SUMMARYThe biochemical and biological properties of the flagella of Campylobacterjejuni have been investigated using two variants selected from a flagellate, motile clinical isolate (strain 81116): a flagellate, non-motile variant (SF-1) and an aflagellate variant (SF-2). Phenotypic and biochemical analysis of the strains and amino acid analysis of the isolated flagella suggest that the variants differed from the wild-type strain only in the absence of flagella and/or motility. The aflagellate variant poorly colonized the gastrointestinal tract of infant mice but the flagellate, non-motile variant colonized the mice as successfully as the wild-type strain. 35S-labelled organisms were used to investigate the attachment of the variants to human epithelial cell monolayers in vitro. The flagellate, non-motile strain attached more efficiently to the cells than the wild-type strain or the aflagellate strain. Differences in attachment suggest that an adhesin is intimately associated with flagella of C. jejuni and that active flagella mediate only a tenuous association with host cells. This adhesin attached most efficiently to cells of intestinal epithelial origin and was not specifically inhibited by various sugars.

SUMMARY After the recent successful isolation of spiral organisms from the stomach this paper presents the bacteriological and pathological correlation of gastric antral biopsies from 51 patients endoscopied for upper gastrointestinal symptoms. Campylobacter pyloridis was cultured from 29 patients and seen by either silver staining of the biopsy or scanning electron microscopy in an additional three. The organism was cultured from 23 of the 33 (69%) patients with peptic ulcer disease and from within this group 17 (80%) of the 21 patients with duodenal ulceration. It was cultured only once from the 12 normal biopsies in the series but from 27 of the 38 (71%) biopsies showing gastritis. C pyloridis was also cultured from five out of seven of the 14 endoscopically normal patients, who despite this had biopsy evidence of gastritis. It was the sole organism cultured from 65% of the positive biopsies and scanning electron microscopy invariably revealed it deep to the surface mucus layer. C pyloridis persisted in the three patients with duodenal ulcers after treatment and healing. The findings support the hypothesis that C pyloridis is aetiologically related to gastritis and peptic ulceration though its precise role still remains to be defined.The presence of spiral bacteria on gastric mucosa has been noted by histopathologists for many years. ' Fiesh impetus to these observations and to the search for the aetiology of peptic ulcer disease has been given by the culture of these organisms and the demonstration of their association with gastritis and duodenal ulcer.2-4 Other communications5-7 have upheld these initial findings. The provisional name of Campylobacter pyloridis has been assigned to the new organism.3 8 This paper presents a prospective study on a series of patients with peptic ulcer disease, designed to look at the incidence of this new organism in the stomach and to try and shed light on whether it is a pathogen or not. Methods PATIENTS AND ENDOSCOPY

any symptoms when they were withdrawn, and there were no notable changes in heart rate or blood pressure. Beta-blocker withdrawal produced variable results, but unlike clonidine there was no relation between the dose withdrawn and the increase in heart rates and blood pressures. The reason for this difference must lie in the different pharmacological effects of these drugs, but it is clearly important to know that violent reactions are not likely to attend accidental withdrawal of beta-blocking drugs.The same generalisation can be made with respect to methyldopa, but the doses used were small and the degree of blood pressure control achieved in these patients was not good. None of the recordings showed evidence of postural or exercise hypotension, which are a feature of adequate blood pressure control with this drug, and further studies need to be done in patients taking larger doses whose blood pressure is better controlled, as defined by clinic blood-pressure readings.

Summary. The microbial composition of samples of gastric juice from eight achlorhydric patients was determined by aerobic and rigorously anaerobic culture techniques. Bacteria from 16 genera were commonly isolated, but representatives of only three genera, (streptococci, neisseriae and haemophili) were isolated from every patient. Nitrate and nitrite were both reduced by veillonellae, haemophili, staphylococci, corynebacteria, lactobacilli, flavobacteria and fusobacteria, but the potential rate of nitrate reduction by suspensions of veillonellae, Haemophilus parainjluenzae and members of the Enterobacteriaceae were up to ten times more rapid than the rate of nitrite reduction. Conversely, although all Neisseria spp. reduced nitrite only some strains reduced nitrate. Streptococci did not reduce nitrate. Streptococcus sanguis reduced nitrite when grown with haematin ; other streptococci did not reduce nitrite. Bacterial nitrate and nitrite reduction were active over the pH range 6-8, similar to thepH range of the achlorhydric stomach.From a knowledge of the composition of the bacterial flora and their potential rates of nitrate and nitrite reduction under prevailing conditions, predictions were made about the tendency of nitrite to accumulate during nitrate reduction. Studies of the transient accumulation of nitrite by mixed cultures of H . parainjluenzae and N . subjlava were consistent with these predictions. Haemophili and veillonellae could be responsible for the accumulation of nitrite in the gastric juice of some patients, whereas streptococci and neisseriae would tend to remove nitrite from the stomach as rapidly as it formed.

S U M M A R YThe ability to protect mice against intracerebral infection and to elicit, after one dose, complement-mediated bactericidal antibody capable of killing a mousevirulent phase I strain in vitro, was tested in seven cultures of Bordetellapertussis: three typical phase I strains; two strains grown in the presence of 0.5 mg nicotinic acid/ml ; one phase IV strain ; and the atypical strain 134. The typical strains showed both activities; the nicotinic acid-grown and phase IV strains elicited high antibody titres, but did not confer protection, whereas strain 134 protected, but did not elicit bactericidal antibody.Pyrogenic material extracted from dried organisms by hot phenol and water (lipopolysaccharide) was not antigenic in mice; however, with all strains, except 134, multiple doses of this material coupled to stromata or Escherichiu coli conjugated protein elicited bactericidal and precipitating antisera in mice, although the mice were not protected.Strain 134 contained approximately one quarter of the normal amount of endotoxin, as assayed in actinomycin D-sensitized mice, but was as effective as normal strains as an adjuvant for haemolysin production.