Keiji Oguma

The effect of eradicating Helicobacter pylori on the development of gastric cancer in patients with peptic ulcer disease

OBJECTIVES:Infection with Helicobacter pylori is a risk factor for the development of gastric cancer. However, it is not known whether eradication therapy can prevent the development of gastric cancer in persons in whom the cancer is not yet established. In the present study, we investigated whether the eradication of H. pylori in patients with peptic ulcer disease reduces the likelihood of their developing gastric cancer.METHODS:Prospective posteradication evaluations were conducted in 1,342 consecutive patients (1,191 men and 151 women; mean age: 50 yr) with peptic ulcer diseases who had received H. pylori eradication therapy. After confirmation of eradication, endoscopy and a urea breath test were performed yearly.RESULTS:A total of 1,120 patients completed more than 1-yr follow-up and were followed for up to 8.6 yr (a mean of 3.4 yr). Gastric cancer developed in 8 of 944 patients cured of infection and 4 of 176 who had persistent infection (p = 0.04; log-rank test). All the gastric cancer developed in patients with gastric ulcer, but none in patients with duodenal ulcer (p = 0.005; Fishers exact test). In patients with gastric ulcer, persistent infection was identified as a significant factor for the risk of developing gastric cancer (hazard ratio: 3.35; 95% confidence interval: 1.00–11.22; p = 0.04; Coxs proportional-hazards model).CONCLUSION:H. pylori eradication may reduce their risk of developing gastric cancer in patients with gastric ulcer. Large-scale studies in additional populations of this important international public-health issue are warranted.

Structure and Function of Clostridium botulinum Toxins

Clostridium botulinum strains produce seven immunologically distinct neurotoxins, types A to G. The neurotoxins inhibit the release of acetylcholine (Ach) at the neuromuscular junctions and synapses, and cause botulism in humans and animals. The molecular mass (Mr) of all types of neurotoxins are approximately 150 kDa. The neurotoxins associate with nontoxic components in culture, and become large complexes varying from 300 kDa (12S) to 900 kDa (19S), which are designated as progenitor toxins. Recently, the genes coding for type A to G neurotoxins have been cloned, and their whole nucleotide sequences have been determined. Furthermore, it has become clear that the neurotoxins are Zn2+ -binding proteins and possess protease activities. Structures of the nontoxic components of the progenitor toxins have also been investigated genetically in types C, E and F. In this paper, the gene organization of the neurotoxins and the nontoxic components is summarized, and their structure and function are discussed.

The haemagglutinin of Clostridium botulinum type C progenitor toxin plays an essential role in binding of toxin to the epithelial cells of guinea pig small intestine, leading to the efficient absorption of the toxin

Binding of the purified type C 7S (neurotoxin), 12S and 16S botulinum toxins to epithelial cells of ligated small intestine or colon of the guinea pig (in vivo test) and to pre-fixed gastrointestinal tissue sections (in vitro test) was analysed. The 16S toxin bound intensely to the microvilli of epithelial cells of the small intestine in both in vivo and in vitro tests, but did not bind to cells of the stomach or colon. The neurotoxin and 12S toxin did not bind to epithelial cells of the small intestine or to cells of the stomach or colon. Absorption of the toxins was assessed by determining the toxin titre in the sera of guinea pigs 6-8 h after the intra-intestinal administration of the toxins. When the 16S toxin [1 x 10(5) minimum lethal dose (MLD)] was injected, 200-660 MLD ml-1 was detected in the sera, whereas when the 12S toxin (2 x 10(5) MLD) or 7S toxin (2 x 10(5) MLD) was injected, little toxin activity was detected in the sera. Therefore, the haemagglutinin of type C 16S toxin is apparently very important in the binding and absorption of botulinum toxin in the small intestine.

