PCR assay targeting virulence genes of Helicobacter pylori isolated from drinking water and clinical samples in Lahore metropolitan, Pakistan.

Helicobacter pylorus is considered for chronic gastritis, gastric ulcers and adenocarcinoma and its high infection rate is observed in overcrowded and lower socioeconomic groups in developing countries. This study was designed to identify the role of drinking water in the transmission and prevalence of H. pylori (HP). Selective HP medium was developed for enrichment and presumptive identification of H. pylori by urease, catalase and species specific 16S rRNA tests. The virulence genes (vacA 's' and 'm' regions and cagA) of H. pylori in 90 out of 225 H. pylori positive drinking water samples were present (40%). Ten out of 18 biopsies (55.55%) and 15 out of 50 vomiting fluids of gastric disease patients (30%) were also positive for virulence genes. Anti-H. pylori antibodies were also detected in 31 out of 50 patients' sera. The presence of virulence genes was also directly confirmed by hybridization studies using non-radioactive DNA probes of 16S rRNA, vacA and cagA genes. The presence of H. pylori in water is due to poor sanitary conditions, improper waste disposal and lack of public health education. PCR-based analysis and colony hybridization can be used for detection of H. pylori in clinical and environmental samples.

Histamine receptors and the conjunctiva.

PURPOSE OF REVIEW: The purpose of this review is to evaluate the effect of histamine on various receptors in the conjunctiva. A Medline search from 1980 was performed on the histamine receptor subtypes H1, H2 and H3 in the human conjunctiva. RECENT FINDINGS: In the conjunctiva, histamine has been shown to induce various physiological and immunological changes through both H1 and H2 receptor stimulation. Histamine binding to conjunctival H1 receptors through the phospholipase C-dependent inositol phosphate pathway leads to the symptom of pruritus while histamine stimulation of the conjunctival H2 receptors has been indirectly shown to cause vasodilation. SUMMARY: The effect of histamine on conjunctival H1 receptors appears to be the primary target for ocular allergy treatment as it is primarily involved in ocular pruritus. The exact interaction of the conjunctival H2 receptors appears to work in a complementary fashion to the H1 receptor in controlling other features of ocular allergy such as vasodilation and injection. Thus, oral and topical antihistamines with multiple histamine receptor binding activities may provide an improved treatment paradigm for the various signs and symptoms of ocular allergy. The histamine H1, H2 and H3 receptor affinities of ketotifen, pyrilamine, and epinastine appear to have the strongest H1 and H2 affinities.