prevented by the presence of antioxidants such as alpha-tocopherol, which is lost on storage. Protection may also be restored by the addition of cysteine. These results in rats in vivo can be duplicated in a rat liver microsomal system in vitro, in which malondialdehyde production is a measure of toxicity. It is proposed that the ulcerogenic activity of rice oil is the direct consequence of the stimulation of endogenous lipid peroxidation due to the lowering of the GSH content in the endoplasmic reticulum by the ketoaldehydes in stored rice oil. A similar mechanism is suggested for the ulcerogenic activity of an impoverished diet which directly lowers the tissue levels of GSH.     

Pictorial assessment of the delivery of oropharyngeal rinse versus oropharyngeal spray

Oral rinses/gargles and oral sprays are frequently used in the management of oropharyngeal inflammation. This pictorial study, using methylene blue dye as a marker of the distribution of these topical preparations in the oropharynx, suggests that oral sprays are more effective in coating the oropharynx than oral rinses, whilst oral rinses are better at staining the oral cavity and base of tongue. The authors therefore suggest that oral rinses should be used to treat disease in the oral cavity and oral sprays should be used to treat ailments in the oropharynx.     

The laryngeal mask airway in tonsillectomy: the surgeon's perspective

The laryngeal mask airway presents certain advantages in the management of the airway during general anaesthesia. However, from the surgeon's perspective, there have been reports of problems occurring when the laryngeal mask airway is used in tonsillectomy. This study of 90 patients undergoing tonsillectomy suggests that surgical access is inferior with a laryngeal mask airway and the weight of tonsillar tissue excised is less. In addition the laryngeal mask airway needs to be changed to an endotracheal tube during the procedure in 11.4% of patients.     

Systematic errors in bone conduction audiometry

Air and bone conduction audiometry was carried out on two separate groups of 12 normal hearing volunteers. One group was tested at St Mary's hospital, the other at Charing Cross hospital. The results from both centres showed evidence of a systematic error in bone conduction resulting in a pattern of 'notching' at 2 kHz. We argue that the effect is likely to be more apparent in conductive deafness and that a significant distortion of the audiogram occurs in about 17% of such cases. Since the problem appears not to be restricted to the centres involved in the study, we strongly recommend that the issue be addressed by the appropriate professional bodies.     

Dietary factors in relation to the distribution of duodenal ulcer in India as assessed by studies in rats

BACKGROUND: The prevalence of duodenal ulcer is less in the northern wheat-eating regions of India and China than in the southern rice-eating areas. METHODS AND RESULTS: Experiments were conducted on rat peptic ulcer models in which controls were fed on either known ulcerogenic rice or rice plus tapioca diets or on non-ulcerogenic stock diet. By using an ulcerogenic diet and pyloric ligation, unrefined wheat, wheat bran and their respective oils were protective against ulceration. Refined wheat, wheat germ and its oil were not protective. Freshly milled rice and unmilled rice were protective, but stored rice bran and its oil increased the ulceration. Fresh rice bran oil was not ulcerogenic, but on storage, it became ulcerogenic. By using stock diet and alcohol-induced ulceration, the findings with whole wheat oil, wheat bran and wheat germ oil were confirmed. Rats fed on the stock diet subjected to pyloric ligation developed ulcers following intragastric injection of stored rice bran oil. This ulcerogenicity was counteracted by whole wheat oil. CONCLUSION: These results suggest that the factor of diet may well explain the regional differences in the prevalence of duodenal ulceration between North and South India and China where other etiologic factors are similar.     

S-arylcysteine-keratin adducts as biomarkers of human dermal exposure to aromatic hydrocarbons

To measure biomarkers of skin exposure to ubiquitous industrial and environmental aromatic hydrocarbons, we sought to develop an ELISA to quantitate protein adducts of metabolites of benzene and naphthalene in the skin of exposed individuals. We hypothesized that electrophilic arene oxides formed by CYP isoforms expressed in the human skin react with nucleophilic sites on keratin, the most abundant protein in the stratum corneum that is synthesized de novo during keratinocyte maturation and differentiation. The sulfhydryl groups of cysteines in the head region of the keratin proteins 1 (K1) and 10 (K10) are likely targets. The following synthetic S-arylcysteines were incorporated into 10-mer head sequences of K1 [GGGRFSS( S-aryl-C)GG] and K10 [GGGG( S-aryl-C)GGGGG] to form the predicted immunogenic epitopes for antibody production for ELISA: S-phenylcysteine-K1 (SPK1), S-phenylcysteine-K10 (SPK10), S-(1-naphthyl)cysteine-K1 (1NK1), S-(1-naphthyl)cysteine-K10 (1NK10), S-(2-naphthyl)cysteine-K1 (2NK1), and S-(2-naphthyl)cysteine-K10 (2NK10). Analysis by ELISA was chosen based on its high throughput and sensitivity, and low cost. The synthetic modified oligopeptides, available in quantity, served both as immunogens and as chemical standards for quantitative ELISA. Polyclonal rabbit antibodies produced against the naphthyl-modified keratins reacted with their respective antigens with threshold sensitivities of 15-31 ng/mL and high specificity over a linear range up to 500 ng/mL. Anti- S-phenylcysteine antibodies were not sufficiently specific or sensitive toward the target antigens for use in ELISA under our experimental conditions. In dermal tape-strip samples collected from 13 individuals exposed to naphthalene-containing jet fuel, naphthyl-conjugated peptides were detected at levels from 0.343 +/- 0.274 to 2.34 +/- 1.61 pmol adduct/microg keratin but were undetectable in unexposed volunteers. This is the first report of adducts of naphthalene (or of any polycyclic aromatic hydrocarbon) detected in the exposed intact human skin. Quantitation of naphthyl-keratin adducts in the skin of exposed individuals will allow us to investigate the importance of dermal penetration, metabolism, and adduction to keratin and to predict more accurately the contribution of dermal exposure to systemic dose for use in exposure and risk-assessment models.