Nickel is an essential transition metal for the virulence and survival of Helicobacter pylori in the acidic human stomach. The nickel– and proton– dependent transcriptional regulator HpNikR is important for maintaining nickel homeostasis inside the cytosol by regulating multiple H. pylori genes. A previous ChIP-sequencing experiment with H. pylori G27 and HpNikR identified two novel genes currently annotated as putative iron-transporters, HpG27_866 and HpG27_1499. In vitro DNA-binding assays with the promoter sequences of the two genes revealed nickel-dependent HpNikR binding with an affinity of ~10-7 M. The recognition site of HpNikR was identified on HpG27_1499 by footprinting assays, which loosely correlates with the HpNikR pseudo-consensus sequence. Furthermore, HpG27_1499 transcription showed nickel-dependent repression in WT H. pylori, and no changes in an isogenic ΔnikR strain. These data suggest that HpG27_1499 could be a nickel importer that is regulated by HpNikR in a nickel-responsive manner.

Introduction: Gastric cancer (GC) is ranked as the second most common fatal malignancy worldwide. Although Helicobacter pylori is recognized as a major predisposing factor for non-cardia GC, infection alone is not sufficient to cause cancer. This thesis aimed to determine the variation in host genetic polymorphisms in subjects from Malaysia and Singapore and to examine the role of H. pylori infection, host genetic factors and dietary factors in the etiology of non-cardia GC in Chinese subjects resident in Malaysia. Methods: Functional dyspepsia (FD) controls from three ethnic groups in Malaysia, Chinese (123), Indian (110) and Malay (84) and Singaporean Chinese (127) plus Malaysian Chinese gastric cancer cases (55)were examined. Polymorphisms in IL-1B-511, IL-1RN, IL-10 cluster, TNFA-308 and TLR5+1174 were determined by PCR-RFLP or PCR; H. pylori status by serology, dietary intake by questionnaire and gastric IL-1b levels by real time PCR. Results: 1) Significant differences existed in the frequency of all polymorphisms, except IL-1B-1473 and TNFA-308, in the three Malaysian ethnic groups and in the IL-1B-511 polymorphism in Malaysian and Singaporean Chinese FD 2) Globally, two distinct patterns of IL-1B-511, IL-1RN, IL-10-1082, IL-10-592 and TNFA-308 exist, Western and East-Asian 3) In Malaysian Malays, the IL-10 ATA haplotype was associated with H. pylori susceptibility 4) In Malaysian Chinese an increased risk of GC was associated with carriage of the IL-1B-1473 G allele {OR=4.4(1.3-15.3)} and the IL-1B-511 C allele {OR=1.8(0.8-4.1)} 5) Increased levels of IL-1b were observed in Singaporean and Malaysian Chinese FD subjects carrying the IL-1-511C and IL-1-1473G alleles 6) Malaysian Chinese not consuming fresh fruit and vegetables had the highest risk of GC {OR=10.2 (3.4-30.6)} 7) The highest risk of GC {OR=37.3(3.3-424.8)} was observed in H. pylori positive Malaysian Chinese who carried both the IL-1B-511C and IL-1B-1473G alleles and did not consume fresh fruit and vegetables. Conclusions: In Malaysian Chinese, H. pylori infection, host genetic and dietary factors all contribute to the risk of GC. However the significant difference observed in the frequency of host genetic polymorphisms within and between ethnic groups suggests that a single group of risk factors cannot be used to determine GC risk across all populations.

Tez (Tıpta Uzmanlık) - Süleyman Demirel Üniversitesi, Tıp Fakültesi, İç Hastalıkları ve Doğum Anabilim Dalı, 2006. / Bibliyografya var.

Diss. (sammanfattning) Linköping : Univ., 2002. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Linköping : Univ., 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2004. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 60-66). Also available for download via the World Wide Web; free to University of Oregon users.

Tez (Tıpta Uzmanlık) - Süleyman Demirel Üniversitesi, Tıp Fakültesi, Çocuk Sağlığı ve Hastalıkları Anabilim Dalı, 2002. / Bibliyografya var.