Identification and characterization of functional subunits of Clostridium botulinum type A progenitor toxin involved in binding to intestinal microvilli and erythrocytes

Clostridium botulinum type A hemagglutinin‐positive progenitor toxin consists of three distinct components: neurotoxin (NTX), hemagglutinin (HA), and non‐toxic non‐HA (NTNH). The HA consists of four subcomponents designated HA1, 2, 3a and 3b. By employing purified toxin and GST‐fusion proteins of each HA subcomponent, we found that the HA‐positive progenitor toxin, GST‐HA1 and GST‐HA3b bind to human erythrocytes and microvilli of guinea pig upper small intestinal sections. The HA‐positive progenitor toxin and GST‐HA1 bind via galactose moieties, GST‐HA3b binds via sialic acid moieties. GST‐2 and GST‐3a showed no detectable binding.

The HA proteins of botulinum toxin disrupt intestinal epithelial intercellular junctions to increase toxin absorption.

The type B botulinum neurotoxin (BoNT) elicits flaccid paralysis and death in humans by intoxicating peripheral nerves after oral absorption. Here, we examine the function of the haemagglutinin (HA), a non‐toxic component of the large 16S BoNT complex. We find that the HA acts in the intestine to disrupt epithelial barrier function by opening intercellular tight and adherens junctions. This allows transport of BoNT and other large solutes into the systemic circulation and explains how the type B BoNT complexes are efficiently absorbed. In vitro, HA appears to act on the epithelial cell via the basolateral membrane only, suggesting the possibility of another step in the absorptive process. These studies show that the 16S BoNT complex is a multifunctional protein assembly equipped with the machinery to efficiently breach the intestinal barrier and act systemically on peripheral nerves.

Baseline gastric mucosal atrophy is a risk factor associated with the development of gastric cancer after Helicobacter pylori eradication therapy in patients with peptic ulcer diseases

Background We previously reported that eradication of Helicobacter pylori could reduce the risk of developing gastric cancer in patients with peptic ulcer diseases. In the present study, we further followed up our patient groups to identify factors associated with the development of gastric cancer.MethodsProspective posteradication evaluations were conducted in 1342 consecutive patients (1191 men and 151 women; mean age, 50 years) with peptic ulcer disease who had received H. pylori eradication therapy. The patients had undergone endoscopic examination before eradication therapy to evaluate peptic ulcers, background gastric mucosa, and H. pylori infection. After confirmation of eradication, follow-up endoscopy was performed yearly.ResultsA total of 1131 patients were followed for up to 9.5 years (mean, 3.9 years). Gastric cancer developed in 9 of 953 patients cured of infection and in 4 of 178 who had persistent infection (P = 0.04). The risk of developing gastric cancer after receiving H. pylori eradication therapy was increased according to the grade of baseline gastric mucosal atrophy (P = 0.01). In patients with peptic ulcer diseases, persistent infection of H. pylori (hazard ratio, 3.9; P = 0.03), the grade of baseline gastric mucosal atrophy (3.3, P = 0.01) and age (2.0, P = 0.04) were identified as significant risk factors for developing gastric cancer.ConclusionsThe grade of gastric atrophy was closely related to the development of gastric cancer after receiving H. pylori eradication therapy. Thus, eradication of H. pylori before the significant expansion of atrophy is most beneficial to prevent gastric cancer.

Structure and Function of Clostridium Botulinum Progenitor Toxin

Clostridium botulinum strains produce seven immunologically distinct neurotoxins (NTX), type A to G. the NTXs associate with nontoxic components in cultures, and become large complexes with three forms (12S, 16S, and 19S) designated progenitor toxins. the 12S toxin consists of a NTX and a nontoxic component having no hemagglutinin (HA) activity (described here as non-toxic non-HA, NTNH), and the 16S and 19S toxins are formed by conjugation of the 12S toxin with HA. Based on the genetic-and protein chemical-analyses of the progenitor toxins it became clear that 1) the HA consists of four subcomponents namely HA1 (Mr. 33–35 kDa), HA2 (15–17 kDa), HA3a (19–23 kDa), and HA3b (52–53 kDa), 2) the genes coding for NTX (ntx), NTNH (ntnh), and HA (ha) occur as a cluster; ha lies just upstream of ntnh, and ntx lies just downstream of ntnh, 3) ha is in the opposite orientation from that of ntnh and ntx, 4) ha consists of three ORFs (ha1, ha2, and ha3), 5) the gene product (70 kDa) of ha3 is split into HA3a and HA3b ...

