Table 1.

Baseline characteristics of patient with low-density Helicobacter pylori

Characteristic	On presentation
Personal	Female, aged 59 years, weight 84 kg, height 1.6 m, body mass index 32.8 kg/m2
Manifestations	Brady/hypokinesia-predominant idiopathic parkinsonism, untreated
Blood profile	Full bood count, B-lymphocyte and T subset counts: normal. Serum vitamin B12, folate and ferritin: normal. Homocysteine = 21 μmol/L (target <16). Autoantibody screen: anti-intrinsic factor positive, otherwise negative including anti-nuclear antibody
Helicobacter screen	Urea-breath-test negative: immunoblot score positive: anti-urease ELISA not done
Gastric biopsy sites	Three sets (antral and corporal): two sets for histology, one microbiology
Histology	Mild chronic antral/corporal inflammation, no polymorphonuclear activity or Helicobacter-like organismsseen. No atrophy or intestinal metaplasia
Culture	Negative
Molecular microbiologya	Positive for Helicobacter DNA from three different vacA regions (s1, m2, and intermediate) in antrum, for mid-region (m2) only in corpus; both biopsies cagA negative

^aGenomic DNA extracted from biopsies (Qiagen DNeasy Tissue kit, Qiagen Ltd, Crawley, UK) and the presence of H. pylori genomic DNA tested by PCR amplification.Primers specific for three regions of vacA gene used: (1) signal-region (primers VA1-F and VA1-R [30]); (2) mid-region (primers VAG-F and VAG-R [31]); (3) intermediate-region between signal and mid (primers DL2 and VacR9 (see [32] for primer sequence)).

Signal- and mid-region primers determine vacA type by product size and hence are expected to give a product for all H. pylori strains. The additional primer pair DL2/VacR9 amplify the entire intermediate-region, and are not specific for i-region type, hence are also expected to give a product for all H. pylori strains. PCR product sizes were estimated by agarose gel electrophoresis with reference to positive control strains and a commercial DNA ladder. Product for signal-region reaction matched size of that for s1 control strain 60190 (259 bp); mid-region product matched that obtained for m2-type control strain Tx30a (645 bp). Intermediate-region amplification gave a band similar to that of 60190 (361 bp), the expected size for primer used. Negative control samples (no template) demonstrated that contamination of reagents with H. pylori DNA (a likely reason for a false-positive result) had not occurred.

The s1 signal-region allele associated with in vitro vacuolating activity, s2 Vac protein being nonvacuolating. Mid-region affects epithelial cell binding, m1 toxin vacuolating a wider variety of cells [32]. Thus, s1/m1 strains are vacuolating, s2/m2 nonvacuolating and s1/m2 variable. Intermediate-region interacts in vacuolation, according to subtype (not determined). Decreased propensity toward gastric disease expected with cagA negativity.

Primers for cagA were cag2 and cag4 [33].