Chemiluminescence of neutrophils from patients with Behçet's disease and its correlation with an increased proportion of uncommon serotypes of Streptococcus sanguis in the oral flora.

Zymosan-induced chemiluminescence was investigated in whole blood and in neutrophils: in both, the peak count was frequently elevated in Behçets disease, and was significantly higher than in healthy controls; similarly the peak time was shorter. There were more uncommon serotypes of Streptococcus sanguis in the oral flora of patients with Behçets disease. Common serotypes were present in the flora of healthy controls, but not in patients with the disease. The percentage of Strep. sanguis in the oral flora was significantly correlated with the level of chemiluminescence response. Thus infection with uncommon serotypes of Strep. sanguis may play a role in the aetiology of Behçets disease.

Simple Method for Detection of Clostridium botulinum Type A to F Neurotoxin Genes by Ploymerase Chain Reaction

A polymerase chain reaction (PCR)‐based method was established to detect each type of neurotoxin genes of Clostridium botulinum types A to F by employing the oligonucleotide primer sets corresponding to special regions of the light chains of the neurotoxins. In this procedure, the PCR products were easily confirmed by restriction enzyme digestion profiles, and as little as 2.5 pg of template DNAs from toxigenic strains could be detected. The specific PCR products were obtained from toxigenic C. botulinum types A to F, a type E toxin‐producing C. butyricum strain, and a type F toxin‐producing C. baratii strain, but no PCR product was detected in nontoxigenic strains of C. botulinum and other clostridial species. The neurotoxin genes were also detected in food products of a seasoned dry salmon and a fermented fish (Izushi) which had caused type E outbreaks of botulism. Therefore, it is concluded that this PCR‐based detection method can be used for the rapid diagnosis of botulism.

The role of streptococcal hypersensitivity in the pathogenesis of Behçet’s Disease

Behçets disease (BD) is still considered as a mysterious multisystemic disorder characterized by recurrent involvement of muco-cutaneous, ocular, intestinal, vascular and/or nervous system organs. In this review, we would like to highlight and discuss several important advances in our understanding of the pathogenesis of BD based on the intrinsic genetic factors including HLA-B51 and MICA expression and extrinsic triggering factors. As one of the extrinsic triggering factors, we focused on the hypersensitivity against oral streptococci which might be acquired through the innate immune mechanism. It was found that HLA-B51 restricted CD8 T cell response was clearly correlated with the target tissues expressing MICA*009 by stress in active BD patients with HLA-B51 as the intrinsic factors. Bes-1 gene and HSP-65 derived from oral S. sanguinis, which is the uncommon serotype (KTH-1, strain BD113-20), are supposed to play important roles as an extrinsic factor in BD pathogenesis. The peptides of the Bes-1 gene are highly homologous with the retinal protein Brn3b and moreover, the Bes-1 peptides were homologous with HSP-65 derived from microorganisms in association with the counterpart human HSP-60, which appeared reactively in the patients. HSP-65/60 also has high homologies with the respective T cell epitope of BD patients. Although HSP-65/60 and the peptides of Bes-1 gene were found to stimulate PBMCs from BD patients in the production of pro-inflammatory Th1 type cytokines, some homologous peptides of HSP-65 with T cell epitopes were found to reduce IL-8, IL-12 and TNF-alpha produced from PBMCs of active BD patients. The findings might be correlated with the clinically therapeutic effects for BD patients with severe uveitis, who were led to immunotolerance by the peptide of human HSP-60 (336-351), as previously reported. Then, the pathogenesis of BD was discussed referring to intrinsic genetic factors and extrinsic triggering factors in aspects of streptococcal hypersensitivity, which might be acquired through the innate immune mechanisms. The BD symptoms were thought to be due to vascular reactions as immune responses in correlation with monocyte expressed streptococcal agents.